memory.c 67.2 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>

#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>

#include <linux/swapops.h>
#include <linux/elf.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;
unsigned long vmalloc_earlyreserve;

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);
EXPORT_SYMBOL(vmalloc_earlyreserve);

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int randomize_va_space __read_mostly = 1;

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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	struct page *page = pmd_page(*pmd);
	pmd_clear(pmd);
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	pte_lock_deinit(page);
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	pte_free_tlb(tlb, page);
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	dec_zone_page_state(page, NR_PAGETABLE);
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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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	if (!(*tlb)->fullmm)
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		flush_tlb_pgtables((*tlb)->mm, start, end);
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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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	struct page *new = pte_alloc_one(mm, address);
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	if (!new)
		return -ENOMEM;

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	pte_lock_init(new);
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	spin_lock(&mm->page_table_lock);
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	if (pmd_present(*pmd)) {	/* Another has populated it */
		pte_lock_deinit(new);
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		pte_free(new);
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	} else {
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		mm->nr_ptes++;
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		inc_zone_page_state(new, NR_PAGETABLE);
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		pmd_populate(mm, pmd, new);
	}
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	spin_unlock(&mm->page_table_lock);
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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;

	spin_lock(&init_mm.page_table_lock);
	if (pmd_present(*pmd))		/* Another has populated it */
		pte_free_kernel(new);
	else
		pmd_populate_kernel(&init_mm, pmd, new);
	spin_unlock(&init_mm.page_table_lock);
	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.
 */
void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
{
	printk(KERN_ERR "Bad pte = %08llx, process = %s, "
			"vm_flags = %lx, vaddr = %lx\n",
		(long long)pte_val(pte),
		(vma->vm_mm == current->mm ? current->comm : "???"),
		vma->vm_flags, vaddr);
	dump_stack();
}

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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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 * This function gets the "struct page" associated with a pte.
 *
 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
 * will have each page table entry just pointing to a raw page frame
 * number, and as far as the VM layer is concerned, those do not have
 * pages associated with them - even if the PFN might point to memory
 * that otherwise is perfectly fine and has a "struct page".
 *
 * The way we recognize those mappings is through the rules set up
 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
 * and the vm_pgoff will point to the first PFN mapped: thus every
 * page that is a raw mapping will always honor the rule
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
 * and if that isn't true, the page has been COW'ed (in which case it
 * _does_ have a "struct page" associated with it even if it is in a
 * VM_PFNMAP range).
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 */
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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 (unlikely(vma->vm_flags & VM_PFNMAP)) {
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		unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
		if (pfn == vma->vm_pgoff + off)
			return NULL;
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		if (!is_cow_mapping(vma->vm_flags))
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			return NULL;
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	}

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	/*
	 * Add some anal sanity checks for now. Eventually,
	 * we should just do "return pfn_to_page(pfn)", but
	 * in the meantime we check that we get a valid pfn,
	 * and that the resulting page looks ok.
	 */
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	if (unlikely(!pfn_valid(pfn))) {
		print_bad_pte(vma, pte, addr);
		return NULL;
	}

	/*
	 * NOTE! We still have PageReserved() pages in the page 
	 * tables. 
	 *
	 * The PAGE_ZERO() pages and various VDSO mappings can
	 * cause them to exist.
	 */
	return pfn_to_page(pfn);
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}

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

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

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

			swap_duplicate(entry);
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			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
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				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
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				spin_unlock(&mmlist_lock);
			}
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			if (is_write_migration_entry(entry) &&
					is_cow_mapping(vm_flags)) {
				/*
				 * COW mappings require pages in both parent
				 * and child to be set to read.
				 */
				make_migration_entry_read(&entry);
				pte = swp_entry_to_pte(entry);
				set_pte_at(src_mm, addr, src_pte, pte);
			}
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		}
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		goto out_set_pte;
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	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
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	if (is_cow_mapping(vm_flags)) {
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		ptep_set_wrprotect(src_mm, addr, src_pte);
		pte = *src_pte;
	}

	/*
	 * 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);
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	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
		page_dup_rmap(page);
		rss[!!PageAnon(page)]++;
	}
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out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
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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;
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	spinlock_t *src_ptl, *dst_ptl;
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	int progress = 0;
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	int rss[2];
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again:
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	rss[1] = rss[0] = 0;
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	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
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	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
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	src_ptl = pte_lockptr(src_mm, src_pmd);
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	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
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	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
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		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
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			    need_lockbreak(src_ptl) ||
			    need_lockbreak(dst_ptl))
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				break;
		}
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		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
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		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
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		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

