7a36a752d0
get_user_pages() must not return the error when i != 0. When pages != NULL we have i get_page()'ed pages. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2897 lines
78 KiB
C
2897 lines
78 KiB
C
/*
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* linux/mm/memory.c
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*/
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/*
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* demand-loading started 01.12.91 - seems it is high on the list of
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* things wanted, and it should be easy to implement. - Linus
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*/
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/*
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* Ok, demand-loading was easy, shared pages a little bit tricker. Shared
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* pages started 02.12.91, seems to work. - Linus.
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*
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* Tested sharing by executing about 30 /bin/sh: under the old kernel it
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* would have taken more than the 6M I have free, but it worked well as
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* far as I could see.
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*
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* Also corrected some "invalidate()"s - I wasn't doing enough of them.
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*/
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/*
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* Real VM (paging to/from disk) started 18.12.91. Much more work and
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* thought has to go into this. Oh, well..
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* 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
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* Found it. Everything seems to work now.
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* 20.12.91 - Ok, making the swap-device changeable like the root.
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*/
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/*
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* 05.04.94 - Multi-page memory management added for v1.1.
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* Idea by Alex Bligh (alex@cconcepts.co.uk)
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*
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* 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
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* (Gerhard.Wichert@pdb.siemens.de)
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*
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* Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
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*/
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#include <linux/kernel_stat.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/mman.h>
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#include <linux/swap.h>
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#include <linux/highmem.h>
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#include <linux/pagemap.h>
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#include <linux/rmap.h>
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#include <linux/module.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/writeback.h>
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#include <linux/memcontrol.h>
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#include <asm/pgalloc.h>
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#include <asm/uaccess.h>
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#include <asm/tlb.h>
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#include <asm/tlbflush.h>
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#include <asm/pgtable.h>
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#include <linux/swapops.h>
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#include <linux/elf.h>
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#ifndef CONFIG_NEED_MULTIPLE_NODES
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/* use the per-pgdat data instead for discontigmem - mbligh */
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unsigned long max_mapnr;
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struct page *mem_map;
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EXPORT_SYMBOL(max_mapnr);
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EXPORT_SYMBOL(mem_map);
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#endif
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unsigned long num_physpages;
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/*
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* A number of key systems in x86 including ioremap() rely on the assumption
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* that high_memory defines the upper bound on direct map memory, then end
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* of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
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* highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
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* and ZONE_HIGHMEM.
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*/
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void * high_memory;
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EXPORT_SYMBOL(num_physpages);
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EXPORT_SYMBOL(high_memory);
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/*
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* Randomize the address space (stacks, mmaps, brk, etc.).
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*
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* ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
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* as ancient (libc5 based) binaries can segfault. )
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*/
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int randomize_va_space __read_mostly =
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#ifdef CONFIG_COMPAT_BRK
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1;
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#else
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2;
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#endif
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static int __init disable_randmaps(char *s)
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{
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randomize_va_space = 0;
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return 1;
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}
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__setup("norandmaps", disable_randmaps);
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|
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/*
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* If a p?d_bad entry is found while walking page tables, report
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* the error, before resetting entry to p?d_none. Usually (but
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* very seldom) called out from the p?d_none_or_clear_bad macros.
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*/
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void pgd_clear_bad(pgd_t *pgd)
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{
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pgd_ERROR(*pgd);
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pgd_clear(pgd);
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}
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void pud_clear_bad(pud_t *pud)
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{
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pud_ERROR(*pud);
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pud_clear(pud);
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}
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void pmd_clear_bad(pmd_t *pmd)
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{
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pmd_ERROR(*pmd);
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pmd_clear(pmd);
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}
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/*
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* Note: this doesn't free the actual pages themselves. That
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* has been handled earlier when unmapping all the memory regions.
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*/
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static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
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{
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pgtable_t token = pmd_pgtable(*pmd);
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pmd_clear(pmd);
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pte_free_tlb(tlb, token);
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tlb->mm->nr_ptes--;
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}
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static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
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unsigned long addr, unsigned long end,
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unsigned long floor, unsigned long ceiling)
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{
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pmd_t *pmd;
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unsigned long next;
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unsigned long start;
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start = addr;
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pmd = pmd_offset(pud, addr);
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do {
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next = pmd_addr_end(addr, end);
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if (pmd_none_or_clear_bad(pmd))
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continue;
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free_pte_range(tlb, pmd);
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} while (pmd++, addr = next, addr != end);
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start &= PUD_MASK;
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if (start < floor)
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return;
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if (ceiling) {
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ceiling &= PUD_MASK;
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if (!ceiling)
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return;
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}
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if (end - 1 > ceiling - 1)
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return;
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pmd = pmd_offset(pud, start);
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pud_clear(pud);
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pmd_free_tlb(tlb, pmd);
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}
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static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
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unsigned long addr, unsigned long end,
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unsigned long floor, unsigned long ceiling)
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{
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pud_t *pud;
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unsigned long next;
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unsigned long start;
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start = addr;
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pud = pud_offset(pgd, addr);
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do {
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next = pud_addr_end(addr, end);
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if (pud_none_or_clear_bad(pud))
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continue;
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free_pmd_range(tlb, pud, addr, next, floor, ceiling);
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} while (pud++, addr = next, addr != end);
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start &= PGDIR_MASK;
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if (start < floor)
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return;
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if (ceiling) {
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ceiling &= PGDIR_MASK;
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if (!ceiling)
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return;
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}
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if (end - 1 > ceiling - 1)
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return;
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pud = pud_offset(pgd, start);
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pgd_clear(pgd);
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pud_free_tlb(tlb, pud);
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}
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/*
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* This function frees user-level page tables of a process.
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*
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* Must be called with pagetable lock held.
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*/
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void free_pgd_range(struct mmu_gather **tlb,
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unsigned long addr, unsigned long end,
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unsigned long floor, unsigned long ceiling)
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{
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pgd_t *pgd;
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unsigned long next;
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unsigned long start;
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/*
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* The next few lines have given us lots of grief...
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*
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* Why are we testing PMD* at this top level? Because often
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* there will be no work to do at all, and we'd prefer not to
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* go all the way down to the bottom just to discover that.
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*
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* Why all these "- 1"s? Because 0 represents both the bottom
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* of the address space and the top of it (using -1 for the
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* top wouldn't help much: the masks would do the wrong thing).
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* The rule is that addr 0 and floor 0 refer to the bottom of
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* the address space, but end 0 and ceiling 0 refer to the top
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* Comparisons need to use "end - 1" and "ceiling - 1" (though
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* that end 0 case should be mythical).
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*
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* Wherever addr is brought up or ceiling brought down, we must
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* be careful to reject "the opposite 0" before it confuses the
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* subsequent tests. But what about where end is brought down
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* by PMD_SIZE below? no, end can't go down to 0 there.
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*
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* Whereas we round start (addr) and ceiling down, by different
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* masks at different levels, in order to test whether a table
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* now has no other vmas using it, so can be freed, we don't
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* bother to round floor or end up - the tests don't need that.
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*/
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addr &= PMD_MASK;
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if (addr < floor) {
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addr += PMD_SIZE;
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if (!addr)
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return;
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}
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if (ceiling) {
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ceiling &= PMD_MASK;
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if (!ceiling)
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return;
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}
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if (end - 1 > ceiling - 1)
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end -= PMD_SIZE;
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if (addr > end - 1)
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return;
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start = addr;
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pgd = pgd_offset((*tlb)->mm, addr);
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do {
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next = pgd_addr_end(addr, end);
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if (pgd_none_or_clear_bad(pgd))
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continue;
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free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
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} while (pgd++, addr = next, addr != end);
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}
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void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
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unsigned long floor, unsigned long ceiling)
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{
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while (vma) {
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struct vm_area_struct *next = vma->vm_next;
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unsigned long addr = vma->vm_start;
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/*
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* Hide vma from rmap and vmtruncate before freeing pgtables
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*/
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anon_vma_unlink(vma);
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unlink_file_vma(vma);
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if (is_vm_hugetlb_page(vma)) {
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hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
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floor, next? next->vm_start: ceiling);
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} else {
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/*
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* Optimization: gather nearby vmas into one call down
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*/
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while (next && next->vm_start <= vma->vm_end + PMD_SIZE
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&& !is_vm_hugetlb_page(next)) {
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vma = next;
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next = vma->vm_next;
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anon_vma_unlink(vma);
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unlink_file_vma(vma);
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}
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free_pgd_range(tlb, addr, vma->vm_end,
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floor, next? next->vm_start: ceiling);
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}
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vma = next;
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}
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}
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int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
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{
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pgtable_t new = pte_alloc_one(mm, address);
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if (!new)
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return -ENOMEM;
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/*
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* Ensure all pte setup (eg. pte page lock and page clearing) are
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* visible before the pte is made visible to other CPUs by being
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* put into page tables.
