| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * mm/mmap.c |
| * |
| * Written by obz. |
| * |
| * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/kernel.h> |
| #include <linux/slab.h> |
| #include <linux/backing-dev.h> |
| #include <linux/mm.h> |
| #include <linux/mm_inline.h> |
| #include <linux/shm.h> |
| #include <linux/mman.h> |
| #include <linux/pagemap.h> |
| #include <linux/swap.h> |
| #include <linux/syscalls.h> |
| #include <linux/capability.h> |
| #include <linux/init.h> |
| #include <linux/file.h> |
| #include <linux/fs.h> |
| #include <linux/personality.h> |
| #include <linux/security.h> |
| #include <linux/hugetlb.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/profile.h> |
| #include <linux/export.h> |
| #include <linux/mount.h> |
| #include <linux/mempolicy.h> |
| #include <linux/rmap.h> |
| #include <linux/mmu_notifier.h> |
| #include <linux/mmdebug.h> |
| #include <linux/perf_event.h> |
| #include <linux/audit.h> |
| #include <linux/khugepaged.h> |
| #include <linux/uprobes.h> |
| #include <linux/notifier.h> |
| #include <linux/memory.h> |
| #include <linux/printk.h> |
| #include <linux/userfaultfd_k.h> |
| #include <linux/moduleparam.h> |
| #include <linux/pkeys.h> |
| #include <linux/oom.h> |
| #include <linux/sched/mm.h> |
| #include <linux/ksm.h> |
| |
| #include <linux/uaccess.h> |
| #include <asm/cacheflush.h> |
| #include <asm/tlb.h> |
| #include <asm/mmu_context.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/mmap.h> |
| |
| #include "internal.h" |
| |
| #ifndef arch_mmap_check |
| #define arch_mmap_check(addr, len, flags) (0) |
| #endif |
| |
| #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS |
| const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; |
| const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; |
| int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; |
| #endif |
| #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; |
| const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; |
| int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; |
| #endif |
| |
| static bool ignore_rlimit_data; |
| core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); |
| |
| static void unmap_region(struct mm_struct *mm, struct ma_state *mas, |
| struct vm_area_struct *vma, struct vm_area_struct *prev, |
| struct vm_area_struct *next, unsigned long start, |
| unsigned long end, unsigned long tree_end, bool mm_wr_locked); |
| |
| static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) |
| { |
| return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); |
| } |
| |
| /* Update vma->vm_page_prot to reflect vma->vm_flags. */ |
| void vma_set_page_prot(struct vm_area_struct *vma) |
| { |
| unsigned long vm_flags = vma->vm_flags; |
| pgprot_t vm_page_prot; |
| |
| vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); |
| if (vma_wants_writenotify(vma, vm_page_prot)) { |
| vm_flags &= ~VM_SHARED; |
| vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags); |
| } |
| /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */ |
| WRITE_ONCE(vma->vm_page_prot, vm_page_prot); |
| } |
| |
| /* |
| * Requires inode->i_mapping->i_mmap_rwsem |
| */ |
| static void __remove_shared_vm_struct(struct vm_area_struct *vma, |
| struct file *file, struct address_space *mapping) |
| { |
| if (vma->vm_flags & VM_SHARED) |
| mapping_unmap_writable(mapping); |
| |
| flush_dcache_mmap_lock(mapping); |
| vma_interval_tree_remove(vma, &mapping->i_mmap); |
| flush_dcache_mmap_unlock(mapping); |
| } |
| |
| /* |
| * Unlink a file-based vm structure from its interval tree, to hide |
| * vma from rmap and vmtruncate before freeing its page tables. |
| */ |
| void unlink_file_vma(struct vm_area_struct *vma) |
| { |
| struct file *file = vma->vm_file; |
| |
| if (file) { |
| struct address_space *mapping = file->f_mapping; |
| i_mmap_lock_write(mapping); |
| __remove_shared_vm_struct(vma, file, mapping); |
| i_mmap_unlock_write(mapping); |
| } |
| } |
| |
| /* |
| * Close a vm structure and free it. |
| */ |
| static void remove_vma(struct vm_area_struct *vma, bool unreachable) |
| { |
| might_sleep(); |
| if (vma->vm_ops && vma->vm_ops->close) |
| vma->vm_ops->close(vma); |
| if (vma->vm_file) |
| fput(vma->vm_file); |
| mpol_put(vma_policy(vma)); |
| if (unreachable) |
| __vm_area_free(vma); |
| else |
| vm_area_free(vma); |
| } |
| |
| static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi, |
| unsigned long min) |
| { |
| return mas_prev(&vmi->mas, min); |
| } |
| |
| /* |
| * check_brk_limits() - Use platform specific check of range & verify mlock |
| * limits. |
| * @addr: The address to check |
| * @len: The size of increase. |
| * |
| * Return: 0 on success. |
| */ |
| static int check_brk_limits(unsigned long addr, unsigned long len) |
| { |
| unsigned long mapped_addr; |
| |
| mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); |
| if (IS_ERR_VALUE(mapped_addr)) |
| return mapped_addr; |
| |
| return mlock_future_ok(current->mm, current->mm->def_flags, len) |
| ? 0 : -EAGAIN; |
| } |
| static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma, |
| unsigned long addr, unsigned long request, unsigned long flags); |
| SYSCALL_DEFINE1(brk, unsigned long, brk) |
| { |
| unsigned long newbrk, oldbrk, origbrk; |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *brkvma, *next = NULL; |
| unsigned long min_brk; |
| bool populate = false; |
| LIST_HEAD(uf); |
| struct vma_iterator vmi; |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| origbrk = mm->brk; |
| |
| #ifdef CONFIG_COMPAT_BRK |
| /* |
| * CONFIG_COMPAT_BRK can still be overridden by setting |
| * randomize_va_space to 2, which will still cause mm->start_brk |
| * to be arbitrarily shifted |
| */ |
| if (current->brk_randomized) |
| min_brk = mm->start_brk; |
| else |
| min_brk = mm->end_data; |
| #else |
| min_brk = mm->start_brk; |
| #endif |
| if (brk < min_brk) |
| goto out; |
| |
| /* |
| * Check against rlimit here. If this check is done later after the test |
| * of oldbrk with newbrk then it can escape the test and let the data |
| * segment grow beyond its set limit the in case where the limit is |
| * not page aligned -Ram Gupta |
| */ |
| if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, |
| mm->end_data, mm->start_data)) |
| goto out; |
| |
| newbrk = PAGE_ALIGN(brk); |
| oldbrk = PAGE_ALIGN(mm->brk); |
| if (oldbrk == newbrk) { |
| mm->brk = brk; |
| goto success; |
| } |
| |
| /* Always allow shrinking brk. */ |
| if (brk <= mm->brk) { |
| /* Search one past newbrk */ |
| vma_iter_init(&vmi, mm, newbrk); |
| brkvma = vma_find(&vmi, oldbrk); |
| if (!brkvma || brkvma->vm_start >= oldbrk) |
| goto out; /* mapping intersects with an existing non-brk vma. */ |
| /* |
| * mm->brk must be protected by write mmap_lock. |
| * do_vma_munmap() will drop the lock on success, so update it |
| * before calling do_vma_munmap(). |
| */ |
| mm->brk = brk; |
| if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true)) |
| goto out; |
| |
| goto success_unlocked; |
| } |
| |
| if (check_brk_limits(oldbrk, newbrk - oldbrk)) |
| goto out; |
| |
| /* |
| * Only check if the next VMA is within the stack_guard_gap of the |
| * expansion area |
| */ |
| vma_iter_init(&vmi, mm, oldbrk); |
| next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap); |
| if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) |
| goto out; |
| |
| brkvma = vma_prev_limit(&vmi, mm->start_brk); |
| /* Ok, looks good - let it rip. */ |
| if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0) |
| goto out; |
| |
| mm->brk = brk; |
| if (mm->def_flags & VM_LOCKED) |
| populate = true; |
| |
| success: |
| mmap_write_unlock(mm); |
| success_unlocked: |
| userfaultfd_unmap_complete(mm, &uf); |
| if (populate) |
| mm_populate(oldbrk, newbrk - oldbrk); |
| return brk; |
| |
| out: |
| mm->brk = origbrk; |
| mmap_write_unlock(mm); |
| return origbrk; |
| } |
| |
| #if defined(CONFIG_DEBUG_VM_MAPLE_TREE) |
| static void validate_mm(struct mm_struct *mm) |
| { |
| int bug = 0; |
| int i = 0; |
| struct vm_area_struct *vma; |
| VMA_ITERATOR(vmi, mm, 0); |
| |
| mt_validate(&mm->mm_mt); |
| for_each_vma(vmi, vma) { |
| #ifdef CONFIG_DEBUG_VM_RB |
| struct anon_vma *anon_vma = vma->anon_vma; |
| struct anon_vma_chain *avc; |
| #endif |
| unsigned long vmi_start, vmi_end; |
| bool warn = 0; |
| |
| vmi_start = vma_iter_addr(&vmi); |
| vmi_end = vma_iter_end(&vmi); |
| if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm)) |
| warn = 1; |
| |
| if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm)) |
| warn = 1; |
| |
| if (warn) { |
| pr_emerg("issue in %s\n", current->comm); |
| dump_stack(); |
| dump_vma(vma); |
| pr_emerg("tree range: %px start %lx end %lx\n", vma, |
| vmi_start, vmi_end - 1); |
| vma_iter_dump_tree(&vmi); |
| } |
| |
| #ifdef CONFIG_DEBUG_VM_RB |
| if (anon_vma) { |
| anon_vma_lock_read(anon_vma); |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| anon_vma_interval_tree_verify(avc); |
| anon_vma_unlock_read(anon_vma); |
| } |
| #endif |
| i++; |
| } |
| if (i != mm->map_count) { |
| pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i); |
| bug = 1; |
| } |
| VM_BUG_ON_MM(bug, mm); |
| } |
| |
| #else /* !CONFIG_DEBUG_VM_MAPLE_TREE */ |
| #define validate_mm(mm) do { } while (0) |
| #endif /* CONFIG_DEBUG_VM_MAPLE_TREE */ |
| |
| /* |
| * vma has some anon_vma assigned, and is already inserted on that |
| * anon_vma's interval trees. |
| * |
| * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the |
| * vma must be removed from the anon_vma's interval trees using |
| * anon_vma_interval_tree_pre_update_vma(). |
| * |
| * After the update, the vma will be reinserted using |
| * anon_vma_interval_tree_post_update_vma(). |
| * |
| * The entire update must be protected by exclusive mmap_lock and by |
| * the root anon_vma's mutex. |
| */ |
| static inline void |
| anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) |
| { |
| struct anon_vma_chain *avc; |
| |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); |
| } |
| |
| static inline void |
| anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) |
| { |
| struct anon_vma_chain *avc; |
| |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); |
| } |
| |
| static unsigned long count_vma_pages_range(struct mm_struct *mm, |
| unsigned long addr, unsigned long end) |
| { |
| VMA_ITERATOR(vmi, mm, addr); |
| struct vm_area_struct *vma; |
| unsigned long nr_pages = 0; |
| |
| for_each_vma_range(vmi, vma, end) { |
| unsigned long vm_start = max(addr, vma->vm_start); |
| unsigned long vm_end = min(end, vma->vm_end); |
| |
| nr_pages += PHYS_PFN(vm_end - vm_start); |
| } |
| |
| return nr_pages; |
| } |
| |
| static void __vma_link_file(struct vm_area_struct *vma, |
| struct address_space *mapping) |
| { |
| if (vma->vm_flags & VM_SHARED) |
| mapping_allow_writable(mapping); |
| |
| flush_dcache_mmap_lock(mapping); |
| vma_interval_tree_insert(vma, &mapping->i_mmap); |
| flush_dcache_mmap_unlock(mapping); |
| } |
| |
| static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) |
| { |
| VMA_ITERATOR(vmi, mm, 0); |
| struct address_space *mapping = NULL; |
| |
| vma_iter_config(&vmi, vma->vm_start, vma->vm_end); |
| if (vma_iter_prealloc(&vmi, vma)) |
| return -ENOMEM; |
| |
| vma_start_write(vma); |
| |
| vma_iter_store(&vmi, vma); |
| |
| if (vma->vm_file) { |
| mapping = vma->vm_file->f_mapping; |
| i_mmap_lock_write(mapping); |
| __vma_link_file(vma, mapping); |
| i_mmap_unlock_write(mapping); |
| } |
| |
| mm->map_count++; |
| validate_mm(mm); |
| return 0; |
| } |
| |
| /* |
| * init_multi_vma_prep() - Initializer for struct vma_prepare |
| * @vp: The vma_prepare struct |
| * @vma: The vma that will be altered once locked |
| * @next: The next vma if it is to be adjusted |
| * @remove: The first vma to be removed |
| * @remove2: The second vma to be removed |
| */ |
| static inline void init_multi_vma_prep(struct vma_prepare *vp, |
| struct vm_area_struct *vma, struct vm_area_struct *next, |
| struct vm_area_struct *remove, struct vm_area_struct *remove2) |
| { |
| memset(vp, 0, sizeof(struct vma_prepare)); |
| vp->vma = vma; |
| vp->anon_vma = vma->anon_vma; |
| vp->remove = remove; |
| vp->remove2 = remove2; |
| vp->adj_next = next; |
| if (!vp->anon_vma && next) |
| vp->anon_vma = next->anon_vma; |
| |
| vp->file = vma->vm_file; |
| if (vp->file) |
| vp->mapping = vma->vm_file->f_mapping; |
| |
| } |
| |
| /* |
| * init_vma_prep() - Initializer wrapper for vma_prepare struct |
| * @vp: The vma_prepare struct |
| * @vma: The vma that will be altered once locked |
| */ |
| static inline void init_vma_prep(struct vma_prepare *vp, |
| struct vm_area_struct *vma) |
| { |
| init_multi_vma_prep(vp, vma, NULL, NULL, NULL); |
| } |
| |
| |
| /* |
| * vma_prepare() - Helper function for handling locking VMAs prior to altering |
| * @vp: The initialized vma_prepare struct |
| */ |
| static inline void vma_prepare(struct vma_prepare *vp) |
| { |
| if (vp->file) { |
| uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end); |
| |
| if (vp->adj_next) |
| uprobe_munmap(vp->adj_next, vp->adj_next->vm_start, |
| vp->adj_next->vm_end); |
| |
| i_mmap_lock_write(vp->mapping); |
| if (vp->insert && vp->insert->vm_file) { |
| /* |
| * Put into interval tree now, so instantiated pages |
| * are visible to arm/parisc __flush_dcache_page |
| * throughout; but we cannot insert into address |
| * space until vma start or end is updated. |
| */ |
| __vma_link_file(vp->insert, |
| vp->insert->vm_file->f_mapping); |
| } |
| } |
| |
| if (vp->anon_vma) { |
| anon_vma_lock_write(vp->anon_vma); |
| anon_vma_interval_tree_pre_update_vma(vp->vma); |
| if (vp->adj_next) |
| anon_vma_interval_tree_pre_update_vma(vp->adj_next); |
| } |
| |
| if (vp->file) { |
| flush_dcache_mmap_lock(vp->mapping); |
| vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap); |
| if (vp->adj_next) |
| vma_interval_tree_remove(vp->adj_next, |
| &vp->mapping->i_mmap); |
| } |
| |
| } |
| |
| /* |
| * vma_complete- Helper function for handling the unlocking after altering VMAs, |
| * or for inserting a VMA. |
| * |
| * @vp: The vma_prepare struct |
| * @vmi: The vma iterator |
| * @mm: The mm_struct |
| */ |
| static inline void vma_complete(struct vma_prepare *vp, |
| struct vma_iterator *vmi, struct mm_struct *mm) |
| { |
| if (vp->file) { |
| if (vp->adj_next) |
| vma_interval_tree_insert(vp->adj_next, |
| &vp->mapping->i_mmap); |
| vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap); |
| flush_dcache_mmap_unlock(vp->mapping); |
| } |
| |
| if (vp->remove && vp->file) { |
| __remove_shared_vm_struct(vp->remove, vp->file, vp->mapping); |
| if (vp->remove2) |
| __remove_shared_vm_struct(vp->remove2, vp->file, |
| vp->mapping); |
| } else if (vp->insert) { |
| /* |
| * split_vma has split insert from vma, and needs |
| * us to insert it before dropping the locks |
| * (it may either follow vma or precede it). |
| */ |
| vma_iter_store(vmi, vp->insert); |
| mm->map_count++; |
| } |
| |
| if (vp->anon_vma) { |
| anon_vma_interval_tree_post_update_vma(vp->vma); |
| if (vp->adj_next) |
| anon_vma_interval_tree_post_update_vma(vp->adj_next); |
| anon_vma_unlock_write(vp->anon_vma); |
| } |
| |
| if (vp->file) { |
| i_mmap_unlock_write(vp->mapping); |
| uprobe_mmap(vp->vma); |
| |
| if (vp->adj_next) |
| uprobe_mmap(vp->adj_next); |
| } |
| |
| if (vp->remove) { |
| again: |
| vma_mark_detached(vp->remove, true); |
| if (vp->file) { |
| uprobe_munmap(vp->remove, vp->remove->vm_start, |
| vp->remove->vm_end); |
| fput(vp->file); |
| } |
| if (vp->remove->anon_vma) |
| anon_vma_merge(vp->vma, vp->remove); |
| mm->map_count--; |
| mpol_put(vma_policy(vp->remove)); |
| if (!vp->remove2) |
| WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end); |
| vm_area_free(vp->remove); |
| |
| /* |
| * In mprotect's case 6 (see comments on vma_merge), |
| * we are removing both mid and next vmas |
| */ |
| if (vp->remove2) { |
| vp->remove = vp->remove2; |
| vp->remove2 = NULL; |
| goto again; |
| } |
| } |
| if (vp->insert && vp->file) |
| uprobe_mmap(vp->insert); |
| validate_mm(mm); |
| } |
| |
| /* |
| * dup_anon_vma() - Helper function to duplicate anon_vma |
| * @dst: The destination VMA |
| * @src: The source VMA |
| * @dup: Pointer to the destination VMA when successful. |
| * |
| * Returns: 0 on success. |
| */ |
| static inline int dup_anon_vma(struct vm_area_struct *dst, |
| struct vm_area_struct *src, struct vm_area_struct **dup) |
| { |
| /* |
| * Easily overlooked: when mprotect shifts the boundary, make sure the |
| * expanding vma has anon_vma set if the shrinking vma had, to cover any |
| * anon pages imported. |
| */ |
| if (src->anon_vma && !dst->anon_vma) { |
| int ret; |
| |
| vma_assert_write_locked(dst); |
| dst->anon_vma = src->anon_vma; |
| ret = anon_vma_clone(dst, src); |
| if (ret) |
| return ret; |
| |
| *dup = dst; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * vma_expand - Expand an existing VMA |
| * |
| * @vmi: The vma iterator |
| * @vma: The vma to expand |
| * @start: The start of the vma |
| * @end: The exclusive end of the vma |
| * @pgoff: The page offset of vma |
| * @next: The current of next vma. |
| * |
| * Expand @vma to @start and @end. Can expand off the start and end. Will |
| * expand over @next if it's different from @vma and @end == @next->vm_end. |
| * Checking if the @vma can expand and merge with @next needs to be handled by |
| * the caller. |
| * |
| * Returns: 0 on success |
| */ |
| int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| unsigned long start, unsigned long end, pgoff_t pgoff, |
| struct vm_area_struct *next) |
| { |
| struct vm_area_struct *anon_dup = NULL; |
| bool remove_next = false; |
| struct vma_prepare vp; |
| |
| vma_start_write(vma); |
| if (next && (vma != next) && (end == next->vm_end)) { |
| int ret; |
| |
| remove_next = true; |
| vma_start_write(next); |
| ret = dup_anon_vma(vma, next, &anon_dup); |
| if (ret) |
| return ret; |
| } |
| |
| init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL); |
| /* Not merging but overwriting any part of next is not handled. */ |
| VM_WARN_ON(next && !vp.remove && |
| next != vma && end > next->vm_start); |
| /* Only handles expanding */ |
| VM_WARN_ON(vma->vm_start < start || vma->vm_end > end); |
| |
| /* Note: vma iterator must be pointing to 'start' */ |
| vma_iter_config(vmi, start, end); |
| if (vma_iter_prealloc(vmi, vma)) |
| goto nomem; |
| |
| vma_prepare(&vp); |
| vma_adjust_trans_huge(vma, start, end, 0); |
| vma->vm_start = start; |
| vma->vm_end = end; |
| vma->vm_pgoff = pgoff; |
| vma_iter_store(vmi, vma); |
| |
| vma_complete(&vp, vmi, vma->vm_mm); |
| return 0; |
| |
| nomem: |
| if (anon_dup) |
| unlink_anon_vmas(anon_dup); |
| return -ENOMEM; |
| } |
| |
| /* |
| * vma_shrink() - Reduce an existing VMAs memory area |
| * @vmi: The vma iterator |
| * @vma: The VMA to modify |
| * @start: The new start |
| * @end: The new end |
| * |
| * Returns: 0 on success, -ENOMEM otherwise |
| */ |
| int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| unsigned long start, unsigned long end, pgoff_t pgoff) |
| { |
| struct vma_prepare vp; |
| |
| WARN_ON((vma->vm_start != start) && (vma->vm_end != end)); |
| |
| if (vma->vm_start < start) |
| vma_iter_config(vmi, vma->vm_start, start); |
| else |
| vma_iter_config(vmi, end, vma->vm_end); |
| |
| if (vma_iter_prealloc(vmi, NULL)) |
| return -ENOMEM; |
| |
| vma_start_write(vma); |
| |
| init_vma_prep(&vp, vma); |
| vma_prepare(&vp); |
| vma_adjust_trans_huge(vma, start, end, 0); |
| |
| vma_iter_clear(vmi); |
| vma->vm_start = start; |
| vma->vm_end = end; |
| vma->vm_pgoff = pgoff; |
| vma_complete(&vp, vmi, vma->vm_mm); |
| return 0; |
| } |
| |
| /* |
| * If the vma has a ->close operation then the driver probably needs to release |
| * per-vma resources, so we don't attempt to merge those if the caller indicates |
| * the current vma may be removed as part of the merge. |
| */ |
| static inline bool is_mergeable_vma(struct vm_area_struct *vma, |
| struct file *file, unsigned long vm_flags, |
| struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| struct anon_vma_name *anon_name, bool may_remove_vma) |
| { |
| /* |
| * VM_SOFTDIRTY should not prevent from VMA merging, if we |
| * match the flags but dirty bit -- the caller should mark |
| * merged VMA as dirty. If dirty bit won't be excluded from |
| * comparison, we increase pressure on the memory system forcing |
| * the kernel to generate new VMAs when old one could be |
| * extended instead. |
| */ |
| if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) |
| return false; |
| if (vma->vm_file != file) |
| return false; |
| if (may_remove_vma && vma->vm_ops && vma->vm_ops->close) |
| return false; |
| if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) |
| return false; |
| if (!anon_vma_name_eq(anon_vma_name(vma), anon_name)) |
| return false; |
| return true; |
| } |
| |
| static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1, |
| struct anon_vma *anon_vma2, struct vm_area_struct *vma) |
| { |
| /* |
| * The list_is_singular() test is to avoid merging VMA cloned from |
| * parents. This can improve scalability caused by anon_vma lock. |
| */ |
| if ((!anon_vma1 || !anon_vma2) && (!vma || |
| list_is_singular(&vma->anon_vma_chain))) |
| return true; |
| return anon_vma1 == anon_vma2; |
| } |
| |
| /* |
| * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| * in front of (at a lower virtual address and file offset than) the vma. |
| * |
| * We cannot merge two vmas if they have differently assigned (non-NULL) |
| * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| * |
| * We don't check here for the merged mmap wrapping around the end of pagecache |
| * indices (16TB on ia32) because do_mmap() does not permit mmap's which |
| * wrap, nor mmaps which cover the final page at index -1UL. |
| * |
| * We assume the vma may be removed as part of the merge. |
| */ |
| static bool |
| can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, |
| struct anon_vma *anon_vma, struct file *file, |
| pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| struct anon_vma_name *anon_name) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) && |
| is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { |
| if (vma->vm_pgoff == vm_pgoff) |
| return true; |
| } |
| return false; |
| } |
| |
| /* |
| * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
| * beyond (at a higher virtual address and file offset than) the vma. |
| * |
| * We cannot merge two vmas if they have differently assigned (non-NULL) |
| * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
| * |
| * We assume that vma is not removed as part of the merge. |
| */ |
| static bool |
| can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, |
| struct anon_vma *anon_vma, struct file *file, |
| pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| struct anon_vma_name *anon_name) |
| { |
| if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) && |
| is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { |
| pgoff_t vm_pglen; |
| vm_pglen = vma_pages(vma); |
| if (vma->vm_pgoff + vm_pglen == vm_pgoff) |
| return true; |
| } |
| return false; |
| } |
| |
| /* |
| * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name), |
| * figure out whether that can be merged with its predecessor or its |
| * successor. Or both (it neatly fills a hole). |
| * |
| * In most cases - when called for mmap, brk or mremap - [addr,end) is |
| * certain not to be mapped by the time vma_merge is called; but when |
| * called for mprotect, it is certain to be already mapped (either at |
| * an offset within prev, or at the start of next), and the flags of |
| * this area are about to be changed to vm_flags - and the no-change |
| * case has already been eliminated. |
| * |
| * The following mprotect cases have to be considered, where **** is |
| * the area passed down from mprotect_fixup, never extending beyond one |
| * vma, PPPP is the previous vma, CCCC is a concurrent vma that starts |
| * at the same address as **** and is of the same or larger span, and |
| * NNNN the next vma after ****: |
| * |
| * **** **** **** |
| * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC |
| * cannot merge might become might become |
| * PPNNNNNNNNNN PPPPPPPPPPCC |
| * mmap, brk or case 4 below case 5 below |
| * mremap move: |
| * **** **** |
| * PPPP NNNN PPPPCCCCNNNN |
| * might become might become |
| * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or |
| * PPPPPPPPNNNN 2 or PPPPPPPPNNNN 7 or |
| * PPPPNNNNNNNN 3 PPPPNNNNNNNN 8 |
| * |
| * It is important for case 8 that the vma CCCC overlapping the |
| * region **** is never going to extended over NNNN. Instead NNNN must |
| * be extended in region **** and CCCC must be removed. This way in |
| * all cases where vma_merge succeeds, the moment vma_merge drops the |
| * rmap_locks, the properties of the merged vma will be already |
| * correct for the whole merged range. Some of those properties like |
| * vm_page_prot/vm_flags may be accessed by rmap_walks and they must |
| * be correct for the whole merged range immediately after the |
| * rmap_locks are released. Otherwise if NNNN would be removed and |
| * CCCC would be extended over the NNNN range, remove_migration_ptes |
| * or other rmap walkers (if working on addresses beyond the "end" |
| * parameter) may establish ptes with the wrong permissions of CCCC |
| * instead of the right permissions of NNNN. |
| * |
| * In the code below: |
| * PPPP is represented by *prev |
| * CCCC is represented by *curr or not represented at all (NULL) |
| * NNNN is represented by *next or not represented at all (NULL) |
| * **** is not represented - it will be merged and the vma containing the |
| * area is returned, or the function will return NULL |
| */ |
| struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, |
| struct vm_area_struct *prev, unsigned long addr, |
| unsigned long end, unsigned long vm_flags, |
| struct anon_vma *anon_vma, struct file *file, |
| pgoff_t pgoff, struct mempolicy *policy, |
| struct vm_userfaultfd_ctx vm_userfaultfd_ctx, |
| struct anon_vma_name *anon_name) |
| { |
| struct vm_area_struct *curr, *next, *res; |
| struct vm_area_struct *vma, *adjust, *remove, *remove2; |
| struct vm_area_struct *anon_dup = NULL; |
| struct vma_prepare vp; |
| pgoff_t vma_pgoff; |
| int err = 0; |
| bool merge_prev = false; |
| bool merge_next = false; |
| bool vma_expanded = false; |
| unsigned long vma_start = addr; |
| unsigned long vma_end = end; |
| pgoff_t pglen = (end - addr) >> PAGE_SHIFT; |
| long adj_start = 0; |
| |
| /* |
| * We later require that vma->vm_flags == vm_flags, |
| * so this tests vma->vm_flags & VM_SPECIAL, too. |
| */ |
| if (vm_flags & VM_SPECIAL) |
| return NULL; |
| |
| /* Does the input range span an existing VMA? (cases 5 - 8) */ |
| curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end); |
| |
| if (!curr || /* cases 1 - 4 */ |
| end == curr->vm_end) /* cases 6 - 8, adjacent VMA */ |
| next = vma_lookup(mm, end); |
| else |
| next = NULL; /* case 5 */ |
| |
| if (prev) { |
| vma_start = prev->vm_start; |
| vma_pgoff = prev->vm_pgoff; |
| |
| /* Can we merge the predecessor? */ |
| if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy) |
| && can_vma_merge_after(prev, vm_flags, anon_vma, file, |
| pgoff, vm_userfaultfd_ctx, anon_name)) { |
| merge_prev = true; |
| vma_prev(vmi); |
| } |
| } |
| |
| /* Can we merge the successor? */ |
| if (next && mpol_equal(policy, vma_policy(next)) && |
| can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen, |
| vm_userfaultfd_ctx, anon_name)) { |
| merge_next = true; |
| } |
| |
| /* Verify some invariant that must be enforced by the caller. */ |
| VM_WARN_ON(prev && addr <= prev->vm_start); |
| VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end)); |
| VM_WARN_ON(addr >= end); |
| |
| if (!merge_prev && !merge_next) |
| return NULL; /* Not mergeable. */ |
| |
| if (merge_prev) |
| vma_start_write(prev); |
| |
| res = vma = prev; |
| remove = remove2 = adjust = NULL; |
| |
| /* Can we merge both the predecessor and the successor? */ |
| if (merge_prev && merge_next && |
| is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) { |
| vma_start_write(next); |
| remove = next; /* case 1 */ |
| vma_end = next->vm_end; |
| err = dup_anon_vma(prev, next, &anon_dup); |
| if (curr) { /* case 6 */ |
| vma_start_write(curr); |
| remove = curr; |
| remove2 = next; |
| if (!next->anon_vma) |
| err = dup_anon_vma(prev, curr, &anon_dup); |
| } |
| } else if (merge_prev) { /* case 2 */ |
| if (curr) { |
| vma_start_write(curr); |
| err = dup_anon_vma(prev, curr, &anon_dup); |
| if (end == curr->vm_end) { /* case 7 */ |
| remove = curr; |
| } else { /* case 5 */ |
| adjust = curr; |
| adj_start = (end - curr->vm_start); |
| } |
| } |
| } else { /* merge_next */ |
| vma_start_write(next); |
| res = next; |
| if (prev && addr < prev->vm_end) { /* case 4 */ |
| vma_start_write(prev); |
| vma_end = addr; |
| adjust = next; |
| adj_start = -(prev->vm_end - addr); |
| err = dup_anon_vma(next, prev, &anon_dup); |
| } else { |
| /* |
| * Note that cases 3 and 8 are the ONLY ones where prev |
| * is permitted to be (but is not necessarily) NULL. |
| */ |
| vma = next; /* case 3 */ |
| vma_start = addr; |
| vma_end = next->vm_end; |
| vma_pgoff = next->vm_pgoff - pglen; |
| if (curr) { /* case 8 */ |
| vma_pgoff = curr->vm_pgoff; |
| vma_start_write(curr); |
| remove = curr; |
| err = dup_anon_vma(next, curr, &anon_dup); |
| } |
| } |
| } |
| |
| /* Error in anon_vma clone. */ |
| if (err) |
| goto anon_vma_fail; |
| |
| if (vma_start < vma->vm_start || vma_end > vma->vm_end) |
| vma_expanded = true; |
| |
| if (vma_expanded) { |
| vma_iter_config(vmi, vma_start, vma_end); |
| } else { |
| vma_iter_config(vmi, adjust->vm_start + adj_start, |
| adjust->vm_end); |
| } |
| |
| if (vma_iter_prealloc(vmi, vma)) |
| goto prealloc_fail; |
| |
| init_multi_vma_prep(&vp, vma, adjust, remove, remove2); |
| VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && |
| vp.anon_vma != adjust->anon_vma); |
| |
| vma_prepare(&vp); |
| vma_adjust_trans_huge(vma, vma_start, vma_end, adj_start); |
| |
| vma->vm_start = vma_start; |
| vma->vm_end = vma_end; |
| vma->vm_pgoff = vma_pgoff; |
| |
| if (vma_expanded) |
| vma_iter_store(vmi, vma); |
| |
| if (adj_start) { |
| adjust->vm_start += adj_start; |
| adjust->vm_pgoff += adj_start >> PAGE_SHIFT; |
| if (adj_start < 0) { |
| WARN_ON(vma_expanded); |
| vma_iter_store(vmi, next); |
| } |
| } |
| |
| vma_complete(&vp, vmi, mm); |
| khugepaged_enter_vma(res, vm_flags); |
| return res; |
| |
| prealloc_fail: |
| if (anon_dup) |
| unlink_anon_vmas(anon_dup); |
| |
| anon_vma_fail: |
| vma_iter_set(vmi, addr); |
| vma_iter_load(vmi); |
| return NULL; |
| } |
| |
| /* |
| * Rough compatibility check to quickly see if it's even worth looking |
| * at sharing an anon_vma. |
| * |
| * They need to have the same vm_file, and the flags can only differ |
| * in things that mprotect may change. |
| * |
| * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that |
| * we can merge the two vma's. For example, we refuse to merge a vma if |
| * there is a vm_ops->close() function, because that indicates that the |
| * driver is doing some kind of reference counting. But that doesn't |
| * really matter for the anon_vma sharing case. |
| */ |
| static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) |
| { |
| return a->vm_end == b->vm_start && |
| mpol_equal(vma_policy(a), vma_policy(b)) && |
| a->vm_file == b->vm_file && |
| !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) && |
| b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); |
| } |
| |
| /* |
| * Do some basic sanity checking to see if we can re-use the anon_vma |
| * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be |
| * the same as 'old', the other will be the new one that is trying |
| * to share the anon_vma. |
| * |
| * NOTE! This runs with mmap_lock held for reading, so it is possible that |
| * the anon_vma of 'old' is concurrently in the process of being set up |
| * by another page fault trying to merge _that_. But that's ok: if it |
| * is being set up, that automatically means that it will be a singleton |
| * acceptable for merging, so we can do all of this optimistically. But |
| * we do that READ_ONCE() to make sure that we never re-load the pointer. |
| * |
| * IOW: that the "list_is_singular()" test on the anon_vma_chain only |
| * matters for the 'stable anon_vma' case (ie the thing we want to avoid |
| * is to return an anon_vma that is "complex" due to having gone through |
| * a fork). |
| * |
| * We also make sure that the two vma's are compatible (adjacent, |
| * and with the same memory policies). That's all stable, even with just |
| * a read lock on the mmap_lock. |
| */ |
| static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) |
| { |
| if (anon_vma_compatible(a, b)) { |
| struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); |
| |
| if (anon_vma && list_is_singular(&old->anon_vma_chain)) |
| return anon_vma; |
| } |
| return NULL; |
| } |
| |
| /* |
| * find_mergeable_anon_vma is used by anon_vma_prepare, to check |
| * neighbouring vmas for a suitable anon_vma, before it goes off |
| * to allocate a new anon_vma. It checks because a repetitive |
| * sequence of mprotects and faults may otherwise lead to distinct |
| * anon_vmas being allocated, preventing vma merge in subsequent |
| * mprotect. |
| */ |
| struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) |
| { |
| MA_STATE(mas, &vma->vm_mm->mm_mt, vma->vm_end, vma->vm_end); |
| struct anon_vma *anon_vma = NULL; |
| struct vm_area_struct *prev, *next; |
| |
| /* Try next first. */ |
| next = mas_walk(&mas); |
| if (next) { |
| anon_vma = reusable_anon_vma(next, vma, next); |
| if (anon_vma) |
| return anon_vma; |
| } |
| |
| prev = mas_prev(&mas, 0); |
| VM_BUG_ON_VMA(prev != vma, vma); |
| prev = mas_prev(&mas, 0); |
| /* Try prev next. */ |
| if (prev) |
| anon_vma = reusable_anon_vma(prev, prev, vma); |
| |
| /* |
| * We might reach here with anon_vma == NULL if we can't find |
| * any reusable anon_vma. |
| * There's no absolute need to look only at touching neighbours: |
| * we could search further afield for "compatible" anon_vmas. |
| * But it would probably just be a waste of time searching, |
| * or lead to too many vmas hanging off the same anon_vma. |
| * We're trying to allow mprotect remerging later on, |
| * not trying to minimize memory used for anon_vmas. |
| */ |
| return anon_vma; |
| } |
| |
| /* |
| * If a hint addr is less than mmap_min_addr change hint to be as |
| * low as possible but still greater than mmap_min_addr |
| */ |
| static inline unsigned long round_hint_to_min(unsigned long hint) |
| { |
| hint &= PAGE_MASK; |
| if (((void *)hint != NULL) && |
| (hint < mmap_min_addr)) |
| return PAGE_ALIGN(mmap_min_addr); |
| return hint; |
| } |
| |
| bool mlock_future_ok(struct mm_struct *mm, unsigned long flags, |
| unsigned long bytes) |
| { |
| unsigned long locked_pages, limit_pages; |
| |
| if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK)) |
| return true; |
| |
| locked_pages = bytes >> PAGE_SHIFT; |
| locked_pages += mm->locked_vm; |
| |
| limit_pages = rlimit(RLIMIT_MEMLOCK); |
| limit_pages >>= PAGE_SHIFT; |
| |
| return locked_pages <= limit_pages; |
| } |
| |
| static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) |
| { |
| if (S_ISREG(inode->i_mode)) |
| return MAX_LFS_FILESIZE; |
| |
| if (S_ISBLK(inode->i_mode)) |
| return MAX_LFS_FILESIZE; |
| |
| if (S_ISSOCK(inode->i_mode)) |
| return MAX_LFS_FILESIZE; |
| |
| /* Special "we do even unsigned file positions" case */ |
| if (file->f_mode & FMODE_UNSIGNED_OFFSET) |
| return 0; |
| |
| /* Yes, random drivers might want more. But I'm tired of buggy drivers */ |
| return ULONG_MAX; |
| } |
| |
| static inline bool file_mmap_ok(struct file *file, struct inode *inode, |
| unsigned long pgoff, unsigned long len) |
| { |
| u64 maxsize = file_mmap_size_max(file, inode); |
| |
| if (maxsize && len > maxsize) |
| return false; |
| maxsize -= len; |
| if (pgoff > maxsize >> PAGE_SHIFT) |
| return false; |
| return true; |
| } |
| |
| /* |
| * The caller must write-lock current->mm->mmap_lock. |
| */ |
| unsigned long do_mmap(struct file *file, unsigned long addr, |
| unsigned long len, unsigned long prot, |
| unsigned long flags, vm_flags_t vm_flags, |
| unsigned long pgoff, unsigned long *populate, |
| struct list_head *uf) |
| { |
| struct mm_struct *mm = current->mm; |
| int pkey = 0; |
| |
| *populate = 0; |
| |
| if (!len) |
| return -EINVAL; |
| |
| /* |
| * Does the application expect PROT_READ to imply PROT_EXEC? |
| * |
| * (the exception is when the underlying filesystem is noexec |
| * mounted, in which case we dont add PROT_EXEC.) |
| */ |
| if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
| if (!(file && path_noexec(&file->f_path))) |
| prot |= PROT_EXEC; |
| |
| /* force arch specific MAP_FIXED handling in get_unmapped_area */ |
| if (flags & MAP_FIXED_NOREPLACE) |
| flags |= MAP_FIXED; |
| |
| if (!(flags & MAP_FIXED)) |
| addr = round_hint_to_min(addr); |
| |
| /* Careful about overflows.. */ |
| len = PAGE_ALIGN(len); |
| if (!len) |
| return -ENOMEM; |
| |
| /* offset overflow? */ |
| if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) |
| return -EOVERFLOW; |
| |
| /* Too many mappings? */ |
| if (mm->map_count > sysctl_max_map_count) |
| return -ENOMEM; |
| |
| /* Obtain the address to map to. we verify (or select) it and ensure |
| * that it represents a valid section of the address space. |
| */ |
| addr = get_unmapped_area(file, addr, len, pgoff, flags); |
| if (IS_ERR_VALUE(addr)) |
| return addr; |
| |
| if (flags & MAP_FIXED_NOREPLACE) { |
| if (find_vma_intersection(mm, addr, addr + len)) |
| return -EEXIST; |
| } |
| |
| if (prot == PROT_EXEC) { |
| pkey = execute_only_pkey(mm); |
| if (pkey < 0) |
| pkey = 0; |
| } |
| |
| /* Do simple checking here so the lower-level routines won't have |
| * to. we assume access permissions have been handled by the open |
| * of the memory object, so we don't do any here. |
| */ |
| vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) | |
| mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
| |
| if (flags & MAP_LOCKED) |
| if (!can_do_mlock()) |
| return -EPERM; |
| |
| if (!mlock_future_ok(mm, vm_flags, len)) |
| return -EAGAIN; |
| |
| if (file) { |
| struct inode *inode = file_inode(file); |
| unsigned long flags_mask; |
| |
| if (!file_mmap_ok(file, inode, pgoff, len)) |
| return -EOVERFLOW; |
| |
| flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; |
| |
| switch (flags & MAP_TYPE) { |
| case MAP_SHARED: |
| /* |
| * Force use of MAP_SHARED_VALIDATE with non-legacy |
| * flags. E.g. MAP_SYNC is dangerous to use with |
| * MAP_SHARED as you don't know which consistency model |
| * you will get. We silently ignore unsupported flags |
| * with MAP_SHARED to preserve backward compatibility. |
| */ |
| flags &= LEGACY_MAP_MASK; |
| fallthrough; |
| case MAP_SHARED_VALIDATE: |
| if (flags & ~flags_mask) |
| return -EOPNOTSUPP; |
| if (prot & PROT_WRITE) { |
| if (!(file->f_mode & FMODE_WRITE)) |
| return -EACCES; |
| if (IS_SWAPFILE(file->f_mapping->host)) |
| return -ETXTBSY; |
| } |
| |
| /* |
| * Make sure we don't allow writing to an append-only |
| * file.. |
| */ |
| if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) |
| return -EACCES; |
| |
| vm_flags |= VM_SHARED | VM_MAYSHARE; |
| if (!(file->f_mode & FMODE_WRITE)) |
| vm_flags &= ~(VM_MAYWRITE | VM_SHARED); |
| fallthrough; |
| case MAP_PRIVATE: |
| if (!(file->f_mode & FMODE_READ)) |
| return -EACCES; |
| if (path_noexec(&file->f_path)) { |
| if (vm_flags & VM_EXEC) |
| return -EPERM; |
| vm_flags &= ~VM_MAYEXEC; |
| } |
| |
| if (!file->f_op->mmap) |
| return -ENODEV; |
| if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| return -EINVAL; |
| break; |
| |
| default: |
| return -EINVAL; |
| } |
| } else { |
| switch (flags & MAP_TYPE) { |
| case MAP_SHARED: |
| if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
| return -EINVAL; |
| /* |
| * Ignore pgoff. |
| */ |
| pgoff = 0; |
| vm_flags |= VM_SHARED | VM_MAYSHARE; |
| break; |
| case MAP_PRIVATE: |
| /* |
| * Set pgoff according to addr for anon_vma. |
| */ |
| pgoff = addr >> PAGE_SHIFT; |
| break; |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| /* |
| * Set 'VM_NORESERVE' if we should not account for the |
| * memory use of this mapping. |
| */ |
| if (flags & MAP_NORESERVE) { |
| /* We honor MAP_NORESERVE if allowed to overcommit */ |
| if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) |
| vm_flags |= VM_NORESERVE; |
| |
| /* hugetlb applies strict overcommit unless MAP_NORESERVE */ |
| if (file && is_file_hugepages(file)) |
| vm_flags |= VM_NORESERVE; |
| } |
| |
| addr = mmap_region(file, addr, len, vm_flags, pgoff, uf); |
| if (!IS_ERR_VALUE(addr) && |
| ((vm_flags & VM_LOCKED) || |
| (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) |
| *populate = len; |
| return addr; |
| } |
| |
| unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, |
| unsigned long prot, unsigned long flags, |
| unsigned long fd, unsigned long pgoff) |
| { |
| struct file *file = NULL; |
| unsigned long retval; |
| |
| if (!(flags & MAP_ANONYMOUS)) { |
| audit_mmap_fd(fd, flags); |
| file = fget(fd); |
| if (!file) |
| return -EBADF; |
| if (is_file_hugepages(file)) { |
| len = ALIGN(len, huge_page_size(hstate_file(file))); |
| } else if (unlikely(flags & MAP_HUGETLB)) { |
| retval = -EINVAL; |
| goto out_fput; |
| } |
| } else if (flags & MAP_HUGETLB) { |
| struct hstate *hs; |
| |
| hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); |
| if (!hs) |
| return -EINVAL; |
| |
| len = ALIGN(len, huge_page_size(hs)); |
| /* |
| * VM_NORESERVE is used because the reservations will be |
| * taken when vm_ops->mmap() is called |
| */ |
| file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, |
| VM_NORESERVE, |
| HUGETLB_ANONHUGE_INODE, |
| (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); |
| if (IS_ERR(file)) |
| return PTR_ERR(file); |
| } |
| |
| retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
| out_fput: |
| if (file) |
| fput(file); |
| return retval; |
| } |
| |
| SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
| unsigned long, prot, unsigned long, flags, |
| unsigned long, fd, unsigned long, pgoff) |
| { |
| return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); |
| } |
| |
| #ifdef __ARCH_WANT_SYS_OLD_MMAP |
| struct mmap_arg_struct { |
| unsigned long addr; |
| unsigned long len; |
| unsigned long prot; |
| unsigned long flags; |
| unsigned long fd; |
| unsigned long offset; |
| }; |
| |
| SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) |
| { |
| struct mmap_arg_struct a; |
| |
| if (copy_from_user(&a, arg, sizeof(a))) |
| return -EFAULT; |
| if (offset_in_page(a.offset)) |
| return -EINVAL; |
| |
| return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
| a.offset >> PAGE_SHIFT); |
| } |
| #endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
| |
| static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops) |
| { |
| return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite); |
| } |
| |
| static bool vma_is_shared_writable(struct vm_area_struct *vma) |
| { |
| return (vma->vm_flags & (VM_WRITE | VM_SHARED)) == |
| (VM_WRITE | VM_SHARED); |
| } |
| |
| static bool vma_fs_can_writeback(struct vm_area_struct *vma) |
| { |
| /* No managed pages to writeback. */ |
| if (vma->vm_flags & VM_PFNMAP) |
| return false; |
| |
| return vma->vm_file && vma->vm_file->f_mapping && |
| mapping_can_writeback(vma->vm_file->f_mapping); |
| } |
| |
| /* |
| * Does this VMA require the underlying folios to have their dirty state |
| * tracked? |
| */ |
| bool vma_needs_dirty_tracking(struct vm_area_struct *vma) |
| { |
| /* Only shared, writable VMAs require dirty tracking. */ |
| if (!vma_is_shared_writable(vma)) |
| return false; |
| |
| /* Does the filesystem need to be notified? */ |
| if (vm_ops_needs_writenotify(vma->vm_ops)) |
| return true; |
| |
| /* |
| * Even if the filesystem doesn't indicate a need for writenotify, if it |
| * can writeback, dirty tracking is still required. |
| */ |
| return vma_fs_can_writeback(vma); |
| } |
| |
| /* |
| * Some shared mappings will want the pages marked read-only |
| * to track write events. If so, we'll downgrade vm_page_prot |
| * to the private version (using protection_map[] without the |
| * VM_SHARED bit). |
| */ |
| int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) |
| { |
| /* If it was private or non-writable, the write bit is already clear */ |
| if (!vma_is_shared_writable(vma)) |
| return 0; |
| |
| /* The backer wishes to know when pages are first written to? */ |
| if (vm_ops_needs_writenotify(vma->vm_ops)) |
| return 1; |
| |
| /* The open routine did something to the protections that pgprot_modify |
| * won't preserve? */ |
| if (pgprot_val(vm_page_prot) != |
| pgprot_val(vm_pgprot_modify(vm_page_prot, vma->vm_flags))) |
| return 0; |
| |
| /* |
| * Do we need to track softdirty? hugetlb does not support softdirty |
| * tracking yet. |
| */ |
| if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma)) |
| return 1; |
| |
| /* Do we need write faults for uffd-wp tracking? */ |
| if (userfaultfd_wp(vma)) |
| return 1; |
| |
| /* Can the mapping track the dirty pages? */ |
| return vma_fs_can_writeback(vma); |
| } |
| |
| /* |
| * We account for memory if it's a private writeable mapping, |
| * not hugepages and VM_NORESERVE wasn't set. |
| */ |
| static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) |
| { |
| /* |
| * hugetlb has its own accounting separate from the core VM |
| * VM_HUGETLB may not be set yet so we cannot check for that flag. |
| */ |
| if (file && is_file_hugepages(file)) |
| return 0; |
| |
| return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; |
| } |
| |
| /** |
| * unmapped_area() - Find an area between the low_limit and the high_limit with |
| * the correct alignment and offset, all from @info. Note: current->mm is used |
| * for the search. |
| * |
| * @info: The unmapped area information including the range [low_limit - |
| * high_limit), the alignment offset and mask. |
| * |
| * Return: A memory address or -ENOMEM. |
| */ |
| static unsigned long unmapped_area(struct vm_unmapped_area_info *info) |
| { |
| unsigned long length, gap; |
| unsigned long low_limit, high_limit; |
| struct vm_area_struct *tmp; |
| |
| MA_STATE(mas, ¤t->mm->mm_mt, 0, 0); |
| |
| /* Adjust search length to account for worst case alignment overhead */ |
| length = info->length + info->align_mask; |
| if (length < info->length) |
| return -ENOMEM; |
| |
| low_limit = info->low_limit; |
| if (low_limit < mmap_min_addr) |
| low_limit = mmap_min_addr; |
| high_limit = info->high_limit; |
| retry: |
| if (mas_empty_area(&mas, low_limit, high_limit - 1, length)) |
| return -ENOMEM; |
| |
| gap = mas.index; |
| gap += (info->align_offset - gap) & info->align_mask; |
| tmp = mas_next(&mas, ULONG_MAX); |
| if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */ |
| if (vm_start_gap(tmp) < gap + length - 1) { |
| low_limit = tmp->vm_end; |
| mas_reset(&mas); |
| goto retry; |
| } |
| } else { |
| tmp = mas_prev(&mas, 0); |
| if (tmp && vm_end_gap(tmp) > gap) { |
| low_limit = vm_end_gap(tmp); |
| mas_reset(&mas); |
| goto retry; |
| } |
| } |
| |
| return gap; |
| } |
| |
| /** |
| * unmapped_area_topdown() - Find an area between the low_limit and the |
| * high_limit with the correct alignment and offset at the highest available |
| * address, all from @info. Note: current->mm is used for the search. |
| * |
| * @info: The unmapped area information including the range [low_limit - |
| * high_limit), the alignment offset and mask. |
| * |
| * Return: A memory address or -ENOMEM. |
| */ |
| static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) |
| { |
| unsigned long length, gap, gap_end; |
| unsigned long low_limit, high_limit; |
| struct vm_area_struct *tmp; |
| |
| MA_STATE(mas, ¤t->mm->mm_mt, 0, 0); |
| /* Adjust search length to account for worst case alignment overhead */ |
| length = info->length + info->align_mask; |
| if (length < info->length) |
| return -ENOMEM; |
| |
| low_limit = info->low_limit; |
| if (low_limit < mmap_min_addr) |
| low_limit = mmap_min_addr; |
| high_limit = info->high_limit; |
| retry: |
| if (mas_empty_area_rev(&mas, low_limit, high_limit - 1, length)) |
| return -ENOMEM; |
| |
| gap = mas.last + 1 - info->length; |
| gap -= (gap - info->align_offset) & info->align_mask; |
| gap_end = mas.last; |
| tmp = mas_next(&mas, ULONG_MAX); |
| if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */ |
| if (vm_start_gap(tmp) <= gap_end) { |
| high_limit = vm_start_gap(tmp); |
| mas_reset(&mas); |
| goto retry; |
| } |
| } else { |
| tmp = mas_prev(&mas, 0); |
| if (tmp && vm_end_gap(tmp) > gap) { |
| high_limit = tmp->vm_start; |
| mas_reset(&mas); |
| goto retry; |
| } |
| } |
| |
| return gap; |
| } |
| |
| /* |
| * Search for an unmapped address range. |
| * |
| * We are looking for a range that: |
| * - does not intersect with any VMA; |
| * - is contained within the [low_limit, high_limit) interval; |
| * - is at least the desired size. |
| * - satisfies (begin_addr & align_mask) == (align_offset & align_mask) |
| */ |
| unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) |
| { |
| unsigned long addr; |
| |
| if (info->flags & VM_UNMAPPED_AREA_TOPDOWN) |
| addr = unmapped_area_topdown(info); |
| else |
| addr = unmapped_area(info); |
| |
| trace_vm_unmapped_area(addr, info); |
| return addr; |
| } |
| EXPORT_SYMBOL_GPL(vm_unmapped_area); |
| |
| /* Get an address range which is currently unmapped. |
| * For shmat() with addr=0. |
| * |
| * Ugly calling convention alert: |
| * Return value with the low bits set means error value, |
| * ie |
| * if (ret & ~PAGE_MASK) |
| * error = ret; |
| * |
| * This function "knows" that -ENOMEM has the bits set. |
| */ |
| unsigned long |
| generic_get_unmapped_area(struct file *filp, unsigned long addr, |
| unsigned long len, unsigned long pgoff, |
| unsigned long flags) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma, *prev; |
| struct vm_unmapped_area_info info; |
| const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags); |
| |
| if (len > mmap_end - mmap_min_addr) |
| return -ENOMEM; |
| |
| if (flags & MAP_FIXED) |
| return addr; |
| |
| if (addr) { |
| addr = PAGE_ALIGN(addr); |
| vma = find_vma_prev(mm, addr, &prev); |
| if (mmap_end - len >= addr && addr >= mmap_min_addr && |
| (!vma || addr + len <= vm_start_gap(vma)) && |
| (!prev || addr >= vm_end_gap(prev))) |
| return addr; |
| } |
| |
| info.flags = 0; |
| info.length = len; |
| info.low_limit = mm->mmap_base; |
| info.high_limit = mmap_end; |
| info.align_mask = 0; |
| info.align_offset = 0; |
| return vm_unmapped_area(&info); |
| } |
| |
| #ifndef HAVE_ARCH_UNMAPPED_AREA |
| unsigned long |
| arch_get_unmapped_area(struct file *filp, unsigned long addr, |
| unsigned long len, unsigned long pgoff, |
| unsigned long flags) |
| { |
| return generic_get_unmapped_area(filp, addr, len, pgoff, flags); |
| } |
| #endif |
| |
| /* |
| * This mmap-allocator allocates new areas top-down from below the |
| * stack's low limit (the base): |
| */ |
| unsigned long |
| generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr, |
| unsigned long len, unsigned long pgoff, |
| unsigned long flags) |
| { |
| struct vm_area_struct *vma, *prev; |
| struct mm_struct *mm = current->mm; |
| struct vm_unmapped_area_info info; |
| const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags); |
| |
| /* requested length too big for entire address space */ |
| if (len > mmap_end - mmap_min_addr) |
| return -ENOMEM; |
| |
| if (flags & MAP_FIXED) |
| return addr; |
| |
| /* requesting a specific address */ |
| if (addr) { |
| addr = PAGE_ALIGN(addr); |
| vma = find_vma_prev(mm, addr, &prev); |
| if (mmap_end - len >= addr && addr >= mmap_min_addr && |
| (!vma || addr + len <= vm_start_gap(vma)) && |
| (!prev || addr >= vm_end_gap(prev))) |
| return addr; |
| } |
| |
| info.flags = VM_UNMAPPED_AREA_TOPDOWN; |
| info.length = len; |
| info.low_limit = PAGE_SIZE; |
| info.high_limit = arch_get_mmap_base(addr, mm->mmap_base); |
| info.align_mask = 0; |
| info.align_offset = 0; |
| addr = vm_unmapped_area(&info); |
| |
| /* |
| * A failed mmap() very likely causes application failure, |
| * so fall back to the bottom-up function here. This scenario |
| * can happen with large stack limits and large mmap() |
| * allocations. |
| */ |
| if (offset_in_page(addr)) { |
| VM_BUG_ON(addr != -ENOMEM); |
| info.flags = 0; |
| info.low_limit = TASK_UNMAPPED_BASE; |
| info.high_limit = mmap_end; |
| addr = vm_unmapped_area(&info); |
| } |
| |
| return addr; |
| } |
| |
| #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN |
| unsigned long |
| arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, |
| unsigned long len, unsigned long pgoff, |
| unsigned long flags) |
| { |
| return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); |
| } |
| #endif |
| |
| unsigned long |
| get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, |
| unsigned long pgoff, unsigned long flags) |
| { |
| unsigned long (*get_area)(struct file *, unsigned long, |
| unsigned long, unsigned long, unsigned long); |
| |
| unsigned long error = arch_mmap_check(addr, len, flags); |
| if (error) |
| return error; |
| |
| /* Careful about overflows.. */ |
| if (len > TASK_SIZE) |
| return -ENOMEM; |
| |
| get_area = current->mm->get_unmapped_area; |
| if (file) { |
| if (file->f_op->get_unmapped_area) |
| get_area = file->f_op->get_unmapped_area; |
| } else if (flags & MAP_SHARED) { |
| /* |
| * mmap_region() will call shmem_zero_setup() to create a file, |
| * so use shmem's get_unmapped_area in case it can be huge. |
| * do_mmap() will clear pgoff, so match alignment. |
| */ |
| pgoff = 0; |
| get_area = shmem_get_unmapped_area; |
| } |
| |
| addr = get_area(file, addr, len, pgoff, flags); |
| if (IS_ERR_VALUE(addr)) |
| return addr; |
| |
| if (addr > TASK_SIZE - len) |
| return -ENOMEM; |
| if (offset_in_page(addr)) |
| return -EINVAL; |
| |
| error = security_mmap_addr(addr); |
| return error ? error : addr; |
| } |
| |
| EXPORT_SYMBOL(get_unmapped_area); |
| |
| /** |
| * find_vma_intersection() - Look up the first VMA which intersects the interval |
| * @mm: The process address space. |
| * @start_addr: The inclusive start user address. |
| * @end_addr: The exclusive end user address. |
| * |
| * Returns: The first VMA within the provided range, %NULL otherwise. Assumes |
| * start_addr < end_addr. |
| */ |
| struct vm_area_struct *find_vma_intersection(struct mm_struct *mm, |
| unsigned long start_addr, |
| unsigned long end_addr) |
| { |
| unsigned long index = start_addr; |
| |
| mmap_assert_locked(mm); |
| return mt_find(&mm->mm_mt, &index, end_addr - 1); |
| } |
| EXPORT_SYMBOL(find_vma_intersection); |
| |
| /** |
| * find_vma() - Find the VMA for a given address, or the next VMA. |
| * @mm: The mm_struct to check |
| * @addr: The address |
| * |
| * Returns: The VMA associated with addr, or the next VMA. |
| * May return %NULL in the case of no VMA at addr or above. |
| */ |
| struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
| { |
| unsigned long index = addr; |
| |
| mmap_assert_locked(mm); |
| return mt_find(&mm->mm_mt, &index, ULONG_MAX); |
| } |
| EXPORT_SYMBOL(find_vma); |
| |
| /** |
| * find_vma_prev() - Find the VMA for a given address, or the next vma and |
| * set %pprev to the previous VMA, if any. |
| * @mm: The mm_struct to check |
| * @addr: The address |
| * @pprev: The pointer to set to the previous VMA |
| * |
| * Note that RCU lock is missing here since the external mmap_lock() is used |
| * instead. |
| * |
| * Returns: The VMA associated with @addr, or the next vma. |
| * May return %NULL in the case of no vma at addr or above. |
| */ |
| struct vm_area_struct * |
| find_vma_prev(struct mm_struct *mm, unsigned long addr, |
| struct vm_area_struct **pprev) |
| { |
| struct vm_area_struct *vma; |
| MA_STATE(mas, &mm->mm_mt, addr, addr); |
| |
| vma = mas_walk(&mas); |
| *pprev = mas_prev(&mas, 0); |
| if (!vma) |
| vma = mas_next(&mas, ULONG_MAX); |
| return vma; |
| } |
| |
| /* |
| * Verify that the stack growth is acceptable and |
| * update accounting. This is shared with both the |
| * grow-up and grow-down cases. |
| */ |
| static int acct_stack_growth(struct vm_area_struct *vma, |
| unsigned long size, unsigned long grow) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long new_start; |
| |
| /* address space limit tests */ |
| if (!may_expand_vm(mm, vma->vm_flags, grow)) |
| return -ENOMEM; |
| |
| /* Stack limit test */ |
| if (size > rlimit(RLIMIT_STACK)) |
| return -ENOMEM; |
| |
| /* mlock limit tests */ |
| if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT)) |
| return -ENOMEM; |
| |
| /* Check to ensure the stack will not grow into a hugetlb-only region */ |
| new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : |
| vma->vm_end - size; |
| if (is_hugepage_only_range(vma->vm_mm, new_start, size)) |
| return -EFAULT; |
| |
| /* |
| * Overcommit.. This must be the final test, as it will |
| * update security statistics. |
| */ |
| if (security_vm_enough_memory_mm(mm, grow)) |
| return -ENOMEM; |
| |
| return 0; |
| } |
| |
| #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) |
| /* |
| * PA-RISC uses this for its stack; IA64 for its Register Backing Store. |
| * vma is the last one with address > vma->vm_end. Have to extend vma. |
| */ |
| static int expand_upwards(struct vm_area_struct *vma, unsigned long address) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct vm_area_struct *next; |
| unsigned long gap_addr; |
| int error = 0; |
| MA_STATE(mas, &mm->mm_mt, vma->vm_start, address); |
| |
| if (!(vma->vm_flags & VM_GROWSUP)) |
| return -EFAULT; |
| |
| /* Guard against exceeding limits of the address space. */ |
| address &= PAGE_MASK; |
| if (address >= (TASK_SIZE & PAGE_MASK)) |
| return -ENOMEM; |
| address += PAGE_SIZE; |
| |
| /* Enforce stack_guard_gap */ |
| gap_addr = address + stack_guard_gap; |
| |
| /* Guard against overflow */ |
| if (gap_addr < address || gap_addr > TASK_SIZE) |
| gap_addr = TASK_SIZE; |
| |
| next = find_vma_intersection(mm, vma->vm_end, gap_addr); |
| if (next && vma_is_accessible(next)) { |
| if (!(next->vm_flags & VM_GROWSUP)) |
| return -ENOMEM; |
| /* Check that both stack segments have the same anon_vma? */ |
| } |
| |
| if (next) |
| mas_prev_range(&mas, address); |
| |
| __mas_set_range(&mas, vma->vm_start, address - 1); |
| if (mas_preallocate(&mas, vma, GFP_KERNEL)) |
| return -ENOMEM; |
| |
| /* We must make sure the anon_vma is allocated. */ |
| if (unlikely(anon_vma_prepare(vma))) { |
| mas_destroy(&mas); |
| return -ENOMEM; |
| } |
| |
| /* Lock the VMA before expanding to prevent concurrent page faults */ |
| vma_start_write(vma); |
| /* |
| * vma->vm_start/vm_end cannot change under us because the caller |
| * is required to hold the mmap_lock in read mode. We need the |
| * anon_vma lock to serialize against concurrent expand_stacks. |
| */ |
| anon_vma_lock_write(vma->anon_vma); |
| |
| /* Somebody else might have raced and expanded it already */ |
| if (address > vma->vm_end) { |
| unsigned long size, grow; |
| |
| size = address - vma->vm_start; |
| grow = (address - vma->vm_end) >> PAGE_SHIFT; |
| |
| error = -ENOMEM; |
| if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { |
| error = acct_stack_growth(vma, size, grow); |
| if (!error) { |
| /* |
| * We only hold a shared mmap_lock lock here, so |
| * we need to protect against concurrent vma |
| * expansions. anon_vma_lock_write() doesn't |
| * help here, as we don't guarantee that all |
| * growable vmas in a mm share the same root |
| * anon vma. So, we reuse mm->page_table_lock |
| * to guard against concurrent vma expansions. |
| */ |
| spin_lock(&mm->page_table_lock); |
| if (vma->vm_flags & VM_LOCKED) |
| mm->locked_vm += grow; |
| vm_stat_account(mm, vma->vm_flags, grow); |
| anon_vma_interval_tree_pre_update_vma(vma); |
| vma->vm_end = address; |
| /* Overwrite old entry in mtree. */ |
| mas_store_prealloc(&mas, vma); |
| anon_vma_interval_tree_post_update_vma(vma); |
| spin_unlock(&mm->page_table_lock); |
| |
| perf_event_mmap(vma); |
| } |
| } |
| } |
| anon_vma_unlock_write(vma->anon_vma); |
| khugepaged_enter_vma(vma, vma->vm_flags); |
| mas_destroy(&mas); |
| validate_mm(mm); |
| return error; |
| } |
| #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ |
| |
| /* |
| * vma is the first one with address < vma->vm_start. Have to extend vma. |
| * mmap_lock held for writing. |
| */ |
| int expand_downwards(struct vm_area_struct *vma, unsigned long address) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_start); |
| struct vm_area_struct *prev; |
| int error = 0; |
| |
| if (!(vma->vm_flags & VM_GROWSDOWN)) |
| return -EFAULT; |
| |
| address &= PAGE_MASK; |
| if (address < mmap_min_addr || address < FIRST_USER_ADDRESS) |
| return -EPERM; |
| |
| /* Enforce stack_guard_gap */ |
| prev = mas_prev(&mas, 0); |
| /* Check that both stack segments have the same anon_vma? */ |
| if (prev) { |
| if (!(prev->vm_flags & VM_GROWSDOWN) && |
| vma_is_accessible(prev) && |
| (address - prev->vm_end < stack_guard_gap)) |
| return -ENOMEM; |
| } |
| |
| if (prev) |
| mas_next_range(&mas, vma->vm_start); |
| |
| __mas_set_range(&mas, address, vma->vm_end - 1); |
| if (mas_preallocate(&mas, vma, GFP_KERNEL)) |
| return -ENOMEM; |
| |
| /* We must make sure the anon_vma is allocated. */ |
| if (unlikely(anon_vma_prepare(vma))) { |
| mas_destroy(&mas); |
| return -ENOMEM; |
| } |
| |
| /* Lock the VMA before expanding to prevent concurrent page faults */ |
| vma_start_write(vma); |
| /* |
| * vma->vm_start/vm_end cannot change under us because the caller |
| * is required to hold the mmap_lock in read mode. We need the |
| * anon_vma lock to serialize against concurrent expand_stacks. |
| */ |
| anon_vma_lock_write(vma->anon_vma); |
| |
| /* Somebody else might have raced and expanded it already */ |
| if (address < vma->vm_start) { |
| unsigned long size, grow; |
| |
| size = vma->vm_end - address; |
| grow = (vma->vm_start - address) >> PAGE_SHIFT; |
| |
| error = -ENOMEM; |
| if (grow <= vma->vm_pgoff) { |
| error = acct_stack_growth(vma, size, grow); |
| if (!error) { |
| /* |
| * We only hold a shared mmap_lock lock here, so |
| * we need to protect against concurrent vma |
| * expansions. anon_vma_lock_write() doesn't |
| * help here, as we don't guarantee that all |
| * growable vmas in a mm share the same root |
| * anon vma. So, we reuse mm->page_table_lock |
| * to guard against concurrent vma expansions. |
| */ |
| spin_lock(&mm->page_table_lock); |
| if (vma->vm_flags & VM_LOCKED) |
| mm->locked_vm += grow; |
| vm_stat_account(mm, vma->vm_flags, grow); |
| anon_vma_interval_tree_pre_update_vma(vma); |
| vma->vm_start = address; |
| vma->vm_pgoff -= grow; |
| /* Overwrite old entry in mtree. */ |
| mas_store_prealloc(&mas, vma); |
| anon_vma_interval_tree_post_update_vma(vma); |
| spin_unlock(&mm->page_table_lock); |
| |
| perf_event_mmap(vma); |
| } |
| } |
| } |
| anon_vma_unlock_write(vma->anon_vma); |
| khugepaged_enter_vma(vma, vma->vm_flags); |
| mas_destroy(&mas); |
| validate_mm(mm); |
| return error; |
| } |
| |
| /* enforced gap between the expanding stack and other mappings. */ |
| unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; |
| |
| static int __init cmdline_parse_stack_guard_gap(char *p) |
| { |
| unsigned long val; |
| char *endptr; |
| |
| val = simple_strtoul(p, &endptr, 10); |
| if (!*endptr) |
| stack_guard_gap = val << PAGE_SHIFT; |
| |
| return 1; |
| } |
| __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap); |
| |
| #ifdef CONFIG_STACK_GROWSUP |
| int expand_stack_locked(struct vm_area_struct *vma, unsigned long address) |
| { |
| return expand_upwards(vma, address); |
| } |
| |
| struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr) |
| { |
| struct vm_area_struct *vma, *prev; |
| |
| addr &= PAGE_MASK; |
| vma = find_vma_prev(mm, addr, &prev); |
| if (vma && (vma->vm_start <= addr)) |
| return vma; |
| if (!prev) |
| return NULL; |
| if (expand_stack_locked(prev, addr)) |
| return NULL; |
| if (prev->vm_flags & VM_LOCKED) |
| populate_vma_page_range(prev, addr, prev->vm_end, NULL); |
| return prev; |
| } |
| #else |
| int expand_stack_locked(struct vm_area_struct *vma, unsigned long address) |
| { |
| if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) |
| return -EINVAL; |
| return expand_downwards(vma, address); |
| } |
| |
| struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr) |
| { |
| struct vm_area_struct *vma; |
| unsigned long start; |
| |
| addr &= PAGE_MASK; |
| vma = find_vma(mm, addr); |
| if (!vma) |
| return NULL; |
| if (vma->vm_start <= addr) |
| return vma; |
| start = vma->vm_start; |
| if (expand_stack_locked(vma, addr)) |
| return NULL; |
| if (vma->vm_flags & VM_LOCKED) |
| populate_vma_page_range(vma, addr, start, NULL); |
| return vma; |
| } |
| #endif |
| |
| /* |
| * IA64 has some horrid mapping rules: it can expand both up and down, |
| * but with various special rules. |
| * |
| * We'll get rid of this architecture eventually, so the ugliness is |
| * temporary. |
| */ |
| #ifdef CONFIG_IA64 |
| static inline bool vma_expand_ok(struct vm_area_struct *vma, unsigned long addr) |
| { |
| return REGION_NUMBER(addr) == REGION_NUMBER(vma->vm_start) && |
| REGION_OFFSET(addr) < RGN_MAP_LIMIT; |
| } |
| |
| /* |
| * IA64 stacks grow down, but there's a special register backing store |
| * that can grow up. Only sequentially, though, so the new address must |
| * match vm_end. |
| */ |
| static inline int vma_expand_up(struct vm_area_struct *vma, unsigned long addr) |
| { |
| if (!vma_expand_ok(vma, addr)) |
| return -EFAULT; |
| if (vma->vm_end != (addr & PAGE_MASK)) |
| return -EFAULT; |
| return expand_upwards(vma, addr); |
| } |
| |
| static inline bool vma_expand_down(struct vm_area_struct *vma, unsigned long addr) |
| { |
| if (!vma_expand_ok(vma, addr)) |
| return -EFAULT; |
| return expand_downwards(vma, addr); |
| } |
| |
| #elif defined(CONFIG_STACK_GROWSUP) |
| |
| #define vma_expand_up(vma,addr) expand_upwards(vma, addr) |
| #define vma_expand_down(vma, addr) (-EFAULT) |
| |
| #else |
| |
| #define vma_expand_up(vma,addr) (-EFAULT) |
| #define vma_expand_down(vma, addr) expand_downwards(vma, addr) |
| |
| #endif |
| |
| /* |
| * expand_stack(): legacy interface for page faulting. Don't use unless |
| * you have to. |
| * |
| * This is called with the mm locked for reading, drops the lock, takes |
| * the lock for writing, tries to look up a vma again, expands it if |
| * necessary, and downgrades the lock to reading again. |
| * |
| * If no vma is found or it can't be expanded, it returns NULL and has |
| * dropped the lock. |
| */ |
| struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr) |
| { |
| struct vm_area_struct *vma, *prev; |
| |
| mmap_read_unlock(mm); |
| if (mmap_write_lock_killable(mm)) |
| return NULL; |
| |
| vma = find_vma_prev(mm, addr, &prev); |
| if (vma && vma->vm_start <= addr) |
| goto success; |
| |
| if (prev && !vma_expand_up(prev, addr)) { |
| vma = prev; |
| goto success; |
| } |
| |
| if (vma && !vma_expand_down(vma, addr)) |
| goto success; |
| |
| mmap_write_unlock(mm); |
| return NULL; |
| |
| success: |
| mmap_write_downgrade(mm); |
| return vma; |
| } |
| |
| /* |
| * Ok - we have the memory areas we should free on a maple tree so release them, |
| * and do the vma updates. |
| * |
| * Called with the mm semaphore held. |
| */ |
| static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas) |
| { |
| unsigned long nr_accounted = 0; |
| struct vm_area_struct *vma; |
| |
| /* Update high watermark before we lower total_vm */ |
| update_hiwater_vm(mm); |
| mas_for_each(mas, vma, ULONG_MAX) { |
| long nrpages = vma_pages(vma); |
| |
| if (vma->vm_flags & VM_ACCOUNT) |
| nr_accounted += nrpages; |
| vm_stat_account(mm, vma->vm_flags, -nrpages); |
| remove_vma(vma, false); |
| } |
| vm_unacct_memory(nr_accounted); |
| } |
| |
| /* |
| * Get rid of page table information in the indicated region. |
| * |
| * Called with the mm semaphore held. |
| */ |
| static void unmap_region(struct mm_struct *mm, struct ma_state *mas, |
| struct vm_area_struct *vma, struct vm_area_struct *prev, |
| struct vm_area_struct *next, unsigned long start, |
| unsigned long end, unsigned long tree_end, bool mm_wr_locked) |
| { |
| struct mmu_gather tlb; |
| unsigned long mt_start = mas->index; |
| |
| lru_add_drain(); |
| tlb_gather_mmu(&tlb, mm); |
| update_hiwater_rss(mm); |
| unmap_vmas(&tlb, mas, vma, start, end, tree_end, mm_wr_locked); |
| mas_set(mas, mt_start); |
| free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, |
| next ? next->vm_start : USER_PGTABLES_CEILING, |
| mm_wr_locked); |
| tlb_finish_mmu(&tlb); |
| } |
| |
| /* |
| * __split_vma() bypasses sysctl_max_map_count checking. We use this where it |
| * has already been checked or doesn't make sense to fail. |
| * VMA Iterator will point to the end VMA. |
| */ |
| int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| unsigned long addr, int new_below) |
| { |
| struct vma_prepare vp; |
| struct vm_area_struct *new; |
| int err; |
| |
| WARN_ON(vma->vm_start >= addr); |
| WARN_ON(vma->vm_end <= addr); |
| |
| if (vma->vm_ops && vma->vm_ops->may_split) { |
| err = vma->vm_ops->may_split(vma, addr); |
| if (err) |
| return err; |
| } |
| |
| new = vm_area_dup(vma); |
| if (!new) |
| return -ENOMEM; |
| |
| if (new_below) { |
| new->vm_end = addr; |
| } else { |
| new->vm_start = addr; |
| new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); |
| } |
| |
| err = -ENOMEM; |
| vma_iter_config(vmi, new->vm_start, new->vm_end); |
| if (vma_iter_prealloc(vmi, new)) |
| goto out_free_vma; |
| |
| err = vma_dup_policy(vma, new); |
| if (err) |
| goto out_free_vmi; |
| |
| err = anon_vma_clone(new, vma); |
| if (err) |
| goto out_free_mpol; |
| |
| if (new->vm_file) |
| get_file(new->vm_file); |
| |
| if (new->vm_ops && new->vm_ops->open) |
| new->vm_ops->open(new); |
| |
| vma_start_write(vma); |
| vma_start_write(new); |
| |
| init_vma_prep(&vp, vma); |
| vp.insert = new; |
| vma_prepare(&vp); |
| vma_adjust_trans_huge(vma, vma->vm_start, addr, 0); |
| |
| if (new_below) { |
| vma->vm_start = addr; |
| vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT; |
| } else { |
| vma->vm_end = addr; |
| } |
| |
| /* vma_complete stores the new vma */ |
| vma_complete(&vp, vmi, vma->vm_mm); |
| |
| /* Success. */ |
| if (new_below) |
| vma_next(vmi); |
| return 0; |
| |
| out_free_mpol: |
| mpol_put(vma_policy(new)); |
| out_free_vmi: |
| vma_iter_free(vmi); |
| out_free_vma: |
| vm_area_free(new); |
| return err; |
| } |
| |
| /* |
| * Split a vma into two pieces at address 'addr', a new vma is allocated |
| * either for the first part or the tail. |
| */ |
| int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| unsigned long addr, int new_below) |
| { |
| if (vma->vm_mm->map_count >= sysctl_max_map_count) |
| return -ENOMEM; |
| |
| return __split_vma(vmi, vma, addr, new_below); |
| } |
| |
| /* |
| * do_vmi_align_munmap() - munmap the aligned region from @start to @end. |
| * @vmi: The vma iterator |
| * @vma: The starting vm_area_struct |
| * @mm: The mm_struct |
| * @start: The aligned start address to munmap. |
| * @end: The aligned end address to munmap. |
| * @uf: The userfaultfd list_head |
| * @unlock: Set to true to drop the mmap_lock. unlocking only happens on |
| * success. |
| * |
| * Return: 0 on success and drops the lock if so directed, error and leaves the |
| * lock held otherwise. |
| */ |
| static int |
| do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| struct mm_struct *mm, unsigned long start, |
| unsigned long end, struct list_head *uf, bool unlock) |
| { |
| struct vm_area_struct *prev, *next = NULL; |
| struct maple_tree mt_detach; |
| int count = 0; |
| int error = -ENOMEM; |
| unsigned long locked_vm = 0; |
| MA_STATE(mas_detach, &mt_detach, 0, 0); |
| mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK); |
| mt_on_stack(mt_detach); |
| |
| /* |
| * If we need to split any vma, do it now to save pain later. |
| * |
| * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially |
| * unmapped vm_area_struct will remain in use: so lower split_vma |
| * places tmp vma above, and higher split_vma places tmp vma below. |
| */ |
| |
| /* Does it split the first one? */ |
| if (start > vma->vm_start) { |
| |
| /* |
| * Make sure that map_count on return from munmap() will |
| * not exceed its limit; but let map_count go just above |
| * its limit temporarily, to help free resources as expected. |
| */ |
| if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) |
| goto map_count_exceeded; |
| |
| error = __split_vma(vmi, vma, start, 1); |
| if (error) |
| goto start_split_failed; |
| } |
| |
| /* |
| * Detach a range of VMAs from the mm. Using next as a temp variable as |
| * it is always overwritten. |
| */ |
| next = vma; |
| do { |
| /* Does it split the end? */ |
| if (next->vm_end > end) { |
| error = __split_vma(vmi, next, end, 0); |
| if (error) |
| goto end_split_failed; |
| } |
| vma_start_write(next); |
| mas_set(&mas_detach, count); |
| error = mas_store_gfp(&mas_detach, next, GFP_KERNEL); |
| if (error) |
| goto munmap_gather_failed; |
| vma_mark_detached(next, true); |
| if (next->vm_flags & VM_LOCKED) |
| locked_vm += vma_pages(next); |
| |
| count++; |
| if (unlikely(uf)) { |
| /* |
| * If userfaultfd_unmap_prep returns an error the vmas |
| * will remain split, but userland will get a |
| * highly unexpected error anyway. This is no |
| * different than the case where the first of the two |
| * __split_vma fails, but we don't undo the first |
| * split, despite we could. This is unlikely enough |
| * failure that it's not worth optimizing it for. |
| */ |
| error = userfaultfd_unmap_prep(next, start, end, uf); |
| |
| if (error) |
| goto userfaultfd_error; |
| } |
| #ifdef CONFIG_DEBUG_VM_MAPLE_TREE |
| BUG_ON(next->vm_start < start); |
| BUG_ON(next->vm_start > end); |
| #endif |
| } for_each_vma_range(*vmi, next, end); |
| |
| #if defined(CONFIG_DEBUG_VM_MAPLE_TREE) |
| /* Make sure no VMAs are about to be lost. */ |
| { |
| MA_STATE(test, &mt_detach, 0, 0); |
| struct vm_area_struct *vma_mas, *vma_test; |
| int test_count = 0; |
| |
| vma_iter_set(vmi, start); |
| rcu_read_lock(); |
| vma_test = mas_find(&test, count - 1); |
| for_each_vma_range(*vmi, vma_mas, end) { |
| BUG_ON(vma_mas != vma_test); |
| test_count++; |
| vma_test = mas_next(&test, count - 1); |
| } |
| rcu_read_unlock(); |
| BUG_ON(count != test_count); |
| } |
| #endif |
| |
| while (vma_iter_addr(vmi) > start) |
| vma_iter_prev_range(vmi); |
| |
| error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL); |
| if (error) |
| goto clear_tree_failed; |
| |
| /* Point of no return */ |
| mm->locked_vm -= locked_vm; |
| mm->map_count -= count; |
| if (unlock) |
| mmap_write_downgrade(mm); |
| |
| prev = vma_iter_prev_range(vmi); |
| next = vma_next(vmi); |
| if (next) |
| vma_iter_prev_range(vmi); |
| |
| /* |
| * We can free page tables without write-locking mmap_lock because VMAs |
| * were isolated before we downgraded mmap_lock. |
| */ |
| mas_set(&mas_detach, 1); |
| unmap_region(mm, &mas_detach, vma, prev, next, start, end, count, |
| !unlock); |
| /* Statistics and freeing VMAs */ |
| mas_set(&mas_detach, 0); |
| remove_mt(mm, &mas_detach); |
| validate_mm(mm); |
| if (unlock) |
| mmap_read_unlock(mm); |
| |
| __mt_destroy(&mt_detach); |
| return 0; |
| |
| clear_tree_failed: |
| userfaultfd_error: |
| munmap_gather_failed: |
| end_split_failed: |
| mas_set(&mas_detach, 0); |
| mas_for_each(&mas_detach, next, end) |
| vma_mark_detached(next, false); |
| |
| __mt_destroy(&mt_detach); |
| start_split_failed: |
| map_count_exceeded: |
| validate_mm(mm); |
| return error; |
| } |
| |
| /* |
| * do_vmi_munmap() - munmap a given range. |
| * @vmi: The vma iterator |
| * @mm: The mm_struct |
| * @start: The start address to munmap |
| * @len: The length of the range to munmap |
| * @uf: The userfaultfd list_head |
| * @unlock: set to true if the user wants to drop the mmap_lock on success |
| * |
| * This function takes a @mas that is either pointing to the previous VMA or set |
| * to MA_START and sets it up to remove the mapping(s). The @len will be |
| * aligned and any arch_unmap work will be preformed. |
| * |
| * Return: 0 on success and drops the lock if so directed, error and leaves the |
| * lock held otherwise. |
| */ |
| int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm, |
| unsigned long start, size_t len, struct list_head *uf, |
| bool unlock) |
| { |
| unsigned long end; |
| struct vm_area_struct *vma; |
| |
| if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) |
| return -EINVAL; |
| |
| end = start + PAGE_ALIGN(len); |
| if (end == start) |
| return -EINVAL; |
| |
| /* arch_unmap() might do unmaps itself. */ |
| arch_unmap(mm, start, end); |
| |
| /* Find the first overlapping VMA */ |
| vma = vma_find(vmi, end); |
| if (!vma) { |
| if (unlock) |
| mmap_write_unlock(mm); |
| return 0; |
| } |
| |
| return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock); |
| } |
| |
| /* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls. |
| * @mm: The mm_struct |
| * @start: The start address to munmap |
| * @len: The length to be munmapped. |
| * @uf: The userfaultfd list_head |
| * |
| * Return: 0 on success, error otherwise. |
| */ |
| int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, |
| struct list_head *uf) |
| { |
| VMA_ITERATOR(vmi, mm, start); |
| |
| return do_vmi_munmap(&vmi, mm, start, len, uf, false); |
| } |
| |
| unsigned long mmap_region(struct file *file, unsigned long addr, |
| unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, |
| struct list_head *uf) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma = NULL; |
| struct vm_area_struct *next, *prev, *merge; |
| pgoff_t pglen = len >> PAGE_SHIFT; |
| unsigned long charged = 0; |
| unsigned long end = addr + len; |
| unsigned long merge_start = addr, merge_end = end; |
| pgoff_t vm_pgoff; |
| int error; |
| VMA_ITERATOR(vmi, mm, addr); |
| |
| /* Check against address space limit. */ |
| if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) { |
| unsigned long nr_pages; |
| |
| /* |
| * MAP_FIXED may remove pages of mappings that intersects with |
| * requested mapping. Account for the pages it would unmap. |
| */ |
| nr_pages = count_vma_pages_range(mm, addr, end); |
| |
| if (!may_expand_vm(mm, vm_flags, |
| (len >> PAGE_SHIFT) - nr_pages)) |
| return -ENOMEM; |
| } |
| |
| /* Unmap any existing mapping in the area */ |
| if (do_vmi_munmap(&vmi, mm, addr, len, uf, false)) |
| return -ENOMEM; |
| |
| /* |
| * Private writable mapping: check memory availability |
| */ |
| if (accountable_mapping(file, vm_flags)) { |
| charged = len >> PAGE_SHIFT; |
| if (security_vm_enough_memory_mm(mm, charged)) |
| return -ENOMEM; |
| vm_flags |= VM_ACCOUNT; |
| } |
| |
| next = vma_next(&vmi); |
| prev = vma_prev(&vmi); |
| if (vm_flags & VM_SPECIAL) { |
| if (prev) |
| vma_iter_next_range(&vmi); |
| goto cannot_expand; |
| } |
| |
| /* Attempt to expand an old mapping */ |
| /* Check next */ |
| if (next && next->vm_start == end && !vma_policy(next) && |
| can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen, |
| NULL_VM_UFFD_CTX, NULL)) { |
| merge_end = next->vm_end; |
| vma = next; |
| vm_pgoff = next->vm_pgoff - pglen; |
| } |
| |
| /* Check prev */ |
| if (prev && prev->vm_end == addr && !vma_policy(prev) && |
| (vma ? can_vma_merge_after(prev, vm_flags, vma->anon_vma, file, |
| pgoff, vma->vm_userfaultfd_ctx, NULL) : |
| can_vma_merge_after(prev, vm_flags, NULL, file, pgoff, |
| NULL_VM_UFFD_CTX, NULL))) { |
| merge_start = prev->vm_start; |
| vma = prev; |
| vm_pgoff = prev->vm_pgoff; |
| } else if (prev) { |
| vma_iter_next_range(&vmi); |
| } |
| |
| /* Actually expand, if possible */ |
| if (vma && |
| !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) { |
| khugepaged_enter_vma(vma, vm_flags); |
| goto expanded; |
| } |
| |
| if (vma == prev) |
| vma_iter_set(&vmi, addr); |
| cannot_expand: |
| |
| /* |
| * Determine the object being mapped and call the appropriate |
| * specific mapper. the address has already been validated, but |
| * not unmapped, but the maps are removed from the list. |
| */ |
| vma = vm_area_alloc(mm); |
| if (!vma) { |
| error = -ENOMEM; |
| goto unacct_error; |
| } |
| |
| vma_iter_config(&vmi, addr, end); |
| vma->vm_start = addr; |
| vma->vm_end = end; |
| vm_flags_init(vma, vm_flags); |
| vma->vm_page_prot = vm_get_page_prot(vm_flags); |
| vma->vm_pgoff = pgoff; |
| |
| if (file) { |
| if (vm_flags & VM_SHARED) { |
| error = mapping_map_writable(file->f_mapping); |
| if (error) |
| goto free_vma; |
| } |
| |
| vma->vm_file = get_file(file); |
| error = call_mmap(file, vma); |
| if (error) |
| goto unmap_and_free_vma; |
| |
| /* |
| * Expansion is handled above, merging is handled below. |
| * Drivers should not alter the address of the VMA. |
| */ |
| error = -EINVAL; |
| if (WARN_ON((addr != vma->vm_start))) |
| goto close_and_free_vma; |
| |
| vma_iter_config(&vmi, addr, end); |
| /* |
| * If vm_flags changed after call_mmap(), we should try merge |
| * vma again as we may succeed this time. |
| */ |
| if (unlikely(vm_flags != vma->vm_flags && prev)) { |
| merge = vma_merge(&vmi, mm, prev, vma->vm_start, |
| vma->vm_end, vma->vm_flags, NULL, |
| vma->vm_file, vma->vm_pgoff, NULL, |
| NULL_VM_UFFD_CTX, NULL); |
| if (merge) { |
| /* |
| * ->mmap() can change vma->vm_file and fput |
| * the original file. So fput the vma->vm_file |
| * here or we would add an extra fput for file |
| * and cause general protection fault |
| * ultimately. |
| */ |
| fput(vma->vm_file); |
| vm_area_free(vma); |
| vma = merge; |
| /* Update vm_flags to pick up the change. */ |
| vm_flags = vma->vm_flags; |
| goto unmap_writable; |
| } |
| } |
| |
| vm_flags = vma->vm_flags; |
| } else if (vm_flags & VM_SHARED) { |
| error = shmem_zero_setup(vma); |
| if (error) |
| goto free_vma; |
| } else { |
| vma_set_anonymous(vma); |
| } |
| |
| if (map_deny_write_exec(vma, vma->vm_flags)) { |
| error = -EACCES; |
| goto close_and_free_vma; |
| } |
| |
| /* Allow architectures to sanity-check the vm_flags */ |
| error = -EINVAL; |
| if (!arch_validate_flags(vma->vm_flags)) |
| goto close_and_free_vma; |
| |
| error = -ENOMEM; |
| if (vma_iter_prealloc(&vmi, vma)) |
| goto close_and_free_vma; |
| |
| /* Lock the VMA since it is modified after insertion into VMA tree */ |
| vma_start_write(vma); |
| vma_iter_store(&vmi, vma); |
| mm->map_count++; |
| if (vma->vm_file) { |
| i_mmap_lock_write(vma->vm_file->f_mapping); |
| if (vma->vm_flags & VM_SHARED) |
| mapping_allow_writable(vma->vm_file->f_mapping); |
| |
| flush_dcache_mmap_lock(vma->vm_file->f_mapping); |
| vma_interval_tree_insert(vma, &vma->vm_file->f_mapping->i_mmap); |
| flush_dcache_mmap_unlock(vma->vm_file->f_mapping); |
| i_mmap_unlock_write(vma->vm_file->f_mapping); |
| } |
| |
| /* |
| * vma_merge() calls khugepaged_enter_vma() either, the below |
| * call covers the non-merge case. |
| */ |
| khugepaged_enter_vma(vma, vma->vm_flags); |
| |
| /* Once vma denies write, undo our temporary denial count */ |
| unmap_writable: |
| if (file && vm_flags & VM_SHARED) |
| mapping_unmap_writable(file->f_mapping); |
| file = vma->vm_file; |
| ksm_add_vma(vma); |
| expanded: |
| perf_event_mmap(vma); |
| |
| vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); |
| if (vm_flags & VM_LOCKED) { |
| if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || |
| is_vm_hugetlb_page(vma) || |
| vma == get_gate_vma(current->mm)) |
| vm_flags_clear(vma, VM_LOCKED_MASK); |
| else |
| mm->locked_vm += (len >> PAGE_SHIFT); |
| } |
| |
| if (file) |
| uprobe_mmap(vma); |
| |
| /* |
| * New (or expanded) vma always get soft dirty status. |
| * Otherwise user-space soft-dirty page tracker won't |
| * be able to distinguish situation when vma area unmapped, |
| * then new mapped in-place (which must be aimed as |
| * a completely new data area). |
| */ |
| vm_flags_set(vma, VM_SOFTDIRTY); |
| |
| vma_set_page_prot(vma); |
| |
| validate_mm(mm); |
| return addr; |
| |
| close_and_free_vma: |
| if (file && vma->vm_ops && vma->vm_ops->close) |
| vma->vm_ops->close(vma); |
| |
| if (file || vma->vm_file) { |
| unmap_and_free_vma: |
| fput(vma->vm_file); |
| vma->vm_file = NULL; |
| |
| vma_iter_set(&vmi, vma->vm_end); |
| /* Undo any partial mapping done by a device driver. */ |
| unmap_region(mm, &vmi.mas, vma, prev, next, vma->vm_start, |
| vma->vm_end, vma->vm_end, true); |
| } |
| if (file && (vm_flags & VM_SHARED)) |
| mapping_unmap_writable(file->f_mapping); |
| free_vma: |
| vm_area_free(vma); |
| unacct_error: |
| if (charged) |
| vm_unacct_memory(charged); |
| validate_mm(mm); |
| return error; |
| } |
| |
| static int __vm_munmap(unsigned long start, size_t len, bool unlock) |
| { |
| int ret; |
| struct mm_struct *mm = current->mm; |
| LIST_HEAD(uf); |
| VMA_ITERATOR(vmi, mm, start); |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| ret = do_vmi_munmap(&vmi, mm, start, len, &uf, unlock); |
| if (ret || !unlock) |
| mmap_write_unlock(mm); |
| |
| userfaultfd_unmap_complete(mm, &uf); |
| return ret; |
| } |
| |
| int vm_munmap(unsigned long start, size_t len) |
| { |
| return __vm_munmap(start, len, false); |
| } |
| EXPORT_SYMBOL(vm_munmap); |
| |
| SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
| { |
| addr = untagged_addr(addr); |
| return __vm_munmap(addr, len, true); |
| } |
| |
| |
| /* |
| * Emulation of deprecated remap_file_pages() syscall. |
| */ |
| SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, |
| unsigned long, prot, unsigned long, pgoff, unsigned long, flags) |
| { |
| |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| unsigned long populate = 0; |
| unsigned long ret = -EINVAL; |
| struct file *file; |
| |
| pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n", |
| current->comm, current->pid); |
| |
| if (prot) |
| return ret; |
| start = start & PAGE_MASK; |
| size = size & PAGE_MASK; |
| |
| if (start + size <= start) |
| return ret; |
| |
| /* Does pgoff wrap? */ |
| if (pgoff + (size >> PAGE_SHIFT) < pgoff) |
| return ret; |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| vma = vma_lookup(mm, start); |
| |
| if (!vma || !(vma->vm_flags & VM_SHARED)) |
| goto out; |
| |
| if (start + size > vma->vm_end) { |
| VMA_ITERATOR(vmi, mm, vma->vm_end); |
| struct vm_area_struct *next, *prev = vma; |
| |
| for_each_vma_range(vmi, next, start + size) { |
| /* hole between vmas ? */ |
| if (next->vm_start != prev->vm_end) |
| goto out; |
| |
| if (next->vm_file != vma->vm_file) |
| goto out; |
| |
| if (next->vm_flags != vma->vm_flags) |
| goto out; |
| |
| if (start + size <= next->vm_end) |
| break; |
| |
| prev = next; |
| } |
| |
| if (!next) |
| goto out; |
| } |
| |
| prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; |
| prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; |
| prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; |
| |
| flags &= MAP_NONBLOCK; |
| flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; |
| if (vma->vm_flags & VM_LOCKED) |
| flags |= MAP_LOCKED; |
| |
| file = get_file(vma->vm_file); |
| ret = do_mmap(vma->vm_file, start, size, |
| prot, flags, 0, pgoff, &populate, NULL); |
| fput(file); |
| out: |
| mmap_write_unlock(mm); |
| if (populate) |
| mm_populate(ret, populate); |
| if (!IS_ERR_VALUE(ret)) |
| ret = 0; |
| return ret; |
| } |
| |
| /* |
| * do_vma_munmap() - Unmap a full or partial vma. |
| * @vmi: The vma iterator pointing at the vma |
| * @vma: The first vma to be munmapped |
| * @start: the start of the address to unmap |
| * @end: The end of the address to unmap |
| * @uf: The userfaultfd list_head |
| * @unlock: Drop the lock on success |
| * |
| * unmaps a VMA mapping when the vma iterator is already in position. |
| * Does not handle alignment. |
| * |
| * Return: 0 on success drops the lock of so directed, error on failure and will |
| * still hold the lock. |
| */ |
| int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| unsigned long start, unsigned long end, struct list_head *uf, |
| bool unlock) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| |
| arch_unmap(mm, start, end); |
| return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock); |
| } |
| |
| /* |
| * do_brk_flags() - Increase the brk vma if the flags match. |
| * @vmi: The vma iterator |
| * @addr: The start address |
| * @len: The length of the increase |
| * @vma: The vma, |
| * @flags: The VMA Flags |
| * |
| * Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags |
| * do not match then create a new anonymous VMA. Eventually we may be able to |
| * do some brk-specific accounting here. |
| */ |
| static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, |
| unsigned long addr, unsigned long len, unsigned long flags) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vma_prepare vp; |
| |
| /* |
| * Check against address space limits by the changed size |
| * Note: This happens *after* clearing old mappings in some code paths. |
| */ |
| flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; |
| if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) |
| return -ENOMEM; |
| |
| if (mm->map_count > sysctl_max_map_count) |
| return -ENOMEM; |
| |
| if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) |
| return -ENOMEM; |
| |
| /* |
| * Expand the existing vma if possible; Note that singular lists do not |
| * occur after forking, so the expand will only happen on new VMAs. |
| */ |
| if (vma && vma->vm_end == addr && !vma_policy(vma) && |
| can_vma_merge_after(vma, flags, NULL, NULL, |
| addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) { |
| vma_iter_config(vmi, vma->vm_start, addr + len); |
| if (vma_iter_prealloc(vmi, vma)) |
| goto unacct_fail; |
| |
| vma_start_write(vma); |
| |
| init_vma_prep(&vp, vma); |
| vma_prepare(&vp); |
| vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0); |
| vma->vm_end = addr + len; |
| vm_flags_set(vma, VM_SOFTDIRTY); |
| vma_iter_store(vmi, vma); |
| |
| vma_complete(&vp, vmi, mm); |
| khugepaged_enter_vma(vma, flags); |
| goto out; |
| } |
| |
| if (vma) |
| vma_iter_next_range(vmi); |
| /* create a vma struct for an anonymous mapping */ |
| vma = vm_area_alloc(mm); |
| if (!vma) |
| goto unacct_fail; |
| |
| vma_set_anonymous(vma); |
| vma->vm_start = addr; |
| vma->vm_end = addr + len; |
| vma->vm_pgoff = addr >> PAGE_SHIFT; |
| vm_flags_init(vma, flags); |
| vma->vm_page_prot = vm_get_page_prot(flags); |
| vma_start_write(vma); |
| if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL)) |
| goto mas_store_fail; |
| |
| mm->map_count++; |
| validate_mm(mm); |
| ksm_add_vma(vma); |
| out: |
| perf_event_mmap(vma); |
| mm->total_vm += len >> PAGE_SHIFT; |
| mm->data_vm += len >> PAGE_SHIFT; |
| if (flags & VM_LOCKED) |
| mm->locked_vm += (len >> PAGE_SHIFT); |
| vm_flags_set(vma, VM_SOFTDIRTY); |
| return 0; |
| |
| mas_store_fail: |
| vm_area_free(vma); |
| unacct_fail: |
| vm_unacct_memory(len >> PAGE_SHIFT); |
| return -ENOMEM; |
| } |
| |
| int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma = NULL; |
| unsigned long len; |
| int ret; |
| bool populate; |
| LIST_HEAD(uf); |
| VMA_ITERATOR(vmi, mm, addr); |
| |
| len = PAGE_ALIGN(request); |
| if (len < request) |
| return -ENOMEM; |
| if (!len) |
| return 0; |
| |
| /* Until we need other flags, refuse anything except VM_EXEC. */ |
| if ((flags & (~VM_EXEC)) != 0) |
| return -EINVAL; |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| ret = check_brk_limits(addr, len); |
| if (ret) |
| goto limits_failed; |
| |
| ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0); |
| if (ret) |
| goto munmap_failed; |
| |
| vma = vma_prev(&vmi); |
| ret = do_brk_flags(&vmi, vma, addr, len, flags); |
| populate = ((mm->def_flags & VM_LOCKED) != 0); |
| mmap_write_unlock(mm); |
| userfaultfd_unmap_complete(mm, &uf); |
| if (populate && !ret) |
| mm_populate(addr, len); |
| return ret; |
| |
| munmap_failed: |
| limits_failed: |
| mmap_write_unlock(mm); |
| return ret; |
| } |
| EXPORT_SYMBOL(vm_brk_flags); |
| |
| int vm_brk(unsigned long addr, unsigned long len) |
| { |
| return vm_brk_flags(addr, len, 0); |
| } |
| EXPORT_SYMBOL(vm_brk); |
| |
| /* Release all mmaps. */ |
| void exit_mmap(struct mm_struct *mm) |
| { |
| struct mmu_gather tlb; |
| struct vm_area_struct *vma; |
| unsigned long nr_accounted = 0; |
| MA_STATE(mas, &mm->mm_mt, 0, 0); |
| int count = 0; |
| |
| /* mm's last user has gone, and its about to be pulled down */ |
| mmu_notifier_release(mm); |
| |
| mmap_read_lock(mm); |
| arch_exit_mmap(mm); |
| |
| vma = mas_find(&mas, ULONG_MAX); |
| if (!vma) { |
| /* Can happen if dup_mmap() received an OOM */ |
| mmap_read_unlock(mm); |
| return; |
| } |
| |
| lru_add_drain(); |
| flush_cache_mm(mm); |
| tlb_gather_mmu_fullmm(&tlb, mm); |
| /* update_hiwater_rss(mm) here? but nobody should be looking */ |
| /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */ |
| unmap_vmas(&tlb, &mas, vma, 0, ULONG_MAX, ULONG_MAX, false); |
| mmap_read_unlock(mm); |
| |
| /* |
| * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper |
| * because the memory has been already freed. |
| */ |
| set_bit(MMF_OOM_SKIP, &mm->flags); |
| mmap_write_lock(mm); |
| mt_clear_in_rcu(&mm->mm_mt); |
| mas_set(&mas, vma->vm_end); |
| free_pgtables(&tlb, &mas, vma, FIRST_USER_ADDRESS, |
| USER_PGTABLES_CEILING, true); |
| tlb_finish_mmu(&tlb); |
| |
| /* |
| * Walk the list again, actually closing and freeing it, with preemption |
| * enabled, without holding any MM locks besides the unreachable |
| * mmap_write_lock. |
| */ |
| mas_set(&mas, vma->vm_end); |
| do { |
| if (vma->vm_flags & VM_ACCOUNT) |
| nr_accounted += vma_pages(vma); |
| remove_vma(vma, true); |
| count++; |
| cond_resched(); |
| } while ((vma = mas_find(&mas, ULONG_MAX)) != NULL); |
| |
| BUG_ON(count != mm->map_count); |
| |
| trace_exit_mmap(mm); |
| __mt_destroy(&mm->mm_mt); |
| mmap_write_unlock(mm); |
| vm_unacct_memory(nr_accounted); |
| } |
| |
| /* Insert vm structure into process list sorted by address |
| * and into the inode's i_mmap tree. If vm_file is non-NULL |
| * then i_mmap_rwsem is taken here. |
| */ |
| int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) |
| { |
| unsigned long charged = vma_pages(vma); |
| |
| |
| if (find_vma_intersection(mm, vma->vm_start, vma->vm_end)) |
| return -ENOMEM; |
| |
| if ((vma->vm_flags & VM_ACCOUNT) && |
| security_vm_enough_memory_mm(mm, charged)) |
| return -ENOMEM; |
| |
| /* |
| * The vm_pgoff of a purely anonymous vma should be irrelevant |
| * until its first write fault, when page's anon_vma and index |
| * are set. But now set the vm_pgoff it will almost certainly |
| * end up with (unless mremap moves it elsewhere before that |
| * first wfault), so /proc/pid/maps tells a consistent story. |
| * |
| * By setting it to reflect the virtual start address of the |
| * vma, merges and splits can happen in a seamless way, just |
| * using the existing file pgoff checks and manipulations. |
| * Similarly in do_mmap and in do_brk_flags. |
| */ |
| if (vma_is_anonymous(vma)) { |
| BUG_ON(vma->anon_vma); |
| vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; |
| } |
| |
| if (vma_link(mm, vma)) { |
| vm_unacct_memory(charged); |
| return -ENOMEM; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Copy the vma structure to a new location in the same mm, |
| * prior to moving page table entries, to effect an mremap move. |
| */ |
| struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, |
| unsigned long addr, unsigned long len, pgoff_t pgoff, |
| bool *need_rmap_locks) |
| { |
| struct vm_area_struct *vma = *vmap; |
| unsigned long vma_start = vma->vm_start; |
| struct mm_struct *mm = vma->vm_mm; |
| struct vm_area_struct *new_vma, *prev; |
| bool faulted_in_anon_vma = true; |
| VMA_ITERATOR(vmi, mm, addr); |
| |
| /* |
| * If anonymous vma has not yet been faulted, update new pgoff |
| * to match new location, to increase its chance of merging. |
| */ |
| if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { |
| pgoff = addr >> PAGE_SHIFT; |
| faulted_in_anon_vma = false; |
| } |
| |
| new_vma = find_vma_prev(mm, addr, &prev); |
| if (new_vma && new_vma->vm_start < addr + len) |
| return NULL; /* should never get here */ |
| |
| new_vma = vma_merge(&vmi, mm, prev, addr, addr + len, vma->vm_flags, |
| vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), |
| vma->vm_userfaultfd_ctx, anon_vma_name(vma)); |
| if (new_vma) { |
| /* |
| * Source vma may have been merged into new_vma |
| */ |
| if (unlikely(vma_start >= new_vma->vm_start && |
| vma_start < new_vma->vm_end)) { |
| /* |
| * The only way we can get a vma_merge with |
| * self during an mremap is if the vma hasn't |
| * been faulted in yet and we were allowed to |
| * reset the dst vma->vm_pgoff to the |
| * destination address of the mremap to allow |
| * the merge to happen. mremap must change the |
| * vm_pgoff linearity between src and dst vmas |
| * (in turn preventing a vma_merge) to be |
| * safe. It is only safe to keep the vm_pgoff |
| * linear if there are no pages mapped yet. |
| */ |
| VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); |
| *vmap = vma = new_vma; |
| } |
| *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); |
| } else { |
| new_vma = vm_area_dup(vma); |
| if (!new_vma) |
| goto out; |
| new_vma->vm_start = addr; |
| new_vma->vm_end = addr + len; |
| new_vma->vm_pgoff = pgoff; |
| if (vma_dup_policy(vma, new_vma)) |
| goto out_free_vma; |
| if (anon_vma_clone(new_vma, vma)) |
| goto out_free_mempol; |
| if (new_vma->vm_file) |
| get_file(new_vma->vm_file); |
| if (new_vma->vm_ops && new_vma->vm_ops->open) |
| new_vma->vm_ops->open(new_vma); |
| if (vma_link(mm, new_vma)) |
| goto out_vma_link; |
| *need_rmap_locks = false; |
| } |
| return new_vma; |
| |
| out_vma_link: |
| if (new_vma->vm_ops && new_vma->vm_ops->close) |
| new_vma->vm_ops->close(new_vma); |
| |
| if (new_vma->vm_file) |
| fput(new_vma->vm_file); |
| |
| unlink_anon_vmas(new_vma); |
| out_free_mempol: |
| mpol_put(vma_policy(new_vma)); |
| out_free_vma: |
| vm_area_free(new_vma); |
| out: |
| return NULL; |
| } |
| |
| /* |
| * Return true if the calling process may expand its vm space by the passed |
| * number of pages |
| */ |
| bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) |
| { |
| if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) |
| return false; |
| |
| if (is_data_mapping(flags) && |
| mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) { |
| /* Workaround for Valgrind */ |
| if (rlimit(RLIMIT_DATA) == 0 && |
| mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT) |
| return true; |
| |
| pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n", |
| current->comm, current->pid, |
| (mm->data_vm + npages) << PAGE_SHIFT, |
| rlimit(RLIMIT_DATA), |
| ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data"); |
| |
| if (!ignore_rlimit_data) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) |
| { |
| WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages); |
| |
| if (is_exec_mapping(flags)) |
| mm->exec_vm += npages; |
| else if (is_stack_mapping(flags)) |
| mm->stack_vm += npages; |
| else if (is_data_mapping(flags)) |
| mm->data_vm += npages; |
| } |
| |
| static vm_fault_t special_mapping_fault(struct vm_fault *vmf); |
| |
| /* |
| * Having a close hook prevents vma merging regardless of flags. |
| */ |
| static void special_mapping_close(struct vm_area_struct *vma) |
| { |
| } |
| |
| static const char *special_mapping_name(struct vm_area_struct *vma) |
| { |
| return ((struct vm_special_mapping *)vma->vm_private_data)->name; |
| } |
| |
| static int special_mapping_mremap(struct vm_area_struct *new_vma) |
| { |
| struct vm_special_mapping *sm = new_vma->vm_private_data; |
| |
| if (WARN_ON_ONCE(current->mm != new_vma->vm_mm)) |
| return -EFAULT; |
| |
| if (sm->mremap) |
| return sm->mremap(sm, new_vma); |
| |
| return 0; |
| } |
| |
| static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr) |
| { |
| /* |
| * Forbid splitting special mappings - kernel has expectations over |
| * the number of pages in mapping. Together with VM_DONTEXPAND |
| * the size of vma should stay the same over the special mapping's |
| * lifetime. |
| */ |
| return -EINVAL; |
| } |
| |
| static const struct vm_operations_struct special_mapping_vmops = { |
| .close = special_mapping_close, |
| .fault = special_mapping_fault, |
| .mremap = special_mapping_mremap, |
| .name = special_mapping_name, |
| /* vDSO code relies that VVAR can't be accessed remotely */ |
| .access = NULL, |
| .may_split = special_mapping_split, |
| }; |
| |
| static const struct vm_operations_struct legacy_special_mapping_vmops = { |
| .close = special_mapping_close, |
| .fault = special_mapping_fault, |
| }; |
| |
| static vm_fault_t special_mapping_fault(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| pgoff_t pgoff; |
| struct page **pages; |
| |
| if (vma->vm_ops == &legacy_special_mapping_vmops) { |
| pages = vma->vm_private_data; |
| } else { |
| struct vm_special_mapping *sm = vma->vm_private_data; |
| |
| if (sm->fault) |
| return sm->fault(sm, vmf->vma, vmf); |
| |
| pages = sm->pages; |
| } |
| |
| for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) |
| pgoff--; |
| |
| if (*pages) { |
| struct page *page = *pages; |
| get_page(page); |
| vmf->page = page; |
| return 0; |
| } |
| |
| return VM_FAULT_SIGBUS; |
| } |
| |
| static struct vm_area_struct *__install_special_mapping( |
| struct mm_struct *mm, |
| unsigned long addr, unsigned long len, |
| unsigned long vm_flags, void *priv, |
| const struct vm_operations_struct *ops) |
| { |
| int ret; |
| struct vm_area_struct *vma; |
| |
| vma = vm_area_alloc(mm); |
| if (unlikely(vma == NULL)) |
| return ERR_PTR(-ENOMEM); |
| |
| vma->vm_start = addr; |
| vma->vm_end = addr + len; |
| |
| vm_flags_init(vma, (vm_flags | mm->def_flags | |
| VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK); |
| vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| |
| vma->vm_ops = ops; |
| vma->vm_private_data = priv; |
| |
| ret = insert_vm_struct(mm, vma); |
| if (ret) |
| goto out; |
| |
| vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT); |
| |
| perf_event_mmap(vma); |
| |
| return vma; |
| |
| out: |
| vm_area_free(vma); |
| return ERR_PTR(ret); |
| } |
| |
| bool vma_is_special_mapping(const struct vm_area_struct *vma, |
| const struct vm_special_mapping *sm) |
| { |
| return vma->vm_private_data == sm && |
| (vma->vm_ops == &special_mapping_vmops || |
| vma->vm_ops == &legacy_special_mapping_vmops); |
| } |
| |
| /* |
| * Called with mm->mmap_lock held for writing. |
| * Insert a new vma covering the given region, with the given flags. |
| * Its pages are supplied by the given array of struct page *. |
| * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. |
| * The region past the last page supplied will always produce SIGBUS. |
| * The array pointer and the pages it points to are assumed to stay alive |
| * for as long as this mapping might exist. |
| */ |
| struct vm_area_struct *_install_special_mapping( |
| struct mm_struct *mm, |
| unsigned long addr, unsigned long len, |
| unsigned long vm_flags, const struct vm_special_mapping *spec) |
| { |
| return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec, |
| &special_mapping_vmops); |
| } |
| |
| int install_special_mapping(struct mm_struct *mm, |
| unsigned long addr, unsigned long len, |
| unsigned long vm_flags, struct page **pages) |
| { |
| struct vm_area_struct *vma = __install_special_mapping( |
| mm, addr, len, vm_flags, (void *)pages, |
| &legacy_special_mapping_vmops); |
| |
| return PTR_ERR_OR_ZERO(vma); |
| } |
| |
| static DEFINE_MUTEX(mm_all_locks_mutex); |
| |
| static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) |
| { |
| if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { |
| /* |
| * The LSB of head.next can't change from under us |
| * because we hold the mm_all_locks_mutex. |
| */ |
| down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock); |
| /* |
| * We can safely modify head.next after taking the |
| * anon_vma->root->rwsem. If some other vma in this mm shares |
| * the same anon_vma we won't take it again. |
| * |
| * No need of atomic instructions here, head.next |
| * can't change from under us thanks to the |
| * anon_vma->root->rwsem. |
| */ |
| if (__test_and_set_bit(0, (unsigned long *) |
| &anon_vma->root->rb_root.rb_root.rb_node)) |
| BUG(); |
| } |
| } |
| |
| static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) |
| { |
| if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| /* |
| * AS_MM_ALL_LOCKS can't change from under us because |
| * we hold the mm_all_locks_mutex. |
| * |
| * Operations on ->flags have to be atomic because |
| * even if AS_MM_ALL_LOCKS is stable thanks to the |
| * mm_all_locks_mutex, there may be other cpus |
| * changing other bitflags in parallel to us. |
| */ |
| if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) |
| BUG(); |
| down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock); |
| } |
| } |
| |
| /* |
| * This operation locks against the VM for all pte/vma/mm related |
| * operations that could ever happen on a certain mm. This includes |
| * vmtruncate, try_to_unmap, and all page faults. |
| * |
| * The caller must take the mmap_lock in write mode before calling |
| * mm_take_all_locks(). The caller isn't allowed to release the |
| * mmap_lock until mm_drop_all_locks() returns. |
| * |
| * mmap_lock in write mode is required in order to block all operations |
| * that could modify pagetables and free pages without need of |
| * altering the vma layout. It's also needed in write mode to avoid new |
| * anon_vmas to be associated with existing vmas. |
| * |
| * A single task can't take more than one mm_take_all_locks() in a row |
| * or it would deadlock. |
| * |
| * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in |
| * mapping->flags avoid to take the same lock twice, if more than one |
| * vma in this mm is backed by the same anon_vma or address_space. |
| * |
| * We take locks in following order, accordingly to comment at beginning |
| * of mm/rmap.c: |
| * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for |
| * hugetlb mapping); |
| * - all vmas marked locked |
| * - all i_mmap_rwsem locks; |
| * - all anon_vma->rwseml |
| * |
| * We can take all locks within these types randomly because the VM code |
| * doesn't nest them and we protected from parallel mm_take_all_locks() by |
| * mm_all_locks_mutex. |
| * |
| * mm_take_all_locks() and mm_drop_all_locks are expensive operations |
| * that may have to take thousand of locks. |
| * |
| * mm_take_all_locks() can fail if it's interrupted by signals. |
| */ |
| int mm_take_all_locks(struct mm_struct *mm) |
| { |
| struct vm_area_struct *vma; |
| struct anon_vma_chain *avc; |
| MA_STATE(mas, &mm->mm_mt, 0, 0); |
| |
| mmap_assert_write_locked(mm); |
| |
| mutex_lock(&mm_all_locks_mutex); |
| |
| /* |
| * vma_start_write() does not have a complement in mm_drop_all_locks() |
| * because vma_start_write() is always asymmetrical; it marks a VMA as |
| * being written to until mmap_write_unlock() or mmap_write_downgrade() |
| * is reached. |
| */ |
| mas_for_each(&mas, vma, ULONG_MAX) { |
| if (signal_pending(current)) |
| goto out_unlock; |
| vma_start_write(vma); |
| } |
| |
| mas_set(&mas, 0); |
| mas_for_each(&mas, vma, ULONG_MAX) { |
| if (signal_pending(current)) |
| goto out_unlock; |
| if (vma->vm_file && vma->vm_file->f_mapping && |
| is_vm_hugetlb_page(vma)) |
| vm_lock_mapping(mm, vma->vm_file->f_mapping); |
| } |
| |
| mas_set(&mas, 0); |
| mas_for_each(&mas, vma, ULONG_MAX) { |
| if (signal_pending(current)) |
| goto out_unlock; |
| if (vma->vm_file && vma->vm_file->f_mapping && |
| !is_vm_hugetlb_page(vma)) |
| vm_lock_mapping(mm, vma->vm_file->f_mapping); |
| } |
| |
| mas_set(&mas, 0); |
| mas_for_each(&mas, vma, ULONG_MAX) { |
| if (signal_pending(current)) |
| goto out_unlock; |
| if (vma->anon_vma) |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| vm_lock_anon_vma(mm, avc->anon_vma); |
| } |
| |
| return 0; |
| |
| out_unlock: |
| mm_drop_all_locks(mm); |
| return -EINTR; |
| } |
| |
| static void vm_unlock_anon_vma(struct anon_vma *anon_vma) |
| { |
| if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { |
| /* |
| * The LSB of head.next can't change to 0 from under |
| * us because we hold the mm_all_locks_mutex. |
| * |
| * We must however clear the bitflag before unlocking |
| * the vma so the users using the anon_vma->rb_root will |
| * never see our bitflag. |
| * |
| * No need of atomic instructions here, head.next |
| * can't change from under us until we release the |
| * anon_vma->root->rwsem. |
| */ |
| if (!__test_and_clear_bit(0, (unsigned long *) |
| &anon_vma->root->rb_root.rb_root.rb_node)) |
| BUG(); |
| anon_vma_unlock_write(anon_vma); |
| } |
| } |
| |
| static void vm_unlock_mapping(struct address_space *mapping) |
| { |
| if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
| /* |
| * AS_MM_ALL_LOCKS can't change to 0 from under us |
| * because we hold the mm_all_locks_mutex. |
| */ |
| i_mmap_unlock_write(mapping); |
| if (!test_and_clear_bit(AS_MM_ALL_LOCKS, |
| &mapping->flags)) |
| BUG(); |
| } |
| } |
| |
| /* |
| * The mmap_lock cannot be released by the caller until |
| * mm_drop_all_locks() returns. |
| */ |
| void mm_drop_all_locks(struct mm_struct *mm) |
| { |
| struct vm_area_struct *vma; |
| struct anon_vma_chain *avc; |
| MA_STATE(mas, &mm->mm_mt, 0, 0); |
| |
| mmap_assert_write_locked(mm); |
| BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); |
| |
| mas_for_each(&mas, vma, ULONG_MAX) { |
| if (vma->anon_vma) |
| list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
| vm_unlock_anon_vma(avc->anon_vma); |
| if (vma->vm_file && vma->vm_file->f_mapping) |
| vm_unlock_mapping(vma->vm_file->f_mapping); |
| } |
| |
| mutex_unlock(&mm_all_locks_mutex); |
| } |
| |
| /* |
| * initialise the percpu counter for VM |
| */ |
| void __init mmap_init(void) |
| { |
| int ret; |
| |
| ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); |
| VM_BUG_ON(ret); |
| } |
| |
| /* |
| * Initialise sysctl_user_reserve_kbytes. |
| * |
| * This is intended to prevent a user from starting a single memory hogging |
| * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER |
| * mode. |
| * |
| * The default value is min(3% of free memory, 128MB) |
| * 128MB is enough to recover with sshd/login, bash, and top/kill. |
| */ |
| static int init_user_reserve(void) |
| { |
| unsigned long free_kbytes; |
| |
| free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); |
| |
| sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); |
| return 0; |
| } |
| subsys_initcall(init_user_reserve); |
| |
| /* |
| * Initialise sysctl_admin_reserve_kbytes. |
| * |
| * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin |
| * to log in and kill a memory hogging process. |
| * |
| * Systems with more than 256MB will reserve 8MB, enough to recover |
| * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will |
| * only reserve 3% of free pages by default. |
| */ |
| static int init_admin_reserve(void) |
| { |
| unsigned long free_kbytes; |
| |
| free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); |
| |
| sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); |
| return 0; |
| } |
| subsys_initcall(init_admin_reserve); |
| |
| /* |
| * Reinititalise user and admin reserves if memory is added or removed. |
| * |
| * The default user reserve max is 128MB, and the default max for the |
| * admin reserve is 8MB. These are usually, but not always, enough to |
| * enable recovery from a memory hogging process using login/sshd, a shell, |
| * and tools like top. It may make sense to increase or even disable the |
| * reserve depending on the existence of swap or variations in the recovery |
| * tools. So, the admin may have changed them. |
| * |
| * If memory is added and the reserves have been eliminated or increased above |
| * the default max, then we'll trust the admin. |
| * |
| * If memory is removed and there isn't enough free memory, then we |
| * need to reset the reserves. |
| * |
| * Otherwise keep the reserve set by the admin. |
| */ |
| static int reserve_mem_notifier(struct notifier_block *nb, |
| unsigned long action, void *data) |
| { |
| unsigned long tmp, free_kbytes; |
| |
| switch (action) { |
| case MEM_ONLINE: |
| /* Default max is 128MB. Leave alone if modified by operator. */ |
| tmp = sysctl_user_reserve_kbytes; |
| if (0 < tmp && tmp < (1UL << 17)) |
| init_user_reserve(); |
| |
| /* Default max is 8MB. Leave alone if modified by operator. */ |
| tmp = sysctl_admin_reserve_kbytes; |
| if (0 < tmp && tmp < (1UL << 13)) |
| init_admin_reserve(); |
| |
| break; |
| case MEM_OFFLINE: |
| free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); |
| |
| if (sysctl_user_reserve_kbytes > free_kbytes) { |
| init_user_reserve(); |
| pr_info("vm.user_reserve_kbytes reset to %lu\n", |
| sysctl_user_reserve_kbytes); |
| } |
| |
| if (sysctl_admin_reserve_kbytes > free_kbytes) { |
| init_admin_reserve(); |
| pr_info("vm.admin_reserve_kbytes reset to %lu\n", |
| sysctl_admin_reserve_kbytes); |
| } |
| break; |
| default: |
| break; |
| } |
| return NOTIFY_OK; |
| } |
| |
| static int __meminit init_reserve_notifier(void) |
| { |
| if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI)) |
| pr_err("Failed registering memory add/remove notifier for admin reserve\n"); |
| |
| return 0; |
| } |
| subsys_initcall(init_reserve_notifier); |