memory.c 86.3 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include <linux/module.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/writeback.h>
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#include <linux/memcontrol.h>
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#include <linux/mmu_notifier.h>
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#include <linux/kallsyms.h>
#include <linux/swapops.h>
#include <linux/elf.h>
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#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>

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#include "internal.h"

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

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

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

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);

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


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

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

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

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

/*
 * Note: this doesn't free the actual pages themselves. That
 * has been handled earlier when unmapping all the memory regions.
 */
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static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
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{
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	pgtable_t token = pmd_pgtable(*pmd);
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	pmd_clear(pmd);
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	pte_free_tlb(tlb, token);
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	tlb->mm->nr_ptes--;
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}

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static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pmd_t *pmd;
	unsigned long next;
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	unsigned long start;
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	start = addr;
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	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			continue;
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		free_pte_range(tlb, pmd);
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	} while (pmd++, addr = next, addr != end);

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	start &= PUD_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

	pmd = pmd_offset(pud, start);
	pud_clear(pud);
	pmd_free_tlb(tlb, pmd);
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}

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static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pud_t *pud;
	unsigned long next;
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	unsigned long start;
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	start = addr;
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	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
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		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
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	} while (pud++, addr = next, addr != end);

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	start &= PGDIR_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

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

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

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

	start = addr;
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	pgd = pgd_offset(tlb->mm, addr);
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	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
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		free_pud_range(tlb, pgd, addr, next, floor, ceiling);
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	} while (pgd++, addr = next, addr != end);
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}

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void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
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		unsigned long floor, unsigned long ceiling)
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{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

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		/*
		 * Hide vma from rmap and vmtruncate before freeing pgtables
		 */
		anon_vma_unlink(vma);
		unlink_file_vma(vma);

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		if (is_vm_hugetlb_page(vma)) {
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			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
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				floor, next? next->vm_start: ceiling);
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		} else {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
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			       && !is_vm_hugetlb_page(next)) {
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				vma = next;
				next = vma->vm_next;
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				anon_vma_unlink(vma);
				unlink_file_vma(vma);
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			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
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		vma = next;
	}
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}

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int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
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{
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	pgtable_t new = pte_alloc_one(mm, address);
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	if (!new)
		return -ENOMEM;

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

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	spin_lock(&mm->page_table_lock);
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	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
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		mm->nr_ptes++;
		pmd_populate(mm, pmd, new);
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		new = NULL;
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	}
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	spin_unlock(&mm->page_table_lock);
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	if (new)
		pte_free(mm, new);
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	return 0;
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}

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int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
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{
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	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
	if (!new)
		return -ENOMEM;

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

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	spin_lock(&init_mm.page_table_lock);
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	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
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		pmd_populate_kernel(&init_mm, pmd, new);
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		new = NULL;
	}
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	spin_unlock(&init_mm.page_table_lock);
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	if (new)
		pte_free_kernel(&init_mm, new);
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	return 0;
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}

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static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
{
	if (file_rss)
		add_mm_counter(mm, file_rss, file_rss);
	if (anon_rss)
		add_mm_counter(mm, anon_rss, anon_rss);
}

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/*
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 * This function is called to print an error when a bad pte
 * is found. For example, we might have a PFN-mapped pte in
 * a region that doesn't allow it.
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 *
 * The calling function must still handle the error.
 */
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static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
			  pte_t pte, struct page *page)
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{
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	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
	pud_t *pud = pud_offset(pgd, addr);
	pmd_t *pmd = pmd_offset(pud, addr);
	struct address_space *mapping;
	pgoff_t index;
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	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

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

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

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

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/*
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 * vm_normal_page -- This function gets the "struct page" associated with a pte.
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 *
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 * "Special" mappings do not wish to be associated with a "struct page" (either
 * it doesn't exist, or it exists but they don't want to touch it). In this
 * case, NULL is returned here. "Normal" mappings do have a struct page.
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 *
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 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 * pte bit, in which case this function is trivial. Secondly, an architecture
 * may not have a spare pte bit, which requires a more complicated scheme,
 * described below.
 *
 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 * special mapping (even if there are underlying and valid "struct pages").
 * COWed pages of a VM_PFNMAP are always normal.
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 *
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 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
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 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
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 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
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 * And for normal mappings this is false.
 *
 * This restricts such mappings to be a linear translation from virtual address
 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 * as the vma is not a COW mapping; in that case, we know that all ptes are
 * special (because none can have been COWed).
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 *
 *
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 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
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 *
 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 * page" backing, however the difference is that _all_ pages with a struct
 * page (that is, those where pfn_valid is true) are refcounted and considered
 * normal pages by the VM. The disadvantage is that pages are refcounted
 * (which can be slower and simply not an option for some PFNMAP users). The
 * advantage is that we don't have to follow the strict linearity rule of
 * PFNMAP mappings in order to support COWable mappings.
 *
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 */
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#ifdef __HAVE_ARCH_PTE_SPECIAL
# define HAVE_PTE_SPECIAL 1
#else
# define HAVE_PTE_SPECIAL 0
#endif
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
				pte_t pte)
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{
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	unsigned long pfn = pte_pfn(pte);
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	if (HAVE_PTE_SPECIAL) {
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		if (likely(!pte_special(pte)))
			goto check_pfn;
		if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)))
			print_bad_pte(vma, addr, pte, NULL);
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		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

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	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
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			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
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			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
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	}

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check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
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	/*
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	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
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	 */
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out:
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	return pfn_to_page(pfn);
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}

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/*
 * copy one vm_area from one task to the other. Assumes the page tables
 * already present in the new task to be cleared in the whole range
 * covered by this vma.
 */

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

	/* pte contains position in swap or file, so copy. */
	if (unlikely(!pte_present(pte))) {
		if (!pte_file(pte)) {
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			swp_entry_t entry = pte_to_swp_entry(pte);

			swap_duplicate(entry);
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			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
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				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
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				spin_unlock(&mmlist_lock);
			}
564 565 566 567 568 569 570 571 572 573
			if (is_write_migration_entry(entry) &&
					is_cow_mapping(vm_flags)) {
				/*
				 * COW mappings require pages in both parent
				 * and child to be set to read.
				 */
				make_migration_entry_read(&entry);
				pte = swp_entry_to_pte(entry);
				set_pte_at(src_mm, addr, src_pte, pte);
			}
L
Linus Torvalds 已提交
574
		}
575
		goto out_set_pte;
L
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576 577 578 579 580 581
	}

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

	/*
	 * If it's a shared mapping, mark it clean in
	 * the child
	 */
	if (vm_flags & VM_SHARED)
		pte = pte_mkclean(pte);
	pte = pte_mkold(pte);
594 595 596 597

