memory.c 90.9 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;
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	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

	/*
	 * Allow a burst of 60 reports, then keep quiet for that minute;
	 * or allow a steady drip of one report per second.
	 */
	if (nr_shown == 60) {
		if (time_before(jiffies, resume)) {
			nr_unshown++;
			return;
		}
		if (nr_unshown) {
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			printk(KERN_ALERT
				"BUG: Bad page map: %lu messages suppressed\n",
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				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
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	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
	index = linear_page_index(vma, addr);

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	printk(KERN_ALERT
		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
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		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
	if (page) {
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		printk(KERN_ALERT
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		"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);
	}
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	printk(KERN_ALERT
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		"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)
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		print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
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				(unsigned long)vma->vm_ops->fault);
	if (vma->vm_file && vma->vm_file->f_op)
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		print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
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				(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);
			}
564 565 566 567 568 569 570 571 572 573
			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);
			}
L
Linus Torvalds 已提交
574
		}
575
		goto out_set_pte;
L
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576 577 578 579 580 581
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
582
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
583
		ptep_set_wrprotect(src_mm, addr, src_pte);
584
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
585 586 587 588 589 590 591 592 593
	}

	/*
	 * 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);
594 595 596 597

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
N
Nick Piggin 已提交
598
		page_dup_rmap(page, vma, addr);
599 600
		rss[!!PageAnon(page)]++;
	}
601 602 603

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
611
	spinlock_t *src_ptl, *dst_ptl;
612
	int progress = 0;
H
Hugh Dickins 已提交
613
	int rss[2];
L
Linus Torvalds 已提交
614 615

again:
616
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
617
	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
621
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
622
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
623
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
624 625 626 627 628 629

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
630 631 632
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
633
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
634 635
				break;
		}
L
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636 637 638 639
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
640
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
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		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

644
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
645
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
646
	pte_unmap_nested(src_pte - 1);
647
	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();
L
Linus Torvalds 已提交
650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705
	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
706
	int ret;
L
Linus Torvalds 已提交
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708 709 710 711 712 713
	/*
	 * 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.
	 */
714
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
715 716 717 718
		if (!vma->anon_vma)
			return 0;
	}

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

722
	if (unlikely(is_pfn_mapping(vma))) {
723 724 725 726 727 728 729 730 731
		/*
		 * 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;
	}

A
Andrea Arcangeli 已提交
732 733 734 735 736 737 738 739 740 741
	/*
	 * 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
742 743 744 745 746 747
	dst_pgd = pgd_offset(dst_mm, addr);
	src_pgd = pgd_offset(src_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(src_pgd))
			continue;
A
Andrea Arcangeli 已提交
748 749 750 751 752
		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
753
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
754 755 756 757 758

	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_end(src_mm,
						  vma->vm_start, end);
	return ret;
L
Linus Torvalds 已提交
759 760
}

761
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
762
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
763
				unsigned long addr, unsigned long end,
764
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
765
{
N
Nick Piggin 已提交
766
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
767
	pte_t *pte;
768
	spinlock_t *ptl;
769 770
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
771

772
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
773
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
774 775
	do {
		pte_t ptent = *pte;
776 777
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
778
			continue;
779
		}
780 781 782

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
783
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
784
			struct page *page;
785

786
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804
			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
805
			ptent = ptep_get_and_clear_full(mm, addr, pte,
806
							tlb->fullmm);
L
Linus Torvalds 已提交
807 808 809 810 811 812
			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
813
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
814 815
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
816
				anon_rss--;
817 818 819
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
820 821
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
822
					mark_page_accessed(page);
H
Hugh Dickins 已提交
823
				file_rss--;
824
			}
825
			page_remove_rmap(page);
826 827
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
L
Linus Torvalds 已提交
828 829 830 831 832 833 834 835 836
			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;
837 838 839 840 841 842
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
		} else if
		  (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
			print_bad_pte(vma, addr, ptent, NULL);
843
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
844
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
845

H
Hugh Dickins 已提交
846
	add_mm_rss(mm, file_rss, anon_rss);
847
	arch_leave_lazy_mmu_mode();
848
	pte_unmap_unlock(pte - 1, ptl);
849 850

	return addr;
L
Linus Torvalds 已提交
851 852
}

853
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
854
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
855
				unsigned long addr, unsigned long end,
856
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
857 858 859 860 861 862 863
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
864 865
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
866
			continue;
867 868 869 870 871 872
		}
		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
873 874
}

875
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
876
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
877
				unsigned long addr, unsigned long end,
878
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
879 880 881 882 883 884 885
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
886 887
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
888
			continue;
889 890 891 892 893 894
		}
		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
895 896
}

897 898
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
899
				unsigned long addr, unsigned long end,
900
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
901 902 903 904 905 906 907 908 909 910 911 912
{
	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);
913 914
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
915
			continue;
916 917 918 919
		}
		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
920
	tlb_end_vma(tlb, vma);
921 922

	return addr;
L
Linus Torvalds 已提交
923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940
}

#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
 *
941
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
942
 *
943
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
944
 *
945 946
 * 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
947 948 949 950 951 952 953 954 955 956 957
 * 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.
 */
958
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
959 960 961 962
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
963
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
964 965
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
966
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
967
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
968
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
969
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
970

