| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/mm/memory.c |
| * |
| * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| */ |
| |
| /* |
| * demand-loading started 01.12.91 - seems it is high on the list of |
| * things wanted, and it should be easy to implement. - Linus |
| */ |
| |
| /* |
| * Ok, demand-loading was easy, shared pages a little bit tricker. Shared |
| * pages started 02.12.91, seems to work. - Linus. |
| * |
| * Tested sharing by executing about 30 /bin/sh: under the old kernel it |
| * would have taken more than the 6M I have free, but it worked well as |
| * far as I could see. |
| * |
| * Also corrected some "invalidate()"s - I wasn't doing enough of them. |
| */ |
| |
| /* |
| * Real VM (paging to/from disk) started 18.12.91. Much more work and |
| * thought has to go into this. Oh, well.. |
| * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. |
| * Found it. Everything seems to work now. |
| * 20.12.91 - Ok, making the swap-device changeable like the root. |
| */ |
| |
| /* |
| * 05.04.94 - Multi-page memory management added for v1.1. |
| * Idea by Alex Bligh (alex@cconcepts.co.uk) |
| * |
| * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG |
| * (Gerhard.Wichert@pdb.siemens.de) |
| * |
| * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) |
| */ |
| |
| #include <linux/kernel_stat.h> |
| #include <linux/mm.h> |
| #include <linux/mm_inline.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/coredump.h> |
| #include <linux/sched/numa_balancing.h> |
| #include <linux/sched/task.h> |
| #include <linux/hugetlb.h> |
| #include <linux/mman.h> |
| #include <linux/swap.h> |
| #include <linux/highmem.h> |
| #include <linux/pagemap.h> |
| #include <linux/memremap.h> |
| #include <linux/ksm.h> |
| #include <linux/rmap.h> |
| #include <linux/export.h> |
| #include <linux/delayacct.h> |
| #include <linux/init.h> |
| #include <linux/pfn_t.h> |
| #include <linux/writeback.h> |
| #include <linux/memcontrol.h> |
| #include <linux/mmu_notifier.h> |
| #include <linux/swapops.h> |
| #include <linux/elf.h> |
| #include <linux/gfp.h> |
| #include <linux/migrate.h> |
| #include <linux/string.h> |
| #include <linux/memory-tiers.h> |
| #include <linux/debugfs.h> |
| #include <linux/userfaultfd_k.h> |
| #include <linux/dax.h> |
| #include <linux/oom.h> |
| #include <linux/numa.h> |
| #include <linux/perf_event.h> |
| #include <linux/ptrace.h> |
| #include <linux/vmalloc.h> |
| #include <linux/sched/sysctl.h> |
| |
| #include <trace/events/kmem.h> |
| |
| #include <asm/io.h> |
| #include <asm/mmu_context.h> |
| #include <asm/pgalloc.h> |
| #include <linux/uaccess.h> |
| #include <asm/tlb.h> |
| #include <asm/tlbflush.h> |
| |
| #include "pgalloc-track.h" |
| #include "internal.h" |
| #include "swap.h" |
| |
| #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST) |
| #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. |
| #endif |
| |
| #ifndef CONFIG_NUMA |
| unsigned long max_mapnr; |
| EXPORT_SYMBOL(max_mapnr); |
| |
| struct page *mem_map; |
| EXPORT_SYMBOL(mem_map); |
| #endif |
| |
| static vm_fault_t do_fault(struct vm_fault *vmf); |
| |
| /* |
| * A number of key systems in x86 including ioremap() rely on the assumption |
| * that high_memory defines the upper bound on direct map memory, then end |
| * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and |
| * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL |
| * and ZONE_HIGHMEM. |
| */ |
| void *high_memory; |
| EXPORT_SYMBOL(high_memory); |
| |
| /* |
| * Randomize the address space (stacks, mmaps, brk, etc.). |
| * |
| * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, |
| * as ancient (libc5 based) binaries can segfault. ) |
| */ |
| int randomize_va_space __read_mostly = |
| #ifdef CONFIG_COMPAT_BRK |
| 1; |
| #else |
| 2; |
| #endif |
| |
| #ifndef arch_wants_old_prefaulted_pte |
| static inline bool arch_wants_old_prefaulted_pte(void) |
| { |
| /* |
| * Transitioning a PTE from 'old' to 'young' can be expensive on |
| * some architectures, even if it's performed in hardware. By |
| * default, "false" means prefaulted entries will be 'young'. |
| */ |
| return false; |
| } |
| #endif |
| |
| static int __init disable_randmaps(char *s) |
| { |
| randomize_va_space = 0; |
| return 1; |
| } |
| __setup("norandmaps", disable_randmaps); |
| |
| unsigned long zero_pfn __read_mostly; |
| EXPORT_SYMBOL(zero_pfn); |
| |
| unsigned long highest_memmap_pfn __read_mostly; |
| |
| /* |
| * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() |
| */ |
| static int __init init_zero_pfn(void) |
| { |
| zero_pfn = page_to_pfn(ZERO_PAGE(0)); |
| return 0; |
| } |
| early_initcall(init_zero_pfn); |
| |
| void mm_trace_rss_stat(struct mm_struct *mm, int member, long count) |
| { |
| trace_rss_stat(mm, member, count); |
| } |
| |
| #if defined(SPLIT_RSS_COUNTING) |
| |
| void sync_mm_rss(struct mm_struct *mm) |
| { |
| int i; |
| |
| for (i = 0; i < NR_MM_COUNTERS; i++) { |
| if (current->rss_stat.count[i]) { |
| add_mm_counter(mm, i, current->rss_stat.count[i]); |
| current->rss_stat.count[i] = 0; |
| } |
| } |
| current->rss_stat.events = 0; |
| } |
| |
| static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) |
| { |
| struct task_struct *task = current; |
| |
| if (likely(task->mm == mm)) |
| task->rss_stat.count[member] += val; |
| else |
| add_mm_counter(mm, member, val); |
| } |
| #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) |
| #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) |
| |
| /* sync counter once per 64 page faults */ |
| #define TASK_RSS_EVENTS_THRESH (64) |
| static void check_sync_rss_stat(struct task_struct *task) |
| { |
| if (unlikely(task != current)) |
| return; |
| if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) |
| sync_mm_rss(task->mm); |
| } |
| #else /* SPLIT_RSS_COUNTING */ |
| |
| #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) |
| #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) |
| |
| static void check_sync_rss_stat(struct task_struct *task) |
| { |
| } |
| |
| #endif /* SPLIT_RSS_COUNTING */ |
| |
| /* |
| * Note: this doesn't free the actual pages themselves. That |
| * has been handled earlier when unmapping all the memory regions. |
| */ |
| static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, |
| unsigned long addr) |
| { |
| pgtable_t token = pmd_pgtable(*pmd); |
| pmd_clear(pmd); |
| pte_free_tlb(tlb, token, addr); |
| mm_dec_nr_ptes(tlb->mm); |
| } |
| |
| static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| unsigned long start; |
| |
| start = addr; |
| pmd = pmd_offset(pud, addr); |
| do { |
| next = pmd_addr_end(addr, end); |
| if (pmd_none_or_clear_bad(pmd)) |
| continue; |
| free_pte_range(tlb, pmd, addr); |
| } while (pmd++, addr = next, addr != end); |
| |
| start &= PUD_MASK; |
| if (start < floor) |
| return; |
| if (ceiling) { |
| ceiling &= PUD_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| return; |
| |
| pmd = pmd_offset(pud, start); |
| pud_clear(pud); |
| pmd_free_tlb(tlb, pmd, start); |
| mm_dec_nr_pmds(tlb->mm); |
| } |
| |
| static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| pud_t *pud; |
| unsigned long next; |
| unsigned long start; |
| |
| start = addr; |
| pud = pud_offset(p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_none_or_clear_bad(pud)) |
| continue; |
| free_pmd_range(tlb, pud, addr, next, floor, ceiling); |
| } while (pud++, addr = next, addr != end); |
| |
| start &= P4D_MASK; |
| if (start < floor) |
| return; |
| if (ceiling) { |
| ceiling &= P4D_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| return; |
| |
| pud = pud_offset(p4d, start); |
| p4d_clear(p4d); |
| pud_free_tlb(tlb, pud, start); |
| mm_dec_nr_puds(tlb->mm); |
| } |
| |
| static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| unsigned long start; |
| |
| start = addr; |
| p4d = p4d_offset(pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(p4d)) |
| continue; |
| free_pud_range(tlb, p4d, addr, next, floor, ceiling); |
| } while (p4d++, addr = next, addr != end); |
| |
| start &= PGDIR_MASK; |
| if (start < floor) |
| return; |
| if (ceiling) { |
| ceiling &= PGDIR_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| return; |
| |
| p4d = p4d_offset(pgd, start); |
| pgd_clear(pgd); |
| p4d_free_tlb(tlb, p4d, start); |
| } |
| |
| /* |
| * This function frees user-level page tables of a process. |
| */ |
| void free_pgd_range(struct mmu_gather *tlb, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| pgd_t *pgd; |
| unsigned long next; |
| |
| /* |
| * The next few lines have given us lots of grief... |
| * |
| * Why are we testing PMD* at this top level? Because often |
| * there will be no work to do at all, and we'd prefer not to |
| * go all the way down to the bottom just to discover that. |
| * |
| * Why all these "- 1"s? Because 0 represents both the bottom |
| * of the address space and the top of it (using -1 for the |
| * top wouldn't help much: the masks would do the wrong thing). |
| * The rule is that addr 0 and floor 0 refer to the bottom of |
| * the address space, but end 0 and ceiling 0 refer to the top |
| * Comparisons need to use "end - 1" and "ceiling - 1" (though |
| * that end 0 case should be mythical). |
| * |
| * Wherever addr is brought up or ceiling brought down, we must |
| * be careful to reject "the opposite 0" before it confuses the |
| * subsequent tests. But what about where end is brought down |
| * by PMD_SIZE below? no, end can't go down to 0 there. |
| * |
| * Whereas we round start (addr) and ceiling down, by different |
| * masks at different levels, in order to test whether a table |
| * now has no other vmas using it, so can be freed, we don't |
| * bother to round floor or end up - the tests don't need that. |
| */ |
| |
| addr &= PMD_MASK; |
| if (addr < floor) { |
| addr += PMD_SIZE; |
| if (!addr) |
| return; |
| } |
| if (ceiling) { |
| ceiling &= PMD_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| end -= PMD_SIZE; |
| if (addr > end - 1) |
| return; |
| /* |
| * We add page table cache pages with PAGE_SIZE, |
| * (see pte_free_tlb()), flush the tlb if we need |
| */ |
| tlb_change_page_size(tlb, PAGE_SIZE); |
| pgd = pgd_offset(tlb->mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(pgd)) |
| continue; |
| free_p4d_range(tlb, pgd, addr, next, floor, ceiling); |
| } while (pgd++, addr = next, addr != end); |
| } |
| |
| void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt, |
| struct vm_area_struct *vma, unsigned long floor, |
| unsigned long ceiling) |
| { |
| MA_STATE(mas, mt, vma->vm_end, vma->vm_end); |
| |
| do { |
| unsigned long addr = vma->vm_start; |
| struct vm_area_struct *next; |
| |
| /* |
| * Note: USER_PGTABLES_CEILING may be passed as ceiling and may |
| * be 0. This will underflow and is okay. |
| */ |
| next = mas_find(&mas, ceiling - 1); |
| |
| /* |
| * Hide vma from rmap and truncate_pagecache before freeing |
| * pgtables |
| */ |
| unlink_anon_vmas(vma); |
| unlink_file_vma(vma); |
| |
| if (is_vm_hugetlb_page(vma)) { |
| hugetlb_free_pgd_range(tlb, addr, vma->vm_end, |
| floor, next ? next->vm_start : ceiling); |
| } else { |
| /* |
| * Optimization: gather nearby vmas into one call down |
| */ |
| while (next && next->vm_start <= vma->vm_end + PMD_SIZE |
| && !is_vm_hugetlb_page(next)) { |
| vma = next; |
| next = mas_find(&mas, ceiling - 1); |
| unlink_anon_vmas(vma); |
| unlink_file_vma(vma); |
| } |
| free_pgd_range(tlb, addr, vma->vm_end, |
| floor, next ? next->vm_start : ceiling); |
| } |
| vma = next; |
| } while (vma); |
| } |
| |
| void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte) |
| { |
| spinlock_t *ptl = pmd_lock(mm, pmd); |
| |
| if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
| mm_inc_nr_ptes(mm); |
| /* |
| * Ensure all pte setup (eg. pte page lock and page clearing) are |
| * visible before the pte is made visible to other CPUs by being |
| * put into page tables. |
| * |
| * The other side of the story is the pointer chasing in the page |
| * table walking code (when walking the page table without locking; |
| * ie. most of the time). Fortunately, these data accesses consist |
| * of a chain of data-dependent loads, meaning most CPUs (alpha |
| * being the notable exception) will already guarantee loads are |
| * seen in-order. See the alpha page table accessors for the |
| * smp_rmb() barriers in page table walking code. |
| */ |
| smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ |
| pmd_populate(mm, pmd, *pte); |
| *pte = NULL; |
| } |
| spin_unlock(ptl); |
| } |
| |
| int __pte_alloc(struct mm_struct *mm, pmd_t *pmd) |
| { |
| pgtable_t new = pte_alloc_one(mm); |
| if (!new) |
| return -ENOMEM; |
| |
| pmd_install(mm, pmd, &new); |
| if (new) |
| pte_free(mm, new); |
| return 0; |
| } |
| |
| int __pte_alloc_kernel(pmd_t *pmd) |
| { |
| pte_t *new = pte_alloc_one_kernel(&init_mm); |
| if (!new) |
| return -ENOMEM; |
| |
| spin_lock(&init_mm.page_table_lock); |
| if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
| smp_wmb(); /* See comment in pmd_install() */ |
| pmd_populate_kernel(&init_mm, pmd, new); |
| new = NULL; |
| } |
| spin_unlock(&init_mm.page_table_lock); |
| if (new) |
| pte_free_kernel(&init_mm, new); |
| return 0; |
| } |
| |
| static inline void init_rss_vec(int *rss) |
| { |
| memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); |
| } |
| |
| static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) |
| { |
| int i; |
| |
| if (current->mm == mm) |
| sync_mm_rss(mm); |
| for (i = 0; i < NR_MM_COUNTERS; i++) |
| if (rss[i]) |
| add_mm_counter(mm, i, rss[i]); |
| } |
| |
| /* |
| * This function is called to print an error when a bad pte |
| * is found. For example, we might have a PFN-mapped pte in |
| * a region that doesn't allow it. |
| * |
| * The calling function must still handle the error. |
| */ |
| static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, |
| pte_t pte, struct page *page) |
| { |
| pgd_t *pgd = pgd_offset(vma->vm_mm, addr); |
| p4d_t *p4d = p4d_offset(pgd, addr); |
| pud_t *pud = pud_offset(p4d, addr); |
| pmd_t *pmd = pmd_offset(pud, addr); |
| struct address_space *mapping; |
| pgoff_t index; |
| static unsigned long resume; |
| static unsigned long nr_shown; |
| static unsigned long nr_unshown; |
| |
| /* |
| * Allow a burst of 60 reports, then keep quiet for that minute; |
| * or allow a steady drip of one report per second. |
| */ |
| if (nr_shown == 60) { |
| if (time_before(jiffies, resume)) { |
| nr_unshown++; |
| return; |
| } |
| if (nr_unshown) { |
| pr_alert("BUG: Bad page map: %lu messages suppressed\n", |
| nr_unshown); |
| nr_unshown = 0; |
| } |
| nr_shown = 0; |
| } |
| if (nr_shown++ == 0) |
| resume = jiffies + 60 * HZ; |
| |
| mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; |
| index = linear_page_index(vma, addr); |
| |
| pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", |
| current->comm, |
| (long long)pte_val(pte), (long long)pmd_val(*pmd)); |
| if (page) |
| dump_page(page, "bad pte"); |
| pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n", |
| (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); |
| pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n", |
| vma->vm_file, |
| vma->vm_ops ? vma->vm_ops->fault : NULL, |
| vma->vm_file ? vma->vm_file->f_op->mmap : NULL, |
| mapping ? mapping->a_ops->read_folio : NULL); |
| dump_stack(); |
| add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
| } |
| |
| /* |
| * vm_normal_page -- This function gets the "struct page" associated with a pte. |
| * |
| * "Special" mappings do not wish to be associated with a "struct page" (either |
| * it doesn't exist, or it exists but they don't want to touch it). In this |
| * case, NULL is returned here. "Normal" mappings do have a struct page. |
| * |
| * There are 2 broad cases. Firstly, an architecture may define a pte_special() |
| * pte bit, in which case this function is trivial. Secondly, an architecture |
| * may not have a spare pte bit, which requires a more complicated scheme, |
| * described below. |
| * |
| * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a |
| * special mapping (even if there are underlying and valid "struct pages"). |
| * COWed pages of a VM_PFNMAP are always normal. |
| * |
| * The way we recognize COWed pages within VM_PFNMAP mappings is through the |
| * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit |
| * set, and the vm_pgoff will point to the first PFN mapped: thus every special |
| * mapping will always honor the rule |
| * |
| * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) |
| * |
| * And for normal mappings this is false. |
| * |
| * This restricts such mappings to be a linear translation from virtual address |
| * to pfn. To get around this restriction, we allow arbitrary mappings so long |
| * as the vma is not a COW mapping; in that case, we know that all ptes are |
| * special (because none can have been COWed). |
| * |
| * |
| * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. |
| * |
| * VM_MIXEDMAP mappings can likewise contain memory with or without "struct |
| * page" backing, however the difference is that _all_ pages with a struct |
| * page (that is, those where pfn_valid is true) are refcounted and considered |
| * normal pages by the VM. The disadvantage is that pages are refcounted |
| * (which can be slower and simply not an option for some PFNMAP users). The |
| * advantage is that we don't have to follow the strict linearity rule of |
| * PFNMAP mappings in order to support COWable mappings. |
| * |
| */ |
| struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, |
| pte_t pte) |
| { |
| unsigned long pfn = pte_pfn(pte); |
| |
| if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { |
| if (likely(!pte_special(pte))) |
| goto check_pfn; |
| if (vma->vm_ops && vma->vm_ops->find_special_page) |
| return vma->vm_ops->find_special_page(vma, addr); |
| if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
| return NULL; |
| if (is_zero_pfn(pfn)) |
| return NULL; |
| if (pte_devmap(pte)) |
| /* |
| * NOTE: New users of ZONE_DEVICE will not set pte_devmap() |
| * and will have refcounts incremented on their struct pages |
| * when they are inserted into PTEs, thus they are safe to |
| * return here. Legacy ZONE_DEVICE pages that set pte_devmap() |
| * do not have refcounts. Example of legacy ZONE_DEVICE is |
| * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers. |
| */ |
| return NULL; |
| |
| print_bad_pte(vma, addr, pte, NULL); |
| return NULL; |
| } |
| |
| /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ |
| |
| if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
| if (vma->vm_flags & VM_MIXEDMAP) { |
| if (!pfn_valid(pfn)) |
| return NULL; |
| goto out; |
| } else { |
| unsigned long off; |
| off = (addr - vma->vm_start) >> PAGE_SHIFT; |
| if (pfn == vma->vm_pgoff + off) |
| return NULL; |
| if (!is_cow_mapping(vma->vm_flags)) |
| return NULL; |
| } |
| } |
| |
| if (is_zero_pfn(pfn)) |
| return NULL; |
| |
| check_pfn: |
| if (unlikely(pfn > highest_memmap_pfn)) { |
| print_bad_pte(vma, addr, pte, NULL); |
| return NULL; |
| } |
| |
| /* |
| * NOTE! We still have PageReserved() pages in the page tables. |
| * eg. VDSO mappings can cause them to exist. |
| */ |
| out: |
| return pfn_to_page(pfn); |
| } |
| |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, |
| pmd_t pmd) |
| { |
| unsigned long pfn = pmd_pfn(pmd); |
| |
| /* |
| * There is no pmd_special() but there may be special pmds, e.g. |
| * in a direct-access (dax) mapping, so let's just replicate the |
| * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here. |
| */ |
| if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
| if (vma->vm_flags & VM_MIXEDMAP) { |
| if (!pfn_valid(pfn)) |
| return NULL; |
| goto out; |
| } else { |
| unsigned long off; |
| off = (addr - vma->vm_start) >> PAGE_SHIFT; |
| if (pfn == vma->vm_pgoff + off) |
| return NULL; |
| if (!is_cow_mapping(vma->vm_flags)) |
| return NULL; |
| } |
| } |
| |
| if (pmd_devmap(pmd)) |
| return NULL; |
| if (is_huge_zero_pmd(pmd)) |
| return NULL; |
| if (unlikely(pfn > highest_memmap_pfn)) |
| return NULL; |
| |
| /* |
| * NOTE! We still have PageReserved() pages in the page tables. |
| * eg. VDSO mappings can cause them to exist. |
| */ |
| out: |
| return pfn_to_page(pfn); |
| } |
| #endif |
| |
| static void restore_exclusive_pte(struct vm_area_struct *vma, |
| struct page *page, unsigned long address, |
| pte_t *ptep) |
| { |
| pte_t pte; |
| swp_entry_t entry; |
| |
| pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); |
| if (pte_swp_soft_dirty(*ptep)) |
| pte = pte_mksoft_dirty(pte); |
| |
| entry = pte_to_swp_entry(*ptep); |
| if (pte_swp_uffd_wp(*ptep)) |
| pte = pte_mkuffd_wp(pte); |
| else if (is_writable_device_exclusive_entry(entry)) |
| pte = maybe_mkwrite(pte_mkdirty(pte), vma); |
| |
| VM_BUG_ON(pte_write(pte) && !(PageAnon(page) && PageAnonExclusive(page))); |
| |
| /* |
| * No need to take a page reference as one was already |
| * created when the swap entry was made. |
| */ |
| if (PageAnon(page)) |
| page_add_anon_rmap(page, vma, address, RMAP_NONE); |
| else |
| /* |
| * Currently device exclusive access only supports anonymous |
| * memory so the entry shouldn't point to a filebacked page. |
| */ |
| WARN_ON_ONCE(1); |
| |
