| /* |
| * 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/module.h> |
| #include <linux/swap.h> |
| #include <linux/bio.h> |
| #include <linux/pagemap.h> |
| #include <linux/mempool.h> |
| #include <linux/blkdev.h> |
| #include <linux/init.h> |
| #include <linux/hash.h> |
| #include <linux/highmem.h> |
| #include <linux/kgdb.h> |
| #include <asm/tlbflush.h> |
| |
| |
| #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32) |
| DEFINE_PER_CPU(int, __kmap_atomic_idx); |
| #endif |
| |
| /* |
| * 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 |
| |
| unsigned long totalhigh_pages __read_mostly; |
| EXPORT_SYMBOL(totalhigh_pages); |
| |
| |
| EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx); |
| |
| unsigned int nr_free_highpages (void) |
| { |
| pg_data_t *pgdat; |
| unsigned int pages = 0; |
| |
| for_each_online_pgdat(pgdat) { |
| pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM], |
| NR_FREE_PAGES); |
| if (zone_movable_is_highmem()) |
| pages += zone_page_state( |
| &pgdat->node_zones[ZONE_MOVABLE], |
| NR_FREE_PAGES); |
| } |
| |
| return pages; |
| } |
| |
| static int pkmap_count[LAST_PKMAP]; |
| static unsigned int last_pkmap_nr; |
| static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); |
| |
| pte_t * pkmap_page_table; |
| |
| static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); |
| |
| /* |
| * 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 |
| |
| 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, (unsigned long)page_address(page), |
| &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)); |
| } |
| |
| /** |
| * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings |
| */ |
| 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; |
| |
| start: |
| count = LAST_PKMAP; |
| /* Find an empty entry */ |
| for (;;) { |
| last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; |
| if (!last_pkmap_nr) { |
| flush_all_zero_pkmaps(); |
| count = LAST_PKMAP; |
| } |
| 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); |
| |
| __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 - map 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; |
| |
| 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. |
| */ |
| 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); |
| #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; |
| }; |
| |
| /* |
| * page_address_map freelist, allocated from page_address_maps. |
| */ |
| static struct list_head page_address_pool; /* freelist */ |
| static spinlock_t pool_lock; /* protects page_address_pool */ |
| |
| /* |
| * 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 */ |
| BUG_ON(list_empty(&page_address_pool)); |
| |
| spin_lock_irqsave(&pool_lock, flags); |
| pam = list_entry(page_address_pool.next, |
| struct page_address_map, list); |
| list_del(&pam->list); |
| spin_unlock_irqrestore(&pool_lock, flags); |
| |
| 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); |
| spin_lock_irqsave(&pool_lock, flags); |
| list_add_tail(&pam->list, &page_address_pool); |
| spin_unlock_irqrestore(&pool_lock, flags); |
| goto done; |
| } |
| } |
| spin_unlock_irqrestore(&pas->lock, flags); |
| } |
| done: |
| return; |
| } |
| |
| static struct page_address_map page_address_maps[LAST_PKMAP]; |
| |
| void __init page_address_init(void) |
| { |
| int i; |
| |
| INIT_LIST_HEAD(&page_address_pool); |
| for (i = 0; i < ARRAY_SIZE(page_address_maps); i++) |
| list_add(&page_address_maps[i].list, &page_address_pool); |
| 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); |
| } |
| spin_lock_init(&pool_lock); |
| } |
| |
| #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */ |