/* * 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_NEED_MULTIPLE_NODES /* 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 void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd) { struct page *page = pmd_page(*pmd); pmd_clear(pmd); pte_free_tlb(tlb, page); dec_page_state(nr_page_table_pages); tlb->mm->nr_ptes--; } static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { pmd_t *pmd; unsigned long next; unsigned long start; start = addr; pmd = pmd_offset(pud, addr); do { next = pmd_addr_end(addr, end); if (pmd_none_or_clear_bad(pmd)) continue; free_pte_range(tlb, pmd); } while (pmd++, addr = next, addr != end); start &= PUD_MASK; if (start < floor) return; if (ceiling) { ceiling &= PUD_MASK; if (!ceiling) return; } if (end - 1 > ceiling - 1) return; pmd = pmd_offset(pud, start); pud_clear(pud); pmd_free_tlb(tlb, pmd); } static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { pud_t *pud; unsigned long next; unsigned long start; start = addr; pud = pud_offset(pgd, addr); do { next = pud_addr_end(addr, end); if (pud_none_or_clear_bad(pud)) continue; free_pmd_range(tlb, pud, addr, next, floor, ceiling); } while (pud++, addr = next, addr != end); start &= PGDIR_MASK; if (start < floor) return; if (ceiling) { ceiling &= PGDIR_MASK; if (!ceiling) return; } if (end - 1 > ceiling - 1) return; pud = pud_offset(pgd, start); pgd_clear(pgd); pud_free_tlb(tlb, pud); } /* * This function frees user-level page tables of a process. * * Must be called with pagetable lock held. */ void free_pgd_range(struct mmu_gather **tlb, unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { pgd_t *pgd; unsigned long next; unsigned long start; /* * The next few lines have given us lots of grief... * * Why are we testing PMD* at this top level? Because often * there will be no work to do at all, and we'd prefer not to * go all the way down to the bottom just to discover that. * * Why all these "- 1"s? Because 0 represents both the bottom * of the address space and the top of it (using -1 for the * top wouldn't help much: the masks would do the wrong thing). * The rule is that addr 0 and floor 0 refer to the bottom of * the address space, but end 0 and ceiling 0 refer to the top * Comparisons need to use "end - 1" and "ceiling - 1" (though * that end 0 case should be mythical). * * Wherever addr is brought up or ceiling brought down, we must * be careful to reject "the opposite 0" before it confuses the * subsequent tests. But what about where end is brought down * by PMD_SIZE below? no, end can't go down to 0 there. * * Whereas we round start (addr) and ceiling down, by different * masks at different levels, in order to test whether a table * now has no other vmas using it, so can be freed, we don't * bother to round floor or end up - the tests don't need that. */ addr &= PMD_MASK; if (addr < floor) { addr += PMD_SIZE; if (!addr) return; } if (ceiling) { ceiling &= PMD_MASK; if (!ceiling) return; } if (end - 1 > ceiling - 1) end -= PMD_SIZE; if (addr > end - 1) return; start = addr; pgd = pgd_offset((*tlb)->mm, addr); do { next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) continue; free_pud_range(*tlb, pgd, addr, next, floor, ceiling); } while (pgd++, addr = next, addr != end); if (!tlb_is_full_mm(*tlb)) flush_tlb_pgtables((*tlb)->mm, start, end); } void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma, unsigned long floor, unsigned long ceiling) { while (vma) { struct vm_area_struct *next = vma->vm_next; unsigned long addr = vma->vm_start; if (is_hugepage_only_range(vma->vm_mm, addr, HPAGE_SIZE)) { hugetlb_free_pgd_range(tlb, addr, vma->vm_end, floor, next? next->vm_start: ceiling); } else { /* * Optimization: gather nearby vmas into one call down */ while (next && next->vm_start <= vma->vm_end + PMD_SIZE && !is_hugepage_only_range(vma->vm_mm, next->vm_start, HPAGE_SIZE)) { vma = next; next = vma->vm_next; } free_pgd_range(tlb, addr, vma->vm_end, floor, next? next->vm_start: ceiling); } vma = next; } } 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 end address of the unmapping (restart addr if interrupted). * * 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. */ unsigned long 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; unsigned long start = start_addr; 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 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; 