memory.c 80.7 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

/*
 * demand-loading started 01.12.91 - seems it is high on the list of
 * things wanted, and it should be easy to implement. - Linus
 */

/*
 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
 * pages started 02.12.91, seems to work. - Linus.
 *
 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
 * would have taken more than the 6M I have free, but it worked well as
 * far as I could see.
 *
 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
 */

/*
 * Real VM (paging to/from disk) started 18.12.91. Much more work and
 * thought has to go into this. Oh, well..
 * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
 *		Found it. Everything seems to work now.
 * 20.12.91  -  Ok, making the swap-device changeable like the root.
 */

/*
 * 05.04.94  -  Multi-page memory management added for v1.1.
 * 		Idea by Alex Bligh (alex@cconcepts.co.uk)
 *
 * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
 *		(Gerhard.Wichert@pdb.siemens.de)
 *
 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
 */

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include <linux/module.h>
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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 <linux/mmu_notifier.h>
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#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>

#include <linux/swapops.h>
#include <linux/elf.h>

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#include "internal.h"

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#ifndef CONFIG_NEED_MULTIPLE_NODES
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/* use the per-pgdat data instead for discontigmem - mbligh */
unsigned long max_mapnr;
struct page *mem_map;

EXPORT_SYMBOL(max_mapnr);
EXPORT_SYMBOL(mem_map);
#endif

unsigned long num_physpages;
/*
 * A number of key systems in x86 including ioremap() rely on the assumption
 * that high_memory defines the upper bound on direct map memory, then end
 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
 * and ZONE_HIGHMEM.
 */
void * high_memory;

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);

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/*
 * Randomize the address space (stacks, mmaps, brk, etc.).
 *
 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
 *   as ancient (libc5 based) binaries can segfault. )
 */
int randomize_va_space __read_mostly =
#ifdef CONFIG_COMPAT_BRK
					1;
#else
					2;
#endif
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static int __init disable_randmaps(char *s)
{
	randomize_va_space = 0;
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	return 1;
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}
__setup("norandmaps", disable_randmaps);


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/*
 * If a p?d_bad entry is found while walking page tables, report
 * the error, before resetting entry to p?d_none.  Usually (but
 * very seldom) called out from the p?d_none_or_clear_bad macros.
 */

void pgd_clear_bad(pgd_t *pgd)
{
	pgd_ERROR(*pgd);
	pgd_clear(pgd);
}

void pud_clear_bad(pud_t *pud)
{
	pud_ERROR(*pud);
	pud_clear(pud);
}

void pmd_clear_bad(pmd_t *pmd)
{
	pmd_ERROR(*pmd);
	pmd_clear(pmd);
}

/*
 * Note: this doesn't free the actual pages themselves. That
 * has been handled earlier when unmapping all the memory regions.
 */
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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,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pmd_t *pmd;
	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);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			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;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

	pmd = pmd_offset(pud, start);
	pud_clear(pud);
	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,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pud_t *pud;
	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);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			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;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

	pud = pud_offset(pgd, start);
	pgd_clear(pgd);
	pud_free_tlb(tlb, pud);
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}

/*
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 * This function frees user-level page tables of a process.
 *
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 * Must be called with pagetable lock held.
 */
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void free_pgd_range(struct mmu_gather *tlb,
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			unsigned long addr, unsigned long end,
			unsigned long floor, unsigned long ceiling)
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{
	pgd_t *pgd;
	unsigned long next;
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	unsigned long start;

	/*
	 * The next few lines have given us lots of grief...
	 *
	 * Why are we testing PMD* at this top level?  Because often
	 * there will be no work to do at all, and we'd prefer not to
	 * go all the way down to the bottom just to discover that.
	 *
	 * Why all these "- 1"s?  Because 0 represents both the bottom
	 * of the address space and the top of it (using -1 for the
	 * top wouldn't help much: the masks would do the wrong thing).
	 * The rule is that addr 0 and floor 0 refer to the bottom of
	 * the address space, but end 0 and ceiling 0 refer to the top
	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
	 * that end 0 case should be mythical).
	 *
	 * Wherever addr is brought up or ceiling brought down, we must
	 * be careful to reject "the opposite 0" before it confuses the
	 * subsequent tests.  But what about where end is brought down
	 * by PMD_SIZE below? no, end can't go down to 0 there.
	 *
	 * Whereas we round start (addr) and ceiling down, by different
	 * masks at different levels, in order to test whether a table
	 * now has no other vmas using it, so can be freed, we don't
	 * bother to round floor or end up - the tests don't need that.
	 */
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	addr &= PMD_MASK;
	if (addr < floor) {
		addr += PMD_SIZE;
		if (!addr)
			return;
	}
	if (ceiling) {
		ceiling &= PMD_MASK;
		if (!ceiling)
			return;
	}
	if (end - 1 > ceiling - 1)
		end -= PMD_SIZE;
	if (addr > end - 1)
		return;

	start = addr;
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	pgd = pgd_offset(tlb->mm, addr);
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	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			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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{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

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		/*
		 * Hide vma from rmap and vmtruncate before freeing pgtables
		 */
		anon_vma_unlink(vma);
		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 {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			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;
				next = vma->vm_next;
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				anon_vma_unlink(vma);
				unlink_file_vma(vma);
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			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
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		vma = next;
	}
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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)
		return -ENOMEM;

