| /* |
| * 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/ksm.h> |
| #include <linux/rmap.h> |
| #include <linux/module.h> |
| #include <linux/delayacct.h> |
| #include <linux/init.h> |
| #include <linux/writeback.h> |
| #include <linux/memcontrol.h> |
| #include <linux/mmu_notifier.h> |
| #include <linux/kallsyms.h> |
| #include <linux/swapops.h> |
| #include <linux/elf.h> |
| |
| #include <asm/io.h> |
| #include <asm/pgalloc.h> |
| #include <asm/uaccess.h> |
| #include <asm/tlb.h> |
| #include <asm/tlbflush.h> |
| #include <asm/pgtable.h> |
| |
| #include "internal.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; |
| |
| EXPORT_SYMBOL(num_physpages); |
| EXPORT_SYMBOL(high_memory); |
| |
| /* |
| * Randomize the address space (stacks, mmaps, brk, etc.). |
| * |
| * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, |
| * as ancient (libc5 based) binaries can segfault. ) |
| */ |
| int randomize_va_space __read_mostly = |
| #ifdef CONFIG_COMPAT_BRK |
| 1; |
| #else |
| 2; |
| #endif |
| |
| static int __init disable_randmaps(char *s) |
| { |
| randomize_va_space = 0; |
| return 1; |
| } |
| __setup("norandmaps", disable_randmaps); |
| |
| unsigned long zero_pfn __read_mostly; |
| |
| /* |
| * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() |
| */ |
| static int __init init_zero_pfn(void) |
| { |
| zero_pfn = page_to_pfn(ZERO_PAGE(0)); |
| return 0; |
| } |
| core_initcall(init_zero_pfn); |
| |
| /* |
| * 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, |
| unsigned long addr) |
| { |
| pgtable_t token = pmd_pgtable(*pmd); |
| pmd_clear(pmd); |
| pte_free_tlb(tlb, token, addr); |
| 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, addr); |
| } 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, start); |
| } |
| |
| 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, start); |
| } |
| |
| /* |
| * 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); |
| } |
| |
| 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; |
| |
| /* |
| * Hide vma from rmap and vmtruncate before freeing pgtables |
| */ |
| anon_vma_unlink(vma); |
| unlink_file_vma(vma); |
| |
| if (is_vm_hugetlb_page(vma)) { |
| 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_vm_hugetlb_page(next)) { |
| vma = next; |
| next = vma->vm_next; |
| anon_vma_unlink(vma); |
| unlink_file_vma(vma); |
| } |
| free_pgd_range(tlb, addr, vma->vm_end, |
| floor, next? next->vm_start: ceiling); |
| } |
| vma = next; |
| } |
| } |
| |
| int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) |
| { |
| pgtable_t new = pte_alloc_one(mm, address); |
| if (!new) |
| return -ENOMEM; |
| |
| /* |
| * Ensure all pte setup (eg. pte page lock and page clearing) are |
| * visible before the pte is made visible to other CPUs by being |
| * put into page tables. |
| * |
| * The other side of the story is the pointer chasing in the page |
| * table walking code (when walking the page table without locking; |
| * ie. most of the time). Fortunately, these data accesses consist |
| * of a chain of data-dependent loads, meaning most CPUs (alpha |
| * being the notable exception) will already guarantee loads are |
| * seen in-order. See the alpha page table accessors for the |
| * smp_read_barrier_depends() barriers in page table walking code. |
| */ |
| smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ |
| |
| spin_lock(&mm->page_table_lock); |
| if (!pmd_present(*pmd)) { /* Has another populated it ? */ |
| mm->nr_ptes++; |
| pmd_populate(mm, pmd, new); |
| new = NULL; |
| } |
| spin_unlock(&mm->page_table_lock); |
| if (new) |
| pte_free(mm, new); |
| return 0; |
| } |
| |
| int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) |
| { |
| pte_t *new = pte_alloc_one_kernel(&init_mm, address); |
| if (!new) |
| return -ENOMEM; |
| |
| smp_wmb(); /* See comment in __pte_alloc */ |
| |
| spin_lock(&init_mm.page_table_lock); |
| if (!pmd_present(*pmd)) { /* Has another populated it ? */ |
| pmd_populate_kernel(&init_mm, pmd, new); |
| new = NULL; |
| } |
| spin_unlock(&init_mm.page_table_lock); |
| if (new) |
| pte_free_kernel(&init_mm, new); |
| return 0; |
| } |
| |
| static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) |
| { |
| if (file_rss) |
| add_mm_counter(mm, file_rss, file_rss); |
| if (anon_rss) |
| add_mm_counter(mm, anon_rss, anon_rss); |
| } |
| |
| /* |
| * This function is called to print an error when a bad pte |
| * is found. For example, we might have a PFN-mapped pte in |
| * a region that doesn't allow it. |
| * |
| * The calling function must still handle the error. |
| */ |
| static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, |
| pte_t pte, struct page *page) |
| { |
| pgd_t *pgd = pgd_offset(vma->vm_mm, addr); |
| pud_t *pud = pud_offset(pgd, addr); |
| pmd_t *pmd = pmd_offset(pud, addr); |
| struct address_space *mapping; |
| pgoff_t index; |
| static unsigned long resume; |
| static unsigned long nr_shown; |
| static unsigned long nr_unshown; |
| |
| /* |
| * Allow a burst of 60 reports, then keep quiet for that minute; |
| * or allow a steady drip of one report per second. |
| */ |
| if (nr_shown == 60) { |
| if (time_before(jiffies, resume)) { |
| nr_unshown++; |
| return; |
| } |
| if (nr_unshown) { |
| printk(KERN_ALERT |
| "BUG: Bad page map: %lu messages suppressed\n", |
| nr_unshown); |
| nr_unshown = 0; |
| } |
| nr_shown = 0; |
| } |
| if (nr_shown++ == 0) |
| resume = jiffies + 60 * HZ; |
| |
| mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; |
| index = linear_page_index(vma, addr); |
| |
| printk(KERN_ALERT |
| "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", |
| current->comm, |
| (long long)pte_val(pte), (long long)pmd_val(*pmd)); |
| if (page) { |
| printk(KERN_ALERT |
| "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n", |
| page, (void *)page->flags, page_count(page), |
| page_mapcount(page), page->mapping, page->index); |
| } |
| printk(KERN_ALERT |
| "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", |
| (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); |
| /* |
| * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y |
| */ |
| if (vma->vm_ops) |
| print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n", |
| (unsigned long)vma->vm_ops->fault); |
| if (vma->vm_file && vma->vm_file->f_op) |
| print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n", |
| (unsigned long)vma->vm_file->f_op->mmap); |
| dump_stack(); |
| add_taint(TAINT_BAD_PAGE); |
| } |
| |
| static inline int is_cow_mapping(unsigned int flags) |
| { |
| return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; |
| } |
| |
| #ifndef is_zero_pfn |
| static inline int is_zero_pfn(unsigned long pfn) |
| { |
| return pfn == zero_pfn; |
| } |
| #endif |
| |
| #ifndef my_zero_pfn |
| static inline unsigned long my_zero_pfn(unsigned long addr) |
| { |
| return zero_pfn; |
| } |
| #endif |
| |
| /* |
| * vm_normal_page -- This function gets the "struct page" associated with a pte. |
| * |
| * "Special" mappings do not wish to be associated with a "struct page" (either |
| * it doesn't exist, or it exists but they don't want to touch it). In this |
| * case, NULL is returned here. "Normal" mappings do have a struct page. |
| * |
| * There are 2 broad cases. Firstly, an architecture may define a pte_special() |
| * pte bit, in which case this function is trivial. Secondly, an architecture |
| * may not have a spare pte bit, which requires a more complicated scheme, |
| * described below. |
| * |
| * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a |
| * special mapping (even if there are underlying and valid "struct pages"). |
| * COWed pages of a VM_PFNMAP are always normal. |
| * |
| * The way we recognize COWed pages within VM_PFNMAP mappings is through the |
| * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit |
| * set, and the vm_pgoff will point to the first PFN mapped: thus every special |
| * mapping will always honor the rule |
| * |
| * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) |
| * |
| * And for normal mappings this is false. |
| * |
| * This restricts such mappings to be a linear translation from virtual address |
| * to pfn. To get around this restriction, we allow arbitrary mappings so long |
| * as the vma is not a COW mapping; in that case, we know that all ptes are |
| * special (because none can have been COWed). |
| * |
| * |
| * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. |
| * |
| * VM_MIXEDMAP mappings can likewise contain memory with or without "struct |
| * page" backing, however the difference is that _all_ pages with a struct |
| * page (that is, those where pfn_valid is true) are refcounted and considered |
| * normal pages by the VM. The disadvantage is that pages are refcounted |
| * (which can be slower and simply not an option for some PFNMAP users). The |
| * advantage is that we don't have to follow the strict linearity rule of |
| * PFNMAP mappings in order to support COWable mappings. |
| * |
| */ |
| #ifdef __HAVE_ARCH_PTE_SPECIAL |
| # define HAVE_PTE_SPECIAL 1 |
| #else |
| # define HAVE_PTE_SPECIAL 0 |
| #endif |
| struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, |
| pte_t pte) |
| { |
| unsigned long pfn = pte_pfn(pte); |
| |
| if (HAVE_PTE_SPECIAL) { |
| if (likely(!pte_special(pte))) |
| goto check_pfn; |
| if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
| return NULL; |
| if (!is_zero_pfn(pfn)) |
