diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 2165 |
1 files changed, 2165 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c new file mode 100644 index 00000000000..fb6e5deb873 --- /dev/null +++ b/mm/memory.c @@ -0,0 +1,2165 @@ +/* + * linux/mm/memory.c + * + * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds + */ + +/* + * demand-loading started 01.12.91 - seems it is high on the list of + * things wanted, and it should be easy to implement. - Linus + */ + +/* + * Ok, demand-loading was easy, shared pages a little bit tricker. Shared + * pages started 02.12.91, seems to work. - Linus. + * + * Tested sharing by executing about 30 /bin/sh: under the old kernel it + * would have taken more than the 6M I have free, but it worked well as + * far as I could see. + * + * Also corrected some "invalidate()"s - I wasn't doing enough of them. + */ + +/* + * Real VM (paging to/from disk) started 18.12.91. Much more work and + * thought has to go into this. Oh, well.. + * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. + * Found it. Everything seems to work now. + * 20.12.91 - Ok, making the swap-device changeable like the root. + */ + +/* + * 05.04.94 - Multi-page memory management added for v1.1. + * Idea by Alex Bligh (alex@cconcepts.co.uk) + * + * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG + * (Gerhard.Wichert@pdb.siemens.de) + * + * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) + */ + +#include <linux/kernel_stat.h> +#include <linux/mm.h> +#include <linux/hugetlb.h> +#include <linux/mman.h> +#include <linux/swap.h> +#include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/rmap.h> +#include <linux/module.h> +#include <linux/init.h> + +#include <asm/pgalloc.h> +#include <asm/uaccess.h> +#include <asm/tlb.h> +#include <asm/tlbflush.h> +#include <asm/pgtable.h> + +#include <linux/swapops.h> +#include <linux/elf.h> + +#ifndef CONFIG_DISCONTIGMEM +/* use the per-pgdat data instead for discontigmem - mbligh */ +unsigned long max_mapnr; +struct page *mem_map; + +EXPORT_SYMBOL(max_mapnr); +EXPORT_SYMBOL(mem_map); +#endif + +unsigned long num_physpages; +/* + * A number of key systems in x86 including ioremap() rely on the assumption + * that high_memory defines the upper bound on direct map memory, then end + * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and + * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL + * and ZONE_HIGHMEM. + */ +void * high_memory; +unsigned long vmalloc_earlyreserve; + +EXPORT_SYMBOL(num_physpages); +EXPORT_SYMBOL(high_memory); +EXPORT_SYMBOL(vmalloc_earlyreserve); + +/* + * If a p?d_bad entry is found while walking page tables, report + * the error, before resetting entry to p?d_none. Usually (but + * very seldom) called out from the p?d_none_or_clear_bad macros. + */ + +void pgd_clear_bad(pgd_t *pgd) +{ + pgd_ERROR(*pgd); + pgd_clear(pgd); +} + +void pud_clear_bad(pud_t *pud) +{ + pud_ERROR(*pud); + pud_clear(pud); +} + +void pmd_clear_bad(pmd_t *pmd) +{ + pmd_ERROR(*pmd); + pmd_clear(pmd); +} + +/* + * Note: this doesn't free the actual pages themselves. That + * has been handled earlier when unmapping all the memory regions. + */ +static inline void clear_pte_range(struct mmu_gather *tlb, pmd_t *pmd, + unsigned long addr, unsigned long end) +{ + if (!((addr | end) & ~PMD_MASK)) { + /* Only free fully aligned ranges */ + struct page *page = pmd_page(*pmd); + pmd_clear(pmd); + dec_page_state(nr_page_table_pages); + tlb->mm->nr_ptes--; + pte_free_tlb(tlb, page); + } +} + +static inline void clear_pmd_range(struct mmu_gather *tlb, pud_t *pud, + unsigned long addr, unsigned long end) +{ + pmd_t *pmd; + unsigned long next; + pmd_t *empty_pmd = NULL; + + pmd = pmd_offset(pud, addr); + + /* Only free fully aligned ranges */ + if (!((addr | end) & ~PUD_MASK)) + empty_pmd = pmd; + do { + next = pmd_addr_end(addr, end); + if (pmd_none_or_clear_bad(pmd)) + continue; + clear_pte_range(tlb, pmd, addr, next); + } while (pmd++, addr = next, addr != end); + + if (empty_pmd) { + pud_clear(pud); + pmd_free_tlb(tlb, empty_pmd); + } +} + +static inline void clear_pud_range(struct mmu_gather *tlb, pgd_t *pgd, + unsigned long addr, unsigned long end) +{ + pud_t *pud; + unsigned long next; + pud_t *empty_pud = NULL; + + pud = pud_offset(pgd, addr); + + /* Only free fully aligned ranges */ + if (!((addr | end) & ~PGDIR_MASK)) + empty_pud = pud; + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(pud)) + continue; + clear_pmd_range(tlb, pud, addr, next); + } while (pud++, addr = next, addr != end); + + if (empty_pud) { + pgd_clear(pgd); + pud_free_tlb(tlb, empty_pud); + } +} + +/* + * This function clears user-level page tables of a process. + * Unlike other pagetable walks, some memory layouts might give end 0. + * Must be called with pagetable lock held. + */ +void clear_page_range(struct mmu_gather *tlb, + unsigned long addr, unsigned long end) +{ + pgd_t *pgd; + unsigned long next; + + pgd = pgd_offset(tlb->mm, addr); + do { + next = pgd_addr_end(addr, end); + if (pgd_none_or_clear_bad(pgd)) + continue; + clear_pud_range(tlb, pgd, addr, next); + } while (pgd++, addr = next, addr != end); +} + +pte_t fastcall * pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long address) +{ + if (!pmd_present(*pmd)) { + struct page *new; + + spin_unlock(&mm->page_table_lock); + new = pte_alloc_one(mm, address); + spin_lock(&mm->page_table_lock); + if (!new) + return NULL; + /* + * Because we dropped the lock, we should re-check the + * entry, as somebody else could have populated it.. + */ + if (pmd_present(*pmd)) { + pte_free(new); + goto out; + } + mm->nr_ptes++; + inc_page_state(nr_page_table_pages); + pmd_populate(mm, pmd, new); + } +out: + return pte_offset_map(pmd, address); +} + +pte_t fastcall * pte_alloc_kernel(struct mm_struct *mm, pmd_t *pmd, unsigned long address) +{ + if (!pmd_present(*pmd)) { + pte_t *new; + + spin_unlock(&mm->page_table_lock); + new = pte_alloc_one_kernel(mm, address); + spin_lock(&mm->page_table_lock); + if (!new) + return NULL; + + /* + * Because we dropped the lock, we should re-check the + * entry, as somebody else could have populated it.. + */ + if (pmd_present(*pmd)) { + pte_free_kernel(new); + goto out; + } + pmd_populate_kernel(mm, pmd, new); + } +out: + return pte_offset_kernel(pmd, address); +} + +/* + * copy one vm_area from one task to the other. Assumes the page tables + * already present in the new task to be cleared in the whole range + * covered by this vma. + * + * dst->page_table_lock is held on entry and exit, + * but may be dropped within p[mg]d_alloc() and pte_alloc_map(). + */ + +static inline void +copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, + pte_t *dst_pte, pte_t *src_pte, unsigned long vm_flags, + unsigned long addr) +{ + pte_t pte = *src_pte; + struct page *page; + unsigned long pfn; + + /* pte contains position in swap or file, so copy. */ + if (unlikely(!pte_present(pte))) { + if (!pte_file(pte)) { + swap_duplicate(pte_to_swp_entry(pte)); + /* make sure dst_mm is on swapoff's mmlist. */ + if (unlikely(list_empty(&dst_mm->mmlist))) { + spin_lock(&mmlist_lock); + list_add(&dst_mm->mmlist, &src_mm->mmlist); + spin_unlock(&mmlist_lock); + } + } + set_pte_at(dst_mm, addr, dst_pte, pte); + return; + } + + pfn = pte_pfn(pte); + /* the pte points outside of valid memory, the + * mapping is assumed to be good, meaningful + * and not mapped via rmap - duplicate the + * mapping as is. + */ + page = NULL; + if (pfn_valid(pfn)) + page = pfn_to_page(pfn); + + if (!page || PageReserved(page)) { + set_pte_at(dst_mm, addr, dst_pte, pte); + return; + } + + /* + * If it's a COW mapping, write protect it both + * in the parent and the child + */ + if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) { + ptep_set_wrprotect(src_mm, addr, src_pte); + pte = *src_pte; + } + + /* + * If it's a shared mapping, mark it clean in + * the child + */ + if (vm_flags & VM_SHARED) + pte = pte_mkclean(pte); + pte = pte_mkold(pte); + get_page(page); + inc_mm_counter(dst_mm, rss); + if (PageAnon(page)) + inc_mm_counter(dst_mm, anon_rss); + set_pte_at(dst_mm, addr, dst_pte, pte); + page_dup_rmap(page); +} + +static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, + pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, + unsigned long addr, unsigned long end) +{ + pte_t *src_pte, *dst_pte; + unsigned long vm_flags = vma->vm_flags; + int progress; + +again: + dst_pte = pte_alloc_map(dst_mm, dst_pmd, addr); + if (!dst_pte) + return -ENOMEM; + src_pte = pte_offset_map_nested(src_pmd, addr); + + progress = 0; + spin_lock(&src_mm->page_table_lock); + do { + /* + * We are holding two locks at this point - either of them + * could generate latencies in another task on another CPU. + */ + if (progress >= 32 && (need_resched() || + need_lockbreak(&src_mm->page_table_lock) || + need_lockbreak(&dst_mm->page_table_lock))) + break; + if (pte_none(*src_pte)) { + progress++; + continue; + } + copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vm_flags, addr); + progress += 8; + } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); + spin_unlock(&src_mm->page_table_lock); + + pte_unmap_nested(src_pte - 1); + pte_unmap(dst_pte - 1); + cond_resched_lock(&dst_mm->page_table_lock); + if (addr != end) + goto again; + return 0; +} + +static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, + pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, + unsigned long addr, unsigned long end) +{ + pmd_t *src_pmd, *dst_pmd; + unsigned long next; + + dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); + if (!dst_pmd) + return -ENOMEM; + src_pmd = pmd_offset(src_pud, addr); + do { + next = pmd_addr_end(addr, end); + if (pmd_none_or_clear_bad(src_pmd)) + continue; + if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, + vma, addr, next)) + return -ENOMEM; + } while (dst_pmd++, src_pmd++, addr = next, addr != end); + return 0; +} + +static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, + pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, + unsigned long addr, unsigned long end) +{ + pud_t *src_pud, *dst_pud; + unsigned long next; + + dst_pud = pud_alloc(dst_mm, dst_pgd, addr); + if (!dst_pud) + return -ENOMEM; + src_pud = pud_offset(src_pgd, addr); + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(src_pud)) + continue; + if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, + vma, addr, next)) + return -ENOMEM; + } while (dst_pud++, src_pud++, addr = next, addr != end); + return 0; +} + +int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, + struct vm_area_struct *vma) +{ + pgd_t *src_pgd, *dst_pgd; + unsigned long next; + unsigned long addr = vma->vm_start; + unsigned long end = vma->vm_end; + + if (is_vm_hugetlb_page(vma)) + return copy_hugetlb_page_range(dst_mm, src_mm, vma); + + dst_pgd = pgd_offset(dst_mm, addr); + src_pgd = pgd_offset(src_mm, addr); + do { + next = pgd_addr_end(addr, end); + if (pgd_none_or_clear_bad(src_pgd)) + continue; + if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, + vma, addr, next)) + return -ENOMEM; + } while (dst_pgd++, src_pgd++, addr = next, addr != end); + return 0; +} + +static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd, + unsigned long addr, unsigned long end, + struct zap_details *details) +{ + pte_t *pte; + + pte = pte_offset_map(pmd, addr); + do { + pte_t ptent = *pte; + if (pte_none(ptent)) + continue; + if (pte_present(ptent)) { + struct page *page = NULL; + unsigned long pfn = pte_pfn(ptent); + if (pfn_valid(pfn)) { + page = pfn_to_page(pfn); + if (PageReserved(page)) + page = NULL; + } + if (unlikely(details) && page) { + /* + * unmap_shared_mapping_pages() wants to + * invalidate cache without truncating: + * unmap shared but keep private pages. + */ + if (details->check_mapping && + details->check_mapping != page->mapping) + continue; + /* + * Each page->index must be checked when + * invalidating or truncating nonlinear. + */ + if (details->nonlinear_vma && + (page->index < details->first_index || + page->index > details->last_index)) + continue; + } + ptent = ptep_get_and_clear(tlb->mm, addr, pte); + tlb_remove_tlb_entry(tlb, pte, addr); + if (unlikely(!page)) + continue; + if (unlikely(details) && details->nonlinear_vma + && linear_page_index(details->nonlinear_vma, + addr) != page->index) + set_pte_at(tlb->mm, addr, pte, + pgoff_to_pte(page->index)); + if (pte_dirty(ptent)) + set_page_dirty(page); + if (PageAnon(page)) + dec_mm_counter(tlb->mm, anon_rss); + else if (pte_young(ptent)) + mark_page_accessed(page); + tlb->freed++; + page_remove_rmap(page); + tlb_remove_page(tlb, page); + continue; + } + /* + * If details->check_mapping, we leave swap entries; + * if details->nonlinear_vma, we leave file entries. + */ + if (unlikely(details)) + continue; + if (!pte_file(ptent)) + free_swap_and_cache(pte_to_swp_entry(ptent)); + pte_clear(tlb->mm, addr, pte); + } while (pte++, addr += PAGE_SIZE, addr != end); + pte_unmap(pte - 1); +} + +static inline void zap_pmd_range(struct mmu_gather *tlb, pud_t *pud, + unsigned long addr, unsigned long end, + struct zap_details *details) +{ + pmd_t *pmd; + unsigned long next; + + pmd = pmd_offset(pud, addr); + do { + next = pmd_addr_end(addr, end); + if (pmd_none_or_clear_bad(pmd)) + continue; + zap_pte_range(tlb, pmd, addr, next, details); + } while (pmd++, addr = next, addr != end); +} + +static inline void zap_pud_range(struct mmu_gather *tlb, pgd_t *pgd, + unsigned long addr, unsigned long end, + struct zap_details *details) +{ + pud_t *pud; + unsigned long next; + + pud = pud_offset(pgd, addr); + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(pud)) + continue; + zap_pmd_range(tlb, pud, addr, next, details); + } while (pud++, addr = next, addr != end); +} + +static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma, + unsigned long addr, unsigned long end, + struct zap_details *details) +{ + pgd_t *pgd; + unsigned long next; + + if (details && !details->check_mapping && !details->nonlinear_vma) + details = NULL; + + BUG_ON(addr >= end); + tlb_start_vma(tlb, vma); + pgd = pgd_offset(vma->vm_mm, addr); + do { + next = pgd_addr_end(addr, end); + if (pgd_none_or_clear_bad(pgd)) + continue; + zap_pud_range(tlb, pgd, addr, next, details); + } while (pgd++, addr = next, addr != end); + tlb_end_vma(tlb, vma); +} + +#ifdef CONFIG_PREEMPT +# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) +#else +/* No preempt: go for improved straight-line efficiency */ +# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) +#endif + +/** + * unmap_vmas - unmap a range of memory covered by a list of vma's + * @tlbp: address of the caller's struct mmu_gather + * @mm: the controlling mm_struct + * @vma: the starting vma + * @start_addr: virtual address at which to start unmapping + * @end_addr: virtual address at which to end unmapping + * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here + * @details: details of nonlinear truncation or shared cache invalidation + * + * Returns the number of vma's which were covered by the unmapping. + * + * Unmap all pages in the vma list. Called under page_table_lock. + * + * We aim to not hold page_table_lock for too long (for scheduling latency + * reasons). So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to + * return the ending mmu_gather to the caller. + * + * Only addresses between `start' and `end' will be unmapped. + * + * The VMA list must be sorted in ascending virtual address order. + * + * unmap_vmas() assumes that the caller will flush the whole unmapped address + * range after unmap_vmas() returns. So the only responsibility here is to + * ensure that any thus-far unmapped pages are flushed before unmap_vmas() + * drops the lock and schedules. + */ +int unmap_vmas(struct mmu_gather **tlbp, struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long start_addr, + unsigned long end_addr, unsigned long *nr_accounted, + struct zap_details *details) +{ + unsigned long zap_bytes = ZAP_BLOCK_SIZE; + unsigned long tlb_start = 0; /* For tlb_finish_mmu */ + int tlb_start_valid = 0; + int ret = 0; + spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; + int fullmm = tlb_is_full_mm(*tlbp); + + for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { + unsigned long start; + unsigned long end; + + start = max(vma->vm_start, start_addr); + if (start >= vma->vm_end) + continue; + end = min(vma->vm_end, end_addr); + if (end <= vma->vm_start) + continue; + + if (vma->vm_flags & VM_ACCOUNT) + *nr_accounted += (end - start) >> PAGE_SHIFT; + + ret++; + while (start != end) { + unsigned long block; + + if (!tlb_start_valid) { + tlb_start = start; + tlb_start_valid = 1; + } + + if (is_vm_hugetlb_page(vma)) { + block = end - start; + unmap_hugepage_range(vma, start, end); + } else { + block = min(zap_bytes, end - start); + unmap_page_range(*tlbp, vma, start, + start + block, details); + } + + start += block; + zap_bytes -= block; + if ((long)zap_bytes > 0) + continue; + + tlb_finish_mmu(*tlbp, tlb_start, start); + + if (need_resched() || + need_lockbreak(&mm->page_table_lock) || + (i_mmap_lock && need_lockbreak(i_mmap_lock))) { + if (i_mmap_lock) { + /* must reset count of rss freed */ + *tlbp = tlb_gather_mmu(mm, fullmm); + details->break_addr = start; + goto out; + } + spin_unlock(&mm->page_table_lock); + cond_resched(); + spin_lock(&mm->page_table_lock); + } + + *tlbp = tlb_gather_mmu(mm, fullmm); + tlb_start_valid = 0; + zap_bytes = ZAP_BLOCK_SIZE; + } + } +out: + return ret; +} + +/** + * zap_page_range - remove user pages in a given range + * @vma: vm_area_struct holding the applicable pages + * @address: starting address of pages to zap + * @size: number of bytes to zap + * @details: details of nonlinear truncation or shared cache invalidation + */ +void zap_page_range(struct vm_area_struct *vma, unsigned long address, + unsigned long size, struct zap_details *details) +{ + struct mm_struct *mm = vma->vm_mm; + struct mmu_gather *tlb; + unsigned long end = address + size; + unsigned long nr_accounted = 0; + + if (is_vm_hugetlb_page(vma)) { + zap_hugepage_range(vma, address, size); + return; + } + + lru_add_drain(); + spin_lock(&mm->page_table_lock); + tlb = tlb_gather_mmu(mm, 0); + unmap_vmas(&tlb, mm, vma, address, end, &nr_accounted, details); + tlb_finish_mmu(tlb, address, end); + spin_unlock(&mm->page_table_lock); +} + +/* + * Do a quick page-table lookup for a single page. + * mm->page_table_lock must be held. + */ +static struct page * +__follow_page(struct mm_struct *mm, unsigned long address, int read, int write) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *ptep, pte; + unsigned long pfn; + struct page *page; + + page = follow_huge_addr(mm, address, write); + if (! IS_ERR(page)) + return page; + + pgd = pgd_offset(mm, address); + if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) + goto out; + + pud = pud_offset(pgd, address); + if (pud_none(*pud) || unlikely(pud_bad(*pud))) + goto out; + + pmd = pmd_offset(pud, address); + if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) + goto out; + if (pmd_huge(*pmd)) + return follow_huge_pmd(mm, address, pmd, write); + + ptep = pte_offset_map(pmd, address); + if (!ptep) + goto out; + + pte = *ptep; + pte_unmap(ptep); + if (pte_present(pte)) { + if (write && !pte_write(pte)) + goto out; + if (read && !pte_read(pte)) + goto out; + pfn = pte_pfn(pte); + if (pfn_valid(pfn)) { + page = pfn_to_page(pfn); + if (write && !pte_dirty(pte) && !PageDirty(page)) + set_page_dirty(page); + mark_page_accessed(page); + return page; + } + } + +out: + return NULL; +} + +struct page * +follow_page(struct mm_struct *mm, unsigned long address, int write) +{ + return __follow_page(mm, address, /*read*/0, write); +} + +int +check_user_page_readable(struct mm_struct *mm, unsigned long address) +{ + return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL; +} + +EXPORT_SYMBOL(check_user_page_readable); + +/* + * Given a physical address, is there a useful struct page pointing to + * it? This may become more complex in the future if we start dealing + * with IO-aperture pages for direct-IO. + */ + +static inline struct page *get_page_map(struct page *page) +{ + if (!pfn_valid(page_to_pfn(page))) + return NULL; + return page; +} + + +static inline int +untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma, + unsigned long address) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + + /* Check if the vma is for an anonymous mapping. */ + if (vma->vm_ops && vma->vm_ops->nopage) + return 0; + + /* Check if page directory entry exists. */ + pgd = pgd_offset(mm, address); + if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) + return 1; + + pud = pud_offset(pgd, address); + if (pud_none(*pud) || unlikely(pud_bad(*pud))) + return 1; + + /* Check if page middle directory entry exists. */ + pmd = pmd_offset(pud, address); + if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) + return 1; + + /* There is a pte slot for 'address' in 'mm'. */ + return 0; +} + + +int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, int len, int write, int force, + struct page **pages, struct vm_area_struct **vmas) +{ + int i; + unsigned int flags; + + /* + * Require read or write permissions. + * If 'force' is set, we only require the "MAY" flags. + */ + flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); + flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); + i = 0; + + do { + struct vm_area_struct * vma; + + vma = find_extend_vma(mm, start); + if (!vma && in_gate_area(tsk, start)) { + unsigned long pg = start & PAGE_MASK; + struct vm_area_struct *gate_vma = get_gate_vma(tsk); + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + if (write) /* user gate pages are read-only */ + return i ? : -EFAULT; + if (pg > TASK_SIZE) + pgd = pgd_offset_k(pg); + else + pgd = pgd_offset_gate(mm, pg); + BUG_ON(pgd_none(*pgd)); + pud = pud_offset(pgd, pg); + BUG_ON(pud_none(*pud)); + pmd = pmd_offset(pud, pg); + BUG_ON(pmd_none(*pmd)); + pte = pte_offset_map(pmd, pg); + BUG_ON(pte_none(*pte)); + if (pages) { + pages[i] = pte_page(*pte); + get_page(pages[i]); + } + pte_unmap(pte); + if (vmas) + vmas[i] = gate_vma; + i++; + start += PAGE_SIZE; + len--; + continue; + } + + if (!vma || (vma->vm_flags & VM_IO) + || !(flags & vma->vm_flags)) + return i ? : -EFAULT; + + if (is_vm_hugetlb_page(vma)) { + i = follow_hugetlb_page(mm, vma, pages, vmas, + &start, &len, i); + continue; + } + spin_lock(&mm->page_table_lock); + do { + struct page *map; + int lookup_write = write; + + cond_resched_lock(&mm->page_table_lock); + while (!(map = follow_page(mm, start, lookup_write))) { + /* + * Shortcut for anonymous pages. We don't want + * to force the creation of pages tables for + * insanly big anonymously mapped areas that + * nobody touched so far. This is important + * for doing a core dump for these mappings. + */ + if (!lookup_write && + untouched_anonymous_page(mm,vma,start)) { + map = ZERO_PAGE(start); + break; + } + spin_unlock(&mm->page_table_lock); + switch (handle_mm_fault(mm,vma,start,write)) { + case VM_FAULT_MINOR: + tsk->min_flt++; + break; + case VM_FAULT_MAJOR: + tsk->maj_flt++; + break; + case VM_FAULT_SIGBUS: + return i ? i : -EFAULT; + case VM_FAULT_OOM: + return i ? i : -ENOMEM; + default: + BUG(); + } + /* + * Now that we have performed a write fault + * and surely no longer have a shared page we + * shouldn't write, we shouldn't ignore an + * unwritable page in the page table if + * we are forcing write access. + */ + lookup_write = write && !force; + spin_lock(&mm->page_table_lock); + } + if (pages) { + pages[i] = get_page_map(map); + if (!pages[i]) { + spin_unlock(&mm->page_table_lock); + while (i--) + page_cache_release(pages[i]); + i = -EFAULT; + goto out; + } + flush_dcache_page(pages[i]); + if (!PageReserved(pages[i])) + page_cache_get(pages[i]); + } + if (vmas) + vmas[i] = vma; + i++; + start += PAGE_SIZE; + len--; + } while(len && start < vma->vm_end); + spin_unlock(&mm->page_table_lock); + } while(len); +out: + return i; +} + +EXPORT_SYMBOL(get_user_pages); + +static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd, + unsigned long addr, unsigned long end, pgprot_t prot) +{ + pte_t *pte; + + pte = pte_alloc_map(mm, pmd, addr); + if (!pte) + return -ENOMEM; + do { + pte_t zero_pte = pte_wrprotect(mk_pte(ZERO_PAGE(addr), prot)); + BUG_ON(!pte_none(*pte)); + set_pte_at(mm, addr, pte, zero_pte); + } while (pte++, addr += PAGE_SIZE, addr != end); + pte_unmap(pte - 1); + return 0; +} + +static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud, + unsigned long addr, unsigned long end, pgprot_t prot) +{ + pmd_t *pmd; + unsigned long next; + + pmd = pmd_alloc(mm, pud, addr); + if (!pmd) + return -ENOMEM; + do { + next = pmd_addr_end(addr, end); + if (zeromap_pte_range(mm, pmd, addr, next, prot)) + return -ENOMEM; + } while (pmd++, addr = next, addr != end); + return 0; +} + +static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd, + unsigned long addr, unsigned long end, pgprot_t prot) +{ + pud_t *pud; + unsigned long next; + + pud = pud_alloc(mm, pgd, addr); + if (!pud) + return -ENOMEM; + do { + next = pud_addr_end(addr, end); + if (zeromap_pmd_range(mm, pud, addr, next, prot)) + return -ENOMEM; + } while (pud++, addr = next, addr != end); + return 0; +} + +int zeromap_page_range(struct vm_area_struct *vma, + unsigned long addr, unsigned long size, pgprot_t prot) +{ + pgd_t *pgd; + unsigned long next; + unsigned long end = addr + size; + struct mm_struct *mm = vma->vm_mm; + int err; + + BUG_ON(addr >= end); + pgd = pgd_offset(mm, addr); + flush_cache_range(vma, addr, end); + spin_lock(&mm->page_table_lock); + do { + next = pgd_addr_end(addr, end); + err = zeromap_pud_range(mm, pgd, addr, next, prot); + if (err) + break; + } while (pgd++, addr = next, addr != end); + spin_unlock(&mm->page_table_lock); + return err; +} + +/* + * maps a range of physical memory into the requested pages. the old + * mappings are removed. any references to nonexistent pages results + * in null mappings (currently treated as "copy-on-access") + */ +static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, + unsigned long addr, unsigned long end, + unsigned long pfn, pgprot_t prot) +{ + pte_t *pte; + + pte = pte_alloc_map(mm, pmd, addr); + if (!pte) + return -ENOMEM; + do { + BUG_ON(!pte_none(*pte)); + if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn))) + set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); + pfn++; + } while (pte++, addr += PAGE_SIZE, addr != end); + pte_unmap(pte - 1); + return 0; +} + +static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, + unsigned long addr, unsigned long end, + unsigned long pfn, pgprot_t prot) +{ + pmd_t *pmd; + unsigned long next; + + pfn -= addr >> PAGE_SHIFT; + pmd = pmd_alloc(mm, pud, addr); + if (!pmd) + return -ENOMEM; + do { + next = pmd_addr_end(addr, end); + if (remap_pte_range(mm, pmd, addr, next, + pfn + (addr >> PAGE_SHIFT), prot)) + return -ENOMEM; + } while (pmd++, addr = next, addr != end); + return 0; +} + +static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, + unsigned long addr, unsigned long end, + unsigned long pfn, pgprot_t prot) +{ + pud_t *pud; + unsigned long next; + + pfn -= addr >> PAGE_SHIFT; + pud = pud_alloc(mm, pgd, addr); + if (!pud) + return -ENOMEM; + do { + next = pud_addr_end(addr, end); + if (remap_pmd_range(mm, pud, addr, next, + pfn + (addr >> PAGE_SHIFT), prot)) + return -ENOMEM; + } while (pud++, addr = next, addr != end); + return 0; +} + +/* Note: this is only safe if the mm semaphore is held when called. */ +int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, + unsigned long pfn, unsigned long size, pgprot_t prot) +{ + pgd_t *pgd; + unsigned long next; + unsigned long end = addr + size; + struct mm_struct *mm = vma->vm_mm; + int err; + + /* + * Physically remapped pages are special. Tell the + * rest of the world about it: + * VM_IO tells people not to look at these pages + * (accesses can have side effects). + * VM_RESERVED tells swapout not to try to touch + * this region. + */ + vma->vm_flags |= VM_IO | VM_RESERVED; + + BUG_ON(addr >= end); + pfn -= addr >> PAGE_SHIFT; + pgd = pgd_offset(mm, addr); + flush_cache_range(vma, addr, end); + spin_lock(&mm->page_table_lock); + do { + next = pgd_addr_end(addr, end); + err = remap_pud_range(mm, pgd, addr, next, + pfn + (addr >> PAGE_SHIFT), prot); + if (err) + break; + } while (pgd++, addr = next, addr != end); + spin_unlock(&mm->page_table_lock); + return err; +} +EXPORT_SYMBOL(remap_pfn_range); + +/* + * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when + * servicing faults for write access. In the normal case, do always want + * pte_mkwrite. But get_user_pages can cause write faults for mappings + * that do not have writing enabled, when used by access_process_vm. + */ +static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) +{ + if (likely(vma->vm_flags & VM_WRITE)) + pte = pte_mkwrite(pte); + return pte; +} + +/* + * We hold the mm semaphore for reading and vma->vm_mm->page_table_lock + */ +static inline void break_cow(struct vm_area_struct * vma, struct page * new_page, unsigned long address, + pte_t *page_table) +{ + pte_t entry; + + entry = maybe_mkwrite(pte_mkdirty(mk_pte(new_page, vma->vm_page_prot)), + vma); + ptep_establish(vma, address, page_table, entry); + update_mmu_cache(vma, address, entry); + lazy_mmu_prot_update(entry); +} + +/* + * This routine handles present pages, when users try to write + * to a shared page. It is done by copying the page to a new address + * and decrementing the shared-page counter for the old page. + * + * Goto-purists beware: the only reason for goto's here is that it results + * in better assembly code.. The "default" path will see no jumps at all. + * + * Note that this routine assumes that the protection checks have been + * done by the caller (the low-level page fault routine in most cases). + * Thus we can safely just mark it writable once we've done any necessary + * COW. + * + * We also mark the page dirty at this point even though the page will + * change only once the write actually happens. This avoids a few races, + * and potentially makes it more efficient. + * + * We hold the mm semaphore and the page_table_lock on entry and exit + * with the page_table_lock released. + */ +static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma, + unsigned long address, pte_t *page_table, pmd_t *pmd, pte_t pte) +{ + struct page *old_page, *new_page; + unsigned long pfn = pte_pfn(pte); + pte_t entry; + + if (unlikely(!pfn_valid(pfn))) { + /* + * This should really halt the system so it can be debugged or + * at least the kernel stops what it's doing before it corrupts + * data, but for the moment just pretend this is OOM. + */ + pte_unmap(page_table); + printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n", + address); + spin_unlock(&mm->page_table_lock); + return VM_FAULT_OOM; + } + old_page = pfn_to_page(pfn); + + if (!TestSetPageLocked(old_page)) { + int reuse = can_share_swap_page(old_page); + unlock_page(old_page); + if (reuse) { + flush_cache_page(vma, address, pfn); + entry = maybe_mkwrite(pte_mkyoung(pte_mkdirty(pte)), + vma); + ptep_set_access_flags(vma, address, page_table, entry, 1); + update_mmu_cache(vma, address, entry); + lazy_mmu_prot_update(entry); + pte_unmap(page_table); + spin_unlock(&mm->page_table_lock); + return VM_FAULT_MINOR; + } + } + pte_unmap(page_table); + + /* + * Ok, we need to copy. Oh, well.. + */ + if (!PageReserved(old_page)) + page_cache_get(old_page); + spin_unlock(&mm->page_table_lock); + + if (unlikely(anon_vma_prepare(vma))) + goto no_new_page; + if (old_page == ZERO_PAGE(address)) { + new_page = alloc_zeroed_user_highpage(vma, address); + if (!new_page) + goto no_new_page; + } else { + new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); + if (!new_page) + goto no_new_page; + copy_user_highpage(new_page, old_page, address); + } + /* + * Re-check the pte - we dropped the lock + */ + spin_lock(&mm->page_table_lock); + page_table = pte_offset_map(pmd, address); + if (likely(pte_same(*page_table, pte))) { + if (PageAnon(old_page)) + dec_mm_counter(mm, anon_rss); + if (PageReserved(old_page)) + inc_mm_counter(mm, rss); + else + page_remove_rmap(old_page); + flush_cache_page(vma, address, pfn); + break_cow(vma, new_page, address, page_table); + lru_cache_add_active(new_page); + page_add_anon_rmap(new_page, vma, address); + + /* Free the old page.. */ + new_page = old_page; + } + pte_unmap(page_table); + page_cache_release(new_page); + page_cache_release(old_page); + spin_unlock(&mm->page_table_lock); + return VM_FAULT_MINOR; + +no_new_page: + page_cache_release(old_page); + return VM_FAULT_OOM; +} + +/* + * Helper functions for unmap_mapping_range(). + * + * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ + * + * We have to restart searching the prio_tree whenever we drop the lock, + * since the iterator is only valid while the lock is held, and anyway + * a later vma might be split and reinserted earlier while lock dropped. + * + * The list of nonlinear vmas could be handled more efficiently, using + * a placeholder, but handle it in the same way until a need is shown. + * It is important to search the prio_tree before nonlinear list: a vma + * may become nonlinear and be shifted from prio_tree to nonlinear list + * while the lock is dropped; but never shifted from list to prio_tree. + * + * In order to make forward progress despite restarting the search, + * vm_truncate_count is used to mark a vma as now dealt with, so we can + * quickly skip it next time around. Since the prio_tree search only + * shows us those vmas affected by unmapping the range in question, we + * can't efficiently keep all vmas in step with mapping->truncate_count: + * so instead reset them all whenever it wraps back to 0 (then go to 1). + * mapping->truncate_count and vma->vm_truncate_count are protected by + * i_mmap_lock. + * + * In order to make forward progress despite repeatedly restarting some + * large vma, note the break_addr set by unmap_vmas when it breaks out: + * and restart from that address when we reach that vma again. It might + * have been split or merged, shrunk or extended, but never shifted: so + * restart_addr remains valid so long as it remains in the vma's range. + * unmap_mapping_range forces truncate_count to leap over page-aligned + * values so we can save vma's restart_addr in its truncate_count field. + */ +#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) + +static void reset_vma_truncate_counts(struct address_space *mapping) +{ + struct vm_area_struct *vma; + struct prio_tree_iter iter; + + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) + vma->vm_truncate_count = 0; + list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) + vma->vm_truncate_count = 0; +} + +static int unmap_mapping_range_vma(struct vm_area_struct *vma, + unsigned long start_addr, unsigned long end_addr, + struct zap_details *details) +{ + unsigned long restart_addr; + int need_break; + +again: + restart_addr = vma->vm_truncate_count; + if (is_restart_addr(restart_addr) && start_addr < restart_addr) { + start_addr = restart_addr; + if (start_addr >= end_addr) { + /* Top of vma has been split off since last time */ + vma->vm_truncate_count = details->truncate_count; + return 0; + } + } + + details->break_addr = end_addr; + zap_page_range(vma, start_addr, end_addr - start_addr, details); + + /* + * We cannot rely on the break test in unmap_vmas: + * on the one hand, we don't want to restart our loop + * just because that broke out for the page_table_lock; + * on the other hand, it does no test when vma is small. + */ + need_break = need_resched() || + need_lockbreak(details->i_mmap_lock); + + if (details->break_addr >= end_addr) { + /* We have now completed this vma: mark it so */ + vma->vm_truncate_count = details->truncate_count; + if (!need_break) + return 0; + } else { + /* Note restart_addr in vma's truncate_count field */ + vma->vm_truncate_count = details->break_addr; + if (!need_break) + goto again; + } + + spin_unlock(details->i_mmap_lock); + cond_resched(); + spin_lock(details->i_mmap_lock); + return -EINTR; +} + +static inline void unmap_mapping_range_tree(struct prio_tree_root *root, + struct zap_details *details) +{ + struct vm_area_struct *vma; + struct prio_tree_iter iter; + pgoff_t vba, vea, zba, zea; + +restart: + vma_prio_tree_foreach(vma, &iter, root, + details->first_index, details->last_index) { + /* Skip quickly over those we have already dealt with */ + if (vma->vm_truncate_count == details->truncate_count) + continue; + + vba = vma->vm_pgoff; + vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; + /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ + zba = details->first_index; + if (zba < vba) + zba = vba; + zea = details->last_index; + if (zea > vea) + zea = vea; + + if (unmap_mapping_range_vma(vma, + ((zba - vba) << PAGE_SHIFT) + vma->vm_start, + ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, + details) < 0) + goto restart; + } +} + +static inline void unmap_mapping_range_list(struct list_head *head, + struct zap_details *details) +{ + struct vm_area_struct *vma; + + /* + * In nonlinear VMAs there is no correspondence between virtual address + * offset and file offset. So we must perform an exhaustive search + * across *all* the pages in each nonlinear VMA, not just the pages + * whose virtual address lies outside the file truncation point. + */ +restart: + list_for_each_entry(vma, head, shared.vm_set.list) { + /* Skip quickly over those we have already dealt with */ + if (vma->vm_truncate_count == details->truncate_count) + continue; + details->nonlinear_vma = vma; + if (unmap_mapping_range_vma(vma, vma->vm_start, + vma->vm_end, details) < 0) + goto restart; + } +} + +/** + * unmap_mapping_range - unmap the portion of all mmaps + * in the specified address_space corresponding to the specified + * page range in the underlying file. + * @address_space: the address space containing mmaps to be unmapped. + * @holebegin: byte in first page to unmap, relative to the start of + * the underlying file. This will be rounded down to a PAGE_SIZE + * boundary. Note that this is different from vmtruncate(), which + * must keep the partial page. In contrast, we must get rid of + * partial pages. + * @holelen: size of prospective hole in bytes. This will be rounded + * up to a PAGE_SIZE boundary. A holelen of zero truncates to the + * end of the file. + * @even_cows: 1 when truncating a file, unmap even private COWed pages; + * but 0 when invalidating pagecache, don't throw away private data. + */ +void unmap_mapping_range(struct address_space *mapping, + loff_t const holebegin, loff_t const holelen, int even_cows) +{ + struct zap_details details; + pgoff_t hba = holebegin >> PAGE_SHIFT; + pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; + + /* Check for overflow. */ + if (sizeof(holelen) > sizeof(hlen)) { + long long holeend = + (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (holeend & ~(long long)ULONG_MAX) + hlen = ULONG_MAX - hba + 1; + } + + details.check_mapping = even_cows? NULL: mapping; + details.nonlinear_vma = NULL; + details.first_index = hba; + details.last_index = hba + hlen - 1; + if (details.last_index < details.first_index) + details.last_index = ULONG_MAX; + details.i_mmap_lock = &mapping->i_mmap_lock; + + spin_lock(&mapping->i_mmap_lock); + + /* serialize i_size write against truncate_count write */ + smp_wmb(); + /* Protect against page faults, and endless unmapping loops */ + mapping->truncate_count++; + /* + * For archs where spin_lock has inclusive semantics like ia64 + * this smp_mb() will prevent to read pagetable contents + * before the truncate_count increment is visible to + * other cpus. + */ + smp_mb(); + if (unlikely(is_restart_addr(mapping->truncate_count))) { + if (mapping->truncate_count == 0) + reset_vma_truncate_counts(mapping); + mapping->truncate_count++; + } + details.truncate_count = mapping->truncate_count; + + if (unlikely(!prio_tree_empty(&mapping->i_mmap))) + unmap_mapping_range_tree(&mapping->i_mmap, &details); + if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) + unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); + spin_unlock(&mapping->i_mmap_lock); +} +EXPORT_SYMBOL(unmap_mapping_range); + +/* + * Handle all mappings that got truncated by a "truncate()" + * system call. + * + * NOTE! We have to be ready to update the memory sharing + * between the file and the memory map for a potential last + * incomplete page. Ugly, but necessary. + */ +int vmtruncate(struct inode * inode, loff_t offset) +{ + struct address_space *mapping = inode->i_mapping; + unsigned long limit; + + if (inode->i_size < offset) + goto do_expand; + /* + * truncation of in-use swapfiles is disallowed - it would cause + * subsequent swapout to scribble on the now-freed blocks. + */ + if (IS_SWAPFILE(inode)) + goto out_busy; + i_size_write(inode, offset); + unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); + truncate_inode_pages(mapping, offset); + goto out_truncate; + +do_expand: + limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; + if (limit != RLIM_INFINITY && offset > limit) + goto out_sig; + if (offset > inode->i_sb->s_maxbytes) + goto out_big; + i_size_write(inode, offset); + +out_truncate: + if (inode->i_op && inode->i_op->truncate) + inode->i_op->truncate(inode); + return 0; +out_sig: + send_sig(SIGXFSZ, current, 0); +out_big: + return -EFBIG; +out_busy: + return -ETXTBSY; +} + +EXPORT_SYMBOL(vmtruncate); + +/* + * Primitive swap readahead code. We simply read an aligned block of + * (1 << page_cluster) entries in the swap area. This method is chosen + * because it doesn't cost us any seek time. We also make sure to queue + * the 'original' request together with the readahead ones... + * + * This has been extended to use the NUMA policies from the mm triggering + * the readahead. + * + * Caller must hold down_read on the vma->vm_mm if vma is not NULL. + */ +void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) +{ +#ifdef CONFIG_NUMA + struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; +#endif + int i, num; + struct page *new_page; + unsigned long offset; + + /* + * Get the number of handles we should do readahead io to. + */ + num = valid_swaphandles(entry, &offset); + for (i = 0; i < num; offset++, i++) { + /* Ok, do the async read-ahead now */ + new_page = read_swap_cache_async(swp_entry(swp_type(entry), + offset), vma, addr); + if (!new_page) + break; + page_cache_release(new_page); +#ifdef CONFIG_NUMA + /* + * Find the next applicable VMA for the NUMA policy. + */ + addr += PAGE_SIZE; + if (addr == 0) + vma = NULL; + if (vma) { + if (addr >= vma->vm_end) { + vma = next_vma; + next_vma = vma ? vma->vm_next : NULL; + } + if (vma && addr < vma->vm_start) + vma = NULL; + } else { + if (next_vma && addr >= next_vma->vm_start) { + vma = next_vma; + next_vma = vma->vm_next; + } + } +#endif + } + lru_add_drain(); /* Push any new pages onto the LRU now */ +} + +/* + * We hold the mm semaphore and the page_table_lock on entry and + * should release the pagetable lock on exit.. + */ +static int do_swap_page(struct mm_struct * mm, + struct vm_area_struct * vma, unsigned long address, + pte_t *page_table, pmd_t *pmd, pte_t orig_pte, int write_access) +{ + struct page *page; + swp_entry_t entry = pte_to_swp_entry(orig_pte); + pte_t pte; + int ret = VM_FAULT_MINOR; + + pte_unmap(page_table); + spin_unlock(&mm->page_table_lock); + page = lookup_swap_cache(entry); + if (!page) { + swapin_readahead(entry, address, vma); + page = read_swap_cache_async(entry, vma, address); + if (!page) { + /* + * Back out if somebody else faulted in this pte while + * we released the page table lock. + */ + spin_lock(&mm->page_table_lock); + page_table = pte_offset_map(pmd, address); + if (likely(pte_same(*page_table, orig_pte))) + ret = VM_FAULT_OOM; + else + ret = VM_FAULT_MINOR; + pte_unmap(page_table); + spin_unlock(&mm->page_table_lock); + goto out; + } + + /* Had to read the page from swap area: Major fault */ + ret = VM_FAULT_MAJOR; + inc_page_state(pgmajfault); + grab_swap_token(); + } + + mark_page_accessed(page); + lock_page(page); + + /* + * Back out if somebody else faulted in this pte while we + * released the page table lock. + */ + spin_lock(&mm->page_table_lock); + page_table = pte_offset_map(pmd, address); + if (unlikely(!pte_same(*page_table, orig_pte))) { + pte_unmap(page_table); + spin_unlock(&mm->page_table_lock); + unlock_page(page); + page_cache_release(page); + ret = VM_FAULT_MINOR; + goto out; + } + + /* The page isn't present yet, go ahead with the fault. */ + + swap_free(entry); + if (vm_swap_full()) + remove_exclusive_swap_page(page); + + inc_mm_counter(mm, rss); + pte = mk_pte(page, vma->vm_page_prot); + if (write_access && can_share_swap_page(page)) { + pte = maybe_mkwrite(pte_mkdirty(pte), vma); + write_access = 0; + } + unlock_page(page); + + flush_icache_page(vma, page); + set_pte_at(mm, address, page_table, pte); + page_add_anon_rmap(page, vma, address); + + if (write_access) { + if (do_wp_page(mm, vma, address, + page_table, pmd, pte) == VM_FAULT_OOM) + ret = VM_FAULT_OOM; + goto out; + } + + /* No need to invalidate - it was non-present before */ + update_mmu_cache(vma, address, pte); + lazy_mmu_prot_update(pte); + pte_unmap(page_table); + spin_unlock(&mm->page_table_lock); +out: + return ret; +} + +/* + * We are called with the MM semaphore and page_table_lock + * spinlock held to protect against concurrent faults in + * multithreaded programs. + */ +static int +do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, + pte_t *page_table, pmd_t *pmd, int write_access, + unsigned long addr) +{ + pte_t entry; + struct page * page = ZERO_PAGE(addr); + + /* Read-only mapping of ZERO_PAGE. */ + entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot)); + + /* ..except if it's a write access */ + if (write_access) { + /* Allocate our own private page. */ + pte_unmap(page_table); + spin_unlock(&mm->page_table_lock); + + if (unlikely(anon_vma_prepare(vma))) + goto no_mem; + page = alloc_zeroed_user_highpage(vma, addr); + if (!page) + goto no_mem; + + spin_lock(&mm->page_table_lock); + page_table = pte_offset_map(pmd, addr); + + if (!pte_none(*page_table)) { + pte_unmap(page_table); + page_cache_release(page); + spin_unlock(&mm->page_table_lock); + goto out; + } + inc_mm_counter(mm, rss); + entry = maybe_mkwrite(pte_mkdirty(mk_pte(page, + vma->vm_page_prot)), + vma); + lru_cache_add_active(page); + SetPageReferenced(page); + page_add_anon_rmap(page, vma, addr); + } + + set_pte_at(mm, addr, page_table, entry); + pte_unmap(page_table); + + /* No need to invalidate - it was non-present before */ + update_mmu_cache(vma, addr, entry); + lazy_mmu_prot_update(entry); + spin_unlock(&mm->page_table_lock); +out: + return VM_FAULT_MINOR; +no_mem: + return VM_FAULT_OOM; +} + +/* + * do_no_page() tries to create a new page mapping. It aggressively + * tries to share with existing pages, but makes a separate copy if + * the "write_access" parameter is true in order to avoid the next + * page fault. + * + * As this is called only for pages that do not currently exist, we + * do not need to flush old virtual caches or the TLB. + * + * This is called with the MM semaphore held and the page table + * spinlock held. Exit with the spinlock released. + */ +static int +do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, int write_access, pte_t *page_table, pmd_t *pmd) +{ + struct page * new_page; + struct address_space *mapping = NULL; + pte_t entry; + unsigned int sequence = 0; + int ret = VM_FAULT_MINOR; + int anon = 0; + + if (!vma->vm_ops || !vma->vm_ops->nopage) + return do_anonymous_page(mm, vma, page_table, + pmd, write_access, address); + pte_unmap(page_table); + spin_unlock(&mm->page_table_lock); + + if (vma->vm_file) { + mapping = vma->vm_file->f_mapping; + sequence = mapping->truncate_count; + smp_rmb(); /* serializes i_size against truncate_count */ + } +retry: + cond_resched(); + new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); + /* + * No smp_rmb is needed here as long as there's a full + * spin_lock/unlock sequence inside the ->nopage callback + * (for the pagecache lookup) that acts as an implicit + * smp_mb() and prevents the i_size read to happen + * after the next truncate_count read. + */ + + /* no page was available -- either SIGBUS or OOM */ + if (new_page == NOPAGE_SIGBUS) + return VM_FAULT_SIGBUS; + if (new_page == NOPAGE_OOM) + return VM_FAULT_OOM; + + /* + * Should we do an early C-O-W break? + */ + if (write_access && !(vma->vm_flags & VM_SHARED)) { + struct page *page; + + if (unlikely(anon_vma_prepare(vma))) + goto oom; + page = alloc_page_vma(GFP_HIGHUSER, vma, address); + if (!page) + goto oom; + copy_user_highpage(page, new_page, address); + page_cache_release(new_page); + new_page = page; + anon = 1; + } + + spin_lock(&mm->page_table_lock); + /* + * For a file-backed vma, someone could have truncated or otherwise + * invalidated this page. If unmap_mapping_range got called, + * retry getting the page. + */ + if (mapping && unlikely(sequence != mapping->truncate_count)) { + sequence = mapping->truncate_count; + spin_unlock(&mm->page_table_lock); + page_cache_release(new_page); + goto retry; + } + page_table = pte_offset_map(pmd, address); + + /* + * This silly early PAGE_DIRTY setting removes a race + * due to the bad i386 page protection. But it's valid + * for other architectures too. + * + * Note that if write_access is true, we either now have + * an exclusive copy of the page, or this is a shared mapping, + * so we can make it writable and dirty to avoid having to + * handle that later. + */ + /* Only go through if we didn't race with anybody else... */ + if (pte_none(*page_table)) { + if (!PageReserved(new_page)) + inc_mm_counter(mm, rss); + + flush_icache_page(vma, new_page); + entry = mk_pte(new_page, vma->vm_page_prot); + if (write_access) + entry = maybe_mkwrite(pte_mkdirty(entry), vma); + set_pte_at(mm, address, page_table, entry); + if (anon) { + lru_cache_add_active(new_page); + page_add_anon_rmap(new_page, vma, address); + } else + page_add_file_rmap(new_page); + pte_unmap(page_table); + } else { + /* One of our sibling threads was faster, back out. */ + pte_unmap(page_table); + page_cache_release(new_page); + spin_unlock(&mm->page_table_lock); + goto out; + } + + /* no need to invalidate: a not-present page shouldn't be cached */ + update_mmu_cache(vma, address, entry); + lazy_mmu_prot_update(entry); + spin_unlock(&mm->page_table_lock); +out: + return ret; +oom: + page_cache_release(new_page); + ret = VM_FAULT_OOM; + goto out; +} + +/* + * Fault of a previously existing named mapping. Repopulate the pte + * from the encoded file_pte if possible. This enables swappable + * nonlinear vmas. + */ +static int do_file_page(struct mm_struct * mm, struct vm_area_struct * vma, + unsigned long address, int write_access, pte_t *pte, pmd_t *pmd) +{ + unsigned long pgoff; + int err; + + BUG_ON(!vma->vm_ops || !vma->vm_ops->nopage); + /* + * Fall back to the linear mapping if the fs does not support + * ->populate: + */ + if (!vma->vm_ops || !vma->vm_ops->populate || + (write_access && !(vma->vm_flags & VM_SHARED))) { + pte_clear(mm, address, pte); + return do_no_page(mm, vma, address, write_access, pte, pmd); + } + + pgoff = pte_to_pgoff(*pte); + + pte_unmap(pte); + spin_unlock(&mm->page_table_lock); + + err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, vma->vm_page_prot, pgoff, 0); + if (err == -ENOMEM) + return VM_FAULT_OOM; + if (err) + return VM_FAULT_SIGBUS; + return VM_FAULT_MAJOR; +} + +/* + * These routines also need to handle stuff like marking pages dirty + * and/or accessed for architectures that don't do it in hardware (most + * RISC architectures). The early dirtying is also good on the i386. + * + * There is also a hook called "update_mmu_cache()" that architectures + * with external mmu caches can use to update those (ie the Sparc or + * PowerPC hashed page tables that act as extended TLBs). + * + * Note the "page_table_lock". It is to protect against kswapd removing + * pages from under us. Note that kswapd only ever _removes_ pages, never + * adds them. As such, once we have noticed that the page is not present, + * we can drop the lock early. + * + * The adding of pages is protected by the MM semaphore (which we hold), + * so we don't need to worry about a page being suddenly been added into + * our VM. + * + * We enter with the pagetable spinlock held, we are supposed to + * release it when done. + */ +static inline int handle_pte_fault(struct mm_struct *mm, + struct vm_area_struct * vma, unsigned long address, + int write_access, pte_t *pte, pmd_t *pmd) +{ + pte_t entry; + + entry = *pte; + if (!pte_present(entry)) { + /* + * If it truly wasn't present, we know that kswapd + * and the PTE updates will not touch it later. So + * drop the lock. + */ + if (pte_none(entry)) + return do_no_page(mm, vma, address, write_access, pte, pmd); + if (pte_file(entry)) + return do_file_page(mm, vma, address, write_access, pte, pmd); + return do_swap_page(mm, vma, address, pte, pmd, entry, write_access); + } + + if (write_access) { + if (!pte_write(entry)) + return do_wp_page(mm, vma, address, pte, pmd, entry); + + entry = pte_mkdirty(entry); + } + entry = pte_mkyoung(entry); + ptep_set_access_flags(vma, address, pte, entry, write_access); + update_mmu_cache(vma, address, entry); + lazy_mmu_prot_update(entry); + pte_unmap(pte); + spin_unlock(&mm->page_table_lock); + return VM_FAULT_MINOR; +} + +/* + * By the time we get here, we already hold the mm semaphore + */ +int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma, + unsigned long address, int write_access) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + __set_current_state(TASK_RUNNING); + + inc_page_state(pgfault); + + if (is_vm_hugetlb_page(vma)) + return VM_FAULT_SIGBUS; /* mapping truncation does this. */ + + /* + * We need the page table lock to synchronize with kswapd + * and the SMP-safe atomic PTE updates. + */ + pgd = pgd_offset(mm, address); + spin_lock(&mm->page_table_lock); + + pud = pud_alloc(mm, pgd, address); + if (!pud) + goto oom; + + pmd = pmd_alloc(mm, pud, address); + if (!pmd) + goto oom; + + pte = pte_alloc_map(mm, pmd, address); + if (!pte) + goto oom; + + return handle_pte_fault(mm, vma, address, write_access, pte, pmd); + + oom: + spin_unlock(&mm->page_table_lock); + return VM_FAULT_OOM; +} + +#ifndef __PAGETABLE_PUD_FOLDED +/* + * Allocate page upper directory. + * + * We've already handled the fast-path in-line, and we own the + * page table lock. + */ +pud_t fastcall *__pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) +{ + pud_t *new; + + spin_unlock(&mm->page_table_lock); + new = pud_alloc_one(mm, address); + spin_lock(&mm->page_table_lock); + if (!new) + return NULL; + + /* + * Because we dropped the lock, we should re-check the + * entry, as somebody else could have populated it.. + */ + if (pgd_present(*pgd)) { + pud_free(new); + goto out; + } + pgd_populate(mm, pgd, new); + out: + return pud_offset(pgd, address); +} +#endif /* __PAGETABLE_PUD_FOLDED */ + +#ifndef __PAGETABLE_PMD_FOLDED +/* + * Allocate page middle directory. + * + * We've already handled the fast-path in-line, and we own the + * page table lock. + */ +pmd_t fastcall *__pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) +{ + pmd_t *new; + + spin_unlock(&mm->page_table_lock); + new = pmd_alloc_one(mm, address); + spin_lock(&mm->page_table_lock); + if (!new) + return NULL; + + /* + * Because we dropped the lock, we should re-check the + * entry, as somebody else could have populated it.. + */ +#ifndef __ARCH_HAS_4LEVEL_HACK + if (pud_present(*pud)) { + pmd_free(new); + goto out; + } + pud_populate(mm, pud, new); +#else + if (pgd_present(*pud)) { + pmd_free(new); + goto out; + } + pgd_populate(mm, pud, new); +#endif /* __ARCH_HAS_4LEVEL_HACK */ + + out: + return pmd_offset(pud, address); +} +#endif /* __PAGETABLE_PMD_FOLDED */ + +int make_pages_present(unsigned long addr, unsigned long end) +{ + int ret, len, write; + struct vm_area_struct * vma; + + vma = find_vma(current->mm, addr); + if (!vma) + return -1; + write = (vma->vm_flags & VM_WRITE) != 0; + if (addr >= end) + BUG(); + if (end > vma->vm_end) + BUG(); + len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE; + ret = get_user_pages(current, current->mm, addr, + len, write, 0, NULL, NULL); + if (ret < 0) + return ret; + return ret == len ? 0 : -1; +} + +/* + * Map a vmalloc()-space virtual address to the physical page. + */ +struct page * vmalloc_to_page(void * vmalloc_addr) +{ + unsigned long addr = (unsigned long) vmalloc_addr; + struct page *page = NULL; + pgd_t *pgd = pgd_offset_k(addr); + pud_t *pud; + pmd_t *pmd; + pte_t *ptep, pte; + + if (!pgd_none(*pgd)) { + pud = pud_offset(pgd, addr); + if (!pud_none(*pud)) { + pmd = pmd_offset(pud, addr); + if (!pmd_none(*pmd)) { + ptep = pte_offset_map(pmd, addr); + pte = *ptep; + if (pte_present(pte)) + page = pte_page(pte); + pte_unmap(ptep); + } + } + } + return page; +} + +EXPORT_SYMBOL(vmalloc_to_page); + +/* + * Map a vmalloc()-space virtual address to the physical page frame number. + */ +unsigned long vmalloc_to_pfn(void * vmalloc_addr) +{ + return page_to_pfn(vmalloc_to_page(vmalloc_addr)); +} + +EXPORT_SYMBOL(vmalloc_to_pfn); + +/* + * update_mem_hiwater + * - update per process rss and vm high water data + */ +void update_mem_hiwater(struct task_struct *tsk) +{ + if (tsk->mm) { + unsigned long rss = get_mm_counter(tsk->mm, rss); + + if (tsk->mm->hiwater_rss < rss) + tsk->mm->hiwater_rss = rss; + if (tsk->mm->hiwater_vm < tsk->mm->total_vm) + tsk->mm->hiwater_vm = tsk->mm->total_vm; + } +} + +#if !defined(__HAVE_ARCH_GATE_AREA) + +#if defined(AT_SYSINFO_EHDR) +struct vm_area_struct gate_vma; + +static int __init gate_vma_init(void) +{ + gate_vma.vm_mm = NULL; + gate_vma.vm_start = FIXADDR_USER_START; + gate_vma.vm_end = FIXADDR_USER_END; + gate_vma.vm_page_prot = PAGE_READONLY; + gate_vma.vm_flags = 0; + return 0; +} +__initcall(gate_vma_init); +#endif + +struct vm_area_struct *get_gate_vma(struct task_struct *tsk) +{ +#ifdef AT_SYSINFO_EHDR + return &gate_vma; +#else + return NULL; +#endif +} + +int in_gate_area_no_task(unsigned long addr) +{ +#ifdef AT_SYSINFO_EHDR + if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) + return 1; +#endif + return 0; +} + +#endif /* __HAVE_ARCH_GATE_AREA */ |