memory.c 71.9 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include <linux/module.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/writeback.h>
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#include <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;

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);

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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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}

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(mm, 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 */
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		pte_free_kernel(&init_mm, new);
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	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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#ifdef CONFIG_DEBUG_VM
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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;
	}
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#endif
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	/*
	 * 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);
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		pte = pte_wrprotect(pte);
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	}

	/*
	 * 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);
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		page_dup_rmap(page, vma, addr);
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		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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	arch_enter_lazy_mmu_mode();
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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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			    spin_needbreak(src_ptl) || spin_needbreak(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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	arch_leave_lazy_mmu_mode();
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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;

590 591 592 593 594 595
	/*
	 * 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.
	 */
596
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
597 598 599 600
		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;
}

617
static unsigned long zap_pte_range(struct mmu_gather *tlb,
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				struct vm_area_struct *vma, pmd_t *pmd,
L
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				unsigned long addr, unsigned long end,
620
				long *zap_work, struct zap_details *details)
L
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{
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622
	struct mm_struct *mm = tlb->mm;
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	pte_t *pte;
624
	spinlock_t *ptl;
625 626
	int file_rss = 0;
	int anon_rss = 0;
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628
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
629
	arch_enter_lazy_mmu_mode();
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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
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
677
					SetPageReferenced(page);
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				file_rss--;
679
			}
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			page_remove_rmap(page, vma);
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			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));
692
		pte_clear_not_present_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
	arch_leave_lazy_mmu_mode();
697
	pte_unmap_unlock(pte - 1, ptl);
698 699

	return addr;
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}

702
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
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703
				struct vm_area_struct *vma, pud_t *pud,
L
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				unsigned long addr, unsigned long end,
705
				long *zap_work, struct zap_details *details)
L
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{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
713 714
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
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			continue;
716 717 718 719 720 721
		}
		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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}

724
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
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725
				struct vm_area_struct *vma, pgd_t *pgd,
L
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				unsigned long addr, unsigned long end,
727
				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);
735 736
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
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			continue;
738 739 740 741 742 743
		}
		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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}

746 747
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
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748
				unsigned long addr, unsigned long end,
749
				long *zap_work, struct zap_details *details)
L
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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);
762 763
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
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			continue;
765 766 767 768
		}
		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);
770 771

	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
 *
790
 * Returns the end address of the unmapping (restart addr if interrupted).
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 *
792
 * Unmap all pages in the vma list.
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 *
794 795
 * 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.
 */
807
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
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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)
{
812
	long zap_work = ZAP_BLOCK_SIZE;
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	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
815
	unsigned long start = start_addr;
L
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	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
817
	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;
			}

838
			if (unlikely(is_vm_hugetlb_page(vma))) {
L
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				unmap_hugepage_range(vma, start, end);
840 841 842 843 844 845 846 847 848 849
				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() ||
N
Nick Piggin 已提交
855
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
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856
				if (i_mmap_lock) {
857
					*tlbp = NULL;
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					goto out;
				}
				cond_resched();
			}

863
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
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			tlb_start_valid = 0;
865
			zap_work = ZAP_BLOCK_SIZE;
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		}
	}
out:
869
	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
 */
879
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);
889
	update_hiwater_rss(mm);
890 891 892
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
893
	return end;
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}

/*
 * Do a quick page-table lookup for a single page.
 */
899
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
900
			unsigned int flags)
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{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
906
	spinlock_t *ptl;
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	struct page *page;
908
	struct mm_struct *mm = vma->vm_mm;
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910 911 912 913 914
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
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916
	page = NULL;
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	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
919
		goto no_page_table;
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	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
923
		goto no_page_table;
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	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
927 928 929 930 931
		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;
933
	}
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935
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
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936 937 938 939
	if (!ptep)
		goto out;

	pte = *ptep;
940 941 942 943
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
944 945
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
946
		goto unlock;
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948 949 950 951 952 953 954 955 956 957
	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:
959
	return page;
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961 962 963 964 965 966
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
N
Nick Piggin 已提交
967
		page = ZERO_PAGE(0);
968 969 970 971 972
		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;
980
	unsigned int vm_flags;
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	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
986 987
	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 {
991 992
		struct vm_area_struct *vma;
		unsigned int foll_flags;
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993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011