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*
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* The other side of the story is the pointer chasing in the page
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* table walking code (when walking the page table without locking;
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* ie. most of the time). Fortunately, these data accesses consist
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* of a chain of data-dependent loads, meaning most CPUs (alpha
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* being the notable exception) will already guarantee loads are
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* seen in-order. See the alpha page table accessors for the
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* smp_read_barrier_depends() barriers in page table walking code.
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*/
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smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
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spin_lock(&mm->page_table_lock);
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if (!pmd_present(*pmd)) { /* Has another populated it ? */
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mm->nr_ptes++;
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pmd_populate(mm, pmd, new);
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new = NULL;
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}
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spin_unlock(&mm->page_table_lock);
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if (new)
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pte_free(mm, new);
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return 0;
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}
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|
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int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
|
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{
|
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pte_t *new = pte_alloc_one_kernel(&init_mm, address);
|
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if (!new)
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return -ENOMEM;
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smp_wmb(); /* See comment in __pte_alloc */
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|
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spin_lock(&init_mm.page_table_lock);
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if (!pmd_present(*pmd)) { /* Has another populated it ? */
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pmd_populate_kernel(&init_mm, pmd, new);
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new = NULL;
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}
|
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spin_unlock(&init_mm.page_table_lock);
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if (new)
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pte_free_kernel(&init_mm, new);
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return 0;
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}
|
|
|
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static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
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{
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if (file_rss)
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add_mm_counter(mm, file_rss, file_rss);
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if (anon_rss)
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add_mm_counter(mm, anon_rss, anon_rss);
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}
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|
|
/*
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* This function is called to print an error when a bad pte
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* is found. For example, we might have a PFN-mapped pte in
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* a region that doesn't allow it.
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*
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* The calling function must still handle the error.
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*/
|
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void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
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{
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printk(KERN_ERR "Bad pte = %08llx, process = %s, "
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"vm_flags = %lx, vaddr = %lx\n",
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(long long)pte_val(pte),
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(vma->vm_mm == current->mm ? current->comm : "???"),
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vma->vm_flags, vaddr);
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dump_stack();
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}
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|
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static inline int is_cow_mapping(unsigned int flags)
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{
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return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
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}
|
|
|
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/*
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* vm_normal_page -- This function gets the "struct page" associated with a pte.
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*
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* "Special" mappings do not wish to be associated with a "struct page" (either
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* it doesn't exist, or it exists but they don't want to touch it). In this
|
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* case, NULL is returned here. "Normal" mappings do have a struct page.
|
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*
|
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* There are 2 broad cases. Firstly, an architecture may define a pte_special()
|
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* pte bit, in which case this function is trivial. Secondly, an architecture
|
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* may not have a spare pte bit, which requires a more complicated scheme,
|
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* described below.
|
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*
|
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* A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
|
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* special mapping (even if there are underlying and valid "struct pages").
|
|
* COWed pages of a VM_PFNMAP are always normal.
|
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*
|
|
* 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;
|
|
|
|
/*
|
|
* 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);
|
|
|
|
dst_pgd = pgd_offset(dst_mm, addr);
|
|
src_pgd = pgd_offset(src_mm, addr);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none_or_clear_bad(src_pgd))
|
|
continue;
|
|
if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
|
|
vma, addr, next))
|
|
return -ENOMEM;
|
|
} while (dst_pgd++, src_pgd++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static 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;
|
|
|
|
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))) {
|
|
unmap_hugepage_range(vma, start, end);
|
|
zap_work -= (end - start) /
|
|
(HPAGE_SIZE / PAGE_SIZE);
|
|
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:
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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) || 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 or a nopfn routine, it's not an
|
|
* anonymous region.