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	/*
	 * Ensure all pte setup (eg. pte page lock and page clearing) are
	 * visible before the pte is made visible to other CPUs by being
	 * put into page tables.
	 *
	 * The other side of the story is the pointer chasing in the page
	 * table walking code (when walking the page table without locking;
	 * ie. most of the time). Fortunately, these data accesses consist
	 * of a chain of data-dependent loads, meaning most CPUs (alpha
	 * being the notable exception) will already guarantee loads are
	 * seen in-order. See the alpha page table accessors for the
	 * smp_read_barrier_depends() barriers in page table walking code.
	 */
	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */

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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++;
		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)
		pte_free(mm, new);
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	return 0;
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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);
	if (!new)
		return -ENOMEM;

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	smp_wmb(); /* See comment in __pte_alloc */

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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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	spin_unlock(&init_mm.page_table_lock);
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	if (new)
		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)
{
	if (file_rss)
		add_mm_counter(mm, file_rss, file_rss);
	if (anon_rss)
		add_mm_counter(mm, anon_rss, anon_rss);
}

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/*
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 * This function is called to print an error when a bad pte
 * is found. For example, we might have a PFN-mapped pte in
 * a region that doesn't allow it.
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 *
 * The calling function must still handle the error.
 */
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static void print_bad_pte(struct vm_area_struct *vma, pte_t pte,
			  unsigned long vaddr)
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{
	printk(KERN_ERR "Bad pte = %08llx, process = %s, "
			"vm_flags = %lx, vaddr = %lx\n",
		(long long)pte_val(pte),
		(vma->vm_mm == current->mm ? current->comm : "???"),
		vma->vm_flags, vaddr);
	dump_stack();
}

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static inline int is_cow_mapping(unsigned int flags)
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

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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
 * it doesn't exist, or it exists but they don't want to touch it). In this
 * case, NULL is returned here. "Normal" mappings do have a struct page.
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 *
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 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 * pte bit, in which case this function is trivial. Secondly, an architecture
 * may not have a spare pte bit, which requires a more complicated scheme,
 * described below.
 *
 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 * special mapping (even if there are underlying and valid "struct pages").
 * COWed pages of a VM_PFNMAP are always normal.
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 *
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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
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 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
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 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
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 * 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).
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 *
 *
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 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
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 *
 * 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.
 *
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 */
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#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)
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{
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	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);
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	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
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			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
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			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
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	}

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	VM_BUG_ON(!pfn_valid(pfn));
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	/*
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	 * NOTE! We still have PageReserved() pages in the page tables.
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	 *
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	 * eg. VDSO mappings can cause them to exist.
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	 */
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out:
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	return pfn_to_page(pfn);
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}

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/*
 * 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.
 */

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static inline void
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copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
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		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
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		unsigned long addr, int *rss)
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{
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	unsigned long vm_flags = vma->vm_flags;
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	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)) {
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			swp_entry_t entry = pte_to_swp_entry(pte);

			swap_duplicate(entry);
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			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
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				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
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				spin_unlock(&mmlist_lock);
			}
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			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);
			}
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		}
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		goto out_set_pte;
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	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
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	if (is_cow_mapping(vm_flags)) {
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		ptep_set_wrprotect(src_mm, addr, src_pte);
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		pte = pte_wrprotect(pte);
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	}

	/*
	 * 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);
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	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
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		page_dup_rmap(page, vma, addr);
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		rss[!!PageAnon(page)]++;
	}
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out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
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}

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;
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	spinlock_t *src_ptl, *dst_ptl;
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	int progress = 0;
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	int rss[2];
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again:
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	rss[1] = rss[0] = 0;
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Hugh Dickins 已提交
567
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
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	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
571
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
572
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
573
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
574 575 576 577 578 579

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
580 581 582
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
583
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
584 585
				break;
		}
L
Linus Torvalds 已提交
586 587 588 589
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
590
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
591 592 593
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

594
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
595
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
596
	pte_unmap_nested(src_pte - 1);
597
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
598 599
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
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Linus Torvalds 已提交
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	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;
A
Andrea Arcangeli 已提交
656
	int ret;
L
Linus Torvalds 已提交
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658 659 660 661 662 663
	/*
	 * 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.
	 */
664
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
665 666 667 668
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
669 670 671
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

A
Andrea Arcangeli 已提交
672 673 674 675 676 677 678 679 680 681
	/*
	 * We need to invalidate the secondary MMU mappings only when
	 * there could be a permission downgrade on the ptes of the
	 * parent mm. And a permission downgrade will only happen if
	 * is_cow_mapping() returns true.
	 */
	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_start(src_mm, addr, end);

	ret = 0;
L
Linus Torvalds 已提交
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	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;
A
Andrea Arcangeli 已提交
688 689 690 691 692
		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
					    vma, addr, next))) {
			ret = -ENOMEM;
			break;
		}
L
Linus Torvalds 已提交
693
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
694 695 696 697 698

	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_end(src_mm,
						  vma->vm_start, end);
	return ret;
L
Linus Torvalds 已提交
699 700
}

701
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
702
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
703
				unsigned long addr, unsigned long end,
704
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
705
{
N
Nick Piggin 已提交
706
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
707
	pte_t *pte;
708
	spinlock_t *ptl;
709 710
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
711

712
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
713
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
714 715
	do {
		pte_t ptent = *pte;
716 717
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
718
			continue;
719
		}
720 721 722

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
723
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
724
			struct page *page;
725

726
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744
			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;
			}
N
Nick Piggin 已提交
745
			ptent = ptep_get_and_clear_full(mm, addr, pte,
746
							tlb->fullmm);
L
Linus Torvalds 已提交
747 748 749 750 751 752
			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)
N
Nick Piggin 已提交
753
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
754 755
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
756
				anon_rss--;
757 758 759 760
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
761
					SetPageReferenced(page);
H
Hugh Dickins 已提交
762
				file_rss--;
763
			}
N
Nick Piggin 已提交
764
			page_remove_rmap(page, vma);
L
Linus Torvalds 已提交
765 766 767 768 769 770 771 772 773 774 775
			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));
776
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
777
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
778

H
Hugh Dickins 已提交
779
	add_mm_rss(mm, file_rss, anon_rss);
780
	arch_leave_lazy_mmu_mode();
781
	pte_unmap_unlock(pte - 1, ptl);
782 783

	return addr;
L
Linus Torvalds 已提交
784 785
}

786
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
787
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
788
				unsigned long addr, unsigned long end,
789
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
790 791 792 793 794 795 796
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
797 798
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
799
			continue;
800 801 802 803 804 805
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
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}

808
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
809
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
810
				unsigned long addr, unsigned long end,
811
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
812 813 814 815 816 817 818
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
819 820
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
821
			continue;
822 823 824 825 826 827
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
828 829
}

830 831
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
832
				unsigned long addr, unsigned long end,
833
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
834 835 836 837 838 839 840 841 842 843 844 845
{
	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);
846 847
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
848
			continue;
849 850 851 852
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
L
Linus Torvalds 已提交
853
	tlb_end_vma(tlb, vma);
854 855

	return addr;
L
Linus Torvalds 已提交
856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873
}

#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
 *
874
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
875
 *
876
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
877
 *
878 879
 * 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
L
Linus Torvalds 已提交
880 881 882 883 884 885 886 887 888 889 890
 * 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.
 */
891
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
892 893 894 895
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
896
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
897 898
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
899
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
900
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
901
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
902
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
903

A
Andrea Arcangeli 已提交
904
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923
	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;
			}

924
			if (unlikely(is_vm_hugetlb_page(vma))) {
925 926 927 928 929 930 931 932 933 934 935 936 937 938
				/*
				 * It is undesirable to test vma->vm_file as it
				 * should be non-null for valid hugetlb area.
				 * However, vm_file will be NULL in the error
				 * cleanup path of do_mmap_pgoff. When
				 * hugetlbfs ->mmap method fails,
				 * do_mmap_pgoff() nullifies vma->vm_file
				 * before calling this function to clean up.
				 * Since no pte has actually been setup, it is
				 * safe to do nothing in this case.
				 */
				if (vma->vm_file) {
					unmap_hugepage_range(vma, start, end, NULL);
					zap_work -= (end - start) /
939
					pages_per_huge_page(hstate_vma(vma));
940 941
				}

942 943 944 945 946 947 948 949
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

			if (zap_work > 0) {
				BUG_ON(start != end);
				break;
L
Linus Torvalds 已提交
950 951 952 953 954
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
955
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
956
				if (i_mmap_lock) {
957
					*tlbp = NULL;
L
Linus Torvalds 已提交
958 959 960 961 962
					goto out;
				}
				cond_resched();
			}

963
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
964
			tlb_start_valid = 0;
965
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
966 967 968
		}
	}
out:
A
Andrea Arcangeli 已提交
969
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
970
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
971 972 973 974 975 976 977 978 979
}

/**
 * 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
 */
980
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
981 982 983 984 985 986 987 988 989
		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);
990
	update_hiwater_rss(mm);
991 992 993
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
994
	return end;
L
Linus Torvalds 已提交
995 996
}

997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019
/**
 * zap_vma_ptes - remove ptes mapping the vma
 * @vma: vm_area_struct holding ptes to be zapped
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 *
 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
 *
 * The entire address range must be fully contained within the vma.
 *
 * Returns 0 if successful.
 */
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
		unsigned long size)
{
	if (address < vma->vm_start || address + size > vma->vm_end ||
	    		!(vma->vm_flags & VM_PFNMAP))
		return -1;
	zap_page_range(vma, address, size, NULL);
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

L
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1020 1021 1022
/*
 * Do a quick page-table lookup for a single page.
 */
1023
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1024
			unsigned int flags)
L
Linus Torvalds 已提交
1025 1026 1027 1028 1029
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1030
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1031
	struct page *page;
1032
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1033

1034 1035 1036 1037 1038
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
Linus Torvalds 已提交
1039

1040
	page = NULL;
L
Linus Torvalds 已提交
1041 1042
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1043
		goto no_page_table;
L
Linus Torvalds 已提交
1044 1045

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1046
	if (pud_none(*pud))
1047
		goto no_page_table;
A
Andi Kleen 已提交
1048 1049 1050 1051 1052 1053 1054 1055
	if (pud_huge(*pud)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
		goto out;
	}
	if (unlikely(pud_bad(*pud)))
		goto no_page_table;

L
Linus Torvalds 已提交
1056
	pmd = pmd_offset(pud, address);
1057
	if (pmd_none(*pmd))
1058 1059 1060 1061
		goto no_page_table;
	if (pmd_huge(*pmd)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
1062
		goto out;
1063
	}
1064 1065 1066
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1067
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1068 1069

	pte = *ptep;
1070
	if (!pte_present(pte))
1071
		goto no_page;
1072 1073
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
1074 1075
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
1076
		goto bad_page;
L
Linus Torvalds 已提交
1077