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); 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 start; /* which is now the end (or restart) address */ } /** * 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 */ unsigned long 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 end; } lru_add_drain(); spin_lock(&mm->page_table_lock); tlb = tlb_gather_mmu(mm, 0); end = unmap_vmas(&tlb, mm, vma, address, end, &nr_accounted, details); tlb_finish_mmu(tlb, address, end); spin_unlock(&mm->page_table_lock); return end; } /* * 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, int accessed) { 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 (accessed) { if (write && !pte_dirty(pte) &&!PageDirty(page)) set_page_dirty(page); mark_page_accessed(page); } return page; } } out: return NULL; } inline struct page * follow_page(struct mm_struct *mm, unsigned long address, int write) { return __follow_page(mm, address, 0, write, 1); } /* * check_user_page_readable() can be called frm niterrupt context by oprofile, * so we need to avoid taking any non-irq-safe locks */ int check_user_page_readable(struct mm_struct *mm, unsigned long address) { return __follow_page(mm, address, 1, 0, 0) != NULL; } EXPORT_SYMBOL(check_user_page_readable); 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); if (pmd_none(*pmd)) return i ? : -EFAULT; pte = pte_offset_map(pmd, pg); if (pte_none(*pte)) { pte_unmap(pte); return i ? : -EFAULT; } 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 { int write_access = write; struct page *page; cond_resched_lock(&mm->page_table_lock); while (!(page = follow_page(mm, start, write_access))) { int ret; /* * Shortcut for anonymous pages. We don't want * to force the creation of pages tables for * insanely big anonymously mapped areas that * nobody touched so far. This is important * for doing a core dump for these mappings. */ if (!write && untouched_anonymous_page(mm,vma,start)) { page = ZERO_PAGE(start); break; } spin_unlock(&mm->page_table_lock); ret = __handle_mm_fault(mm, vma, start, write_access); /* * The VM_FAULT_WRITE bit tells us that do_wp_page has * broken COW when necessary, even if maybe_mkwrite * decided not to set pte_write. We can thus safely do * subsequent page lookups as if they were reads. */ if (ret & VM_FAULT_WRITE) write_access = 0; switch (ret & ~VM_FAULT_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(); } spin_lock(&mm->page_table_lock); } if (pages) { pages[i] = page; flush_dcache_page(page); if (!PageReserved(page)) page_cache_get(page); } if (vmas) vmas[i] = vma; i++; start += PAGE_SIZE; len--; } while (len && start < vma->vm_end); spin_unlock(&mm->page_table_lock); } while (len); 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 + PAGE_ALIGN(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; int ret; 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 (PageAnon(old_page) && !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|VM_FAULT_WRITE; } } 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 */ ret = VM_FAULT_MINOR; 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; ret |= VM_FAULT_WRITE; } pte_unmap(page_table); page_cache_release(new_page); page_cache_release(old_page); spin_unlock(&mm->page_table_lock); return ret; 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 restart_addr from 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; } } restart_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 (restart_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 = restart_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. * @mapping: 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))) { ret = VM_FAULT_MINOR; goto out_nomap; } if (unlikely(!PageUptodate(page))) { ret = VM_FAULT_SIGBUS; goto out_nomap; } /* The page isn't present yet, go ahead with the fault. */ 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; } flush_icache_page(vma, page); set_pte_at(mm, address, page_table, pte); page_add_anon_rmap(page, vma, address); swap_free(entry); if (vm_swap_full()) remove_exclusive_swap_page(page); unlock_page(page); 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; out_nomap: pte_unmap(page_table); spin_unlock(&mm->page_table_lock); unlock_page(page); page_cache_release(page); goto out; } /* * 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 */