// 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> #ifdef CONFIG_KMAP_LOCALstatic inline int kmap_local_calc_idx(int idx){ return idx + KM_MAX_IDX * smp_processor_id();} #ifndef arch_kmap_local_map_idx#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx)#endif#endif /* CONFIG_KMAP_LOCAL */ /* * 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(const 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 unsigned long __nr_free_highpages(void){ unsigned long pages = 0; struct zone *zone; for_each_populated_zone(zone) { if (is_highmem(zone)) pages += zone_page_state(zone, NR_FREE_PAGES); } return pages;} unsigned long __totalhigh_pages(void){ unsigned long pages = 0; struct zone *zone; for_each_populated_zone(zone) { if (is_highmem(zone)) pages += zone_managed_pages(zone); } return pages;}EXPORT_SYMBOL(__totalhigh_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 base = (unsigned long) vaddr & PAGE_MASK; struct kmap_ctrl *kctrl = ¤t->kmap_ctrl; unsigned long addr = (unsigned long)vaddr; int i; /* kmap() mappings */ if (WARN_ON_ONCE(addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP))) return pte_page(ptep_get(&pkmap_page_table[PKMAP_NR(addr)])); /* kmap_local_page() mappings */ if (WARN_ON_ONCE(base >= __fix_to_virt(FIX_KMAP_END) && base < __fix_to_virt(FIX_KMAP_BEGIN))) { for (i = 0; i < kctrl->idx; i++) { unsigned long base_addr; int idx; pte_t pteval = kctrl->pteval[i]; idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); base_addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); if (base_addr == base) return pte_page(pteval); } } return virt_to_page(vaddr);}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; pte_t ptent; /* * 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 */ ptent = ptep_get(&pkmap_page_table[i]); BUG_ON(pte_none(ptent)); /* * 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(ptent); 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(const 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(const 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); 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_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)Lines 1–500 of 826. 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// 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> #ifdef CONFIG_KMAP_LOCAL static inline int kmap_local_calc_idx(int idx) { return idx + KM_MAX_IDX * smp_processor_id(); } #ifndef arch_kmap_local_map_idx #define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx) #endif #endif /* CONFIG_KMAP_LOCAL */ /* * 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(const 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 unsigned long __nr_free_highpages(void) { unsigned long pages = 0; struct zone *zone; for_each_populated_zone(zone) { if (is_highmem(zone)) pages += zone_page_state(zone, NR_FREE_PAGES); } return pages; } unsigned long __totalhigh_pages(void) { unsigned long pages = 0; struct zone *zone; for_each_populated_zone(zone) { if (is_highmem(zone)) pages += zone_managed_pages(zone); } return pages; } EXPORT_SYMBOL(__totalhigh_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 base = (unsigned long) vaddr & PAGE_MASK; struct kmap_ctrl *kctrl = ¤t->kmap_ctrl; unsigned long addr = (unsigned long)vaddr; int i; /* kmap() mappings */ if (WARN_ON_ONCE(addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP))) return pte_page(ptep_get(&pkmap_page_table[PKMAP_NR(addr)])); /* kmap_local_page() mappings */ if (WARN_ON_ONCE(base >= __fix_to_virt(FIX_KMAP_END) && base < __fix_to_virt(FIX_KMAP_BEGIN))) { for (i = 0; i < kctrl->idx; i++) { unsigned long base_addr; int idx; pte_t pteval = kctrl->pteval[i]; idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); base_addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); if (base_addr == base) return pte_page(pteval); } } return virt_to_page(vaddr); } 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; pte_t ptent; /* * 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 */ ptent = ptep_get(&pkmap_page_table[i]); BUG_ON(pte_none(ptent)); /* * 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(ptent); 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(const 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(const 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); 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_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)