| set_pte_at(vma->vm_mm, address, ptep, pte); |
| |
| /* |
| * No need to invalidate - it was non-present before. However |
| * secondary CPUs may have mappings that need invalidating. |
| */ |
| update_mmu_cache(vma, address, ptep); |
| } |
| |
| /* |
| * Tries to restore an exclusive pte if the page lock can be acquired without |
| * sleeping. |
| */ |
| static int |
| try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma, |
| unsigned long addr) |
| { |
| swp_entry_t entry = pte_to_swp_entry(*src_pte); |
| struct page *page = pfn_swap_entry_to_page(entry); |
| |
| if (trylock_page(page)) { |
| restore_exclusive_pte(vma, page, addr, src_pte); |
| unlock_page(page); |
| return 0; |
| } |
| |
| return -EBUSY; |
| } |
| |
| /* |
| * copy one vm_area from one task to the other. Assumes the page tables |
| * already present in the new task to be cleared in the whole range |
| * covered by this vma. |
| */ |
| |
| static unsigned long |
| copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma, |
| struct vm_area_struct *src_vma, unsigned long addr, int *rss) |
| { |
| unsigned long vm_flags = dst_vma->vm_flags; |
| pte_t pte = *src_pte; |
| struct page *page; |
| swp_entry_t entry = pte_to_swp_entry(pte); |
| |
| if (likely(!non_swap_entry(entry))) { |
| if (swap_duplicate(entry) < 0) |
| return -EIO; |
| |
| /* make sure dst_mm is on swapoff's mmlist. */ |
| if (unlikely(list_empty(&dst_mm->mmlist))) { |
| spin_lock(&mmlist_lock); |
| if (list_empty(&dst_mm->mmlist)) |
| list_add(&dst_mm->mmlist, |
| &src_mm->mmlist); |
| spin_unlock(&mmlist_lock); |
| } |
| /* Mark the swap entry as shared. */ |
| if (pte_swp_exclusive(*src_pte)) { |
| pte = pte_swp_clear_exclusive(*src_pte); |
| set_pte_at(src_mm, addr, src_pte, pte); |
| } |
| rss[MM_SWAPENTS]++; |
| } else if (is_migration_entry(entry)) { |
| page = pfn_swap_entry_to_page(entry); |
| |
| rss[mm_counter(page)]++; |
| |
| if (!is_readable_migration_entry(entry) && |
| is_cow_mapping(vm_flags)) { |
| /* |
| * COW mappings require pages in both parent and child |
| * to be set to read. A previously exclusive entry is |
| * now shared. |
| */ |
| entry = make_readable_migration_entry( |
| swp_offset(entry)); |
| pte = swp_entry_to_pte(entry); |
| if (pte_swp_soft_dirty(*src_pte)) |
| pte = pte_swp_mksoft_dirty(pte); |
| if (pte_swp_uffd_wp(*src_pte)) |
| pte = pte_swp_mkuffd_wp(pte); |
| set_pte_at(src_mm, addr, src_pte, pte); |
| } |
| } else if (is_device_private_entry(entry)) { |
| page = pfn_swap_entry_to_page(entry); |
| |
| /* |
| * Update rss count even for unaddressable pages, as |
| * they should treated just like normal pages in this |
| * respect. |
| * |
| * We will likely want to have some new rss counters |
| * for unaddressable pages, at some point. But for now |
| * keep things as they are. |
| */ |
| get_page(page); |
| rss[mm_counter(page)]++; |
| /* Cannot fail as these pages cannot get pinned. */ |
| BUG_ON(page_try_dup_anon_rmap(page, false, src_vma)); |
| |
| /* |
| * We do not preserve soft-dirty information, because so |
| * far, checkpoint/restore is the only feature that |
| * requires that. And checkpoint/restore does not work |
| * when a device driver is involved (you cannot easily |
| * save and restore device driver state). |
| */ |
| if (is_writable_device_private_entry(entry) && |
| is_cow_mapping(vm_flags)) { |
| entry = make_readable_device_private_entry( |
| swp_offset(entry)); |
| pte = swp_entry_to_pte(entry); |
| if (pte_swp_uffd_wp(*src_pte)) |
| pte = pte_swp_mkuffd_wp(pte); |
| set_pte_at(src_mm, addr, src_pte, pte); |
| } |
| } else if (is_device_exclusive_entry(entry)) { |
| /* |
| * Make device exclusive entries present by restoring the |
| * original entry then copying as for a present pte. Device |
| * exclusive entries currently only support private writable |
| * (ie. COW) mappings. |
| */ |
| VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); |
| if (try_restore_exclusive_pte(src_pte, src_vma, addr)) |
| return -EBUSY; |
| return -ENOENT; |
| } else if (is_pte_marker_entry(entry)) { |
| /* |
| * We're copying the pgtable should only because dst_vma has |
| * uffd-wp enabled, do sanity check. |
| */ |
| WARN_ON_ONCE(!userfaultfd_wp(dst_vma)); |
| set_pte_at(dst_mm, addr, dst_pte, pte); |
| return 0; |
| } |
| if (!userfaultfd_wp(dst_vma)) |
| pte = pte_swp_clear_uffd_wp(pte); |
| set_pte_at(dst_mm, addr, dst_pte, pte); |
| return 0; |
| } |
| |
| /* |
| * Copy a present and normal page. |
| * |
| * NOTE! The usual case is that this isn't required; |
| * instead, the caller can just increase the page refcount |
| * and re-use the pte the traditional way. |
| * |
| * And if we need a pre-allocated page but don't yet have |
| * one, return a negative error to let the preallocation |
| * code know so that it can do so outside the page table |
| * lock. |
| */ |
| static inline int |
| copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, |
| struct page **prealloc, struct page *page) |
| { |
| struct page *new_page; |
| pte_t pte; |
| |
| new_page = *prealloc; |
| if (!new_page) |
| return -EAGAIN; |
| |
| /* |
| * We have a prealloc page, all good! Take it |
| * over and copy the page & arm it. |
| */ |
| *prealloc = NULL; |
| copy_user_highpage(new_page, page, addr, src_vma); |
| __SetPageUptodate(new_page); |
| page_add_new_anon_rmap(new_page, dst_vma, addr); |
| lru_cache_add_inactive_or_unevictable(new_page, dst_vma); |
| rss[mm_counter(new_page)]++; |
| |
| /* All done, just insert the new page copy in the child */ |
| pte = mk_pte(new_page, dst_vma->vm_page_prot); |
| pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma); |
| if (userfaultfd_pte_wp(dst_vma, *src_pte)) |
| /* Uffd-wp needs to be delivered to dest pte as well */ |
| pte = pte_wrprotect(pte_mkuffd_wp(pte)); |
| set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); |
| return 0; |
| } |
| |
| /* |
| * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page |
| * is required to copy this pte. |
| */ |
| static inline int |
| copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, |
| struct page **prealloc) |
| { |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| unsigned long vm_flags = src_vma->vm_flags; |
| pte_t pte = *src_pte; |
| struct page *page; |
| |
| page = vm_normal_page(src_vma, addr, pte); |
| if (page && PageAnon(page)) { |
| /* |
| * If this page may have been pinned by the parent process, |
| * copy the page immediately for the child so that we'll always |
| * guarantee the pinned page won't be randomly replaced in the |
| * future. |
| */ |
| get_page(page); |
| if (unlikely(page_try_dup_anon_rmap(page, false, src_vma))) { |
| /* Page maybe pinned, we have to copy. */ |
| put_page(page); |
| return copy_present_page(dst_vma, src_vma, dst_pte, src_pte, |
| addr, rss, prealloc, page); |
| } |
| rss[mm_counter(page)]++; |
| } else if (page) { |
| get_page(page); |
| page_dup_file_rmap(page, false); |
| rss[mm_counter(page)]++; |
| } |
| |
| /* |
| * If it's a COW mapping, write protect it both |
| * in the parent and the child |
| */ |
| if (is_cow_mapping(vm_flags) && pte_write(pte)) { |
| ptep_set_wrprotect(src_mm, addr, src_pte); |
| pte = pte_wrprotect(pte); |
| } |
| VM_BUG_ON(page && PageAnon(page) && PageAnonExclusive(page)); |
| |
| /* |
| * If it's a shared mapping, mark it clean in |
| * the child |
| */ |
| if (vm_flags & VM_SHARED) |
| pte = pte_mkclean(pte); |
| pte = pte_mkold(pte); |
| |
| if (!userfaultfd_wp(dst_vma)) |
| pte = pte_clear_uffd_wp(pte); |
| |
| set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); |
| return 0; |
| } |
| |
| static inline struct page * |
| page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma, |
| unsigned long addr) |
| { |
| struct page *new_page; |
| |
| new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr); |
| if (!new_page) |
| return NULL; |
| |
| if (mem_cgroup_charge(page_folio(new_page), src_mm, GFP_KERNEL)) { |
| put_page(new_page); |
| return NULL; |
| } |
| cgroup_throttle_swaprate(new_page, GFP_KERNEL); |
| |
| return new_page; |
| } |
| |
| static int |
| copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| pte_t *orig_src_pte, *orig_dst_pte; |
| pte_t *src_pte, *dst_pte; |
| spinlock_t *src_ptl, *dst_ptl; |
| int progress, ret = 0; |
| int rss[NR_MM_COUNTERS]; |
| swp_entry_t entry = (swp_entry_t){0}; |
| struct page *prealloc = NULL; |
| |
| again: |
| progress = 0; |
| init_rss_vec(rss); |
| |
| dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); |
| if (!dst_pte) { |
| ret = -ENOMEM; |
| goto out; |
| } |
| src_pte = pte_offset_map(src_pmd, addr); |
| src_ptl = pte_lockptr(src_mm, src_pmd); |
| spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
| orig_src_pte = src_pte; |
| orig_dst_pte = dst_pte; |
| arch_enter_lazy_mmu_mode(); |
| |
| do { |
| /* |
| * We are holding two locks at this point - either of them |
| * could generate latencies in another task on another CPU. |
| */ |
| if (progress >= 32) { |
| progress = 0; |
| if (need_resched() || |
| spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) |
| break; |
| } |
| if (pte_none(*src_pte)) { |
| progress++; |
| continue; |
| } |
| if (unlikely(!pte_present(*src_pte))) { |
| ret = copy_nonpresent_pte(dst_mm, src_mm, |
| dst_pte, src_pte, |
| dst_vma, src_vma, |
| addr, rss); |
| if (ret == -EIO) { |
| entry = pte_to_swp_entry(*src_pte); |
| break; |
| } else if (ret == -EBUSY) { |
| break; |
| } else if (!ret) { |
| progress += 8; |
| continue; |
| } |
| |
| /* |
| * Device exclusive entry restored, continue by copying |
| * the now present pte. |
| */ |
| WARN_ON_ONCE(ret != -ENOENT); |
| } |
| /* copy_present_pte() will clear `*prealloc' if consumed */ |
| ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte, |
| addr, rss, &prealloc); |
| /* |
| * If we need a pre-allocated page for this pte, drop the |
| * locks, allocate, and try again. |
| */ |
| if (unlikely(ret == -EAGAIN)) |
| break; |
| if (unlikely(prealloc)) { |
| /* |
| * pre-alloc page cannot be reused by next time so as |
| * to strictly follow mempolicy (e.g., alloc_page_vma() |
| * will allocate page according to address). This |
| * could only happen if one pinned pte changed. |
| */ |
| put_page(prealloc); |
| prealloc = NULL; |
| } |
| progress += 8; |
| } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); |
| |
| arch_leave_lazy_mmu_mode(); |
| spin_unlock(src_ptl); |
| pte_unmap(orig_src_pte); |
| add_mm_rss_vec(dst_mm, rss); |
| pte_unmap_unlock(orig_dst_pte, dst_ptl); |
| cond_resched(); |
| |
| if (ret == -EIO) { |
| VM_WARN_ON_ONCE(!entry.val); |
| if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) { |
| ret = -ENOMEM; |
| goto out; |
| } |
| entry.val = 0; |
| } else if (ret == -EBUSY) { |
| goto out; |
| } else if (ret == -EAGAIN) { |
| prealloc = page_copy_prealloc(src_mm, src_vma, addr); |
| if (!prealloc) |
| return -ENOMEM; |
| } else if (ret) { |
| VM_WARN_ON_ONCE(1); |
| } |
| |
| /* We've captured and resolved the error. Reset, try again. */ |
| ret = 0; |
| |
| if (addr != end) |
| goto again; |
| out: |
| if (unlikely(prealloc)) |
| put_page(prealloc); |
| return ret; |
| } |
| |
| static inline int |
| copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pud_t *dst_pud, pud_t *src_pud, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| pmd_t *src_pmd, *dst_pmd; |
| unsigned long next; |
| |
| dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); |
| if (!dst_pmd) |
| return -ENOMEM; |
| src_pmd = pmd_offset(src_pud, addr); |
| do { |
| next = pmd_addr_end(addr, end); |
| if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd) |
| || pmd_devmap(*src_pmd)) { |
| int err; |
| VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma); |
| err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd, |
| addr, dst_vma, src_vma); |
| if (err == -ENOMEM) |
| return -ENOMEM; |
| if (!err) |
| continue; |
| /* fall through */ |
| } |
| if (pmd_none_or_clear_bad(src_pmd)) |
| continue; |
| if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd, |
| addr, next)) |
| return -ENOMEM; |
| } while (dst_pmd++, src_pmd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int |
| copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| pud_t *src_pud, *dst_pud; |
| unsigned long next; |
| |
| dst_pud = pud_alloc(dst_mm, dst_p4d, addr); |
| if (!dst_pud) |
| return -ENOMEM; |
| src_pud = pud_offset(src_p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) { |
| int err; |
| |
| VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma); |
| err = copy_huge_pud(dst_mm, src_mm, |
| dst_pud, src_pud, addr, src_vma); |
| if (err == -ENOMEM) |
| return -ENOMEM; |
| if (!err) |
| continue; |
| /* fall through */ |
| } |
| if (pud_none_or_clear_bad(src_pud)) |
| continue; |
| if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud, |
| addr, next)) |
| return -ENOMEM; |
| } while (dst_pud++, src_pud++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int |
| copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| p4d_t *src_p4d, *dst_p4d; |
| unsigned long next; |
| |
| dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr); |
| if (!dst_p4d) |
| return -ENOMEM; |
| src_p4d = p4d_offset(src_pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(src_p4d)) |
| continue; |
| if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d, |
| addr, next)) |
| return -ENOMEM; |
| } while (dst_p4d++, src_p4d++, addr = next, addr != end); |
| return 0; |
| } |
| |
| /* |
| * Return true if the vma needs to copy the pgtable during this fork(). Return |
| * false when we can speed up fork() by allowing lazy page faults later until |
| * when the child accesses the memory range. |
| */ |
| static bool |
| vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) |
| { |
| /* |
| * Always copy pgtables when dst_vma has uffd-wp enabled even if it's |
| * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable |
| * contains uffd-wp protection information, that's something we can't |
| * retrieve from page cache, and skip copying will lose those info. |
| */ |
| if (userfaultfd_wp(dst_vma)) |
| return true; |
| |
| if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
| return true; |
| |
| if (src_vma->anon_vma) |
| return true; |
| |
| /* |
| * Don't copy ptes where a page fault will fill them correctly. Fork |
| * becomes much lighter when there are big shared or private readonly |
| * mappings. The tradeoff is that copy_page_range is more efficient |
| * than faulting. |
| */ |
| return false; |
| } |
| |
| int |
| copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) |
| { |
| pgd_t *src_pgd, *dst_pgd; |
| unsigned long next; |
| unsigned long addr = src_vma->vm_start; |
| unsigned long end = src_vma->vm_end; |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| struct mmu_notifier_range range; |
| bool is_cow; |
| int ret; |
| |
| if (!vma_needs_copy(dst_vma, src_vma)) |
| return 0; |
| |
| if (is_vm_hugetlb_page(src_vma)) |
| return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma); |
| |
| if (unlikely(src_vma->vm_flags & VM_PFNMAP)) { |
| /* |
| * We do not free on error cases below as remove_vma |
| * gets called on error from higher level routine |
| */ |
| ret = track_pfn_copy(src_vma); |
| if (ret) |
| return ret; |
| } |
| |
| /* |
| * We need to invalidate the secondary MMU mappings only when |
| * there could be a permission downgrade on the ptes of the |
| * parent mm. And a permission downgrade will only happen if |
| * is_cow_mapping() returns true. |
| */ |
| is_cow = is_cow_mapping(src_vma->vm_flags); |
| |
| if (is_cow) { |
| mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, |
| 0, src_vma, src_mm, addr, end); |
| mmu_notifier_invalidate_range_start(&range); |
| /* |
| * Disabling preemption is not needed for the write side, as |
| * the read side doesn't spin, but goes to the mmap_lock. |
| * |
| * Use the raw variant of the seqcount_t write API to avoid |
| * lockdep complaining about preemptibility. |
| */ |
| mmap_assert_write_locked(src_mm); |
| raw_write_seqcount_begin(&src_mm->write_protect_seq); |
| } |
| |
| ret = 0; |
| dst_pgd = pgd_offset(dst_mm, addr); |
| src_pgd = pgd_offset(src_mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(src_pgd)) |
| continue; |
| if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd, |
| addr, next))) { |
| ret = -ENOMEM; |
| break; |
| } |
| } while (dst_pgd++, src_pgd++, addr = next, addr != end); |
| |
| if (is_cow) { |
| raw_write_seqcount_end(&src_mm->write_protect_seq); |
| mmu_notifier_invalidate_range_end(&range); |
| } |
| return ret; |
| } |
| |
| /* |
| * Parameter block passed down to zap_pte_range in exceptional cases. |
| */ |
| struct zap_details { |
| struct folio *single_folio; /* Locked folio to be unmapped */ |
| bool even_cows; /* Zap COWed private pages too? */ |
| zap_flags_t zap_flags; /* Extra flags for zapping */ |
| }; |
| |
| /* Whether we should zap all COWed (private) pages too */ |
| static inline bool should_zap_cows(struct zap_details *details) |
| { |
| /* By default, zap all pages */ |
| if (!details) |
| return true; |
| |
| /* Or, we zap COWed pages only if the caller wants to */ |
| return details->even_cows; |
| } |
| |
| /* Decides whether we should zap this page with the page pointer specified */ |
| static inline bool should_zap_page(struct zap_details *details, struct page *page) |
| { |
| /* If we can make a decision without *page.. */ |
| if (should_zap_cows(details)) |
| return true; |
| |
| /* E.g. the caller passes NULL for the case of a zero page */ |
| if (!page) |
| return true; |
| |
| /* Otherwise we should only zap non-anon pages */ |
| return !PageAnon(page); |
| } |
| |
| static inline bool zap_drop_file_uffd_wp(struct zap_details *details) |
| { |
| if (!details) |
| return false; |
| |
| return details->zap_flags & ZAP_FLAG_DROP_MARKER; |
| } |
| |
| /* |
| * This function makes sure that we'll replace the none pte with an uffd-wp |
| * swap special pte marker when necessary. Must be with the pgtable lock held. |
| */ |
| static inline void |
| zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, |
| unsigned long addr, pte_t *pte, |
| struct zap_details *details, pte_t pteval) |
| { |
| if (zap_drop_file_uffd_wp(details)) |
| return; |
| |
| pte_install_uffd_wp_if_needed(vma, addr, pte, pteval); |
| } |
| |
| static unsigned long zap_pte_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| struct mm_struct *mm = tlb->mm; |
| int force_flush = 0; |
| int rss[NR_MM_COUNTERS]; |
| spinlock_t *ptl; |
| pte_t *start_pte; |
| pte_t *pte; |
| swp_entry_t entry; |
| |
| tlb_change_page_size(tlb, PAGE_SIZE); |
| again: |
| init_rss_vec(rss); |
| start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| pte = start_pte; |
| flush_tlb_batched_pending(mm); |
| arch_enter_lazy_mmu_mode(); |
| do { |
| pte_t ptent = *pte; |
| struct page *page; |
| |
| if (pte_none(ptent)) |
| continue; |
| |
| if (need_resched()) |
| break; |
| |
| if (pte_present(ptent)) { |
| page = vm_normal_page(vma, addr, ptent); |
| if (unlikely(!should_zap_page(details, page))) |
| continue; |
| ptent = ptep_get_and_clear_full(mm, addr, pte, |
| tlb->fullmm); |
| tlb_remove_tlb_entry(tlb, pte, addr); |
| zap_install_uffd_wp_if_needed(vma, addr, pte, details, |
| ptent); |
| if (unlikely(!page)) |
| continue; |
| |
| if (!PageAnon(page)) { |
| if (pte_dirty(ptent)) { |
| force_flush = 1; |
| set_page_dirty(page); |
| } |
| if (pte_young(ptent) && |
| likely(!(vma->vm_flags & VM_SEQ_READ))) |
| mark_page_accessed(page); |
| } |
| rss[mm_counter(page)]--; |
| page_remove_rmap(page, vma, false); |
| if (unlikely(page_mapcount(page) < 0)) |
| print_bad_pte(vma, addr, ptent, page); |
| if (unlikely(__tlb_remove_page(tlb, page))) { |
| force_flush = 1; |
| addr += PAGE_SIZE; |
| break; |
| } |
| continue; |
| } |
| |
| entry = pte_to_swp_entry(ptent); |
| if (is_device_private_entry(entry) || |
| is_device_exclusive_entry(entry)) { |
| page = pfn_swap_entry_to_page(entry); |
| if (unlikely(!should_zap_page(details, page))) |
| continue; |
| /* |
| * Both device private/exclusive mappings should only |
| * work with anonymous page so far, so we don't need to |
| * consider uffd-wp bit when zap. For more information, |
| * see zap_install_uffd_wp_if_needed(). |
| */ |
| WARN_ON_ONCE(!vma_is_anonymous(vma)); |
| rss[mm_counter(page)]--; |
| if (is_device_private_entry(entry)) |
| page_remove_rmap(page, vma, false); |
| put_page(page); |
| } else if (!non_swap_entry(entry)) { |
| /* Genuine swap entry, hence a private anon page */ |
| if (!should_zap_cows(details)) |
| continue; |
| rss[MM_SWAPENTS]--; |
| if (unlikely(!free_swap_and_cache(entry))) |
| print_bad_pte(vma, addr, ptent, NULL); |
| } else if (is_migration_entry(entry)) { |
| page = pfn_swap_entry_to_page(entry); |
| if (!should_zap_page(details, page)) |
| continue; |
| rss[mm_counter(page)]--; |
| } else if (pte_marker_entry_uffd_wp(entry)) { |
| /* Only drop the uffd-wp marker if explicitly requested */ |
| if (!zap_drop_file_uffd_wp(details)) |
| continue; |
| } else if (is_hwpoison_entry(entry) || |
| is_swapin_error_entry(entry)) { |
| if (!should_zap_cows(details)) |
| continue; |
| } else { |
| /* We should have covered all the swap entry types */ |
| WARN_ON_ONCE(1); |
| } |
| pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); |
| zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| |