A
Andrea Arcangeli 已提交
971
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
972 973 974 975 976 977 978 979 980 981 982 983 984
	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;

985
		if (unlikely(is_pfn_mapping(vma)))
986 987
			untrack_pfn_vma(vma, 0, 0);

L
Linus Torvalds 已提交
988 989 990 991 992 993
		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

994
			if (unlikely(is_vm_hugetlb_page(vma))) {
995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008
				/*
				 * 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) /
1009
					pages_per_huge_page(hstate_vma(vma));
1010 1011
				}

1012 1013 1014 1015 1016 1017 1018 1019
				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
1020 1021 1022 1023 1024
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
1025
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
1026
				if (i_mmap_lock) {
1027
					*tlbp = NULL;
L
Linus Torvalds 已提交
1028 1029 1030 1031 1032
					goto out;
				}
				cond_resched();
			}

1033
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
1034
			tlb_start_valid = 0;
1035
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1036 1037 1038
		}
	}
out:
A
Andrea Arcangeli 已提交
1039
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1040
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
1041 1042 1043 1044 1045 1046 1047 1048 1049
}

/**
 * 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
 */
1050
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1051 1052 1053 1054 1055 1056 1057 1058 1059
		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);
1060
	update_hiwater_rss(mm);
1061 1062 1063
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1064
	return end;
L
Linus Torvalds 已提交
1065 1066
}

1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089
/**
 * 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
1090 1091 1092
/*
 * Do a quick page-table lookup for a single page.
 */
1093
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1094
			unsigned int flags)
L
Linus Torvalds 已提交
1095 1096 1097 1098 1099
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1100
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1101
	struct page *page;
1102
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1103

1104 1105 1106 1107 1108
	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
1109

1110
	page = NULL;
L
Linus Torvalds 已提交
1111 1112
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1113
		goto no_page_table;
L
Linus Torvalds 已提交
1114 1115

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1116
	if (pud_none(*pud))
1117
		goto no_page_table;
A
Andi Kleen 已提交
1118 1119 1120 1121 1122 1123 1124 1125
	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
1126
	pmd = pmd_offset(pud, address);
1127
	if (pmd_none(*pmd))
1128 1129 1130 1131
		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
1132
		goto out;
1133
	}
1134 1135 1136
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1137
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1138 1139

	pte = *ptep;
1140
	if (!pte_present(pte))
1141
		goto no_page;
1142 1143
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
1144 1145
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
1146
		goto bad_page;
L
Linus Torvalds 已提交
1147

1148 1149 1150 1151 1152 1153
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
1154 1155 1156 1157 1158
		/*
		 * pte_mkyoung() would be more correct here, but atomic care
		 * is needed to avoid losing the dirty bit: it is easier to use
		 * mark_page_accessed().
		 */
1159 1160 1161 1162
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1163
out:
1164
	return page;
L
Linus Torvalds 已提交
1165

1166 1167 1168 1169 1170 1171 1172 1173 1174
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 */
1175 1176 1177 1178 1179 1180
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
1181
		page = ZERO_PAGE(0);
1182 1183 1184 1185 1186
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1187 1188
}

1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201
/* 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
1202
	 * And if we have a fault routine, it's not an anonymous region.
1203
	 */
N
Nick Piggin 已提交
1204
	return !vma->vm_ops || !vma->vm_ops->fault;
1205 1206
}

N
Nick Piggin 已提交
1207 1208 1209 1210


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
1211 1212 1213
		struct page **pages, struct vm_area_struct **vmas)
{
	int i;
N
Nick Piggin 已提交
1214 1215 1216 1217
	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);
1218
	int ignore_sigkill = !!(flags & GUP_FLAGS_IGNORE_SIGKILL);
L
Linus Torvalds 已提交
1219

1220 1221
	if (len <= 0)
		return 0;
L
Linus Torvalds 已提交
1222 1223 1224 1225
	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
1226 1227
	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
1228 1229 1230
	i = 0;

	do {
1231 1232
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
1233 1234 1235 1236 1237 1238 1239 1240 1241

		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
1242 1243 1244

			/* user gate pages are read-only */
			if (!ignore && write)
L
Linus Torvalds 已提交
1245 1246 1247 1248 1249 1250 1251 1252 1253
				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);
1254 1255
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1256
			pte = pte_offset_map(pmd, pg);
1257 1258 1259 1260
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1261
			if (pages) {
1262
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1263 1264 1265
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1266 1267 1268 1269 1270 1271 1272 1273 1274 1275
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

N
Nick Piggin 已提交
1276 1277 1278
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
		    (!ignore && !(vm_flags & vma->vm_flags)))
L
Linus Torvalds 已提交
1279 1280 1281 1282
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1283
						&start, &len, i, write);
L
Linus Torvalds 已提交
1284 1285
			continue;
		}
1286 1287 1288 1289

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
1290
		if (!write && use_zero_page(vma))
1291 1292
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1293
		do {
1294
			struct page *page;
L
Linus Torvalds 已提交
1295