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

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
L
Linus Torvalds 已提交
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}

static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
611
	spinlock_t *src_ptl, *dst_ptl;
612
	int progress = 0;
H
Hugh Dickins 已提交
613
	int rss[2];
L
Linus Torvalds 已提交
614 615

again:
616
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
617
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
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	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
621
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
622
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
623
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
624 625 626 627 628 629

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

644
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
645
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
646
	pte_unmap_nested(src_pte - 1);
647
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
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	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
L
Linus Torvalds 已提交
650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705
	if (addr != end)
		goto again;
	return 0;
}

static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pmd_t *src_pmd, *dst_pmd;
	unsigned long next;

	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
	if (!dst_pmd)
		return -ENOMEM;
	src_pmd = pmd_offset(src_pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(src_pmd))
			continue;
		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
	return 0;
}

static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pud_t *src_pud, *dst_pud;
	unsigned long next;

	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
	if (!dst_pud)
		return -ENOMEM;
	src_pud = pud_offset(src_pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(src_pud))
			continue;
		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pud++, src_pud++, addr = next, addr != end);
	return 0;
}

int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		struct vm_area_struct *vma)
{
	pgd_t *src_pgd, *dst_pgd;
	unsigned long next;
	unsigned long addr = vma->vm_start;
	unsigned long end = vma->vm_end;
A
Andrea Arcangeli 已提交
706
	int ret;
L
Linus Torvalds 已提交
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708 709 710 711 712 713
	/*
	 * Don't copy ptes where a page fault will fill them correctly.
	 * Fork becomes much lighter when there are big shared or private
	 * readonly mappings. The tradeoff is that copy_page_range is more
	 * efficient than faulting.
	 */
714
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
715 716 717 718
		if (!vma->anon_vma)
			return 0;
	}

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

722
	if (unlikely(is_pfn_mapping(vma))) {
723 724 725 726 727 728 729 730 731
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
		ret = track_pfn_vma_copy(vma);
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
732 733 734 735 736 737 738 739 740 741
	/*
	 * We need to invalidate the secondary MMU mappings only when
	 * there could be a permission downgrade on the ptes of the
	 * parent mm. And a permission downgrade will only happen if
	 * is_cow_mapping() returns true.
	 */
	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_start(src_mm, addr, end);

	ret = 0;
L
Linus Torvalds 已提交
742 743 744 745 746 747
	dst_pgd = pgd_offset(dst_mm, addr);
	src_pgd = pgd_offset(src_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(src_pgd))
			continue;
A
Andrea Arcangeli 已提交
748 749 750 751 752
		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
					    vma, addr, next))) {
			ret = -ENOMEM;
			break;
		}
L
Linus Torvalds 已提交
753
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
754 755 756 757 758

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

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

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

		(*zap_work) -= PAGE_SIZE;

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

786
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
				/*
				 * Each page->index must be checked when
				 * invalidating or truncating nonlinear.
				 */
				if (details->nonlinear_vma &&
				    (page->index < details->first_index ||
				     page->index > details->last_index))
					continue;
			}
N
Nick Piggin 已提交
805
			ptent = ptep_get_and_clear_full(mm, addr, pte,
806
							tlb->fullmm);
L
Linus Torvalds 已提交
807 808 809 810 811 812
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (unlikely(details) && details->nonlinear_vma
			    && linear_page_index(details->nonlinear_vma,
						addr) != page->index)
N
Nick Piggin 已提交
813
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
814 815
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
816
				anon_rss--;
817 818 819
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
820 821
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
822
					mark_page_accessed(page);
H
Hugh Dickins 已提交
823
				file_rss--;
824
			}
825
			page_remove_rmap(page);
826 827
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
L
Linus Torvalds 已提交
828 829 830 831 832 833 834 835 836
			tlb_remove_page(tlb, page);
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
837 838 839 840 841 842
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
		} else if
		  (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
			print_bad_pte(vma, addr, ptent, NULL);
843
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
844
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
845

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

	return addr;
L
Linus Torvalds 已提交
851 852
}

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

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
864 865
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
866
			continue;
867 868 869 870 871 872
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
873 874
}

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

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
886 887
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
888
			continue;
889 890 891 892 893 894
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
895 896
}

897 898
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
899
				unsigned long addr, unsigned long end,
900
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
901 902 903 904 905 906 907 908 909 910 911 912
{
	pgd_t *pgd;
	unsigned long next;

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

	BUG_ON(addr >= end);
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
913 914
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
915
			continue;
916 917 918 919
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
L
Linus Torvalds 已提交
920
	tlb_end_vma(tlb, vma);
921 922

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

#ifdef CONFIG_PREEMPT
# define ZAP_BLOCK_SIZE	(8 * PAGE_SIZE)
#else
/* No preempt: go for improved straight-line efficiency */
# define ZAP_BLOCK_SIZE	(1024 * PAGE_SIZE)
#endif

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
 * @tlbp: address of the caller's struct mmu_gather
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 * @details: details of nonlinear truncation or shared cache invalidation
 *
941
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
942
 *
943
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
944
 *
945 946
 * We aim to not hold locks for too long (for scheduling latency reasons).
 * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
L
Linus Torvalds 已提交
947 948 949 950 951 952 953 954 955 956 957
 * return the ending mmu_gather to the caller.
 *
 * Only addresses between `start' and `end' will be unmapped.
 *
 * The VMA list must be sorted in ascending virtual address order.
 *
 * unmap_vmas() assumes that the caller will flush the whole unmapped address
 * range after unmap_vmas() returns.  So the only responsibility here is to
 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 * drops the lock and schedules.
 */
958
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
959 960 961 962
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
963
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
964 965
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
966
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
967
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
968
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
969
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
970

A
Andrea Arcangeli 已提交
971
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
972 973 974 975 976 977 978 979 980 981 982 983 984
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
		unsigned long end;

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

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

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

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

994
			if (unlikely(is_vm_hugetlb_page(vma))) {
995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008
				/*
				 * It is undesirable to test vma->vm_file as it
				 * should be non-null for valid hugetlb area.
				 * However, vm_file will be NULL in the error
				 * cleanup path of do_mmap_pgoff. When
				 * hugetlbfs ->mmap method fails,
				 * do_mmap_pgoff() nullifies vma->vm_file
				 * before calling this function to clean up.
				 * Since no pte has actually been setup, it is
				 * safe to do nothing in this case.
				 */
				if (vma->vm_file) {
					unmap_hugepage_range(vma, start, end, NULL);
					zap_work -= (end - start) /
1009
					pages_per_huge_page(hstate_vma(vma));
1010 1011
				}

1012 1013 1014 1015 1016 1017 1018 1019
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

			if (zap_work > 0) {
				BUG_ON(start != end);
				break;
L
Linus Torvalds 已提交
1020 1021 1022 1023 1024
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

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

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

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
 */
1050
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1051 1052 1053 1054 1055 1056 1057 1058 1059
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
	struct mmu_gather *tlb;
	unsigned long end = address + size;
	unsigned long nr_accounted = 0;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
1060
	update_hiwater_rss(mm);
1061 1062 1063
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1064
	return end;
L
Linus Torvalds 已提交
1065 1066
}

1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089
/**
 * zap_vma_ptes - remove ptes mapping the vma
 * @vma: vm_area_struct holding ptes to be zapped
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 *
 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
 *
 * The entire address range must be fully contained within the vma.
 *
 * Returns 0 if successful.
 */
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
		unsigned long size)
{
	if (address < vma->vm_start || address + size > vma->vm_end ||
	    		!(vma->vm_flags & VM_PFNMAP))
		return -1;
	zap_page_range(vma, address, size, NULL);
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

L
Linus Torvalds 已提交
1090 1091 1092
/*
 * Do a quick page-table lookup for a single page.
 */
1093
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1094
			unsigned int flags)
L
Linus Torvalds 已提交
1095 1096 1097 1098 1099
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1100
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1101
	struct page *page;
1102
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1103

1104 1105 1106 1107 1108
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
Linus Torvalds 已提交
1109

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

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1116
	if (pud_none(*pud))
1117
		goto no_page_table;
A
Andi Kleen 已提交
1118 1119 1120 1121 1122 1123 1124 1125
	if (pud_huge(*pud)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
		goto out;
	}
	if (unlikely(pud_bad(*pud)))
		goto no_page_table;

L
Linus Torvalds 已提交
1126
	pmd = pmd_offset(pud, address);
1127
	if (pmd_none(*pmd))
1128 1129 1130 1131
		goto no_page_table;
	if (pmd_huge(*pmd)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
1132
		goto out;
1133
	}
1134 1135 1136
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

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

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

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

1166 1167 1168 1169 1170 1171 1172 1173 1174
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
	/* Fall through to ZERO_PAGE handling */
1175 1176 1177 1178 1179 1180
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
N
Nick Piggin 已提交
1181
		page = ZERO_PAGE(0);
1182 1183 1184 1185 1186
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1187 1188
}

1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201
/* Can we do the FOLL_ANON optimization? */
static inline int use_zero_page(struct vm_area_struct *vma)
{
	/*
	 * We don't want to optimize FOLL_ANON for make_pages_present()
	 * when it tries to page in a VM_LOCKED region. As to VM_SHARED,
	 * we want to get the page from the page tables to make sure
	 * that we serialize and update with any other user of that
	 * mapping.
	 */
	if (vma->vm_flags & (VM_LOCKED | VM_SHARED))
		return 0;
	/*
N
Nick Piggin 已提交
1202
	 * And if we have a fault routine, it's not an anonymous region.
1203
	 */
N
Nick Piggin 已提交
1204
	return !vma->vm_ops || !vma->vm_ops->fault;
1205 1206
}

N
Nick Piggin 已提交
1207 1208 1209 1210


int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		     unsigned long start, int len, int flags,
L
Linus Torvalds 已提交
1211 1212 1213
		struct page **pages, struct vm_area_struct **vmas)
{
	int i;
N
Nick Piggin 已提交
1214 1215 1216 1217
	unsigned int vm_flags = 0;
	int write = !!(flags & GUP_FLAGS_WRITE);
	int force = !!(flags & GUP_FLAGS_FORCE);
	int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
1218
	int ignore_sigkill = !!(flags & GUP_FLAGS_IGNORE_SIGKILL);
L
Linus Torvalds 已提交
1219

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

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

		vma = find_extend_vma(mm, start);
		if (!vma && in_gate_area(tsk, start)) {
			unsigned long pg = start & PAGE_MASK;
			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
N
Nick Piggin 已提交
1242 1243 1244

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

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

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

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

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

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

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

1310
			cond_resched();
1311
			while (!(page = follow_page(vma, start, foll_flags))) {
1312
				int ret;
N
Nick Piggin 已提交
1313
				ret = handle_mm_fault(mm, vma, start,
1314
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
					else if (ret & VM_FAULT_SIGBUS)
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1327
				/*
N
Nick Piggin 已提交
1328 1329 1330 1331
				 * The VM_FAULT_WRITE bit tells us that
				 * do_wp_page has broken COW when necessary,
				 * even if maybe_mkwrite decided not to set
				 * pte_write. We can thus safely do subsequent
1332 1333 1334 1335 1336 1337
				 * page lookups as if they were reads. But only
				 * do so when looping for pte_write is futile:
				 * in some cases userspace may also be wanting
				 * to write to the gotten user page, which a
				 * read fault here might prevent (a readonly
				 * page might get reCOWed by userspace write).
1338
				 */
1339 1340
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1341
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1342

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

1350
				flush_anon_page(vma, page, start);
1351
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1352 1353 1354 1355 1356 1357
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1358 1359
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1360 1361
	return i;
}
N
Nick Piggin 已提交
1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378

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

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

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

L
Linus Torvalds 已提交
1379 1380
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1381 1382
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1383 1384 1385 1386
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1387
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1388 1389 1390 1391 1392 1393
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1394 1395 1396 1397 1398 1399 1400
/*
 * 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
1401 1402
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1403
{
N
Nick Piggin 已提交
1404
	struct mm_struct *mm = vma->vm_mm;
1405
	int retval;
1406
	pte_t *pte;
1407 1408
	spinlock_t *ptl;

1409
	retval = -EINVAL;
1410
	if (PageAnon(page))
1411
		goto out;
1412 1413
	retval = -ENOMEM;
	flush_dcache_page(page);
1414
	pte = get_locked_pte(mm, addr, &ptl);
1415
	if (!pte)
1416
		goto out;
1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
	inc_mm_counter(mm, file_rss);
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1428 1429
	pte_unmap_unlock(pte, ptl);
	return retval;
1430 1431 1432 1433 1434 1435
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1436 1437 1438 1439 1440 1441
/**
 * 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
 *
1442 1443 1444 1445 1446 1447
 * 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
1448
 * (see split_page()).
1449 1450 1451 1452 1453 1454 1455 1456 1457
 *
 * 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
1458 1459
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1460 1461 1462 1463 1464
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1465
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1466
	return insert_page(vma, addr, page, vma->vm_page_prot);
1467
}
1468
EXPORT_SYMBOL(vm_insert_page);
1469

N
Nick Piggin 已提交
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn, pgprot_t prot)
{
	struct mm_struct *mm = vma->vm_mm;
	int retval;
	pte_t *pte, entry;
	spinlock_t *ptl;

	retval = -ENOMEM;
	pte = get_locked_pte(mm, addr, &ptl);
	if (!pte)
		goto out;
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	entry = pte_mkspecial(pfn_pte(pfn, prot));
	set_pte_at(mm, addr, pte, entry);
	update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */

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

N
Nick Piggin 已提交
1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508
/**
 * 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
1509 1510 1511 1512 1513
 *
 * 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
1514 1515
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1516
			unsigned long pfn)
N
Nick Piggin 已提交
1517
{
1518
	int ret;
1519
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1520 1521 1522 1523 1524 1525
	/*
	 * 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
1526 1527 1528 1529 1530
	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
1531

N
Nick Piggin 已提交
1532 1533
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1534
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1535 1536
		return -EINVAL;

1537
	ret = insert_pfn(vma, addr, pfn, pgprot);
1538 1539 1540 1541 1542

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

	return ret;
N
Nick Piggin 已提交
1543 1544
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1545

N
Nick Piggin 已提交
1546 1547 1548 1549
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
1550

N
Nick Piggin 已提交
1551 1552
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1553

N
Nick Piggin 已提交
1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566
	/*
	 * If we don't have pte special, then we have to use the pfn_valid()
	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
	 * refcount the page if pfn_valid is true (hence insert_page rather
	 * than insert_pfn).
	 */
	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
		struct page *page;

		page = pfn_to_page(pfn);
		return insert_page(vma, addr, page, vma->vm_page_prot);
	}
	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
N
Nick Piggin 已提交
1567
}
N
Nick Piggin 已提交
1568
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1569

L
Linus Torvalds 已提交
1570 1571 1572 1573 1574 1575 1576 1577 1578 1579
/*
 * 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
1580
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1581

H
Hugh Dickins 已提交
1582
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1583 1584
	if (!pte)
		return -ENOMEM;
1585
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1586 1587
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1588
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1589 1590
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1591
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1592
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 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
	return 0;
}

static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pmd_t *pmd;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		if (remap_pte_range(mm, pmd, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pmd++, addr = next, addr != end);
	return 0;
}

static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pud_t *pud;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		if (remap_pmd_range(mm, pud, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pud++, addr = next, addr != end);
	return 0;
}

1636 1637 1638 1639 1640 1641 1642 1643 1644 1645
/**
 * 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
1646 1647 1648 1649 1650
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;
1651
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1652 1653 1654 1655 1656 1657 1658 1659
	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
1660 1661 1662 1663 1664
	 *   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.
1665 1666 1667
	 *   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
1668 1669 1670 1671
	 *
	 * 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
1672
	 */
1673
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
1674
		vma->vm_pgoff = pfn;
1675
		vma->vm_flags |= VM_PFN_AT_MMAP;
1676
	} else if (is_cow_mapping(vma->vm_flags))
1677
		return -EINVAL;
L
Linus Torvalds 已提交
1678

1679
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1680

1681
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1682 1683 1684 1685 1686 1687
	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);
1688
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
1689
		return -EINVAL;
1690
	}
1691

L
Linus Torvalds 已提交
1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702
	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);
1703 1704 1705 1706

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

L
Linus Torvalds 已提交
1707 1708 1709 1710
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1711 1712 1713 1714 1715 1716
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;
1717
	pgtable_t token;
1718
	spinlock_t *uninitialized_var(ptl);
1719 1720 1721 1722 1723 1724 1725 1726 1727

	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));

1728 1729
	arch_enter_lazy_mmu_mode();

1730
	token = pmd_pgtable(*pmd);
1731 1732

	do {
1733
		err = fn(pte, token, addr, data);
1734 1735 1736 1737
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

1738 1739
	arch_leave_lazy_mmu_mode();

1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752
	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
1753 1754
	BUG_ON(pud_huge(*pud));

1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);
	return err;
}

static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pud_t *pud;
	unsigned long next;
	int err;

	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
		if (err)
			break;
	} while (pud++, addr = next, addr != end);
	return err;
}

/*
 * Scan a region of virtual memory, filling in page tables as necessary
 * and calling a provided function on each leaf page table.
 */
int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
			unsigned long size, pte_fn_t fn, void *data)
{
	pgd_t *pgd;
	unsigned long next;
A
Andrea Arcangeli 已提交
1796
	unsigned long start = addr, end = addr + size;
1797 1798 1799
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1800
	mmu_notifier_invalidate_range_start(mm, start, end);
1801 1802 1803 1804 1805 1806 1807
	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1808
	mmu_notifier_invalidate_range_end(mm, start, end);
1809 1810 1811 1812
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1813 1814 1815 1816 1817 1818 1819 1820 1821
/*
 * handle_pte_fault chooses page fault handler according to an entry
 * which was read non-atomically.  Before making any commitment, on
 * those architectures or configurations (e.g. i386 with PAE) which
 * might give a mix of unmatched parts, do_swap_page and do_file_page
 * must check under lock before unmapping the pte and proceeding
 * (but do_wp_page is only called after already making such a check;
 * and do_anonymous_page and do_no_page can safely check later on).
 */
H
Hugh Dickins 已提交
1822
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1823 1824 1825 1826 1827
				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
1828 1829
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1830
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1831
		spin_unlock(ptl);
1832 1833 1834 1835 1836 1837
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850
/*
 * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
 * servicing faults for write access.  In the normal case, do always want
 * pte_mkwrite.  But get_user_pages can cause write faults for mappings
 * that do not have writing enabled, when used by access_process_vm.
 */
static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
{
	if (likely(vma->vm_flags & VM_WRITE))
		pte = pte_mkwrite(pte);
	return pte;
}

1851
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1852 1853 1854 1855 1856 1857 1858 1859 1860
{
	/*
	 * If the source page was a PFN mapping, we don't have
	 * a "struct page" for it. We do a best-effort copy by
	 * just copying from the original user address. If that
	 * fails, we just zero-fill it. Live with it.
	 */
	if (unlikely(!src)) {
		void *kaddr = kmap_atomic(dst, KM_USER0);
L
Linus Torvalds 已提交
1861 1862 1863 1864 1865 1866 1867 1868 1869
		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))
1870 1871
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1872
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1873 1874
	} else
		copy_user_highpage(dst, src, va, vma);
1875 1876
}

L
Linus Torvalds 已提交
1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890
/*
 * 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.
 *
1891 1892 1893
 * 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
1894
 */
1895 1896
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1897
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1898
{
1899
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1900
	pte_t entry;
N
Nick Piggin 已提交
1901
	int reuse = 0, ret = 0;
1902
	int page_mkwrite = 0;
1903
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1904

1905
	old_page = vm_normal_page(vma, address, orig_pte);
1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916
	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;
1917
		goto gotten;
1918
	}
L
Linus Torvalds 已提交
1919

1920
	/*
P
Peter Zijlstra 已提交
1921 1922
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1923
	 */
P
Peter Zijlstra 已提交
1924
	if (PageAnon(old_page)) {
1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936
		if (!trylock_page(old_page)) {
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);
			lock_page(old_page);
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
				goto unlock;
			}
			page_cache_release(old_page);
P
Peter Zijlstra 已提交
1937
		}
1938
		reuse = reuse_swap_page(old_page);
1939
		unlock_page(old_page);
P
Peter Zijlstra 已提交
1940
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1941
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1942 1943 1944 1945 1946
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
			/*
			 * Notify the address space that the page is about to
			 * become writable so that it can prohibit this or wait
			 * for the page to get into an appropriate state.
			 *
			 * We do this without the lock held, so that it can
			 * sleep if it needs to.
			 */
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);

			if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
				goto unwritable_page;

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
1970
			page_cache_release(old_page);
1971 1972
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1973 1974

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1975
		}
1976 1977
		dirty_page = old_page;
		get_page(dirty_page);
1978 1979 1980 1981
		reuse = 1;
	}

	if (reuse) {
1982
reuse:
1983 1984 1985
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1986
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1987
			update_mmu_cache(vma, address, entry);
1988 1989
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1990 1991 1992 1993 1994
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1995
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1996
gotten:
1997
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1998 1999

	if (unlikely(anon_vma_prepare(vma)))
2000
		goto oom;
N
Nick Piggin 已提交
2001 2002 2003 2004
	VM_BUG_ON(old_page == ZERO_PAGE(0));
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
	if (!new_page)
		goto oom;
N
Nick Piggin 已提交
2005 2006 2007 2008
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
2009
	if ((vma->vm_flags & VM_LOCKED) && old_page) {
N
Nick Piggin 已提交
2010 2011 2012 2013
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
N
Nick Piggin 已提交
2014
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
2015
	__SetPageUptodate(new_page);
2016

K
KAMEZAWA Hiroyuki 已提交
2017
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2018 2019
		goto oom_free_new;

L
Linus Torvalds 已提交
2020 2021 2022
	/*
	 * Re-check the pte - we dropped the lock
	 */
2023
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2024
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2025 2026 2027 2028 2029 2030
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
2031
			inc_mm_counter(mm, anon_rss);
2032
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2033 2034
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2035 2036 2037 2038 2039 2040
		/*
		 * Clear the pte entry and flush it first, before updating the
		 * pte with the new entry. This will avoid a race condition
		 * seen in the presence of one thread doing SMC and another
		 * thread doing COW.
		 */
A
Andrea Arcangeli 已提交
2041
		ptep_clear_flush_notify(vma, address, page_table);
N
Nick Piggin 已提交
2042
		page_add_new_anon_rmap(new_page, vma, address);
2043 2044
		set_pte_at(mm, address, page_table, entry);
		update_mmu_cache(vma, address, entry);
N
Nick Piggin 已提交
2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067
		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.
			 */
2068
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2069 2070
		}

L
Linus Torvalds 已提交
2071 2072
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2073
		ret |= VM_FAULT_WRITE;
2074 2075 2076
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2077 2078 2079 2080
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
2081
unlock:
2082
	pte_unmap_unlock(page_table, ptl);
2083
	if (dirty_page) {
2084 2085 2086
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2087 2088 2089 2090 2091 2092 2093 2094 2095
		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
		 * do_no_page is protected similarly.
		 */
		wait_on_page_locked(dirty_page);
2096
		set_page_dirty_balance(dirty_page, page_mkwrite);
2097 2098
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
2099
	return ret;
2100
oom_free_new:
2101
	page_cache_release(new_page);
2102
oom:
H
Hugh Dickins 已提交
2103 2104
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
2105
	return VM_FAULT_OOM;
2106 2107 2108 2109

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136
}

/*
 * Helper functions for unmap_mapping_range().
 *
 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
 *
 * We have to restart searching the prio_tree whenever we drop the lock,
 * since the iterator is only valid while the lock is held, and anyway
 * a later vma might be split and reinserted earlier while lock dropped.
 *
 * The list of nonlinear vmas could be handled more efficiently, using
 * a placeholder, but handle it in the same way until a need is shown.
 * It is important to search the prio_tree before nonlinear list: a vma
 * may become nonlinear and be shifted from prio_tree to nonlinear list
 * while the lock is dropped; but never shifted from list to prio_tree.
 *
 * In order to make forward progress despite restarting the search,
 * vm_truncate_count is used to mark a vma as now dealt with, so we can
 * quickly skip it next time around.  Since the prio_tree search only
 * shows us those vmas affected by unmapping the range in question, we
 * can't efficiently keep all vmas in step with mapping->truncate_count:
 * so instead reset them all whenever it wraps back to 0 (then go to 1).
 * mapping->truncate_count and vma->vm_truncate_count are protected by
 * i_mmap_lock.
 *
 * In order to make forward progress despite repeatedly restarting some
2137
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163
 * and restart from that address when we reach that vma again.  It might
 * have been split or merged, shrunk or extended, but never shifted: so
 * restart_addr remains valid so long as it remains in the vma's range.
 * unmap_mapping_range forces truncate_count to leap over page-aligned
 * values so we can save vma's restart_addr in its truncate_count field.
 */
#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))

static void reset_vma_truncate_counts(struct address_space *mapping)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;

	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
		vma->vm_truncate_count = 0;
	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
		vma->vm_truncate_count = 0;
}

static int unmap_mapping_range_vma(struct vm_area_struct *vma,
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
	unsigned long restart_addr;
	int need_break;

2164 2165
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2166
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2167 2168
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2169 2170
	 */

L
Linus Torvalds 已提交
2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181
again:
	restart_addr = vma->vm_truncate_count;
	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
		start_addr = restart_addr;
		if (start_addr >= end_addr) {
			/* Top of vma has been split off since last time */
			vma->vm_truncate_count = details->truncate_count;
			return 0;
		}
	}

2182 2183
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2184
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2185

2186
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2187 2188 2189 2190 2191 2192
		/* We have now completed this vma: mark it so */
		vma->vm_truncate_count = details->truncate_count;
		if (!need_break)
			return 0;
	} else {
		/* Note restart_addr in vma's truncate_count field */
2193
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259
		if (!need_break)
			goto again;
	}

	spin_unlock(details->i_mmap_lock);
	cond_resched();
	spin_lock(details->i_mmap_lock);
	return -EINTR;
}

static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;
	pgoff_t vba, vea, zba, zea;

restart:
	vma_prio_tree_foreach(vma, &iter, root,
			details->first_index, details->last_index) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;

		vba = vma->vm_pgoff;
		vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
		/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
		zba = details->first_index;
		if (zba < vba)
			zba = vba;
		zea = details->last_index;
		if (zea > vea)
			zea = vea;

		if (unmap_mapping_range_vma(vma,
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
				details) < 0)
			goto restart;
	}
}

static inline void unmap_mapping_range_list(struct list_head *head,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;

	/*
	 * In nonlinear VMAs there is no correspondence between virtual address
	 * offset and file offset.  So we must perform an exhaustive search
	 * across *all* the pages in each nonlinear VMA, not just the pages
	 * whose virtual address lies outside the file truncation point.
	 */
restart:
	list_for_each_entry(vma, head, shared.vm_set.list) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;
		details->nonlinear_vma = vma;
		if (unmap_mapping_range_vma(vma, vma->vm_start,
					vma->vm_end, details) < 0)
			goto restart;
	}
}

/**
2260
 * 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
2261
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
 * boundary.  Note that this is different from vmtruncate(), which
 * must keep the partial page.  In contrast, we must get rid of
 * partial pages.
 * @holelen: size of prospective hole in bytes.  This will be rounded
 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
 * end of the file.
 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
 * but 0 when invalidating pagecache, don't throw away private data.
 */
void unmap_mapping_range(struct address_space *mapping,
		loff_t const holebegin, loff_t const holelen, int even_cows)
{
	struct zap_details details;
	pgoff_t hba = holebegin >> PAGE_SHIFT;
	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;

	/* Check for overflow. */
	if (sizeof(holelen) > sizeof(hlen)) {
		long long holeend =
			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
		if (holeend & ~(long long)ULONG_MAX)
			hlen = ULONG_MAX - hba + 1;
	}

	details.check_mapping = even_cows? NULL: mapping;
	details.nonlinear_vma = NULL;
	details.first_index = hba;
	details.last_index = hba + hlen - 1;
	if (details.last_index < details.first_index)
		details.last_index = ULONG_MAX;
	details.i_mmap_lock = &mapping->i_mmap_lock;

	spin_lock(&mapping->i_mmap_lock);

2298
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314
	mapping->truncate_count++;
	if (unlikely(is_restart_addr(mapping->truncate_count))) {
		if (mapping->truncate_count == 0)
			reset_vma_truncate_counts(mapping);
		mapping->truncate_count++;
	}
	details.truncate_count = mapping->truncate_count;

	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
	spin_unlock(&mapping->i_mmap_lock);
}
EXPORT_SYMBOL(unmap_mapping_range);

2315 2316 2317 2318
/**
 * vmtruncate - unmap mappings "freed" by truncate() syscall
 * @inode: inode of the file used
 * @offset: file offset to start truncating
L
Linus Torvalds 已提交
2319 2320 2321 2322 2323 2324 2325
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode * inode, loff_t offset)
{
C
Christoph Hellwig 已提交
2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336
	if (inode->i_size < offset) {
		unsigned long limit;

		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
		if (limit != RLIM_INFINITY && offset > limit)
			goto out_sig;
		if (offset > inode->i_sb->s_maxbytes)
			goto out_big;
		i_size_write(inode, offset);
	} else {
		struct address_space *mapping = inode->i_mapping;
L
Linus Torvalds 已提交
2337

C
Christoph Hellwig 已提交
2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359
		/*
		 * truncation of in-use swapfiles is disallowed - it would
		 * cause subsequent swapout to scribble on the now-freed
		 * blocks.
		 */
		if (IS_SWAPFILE(inode))
			return -ETXTBSY;
		i_size_write(inode, offset);

		/*
		 * unmap_mapping_range is called twice, first simply for
		 * efficiency so that truncate_inode_pages does fewer
		 * single-page unmaps.  However after this first call, and
		 * before truncate_inode_pages finishes, it is possible for
		 * private pages to be COWed, which remain after
		 * truncate_inode_pages finishes, hence the second
		 * unmap_mapping_range call must be made for correctness.
		 */
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
		truncate_inode_pages(mapping, offset);
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	}
2360

A
Al Viro 已提交
2361
	if (inode->i_op->truncate)
L
Linus Torvalds 已提交
2362 2363
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2364

L
Linus Torvalds 已提交
2365 2366 2367 2368 2369 2370 2371
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2372 2373 2374 2375 2376 2377 2378 2379 2380
int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
{
	struct address_space *mapping = inode->i_mapping;

	/*
	 * If the underlying filesystem is not going to provide
	 * a way to truncate a range of blocks (punch a hole) -
	 * we should return failure right now.
	 */
A
Al Viro 已提交
2381
	if (!inode->i_op->truncate_range)
2382 2383
		return -ENOSYS;

2384
	mutex_lock(&inode->i_mutex);
2385 2386 2387
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2388
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2389 2390
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2391
	mutex_unlock(&inode->i_mutex);
2392 2393 2394 2395

	return 0;
}

L
Linus Torvalds 已提交
2396
/*
2397 2398 2399
 * 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
2400
 */
2401 2402 2403
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2404
{
2405
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2406
	struct page *page;
2407
	swp_entry_t entry;
L
Linus Torvalds 已提交
2408
	pte_t pte;
2409
	struct mem_cgroup *ptr = NULL;
N
Nick Piggin 已提交
2410
	int ret = 0;
L
Linus Torvalds 已提交
2411

H
Hugh Dickins 已提交
2412
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2413
		goto out;
2414 2415

	entry = pte_to_swp_entry(orig_pte);
2416 2417 2418 2419
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2420
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2421 2422
	page = lookup_swap_cache(entry);
	if (!page) {
2423
		grab_swap_token(); /* Contend for token _before_ read-in */
2424 2425
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2426 2427
		if (!page) {
			/*
2428 2429
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2430
			 */
2431
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2432 2433
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2434
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2435
			goto unlock;
L
Linus Torvalds 已提交
2436 2437 2438 2439
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2440
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2441 2442
	}

2443 2444 2445
	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

K
KAMEZAWA Hiroyuki 已提交
2446
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2447
		ret = VM_FAULT_OOM;
2448
		unlock_page(page);
2449 2450 2451
		goto out;
	}

L
Linus Torvalds 已提交
2452
	/*
2453
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2454
	 */
2455
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2456
	if (unlikely(!pte_same(*page_table, orig_pte)))
2457 2458 2459 2460 2461
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2462 2463
	}

2464 2465 2466 2467 2468 2469 2470 2471
	/*
	 * 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.
2472 2473 2474 2475
	 * 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().
2476
	 */
L
Linus Torvalds 已提交
2477

2478
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2479
	pte = mk_pte(page, vma->vm_page_prot);
2480
	if (write_access && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2481 2482 2483 2484 2485 2486
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
		write_access = 0;
	}
	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
	page_add_anon_rmap(page, vma, address);
2487 2488
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
2489

2490
	swap_free(entry);
N
Nick Piggin 已提交
2491
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2492
		try_to_free_swap(page);
2493 2494
	unlock_page(page);

L
Linus Torvalds 已提交
2495
	if (write_access) {
2496 2497 2498
		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
2499 2500 2501 2502 2503
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2504
unlock:
2505
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2506 2507
out:
	return ret;
2508
out_nomap:
2509
	mem_cgroup_cancel_charge_swapin(ptr);
2510
	pte_unmap_unlock(page_table, ptl);
2511 2512
	unlock_page(page);
	page_cache_release(page);
2513
	return ret;
L
Linus Torvalds 已提交
2514 2515 2516
}

/*
2517 2518 2519
 * 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
2520
 */
2521 2522 2523
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access)
L
Linus Torvalds 已提交
2524
{
2525 2526
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2527 2528
	pte_t entry;

N
Nick Piggin 已提交
2529 2530
	/* Allocate our own private page. */
	pte_unmap(page_table);
2531

N
Nick Piggin 已提交
2532 2533 2534 2535 2536
	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
2537
	__SetPageUptodate(page);
2538

K
KAMEZAWA Hiroyuki 已提交
2539
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2540 2541
		goto oom_free_page;

N
Nick Piggin 已提交
2542 2543
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2544

N
Nick Piggin 已提交
2545 2546 2547 2548 2549
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!pte_none(*page_table))
		goto release;
	inc_mm_counter(mm, anon_rss);
	page_add_new_anon_rmap(page, vma, address);
2550
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2551 2552

	/* No need to invalidate - it was non-present before */
2553 2554
	update_mmu_cache(vma, address, entry);
unlock:
2555
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2556
	return 0;
2557
release:
2558
	mem_cgroup_uncharge_page(page);
2559 2560
	page_cache_release(page);
	goto unlock;
2561
oom_free_page:
2562
	page_cache_release(page);
2563
oom:
L
Linus Torvalds 已提交
2564 2565 2566 2567
	return VM_FAULT_OOM;
}

/*
2568
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2569
 * tries to share with existing pages, but makes a separate copy if
2570 2571
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2572 2573 2574 2575
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2576
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2577
 * but allow concurrent faults), and pte neither mapped nor locked.
2578
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2579
 */
2580
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2581
		unsigned long address, pmd_t *pmd,
2582
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2583
{
2584
	pte_t *page_table;
2585
	spinlock_t *ptl;
N
Nick Piggin 已提交
2586
	struct page *page;
L
Linus Torvalds 已提交
2587 2588
	pte_t entry;
	int anon = 0;
2589
	int charged = 0;
2590
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2591 2592
	struct vm_fault vmf;
	int ret;
2593
	int page_mkwrite = 0;
2594

N
Nick Piggin 已提交
2595 2596 2597 2598
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2599

N
Nick Piggin 已提交
2600 2601 2602
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2603

2604
	/*
N
Nick Piggin 已提交
2605
	 * For consistency in subsequent calls, make the faulted page always
2606 2607
	 * locked.
	 */
N
Nick Piggin 已提交
2608
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2609
		lock_page(vmf.page);
2610
	else
N
Nick Piggin 已提交
2611
		VM_BUG_ON(!PageLocked(vmf.page));
2612

L
Linus Torvalds 已提交
2613 2614 2615
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2616
	page = vmf.page;
2617
	if (flags & FAULT_FLAG_WRITE) {
2618
		if (!(vma->vm_flags & VM_SHARED)) {
2619
			anon = 1;
2620
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2621
				ret = VM_FAULT_OOM;
2622
				goto out;
2623
			}
N
Nick Piggin 已提交
2624 2625
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2626
			if (!page) {
N
Nick Piggin 已提交
2627
				ret = VM_FAULT_OOM;
2628
				goto out;
2629
			}
K
KAMEZAWA Hiroyuki 已提交
2630
			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2631 2632 2633 2634 2635
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2636 2637 2638 2639 2640 2641
			/*
			 * Don't let another task, with possibly unlocked vma,
			 * keep the mlocked page.
			 */
			if (vma->vm_flags & VM_LOCKED)
				clear_page_mlock(vmf.page);
N
Nick Piggin 已提交
2642
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2643
			__SetPageUptodate(page);
2644
		} else {
2645 2646
			/*
			 * If the page will be shareable, see if the backing
2647
			 * address space wants to know that the page is about
2648 2649
			 * to become writable
			 */
2650 2651 2652
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2653 2654
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2655 2656 2657
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2658 2659 2660 2661 2662 2663 2664 2665
				/*
				 * XXX: this is not quite right (racy vs
				 * invalidate) to unlock and relock the page
				 * like this, however a better fix requires
				 * reworking page_mkwrite locking API, which
				 * is better done later.
				 */
				if (!page->mapping) {
N
Nick Piggin 已提交
2666
					ret = 0;
N
Nick Piggin 已提交
2667 2668 2669
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2670
				page_mkwrite = 1;
2671 2672
			}
		}
2673

L
Linus Torvalds 已提交
2674 2675
	}

2676
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
	 * Note that if write_access is true, we either now have
	 * an exclusive copy of the page, or this is a shared mapping,
	 * so we can make it writable and dirty to avoid having to
	 * handle that later.
	 */
	/* Only go through if we didn't race with anybody else... */
2689
	if (likely(pte_same(*page_table, orig_pte))) {
2690 2691
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2692
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2693 2694
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2695 2696
			inc_mm_counter(mm, anon_rss);
			page_add_new_anon_rmap(page, vma, address);
2697
		} else {
2698
			inc_mm_counter(mm, file_rss);
2699
			page_add_file_rmap(page);
2700
			if (flags & FAULT_FLAG_WRITE) {
2701
				dirty_page = page;
2702 2703
				get_page(dirty_page);
			}
2704
		}
2705
		set_pte_at(mm, address, page_table, entry);
2706 2707 2708

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2709
	} else {
2710 2711
		if (charged)
			mem_cgroup_uncharge_page(page);
2712 2713 2714
		if (anon)
			page_cache_release(page);
		else
2715
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2716 2717
	}

2718
	pte_unmap_unlock(page_table, ptl);
2719 2720

out:
N
Nick Piggin 已提交
2721
	unlock_page(vmf.page);
2722
out_unlocked:
2723
	if (anon)
N
Nick Piggin 已提交
2724
		page_cache_release(vmf.page);
2725
	else if (dirty_page) {
2726 2727 2728
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2729
		set_page_dirty_balance(dirty_page, page_mkwrite);
2730 2731
		put_page(dirty_page);
	}
2732

N
Nick Piggin 已提交
2733
	return ret;
2734
}
2735

2736 2737 2738 2739 2740
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2741
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2742 2743
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2744 2745
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2746 2747
}

L
Linus Torvalds 已提交
2748 2749 2750 2751
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2752 2753 2754 2755
 *
 * 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
2756
 */
N
Nick Piggin 已提交
2757
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2758 2759
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2760
{
N
Nick Piggin 已提交
2761 2762
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2763
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2764

H
Hugh Dickins 已提交
2765
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2766
		return 0;
L
Linus Torvalds 已提交
2767

2768
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2769 2770 2771
		/*
		 * Page table corrupted: show pte and kill process.
		 */
2772
		print_bad_pte(vma, address, orig_pte, NULL);
2773 2774 2775 2776
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2777
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788
}

/*
 * 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
2789 2790 2791
 * 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
2792 2793
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2794 2795
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2796 2797
{
	pte_t entry;
2798
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2799

2800
	entry = *pte;
L
Linus Torvalds 已提交
2801
	if (!pte_present(entry)) {
2802
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2803
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2804
				if (likely(vma->vm_ops->fault))
2805 2806
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2807 2808 2809
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2810
		}
L
Linus Torvalds 已提交
2811
		if (pte_file(entry))
N
Nick Piggin 已提交
2812
			return do_nonlinear_fault(mm, vma, address,
2813 2814 2815
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2816 2817
	}

H
Hugh Dickins 已提交
2818
	ptl = pte_lockptr(mm, pmd);
2819 2820 2821
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2822 2823
	if (write_access) {
		if (!pte_write(entry))
2824 2825
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2826 2827 2828
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2829
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840
		update_mmu_cache(vma, address, entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2841 2842
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2843
	return 0;
L
Linus Torvalds 已提交
2844 2845 2846 2847 2848
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2849
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2850 2851 2852 2853 2854 2855 2856 2857 2858
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2859
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2860

2861 2862
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2863 2864 2865 2866

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2867
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2868 2869
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2870
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2871 2872
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2873
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2874

H
Hugh Dickins 已提交
2875
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2876 2877 2878 2879 2880
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2881
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2882
 */
2883
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2884
{
H
Hugh Dickins 已提交
2885 2886
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2887
		return -ENOMEM;
L
Linus Torvalds 已提交
2888

2889 2890
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2891
	spin_lock(&mm->page_table_lock);
2892
	if (pgd_present(*pgd))		/* Another has populated it */
2893
		pud_free(mm, new);
2894 2895
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2896
	spin_unlock(&mm->page_table_lock);
2897
	return 0;
L
Linus Torvalds 已提交
2898 2899 2900 2901 2902 2903
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2904
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2905
 */
2906
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2907
{
H
Hugh Dickins 已提交
2908 2909
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2910
		return -ENOMEM;
L
Linus Torvalds 已提交
2911

2912 2913
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2914
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2915
#ifndef __ARCH_HAS_4LEVEL_HACK
2916
	if (pud_present(*pud))		/* Another has populated it */
2917
		pmd_free(mm, new);
2918 2919
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2920
#else
2921
	if (pgd_present(*pud))		/* Another has populated it */
2922
		pmd_free(mm, new);
2923 2924
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2925
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2926
	spin_unlock(&mm->page_table_lock);
2927
	return 0;
2928
}
L
Linus Torvalds 已提交
2929 2930 2931 2932 2933 2934 2935 2936 2937
#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
2938
		return -ENOMEM;
L
Linus Torvalds 已提交
2939
	write = (vma->vm_flags & VM_WRITE) != 0;
2940 2941
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2942
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2943 2944
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
2945
	if (ret < 0)
L
Linus Torvalds 已提交
2946
		return ret;
2947
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
2948 2949 2950 2951 2952
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2953
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2954 2955 2956 2957 2958 2959

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
2960 2961
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2962 2963 2964 2965 2966 2967 2968
	/*
	 * Make sure the vDSO gets into every core dump.
	 * Dumping its contents makes post-mortem fully interpretable later
	 * without matching up the same kernel and hardware config to see
	 * what PC values meant.
	 */
	gate_vma.vm_flags |= VM_ALWAYSDUMP;
L
Linus Torvalds 已提交
2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992
	return 0;
}
__initcall(gate_vma_init);
#endif

struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
#ifdef AT_SYSINFO_EHDR
	return &gate_vma;
#else
	return NULL;
#endif
}

int in_gate_area_no_task(unsigned long addr)
{
#ifdef AT_SYSINFO_EHDR
	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
		return 1;
#endif
	return 0;
}

#endif	/* __HAVE_ARCH_GATE_AREA */
2993

2994
#ifdef CONFIG_HAVE_IOREMAP_PROT
2995 2996 2997
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
2998 2999 3000 3001 3002 3003 3004 3005
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
	spinlock_t *ptl;
	resource_size_t phys_addr = 0;
	struct mm_struct *mm = vma->vm_mm;
3006
	int ret = -EINVAL;
3007

3008 3009
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3010 3011 3012

	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3013
		goto out;
3014 3015 3016

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3017
		goto out;
3018 3019 3020

	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3021
		goto out;
3022 3023 3024

	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
	if (pmd_huge(*pmd))
3025
		goto out;
3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039

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

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

	*prot = pgprot_val(pte_pgprot(pte));
3040 3041
	*phys = phys_addr;
	ret = 0;
3042 3043 3044 3045

unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3046
	return ret;
3047 3048 3049 3050 3051 3052 3053
}

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
3054
	void __iomem *maddr;
3055 3056
	int offset = addr & (PAGE_SIZE-1);

3057
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070
		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

3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086
/*
 * Access another process' address space.
 * Source/target buffer must be kernel space,
 * Do not walk the page table directly, use get_user_pages
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	void *old_buf = buf;

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

	down_read(&mm->mmap_sem);
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Simon Arlott 已提交
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	/* ignore errors, just check how much was successfully transferred */
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	while (len) {
		int bytes, ret, offset;
		void *maddr;
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		struct page *page = NULL;
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		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
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		if (ret <= 0) {
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
#ifdef CONFIG_HAVE_IOREMAP_PROT
			vma = find_vma(mm, addr);
			if (!vma)
				break;
			if (vma->vm_ops && vma->vm_ops->access)
				ret = vma->vm_ops->access(vma, addr, buf,
							  len, write);
			if (ret <= 0)
#endif
				break;
			bytes = ret;
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		} else {
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			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);
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		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
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/*
 * 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;

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	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

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	down_read(&mm->mmap_sem);
	vma = find_vma(mm, ip);
	if (vma && vma->vm_file) {
		struct file *f = vma->vm_file;
		char *buf = (char *)__get_free_page(GFP_KERNEL);
		if (buf) {
			char *p, *s;

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			p = d_path(&f->f_path, buf, PAGE_SIZE);
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			if (IS_ERR(p))
				p = "?";
			s = strrchr(p, '/');
			if (s)
				p = s+1;
			printk("%s%s[%lx+%lx]", prefix, p,
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
	up_read(&current->mm->mmap_sem);
}
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#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
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	/*
	 * 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;

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	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