diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 3051 |
1 files changed, 3051 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c new file mode 100644 index 0000000..fe2257f --- /dev/null +++ b/mm/memory.c @@ -0,0 +1,3051 @@ +/* + * linux/mm/memory.c + * + * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds + */ + +/* + * demand-loading started 01.12.91 - seems it is high on the list of + * things wanted, and it should be easy to implement. - Linus + */ + +/* + * Ok, demand-loading was easy, shared pages a little bit tricker. Shared + * pages started 02.12.91, seems to work. - Linus. + * + * Tested sharing by executing about 30 /bin/sh: under the old kernel it + * would have taken more than the 6M I have free, but it worked well as + * far as I could see. + * + * Also corrected some "invalidate()"s - I wasn't doing enough of them. + */ + +/* + * Real VM (paging to/from disk) started 18.12.91. Much more work and + * thought has to go into this. Oh, well.. + * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. + * Found it. Everything seems to work now. + * 20.12.91 - Ok, making the swap-device changeable like the root. + */ + +/* + * 05.04.94 - Multi-page memory management added for v1.1. + * Idea by Alex Bligh (alex@cconcepts.co.uk) + * + * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG + * (Gerhard.Wichert@pdb.siemens.de) + * + * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) + */ + +#include <linux/kernel_stat.h> +#include <linux/mm.h> +#include <linux/hugetlb.h> +#include <linux/mman.h> +#include <linux/swap.h> +#include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/rmap.h> +#include <linux/module.h> +#include <linux/delayacct.h> +#include <linux/init.h> +#include <linux/writeback.h> +#include <linux/memcontrol.h> +#include <linux/mmu_notifier.h> + +#include <asm/pgalloc.h> +#include <asm/uaccess.h> +#include <asm/tlb.h> +#include <asm/tlbflush.h> +#include <asm/pgtable.h> + +#include <linux/swapops.h> +#include <linux/elf.h> + +#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); + + +/* + * 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) +{ + pgtable_t token = pmd_pgtable(*pmd); + pmd_clear(pmd); + pte_free_tlb(tlb, token); + tlb->mm->nr_ptes--; +} + +static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, + unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) +{ + pmd_t *pmd; + unsigned long next; + unsigned long start; + + start = addr; + pmd = pmd_offset(pud, addr); + do { + next = pmd_addr_end(addr, end); + if (pmd_none_or_clear_bad(pmd)) + continue; + free_pte_range(tlb, pmd); + } while (pmd++, addr = next, addr != end); + + start &= PUD_MASK; + if (start < floor) + return; + if (ceiling) { + ceiling &= PUD_MASK; + if (!ceiling) + return; + } + if (end - 1 > ceiling - 1) + return; + + pmd = pmd_offset(pud, start); + pud_clear(pud); + pmd_free_tlb(tlb, pmd); +} + +static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, + unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) +{ + pud_t *pud; + unsigned long next; + unsigned long start; + + start = addr; + pud = pud_offset(pgd, addr); + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(pud)) + continue; + free_pmd_range(tlb, pud, addr, next, floor, ceiling); + } while (pud++, addr = next, addr != end); + + start &= PGDIR_MASK; + if (start < floor) + return; + if (ceiling) { + ceiling &= PGDIR_MASK; + if (!ceiling) + return; + } + if (end - 1 > ceiling - 1) + return; + + pud = pud_offset(pgd, start); + pgd_clear(pgd); + pud_free_tlb(tlb, pud); +} + +/* + * This function frees user-level page tables of a process. + * + * Must be called with pagetable lock held. + */ +void free_pgd_range(struct mmu_gather *tlb, + unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) +{ + pgd_t *pgd; + unsigned long next; + unsigned long start; + + /* + * The next few lines have given us lots of grief... + * + * Why are we testing PMD* at this top level? Because often + * there will be no work to do at all, and we'd prefer not to + * go all the way down to the bottom just to discover that. + * + * Why all these "- 1"s? Because 0 represents both the bottom + * of the address space and the top of it (using -1 for the + * top wouldn't help much: the masks would do the wrong thing). + * The rule is that addr 0 and floor 0 refer to the bottom of + * the address space, but end 0 and ceiling 0 refer to the top + * Comparisons need to use "end - 1" and "ceiling - 1" (though + * that end 0 case should be mythical). + * + * Wherever addr is brought up or ceiling brought down, we must + * be careful to reject "the opposite 0" before it confuses the + * subsequent tests. But what about where end is brought down + * by PMD_SIZE below? no, end can't go down to 0 there. + * + * Whereas we round start (addr) and ceiling down, by different + * masks at different levels, in order