| print_bad_pte(vma, addr, pte, NULL); |
| return NULL; |
| } |
| |
| /* !HAVE_PTE_SPECIAL case follows: */ |
| |
| if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
| if (vma->vm_flags & VM_MIXEDMAP) { |
| if (!pfn_valid(pfn)) |
| return NULL; |
| goto out; |
| } else { |
| unsigned long off; |
| off = (addr - vma->vm_start) >> PAGE_SHIFT; |
| if (pfn == vma->vm_pgoff + off) |
| return NULL; |
| if (!is_cow_mapping(vma->vm_flags)) |
| return NULL; |
| } |
| } |
| |
| if (is_zero_pfn(pfn)) |
| return NULL; |
| check_pfn: |
| if (unlikely(pfn > highest_memmap_pfn)) { |
| print_bad_pte(vma, addr, pte, NULL); |
| return NULL; |
| } |
| |
| /* |
| * NOTE! We still have PageReserved() pages in the page tables. |
| * eg. VDSO mappings can cause them to exist. |
| */ |
| out: |
| return pfn_to_page(pfn); |
| } |
| |
| /* |
| * 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. |
| */ |
| |
| static inline void |
| copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, |
| unsigned long addr, int *rss) |
| { |
| unsigned long vm_flags = vma->vm_flags; |
| pte_t pte = *src_pte; |
| struct page *page; |
| |
| /* pte contains position in swap or file, so copy. */ |
| if (unlikely(!pte_present(pte))) { |
| if (!pte_file(pte)) { |
| swp_entry_t entry = pte_to_swp_entry(pte); |
| |
| swap_duplicate(entry); |
| /* make sure dst_mm is on swapoff's mmlist. */ |
| if (unlikely(list_empty(&dst_mm->mmlist))) { |
| spin_lock(&mmlist_lock); |
| if (list_empty(&dst_mm->mmlist)) |
| list_add(&dst_mm->mmlist, |
| &src_mm->mmlist); |
| spin_unlock(&mmlist_lock); |
| } |
| if (is_write_migration_entry(entry) && |
| is_cow_mapping(vm_flags)) { |
| /* |
| * COW mappings require pages in both parent |
| * and child to be set to read. |
| */ |
| make_migration_entry_read(&entry); |
| pte = swp_entry_to_pte(entry); |
| set_pte_at(src_mm, addr, src_pte, pte); |
| } |
| } |
| goto out_set_pte; |
| } |
| |
| /* |
| * If it's a COW mapping, write protect it both |
| * in the parent and the child |
| */ |
| if (is_cow_mapping(vm_flags)) { |
| ptep_set_wrprotect(src_mm, addr, src_pte); |
| pte = pte_wrprotect(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); |
| |
| page = vm_normal_page(vma, addr, pte); |
| if (page) { |
| get_page(page); |
| page_dup_rmap(page); |
| rss[PageAnon(page)]++; |
| } |
| |
| out_set_pte: |
| set_pte_at(dst_mm, addr, dst_pte, pte); |
| } |
| |
| 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; |
| spinlock_t *src_ptl, *dst_ptl; |
| int progress = 0; |
| int rss[2]; |
| |
| again: |
| rss[1] = rss[0] = 0; |
| dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); |
| if (!dst_pte) |
| return -ENOMEM; |
| src_pte = pte_offset_map_nested(src_pmd, addr); |
| src_ptl = pte_lockptr(src_mm, src_pmd); |
| spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
| arch_enter_lazy_mmu_mode(); |
| |
| do { |
| /* |
| * We are holding two locks at this point - either of them |
| * could generate latencies in another task on another CPU. |
| */ |
| if (progress >= 32) { |
| progress = 0; |
| if (need_resched() || |
| spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) |
| break; |
| } |
| if (pte_none(*src_pte)) { |
| progress++; |
| continue; |
| } |
| copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); |
| progress += 8; |
| } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); |
| |
| arch_leave_lazy_mmu_mode(); |
| spin_unlock(src_ptl); |
| pte_unmap_nested(src_pte - 1); |
| add_mm_rss(dst_mm, rss[0], rss[1]); |
| pte_unmap_unlock(dst_pte - 1, dst_ptl); |
| cond_resched(); |
| 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; |
| int ret; |
| |
| /* |
| * Don't copy ptes where a page fault will fill them correctly. |
| * Fork becomes much lighter when there are big shared or private |
| * readonly mappings. The tradeoff is that copy_page_range is more |
| * efficient than faulting. |
| */ |
| if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { |
| if (!vma->anon_vma) |
| return 0; |
| } |
| |
| if (is_vm_hugetlb_page(vma)) |
| return copy_hugetlb_page_range(dst_mm, src_mm, vma); |
| |
| if (unlikely(is_pfn_mapping(vma))) { |
| /* |
| * We do not free on error cases below as remove_vma |
| * gets called on error from higher level routine |
| */ |
| ret = track_pfn_vma_copy(vma); |
| if (ret) |
| return ret; |
| } |
| |
| /* |
| * We need to invalidate the secondary MMU mappings only when |
| * there could be a permission downgrade on the ptes of the |
| * parent mm. And a permission downgrade will only happen if |
| * is_cow_mapping() returns true. |
| */ |
| if (is_cow_mapping(vma->vm_flags)) |
| mmu_notifier_invalidate_range_start(src_mm, addr, end); |
| |
| ret = 0; |
| 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 (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, |
| vma, addr, next))) { |
| ret = -ENOMEM; |
| break; |
| } |
| } while (dst_pgd++, src_pgd++, addr = next, addr != end); |
| |
| if (is_cow_mapping(vma->vm_flags)) |
| mmu_notifier_invalidate_range_end(src_mm, |
| vma->vm_start, end); |
| return ret; |
| } |
| |
| static unsigned long zap_pte_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| long *zap_work, struct zap_details *details) |
| { |
| struct mm_struct *mm = tlb->mm; |
| pte_t *pte; |
| spinlock_t *ptl; |
| int file_rss = 0; |
| int anon_rss = 0; |
| |
| pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| arch_enter_lazy_mmu_mode(); |
| do { |
| pte_t ptent = *pte; |
| if (pte_none(ptent)) { |
| (*zap_work)--; |
| continue; |
| } |
| |
| (*zap_work) -= PAGE_SIZE; |
| |
| if (pte_present(ptent)) { |
| struct page *page; |
| |
| page = vm_normal_page(vma, addr, ptent); |
| 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_full(mm, addr, pte, |
| tlb->fullmm); |
| 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(mm, addr, pte, |
| pgoff_to_pte(page->index)); |
| if (PageAnon(page)) |
| anon_rss--; |
| else { |
| if (pte_dirty(ptent)) |
| set_page_dirty(page); |
| if (pte_young(ptent) && |
| likely(!VM_SequentialReadHint(vma))) |
| mark_page_accessed(page); |
| file_rss--; |
| } |
| page_remove_rmap(page); |
| if (unlikely(page_mapcount(page) < 0)) |
| print_bad_pte(vma, addr, ptent, 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)) { |
| if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) |
| print_bad_pte(vma, addr, ptent, NULL); |
| } else if |
| (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent)))) |
| print_bad_pte(vma, addr, ptent, NULL); |
| pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); |
| } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); |
| |
| add_mm_rss(mm, file_rss, anon_rss); |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(pte - 1, ptl); |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| long *zap_work, 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)) { |
| (*zap_work)--; |
| continue; |
| } |
| next = zap_pte_range(tlb, vma, pmd, addr, next, |
| zap_work, details); |
| } while (pmd++, addr = next, (addr != end && *zap_work > 0)); |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_pud_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| long *zap_work, 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)) { |
| (*zap_work)--; |
| continue; |
| } |
| next = zap_pmd_range(tlb, vma, pud, addr, next, |
| zap_work, details); |
| } while (pud++, addr = next, (addr != end && *zap_work > 0)); |
| |
| return addr; |
| } |
| |
| static unsigned long unmap_page_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, |
| unsigned long addr, unsigned long end, |
| long *zap_work, 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)) { |
| (*zap_work)--; |
| continue; |
| } |
| next = zap_pud_range(tlb, vma, pgd, addr, next, |
| zap_work, details); |
| } while (pgd++, addr = next, (addr != end && *zap_work > 0)); |
| tlb_end_vma(tlb, vma); |
| |
| return addr; |
| } |
| |
| #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 |
| * @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. |
| * |
| * We aim to not hold locks 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 vm_area_struct *vma, unsigned long start_addr, |
| unsigned long end_addr, unsigned long *nr_accounted, |
| struct zap_details *details) |
| { |
| long zap_work = 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 = (*tlbp)->fullmm; |
| struct mm_struct *mm = vma->vm_mm; |
| |
| mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); |
| 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; |
| |
| if (unlikely(is_pfn_mapping(vma))) |
| untrack_pfn_vma(vma, 0, 0); |
| |
| while (start != end) { |
| if (!tlb_start_valid) { |
| tlb_start = start; |
| tlb_start_valid = 1; |
| } |
| |
| if (unlikely(is_vm_hugetlb_page(vma))) { |
| /* |
| * It is undesirable to test vma->vm_file as it |
| * should be non-null for valid hugetlb area. |
| * However, vm_file will be NULL in the error |
| * cleanup path of do_mmap_pgoff. When |
| * hugetlbfs ->mmap method fails, |
| * do_mmap_pgoff() nullifies vma->vm_file |
| * before calling this function to clean up. |
| * Since no pte has actually been setup, it is |
| * safe to do nothing in this case. |
| */ |
| if (vma->vm_file) { |
| unmap_hugepage_range(vma, start, end, NULL); |
| zap_work -= (end - start) / |
| pages_per_huge_page(hstate_vma(vma)); |
| } |
| |
| start = end; |
| } else |
| start = unmap_page_range(*tlbp, vma, |
| start, end, &zap_work, details); |
| |
| if (zap_work > 0) { |
| BUG_ON(start != end); |