		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);
1012 1013
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
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1014
			pte = pte_offset_map(pmd, pg);
1015 1016 1017 1018
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
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1019
			if (pages) {
1020
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1021 1022 1023
				pages[i] = page;
				if (page)
					get_page(page);
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1024 1025 1026 1027 1028 1029 1030 1031 1032 1033
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1034
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1035
				|| !(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,
1040
						&start, &len, i, write);
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			continue;
		}
1043 1044 1045 1046 1047

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
		if (!write && !(vma->vm_flags & VM_LOCKED) &&
1048 1049
		    (!vma->vm_ops || (!vma->vm_ops->nopage &&
					!vma->vm_ops->fault)))
1050 1051
			foll_flags |= FOLL_ANON;

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		do {
1053
			struct page *page;
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1055 1056 1057 1058 1059 1060 1061 1062
			/*
			 * If tsk is ooming, cut off its access to large memory
			 * allocations. It has a pending SIGKILL, but it can't
			 * be processed until returning to user space.
			 */
			if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
				return -ENOMEM;

1063 1064
			if (write)
				foll_flags |= FOLL_WRITE;
1065

1066
			cond_resched();
1067
			while (!(page = follow_page(vma, start, foll_flags))) {
1068
				int ret;
N
Nick Piggin 已提交
1069
				ret = handle_mm_fault(mm, vma, start,
1070
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
					else if (ret & VM_FAULT_SIGBUS)
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1083
				/*
N
Nick Piggin 已提交
1084 1085 1086 1087 1088
				 * 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.
1089 1090
				 */
				if (ret & VM_FAULT_WRITE)
1091
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1092

1093
				cond_resched();
L
Linus Torvalds 已提交
1094 1095
			}
			if (pages) {
1096
				pages[i] = page;
1097

1098
				flush_anon_page(vma, page, start);
1099
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1100 1101 1102 1103 1104 1105
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1106 1107
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1108 1109 1110 1111
	return i;
}
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1112 1113
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1114 1115 1116 1117
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1118
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1119 1120 1121 1122 1123 1124
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1125 1126 1127 1128 1129 1130 1131 1132 1133 1134
/*
 * 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;
1135
	pte_t *pte;
1136 1137 1138
	spinlock_t *ptl;  

	retval = -EINVAL;
1139
	if (PageAnon(page))
1140 1141 1142
		goto out;
	retval = -ENOMEM;
	flush_dcache_page(page);
1143
	pte = get_locked_pte(mm, addr, &ptl);
1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162
	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;
}

1163 1164 1165 1166 1167 1168
/**
 * vm_insert_page - insert single page into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @page: source kernel page
 *
1169 1170 1171 1172 1173 1174
 * 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
1175
 * (see split_page()).
1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190
 *
 * 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;
1191
	vma->vm_flags |= VM_INSERTPAGE;
1192 1193
	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
1194
EXPORT_SYMBOL(vm_insert_page);
1195

N
Nick Piggin 已提交
1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240
/**
 * vm_insert_pfn - insert single pfn into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @pfn: source kernel pfn
 *
 * Similar to vm_inert_page, this allows drivers to insert individual pages
 * they've allocated into a user vma. Same comments apply.
 *
 * This function should only be called from a vm_ops->fault handler, and
 * in that case the handler should return NULL.
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
		unsigned long pfn)
{
	struct mm_struct *mm = vma->vm_mm;
	int retval;
	pte_t *pte, entry;
	spinlock_t *ptl;

	BUG_ON(!(vma->vm_flags & VM_PFNMAP));
	BUG_ON(is_cow_mapping(vma->vm_flags));

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

	/* Ok, finally just insert the thing.. */
	entry = pfn_pte(pfn, vma->vm_page_prot);
	set_pte_at(mm, addr, pte, entry);
	update_mmu_cache(vma, addr, entry);

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

out:
	return retval;
}
EXPORT_SYMBOL(vm_insert_pfn);

L
Linus Torvalds 已提交
1241 1242 1243 1244 1245 1246 1247 1248 1249 1250
/*
 * 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
1251
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1252

H
Hugh Dickins 已提交
1253
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1254 1255
	if (!pte)
		return -ENOMEM;
1256
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1257 1258
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1259
		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
L
Linus Torvalds 已提交
1260 1261
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1262
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1263
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 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
	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;
}

1307 1308 1309 1310 1311 1312 1313 1314 1315 1316
/**
 * remap_pfn_range - remap kernel memory to userspace
 * @vma: user vma to map to
 * @addr: target user address to start at
 * @pfn: physical address of kernel memory
 * @size: size of map area
 * @prot: page protection flags for this mapping
 *
 *  Note: this is only safe if the mm semaphore is held when called.
 */
L
Linus Torvalds 已提交
1317 1318 1319 1320 1321
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;
1322
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1323 1324 1325 1326 1327 1328 1329 1330
	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
1331 1332 1333 1334 1335
	 *   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.
1336 1337 1338
	 *   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
1339 1340 1341 1342
	 *
	 * 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
1343
	 */
1344
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1345
		if (addr != vma->vm_start || end != vma->vm_end)
1346
			return -EINVAL;
L
Linus Torvalds 已提交
1347 1348 1349
		vma->vm_pgoff = pfn;
	}

1350
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366

	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);

1367 1368 1369 1370 1371 1372 1373
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pte_t *pte;
	int err;
	struct page *pmd_page;
1374
	spinlock_t *uninitialized_var(ptl);
1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460

	pte = (mm == &init_mm) ?
		pte_alloc_kernel(pmd, addr) :
		pte_alloc_map_lock(mm, pmd, addr, &ptl);
	if (!pte)
		return -ENOMEM;

	BUG_ON(pmd_huge(*pmd));

	pmd_page = pmd_page(*pmd);

	do {
		err = fn(pte, pmd_page, addr, data);
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

	if (mm != &init_mm)
		pte_unmap_unlock(pte-1, ptl);
	return err;
}

static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pmd_t *pmd;
	unsigned long next;
	int err;

	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);
	return err;
}

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

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

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

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

1461 1462 1463 1464 1465 1466 1467 1468 1469
/*
 * 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
1470
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1471 1472 1473 1474 1475
				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
1476 1477
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1478
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1479
		spin_unlock(ptl);
1480 1481 1482 1483 1484 1485
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498
/*
 * 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;
}

1499
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1500 1501 1502 1503 1504 1505 1506 1507 1508
{
	/*
	 * 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
1509 1510 1511 1512 1513 1514 1515 1516 1517
		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))
1518 1519
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1520
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1521 1522
	} else
		copy_user_highpage(dst, src, va, vma);
1523 1524
}

L
Linus Torvalds 已提交
1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538
/*
 * 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.
 *
1539 1540 1541
 * 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
1542
 */
1543 1544
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1545
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1546
{
1547
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1548
	pte_t entry;
N
Nick Piggin 已提交
1549
	int reuse = 0, ret = 0;
1550
	int page_mkwrite = 0;
1551
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1552

1553 1554 1555
	old_page = vm_normal_page(vma, address, orig_pte);
	if (!old_page)
		goto gotten;
L
Linus Torvalds 已提交
1556

1557
	/*
P
Peter Zijlstra 已提交
1558 1559
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1560
	 */
P
Peter Zijlstra 已提交
1561 1562 1563 1564 1565 1566
	if (PageAnon(old_page)) {
		if (!TestSetPageLocked(old_page)) {
			reuse = can_share_swap_page(old_page);
			unlock_page(old_page);
		}
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1567
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1568 1569 1570 1571 1572
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
			/*
			 * Notify the address space that the page is about to
			 * become writable so that it can prohibit this or wait
			 * for the page to get into an appropriate state.
			 *
			 * We do this without the lock held, so that it can
			 * sleep if it needs to.
			 */
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);

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

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
1596
			page_cache_release(old_page);
1597 1598
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1599 1600

