memory.c 84.0 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 <linux/kallsyms.h>
#include <linux/swapops.h>
#include <linux/elf.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>

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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, unsigned long addr,
			  pte_t pte, struct page *page)
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{
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	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
	pud_t *pud = pud_offset(pgd, addr);
	pmd_t *pmd = pmd_offset(pud, addr);
	struct address_space *mapping;
	pgoff_t index;

	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
	index = linear_page_index(vma, addr);

	printk(KERN_EMERG "Bad page map in process %s  pte:%08llx pmd:%08llx\n",
		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
	if (page) {
		printk(KERN_EMERG
		"page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
		page, (void *)page->flags, page_count(page),
		page_mapcount(page), page->mapping, page->index);
	}
	printk(KERN_EMERG
		"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
		(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
	/*
	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
	 */
	if (vma->vm_ops)
		print_symbol(KERN_EMERG "vma->vm_ops->fault: %s\n",
				(unsigned long)vma->vm_ops->fault);
	if (vma->vm_file && vma->vm_file->f_op)
		print_symbol(KERN_EMERG "vma->vm_file->f_op->mmap: %s\n",
				(unsigned long)vma->vm_file->f_op->mmap);
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	dump_stack();
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	add_taint(TAINT_BAD_PAGE);
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}

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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 = pte_pfn(pte);
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	if (HAVE_PTE_SPECIAL) {
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		if (likely(!pte_special(pte)))
			goto check_pfn;
		if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)))
			print_bad_pte(vma, addr, pte, NULL);
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		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

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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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check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
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	/*
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	 * NOTE! We still have PageReserved() pages in the page tables.
	 * 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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Linus Torvalds 已提交
559
		ptep_set_wrprotect(src_mm, addr, src_pte);
560
		pte = pte_wrprotect(pte);
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561 562 563 564 565 566 567 568 569
	}

	/*
	 * 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);
570 571 572 573

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
N
Nick Piggin 已提交
574
		page_dup_rmap(page, vma, addr);
575 576
		rss[!!PageAnon(page)]++;
	}
577 578 579

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
L
Linus Torvalds 已提交
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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;
H
Hugh Dickins 已提交
587
	spinlock_t *src_ptl, *dst_ptl;
588
	int progress = 0;
H
Hugh Dickins 已提交
589
	int rss[2];
L
Linus Torvalds 已提交
590 591

again:
592
	rss[1] = rss[0] = 0;
H
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593
	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
597
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
598
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
599
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
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	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
606 607 608
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
609
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
610 611
				break;
		}
L
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612 613 614 615
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
616
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
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		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

620
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
621
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
622
	pte_unmap_nested(src_pte - 1);
623
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
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	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
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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
682
	int ret;
L
Linus Torvalds 已提交
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684 685 686 687 688 689
	/*
	 * 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.
	 */
690
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
691 692 693 694
		if (!vma->anon_vma)
			return 0;
	}

L
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	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

698
	if (unlikely(is_pfn_mapping(vma))) {
699 700 701 702 703 704 705 706 707
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
		ret = track_pfn_vma_copy(vma);
		if (ret)
			return ret;
	}

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Andrea Arcangeli 已提交
708 709 710 711 712 713 714 715 716 717
	/*
	 * 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;
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Andrea Arcangeli 已提交
724 725 726 727 728
		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
729
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
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Andrea Arcangeli 已提交
730 731 732 733 734

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

737
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
738
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
739
				unsigned long addr, unsigned long end,
740
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
741
{
N
Nick Piggin 已提交
742
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
743
	pte_t *pte;
744
	spinlock_t *ptl;
745 746
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
747

748
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
749
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
750 751
	do {
		pte_t ptent = *pte;
752 753
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
754
			continue;
755
		}
756 757 758

		(*zap_work) -= PAGE_SIZE;

L
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759
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
760
			struct page *page;
761

762
			page = vm_normal_page(vma, addr, ptent);
L
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763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780
			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
781
			ptent = ptep_get_and_clear_full(mm, addr, pte,
782
							tlb->fullmm);
L
Linus Torvalds 已提交
783 784 785 786 787 788
			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
789
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
790 791
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
792
				anon_rss--;
793 794 795
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
796 797
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
798
					mark_page_accessed(page);
H
Hugh Dickins 已提交
799
				file_rss--;
800
			}
N
Nick Piggin 已提交
801
			page_remove_rmap(page, vma);
802 803
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
L
Linus Torvalds 已提交
804 805 806 807 808 809 810 811 812 813 814
			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));
815
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
816
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
817