| break; |
| } |
| |
| tlb_finish_mmu(*tlbp, tlb_start, start); |
| |
| if (need_resched() || |
| (i_mmap_lock && spin_needbreak(i_mmap_lock))) { |
| if (i_mmap_lock) { |
| *tlbp = NULL; |
| goto out; |
| } |
| cond_resched(); |
| } |
| |
| *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); |
| tlb_start_valid = 0; |
| zap_work = ZAP_BLOCK_SIZE; |
| } |
| } |
| out: |
| mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); |
| 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; |
| |
| lru_add_drain(); |
| tlb = tlb_gather_mmu(mm, 0); |
| update_hiwater_rss(mm); |
| end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); |
| if (tlb) |
| tlb_finish_mmu(tlb, address, end); |
| return end; |
| } |
| |
| /** |
| * zap_vma_ptes - remove ptes mapping the vma |
| * @vma: vm_area_struct holding ptes to be zapped |
| * @address: starting address of pages to zap |
| * @size: number of bytes to zap |
| * |
| * This function only unmaps ptes assigned to VM_PFNMAP vmas. |
| * |
| * The entire address range must be fully contained within the vma. |
| * |
| * Returns 0 if successful. |
| */ |
| int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, |
| unsigned long size) |
| { |
| if (address < vma->vm_start || address + size > vma->vm_end || |
| !(vma->vm_flags & VM_PFNMAP)) |
| return -1; |
| zap_page_range(vma, address, size, NULL); |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(zap_vma_ptes); |
| |
| /* |
| * Do a quick page-table lookup for a single page. |
| */ |
| struct page *follow_page(struct vm_area_struct *vma, unsigned long address, |
| unsigned int flags) |
| { |
| pgd_t *pgd; |
| pud_t *pud; |
| pmd_t *pmd; |
| pte_t *ptep, pte; |
| spinlock_t *ptl; |
| struct page *page; |
| struct mm_struct *mm = vma->vm_mm; |
| |
| page = follow_huge_addr(mm, address, flags & FOLL_WRITE); |
| if (!IS_ERR(page)) { |
| BUG_ON(flags & FOLL_GET); |
| goto out; |
| } |
| |
| page = NULL; |
| pgd = pgd_offset(mm, address); |
| if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
| goto no_page_table; |
| |
| pud = pud_offset(pgd, address); |
| if (pud_none(*pud)) |
| goto no_page_table; |
| if (pud_huge(*pud)) { |
| BUG_ON(flags & FOLL_GET); |
| page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); |
| goto out; |
| } |
| if (unlikely(pud_bad(*pud))) |
| goto no_page_table; |
| |
| pmd = pmd_offset(pud, address); |
| if (pmd_none(*pmd)) |
| goto no_page_table; |
| if (pmd_huge(*pmd)) { |
| BUG_ON(flags & FOLL_GET); |
| page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); |
| goto out; |
| } |
| if (unlikely(pmd_bad(*pmd))) |
| goto no_page_table; |
| |
| ptep = pte_offset_map_lock(mm, pmd, address, &ptl); |
| |
| pte = *ptep; |
| if (!pte_present(pte)) |
| goto no_page; |
| if ((flags & FOLL_WRITE) && !pte_write(pte)) |
| goto unlock; |
| |
| page = vm_normal_page(vma, address, pte); |
| if (unlikely(!page)) { |
| if ((flags & FOLL_DUMP) || |
| !is_zero_pfn(pte_pfn(pte))) |
| goto bad_page; |
| page = pte_page(pte); |
| } |
| |
| if (flags & FOLL_GET) |
| get_page(page); |
| if (flags & FOLL_TOUCH) { |
| if ((flags & FOLL_WRITE) && |
| !pte_dirty(pte) && !PageDirty(page)) |
| set_page_dirty(page); |
| /* |
| * pte_mkyoung() would be more correct here, but atomic care |
| * is needed to avoid losing the dirty bit: it is easier to use |
| * mark_page_accessed(). |
| */ |
| mark_page_accessed(page); |
| } |
| unlock: |
| pte_unmap_unlock(ptep, ptl); |
| out: |
| return page; |
| |
| bad_page: |
| pte_unmap_unlock(ptep, ptl); |
| return ERR_PTR(-EFAULT); |
| |
| no_page: |
| pte_unmap_unlock(ptep, ptl); |
| if (!pte_none(pte)) |
| return page; |
| |
| no_page_table: |
| /* |
| * When core dumping an enormous anonymous area that nobody |
| * has touched so far, we don't want to allocate unnecessary pages or |
| * page tables. Return error instead of NULL to skip handle_mm_fault, |
| * then get_dump_page() will return NULL to leave a hole in the dump. |
| * But we can only make this optimization where a hole would surely |
| * be zero-filled if handle_mm_fault() actually did handle it. |
| */ |
| if ((flags & FOLL_DUMP) && |
| (!vma->vm_ops || !vma->vm_ops->fault)) |
| return ERR_PTR(-EFAULT); |
| return page; |
| } |
| |
| int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
| unsigned long start, int nr_pages, unsigned int gup_flags, |
| struct page **pages, struct vm_area_struct **vmas) |
| { |
| int i; |
| unsigned long vm_flags; |
| |
| if (nr_pages <= 0) |
| return 0; |
| |
| VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); |
| |
| /* |
| * Require read or write permissions. |
| * If FOLL_FORCE is set, we only require the "MAY" flags. |
| */ |
| vm_flags = (gup_flags & FOLL_WRITE) ? |
| (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); |
| vm_flags &= (gup_flags & FOLL_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; |
| |
| /* user gate pages are read-only */ |
| if (gup_flags & FOLL_WRITE) |
| 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) { |
| struct page *page = vm_normal_page(gate_vma, start, *pte); |
| pages[i] = page; |
| if (page) |
| get_page(page); |
| } |
| pte_unmap(pte); |
| if (vmas) |
| vmas[i] = gate_vma; |
| i++; |
| start += PAGE_SIZE; |
| nr_pages--; |
| continue; |
| } |
| |
| if (!vma || |
| (vma->vm_flags & (VM_IO | VM_PFNMAP)) || |
| !(vm_flags & vma->vm_flags)) |
| return i ? : -EFAULT; |
| |
| if (is_vm_hugetlb_page(vma)) { |
| i = follow_hugetlb_page(mm, vma, pages, vmas, |
| &start, &nr_pages, i, gup_flags); |
| continue; |
| } |
| |
| do { |
| struct page *page; |
| unsigned int foll_flags = gup_flags; |
| |
| /* |
| * If we have a pending SIGKILL, don't keep faulting |
| * pages and potentially allocating memory. |
| */ |
| if (unlikely(fatal_signal_pending(current))) |
| return i ? i : -ERESTARTSYS; |
| |
| cond_resched(); |
| while (!(page = follow_page(vma, start, foll_flags))) { |
| int ret; |
| |
| ret = handle_mm_fault(mm, vma, start, |
| (foll_flags & FOLL_WRITE) ? |
| FAULT_FLAG_WRITE : 0); |
| |
| if (ret & VM_FAULT_ERROR) { |
| if (ret & VM_FAULT_OOM) |
| return i ? i : -ENOMEM; |
| else if (ret & VM_FAULT_SIGBUS) |
| return i ? i : -EFAULT; |
| BUG(); |
| } |
| if (ret & VM_FAULT_MAJOR) |
| tsk->maj_flt++; |
| else |
| tsk->min_flt++; |
| |
| /* |
| * 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. But only |
| * do so when looping for pte_write is futile: |
| * in some cases userspace may also be wanting |
| * to write to the gotten user page, which a |
| * read fault here might prevent (a readonly |
| * page might get reCOWed by userspace write). |
| */ |
| if ((ret & VM_FAULT_WRITE) && |
| !(vma->vm_flags & VM_WRITE)) |
| foll_flags &= ~FOLL_WRITE; |
| |
| cond_resched(); |
| } |
| if (IS_ERR(page)) |
| return i ? i : PTR_ERR(page); |
| if (pages) { |
| pages[i] = page; |
| |
| flush_anon_page(vma, page, start); |
| flush_dcache_page(page); |
| } |
| if (vmas) |
| vmas[i] = vma; |
| i++; |
| start += PAGE_SIZE; |
| nr_pages--; |
| } while (nr_pages && start < vma->vm_end); |
| } while (nr_pages); |
| return i; |
| } |
| |
| /** |
| * get_user_pages() - pin user pages in memory |
| * @tsk: task_struct of target task |
| * @mm: mm_struct of target mm |
| * @start: starting user address |
| * @nr_pages: number of pages from start to pin |
| * @write: whether pages will be written to by the caller |
| * @force: whether to force write access even if user mapping is |
| * readonly. This will result in the page being COWed even |
| * in MAP_SHARED mappings. You do not want this. |
| * @pages: array that receives pointers to the pages pinned. |
| * Should be at least nr_pages long. Or NULL, if caller |
| * only intends to ensure the pages are faulted in. |
| * @vmas: array of pointers to vmas corresponding to each page. |
| * Or NULL if the caller does not require them. |
| * |
| * Returns number of pages pinned. This may be fewer than the number |
| * requested. If nr_pages is 0 or negative, returns 0. If no pages |
| * were pinned, returns -errno. Each page returned must be released |
| * with a put_page() call when it is finished with. vmas will only |
| * remain valid while mmap_sem is held. |
| * |
| * Must be called with mmap_sem held for read or write. |
| * |
| * get_user_pages walks a process's page tables and takes a reference to |
| * each struct page that each user address corresponds to at a given |
| * instant. That is, it takes the page that would be accessed if a user |
| * thread accesses the given user virtual address at that instant. |
| * |
| * This does not guarantee that the page exists in the user mappings when |
| * get_user_pages returns, and there may even be a completely different |
| * page there in some cases (eg. if mmapped pagecache has been invalidated |
| * and subsequently re faulted). However it does guarantee that the page |
| * won't be freed completely. And mostly callers simply care that the page |
| * contains data that was valid *at some point in time*. Typically, an IO |
| * or similar operation cannot guarantee anything stronger anyway because |
| * locks can't be held over the syscall boundary. |
| * |
| * If write=0, the page must not be written to. If the page is written to, |
| * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called |
| * after the page is finished with, and before put_page is called. |
| * |
| * get_user_pages is typically used for fewer-copy IO operations, to get a |