|
|
*/
|
|
return !vma->vm_ops ||
|
|
(!vma->vm_ops->fault && !vma->vm_ops->nopfn);
|
|
}
|
|
|
|
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
|
|
unsigned long start, int len, int write, int force,
|
|
struct page **pages, struct vm_area_struct **vmas)
|
|
{
|
|
int i;
|
|
unsigned int vm_flags;
|
|
|
|
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;
|
|
if (write) /* user gate pages are read-only */
|
|
return i ? : -EFAULT;
|
|
if (pg > TASK_SIZE)
|
|
pgd = pgd_offset_k(pg);
|
|
else
|
|
pgd = pgd_offset_gate(mm, pg);
|
|
BUG_ON(pgd_none(*pgd));
|
|
pud = pud_offset(pgd, pg);
|
|
BUG_ON(pud_none(*pud));
|
|
pmd = pmd_offset(pud, pg);
|
|
if (pmd_none(*pmd))
|
|
return i ? : -EFAULT;
|
|
pte = pte_offset_map(pmd, pg);
|
|
if (pte_none(*pte)) {
|
|
pte_unmap(pte);
|
|
return i ? : -EFAULT;
|
|
}
|
|
if (pages) {
|
|
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))
|
|
|| !(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;
|
|
}
|
|
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 = mem_cgroup_charge(page, mm, GFP_KERNEL);
|
|
if (retval)
|
|
goto out;
|
|
|
|
retval = -EINVAL;
|
|
if (PageAnon(page))
|
|
goto out_uncharge;
|
|
retval = -ENOMEM;
|
|
flush_dcache_page(page);
|
|
pte = get_locked_pte(mm, addr, &ptl);
|
|
if (!pte)
|
|
goto out_uncharge;
|
|
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_uncharge:
|
|
mem_cgroup_uncharge_page(page);
|
|
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.
|
|
*/
|
|
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;
|
|
|
|
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 end = addr + size;
|
|
int err;
|
|
|
|
BUG_ON(addr >= 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);
|
|
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 (!TestSetPageLocked(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;
|
|
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(vma, address, page_table);
|
|
set_pte_at(mm, address, page_table, entry);
|
|
update_mmu_cache(vma, address, entry);
|
|
lru_cache_add_active(new_page);
|
|
page_add_new_anon_rmap(new_page, vma, address);
|
|
|
|
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);
|
|
}
|
|
|
|
if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
|
|
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
|
|
ret = VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
|
|
mark_page_accessed(page);
|
|
lock_page(page);
|
|
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
|
|
|
|
/*
|
|
* 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())
|
|
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);
|
|
lru_cache_add_active(page);
|
|
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;
|
|
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;
|
|
}
|
|
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;
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
|
|
ret = VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
|
|
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);
|
|
set_pte_at(mm, address, page_table, entry);
|
|
if (anon) {
|
|
inc_mm_counter(mm, anon_rss);
|
|
lru_cache_add_active(page);
|
|
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);
|
|
}
|
|
}
|
|
|
|
/* no need to invalidate: a not-present page won't be cached */
|
|
update_mmu_cache(vma, address, entry);
|
|
} else {
|
|
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);
|
|
}
|
|
|
|
|
|
/*
|
|
* do_no_pfn() tries to create a new page mapping for a page without
|
|
* a struct_page backing it
|
|
*
|
|
* 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 mapped but not yet locked.
|
|
* We return with mmap_sem still held, but pte unmapped and unlocked.
|
|
*
|
|
* It is expected that the ->nopfn handler always returns the same pfn
|
|
* for a given virtual mapping.
|
|
*
|
|
* Mark this `noinline' to prevent it from bloating the main pagefault code.
|
|
*/
|
|
static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long address, pte_t *page_table, pmd_t *pmd,
|
|
int write_access)
|
|
{
|
|
spinlock_t *ptl;
|
|
pte_t entry;
|
|
unsigned long pfn;
|
|
|
|
pte_unmap(page_table);
|
|
BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
|
|
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
|
|
|
|
pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
|
|
|
|
BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
|
|
|
|
if (unlikely(pfn == NOPFN_OOM))
|
|
return VM_FAULT_OOM;
|
|
else if (unlikely(pfn == NOPFN_SIGBUS))
|
|
return VM_FAULT_SIGBUS;
|
|
else if (unlikely(pfn == NOPFN_REFAULT))
|
|
return 0;
|
|
|
|
page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
|
|
|
|
/* Only go through if we didn't race with anybody else... */
|
|
if (pte_none(*page_table)) {
|
|
entry = pfn_pte(pfn, vma->vm_page_prot);
|
|
if (write_access)
|
|
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
|
|
set_pte_at(mm, address, page_table, entry);
|
|
}
|
|
pte_unmap_unlock(page_table, ptl);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
if (unlikely(vma->vm_ops->nopfn))
|
|
return do_no_pfn(mm, vma, address, pte,
|
|
pmd, write_access);
|
|
}
|
|
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 -1;
|
|
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 : -1;
|
|
}
|
|
|
|
#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 */
|
|
|
|
/*
|
|
* 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;
|
|
struct page *page;
|
|
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;
|
|
|
|
ret = get_user_pages(tsk, mm, addr, 1,
|
|
write, 1, &page, &vma);
|
|
if (ret <= 0)
|
|
break;
|
|
|
|
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);
|
|
}
|