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1601
		}
1602 1603
		dirty_page = old_page;
		get_page(dirty_page);
1604 1605 1606 1607 1608 1609 1610
		reuse = 1;
	}

	if (reuse) {
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1611
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1612
			update_mmu_cache(vma, address, entry);
1613 1614
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1615 1616 1617 1618 1619
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1620
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1621
gotten:
1622
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1623 1624

	if (unlikely(anon_vma_prepare(vma)))
1625
		goto oom;
N
Nick Piggin 已提交
1626 1627 1628 1629 1630
	VM_BUG_ON(old_page == ZERO_PAGE(0));
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
	if (!new_page)
		goto oom;
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
1631
	__SetPageUptodate(new_page);
1632

L
Linus Torvalds 已提交
1633 1634 1635
	/*
	 * Re-check the pte - we dropped the lock
	 */
1636
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1637
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1638
		if (old_page) {
N
Nick Piggin 已提交
1639
			page_remove_rmap(old_page, vma);
H
Hugh Dickins 已提交
1640 1641 1642 1643 1644
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1645
			inc_mm_counter(mm, anon_rss);
1646
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1647 1648
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1649 1650 1651 1652 1653 1654 1655 1656
		/*
		 * Clear the pte entry and flush it first, before updating the
		 * pte with the new entry. This will avoid a race condition
		 * seen in the presence of one thread doing SMC and another
		 * thread doing COW.
		 */
		ptep_clear_flush(vma, address, page_table);
		set_pte_at(mm, address, page_table, entry);
1657
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1658
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1659
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1660 1661 1662

		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1663
		ret |= VM_FAULT_WRITE;
L
Linus Torvalds 已提交
1664
	}
H
Hugh Dickins 已提交
1665 1666 1667 1668
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1669
unlock:
1670
	pte_unmap_unlock(page_table, ptl);
1671
	if (dirty_page) {
1672 1673 1674
		if (vma->vm_file)
			file_update_time(vma->vm_file);

1675 1676 1677 1678 1679 1680 1681 1682 1683
		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
		 * do_no_page is protected similarly.
		 */
		wait_on_page_locked(dirty_page);
1684
		set_page_dirty_balance(dirty_page, page_mkwrite);
1685 1686
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1687
	return ret;
1688
oom:
H
Hugh Dickins 已提交
1689 1690
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1691
	return VM_FAULT_OOM;
1692 1693 1694 1695

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
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
}

/*
 * 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
1723
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749
 * 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;

1750 1751
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
1752
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
1753 1754
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
1755 1756
	 */

L
Linus Torvalds 已提交
1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767
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;
		}
	}

1768 1769
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
1770
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
1771

1772
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1773 1774 1775 1776 1777 1778
		/* 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 */
1779
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
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 1843 1844 1845
		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;
	}
}

/**
1846
 * 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
1847
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883
 * @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);

1884
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900
	mapping->truncate_count++;
	if (unlikely(is_restart_addr(mapping->truncate_count))) {
		if (mapping->truncate_count == 0)
			reset_vma_truncate_counts(mapping);
		mapping->truncate_count++;
	}
	details.truncate_count = mapping->truncate_count;

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

1901 1902 1903 1904
/**
 * vmtruncate - unmap mappings "freed" by truncate() syscall
 * @inode: inode of the file used
 * @offset: file offset to start truncating
L
Linus Torvalds 已提交
1905 1906 1907 1908 1909 1910 1911
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode * inode, loff_t offset)
{
C
Christoph Hellwig 已提交
1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922
	if (inode->i_size < offset) {
		unsigned long limit;

		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
		if (limit != RLIM_INFINITY && offset > limit)
			goto out_sig;
		if (offset > inode->i_sb->s_maxbytes)
			goto out_big;
		i_size_write(inode, offset);
	} else {
		struct address_space *mapping = inode->i_mapping;
L
Linus Torvalds 已提交
1923

C
Christoph Hellwig 已提交
1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945
		/*
		 * truncation of in-use swapfiles is disallowed - it would
		 * cause subsequent swapout to scribble on the now-freed
		 * blocks.
		 */
		if (IS_SWAPFILE(inode))
			return -ETXTBSY;
		i_size_write(inode, offset);