| * handle on the memory by some means other than accesses via the user virtual |
| * addresses. The pages may be submitted for DMA to devices or accessed via |
| * their kernel linear mapping (via the kmap APIs). Care should be taken to |
| * use the correct cache flushing APIs. |
| * |
| * See also get_user_pages_fast, for performance critical applications. |
| */ |
| int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
| unsigned long start, int nr_pages, int write, int force, |
| struct page **pages, struct vm_area_struct **vmas) |
| { |
| int flags = FOLL_TOUCH; |
| |
| if (pages) |
| flags |= FOLL_GET; |
| if (write) |
| flags |= FOLL_WRITE; |
| if (force) |
| flags |= FOLL_FORCE; |
| |
| return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas); |
| } |
| EXPORT_SYMBOL(get_user_pages); |
| |
| /** |
| * get_dump_page() - pin user page in memory while writing it to core dump |
| * @addr: user address |
| * |
| * Returns struct page pointer of user page pinned for dump, |
| * to be freed afterwards by page_cache_release() or put_page(). |
| * |
| * Returns NULL on any kind of failure - a hole must then be inserted into |
| * the corefile, to preserve alignment with its headers; and also returns |
| * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - |
| * allowing a hole to be left in the corefile to save diskspace. |
| * |
| * Called without mmap_sem, but after all other threads have been killed. |
| */ |
| #ifdef CONFIG_ELF_CORE |
| struct page *get_dump_page(unsigned long addr) |
| { |
| struct vm_area_struct *vma; |
| struct page *page; |
| |
| if (__get_user_pages(current, current->mm, addr, 1, |
| FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1) |
| return NULL; |
| flush_cache_page(vma, addr, page_to_pfn(page)); |
| return page; |
| } |
| #endif /* CONFIG_ELF_CORE */ |
| |
| pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr, |
| spinlock_t **ptl) |
| { |
| pgd_t * pgd = pgd_offset(mm, addr); |
| pud_t * pud = pud_alloc(mm, pgd, addr); |
| if (pud) { |
| pmd_t * pmd = pmd_alloc(mm, pud, addr); |
| if (pmd) |
| return pte_alloc_map_lock(mm, pmd, addr, ptl); |
| } |
| return NULL; |
| } |
| |
| /* |
| * This is the old fallback for page remapping. |
| * |
| * For historical reasons, it only allows reserved pages. Only |
| * old drivers should use this, and they needed to mark their |
| * pages reserved for the old functions anyway. |
| */ |
| static int insert_page(struct vm_area_struct *vma, unsigned long addr, |
| struct page *page, pgprot_t prot) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| int retval; |
| pte_t *pte; |
| spinlock_t *ptl; |
| |
| retval = -EINVAL; |
| if (PageAnon(page)) |
| goto out; |
| retval = -ENOMEM; |
| flush_dcache_page(page); |
| pte = get_locked_pte(mm, addr, &ptl); |
| if (!pte) |
| goto out; |
| retval = -EBUSY; |
| if (!pte_none(*pte)) |
| goto out_unlock; |
| |
| /* Ok, finally just insert the thing.. */ |
| get_page(page); |
| inc_mm_counter(mm, file_rss); |
| page_add_file_rmap(page); |
| set_pte_at(mm, addr, pte, mk_pte(page, prot)); |
| |
| retval = 0; |
| pte_unmap_unlock(pte, ptl); |
| return retval; |
| out_unlock: |
| pte_unmap_unlock(pte, ptl); |
| out: |
| return retval; |
| } |
| |
| /** |
| * vm_insert_page - insert single page into user vma |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @page: source kernel page |
| * |
| * This allows drivers to insert individual pages they've allocated |
| * into a user vma. |
| * |
| * The page has to be a nice clean _individual_ kernel allocation. |
| * If you allocate a compound page, you need to have marked it as |
| * such (__GFP_COMP), or manually just split the page up yourself |
| * (see split_page()). |
| * |
| * NOTE! Traditionally this was done with "remap_pfn_range()" which |
| * took an arbitrary page protection parameter. This doesn't allow |
| * that. Your vma protection will have to be set up correctly, which |
| * means that if you want a shared writable mapping, you'd better |
| * ask for a shared writable mapping! |
| * |
| * The page does not need to be reserved. |
| */ |
| int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
| struct page *page) |
| { |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return -EFAULT; |
| if (!page_count(page)) |
| return -EINVAL; |
| vma->vm_flags |= VM_INSERTPAGE; |
| return insert_page(vma, addr, page, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vm_insert_page); |
| |
| static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn, pgprot_t prot) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| int retval; |
| pte_t *pte, entry; |
| spinlock_t *ptl; |
| |
| retval = -ENOMEM; |
| pte = get_locked_pte(mm, addr, &ptl); |
| if (!pte) |
| goto out; |
| retval = -EBUSY; |
| if (!pte_none(*pte)) |
| goto out_unlock; |
| |
| /* Ok, finally just insert the thing.. */ |
| entry = pte_mkspecial(pfn_pte(pfn, prot)); |
| set_pte_at(mm, addr, pte, entry); |
| update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */ |
| |
| retval = 0; |
| out_unlock: |
| pte_unmap_unlock(pte, ptl); |
| out: |
| return retval; |
| } |
| |
| /** |
| * vm_insert_pfn - insert single pfn into user vma |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @pfn: source kernel pfn |
| * |
| * Similar to vm_inert_page, this allows drivers to insert individual pages |
| * they've allocated into a user vma. Same comments apply. |
| * |
| * This function should only be called from a vm_ops->fault handler, and |
| * in that case the handler should return NULL. |
| * |
| * vma cannot be a COW mapping. |
| * |
| * As this is called only for pages that do not currently exist, we |
| * do not need to flush old virtual caches or the TLB. |
| */ |
| int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn) |
| { |
| int ret; |
| pgprot_t pgprot = vma->vm_page_prot; |
| /* |
| * Technically, architectures with pte_special can avoid all these |
| * restrictions (same for remap_pfn_range). However we would like |
| * consistency in testing and feature parity among all, so we should |
| * try to keep these invariants in place for everybody. |
| */ |
| BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); |
| BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
| (VM_PFNMAP|VM_MIXEDMAP)); |
| BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
| BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); |
| |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return -EFAULT; |
| if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE)) |
| return -EINVAL; |
| |
| ret = insert_pfn(vma, addr, pfn, pgprot); |
| |
| if (ret) |
| untrack_pfn_vma(vma, pfn, PAGE_SIZE); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(vm_insert_pfn); |
| |
| int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn) |
| { |
| BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); |
| |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return -EFAULT; |
| |
| /* |
| * If we don't have pte special, then we have to use the pfn_valid() |
| * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* |
| * refcount the page if pfn_valid is true (hence insert_page rather |
| * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP |
| * without pte special, it would there be refcounted as a normal page. |
| */ |
| if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { |
| struct page *page; |
| |
| page = pfn_to_page(pfn); |
| return insert_page(vma, addr, page, vma->vm_page_prot); |
| } |
| return insert_pfn(vma, addr, pfn, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vm_insert_mixed); |
| |
| /* |
| * 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; |
| spinlock_t *ptl; |
| |
| pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return -ENOMEM; |
| arch_enter_lazy_mmu_mode(); |
| do { |
| BUG_ON(!pte_none(*pte)); |
| set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); |
| pfn++; |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(pte - 1, ptl); |
| 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; |
| } |
| |
| /** |
| * remap_pfn_range - remap kernel memory to userspace |
| * @vma: user vma to map to |
| * @addr: target user address to start at |
| * @pfn: physical address of kernel memory |
| * @size: size of map area |
| * @prot: page protection flags for this mapping |
| * |
| * 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 is specified all over the place, because |
| * in 2.4 it kept swapout's vma scan off this vma; but |
| * in 2.6 the LRU scan won't even find its pages, so this |
| * flag means no more than count its pages in reserved_vm, |
| * and omit it from core dump, even when VM_IO turned off. |
| * VM_PFNMAP tells the core MM that the base pages are just |
| * raw PFN mappings, and do not have a "struct page" associated |
| * with them. |
| * |
| * There's a horrible special case to handle copy-on-write |
| * behaviour that some programs depend on. We mark the "original" |
| * un-COW'ed pages by matching them up with "vma->vm_pgoff". |
| */ |
| if (addr == vma->vm_start && end == vma->vm_end) { |
| vma->vm_pgoff = pfn; |
| vma->vm_flags |= VM_PFN_AT_MMAP; |
| } else if (is_cow_mapping(vma->vm_flags)) |
| return -EINVAL; |
| |
| vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; |
| |
| err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size)); |
| if (err) { |
| /* |
| * To indicate that track_pfn related cleanup is not |
| * needed from higher level routine calling unmap_vmas |