| add_mm_rss_vec(mm, rss); |
| arch_leave_lazy_mmu_mode(); |
| |
| /* Do the actual TLB flush before dropping ptl */ |
| if (force_flush) |
| tlb_flush_mmu_tlbonly(tlb); |
| pte_unmap_unlock(start_pte, ptl); |
| |
| /* |
| * If we forced a TLB flush (either due to running out of |
| * batch buffers or because we needed to flush dirty TLB |
| * entries before releasing the ptl), free the batched |
| * memory too. Restart if we didn't do everything. |
| */ |
| if (force_flush) { |
| force_flush = 0; |
| tlb_flush_mmu(tlb); |
| } |
| |
| if (addr != end) { |
| cond_resched(); |
| goto again; |
| } |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| |
| pmd = pmd_offset(pud, addr); |
| do { |
| next = pmd_addr_end(addr, end); |
| if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { |
| if (next - addr != HPAGE_PMD_SIZE) |
| __split_huge_pmd(vma, pmd, addr, false, NULL); |
| else if (zap_huge_pmd(tlb, vma, pmd, addr)) |
| goto next; |
| /* fall through */ |
| } else if (details && details->single_folio && |
| folio_test_pmd_mappable(details->single_folio) && |
| next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) { |
| spinlock_t *ptl = pmd_lock(tlb->mm, pmd); |
| /* |
| * Take and drop THP pmd lock so that we cannot return |
| * prematurely, while zap_huge_pmd() has cleared *pmd, |
| * but not yet decremented compound_mapcount(). |
| */ |
| spin_unlock(ptl); |
| } |
| |
| /* |
| * Here there can be other concurrent MADV_DONTNEED or |
| * trans huge page faults running, and if the pmd is |
| * none or trans huge it can change under us. This is |
| * because MADV_DONTNEED holds the mmap_lock in read |
| * mode. |
| */ |
| if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
| goto next; |
| next = zap_pte_range(tlb, vma, pmd, addr, next, details); |
| next: |
| cond_resched(); |
| } while (pmd++, addr = next, addr != end); |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_pud_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| pud_t *pud; |
| unsigned long next; |
| |
| pud = pud_offset(p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_trans_huge(*pud) || pud_devmap(*pud)) { |
| if (next - addr != HPAGE_PUD_SIZE) { |
| mmap_assert_locked(tlb->mm); |
| split_huge_pud(vma, pud, addr); |
| } else if (zap_huge_pud(tlb, vma, pud, addr)) |
| goto next; |
| /* fall through */ |
| } |
| if (pud_none_or_clear_bad(pud)) |
| continue; |
| next = zap_pmd_range(tlb, vma, pud, addr, next, details); |
| next: |
| cond_resched(); |
| } while (pud++, addr = next, addr != end); |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_p4d_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| |
| p4d = p4d_offset(pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(p4d)) |
| continue; |
| next = zap_pud_range(tlb, vma, p4d, addr, next, details); |
| } while (p4d++, addr = next, addr != end); |
| |
| return addr; |
| } |
| |
| void unmap_page_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| pgd_t *pgd; |
| unsigned long next; |
| |
| BUG_ON(addr >= end); |
| tlb_start_vma(tlb, vma); |
| pgd = pgd_offset(vma->vm_mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(pgd)) |
| continue; |
| next = zap_p4d_range(tlb, vma, pgd, addr, next, details); |
| } while (pgd++, addr = next, addr != end); |
| tlb_end_vma(tlb, vma); |
| } |
| |
| |
| static void unmap_single_vma(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, unsigned long start_addr, |
| unsigned long end_addr, |
| struct zap_details *details) |
| { |
| unsigned long start = max(vma->vm_start, start_addr); |
| unsigned long end; |
| |
| if (start >= vma->vm_end) |
| return; |
| end = min(vma->vm_end, end_addr); |
| if (end <= vma->vm_start) |
| return; |
| |
| if (vma->vm_file) |
| uprobe_munmap(vma, start, end); |
| |
| if (unlikely(vma->vm_flags & VM_PFNMAP)) |
| untrack_pfn(vma, 0, 0); |
| |
| if (start != end) { |
| if (unlikely(is_vm_hugetlb_page(vma))) { |
| /* |
| * It is undesirable to test vma->vm_file as it |
| * should be non-null for valid hugetlb area. |
| * However, vm_file will be NULL in the error |
| * cleanup path of mmap_region. When |
| * hugetlbfs ->mmap method fails, |
| * mmap_region() nullifies vma->vm_file |
| * before calling this function to clean up. |
| * Since no pte has actually been setup, it is |
| * safe to do nothing in this case. |
| */ |
| if (vma->vm_file) { |
| zap_flags_t zap_flags = details ? |
| details->zap_flags : 0; |
| i_mmap_lock_write(vma->vm_file->f_mapping); |
| __unmap_hugepage_range_final(tlb, vma, start, end, |
| NULL, zap_flags); |
| i_mmap_unlock_write(vma->vm_file->f_mapping); |
| } |
| } else |
| unmap_page_range(tlb, vma, start, end, details); |
| } |
| } |
| |
| /** |
| * unmap_vmas - unmap a range of memory covered by a list of vma's |
| * @tlb: address of the caller's struct mmu_gather |
| * @mt: the maple tree |
| * @vma: the starting vma |
| * @start_addr: virtual address at which to start unmapping |
| * @end_addr: virtual address at which to end unmapping |
| * |
| * Unmap all pages in the vma list. |
| * |
| * Only addresses between `start' and `end' will be unmapped. |
| * |
| * The VMA list must be sorted in ascending virtual address order. |
| * |
| * unmap_vmas() assumes that the caller will flush the whole unmapped address |
| * range after unmap_vmas() returns. So the only responsibility here is to |
| * ensure that any thus-far unmapped pages are flushed before unmap_vmas() |
| * drops the lock and schedules. |
| */ |
| void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt, |
| struct vm_area_struct *vma, unsigned long start_addr, |
| unsigned long end_addr) |
| { |
| struct mmu_notifier_range range; |
| struct zap_details details = { |
| .zap_flags = ZAP_FLAG_DROP_MARKER, |
| /* Careful - we need to zap private pages too! */ |
| .even_cows = true, |
| }; |
| MA_STATE(mas, mt, vma->vm_end, vma->vm_end); |
| |
| mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm, |
| start_addr, end_addr); |
| mmu_notifier_invalidate_range_start(&range); |
| do { |
| unmap_single_vma(tlb, vma, start_addr, end_addr, &details); |
| } while ((vma = mas_find(&mas, end_addr - 1)) != NULL); |
| mmu_notifier_invalidate_range_end(&range); |
| } |
| |
| /** |
| * zap_page_range - remove user pages in a given range |
| * @vma: vm_area_struct holding the applicable pages |
| * @start: starting address of pages to zap |
| * @size: number of bytes to zap |
| * |
| * Caller must protect the VMA list |
| */ |
| void zap_page_range(struct vm_area_struct *vma, unsigned long start, |
| unsigned long size) |
| { |
| struct maple_tree *mt = &vma->vm_mm->mm_mt; |
| unsigned long end = start + size; |
| struct mmu_notifier_range range; |
| struct mmu_gather tlb; |
| MA_STATE(mas, mt, vma->vm_end, vma->vm_end); |
| |
| lru_add_drain(); |
| mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, |
| start, start + size); |
| tlb_gather_mmu(&tlb, vma->vm_mm); |
| update_hiwater_rss(vma->vm_mm); |
| mmu_notifier_invalidate_range_start(&range); |
| do { |
| unmap_single_vma(&tlb, vma, start, range.end, NULL); |
| } while ((vma = mas_find(&mas, end - 1)) != NULL); |
| mmu_notifier_invalidate_range_end(&range); |
| tlb_finish_mmu(&tlb); |
| } |
| |
| /** |
| * zap_page_range_single - remove user pages in a given range |
| * @vma: vm_area_struct holding the applicable pages |
| * @address: starting address of pages to zap |
| * @size: number of bytes to zap |
| * @details: details of shared cache invalidation |
| * |
| * The range must fit into one VMA. |
| */ |
| static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, |
| unsigned long size, struct zap_details *details) |
| { |
| struct mmu_notifier_range range; |
| struct mmu_gather tlb; |
| |
| lru_add_drain(); |
| mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, |
| address, address + size); |
| tlb_gather_mmu(&tlb, vma->vm_mm); |
| update_hiwater_rss(vma->vm_mm); |
| mmu_notifier_invalidate_range_start(&range); |
| unmap_single_vma(&tlb, vma, address, range.end, details); |
| mmu_notifier_invalidate_range_end(&range); |
| tlb_finish_mmu(&tlb); |
| } |
| |
| /** |
| * zap_vma_ptes - remove ptes mapping the vma |
| * @vma: vm_area_struct holding ptes to be zapped |
| * @address: starting address of pages to zap |
| * @size: number of bytes to zap |
| * |
| * This function only unmaps ptes assigned to VM_PFNMAP vmas. |
| * |
| * The entire address range must be fully contained within the vma. |
| * |
| */ |
| void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, |
| unsigned long size) |
| { |
| if (!range_in_vma(vma, address, address + size) || |
| !(vma->vm_flags & VM_PFNMAP)) |
| return; |
| |
| zap_page_range_single(vma, address, size, NULL); |
| } |
| EXPORT_SYMBOL_GPL(zap_vma_ptes); |
| |
| static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr) |
| { |
| pgd_t *pgd; |
| p4d_t *p4d; |
| pud_t *pud; |
| pmd_t *pmd; |
| |
| pgd = pgd_offset(mm, addr); |
| p4d = p4d_alloc(mm, pgd, addr); |
| if (!p4d) |
| return NULL; |
| pud = pud_alloc(mm, p4d, addr); |
| if (!pud) |
| return NULL; |
| pmd = pmd_alloc(mm, pud, addr); |
| if (!pmd) |
| return NULL; |
| |
| VM_BUG_ON(pmd_trans_huge(*pmd)); |
| return pmd; |
| } |
| |
| pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, |
| spinlock_t **ptl) |
| { |
| pmd_t *pmd = walk_to_pmd(mm, addr); |
| |
| if (!pmd) |
| return NULL; |
| return pte_alloc_map_lock(mm, pmd, addr, ptl); |
| } |
| |
| static int validate_page_before_insert(struct page *page) |
| { |
| if (PageAnon(page) || PageSlab(page) || page_has_type(page)) |
| return -EINVAL; |
| flush_dcache_page(page); |
| return 0; |
| } |
| |
| static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte, |
| unsigned long addr, struct page *page, pgprot_t prot) |
| { |
| if (!pte_none(*pte)) |
| return -EBUSY; |
| /* Ok, finally just insert the thing.. */ |
| get_page(page); |
| inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page)); |
| page_add_file_rmap(page, vma, false); |
| set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot)); |
| return 0; |
| } |
| |
| /* |
| * This is the old fallback for page remapping. |
| * |
| * For historical reasons, it only allows reserved pages. Only |
| * old drivers should use this, and they needed to mark their |
| * pages reserved for the old functions anyway. |
| */ |
| static int insert_page(struct vm_area_struct *vma, unsigned long addr, |
| struct page *page, pgprot_t prot) |
| { |
| int retval; |
| pte_t *pte; |
| spinlock_t *ptl; |
| |
| retval = validate_page_before_insert(page); |
| if (retval) |
| goto out; |
| retval = -ENOMEM; |
| pte = get_locked_pte(vma->vm_mm, addr, &ptl); |
| if (!pte) |
| goto out; |
| retval = insert_page_into_pte_locked(vma, pte, addr, page, prot); |
| pte_unmap_unlock(pte, ptl); |
| out: |
| return retval; |
| } |
| |
| #ifdef pte_index |
| static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte, |
| unsigned long addr, struct page *page, pgprot_t prot) |
| { |
| int err; |
| |
| if (!page_count(page)) |
| return -EINVAL; |
| err = validate_page_before_insert(page); |
| if (err) |
| return err; |
| return insert_page_into_pte_locked(vma, pte, addr, page, prot); |
| } |
| |
| /* insert_pages() amortizes the cost of spinlock operations |
| * when inserting pages in a loop. Arch *must* define pte_index. |
| */ |
| static int insert_pages(struct vm_area_struct *vma, unsigned long addr, |
| struct page **pages, unsigned long *num, pgprot_t prot) |
| { |
| pmd_t *pmd = NULL; |
| pte_t *start_pte, *pte; |
| spinlock_t *pte_lock; |
| struct mm_struct *const mm = vma->vm_mm; |
| unsigned long curr_page_idx = 0; |
| unsigned long remaining_pages_total = *num; |
| unsigned long pages_to_write_in_pmd; |
| int ret; |
| more: |
| ret = -EFAULT; |
| pmd = walk_to_pmd(mm, addr); |
| if (!pmd) |
| goto out; |
| |
| pages_to_write_in_pmd = min_t(unsigned long, |
| remaining_pages_total, PTRS_PER_PTE - pte_index(addr)); |
| |
| /* Allocate the PTE if necessary; takes PMD lock once only. */ |
| ret = -ENOMEM; |
| if (pte_alloc(mm, pmd)) |
| goto out; |
| |
| while (pages_to_write_in_pmd) { |
| int pte_idx = 0; |
| const int batch_size = min_t(int, pages_to_write_in_pmd, 8); |
| |
| start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock); |
| for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) { |
| int err = insert_page_in_batch_locked(vma, pte, |
| addr, pages[curr_page_idx], prot); |
| if (unlikely(err)) { |
| pte_unmap_unlock(start_pte, pte_lock); |
| ret = err; |
| remaining_pages_total -= pte_idx; |
| goto out; |
| } |
| addr += PAGE_SIZE; |
| ++curr_page_idx; |
| } |
| pte_unmap_unlock(start_pte, pte_lock); |
| pages_to_write_in_pmd -= batch_size; |
| remaining_pages_total -= batch_size; |
| } |
| if (remaining_pages_total) |
| goto more; |
| ret = 0; |
| out: |
| *num = remaining_pages_total; |
| return ret; |
| } |
| #endif /* ifdef pte_index */ |
| |
| /** |
| * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock. |
| * @vma: user vma to map to |
| * @addr: target start user address of these pages |
| * @pages: source kernel pages |
| * @num: in: number of pages to map. out: number of pages that were *not* |
| * mapped. (0 means all pages were successfully mapped). |
| * |
| * Preferred over vm_insert_page() when inserting multiple pages. |
| * |
| * In case of error, we may have mapped a subset of the provided |
| * pages. It is the caller's responsibility to account for this case. |
| * |
| * The same restrictions apply as in vm_insert_page(). |
| */ |
| int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, |
| struct page **pages, unsigned long *num) |
| { |
| #ifdef pte_index |
| const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1; |
| |
| if (addr < vma->vm_start || end_addr >= vma->vm_end) |
| return -EFAULT; |
| if (!(vma->vm_flags & VM_MIXEDMAP)) { |
| BUG_ON(mmap_read_trylock(vma->vm_mm)); |
| BUG_ON(vma->vm_flags & VM_PFNMAP); |
| vma->vm_flags |= VM_MIXEDMAP; |
| } |
| /* Defer page refcount checking till we're about to map that page. */ |
| return insert_pages(vma, addr, pages, num, vma->vm_page_prot); |
| #else |
| unsigned long idx = 0, pgcount = *num; |
| int err = -EINVAL; |
| |
| for (; idx < pgcount; ++idx) { |
| err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]); |
| if (err) |
| break; |
| } |
| *num = pgcount - idx; |
| return err; |
| #endif /* ifdef pte_index */ |
| } |
| EXPORT_SYMBOL(vm_insert_pages); |
| |
| /** |
| * vm_insert_page - insert single page into user vma |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @page: source kernel page |
| * |
| * This allows drivers to insert individual pages they've allocated |
| * into a user vma. |
| * |
| * The page has to be a nice clean _individual_ kernel allocation. |
| * If you allocate a compound page, you need to have marked it as |
| * such (__GFP_COMP), or manually just split the page up yourself |
| * (see split_page()). |
| * |
| * NOTE! Traditionally this was done with "remap_pfn_range()" which |
| * took an arbitrary page protection parameter. This doesn't allow |
| * that. Your vma protection will have to be set up correctly, which |
| * means that if you want a shared writable mapping, you'd better |
| * ask for a shared writable mapping! |
| * |
| * The page does not need to be reserved. |
| * |
| * Usually this function is called from f_op->mmap() handler |
| * under mm->mmap_lock write-lock, so it can change vma->vm_flags. |
| * Caller must set VM_MIXEDMAP on vma if it wants to call this |
| * function from other places, for example from page-fault handler. |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
| struct page *page) |
| { |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return -EFAULT; |
| if (!page_count(page)) |
| return -EINVAL; |
| if (!(vma->vm_flags & VM_MIXEDMAP)) { |
| BUG_ON(mmap_read_trylock(vma->vm_mm)); |
| BUG_ON(vma->vm_flags & VM_PFNMAP); |
| vma->vm_flags |= VM_MIXEDMAP; |
| } |
| return insert_page(vma, addr, page, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vm_insert_page); |
| |
| /* |
| * __vm_map_pages - maps range of kernel pages into user vma |
| * @vma: user vma to map to |
| * @pages: pointer to array of source kernel pages |
| * @num: number of pages in page array |
| * @offset: user's requested vm_pgoff |
| * |
| * This allows drivers to map range of kernel pages into a user vma. |
| * |
| * Return: 0 on success and error code otherwise. |
| */ |
| static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages, |
| unsigned long num, unsigned long offset) |
| { |
| unsigned long count = vma_pages(vma); |
| unsigned long uaddr = vma->vm_start; |
| int ret, i; |
| |
| /* Fail if the user requested offset is beyond the end of the object */ |
| if (offset >= num) |
| return -ENXIO; |
| |
| /* Fail if the user requested size exceeds available object size */ |
| if (count > num - offset) |
| return -ENXIO; |
| |
| for (i = 0; i < count; i++) { |
| ret = vm_insert_page(vma, uaddr, pages[offset + i]); |
| if (ret < 0) |
| return ret; |
| uaddr += PAGE_SIZE; |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * vm_map_pages - maps range of kernel pages starts with non zero offset |
| * @vma: user vma to map to |
| * @pages: pointer to array of source kernel pages |
| * @num: number of pages in page array |
| * |
| * Maps an object consisting of @num pages, catering for the user's |
| * requested vm_pgoff |
| * |
| * If we fail to insert any page into the vma, the function will return |
| * immediately leaving any previously inserted pages present. Callers |
| * from the mmap handler may immediately return the error as their caller |
| * will destroy the vma, removing any successfully inserted pages. Other |
| * callers should make their own arrangements for calling unmap_region(). |
| * |
| * Context: Process context. Called by mmap handlers. |
| * Return: 0 on success and error code otherwise. |
| */ |
| int vm_map_pages(struct vm_area_struct *vma, struct page **pages, |
| unsigned long num) |
| { |
| return __vm_map_pages(vma, pages, num, vma->vm_pgoff); |
| } |
| EXPORT_SYMBOL(vm_map_pages); |
| |
| /** |
| * vm_map_pages_zero - map range of kernel pages starts with zero offset |
| * @vma: user vma to map to |
| * @pages: pointer to array of source kernel pages |
| * @num: number of pages in page array |
| * |
| * Similar to vm_map_pages(), except that it explicitly sets the offset |
| * to 0. This function is intended for the drivers that did not consider |
| * vm_pgoff. |
| * |
| * Context: Process context. Called by mmap handlers. |
| * Return: 0 on success and error code otherwise. |
| */ |
| int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, |
| unsigned long num) |
| { |
| return __vm_map_pages(vma, pages, num, 0); |
| } |
| EXPORT_SYMBOL(vm_map_pages_zero); |
| |
| static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| pfn_t pfn, pgprot_t prot, bool mkwrite) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| pte_t *pte, entry; |
| spinlock_t *ptl; |
| |
| pte = get_locked_pte(mm, addr, &ptl); |
| if (!pte) |
| return VM_FAULT_OOM; |
| if (!pte_none(*pte)) { |
| if (mkwrite) { |
| /* |
| * For read faults on private mappings the PFN passed |
| * in may not match the PFN we have mapped if the |
| * mapped PFN is a writeable COW page. In the mkwrite |
| * case we are creating a writable PTE for a shared |
| * mapping and we expect the PFNs to match. If they |
| * don't match, we are likely racing with block |
| * allocation and mapping invalidation so just skip the |
| * update. |
| */ |
| if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) { |
| WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte))); |
| goto out_unlock; |
| } |
| entry = pte_mkyoung(*pte); |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| if (ptep_set_access_flags(vma, addr, pte, entry, 1)) |
| update_mmu_cache(vma, addr, pte); |
| } |
| goto out_unlock; |
| } |
| |
| /* Ok, finally just insert the thing.. */ |
| if (pfn_t_devmap(pfn)) |
| entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); |
| else |
| entry = pte_mkspecial(pfn_t_pte(pfn, prot)); |
| |
| if (mkwrite) { |
| entry = pte_mkyoung(entry); |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| } |
| |
| set_pte_at(mm, addr, pte, entry); |
| update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ |
| |
| out_unlock: |
| pte_unmap_unlock(pte, ptl); |
| return VM_FAULT_NOPAGE; |
| } |
| |
| /** |
| * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @pfn: source kernel pfn |
| * @pgprot: pgprot flags for the inserted page |
| * |
| * This is exactly like vmf_insert_pfn(), except that it allows drivers |
| * to override pgprot on a per-page basis. |
| * |
| * This only makes sense for IO mappings, and it makes no sense for |
| * COW mappings. In general, using multiple vmas is preferable; |
| * vmf_insert_pfn_prot should only be used if using multiple VMAs is |
| * impractical. |
| * |
| * See vmf_insert_mixed_prot() for a discussion of the implication of using |
| * a value of @pgprot different from that of @vma->vm_page_prot. |
| * |
| * Context: Process context. May allocate using %GFP_KERNEL. |
| * Return: vm_fault_t value. |
| */ |
| vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn, pgprot_t pgprot) |
| { |
| /* |
| * Technically, architectures with pte_special can avoid all these |
| * restrictions (same for remap_pfn_range). However we would like |