1296
			/*
1297 1298 1299 1300 1301
			 * If we have a pending SIGKILL, don't keep faulting
			 * pages and potentially allocating memory, unless
			 * current is handling munlock--e.g., on exit. In
			 * that case, we are not allocating memory.  Rather,
			 * we're only unlocking already resident/mapped pages.
1302
			 */
1303 1304 1305
			if (unlikely(!ignore_sigkill &&
					fatal_signal_pending(current)))
				return i ? i : -ERESTARTSYS;
1306

1307 1308
			if (write)
				foll_flags |= FOLL_WRITE;
1309

1310
			cond_resched();
1311
			while (!(page = follow_page(vma, start, foll_flags))) {
1312
				int ret;
N
Nick Piggin 已提交
1313
				ret = handle_mm_fault(mm, vma, start,
1314
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326
				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++;

1327
				/*
N
Nick Piggin 已提交
1328 1329 1330 1331
				 * 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
1332 1333 1334 1335 1336 1337
				 * 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).
1338
				 */
1339 1340
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1341
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1342

1343
				cond_resched();
L
Linus Torvalds 已提交
1344
			}
1345 1346
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1347
			if (pages) {
1348
				pages[i] = page;
1349

1350
				flush_anon_page(vma, page, start);
1351
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1352 1353 1354 1355 1356 1357
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1358 1359
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1360 1361
	return i;
}
N
Nick Piggin 已提交
1362

1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412
/**
 * get_user_pages() - pin user pages in memory
 * @tsk:	task_struct of target task
 * @mm:		mm_struct of target mm
 * @start:	starting user address
 * @len:	number of pages from start to pin
 * @write:	whether pages will be written to by the caller
 * @force:	whether to force write access even if user mapping is
 *		readonly. This will result in the page being COWed even
 *		in MAP_SHARED mappings. You do not want this.
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long. Or NULL, if caller
 *		only intends to ensure the pages are faulted in.
 * @vmas:	array of pointers to vmas corresponding to each page.
 *		Or NULL if the caller does not require them.
 *
 * Returns number of pages pinned. This may be fewer than the number
 * requested. If len is 0 or negative, returns 0. If no pages
 * were pinned, returns -errno. Each page returned must be released
 * with a put_page() call when it is finished with. vmas will only
 * remain valid while mmap_sem is held.
 *
 * Must be called with mmap_sem held for read or write.
 *
 * get_user_pages walks a process's page tables and takes a reference to
 * each struct page that each user address corresponds to at a given
 * instant. That is, it takes the page that would be accessed if a user
 * thread accesses the given user virtual address at that instant.
 *
 * This does not guarantee that the page exists in the user mappings when
 * get_user_pages returns, and there may even be a completely different
 * page there in some cases (eg. if mmapped pagecache has been invalidated
 * and subsequently re faulted). However it does guarantee that the page
 * won't be freed completely. And mostly callers simply care that the page
 * contains data that was valid *at some point in time*. Typically, an IO
 * or similar operation cannot guarantee anything stronger anyway because
 * locks can't be held over the syscall boundary.
 *
 * If write=0, the page must not be written to. If the page is written to,
 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
 * after the page is finished with, and before put_page is called.
 *
 * get_user_pages is typically used for fewer-copy IO operations, to get a
 * handle on the memory by some means other than accesses via the user virtual
 * addresses. The pages may be submitted for DMA to devices or accessed via
 * their kernel linear mapping (via the kmap APIs). Care should be taken to
 * use the correct cache flushing APIs.
 *
 * See also get_user_pages_fast, for performance critical applications.
 */
N
Nick Piggin 已提交
1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428
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
1429 1430
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1431 1432
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1433 1434 1435 1436
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1437
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1438 1439 1440 1441 1442 1443
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1444 1445 1446 1447 1448 1449 1450
/*
 * 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
1451 1452
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1453
{
N
Nick Piggin 已提交
1454
	struct mm_struct *mm = vma->vm_mm;
1455
	int retval;
1456
	pte_t *pte;
1457 1458
	spinlock_t *ptl;

1459
	retval = -EINVAL;
1460
	if (PageAnon(page))
1461
		goto out;
1462 1463
	retval = -ENOMEM;
	flush_dcache_page(page);
1464
	pte = get_locked_pte(mm, addr, &ptl);
1465
	if (!pte)
1466
		goto out;
1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477
	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;
1478 1479
	pte_unmap_unlock(pte, ptl);
	return retval;
1480 1481 1482 1483 1484 1485
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1486 1487 1488 1489 1490 1491
/**
 * 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
 *
1492 1493 1494 1495 1496 1497
 * 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
1498
 * (see split_page()).
1499 1500 1501 1502 1503 1504 1505 1506 1507
 *
 * 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
1508 1509
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1510 1511 1512 1513 1514
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1515
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1516
	return insert_page(vma, addr, page, vma->vm_page_prot);
1517
}
1518
EXPORT_SYMBOL(vm_insert_page);
1519

N
Nick Piggin 已提交
1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547
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
1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558
/**
 * 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
1559 1560 1561 1562 1563
 *
 * 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
1564 1565
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1566
			unsigned long pfn)
N
Nick Piggin 已提交
1567
{
1568
	int ret;
1569
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1570 1571 1572 1573 1574 1575
	/*
	 * 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
1576 1577 1578 1579 1580
	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
1581

N
Nick Piggin 已提交
1582 1583
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1584
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1585 1586
		return -EINVAL;

1587
	ret = insert_pfn(vma, addr, pfn, pgprot);
1588 1589 1590 1591 1592

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

	return ret;
N
Nick Piggin 已提交
1593 1594
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1595

N
Nick Piggin 已提交
1596 1597 1598 1599
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
1600

N
Nick Piggin 已提交
1601 1602
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1603

N
Nick Piggin 已提交
1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616
	/*
	 * 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
1617
}
N
Nick Piggin 已提交
1618
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1619

L
Linus Torvalds 已提交
1620 1621 1622 1623 1624 1625 1626 1627 1628 1629
/*
 * 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
1630
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1631

H
Hugh Dickins 已提交
1632
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1633 1634
	if (!pte)
		return -ENOMEM;
1635
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1636 1637
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1638
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1639 1640
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1641
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1642
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685
	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;
}

1686 1687 1688 1689 1690 1691 1692 1693 1694 1695
/**
 * 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
1696 1697 1698 1699 1700
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;
1701
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1702 1703 1704 1705 1706 1707 1708 1709
	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
1710 1711 1712 1713 1714
	 *   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.
1715 1716 1717
	 *   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
1718 1719 1720 1721
	 *
	 * 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
1722
	 */
1723
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
1724
		vma->vm_pgoff = pfn;
1725
		vma->vm_flags |= VM_PFN_AT_MMAP;
1726
	} else if (is_cow_mapping(vma->vm_flags))
1727
		return -EINVAL;
L
Linus Torvalds 已提交
1728

1729
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1730

1731
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1732 1733 1734 1735 1736 1737
	if (err) {
		/*
		 * To indicate that track_pfn related cleanup is not
		 * needed from higher level routine calling unmap_vmas
		 */
		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
1738
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
1739
		return -EINVAL;
1740
	}
1741

L
Linus Torvalds 已提交
1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752
	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);
1753 1754 1755 1756

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

L
Linus Torvalds 已提交
1757 1758 1759 1760
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1761 1762 1763 1764 1765 1766
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;
1767
	pgtable_t token;
1768
	spinlock_t *uninitialized_var(ptl);
1769 1770 1771 1772 1773 1774 1775 1776 1777

	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));

1778 1779
	arch_enter_lazy_mmu_mode();

1780
	token = pmd_pgtable(*pmd);
1781 1782

	do {
1783
		err = fn(pte, token, addr, data);
1784 1785 1786 1787
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

1788 1789
	arch_leave_lazy_mmu_mode();

1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802
	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
1803 1804
	BUG_ON(pud_huge(*pud));

1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845
	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
1846
	unsigned long start = addr, end = addr + size;
1847 1848 1849
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1850
	mmu_notifier_invalidate_range_start(mm, start, end);
1851 1852 1853 1854 1855 1856 1857
	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
1858
	mmu_notifier_invalidate_range_end(mm, start, end);
1859 1860 1861 1862
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1863 1864 1865 1866 1867 1868 1869 1870 1871
/*
 * 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
1872
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1873 1874 1875 1876 1877
				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
1878 1879
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1880
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1881
		spin_unlock(ptl);
1882 1883 1884 1885 1886 1887
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900
/*
 * 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;
}

1901
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1902 1903 1904 1905 1906 1907 1908 1909 1910
{
	/*
	 * 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
1911 1912 1913 1914 1915 1916 1917 1918 1919
		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))
1920 1921
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1922
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1923 1924
	} else
		copy_user_highpage(dst, src, va, vma);
1925 1926
}

L
Linus Torvalds 已提交
1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940
/*
 * 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.
 *
1941 1942 1943
 * 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
1944
 */
1945 1946
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1947
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1948
{
1949
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1950
	pte_t entry;
N
Nick Piggin 已提交
1951
	int reuse = 0, ret = 0;
1952
	int page_mkwrite = 0;
1953
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1954

1955
	old_page = vm_normal_page(vma, address, orig_pte);
1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966
	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;
1967
		goto gotten;
1968
	}
L
Linus Torvalds 已提交
1969

1970
	/*
P
Peter Zijlstra 已提交
1971 1972
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1973
	 */
P
Peter Zijlstra 已提交
1974
	if (PageAnon(old_page)) {
1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986
		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
1987
		}
1988
		reuse = reuse_swap_page(old_page);
1989
		unlock_page(old_page);
P
Peter Zijlstra 已提交
1990
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1991
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1992 1993 1994 1995 1996
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1997
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1998 1999 2000 2001 2002 2003 2004 2005 2006
			struct vm_fault vmf;
			int tmp;

			vmf.virtual_address = (void __user *)(address &
								PAGE_MASK);
			vmf.pgoff = old_page->index;
			vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
			vmf.page = old_page;

2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
			/*
			 * 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);

2018 2019 2020 2021
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2022
				goto unwritable_page;
2023
			}
N
Nick Piggin 已提交
2024 2025 2026 2027 2028 2029 2030 2031 2032
			if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
				lock_page(old_page);
				if (!old_page->mapping) {
					ret = 0; /* retry the fault */
					unlock_page(old_page);
					goto unwritable_page;
				}
			} else
				VM_BUG_ON(!PageLocked(old_page));
2033 2034 2035 2036 2037 2038 2039 2040 2041

			/*
			 * 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);
N
Nick Piggin 已提交
2042 2043 2044
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
2045
				goto unlock;
N
Nick Piggin 已提交
2046
			}
2047 2048

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2049
		}
2050 2051
		dirty_page = old_page;
		get_page(dirty_page);
2052 2053 2054 2055
		reuse = 1;
	}

	if (reuse) {
2056
reuse:
2057 2058 2059
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2060
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2061
			update_mmu_cache(vma, address, entry);
2062 2063
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
2064 2065 2066 2067 2068
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2069
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2070
gotten:
2071
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2072 2073

	if (unlikely(anon_vma_prepare(vma)))
2074
		goto oom;
N
Nick Piggin 已提交
2075 2076 2077 2078
	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
2079 2080 2081 2082
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
2083
	if ((vma->vm_flags & VM_LOCKED) && old_page) {
N
Nick Piggin 已提交
2084 2085 2086 2087
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
N
Nick Piggin 已提交
2088
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
2089
	__SetPageUptodate(new_page);
2090

K
KAMEZAWA Hiroyuki 已提交
2091
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2092 2093
		goto oom_free_new;

L
Linus Torvalds 已提交
2094 2095 2096
	/*
	 * Re-check the pte - we dropped the lock
	 */
2097
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2098
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2099 2100 2101 2102 2103 2104
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
2105
			inc_mm_counter(mm, anon_rss);
2106
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2107 2108
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2109 2110 2111 2112 2113 2114
		/*
		 * 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
2115
		ptep_clear_flush_notify(vma, address, page_table);
N
Nick Piggin 已提交
2116
		page_add_new_anon_rmap(new_page, vma, address);
2117 2118
		set_pte_at(mm, address, page_table, entry);
		update_mmu_cache(vma, address, entry);
N
Nick Piggin 已提交
2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141
		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.
			 */
2142
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2143 2144
		}

L
Linus Torvalds 已提交
2145 2146
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2147
		ret |= VM_FAULT_WRITE;
2148 2149 2150
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2151 2152 2153 2154
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
2155
unlock:
2156
	pte_unmap_unlock(page_table, ptl);
2157
	if (dirty_page) {
2158 2159 2160 2161 2162 2163 2164 2165
		/*
		 * 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.
		 */
N
Nick Piggin 已提交
2166 2167 2168 2169
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
		}
2170
		put_page(dirty_page);
N
Nick Piggin 已提交
2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188
		if (page_mkwrite) {
			struct address_space *mapping = dirty_page->mapping;

			set_page_dirty(dirty_page);
			unlock_page(dirty_page);
			page_cache_release(dirty_page);
			if (mapping)	{
				/*
				 * Some device drivers do not set page.mapping
				 * but still dirty their pages
				 */
				balance_dirty_pages_ratelimited(mapping);
			}
		}

		/* file_update_time outside page_lock */
		if (vma->vm_file)
			file_update_time(vma->vm_file);
2189
	}
N
Nick Piggin 已提交
2190
	return ret;
2191
oom_free_new:
2192
	page_cache_release(new_page);
2193
oom:
N
Nick Piggin 已提交
2194 2195 2196 2197 2198
	if (old_page) {
		if (page_mkwrite) {
			unlock_page(old_page);
			page_cache_release(old_page);
		}
H
Hugh Dickins 已提交
2199
		page_cache_release(old_page);
N
Nick Piggin 已提交
2200
	}
L
Linus Torvalds 已提交
2201
	return VM_FAULT_OOM;
2202 2203 2204

unwritable_page:
	page_cache_release(old_page);
2205
	return ret;
L
Linus Torvalds 已提交
2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232
}

/*
 * 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
2233
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259
 * 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;

2260 2261
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2262
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2263 2264
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2265 2266
	 */

L
Linus Torvalds 已提交
2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277
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;
		}
	}

2278 2279
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2280
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2281

2282
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2283 2284 2285 2286 2287 2288
		/* 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 */
2289
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355
		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;
	}
}

/**
2356
 * 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
2357
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393
 * @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);

2394
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410
	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);

2411 2412 2413 2414
/**
 * 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
2415 2416 2417 2418 2419 2420 2421
 *
 * 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
2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432
	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
2433

C
Christoph Hellwig 已提交
2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455
		/*
		 * 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);
	}
2456

A
Al Viro 已提交
2457
	if (inode->i_op->truncate)
L
Linus Torvalds 已提交
2458 2459
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2460

L
Linus Torvalds 已提交
2461 2462 2463 2464 2465 2466 2467
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2468 2469 2470 2471 2472 2473 2474 2475 2476
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
2477
	if (!inode->i_op->truncate_range)
2478 2479
		return -ENOSYS;

2480
	mutex_lock(&inode->i_mutex);
2481 2482 2483
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2484
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2485 2486
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2487
	mutex_unlock(&inode->i_mutex);
2488 2489 2490 2491

	return 0;
}

L
Linus Torvalds 已提交
2492
/*
2493 2494 2495
 * 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
2496
 */
2497 2498 2499
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
2500
{
2501
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2502
	struct page *page;
2503
	swp_entry_t entry;
L
Linus Torvalds 已提交
2504
	pte_t pte;
2505
	struct mem_cgroup *ptr = NULL;
N
Nick Piggin 已提交
2506
	int ret = 0;
L
Linus Torvalds 已提交
2507