| */ |
| vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP); |
| vma->vm_flags &= ~VM_PFN_AT_MMAP; |
| return -EINVAL; |
| } |
| |
| BUG_ON(addr >= end); |
| pfn -= addr >> PAGE_SHIFT; |
| pgd = pgd_offset(mm, addr); |
| flush_cache_range(vma, addr, end); |
| 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); |
| |
| if (err) |
| untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size)); |
| |
| return err; |
| } |
| EXPORT_SYMBOL(remap_pfn_range); |
| |
| static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data) |
| { |
| pte_t *pte; |
| int err; |
| pgtable_t token; |
| spinlock_t *uninitialized_var(ptl); |
| |
| pte = (mm == &init_mm) ? |
| pte_alloc_kernel(pmd, addr) : |
| pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return -ENOMEM; |
| |
| BUG_ON(pmd_huge(*pmd)); |
| |
| arch_enter_lazy_mmu_mode(); |
| |
| token = pmd_pgtable(*pmd); |
| |
| do { |
| err = fn(pte, token, addr, data); |
| if (err) |
| break; |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| |
| arch_leave_lazy_mmu_mode(); |
| |
| if (mm != &init_mm) |
| pte_unmap_unlock(pte-1, ptl); |
| return err; |
| } |
| |
| static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| int err; |
| |
| BUG_ON(pud_huge(*pud)); |
| |
| pmd = pmd_alloc(mm, pud, addr); |
| if (!pmd) |
| return -ENOMEM; |
| do { |
| next = pmd_addr_end(addr, end); |
| err = apply_to_pte_range(mm, pmd, addr, next, fn, data); |
| if (err) |
| break; |
| } while (pmd++, addr = next, addr != end); |
| return err; |
| } |
| |
| static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data) |
| { |
| pud_t *pud; |
| unsigned long next; |
| int err; |
| |
| pud = pud_alloc(mm, pgd, addr); |
| if (!pud) |
| return -ENOMEM; |
| do { |
| next = pud_addr_end(addr, end); |
| err = apply_to_pmd_range(mm, pud, addr, next, fn, data); |
| if (err) |
| break; |
| } while (pud++, addr = next, addr != end); |
| return err; |
| } |
| |
| /* |
| * Scan a region of virtual memory, filling in page tables as necessary |
| * and calling a provided function on each leaf page table. |
| */ |
| int apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
| unsigned long size, pte_fn_t fn, void *data) |
| { |
| pgd_t *pgd; |
| unsigned long next; |
| unsigned long start = addr, end = addr + size; |
| int err; |
| |
| BUG_ON(addr >= end); |
| mmu_notifier_invalidate_range_start(mm, start, end); |
| pgd = pgd_offset(mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| err = apply_to_pud_range(mm, pgd, addr, next, fn, data); |
| if (err) |
| break; |
| } while (pgd++, addr = next, addr != end); |
| mmu_notifier_invalidate_range_end(mm, start, end); |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(apply_to_page_range); |
| |
| /* |
| * handle_pte_fault chooses page fault handler according to an entry |
| * which was read non-atomically. Before making any commitment, on |
| * those architectures or configurations (e.g. i386 with PAE) which |
| * might give a mix of unmatched parts, do_swap_page and do_file_page |
| * must check under lock before unmapping the pte and proceeding |
| * (but do_wp_page is only called after already making such a check; |
| * and do_anonymous_page and do_no_page can safely check later on). |
| */ |
| static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, |
| pte_t *page_table, pte_t orig_pte) |
| { |
| int same = 1; |
| #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) |
| if (sizeof(pte_t) > sizeof(unsigned long)) { |
| spinlock_t *ptl = pte_lockptr(mm, pmd); |
| spin_lock(ptl); |
| same = pte_same(*page_table, orig_pte); |
| spin_unlock(ptl); |
| } |
| #endif |
| pte_unmap(page_table); |
| return same; |
| } |
| |
| /* |
| * 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; |
| } |
| |
| static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) |
| { |
| /* |
| * If the source page was a PFN mapping, we don't have |
| * a "struct page" for it. We do a best-effort copy by |
| * just copying from the original user address. If that |
| * fails, we just zero-fill it. Live with it. |
| */ |
| if (unlikely(!src)) { |
| void *kaddr = kmap_atomic(dst, KM_USER0); |
| void __user *uaddr = (void __user *)(va & PAGE_MASK); |
| |
| /* |
| * This really shouldn't fail, because the page is there |
| * in the page tables. But it might just be unreadable, |
| * in which case we just give up and fill the result with |
| * zeroes. |
| */ |
| if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) |
| memset(kaddr, 0, PAGE_SIZE); |
| kunmap_atomic(kaddr, KM_USER0); |
| flush_dcache_page(dst); |
| } else |
| copy_user_highpage(dst, src, va, vma); |
| } |
| |
| /* |
| * 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. |
| * |
| * 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 enter with non-exclusive mmap_sem (to exclude vma changes, |
| * but allow concurrent faults), with pte both mapped and locked. |
| * We return with mmap_sem still held, but pte unmapped and unlocked. |
| */ |
| static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| unsigned long address, pte_t *page_table, pmd_t *pmd, |
| spinlock_t *ptl, pte_t orig_pte) |
| { |
| struct page *old_page, *new_page; |
| pte_t entry; |
| int reuse = 0, ret = 0; |
| int page_mkwrite = 0; |
| struct page *dirty_page = NULL; |
| |
| old_page = vm_normal_page(vma, address, orig_pte); |
| if (!old_page) { |
| /* |
| * VM_MIXEDMAP !pfn_valid() case |
| * |
| * We should not cow pages in a shared writeable mapping. |
| * Just mark the pages writable as we can't do any dirty |
| * accounting on raw pfn maps. |
| */ |
| if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
| (VM_WRITE|VM_SHARED)) |
| goto reuse; |
| goto gotten; |
| } |
| |
| /* |
| * Take out anonymous pages first, anonymous shared vmas are |
| * not dirty accountable. |
| */ |
| if (PageAnon(old_page) && !PageKsm(old_page)) { |
| if (!trylock_page(old_page)) { |
| page_cache_get(old_page); |
| pte_unmap_unlock(page_table, ptl); |
| lock_page(old_page); |
| page_table = pte_offset_map_lock(mm, pmd, address, |
| &ptl); |
| if (!pte_same(*page_table, orig_pte)) { |
| unlock_page(old_page); |
| page_cache_release(old_page); |
| goto unlock; |
| } |
| page_cache_release(old_page); |
| } |
| reuse = reuse_swap_page(old_page); |
| unlock_page(old_page); |
| } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
| (VM_WRITE|VM_SHARED))) { |
| /* |
| * Only catch write-faults on shared writable pages, |
| * read-only shared pages can get COWed by |
| * get_user_pages(.write=1, .force=1). |
| */ |
| if (vma->vm_ops && vma->vm_ops->page_mkwrite) { |
| struct vm_fault vmf; |
| int tmp; |
| |
| vmf.virtual_address = (void __user *)(address & |
| PAGE_MASK); |
| vmf.pgoff = old_page->index; |
| vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
| vmf.page = old_page; |
| |
| /* |
| * Notify the address space that the page is about to |
| * become writable so that it can prohibit this or wait |
| * for the page to get into an appropriate state. |
| * |
| * We do this without the lock held, so that it can |
| * sleep if it needs to. |
| */ |
| page_cache_get(old_page); |
| pte_unmap_unlock(page_table, ptl); |
| |
| tmp = vma->vm_ops->page_mkwrite(vma, &vmf); |
| if (unlikely(tmp & |
| (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { |
| ret = tmp; |
| goto unwritable_page; |
| } |
| if (unlikely(!(tmp & VM_FAULT_LOCKED))) { |
| lock_page(old_page); |
| if (!old_page->mapping) { |
| ret = 0; /* retry the fault */ |
| unlock_page(old_page); |
| goto unwritable_page; |
| } |
| } else |
| VM_BUG_ON(!PageLocked(old_page)); |
| |
| /* |
| * Since we dropped the lock we need to revalidate |
| * the PTE as someone else may have changed it. If |
| * they did, we just return, as we can count on the |
| * MMU to tell us if they didn't also make it writable. |
| */ |
| page_table = pte_offset_map_lock(mm, pmd, address, |
| &ptl); |
| if (!pte_same(*page_table, orig_pte)) { |
| unlock_page(old_page); |
| page_cache_release(old_page); |
| goto unlock; |
| } |
| |
| page_mkwrite = 1; |
| } |
| dirty_page = old_page; |
| get_page(dirty_page); |
| reuse = 1; |
| } |
| |
| if (reuse) { |
| reuse: |
| flush_cache_page(vma, address, pte_pfn(orig_pte)); |
| entry = pte_mkyoung(orig_pte); |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| if (ptep_set_access_flags(vma, address, page_table, entry,1)) |
| update_mmu_cache(vma, address, entry); |
| ret |= VM_FAULT_WRITE; |
| goto unlock; |
| } |
| |
| /* |
| * Ok, we need to copy. Oh, well.. |
| */ |
| page_cache_get(old_page); |
| gotten: |
| pte_unmap_unlock(page_table, ptl); |
| |
| if (unlikely(anon_vma_prepare(vma))) |
| goto oom; |
| |
| if (is_zero_pfn(pte_pfn(orig_pte))) { |
| new_page = alloc_zeroed_user_highpage_movable(vma, address); |
| if (!new_page) |
| goto oom; |
| } else { |
| new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); |
| if (!new_page) |
| goto oom; |
| cow_user_page(new_page, old_page, address, vma); |
| } |
| __SetPageUptodate(new_page); |
| |
| /* |
| * Don't let another task, with possibly unlocked vma, |
| * keep the mlocked page. |
| */ |
| if ((vma->vm_flags & VM_LOCKED) && old_page) { |
| lock_page(old_page); /* for LRU manipulation */ |
| clear_page_mlock(old_page); |
| unlock_page(old_page); |
| } |
| |
| if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) |
| goto oom_free_new; |
| |
| /* |
| * Re-check the pte - we dropped the lock |
| */ |