| * consistency in testing and feature parity among all, so we should |
| * try to keep these invariants in place for everybody. |
| */ |
| BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); |
| BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
| (VM_PFNMAP|VM_MIXEDMAP)); |
| BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
| BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); |
| |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return VM_FAULT_SIGBUS; |
| |
| if (!pfn_modify_allowed(pfn, pgprot)) |
| return VM_FAULT_SIGBUS; |
| |
| track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)); |
| |
| return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot, |
| false); |
| } |
| EXPORT_SYMBOL(vmf_insert_pfn_prot); |
| |
| /** |
| * vmf_insert_pfn - insert single pfn into user vma |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @pfn: source kernel pfn |
| * |
| * Similar to vm_insert_page, this allows drivers to insert individual pages |
| * they've allocated into a user vma. Same comments apply. |
| * |
| * This function should only be called from a vm_ops->fault handler, and |
| * in that case the handler should return the result of this function. |
| * |
| * vma cannot be a COW mapping. |
| * |
| * As this is called only for pages that do not currently exist, we |
| * do not need to flush old virtual caches or the TLB. |
| * |
| * Context: Process context. May allocate using %GFP_KERNEL. |
| * Return: vm_fault_t value. |
| */ |
| vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn) |
| { |
| return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vmf_insert_pfn); |
| |
| static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) |
| { |
| /* these checks mirror the abort conditions in vm_normal_page */ |
| if (vma->vm_flags & VM_MIXEDMAP) |
| return true; |
| if (pfn_t_devmap(pfn)) |
| return true; |
| if (pfn_t_special(pfn)) |
| return true; |
| if (is_zero_pfn(pfn_t_to_pfn(pfn))) |
| return true; |
| return false; |
| } |
| |
| static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, |
| unsigned long addr, pfn_t pfn, pgprot_t pgprot, |
| bool mkwrite) |
| { |
| int err; |
| |
| BUG_ON(!vm_mixed_ok(vma, pfn)); |
| |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return VM_FAULT_SIGBUS; |
| |
| track_pfn_insert(vma, &pgprot, pfn); |
| |
| if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot)) |
| return VM_FAULT_SIGBUS; |
| |
| /* |
| * If we don't have pte special, then we have to use the pfn_valid() |
| * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* |
| * refcount the page if pfn_valid is true (hence insert_page rather |
| * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP |
| * without pte special, it would there be refcounted as a normal page. |
| */ |
| if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && |
| !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { |
| struct page *page; |
| |
| /* |
| * At this point we are committed to insert_page() |
| * regardless of whether the caller specified flags that |
| * result in pfn_t_has_page() == false. |
| */ |
| page = pfn_to_page(pfn_t_to_pfn(pfn)); |
| err = insert_page(vma, addr, page, pgprot); |
| } else { |
| return insert_pfn(vma, addr, pfn, pgprot, mkwrite); |
| } |
| |
| if (err == -ENOMEM) |
| return VM_FAULT_OOM; |
| if (err < 0 && err != -EBUSY) |
| return VM_FAULT_SIGBUS; |
| |
| return VM_FAULT_NOPAGE; |
| } |
| |
| /** |
| * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @pfn: source kernel pfn |
| * @pgprot: pgprot flags for the inserted page |
| * |
| * This is exactly like vmf_insert_mixed(), except that it allows drivers |
| * to override pgprot on a per-page basis. |
| * |
| * Typically this function should be used by drivers to set caching- and |
| * encryption bits different than those of @vma->vm_page_prot, because |
| * the caching- or encryption mode may not be known at mmap() time. |
| * This is ok as long as @vma->vm_page_prot is not used by the core vm |
| * to set caching and encryption bits for those vmas (except for COW pages). |
| * This is ensured by core vm only modifying these page table entries using |
| * functions that don't touch caching- or encryption bits, using pte_modify() |
| * if needed. (See for example mprotect()). |
| * Also when new page-table entries are created, this is only done using the |
| * fault() callback, and never using the value of vma->vm_page_prot, |
| * except for page-table entries that point to anonymous pages as the result |
| * of COW. |
| * |
| * Context: Process context. May allocate using %GFP_KERNEL. |
| * Return: vm_fault_t value. |
| */ |
| vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr, |
| pfn_t pfn, pgprot_t pgprot) |
| { |
| return __vm_insert_mixed(vma, addr, pfn, pgprot, false); |
| } |
| EXPORT_SYMBOL(vmf_insert_mixed_prot); |
| |
| vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr, |
| pfn_t pfn) |
| { |
| return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false); |
| } |
| EXPORT_SYMBOL(vmf_insert_mixed); |
| |
| /* |
| * If the insertion of PTE failed because someone else already added a |
| * different entry in the mean time, we treat that as success as we assume |
| * the same entry was actually inserted. |
| */ |
| vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma, |
| unsigned long addr, pfn_t pfn) |
| { |
| return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true); |
| } |
| EXPORT_SYMBOL(vmf_insert_mixed_mkwrite); |
| |
| /* |
| * maps a range of physical memory into the requested pages. the old |
| * mappings are removed. any references to nonexistent pages results |
| * in null mappings (currently treated as "copy-on-access") |
| */ |
| static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| pte_t *pte, *mapped_pte; |
| spinlock_t *ptl; |
| int err = 0; |
| |
| mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return -ENOMEM; |
| arch_enter_lazy_mmu_mode(); |
| do { |
| BUG_ON(!pte_none(*pte)); |
| if (!pfn_modify_allowed(pfn, prot)) { |
| err = -EACCES; |
| break; |
| } |
| set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); |
| pfn++; |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(mapped_pte, ptl); |
| return err; |
| } |
| |
| static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| int err; |
| |
| pfn -= addr >> PAGE_SHIFT; |
| pmd = pmd_alloc(mm, pud, addr); |
| if (!pmd) |
| return -ENOMEM; |
| VM_BUG_ON(pmd_trans_huge(*pmd)); |
| do { |
| next = pmd_addr_end(addr, end); |
| err = remap_pte_range(mm, pmd, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (pmd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| pud_t *pud; |
| unsigned long next; |
| int err; |
| |
| pfn -= addr >> PAGE_SHIFT; |
| pud = pud_alloc(mm, p4d, addr); |
| if (!pud) |
| return -ENOMEM; |
| do { |
| next = pud_addr_end(addr, end); |
| err = remap_pmd_range(mm, pud, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (pud++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| int err; |
| |
| pfn -= addr >> PAGE_SHIFT; |
| p4d = p4d_alloc(mm, pgd, addr); |
| if (!p4d) |
| return -ENOMEM; |
| do { |
| next = p4d_addr_end(addr, end); |
| err = remap_pud_range(mm, p4d, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (p4d++, addr = next, addr != end); |
| return 0; |
| } |
| |
| /* |
| * Variant of remap_pfn_range that does not call track_pfn_remap. The caller |
| * must have pre-validated the caching bits of the pgprot_t. |
| */ |
| int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn, unsigned long size, pgprot_t prot) |
| { |
| pgd_t *pgd; |
| unsigned long next; |
| unsigned long end = addr + PAGE_ALIGN(size); |
| struct mm_struct *mm = vma->vm_mm; |
| int err; |
| |
| if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) |
| return -EINVAL; |
| |
| /* |
| * Physically remapped pages are special. Tell the |
| * rest of the world about it: |
| * VM_IO tells people not to look at these pages |
| * (accesses can have side effects). |
| * VM_PFNMAP tells the core MM that the base pages are just |
| * raw PFN mappings, and do not have a "struct page" associated |
| * with them. |
| * VM_DONTEXPAND |
| * Disable vma merging and expanding with mremap(). |
| * VM_DONTDUMP |
| * Omit vma from core dump, even when VM_IO turned off. |
| * |
| * There's a horrible special case to handle copy-on-write |
| * behaviour that some programs depend on. We mark the "original" |
| * un-COW'ed pages by matching them up with "vma->vm_pgoff". |
| * See vm_normal_page() for details. |
| */ |
| if (is_cow_mapping(vma->vm_flags)) { |
| if (addr != vma->vm_start || end != vma->vm_end) |
| return -EINVAL; |
| vma->vm_pgoff = pfn; |
| } |
| |
| vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; |
| |
| BUG_ON(addr >= end); |
| pfn -= addr >> PAGE_SHIFT; |
| pgd = pgd_offset(mm, addr); |
| flush_cache_range(vma, addr, end); |
| do { |
| next = pgd_addr_end(addr, end); |
| err = remap_p4d_range(mm, pgd, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (pgd++, addr = next, addr != end); |
| |
| return 0; |
| } |
| |
| /** |
| * remap_pfn_range - remap kernel memory to userspace |
| * @vma: user vma to map to |
| * @addr: target page aligned user address to start at |
| * @pfn: page frame number of kernel physical memory address |
| * @size: size of mapping area |
| * @prot: page protection flags for this mapping |
| * |
| * Note: this is only safe if the mm semaphore is held when called. |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn, unsigned long size, pgprot_t prot) |
| { |
| int err; |
| |
| err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); |
| if (err) |
| return -EINVAL; |
| |
| err = remap_pfn_range_notrack(vma, addr, pfn, size, prot); |
| if (err) |
| untrack_pfn(vma, pfn, PAGE_ALIGN(size)); |
| return err; |
| } |
| EXPORT_SYMBOL(remap_pfn_range); |
| |
| /** |
| * vm_iomap_memory - remap memory to userspace |
| * @vma: user vma to map to |
| * @start: start of the physical memory to be mapped |
| * @len: size of area |
| * |
| * This is a simplified io_remap_pfn_range() for common driver use. The |
| * driver just needs to give us the physical memory range to be mapped, |
| * we'll figure out the rest from the vma information. |
| * |
| * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get |
| * whatever write-combining details or similar. |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
| { |
| unsigned long vm_len, pfn, pages; |
| |
| /* Check that the physical memory area passed in looks valid */ |
| if (start + len < start) |
| return -EINVAL; |
| /* |
| * You *really* shouldn't map things that aren't page-aligned, |
| * but we've historically allowed it because IO memory might |
| * just have smaller alignment. |
| */ |
| len += start & ~PAGE_MASK; |
| pfn = start >> PAGE_SHIFT; |
| pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; |
| if (pfn + pages < pfn) |
| return -EINVAL; |
| |
| /* We start the mapping 'vm_pgoff' pages into the area */ |
| if (vma->vm_pgoff > pages) |
| return -EINVAL; |
| pfn += vma->vm_pgoff; |
| pages -= vma->vm_pgoff; |
| |
| /* Can we fit all of the mapping? */ |
| vm_len = vma->vm_end - vma->vm_start; |
| if (vm_len >> PAGE_SHIFT > pages) |
| return -EINVAL; |
| |
| /* Ok, let it rip */ |
| return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vm_iomap_memory); |
| |
| static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| pte_t *pte, *mapped_pte; |
| int err = 0; |
| spinlock_t *ptl; |
| |
| if (create) { |
| mapped_pte = pte = (mm == &init_mm) ? |
| pte_alloc_kernel_track(pmd, addr, mask) : |
| pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return -ENOMEM; |
| } else { |
| mapped_pte = pte = (mm == &init_mm) ? |
| pte_offset_kernel(pmd, addr) : |
| pte_offset_map_lock(mm, pmd, addr, &ptl); |
| } |
| |
| BUG_ON(pmd_huge(*pmd)); |
| |
| arch_enter_lazy_mmu_mode(); |
| |
| if (fn) { |
| do { |
| if (create || !pte_none(*pte)) { |
| err = fn(pte++, addr, data); |
| if (err) |
| break; |
| } |
| } while (addr += PAGE_SIZE, addr != end); |
| } |
| *mask |= PGTBL_PTE_MODIFIED; |
| |
| arch_leave_lazy_mmu_mode(); |
| |
| if (mm != &init_mm) |
| pte_unmap_unlock(mapped_pte, ptl); |
| return err; |
| } |
| |
| static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| int err = 0; |
| |
| BUG_ON(pud_huge(*pud)); |
| |
| if (create) { |
| pmd = pmd_alloc_track(mm, pud, addr, mask); |
| if (!pmd) |
| return -ENOMEM; |
| } else { |
| pmd = pmd_offset(pud, addr); |
| } |
| do { |
| next = pmd_addr_end(addr, end); |
| if (pmd_none(*pmd) && !create) |
| continue; |
| if (WARN_ON_ONCE(pmd_leaf(*pmd))) |
| return -EINVAL; |
| if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) { |
| if (!create) |
| continue; |
| pmd_clear_bad(pmd); |
| } |
| err = apply_to_pte_range(mm, pmd, addr, next, |
| fn, data, create, mask); |
| if (err) |
| break; |
| } while (pmd++, addr = next, addr != end); |
| |
| return err; |
| } |
| |
| static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| pud_t *pud; |
| unsigned long next; |
| int err = 0; |
| |
| if (create) { |
| pud = pud_alloc_track(mm, p4d, addr, mask); |
| if (!pud) |
| return -ENOMEM; |
| } else { |
| pud = pud_offset(p4d, addr); |
| } |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_none(*pud) && !create) |
| continue; |
| if (WARN_ON_ONCE(pud_leaf(*pud))) |
| return -EINVAL; |
| if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { |
| if (!create) |
| continue; |
| pud_clear_bad(pud); |
| } |
| err = apply_to_pmd_range(mm, pud, addr, next, |
| fn, data, create, mask); |
| if (err) |
| break; |
| } while (pud++, addr = next, addr != end); |
| |
| return err; |
| } |
| |
| static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| int err = 0; |
| |
| if (create) { |
| p4d = p4d_alloc_track(mm, pgd, addr, mask); |
| if (!p4d) |
| return -ENOMEM; |
| } else { |
| p4d = p4d_offset(pgd, addr); |
| } |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none(*p4d) && !create) |
| continue; |
| if (WARN_ON_ONCE(p4d_leaf(*p4d))) |
| return -EINVAL; |
| if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) { |
| if (!create) |
| continue; |
| p4d_clear_bad(p4d); |
| } |
| err = apply_to_pud_range(mm, p4d, addr, next, |
| fn, data, create, mask); |
| if (err) |
| break; |
| } while (p4d++, addr = next, addr != end); |
| |
| return err; |
| } |
| |
| static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
| unsigned long size, pte_fn_t fn, |
| void *data, bool create) |
| { |
| pgd_t *pgd; |
| unsigned long start = addr, next; |
| unsigned long end = addr + size; |
| pgtbl_mod_mask mask = 0; |
| int err = 0; |
| |
| if (WARN_ON(addr >= end)) |
| return -EINVAL; |
| |
| pgd = pgd_offset(mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none(*pgd) && !create) |
| continue; |
| if (WARN_ON_ONCE(pgd_leaf(*pgd))) |
| return -EINVAL; |
| if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) { |
| if (!create) |
| continue; |
| pgd_clear_bad(pgd); |
| } |
| err = apply_to_p4d_range(mm, pgd, addr, next, |
| fn, data, create, &mask); |
| if (err) |
| break; |
| } while (pgd++, addr = next, addr != end); |
| |
| if (mask & ARCH_PAGE_TABLE_SYNC_MASK) |
| arch_sync_kernel_mappings(start, start + size); |
| |
| return err; |
| } |
| |
| /* |
| * Scan a region of virtual memory, filling in page tables as necessary |
| * and calling a provided function on each leaf page table. |
| */ |
| int apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
| unsigned long size, pte_fn_t fn, void *data) |
| { |
| return __apply_to_page_range(mm, addr, size, fn, data, true); |
| } |
| EXPORT_SYMBOL_GPL(apply_to_page_range); |
| |
| /* |
| * Scan a region of virtual memory, calling a provided function on |
| * each leaf page table where it exists. |
| * |
| * Unlike apply_to_page_range, this does _not_ fill in page tables |
| * where they are absent. |
| */ |
| int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr, |
| unsigned long size, pte_fn_t fn, void *data) |
| { |
| return __apply_to_page_range(mm, addr, size, fn, data, false); |
| } |
| EXPORT_SYMBOL_GPL(apply_to_existing_page_range); |
| |
| /* |
| * handle_pte_fault chooses page fault handler according to an entry which was |
| * read non-atomically. Before making any commitment, on those architectures |
| * or configurations (e.g. i386 with PAE) which might give a mix of unmatched |
| * parts, do_swap_page must check under lock before unmapping the pte and |
| * proceeding (but do_wp_page is only called after already making such a check; |
| * and do_anonymous_page can safely check later on). |
| */ |
| static inline int pte_unmap_same(struct vm_fault *vmf) |
| { |
| int same = 1; |
| #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION) |
| if (sizeof(pte_t) > sizeof(unsigned long)) { |
| spinlock_t *ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); |
| spin_lock(ptl); |
| same = pte_same(*vmf->pte, vmf->orig_pte); |
| spin_unlock(ptl); |
| } |
| #endif |
| pte_unmap(vmf->pte); |
| vmf->pte = NULL; |
| return same; |
| } |
| |
| static inline bool __wp_page_copy_user(struct page *dst, struct page *src, |
| struct vm_fault *vmf) |
| { |
| bool ret; |
| void *kaddr; |
| void __user *uaddr; |
| bool locked = false; |
| struct vm_area_struct *vma = vmf->vma; |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long addr = vmf->address; |
| |
| if (likely(src)) { |
| copy_user_highpage(dst, src, addr, vma); |
| return true; |
| } |
| |
| /* |
| * If the source page was a PFN mapping, we don't have |
| * a "struct page" for it. We do a best-effort copy by |
| * just copying from the original user address. If that |
| * fails, we just zero-fill it. Live with it. |
| */ |
| kaddr = kmap_atomic(dst); |
| uaddr = (void __user *)(addr & PAGE_MASK); |
| |
| /* |
| * On architectures with software "accessed" bits, we would |
| * take a double page fault, so mark it accessed here. |
| */ |
| if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) { |
| pte_t entry; |
| |
| vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); |
| locked = true; |
| if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) { |
| /* |
| * Other thread has already handled the fault |
| * and update local tlb only |
| */ |
| update_mmu_tlb(vma, addr, vmf->pte); |
| ret = false; |
| goto pte_unlock; |
| } |
| |
| entry = pte_mkyoung(vmf->orig_pte); |
| if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0)) |
| update_mmu_cache(vma, addr, vmf->pte); |
| } |
| |
| /* |
| * This really shouldn't fail, because the page is there |
| * in the page tables. But it might just be unreadable, |
| * in which case we just give up and fill the result with |
| * zeroes. |
| */ |
| if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { |
| if (locked) |
| goto warn; |
| |
| /* Re-validate under PTL if the page is still mapped */ |
| vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); |
| locked = true; |
| if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) { |
| /* The PTE changed under us, update local tlb */ |
| update_mmu_tlb(vma, addr, vmf->pte); |
| ret = false; |
| goto pte_unlock; |
| } |
| |
| /* |
| * The same page can be mapped back since last copy attempt. |
| * Try to copy again under PTL. |
| */ |
| if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { |
| /* |
| * Give a warn in case there can be some obscure |
| * use-case |
| */ |
| warn: |
| WARN_ON_ONCE(1); |
| clear_page(kaddr); |
| } |
| } |
| |
| ret = true; |
| |
| pte_unlock: |
| if (locked) |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| kunmap_atomic(kaddr); |
| flush_dcache_page(dst); |
| |
| return ret; |
| } |
| |
| static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) |
| { |
| struct file *vm_file = vma->vm_file; |
| |
| if (vm_file) |
| return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO; |
| |
| /* |
| * Special mappings (e.g. VDSO) do not have any file so fake |
| * a default GFP_KERNEL for them. |
| */ |
| return GFP_KERNEL; |
| } |
| |
| /* |
| * Notify the address space that the page is about to become writable so that |
| * it can prohibit this or wait for the page to get into an appropriate state. |
| * |
| * We do this without the lock held, so that it can sleep if it needs to. |
| */ |
| static vm_fault_t do_page_mkwrite(struct vm_fault *vmf) |
| { |
| vm_fault_t ret; |
| struct page *page = vmf->page; |
| unsigned int old_flags = vmf->flags; |
| |
| vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
| |
| if (vmf->vma->vm_file && |
| IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host)) |
| return VM_FAULT_SIGBUS; |
| |
| ret = vmf->vma->vm_ops->page_mkwrite(vmf); |
| /* Restore original flags so that caller is not surprised */ |
| vmf->flags = old_flags; |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) |
| return ret; |
| if (unlikely(!(ret & VM_FAULT_LOCKED))) { |
| lock_page(page); |
| if (!page->mapping) { |
| unlock_page(page); |
| return 0; /* retry */ |
| } |
| ret |= VM_FAULT_LOCKED; |
| } else |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| return ret; |
| } |
| |
| /* |
| * Handle dirtying of a page in shared file mapping on a write fault. |
| * |
| * The function expects the page to be locked and unlocks it. |
| */ |
| static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct address_space *mapping; |
| struct page *page = vmf->page; |