to test whether a table + * now has no other vmas using it, so can be freed, we don't + * bother to round floor or end up - the tests don't need that. + */ + + addr &= PMD_MASK; + if (addr < floor) { + addr += PMD_SIZE; + if (!addr) + return; + } + if (ceiling) { + ceiling &= PMD_MASK; + if (!ceiling) + return; + } + if (end - 1 > ceiling - 1) + end -= PMD_SIZE; + if (addr > end - 1) + return; + + start = addr; + pgd = pgd_offset(tlb->mm, addr); + do { + next = pgd_addr_end(addr, end); + if (pgd_none_or_clear_bad(pgd)) + continue; + free_pud_range(tlb, pgd, addr, next, floor, ceiling); + } while (pgd++, addr = next, addr != end); +} + +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, pte_t pte, + unsigned long vaddr) +{ + printk(KERN_ERR "Bad pte = %08llx, process = %s, " + "vm_flags = %lx, vaddr = %lx\n", + (long long)pte_val(pte), + (vma->vm_mm == current->mm ? current->comm : "???"), + vma->vm_flags, vaddr); + dump_stack(); +} + +static inline int is_cow_mapping(unsigned int flags) +{ + return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; +} + +/* + * 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; + + if (HAVE_PTE_SPECIAL) { + if (likely(!pte_special(pte))) { + VM_BUG_ON(!pfn_valid(pte_pfn(pte))); + return pte_page(pte); + } + VM_BUG_ON(!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))); + return NULL; + } + + /* !HAVE_PTE_SPECIAL case follows: */ + + pfn = pte_pfn(pte); + + 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; + } + } + + VM_BUG_ON(!pfn_valid(pfn)); + + /* + * 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, vma, addr); + 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); + + /* + * 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)) + SetPageReferenced(page); + file_rss--; + } + page_remove_rmap(page, vma); + tlb_remove_page(tlb, page); + continue; + } + /* + * If details->check_mapping, we leave swap entries; + * if details->nonlinear_vma, we leave file entries. + */ + if (unlikely(details)) + continue; + if (!pte_file(ptent)) + free_swap_and_cache(pte_to_swp_entry(ptent)); + pte_clear_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; + + 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)) + goto bad_page; + + if (flags & FOLL_GET) + get_page(page); + if (flags & FOLL_TOUCH) { + if ((flags & FOLL_WRITE) && + !pte_dirty(pte) && !PageDirty(page)) + set_page_dirty(page); + 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; + /* Fall through to ZERO_PAGE handling */ +no_page_table: + /* + * When core dumping an enormous anonymous area that nobody + * has touched so far, we don't want to allocate page tables. + */ + if (flags & FOLL_ANON) { + page = ZERO_PAGE(0); + if (flags & FOLL_GET) + get_page(page); + BUG_ON(flags & FOLL_WRITE); + } + return page; +} + +/* Can we do the FOLL_ANON optimization? */ +static inline int use_zero_page(struct vm_area_struct *vma) +{ + /* + * We don't want to optimize FOLL_ANON for make_pages_present() + * when it tries to page in a VM_LOCKED region. As to VM_SHARED, + * we want to get the page from the page tables to make sure + * that we serialize and update with any other user of that + * mapping. + */ + if (vma->vm_flags & (VM_LOCKED | VM_SHARED)) + return 0; + /* + * And if we have a fault routine, it's not an anonymous region. + */ + return !vma->vm_ops || !vma->vm_ops->fault; +} + + + +int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, int len, int flags, + struct page **pages, struct vm_area_struct **vmas) +{ + int i; + unsigned int vm_flags = 0; + int write = !!(flags & GUP_FLAGS_WRITE); + int force = !!(flags & GUP_FLAGS_FORCE); + int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS); + + if (len <= 0) + return 0; + /* + * Require read or write permissions. + * If 'force' is set, we only require the "MAY" flags. + */ + vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); + vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); + i = 0; + + do { + struct vm_area_struct *vma; + unsigned int foll_flags; + + 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 (!ignore && 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; + len--; + continue; + } + + if (!vma || + (vma->vm_flags & (VM_IO | VM_PFNMAP)) || + (!ignore && !(vm_flags & vma->vm_flags))) + return i ? : -EFAULT; + + if (is_vm_hugetlb_page(vma)) { + i = follow_hugetlb_page(mm, vma, pages, vmas, + &start, &len, i, write); + continue; + } + + foll_flags = FOLL_TOUCH; + if (pages) + foll_flags |= FOLL_GET; + if (!write && use_zero_page(vma)) + foll_flags |= FOLL_ANON; + + do { + struct page *page; + + /* + * If tsk is ooming, cut off its access to large memory + * allocations. It has a pending SIGKILL, but it can't + * be processed until returning to user space. + */ + if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE))) + return i ? i : -ENOMEM; + + if (write) + foll_flags |= FOLL_WRITE; + + cond_resched(); + while (!