1078 1079 1080 1081 1082 1083 1084 1085 1086 1087
	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);
L
Linus Torvalds 已提交
1088
out:
1089
	return page;
L
Linus Torvalds 已提交
1090

1091 1092 1093 1094 1095 1096 1097 1098 1099
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 */
1100 1101 1102 1103 1104 1105
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) {
N
Nick Piggin 已提交
1106
		page = ZERO_PAGE(0);
1107 1108 1109 1110 1111
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1112 1113
}

1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126
/* 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;
	/*
N
Nick Piggin 已提交
1127
	 * And if we have a fault routine, it's not an anonymous region.
1128
	 */
N
Nick Piggin 已提交
1129
	return !vma->vm_ops || !vma->vm_ops->fault;
1130 1131
}

L
Linus Torvalds 已提交
1132 1133 1134 1135 1136
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;
1137
	unsigned int vm_flags;
L
Linus Torvalds 已提交
1138

1139 1140
	if (len <= 0)
		return 0;
L
Linus Torvalds 已提交
1141 1142 1143 1144
	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
1145 1146
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
1147 1148 1149
	i = 0;

	do {
1150 1151
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170

		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);
1171 1172
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1173
			pte = pte_offset_map(pmd, pg);
1174 1175 1176 1177
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1178
			if (pages) {
1179
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1180 1181 1182
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1183 1184 1185 1186 1187 1188 1189 1190 1191 1192
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1193
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1194
				|| !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1195 1196 1197 1198
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1199
						&start, &len, i, write);
L
Linus Torvalds 已提交
1200 1201
			continue;
		}
1202 1203 1204 1205

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
1206
		if (!write && use_zero_page(vma))
1207 1208
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1209
		do {
1210
			struct page *page;
L
Linus Torvalds 已提交
1211

1212 1213 1214 1215 1216 1217
			/*
			 * 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)))
1218
				return i ? i : -ENOMEM;
1219

1220 1221
			if (write)
				foll_flags |= FOLL_WRITE;
1222

1223
			cond_resched();
1224
			while (!(page = follow_page(vma, start, foll_flags))) {
1225
				int ret;
N
Nick Piggin 已提交
1226
				ret = handle_mm_fault(mm, vma, start,
1227
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239
				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++;

1240
				/*
N
Nick Piggin 已提交
1241 1242 1243 1244 1245
				 * 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.
1246 1247
				 */
				if (ret & VM_FAULT_WRITE)
1248
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1249

1250
				cond_resched();
L
Linus Torvalds 已提交
1251
			}
1252 1253
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1254
			if (pages) {
1255
				pages[i] = page;
1256

1257
				flush_anon_page(vma, page, start);
1258
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1259 1260 1261 1262 1263 1264
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1265 1266
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1267 1268 1269 1270
	return i;
}
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1271 1272
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1273 1274 1275 1276
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1277
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1278 1279 1280 1281 1282 1283
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1284 1285 1286 1287 1288 1289 1290
/*
 * 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.
 */
N
Nick Piggin 已提交
1291 1292
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1293
{
N
Nick Piggin 已提交
1294
	struct mm_struct *mm = vma->vm_mm;
1295
	int retval;
1296
	pte_t *pte;
1297 1298
	spinlock_t *ptl;

1299
	retval = mem_cgroup_charge(page, mm, GFP_KERNEL);
1300 1301
	if (retval)
		goto out;
1302 1303

	retval = -EINVAL;
1304
	if (PageAnon(page))
1305
		goto out_uncharge;
1306 1307
	retval = -ENOMEM;
	flush_dcache_page(page);
1308
	pte = get_locked_pte(mm, addr, &ptl);
1309
	if (!pte)
1310
		goto out_uncharge;
1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321
	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;
1322 1323
	pte_unmap_unlock(pte, ptl);
	return retval;
1324 1325
out_unlock:
	pte_unmap_unlock(pte, ptl);
1326 1327
out_uncharge:
	mem_cgroup_uncharge_page(page);
1328 1329 1330 1331
out:
	return retval;
}

1332 1333 1334 1335 1336 1337
/**
 * 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
 *
1338 1339 1340 1341 1342 1343
 * 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
N
Nick Piggin 已提交
1344
 * (see split_page()).
1345 1346 1347 1348 1349 1350 1351 1352 1353
 *
 * 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.
 */
N
Nick Piggin 已提交
1354 1355
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1356 1357 1358 1359 1360
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1361
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1362
	return insert_page(vma, addr, page, vma->vm_page_prot);
1363
}
1364
EXPORT_SYMBOL(vm_insert_page);
1365

N
Nick Piggin 已提交
1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393
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;
}

N
Nick Piggin 已提交
1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404
/**
 * 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.
N
Nick Piggin 已提交
1405 1406 1407 1408 1409
 *
 * vma cannot be a COW mapping.
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
N
Nick Piggin 已提交
1410 1411
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1412
			unsigned long pfn)
N
Nick Piggin 已提交
1413
{
N
Nick Piggin 已提交
1414 1415 1416 1417 1418 1419
	/*
	 * 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.
	 */
J
Jared Hulbert 已提交
1420 1421 1422 1423 1424
	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));
N
Nick Piggin 已提交
1425

N
Nick Piggin 已提交
1426 1427 1428 1429 1430
	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);
N
Nick Piggin 已提交
1431

N
Nick Piggin 已提交
1432 1433 1434 1435
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn)
{
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1436

N
Nick Piggin 已提交
1437 1438
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1439

N
Nick Piggin 已提交
1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452
	/*
	 * 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);
N
Nick Piggin 已提交
1453
}
N
Nick Piggin 已提交
1454
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1455

L
Linus Torvalds 已提交
1456 1457 1458 1459 1460 1461 1462 1463 1464 1465
/*
 * 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;
H
Hugh Dickins 已提交
1466
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1467

H
Hugh Dickins 已提交
1468
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1469 1470
	if (!pte)
		return -ENOMEM;
1471
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1472 1473
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1474
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1475 1476
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1477
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1478
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521
	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;
}

1522 1523 1524 1525 1526 1527 1528 1529 1530 1531
/**
 * 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.
 */
L
Linus Torvalds 已提交
1532 1533 1534 1535 1536
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;
1537
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1538 1539 1540 1541 1542 1543 1544 1545
	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).
H
Hugh Dickins 已提交
1546 1547 1548 1549 1550
	 *   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.
1551 1552 1553
	 *   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.
L
Linus Torvalds 已提交
1554 1555 1556 1557
	 *
	 * 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".
L
Linus Torvalds 已提交
1558
	 */
1559
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1560
		if (addr != vma->vm_start || end != vma->vm_end)
1561
			return -EINVAL;
L
Linus Torvalds 已提交
1562 1563 1564
		vma->vm_pgoff = pfn;
	}

1565
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581

	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);

1582 1583 1584 1585 1586 1587
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;
1588
	pgtable_t token;
1589
	spinlock_t *uninitialized_var(ptl);
1590 1591 1592 1593 1594 1595 1596 1597 1598

	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));

1599
	token = pmd_pgtable(*pmd);
1600 1601

	do {
1602
		err = fn(pte, token, addr, data);
1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619
		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;

A
Andi Kleen 已提交
1620 1621
	BUG_ON(pud_huge(*pud));

1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662
	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;
A
Andrea Arcangeli 已提交
1663
	unsigned long start = addr, end = addr + size;
1664 1665 1666
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1667
	mmu_notifier_invalidate_range_start(mm, start, end);
1668 1669 1670 1671 1672 1673 1674
	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);
A
Andrea Arcangeli 已提交
1675
	mmu_notifier_invalidate_range_end(mm, start, end);
1676 1677 1678 1679
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1680 1681 1682 1683 1684 1685 1686 1687 1688
/*
 * 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).
 */
H
Hugh Dickins 已提交
1689
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1690 1691 1692 1693 1694
				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)) {
H
Hugh Dickins 已提交
1695 1696
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1697
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1698
		spin_unlock(ptl);
1699 1700 1701 1702 1703 1704
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717
/*
 * 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;
}

1718
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1719 1720 1721 1722 1723 1724 1725 1726 1727
{
	/*
	 * 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);
L
Linus Torvalds 已提交
1728 1729 1730 1731 1732 1733 1734 1735 1736
		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))
1737 1738
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1739
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1740 1741
	} else
		copy_user_highpage(dst, src, va, vma);
1742 1743
}

L
Linus Torvalds 已提交
1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757
/*
 * 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.
 *
1758 1759 1760
 * 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.
L
Linus Torvalds 已提交
1761
 */
1762 1763
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1764
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1765
{
1766
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1767
	pte_t entry;
N
Nick Piggin 已提交
1768
	int reuse = 0, ret = 0;
1769
	int page_mkwrite = 0;
1770
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1771

1772
	old_page = vm_normal_page(vma, address, orig_pte);
1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783
	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;
1784
		goto gotten;
1785
	}
L
Linus Torvalds 已提交
1786

1787
	/*
P
Peter Zijlstra 已提交
1788 1789
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1790
	 */
P
Peter Zijlstra 已提交
1791 1792 1793 1794 1795 1796
	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)) ==
1797
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1798 1799 1800 1801 1802
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825
		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);
1826
			page_cache_release(old_page);
1827 1828
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1829 1830

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1831
		}
1832 1833
		dirty_page = old_page;
		get_page(dirty_page);
1834 1835 1836 1837
		reuse = 1;
	}

	if (reuse) {
1838
reuse:
1839 1840 1841
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1842
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1843
			update_mmu_cache(vma, address, entry);
1844 1845
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1846 1847 1848 1849 1850
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1851
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1852
gotten:
1853
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1854 1855

	if (unlikely(anon_vma_prepare(vma)))
1856
		goto oom;
N
Nick Piggin 已提交
1857 1858 1859 1860 1861
	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);
N
Nick Piggin 已提交
1862
	__SetPageUptodate(new_page);
1863

1864
	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
1865 1866
		goto oom_free_new;

L
Linus Torvalds 已提交
1867 1868 1869
	/*
	 * Re-check the pte - we dropped the lock
	 */
1870
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1871
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1872 1873 1874 1875 1876 1877
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1878
			inc_mm_counter(mm, anon_rss);
1879
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1880 1881
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1882 1883 1884 1885 1886 1887
		/*
		 * 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.
		 */
A
Andrea Arcangeli 已提交
1888
		ptep_clear_flush_notify(vma, address, page_table);
1889
		set_pte_at(mm, address, page_table, entry);
1890
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1891
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1892
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1893