| page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| if (likely(pte_same(*page_table, orig_pte))) { |
| if (old_page) { |
| if (!PageAnon(old_page)) { |
| dec_mm_counter(mm, file_rss); |
| inc_mm_counter(mm, anon_rss); |
| } |
| } else |
| inc_mm_counter(mm, anon_rss); |
| flush_cache_page(vma, address, pte_pfn(orig_pte)); |
| entry = mk_pte(new_page, vma->vm_page_prot); |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| /* |
| * Clear the pte entry and flush it first, before updating the |
| * pte with the new entry. This will avoid a race condition |
| * seen in the presence of one thread doing SMC and another |
| * thread doing COW. |
| */ |
| ptep_clear_flush(vma, address, page_table); |
| page_add_new_anon_rmap(new_page, vma, address); |
| /* |
| * We call the notify macro here because, when using secondary |
| * mmu page tables (such as kvm shadow page tables), we want the |
| * new page to be mapped directly into the secondary page table. |
| */ |
| set_pte_at_notify(mm, address, page_table, entry); |
| update_mmu_cache(vma, address, entry); |
| if (old_page) { |
| /* |
| * Only after switching the pte to the new page may |
| * we remove the mapcount here. Otherwise another |
| * process may come and find the rmap count decremented |
| * before the pte is switched to the new page, and |
| * "reuse" the old page writing into it while our pte |
| * here still points into it and can be read by other |
| * threads. |
| * |
| * The critical issue is to order this |
| * page_remove_rmap with the ptp_clear_flush above. |
| * Those stores are ordered by (if nothing else,) |
| * the barrier present in the atomic_add_negative |
| * in page_remove_rmap. |
| * |
| * Then the TLB flush in ptep_clear_flush ensures that |
| * no process can access the old page before the |
| * decremented mapcount is visible. And the old page |
| * cannot be reused until after the decremented |
| * mapcount is visible. So transitively, TLBs to |
| * old page will be flushed before it can be reused. |
| */ |
| page_remove_rmap(old_page); |
| } |
| |
| /* Free the old page.. */ |
| new_page = old_page; |
| ret |= VM_FAULT_WRITE; |
| } else |
| mem_cgroup_uncharge_page(new_page); |
| |
| if (new_page) |
| page_cache_release(new_page); |
| if (old_page) |
| page_cache_release(old_page); |
| unlock: |
| pte_unmap_unlock(page_table, ptl); |
| if (dirty_page) { |
| /* |
| * Yes, Virginia, this is actually required to prevent a race |
| * with clear_page_dirty_for_io() from clearing the page dirty |
| * bit after it clear all dirty ptes, but before a racing |
| * do_wp_page installs a dirty pte. |
| * |
| * do_no_page is protected similarly. |
| */ |
| if (!page_mkwrite) { |
| wait_on_page_locked(dirty_page); |
| set_page_dirty_balance(dirty_page, page_mkwrite); |
| } |
| put_page(dirty_page); |
| if (page_mkwrite) { |
| struct address_space *mapping = dirty_page->mapping; |
| |
| set_page_dirty(dirty_page); |
| unlock_page(dirty_page); |
| page_cache_release(dirty_page); |
| if (mapping) { |
| /* |
| * Some device drivers do not set page.mapping |
| * but still dirty their pages |
| */ |
| balance_dirty_pages_ratelimited(mapping); |
| } |
| } |
| |
| /* file_update_time outside page_lock */ |
| if (vma->vm_file) |
| file_update_time(vma->vm_file); |
| } |
| return ret; |
| oom_free_new: |
| page_cache_release(new_page); |
| oom: |
| if (old_page) { |
| if (page_mkwrite) { |
| unlock_page(old_page); |
| page_cache_release(old_page); |
| } |
| page_cache_release(old_page); |
| } |
| return VM_FAULT_OOM; |
| |
| unwritable_page: |
| page_cache_release(old_page); |
| return ret; |
| } |
| |
| /* |
| * 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; |
| |
| /* |
| * files that support invalidating or truncating portions of the |
| * file from under mmaped areas must have their ->fault function |
| * return a locked page (and set VM_FAULT_LOCKED in the return). |
| * This provides synchronisation against concurrent unmapping here. |
| */ |
| |
| 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); |
| need_break = need_resched() || spin_needbreak(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); |
| |
| /* Protect against endless unmapping loops */ |
| mapping->truncate_count++; |
| 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); |
| |
| /** |
| * vmtruncate - unmap mappings "freed" by truncate() syscall |
| * @inode: inode of the file used |
| * @offset: file offset to start truncating |
| * |
| * 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) |
| { |
| if (inode->i_size < offset) { |
| unsigned long limit; |
| |
| 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); |
| } else { |
| struct address_space *mapping = inode->i_mapping; |
| |
| /* |
| * truncation of in-use swapfiles is disallowed - it would |
| * cause subsequent swapout to scribble on the now-freed |
| * blocks. |
| */ |
| if (IS_SWAPFILE(inode)) |
| return -ETXTBSY; |
| i_size_write(inode, offset); |
| |
| /* |
| * unmap_mapping_range is called twice, first simply for |
| * efficiency so that truncate_inode_pages does fewer |
| * single-page unmaps. However after this first call, and |
| * before truncate_inode_pages finishes, it is possible for |
| * private pages to be COWed, which remain after |
| * truncate_inode_pages finishes, hence the second |
| * unmap_mapping_range call must be made for correctness. |
| */ |
| unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); |
| truncate_inode_pages(mapping, offset); |
| unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); |
| } |
| |
| if (inode->i_op->truncate) |
| inode->i_op->truncate(inode); |
| return 0; |
| |
| out_sig: |
| send_sig(SIGXFSZ, current, 0); |
| out_big: |
| return -EFBIG; |
| } |
| EXPORT_SYMBOL(vmtruncate); |
| |
| int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| |
| /* |
| * If the underlying filesystem is not going to provide |
| * a way to truncate a range of blocks (punch a hole) - |
| * we should return failure right now. |
| */ |
| if (!inode->i_op->truncate_range) |
| return -ENOSYS; |
| |
| mutex_lock(&inode->i_mutex); |
| down_write(&inode->i_alloc_sem); |
| unmap_mapping_range(mapping, offset, (end - offset), 1); |
| truncate_inode_pages_range(mapping, offset, end); |
| unmap_mapping_range(mapping, offset, (end - offset), 1); |
| inode->i_op->truncate_range(inode, offset, end); |
| up_write(&inode->i_alloc_sem); |
| mutex_unlock(&inode->i_mutex); |
| |
| return 0; |
| } |
| |
| /* |
| * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| * but allow concurrent faults), and pte mapped but not yet locked. |
| * We return with mmap_sem still held, but pte unmapped and unlocked. |
| */ |
| static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| unsigned long address, pte_t *page_table, pmd_t *pmd, |
| unsigned int flags, pte_t orig_pte) |
| { |
| spinlock_t *ptl; |
| struct page *page; |
| swp_entry_t entry; |
| pte_t pte; |
| struct mem_cgroup *ptr = NULL; |
| int ret = 0; |
| |
| if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) |
| goto out; |
| |
| entry = pte_to_swp_entry(orig_pte); |
| if (is_migration_entry(entry)) { |
| migration_entry_wait(mm, pmd, address); |
| goto out; |
| } |
| delayacct_set_flag(DELAYACCT_PF_SWAPIN); |
| page = lookup_swap_cache(entry); |
| if (!page) { |
| grab_swap_token(mm); /* Contend for token _before_ read-in */ |
| page = swapin_readahead(entry, |
| GFP_HIGHUSER_MOVABLE, vma, address); |
| if (!page) { |
| /* |
| * Back out if somebody else faulted in this pte |
| * while we released the pte lock. |
| */ |
| page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| if (likely(pte_same(*page_table, orig_pte))) |
| ret = VM_FAULT_OOM; |
| delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
| goto unlock; |
| } |
| |
| /* Had to read the page from swap area: Major fault */ |
| ret = VM_FAULT_MAJOR; |
| count_vm_event(PGMAJFAULT); |
| } |
| |
| lock_page(page); |
| delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
| |
| if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { |
| ret = VM_FAULT_OOM; |
| goto out_page; |
| } |
| |
| /* |
| * Back out if somebody else already faulted in this pte. |
| */ |
| page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| if (unlikely(!pte_same(*page_table, orig_pte))) |
| 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. |
| * |
| * Be careful about the sequence of operations here. |
| * To get its accounting right, reuse_swap_page() must be called |
| * while the page is counted on swap but not yet in mapcount i.e. |
| * before page_add_anon_rmap() and swap_free(); try_to_free_swap() |
| * must be called after the swap_free(), or it will never succeed. |
| * Because delete_from_swap_page() may be called by reuse_swap_page(), |
| * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry |
| * in page->private. In this case, a record in swap_cgroup is silently |
| * discarded at swap_free(). |
| */ |
| |
| inc_mm_counter(mm, anon_rss); |
| pte = mk_pte(page, vma->vm_page_prot); |
| if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { |
| pte = maybe_mkwrite(pte_mkdirty(pte), vma); |
| flags &= ~FAULT_FLAG_WRITE; |
| } |
| flush_icache_page(vma, page); |
| set_pte_at(mm, address, page_table, pte); |
| page_add_anon_rmap(page, vma, address); |
| /* It's better to call commit-charge after rmap is established */ |
| mem_cgroup_commit_charge_swapin(page, ptr); |
| |
| swap_free(entry); |