H
Hugh Dickins 已提交
2508
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2509
		goto out;
2510 2511

	entry = pte_to_swp_entry(orig_pte);
2512 2513 2514 2515
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2516
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2517 2518
	page = lookup_swap_cache(entry);
	if (!page) {
2519
		grab_swap_token(); /* Contend for token _before_ read-in */
2520 2521
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2522 2523
		if (!page) {
			/*
2524 2525
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2526
			 */
2527
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2528 2529
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2530
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2531
			goto unlock;
L
Linus Torvalds 已提交
2532 2533 2534 2535
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2536
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2537 2538
	}

2539 2540 2541
	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

K
KAMEZAWA Hiroyuki 已提交
2542
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2543
		ret = VM_FAULT_OOM;
2544
		goto out_page;
2545 2546
	}

L
Linus Torvalds 已提交
2547
	/*
2548
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2549
	 */
2550
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2551
	if (unlikely(!pte_same(*page_table, orig_pte)))
2552 2553 2554 2555 2556
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2557 2558
	}

2559 2560 2561 2562 2563 2564 2565 2566
	/*
	 * The page isn't present yet, go ahead with the fault.
	 *
	 * Be careful about the sequence of operations here.
	 * To get its accounting right, reuse_swap_page() must be called
	 * while the page is counted on swap but not yet in mapcount i.e.
	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
	 * must be called after the swap_free(), or it will never succeed.
2567 2568 2569 2570
	 * Because delete_from_swap_page() may be called by reuse_swap_page(),
	 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
	 * in page->private. In this case, a record in swap_cgroup  is silently
	 * discarded at swap_free().
2571
	 */
L
Linus Torvalds 已提交
2572

2573
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2574
	pte = mk_pte(page, vma->vm_page_prot);
2575
	if (write_access && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2576 2577 2578 2579 2580 2581
		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);
2582 2583
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
2584

2585
	swap_free(entry);
N
Nick Piggin 已提交
2586
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2587
		try_to_free_swap(page);
2588 2589
	unlock_page(page);

L
Linus Torvalds 已提交
2590
	if (write_access) {
2591 2592 2593
		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
2594 2595 2596 2597 2598
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2599
unlock:
2600
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2601 2602
out:
	return ret;
2603
out_nomap:
2604
	mem_cgroup_cancel_charge_swapin(ptr);
2605
	pte_unmap_unlock(page_table, ptl);
2606
out_page:
2607 2608
	unlock_page(page);
	page_cache_release(page);
2609
	return ret;
L
Linus Torvalds 已提交
2610 2611 2612
}

/*
2613 2614 2615
 * 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
2616
 */
2617 2618 2619
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
2620
{
2621 2622
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2623 2624
	pte_t entry;

N
Nick Piggin 已提交
2625 2626
	/* Allocate our own private page. */
	pte_unmap(page_table);
2627

N
Nick Piggin 已提交
2628 2629 2630 2631 2632
	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
2633
	__SetPageUptodate(page);
2634

K
KAMEZAWA Hiroyuki 已提交
2635
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2636 2637
		goto oom_free_page;

N
Nick Piggin 已提交
2638 2639
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2640

N
Nick Piggin 已提交
2641 2642 2643 2644 2645
	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);
2646
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2647 2648

	/* No need to invalidate - it was non-present before */
2649 2650
	update_mmu_cache(vma, address, entry);
unlock:
2651
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2652
	return 0;
2653
release:
2654
	mem_cgroup_uncharge_page(page);
2655 2656
	page_cache_release(page);
	goto unlock;
2657
oom_free_page:
2658
	page_cache_release(page);
2659
oom:
L
Linus Torvalds 已提交
2660 2661 2662 2663
	return VM_FAULT_OOM;
}

/*
2664
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2665
 * tries to share with existing pages, but makes a separate copy if
2666 2667
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2668 2669 2670 2671
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2672
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2673
 * but allow concurrent faults), and pte neither mapped nor locked.
2674
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2675
 */
2676
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2677
		unsigned long address, pmd_t *pmd,
2678
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2679
{
2680
	pte_t *page_table;
2681
	spinlock_t *ptl;
N
Nick Piggin 已提交
2682
	struct page *page;
L
Linus Torvalds 已提交
2683 2684
	pte_t entry;
	int anon = 0;
2685
	int charged = 0;
2686
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2687 2688
	struct vm_fault vmf;
	int ret;
2689
	int page_mkwrite = 0;
2690

N
Nick Piggin 已提交
2691 2692 2693 2694
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2695

N
Nick Piggin 已提交
2696 2697 2698
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2699

2700
	/*
N
Nick Piggin 已提交
2701
	 * For consistency in subsequent calls, make the faulted page always
2702 2703
	 * locked.
	 */
N
Nick Piggin 已提交
2704
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2705
		lock_page(vmf.page);
2706
	else
N
Nick Piggin 已提交
2707
		VM_BUG_ON(!PageLocked(vmf.page));
2708