N
Nick Piggin 已提交
1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919
		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);
		}

L
Linus Torvalds 已提交
1920 1921
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1922
		ret |= VM_FAULT_WRITE;
1923 1924 1925
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
1926 1927 1928 1929
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1930
unlock:
1931
	pte_unmap_unlock(page_table, ptl);
1932
	if (dirty_page) {
1933 1934 1935
		if (vma->vm_file)
			file_update_time(vma->vm_file);

1936 1937 1938 1939 1940 1941 1942 1943 1944
		/*
		 * 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);
1945
		set_page_dirty_balance(dirty_page, page_mkwrite);
1946 1947
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1948
	return ret;
1949
oom_free_new:
1950
	page_cache_release(new_page);
1951
oom:
H
Hugh Dickins 已提交
1952 1953
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1954
	return VM_FAULT_OOM;
1955 1956 1957 1958

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985
}

/*
 * 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
1986
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
 * 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;

2013 2014
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2015
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2016 2017
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2018 2019
	 */

L
Linus Torvalds 已提交
2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030
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;
		}
	}

2031 2032
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2033
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2034

2035
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2036 2037 2038 2039 2040 2041
		/* 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 */
2042
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108
		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;
	}
}

/**
2109
 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
M
Martin Waitz 已提交
2110
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146
 * @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);

2147
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163
	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);

2164 2165 2166 2167
/**
 * vmtruncate - unmap mappings "freed" by truncate() syscall
 * @inode: inode of the file used
 * @offset: file offset to start truncating
L
Linus Torvalds 已提交
2168 2169 2170 2171 2172 2173 2174
 *
 * 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)
{
C
Christoph Hellwig 已提交
2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185
	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;
L
Linus Torvalds 已提交
2186

C
Christoph Hellwig 已提交
2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208
		/*
		 * 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);
	}
2209

L
Linus Torvalds 已提交
2210 2211 2212
	if (inode->i_op && inode->i_op->truncate)
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2213

L
Linus Torvalds 已提交
2214 2215 2216 2217 2218 2219 2220
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232
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;

2233
	mutex_lock(&inode->i_mutex);
2234 2235 2236
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2237
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2238 2239
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2240
	mutex_unlock(&inode->i_mutex);
2241 2242 2243 2244

	return 0;
}

L
Linus Torvalds 已提交
2245
/*
2246 2247 2248
 * 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.
L
Linus Torvalds 已提交
2249
 */
2250 2251 2252
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)
L
Linus Torvalds 已提交
2253
{
2254
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2255
	struct page *page;
2256
	swp_entry_t entry;
L
Linus Torvalds 已提交
2257
	pte_t pte;
N
Nick Piggin 已提交
2258
	int ret = 0;
L
Linus Torvalds 已提交
2259

H
Hugh Dickins 已提交
2260
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2261
		goto out;
2262 2263

	entry = pte_to_swp_entry(orig_pte);
2264 2265 2266 2267
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2268
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2269 2270
	page = lookup_swap_cache(entry);
	if (!page) {
2271
		grab_swap_token(); /* Contend for token _before_ read-in */
2272 2273
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2274 2275
		if (!page) {
			/*
2276 2277
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2278
			 */
2279
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2280 2281
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2282
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2283
			goto unlock;
L
Linus Torvalds 已提交
2284 2285 2286 2287
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2288
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2289 2290
	}

2291
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2292 2293 2294 2295 2296
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
		ret = VM_FAULT_OOM;
		goto out;
	}

L
Linus Torvalds 已提交
2297 2298
	mark_page_accessed(page);
	lock_page(page);
2299
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2300 2301

	/*
2302
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2303
	 */
2304
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2305
	if (unlikely(!pte_same(*page_table, orig_pte)))
2306 2307 2308 2309 2310
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2311 2312 2313 2314
	}

	/* The page isn't present yet, go ahead with the fault. */

2315
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2316 2317 2318 2319 2320 2321 2322 2323 2324 2325
	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);

2326 2327 2328 2329 2330
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2331
	if (write_access) {
2332 2333 2334
		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
		if (ret & VM_FAULT_ERROR)
			ret &= VM_FAULT_ERROR;
L
Linus Torvalds 已提交
2335 2336 2337 2338 2339
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2340
unlock:
2341
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2342 2343
out:
	return ret;
2344
out_nomap:
2345
	mem_cgroup_uncharge_page(page);
2346
	pte_unmap_unlock(page_table, ptl);
2347 2348
	unlock_page(page);
	page_cache_release(page);
2349
	return ret;
L
Linus Torvalds 已提交
2350 2351 2352
}

/*
2353 2354 2355
 * 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.
L
Linus Torvalds 已提交
2356
 */
2357 2358 2359
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)
L
Linus Torvalds 已提交
2360
{
2361 2362
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2363 2364
	pte_t entry;

N
Nick Piggin 已提交
2365 2366
	/* Allocate our own private page. */
	pte_unmap(page_table);
2367

N
Nick Piggin 已提交
2368 2369 2370 2371 2372
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
N
Nick Piggin 已提交
2373
	__SetPageUptodate(page);
2374

2375
	if (mem_cgroup_charge(page, mm, GFP_KERNEL))
2376 2377
		goto oom_free_page;

N
Nick Piggin 已提交
2378 2379
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2380

N
Nick Piggin 已提交
2381 2382 2383 2384 2385 2386
	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);
2387
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2388 2389