| if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) |
| try_to_free_swap(page); |
| unlock_page(page); |
| |
| if (flags & FAULT_FLAG_WRITE) { |
| ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); |
| if (ret & VM_FAULT_ERROR) |
| ret &= VM_FAULT_ERROR; |
| goto out; |
| } |
| |
| /* No need to invalidate - it was non-present before */ |
| update_mmu_cache(vma, address, pte); |
| unlock: |
| pte_unmap_unlock(page_table, ptl); |
| out: |
| return ret; |
| out_nomap: |
| mem_cgroup_cancel_charge_swapin(ptr); |
| pte_unmap_unlock(page_table, ptl); |
| out_page: |
| unlock_page(page); |
| page_cache_release(page); |
| return ret; |
| } |
| |
| /* |
| * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| * but allow concurrent faults), and pte mapped but not yet locked. |
| * We return with mmap_sem still held, but pte unmapped and unlocked. |
| */ |
| static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| unsigned long address, pte_t *page_table, pmd_t *pmd, |
| unsigned int flags) |
| { |
| struct page *page; |
| spinlock_t *ptl; |
| pte_t entry; |
| |
| if (!(flags & FAULT_FLAG_WRITE)) { |
| entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), |
| vma->vm_page_prot)); |
| ptl = pte_lockptr(mm, pmd); |
| spin_lock(ptl); |
| if (!pte_none(*page_table)) |
| goto unlock; |
| goto setpte; |
| } |
| |
| /* Allocate our own private page. */ |
| pte_unmap(page_table); |
| |
| if (unlikely(anon_vma_prepare(vma))) |
| goto oom; |
| page = alloc_zeroed_user_highpage_movable(vma, address); |
| if (!page) |
| goto oom; |
| __SetPageUptodate(page); |
| |
| if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) |
| goto oom_free_page; |
| |
| entry = mk_pte(page, vma->vm_page_prot); |
| if (vma->vm_flags & VM_WRITE) |
| entry = pte_mkwrite(pte_mkdirty(entry)); |
| |
| page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| if (!pte_none(*page_table)) |
| goto release; |
| |
| inc_mm_counter(mm, anon_rss); |
| page_add_new_anon_rmap(page, vma, address); |
| setpte: |
| set_pte_at(mm, address, page_table, entry); |
| |
| /* No need to invalidate - it was non-present before */ |
| update_mmu_cache(vma, address, entry); |
| unlock: |
| pte_unmap_unlock(page_table, ptl); |
| return 0; |
| release: |
| mem_cgroup_uncharge_page(page); |
| page_cache_release(page); |
| goto unlock; |
| oom_free_page: |
| page_cache_release(page); |
| oom: |
| return VM_FAULT_OOM; |
| } |
| |
| /* |
| * __do_fault() tries to create a new page mapping. It aggressively |
| * tries to share with existing pages, but makes a separate copy if |
| * the FAULT_FLAG_WRITE is set in the flags parameter 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. |
| * |
| * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| * but allow concurrent faults), and pte neither mapped nor locked. |
| * We return with mmap_sem still held, but pte unmapped and unlocked. |
| */ |
| static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| unsigned long address, pmd_t *pmd, |
| pgoff_t pgoff, unsigned int flags, pte_t orig_pte) |
| { |
| pte_t *page_table; |
| spinlock_t *ptl; |
| struct page *page; |
| pte_t entry; |
| int anon = 0; |
| int charged = 0; |
| struct page *dirty_page = NULL; |
| struct vm_fault vmf; |
| int ret; |
| int page_mkwrite = 0; |
| |
| vmf.virtual_address = (void __user *)(address & PAGE_MASK); |
| vmf.pgoff = pgoff; |
| vmf.flags = flags; |
| vmf.page = NULL; |
| |
| ret = vma->vm_ops->fault(vma, &vmf); |
| if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) |
| return ret; |
| |
| /* |
| * For consistency in subsequent calls, make the faulted page always |
| * locked. |
| */ |
| if (unlikely(!(ret & VM_FAULT_LOCKED))) |
| lock_page(vmf.page); |
| else |
| VM_BUG_ON(!PageLocked(vmf.page)); |
| |
| /* |
| * Should we do an early C-O-W break? |
| */ |
| page = vmf.page; |
| if (flags & FAULT_FLAG_WRITE) { |
| if (!(vma->vm_flags & VM_SHARED)) { |
| anon = 1; |
| if (unlikely(anon_vma_prepare(vma))) { |
| ret = VM_FAULT_OOM; |
| goto out; |
| } |
| page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, |
| vma, address); |
| if (!page) { |
| ret = VM_FAULT_OOM; |
| goto out; |
| } |
| if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) { |
| ret = VM_FAULT_OOM; |
| page_cache_release(page); |
| goto out; |
| } |
| charged = 1; |
| /* |
| * Don't let another task, with possibly unlocked vma, |
| * keep the mlocked page. |
| */ |
| if (vma->vm_flags & VM_LOCKED) |
| clear_page_mlock(vmf.page); |
| copy_user_highpage(page, vmf.page, address, vma); |
| __SetPageUptodate(page); |
| } else { |
| /* |
| * If the page will be shareable, see if the backing |
| * address space wants to know that the page is about |
| * to become writable |
| */ |
| if (vma->vm_ops->page_mkwrite) { |
| int tmp; |
| |
| unlock_page(page); |
| vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
| tmp = vma->vm_ops->page_mkwrite(vma, &vmf); |
| if (unlikely(tmp & |
| (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { |
| ret = tmp; |
| goto unwritable_page; |
| } |
| if (unlikely(!(tmp & VM_FAULT_LOCKED))) { |
| lock_page(page); |
| if (!page->mapping) { |
| ret = 0; /* retry the fault */ |
| unlock_page(page); |
| goto unwritable_page; |
| } |
| } else |
| VM_BUG_ON(!PageLocked(page)); |
| page_mkwrite = 1; |
| } |
| } |
| |
| } |
| |
| page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
| |
| /* |
| * 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 FAULT_FLAG_WRITE is set, 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 (likely(pte_same(*page_table, orig_pte))) { |
| flush_icache_page(vma, page); |
| entry = mk_pte(page, vma->vm_page_prot); |
| if (flags & FAULT_FLAG_WRITE) |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| if (anon) { |
| inc_mm_counter(mm, anon_rss); |
| page_add_new_anon_rmap(page, vma, address); |
| } else { |
| inc_mm_counter(mm, file_rss); |
| page_add_file_rmap(page); |
| if (flags & FAULT_FLAG_WRITE) { |
| dirty_page = page; |
| get_page(dirty_page); |
| } |
| } |
| set_pte_at(mm, address, page_table, entry); |
| |
| /* no need to invalidate: a not-present page won't be cached */ |
| update_mmu_cache(vma, address, entry); |
| } else { |
| if (charged) |
| mem_cgroup_uncharge_page(page); |
| if (anon) |
| page_cache_release(page); |
| else |
| anon = 1; /* no anon but release faulted_page */ |
| } |
| |
| pte_unmap_unlock(page_table, ptl); |
| |
| out: |
| if (dirty_page) { |
| struct address_space *mapping = page->mapping; |
| |
| if (set_page_dirty(dirty_page)) |
| page_mkwrite = 1; |
| unlock_page(dirty_page); |
| put_page(dirty_page); |
| if (page_mkwrite && mapping) { |
| /* |
| * Some device drivers do not set page.mapping but still |
| * dirty their pages |
| */ |
| balance_dirty_pages_ratelimited(mapping); |
| } |
| |
| /* file_update_time outside page_lock */ |
| if (vma->vm_file) |
| file_update_time(vma->vm_file); |
| } else { |
| unlock_page(vmf.page); |
| if (anon) |
| page_cache_release(vmf.page); |
| } |
| |
| return ret; |
| |
| unwritable_page: |
| page_cache_release(page); |
| return ret; |
| } |
| |
| static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| unsigned long address, pte_t *page_table, pmd_t *pmd, |
| unsigned int flags, pte_t orig_pte) |
| { |
| pgoff_t pgoff = (((address & PAGE_MASK) |
| - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
| |
| pte_unmap(page_table); |
| return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); |
| } |
| |
| /* |
| * Fault of a previously existing named mapping. Repopulate the pte |
| * from the encoded file_pte if possible. This enables swappable |
| * nonlinear vmas. |
| * |
| * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| * but allow concurrent faults), and pte mapped but not yet locked. |
| * We return with mmap_sem still held, but pte unmapped and unlocked. |
| */ |
| static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| unsigned long address, pte_t *page_table, pmd_t *pmd, |
| unsigned int flags, pte_t orig_pte) |
| { |
| pgoff_t pgoff; |
| |
| flags |= FAULT_FLAG_NONLINEAR; |
| |
| if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) |
| return 0; |
| |
| if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { |
| /* |
| * Page table corrupted: show pte and kill process. |
| */ |
| print_bad_pte(vma, address, orig_pte, NULL); |
| return VM_FAULT_OOM; |
| } |
| |
| pgoff = pte_to_pgoff(orig_pte); |
| return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); |
| } |
| |
| /* |
| * 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). |
| * |
| * We enter with non-exclusive mmap_sem (to exclude vma changes, |
| * but allow concurrent faults), and pte mapped but not yet locked. |
| * We return with mmap_sem still held, but pte unmapped and unlocked. |
| */ |
| static inline int handle_pte_fault(struct mm_struct *mm, |
| struct vm_area_struct *vma, unsigned long address, |
| pte_t *pte, pmd_t *pmd, unsigned int flags) |
| { |
| pte_t entry; |
| spinlock_t *ptl; |
| |
| entry = *pte; |
| if (!pte_present(entry)) { |
| if (pte_none(entry)) { |
| if (vma->vm_ops) { |
| if (likely(vma->vm_ops->fault)) |
| return do_linear_fault(mm, vma, address, |
| pte, pmd, flags, entry); |
| } |
| return do_anonymous_page(mm, vma, address, |
| pte, pmd, flags); |
| } |
| if (pte_file(entry)) |
| return do_nonlinear_fault(mm, vma, address, |
| pte, pmd, flags, entry); |
| return do_swap_page(mm, vma, address, |
| pte, pmd, flags, entry); |
| } |
| |
| ptl = pte_lockptr(mm, pmd); |