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	spin_unlock(src_ptl);
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	pte_unmap_nested(src_pte - 1);
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	add_mm_rss(dst_mm, rss[0], rss[1]);
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	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
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	if (addr != end)
		goto again;
	return 0;
}

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

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

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

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

int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		struct vm_area_struct *vma)
{
	pgd_t *src_pgd, *dst_pgd;
	unsigned long next;
	unsigned long addr = vma->vm_start;
	unsigned long end = vma->vm_end;

591 592 593 594 595 596
	/*
	 * 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.
	 */
597
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
598 599 600 601
		if (!vma->anon_vma)
			return 0;
	}

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

	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;
		if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
	return 0;
}

618
static unsigned long zap_pte_range(struct mmu_gather *tlb,
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				struct vm_area_struct *vma, pmd_t *pmd,
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				unsigned long addr, unsigned long end,
621
				long *zap_work, struct zap_details *details)
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{
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	struct mm_struct *mm = tlb->mm;
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	pte_t *pte;
625
	spinlock_t *ptl;
626 627
	int file_rss = 0;
	int anon_rss = 0;
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629
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
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	do {
		pte_t ptent = *pte;
632 633
		if (pte_none(ptent)) {
			(*zap_work)--;
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			continue;
635
		}
636 637 638

		(*zap_work) -= PAGE_SIZE;

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		if (pte_present(ptent)) {
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			struct page *page;
641

642
			page = vm_normal_page(vma, addr, ptent);
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			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;
			}
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			ptent = ptep_get_and_clear_full(mm, addr, pte,
662
							tlb->fullmm);
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			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)
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				set_pte_at(mm, addr, pte,
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					   pgoff_to_pte(page->index));
			if (PageAnon(page))
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				anon_rss--;
673 674 675 676 677
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
					mark_page_accessed(page);
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				file_rss--;
679
			}
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			page_remove_rmap(page);
			tlb_remove_page(tlb, page);
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
		if (!pte_file(ptent))
			free_swap_and_cache(pte_to_swp_entry(ptent));
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		pte_clear_full(mm, addr, pte, tlb->fullmm);
693
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
694

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	add_mm_rss(mm, file_rss, anon_rss);
696
	pte_unmap_unlock(pte - 1, ptl);
697 698

	return addr;
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}

701
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
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702
				struct vm_area_struct *vma, pud_t *pud,
L
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				unsigned long addr, unsigned long end,
704
				long *zap_work, struct zap_details *details)
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{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
712 713
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
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			continue;
715 716 717 718 719 720
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
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}

723
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
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				struct vm_area_struct *vma, pgd_t *pgd,
L
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				unsigned long addr, unsigned long end,
726
				long *zap_work, struct zap_details *details)
L
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{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
734 735
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
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			continue;
737 738 739 740 741 742
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
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}

745 746
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
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				unsigned long addr, unsigned long end,
748
				long *zap_work, struct zap_details *details)
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{
	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);
761 762
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
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			continue;
764 765 766 767
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
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	tlb_end_vma(tlb, vma);
769 770

	return addr;
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}

#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
 *
789
 * Returns the end address of the unmapping (restart addr if interrupted).
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 *
791
 * Unmap all pages in the vma list.
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 *
793 794
 * 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
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 * 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.
 */
806
unsigned long unmap_vmas(struct mmu_gather **tlbp,
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		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
811
	long zap_work = ZAP_BLOCK_SIZE;
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	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
814
	unsigned long start = start_addr;
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	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
816
	int fullmm = (*tlbp)->fullmm;
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	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;

		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

837
			if (unlikely(is_vm_hugetlb_page(vma))) {
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				unmap_hugepage_range(vma, start, end);
839 840 841 842 843 844 845 846 847 848
				zap_work -= (end - start) /
						(HPAGE_SIZE / PAGE_SIZE);
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

			if (zap_work > 0) {
				BUG_ON(start != end);
				break;
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			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
				(i_mmap_lock && need_lockbreak(i_mmap_lock))) {
				if (i_mmap_lock) {
856
					*tlbp = NULL;
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					goto out;
				}
				cond_resched();
			}

862
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
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			tlb_start_valid = 0;
864
			zap_work = ZAP_BLOCK_SIZE;
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		}
	}
out:
868
	return start;	/* which is now the end (or restart) address */
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}

/**
 * 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
 */
878
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
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		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);
888
	update_hiwater_rss(mm);
889 890 891
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
892
	return end;
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}

/*
 * Do a quick page-table lookup for a single page.
 */
898
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
899
			unsigned int flags)
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{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
905
	spinlock_t *ptl;
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	struct page *page;
907
	struct mm_struct *mm = vma->vm_mm;
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909 910 911 912 913
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
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915
	page = NULL;
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	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
918
		goto no_page_table;
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	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
922
		goto no_page_table;
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	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
926 927 928 929 930
		goto no_page_table;

	if (pmd_huge(*pmd)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
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		goto out;
932
	}
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934
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
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	if (!ptep)
		goto out;

	pte = *ptep;
939 940 941 942
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
943 944
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
945
		goto unlock;
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947 948 949 950 951 952 953 954 955 956
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
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out:
958
	return page;
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960 961 962 963 964 965 966 967 968 969 970 971
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) {
		page = ZERO_PAGE(address);
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
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}

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 i;
979
	unsigned int vm_flags;
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	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
985 986
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
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	i = 0;

	do {
990 991
		struct vm_area_struct *vma;
		unsigned int foll_flags;
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		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;
			if (write) /* user gate pages are read-only */
				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);
1011 1012
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
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			pte = pte_offset_map(pmd, pg);
1014 1015 1016 1017
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
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			if (pages) {
1019
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1020 1021 1022
				pages[i] = page;
				if (page)
					get_page(page);
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			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1033
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1034
				|| !(vm_flags & vma->vm_flags))
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			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
						&start, &len, i);
			continue;
		}
1042 1043 1044 1045 1046 1047 1048 1049

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
		if (!write && !(vma->vm_flags & VM_LOCKED) &&
		    (!vma->vm_ops || !vma->vm_ops->nopage))
			foll_flags |= FOLL_ANON;

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		do {
1051
			struct page *page;
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1053 1054
			if (write)
				foll_flags |= FOLL_WRITE;
1055

1056
			cond_resched();
1057
			while (!(page = follow_page(vma, start, foll_flags))) {
1058 1059 1060
				int ret;
				ret = __handle_mm_fault(mm, vma, start,
						foll_flags & FOLL_WRITE);
1061 1062 1063 1064 1065 1066 1067
				/*
				 * 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 page lookups as if they were reads.
				 */
				if (ret & VM_FAULT_WRITE)
1068
					foll_flags &= ~FOLL_WRITE;
1069 1070
				
				switch (ret & ~VM_FAULT_WRITE) {
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				case VM_FAULT_MINOR:
					tsk->min_flt++;
					break;
				case VM_FAULT_MAJOR:
					tsk->maj_flt++;
					break;
				case VM_FAULT_SIGBUS:
					return i ? i : -EFAULT;
				case VM_FAULT_OOM:
					return i ? i : -ENOMEM;
				default:
					BUG();
				}
			}
			if (pages) {
1086
				pages[i] = page;
1087 1088

				flush_anon_page(page, start);
1089
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1090 1091 1092 1093 1094 1095
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1096 1097
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1098 1099 1100 1101 1102 1103 1104 1105
	return i;
}
EXPORT_SYMBOL(get_user_pages);

static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pte_t *pte;
H
Hugh Dickins 已提交
1106
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1107

H
Hugh Dickins 已提交
1108
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1109 1110 1111
	if (!pte)
		return -ENOMEM;
	do {
N
Nick Piggin 已提交
1112 1113 1114 1115 1116
		struct page *page = ZERO_PAGE(addr);
		pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
		page_cache_get(page);
		page_add_file_rmap(page);
		inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
1117 1118 1119
		BUG_ON(!pte_none(*pte));
		set_pte_at(mm, addr, pte, zero_pte);
	} while (pte++, addr += PAGE_SIZE, addr != end);
H
Hugh Dickins 已提交
1120
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178
	return 0;
}

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

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

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

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

int zeromap_page_range(struct vm_area_struct *vma,
			unsigned long addr, unsigned long size, pgprot_t prot)
{
	pgd_t *pgd;
	unsigned long next;
	unsigned long end = addr + size;
	struct mm_struct *mm = vma->vm_mm;
	int err;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	flush_cache_range(vma, addr, end);
	do {
		next = pgd_addr_end(addr, end);
		err = zeromap_pud_range(mm, pgd, addr, next, prot);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
	return err;
}

1179
pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1180 1181 1182 1183
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1184
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1185 1186 1187 1188 1189 1190
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1191 1192 1193 1194 1195 1196 1197 1198 1199 1200
/*
 * 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.
 */
static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
{
	int retval;
1201
	pte_t *pte;
1202 1203 1204
	spinlock_t *ptl;  

	retval = -EINVAL;
1205
	if (PageAnon(page))
1206 1207 1208
		goto out;
	retval = -ENOMEM;
	flush_dcache_page(page);
1209
	pte = get_locked_pte(mm, addr, &ptl);
1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228
	if (!pte)
		goto out;
	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;
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1229 1230 1231 1232 1233 1234 1235
/*
 * 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
1236
 * (see split_page()).
1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251
 *
 * 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.
 */
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1252
	vma->vm_flags |= VM_INSERTPAGE;
1253 1254
	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
1255
EXPORT_SYMBOL(vm_insert_page);
1256

L
Linus Torvalds 已提交
1257 1258 1259 1260 1261 1262 1263 1264 1265 1266
/*
 * 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
1267
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1268

H
Hugh Dickins 已提交
1269
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1270 1271 1272 1273
	if (!pte)
		return -ENOMEM;
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1274
		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
L
Linus Torvalds 已提交
1275 1276
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
H
Hugh Dickins 已提交
1277
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326
	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;
}

/*  Note: this is only safe if the mm semaphore is held when called. */
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;
1327
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1328 1329 1330 1331 1332 1333 1334 1335
	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
1336 1337 1338 1339 1340
	 *   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.
1341 1342 1343
	 *   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
1344 1345 1346 1347
	 *
	 * 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
1348
	 */
1349
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1350
		if (addr != vma->vm_start || end != vma->vm_end)
1351
			return -EINVAL;
L
Linus Torvalds 已提交
1352 1353 1354
		vma->vm_pgoff = pfn;
	}

1355
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371

	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);
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1372 1373 1374 1375 1376 1377 1378 1379 1380
/*
 * 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
1381
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1382 1383 1384 1385 1386
				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
1387 1388
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1389
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1390
		spin_unlock(ptl);
1391 1392 1393 1394 1395 1396
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409
/*
 * 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;
}

1410 1411 1412 1413 1414 1415 1416 1417 1418 1419
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
{
	/*
	 * 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
1420 1421 1422 1423 1424 1425 1426 1427 1428
		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))
1429 1430 1431 1432 1433 1434 1435 1436
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
		return;
		
	}
	copy_user_highpage(dst, src, va);
}

L
Linus Torvalds 已提交
1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450
/*
 * 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.
 *
1451 1452 1453
 * 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
1454
 */
1455 1456
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1457
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1458
{
1459
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1460
	pte_t entry;
1461 1462
	int reuse = 0, ret = VM_FAULT_MINOR;
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1463

1464 1465 1466
	old_page = vm_normal_page(vma, address, orig_pte);
	if (!old_page)
		goto gotten;
L
Linus Torvalds 已提交
1467

1468 1469 1470 1471 1472 1473
	/*
	 * Only catch write-faults on shared writable pages, read-only
	 * shared pages can get COWed by get_user_pages(.write=1, .force=1).
	 */
	if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
					(VM_WRITE|VM_SHARED))) {
1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500
		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;

			page_cache_release(old_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);
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
L
Linus Torvalds 已提交
1501
		}
1502 1503
		dirty_page = old_page;
		get_page(dirty_page);
1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518
		reuse = 1;
	} else if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
		reuse = can_share_swap_page(old_page);
		unlock_page(old_page);
	}

	if (reuse) {
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		ptep_set_access_flags(vma, address, page_table, entry, 1);
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(entry);
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1519 1520 1521 1522 1523
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1524
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1525
gotten:
1526
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1527 1528

	if (unlikely(anon_vma_prepare(vma)))
1529
		goto oom;
1530
	if (old_page == ZERO_PAGE(address)) {
L
Linus Torvalds 已提交
1531 1532
		new_page = alloc_zeroed_user_highpage(vma, address);
		if (!new_page)
1533
			goto oom;
L
Linus Torvalds 已提交
1534 1535 1536
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
		if (!new_page)
1537
			goto oom;
1538
		cow_user_page(new_page, old_page, address);
L
Linus Torvalds 已提交
1539
	}
1540

L
Linus Torvalds 已提交
1541 1542 1543
	/*
	 * Re-check the pte - we dropped the lock
	 */
1544
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1545
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1546 1547 1548 1549 1550 1551 1552
		if (old_page) {
			page_remove_rmap(old_page);
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1553
			inc_mm_counter(mm, anon_rss);
1554
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1555 1556
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1557
		lazy_mmu_prot_update(entry);
1558 1559
		ptep_establish(vma, address, page_table, entry);
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1560
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1561
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1562 1563 1564

		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1565
		ret |= VM_FAULT_WRITE;
L
Linus Torvalds 已提交
1566
	}
H
Hugh Dickins 已提交
1567 1568 1569 1570
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1571
unlock:
1572
	pte_unmap_unlock(page_table, ptl);
1573 1574 1575 1576
	if (dirty_page) {
		set_page_dirty(dirty_page);
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1577
	return ret;
1578
oom:
H
Hugh Dickins 已提交
1579 1580
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1581
	return VM_FAULT_OOM;
1582 1583 1584 1585

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612
}

/*
 * 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
1613
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650
 * 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;

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;
		}
	}

1651 1652
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
L
Linus Torvalds 已提交
1653 1654 1655
	need_break = need_resched() ||
			need_lockbreak(details->i_mmap_lock);

1656
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1657 1658 1659 1660 1661 1662
		/* 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 */
1663
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732
		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;
	}
}

/**
 * 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
1733
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 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 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842
 * @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);

	/* serialize i_size write against truncate_count write */
	smp_wmb();
	/* Protect against page faults, and endless unmapping loops */
	mapping->truncate_count++;
	/*
	 * For archs where spin_lock has inclusive semantics like ia64
	 * this smp_mb() will prevent to read pagetable contents
	 * before the truncate_count increment is visible to
	 * other cpus.
	 */
	smp_mb();
	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);

/*
 * Handle all mappings that got truncated by a "truncate()"
 * system call.
 *
 * 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)
{
	struct address_space *mapping = inode->i_mapping;
	unsigned long limit;

	if (inode->i_size < offset)
		goto do_expand;
	/*
	 * truncation of in-use swapfiles is disallowed - it would cause
	 * subsequent swapout to scribble on the now-freed blocks.
	 */
	if (IS_SWAPFILE(inode))
		goto out_busy;
	i_size_write(inode, offset);
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	truncate_inode_pages(mapping, offset);
	goto out_truncate;

do_expand:
	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);

out_truncate:
	if (inode->i_op && inode->i_op->truncate)
		inode->i_op->truncate(inode);
	return 0;
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
out_busy:
	return -ETXTBSY;
}
EXPORT_SYMBOL(vmtruncate);

1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854
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.
	 */
	if (!inode->i_op || !inode->i_op->truncate_range)
		return -ENOSYS;

1855
	mutex_lock(&inode->i_mutex);
1856 1857 1858 1859 1860
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
1861
	mutex_unlock(&inode->i_mutex);
1862 1863 1864

	return 0;
}
1865
EXPORT_UNUSED_SYMBOL(vmtruncate_range);  /*  June 2006  */
1866

L
Linus Torvalds 已提交
1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923
/* 
 * Primitive swap readahead code. We simply read an aligned block of
 * (1 << page_cluster) entries in the swap area. This method is chosen
 * because it doesn't cost us any seek time.  We also make sure to queue
 * the 'original' request together with the readahead ones...  
 *
 * This has been extended to use the NUMA policies from the mm triggering
 * the readahead.
 *
 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
 */
void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
{
#ifdef CONFIG_NUMA
	struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
#endif
	int i, num;
	struct page *new_page;
	unsigned long offset;

	/*
	 * Get the number of handles we should do readahead io to.
	 */
	num = valid_swaphandles(entry, &offset);
	for (i = 0; i < num; offset++, i++) {
		/* Ok, do the async read-ahead now */
		new_page = read_swap_cache_async(swp_entry(swp_type(entry),
							   offset), vma, addr);
		if (!new_page)
			break;
		page_cache_release(new_page);
#ifdef CONFIG_NUMA
		/*
		 * Find the next applicable VMA for the NUMA policy.
		 */
		addr += PAGE_SIZE;
		if (addr == 0)
			vma = NULL;
		if (vma) {
			if (addr >= vma->vm_end) {
				vma = next_vma;
				next_vma = vma ? vma->vm_next : NULL;
			}
			if (vma && addr < vma->vm_start)
				vma = NULL;
		} else {
			if (next_vma && addr >= next_vma->vm_start) {
				vma = next_vma;
				next_vma = vma->vm_next;
			}
		}
#endif
	}
	lru_add_drain();	/* Push any new pages onto the LRU now */
}

/*
1924 1925 1926
 * 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
1927
 */
1928 1929 1930
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
1931
{
1932
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1933
	struct page *page;
1934
	swp_entry_t entry;
L
Linus Torvalds 已提交
1935 1936 1937
	pte_t pte;
	int ret = VM_FAULT_MINOR;

H
Hugh Dickins 已提交
1938
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1939
		goto out;
1940 1941

	entry = pte_to_swp_entry(orig_pte);
1942 1943 1944 1945
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
1946
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
1947 1948 1949 1950 1951 1952
	page = lookup_swap_cache(entry);
	if (!page) {
 		swapin_readahead(entry, address, vma);
 		page = read_swap_cache_async(entry, vma, address);
		if (!page) {
			/*
1953 1954
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
1955
			 */
1956
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1957 1958
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
1959
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
1960
			goto unlock;
L
Linus Torvalds 已提交
1961 1962 1963 1964
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
1965
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
1966 1967 1968
		grab_swap_token();
	}

1969
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
1970 1971 1972 1973
	mark_page_accessed(page);
	lock_page(page);

	/*
1974
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
1975
	 */
1976
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
1977
	if (unlikely(!pte_same(*page_table, orig_pte)))
1978 1979 1980 1981 1982
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
1983 1984 1985 1986
	}

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

1987
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
	pte = mk_pte(page, vma->vm_page_prot);
	if (write_access && can_share_swap_page(page)) {
		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);

1998 1999 2000 2001 2002
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2003 2004
	if (write_access) {
		if (do_wp_page(mm, vma, address,
2005
				page_table, pmd, ptl, pte) == VM_FAULT_OOM)
L
Linus Torvalds 已提交
2006 2007 2008 2009 2010 2011 2012
			ret = VM_FAULT_OOM;
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
	lazy_mmu_prot_update(pte);
2013
unlock:
2014
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2015 2016
out:
	return ret;
2017
out_nomap:
2018
	pte_unmap_unlock(page_table, ptl);
2019 2020
	unlock_page(page);
	page_cache_release(page);
2021
	return ret;
L
Linus Torvalds 已提交
2022 2023 2024
}

/*
2025 2026 2027
 * 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
2028
 */
2029 2030 2031
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
2032
{
2033 2034
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2035 2036
	pte_t entry;

2037
	if (write_access) {
L
Linus Torvalds 已提交
2038 2039 2040 2041
		/* Allocate our own private page. */
		pte_unmap(page_table);

		if (unlikely(anon_vma_prepare(vma)))
2042 2043
			goto oom;
		page = alloc_zeroed_user_highpage(vma, address);
L
Linus Torvalds 已提交
2044
		if (!page)
2045
			goto oom;
L
Linus Torvalds 已提交
2046

2047 2048
		entry = mk_pte(page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2049 2050 2051 2052 2053

		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
		if (!pte_none(*page_table))
			goto release;
		inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2054
		lru_cache_add_active(page);
N
Nick Piggin 已提交
2055
		page_add_new_anon_rmap(page, vma, address);
N
Nick Piggin 已提交
2056
	} else {
2057 2058 2059 2060 2061
		/* Map the ZERO_PAGE - vm_page_prot is readonly */
		page = ZERO_PAGE(address);
		page_cache_get(page);
		entry = mk_pte(page, vma->vm_page_prot);

H
Hugh Dickins 已提交
2062
		ptl = pte_lockptr(mm, pmd);
2063 2064 2065
		spin_lock(ptl);
		if (!pte_none(*page_table))
			goto release;
N
Nick Piggin 已提交
2066 2067
		inc_mm_counter(mm, file_rss);
		page_add_file_rmap(page);
L
Linus Torvalds 已提交
2068 2069
	}

2070
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2071 2072

	/* No need to invalidate - it was non-present before */
2073
	update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2074
	lazy_mmu_prot_update(entry);
2075
unlock:
2076
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2077
	return VM_FAULT_MINOR;
2078 2079 2080
release:
	page_cache_release(page);
	goto unlock;
2081
oom:
L
Linus Torvalds 已提交
2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093
	return VM_FAULT_OOM;
}

/*
 * do_no_page() tries to create a new page mapping. It aggressively
 * tries to share with existing pages, but makes a separate copy if
 * the "write_access" parameter is true in order to avoid the next
 * page fault.
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2094 2095 2096
 * 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
2097
 */
2098 2099 2100
static int do_no_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
2101
{
2102
	spinlock_t *ptl;
2103
	struct page *new_page;
L
Linus Torvalds 已提交
2104 2105 2106 2107 2108
	struct address_space *mapping = NULL;
	pte_t entry;
	unsigned int sequence = 0;
	int ret = VM_FAULT_MINOR;
	int anon = 0;
2109
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2110 2111

	pte_unmap(page_table);
2112 2113
	BUG_ON(vma->vm_flags & VM_PFNMAP);

L
Linus Torvalds 已提交
2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;
		sequence = mapping->truncate_count;
		smp_rmb(); /* serializes i_size against truncate_count */
	}
retry:
	new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
	/*
	 * No smp_rmb is needed here as long as there's a full
	 * spin_lock/unlock sequence inside the ->nopage callback
	 * (for the pagecache lookup) that acts as an implicit
	 * smp_mb() and prevents the i_size read to happen
	 * after the next truncate_count read.
	 */

	/* no page was available -- either SIGBUS or OOM */
	if (new_page == NOPAGE_SIGBUS)
		return VM_FAULT_SIGBUS;
	if (new_page == NOPAGE_OOM)
		return VM_FAULT_OOM;

	/*
	 * Should we do an early C-O-W break?
	 */
2138 2139 2140
	if (write_access) {
		if (!(vma->vm_flags & VM_SHARED)) {
			struct page *page;
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Linus Torvalds 已提交
2141

2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162
			if (unlikely(anon_vma_prepare(vma)))
				goto oom;
			page = alloc_page_vma(GFP_HIGHUSER, vma, address);
			if (!page)
				goto oom;
			copy_user_highpage(page, new_page, address);
			page_cache_release(new_page);
			new_page = page;
			anon = 1;

		} else {
			/* if the page will be shareable, see if the backing
			 * address space wants to know that the page is about
			 * to become writable */
			if (vma->vm_ops->page_mkwrite &&
			    vma->vm_ops->page_mkwrite(vma, new_page) < 0
			    ) {
				page_cache_release(new_page);
				return VM_FAULT_SIGBUS;
			}
		}
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2163 2164
	}

2165
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
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2166 2167 2168 2169 2170 2171
	/*
	 * For a file-backed vma, someone could have truncated or otherwise
	 * invalidated this page.  If unmap_mapping_range got called,
	 * retry getting the page.
	 */
	if (mapping && unlikely(sequence != mapping->truncate_count)) {
2172
		pte_unmap_unlock(page_table, ptl);
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2173
		page_cache_release(new_page);
2174 2175 2176
		cond_resched();
		sequence = mapping->truncate_count;
		smp_rmb();
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2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197
		goto retry;
	}

	/*
	 * 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... */
	if (pte_none(*page_table)) {
		flush_icache_page(vma, new_page);
		entry = mk_pte(new_page, vma->vm_page_prot);
		if (write_access)
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2198
			inc_mm_counter(mm, anon_rss);
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2199
			lru_cache_add_active(new_page);
N
Nick Piggin 已提交
2200
			page_add_new_anon_rmap(new_page, vma, address);
2201
		} else {
2202
			inc_mm_counter(mm, file_rss);
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2203
			page_add_file_rmap(new_page);
2204 2205 2206 2207
			if (write_access) {
				dirty_page = new_page;
				get_page(dirty_page);
			}
2208
		}
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2209 2210 2211
	} else {
		/* One of our sibling threads was faster, back out. */
		page_cache_release(new_page);
2212
		goto unlock;
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2213 2214 2215 2216 2217
	}

	/* no need to invalidate: a not-present page shouldn't be cached */
	update_mmu_cache(vma, address, entry);
	lazy_mmu_prot_update(entry);
2218
unlock:
2219
	pte_unmap_unlock(page_table, ptl);
2220 2221 2222 2223
	if (dirty_page) {
		set_page_dirty(dirty_page);
		put_page(dirty_page);
	}
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2224 2225 2226
	return ret;
oom:
	page_cache_release(new_page);
2227
	return VM_FAULT_OOM;
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2228 2229 2230 2231 2232 2233
}

/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2234 2235 2236 2237
 *
 * 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
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 */
2239 2240 2241
static int do_file_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
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2242
{
2243
	pgoff_t pgoff;
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2244 2245
	int err;

H
Hugh Dickins 已提交
2246
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2247
		return VM_FAULT_MINOR;
L
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2248

2249 2250 2251 2252
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2253
		print_bad_pte(vma, orig_pte, address);
2254 2255 2256 2257 2258 2259 2260
		return VM_FAULT_OOM;
	}
	/* We can then assume vm->vm_ops && vma->vm_ops->populate */

	pgoff = pte_to_pgoff(orig_pte);
	err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
					vma->vm_page_prot, pgoff, 0);
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2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276
	if (err == -ENOMEM)
		return VM_FAULT_OOM;
	if (err)
		return VM_FAULT_SIGBUS;
	return VM_FAULT_MAJOR;
}

/*
 * 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
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 * 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.
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Linus Torvalds 已提交
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 */
static inline int handle_pte_fault(struct mm_struct *mm,
2282 2283
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
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2284 2285
{
	pte_t entry;
2286
	pte_t old_entry;
2287
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2288

2289
	old_entry = entry = *pte;
L
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2290
	if (!pte_present(entry)) {
2291 2292 2293 2294 2295 2296 2297
		if (pte_none(entry)) {
			if (!vma->vm_ops || !vma->vm_ops->nopage)
				return do_anonymous_page(mm, vma, address,
					pte, pmd, write_access);
			return do_no_page(mm, vma, address,
					pte, pmd, write_access);
		}
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2298
		if (pte_file(entry))
2299 2300 2301 2302
			return do_file_page(mm, vma, address,
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2303 2304
	}

H
Hugh Dickins 已提交
2305
	ptl = pte_lockptr(mm, pmd);
2306 2307 2308
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
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Linus Torvalds 已提交
2309 2310
	if (write_access) {
		if (!pte_write(entry))
2311 2312
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2313 2314 2315
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329
	if (!pte_same(old_entry, entry)) {
		ptep_set_access_flags(vma, address, pte, entry, write_access);
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(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);
	}
2330 2331
unlock:
	pte_unmap_unlock(pte, ptl);
L
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2332 2333 2334 2335 2336 2337
	return VM_FAULT_MINOR;
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
2338
int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
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2339 2340 2341 2342 2343 2344 2345 2346 2347
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2348
	count_vm_event(PGFAULT);
L
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2349

2350 2351
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2352 2353 2354 2355

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2356
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2357 2358
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2359
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2360 2361
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2362
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2363

H
Hugh Dickins 已提交
2364
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
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2365 2366
}

2367 2368
EXPORT_SYMBOL_GPL(__handle_mm_fault);

L
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2369 2370 2371
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2372
 * We've already handled the fast-path in-line.
L
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2373
 */
2374
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2375
{
H
Hugh Dickins 已提交
2376 2377
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2378
		return -ENOMEM;
L
Linus Torvalds 已提交
2379

H
Hugh Dickins 已提交
2380
	spin_lock(&mm->page_table_lock);
2381
	if (pgd_present(*pgd))		/* Another has populated it */
L
Linus Torvalds 已提交
2382
		pud_free(new);
2383 2384
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2385
	spin_unlock(&mm->page_table_lock);
2386
	return 0;
L
Linus Torvalds 已提交
2387
}
2388 2389 2390 2391 2392 2393
#else
/* Workaround for gcc 2.96 */
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
	return 0;
}
L
Linus Torvalds 已提交
2394 2395 2396 2397 2398
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2399
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2400
 */
2401
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2402
{
H
Hugh Dickins 已提交
2403 2404
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2405
		return -ENOMEM;
L
Linus Torvalds 已提交
2406

H
Hugh Dickins 已提交
2407
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2408
#ifndef __ARCH_HAS_4LEVEL_HACK
2409
	if (pud_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2410
		pmd_free(new);
2411 2412
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2413
#else
2414
	if (pgd_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2415
		pmd_free(new);
2416 2417
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2418
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2419
	spin_unlock(&mm->page_table_lock);
2420
	return 0;
2421 2422 2423 2424 2425 2426
}
#else
/* Workaround for gcc 2.96 */
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
	return 0;
L
Linus Torvalds 已提交
2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438
}
#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)
		return -1;
	write = (vma->vm_flags & VM_WRITE) != 0;
2439 2440
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
L
Linus Torvalds 已提交
2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491
	len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
	if (ret < 0)
		return ret;
	return ret == len ? 0 : -1;
}

/* 
 * Map a vmalloc()-space virtual address to the physical page.
 */
struct page * vmalloc_to_page(void * vmalloc_addr)
{
	unsigned long addr = (unsigned long) vmalloc_addr;
	struct page *page = NULL;
	pgd_t *pgd = pgd_offset_k(addr);
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
  
	if (!pgd_none(*pgd)) {
		pud = pud_offset(pgd, addr);
		if (!pud_none(*pud)) {
			pmd = pmd_offset(pud, addr);
			if (!pmd_none(*pmd)) {
				ptep = pte_offset_map(pmd, addr);
				pte = *ptep;
				if (pte_present(pte))
					page = pte_page(pte);
				pte_unmap(ptep);
			}
		}
	}
	return page;
}

EXPORT_SYMBOL(vmalloc_to_page);

/*
 * Map a vmalloc()-space virtual address to the physical page frame number.
 */
unsigned long vmalloc_to_pfn(void * vmalloc_addr)
{
	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
}

EXPORT_SYMBOL(vmalloc_to_pfn);

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2492
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2493 2494 2495 2496 2497 2498 2499

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;
	gate_vma.vm_page_prot = PAGE_READONLY;
H
Hugh Dickins 已提交
2500
	gate_vma.vm_flags = 0;
L
Linus Torvalds 已提交
2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524
	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 */