		/*
		 * unmap_mapping_range is called twice, first simply for
		 * efficiency so that truncate_inode_pages does fewer
		 * single-page unmaps.  However after this first call, and
		 * before truncate_inode_pages finishes, it is possible for
		 * private pages to be COWed, which remain after
		 * truncate_inode_pages finishes, hence the second
		 * unmap_mapping_range call must be made for correctness.
		 */
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
		truncate_inode_pages(mapping, offset);
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	}
1946

L
Linus Torvalds 已提交
1947 1948 1949
	if (inode->i_op && inode->i_op->truncate)
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
1950

L
Linus Torvalds 已提交
1951 1952 1953 1954 1955 1956 1957
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969
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;

1970
	mutex_lock(&inode->i_mutex);
1971 1972 1973
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
1974
	unmap_mapping_range(mapping, offset, (end - offset), 1);
1975 1976
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
1977
	mutex_unlock(&inode->i_mutex);
1978 1979 1980 1981

	return 0;
}

L
Linus Torvalds 已提交
1982
/*
1983 1984 1985
 * 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
1986
 */
1987 1988 1989
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
1990
{
1991
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1992
	struct page *page;
1993
	swp_entry_t entry;
L
Linus Torvalds 已提交
1994
	pte_t pte;
N
Nick Piggin 已提交
1995
	int ret = 0;
L
Linus Torvalds 已提交
1996

H
Hugh Dickins 已提交
1997
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1998
		goto out;
1999 2000

	entry = pte_to_swp_entry(orig_pte);
2001 2002 2003 2004
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2005
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2006 2007
	page = lookup_swap_cache(entry);
	if (!page) {
2008
		grab_swap_token(); /* Contend for token _before_ read-in */
2009 2010
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2011 2012
		if (!page) {
			/*
2013 2014
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2015
			 */
2016
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2017 2018
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2019
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2020
			goto unlock;
L
Linus Torvalds 已提交
2021 2022 2023 2024
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2025
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2026 2027 2028 2029
	}

	mark_page_accessed(page);
	lock_page(page);
2030
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2031 2032

	/*
2033
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2034
	 */
2035
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2036
	if (unlikely(!pte_same(*page_table, orig_pte)))
2037 2038 2039 2040 2041
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2042 2043 2044 2045
	}

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

2046
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2047 2048 2049 2050 2051 2052 2053 2054 2055 2056
	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);

2057 2058 2059 2060 2061
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2062
	if (write_access) {
N
Nick Piggin 已提交
2063
		/* XXX: We could OR the do_wp_page code with this one? */
L
Linus Torvalds 已提交
2064
		if (do_wp_page(mm, vma, address,
N
Nick Piggin 已提交
2065
				page_table, pmd, ptl, pte) & VM_FAULT_OOM)
L
Linus Torvalds 已提交
2066 2067 2068 2069 2070 2071
			ret = VM_FAULT_OOM;
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2072
unlock:
2073
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2074 2075
out:
	return ret;
2076
out_nomap:
2077
	pte_unmap_unlock(page_table, ptl);
2078 2079
	unlock_page(page);
	page_cache_release(page);
2080
	return ret;
L
Linus Torvalds 已提交
2081 2082 2083
}

/*
2084 2085 2086
 * 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
2087
 */
2088 2089 2090
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
2091
{
2092 2093
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2094 2095
	pte_t entry;

N
Nick Piggin 已提交
2096 2097
	/* Allocate our own private page. */
	pte_unmap(page_table);
2098

N
Nick Piggin 已提交
2099 2100 2101 2102 2103
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
N
Nick Piggin 已提交
2104
	__SetPageUptodate(page);
2105

N
Nick Piggin 已提交
2106 2107
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2108

N
Nick Piggin 已提交
2109 2110 2111 2112 2113 2114
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!pte_none(*page_table))
		goto release;
	inc_mm_counter(mm, anon_rss);
	lru_cache_add_active(page);
	page_add_new_anon_rmap(page, vma, address);
2115
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2116 2117

	/* No need to invalidate - it was non-present before */
2118 2119
	update_mmu_cache(vma, address, entry);
unlock:
2120
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2121
	return 0;
2122 2123 2124
release:
	page_cache_release(page);
	goto unlock;
2125
oom:
L
Linus Torvalds 已提交
2126 2127 2128 2129
	return VM_FAULT_OOM;
}

/*
2130
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2131
 * tries to share with existing pages, but makes a separate copy if
2132 2133
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2134 2135 2136 2137
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2138
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2139
 * but allow concurrent faults), and pte neither mapped nor locked.
2140
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2141
 */
2142
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2143
		unsigned long address, pmd_t *pmd,
2144
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2145
{
2146
	pte_t *page_table;
2147
	spinlock_t *ptl;
N
Nick Piggin 已提交
2148
	struct page *page;
L
Linus Torvalds 已提交
2149 2150
	pte_t entry;
	int anon = 0;
2151
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2152 2153
	struct vm_fault vmf;
	int ret;
2154
	int page_mkwrite = 0;
2155

N
Nick Piggin 已提交
2156 2157 2158 2159
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2160

2161 2162
	BUG_ON(vma->vm_flags & VM_PFNMAP);

2163
	if (likely(vma->vm_ops->fault)) {
N
Nick Piggin 已提交
2164
		ret = vma->vm_ops->fault(vma, &vmf);
N
Nick Piggin 已提交
2165 2166
		if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
			return ret;
2167 2168
	} else {
		/* Legacy ->nopage path */
N
Nick Piggin 已提交
2169
		ret = 0;
N
Nick Piggin 已提交
2170
		vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2171
		/* no page was available -- either SIGBUS or OOM */
N
Nick Piggin 已提交
2172
		if (unlikely(vmf.page == NOPAGE_SIGBUS))
2173
			return VM_FAULT_SIGBUS;
N
Nick Piggin 已提交
2174
		else if (unlikely(vmf.page == NOPAGE_OOM))
2175 2176
			return VM_FAULT_OOM;
	}
L
Linus Torvalds 已提交
2177

2178
	/*
N
Nick Piggin 已提交
2179
	 * For consistency in subsequent calls, make the faulted page always
2180 2181
	 * locked.
	 */
N
Nick Piggin 已提交
2182
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2183
		lock_page(vmf.page);
2184
	else
N
Nick Piggin 已提交
2185
		VM_BUG_ON(!PageLocked(vmf.page));
2186

L
Linus Torvalds 已提交
2187 2188 2189
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2190
	page = vmf.page;
2191
	if (flags & FAULT_FLAG_WRITE) {
2192
		if (!(vma->vm_flags & VM_SHARED)) {
2193
			anon = 1;
2194
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2195
				ret = VM_FAULT_OOM;
2196
				goto out;
2197
			}
N
Nick Piggin 已提交
2198 2199
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2200
			if (!page) {
N
Nick Piggin 已提交
2201
				ret = VM_FAULT_OOM;
2202
				goto out;
2203
			}
N
Nick Piggin 已提交
2204
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2205
			__SetPageUptodate(page);
2206
		} else {
2207 2208
			/*
			 * If the page will be shareable, see if the backing
2209
			 * address space wants to know that the page is about
2210 2211
			 * to become writable
			 */
2212 2213 2214
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2215 2216
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2217 2218 2219
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2220 2221 2222 2223 2224 2225 2226 2227
				/*
				 * XXX: this is not quite right (racy vs
				 * invalidate) to unlock and relock the page
				 * like this, however a better fix requires
				 * reworking page_mkwrite locking API, which
				 * is better done later.
				 */
				if (!page->mapping) {
N
Nick Piggin 已提交
2228
					ret = 0;
N
Nick Piggin 已提交
2229 2230 2231
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2232
				page_mkwrite = 1;
2233 2234
			}
		}
2235

L
Linus Torvalds 已提交
2236 2237
	}

2238
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250

	/*
	 * 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... */
2251
	if (likely(pte_same(*page_table, orig_pte))) {
2252 2253
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2254
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2255 2256 2257
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2258 2259 2260
                        inc_mm_counter(mm, anon_rss);
                        lru_cache_add_active(page);
                        page_add_new_anon_rmap(page, vma, address);
2261
		} else {
2262
			inc_mm_counter(mm, file_rss);
2263
			page_add_file_rmap(page);
2264
			if (flags & FAULT_FLAG_WRITE) {
2265
				dirty_page = page;
2266 2267
				get_page(dirty_page);
			}
2268
		}
2269 2270 2271

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2272
	} else {
2273 2274 2275
		if (anon)
			page_cache_release(page);
		else
2276
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2277 2278
	}

2279
	pte_unmap_unlock(page_table, ptl);
2280 2281

out:
N
Nick Piggin 已提交
2282
	unlock_page(vmf.page);
2283
out_unlocked:
2284
	if (anon)
N
Nick Piggin 已提交
2285
		page_cache_release(vmf.page);
2286
	else if (dirty_page) {
2287 2288 2289
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2290
		set_page_dirty_balance(dirty_page, page_mkwrite);
2291 2292
		put_page(dirty_page);
	}
2293

N
Nick Piggin 已提交
2294
	return ret;
2295
}
2296

2297 2298 2299 2300 2301
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2302
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2303 2304
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2305 2306
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2307 2308
}

L
Linus Torvalds 已提交
2309

J
Jes Sorensen 已提交
2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338
/*
 * do_no_pfn() tries to create a new page mapping for a page without
 * a struct_page backing it
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
 * 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.
 *
 * It is expected that the ->nopfn handler always returns the same pfn
 * for a given virtual mapping.
 *
 * Mark this `noinline' to prevent it from bloating the main pagefault code.
 */
static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
		     unsigned long address, pte_t *page_table, pmd_t *pmd,
		     int write_access)
{
	spinlock_t *ptl;
	pte_t entry;
	unsigned long pfn;

	pte_unmap(page_table);
	BUG_ON(!(vma->vm_flags & VM_PFNMAP));
	BUG_ON(is_cow_mapping(vma->vm_flags));

	pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
2339
	if (unlikely(pfn == NOPFN_OOM))
J
Jes Sorensen 已提交
2340
		return VM_FAULT_OOM;
2341
	else if (unlikely(pfn == NOPFN_SIGBUS))
J
Jes Sorensen 已提交
2342
		return VM_FAULT_SIGBUS;
2343
	else if (unlikely(pfn == NOPFN_REFAULT))
N
Nick Piggin 已提交
2344
		return 0;
J
Jes Sorensen 已提交
2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355

	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);

	/* Only go through if we didn't race with anybody else... */
	if (pte_none(*page_table)) {
		entry = pfn_pte(pfn, vma->vm_page_prot);
		if (write_access)
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
	}
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2356
	return 0;
J
Jes Sorensen 已提交
2357 2358
}

L
Linus Torvalds 已提交
2359 2360 2361 2362
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2363 2364 2365 2366
 *
 * 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
2367
 */
N
Nick Piggin 已提交
2368
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2369 2370
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2371
{
N
Nick Piggin 已提交
2372 2373
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2374
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2375

H
Hugh Dickins 已提交
2376
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2377
		return 0;
L
Linus Torvalds 已提交
2378

N
Nick Piggin 已提交
2379 2380
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2381 2382 2383
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2384
		print_bad_pte(vma, orig_pte, address);
2385 2386 2387 2388
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2389
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400
}

/*
 * 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
2401 2402 2403
 * 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
2404 2405
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2406 2407
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2408 2409
{
	pte_t entry;
2410
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2411

2412
	entry = *pte;
L
Linus Torvalds 已提交
2413
	if (!pte_present(entry)) {
2414
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2415
			if (vma->vm_ops) {
2416 2417 2418
				if (vma->vm_ops->fault || vma->vm_ops->nopage)
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2419 2420 2421 2422 2423 2424
				if (unlikely(vma->vm_ops->nopfn))
					return do_no_pfn(mm, vma, address, pte,
							 pmd, write_access);
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2425
		}
L
Linus Torvalds 已提交
2426
		if (pte_file(entry))
N
Nick Piggin 已提交
2427
			return do_nonlinear_fault(mm, vma, address,
2428 2429 2430
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2431 2432
	}

H
Hugh Dickins 已提交
2433
	ptl = pte_lockptr(mm, pmd);
2434 2435 2436
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2437 2438
	if (write_access) {
		if (!pte_write(entry))
2439 2440
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2441 2442 2443
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2444
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455
		update_mmu_cache(vma, address, entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2456 2457
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2458
	return 0;
L
Linus Torvalds 已提交
2459 2460 2461 2462 2463
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2464
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2465 2466 2467 2468 2469 2470 2471 2472 2473
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2474
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2475

2476 2477
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2478 2479 2480 2481

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2482
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2483 2484
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2485
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2486 2487
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2488
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2489

H
Hugh Dickins 已提交
2490
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2491 2492 2493 2494 2495
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2496
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2497
 */
2498
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2499
{
H
Hugh Dickins 已提交
2500 2501
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2502
		return -ENOMEM;
L
Linus Torvalds 已提交
2503

H
Hugh Dickins 已提交
2504
	spin_lock(&mm->page_table_lock);
2505
	if (pgd_present(*pgd))		/* Another has populated it */
2506
		pud_free(mm, new);
2507 2508
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2509
	spin_unlock(&mm->page_table_lock);
2510
	return 0;
L
Linus Torvalds 已提交
2511 2512 2513 2514 2515 2516
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2517
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2518
 */
2519
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2520
{
H
Hugh Dickins 已提交
2521 2522
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2523
		return -ENOMEM;
L
Linus Torvalds 已提交
2524

H
Hugh Dickins 已提交
2525
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2526
#ifndef __ARCH_HAS_4LEVEL_HACK
2527
	if (pud_present(*pud))		/* Another has populated it */
2528
		pmd_free(mm, new);
2529 2530
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2531
#else
2532
	if (pgd_present(*pud))		/* Another has populated it */
2533
		pmd_free(mm, new);
2534 2535
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2536
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2537
	spin_unlock(&mm->page_table_lock);
2538
	return 0;
2539
}
L
Linus Torvalds 已提交
2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550
#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;
2551 2552
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2553
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2554 2555 2556 2557 2558 2559 2560 2561 2562 2563
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
	if (ret < 0)
		return ret;
	return ret == len ? 0 : -1;
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2564
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2565 2566 2567 2568 2569 2570

static int __init gate_vma_init(void)
{
	gate_vma.vm_mm = NULL;
	gate_vma.vm_start = FIXADDR_USER_START;
	gate_vma.vm_end = FIXADDR_USER_END;
R
Roland McGrath 已提交
2571 2572
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2573 2574 2575 2576 2577 2578 2579
	/*
	 * Make sure the vDSO gets into every core dump.
	 * Dumping its contents makes post-mortem fully interpretable later
	 * without matching up the same kernel and hardware config to see
	 * what PC values meant.
	 */
	gate_vma.vm_flags |= VM_ALWAYSDUMP;
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Linus Torvalds 已提交
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	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 */
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/*
 * Access another process' address space.
 * Source/target buffer must be kernel space,
 * Do not walk the page table directly, use get_user_pages
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	struct page *page;
	void *old_buf = buf;

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

	down_read(&mm->mmap_sem);
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Simon Arlott 已提交
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	/* ignore errors, just check how much was successfully transferred */
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	while (len) {
		int bytes, ret, offset;
		void *maddr;

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
		if (ret <= 0)
			break;

		bytes = len;
		offset = addr & (PAGE_SIZE-1);
		if (bytes > PAGE_SIZE-offset)
			bytes = PAGE_SIZE-offset;

		maddr = kmap(page);
		if (write) {
			copy_to_user_page(vma, page, addr,
					  maddr + offset, buf, bytes);
			set_page_dirty_lock(page);
		} else {
			copy_from_user_page(vma, page, addr,
					    buf, maddr + offset, bytes);
		}
		kunmap(page);
		page_cache_release(page);
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
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/*
 * Print the name of a VMA.
 */
void print_vma_addr(char *prefix, unsigned long ip)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;

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

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