memory.c 107.9 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>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/export.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 <linux/gfp.h>
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#include <asm/io.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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unsigned long zero_pfn __read_mostly;
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unsigned long highest_memmap_pfn __read_mostly;
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/*
 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
 */
static int __init init_zero_pfn(void)
{
	zero_pfn = page_to_pfn(ZERO_PAGE(0));
	return 0;
}
core_initcall(init_zero_pfn);
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#if defined(SPLIT_RSS_COUNTING)

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void sync_mm_rss(struct mm_struct *mm)
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{
	int i;

	for (i = 0; i < NR_MM_COUNTERS; i++) {
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		if (current->rss_stat.count[i]) {
			add_mm_counter(mm, i, current->rss_stat.count[i]);
			current->rss_stat.count[i] = 0;
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		}
	}
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	current->rss_stat.events = 0;
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}

static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
{
	struct task_struct *task = current;

	if (likely(task->mm == mm))
		task->rss_stat.count[member] += val;
	else
		add_mm_counter(mm, member, val);
}
#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)

/* sync counter once per 64 page faults */
#define TASK_RSS_EVENTS_THRESH	(64)
static void check_sync_rss_stat(struct task_struct *task)
{
	if (unlikely(task != current))
		return;
	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
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		sync_mm_rss(task->mm);
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}
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#else /* SPLIT_RSS_COUNTING */
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#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)

static void check_sync_rss_stat(struct task_struct *task)
{
}

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#endif /* SPLIT_RSS_COUNTING */

#ifdef HAVE_GENERIC_MMU_GATHER

static int tlb_next_batch(struct mmu_gather *tlb)
{
	struct mmu_gather_batch *batch;

	batch = tlb->active;
	if (batch->next) {
		tlb->active = batch->next;
		return 1;
	}

	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
	if (!batch)
		return 0;

	batch->next = NULL;
	batch->nr   = 0;
	batch->max  = MAX_GATHER_BATCH;

	tlb->active->next = batch;
	tlb->active = batch;

	return 1;
}

/* tlb_gather_mmu
 *	Called to initialize an (on-stack) mmu_gather structure for page-table
 *	tear-down from @mm. The @fullmm argument is used when @mm is without
 *	users and we're going to destroy the full address space (exit/execve).
 */
void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
{
	tlb->mm = mm;

	tlb->fullmm     = fullmm;
	tlb->need_flush = 0;
	tlb->fast_mode  = (num_possible_cpus() == 1);
	tlb->local.next = NULL;
	tlb->local.nr   = 0;
	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
	tlb->active     = &tlb->local;

#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb->batch = NULL;
#endif
}

void tlb_flush_mmu(struct mmu_gather *tlb)
{
	struct mmu_gather_batch *batch;

	if (!tlb->need_flush)
		return;
	tlb->need_flush = 0;
	tlb_flush(tlb);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb_table_flush(tlb);
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#endif

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	if (tlb_fast_mode(tlb))
		return;

	for (batch = &tlb->local; batch; batch = batch->next) {
		free_pages_and_swap_cache(batch->pages, batch->nr);
		batch->nr = 0;
	}
	tlb->active = &tlb->local;
}

/* tlb_finish_mmu
 *	Called at the end of the shootdown operation to free up any resources
 *	that were required.
 */
void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
	struct mmu_gather_batch *batch, *next;

	tlb_flush_mmu(tlb);

	/* keep the page table cache within bounds */
	check_pgt_cache();

	for (batch = tlb->local.next; batch; batch = next) {
		next = batch->next;
		free_pages((unsigned long)batch, 0);
	}
	tlb->local.next = NULL;
}

/* __tlb_remove_page
 *	Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
 *	handling the additional races in SMP caused by other CPUs caching valid
 *	mappings in their TLBs. Returns the number of free page slots left.
 *	When out of page slots we must call tlb_flush_mmu().
 */
int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
	struct mmu_gather_batch *batch;

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	VM_BUG_ON(!tlb->need_flush);
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	if (tlb_fast_mode(tlb)) {
		free_page_and_swap_cache(page);
		return 1; /* avoid calling tlb_flush_mmu() */
	}

	batch = tlb->active;
	batch->pages[batch->nr++] = page;
	if (batch->nr == batch->max) {
		if (!tlb_next_batch(tlb))
			return 0;
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		batch = tlb->active;
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	}
	VM_BUG_ON(batch->nr > batch->max);

	return batch->max - batch->nr;
}

#endif /* HAVE_GENERIC_MMU_GATHER */

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#ifdef CONFIG_HAVE_RCU_TABLE_FREE

/*
 * See the comment near struct mmu_table_batch.
 */

static void tlb_remove_table_smp_sync(void *arg)
{
	/* Simply deliver the interrupt */
}

static void tlb_remove_table_one(void *table)
{
	/*
	 * This isn't an RCU grace period and hence the page-tables cannot be
	 * assumed to be actually RCU-freed.
	 *
	 * It is however sufficient for software page-table walkers that rely on
	 * IRQ disabling. See the comment near struct mmu_table_batch.
	 */
	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
	__tlb_remove_table(table);
}

static void tlb_remove_table_rcu(struct rcu_head *head)
{
	struct mmu_table_batch *batch;
	int i;

	batch = container_of(head, struct mmu_table_batch, rcu);

	for (i = 0; i < batch->nr; i++)
		__tlb_remove_table(batch->tables[i]);

	free_page((unsigned long)batch);
}

void tlb_table_flush(struct mmu_gather *tlb)
{
	struct mmu_table_batch **batch = &tlb->batch;

	if (*batch) {
		call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
		*batch = NULL;
	}
}

void tlb_remove_table(struct mmu_gather *tlb, void *table)
{
	struct mmu_table_batch **batch = &tlb->batch;

	tlb->need_flush = 1;

	/*
	 * When there's less then two users of this mm there cannot be a
	 * concurrent page-table walk.
	 */
	if (atomic_read(&tlb->mm->mm_users) < 2) {
		__tlb_remove_table(table);
		return;
	}

	if (*batch == NULL) {
		*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
		if (*batch == NULL) {
			tlb_remove_table_one(table);
			return;
		}
		(*batch)->nr = 0;
	}
	(*batch)->tables[(*batch)->nr++] = table;
	if ((*batch)->nr == MAX_TABLE_BATCH)
		tlb_table_flush(tlb);
}

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#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
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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,
			   unsigned long addr)
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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, addr);
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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, addr);
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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);
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	pmd_free_tlb(tlb, pmd, start);
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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);
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	pud_free_tlb(tlb, pud, start);
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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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	/*
	 * 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;

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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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		/*
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		 * Hide vma from rmap and truncate_pagecache before freeing
		 * pgtables
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		 */
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		unlink_anon_vmas(vma);
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		unlink_file_vma(vma);

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		if (is_vm_hugetlb_page(vma)) {
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			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
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				floor, next? next->vm_start: ceiling);
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		} else {
			/*
			 * 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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				unlink_anon_vmas(vma);
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				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, struct vm_area_struct *vma,
		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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	int wait_split_huge_page;
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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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	wait_split_huge_page = 0;
	if (likely(pmd_none(*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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	} else if (unlikely(pmd_trans_splitting(*pmd)))
		wait_split_huge_page = 1;
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	spin_unlock(&mm->page_table_lock);
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	if (new)
		pte_free(mm, new);
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	if (wait_split_huge_page)
		wait_split_huge_page(vma->anon_vma, pmd);
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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 (likely(pmd_none(*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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	} else
		VM_BUG_ON(pmd_trans_splitting(*pmd));
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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 init_rss_vec(int *rss)
{
	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
}

static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
637
{
K
KAMEZAWA Hiroyuki 已提交
638 639
	int i;

640
	if (current->mm == mm)
641
		sync_mm_rss(mm);
K
KAMEZAWA Hiroyuki 已提交
642 643 644
	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
645 646
}

N
Nick Piggin 已提交
647
/*
648 649 650
 * 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.
N
Nick Piggin 已提交
651 652 653
 *
 * The calling function must still handle the error.
 */
654 655
static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
			  pte_t pte, struct page *page)
N
Nick Piggin 已提交
656
{
657 658 659 660 661
	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;
662 663 664 665 666 667 668 669 670 671 672 673 674 675
	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) {
676 677
			printk(KERN_ALERT
				"BUG: Bad page map: %lu messages suppressed\n",
678 679 680 681 682 683 684
				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
685 686 687 688

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

689 690
	printk(KERN_ALERT
		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
691 692
		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
693 694
	if (page)
		dump_page(page);
695
	printk(KERN_ALERT
696 697 698 699 700 701
		"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)
702
		print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
703 704
				(unsigned long)vma->vm_ops->fault);
	if (vma->vm_file && vma->vm_file->f_op)
705
		print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
706
				(unsigned long)vma->vm_file->f_op->mmap);
N
Nick Piggin 已提交
707
	dump_stack();
708
	add_taint(TAINT_BAD_PAGE);
N
Nick Piggin 已提交
709 710
}

711
static inline int is_cow_mapping(vm_flags_t flags)
712 713 714 715
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

H
Hugh Dickins 已提交
716 717 718 719 720 721 722 723 724 725 726 727 728 729
#ifndef is_zero_pfn
static inline int is_zero_pfn(unsigned long pfn)
{
	return pfn == zero_pfn;
}
#endif

#ifndef my_zero_pfn
static inline unsigned long my_zero_pfn(unsigned long addr)
{
	return zero_pfn;
}
#endif

H
Hugh Dickins 已提交
730
/*
N
Nick Piggin 已提交
731
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
732
 *
N
Nick Piggin 已提交
733 734 735
 * "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.
J
Jared Hulbert 已提交
736
 *
N
Nick Piggin 已提交
737 738 739 740 741 742 743 744
 * 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.
745
 *
J
Jared Hulbert 已提交
746 747
 * 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
N
Nick Piggin 已提交
748 749
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
750 751 752
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
753 754 755 756 757 758
 * 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).
J
Jared Hulbert 已提交
759 760
 *
 *
N
Nick Piggin 已提交
761
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
762 763 764 765 766 767 768 769 770
 *
 * 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.
 *
H
Hugh Dickins 已提交
771
 */
N
Nick Piggin 已提交
772 773 774 775 776 777 778
#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)
H
Hugh Dickins 已提交
779
{
780
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
781 782

	if (HAVE_PTE_SPECIAL) {
783 784
		if (likely(!pte_special(pte)))
			goto check_pfn;
H
Hugh Dickins 已提交
785 786
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
787
		if (!is_zero_pfn(pfn))
788
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
789 790 791 792 793
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
794 795 796 797 798 799
	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
N
Nick Piggin 已提交
800 801
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
802 803 804 805 806
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
807 808
	}

H
Hugh Dickins 已提交
809 810
	if (is_zero_pfn(pfn))
		return NULL;
811 812 813 814 815
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
816 817

	/*
N
Nick Piggin 已提交
818 819
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
820
	 */
J
Jared Hulbert 已提交
821
out:
822
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
823 824
}

L
Linus Torvalds 已提交
825 826 827 828 829 830
/*
 * 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.
 */

H
Hugh Dickins 已提交
831
static inline unsigned long
L
Linus Torvalds 已提交
832
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
833
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
834
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
835
{
N
Nick Piggin 已提交
836
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
837 838 839 840 841 842
	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)) {
843 844
			swp_entry_t entry = pte_to_swp_entry(pte);

H
Hugh Dickins 已提交
845 846 847
			if (swap_duplicate(entry) < 0)
				return entry.val;

L
Linus Torvalds 已提交
848 849 850
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
851 852 853
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
854 855
				spin_unlock(&mmlist_lock);
			}
K
KAMEZAWA Hiroyuki 已提交
856 857
			if (likely(!non_swap_entry(entry)))
				rss[MM_SWAPENTS]++;
858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875
			else if (is_migration_entry(entry)) {
				page = migration_entry_to_page(entry);

				if (PageAnon(page))
					rss[MM_ANONPAGES]++;
				else
					rss[MM_FILEPAGES]++;

				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);
				}
876
			}
L
Linus Torvalds 已提交
877
		}
878
		goto out_set_pte;
L
Linus Torvalds 已提交
879 880 881 882 883 884
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
885
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
886
		ptep_set_wrprotect(src_mm, addr, src_pte);
887
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
888 889 890 891 892 893 894 895 896
	}

	/*
	 * 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);
897 898 899 900

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
901
		page_dup_rmap(page);
K
KAMEZAWA Hiroyuki 已提交
902 903 904 905
		if (PageAnon(page))
			rss[MM_ANONPAGES]++;
		else
			rss[MM_FILEPAGES]++;
906
	}
907 908 909

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
910
	return 0;
L
Linus Torvalds 已提交
911 912
}

913 914 915
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)
L
Linus Torvalds 已提交
916
{
917
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
918
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
919
	spinlock_t *src_ptl, *dst_ptl;
920
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
921
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
922
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
923 924

again:
K
KAMEZAWA Hiroyuki 已提交
925 926
	init_rss_vec(rss);

H
Hugh Dickins 已提交
927
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
928 929
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
930
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
931
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
932
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
933 934
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
935
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
936 937 938 939 940 941

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
942 943 944
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
945
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
946 947
				break;
		}
L
Linus Torvalds 已提交
948 949 950 951
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
952 953 954 955
		entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
							vma, addr, rss);
		if (entry.val)
			break;
L
Linus Torvalds 已提交
956 957 958
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

959
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
960
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
961
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
962
	add_mm_rss_vec(dst_mm, rss);
963
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
964
	cond_resched();
H
Hugh Dickins 已提交
965 966 967 968 969 970

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988
	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);
989 990
		if (pmd_trans_huge(*src_pmd)) {
			int err;
991
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
992 993 994 995 996 997 998 999
			err = copy_huge_pmd(dst_mm, src_mm,
					    dst_pmd, src_pmd, addr, vma);
			if (err == -ENOMEM)
				return -ENOMEM;
			if (!err)
				continue;
			/* fall through */
		}
L
Linus Torvalds 已提交
1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
		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
1038
	int ret;
L
Linus Torvalds 已提交
1039

1040 1041 1042 1043 1044 1045
	/*
	 * 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.
	 */
1046
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1047 1048 1049 1050
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
1051 1052 1053
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1054
	if (unlikely(is_pfn_mapping(vma))) {
1055 1056 1057 1058 1059 1060 1061 1062 1063
		/*
		 * 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
1064 1065 1066 1067 1068 1069 1070 1071 1072 1073
	/*
	 * 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
1074 1075 1076 1077 1078 1079
	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
1080 1081 1082 1083 1084
		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
1085
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1086 1087 1088 1089 1090

	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
1091 1092
}

1093
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1094
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1095
				unsigned long addr, unsigned long end,
1096
				struct zap_details *details)
L
Linus Torvalds 已提交
1097
{
N
Nick Piggin 已提交
1098
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1099
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1100
	int rss[NR_MM_COUNTERS];
1101
	spinlock_t *ptl;
1102
	pte_t *start_pte;
1103
	pte_t *pte;
K
KAMEZAWA Hiroyuki 已提交
1104

P
Peter Zijlstra 已提交
1105
again:
1106
	init_rss_vec(rss);
1107 1108
	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	pte = start_pte;
1109
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1110 1111
	do {
		pte_t ptent = *pte;
1112
		if (pte_none(ptent)) {
L
Linus Torvalds 已提交
1113
			continue;
1114
		}
1115

L
Linus Torvalds 已提交
1116
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
1117
			struct page *page;
1118

1119
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137
			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
1138
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1139
							tlb->fullmm);
L
Linus Torvalds 已提交
1140 1141 1142 1143 1144 1145
			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
1146
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
1147 1148
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
K
KAMEZAWA Hiroyuki 已提交
1149
				rss[MM_ANONPAGES]--;
1150 1151 1152
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
1153 1154
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
1155
					mark_page_accessed(page);
K
KAMEZAWA Hiroyuki 已提交
1156
				rss[MM_FILEPAGES]--;
1157
			}
1158
			page_remove_rmap(page);
1159 1160
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
P
Peter Zijlstra 已提交
1161 1162 1163
			force_flush = !__tlb_remove_page(tlb, page);
			if (force_flush)
				break;
L
Linus Torvalds 已提交
1164 1165 1166 1167 1168 1169 1170 1171
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
1172 1173 1174
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
K
KAMEZAWA Hiroyuki 已提交
1175 1176 1177 1178 1179
		} else {
			swp_entry_t entry = pte_to_swp_entry(ptent);

			if (!non_swap_entry(entry))
				rss[MM_SWAPENTS]--;
1180 1181 1182 1183 1184 1185 1186 1187 1188 1189
			else if (is_migration_entry(entry)) {
				struct page *page;

				page = migration_entry_to_page(entry);

				if (PageAnon(page))
					rss[MM_ANONPAGES]--;
				else
					rss[MM_FILEPAGES]--;
			}
K
KAMEZAWA Hiroyuki 已提交
1190 1191 1192
			if (unlikely(!free_swap_and_cache(entry)))
				print_bad_pte(vma, addr, ptent, NULL);
		}
1193
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1194
	} while (pte++, addr += PAGE_SIZE, addr != end);
1195

K
KAMEZAWA Hiroyuki 已提交
1196
	add_mm_rss_vec(mm, rss);
1197
	arch_leave_lazy_mmu_mode();
1198
	pte_unmap_unlock(start_pte, ptl);
1199

P
Peter Zijlstra 已提交
1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211
	/*
	 * mmu_gather ran out of room to batch pages, we break out of
	 * the PTE lock to avoid doing the potential expensive TLB invalidate
	 * and page-free while holding it.
	 */
	if (force_flush) {
		force_flush = 0;
		tlb_flush_mmu(tlb);
		if (addr != end)
			goto again;
	}

1212
	return addr;
L
Linus Torvalds 已提交
1213 1214
}

1215
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1216
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1217
				unsigned long addr, unsigned long end,
1218
				struct zap_details *details)
L
Linus Torvalds 已提交
1219 1220 1221 1222 1223 1224 1225
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1226
		if (pmd_trans_huge(*pmd)) {
1227
			if (next - addr != HPAGE_PMD_SIZE) {
1228
				VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1229
				split_huge_page_pmd(vma->vm_mm, pmd);
S
Shaohua Li 已提交
1230
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1231
				goto next;
1232 1233
			/* fall through */
		}
1234 1235 1236 1237 1238 1239 1240 1241 1242
		/*
		 * Here there can be other concurrent MADV_DONTNEED or
		 * trans huge page faults running, and if the pmd is
		 * none or trans huge it can change under us. This is
		 * because MADV_DONTNEED holds the mmap_sem in read
		 * mode.
		 */
		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
			goto next;
1243
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1244
next:
1245 1246
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1247 1248

	return addr;
L
Linus Torvalds 已提交
1249 1250
}

1251
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1252
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1253
				unsigned long addr, unsigned long end,
1254
				struct zap_details *details)
L
Linus Torvalds 已提交
1255 1256 1257 1258 1259 1260 1261
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1262
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1263
			continue;
1264 1265
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
	} while (pud++, addr = next, addr != end);
1266 1267

	return addr;
L
Linus Torvalds 已提交
1268 1269
}

A
Al Viro 已提交
1270 1271 1272 1273
static void unmap_page_range(struct mmu_gather *tlb,
			     struct vm_area_struct *vma,
			     unsigned long addr, unsigned long end,
			     struct zap_details *details)
L
Linus Torvalds 已提交
1274 1275 1276 1277 1278 1279 1280 1281
{
	pgd_t *pgd;
	unsigned long next;

	if (details && !details->check_mapping && !details->nonlinear_vma)
		details = NULL;

	BUG_ON(addr >= end);
1282
	mem_cgroup_uncharge_start();
L
Linus Torvalds 已提交
1283 1284 1285 1286
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
1287
		if (pgd_none_or_clear_bad(pgd))
L
Linus Torvalds 已提交
1288
			continue;
1289 1290
		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
	} while (pgd++, addr = next, addr != end);
L
Linus Torvalds 已提交
1291
	tlb_end_vma(tlb, vma);
1292
	mem_cgroup_uncharge_end();
L
Linus Torvalds 已提交
1293
}
1294

1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
	unsigned long start = max(vma->vm_start, start_addr);
	unsigned long end;

	if (start >= vma->vm_end)
		return;
	end = min(vma->vm_end, end_addr);
	if (end <= vma->vm_start)
		return;

	if (vma->vm_flags & VM_ACCOUNT)
		*nr_accounted += (end - start) >> PAGE_SHIFT;

	if (unlikely(is_pfn_mapping(vma)))
		untrack_pfn_vma(vma, 0, 0);

	if (start != end) {
		if (unlikely(is_vm_hugetlb_page(vma))) {
			/*
			 * 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);
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1334 1335 1336 1337
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1338
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1339 1340 1341 1342 1343 1344
 * @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
 *
1345
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1346 1347 1348 1349 1350 1351 1352 1353 1354 1355
 *
 * 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.
 */
A
Al Viro 已提交
1356
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1357 1358 1359 1360
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
A
Andrea Arcangeli 已提交
1361
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1362

A
Andrea Arcangeli 已提交
1363
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1364 1365 1366
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
		unmap_single_vma(tlb, vma, start_addr, end_addr, nr_accounted,
				 details);
A
Andrea Arcangeli 已提交
1367
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1368 1369 1370 1371 1372 1373 1374 1375
}

/**
 * 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
1376 1377
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1378
 */
A
Al Viro 已提交
1379
void zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1380 1381 1382
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1383
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1384 1385 1386 1387
	unsigned long end = address + size;
	unsigned long nr_accounted = 0;

	lru_add_drain();
P
Peter Zijlstra 已提交
1388
	tlb_gather_mmu(&tlb, mm, 0);
1389
	update_hiwater_rss(mm);
A
Al Viro 已提交
1390
	unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
P
Peter Zijlstra 已提交
1391
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1392 1393
}

1394 1395 1396 1397 1398 1399 1400 1401
/**
 * zap_page_range_single - 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
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1402
 */
1403
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1404 1405 1406
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1407
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1408 1409 1410 1411
	unsigned long end = address + size;
	unsigned long nr_accounted = 0;

	lru_add_drain();
P
Peter Zijlstra 已提交
1412
	tlb_gather_mmu(&tlb, mm, 0);
1413
	update_hiwater_rss(mm);
1414 1415 1416
	mmu_notifier_invalidate_range_start(mm, address, end);
	unmap_single_vma(&tlb, vma, address, end, &nr_accounted, details);
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1417
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1418 1419
}

1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437
/**
 * 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;
1438
	zap_page_range_single(vma, address, size, NULL);
1439 1440 1441 1442
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

J
Johannes Weiner 已提交
1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453
/**
 * follow_page - look up a page descriptor from a user-virtual address
 * @vma: vm_area_struct mapping @address
 * @address: virtual address to look up
 * @flags: flags modifying lookup behaviour
 *
 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
 *
 * Returns the mapped (struct page *), %NULL if no mapping exists, or
 * an error pointer if there is a mapping to something not represented
 * by a page descriptor (see also vm_normal_page()).
L
Linus Torvalds 已提交
1454
 */
1455
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1456
			unsigned int flags)
L
Linus Torvalds 已提交
1457 1458 1459 1460 1461
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1462
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1463
	struct page *page;
1464
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1465

1466 1467 1468 1469 1470
	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
1471

1472
	page = NULL;
L
Linus Torvalds 已提交
1473 1474
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1475
		goto no_page_table;
L
Linus Torvalds 已提交
1476 1477

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1478
	if (pud_none(*pud))
1479
		goto no_page_table;
1480
	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
A
Andi Kleen 已提交
1481 1482 1483 1484 1485 1486 1487
		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
1488
	pmd = pmd_offset(pud, address);
1489
	if (pmd_none(*pmd))
1490
		goto no_page_table;
1491
	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1492 1493
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
1494
		goto out;
1495
	}
1496
	if (pmd_trans_huge(*pmd)) {
1497 1498 1499 1500
		if (flags & FOLL_SPLIT) {
			split_huge_page_pmd(mm, pmd);
			goto split_fallthrough;
		}
1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515
		spin_lock(&mm->page_table_lock);
		if (likely(pmd_trans_huge(*pmd))) {
			if (unlikely(pmd_trans_splitting(*pmd))) {
				spin_unlock(&mm->page_table_lock);
				wait_split_huge_page(vma->anon_vma, pmd);
			} else {
				page = follow_trans_huge_pmd(mm, address,
							     pmd, flags);
				spin_unlock(&mm->page_table_lock);
				goto out;
			}
		} else
			spin_unlock(&mm->page_table_lock);
		/* fall through */
	}
1516
split_fallthrough:
1517 1518 1519
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1520
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1521 1522

	pte = *ptep;
1523
	if (!pte_present(pte))
1524
		goto no_page;
1525 1526
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
H
Hugh Dickins 已提交
1527

1528
	page = vm_normal_page(vma, address, pte);
H
Hugh Dickins 已提交
1529 1530
	if (unlikely(!page)) {
		if ((flags & FOLL_DUMP) ||
H
Hugh Dickins 已提交
1531
		    !is_zero_pfn(pte_pfn(pte)))
H
Hugh Dickins 已提交
1532 1533 1534
			goto bad_page;
		page = pte_page(pte);
	}
L
Linus Torvalds 已提交
1535

1536
	if (flags & FOLL_GET)
1537
		get_page_foll(page);
1538 1539 1540 1541
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
1542 1543 1544 1545 1546
		/*
		 * 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().
		 */
1547 1548
		mark_page_accessed(page);
	}
1549
	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570
		/*
		 * The preliminary mapping check is mainly to avoid the
		 * pointless overhead of lock_page on the ZERO_PAGE
		 * which might bounce very badly if there is contention.
		 *
		 * If the page is already locked, we don't need to
		 * handle it now - vmscan will handle it later if and
		 * when it attempts to reclaim the page.
		 */
		if (page->mapping && trylock_page(page)) {
			lru_add_drain();  /* push cached pages to LRU */
			/*
			 * Because we lock page here and migration is
			 * blocked by the pte's page reference, we need
			 * only check for file-cache page truncation.
			 */
			if (page->mapping)
				mlock_vma_page(page);
			unlock_page(page);
		}
	}
1571 1572
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1573
out:
1574
	return page;
L
Linus Torvalds 已提交
1575

1576 1577 1578 1579 1580 1581 1582 1583
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
H
Hugh Dickins 已提交
1584

1585 1586 1587
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
H
Hugh Dickins 已提交
1588 1589 1590 1591 1592
	 * has touched so far, we don't want to allocate unnecessary pages or
	 * page tables.  Return error instead of NULL to skip handle_mm_fault,
	 * then get_dump_page() will return NULL to leave a hole in the dump.
	 * But we can only make this optimization where a hole would surely
	 * be zero-filled if handle_mm_fault() actually did handle it.
1593
	 */
H
Hugh Dickins 已提交
1594 1595 1596
	if ((flags & FOLL_DUMP) &&
	    (!vma->vm_ops || !vma->vm_ops->fault))
		return ERR_PTR(-EFAULT);
1597
	return page;
L
Linus Torvalds 已提交
1598 1599
}

1600 1601
static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
{
1602 1603
	return stack_guard_page_start(vma, addr) ||
	       stack_guard_page_end(vma, addr+PAGE_SIZE);
1604 1605
}

H
Huang Ying 已提交
1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654
/**
 * __get_user_pages() - pin user pages in memory
 * @tsk:	task_struct of target task
 * @mm:		mm_struct of target mm
 * @start:	starting user address
 * @nr_pages:	number of pages from start to pin
 * @gup_flags:	flags modifying pin behaviour
 * @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.
 * @nonblocking: whether waiting for disk IO or mmap_sem contention
 *
 * Returns number of pages pinned. This may be fewer than the number
 * requested. If nr_pages 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 @gup_flags & FOLL_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.
 *
 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
 * or mmap_sem contention, and if waiting is needed to pin all pages,
 * *@nonblocking will be set to 0.
 *
 * In most cases, get_user_pages or get_user_pages_fast should be used
 * instead of __get_user_pages. __get_user_pages should be used only if
 * you need some special @gup_flags.
 */
N
Nick Piggin 已提交
1655
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
H
Hugh Dickins 已提交
1656
		     unsigned long start, int nr_pages, unsigned int gup_flags,
1657 1658
		     struct page **pages, struct vm_area_struct **vmas,
		     int *nonblocking)
L
Linus Torvalds 已提交
1659 1660
{
	int i;
H
Hugh Dickins 已提交
1661
	unsigned long vm_flags;
L
Linus Torvalds 已提交
1662

1663
	if (nr_pages <= 0)
1664
		return 0;
H
Hugh Dickins 已提交
1665 1666 1667

	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));

L
Linus Torvalds 已提交
1668 1669
	/* 
	 * Require read or write permissions.
H
Hugh Dickins 已提交
1670
	 * If FOLL_FORCE is set, we only require the "MAY" flags.
L
Linus Torvalds 已提交
1671
	 */
H
Hugh Dickins 已提交
1672 1673 1674 1675
	vm_flags  = (gup_flags & FOLL_WRITE) ?
			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= (gup_flags & FOLL_FORCE) ?
			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
1676 1677 1678
	i = 0;

	do {
1679
		struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1680 1681

		vma = find_extend_vma(mm, start);
1682
		if (!vma && in_gate_area(mm, start)) {
L
Linus Torvalds 已提交
1683 1684 1685 1686 1687
			unsigned long pg = start & PAGE_MASK;
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
N
Nick Piggin 已提交
1688 1689

			/* user gate pages are read-only */
H
Hugh Dickins 已提交
1690
			if (gup_flags & FOLL_WRITE)
L
Linus Torvalds 已提交
1691 1692 1693 1694 1695 1696 1697 1698 1699
				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);
1700 1701
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
1702
			VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1703
			pte = pte_offset_map(pmd, pg);
1704 1705 1706 1707
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
1708
			vma = get_gate_vma(mm);
L
Linus Torvalds 已提交
1709
			if (pages) {
1710 1711
				struct page *page;

1712
				page = vm_normal_page(vma, start, *pte);
1713 1714 1715 1716 1717 1718 1719 1720 1721
				if (!page) {
					if (!(gup_flags & FOLL_DUMP) &&
					     is_zero_pfn(pte_pfn(*pte)))
						page = pte_page(*pte);
					else {
						pte_unmap(pte);
						return i ? : -EFAULT;
					}
				}
1722
				pages[i] = page;
1723
				get_page(page);
L
Linus Torvalds 已提交
1724 1725
			}
			pte_unmap(pte);
1726
			goto next_page;
L
Linus Torvalds 已提交
1727 1728
		}

N
Nick Piggin 已提交
1729 1730
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
H
Hugh Dickins 已提交
1731
		    !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1732 1733
			return i ? : -EFAULT;

H
Hugh Dickins 已提交
1734 1735
		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
H
Hugh Dickins 已提交
1736
					&start, &nr_pages, i, gup_flags);
H
Hugh Dickins 已提交
1737 1738
			continue;
		}
1739

L
Linus Torvalds 已提交
1740
		do {
1741
			struct page *page;
H
Hugh Dickins 已提交
1742
			unsigned int foll_flags = gup_flags;
L
Linus Torvalds 已提交
1743

1744
			/*
1745
			 * If we have a pending SIGKILL, don't keep faulting
H
Hugh Dickins 已提交
1746
			 * pages and potentially allocating memory.
1747
			 */
H
Hugh Dickins 已提交
1748
			if (unlikely(fatal_signal_pending(current)))
1749
				return i ? i : -ERESTARTSYS;
1750

1751
			cond_resched();
1752
			while (!(page = follow_page(vma, start, foll_flags))) {
1753
				int ret;
1754 1755
				unsigned int fault_flags = 0;

1756 1757 1758 1759 1760
				/* For mlock, just skip the stack guard page. */
				if (foll_flags & FOLL_MLOCK) {
					if (stack_guard_page(vma, start))
						goto next_page;
				}
1761 1762 1763 1764
				if (foll_flags & FOLL_WRITE)
					fault_flags |= FAULT_FLAG_WRITE;
				if (nonblocking)
					fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1765 1766
				if (foll_flags & FOLL_NOWAIT)
					fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1767

1768
				ret = handle_mm_fault(mm, vma, start,
1769
							fault_flags);
1770

N
Nick Piggin 已提交
1771 1772 1773
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
1774 1775 1776 1777 1778 1779 1780 1781 1782 1783
					if (ret & (VM_FAULT_HWPOISON |
						   VM_FAULT_HWPOISON_LARGE)) {
						if (i)
							return i;
						else if (gup_flags & FOLL_HWPOISON)
							return -EHWPOISON;
						else
							return -EFAULT;
					}
					if (ret & VM_FAULT_SIGBUS)
N
Nick Piggin 已提交
1784 1785 1786
						return i ? i : -EFAULT;
					BUG();
				}
1787 1788 1789 1790 1791 1792 1793

				if (tsk) {
					if (ret & VM_FAULT_MAJOR)
						tsk->maj_flt++;
					else
						tsk->min_flt++;
				}
N
Nick Piggin 已提交
1794

1795
				if (ret & VM_FAULT_RETRY) {
1796 1797
					if (nonblocking)
						*nonblocking = 0;
1798 1799 1800
					return i;
				}

1801
				/*
N
Nick Piggin 已提交
1802 1803 1804 1805
				 * 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
1806 1807 1808 1809 1810 1811
				 * 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).
1812
				 */
1813 1814
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1815
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1816

1817
				cond_resched();
L
Linus Torvalds 已提交
1818
			}
1819 1820
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1821
			if (pages) {
1822
				pages[i] = page;
1823

1824
				flush_anon_page(vma, page, start);
1825
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1826
			}
1827
next_page:
L
Linus Torvalds 已提交
1828 1829 1830 1831
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
1832 1833 1834
			nr_pages--;
		} while (nr_pages && start < vma->vm_end);
	} while (nr_pages);
L
Linus Torvalds 已提交
1835 1836
	return i;
}
H
Huang Ying 已提交
1837
EXPORT_SYMBOL(__get_user_pages);
N
Nick Piggin 已提交
1838

1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895
/*
 * fixup_user_fault() - manually resolve a user page fault
 * @tsk:	the task_struct to use for page fault accounting, or
 *		NULL if faults are not to be recorded.
 * @mm:		mm_struct of target mm
 * @address:	user address
 * @fault_flags:flags to pass down to handle_mm_fault()
 *
 * This is meant to be called in the specific scenario where for locking reasons
 * we try to access user memory in atomic context (within a pagefault_disable()
 * section), this returns -EFAULT, and we want to resolve the user fault before
 * trying again.
 *
 * Typically this is meant to be used by the futex code.
 *
 * The main difference with get_user_pages() is that this function will
 * unconditionally call handle_mm_fault() which will in turn perform all the
 * necessary SW fixup of the dirty and young bits in the PTE, while
 * handle_mm_fault() only guarantees to update these in the struct page.
 *
 * This is important for some architectures where those bits also gate the
 * access permission to the page because they are maintained in software.  On
 * such architectures, gup() will not be enough to make a subsequent access
 * succeed.
 *
 * This should be called with the mm_sem held for read.
 */
int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
		     unsigned long address, unsigned int fault_flags)
{
	struct vm_area_struct *vma;
	int ret;

	vma = find_extend_vma(mm, address);
	if (!vma || address < vma->vm_start)
		return -EFAULT;

	ret = handle_mm_fault(mm, vma, address, fault_flags);
	if (ret & VM_FAULT_ERROR) {
		if (ret & VM_FAULT_OOM)
			return -ENOMEM;
		if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
			return -EHWPOISON;
		if (ret & VM_FAULT_SIGBUS)
			return -EFAULT;
		BUG();
	}
	if (tsk) {
		if (ret & VM_FAULT_MAJOR)
			tsk->maj_flt++;
		else
			tsk->min_flt++;
	}
	return 0;
}

/*
1896
 * get_user_pages() - pin user pages in memory
1897 1898
 * @tsk:	the task_struct to use for page fault accounting, or
 *		NULL if faults are not to be recorded.
1899 1900
 * @mm:		mm_struct of target mm
 * @start:	starting user address
1901
 * @nr_pages:	number of pages from start to pin
1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912
 * @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
1913
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945
 * 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
1946
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1947
		unsigned long start, int nr_pages, int write, int force,
N
Nick Piggin 已提交
1948 1949
		struct page **pages, struct vm_area_struct **vmas)
{
H
Hugh Dickins 已提交
1950
	int flags = FOLL_TOUCH;
N
Nick Piggin 已提交
1951

H
Hugh Dickins 已提交
1952 1953
	if (pages)
		flags |= FOLL_GET;
N
Nick Piggin 已提交
1954
	if (write)
H
Hugh Dickins 已提交
1955
		flags |= FOLL_WRITE;
N
Nick Piggin 已提交
1956
	if (force)
H
Hugh Dickins 已提交
1957
		flags |= FOLL_FORCE;
N
Nick Piggin 已提交
1958

1959 1960
	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
				NULL);
N
Nick Piggin 已提交
1961
}
L
Linus Torvalds 已提交
1962 1963
EXPORT_SYMBOL(get_user_pages);

H
Hugh Dickins 已提交
1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984
/**
 * get_dump_page() - pin user page in memory while writing it to core dump
 * @addr: user address
 *
 * Returns struct page pointer of user page pinned for dump,
 * to be freed afterwards by page_cache_release() or put_page().
 *
 * Returns NULL on any kind of failure - a hole must then be inserted into
 * the corefile, to preserve alignment with its headers; and also returns
 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
 * allowing a hole to be left in the corefile to save diskspace.
 *
 * Called without mmap_sem, but after all other threads have been killed.
 */
#ifdef CONFIG_ELF_CORE
struct page *get_dump_page(unsigned long addr)
{
	struct vm_area_struct *vma;
	struct page *page;

	if (__get_user_pages(current, current->mm, addr, 1,
1985 1986
			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
			     NULL) < 1)
H
Hugh Dickins 已提交
1987 1988 1989 1990 1991 1992
		return NULL;
	flush_cache_page(vma, addr, page_to_pfn(page));
	return page;
}
#endif /* CONFIG_ELF_CORE */

1993
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1994
			spinlock_t **ptl)
1995 1996 1997 1998
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1999
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
2000 2001
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
2002
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
2003
		}
2004 2005 2006 2007
	}
	return NULL;
}

2008 2009 2010 2011 2012 2013 2014
/*
 * 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
2015 2016
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
2017
{
N
Nick Piggin 已提交
2018
	struct mm_struct *mm = vma->vm_mm;
2019
	int retval;
2020
	pte_t *pte;
2021 2022
	spinlock_t *ptl;

2023
	retval = -EINVAL;
2024
	if (PageAnon(page))
2025
		goto out;
2026 2027
	retval = -ENOMEM;
	flush_dcache_page(page);
2028
	pte = get_locked_pte(mm, addr, &ptl);
2029
	if (!pte)
2030
		goto out;
2031 2032 2033 2034 2035 2036
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
2037
	inc_mm_counter_fast(mm, MM_FILEPAGES);
2038 2039 2040 2041
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
2042 2043
	pte_unmap_unlock(pte, ptl);
	return retval;
2044 2045 2046 2047 2048 2049
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

2050 2051 2052 2053 2054 2055
/**
 * 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
 *
2056 2057 2058 2059 2060 2061
 * 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
2062
 * (see split_page()).
2063 2064 2065 2066 2067 2068 2069 2070 2071
 *
 * 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
2072 2073
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
2074 2075 2076 2077 2078
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
2079
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
2080
	return insert_page(vma, addr, page, vma->vm_page_prot);
2081
}
2082
EXPORT_SYMBOL(vm_insert_page);
2083

N
Nick Piggin 已提交
2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102
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);
2103
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
2104 2105 2106 2107 2108 2109 2110 2111

	retval = 0;
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

N
Nick Piggin 已提交
2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122
/**
 * 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
2123 2124 2125 2126 2127
 *
 * 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
2128 2129
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
2130
			unsigned long pfn)
N
Nick Piggin 已提交
2131
{
2132
	int ret;
2133
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
2134 2135 2136 2137 2138 2139
	/*
	 * 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
2140 2141 2142 2143 2144
	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
2145

N
Nick Piggin 已提交
2146 2147
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
2148
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2149 2150
		return -EINVAL;

2151
	ret = insert_pfn(vma, addr, pfn, pgprot);
2152 2153 2154 2155 2156

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

	return ret;
N
Nick Piggin 已提交
2157 2158
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
2159

N
Nick Piggin 已提交
2160 2161 2162 2163
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
2164

N
Nick Piggin 已提交
2165 2166
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
2167

N
Nick Piggin 已提交
2168 2169 2170 2171
	/*
	 * 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
H
Hugh Dickins 已提交
2172 2173
	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
	 * without pte special, it would there be refcounted as a normal page.
N
Nick Piggin 已提交
2174 2175 2176 2177 2178 2179 2180 2181
	 */
	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
2182
}
N
Nick Piggin 已提交
2183
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
2184

L
Linus Torvalds 已提交
2185 2186 2187 2188 2189 2190 2191 2192 2193 2194
/*
 * 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
2195
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2196

H
Hugh Dickins 已提交
2197
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
2198 2199
	if (!pte)
		return -ENOMEM;
2200
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
2201 2202
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
2203
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
2204 2205
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
2206
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
2207
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221
	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;
2222
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251
	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;
}

2252 2253 2254 2255 2256 2257 2258 2259 2260 2261
/**
 * 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
2262 2263 2264 2265 2266
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;
2267
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
2268 2269 2270 2271 2272 2273 2274 2275
	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
2276 2277 2278 2279 2280
	 *   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.
2281 2282 2283
	 *   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
2284 2285 2286 2287
	 *
	 * 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
2288
	 */
2289
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
2290
		vma->vm_pgoff = pfn;
2291
		vma->vm_flags |= VM_PFN_AT_MMAP;
2292
	} else if (is_cow_mapping(vma->vm_flags))
2293
		return -EINVAL;
L
Linus Torvalds 已提交
2294

2295
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
2296

2297
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2298 2299 2300 2301 2302 2303
	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);
2304
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
2305
		return -EINVAL;
2306
	}
2307

L
Linus Torvalds 已提交
2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318
	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);
2319 2320 2321 2322

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

L
Linus Torvalds 已提交
2323 2324 2325 2326
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

2327 2328 2329 2330 2331 2332
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;
2333
	pgtable_t token;
2334
	spinlock_t *uninitialized_var(ptl);
2335 2336 2337 2338 2339 2340 2341 2342 2343

	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));

2344 2345
	arch_enter_lazy_mmu_mode();

2346
	token = pmd_pgtable(*pmd);
2347 2348

	do {
2349
		err = fn(pte++, token, addr, data);
2350 2351
		if (err)
			break;
2352
	} while (addr += PAGE_SIZE, addr != end);
2353

2354 2355
	arch_leave_lazy_mmu_mode();

2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368
	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
2369 2370
	BUG_ON(pud_huge(*pud));

2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411
	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;
2412
	unsigned long end = addr + size;
2413 2414 2415 2416 2417 2418 2419 2420 2421 2422
	int err;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
2423

2424 2425 2426 2427
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

2428 2429 2430 2431
/*
 * 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
2432
 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2433 2434
 * must check under lock before unmapping the pte and proceeding
 * (but do_wp_page is only called after already making such a check;
2435
 * and do_anonymous_page can safely check later on).
2436
 */
H
Hugh Dickins 已提交
2437
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2438 2439 2440 2441 2442
				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
2443 2444
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
2445
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
2446
		spin_unlock(ptl);
2447 2448 2449 2450 2451 2452
	}
#endif
	pte_unmap(page_table);
	return same;
}

2453
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2454 2455 2456 2457 2458 2459 2460 2461
{
	/*
	 * 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)) {
2462
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
2463 2464 2465 2466 2467 2468 2469 2470 2471
		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))
2472
			clear_page(kaddr);
2473
		kunmap_atomic(kaddr);
2474
		flush_dcache_page(dst);
N
Nick Piggin 已提交
2475 2476
	} else
		copy_user_highpage(dst, src, va, vma);
2477 2478
}

L
Linus Torvalds 已提交
2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492
/*
 * 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.
 *
2493 2494 2495
 * 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
2496
 */
2497 2498
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2499
		spinlock_t *ptl, pte_t orig_pte)
2500
	__releases(ptl)
L
Linus Torvalds 已提交
2501
{
2502
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
2503
	pte_t entry;
2504
	int ret = 0;
2505
	int page_mkwrite = 0;
2506
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2507

2508
	old_page = vm_normal_page(vma, address, orig_pte);
2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519
	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;
2520
		goto gotten;
2521
	}
L
Linus Torvalds 已提交
2522

2523
	/*
P
Peter Zijlstra 已提交
2524 2525
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2526
	 */
H
Hugh Dickins 已提交
2527
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538
		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);
				goto unlock;
			}
			page_cache_release(old_page);
P
Peter Zijlstra 已提交
2539
		}
2540
		if (reuse_swap_page(old_page)) {
2541 2542 2543 2544 2545 2546
			/*
			 * The page is all ours.  Move it to our anon_vma so
			 * the rmap code will not search our parent or siblings.
			 * Protected against the rmap code by the page lock.
			 */
			page_move_anon_rmap(old_page, vma, address);
2547 2548 2549
			unlock_page(old_page);
			goto reuse;
		}
2550
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2551
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2552
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
2553 2554 2555 2556 2557
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2558
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2559 2560 2561 2562 2563 2564 2565 2566 2567
			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;

2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578
			/*
			 * 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);

2579 2580 2581 2582
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2583
				goto unwritable_page;
2584
			}
N
Nick Piggin 已提交
2585 2586 2587 2588 2589 2590 2591 2592 2593
			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));
2594 2595 2596 2597 2598 2599 2600 2601 2602

			/*
			 * 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
2603 2604
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
2605
				goto unlock;
N
Nick Piggin 已提交
2606
			}
2607 2608

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2609
		}
2610 2611
		dirty_page = old_page;
		get_page(dirty_page);
2612

2613
reuse:
2614 2615 2616
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2617
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2618
			update_mmu_cache(vma, address, page_table);
2619
		pte_unmap_unlock(page_table, ptl);
2620
		ret |= VM_FAULT_WRITE;
2621 2622 2623 2624 2625 2626 2627 2628 2629 2630

		if (!dirty_page)
			return ret;

		/*
		 * 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.
		 *
2631
		 * __do_fault is protected similarly.
2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657
		 */
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
		}
		put_page(dirty_page);
		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);

		return ret;
L
Linus Torvalds 已提交
2658 2659 2660 2661 2662
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2663
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2664
gotten:
2665
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2666 2667

	if (unlikely(anon_vma_prepare(vma)))
2668
		goto oom;
H
Hugh Dickins 已提交
2669

H
Hugh Dickins 已提交
2670
	if (is_zero_pfn(pte_pfn(orig_pte))) {
H
Hugh Dickins 已提交
2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681
		new_page = alloc_zeroed_user_highpage_movable(vma, address);
		if (!new_page)
			goto oom;
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
		if (!new_page)
			goto oom;
		cow_user_page(new_page, old_page, address, vma);
	}
	__SetPageUptodate(new_page);

K
KAMEZAWA Hiroyuki 已提交
2682
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2683 2684
		goto oom_free_new;

L
Linus Torvalds 已提交
2685 2686 2687
	/*
	 * Re-check the pte - we dropped the lock
	 */
2688
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2689
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2690 2691
		if (old_page) {
			if (!PageAnon(old_page)) {
2692 2693
				dec_mm_counter_fast(mm, MM_FILEPAGES);
				inc_mm_counter_fast(mm, MM_ANONPAGES);
H
Hugh Dickins 已提交
2694 2695
			}
		} else
2696
			inc_mm_counter_fast(mm, MM_ANONPAGES);
2697
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2698 2699
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2700 2701 2702 2703 2704 2705
		/*
		 * 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.
		 */
2706
		ptep_clear_flush(vma, address, page_table);
N
Nick Piggin 已提交
2707
		page_add_new_anon_rmap(new_page, vma, address);
2708 2709 2710 2711 2712 2713
		/*
		 * We call the notify macro here because, when using secondary
		 * mmu page tables (such as kvm shadow page tables), we want the
		 * new page to be mapped directly into the secondary page table.
		 */
		set_pte_at_notify(mm, address, page_table, entry);
2714
		update_mmu_cache(vma, address, page_table);
N
Nick Piggin 已提交
2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737
		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.
			 */
2738
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2739 2740
		}

L
Linus Torvalds 已提交
2741 2742
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2743
		ret |= VM_FAULT_WRITE;
2744 2745 2746
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2747 2748
	if (new_page)
		page_cache_release(new_page);
2749
unlock:
2750
	pte_unmap_unlock(page_table, ptl);
2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762
	if (old_page) {
		/*
		 * Don't let another task, with possibly unlocked vma,
		 * keep the mlocked page.
		 */
		if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
			lock_page(old_page);	/* LRU manipulation */
			munlock_vma_page(old_page);
			unlock_page(old_page);
		}
		page_cache_release(old_page);
	}
N
Nick Piggin 已提交
2763
	return ret;
2764
oom_free_new:
2765
	page_cache_release(new_page);
2766
oom:
N
Nick Piggin 已提交
2767 2768 2769 2770 2771
	if (old_page) {
		if (page_mkwrite) {
			unlock_page(old_page);
			page_cache_release(old_page);
		}
H
Hugh Dickins 已提交
2772
		page_cache_release(old_page);
N
Nick Piggin 已提交
2773
	}
L
Linus Torvalds 已提交
2774
	return VM_FAULT_OOM;
2775 2776 2777

unwritable_page:
	page_cache_release(old_page);
2778
	return ret;
L
Linus Torvalds 已提交
2779 2780
}

2781
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2782 2783 2784
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2785
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807
}

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;

	vma_prio_tree_foreach(vma, &iter, root,
			details->first_index, details->last_index) {

		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;

2808
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2809 2810
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2811
				details);
L
Linus Torvalds 已提交
2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827
	}
}

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.
	 */
	list_for_each_entry(vma, head, shared.vm_set.list) {
		details->nonlinear_vma = vma;
2828
		unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
L
Linus Torvalds 已提交
2829 2830 2831 2832
	}
}

/**
2833
 * 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
2834
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2835 2836
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
N
npiggin@suse.de 已提交
2837
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868
 * 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;


2869
	mutex_lock(&mapping->i_mmap_mutex);
L
Linus Torvalds 已提交
2870 2871 2872 2873
	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);
2874
	mutex_unlock(&mapping->i_mmap_mutex);
L
Linus Torvalds 已提交
2875 2876 2877 2878
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2879 2880 2881
 * 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
2882
 */
2883 2884
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2885
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2886
{
2887
	spinlock_t *ptl;
A
Andrea Arcangeli 已提交
2888
	struct page *page, *swapcache = NULL;
2889
	swp_entry_t entry;
L
Linus Torvalds 已提交
2890
	pte_t pte;
2891
	int locked;
2892
	struct mem_cgroup *ptr;
2893
	int exclusive = 0;
N
Nick Piggin 已提交
2894
	int ret = 0;
L
Linus Torvalds 已提交
2895

H
Hugh Dickins 已提交
2896
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2897
		goto out;
2898 2899

	entry = pte_to_swp_entry(orig_pte);
2900 2901 2902 2903 2904 2905 2906
	if (unlikely(non_swap_entry(entry))) {
		if (is_migration_entry(entry)) {
			migration_entry_wait(mm, pmd, address);
		} else if (is_hwpoison_entry(entry)) {
			ret = VM_FAULT_HWPOISON;
		} else {
			print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
2907
			ret = VM_FAULT_SIGBUS;
2908
		}
2909 2910
		goto out;
	}
2911
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2912 2913
	page = lookup_swap_cache(entry);
	if (!page) {
H
Hugh Dickins 已提交
2914
		grab_swap_token(mm); /* Contend for token _before_ read-in */
2915 2916
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2917 2918
		if (!page) {
			/*
2919 2920
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2921
			 */
2922
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2923 2924
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2925
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2926
			goto unlock;
L
Linus Torvalds 已提交
2927 2928 2929 2930
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2931
		count_vm_event(PGMAJFAULT);
2932
		mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2933
	} else if (PageHWPoison(page)) {
2934 2935 2936 2937
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2938 2939
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2940
		goto out_release;
L
Linus Torvalds 已提交
2941 2942
	}

2943
	locked = lock_page_or_retry(page, mm, flags);
2944
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2945 2946 2947 2948
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2949

A
Andrea Arcangeli 已提交
2950
	/*
2951 2952 2953 2954
	 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
	 * release the swapcache from under us.  The page pin, and pte_same
	 * test below, are not enough to exclude that.  Even if it is still
	 * swapcache, we need to check that the page's swap has not changed.
A
Andrea Arcangeli 已提交
2955
	 */
2956
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968
		goto out_page;

	if (ksm_might_need_to_copy(page, vma, address)) {
		swapcache = page;
		page = ksm_does_need_to_copy(page, vma, address);

		if (unlikely(!page)) {
			ret = VM_FAULT_OOM;
			page = swapcache;
			swapcache = NULL;
			goto out_page;
		}
H
Hugh Dickins 已提交
2969 2970
	}

K
KAMEZAWA Hiroyuki 已提交
2971
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2972
		ret = VM_FAULT_OOM;
2973
		goto out_page;
2974 2975
	}

L
Linus Torvalds 已提交
2976
	/*
2977
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2978
	 */
2979
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2980
	if (unlikely(!pte_same(*page_table, orig_pte)))
2981 2982 2983 2984 2985
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2986 2987
	}

2988 2989 2990 2991 2992 2993 2994 2995
	/*
	 * 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.
2996 2997 2998 2999
	 * 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().
3000
	 */
L
Linus Torvalds 已提交
3001

3002
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
3003
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
3004
	pte = mk_pte(page, vma->vm_page_prot);
3005
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
3006
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3007
		flags &= ~FAULT_FLAG_WRITE;
3008
		ret |= VM_FAULT_WRITE;
3009
		exclusive = 1;
L
Linus Torvalds 已提交
3010 3011 3012
	}
	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
3013
	do_page_add_anon_rmap(page, vma, address, exclusive);
3014 3015
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
3016

3017
	swap_free(entry);
N
Nick Piggin 已提交
3018
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3019
		try_to_free_swap(page);
3020
	unlock_page(page);
A
Andrea Arcangeli 已提交
3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032
	if (swapcache) {
		/*
		 * Hold the lock to avoid the swap entry to be reused
		 * until we take the PT lock for the pte_same() check
		 * (to avoid false positives from pte_same). For
		 * further safety release the lock after the swap_free
		 * so that the swap count won't change under a
		 * parallel locked swapcache.
		 */
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
3033

3034
	if (flags & FAULT_FLAG_WRITE) {
3035 3036 3037
		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
3038 3039 3040 3041
		goto out;
	}

	/* No need to invalidate - it was non-present before */
3042
	update_mmu_cache(vma, address, page_table);
3043
unlock:
3044
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
3045 3046
out:
	return ret;
3047
out_nomap:
3048
	mem_cgroup_cancel_charge_swapin(ptr);
3049
	pte_unmap_unlock(page_table, ptl);
3050
out_page:
3051
	unlock_page(page);
3052
out_release:
3053
	page_cache_release(page);
A
Andrea Arcangeli 已提交
3054 3055 3056 3057
	if (swapcache) {
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
3058
	return ret;
L
Linus Torvalds 已提交
3059 3060
}

3061
/*
3062 3063
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3064 3065 3066 3067 3068 3069
 * doesn't hit another vma.
 */
static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
{
	address &= PAGE_MASK;
	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3070 3071 3072 3073 3074 3075 3076 3077 3078 3079
		struct vm_area_struct *prev = vma->vm_prev;

		/*
		 * Is there a mapping abutting this one below?
		 *
		 * That's only ok if it's the same stack mapping
		 * that has gotten split..
		 */
		if (prev && prev->vm_end == address)
			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3080

3081
		expand_downwards(vma, address - PAGE_SIZE);
3082
	}
3083 3084 3085 3086 3087 3088 3089 3090 3091
	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
		struct vm_area_struct *next = vma->vm_next;

		/* As VM_GROWSDOWN but s/below/above/ */
		if (next && next->vm_start == address + PAGE_SIZE)
			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;

		expand_upwards(vma, address + PAGE_SIZE);
	}
3092 3093 3094
	return 0;
}

L
Linus Torvalds 已提交
3095
/*
3096 3097 3098
 * 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
3099
 */
3100 3101
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3102
		unsigned int flags)
L
Linus Torvalds 已提交
3103
{
3104 3105
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3106 3107
	pte_t entry;

3108 3109 3110 3111
	pte_unmap(page_table);

	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
3112 3113
		return VM_FAULT_SIGBUS;

3114
	/* Use the zero-page for reads */
H
Hugh Dickins 已提交
3115 3116 3117
	if (!(flags & FAULT_FLAG_WRITE)) {
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
3118
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
3119 3120 3121 3122 3123
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
3124 3125 3126 3127 3128 3129
	/* Allocate our own private page. */
	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
3130
	__SetPageUptodate(page);
3131

K
KAMEZAWA Hiroyuki 已提交
3132
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3133 3134
		goto oom_free_page;

N
Nick Piggin 已提交
3135
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
3136 3137
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
3138

N
Nick Piggin 已提交
3139
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3140
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
3141
		goto release;
H
Hugh Dickins 已提交
3142

3143
	inc_mm_counter_fast(mm, MM_ANONPAGES);
N
Nick Piggin 已提交
3144
	page_add_new_anon_rmap(page, vma, address);
H
Hugh Dickins 已提交
3145
setpte:
3146
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
3147 3148

	/* No need to invalidate - it was non-present before */
3149
	update_mmu_cache(vma, address, page_table);
3150
unlock:
3151
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
3152
	return 0;
3153
release:
3154
	mem_cgroup_uncharge_page(page);
3155 3156
	page_cache_release(page);
	goto unlock;
3157
oom_free_page:
3158
	page_cache_release(page);
3159
oom:
L
Linus Torvalds 已提交
3160 3161 3162 3163
	return VM_FAULT_OOM;
}

/*
3164
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
3165
 * tries to share with existing pages, but makes a separate copy if
3166 3167
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
3168 3169 3170 3171
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
3172
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3173
 * but allow concurrent faults), and pte neither mapped nor locked.
3174
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
3175
 */
3176
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3177
		unsigned long address, pmd_t *pmd,
3178
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3179
{
3180
	pte_t *page_table;
3181
	spinlock_t *ptl;
N
Nick Piggin 已提交
3182
	struct page *page;
3183
	struct page *cow_page;
L
Linus Torvalds 已提交
3184 3185
	pte_t entry;
	int anon = 0;
3186
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
3187 3188
	struct vm_fault vmf;
	int ret;
3189
	int page_mkwrite = 0;
3190

3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210
	/*
	 * If we do COW later, allocate page befor taking lock_page()
	 * on the file cache page. This will reduce lock holding time.
	 */
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {

		if (unlikely(anon_vma_prepare(vma)))
			return VM_FAULT_OOM;

		cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
		if (!cow_page)
			return VM_FAULT_OOM;

		if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
			page_cache_release(cow_page);
			return VM_FAULT_OOM;
		}
	} else
		cow_page = NULL;

N
Nick Piggin 已提交
3211 3212 3213 3214
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
3215

N
Nick Piggin 已提交
3216
	ret = vma->vm_ops->fault(vma, &vmf);
3217 3218
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
			    VM_FAULT_RETRY)))
3219
		goto uncharge_out;
L
Linus Torvalds 已提交
3220

3221 3222 3223
	if (unlikely(PageHWPoison(vmf.page))) {
		if (ret & VM_FAULT_LOCKED)
			unlock_page(vmf.page);
3224 3225
		ret = VM_FAULT_HWPOISON;
		goto uncharge_out;
3226 3227
	}

3228
	/*
N
Nick Piggin 已提交
3229
	 * For consistency in subsequent calls, make the faulted page always
3230 3231
	 * locked.
	 */
N
Nick Piggin 已提交
3232
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
3233
		lock_page(vmf.page);
3234
	else
N
Nick Piggin 已提交
3235
		VM_BUG_ON(!PageLocked(vmf.page));
3236

L
Linus Torvalds 已提交
3237 3238 3239
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
3240
	page = vmf.page;
3241
	if (flags & FAULT_FLAG_WRITE) {
3242
		if (!(vma->vm_flags & VM_SHARED)) {
3243
			page = cow_page;
3244
			anon = 1;
N
Nick Piggin 已提交
3245
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
3246
			__SetPageUptodate(page);
3247
		} else {
3248 3249
			/*
			 * If the page will be shareable, see if the backing
3250
			 * address space wants to know that the page is about
3251 3252
			 * to become writable
			 */
3253
			if (vma->vm_ops->page_mkwrite) {
3254 3255
				int tmp;

3256
				unlock_page(page);
N
Nick Piggin 已提交
3257
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3258 3259 3260 3261
				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
3262
					goto unwritable_page;
N
Nick Piggin 已提交
3263
				}
N
Nick Piggin 已提交
3264 3265 3266 3267 3268 3269 3270 3271 3272
				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));
3273
				page_mkwrite = 1;
3274 3275
			}
		}
3276

L
Linus Torvalds 已提交
3277 3278
	}

3279
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
3280 3281 3282 3283 3284 3285

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
3286
	 * Note that if FAULT_FLAG_WRITE is set, we either now have
L
Linus Torvalds 已提交
3287 3288 3289 3290 3291
	 * 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... */
3292
	if (likely(pte_same(*page_table, orig_pte))) {
3293 3294
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
3295
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
3296 3297
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
3298
			inc_mm_counter_fast(mm, MM_ANONPAGES);
3299
			page_add_new_anon_rmap(page, vma, address);
3300
		} else {
3301
			inc_mm_counter_fast(mm, MM_FILEPAGES);
3302
			page_add_file_rmap(page);
3303
			if (flags & FAULT_FLAG_WRITE) {
3304
				dirty_page = page;
3305 3306
				get_page(dirty_page);
			}
3307
		}
3308
		set_pte_at(mm, address, page_table, entry);
3309 3310

		/* no need to invalidate: a not-present page won't be cached */
3311
		update_mmu_cache(vma, address, page_table);
L
Linus Torvalds 已提交
3312
	} else {
3313 3314
		if (cow_page)
			mem_cgroup_uncharge_page(cow_page);
3315 3316 3317
		if (anon)
			page_cache_release(page);
		else
3318
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
3319 3320
	}

3321
	pte_unmap_unlock(page_table, ptl);
3322

N
Nick Piggin 已提交
3323 3324
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
3325

N
Nick Piggin 已提交
3326 3327 3328
		if (set_page_dirty(dirty_page))
			page_mkwrite = 1;
		unlock_page(dirty_page);
3329
		put_page(dirty_page);
N
Nick Piggin 已提交
3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344
		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);
3345
	}
3346

N
Nick Piggin 已提交
3347
	return ret;
N
Nick Piggin 已提交
3348 3349 3350 3351

unwritable_page:
	page_cache_release(page);
	return ret;
3352 3353 3354 3355 3356 3357 3358
uncharge_out:
	/* fs's fault handler get error */
	if (cow_page) {
		mem_cgroup_uncharge_page(cow_page);
		page_cache_release(cow_page);
	}
	return ret;
3359
}
3360

3361 3362
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3363
		unsigned int flags, pte_t orig_pte)
3364 3365
{
	pgoff_t pgoff = (((address & PAGE_MASK)
3366
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3367

3368 3369
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3370 3371
}

L
Linus Torvalds 已提交
3372 3373 3374 3375
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
3376 3377 3378 3379
 *
 * 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
3380
 */
N
Nick Piggin 已提交
3381
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3382
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3383
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3384
{
3385
	pgoff_t pgoff;
L
Linus Torvalds 已提交
3386

3387 3388
	flags |= FAULT_FLAG_NONLINEAR;

H
Hugh Dickins 已提交
3389
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
3390
		return 0;
L
Linus Torvalds 已提交
3391

3392
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3393 3394 3395
		/*
		 * Page table corrupted: show pte and kill process.
		 */
3396
		print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
3397
		return VM_FAULT_SIGBUS;
3398 3399 3400
	}

	pgoff = pte_to_pgoff(orig_pte);
3401
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412
}

/*
 * 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
3413 3414 3415
 * 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
3416
 */
3417 3418 3419
int handle_pte_fault(struct mm_struct *mm,
		     struct vm_area_struct *vma, unsigned long address,
		     pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3420 3421
{
	pte_t entry;
3422
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3423

3424
	entry = *pte;
L
Linus Torvalds 已提交
3425
	if (!pte_present(entry)) {
3426
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
3427
			if (vma->vm_ops) {
N
Nick Piggin 已提交
3428
				if (likely(vma->vm_ops->fault))
3429
					return do_linear_fault(mm, vma, address,
3430
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
3431 3432
			}
			return do_anonymous_page(mm, vma, address,
3433
						 pte, pmd, flags);
3434
		}
L
Linus Torvalds 已提交
3435
		if (pte_file(entry))
N
Nick Piggin 已提交
3436
			return do_nonlinear_fault(mm, vma, address,
3437
					pte, pmd, flags, entry);
3438
		return do_swap_page(mm, vma, address,
3439
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3440 3441
	}

H
Hugh Dickins 已提交
3442
	ptl = pte_lockptr(mm, pmd);
3443 3444 3445
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3446
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3447
		if (!pte_write(entry))
3448 3449
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3450 3451 3452
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3453
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3454
		update_mmu_cache(vma, address, pte);
3455 3456 3457 3458 3459 3460 3461
	} 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.
		 */
3462
		if (flags & FAULT_FLAG_WRITE)
3463
			flush_tlb_fix_spurious_fault(vma, address);
3464
	}
3465 3466
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3467
	return 0;
L
Linus Torvalds 已提交
3468 3469 3470 3471 3472
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
3473
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3474
		unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
3475 3476 3477 3478 3479 3480 3481 3482
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

3483
	count_vm_event(PGFAULT);
3484
	mem_cgroup_count_vm_event(mm, PGFAULT);
L
Linus Torvalds 已提交
3485

3486 3487 3488
	/* do counter updates before entering really critical section. */
	check_sync_rss_stat(current);

3489
	if (unlikely(is_vm_hugetlb_page(vma)))
3490
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3491 3492 3493 3494

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3495
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3496 3497
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3498
		return VM_FAULT_OOM;
3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513 3514 3515 3516 3517 3518 3519 3520
	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
		if (!vma->vm_ops)
			return do_huge_pmd_anonymous_page(mm, vma, address,
							  pmd, flags);
	} else {
		pmd_t orig_pmd = *pmd;
		barrier();
		if (pmd_trans_huge(orig_pmd)) {
			if (flags & FAULT_FLAG_WRITE &&
			    !pmd_write(orig_pmd) &&
			    !pmd_trans_splitting(orig_pmd))
				return do_huge_pmd_wp_page(mm, vma, address,
							   pmd, orig_pmd);
			return 0;
		}
	}

	/*
	 * Use __pte_alloc instead of pte_alloc_map, because we can't
	 * run pte_offset_map on the pmd, if an huge pmd could
	 * materialize from under us from a different thread.
	 */
3521
	if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
H
Hugh Dickins 已提交
3522
		return VM_FAULT_OOM;
3523 3524 3525 3526 3527 3528 3529 3530 3531 3532
	/* if an huge pmd materialized from under us just retry later */
	if (unlikely(pmd_trans_huge(*pmd)))
		return 0;
	/*
	 * A regular pmd is established and it can't morph into a huge pmd
	 * from under us anymore at this point because we hold the mmap_sem
	 * read mode and khugepaged takes it in write mode. So now it's
	 * safe to run pte_offset_map().
	 */
	pte = pte_offset_map(pmd, address);
L
Linus Torvalds 已提交
3533

3534
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3535 3536 3537 3538 3539
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3540
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3541
 */
3542
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3543
{
H
Hugh Dickins 已提交
3544 3545
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3546
		return -ENOMEM;
L
Linus Torvalds 已提交
3547

3548 3549
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3550
	spin_lock(&mm->page_table_lock);
3551
	if (pgd_present(*pgd))		/* Another has populated it */
3552
		pud_free(mm, new);
3553 3554
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3555
	spin_unlock(&mm->page_table_lock);
3556
	return 0;
L
Linus Torvalds 已提交
3557 3558 3559 3560 3561 3562
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3563
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3564
 */
3565
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3566
{
H
Hugh Dickins 已提交
3567 3568
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3569
		return -ENOMEM;
L
Linus Torvalds 已提交
3570

3571 3572
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3573
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3574
#ifndef __ARCH_HAS_4LEVEL_HACK
3575
	if (pud_present(*pud))		/* Another has populated it */
3576
		pmd_free(mm, new);
3577 3578
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3579
#else
3580
	if (pgd_present(*pud))		/* Another has populated it */
3581
		pmd_free(mm, new);
3582 3583
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3584
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3585
	spin_unlock(&mm->page_table_lock);
3586
	return 0;
3587
}
L
Linus Torvalds 已提交
3588 3589 3590 3591 3592 3593 3594 3595 3596
#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
3597
		return -ENOMEM;
3598 3599 3600 3601 3602 3603
	/*
	 * We want to touch writable mappings with a write fault in order
	 * to break COW, except for shared mappings because these don't COW
	 * and we would not want to dirty them for nothing.
	 */
	write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3604 3605
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
3606
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
3607 3608
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
3609
	if (ret < 0)
L
Linus Torvalds 已提交
3610
		return ret;
3611
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
3612 3613 3614 3615 3616
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
3617
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
3618 3619 3620 3621 3622 3623

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
3624 3625
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
3626

L
Linus Torvalds 已提交
3627 3628 3629 3630 3631
	return 0;
}
__initcall(gate_vma_init);
#endif

3632
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
L
Linus Torvalds 已提交
3633 3634 3635 3636 3637 3638 3639 3640
{
#ifdef AT_SYSINFO_EHDR
	return &gate_vma;
#else
	return NULL;
#endif
}

3641
int in_gate_area_no_mm(unsigned long addr)
L
Linus Torvalds 已提交
3642 3643 3644 3645 3646 3647 3648 3649 3650
{
#ifdef AT_SYSINFO_EHDR
	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
		return 1;
#endif
	return 0;
}

#endif	/* __HAVE_ARCH_GATE_AREA */
3651

3652
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3653 3654 3655 3656 3657 3658 3659 3660 3661 3662 3663 3664 3665 3666 3667 3668
		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);
3669
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682 3683 3684 3685 3686 3687 3688 3689
	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;
}

3690 3691 3692 3693 3694 3695 3696 3697 3698 3699 3700
static inline int follow_pte(struct mm_struct *mm, unsigned long address,
			     pte_t **ptepp, spinlock_t **ptlp)
{
	int res;

	/* (void) is needed to make gcc happy */
	(void) __cond_lock(*ptlp,
			   !(res = __follow_pte(mm, address, ptepp, ptlp)));
	return res;
}

J
Johannes Weiner 已提交
3701 3702 3703 3704 3705 3706 3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722 3723 3724 3725 3726 3727 3728 3729
/**
 * 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);

3730
#ifdef CONFIG_HAVE_IOREMAP_PROT
3731 3732 3733
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3734
{
3735
	int ret = -EINVAL;
3736 3737 3738
	pte_t *ptep, pte;
	spinlock_t *ptl;

3739 3740
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3741

3742
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3743
		goto out;
3744
	pte = *ptep;
3745

3746 3747 3748 3749
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3750
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3751

3752
	ret = 0;
3753 3754 3755
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3756
	return ret;
3757 3758 3759 3760 3761 3762 3763
}

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
3764
	void __iomem *maddr;
3765 3766
	int offset = addr & (PAGE_SIZE-1);

3767
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3768 3769 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780
		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

3781
/*
3782 3783
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3784
 */
3785 3786
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
3787 3788 3789 3790 3791
{
	struct vm_area_struct *vma;
	void *old_buf = buf;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3792
	/* ignore errors, just check how much was successfully transferred */
3793 3794 3795
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3796
		struct page *page = NULL;
3797 3798 3799

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3800 3801 3802 3803 3804 3805 3806
		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);
3807
			if (!vma || vma->vm_start > addr)
3808 3809 3810 3811 3812 3813 3814 3815
				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;
3816
		} else {
3817 3818 3819 3820 3821 3822 3823 3824 3825 3826 3827 3828 3829 3830 3831 3832
			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);
3833 3834 3835 3836 3837 3838 3839 3840 3841
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
3842

S
Stephen Wilson 已提交
3843
/**
3844
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
3845 3846 3847 3848 3849 3850 3851 3852 3853 3854 3855 3856 3857 3858
 * @mm:		the mm_struct of the target address space
 * @addr:	start address to access
 * @buf:	source or destination buffer
 * @len:	number of bytes to transfer
 * @write:	whether the access is a write
 *
 * The caller must hold a reference on @mm.
 */
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
		void *buf, int len, int write)
{
	return __access_remote_vm(NULL, mm, addr, buf, len, write);
}

3859 3860 3861 3862 3863 3864 3865 3866 3867 3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879
/*
 * 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;
	int ret;

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

	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
	mmput(mm);

	return ret;
}

3880 3881 3882 3883 3884 3885 3886 3887
/*
 * 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;

3888 3889 3890 3891 3892 3893 3894
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3895 3896 3897 3898 3899 3900 3901 3902
	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;

3903
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3904 3905 3906 3907 3908 3909 3910 3911 3912 3913 3914 3915 3916
			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);
}
3917 3918 3919 3920

#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
3921 3922 3923 3924 3925 3926 3927 3928 3929
	/*
	 * 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;

3930 3931 3932 3933 3934 3935 3936 3937 3938 3939 3940
	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
A
Andrea Arcangeli 已提交
3941 3942 3943 3944 3945 3946 3947 3948 3949 3950 3951 3952 3953 3954 3955 3956 3957 3958 3959 3960 3961 3962 3963 3964 3965 3966 3967 3968 3969 3970 3971 3972 3973 3974 3975 3976 3977 3978 3979 3980 3981 3982 3983 3984 3985 3986 3987 3988 3989 3990 3991 3992 3993 3994 3995 3996 3997 3998 3999 4000 4001 4002 4003 4004 4005 4006 4007 4008 4009 4010 4011

#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
static void clear_gigantic_page(struct page *page,
				unsigned long addr,
				unsigned int pages_per_huge_page)
{
	int i;
	struct page *p = page;

	might_sleep();
	for (i = 0; i < pages_per_huge_page;
	     i++, p = mem_map_next(p, page, i)) {
		cond_resched();
		clear_user_highpage(p, addr + i * PAGE_SIZE);
	}
}
void clear_huge_page(struct page *page,
		     unsigned long addr, unsigned int pages_per_huge_page)
{
	int i;

	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
		clear_gigantic_page(page, addr, pages_per_huge_page);
		return;
	}

	might_sleep();
	for (i = 0; i < pages_per_huge_page; i++) {
		cond_resched();
		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
	}
}

static void copy_user_gigantic_page(struct page *dst, struct page *src,
				    unsigned long addr,
				    struct vm_area_struct *vma,
				    unsigned int pages_per_huge_page)
{
	int i;
	struct page *dst_base = dst;
	struct page *src_base = src;

	for (i = 0; i < pages_per_huge_page; ) {
		cond_resched();
		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);

		i++;
		dst = mem_map_next(dst, dst_base, i);
		src = mem_map_next(src, src_base, i);
	}
}

void copy_user_huge_page(struct page *dst, struct page *src,
			 unsigned long addr, struct vm_area_struct *vma,
			 unsigned int pages_per_huge_page)
{
	int i;

	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
		copy_user_gigantic_page(dst, src, addr, vma,
					pages_per_huge_page);
		return;
	}

	might_sleep();
	for (i = 0; i < pages_per_huge_page; i++) {
		cond_resched();
		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
	}
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */