| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * High memory handling common code and variables. |
| * |
| * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de |
| * Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de |
| * |
| * |
| * Redesigned the x86 32-bit VM architecture to deal with |
| * 64-bit physical space. With current x86 CPUs this |
| * means up to 64 Gigabytes physical RAM. |
| * |
| * Rewrote high memory support to move the page cache into |
| * high memory. Implemented permanent (schedulable) kmaps |
| * based on Linus' idea. |
| * |
| * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/export.h> |
| #include <linux/swap.h> |
| #include <linux/bio.h> |
| #include <linux/pagemap.h> |
| #include <linux/mempool.h> |
| #include <linux/init.h> |
| #include <linux/hash.h> |
| #include <linux/highmem.h> |
| #include <linux/kgdb.h> |
| #include <asm/tlbflush.h> |
| #include <linux/vmalloc.h> |
| |
| /* |
| * Virtual_count is not a pure "count". |
| * 0 means that it is not mapped, and has not been mapped |
| * since a TLB flush - it is usable. |
| * 1 means that there are no users, but it has been mapped |
| * since the last TLB flush - so we can't use it. |
| * n means that there are (n-1) current users of it. |
| */ |
| #ifdef CONFIG_HIGHMEM |
| |
| /* |
| * Architecture with aliasing data cache may define the following family of |
| * helper functions in its asm/highmem.h to control cache color of virtual |
| * addresses where physical memory pages are mapped by kmap. |
| */ |
| #ifndef get_pkmap_color |
| |
| /* |
| * Determine color of virtual address where the page should be mapped. |
| */ |
| static inline unsigned int get_pkmap_color(struct page *page) |
| { |
| return 0; |
| } |
| #define get_pkmap_color get_pkmap_color |
| |
| /* |
| * Get next index for mapping inside PKMAP region for page with given color. |
| */ |
| static inline unsigned int get_next_pkmap_nr(unsigned int color) |
| { |
| static unsigned int last_pkmap_nr; |
| |
| last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; |
| return last_pkmap_nr; |
| } |
| |
| /* |
| * Determine if page index inside PKMAP region (pkmap_nr) of given color |
| * has wrapped around PKMAP region end. When this happens an attempt to |
| * flush all unused PKMAP slots is made. |
| */ |
| static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color) |
| { |
| return pkmap_nr == 0; |
| } |
| |
| /* |
| * Get the number of PKMAP entries of the given color. If no free slot is |
| * found after checking that many entries, kmap will sleep waiting for |
| * someone to call kunmap and free PKMAP slot. |
| */ |
| static inline int get_pkmap_entries_count(unsigned int color) |
| { |
| return LAST_PKMAP; |
| } |
| |
| /* |
| * Get head of a wait queue for PKMAP entries of the given color. |
| * Wait queues for different mapping colors should be independent to avoid |
| * unnecessary wakeups caused by freeing of slots of other colors. |
| */ |
| static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color) |
| { |
| static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); |
| |
| return &pkmap_map_wait; |
| } |
| #endif |
| |
| atomic_long_t _totalhigh_pages __read_mostly; |
| EXPORT_SYMBOL(_totalhigh_pages); |
| |
| unsigned int __nr_free_highpages(void) |
| { |
| struct zone *zone; |
| unsigned int pages = 0; |
| |
| for_each_populated_zone(zone) { |
| if (is_highmem(zone)) |
| pages += zone_page_state(zone, NR_FREE_PAGES); |
| } |
| |
| return pages; |
| } |
| |
| static int pkmap_count[LAST_PKMAP]; |
| static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); |
| |
| pte_t *pkmap_page_table; |
| |
| /* |
| * Most architectures have no use for kmap_high_get(), so let's abstract |
| * the disabling of IRQ out of the locking in that case to save on a |
| * potential useless overhead. |
| */ |
| #ifdef ARCH_NEEDS_KMAP_HIGH_GET |
| #define lock_kmap() spin_lock_irq(&kmap_lock) |
| #define unlock_kmap() spin_unlock_irq(&kmap_lock) |
| #define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags) |
| #define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags) |
| #else |
| #define lock_kmap() spin_lock(&kmap_lock) |
| #define unlock_kmap() spin_unlock(&kmap_lock) |
| #define lock_kmap_any(flags) \ |
| do { spin_lock(&kmap_lock); (void)(flags); } while (0) |
| #define unlock_kmap_any(flags) \ |
| do { spin_unlock(&kmap_lock); (void)(flags); } while (0) |
| #endif |
| |
| struct page *__kmap_to_page(void *vaddr) |
| { |
| unsigned long addr = (unsigned long)vaddr; |
| |
| if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) { |
| int i = PKMAP_NR(addr); |
| |
| return pte_page(pkmap_page_table[i]); |
| } |
| |
| return virt_to_page(addr); |
| } |
| EXPORT_SYMBOL(__kmap_to_page); |
| |
| static void flush_all_zero_pkmaps(void) |
| { |
| int i; |
| int need_flush = 0; |
| |
| flush_cache_kmaps(); |
| |
| for (i = 0; i < LAST_PKMAP; i++) { |
| struct page *page; |
| |
| /* |
| * zero means we don't have anything to do, |
| * >1 means that it is still in use. Only |
| * a count of 1 means that it is free but |
| * needs to be unmapped |
| */ |
| if (pkmap_count[i] != 1) |
| continue; |
| pkmap_count[i] = 0; |
| |
| /* sanity check */ |
| BUG_ON(pte_none(pkmap_page_table[i])); |
| |
| /* |
| * Don't need an atomic fetch-and-clear op here; |
| * no-one has the page mapped, and cannot get at |
| * its virtual address (and hence PTE) without first |
| * getting the kmap_lock (which is held here). |
| * So no dangers, even with speculative execution. |
| */ |
| page = pte_page(pkmap_page_table[i]); |
| pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]); |
| |
| set_page_address(page, NULL); |
| need_flush = 1; |
| } |
| if (need_flush) |
| flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); |
| } |
| |
| void __kmap_flush_unused(void) |
| { |
| lock_kmap(); |
| flush_all_zero_pkmaps(); |
| unlock_kmap(); |
| } |
| |
| static inline unsigned long map_new_virtual(struct page *page) |
| { |
| unsigned long vaddr; |
| int count; |
| unsigned int last_pkmap_nr; |
| unsigned int color = get_pkmap_color(page); |
| |
| start: |
| count = get_pkmap_entries_count(color); |
| /* Find an empty entry */ |
| for (;;) { |
| last_pkmap_nr = get_next_pkmap_nr(color); |
| if (no_more_pkmaps(last_pkmap_nr, color)) { |
| flush_all_zero_pkmaps(); |
| count = get_pkmap_entries_count(color); |
| } |
| if (!pkmap_count[last_pkmap_nr]) |
| break; /* Found a usable entry */ |
| if (--count) |
| continue; |
| |
| /* |
| * Sleep for somebody else to unmap their entries |
| */ |
| { |
| DECLARE_WAITQUEUE(wait, current); |
| wait_queue_head_t *pkmap_map_wait = |
| get_pkmap_wait_queue_head(color); |
| |
| __set_current_state(TASK_UNINTERRUPTIBLE); |
| add_wait_queue(pkmap_map_wait, &wait); |
| unlock_kmap(); |
| schedule(); |
| remove_wait_queue(pkmap_map_wait, &wait); |
| lock_kmap(); |
| |
| /* Somebody else might have mapped it while we slept */ |
| if (page_address(page)) |
| return (unsigned long)page_address(page); |
| |
| /* Re-start */ |
| goto start; |
| } |
| } |
| vaddr = PKMAP_ADDR(last_pkmap_nr); |
| set_pte_at(&init_mm, vaddr, |
| &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot)); |
| |
| pkmap_count[last_pkmap_nr] = 1; |
| set_page_address(page, (void *)vaddr); |
| |
| return vaddr; |
| } |
| |
| /** |
| * kmap_high - map a highmem page into memory |
| * @page: &struct page to map |
| * |
| * Returns the page's virtual memory address. |