| bool dirtied; |
| bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite; |
| |
| dirtied = set_page_dirty(page); |
| VM_BUG_ON_PAGE(PageAnon(page), page); |
| /* |
| * Take a local copy of the address_space - page.mapping may be zeroed |
| * by truncate after unlock_page(). The address_space itself remains |
| * pinned by vma->vm_file's reference. We rely on unlock_page()'s |
| * release semantics to prevent the compiler from undoing this copying. |
| */ |
| mapping = page_rmapping(page); |
| unlock_page(page); |
| |
| if (!page_mkwrite) |
| file_update_time(vma->vm_file); |
| |
| /* |
| * Throttle page dirtying rate down to writeback speed. |
| * |
| * mapping may be NULL here because some device drivers do not |
| * set page.mapping but still dirty their pages |
| * |
| * Drop the mmap_lock before waiting on IO, if we can. The file |
| * is pinning the mapping, as per above. |
| */ |
| if ((dirtied || page_mkwrite) && mapping) { |
| struct file *fpin; |
| |
| fpin = maybe_unlock_mmap_for_io(vmf, NULL); |
| balance_dirty_pages_ratelimited(mapping); |
| if (fpin) { |
| fput(fpin); |
| return VM_FAULT_COMPLETED; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Handle write page faults for pages that can be reused in the current vma |
| * |
| * This can happen either due to the mapping being with the VM_SHARED flag, |
| * or due to us being the last reference standing to the page. In either |
| * case, all we need to do here is to mark the page as writable and update |
| * any related book-keeping. |
| */ |
| static inline void wp_page_reuse(struct vm_fault *vmf) |
| __releases(vmf->ptl) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct page *page = vmf->page; |
| pte_t entry; |
| |
| VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE)); |
| VM_BUG_ON(page && PageAnon(page) && !PageAnonExclusive(page)); |
| |
| /* |
| * Clear the pages cpupid information as the existing |
| * information potentially belongs to a now completely |
| * unrelated process. |
| */ |
| if (page) |
| page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1); |
| |
| flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); |
| entry = pte_mkyoung(vmf->orig_pte); |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1)) |
| update_mmu_cache(vma, vmf->address, vmf->pte); |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| count_vm_event(PGREUSE); |
| } |
| |
| /* |
| * Handle the case of a page which we actually need to copy to a new page, |
| * either due to COW or unsharing. |
| * |
| * Called with mmap_lock locked and the old page referenced, but |
| * without the ptl held. |
| * |
| * High level logic flow: |
| * |
| * - Allocate a page, copy the content of the old page to the new one. |
| * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc. |
| * - Take the PTL. If the pte changed, bail out and release the allocated page |
| * - If the pte is still the way we remember it, update the page table and all |
| * relevant references. This includes dropping the reference the page-table |
| * held to the old page, as well as updating the rmap. |
| * - In any case, unlock the PTL and drop the reference we took to the old page. |
| */ |
| static vm_fault_t wp_page_copy(struct vm_fault *vmf) |
| { |
| const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; |
| struct vm_area_struct *vma = vmf->vma; |
| struct mm_struct *mm = vma->vm_mm; |
| struct page *old_page = vmf->page; |
| struct page *new_page = NULL; |
| pte_t entry; |
| int page_copied = 0; |
| struct mmu_notifier_range range; |
| |
| delayacct_wpcopy_start(); |
| |
| if (unlikely(anon_vma_prepare(vma))) |
| goto oom; |
| |
| if (is_zero_pfn(pte_pfn(vmf->orig_pte))) { |
| new_page = alloc_zeroed_user_highpage_movable(vma, |
| vmf->address); |
| if (!new_page) |
| goto oom; |
| } else { |
| new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, |
| vmf->address); |
| if (!new_page) |
| goto oom; |
| |
| if (!__wp_page_copy_user(new_page, old_page, vmf)) { |
| /* |
| * COW failed, if the fault was solved by other, |
| * it's fine. If not, userspace would re-fault on |
| * the same address and we will handle the fault |
| * from the second attempt. |
| */ |
| put_page(new_page); |
| if (old_page) |
| put_page(old_page); |
| |
| delayacct_wpcopy_end(); |
| return 0; |
| } |
| } |
| |
| if (mem_cgroup_charge(page_folio(new_page), mm, GFP_KERNEL)) |
| goto oom_free_new; |
| cgroup_throttle_swaprate(new_page, GFP_KERNEL); |
| |
| __SetPageUptodate(new_page); |
| |
| mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, |
| vmf->address & PAGE_MASK, |
| (vmf->address & PAGE_MASK) + PAGE_SIZE); |
| mmu_notifier_invalidate_range_start(&range); |
| |
| /* |
| * Re-check the pte - we dropped the lock |
| */ |
| vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl); |
| if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { |
| if (old_page) { |
| if (!PageAnon(old_page)) { |
| dec_mm_counter_fast(mm, |
| mm_counter_file(old_page)); |
| inc_mm_counter_fast(mm, MM_ANONPAGES); |
| } |
| } else { |
| inc_mm_counter_fast(mm, MM_ANONPAGES); |
| } |
| flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); |
| entry = mk_pte(new_page, vma->vm_page_prot); |
| entry = pte_sw_mkyoung(entry); |
| if (unlikely(unshare)) { |
| if (pte_soft_dirty(vmf->orig_pte)) |
| entry = pte_mksoft_dirty(entry); |
| if (pte_uffd_wp(vmf->orig_pte)) |
| entry = pte_mkuffd_wp(entry); |
| } else { |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| } |
| |
| /* |
| * Clear the pte entry and flush it first, before updating the |
| * pte with the new entry, to keep TLBs on different CPUs in |
| * sync. This code used to set the new PTE then flush TLBs, but |
| * that left a window where the new PTE could be loaded into |
| * some TLBs while the old PTE remains in others. |
| */ |
| ptep_clear_flush_notify(vma, vmf->address, vmf->pte); |
| page_add_new_anon_rmap(new_page, vma, vmf->address); |
| lru_cache_add_inactive_or_unevictable(new_page, vma); |
| /* |
| * We call the notify macro here because, when using secondary |
| * mmu page tables (such as kvm shadow page tables), we want the |
| * new page to be mapped directly into the secondary page table. |
| */ |
| BUG_ON(unshare && pte_write(entry)); |
| set_pte_at_notify(mm, vmf->address, vmf->pte, entry); |
| update_mmu_cache(vma, vmf->address, vmf->pte); |
| if (old_page) { |
| /* |
| * Only after switching the pte to the new page may |
| * we remove the mapcount here. Otherwise another |
| * process may come and find the rmap count decremented |
| * before the pte is switched to the new page, and |
| * "reuse" the old page writing into it while our pte |
| * here still points into it and can be read by other |
| * threads. |
| * |
| * The critical issue is to order this |
| * page_remove_rmap with the ptp_clear_flush above. |
| * Those stores are ordered by (if nothing else,) |
| * the barrier present in the atomic_add_negative |
| * in page_remove_rmap. |
| * |
| * Then the TLB flush in ptep_clear_flush ensures that |
| * no process can access the old page before the |
| * decremented mapcount is visible. And the old page |
| * cannot be reused until after the decremented |
| * mapcount is visible. So transitively, TLBs to |
| * old page will be flushed before it can be reused. |
| */ |
| page_remove_rmap(old_page, vma, false); |
| } |
| |
| /* Free the old page.. */ |
| new_page = old_page; |
| page_copied = 1; |
| } else { |
| update_mmu_tlb(vma, vmf->address, vmf->pte); |
| } |
| |
| if (new_page) |
| put_page(new_page); |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| /* |
| * No need to double call mmu_notifier->invalidate_range() callback as |
| * the above ptep_clear_flush_notify() did already call it. |
| */ |
| mmu_notifier_invalidate_range_only_end(&range); |
| if (old_page) { |
| if (page_copied) |
| free_swap_cache(old_page); |
| put_page(old_page); |
| } |
| |
| delayacct_wpcopy_end(); |
| return (page_copied && !unshare) ? VM_FAULT_WRITE : 0; |
| oom_free_new: |
| put_page(new_page); |
| oom: |
| if (old_page) |
| put_page(old_page); |
| |
| delayacct_wpcopy_end(); |
| return VM_FAULT_OOM; |
| } |
| |
| /** |
| * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE |
| * writeable once the page is prepared |
| * |
| * @vmf: structure describing the fault |
| * |
| * This function handles all that is needed to finish a write page fault in a |
| * shared mapping due to PTE being read-only once the mapped page is prepared. |
| * It handles locking of PTE and modifying it. |
| * |
| * The function expects the page to be locked or other protection against |
| * concurrent faults / writeback (such as DAX radix tree locks). |
| * |
| * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before |
| * we acquired PTE lock. |
| */ |
| vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf) |
| { |
| WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED)); |
| vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address, |
| &vmf->ptl); |
| /* |
| * We might have raced with another page fault while we released the |
| * pte_offset_map_lock. |
| */ |
| if (!pte_same(*vmf->pte, vmf->orig_pte)) { |
| update_mmu_tlb(vmf->vma, vmf->address, vmf->pte); |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return VM_FAULT_NOPAGE; |
| } |
| wp_page_reuse(vmf); |
| return 0; |
| } |
| |
| /* |
| * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED |
| * mapping |
| */ |
| static vm_fault_t wp_pfn_shared(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| |
| if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { |
| vm_fault_t ret; |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| vmf->flags |= FAULT_FLAG_MKWRITE; |
| ret = vma->vm_ops->pfn_mkwrite(vmf); |
| if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)) |
| return ret; |
| return finish_mkwrite_fault(vmf); |
| } |
| wp_page_reuse(vmf); |
| return VM_FAULT_WRITE; |
| } |
| |
| static vm_fault_t wp_page_shared(struct vm_fault *vmf) |
| __releases(vmf->ptl) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| vm_fault_t ret = VM_FAULT_WRITE; |
| |
| get_page(vmf->page); |
| |
| if (vma->vm_ops && vma->vm_ops->page_mkwrite) { |
| vm_fault_t tmp; |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| tmp = do_page_mkwrite(vmf); |
| if (unlikely(!tmp || (tmp & |
| (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { |
| put_page(vmf->page); |
| return tmp; |
| } |
| tmp = finish_mkwrite_fault(vmf); |
| if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { |
| unlock_page(vmf->page); |
| put_page(vmf->page); |
| return tmp; |
| } |
| } else { |
| wp_page_reuse(vmf); |
| lock_page(vmf->page); |
| } |
| ret |= fault_dirty_shared_page(vmf); |
| put_page(vmf->page); |
| |
| return ret; |
| } |
| |
| /* |
| * This routine handles present pages, when |
| * * users try to write to a shared page (FAULT_FLAG_WRITE) |
| * * GUP wants to take a R/O pin on a possibly shared anonymous page |
| * (FAULT_FLAG_UNSHARE) |
| * |
| * It is done by copying the page to a new address and decrementing the |
| * shared-page counter for the old page. |
| * |
| * Note that this routine assumes that the protection checks have been |
| * done by the caller (the low-level page fault routine in most cases). |
| * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've |
| * done any necessary COW. |
| * |
| * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even |
| * though the page will change only once the write actually happens. This |
| * avoids a few races, and potentially makes it more efficient. |
| * |
| * We enter with non-exclusive mmap_lock (to exclude vma changes, |
| * but allow concurrent faults), with pte both mapped and locked. |
| * We return with mmap_lock still held, but pte unmapped and unlocked. |
| */ |
| static vm_fault_t do_wp_page(struct vm_fault *vmf) |
| __releases(vmf->ptl) |
| { |
| const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; |
| struct vm_area_struct *vma = vmf->vma; |
| |
| VM_BUG_ON(unshare && (vmf->flags & FAULT_FLAG_WRITE)); |
| VM_BUG_ON(!unshare && !(vmf->flags & FAULT_FLAG_WRITE)); |
| |
| if (likely(!unshare)) { |
| if (userfaultfd_pte_wp(vma, *vmf->pte)) { |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return handle_userfault(vmf, VM_UFFD_WP); |
| } |
| |
| /* |
| * Userfaultfd write-protect can defer flushes. Ensure the TLB |
| * is flushed in this case before copying. |
| */ |
| if (unlikely(userfaultfd_wp(vmf->vma) && |
| mm_tlb_flush_pending(vmf->vma->vm_mm))) |
| flush_tlb_page(vmf->vma, vmf->address); |
| } |
| |
| vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte); |
| if (!vmf->page) { |
| if (unlikely(unshare)) { |
| /* No anonymous page -> nothing to do. */ |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return 0; |
| } |
| |
| /* |
| * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a |
| * VM_PFNMAP VMA. |
| * |
| * We should not cow pages in a shared writeable mapping. |
| * Just mark the pages writable and/or call ops->pfn_mkwrite. |
| */ |
| if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
| (VM_WRITE|VM_SHARED)) |
| return wp_pfn_shared(vmf); |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return wp_page_copy(vmf); |
| } |
| |
| /* |
| * Take out anonymous pages first, anonymous shared vmas are |
| * not dirty accountable. |
| */ |
| if (PageAnon(vmf->page)) { |
| struct page *page = vmf->page; |
| |
| /* |
| * If the page is exclusive to this process we must reuse the |
| * page without further checks. |
| */ |
| if (PageAnonExclusive(page)) |
| goto reuse; |
| |
| /* |
| * We have to verify under page lock: these early checks are |
| * just an optimization to avoid locking the page and freeing |
| * the swapcache if there is little hope that we can reuse. |
| * |
| * PageKsm() doesn't necessarily raise the page refcount. |
| */ |
| if (PageKsm(page) || page_count(page) > 3) |
| goto copy; |
| if (!PageLRU(page)) |
| /* |
| * Note: We cannot easily detect+handle references from |
| * remote LRU pagevecs or references to PageLRU() pages. |
| */ |
| lru_add_drain(); |
| if (page_count(page) > 1 + PageSwapCache(page)) |
| goto copy; |
| if (!trylock_page(page)) |
| goto copy; |
| if (PageSwapCache(page)) |
| try_to_free_swap(page); |
| if (PageKsm(page) || page_count(page) != 1) { |
| unlock_page(page); |
| goto copy; |
| } |
| /* |
| * Ok, we've got the only page reference from our mapping |
| * and the page is locked, it's dark out, and we're wearing |
| * sunglasses. Hit it. |
| */ |
| page_move_anon_rmap(page, vma); |
| unlock_page(page); |
| reuse: |
| if (unlikely(unshare)) { |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return 0; |
| } |
| wp_page_reuse(vmf); |
| return VM_FAULT_WRITE; |
| } else if (unshare) { |
| /* No anonymous page -> nothing to do. */ |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return 0; |
| } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
| (VM_WRITE|VM_SHARED))) { |
| return wp_page_shared(vmf); |
| } |
| copy: |
| /* |
| * Ok, we need to copy. Oh, well.. |
| */ |
| get_page(vmf->page); |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| #ifdef CONFIG_KSM |
| if (PageKsm(vmf->page)) |
| count_vm_event(COW_KSM); |
| #endif |
| return wp_page_copy(vmf); |
| } |
| |
| static void unmap_mapping_range_vma(struct vm_area_struct *vma, |
| unsigned long start_addr, unsigned long end_addr, |
| struct zap_details *details) |
| { |
| zap_page_range_single(vma, start_addr, end_addr - start_addr, details); |
| } |
| |
| static inline void unmap_mapping_range_tree(struct rb_root_cached *root, |
| pgoff_t first_index, |
| pgoff_t last_index, |
| struct zap_details *details) |
| { |
| struct vm_area_struct *vma; |
| pgoff_t vba, vea, zba, zea; |
| |
| vma_interval_tree_foreach(vma, root, first_index, last_index) { |
| vba = vma->vm_pgoff; |
| vea = vba + vma_pages(vma) - 1; |
| zba = max(first_index, vba); |
| zea = min(last_index, vea); |
| |
| unmap_mapping_range_vma(vma, |
| ((zba - vba) << PAGE_SHIFT) + vma->vm_start, |
| ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, |
| details); |
| } |
| } |
| |
| /** |
| * unmap_mapping_folio() - Unmap single folio from processes. |
| * @folio: The locked folio to be unmapped. |
| * |
| * Unmap this folio from any userspace process which still has it mmaped. |
| * Typically, for efficiency, the range of nearby pages has already been |
| * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once |
| * truncation or invalidation holds the lock on a folio, it may find that |
| * the page has been remapped again: and then uses unmap_mapping_folio() |
| * to unmap it finally. |
| */ |
| void unmap_mapping_folio(struct folio *folio) |
| { |
| struct address_space *mapping = folio->mapping; |
| struct zap_details details = { }; |
| pgoff_t first_index; |
| pgoff_t last_index; |
| |
| VM_BUG_ON(!folio_test_locked(folio)); |
| |
| first_index = folio->index; |
| last_index = folio->index + folio_nr_pages(folio) - 1; |
| |
| details.even_cows = false; |
| details.single_folio = folio; |
| details.zap_flags = ZAP_FLAG_DROP_MARKER; |
| |
| i_mmap_lock_read(mapping); |
| if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) |
| unmap_mapping_range_tree(&mapping->i_mmap, first_index, |
| last_index, &details); |
| i_mmap_unlock_read(mapping); |
| } |
| |
| /** |
| * unmap_mapping_pages() - Unmap pages from processes. |
| * @mapping: The address space containing pages to be unmapped. |
| * @start: Index of first page to be unmapped. |
| * @nr: Number of pages to be unmapped. 0 to unmap to end of file. |
| * @even_cows: Whether to unmap even private COWed pages. |
| * |
| * Unmap the pages in this address space from any userspace process which |
| * has them mmaped. Generally, you want to remove COWed pages as well when |
| * a file is being truncated, but not when invalidating pages from the page |
| * cache. |
| */ |
| void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, |
| pgoff_t nr, bool even_cows) |
| { |
| struct zap_details details = { }; |
| pgoff_t first_index = start; |
| pgoff_t last_index = start + nr - 1; |
| |
| details.even_cows = even_cows; |
| if (last_index < first_index) |
| last_index = ULONG_MAX; |
| |
| i_mmap_lock_read(mapping); |
| if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) |
| unmap_mapping_range_tree(&mapping->i_mmap, first_index, |
| last_index, &details); |
| i_mmap_unlock_read(mapping); |
| } |
| EXPORT_SYMBOL_GPL(unmap_mapping_pages); |
| |
| /** |
| * unmap_mapping_range - unmap the portion of all mmaps in the specified |
| * address_space corresponding to the specified byte range in the underlying |
| * file. |
| * |
| * @mapping: the address space containing mmaps to be unmapped. |
| * @holebegin: byte in first page to unmap, relative to the start of |
| * the underlying file. This will be rounded down to a PAGE_SIZE |
| * boundary. Note that this is different from truncate_pagecache(), which |
| * must keep the partial page. In contrast, we must get rid of |
| * partial pages. |
| * @holelen: size of prospective hole in bytes. This will be rounded |
| * up to a PAGE_SIZE boundary. A holelen of zero truncates to the |
| * end of the file. |
| * @even_cows: 1 when truncating a file, unmap even private COWed pages; |
| * but 0 when invalidating pagecache, don't throw away private data. |
| */ |
| void unmap_mapping_range(struct address_space *mapping, |
| loff_t const holebegin, loff_t const holelen, int even_cows) |
| { |
| pgoff_t hba = holebegin >> PAGE_SHIFT; |
| pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| |
| /* Check for overflow. */ |
| if (sizeof(holelen) > sizeof(hlen)) { |
| long long holeend = |
| (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| if (holeend & ~(long long)ULONG_MAX) |
| hlen = ULONG_MAX - hba + 1; |
| } |
| |
| unmap_mapping_pages(mapping, hba, hlen, even_cows); |
| } |
| EXPORT_SYMBOL(unmap_mapping_range); |
| |
| /* |
| * Restore a potential device exclusive pte to a working pte entry |
| */ |
| static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) |
| { |
| struct page *page = vmf->page; |
| struct vm_area_struct *vma = vmf->vma; |
| struct mmu_notifier_range range; |
| |
| if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) |
| return VM_FAULT_RETRY; |
| mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma, |
| vma->vm_mm, vmf->address & PAGE_MASK, |
| (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL); |
| mmu_notifier_invalidate_range_start(&range); |
| |
| vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, |
| &vmf->ptl); |
| if (likely(pte_same(*vmf->pte, vmf->orig_pte))) |
| restore_exclusive_pte(vma, page, vmf->address, vmf->pte); |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| unlock_page(page); |
| |
| mmu_notifier_invalidate_range_end(&range); |
| return 0; |
| } |
| |
| static inline bool should_try_to_free_swap(struct page *page, |
| struct vm_area_struct *vma, |
| unsigned int fault_flags) |
| { |
| if (!PageSwapCache(page)) |
| return false; |
| if (mem_cgroup_swap_full(page) || (vma->vm_flags & VM_LOCKED) || |
| PageMlocked(page)) |
| return true; |
| /* |
| * If we want to map a page that's in the swapcache writable, we |
| * have to detect via the refcount if we're really the exclusive |
| * user. Try freeing the swapcache to get rid of the swapcache |
| * reference only in case it's likely that we'll be the exlusive user. |