L
Linus Torvalds 已提交
2709 2710 2711
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2712
	page = vmf.page;
2713
	if (flags & FAULT_FLAG_WRITE) {
2714
		if (!(vma->vm_flags & VM_SHARED)) {
2715
			anon = 1;
2716
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2717
				ret = VM_FAULT_OOM;
2718
				goto out;
2719
			}
N
Nick Piggin 已提交
2720 2721
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2722
			if (!page) {
N
Nick Piggin 已提交
2723
				ret = VM_FAULT_OOM;
2724
				goto out;
2725
			}
K
KAMEZAWA Hiroyuki 已提交
2726
			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2727 2728 2729 2730 2731
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2732 2733 2734 2735 2736 2737
			/*
			 * 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
2738
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2739
			__SetPageUptodate(page);
2740
		} else {
2741 2742
			/*
			 * If the page will be shareable, see if the backing
2743
			 * address space wants to know that the page is about
2744 2745
			 * to become writable
			 */
2746
			if (vma->vm_ops->page_mkwrite) {
2747 2748
				int tmp;

2749
				unlock_page(page);
N
Nick Piggin 已提交
2750
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2751 2752 2753 2754
				tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
				if (unlikely(tmp &
					  (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
					ret = tmp;
N
Nick Piggin 已提交
2755
					goto unwritable_page;
N
Nick Piggin 已提交
2756
				}
N
Nick Piggin 已提交
2757 2758 2759 2760 2761 2762 2763 2764 2765
				if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
					lock_page(page);
					if (!page->mapping) {
						ret = 0; /* retry the fault */
						unlock_page(page);
						goto unwritable_page;
					}
				} else
					VM_BUG_ON(!PageLocked(page));
2766
				page_mkwrite = 1;
2767 2768
			}
		}
2769

L
Linus Torvalds 已提交
2770 2771
	}

2772
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784

	/*
	 * 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... */
2785
	if (likely(pte_same(*page_table, orig_pte))) {
2786 2787
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2788
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2789 2790
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2791 2792
			inc_mm_counter(mm, anon_rss);
			page_add_new_anon_rmap(page, vma, address);
2793
		} else {
2794
			inc_mm_counter(mm, file_rss);
2795
			page_add_file_rmap(page);
2796
			if (flags & FAULT_FLAG_WRITE) {
2797
				dirty_page = page;
2798 2799
				get_page(dirty_page);
			}
2800
		}
2801
		set_pte_at(mm, address, page_table, entry);
2802 2803 2804

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2805
	} else {
2806 2807
		if (charged)
			mem_cgroup_uncharge_page(page);
2808 2809 2810
		if (anon)
			page_cache_release(page);
		else
2811
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2812 2813
	}

2814
	pte_unmap_unlock(page_table, ptl);
2815 2816

out:
N
Nick Piggin 已提交
2817 2818
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
2819

N
Nick Piggin 已提交
2820 2821 2822
		if (set_page_dirty(dirty_page))
			page_mkwrite = 1;
		unlock_page(dirty_page);
2823
		put_page(dirty_page);
N
Nick Piggin 已提交
2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838
		if (page_mkwrite && mapping) {
			/*
			 * Some device drivers do not set page.mapping but still
			 * dirty their pages
			 */
			balance_dirty_pages_ratelimited(mapping);
		}

		/* file_update_time outside page_lock */
		if (vma->vm_file)
			file_update_time(vma->vm_file);
	} else {
		unlock_page(vmf.page);
		if (anon)
			page_cache_release(vmf.page);
2839
	}
2840

N
Nick Piggin 已提交
2841
	return ret;
N
Nick Piggin 已提交
2842 2843 2844 2845

unwritable_page:
	page_cache_release(page);
	return ret;
2846
}
2847

2848 2849 2850 2851 2852
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)
2853
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2854 2855
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2856 2857
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2858 2859
}

L
Linus Torvalds 已提交
2860 2861 2862 2863
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2864 2865 2866 2867
 *
 * 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
2868
 */
N
Nick Piggin 已提交
2869
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2870 2871
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2872
{
N
Nick Piggin 已提交
2873 2874
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2875
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2876

H
Hugh Dickins 已提交
2877
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2878
		return 0;
L
Linus Torvalds 已提交
2879

2880
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2881 2882 2883
		/*
		 * Page table corrupted: show pte and kill process.
		 */
2884
		print_bad_pte(vma, address, orig_pte, NULL);
2885 2886 2887 2888
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2889
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900
}

/*
 * 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
2901 2902 2903
 * 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
2904 2905
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2906 2907
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2908 2909
{
	pte_t entry;
2910
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2911

2912
	entry = *pte;
L
Linus Torvalds 已提交
2913
	if (!pte_present(entry)) {
2914
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2915
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2916
				if (likely(vma->vm_ops->fault))
2917 2918
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2919 2920 2921
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2922
		}
L
Linus Torvalds 已提交
2923
		if (pte_file(entry))
N
Nick Piggin 已提交
2924
			return do_nonlinear_fault(mm, vma, address,
2925 2926 2927
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2928 2929
	}

H
Hugh Dickins 已提交
2930
	ptl = pte_lockptr(mm, pmd);
2931 2932 2933
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2934 2935
	if (write_access) {
		if (!pte_write(entry))
2936 2937
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2938 2939 2940
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2941
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952
		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);
	}
2953 2954
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2955
	return 0;
L
Linus Torvalds 已提交
2956 2957 2958 2959 2960
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2961
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2962 2963 2964 2965 2966 2967 2968 2969 2970
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2971
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2972

2973 2974
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2975 2976 2977 2978

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2979
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2980 2981
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2982
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2983 2984
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2985
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2986

H
Hugh Dickins 已提交
2987
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2988 2989 2990 2991 2992
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2993
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2994
 */
2995
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2996
{
H
Hugh Dickins 已提交
2997 2998
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2999
		return -ENOMEM;
L
Linus Torvalds 已提交
3000

3001 3002
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3003
	spin_lock(&mm->page_table_lock);
3004
	if (pgd_present(*pgd))		/* Another has populated it */
3005
		pud_free(mm, new);
3006 3007
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3008
	spin_unlock(&mm->page_table_lock);
3009
	return 0;
L
Linus Torvalds 已提交
3010 3011 3012 3013 3014 3015
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3016
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3017
 */
3018
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3019
{
H
Hugh Dickins 已提交
3020 3021
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3022
		return -ENOMEM;
L
Linus Torvalds 已提交
3023

3024 3025
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3026
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3027
#ifndef __ARCH_HAS_4LEVEL_HACK
3028
	if (pud_present(*pud))		/* Another has populated it */
3029
		pmd_free(mm, new);
3030 3031
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3032
#else
3033
	if (pgd_present(*pud))		/* Another has populated it */
3034
		pmd_free(mm, new);
3035 3036
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3037
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3038
	spin_unlock(&mm->page_table_lock);
3039
	return 0;
3040
}
L
Linus Torvalds 已提交
3041 3042 3043 3044 3045 3046 3047 3048 3049
#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
3050
		return -ENOMEM;
L
Linus Torvalds 已提交
3051
	write = (vma->vm_flags & VM_WRITE) != 0;
3052 3053
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
3054
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
3055 3056
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
3057
	if (ret < 0)
L
Linus Torvalds 已提交
3058
		return ret;
3059
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
3060 3061 3062 3063 3064
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
3065
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
3066 3067 3068 3069 3070 3071

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
3072 3073
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
3074 3075 3076 3077 3078 3079 3080
	/*
	 * 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
3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104
	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 */
3105

J
Johannes Weiner 已提交
3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142
static int follow_pte(struct mm_struct *mm, unsigned long address,
		pte_t **ptepp, spinlock_t **ptlp)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep;

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

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

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

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

	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
	if (!ptep)
		goto out;
	if (!pte_present(*ptep))
		goto unlock;
	*ptepp = ptep;
	return 0;
unlock:
	pte_unmap_unlock(ptep, *ptlp);
out:
	return -EINVAL;
}

J
Johannes Weiner 已提交
3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171
/**
 * follow_pfn - look up PFN at a user virtual address
 * @vma: memory mapping
 * @address: user virtual address
 * @pfn: location to store found PFN
 *
 * Only IO mappings and raw PFN mappings are allowed.
 *
 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 */
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
	unsigned long *pfn)
{
	int ret = -EINVAL;
	spinlock_t *ptl;
	pte_t *ptep;

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

	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
	if (ret)
		return ret;
	*pfn = pte_pfn(*ptep);
	pte_unmap_unlock(ptep, ptl);
	return 0;
}
EXPORT_SYMBOL(follow_pfn);

3172
#ifdef CONFIG_HAVE_IOREMAP_PROT
3173 3174 3175
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3176
{
3177
	int ret = -EINVAL;
3178 3179 3180
	pte_t *ptep, pte;
	spinlock_t *ptl;

3181 3182
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3183

3184
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3185
		goto out;
3186
	pte = *ptep;
3187

3188 3189 3190 3191
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3192
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3193

3194
	ret = 0;
3195 3196 3197
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3198
	return ret;
3199 3200 3201 3202 3203 3204 3205
}

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
3206
	void __iomem *maddr;
3207 3208
	int offset = addr & (PAGE_SIZE-1);

3209
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222
		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

3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238
/*
 * 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
3239
	/* ignore errors, just check how much was successfully transferred */
3240 3241 3242
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3243
		struct page *page = NULL;
3244 3245 3246

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262
		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;
3263
		} else {
3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279
			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);
3280 3281 3282 3283 3284 3285 3286 3287 3288 3289
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
3290 3291 3292 3293 3294 3295 3296 3297 3298

/*
 * 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;

3299 3300 3301 3302 3303 3304 3305
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3306 3307 3308 3309 3310 3311 3312 3313
	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;

3314
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327
			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);
}
3328 3329 3330 3331

#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
3332 3333 3334 3335 3336 3337 3338 3339 3340
	/*
	 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
	 * holding the mmap_sem, this is safe because kernel memory doesn't
	 * get paged out, therefore we'll never actually fault, and the
	 * below annotations will generate false positives.
	 */
	if (segment_eq(get_fs(), KERNEL_DS))
		return;

3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351
	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