H
Hugh Dickins 已提交
818
	add_mm_rss(mm, file_rss, anon_rss);
819
	arch_leave_lazy_mmu_mode();
820
	pte_unmap_unlock(pte - 1, ptl);
821 822

	return addr;
L
Linus Torvalds 已提交
823 824
}

825
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
826
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
827
				unsigned long addr, unsigned long end,
828
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
829 830 831 832 833 834 835
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
836 837
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
838
			continue;
839 840 841 842 843 844
		}
		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
845 846
}

847
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
848
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
849
				unsigned long addr, unsigned long end,
850
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
851 852 853 854 855 856 857
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
858 859
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
860
			continue;
861 862 863 864 865 866
		}
		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
867 868
}

869 870
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
871
				unsigned long addr, unsigned long end,
872
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
873 874 875 876 877 878 879 880 881 882 883 884
{
	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);
885 886
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
887
			continue;
888 889 890 891
		}
		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
892
	tlb_end_vma(tlb, vma);
893 894

	return addr;
L
Linus Torvalds 已提交
895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912
}

#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
 *
913
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
914
 *
915
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
916
 *
917 918
 * 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
919 920 921 922 923 924 925 926 927 928 929
 * 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.
 */
930
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
931 932 933 934
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
935
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
936 937
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
938
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
939
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
940
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
941
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
942

A
Andrea Arcangeli 已提交
943
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
944 945 946 947 948 949 950 951 952 953 954 955 956
	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;

957
		if (unlikely(is_pfn_mapping(vma)))
958 959
			untrack_pfn_vma(vma, 0, 0);

L
Linus Torvalds 已提交
960 961 962 963 964 965
		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

966
			if (unlikely(is_vm_hugetlb_page(vma))) {
967 968 969 970 971 972 973 974 975 976 977 978 979 980
				/*
				 * 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) /
981
					pages_per_huge_page(hstate_vma(vma));
982 983
				}

984 985 986 987 988 989 990 991
				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
992 993 994 995 996
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
997
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
998
				if (i_mmap_lock) {
999
					*tlbp = NULL;
L
Linus Torvalds 已提交
1000 1001 1002 1003 1004
					goto out;
				}
				cond_resched();
			}

1005
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
1006
			tlb_start_valid = 0;
1007
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1008 1009 1010
		}
	}
out:
A
Andrea Arcangeli 已提交
1011
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1012
	return start;	/* which is now the end (or restart) address */
L
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1013 1014 1015 1016 1017 1018 1019 1020 1021
}

/**
 * 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
 */
1022
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1023 1024 1025 1026 1027 1028 1029 1030 1031
		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);
1032
	update_hiwater_rss(mm);
1033 1034 1035
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1036
	return end;
L
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1037 1038
}

1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
/**
 * 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
Linus Torvalds 已提交
1062 1063 1064
/*
 * Do a quick page-table lookup for a single page.
 */
1065
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1066
			unsigned int flags)
L
Linus Torvalds 已提交
1067 1068 1069 1070 1071
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1072
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1073
	struct page *page;
1074
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1075

1076 1077 1078 1079 1080
	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
1081

1082
	page = NULL;
L
Linus Torvalds 已提交
1083 1084
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1085
		goto no_page_table;
L
Linus Torvalds 已提交
1086 1087

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1088
	if (pud_none(*pud))
1089
		goto no_page_table;
A
Andi Kleen 已提交
1090 1091 1092 1093 1094 1095 1096 1097
	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
1098
	pmd = pmd_offset(pud, address);
1099
	if (pmd_none(*pmd))
1100 1101 1102 1103
		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
1104
		goto out;
1105
	}
1106 1107 1108
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1109
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1110 1111

	pte = *ptep;
1112
	if (!pte_present(pte))
1113
		goto no_page;
1114 1115
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
1116 1117
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
1118
		goto bad_page;
L
Linus Torvalds 已提交
1119

1120 1121 1122 1123 1124 1125 1126 1127 1128 1129
	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
1130
out:
1131
	return page;
L
Linus Torvalds 已提交
1132

1133 1134 1135 1136 1137 1138 1139 1140 1141
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 */
1142 1143 1144 1145 1146 1147
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
1148
		page = ZERO_PAGE(0);
1149 1150 1151 1152 1153
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1154 1155
}

1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168
/* 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
1169
	 * And if we have a fault routine, it's not an anonymous region.
1170
	 */
N
Nick Piggin 已提交
1171
	return !vma->vm_ops || !vma->vm_ops->fault;
1172 1173
}

N
Nick Piggin 已提交
1174 1175 1176 1177


int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		     unsigned long start, int len, int flags,
L
Linus Torvalds 已提交
1178 1179 1180
		struct page **pages, struct vm_area_struct **vmas)
{
	int i;
N
Nick Piggin 已提交
1181 1182 1183 1184
	unsigned int vm_flags = 0;
	int write = !!(flags & GUP_FLAGS_WRITE);
	int force = !!(flags & GUP_FLAGS_FORCE);
	int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
L
Linus Torvalds 已提交
1185

1186 1187
	if (len <= 0)
		return 0;
L
Linus Torvalds 已提交
1188 1189 1190 1191
	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
1192 1193
	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
1194 1195 1196
	i = 0;

	do {
1197 1198
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
1199 1200 1201 1202 1203 1204 1205 1206 1207

		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;
N
Nick Piggin 已提交
1208 1209 1210

			/* user gate pages are read-only */
			if (!ignore && write)
L
Linus Torvalds 已提交
1211 1212 1213 1214 1215 1216 1217 1218 1219
				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);
1220 1221
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1222
			pte = pte_offset_map(pmd, pg);
1223 1224 1225 1226
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1227
			if (pages) {
1228
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1229 1230 1231
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1232 1233 1234 1235 1236 1237 1238 1239 1240 1241
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

N
Nick Piggin 已提交
1242 1243 1244
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
		    (!ignore && !(vm_flags & vma->vm_flags)))
L
Linus Torvalds 已提交
1245 1246 1247 1248
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1249
						&start, &len, i, write);
L
Linus Torvalds 已提交
1250 1251
			continue;
		}
1252 1253 1254 1255

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
1256
		if (!write && use_zero_page(vma))
1257 1258
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1259
		do {
1260
			struct page *page;
L
Linus Torvalds 已提交
1261

1262 1263 1264 1265 1266 1267
			/*
			 * 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)))
1268
				return i ? i : -ENOMEM;
1269

1270 1271
			if (write)
				foll_flags |= FOLL_WRITE;
1272

1273
			cond_resched();
1274
			while (!(page = follow_page(vma, start, foll_flags))) {
1275
				int ret;
N
Nick Piggin 已提交
1276
				ret = handle_mm_fault(mm, vma, start,
1277
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289
				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++;

1290
				/*
N
Nick Piggin 已提交
1291 1292 1293 1294
				 * 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
1295 1296 1297 1298 1299 1300
				 * page lookups as if they were reads. But only
				 * do so when looping for pte_write is futile:
				 * in some cases userspace may also be wanting
				 * to write to the gotten user page, which a
				 * read fault here might prevent (a readonly
				 * page might get reCOWed by userspace write).
1301
				 */
1302 1303
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1304
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1305

1306
				cond_resched();
L
Linus Torvalds 已提交
1307
			}
1308 1309
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1310
			if (pages) {
1311
				pages[i] = page;
1312

1313
				flush_anon_page(vma, page, start);
1314
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1315 1316 1317 1318 1319 1320
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1321 1322
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1323 1324
	return i;
}
N
Nick Piggin 已提交
1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341

int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long start, int len, int write, int force,
		struct page **pages, struct vm_area_struct **vmas)
{
	int flags = 0;

	if (write)
		flags |= GUP_FLAGS_WRITE;
	if (force)
		flags |= GUP_FLAGS_FORCE;

	return __get_user_pages(tsk, mm,
				start, len, flags,
				pages, vmas);
}

L
Linus Torvalds 已提交
1342 1343
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1344 1345
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1346 1347 1348 1349
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1350
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1351 1352 1353 1354 1355 1356
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1357 1358 1359 1360 1361 1362 1363
/*
 * 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
1364 1365
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1366
{
N
Nick Piggin 已提交
1367
	struct mm_struct *mm = vma->vm_mm;
1368
	int retval;
1369
	pte_t *pte;
1370 1371
	spinlock_t *ptl;

1372
	retval = -EINVAL;
1373
	if (PageAnon(page))
1374
		goto out;
1375 1376
	retval = -ENOMEM;
	flush_dcache_page(page);
1377
	pte = get_locked_pte(mm, addr, &ptl);
1378
	if (!pte)
1379
		goto out;
1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390
	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;
1391 1392
	pte_unmap_unlock(pte, ptl);
	return retval;
1393 1394 1395 1396 1397 1398
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1399 1400 1401 1402 1403 1404
/**
 * 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
 *
1405 1406 1407 1408 1409 1410
 * 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
1411
 * (see split_page()).
1412 1413 1414 1415 1416 1417 1418 1419 1420
 *
 * 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
1421 1422
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1423 1424 1425 1426 1427
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1428
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1429
	return insert_page(vma, addr, page, vma->vm_page_prot);
1430
}
1431
EXPORT_SYMBOL(vm_insert_page);
1432

N
Nick Piggin 已提交
1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460
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
1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471
/**
 * 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
1472 1473 1474 1475 1476
 *
 * 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
1477 1478
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1479
			unsigned long pfn)
N
Nick Piggin 已提交
1480
{
1481
	int ret;
N
Nick Piggin 已提交
1482 1483 1484 1485 1486 1487
	/*
	 * 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
1488 1489 1490 1491 1492
	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
1493

N
Nick Piggin 已提交
1494 1495
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1496 1497 1498 1499 1500 1501 1502 1503 1504
	if (track_pfn_vma_new(vma, vma->vm_page_prot, pfn, PAGE_SIZE))
		return -EINVAL;

	ret = insert_pfn(vma, addr, pfn, vma->vm_page_prot);

	if (ret)
		untrack_pfn_vma(vma, pfn, PAGE_SIZE);

	return ret;
N
Nick Piggin 已提交
1505 1506
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1507

N
Nick Piggin 已提交
1508 1509 1510 1511
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
1512

N
Nick Piggin 已提交
1513 1514
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1515

N
Nick Piggin 已提交
1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528
	/*
	 * 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
1529
}
N
Nick Piggin 已提交
1530
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1531

L
Linus Torvalds 已提交
1532 1533 1534 1535 1536 1537 1538 1539 1540 1541
/*
 * 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
1542
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1543

H
Hugh Dickins 已提交
1544
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1545 1546
	if (!pte)
		return -ENOMEM;
1547
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1548 1549
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1550
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1551 1552
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1553
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1554
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597
	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;
}

1598 1599 1600 1601 1602 1603 1604 1605 1606 1607
/**
 * 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
1608 1609 1610 1611 1612
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;
1613
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1614 1615 1616 1617 1618 1619 1620 1621
	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
1622 1623 1624 1625 1626
	 *   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.
1627 1628 1629
	 *   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
1630 1631 1632 1633
	 *
	 * 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
1634
	 */
1635
	if (addr == vma->vm_start && end == vma->vm_end)
L
Linus Torvalds 已提交
1636
		vma->vm_pgoff = pfn;
1637 1638
	else if (is_cow_mapping(vma->vm_flags))
		return -EINVAL;
L
Linus Torvalds 已提交
1639

1640
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1641

1642 1643 1644 1645
	err = track_pfn_vma_new(vma, prot, pfn, PAGE_ALIGN(size));
	if (err)
		return -EINVAL;

L
Linus Torvalds 已提交
1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656
	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);
1657 1658 1659 1660

	if (err)
		untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));

L
Linus Torvalds 已提交
1661 1662 1663 1664
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1665 1666 1667 1668 1669 1670
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;
1671
	pgtable_t token;
1672
	spinlock_t *uninitialized_var(ptl);
1673 1674 1675 1676 1677 1678 1679 1680 1681

	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));

1682 1683
	arch_enter_lazy_mmu_mode();

1684
	token = pmd_pgtable(*pmd);
1685 1686

	do {
1687
		err = fn(pte, token, addr, data);
1688 1689 1690 1691
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

1692 1693
	arch_leave_lazy_mmu_mode();

1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706
	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
1707 1708
	BUG_ON(pud_huge(*pud));

1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749
	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
1750
	unsigned long start = addr, end = addr + size;
1751 1752 1753
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1754
	mmu_notifier_invalidate_range_start(mm, start, end);
1755 1756 1757 1758 1759 1760 1761
	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
1762
	mmu_notifier_invalidate_range_end(mm, start, end);
1763 1764 1765 1766
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1767 1768 1769 1770 1771 1772 1773 1774 1775
/*
 * 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
1776
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1777 1778 1779 1780 1781
				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
1782 1783
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1784
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1785
		spin_unlock(ptl);
1786 1787 1788 1789 1790 1791
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804
/*
 * 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;
}

1805
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1806 1807 1808 1809 1810 1811 1812 1813 1814
{
	/*
	 * 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
1815 1816 1817 1818 1819 1820 1821 1822 1823
		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))
1824 1825
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1826
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1827 1828
	} else
		copy_user_highpage(dst, src, va, vma);
1829 1830
}

L
Linus Torvalds 已提交
1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844
/*
 * 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.
 *
1845 1846 1847
 * 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
1848
 */
1849 1850
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1851
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1852
{
1853
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1854
	pte_t entry;
N
Nick Piggin 已提交
1855
	int reuse = 0, ret = 0;
1856
	int page_mkwrite = 0;
1857
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1858

1859
	old_page = vm_normal_page(vma, address, orig_pte);
1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870
	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;
1871
		goto gotten;
1872
	}
L
Linus Torvalds 已提交
1873

1874
	/*
P
Peter Zijlstra 已提交
1875 1876
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1877
	 */
P
Peter Zijlstra 已提交
1878
	if (PageAnon(old_page)) {
1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890
		if (!trylock_page(old_page)) {
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);
			lock_page(old_page);
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
				goto unlock;
			}
			page_cache_release(old_page);
P
Peter Zijlstra 已提交
1891
		}
1892
		reuse = reuse_swap_page(old_page);
1893
		unlock_page(old_page);
P
Peter Zijlstra 已提交
1894
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1895
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1896 1897 1898 1899 1900
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923
		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);
1924
			page_cache_release(old_page);
1925 1926
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1927 1928

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1929
		}
1930 1931
		dirty_page = old_page;
		get_page(dirty_page);
1932 1933 1934 1935
		reuse = 1;
	}

	if (reuse) {
1936
reuse:
1937 1938 1939
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1940
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1941
			update_mmu_cache(vma, address, entry);
1942 1943
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1944 1945 1946 1947 1948
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1949
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1950
gotten:
1951
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1952 1953

	if (unlikely(anon_vma_prepare(vma)))
1954
		goto oom;
N
Nick Piggin 已提交
1955 1956 1957 1958
	VM_BUG_ON(old_page == ZERO_PAGE(0));
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
	if (!new_page)
		goto oom;
N
Nick Piggin 已提交
1959 1960 1961 1962 1963 1964 1965 1966 1967
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
	if (vma->vm_flags & VM_LOCKED) {
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
N
Nick Piggin 已提交
1968
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
1969
	__SetPageUptodate(new_page);
1970

1971
	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
1972 1973
		goto oom_free_new;

L
Linus Torvalds 已提交
1974 1975 1976
	/*
	 * Re-check the pte - we dropped the lock
	 */
1977
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1978
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1979 1980 1981 1982 1983 1984
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1985
			inc_mm_counter(mm, anon_rss);
1986
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1987 1988
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1989 1990 1991 1992 1993 1994
		/*
		 * 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
1995
		ptep_clear_flush_notify(vma, address, page_table);
N
Nick Piggin 已提交
1996
		page_add_new_anon_rmap(new_page, vma, address);
1997 1998
		set_pte_at(mm, address, page_table, entry);
		update_mmu_cache(vma, address, entry);
N
Nick Piggin 已提交
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024
		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
2025 2026
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2027
		ret |= VM_FAULT_WRITE;
2028 2029 2030
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2031 2032 2033 2034
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
2035
unlock:
2036
	pte_unmap_unlock(page_table, ptl);
2037
	if (dirty_page) {
2038 2039 2040
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2041 2042 2043 2044 2045 2046 2047 2048 2049
		/*
		 * 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);
2050
		set_page_dirty_balance(dirty_page, page_mkwrite);
2051 2052
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
2053
	return ret;
2054
oom_free_new:
2055
	page_cache_release(new_page);
2056
oom:
H
Hugh Dickins 已提交
2057 2058
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
2059
	return VM_FAULT_OOM;
2060 2061 2062 2063

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
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
}

/*
 * 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
2091
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117
 * 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;

2118 2119
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2120
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2121 2122
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2123 2124
	 */

L
Linus Torvalds 已提交
2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135
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;
		}
	}

2136 2137
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2138
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2139

2140
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2141 2142 2143 2144 2145 2146
		/* 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 */
2147
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213
		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;
	}
}

/**
2214
 * 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
2215
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251
 * @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);

2252
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268
	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);

2269 2270 2271 2272
/**
 * 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
2273 2274 2275 2276 2277 2278 2279
 *
 * 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
2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290
	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
2291

C
Christoph Hellwig 已提交
2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313
		/*
		 * 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);
	}
2314

A
Al Viro 已提交
2315
	if (inode->i_op->truncate)
L
Linus Torvalds 已提交
2316 2317
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2318

L
Linus Torvalds 已提交
2319 2320 2321 2322 2323 2324 2325
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2326 2327 2328 2329 2330 2331 2332 2333 2334
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.
	 */
A
Al Viro 已提交
2335
	if (!inode->i_op->truncate_range)
2336 2337
		return -ENOSYS;

2338
	mutex_lock(&inode->i_mutex);
2339 2340 2341
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2342
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2343 2344
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2345
	mutex_unlock(&inode->i_mutex);
2346 2347 2348 2349

	return 0;
}

L
Linus Torvalds 已提交
2350
/*
2351 2352 2353
 * 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
2354
 */
2355 2356 2357
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
2358
{
2359
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2360
	struct page *page;
2361
	swp_entry_t entry;
L
Linus Torvalds 已提交
2362
	pte_t pte;
N
Nick Piggin 已提交
2363
	int ret = 0;
L
Linus Torvalds 已提交
2364

H
Hugh Dickins 已提交
2365
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2366
		goto out;
2367 2368

	entry = pte_to_swp_entry(orig_pte);
2369 2370 2371 2372
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2373
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2374 2375
	page = lookup_swap_cache(entry);
	if (!page) {
2376
		grab_swap_token(); /* Contend for token _before_ read-in */
2377 2378
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2379 2380
		if (!page) {
			/*
2381 2382
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2383
			 */
2384
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2385 2386
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2387
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2388
			goto unlock;
L
Linus Torvalds 已提交
2389 2390 2391 2392
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2393
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2394 2395
	}

2396 2397 2398 2399 2400
	mark_page_accessed(page);

	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

2401
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2402
		ret = VM_FAULT_OOM;
2403
		unlock_page(page);
2404 2405 2406
		goto out;
	}

L
Linus Torvalds 已提交
2407
	/*
2408
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2409
	 */
2410
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2411
	if (unlikely(!pte_same(*page_table, orig_pte)))
2412 2413 2414 2415 2416
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2417 2418 2419 2420
	}

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

2421
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2422
	pte = mk_pte(page, vma->vm_page_prot);
2423
	if (write_access && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2424 2425 2426 2427 2428 2429 2430 2431
		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);

2432
	swap_free(entry);
N
Nick Piggin 已提交
2433
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2434
		try_to_free_swap(page);
2435 2436
	unlock_page(page);

L
Linus Torvalds 已提交
2437
	if (write_access) {
2438 2439 2440
		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
2441 2442 2443 2444 2445
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2446
unlock:
2447
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2448 2449
out:
	return ret;
2450
out_nomap:
2451
	mem_cgroup_uncharge_page(page);
2452
	pte_unmap_unlock(page_table, ptl);
2453 2454
	unlock_page(page);
	page_cache_release(page);
2455
	return ret;
L
Linus Torvalds 已提交
2456 2457 2458
}

/*
2459 2460 2461
 * 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
2462
 */
2463 2464 2465
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
2466
{
2467 2468
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2469 2470
	pte_t entry;

N
Nick Piggin 已提交
2471 2472
	/* Allocate our own private page. */
	pte_unmap(page_table);
2473

N
Nick Piggin 已提交
2474 2475 2476 2477 2478
	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
2479
	__SetPageUptodate(page);
2480

2481
	if (mem_cgroup_charge(page, mm, GFP_KERNEL))
2482 2483
		goto oom_free_page;

N
Nick Piggin 已提交
2484 2485
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2486

N
Nick Piggin 已提交
2487 2488 2489 2490 2491
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!pte_none(*page_table))
		goto release;
	inc_mm_counter(mm, anon_rss);
	page_add_new_anon_rmap(page, vma, address);
2492
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2493 2494

	/* No need to invalidate - it was non-present before */
2495 2496
	update_mmu_cache(vma, address, entry);
unlock:
2497
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2498
	return 0;
2499
release:
2500
	mem_cgroup_uncharge_page(page);
2501 2502
	page_cache_release(page);
	goto unlock;
2503
oom_free_page:
2504
	page_cache_release(page);
2505
oom:
L
Linus Torvalds 已提交
2506 2507 2508 2509
	return VM_FAULT_OOM;
}

/*
2510
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2511
 * tries to share with existing pages, but makes a separate copy if
2512 2513
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2514 2515 2516 2517
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2518
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2519
 * but allow concurrent faults), and pte neither mapped nor locked.
2520
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2521
 */
2522
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2523
		unsigned long address, pmd_t *pmd,
2524
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2525
{
2526
	pte_t *page_table;
2527
	spinlock_t *ptl;
N
Nick Piggin 已提交
2528
	struct page *page;
L
Linus Torvalds 已提交
2529 2530
	pte_t entry;
	int anon = 0;
2531
	int charged = 0;
2532
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2533 2534
	struct vm_fault vmf;
	int ret;
2535
	int page_mkwrite = 0;
2536

N
Nick Piggin 已提交
2537 2538 2539 2540
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2541

N
Nick Piggin 已提交
2542 2543 2544
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2545

2546
	/*
N
Nick Piggin 已提交
2547
	 * For consistency in subsequent calls, make the faulted page always
2548 2549
	 * locked.
	 */
N
Nick Piggin 已提交
2550
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2551
		lock_page(vmf.page);
2552
	else
N
Nick Piggin 已提交
2553
		VM_BUG_ON(!PageLocked(vmf.page));
2554

L
Linus Torvalds 已提交
2555 2556 2557
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2558
	page = vmf.page;
2559
	if (flags & FAULT_FLAG_WRITE) {
2560
		if (!(vma->vm_flags & VM_SHARED)) {
2561
			anon = 1;
2562
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2563
				ret = VM_FAULT_OOM;
2564
				goto out;
2565
			}
N
Nick Piggin 已提交
2566 2567
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2568
			if (!page) {
N
Nick Piggin 已提交
2569
				ret = VM_FAULT_OOM;
2570
				goto out;
2571
			}
2572 2573 2574 2575 2576 2577
			if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2578 2579 2580 2581 2582 2583
			/*
			 * Don't let another task, with possibly unlocked vma,
			 * keep the mlocked page.
			 */
			if (vma->vm_flags & VM_LOCKED)
				clear_page_mlock(vmf.page);
N
Nick Piggin 已提交
2584
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2585
			__SetPageUptodate(page);
2586
		} else {
2587 2588
			/*
			 * If the page will be shareable, see if the backing
2589
			 * address space wants to know that the page is about
2590 2591
			 * to become writable
			 */
2592 2593 2594
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2595 2596
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2597 2598 2599
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2600 2601 2602 2603 2604 2605 2606 2607
				/*
				 * 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
2608
					ret = 0;
N
Nick Piggin 已提交
2609 2610 2611
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2612
				page_mkwrite = 1;
2613 2614
			}
		}
2615

L
Linus Torvalds 已提交
2616 2617
	}

2618
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630

	/*
	 * 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... */
2631
	if (likely(pte_same(*page_table, orig_pte))) {
2632 2633
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2634
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2635 2636
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2637 2638
			inc_mm_counter(mm, anon_rss);
			page_add_new_anon_rmap(page, vma, address);
2639
		} else {
2640
			inc_mm_counter(mm, file_rss);
2641
			page_add_file_rmap(page);
2642
			if (flags & FAULT_FLAG_WRITE) {
2643
				dirty_page = page;
2644 2645
				get_page(dirty_page);
			}
2646
		}
2647
		set_pte_at(mm, address, page_table, entry);
2648 2649 2650

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2651
	} else {
2652 2653
		if (charged)
			mem_cgroup_uncharge_page(page);
2654 2655 2656
		if (anon)
			page_cache_release(page);
		else
2657
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2658 2659
	}

2660
	pte_unmap_unlock(page_table, ptl);
2661 2662

out:
N
Nick Piggin 已提交
2663
	unlock_page(vmf.page);
2664
out_unlocked:
2665
	if (anon)
N
Nick Piggin 已提交
2666
		page_cache_release(vmf.page);
2667
	else if (dirty_page) {
2668 2669 2670
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2671
		set_page_dirty_balance(dirty_page, page_mkwrite);
2672 2673
		put_page(dirty_page);
	}
2674

N
Nick Piggin 已提交
2675
	return ret;
2676
}
2677

2678 2679 2680 2681 2682
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)
2683
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2684 2685
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2686 2687
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2688 2689
}

L
Linus Torvalds 已提交
2690 2691 2692 2693
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2694 2695 2696 2697
 *
 * 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
2698
 */
N
Nick Piggin 已提交
2699
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2700 2701
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2702
{
N
Nick Piggin 已提交
2703 2704
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2705
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2706

H
Hugh Dickins 已提交
2707
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2708
		return 0;
L
Linus Torvalds 已提交
2709

N
Nick Piggin 已提交
2710 2711
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2712 2713 2714
		/*
		 * Page table corrupted: show pte and kill process.
		 */
2715
		print_bad_pte(vma, address, orig_pte, NULL);
2716 2717 2718 2719
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2720
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731
}

/*
 * 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
2732 2733 2734
 * 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
2735 2736
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2737 2738
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2739 2740
{
	pte_t entry;
2741
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2742

2743
	entry = *pte;
L
Linus Torvalds 已提交
2744
	if (!pte_present(entry)) {
2745
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2746
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2747
				if (likely(vma->vm_ops->fault))
2748 2749
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2750 2751 2752
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2753
		}
L
Linus Torvalds 已提交
2754
		if (pte_file(entry))
N
Nick Piggin 已提交
2755
			return do_nonlinear_fault(mm, vma, address,
2756 2757 2758
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2759 2760
	}

H
Hugh Dickins 已提交
2761
	ptl = pte_lockptr(mm, pmd);
2762 2763 2764
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2765 2766
	if (write_access) {
		if (!pte_write(entry))
2767 2768
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2769 2770 2771
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2772
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783
		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);
	}
2784 2785
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2786
	return 0;
L
Linus Torvalds 已提交
2787 2788 2789 2790 2791
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2792
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2793 2794 2795 2796 2797 2798 2799 2800 2801
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2802
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2803

2804 2805
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2806 2807 2808 2809

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2810
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2811 2812
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2813
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2814 2815
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2816
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2817

H
Hugh Dickins 已提交
2818
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2819 2820 2821 2822 2823
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2824
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2825
 */
2826
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2827
{
H
Hugh Dickins 已提交
2828 2829
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2830
		return -ENOMEM;
L
Linus Torvalds 已提交
2831

2832 2833
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2834
	spin_lock(&mm->page_table_lock);
2835
	if (pgd_present(*pgd))		/* Another has populated it */
2836
		pud_free(mm, new);
2837 2838
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2839
	spin_unlock(&mm->page_table_lock);
2840
	return 0;
L
Linus Torvalds 已提交
2841 2842 2843 2844 2845 2846
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2847
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2848
 */
2849
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2850
{
H
Hugh Dickins 已提交
2851 2852
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2853
		return -ENOMEM;
L
Linus Torvalds 已提交
2854

2855 2856
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2857
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2858
#ifndef __ARCH_HAS_4LEVEL_HACK
2859
	if (pud_present(*pud))		/* Another has populated it */
2860
		pmd_free(mm, new);
2861 2862
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2863
#else
2864
	if (pgd_present(*pud))		/* Another has populated it */
2865
		pmd_free(mm, new);
2866 2867
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2868
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2869
	spin_unlock(&mm->page_table_lock);
2870
	return 0;
2871
}
L
Linus Torvalds 已提交
2872 2873 2874 2875 2876 2877 2878 2879 2880
#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)
K
KOSAKI Motohiro 已提交
2881
		return -ENOMEM;
L
Linus Torvalds 已提交
2882
	write = (vma->vm_flags & VM_WRITE) != 0;
2883 2884
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2885
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2886 2887
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
2888
	if (ret < 0)
L
Linus Torvalds 已提交
2889
		return ret;
2890
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
2891 2892 2893 2894 2895
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2896
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2897 2898 2899 2900 2901 2902

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
2903 2904
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2905 2906 2907 2908 2909 2910 2911
	/*
	 * 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
2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935
	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 */
2936

2937
#ifdef CONFIG_HAVE_IOREMAP_PROT
2938 2939 2940
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
2941 2942 2943 2944 2945 2946 2947 2948
{
	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;
2949
	int ret = -EINVAL;
2950

2951 2952
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
2953 2954 2955

	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
2956
		goto out;
2957 2958 2959

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
2960
		goto out;
2961 2962 2963

	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
2964
		goto out;
2965 2966 2967

	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
	if (pmd_huge(*pmd))
2968
		goto out;
2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982

	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));
2983 2984
	*phys = phys_addr;
	ret = 0;
2985 2986 2987 2988

unlock:
	pte_unmap_unlock(ptep, ptl);
out:
2989
	return ret;
2990 2991 2992 2993 2994 2995 2996
}

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;
K
KOSAKI Motohiro 已提交
2997
	void __iomem *maddr;
2998 2999
	int offset = addr & (PAGE_SIZE-1);

3000
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013
		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

3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029
/*
 * 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
3030
	/* ignore errors, just check how much was successfully transferred */
3031 3032 3033
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3034
		struct page *page = NULL;
3035 3036 3037

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053
		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;
3054
		} else {
3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070
			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);
3071 3072 3073 3074 3075 3076 3077 3078 3079 3080
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
3081 3082 3083 3084 3085 3086 3087 3088 3089

/*
 * 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;

3090 3091 3092 3093 3094 3095 3096
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3097 3098 3099 3100 3101 3102 3103 3104
	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;

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			p = d_path(&f->f_path, buf, PAGE_SIZE);
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			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);
}
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#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
	might_sleep();
	/*
	 * it would be nicer only to annotate paths which are not under
	 * pagefault_disable, however that requires a larger audit and
	 * providing helpers like get_user_atomic.
	 */
	if (!in_atomic() && current->mm)
		might_lock_read(&current->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);
#endif