| */ |
| return (fault_flags & FAULT_FLAG_WRITE) && !PageKsm(page) && |
| page_count(page) == 2; |
| } |
| |
| static vm_fault_t pte_marker_clear(struct vm_fault *vmf) |
| { |
| vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, |
| vmf->address, &vmf->ptl); |
| /* |
| * Be careful so that we will only recover a special uffd-wp pte into a |
| * none pte. Otherwise it means the pte could have changed, so retry. |
| */ |
| if (is_pte_marker(*vmf->pte)) |
| pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte); |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return 0; |
| } |
| |
| /* |
| * This is actually a page-missing access, but with uffd-wp special pte |
| * installed. It means this pte was wr-protected before being unmapped. |
| */ |
| static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf) |
| { |
| /* |
| * Just in case there're leftover special ptes even after the region |
| * got unregistered - we can simply clear them. We can also do that |
| * proactively when e.g. when we do UFFDIO_UNREGISTER upon some uffd-wp |
| * ranges, but it should be more efficient to be done lazily here. |
| */ |
| if (unlikely(!userfaultfd_wp(vmf->vma) || vma_is_anonymous(vmf->vma))) |
| return pte_marker_clear(vmf); |
| |
| /* do_fault() can handle pte markers too like none pte */ |
| return do_fault(vmf); |
| } |
| |
| static vm_fault_t handle_pte_marker(struct vm_fault *vmf) |
| { |
| swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte); |
| unsigned long marker = pte_marker_get(entry); |
| |
| /* |
| * PTE markers should always be with file-backed memories, and the |
| * marker should never be empty. If anything weird happened, the best |
| * thing to do is to kill the process along with its mm. |
| */ |
| if (WARN_ON_ONCE(vma_is_anonymous(vmf->vma) || !marker)) |
| return VM_FAULT_SIGBUS; |
| |
| if (pte_marker_entry_uffd_wp(entry)) |
| return pte_marker_handle_uffd_wp(vmf); |
| |
| /* This is an unknown pte marker */ |
| return VM_FAULT_SIGBUS; |
| } |
| |
| /* |
| * We enter with non-exclusive mmap_lock (to exclude vma changes, |
| * but allow concurrent faults), and pte mapped but not yet locked. |
| * We return with pte unmapped and unlocked. |
| * |
| * We return with the mmap_lock locked or unlocked in the same cases |
| * as does filemap_fault(). |
| */ |
| vm_fault_t do_swap_page(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct page *page = NULL, *swapcache; |
| struct swap_info_struct *si = NULL; |
| rmap_t rmap_flags = RMAP_NONE; |
| bool exclusive = false; |
| swp_entry_t entry; |
| pte_t pte; |
| int locked; |
| vm_fault_t ret = 0; |
| void *shadow = NULL; |
| |
| if (!pte_unmap_same(vmf)) |
| goto out; |
| |
| entry = pte_to_swp_entry(vmf->orig_pte); |
| if (unlikely(non_swap_entry(entry))) { |
| if (is_migration_entry(entry)) { |
| migration_entry_wait(vma->vm_mm, vmf->pmd, |
| vmf->address); |
| } else if (is_device_exclusive_entry(entry)) { |
| vmf->page = pfn_swap_entry_to_page(entry); |
| ret = remove_device_exclusive_entry(vmf); |
| } else if (is_device_private_entry(entry)) { |
| vmf->page = pfn_swap_entry_to_page(entry); |
| ret = vmf->page->pgmap->ops->migrate_to_ram(vmf); |
| } else if (is_hwpoison_entry(entry)) { |
| ret = VM_FAULT_HWPOISON; |
| } else if (is_swapin_error_entry(entry)) { |
| ret = VM_FAULT_SIGBUS; |
| } else if (is_pte_marker_entry(entry)) { |
| ret = handle_pte_marker(vmf); |
| } else { |
| print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL); |
| ret = VM_FAULT_SIGBUS; |
| } |
| goto out; |
| } |
| |
| /* Prevent swapoff from happening to us. */ |
| si = get_swap_device(entry); |
| if (unlikely(!si)) |
| goto out; |
| |
| page = lookup_swap_cache(entry, vma, vmf->address); |
| swapcache = page; |
| |
| if (!page) { |
| if (data_race(si->flags & SWP_SYNCHRONOUS_IO) && |
| __swap_count(entry) == 1) { |
| /* skip swapcache */ |
| page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, |
| vmf->address); |
| if (page) { |
| __SetPageLocked(page); |
| __SetPageSwapBacked(page); |
| |
| if (mem_cgroup_swapin_charge_page(page, |
| vma->vm_mm, GFP_KERNEL, entry)) { |
| ret = VM_FAULT_OOM; |
| goto out_page; |
| } |
| mem_cgroup_swapin_uncharge_swap(entry); |
| |
| shadow = get_shadow_from_swap_cache(entry); |
| if (shadow) |
| workingset_refault(page_folio(page), |
| shadow); |
| |
| lru_cache_add(page); |
| |
| /* To provide entry to swap_readpage() */ |
| set_page_private(page, entry.val); |
| swap_readpage(page, true, NULL); |
| set_page_private(page, 0); |
| } |
| } else { |
| page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, |
| vmf); |
| swapcache = page; |
| } |
| |
| if (!page) { |
| /* |
| * Back out if somebody else faulted in this pte |
| * while we released the pte lock. |
| */ |
| vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, |
| vmf->address, &vmf->ptl); |
| if (likely(pte_same(*vmf->pte, vmf->orig_pte))) |
| ret = VM_FAULT_OOM; |
| goto unlock; |
| } |
| |
| /* Had to read the page from swap area: Major fault */ |
| ret = VM_FAULT_MAJOR; |
| count_vm_event(PGMAJFAULT); |
| count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); |
| } else if (PageHWPoison(page)) { |
| /* |
| * hwpoisoned dirty swapcache pages are kept for killing |
| * owner processes (which may be unknown at hwpoison time) |
| */ |
| ret = VM_FAULT_HWPOISON; |
| goto out_release; |
| } |
| |
| locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags); |
| |
| if (!locked) { |
| ret |= VM_FAULT_RETRY; |
| goto out_release; |
| } |
| |
| if (swapcache) { |
| /* |
| * Make sure try_to_free_swap or swapoff did not release the |
| * swapcache from under us. The page pin, and pte_same test |
| * below, are not enough to exclude that. Even if it is still |
| * swapcache, we need to check that the page's swap has not |
| * changed. |
| */ |
| if (unlikely(!PageSwapCache(page) || |
| page_private(page) != entry.val)) |
| goto out_page; |
| |
| /* |
| * KSM sometimes has to copy on read faults, for example, if |
| * page->index of !PageKSM() pages would be nonlinear inside the |
| * anon VMA -- PageKSM() is lost on actual swapout. |
| */ |
| page = ksm_might_need_to_copy(page, vma, vmf->address); |
| if (unlikely(!page)) { |
| ret = VM_FAULT_OOM; |
| page = swapcache; |
| goto out_page; |
| } |
| |
| /* |
| * If we want to map a page that's in the swapcache writable, we |
| * have to detect via the refcount if we're really the exclusive |
| * owner. Try removing the extra reference from the local LRU |
| * pagevecs if required. |
| */ |
| if ((vmf->flags & FAULT_FLAG_WRITE) && page == swapcache && |
| !PageKsm(page) && !PageLRU(page)) |
| lru_add_drain(); |
| } |
| |
| cgroup_throttle_swaprate(page, GFP_KERNEL); |
| |
| /* |
| * Back out if somebody else already faulted in this pte. |
| */ |
| vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, |
| &vmf->ptl); |
| if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) |
| goto out_nomap; |
| |
| if (unlikely(!PageUptodate(page))) { |
| ret = VM_FAULT_SIGBUS; |
| goto out_nomap; |
| } |
| |
| /* |
| * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte |
| * must never point at an anonymous page in the swapcache that is |
| * PG_anon_exclusive. Sanity check that this holds and especially, that |
| * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity |
| * check after taking the PT lock and making sure that nobody |
| * concurrently faulted in this page and set PG_anon_exclusive. |
| */ |
| BUG_ON(!PageAnon(page) && PageMappedToDisk(page)); |
| BUG_ON(PageAnon(page) && PageAnonExclusive(page)); |
| |
| /* |
| * Check under PT lock (to protect against concurrent fork() sharing |
| * the swap entry concurrently) for certainly exclusive pages. |
| */ |
| if (!PageKsm(page)) { |
| /* |
| * Note that pte_swp_exclusive() == false for architectures |
| * without __HAVE_ARCH_PTE_SWP_EXCLUSIVE. |
| */ |
| exclusive = pte_swp_exclusive(vmf->orig_pte); |
| if (page != swapcache) { |
| /* |
| * We have a fresh page that is not exposed to the |
| * swapcache -> certainly exclusive. |
| */ |
| exclusive = true; |
| } else if (exclusive && PageWriteback(page) && |
| data_race(si->flags & SWP_STABLE_WRITES)) { |
| /* |
| * This is tricky: not all swap backends support |
| * concurrent page modifications while under writeback. |
| * |
| * So if we stumble over such a page in the swapcache |
| * we must not set the page exclusive, otherwise we can |
| * map it writable without further checks and modify it |
| * while still under writeback. |
| * |
| * For these problematic swap backends, simply drop the |
| * exclusive marker: this is perfectly fine as we start |
| * writeback only if we fully unmapped the page and |
| * there are no unexpected references on the page after |
| * unmapping succeeded. After fully unmapped, no |
| * further GUP references (FOLL_GET and FOLL_PIN) can |
| * appear, so dropping the exclusive marker and mapping |
| * it only R/O is fine. |
| */ |
| exclusive = false; |
| } |
| } |
| |
| /* |
| * Remove the swap entry and conditionally try to free up the swapcache. |
| * We're already holding a reference on the page but haven't mapped it |
| * yet. |
| */ |
| swap_free(entry); |
| if (should_try_to_free_swap(page, vma, vmf->flags)) |
| try_to_free_swap(page); |
| |
| inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); |
| dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS); |
| pte = mk_pte(page, vma->vm_page_prot); |
| |
| /* |
| * Same logic as in do_wp_page(); however, optimize for pages that are |
| * certainly not shared either because we just allocated them without |
| * exposing them to the swapcache or because the swap entry indicates |
| * exclusivity. |
| */ |
| if (!PageKsm(page) && (exclusive || page_count(page) == 1)) { |
| if (vmf->flags & FAULT_FLAG_WRITE) { |
| pte = maybe_mkwrite(pte_mkdirty(pte), vma); |
| vmf->flags &= ~FAULT_FLAG_WRITE; |
| ret |= VM_FAULT_WRITE; |
| } |
| rmap_flags |= RMAP_EXCLUSIVE; |
| } |
| flush_icache_page(vma, page); |
| if (pte_swp_soft_dirty(vmf->orig_pte)) |
| pte = pte_mksoft_dirty(pte); |
| if (pte_swp_uffd_wp(vmf->orig_pte)) { |
| pte = pte_mkuffd_wp(pte); |
| pte = pte_wrprotect(pte); |
| } |
| vmf->orig_pte = pte; |
| |
| /* ksm created a completely new copy */ |
| if (unlikely(page != swapcache && swapcache)) { |
| page_add_new_anon_rmap(page, vma, vmf->address); |
| lru_cache_add_inactive_or_unevictable(page, vma); |
| } else { |
| page_add_anon_rmap(page, vma, vmf->address, rmap_flags); |
| } |
| |
| VM_BUG_ON(!PageAnon(page) || (pte_write(pte) && !PageAnonExclusive(page))); |
| set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); |
| arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte); |
| |
| unlock_page(page); |
| if (page != swapcache && swapcache) { |
| /* |
| * Hold the lock to avoid the swap entry to be reused |
| * until we take the PT lock for the pte_same() check |
| * (to avoid false positives from pte_same). For |
| * further safety release the lock after the swap_free |
| * so that the swap count won't change under a |
| * parallel locked swapcache. |
| */ |
| unlock_page(swapcache); |
| put_page(swapcache); |
| } |
| |
| if (vmf->flags & FAULT_FLAG_WRITE) { |
| ret |= do_wp_page(vmf); |
| if (ret & VM_FAULT_ERROR) |
| ret &= VM_FAULT_ERROR; |
| goto out; |
| } |
| |
| /* No need to invalidate - it was non-present before */ |
| update_mmu_cache(vma, vmf->address, vmf->pte); |
| unlock: |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| out: |
| if (si) |
| put_swap_device(si); |
| return ret; |
| out_nomap: |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| out_page: |
| unlock_page(page); |
| out_release: |
| put_page(page); |
| if (page != swapcache && swapcache) { |
| unlock_page(swapcache); |
| put_page(swapcache); |
| } |
| if (si) |
| put_swap_device(si); |
| return ret; |
| } |
| |
| /* |
| * We enter with non-exclusive mmap_lock (to exclude vma changes, |
| * but allow concurrent faults), and pte mapped but not yet locked. |
| * We return with mmap_lock still held, but pte unmapped and unlocked. |
| */ |
| static vm_fault_t do_anonymous_page(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct page *page; |
| vm_fault_t ret = 0; |
| pte_t entry; |
| |
| /* File mapping without ->vm_ops ? */ |
| if (vma->vm_flags & VM_SHARED) |
| return VM_FAULT_SIGBUS; |
| |
| /* |
| * Use pte_alloc() instead of pte_alloc_map(). We can't run |
| * pte_offset_map() on pmds where a huge pmd might be created |
| * from a different thread. |
| * |
| * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when |
| * parallel threads are excluded by other means. |
| * |
| * Here we only have mmap_read_lock(mm). |
| */ |
| if (pte_alloc(vma->vm_mm, vmf->pmd)) |
| return VM_FAULT_OOM; |
| |
| /* See comment in handle_pte_fault() */ |
| if (unlikely(pmd_trans_unstable(vmf->pmd))) |
| return 0; |
| |
| /* Use the zero-page for reads */ |
| if (!(vmf->flags & FAULT_FLAG_WRITE) && |
| !mm_forbids_zeropage(vma->vm_mm)) { |
| entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address), |
| vma->vm_page_prot)); |
| vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, |
| vmf->address, &vmf->ptl); |
| if (!pte_none(*vmf->pte)) { |
| update_mmu_tlb(vma, vmf->address, vmf->pte); |
| goto unlock; |
| } |
| ret = check_stable_address_space(vma->vm_mm); |
| if (ret) |
| goto unlock; |
| /* Deliver the page fault to userland, check inside PT lock */ |
| if (userfaultfd_missing(vma)) { |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return handle_userfault(vmf, VM_UFFD_MISSING); |
| } |
| goto setpte; |
| } |
| |
| /* Allocate our own private page. */ |
| if (unlikely(anon_vma_prepare(vma))) |
| goto oom; |
| page = alloc_zeroed_user_highpage_movable(vma, vmf->address); |
| if (!page) |
| goto oom; |
| |
| if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL)) |
| goto oom_free_page; |
| cgroup_throttle_swaprate(page, GFP_KERNEL); |
| |
| /* |
| * The memory barrier inside __SetPageUptodate makes sure that |
| * preceding stores to the page contents become visible before |
| * the set_pte_at() write. |
| */ |
| __SetPageUptodate(page); |
| |
| entry = mk_pte(page, vma->vm_page_prot); |
| entry = pte_sw_mkyoung(entry); |
| if (vma->vm_flags & VM_WRITE) |
| entry = pte_mkwrite(pte_mkdirty(entry)); |
| |
| vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, |
| &vmf->ptl); |
| if (!pte_none(*vmf->pte)) { |
| update_mmu_cache(vma, vmf->address, vmf->pte); |
| goto release; |
| } |
| |
| ret = check_stable_address_space(vma->vm_mm); |
| if (ret) |
| goto release; |
| |
| /* Deliver the page fault to userland, check inside PT lock */ |
| if (userfaultfd_missing(vma)) { |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| put_page(page); |
| return handle_userfault(vmf, VM_UFFD_MISSING); |
| } |
| |
| inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); |
| page_add_new_anon_rmap(page, vma, vmf->address); |
| lru_cache_add_inactive_or_unevictable(page, vma); |
| setpte: |
| set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); |
| |
| /* No need to invalidate - it was non-present before */ |
| update_mmu_cache(vma, vmf->address, vmf->pte); |
| unlock: |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return ret; |
| release: |
| put_page(page); |
| goto unlock; |
| oom_free_page: |
| put_page(page); |
| oom: |
| return VM_FAULT_OOM; |
| } |
| |
| /* |
| * The mmap_lock must have been held on entry, and may have been |
| * released depending on flags and vma->vm_ops->fault() return value. |
| * See filemap_fault() and __lock_page_retry(). |
| */ |
| static vm_fault_t __do_fault(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| vm_fault_t ret; |
| |
| /* |
| * Preallocate pte before we take page_lock because this might lead to |
| * deadlocks for memcg reclaim which waits for pages under writeback: |
| * lock_page(A) |
| * SetPageWriteback(A) |
| * unlock_page(A) |
| * lock_page(B) |
| * lock_page(B) |
| * pte_alloc_one |
| * shrink_page_list |
| * wait_on_page_writeback(A) |
| * SetPageWriteback(B) |
| * unlock_page(B) |
| * # flush A, B to clear the writeback |
| */ |
| if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) { |
| vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); |
| if (!vmf->prealloc_pte) |
| return VM_FAULT_OOM; |
| } |
| |
| ret = vma->vm_ops->fault(vmf); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY | |
| VM_FAULT_DONE_COW))) |
| return ret; |
| |
| if (unlikely(PageHWPoison(vmf->page))) { |
| struct page *page = vmf->page; |
| vm_fault_t poisonret = VM_FAULT_HWPOISON; |
| if (ret & VM_FAULT_LOCKED) { |
| if (page_mapped(page)) |
| unmap_mapping_pages(page_mapping(page), |
| page->index, 1, false); |
| /* Retry if a clean page was removed from the cache. */ |
| if (invalidate_inode_page(page)) |
| poisonret = VM_FAULT_NOPAGE; |
| unlock_page(page); |
| } |
| put_page(page); |
| vmf->page = NULL; |
| return poisonret; |
| } |
| |
| if (unlikely(!(ret & VM_FAULT_LOCKED))) |
| lock_page(vmf->page); |
| else |
| VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page); |
| |
| return ret; |
| } |
| |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| static void deposit_prealloc_pte(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| |
| pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); |
| /* |
| * We are going to consume the prealloc table, |
| * count that as nr_ptes. |
| */ |
| mm_inc_nr_ptes(vma->vm_mm); |
| vmf->prealloc_pte = NULL; |
| } |
| |
| vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| bool write = vmf->flags & FAULT_FLAG_WRITE; |
| unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
| pmd_t entry; |
| int i; |
| vm_fault_t ret = VM_FAULT_FALLBACK; |
| |
| if (!transhuge_vma_suitable(vma, haddr)) |
| return ret; |
| |
| page = compound_head(page); |
| if (compound_order(page) != HPAGE_PMD_ORDER) |
| return ret; |
| |
| /* |
| * Just backoff if any subpage of a THP is corrupted otherwise |
| * the corrupted page may mapped by PMD silently to escape the |
| * check. This kind of THP just can be PTE mapped. Access to |
| * the corrupted subpage should trigger SIGBUS as expected. |
| */ |
| if (unlikely(PageHasHWPoisoned(page))) |
| return ret; |
| |
| /* |
| * Archs like ppc64 need additional space to store information |
| * related to pte entry. Use the preallocated table for that. |
| */ |
| if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) { |
| vmf->prealloc_pte = pte_alloc_one(vma->vm_mm); |
| if (!vmf->prealloc_pte) |
| return VM_FAULT_OOM; |
| } |
| |
| vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
| if (unlikely(!pmd_none(*vmf->pmd))) |
| goto out; |
| |
| for (i = 0; i < HPAGE_PMD_NR; i++) |
| flush_icache_page(vma, page + i); |
| |
| entry = mk_huge_pmd(page, vma->vm_page_prot); |
| if (write) |
| entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
| |
| add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR); |
| page_add_file_rmap(page, vma, true); |
| |
| /* |
| * deposit and withdraw with pmd lock held |
| */ |
| if (arch_needs_pgtable_deposit()) |
| deposit_prealloc_pte(vmf); |
| |
| set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); |
| |
| update_mmu_cache_pmd(vma, haddr, vmf->pmd); |
| |
| /* fault is handled */ |
| ret = 0; |
| count_vm_event(THP_FILE_MAPPED); |
| out: |
| spin_unlock(vmf->ptl); |
| return ret; |
| } |
| #else |
| vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) |
| { |
| return VM_FAULT_FALLBACK; |
| } |
| #endif |
| |
| void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| bool uffd_wp = pte_marker_uffd_wp(vmf->orig_pte); |
| bool write = vmf->flags & FAULT_FLAG_WRITE; |
| bool prefault = vmf->address != addr; |
| pte_t entry; |
| |
| flush_icache_page(vma, page); |
| entry = mk_pte(page, vma->vm_page_prot); |
| |
| if (prefault && arch_wants_old_prefaulted_pte()) |
| entry = pte_mkold(entry); |
| else |
| entry = pte_sw_mkyoung(entry); |
| |
| if (write) |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| if (unlikely(uffd_wp)) |
| entry = pte_mkuffd_wp(pte_wrprotect(entry)); |
| /* copy-on-write page */ |
| if (write && !(vma->vm_flags & VM_SHARED)) { |
| inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); |
| page_add_new_anon_rmap(page, vma, addr); |
| lru_cache_add_inactive_or_unevictable(page, vma); |
| } else { |
| inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page)); |
| page_add_file_rmap(page, vma, false); |
| } |
| set_pte_at(vma->vm_mm, addr, vmf->pte, entry); |
| } |
| |
| static bool vmf_pte_changed(struct vm_fault *vmf) |
| { |
| if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID) |
| return !pte_same(*vmf->pte, vmf->orig_pte); |
| |
| return !pte_none(*vmf->pte); |
| } |
| |
| /** |
| * finish_fault - finish page fault once we have prepared the page to fault |
| * |
| * @vmf: structure describing the fault |
| * |
| * This function handles all that is needed to finish a page fault once the |
| * page to fault in is prepared. It handles locking of PTEs, inserts PTE for |
| * given page, adds reverse page mapping, handles memcg charges and LRU |
| * addition. |
| * |
| * The function expects the page to be locked and on success it consumes a |
| * reference of a page being mapped (for the PTE which maps it). |
| * |
| * Return: %0 on success, %VM_FAULT_ code in case of error. |
| */ |
| vm_fault_t finish_fault(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct page *page; |
| vm_fault_t ret; |
| |
| /* Did we COW the page? */ |
| if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) |
| page = vmf->cow_page; |
| else |
| page = vmf->page; |
| |
| /* |
| * check even for read faults because we might have lost our CoWed |
| * page |
| */ |
| if (!(vma->vm_flags & VM_SHARED)) { |
| ret = check_stable_address_space(vma->vm_mm); |
| if (ret) |
| return ret; |
| } |
| |
| if (pmd_none(*vmf->pmd)) { |
| if (PageTransCompound(page)) { |
| ret = do_set_pmd(vmf, page); |
| if (ret != VM_FAULT_FALLBACK) |
| return ret; |
| } |
| |
| if (vmf->prealloc_pte) |
| pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte); |
| else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) |
| return VM_FAULT_OOM; |
| } |
| |
| /* |
| * See comment in handle_pte_fault() for how this scenario happens, we |
| * need to return NOPAGE so that we drop this page. |
| */ |
| if (pmd_devmap_trans_unstable(vmf->pmd)) |
| return VM_FAULT_NOPAGE; |
| |
| vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, |
| vmf->address, &vmf->ptl); |
| |
| /* Re-check under ptl */ |
| if (likely(!vmf_pte_changed(vmf))) { |
| do_set_pte(vmf, page, vmf->address); |
| |
| /* no need to invalidate: a not-present page won't be cached */ |
| update_mmu_cache(vma, vmf->address, vmf->pte); |
| |
| ret = 0; |
| } else { |
| update_mmu_tlb(vma, vmf->address, vmf->pte); |
| ret = VM_FAULT_NOPAGE; |
| } |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return ret; |
| } |
| |
| static unsigned long fault_around_bytes __read_mostly = |
| rounddown_pow_of_two(65536); |
| |
| #ifdef CONFIG_DEBUG_FS |
| static int fault_around_bytes_get(void *data, u64 *val) |
| { |
| *val = fault_around_bytes; |
| return 0; |
| } |
| |
| /* |
| * fault_around_bytes must be rounded down to the nearest page order as it's |
| * what do_fault_around() expects to see. |
| */ |
| static int fault_around_bytes_set(void *data, u64 val) |
| { |
| if (val / PAGE_SIZE > PTRS_PER_PTE) |
| return -EINVAL; |
| if (val > PAGE_SIZE) |
| fault_around_bytes = rounddown_pow_of_two(val); |
| else |
| fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */ |
| return 0; |
| } |
| DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops, |
| fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); |
| |
| static int __init fault_around_debugfs(void) |
| { |
| debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL, |
| &fault_around_bytes_fops); |
| return 0; |
| } |
| late_initcall(fault_around_debugfs); |
| #endif |
| |
| /* |
| * do_fault_around() tries to map few pages around the fault address. The hope |
| * is that the pages will be needed soon and this will lower the number of |
| * faults to handle. |
| * |
| * It uses vm_ops->map_pages() to map the pages, which skips the page if it's |
| * not ready to be mapped: not up-to-date, locked, etc. |
| * |
| * This function doesn't cross the VMA boundaries, in order to call map_pages() |
| * only once. |
| * |
| * fault_around_bytes defines how many bytes we'll try to map. |
| * do_fault_around() expects it to be set to a power of two less than or equal |
| * to PTRS_PER_PTE. |
| * |
| * The virtual address of the area that we map is naturally aligned to |
| * fault_around_bytes rounded down to the machine page size |
| * (and therefore to page order). This way it's easier to guarantee |
| * that we don't cross page table boundaries. |
| */ |
| static vm_fault_t do_fault_around(struct vm_fault *vmf) |
| { |
| unsigned long address = vmf->address, nr_pages, mask; |
| pgoff_t start_pgoff = vmf->pgoff; |
| pgoff_t end_pgoff; |
| int off; |
| |
| nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT; |
| mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK; |
| |
| address = max(address & mask, vmf->vma->vm_start); |
| off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); |
| start_pgoff -= off; |
| |
| /* |
| * end_pgoff is either the end of the page table, the end of |
| * the vma or nr_pages from start_pgoff, depending what is nearest. |
| */ |
| end_pgoff = start_pgoff - |
| ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + |
| PTRS_PER_PTE - 1; |
| end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1, |
| start_pgoff + nr_pages - 1); |
| |
| if (pmd_none(*vmf->pmd)) { |
| vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm); |
| if (!vmf->prealloc_pte) |
| return VM_FAULT_OOM; |
| } |
| |
| return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); |
| } |
| |
| /* Return true if we should do read fault-around, false otherwise */ |
| static inline bool should_fault_around(struct vm_fault *vmf) |
| { |
| /* No ->map_pages? No way to fault around... */ |
| if (!vmf->vma->vm_ops->map_pages) |
| return false; |
| |
| if (uffd_disable_fault_around(vmf->vma)) |
| return false; |
| |
| return fault_around_bytes >> PAGE_SHIFT > 1; |
| } |
| |
| static vm_fault_t do_read_fault(struct vm_fault *vmf) |
| { |
| vm_fault_t ret = 0; |
| |
| /* |
| * Let's call ->map_pages() first and use ->fault() as fallback |
| * if page by the offset is not ready to be mapped (cold cache or |
| * something). |
| */ |
| if (should_fault_around(vmf)) { |
| ret = do_fault_around(vmf); |
| if (ret) |
| return ret; |
| } |
| |
| ret = __do_fault(vmf); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| return ret; |
| |
| ret |= finish_fault(vmf); |
| unlock_page(vmf->page); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| put_page(vmf->page); |
| return ret; |
| } |
| |
| static vm_fault_t do_cow_fault(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| vm_fault_t ret; |
| |
| if (unlikely(anon_vma_prepare(vma))) |
| return VM_FAULT_OOM; |
| |
| vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); |
| if (!vmf->cow_page) |
| return VM_FAULT_OOM; |
| |
| if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm, |
| GFP_KERNEL)) { |
| put_page(vmf->cow_page); |
| return VM_FAULT_OOM; |
| } |
| cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL); |
| |
| ret = __do_fault(vmf); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| goto uncharge_out; |
| if (ret & VM_FAULT_DONE_COW) |
| return ret; |
| |
| copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma); |
| __SetPageUptodate(vmf->cow_page); |
| |
| ret |= finish_fault(vmf); |
| unlock_page(vmf->page); |
| put_page(vmf->page); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| goto uncharge_out; |
| return ret; |
| uncharge_out: |
| put_page(vmf->cow_page); |
| return ret; |
| } |
| |
| static vm_fault_t do_shared_fault(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| vm_fault_t ret, tmp; |
| |
| ret = __do_fault(vmf); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) |
| return ret; |
| |
| /* |
| * Check if the backing address space wants to know that the page is |
| * about to become writable |
| */ |
| if (vma->vm_ops->page_mkwrite) { |
| unlock_page(vmf->page); |
| tmp = do_page_mkwrite(vmf); |
| if (unlikely(!tmp || |
| (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { |
| put_page(vmf->page); |
| return tmp; |
| } |
| } |
| |
| ret |= finish_fault(vmf); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | |
| VM_FAULT_RETRY))) { |
| unlock_page(vmf->page); |
| put_page(vmf->page); |
| return ret; |
| } |
| |
| ret |= fault_dirty_shared_page(vmf); |
| return ret; |
| } |
| |
| /* |
| * We enter with non-exclusive mmap_lock (to exclude vma changes, |
| * but allow concurrent faults). |
| * The mmap_lock may have been released depending on flags and our |
| * return value. See filemap_fault() and __folio_lock_or_retry(). |
| * If mmap_lock is released, vma may become invalid (for example |
| * by other thread calling munmap()). |
| */ |
| static vm_fault_t do_fault(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct mm_struct *vm_mm = vma->vm_mm; |
| vm_fault_t ret; |
| |
| /* |
| * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND |
| */ |
| if (!vma->vm_ops->fault) { |
| /* |
| * If we find a migration pmd entry or a none pmd entry, which |
| * should never happen, return SIGBUS |
| */ |
| if (unlikely(!pmd_present(*vmf->pmd))) |
| ret = VM_FAULT_SIGBUS; |
| else { |
| vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, |
| vmf->pmd, |
| vmf->address, |
| &vmf->ptl); |
| /* |
| * Make sure this is not a temporary clearing of pte |
| * by holding ptl and checking again. A R/M/W update |
| * of pte involves: take ptl, clearing the pte so that |
| * we don't have concurrent modification by hardware |
| * followed by an update. |
| */ |
| if (unlikely(pte_none(*vmf->pte))) |
| ret = VM_FAULT_SIGBUS; |
| else |
| ret = VM_FAULT_NOPAGE; |
| |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| } |
| } else if (!(vmf->flags & FAULT_FLAG_WRITE)) |
| ret = do_read_fault(vmf); |
| else if (!(vma->vm_flags & VM_SHARED)) |
| ret = do_cow_fault(vmf); |
| else |
| ret = do_shared_fault(vmf); |
| |
| /* preallocated pagetable is unused: free it */ |
| if (vmf->prealloc_pte) { |
| pte_free(vm_mm, vmf->prealloc_pte); |
| vmf->prealloc_pte = NULL; |
| } |
| return ret; |
| } |
| |
| int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, |
| unsigned long addr, int page_nid, int *flags) |
| { |
| get_page(page); |
| |
| count_vm_numa_event(NUMA_HINT_FAULTS); |
| if (page_nid == numa_node_id()) { |
| count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
| *flags |= TNF_FAULT_LOCAL; |
| } |
| |
| return mpol_misplaced(page, vma, addr); |
| } |
| |
| static vm_fault_t do_numa_page(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct page *page = NULL; |
| int page_nid = NUMA_NO_NODE; |
| int last_cpupid; |
| int target_nid; |
| pte_t pte, old_pte; |
| bool was_writable = pte_savedwrite(vmf->orig_pte); |
| int flags = 0; |
| |
| /* |
| * The "pte" at this point cannot be used safely without |
| * validation through pte_unmap_same(). It's of NUMA type but |
| * the pfn may be screwed if the read is non atomic. |
| */ |
| vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd); |
| spin_lock(vmf->ptl); |
| if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| goto out; |
| } |
| |
| /* Get the normal PTE */ |
| old_pte = ptep_get(vmf->pte); |
| pte = pte_modify(old_pte, vma->vm_page_prot); |
| |
| page = vm_normal_page(vma, vmf->address, pte); |
| if (!page || is_zone_device_page(page)) |
| goto out_map; |
| |
| /* TODO: handle PTE-mapped THP */ |
| if (PageCompound(page)) |
| goto out_map; |
| |
| /* |
| * Avoid grouping on RO pages in general. RO pages shouldn't hurt as |
| * much anyway since they can be in shared cache state. This misses |
| * the case where a mapping is writable but the process never writes |
| * to it but pte_write gets cleared during protection updates and |
| * pte_dirty has unpredictable behaviour between PTE scan updates, |
| * background writeback, dirty balancing and application behaviour. |
| */ |
| if (!was_writable) |
| flags |= TNF_NO_GROUP; |
| |
| /* |
| * Flag if the page is shared between multiple address spaces. This |
| * is later used when determining whether to group tasks together |
| */ |
| if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) |
| flags |= TNF_SHARED; |
| |
| page_nid = page_to_nid(page); |
| /* |
| * For memory tiering mode, cpupid of slow memory page is used |
| * to record page access time. So use default value. |
| */ |
| if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) && |
| !node_is_toptier(page_nid)) |
| last_cpupid = (-1 & LAST_CPUPID_MASK); |
| else |
| last_cpupid = page_cpupid_last(page); |
| target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid, |
| &flags); |
| if (target_nid == NUMA_NO_NODE) { |
| put_page(page); |
| goto out_map; |
| } |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| |
| /* Migrate to the requested node */ |
| if (migrate_misplaced_page(page, vma, target_nid)) { |
| page_nid = target_nid; |
| flags |= TNF_MIGRATED; |
| } else { |
| flags |= TNF_MIGRATE_FAIL; |
| vmf->pte = pte_offset_map(vmf->pmd, vmf->address); |
| spin_lock(vmf->ptl); |
| if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| goto out; |
| } |
| goto out_map; |
| } |
| |
| out: |
| if (page_nid != NUMA_NO_NODE) |
| task_numa_fault(last_cpupid, page_nid, 1, flags); |
| return 0; |
| out_map: |
| /* |
| * Make it present again, depending on how arch implements |
| * non-accessible ptes, some can allow access by kernel mode. |
| */ |
| old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte); |
| pte = pte_modify(old_pte, vma->vm_page_prot); |
| pte = pte_mkyoung(pte); |
| if (was_writable) |
| pte = pte_mkwrite(pte); |
| ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte); |
| update_mmu_cache(vma, vmf->address, vmf->pte); |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| goto out; |
| } |
| |
| static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) |
| { |
| if (vma_is_anonymous(vmf->vma)) |
| return do_huge_pmd_anonymous_page(vmf); |
| if (vmf->vma->vm_ops->huge_fault) |
| return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); |
| return VM_FAULT_FALLBACK; |
| } |
| |
| /* `inline' is required to avoid gcc 4.1.2 build error */ |
| static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) |
| { |
| const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; |
| |
| if (vma_is_anonymous(vmf->vma)) { |
| if (likely(!unshare) && |
| userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd)) |
| return handle_userfault(vmf, VM_UFFD_WP); |
| return do_huge_pmd_wp_page(vmf); |
| } |
| if (vmf->vma->vm_ops->huge_fault) { |
| vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); |
| |
| if (!(ret & VM_FAULT_FALLBACK)) |
| return ret; |
| } |
| |
| /* COW or write-notify handled on pte level: split pmd. */ |
| __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL); |
| |
| return VM_FAULT_FALLBACK; |
| } |
| |
| static vm_fault_t create_huge_pud(struct vm_fault *vmf) |
| { |
| #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ |
| defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) |
| /* No support for anonymous transparent PUD pages yet */ |
| if (vma_is_anonymous(vmf->vma)) |
| return VM_FAULT_FALLBACK; |
| if (vmf->vma->vm_ops->huge_fault) |
| return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); |
| #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
| return VM_FAULT_FALLBACK; |
| } |
| |
| static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) |
| { |
| #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ |
| defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) |
| /* No support for anonymous transparent PUD pages yet */ |
| if (vma_is_anonymous(vmf->vma)) |
| goto split; |
| if (vmf->vma->vm_ops->huge_fault) { |
| vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); |
| |
| if (!(ret & VM_FAULT_FALLBACK)) |
| return ret; |
| } |
| split: |
| /* COW or write-notify not handled on PUD level: split pud.*/ |
| __split_huge_pud(vmf->vma, vmf->pud, vmf->address); |
| #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ |
| return VM_FAULT_FALLBACK; |
| } |
| |
| /* |
| * These routines also need to handle stuff like marking pages dirty |
| * and/or accessed for architectures that don't do it in hardware (most |
| * RISC architectures). The early dirtying is also good on the i386. |
| * |
| * There is also a hook called "update_mmu_cache()" that architectures |
| * with external mmu caches can use to update those (ie the Sparc or |
| * PowerPC hashed page tables that act as extended TLBs). |
| * |
| * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow |
| * concurrent faults). |
| * |
| * The mmap_lock may have been released depending on flags and our return value. |
| * See filemap_fault() and __folio_lock_or_retry(). |
| */ |
| static vm_fault_t handle_pte_fault(struct vm_fault *vmf) |
| { |
| pte_t entry; |
| |
| if (unlikely(pmd_none(*vmf->pmd))) { |
| /* |
| * Leave __pte_alloc() until later: because vm_ops->fault may |
| * want to allocate huge page, and if we expose page table |
| * for an instant, it will be difficult to retract from |
| * concurrent faults and from rmap lookups. |
| */ |
| vmf->pte = NULL; |
| vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID; |
| } else { |
| /* |
| * If a huge pmd materialized under us just retry later. Use |
| * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead |
| * of pmd_trans_huge() to ensure the pmd didn't become |
| * pmd_trans_huge under us and then back to pmd_none, as a |
| * result of MADV_DONTNEED running immediately after a huge pmd |
| * fault in a different thread of this mm, in turn leading to a |
| * misleading pmd_trans_huge() retval. All we have to ensure is |
| * that it is a regular pmd that we can walk with |
| * pte_offset_map() and we can do that through an atomic read |
| * in C, which is what pmd_trans_unstable() provides. |
| */ |
| if (pmd_devmap_trans_unstable(vmf->pmd)) |
| return 0; |
| /* |
| * A regular pmd is established and it can't morph into a huge |
| * pmd from under us anymore at this point because we hold the |
| * mmap_lock read mode and khugepaged takes it in write mode. |
| * So now it's safe to run pte_offset_map(). |
| */ |
| vmf->pte = pte_offset_map(vmf->pmd, vmf->address); |
| vmf->orig_pte = *vmf->pte; |
| vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID; |
| |
| /* |
| * some architectures can have larger ptes than wordsize, |
| * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and |
| * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic |
| * accesses. The code below just needs a consistent view |
| * for the ifs and we later double check anyway with the |
| * ptl lock held. So here a barrier will do. |
| */ |
| barrier(); |
| if (pte_none(vmf->orig_pte)) { |
| pte_unmap(vmf->pte); |
| vmf->pte = NULL; |
| } |
| } |
| |
| if (!vmf->pte) { |
| if (vma_is_anonymous(vmf->vma)) |
| return do_anonymous_page(vmf); |
| else |
| return do_fault(vmf); |
| } |
| |
| if (!pte_present(vmf->orig_pte)) |
| return do_swap_page(vmf); |
| |
| if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma)) |
| return do_numa_page(vmf); |
| |
| vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); |
| spin_lock(vmf->ptl); |
| entry = vmf->orig_pte; |
| if (unlikely(!pte_same(*vmf->pte, entry))) { |
| update_mmu_tlb(vmf->vma, vmf->address, vmf->pte); |
| goto unlock; |
| } |
| if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) { |
| if (!pte_write(entry)) |
| return do_wp_page(vmf); |
| else if (likely(vmf->flags & FAULT_FLAG_WRITE)) |
| entry = pte_mkdirty(entry); |
| } |
| entry = pte_mkyoung(entry); |
| if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry, |
| vmf->flags & FAULT_FLAG_WRITE)) { |
| update_mmu_cache(vmf->vma, vmf->address, vmf->pte); |
| } else { |
| /* Skip spurious TLB flush for retried page fault */ |
| if (vmf->flags & FAULT_FLAG_TRIED) |
| goto unlock; |
| /* |
| * This is needed only for protection faults but the arch code |
| * is not yet telling us if this is a protection fault or not. |
| * This still avoids useless tlb flushes for .text page faults |
| * with threads. |
| */ |
| if (vmf->flags & FAULT_FLAG_WRITE) |
| flush_tlb_fix_spurious_fault(vmf->vma, vmf->address); |
| } |
| unlock: |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| return 0; |
| } |
| |
| /* |
| * By the time we get here, we already hold the mm semaphore |
| * |
| * The mmap_lock may have been released depending on flags and our |
| * return value. See filemap_fault() and __folio_lock_or_retry(). |
| */ |
| static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, |
| unsigned long address, unsigned int flags) |
| { |
| struct vm_fault vmf = { |
| .vma = vma, |
| .address = address & PAGE_MASK, |
| .real_address = address, |
| .flags = flags, |
| .pgoff = linear_page_index(vma, address), |
| .gfp_mask = __get_fault_gfp_mask(vma), |
| }; |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long vm_flags = vma->vm_flags; |
| pgd_t *pgd; |
| p4d_t *p4d; |
| vm_fault_t ret; |
| |
| pgd = pgd_offset(mm, address); |
| p4d = p4d_alloc(mm, pgd, address); |
| if (!p4d) |
| return VM_FAULT_OOM; |
| |
| vmf.pud = pud_alloc(mm, p4d, address); |
| if (!vmf.pud) |
| return VM_FAULT_OOM; |
| retry_pud: |
| if (pud_none(*vmf.pud) && |
| hugepage_vma_check(vma, vm_flags, false, true, true)) { |
| ret = create_huge_pud(&vmf); |
| if (!(ret & VM_FAULT_FALLBACK)) |
| return ret; |
| } else { |
| pud_t orig_pud = *vmf.pud; |
| |
| barrier(); |
| if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) { |
| |
| /* |
| * TODO once we support anonymous PUDs: NUMA case and |
| * FAULT_FLAG_UNSHARE handling. |
| */ |
| if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) { |
| ret = wp_huge_pud(&vmf, orig_pud); |
| if (!(ret & VM_FAULT_FALLBACK)) |
| return ret; |
| } else { |
| huge_pud_set_accessed(&vmf, orig_pud); |
| return 0; |
| } |
| } |
| } |
| |
| vmf.pmd = pmd_alloc(mm, vmf.pud, address); |
| if (!vmf.pmd) |
| return VM_FAULT_OOM; |
| |
| /* Huge pud page fault raced with pmd_alloc? */ |
| if (pud_trans_unstable(vmf.pud)) |
| goto retry_pud; |
| |
| if (pmd_none(*vmf.pmd) && |
| hugepage_vma_check(vma, vm_flags, false, true, true)) { |
| ret = create_huge_pmd(&vmf); |
| if (!(ret & VM_FAULT_FALLBACK)) |
| return ret; |
| } else { |
| vmf.orig_pmd = *vmf.pmd; |
| |
| barrier(); |
| if (unlikely(is_swap_pmd(vmf.orig_pmd))) { |
| VM_BUG_ON(thp_migration_supported() && |
| !is_pmd_migration_entry(vmf.orig_pmd)); |
| if (is_pmd_migration_entry(vmf.orig_pmd)) |
| pmd_migration_entry_wait(mm, vmf.pmd); |
| return 0; |
| } |
| if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) { |
| if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma)) |
| return do_huge_pmd_numa_page(&vmf); |
| |
| if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) && |
| !pmd_write(vmf.orig_pmd)) { |
| ret = wp_huge_pmd(&vmf); |
| if (!(ret & VM_FAULT_FALLBACK)) |
| return ret; |
| } else { |
| huge_pmd_set_accessed(&vmf); |
| return 0; |
| } |
| } |
| } |
| |
| return handle_pte_fault(&vmf); |
| } |
| |
| /** |
| * mm_account_fault - Do page fault accounting |
| * |
| * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting |
| * of perf event counters, but we'll still do the per-task accounting to |
| * the task who triggered this page fault. |
| * @address: the faulted address. |
| * @flags: the fault flags. |
| * @ret: the fault retcode. |
| * |
| * This will take care of most of the page fault accounting. Meanwhile, it |
| * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter |
| * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should |
| * still be in per-arch page fault handlers at the entry of page fault. |
| */ |
| static inline void mm_account_fault(struct pt_regs *regs, |
| unsigned long address, unsigned int flags, |
| vm_fault_t ret) |
| { |
| bool major; |
| |
| /* |
| * We don't do accounting for some specific faults: |
| * |
| * - Unsuccessful faults (e.g. when the address wasn't valid). That |
| * includes arch_vma_access_permitted() failing before reaching here. |
| * So this is not a "this many hardware page faults" counter. We |
| * should use the hw profiling for that. |
| * |
| * - Incomplete faults (VM_FAULT_RETRY). They will only be counted |
| * once they're completed. |
| */ |
| if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY)) |
| return; |
| |
| /* |
| * We define the fault as a major fault when the final successful fault |
| * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't |
| * handle it immediately previously). |
| */ |
| major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED); |
| |
| if (major) |
| current->maj_flt++; |
| else |
| current->min_flt++; |
| |
| /* |
| * If the fault is done for GUP, regs will be NULL. We only do the |
| * accounting for the per thread fault counters who triggered the |
| * fault, and we skip the perf event updates. |
| */ |
| if (!regs) |
| return; |
| |
| if (major) |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); |
| else |
| perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); |
| } |
| |
| #ifdef CONFIG_LRU_GEN |
| static void lru_gen_enter_fault(struct vm_area_struct *vma) |
| { |
| /* the LRU algorithm doesn't apply to sequential or random reads */ |
| current->in_lru_fault = !(vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ)); |
| } |
| |
| static void lru_gen_exit_fault(void) |
| { |
| current->in_lru_fault = false; |
| } |
| #else |
| static void lru_gen_enter_fault(struct vm_area_struct *vma) |
| { |
| } |
| |
| static void lru_gen_exit_fault(void) |
| { |
| } |
| #endif /* CONFIG_LRU_GEN */ |
| |
| /* |
| * By the time we get here, we already hold the mm semaphore |
| * |
| * The mmap_lock may have been released depending on flags and our |
| * return value. See filemap_fault() and __folio_lock_or_retry(). |
| */ |
| vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, |
| unsigned int flags, struct pt_regs *regs) |
| { |
| vm_fault_t ret; |
| |
| __set_current_state(TASK_RUNNING); |
| |
| count_vm_event(PGFAULT); |
| count_memcg_event_mm(vma->vm_mm, PGFAULT); |
| |
| /* do counter updates before entering really critical section. */ |
| check_sync_rss_stat(current); |
| |
| if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, |
| flags & FAULT_FLAG_INSTRUCTION, |
| flags & FAULT_FLAG_REMOTE)) |
| return VM_FAULT_SIGSEGV; |
| |
| /* |
| * Enable the memcg OOM handling for faults triggered in user |
| * space. Kernel faults are handled more gracefully. |
| */ |
| if (flags & FAULT_FLAG_USER) |
| mem_cgroup_enter_user_fault(); |
| |
| lru_gen_enter_fault(vma); |
| |
| if (unlikely(is_vm_hugetlb_page(vma))) |
| ret = hugetlb_fault(vma->vm_mm, vma, address, flags); |
| else |
| ret = __handle_mm_fault(vma, address, flags); |
| |
| lru_gen_exit_fault(); |
| |
| if (flags & FAULT_FLAG_USER) { |
| mem_cgroup_exit_user_fault(); |
| /* |
| * The task may have entered a memcg OOM situation but |
| * if the allocation error was handled gracefully (no |
| * VM_FAULT_OOM), there is no need to kill anything. |
| * Just clean up the OOM state peacefully. |
| */ |
| if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) |
| mem_cgroup_oom_synchronize(false); |
| } |
| |
| mm_account_fault(regs, address, flags, ret); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(handle_mm_fault); |
| |
| #ifndef __PAGETABLE_P4D_FOLDED |
| /* |
| * Allocate p4d page table. |
| * We've already handled the fast-path in-line. |
| */ |
| int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) |
| { |
| p4d_t *new = p4d_alloc_one(mm, address); |
| if (!new) |
| return -ENOMEM; |
| |
| spin_lock(&mm->page_table_lock); |
| if (pgd_present(*pgd)) { /* Another has populated it */ |
| p4d_free(mm, new); |
| } else { |
| smp_wmb(); /* See comment in pmd_install() */ |
| pgd_populate(mm, pgd, new); |
| } |
| spin_unlock(&mm->page_table_lock); |
| return 0; |
| } |
| #endif /* __PAGETABLE_P4D_FOLDED */ |
| |
| #ifndef __PAGETABLE_PUD_FOLDED |
| /* |
| * Allocate page upper directory. |
| * We've already handled the fast-path in-line. |
| */ |
| int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address) |
| { |
| pud_t *new = pud_alloc_one(mm, address); |
| if (!new) |
| return -ENOMEM; |
| |
| spin_lock(&mm->page_table_lock); |
| if (!p4d_present(*p4d)) { |
| mm_inc_nr_puds(mm); |
| smp_wmb(); /* See comment in pmd_install() */ |
| p4d_populate(mm, p4d, new); |
| } else /* Another has populated it */ |
| pud_free(mm, new); |
| spin_unlock(&mm->page_table_lock); |
| return 0; |
| } |
| #endif /* __PAGETABLE_PUD_FOLDED */ |
| |
| #ifndef __PAGETABLE_PMD_FOLDED |
| /* |
| * Allocate page middle directory. |
| * We've already handled the fast-path in-line. |
| */ |
| int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) |
| { |
| spinlock_t *ptl; |
| pmd_t *new = pmd_alloc_one(mm, address); |
| if (!new) |
| return -ENOMEM; |
| |
| ptl = pud_lock(mm, pud); |
| if (!pud_present(*pud)) { |
| mm_inc_nr_pmds(mm); |
| smp_wmb(); /* See comment in pmd_install() */ |
| pud_populate(mm, pud, new); |
| } else { /* Another has populated it */ |
| pmd_free(mm, new); |
| } |
| spin_unlock(ptl); |
| return 0; |
| } |
| #endif /* __PAGETABLE_PMD_FOLDED */ |
| |
| /** |
| * follow_pte - look up PTE at a user virtual address |
| * @mm: the mm_struct of the target address space |
| * @address: user virtual address |
| * @ptepp: location to store found PTE |
| * @ptlp: location to store the lock for the PTE |
| * |
| * On a successful return, the pointer to the PTE is stored in @ptepp; |
| * the corresponding lock is taken and its location is stored in @ptlp. |
| * The contents of the PTE are only stable until @ptlp is released; |
| * any further use, if any, must be protected against invalidation |
| * with MMU notifiers. |
| * |
| * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore |
| * should be taken for read. |
| * |
| * KVM uses this function. While it is arguably less bad than ``follow_pfn``, |
| * it is not a good general-purpose API. |
| * |
| * Return: zero on success, -ve otherwise. |
| */ |
| int follow_pte(struct mm_struct *mm, unsigned long address, |
| pte_t **ptepp, spinlock_t **ptlp) |
| { |
| pgd_t *pgd; |
| p4d_t *p4d; |
| pud_t *pud; |
| pmd_t *pmd; |
| pte_t *ptep; |
| |
| pgd = pgd_offset(mm, address); |
| if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
| goto out; |
| |
| p4d = p4d_offset(pgd, address); |
| if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d))) |
| goto out; |
| |
| pud = pud_offset(p4d, address); |
| if (pud_none(*pud) || unlikely(pud_bad(*pud))) |
| goto out; |
| |
| pmd = pmd_offset(pud, address); |
| VM_BUG_ON(pmd_trans_huge(*pmd)); |
| |
| if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) |
| goto out; |
| |
| ptep = pte_offset_map_lock(mm, pmd, address, ptlp); |
| if (!pte_present(*ptep)) |
| goto unlock; |
| *ptepp = ptep; |
| return 0; |
| unlock: |
| pte_unmap_unlock(ptep, *ptlp); |
| out: |
| return -EINVAL; |
| } |
| EXPORT_SYMBOL_GPL(follow_pte); |
| |
| /** |
| * follow_pfn - look up PFN at a user virtual address |
| * @vma: memory mapping |
| * @address: user virtual address |
| * @pfn: location to store found PFN |
| * |
| * Only IO mappings and raw PFN mappings are allowed. |
| * |
| * This function does not allow the caller to read the permissions |
| * of the PTE. Do not use it. |
| * |
| * Return: zero and the pfn at @pfn on success, -ve otherwise. |
| */ |
| int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
| unsigned long *pfn) |
| { |
| int ret = -EINVAL; |
| spinlock_t *ptl; |
| pte_t *ptep; |
| |
| if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| return ret; |
| |
| ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); |
| if (ret) |
| return ret; |
| *pfn = pte_pfn(*ptep); |
| pte_unmap_unlock(ptep, ptl); |
| return 0; |
| } |
| EXPORT_SYMBOL(follow_pfn); |
| |
| #ifdef CONFIG_HAVE_IOREMAP_PROT |
| int follow_phys(struct vm_area_struct *vma, |
| unsigned long address, unsigned int flags, |
| unsigned long *prot, resource_size_t *phys) |
| { |
| int ret = -EINVAL; |
| pte_t *ptep, pte; |
| spinlock_t *ptl; |
| |
| if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| goto out; |
| |
| if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) |
| goto out; |
| pte = *ptep; |
| |
| if ((flags & FOLL_WRITE) && !pte_write(pte)) |
| goto unlock; |
| |
| *prot = pgprot_val(pte_pgprot(pte)); |
| *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; |
| |
| ret = 0; |
| unlock: |
| pte_unmap_unlock(ptep, ptl); |
| out: |
| return ret; |
| } |
| |
| /** |
| * generic_access_phys - generic implementation for iomem mmap access |
| * @vma: the vma to access |
| * @addr: userspace address, not relative offset within @vma |
| * @buf: buffer to read/write |
| * @len: length of transfer |
| * @write: set to FOLL_WRITE when writing, otherwise reading |
| * |
| * This is a generic implementation for &vm_operations_struct.access for an |
| * iomem mapping. This callback is used by access_process_vm() when the @vma is |
| * not page based. |
| */ |
| int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, |
| void *buf, int len, int write) |
| { |
| resource_size_t phys_addr; |
| unsigned long prot = 0; |
| void __iomem *maddr; |
| pte_t *ptep, pte; |
| spinlock_t *ptl; |
| int offset = offset_in_page(addr); |
| int ret = -EINVAL; |
| |
| if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| return -EINVAL; |
| |
| retry: |
| if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) |
| return -EINVAL; |
| pte = *ptep; |
| pte_unmap_unlock(ptep, ptl); |
| |
| prot = pgprot_val(pte_pgprot(pte)); |
| phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; |
| |
| if ((write & FOLL_WRITE) && !pte_write(pte)) |
| return -EINVAL; |
| |
| maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot); |
| if (!maddr) |
| return -ENOMEM; |
| |
| if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) |
| goto out_unmap; |
| |
| if (!pte_same(pte, *ptep)) { |
| pte_unmap_unlock(ptep, ptl); |
| iounmap(maddr); |
| |
| goto retry; |
| } |
| |
| if (write) |
| memcpy_toio(maddr + offset, buf, len); |
| else |
| memcpy_fromio(buf, maddr + offset, len); |
| ret = len; |
| pte_unmap_unlock(ptep, ptl); |
| out_unmap: |
| iounmap(maddr); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(generic_access_phys); |
| #endif |
| |
| /* |
| * Access another process' address space as given in mm. |
| */ |
| int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, |
| int len, unsigned int gup_flags) |
| { |
| struct vm_area_struct *vma; |
| void *old_buf = buf; |
| int write = gup_flags & FOLL_WRITE; |
| |
| if (mmap_read_lock_killable(mm)) |
| return 0; |
| |
| /* ignore errors, just check how much was successfully transferred */ |
| while (len) { |
| int bytes, ret, offset; |
| void *maddr; |
| struct page *page = NULL; |
| |
| ret = get_user_pages_remote(mm, addr, 1, |
| gup_flags, &page, &vma, NULL); |
| if (ret <= 0) { |
| #ifndef CONFIG_HAVE_IOREMAP_PROT |
| break; |
| #else |
| /* |
| * Check if this is a VM_IO | VM_PFNMAP VMA, which |
| * we can access using slightly different code. |
| */ |
| vma = vma_lookup(mm, addr); |
| if (!vma) |
| break; |
| if (vma->vm_ops && vma->vm_ops->access) |
| ret = vma->vm_ops->access(vma, addr, buf, |
| len, write); |
| if (ret <= 0) |
| break; |
| bytes = ret; |
| #endif |
| } else { |
| bytes = len; |
| offset = addr & (PAGE_SIZE-1); |
| if (bytes > PAGE_SIZE-offset) |
| bytes = PAGE_SIZE-offset; |
| |
| maddr = kmap(page); |
| if (write) { |
| copy_to_user_page(vma, page, addr, |
| maddr + offset, buf, bytes); |
| set_page_dirty_lock(page); |
| } else { |
| copy_from_user_page(vma, page, addr, |
| buf, maddr + offset, bytes); |
| } |
| kunmap(page); |
| put_page(page); |
| } |
| len -= bytes; |
| buf += bytes; |
| addr += bytes; |
| } |
| mmap_read_unlock(mm); |
| |
| return buf - old_buf; |
| } |
| |
| /** |
| * access_remote_vm - access another process' address space |
| * @mm: the mm_struct of the target address space |
| * @addr: start address to access |
| * @buf: source or destination buffer |
| * @len: number of bytes to transfer |
| * @gup_flags: flags modifying lookup behaviour |
| * |
| * The caller must hold a reference on @mm. |
| * |
| * Return: number of bytes copied from source to destination. |
| */ |
| int access_remote_vm(struct mm_struct *mm, unsigned long addr, |
| void *buf, int len, unsigned int gup_flags) |
| { |
| return __access_remote_vm(mm, addr, buf, len, gup_flags); |
| } |
| |
| /* |
| * Access another process' address space. |
| * Source/target buffer must be kernel space, |
| * Do not walk the page table directly, use get_user_pages |
| */ |
| int access_process_vm(struct task_struct *tsk, unsigned long addr, |
| void *buf, int len, unsigned int gup_flags) |
| { |
| struct mm_struct *mm; |
| int ret; |
| |
| mm = get_task_mm(tsk); |
| if (!mm) |
| return 0; |
| |
| ret = __access_remote_vm(mm, addr, buf, len, gup_flags); |
| |
| mmput(mm); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(access_process_vm); |
| |
| /* |
| * Print the name of a VMA. |
| */ |
| void print_vma_addr(char *prefix, unsigned long ip) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| |
| /* |
| * we might be running from an atomic context so we cannot sleep |
| */ |
| if (!mmap_read_trylock(mm)) |
| return; |
| |
| vma = find_vma(mm, ip); |
| if (vma && vma->vm_file) { |
| struct file *f = vma->vm_file; |
| char *buf = (char *)__get_free_page(GFP_NOWAIT); |
| if (buf) { |
| char *p; |
| |
| p = file_path(f, buf, PAGE_SIZE); |
| if (IS_ERR(p)) |
| p = "?"; |
| printk("%s%s[%lx+%lx]", prefix, kbasename(p), |
| vma->vm_start, |
| vma->vm_end - vma->vm_start); |
| free_page((unsigned long)buf); |
| } |
| } |
| mmap_read_unlock(mm); |
| } |
| |
| #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) |
| void __might_fault(const char *file, int line) |
| { |
| if (pagefault_disabled()) |
| return; |
| __might_sleep(file, line); |
| #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) |
| if (current->mm) |
| might_lock_read(¤t->mm->mmap_lock); |
| #endif |
| } |
| EXPORT_SYMBOL(__might_fault); |
| #endif |
| |
| #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) |
| /* |
| * Process all subpages of the specified huge page with the specified |
| * operation. The target subpage will be processed last to keep its |
| * cache lines hot. |
| */ |
| static inline void process_huge_page( |
| unsigned long addr_hint, unsigned int pages_per_huge_page, |
| void (*process_subpage)(unsigned long addr, int idx, void *arg), |
| void *arg) |
| { |
| int i, n, base, l; |
| unsigned long addr = addr_hint & |
| ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); |
| |
| /* Process target subpage last to keep its cache lines hot */ |
| might_sleep(); |
| n = (addr_hint - addr) / PAGE_SIZE; |
| if (2 * n <= pages_per_huge_page) { |
| /* If target subpage in first half of huge page */ |
| base = 0; |
| l = n; |
| /* Process subpages at the end of huge page */ |
| for (i = pages_per_huge_page - 1; i >= 2 * n; i--) { |
| cond_resched(); |
| process_subpage(addr + i * PAGE_SIZE, i, arg); |
| } |
| } else { |
| /* If target subpage in second half of huge page */ |
| base = pages_per_huge_page - 2 * (pages_per_huge_page - n); |
| l = pages_per_huge_page - n; |
| /* Process subpages at the begin of huge page */ |
| for (i = 0; i < base; i++) { |
| cond_resched(); |
| process_subpage(addr + i * PAGE_SIZE, i, arg); |
| } |
| } |
| /* |
| * Process remaining subpages in left-right-left-right pattern |
| * towards the target subpage |
| */ |
| for (i = 0; i < l; i++) { |
| int left_idx = base + i; |
| int right_idx = base + 2 * l - 1 - i; |
| |
| cond_resched(); |
| process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg); |
| cond_resched(); |
| process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg); |
| } |
| } |
| |
| static void clear_gigantic_page(struct page *page, |
| unsigned long addr, |
| unsigned int pages_per_huge_page) |
| { |
| int i; |
| struct page *p = page; |
| |
| might_sleep(); |
| for (i = 0; i < pages_per_huge_page; |
| i++, p = mem_map_next(p, page, i)) { |
| cond_resched(); |
| clear_user_highpage(p, addr + i * PAGE_SIZE); |
| } |
| } |
| |
| static void clear_subpage(unsigned long addr, int idx, void *arg) |
| { |
| struct page *page = arg; |
| |
| clear_user_highpage(page + idx, addr); |
| } |
| |
| void clear_huge_page(struct page *page, |
| unsigned long addr_hint, unsigned int pages_per_huge_page) |
| { |
| unsigned long addr = addr_hint & |
| ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); |
| |
| if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { |
| clear_gigantic_page(page, addr, pages_per_huge_page); |
| return; |
| } |
| |
| process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page); |
| } |
| |
| static void copy_user_gigantic_page(struct page *dst, struct page *src, |
| unsigned long addr, |
| struct vm_area_struct *vma, |
| unsigned int pages_per_huge_page) |
| { |
| int i; |
| struct page *dst_base = dst; |
| struct page *src_base = src; |
| |
| for (i = 0; i < pages_per_huge_page; ) { |
| cond_resched(); |
| copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); |
| |
| i++; |
| dst = mem_map_next(dst, dst_base, i); |
| src = mem_map_next(src, src_base, i); |
| } |
| } |
| |
| struct copy_subpage_arg { |
| struct page *dst; |
| struct page *src; |
| struct vm_area_struct *vma; |
| }; |
| |
| static void copy_subpage(unsigned long addr, int idx, void *arg) |
| { |
| struct copy_subpage_arg *copy_arg = arg; |
| |
| copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx, |
| addr, copy_arg->vma); |
| } |
| |
| void copy_user_huge_page(struct page *dst, struct page *src, |
| unsigned long addr_hint, struct vm_area_struct *vma, |
| unsigned int pages_per_huge_page) |
| { |
| unsigned long addr = addr_hint & |
| ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); |
| struct copy_subpage_arg arg = { |
| .dst = dst, |
| .src = src, |
| .vma = vma, |
| }; |
| |
| if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { |
| copy_user_gigantic_page(dst, src, addr, vma, |
| pages_per_huge_page); |
| return; |
| } |
| |
| process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg); |
| } |
| |
| long copy_huge_page_from_user(struct page *dst_page, |
| const void __user *usr_src, |
| unsigned int pages_per_huge_page, |
| bool allow_pagefault) |
| { |
| void *page_kaddr; |
| unsigned long i, rc = 0; |
| unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; |
| struct page *subpage = dst_page; |
| |
| for (i = 0; i < pages_per_huge_page; |
| i++, subpage = mem_map_next(subpage, dst_page, i)) { |
| if (allow_pagefault) |
| page_kaddr = kmap(subpage); |
| else |
| page_kaddr = kmap_atomic(subpage); |
| rc = copy_from_user(page_kaddr, |
| usr_src + i * PAGE_SIZE, PAGE_SIZE); |
| if (allow_pagefault) |
| kunmap(subpage); |
| else |
| kunmap_atomic(page_kaddr); |
| |
| ret_val -= (PAGE_SIZE - rc); |
| if (rc) |
| break; |
| |
| flush_dcache_page(subpage); |
| |
| cond_resched(); |
| } |
| return ret_val; |
| } |
| #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ |
| |
| #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS |
| |
| static struct kmem_cache *page_ptl_cachep; |
| |
| void __init ptlock_cache_init(void) |
| { |
| page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, |
| SLAB_PANIC, NULL); |
| } |
| |
| bool ptlock_alloc(struct page *page) |
| { |
| spinlock_t *ptl; |
| |
| ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); |
| if (!ptl) |
| return false; |
| page->ptl = ptl; |
| return true; |
| } |
| |
| void ptlock_free(struct page *page) |
| { |
| kmem_cache_free(page_ptl_cachep, page->ptl); |
| } |
| #endif |