(page = follow_page(vma, start, foll_flags))) { + int ret; + ret = handle_mm_fault(mm, vma, start, + foll_flags & FOLL_WRITE); + 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. + */ + if (ret & VM_FAULT_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; + len--; + } while (len && start < vma->vm_end); + } while (len); + return i; +} + +int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, int len, int write, int force, + struct page **pages, struct vm_area_struct **vmas) +{ + int flags = 0; + + if (write) + flags |= GUP_FLAGS_WRITE; + if (force) + flags |= GUP_FLAGS_FORCE; + + return __get_user_pages(tsk, mm, + start, len, flags, + pages, vmas); +} + +EXPORT_SYMBOL(get_user_pages); + +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) +{ + /* + * 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; + return insert_pfn(vma, addr, pfn, vma->vm_page_prot); +} +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 (!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 (is_cow_mapping(vma->vm_flags)) { + if (addr != vma->vm_start || end != vma->vm_end) + return -EINVAL; + vma->vm_pgoff = pfn; + } + + vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; + + 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); + 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)); + + token = pmd_pgtable(*pmd); + + do { + err = fn(pte, token, addr, data); + if (err) + break; + } while (pte++, addr += PAGE_SIZE, addr != end); + + 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)) { + if (trylock_page(old_page)) { + reuse = can_share_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) { + /* + * 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); + + if (vma->vm_ops->page_mkwrite(vma, old_page) < 0) + goto unwritable_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); + page_cache_release(old_page); + if (!pte_same(*page_table, orig_pte)) + 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; + VM_BUG_ON(old_page == ZERO_PAGE(0)); + new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); + if (!new_page) + goto oom; + /* + * 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); + } + cow_user_page(new_page, old_page, address, vma); + __SetPageUptodate(new_page); + + if (mem_cgroup_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_notify(vma, address, page_table); + SetPageSwapBacked(new_page); + lru_cache_add_active_or_unevictable(new_page, vma); + page_add_new_anon_rmap(new_page, vma, address); + +//TODO: is this safe? do_anonymous_page() does it this way. + set_pte_at(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, vma); + } + + /* 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) { + if (vma->vm_file) + file_update_time(vma->vm_file); + + /* + * 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. + */ + wait_on_page_locked(dirty_page); + set_page_dirty_balance(dirty_page, page_mkwrite); + put_page(dirty_page); + } + return ret; +oom_free_new: + page_cache_release(new_page); +oom: + if (old_page) + page_cache_release(old_page); + return VM_FAULT_OOM; + +unwritable_page: + page_cache_release(old_page); + return VM_FAULT_SIGBUS; +} + +/* + * 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 && 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 || !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, + int write_access, pte_t orig_pte) +{ + spinlock_t *ptl; + struct page *page; + swp_entry_t entry; + pte_t pte; + 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(); /* 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); + } + + mark_page_accessed(page); + + lock_page(page); + delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + + if (mem_cgroup_charge(page, mm, GFP_KERNEL)) { + ret = VM_FAULT_OOM; + unlock_page(page); + goto out; + } + + /* + * 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. */ + + inc_mm_counter(mm, anon_rss); + pte = mk_pte(page, vma->vm_page_prot); + if (write_access && can_share_swap_page(page)) { + pte = maybe_mkwrite(pte_mkdirty(pte), vma); + write_access = 0; + } + + flush_icache_page(vma, page); + set_pte_at(mm, address, page_table, pte); + page_add_anon_rmap(page, vma, address); + + swap_free(entry); + if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) + remove_exclusive_swap_page(page); + unlock_page(page); + + if (write_access) { + 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_uncharge_page(page); + pte_unmap_unlock(page_table, ptl); + 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, + int write_access) +{ + struct page *page; + spinlock_t *ptl; + pte_t entry; + + /* 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_charge(page, mm, GFP_KERNEL)) + goto oom_free_page; + + entry = mk_pte(page, vma->vm_page_prot); + entry = maybe_mkwrite(pte_mkdirty(entry), vma); + + page_table = pte_offset_map_lock(mm, pmd, address, &ptl); + if (!pte_none(*page_table)) + goto release; + inc_mm_counter(mm, anon_rss); + SetPageSwapBacked(page); + lru_cache_add_active_or_unevictable(page, vma); + page_add_new_anon_rmap(page, vma, address); + 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_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) { + unlock_page(page); + if (vma->vm_ops->page_mkwrite(vma, page) < 0) { + ret = VM_FAULT_SIGBUS; + anon = 1; /* no anon but release vmf.page */ + goto out_unlocked; + } + lock_page(page); + /* + * XXX: this is not quite right (racy vs + * invalidate) to unlock and relock the page + * like this, however a better fix requires + * reworking page_mkwrite locking API, which + * is better done later. + */ + if (!page->mapping) { + ret = 0; + anon = 1; /* no anon but release vmf.page */ + goto out; + } + 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 write_access is true, we either now have + * an exclusive copy of the page, or this is a shared mapping, + * so we can make it writable and dirty to avoid having to + * handle that later. + */ + /* Only go through if we didn't race with anybody else... */ + if (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); + SetPageSwapBacked(page); + lru_cache_add_active_or_unevictable(page, vma); + 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); + } + } +//TODO: is this safe? do_anonymous_page() does it this way. + 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: + unlock_page(vmf.page); +out_unlocked: + if (anon) + page_cache_release(vmf.page); + else if (dirty_page) { + if (vma->vm_file) + file_update_time(vma->vm_file); + + set_page_dirty_balance(dirty_page, page_mkwrite); + put_page(dirty_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, + int write_access, pte_t orig_pte) +{ + pgoff_t pgoff = (((address & PAGE_MASK) + - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; + unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0); + + 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, + int write_access, pte_t orig_pte) +{ + unsigned int flags = FAULT_FLAG_NONLINEAR | + (write_access ? FAULT_FLAG_WRITE : 0); + pgoff_t pgoff; + + if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) + return 0; + + if (unlikely(!(vma->vm_flags & VM_NONLINEAR) || + !(vma->vm_flags & VM_CAN_NONLINEAR))) { + /* + * Page table corrupted: show pte and kill process. + */ + print_bad_pte(vma, orig_pte, address); + 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, int write_access) +{ + 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, write_access, entry); + } + return do_anonymous_page(mm, vma, address, + pte, pmd, write_access); + } + if (pte_file(entry)) + return do_nonlinear_fault(mm, vma, address, + pte, pmd, write_access, entry); + return do_swap_page(mm, vma, address, + pte, pmd, write_access, entry); + } + + ptl = pte_lockptr(mm, pmd); + spin_lock(ptl); + if (unlikely(!pte_same(*pte, entry))) + goto unlock; + if (write_access) { + 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, write_access)) { + 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 (write_access) + 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, int write_access) +{ + 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, write_access); + + 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, write_access); +} + +#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 */ + +#ifdef CONFIG_HAVE_IOREMAP_PROT +static resource_size_t follow_phys(struct vm_area_struct *vma, + unsigned long address, unsigned int flags, + unsigned long *prot) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *ptep, pte; + spinlock_t *ptl; + resource_size_t phys_addr = 0; + struct mm_struct *mm = vma->vm_mm; + + VM_BUG_ON(!(vma->vm_flags & (VM_IO | VM_PFNMAP))); + + 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) || unlikely(pud_bad(*pud))) + goto no_page_table; + + pmd = pmd_offset(pud, address); + if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) + goto no_page_table; + + /* We cannot handle huge page PFN maps. Luckily they don't exist. */ + if (pmd_huge(*pmd)) + goto no_page_table; + + ptep = pte_offset_map_lock(mm, pmd, address, &ptl); + if (!ptep) + goto out; + + pte = *ptep; + if (!pte_present(pte)) + goto unlock; + if ((flags & FOLL_WRITE) && !pte_write(pte)) + goto unlock; + phys_addr = pte_pfn(pte); + phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */ + + *prot = pgprot_val(pte_pgprot(pte)); + +unlock: + pte_unmap_unlock(ptep, ptl); +out: + return phys_addr; +no_page_table: + return 0; +} + +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 *maddr; + int offset = addr & (PAGE_SIZE-1); + + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) + return -EINVAL; + + phys_addr = follow_phys(vma, addr, write, &prot); + + if (!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); +} |