| spin_lock(ptl); |
| if (unlikely(!pte_same(*pte, entry))) |
| goto unlock; |
| if (flags & FAULT_FLAG_WRITE) { |
| if (!pte_write(entry)) |
| return do_wp_page(mm, vma, address, |
| pte, pmd, ptl, entry); |
| entry = pte_mkdirty(entry); |
| } |
| entry = pte_mkyoung(entry); |
| if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { |
| update_mmu_cache(vma, address, entry); |
| } else { |
| /* |
| * This is needed only for protection faults but the arch code |
| * is not yet telling us if this is a protection fault or not. |
| * This still avoids useless tlb flushes for .text page faults |
| * with threads. |
| */ |
| if (flags & FAULT_FLAG_WRITE) |
| flush_tlb_page(vma, address); |
| } |
| unlock: |
| pte_unmap_unlock(pte, ptl); |
| return 0; |
| } |
| |
| /* |
| * 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, unsigned int flags) |
| { |
| pgd_t *pgd; |
| pud_t *pud; |
| pmd_t *pmd; |
| pte_t *pte; |
| |
| __set_current_state(TASK_RUNNING); |
| |
| count_vm_event(PGFAULT); |
| |
| if (unlikely(is_vm_hugetlb_page(vma))) |
| return hugetlb_fault(mm, vma, address, flags); |
| |
| pgd = pgd_offset(mm, address); |
| pud = pud_alloc(mm, pgd, address); |
| if (!pud) |
| return VM_FAULT_OOM; |
| pmd = pmd_alloc(mm, pud, address); |
| if (!pmd) |
| return VM_FAULT_OOM; |
| pte = pte_alloc_map(mm, pmd, address); |
| if (!pte) |
| return VM_FAULT_OOM; |
| |
| return handle_pte_fault(mm, vma, address, pte, pmd, flags); |
| } |
| |
| #ifndef __PAGETABLE_PUD_FOLDED |
| /* |
| * Allocate page upper directory. |
| * We've already handled the fast-path in-line. |
| */ |
| int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) |
| { |
| pud_t *new = pud_alloc_one(mm, address); |
| if (!new) |
| return -ENOMEM; |
| |
| smp_wmb(); /* See comment in __pte_alloc */ |
| |
| spin_lock(&mm->page_table_lock); |
| if (pgd_present(*pgd)) /* Another has populated it */ |
| pud_free(mm, new); |
| else |
| pgd_populate(mm, pgd, new); |
| spin_unlock(&mm->page_table_lock); |
| return 0; |
| } |
| #endif /* __PAGETABLE_PUD_FOLDED */ |
| |
| #ifndef __PAGETABLE_PMD_FOLDED |
| /* |
| * Allocate page middle directory. |
| * We've already handled the fast-path in-line. |
| */ |
| int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) |
| { |
| pmd_t *new = pmd_alloc_one(mm, address); |
| if (!new) |
| return -ENOMEM; |
| |
| smp_wmb(); /* See comment in __pte_alloc */ |
| |
| spin_lock(&mm->page_table_lock); |
| #ifndef __ARCH_HAS_4LEVEL_HACK |
| if (pud_present(*pud)) /* Another has populated it */ |
| pmd_free(mm, new); |
| else |
| pud_populate(mm, pud, new); |
| #else |
| if (pgd_present(*pud)) /* Another has populated it */ |
| pmd_free(mm, new); |
| else |
| pgd_populate(mm, pud, new); |
| #endif /* __ARCH_HAS_4LEVEL_HACK */ |
| spin_unlock(&mm->page_table_lock); |
| return 0; |
| } |
| #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 -ENOMEM; |
| write = (vma->vm_flags & VM_WRITE) != 0; |
| BUG_ON(addr >= end); |
| BUG_ON(end > vma->vm_end); |
| len = DIV_ROUND_UP(end, 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 : -EFAULT; |
| } |
| |
| #if !defined(__HAVE_ARCH_GATE_AREA) |
| |
| #if defined(AT_SYSINFO_EHDR) |
| static 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_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; |
| gate_vma.vm_page_prot = __P101; |
| /* |
| * Make sure the vDSO gets into every core dump. |
| * Dumping its contents makes post-mortem fully interpretable later |
| * without matching up the same kernel and hardware config to see |
| * what PC values meant. |
| */ |
| gate_vma.vm_flags |= VM_ALWAYSDUMP; |
| 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 */ |
| |
| static int follow_pte(struct mm_struct *mm, unsigned long address, |
| pte_t **ptepp, spinlock_t **ptlp) |
| { |
| pgd_t *pgd; |
| pud_t *pud; |
| pmd_t *pmd; |
| pte_t *ptep; |
| |
| 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; |
| |
| /* We cannot handle huge page PFN maps. Luckily they don't exist. */ |
| if (pmd_huge(*pmd)) |
| goto out; |
| |
| ptep = pte_offset_map_lock(mm, pmd, address, ptlp); |
| if (!ptep) |
| goto out; |
| if (!pte_present(*ptep)) |
| goto unlock; |
| *ptepp = ptep; |
| return 0; |
| unlock: |
| pte_unmap_unlock(ptep, *ptlp); |
| out: |
| return -EINVAL; |
| } |
| |
| /** |
| * follow_pfn - look up PFN at a user virtual address |
| * @vma: memory mapping |
| * @address: user virtual address |
| * @pfn: location to store found PFN |
| * |
| * Only IO mappings and raw PFN mappings are allowed. |
| * |
| * Returns zero and the pfn at @pfn on success, -ve otherwise. |
| */ |
| int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
| unsigned long *pfn) |
| { |
| int ret = -EINVAL; |
| spinlock_t *ptl; |
| pte_t *ptep; |
| |
| if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| return ret; |
| |
| ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); |
| if (ret) |
| return ret; |
| *pfn = pte_pfn(*ptep); |
| pte_unmap_unlock(ptep, ptl); |
| return 0; |
| } |
| EXPORT_SYMBOL(follow_pfn); |
| |
| #ifdef CONFIG_HAVE_IOREMAP_PROT |
| int follow_phys(struct vm_area_struct *vma, |
| unsigned long address, unsigned int flags, |
| unsigned long *prot, resource_size_t *phys) |
| { |
| int ret = -EINVAL; |
| pte_t *ptep, pte; |
| spinlock_t *ptl; |
| |
| if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| goto out; |
| |
| if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) |
| goto out; |
| pte = *ptep; |
| |
| if ((flags & FOLL_WRITE) && !pte_write(pte)) |
| goto unlock; |
| |
| *prot = pgprot_val(pte_pgprot(pte)); |
| *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; |
| |
| ret = 0; |
| unlock: |
| pte_unmap_unlock(ptep, ptl); |
| out: |
| return ret; |
| } |
| |
| int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, |
| void *buf, int len, int write) |
| { |
| resource_size_t phys_addr; |
| unsigned long prot = 0; |
| void __iomem *maddr; |
| int offset = addr & (PAGE_SIZE-1); |
| |
| if (follow_phys(vma, addr, write, &prot, &phys_addr)) |
| return -EINVAL; |
| |
| maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); |
| if (write) |
| memcpy_toio(maddr + offset, buf, len); |
| else |
| memcpy_fromio(buf, maddr + offset, len); |
| iounmap(maddr); |
| |
| return len; |
| } |
| #endif |
| |
| /* |
| * Access another process' address space. |
| * Source/target buffer must be kernel space, |
| * Do not walk the page table directly, use get_user_pages |
| */ |
| int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) |
| { |
| struct mm_struct *mm; |
| struct vm_area_struct *vma; |
| void *old_buf = buf; |
| |
| mm = get_task_mm(tsk); |
| if (!mm) |
| return 0; |
| |
| down_read(&mm->mmap_sem); |
| /* ignore errors, just check how much was successfully transferred */ |
| while (len) { |
| int bytes, ret, offset; |
| void *maddr; |
| struct page *page = NULL; |
| |
| ret = get_user_pages(tsk, mm, addr, 1, |
| write, 1, &page, &vma); |
| if (ret <= 0) { |
| /* |
| * Check if this is a VM_IO | VM_PFNMAP VMA, which |
| * we can access using slightly different code. |
| */ |
| #ifdef CONFIG_HAVE_IOREMAP_PROT |
| vma = find_vma(mm, addr); |
| if (!vma) |
| break; |
| if (vma->vm_ops && vma->vm_ops->access) |
| ret = vma->vm_ops->access(vma, addr, buf, |
| len, write); |
| if (ret <= 0) |
| #endif |
| break; |
| bytes = ret; |
| } else { |
| bytes = len; |
| offset = addr & (PAGE_SIZE-1); |
| if (bytes > PAGE_SIZE-offset) |
| bytes = PAGE_SIZE-offset; |
| |
| maddr = kmap(page); |
| if (write) { |
| copy_to_user_page(vma, page, addr, |
| maddr + offset, buf, bytes); |
| set_page_dirty_lock(page); |
| } else { |
| copy_from_user_page(vma, page, addr, |
| buf, maddr + offset, bytes); |
| } |
| kunmap(page); |
| page_cache_release(page); |
| } |
| len -= bytes; |
| buf += bytes; |
| addr += bytes; |
| } |
| up_read(&mm->mmap_sem); |
| mmput(mm); |
| |
| return buf - old_buf; |
| } |
| |
| /* |
| * Print the name of a VMA. |
| */ |
| void print_vma_addr(char *prefix, unsigned long ip) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| |
| /* |
| * Do not print if we are in atomic |
| * contexts (in exception stacks, etc.): |
| */ |
| if (preempt_count()) |
| return; |
| |
| down_read(&mm->mmap_sem); |
| vma = find_vma(mm, ip); |
| if (vma && vma->vm_file) { |
| struct file *f = vma->vm_file; |
| char *buf = (char *)__get_free_page(GFP_KERNEL); |
| if (buf) { |
| char *p, *s; |
| |
| p = d_path(&f->f_path, buf, PAGE_SIZE); |
| if (IS_ERR(p)) |
| p = "?"; |
| s = strrchr(p, '/'); |
| if (s) |
| p = s+1; |
| printk("%s%s[%lx+%lx]", prefix, p, |
| vma->vm_start, |
| vma->vm_end - vma->vm_start); |
| free_page((unsigned long)buf); |
| } |
| } |
| up_read(¤t->mm->mmap_sem); |
| } |
| |
| #ifdef CONFIG_PROVE_LOCKING |
| void might_fault(void) |
| { |
| /* |
| * Some code (nfs/sunrpc) uses socket ops on kernel memory while |
| * holding the mmap_sem, this is safe because kernel memory doesn't |
| * get paged out, therefore we'll never actually fault, and the |
| * below annotations will generate false positives. |
| */ |
| if (segment_eq(get_fs(), KERNEL_DS)) |
| return; |
| |
| might_sleep(); |
| /* |
| * it would be nicer only to annotate paths which are not under |
| * pagefault_disable, however that requires a larger audit and |
| * providing helpers like get_user_atomic. |
| */ |
| if (!in_atomic() && current->mm) |
| might_lock_read(¤t->mm->mmap_sem); |
| } |
| EXPORT_SYMBOL(might_fault); |
| #endif |