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;
1313 1314 1315

				/* FOLL_WRITE matches FAULT_FLAG_WRITE! */
				ret = handle_mm_fault(mm, vma, start, foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327
				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++;

1328
				/*
N
Nick Piggin 已提交
1329 1330 1331 1332
				 * 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
1333 1334 1335 1336 1337 1338
				 * 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).
1339
				 */
1340 1341
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1342
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1343

1344
				cond_resched();
L
Linus Torvalds 已提交
1345
			}
1346 1347
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1348
			if (pages) {
1349
				pages[i] = page;
1350

1351
				flush_anon_page(vma, page, start);
1352
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1353 1354 1355 1356 1357 1358
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1359 1360
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1361 1362
	return i;
}
N
Nick Piggin 已提交
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 1413
/**
 * 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
1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429
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
1430 1431
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1432 1433
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1434 1435 1436 1437
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1438
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1439 1440 1441 1442 1443 1444
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1445 1446 1447 1448 1449 1450 1451
/*
 * 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
1452 1453
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1454
{
N
Nick Piggin 已提交
1455
	struct mm_struct *mm = vma->vm_mm;
1456
	int retval;
1457
	pte_t *pte;
1458 1459
	spinlock_t *ptl;

1460
	retval = -EINVAL;
1461
	if (PageAnon(page))
1462
		goto out;
1463 1464
	retval = -ENOMEM;
	flush_dcache_page(page);
1465
	pte = get_locked_pte(mm, addr, &ptl);
1466
	if (!pte)
1467
		goto out;
1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478
	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;
1479 1480
	pte_unmap_unlock(pte, ptl);
	return retval;
1481 1482 1483 1484 1485 1486
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1487 1488 1489 1490 1491 1492
/**
 * 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
 *
1493 1494 1495 1496 1497 1498
 * 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
1499
 * (see split_page()).
1500 1501 1502 1503 1504 1505 1506 1507 1508
 *
 * 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
1509 1510
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1511 1512 1513 1514 1515
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1516
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1517
	return insert_page(vma, addr, page, vma->vm_page_prot);
1518
}
1519
EXPORT_SYMBOL(vm_insert_page);
1520

N
Nick Piggin 已提交
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 1548
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
1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559
/**
 * 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
1560 1561 1562 1563 1564
 *
 * 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
1565 1566
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1567
			unsigned long pfn)
N
Nick Piggin 已提交
1568
{
1569
	int ret;
1570
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1571 1572 1573 1574 1575 1576
	/*
	 * 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
1577 1578 1579 1580 1581
	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
1582

N
Nick Piggin 已提交
1583 1584
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1585
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1586 1587
		return -EINVAL;

1588
	ret = insert_pfn(vma, addr, pfn, pgprot);
1589 1590 1591 1592 1593

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

	return ret;
N
Nick Piggin 已提交
1594 1595
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1596

N
Nick Piggin 已提交
1597 1598 1599 1600
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
1601

N
Nick Piggin 已提交
1602 1603
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1604

N
Nick Piggin 已提交
1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617
	/*
	 * 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
1618
}
N
Nick Piggin 已提交
1619
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1620

L
Linus Torvalds 已提交
1621 1622 1623 1624 1625 1626 1627 1628 1629 1630
/*
 * 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
1631
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1632

H
Hugh Dickins 已提交
1633
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1634 1635
	if (!pte)
		return -ENOMEM;
1636
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1637 1638
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1639
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1640 1641
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1642
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1643
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
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 1686
	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;
}

1687 1688 1689 1690 1691 1692 1693 1694 1695 1696
/**
 * 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
1697 1698 1699 1700 1701
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;
1702
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1703 1704 1705 1706 1707 1708 1709 1710
	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
1711 1712 1713 1714 1715
	 *   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.
1716 1717 1718
	 *   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
1719 1720 1721 1722
	 *
	 * 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
1723
	 */
1724
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
1725
		vma->vm_pgoff = pfn;
1726
		vma->vm_flags |= VM_PFN_AT_MMAP;
1727
	} else if (is_cow_mapping(vma->vm_flags))
1728
		return -EINVAL;
L
Linus Torvalds 已提交
1729

1730
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1731

1732
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1733 1734 1735 1736 1737 1738
	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);
1739
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
1740
		return -EINVAL;
1741
	}
1742

L
Linus Torvalds 已提交
1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753
	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);
1754 1755 1756 1757

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

L
Linus Torvalds 已提交
1758 1759 1760 1761
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1762 1763 1764 1765 1766 1767
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;
1768
	pgtable_t token;
1769
	spinlock_t *uninitialized_var(ptl);
1770 1771 1772 1773 1774 1775 1776 1777 1778

	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));

1779 1780
	arch_enter_lazy_mmu_mode();

1781
	token = pmd_pgtable(*pmd);
1782 1783

	do {
1784
		err = fn(pte, token, addr, data);
1785 1786 1787 1788
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

1789 1790
	arch_leave_lazy_mmu_mode();

1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803
	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
1804 1805
	BUG_ON(pud_huge(*pud));

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 1846
	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
1847
	unsigned long start = addr, end = addr + size;
1848 1849 1850
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1851
	mmu_notifier_invalidate_range_start(mm, start, end);
1852 1853 1854 1855 1856 1857 1858
	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
1859
	mmu_notifier_invalidate_range_end(mm, start, end);
1860 1861 1862 1863
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1864 1865 1866 1867 1868 1869 1870 1871 1872
/*
 * 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
1873
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1874 1875 1876 1877 1878
				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
1879 1880
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1881
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1882
		spin_unlock(ptl);
1883 1884 1885 1886 1887 1888
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901
/*
 * 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;
}

1902
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1903 1904 1905 1906 1907 1908 1909 1910 1911
{
	/*
	 * 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
1912 1913 1914 1915 1916 1917 1918 1919 1920
		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))
1921 1922
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1923
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1924 1925
	} else
		copy_user_highpage(dst, src, va, vma);
1926 1927
}

L
Linus Torvalds 已提交
1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941
/*
 * 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.
 *
1942 1943 1944
 * 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
1945
 */
1946 1947
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1948
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1949
{
1950
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1951
	pte_t entry;
N
Nick Piggin 已提交
1952
	int reuse = 0, ret = 0;
1953
	int page_mkwrite = 0;
1954
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1955

1956
	old_page = vm_normal_page(vma, address, orig_pte);
1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967
	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;
1968
		goto gotten;
1969
	}
L
Linus Torvalds 已提交
1970

1971
	/*
P
Peter Zijlstra 已提交
1972 1973
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1974
	 */
P
Peter Zijlstra 已提交
1975
	if (PageAnon(old_page)) {
1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987
		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
1988
		}
1989
		reuse = reuse_swap_page(old_page);
1990
		unlock_page(old_page);
P
Peter Zijlstra 已提交
1991
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1992
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1993 1994 1995 1996 1997
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1998
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1999 2000 2001 2002 2003 2004 2005 2006 2007
			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;

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
			/*
			 * 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);

2019 2020 2021 2022
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2023
				goto unwritable_page;
2024
			}
N
Nick Piggin 已提交
2025 2026 2027 2028 2029 2030 2031 2032 2033
			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));
2034 2035 2036 2037 2038 2039 2040 2041 2042

			/*
			 * 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
2043 2044 2045
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
2046
				goto unlock;
N
Nick Piggin 已提交
2047
			}
2048 2049

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2050
		}
2051 2052
		dirty_page = old_page;
		get_page(dirty_page);
2053 2054 2055 2056
		reuse = 1;
	}

	if (reuse) {
2057
reuse:
2058 2059 2060
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2061
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2062
			update_mmu_cache(vma, address, entry);
2063 2064
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
2065 2066 2067 2068 2069
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2070
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2071
gotten:
2072
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2073 2074

	if (unlikely(anon_vma_prepare(vma)))
2075
		goto oom;
N
Nick Piggin 已提交
2076 2077 2078 2079
	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
2080 2081 2082 2083
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
2084
	if ((vma->vm_flags & VM_LOCKED) && old_page) {
N
Nick Piggin 已提交
2085 2086 2087 2088
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
N
Nick Piggin 已提交
2089
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
2090
	__SetPageUptodate(new_page);
2091

K
KAMEZAWA Hiroyuki 已提交
2092
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2093 2094
		goto oom_free_new;

L
Linus Torvalds 已提交
2095 2096 2097
	/*
	 * Re-check the pte - we dropped the lock
	 */
2098
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2099
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2100 2101 2102 2103 2104 2105
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
2106
			inc_mm_counter(mm, anon_rss);
2107
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2108 2109
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2110 2111 2112 2113 2114 2115
		/*
		 * 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
2116
		ptep_clear_flush_notify(vma, address, page_table);
N
Nick Piggin 已提交
2117
		page_add_new_anon_rmap(new_page, vma, address);
2118 2119
		set_pte_at(mm, address, page_table, entry);
		update_mmu_cache(vma, address, entry);
N
Nick Piggin 已提交
2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142
		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.
			 */
2143
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2144 2145
		}

L
Linus Torvalds 已提交
2146 2147
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2148
		ret |= VM_FAULT_WRITE;
2149 2150 2151
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2152 2153 2154 2155
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
2156
unlock:
2157
	pte_unmap_unlock(page_table, ptl);
2158
	if (dirty_page) {
2159 2160 2161 2162 2163 2164 2165 2166
		/*
		 * 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
2167 2168 2169 2170
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
		}
2171
		put_page(dirty_page);
N
Nick Piggin 已提交
2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189
		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);
2190
	}
N
Nick Piggin 已提交
2191
	return ret;
2192
oom_free_new:
2193
	page_cache_release(new_page);
2194
oom:
N
Nick Piggin 已提交
2195 2196 2197 2198 2199
	if (old_page) {
		if (page_mkwrite) {
			unlock_page(old_page);
			page_cache_release(old_page);
		}
H
Hugh Dickins 已提交
2200
		page_cache_release(old_page);
N
Nick Piggin 已提交
2201
	}
L
Linus Torvalds 已提交
2202
	return VM_FAULT_OOM;
2203 2204 2205

unwritable_page:
	page_cache_release(old_page);
2206
	return ret;
L
Linus Torvalds 已提交
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 2233
}

/*
 * 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
2234
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
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 2260
 * 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;

2261 2262
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2263
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2264 2265
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2266 2267
	 */

L
Linus Torvalds 已提交
2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278
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;
		}
	}

2279 2280
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2281
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2282

2283
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2284 2285 2286 2287 2288 2289
		/* 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 */
2290
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
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 2356
		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;
	}
}

/**
2357
 * 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
2358
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
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 2394
 * @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);

2395
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411
	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);

2412 2413 2414 2415
/**
 * 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
2416 2417 2418 2419 2420 2421 2422
 *
 * 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
2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433
	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
2434

C
Christoph Hellwig 已提交
2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456
		/*
		 * 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);
	}
2457

A
Al Viro 已提交
2458
	if (inode->i_op->truncate)
L
Linus Torvalds 已提交
2459 2460
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2461

L
Linus Torvalds 已提交
2462 2463 2464 2465 2466 2467 2468
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2469 2470 2471 2472 2473 2474 2475 2476 2477
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
2478
	if (!inode->i_op->truncate_range)
2479 2480
		return -ENOSYS;

2481
	mutex_lock(&inode->i_mutex);
2482 2483 2484
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2485
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2486 2487
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2488
	mutex_unlock(&inode->i_mutex);
2489 2490 2491 2492

	return 0;
}

L
Linus Torvalds 已提交
2493
/*
2494 2495 2496
 * 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
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,
2500
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2501
{
2502
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2503
	struct page *page;
2504
	swp_entry_t entry;
L
Linus Torvalds 已提交
2505
	pte_t pte;
2506
	struct mem_cgroup *ptr = NULL;
N
Nick Piggin 已提交
2507
	int ret = 0;
L
Linus Torvalds 已提交
2508

H
Hugh Dickins 已提交
2509
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2510
		goto out;
2511 2512

	entry = pte_to_swp_entry(orig_pte);
2513 2514 2515 2516
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2517
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2518 2519
	page = lookup_swap_cache(entry);
	if (!page) {
2520
		grab_swap_token(); /* Contend for token _before_ read-in */
2521 2522
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2523 2524
		if (!page) {
			/*
2525 2526
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2527
			 */
2528
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2529 2530
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2531
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2532
			goto unlock;
L
Linus Torvalds 已提交
2533 2534 2535 2536
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2537
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2538 2539
	}

2540 2541 2542
	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

K
KAMEZAWA Hiroyuki 已提交
2543
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2544
		ret = VM_FAULT_OOM;
2545
		goto out_page;
2546 2547
	}

L
Linus Torvalds 已提交
2548
	/*
2549
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2550
	 */
2551
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2552
	if (unlikely(!pte_same(*page_table, orig_pte)))
2553 2554 2555 2556 2557
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2558 2559
	}

2560 2561 2562 2563 2564 2565 2566 2567
	/*
	 * 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.
2568 2569 2570 2571
	 * 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().
2572
	 */
L
Linus Torvalds 已提交
2573

2574
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2575
	pte = mk_pte(page, vma->vm_page_prot);
2576
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2577
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2578
		flags &= ~FAULT_FLAG_WRITE;
L
Linus Torvalds 已提交
2579 2580 2581 2582
	}
	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
	page_add_anon_rmap(page, vma, address);
2583 2584
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
2585

2586
	swap_free(entry);
N
Nick Piggin 已提交
2587
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2588
		try_to_free_swap(page);
2589 2590
	unlock_page(page);

2591
	if (flags & FAULT_FLAG_WRITE) {
2592 2593 2594
		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
2595 2596 2597 2598 2599
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2600
unlock:
2601
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2602 2603
out:
	return ret;
2604
out_nomap:
2605
	mem_cgroup_cancel_charge_swapin(ptr);
2606
	pte_unmap_unlock(page_table, ptl);
2607
out_page:
2608 2609
	unlock_page(page);
	page_cache_release(page);
2610
	return ret;
L
Linus Torvalds 已提交
2611 2612 2613
}

/*
2614 2615 2616
 * 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
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,
2620
		unsigned int flags)
L
Linus Torvalds 已提交
2621
{
2622 2623
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2624 2625
	pte_t entry;

N
Nick Piggin 已提交
2626 2627
	/* Allocate our own private page. */
	pte_unmap(page_table);
2628

N
Nick Piggin 已提交
2629 2630 2631 2632 2633
	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
2634
	__SetPageUptodate(page);
2635

K
KAMEZAWA Hiroyuki 已提交
2636
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2637 2638
		goto oom_free_page;

N
Nick Piggin 已提交
2639 2640
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2641

N
Nick Piggin 已提交
2642 2643 2644 2645 2646
	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);
2647
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2648 2649

	/* No need to invalidate - it was non-present before */
2650 2651
	update_mmu_cache(vma, address, entry);
unlock:
2652
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2653
	return 0;
2654
release:
2655
	mem_cgroup_uncharge_page(page);
2656 2657
	page_cache_release(page);
	goto unlock;
2658
oom_free_page:
2659
	page_cache_release(page);
2660
oom:
L
Linus Torvalds 已提交
2661 2662 2663 2664
	return VM_FAULT_OOM;
}

/*
2665
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2666
 * tries to share with existing pages, but makes a separate copy if
2667 2668
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2669 2670 2671 2672
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2673
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2674
 * but allow concurrent faults), and pte neither mapped nor locked.
2675
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2676
 */
2677
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2678
		unsigned long address, pmd_t *pmd,
2679
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2680
{
2681
	pte_t *page_table;
2682
	spinlock_t *ptl;
N
Nick Piggin 已提交
2683
	struct page *page;
L
Linus Torvalds 已提交
2684 2685
	pte_t entry;
	int anon = 0;
2686
	int charged = 0;
2687
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2688 2689
	struct vm_fault vmf;
	int ret;
2690
	int page_mkwrite = 0;
2691

N
Nick Piggin 已提交
2692 2693 2694 2695
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2696

N
Nick Piggin 已提交
2697 2698 2699
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2700

2701
	/*
N
Nick Piggin 已提交
2702
	 * For consistency in subsequent calls, make the faulted page always
2703 2704
	 * locked.
	 */
N
Nick Piggin 已提交
2705
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2706
		lock_page(vmf.page);
2707
	else
N
Nick Piggin 已提交
2708
		VM_BUG_ON(!PageLocked(vmf.page));
2709

L
Linus Torvalds 已提交
2710 2711 2712
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2713
	page = vmf.page;
2714
	if (flags & FAULT_FLAG_WRITE) {
2715
		if (!(vma->vm_flags & VM_SHARED)) {
2716
			anon = 1;
2717
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2718
				ret = VM_FAULT_OOM;
2719
				goto out;
2720
			}
N
Nick Piggin 已提交
2721 2722
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2723
			if (!page) {
N
Nick Piggin 已提交
2724
				ret = VM_FAULT_OOM;
2725
				goto out;
2726
			}
K
KAMEZAWA Hiroyuki 已提交
2727
			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2728 2729 2730 2731 2732
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2733 2734 2735 2736 2737 2738
			/*
			 * 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
2739
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2740
			__SetPageUptodate(page);
2741
		} else {
2742 2743
			/*
			 * If the page will be shareable, see if the backing
2744
			 * address space wants to know that the page is about
2745 2746
			 * to become writable
			 */
2747
			if (vma->vm_ops->page_mkwrite) {
2748 2749
				int tmp;

2750
				unlock_page(page);
N
Nick Piggin 已提交
2751
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2752 2753 2754 2755
				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
2756
					goto unwritable_page;
N
Nick Piggin 已提交
2757
				}
N
Nick Piggin 已提交
2758 2759 2760 2761 2762 2763 2764 2765 2766
				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));
2767
				page_mkwrite = 1;
2768 2769
			}
		}
2770

L
Linus Torvalds 已提交
2771 2772
	}

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

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
2780
	 * Note that if FAULT_FLAG_WRITE is set, we either now have
L
Linus Torvalds 已提交
2781 2782 2783 2784 2785
	 * 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... */
2786
	if (likely(pte_same(*page_table, orig_pte))) {
2787 2788
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2789
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2790 2791
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2792 2793
			inc_mm_counter(mm, anon_rss);
			page_add_new_anon_rmap(page, vma, address);
2794
		} else {
2795
			inc_mm_counter(mm, file_rss);
2796
			page_add_file_rmap(page);
2797
			if (flags & FAULT_FLAG_WRITE) {
2798
				dirty_page = page;
2799 2800
				get_page(dirty_page);
			}
2801
		}
2802
		set_pte_at(mm, address, page_table, entry);
2803 2804 2805

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2806
	} else {
2807 2808
		if (charged)
			mem_cgroup_uncharge_page(page);
2809 2810 2811
		if (anon)
			page_cache_release(page);
		else
2812
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2813 2814
	}

2815
	pte_unmap_unlock(page_table, ptl);
2816 2817

out:
N
Nick Piggin 已提交
2818 2819
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
2820

N
Nick Piggin 已提交
2821 2822 2823
		if (set_page_dirty(dirty_page))
			page_mkwrite = 1;
		unlock_page(dirty_page);
2824
		put_page(dirty_page);
N
Nick Piggin 已提交
2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839
		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);
2840
	}
2841

N
Nick Piggin 已提交
2842
	return ret;
N
Nick Piggin 已提交
2843 2844 2845 2846

unwritable_page:
	page_cache_release(page);
	return ret;
2847
}
2848

2849 2850
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2851
		unsigned int flags, pte_t orig_pte)
2852 2853
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2854
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2855

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
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2871
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2872
{
2873
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2874

2875 2876
	flags |= FAULT_FLAG_NONLINEAR;

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
		struct vm_area_struct *vma, unsigned long address,
2907
		pte_t *pte, pmd_t *pmd, unsigned int flags)
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
					return do_linear_fault(mm, vma, address,
2918
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
2919 2920
			}
			return do_anonymous_page(mm, vma, address,
2921
						 pte, pmd, flags);
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
					pte, pmd, flags, entry);
2926
		return do_swap_page(mm, vma, address,
2927
					pte, pmd, flags, 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;
2934
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
2935
		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, flags & FAULT_FLAG_WRITE)) {
2942 2943 2944 2945 2946 2947 2948 2949
		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.
		 */
2950
		if (flags & FAULT_FLAG_WRITE)
2951 2952
			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,
2962
		unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
2963 2964 2965 2966 2967 2968 2969 2970
{
	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
	if (unlikely(is_vm_hugetlb_page(vma)))
2974
		return hugetlb_fault(mm, vma, address, flags);
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

2987
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
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