| * |
| * We cannot call this from interrupts, as it may block. |
| */ |
| void *kmap_high(struct page *page) |
| { |
| unsigned long vaddr; |
| |
| /* |
| * For highmem pages, we can't trust "virtual" until |
| * after we have the lock. |
| */ |
| lock_kmap(); |
| vaddr = (unsigned long)page_address(page); |
| if (!vaddr) |
| vaddr = map_new_virtual(page); |
| pkmap_count[PKMAP_NR(vaddr)]++; |
| BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2); |
| unlock_kmap(); |
| return (void *) vaddr; |
| } |
| EXPORT_SYMBOL(kmap_high); |
| |
| #ifdef ARCH_NEEDS_KMAP_HIGH_GET |
| /** |
| * kmap_high_get - pin a highmem page into memory |
| * @page: &struct page to pin |
| * |
| * Returns the page's current virtual memory address, or NULL if no mapping |
| * exists. If and only if a non null address is returned then a |
| * matching call to kunmap_high() is necessary. |
| * |
| * This can be called from any context. |
| */ |
| void *kmap_high_get(struct page *page) |
| { |
| unsigned long vaddr, flags; |
| |
| lock_kmap_any(flags); |
| vaddr = (unsigned long)page_address(page); |
| if (vaddr) { |
| BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1); |
| pkmap_count[PKMAP_NR(vaddr)]++; |
| } |
| unlock_kmap_any(flags); |
| return (void *) vaddr; |
| } |
| #endif |
| |
| /** |
| * kunmap_high - unmap a highmem page into memory |
| * @page: &struct page to unmap |
| * |
| * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called |
| * only from user context. |
| */ |
| void kunmap_high(struct page *page) |
| { |
| unsigned long vaddr; |
| unsigned long nr; |
| unsigned long flags; |
| int need_wakeup; |
| unsigned int color = get_pkmap_color(page); |
| wait_queue_head_t *pkmap_map_wait; |
| |
| lock_kmap_any(flags); |
| vaddr = (unsigned long)page_address(page); |
| BUG_ON(!vaddr); |
| nr = PKMAP_NR(vaddr); |
| |
| /* |
| * A count must never go down to zero |
| * without a TLB flush! |
| */ |
| need_wakeup = 0; |
| switch (--pkmap_count[nr]) { |
| case 0: |
| BUG(); |
| case 1: |
| /* |
| * Avoid an unnecessary wake_up() function call. |
| * The common case is pkmap_count[] == 1, but |
| * no waiters. |
| * The tasks queued in the wait-queue are guarded |
| * by both the lock in the wait-queue-head and by |
| * the kmap_lock. As the kmap_lock is held here, |
| * no need for the wait-queue-head's lock. Simply |
| * test if the queue is empty. |
| */ |
| pkmap_map_wait = get_pkmap_wait_queue_head(color); |
| need_wakeup = waitqueue_active(pkmap_map_wait); |
| } |
| unlock_kmap_any(flags); |
| |
| /* do wake-up, if needed, race-free outside of the spin lock */ |
| if (need_wakeup) |
| wake_up(pkmap_map_wait); |
| } |
| EXPORT_SYMBOL(kunmap_high); |
| |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| void zero_user_segments(struct page *page, unsigned start1, unsigned end1, |
| unsigned start2, unsigned end2) |
| { |
| unsigned int i; |
| |
| BUG_ON(end1 > page_size(page) || end2 > page_size(page)); |
| |
| if (start1 >= end1) |
| start1 = end1 = 0; |
| if (start2 >= end2) |
| start2 = end2 = 0; |
| |
| for (i = 0; i < compound_nr(page); i++) { |
| void *kaddr = NULL; |
| |
| if (start1 >= PAGE_SIZE) { |
| start1 -= PAGE_SIZE; |
| end1 -= PAGE_SIZE; |
| } else { |
| unsigned this_end = min_t(unsigned, end1, PAGE_SIZE); |
| |
| if (end1 > start1) { |
| kaddr = kmap_local_page(page + i); |
| memset(kaddr + start1, 0, this_end - start1); |
| } |
| end1 -= this_end; |
| start1 = 0; |
| } |
| |
| if (start2 >= PAGE_SIZE) { |
| start2 -= PAGE_SIZE; |
| end2 -= PAGE_SIZE; |
| } else { |
| unsigned this_end = min_t(unsigned, end2, PAGE_SIZE); |
| |
| if (end2 > start2) { |
| if (!kaddr) |
| kaddr = kmap_local_page(page + i); |