	/* No need to invalidate - it was non-present before */
2390 2391
	update_mmu_cache(vma, address, entry);
unlock:
2392
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2393
	return 0;
2394
release:
2395
	mem_cgroup_uncharge_page(page);
2396 2397
	page_cache_release(page);
	goto unlock;
2398
oom_free_page:
2399
	page_cache_release(page);
2400
oom:
L
Linus Torvalds 已提交
2401 2402 2403 2404
	return VM_FAULT_OOM;
}

/*
2405
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2406
 * tries to share with existing pages, but makes a separate copy if
2407 2408
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2409 2410 2411 2412
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2413
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2414
 * but allow concurrent faults), and pte neither mapped nor locked.
2415
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2416
 */
2417
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2418
		unsigned long address, pmd_t *pmd,
2419
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2420
{
2421
	pte_t *page_table;
2422
	spinlock_t *ptl;
N
Nick Piggin 已提交
2423
	struct page *page;
L
Linus Torvalds 已提交
2424 2425
	pte_t entry;
	int anon = 0;
2426
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2427 2428
	struct vm_fault vmf;
	int ret;
2429
	int page_mkwrite = 0;
2430

N
Nick Piggin 已提交
2431 2432 2433 2434
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2435

N
Nick Piggin 已提交
2436 2437 2438
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2439

2440
	/*
N
Nick Piggin 已提交
2441
	 * For consistency in subsequent calls, make the faulted page always
2442 2443
	 * locked.
	 */
N
Nick Piggin 已提交
2444
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2445
		lock_page(vmf.page);
2446
	else
N
Nick Piggin 已提交
2447
		VM_BUG_ON(!PageLocked(vmf.page));
2448

L
Linus Torvalds 已提交
2449 2450 2451
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2452
	page = vmf.page;
2453
	if (flags & FAULT_FLAG_WRITE) {
2454
		if (!(vma->vm_flags & VM_SHARED)) {
2455
			anon = 1;
2456
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2457
				ret = VM_FAULT_OOM;
2458
				goto out;
2459
			}
N
Nick Piggin 已提交
2460 2461
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2462
			if (!page) {
N
Nick Piggin 已提交
2463
				ret = VM_FAULT_OOM;
2464
				goto out;
2465
			}
N
Nick Piggin 已提交
2466
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2467
			__SetPageUptodate(page);
2468
		} else {
2469 2470
			/*
			 * If the page will be shareable, see if the backing
2471
			 * address space wants to know that the page is about
2472 2473
			 * to become writable
			 */
2474 2475 2476
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2477 2478
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2479 2480 2481
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2482 2483 2484 2485 2486 2487 2488 2489
				/*
				 * 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) {
N
Nick Piggin 已提交
2490
					ret = 0;
N
Nick Piggin 已提交
2491 2492 2493
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2494
				page_mkwrite = 1;
2495 2496
			}
		}
2497

L
Linus Torvalds 已提交
2498 2499
	}

2500
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2501 2502 2503 2504
		ret = VM_FAULT_OOM;
		goto out;
	}

2505
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517

	/*
	 * 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... */
2518
	if (likely(pte_same(*page_table, orig_pte))) {
2519 2520
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2521
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2522 2523 2524
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2525 2526 2527
                        inc_mm_counter(mm, anon_rss);
                        lru_cache_add_active(page);
                        page_add_new_anon_rmap(page, vma, address);
2528
		} else {
2529
			inc_mm_counter(mm, file_rss);
2530
			page_add_file_rmap(page);
2531
			if (flags & FAULT_FLAG_WRITE) {
2532
				dirty_page = page;
2533 2534
				get_page(dirty_page);
			}
2535
		}
2536 2537 2538

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2539
	} else {
2540
		mem_cgroup_uncharge_page(page);
2541 2542 2543
		if (anon)
			page_cache_release(page);
		else
2544
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2545 2546
	}

2547
	pte_unmap_unlock(page_table, ptl);
2548 2549

out:
N
Nick Piggin 已提交
2550
	unlock_page(vmf.page);
2551
out_unlocked:
2552
	if (anon)
N
Nick Piggin 已提交
2553
		page_cache_release(vmf.page);
2554
	else if (dirty_page) {
2555 2556 2557
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2558
		set_page_dirty_balance(dirty_page, page_mkwrite);
2559 2560
		put_page(dirty_page);
	}
2561

N
Nick Piggin 已提交
2562
	return ret;
2563
}
2564

2565 2566 2567 2568 2569
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)
2570
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2571 2572
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2573 2574
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2575 2576
}

L
Linus Torvalds 已提交
2577 2578 2579 2580
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2581 2582 2583 2584
 *
 * 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.
L
Linus Torvalds 已提交
2585
 */
N
Nick Piggin 已提交
2586
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2587 2588
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2589
{
N
Nick Piggin 已提交
2590 2591
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2592
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2593

H
Hugh Dickins 已提交
2594
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2595
		return 0;
L
Linus Torvalds 已提交
2596

N
Nick Piggin 已提交
2597 2598
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2599 2600 2601
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2602
		print_bad_pte(vma, orig_pte, address);
2603 2604 2605 2606
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2607
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618
}

/*
 * 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).
 *
H
Hugh Dickins 已提交
2619 2620 2621
 * 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.
L
Linus Torvalds 已提交
2622 2623
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2624 2625
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2626 2627
{
	pte_t entry;
2628
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2629

2630
	entry = *pte;
L
Linus Torvalds 已提交
2631
	if (!pte_present(entry)) {
2632
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2633
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2634
				if (likely(vma->vm_ops->fault))
2635 2636
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2637 2638 2639
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2640
		}
L
Linus Torvalds 已提交
2641
		if (pte_file(entry))
N
Nick Piggin 已提交
2642
			return do_nonlinear_fault(mm, vma, address,
2643 2644 2645
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2646 2647
	}

H
Hugh Dickins 已提交
2648
	ptl = pte_lockptr(mm, pmd);
2649 2650 2651
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2652 2653
	if (write_access) {
		if (!pte_write(entry))
2654 2655
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2656 2657 2658
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2659
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670
		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);
	}
2671 2672
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2673
	return 0;
L
Linus Torvalds 已提交
2674 2675 2676 2677 2678
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2679
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2680 2681 2682 2683 2684 2685 2686 2687 2688
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2689
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2690

2691 2692
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2693 2694 2695 2696

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2697
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2698 2699
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2700
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2701 2702
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2703
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2704

H
Hugh Dickins 已提交
2705
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2706 2707 2708 2709 2710
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2711
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2712
 */
2713
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2714
{
H
Hugh Dickins 已提交
2715 2716
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2717
		return -ENOMEM;
L
Linus Torvalds 已提交
2718

2719 2720
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2721
	spin_lock(&mm->page_table_lock);
2722
	if (pgd_present(*pgd))		/* Another has populated it */
2723
		pud_free(mm, new);
2724 2725
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2726
	spin_unlock(&mm->page_table_lock);
2727
	return 0;
L
Linus Torvalds 已提交
2728 2729 2730 2731 2732 2733
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2734
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2735
 */
2736
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2737
{
H
Hugh Dickins 已提交
2738 2739
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2740
		return -ENOMEM;
L
Linus Torvalds 已提交
2741

2742 2743
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2744
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2745
#ifndef __ARCH_HAS_4LEVEL_HACK
2746
	if (pud_present(*pud))		/* Another has populated it */
2747
		pmd_free(mm, new);
2748 2749
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2750
#else
2751
	if (pgd_present(*pud))		/* Another has populated it */
2752
		pmd_free(mm, new);
2753 2754
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2755
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2756
	spin_unlock(&mm->page_table_lock);
2757
	return 0;
2758
}
L
Linus Torvalds 已提交
2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769
#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;
2770 2771
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2772
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2773 2774 2775 2776 2777 2778 2779 2780 2781 2782
	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)
2783
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2784 2785 2786 2787 2788 2789

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;
R
Roland McGrath 已提交
2790 2791
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2792 2793 2794 2795 2796 2797 2798
	/*
	 * 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;
L
Linus Torvalds 已提交
2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822
	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 */
2823

2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903
#ifdef CONFIG_HAVE_IOREMAP_PROT
static resource_size_t follow_phys(struct vm_area_struct *vma,
			unsigned long address, unsigned int flags,
			unsigned long *prot)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
	spinlock_t *ptl;
	resource_size_t phys_addr = 0;
	struct mm_struct *mm = vma->vm_mm;

	VM_BUG_ON(!(vma->vm_flags & (VM_IO | VM_PFNMAP)));

	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
		goto no_page_table;

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
		goto no_page_table;

	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
		goto no_page_table;

	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
	if (pmd_huge(*pmd))
		goto no_page_table;

	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!ptep)
		goto out;

	pte = *ptep;
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
	phys_addr = pte_pfn(pte);
	phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */

	*prot = pgprot_val(pte_pgprot(pte));

unlock:
	pte_unmap_unlock(ptep, ptl);
out:
	return phys_addr;
no_page_table:
	return 0;
}

int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
			void *buf, int len, int write)
{
	resource_size_t phys_addr;
	unsigned long prot = 0;
	void *maddr;
	int offset = addr & (PAGE_SIZE-1);

	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		return -EINVAL;

	phys_addr = follow_phys(vma, addr, write, &prot);

	if (!phys_addr)
		return -EINVAL;

	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
#endif

2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919
/*
 * Access another process' address space.
 * Source/target buffer must be kernel space,
 * Do not walk the page table directly, use get_user_pages
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	void *old_buf = buf;

	mm = get_task_mm(tsk);
	if (!mm)
		return 0;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
2920
	/* ignore errors, just check how much was successfully transferred */
2921 2922 2923
	while (len) {
		int bytes, ret, offset;
		void *maddr;
2924
		struct page *page = NULL;
2925 2926 2927

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943
		if (ret <= 0) {
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
#ifdef CONFIG_HAVE_IOREMAP_PROT
			vma = find_vma(mm, addr);
			if (!vma)
				break;
			if (vma->vm_ops && vma->vm_ops->access)
				ret = vma->vm_ops->access(vma, addr, buf,
							  len, write);
			if (ret <= 0)
#endif
				break;
			bytes = ret;
2944
		} else {
2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960
			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);
2961 2962 2963 2964 2965 2966 2967 2968 2969 2970
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
2971 2972 2973 2974 2975 2976 2977 2978 2979

/*
 * 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;

2980 2981 2982 2983 2984 2985 2986
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

2987 2988 2989 2990 2991 2992 2993 2994
	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;

2995
			p = d_path(&f->f_path, buf, PAGE_SIZE);
2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008
			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(&current->mm->mmap_sem);
}