| memset(kaddr + start2, 0, this_end - start2); |
| } |
| end2 -= this_end; |
| start2 = 0; |
| } |
| |
| if (kaddr) { |
| kunmap_local(kaddr); |
| flush_dcache_page(page + i); |
| } |
| |
| if (!end1 && !end2) |
| break; |
| } |
| |
| BUG_ON((start1 | start2 | end1 | end2) != 0); |
| } |
| EXPORT_SYMBOL(zero_user_segments); |
| #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
| #endif /* CONFIG_HIGHMEM */ |
| |
| #ifdef CONFIG_KMAP_LOCAL |
| |
| #include <asm/kmap_size.h> |
| |
| /* |
| * With DEBUG_KMAP_LOCAL the stack depth is doubled and every second |
| * slot is unused which acts as a guard page |
| */ |
| #ifdef CONFIG_DEBUG_KMAP_LOCAL |
| # define KM_INCR 2 |
| #else |
| # define KM_INCR 1 |
| #endif |
| |
| static inline int kmap_local_idx_push(void) |
| { |
| WARN_ON_ONCE(in_hardirq() && !irqs_disabled()); |
| current->kmap_ctrl.idx += KM_INCR; |
| BUG_ON(current->kmap_ctrl.idx >= KM_MAX_IDX); |
| return current->kmap_ctrl.idx - 1; |
| } |
| |
| static inline int kmap_local_idx(void) |
| { |
| return current->kmap_ctrl.idx - 1; |
| } |
| |
| static inline void kmap_local_idx_pop(void) |
| { |
| current->kmap_ctrl.idx -= KM_INCR; |
| BUG_ON(current->kmap_ctrl.idx < 0); |
| } |
| |
| #ifndef arch_kmap_local_post_map |
| # define arch_kmap_local_post_map(vaddr, pteval) do { } while (0) |
| #endif |
| |
| #ifndef arch_kmap_local_pre_unmap |
| # define arch_kmap_local_pre_unmap(vaddr) do { } while (0) |
| #endif |
| |
| #ifndef arch_kmap_local_post_unmap |
| # define arch_kmap_local_post_unmap(vaddr) do { } while (0) |
| #endif |
| |
| #ifndef arch_kmap_local_map_idx |
| #define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx) |
| #endif |
| |
| #ifndef arch_kmap_local_unmap_idx |
| #define arch_kmap_local_unmap_idx(idx, vaddr) kmap_local_calc_idx(idx) |
| #endif |
| |
| #ifndef arch_kmap_local_high_get |
| static inline void *arch_kmap_local_high_get(struct page *page) |
| { |
| return NULL; |
| } |
| #endif |
| |
| #ifndef arch_kmap_local_set_pte |
| #define arch_kmap_local_set_pte(mm, vaddr, ptep, ptev) \ |
| set_pte_at(mm, vaddr, ptep, ptev) |
| #endif |
| |
| /* Unmap a local mapping which was obtained by kmap_high_get() */ |
| static inline bool kmap_high_unmap_local(unsigned long vaddr) |
| { |
| #ifdef ARCH_NEEDS_KMAP_HIGH_GET |
| if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) { |
| kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)])); |
| return true; |
| } |
| #endif |
| return false; |
| } |
| |
| static inline int kmap_local_calc_idx(int idx) |
| { |
| return idx + KM_MAX_IDX * smp_processor_id(); |
| } |
| |
| static pte_t *__kmap_pte; |
| |
| static pte_t *kmap_get_pte(unsigned long vaddr, int idx) |
| { |
| if (IS_ENABLED(CONFIG_KMAP_LOCAL_NON_LINEAR_PTE_ARRAY)) |
| /* |
| * Set by the arch if __kmap_pte[-idx] does not produce |
| * the correct entry. |
| */ |
| return virt_to_kpte(vaddr); |
| if (!__kmap_pte) |
| __kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN)); |
| return &__kmap_pte[-idx]; |
| } |
| |
| void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot) |
| { |
| pte_t pteval, *kmap_pte; |
| unsigned long vaddr; |
| int idx; |
| |
| /* |
| * Disable migration so resulting virtual address is stable |
| * across preemption. |
| */ |
| migrate_disable(); |
| preempt_disable(); |
| idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn); |
| vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| kmap_pte = kmap_get_pte(vaddr, idx); |
| BUG_ON(!pte_none(*kmap_pte)); |
| pteval = pfn_pte(pfn, prot); |
| arch_kmap_local_set_pte(&init_mm, vaddr, kmap_pte, pteval); |
| arch_kmap_local_post_map(vaddr, pteval); |
| current->kmap_ctrl.pteval[kmap_local_idx()] = pteval; |
| preempt_enable(); |
| |
| return (void *)vaddr; |
| } |
| EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot); |
| |
| void *__kmap_local_page_prot(struct page *page, pgprot_t prot) |
| { |
| void *kmap; |
| |
| /* |
| * To broaden the usage of the actual kmap_local() machinery always map |
| * pages when debugging is enabled and the architecture has no problems |
| * with alias mappings. |
| */ |
| if (!IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) && !PageHighMem(page)) |
| return page_address(page); |
| |
| /* Try kmap_high_get() if architecture has it enabled */ |
| kmap = arch_kmap_local_high_get(page); |
| if (kmap) |
| return kmap; |
| |
| return __kmap_local_pfn_prot(page_to_pfn(page), prot); |
| } |
| EXPORT_SYMBOL(__kmap_local_page_prot); |
| |
| void kunmap_local_indexed(void *vaddr) |
| { |
| unsigned long addr = (unsigned long) vaddr & PAGE_MASK; |
| pte_t *kmap_pte; |
| int idx; |
| |
| if (addr < __fix_to_virt(FIX_KMAP_END) || |
| addr > __fix_to_virt(FIX_KMAP_BEGIN)) { |
| if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP)) { |
| /* This _should_ never happen! See above. */ |
| WARN_ON_ONCE(1); |
| return; |
| } |
| /* |
| * Handle mappings which were obtained by kmap_high_get() |
| * first as the virtual address of such mappings is below |
| * PAGE_OFFSET. Warn for all other addresses which are in |
| * the user space part of the virtual address space. |
| */ |
| if (!kmap_high_unmap_local(addr)) |
| WARN_ON_ONCE(addr < PAGE_OFFSET); |
| return; |
| } |
| |
| preempt_disable(); |
| idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr); |
| WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); |
| |
| kmap_pte = kmap_get_pte(addr, idx); |
| arch_kmap_local_pre_unmap(addr); |
| pte_clear(&init_mm, addr, kmap_pte); |
| arch_kmap_local_post_unmap(addr); |
| current->kmap_ctrl.pteval[kmap_local_idx()] = __pte(0); |
| kmap_local_idx_pop(); |
| preempt_enable(); |
| migrate_enable(); |
| } |
| EXPORT_SYMBOL(kunmap_local_indexed); |
| |
| /* |
| * Invoked before switch_to(). This is safe even when during or after |
| * clearing the maps an interrupt which needs a kmap_local happens because |
| * the task::kmap_ctrl.idx is not modified by the unmapping code so a |
| * nested kmap_local will use the next unused index and restore the index |
| * on unmap. The already cleared kmaps of the outgoing task are irrelevant |
| * because the interrupt context does not know about them. The same applies |
| * when scheduling back in for an interrupt which happens before the |
| * restore is complete. |
| */ |
| void __kmap_local_sched_out(void) |
| { |
| struct task_struct *tsk = current; |
| pte_t *kmap_pte; |
| int i; |
| |
| /* Clear kmaps */ |
| for (i = 0; i < tsk->kmap_ctrl.idx; i++) { |
| pte_t pteval = tsk->kmap_ctrl.pteval[i]; |
| unsigned long addr; |
| int idx; |
| |
| /* With debug all even slots are unmapped and act as guard */ |
| if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { |
| WARN_ON_ONCE(!pte_none(pteval)); |
| continue; |
| } |
| if (WARN_ON_ONCE(pte_none(pteval))) |
| continue; |
| |
| /* |
| * This is a horrible hack for XTENSA to calculate the |
| * coloured PTE index. Uses the PFN encoded into the pteval |
| * and the map index calculation because the actual mapped |
| * virtual address is not stored in task::kmap_ctrl. |
| * For any sane architecture this is optimized out. |
| */ |
| idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); |
| |
| addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| kmap_pte = kmap_get_pte(addr, idx); |
| arch_kmap_local_pre_unmap(addr); |
| pte_clear(&init_mm, addr, kmap_pte); |
| arch_kmap_local_post_unmap(addr); |
| } |
| } |
| |
| void __kmap_local_sched_in(void) |
| { |
| struct task_struct *tsk = current; |
| pte_t *kmap_pte; |
| int i; |
| |
| /* Restore kmaps */ |
| for (i = 0; i < tsk->kmap_ctrl.idx; i++) { |
| pte_t pteval = tsk->kmap_ctrl.pteval[i]; |
| unsigned long addr; |
| int idx; |
| |
| /* With debug all even slots are unmapped and act as guard */ |
| if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { |
| WARN_ON_ONCE(!pte_none(pteval)); |
| continue; |
| } |
| if (WARN_ON_ONCE(pte_none(pteval))) |
| continue; |
| |
| /* See comment in __kmap_local_sched_out() */ |
| idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); |
| addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| kmap_pte = kmap_get_pte(addr, idx); |
| set_pte_at(&init_mm, addr, kmap_pte, pteval); |
| arch_kmap_local_post_map(addr, pteval); |
| } |
| } |
| |
| void kmap_local_fork(struct task_struct *tsk) |
| { |
| if (WARN_ON_ONCE(tsk->kmap_ctrl.idx)) |
| memset(&tsk->kmap_ctrl, 0, sizeof(tsk->kmap_ctrl)); |
| } |
| |
| #endif |
| |
| #if defined(HASHED_PAGE_VIRTUAL) |
| |
| #define PA_HASH_ORDER 7 |
| |
| /* |
| * Describes one page->virtual association |
| */ |
| struct page_address_map { |
| struct page *page; |
| void *virtual; |
| struct list_head list; |
| }; |
| |
| static struct page_address_map page_address_maps[LAST_PKMAP]; |
| |
| /* |
| * Hash table bucket |
| */ |
| static struct page_address_slot { |
| struct list_head lh; /* List of page_address_maps */ |
| spinlock_t lock; /* Protect this bucket's list */ |
| } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; |
| |
| static struct page_address_slot *page_slot(const struct page *page) |
| { |
| return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; |
| } |
| |
| /** |
| * page_address - get the mapped virtual address of a page |
| * @page: &struct page to get the virtual address of |
| * |
| * Returns the page's virtual address. |
| */ |
| void *page_address(const struct page *page) |
| { |
| unsigned long flags; |
| void *ret; |
| struct page_address_slot *pas; |
| |
| if (!PageHighMem(page)) |
| return lowmem_page_address(page); |
| |
| pas = page_slot(page); |
| ret = NULL; |
| spin_lock_irqsave(&pas->lock, flags); |
| if (!list_empty(&pas->lh)) { |
| struct page_address_map *pam; |
| |
| list_for_each_entry(pam, &pas->lh, list) { |
| if (pam->page == page) { |
| ret = pam->virtual; |
| goto done; |
| } |
| } |
| } |
| done: |
| spin_unlock_irqrestore(&pas->lock, flags); |
| return ret; |
| } |
| EXPORT_SYMBOL(page_address); |
| |
| /** |
| * set_page_address - set a page's virtual address |
| * @page: &struct page to set |
| * @virtual: virtual address to use |
| */ |
| void set_page_address(struct page *page, void *virtual) |
| { |
| unsigned long flags; |
| struct page_address_slot *pas; |
| struct page_address_map *pam; |
| |
| BUG_ON(!PageHighMem(page)); |
| |
| pas = page_slot(page); |
| if (virtual) { /* Add */ |
| pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)]; |
| pam->page = page; |
| pam->virtual = virtual; |
| |
| spin_lock_irqsave(&pas->lock, flags); |
| list_add_tail(&pam->list, &pas->lh); |
| spin_unlock_irqrestore(&pas->lock, flags); |
| } else { /* Remove */ |
| spin_lock_irqsave(&pas->lock, flags); |
| list_for_each_entry(pam, &pas->lh, list) { |
| if (pam->page == page) { |
| list_del(&pam->list); |
| spin_unlock_irqrestore(&pas->lock, flags); |
| goto done; |
| } |
| } |
| spin_unlock_irqrestore(&pas->lock, flags); |
| } |
| done: |
| return; |
| } |
| |
| void __init page_address_init(void) |
| { |
| int i; |
| |
| for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { |
| INIT_LIST_HEAD(&page_address_htable[i].lh); |
| spin_lock_init(&page_address_htable[i].lock); |
| } |
| } |
| |
| #endif /* defined(HASHED_PAGE_VIRTUAL) */ |