memory.c 71.8 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;
unsigned long vmalloc_earlyreserve;

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

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int randomize_va_space __read_mostly = 1;

static int __init disable_randmaps(char *s)
{
	randomize_va_space = 0;
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	return 1;
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}
__setup("norandmaps", disable_randmaps);


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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	pte_lock_init(new);
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	spin_lock(&mm->page_table_lock);
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	if (pmd_present(*pmd)) {	/* Another has populated it */
		pte_lock_deinit(new);
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		pte_free(new);
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	} else {
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		mm->nr_ptes++;
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		inc_zone_page_state(new, NR_PAGETABLE);
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		pmd_populate(mm, pmd, new);
	}
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	spin_unlock(&mm->page_table_lock);
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	return 0;
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}

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

	spin_lock(&init_mm.page_table_lock);
	if (pmd_present(*pmd))		/* Another has populated it */
		pte_free_kernel(new);
	else
		pmd_populate_kernel(&init_mm, pmd, new);
	spin_unlock(&init_mm.page_table_lock);
	return 0;
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}

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

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/*
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 * This function is called to print an error when a bad pte
 * is found. For example, we might have a PFN-mapped pte in
 * a region that doesn't allow it.
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 *
 * The calling function must still handle the error.
 */
void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
{
	printk(KERN_ERR "Bad pte = %08llx, process = %s, "
			"vm_flags = %lx, vaddr = %lx\n",
		(long long)pte_val(pte),
		(vma->vm_mm == current->mm ? current->comm : "???"),
		vma->vm_flags, vaddr);
	dump_stack();
}

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

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

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

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

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

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

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

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

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

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
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	if (is_cow_mapping(vm_flags)) {
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		ptep_set_wrprotect(src_mm, addr, src_pte);
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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);
		page_dup_rmap(page);
		rss[!!PageAnon(page)]++;
	}
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out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
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}

static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pte_t *src_pte, *dst_pte;
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	spinlock_t *src_ptl, *dst_ptl;
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	int progress = 0;
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	int rss[2];
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again:
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	rss[1] = rss[0] = 0;
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	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
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	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
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	src_ptl = pte_lockptr(src_mm, src_pmd);
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	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
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	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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			    need_lockbreak(src_ptl) ||
			    need_lockbreak(dst_ptl))
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				break;
		}
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		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
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		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
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		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

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	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;

594 595 596 597 598 599
	/*
	 * 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.
	 */
600
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
601 602 603 604
		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;
}

621
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
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				struct vm_area_struct *vma, pmd_t *pmd,
L
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623
				unsigned long addr, unsigned long end,
624
				long *zap_work, struct zap_details *details)
L
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{
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	struct mm_struct *mm = tlb->mm;
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	pte_t *pte;
628
	spinlock_t *ptl;
629 630
	int file_rss = 0;
	int anon_rss = 0;
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632
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
633
	arch_enter_lazy_mmu_mode();
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	do {
		pte_t ptent = *pte;
636 637
		if (pte_none(ptent)) {
			(*zap_work)--;
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			continue;
639
		}
640 641 642

		(*zap_work) -= PAGE_SIZE;

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		if (pte_present(ptent)) {
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			struct page *page;
645

646
			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,
666
							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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Nick Piggin 已提交
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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--;
677 678 679 680 681
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
					mark_page_accessed(page);
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				file_rss--;
683
			}
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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));
696
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
697
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
698

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	add_mm_rss(mm, file_rss, anon_rss);
700
	arch_leave_lazy_mmu_mode();
701
	pte_unmap_unlock(pte - 1, ptl);
702 703

	return addr;
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}

706
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
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707
				struct vm_area_struct *vma, pud_t *pud,
L
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				unsigned long addr, unsigned long end,
709
				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);
717 718
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
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			continue;
720 721 722 723 724 725
		}
		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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}

728
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
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729
				struct vm_area_struct *vma, pgd_t *pgd,
L
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				unsigned long addr, unsigned long end,
731
				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);
739 740
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
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741
			continue;
742 743 744 745 746 747
		}
		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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}

750 751
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
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				unsigned long addr, unsigned long end,
753
				long *zap_work, struct zap_details *details)
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{
	pgd_t *pgd;
	unsigned long next;

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

	BUG_ON(addr >= end);
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
766 767
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
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			continue;
769 770 771 772
		}
		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);
774 775

	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
 *
794
 * Returns the end address of the unmapping (restart addr if interrupted).
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 *
796
 * Unmap all pages in the vma list.
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 *
798 799
 * 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.
 */
811
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)
{
816
	long zap_work = ZAP_BLOCK_SIZE;
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	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
819
	unsigned long start = start_addr;
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	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
821
	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;
			}

842
			if (unlikely(is_vm_hugetlb_page(vma))) {
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				unmap_hugepage_range(vma, start, end);
844 845 846 847 848 849 850 851 852 853
				zap_work -= (end - start) /
						(HPAGE_SIZE / PAGE_SIZE);
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

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

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
				(i_mmap_lock && need_lockbreak(i_mmap_lock))) {
				if (i_mmap_lock) {
861
					*tlbp = NULL;
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					goto out;
				}
				cond_resched();
			}

867
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
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			tlb_start_valid = 0;
869
			zap_work = ZAP_BLOCK_SIZE;
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		}
	}
out:
873
	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
 */
883
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);
893
	update_hiwater_rss(mm);
894 895 896
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
897
	return end;
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}

/*
 * Do a quick page-table lookup for a single page.
 */
903
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
904
			unsigned int flags)
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{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
910
	spinlock_t *ptl;
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	struct page *page;
912
	struct mm_struct *mm = vma->vm_mm;
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914 915 916 917 918
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
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920
	page = NULL;
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	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
923
		goto no_page_table;
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	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
927
		goto no_page_table;
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	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
931 932 933 934 935
		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;
937
	}
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939
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
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	if (!ptep)
		goto out;

	pte = *ptep;
944 945 946 947
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
948 949
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
950
		goto unlock;
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952 953 954 955 956 957 958 959 960 961
	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:
963
	return page;
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965 966 967 968 969 970 971 972 973 974 975 976
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
		page = ZERO_PAGE(address);
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
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}

int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long start, int len, int write, int force,
		struct page **pages, struct vm_area_struct **vmas)
{
	int i;
984
	unsigned int vm_flags;
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	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
990 991
	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 {
995 996
		struct vm_area_struct *vma;
		unsigned int foll_flags;
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		vma = find_extend_vma(mm, start);
		if (!vma && in_gate_area(tsk, start)) {
			unsigned long pg = start & PAGE_MASK;
			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
			if (write) /* user gate pages are read-only */
				return i ? : -EFAULT;
			if (pg > TASK_SIZE)
				pgd = pgd_offset_k(pg);
			else
				pgd = pgd_offset_gate(mm, pg);
			BUG_ON(pgd_none(*pgd));
			pud = pud_offset(pgd, pg);
			BUG_ON(pud_none(*pud));
			pmd = pmd_offset(pud, pg);
1016 1017
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
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1018
			pte = pte_offset_map(pmd, pg);
1019 1020 1021 1022
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
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			if (pages) {
1024
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1025 1026 1027
				pages[i] = page;
				if (page)
					get_page(page);
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			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1038
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1039
				|| !(vm_flags & vma->vm_flags))
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			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
						&start, &len, i);
			continue;
		}
1047 1048 1049 1050 1051 1052 1053 1054

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

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		do {
1056
			struct page *page;
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1058 1059
			if (write)
				foll_flags |= FOLL_WRITE;
1060

1061
			cond_resched();
1062
			while (!(page = follow_page(vma, start, foll_flags))) {
1063 1064 1065
				int ret;
				ret = __handle_mm_fault(mm, vma, start,
						foll_flags & FOLL_WRITE);
1066 1067 1068 1069 1070 1071 1072
				/*
				 * The VM_FAULT_WRITE bit tells us that do_wp_page has
				 * broken COW when necessary, even if maybe_mkwrite
				 * decided not to set pte_write. We can thus safely do
				 * subsequent page lookups as if they were reads.
				 */
				if (ret & VM_FAULT_WRITE)
1073
					foll_flags &= ~FOLL_WRITE;
1074 1075
				
				switch (ret & ~VM_FAULT_WRITE) {
L
Linus Torvalds 已提交
1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088
				case VM_FAULT_MINOR:
					tsk->min_flt++;
					break;
				case VM_FAULT_MAJOR:
					tsk->maj_flt++;
					break;
				case VM_FAULT_SIGBUS:
					return i ? i : -EFAULT;
				case VM_FAULT_OOM:
					return i ? i : -ENOMEM;
				default:
					BUG();
				}
1089
				cond_resched();
L
Linus Torvalds 已提交
1090 1091
			}
			if (pages) {
1092
				pages[i] = page;
1093

1094
				flush_anon_page(vma, page, start);
1095
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1096 1097 1098 1099 1100 1101
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1102 1103
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1104 1105 1106 1107 1108 1109 1110 1111
	return i;
}
EXPORT_SYMBOL(get_user_pages);

static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pte_t *pte;
H
Hugh Dickins 已提交
1112
	spinlock_t *ptl;
1113
	int err = 0;
L
Linus Torvalds 已提交
1114

H
Hugh Dickins 已提交
1115
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1116
	if (!pte)
1117
		return -EAGAIN;
1118
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1119
	do {
N
Nick Piggin 已提交
1120 1121
		struct page *page = ZERO_PAGE(addr);
		pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1122 1123 1124 1125 1126 1127

		if (unlikely(!pte_none(*pte))) {
			err = -EEXIST;
			pte++;
			break;
		}
N
Nick Piggin 已提交
1128 1129 1130
		page_cache_get(page);
		page_add_file_rmap(page);
		inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
1131 1132
		set_pte_at(mm, addr, pte, zero_pte);
	} while (pte++, addr += PAGE_SIZE, addr != end);
1133
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1134
	pte_unmap_unlock(pte - 1, ptl);
1135
	return err;
L
Linus Torvalds 已提交
1136 1137 1138 1139 1140 1141 1142
}

static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pmd_t *pmd;
	unsigned long next;
1143
	int err;
L
Linus Torvalds 已提交
1144 1145 1146

	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
1147
		return -EAGAIN;
L
Linus Torvalds 已提交
1148 1149
	do {
		next = pmd_addr_end(addr, end);
1150 1151 1152
		err = zeromap_pte_range(mm, pmd, addr, next, prot);
		if (err)
			break;
L
Linus Torvalds 已提交
1153
	} while (pmd++, addr = next, addr != end);
1154
	return err;
L
Linus Torvalds 已提交
1155 1156 1157 1158 1159 1160 1161
}

static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pud_t *pud;
	unsigned long next;
1162
	int err;
L
Linus Torvalds 已提交
1163 1164 1165

	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
1166
		return -EAGAIN;
L
Linus Torvalds 已提交
1167 1168
	do {
		next = pud_addr_end(addr, end);
1169 1170 1171
		err = zeromap_pmd_range(mm, pud, addr, next, prot);
		if (err)
			break;
L
Linus Torvalds 已提交
1172
	} while (pud++, addr = next, addr != end);
1173
	return err;
L
Linus Torvalds 已提交
1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196
}

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

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

1197
pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1198 1199 1200 1201
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1202
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1203 1204 1205 1206 1207 1208
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1209 1210 1211 1212 1213 1214 1215 1216 1217 1218
/*
 * 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;
1219
	pte_t *pte;
1220 1221 1222
	spinlock_t *ptl;  

	retval = -EINVAL;
1223
	if (PageAnon(page))
1224 1225 1226
		goto out;
	retval = -ENOMEM;
	flush_dcache_page(page);
1227
	pte = get_locked_pte(mm, addr, &ptl);
1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246
	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;
}

1247 1248 1249 1250 1251 1252
/**
 * 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
 *
1253 1254 1255 1256 1257 1258
 * 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
1259
 * (see split_page()).
1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274
 *
 * 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;
1275
	vma->vm_flags |= VM_INSERTPAGE;
1276 1277
	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
1278
EXPORT_SYMBOL(vm_insert_page);
1279

L
Linus Torvalds 已提交
1280 1281 1282 1283 1284 1285 1286 1287 1288 1289
/*
 * 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
1290
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1291

H
Hugh Dickins 已提交
1292
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1293 1294
	if (!pte)
		return -ENOMEM;
1295
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1296 1297
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1298
		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
L
Linus Torvalds 已提交
1299 1300
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1301
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1302
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345
	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;
}

1346 1347 1348 1349 1350 1351 1352 1353 1354 1355
/**
 * 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
1356 1357 1358 1359 1360
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;
1361
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1362 1363 1364 1365 1366 1367 1368 1369
	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
1370 1371 1372 1373 1374
	 *   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.
1375 1376 1377
	 *   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
1378 1379 1380 1381
	 *
	 * 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
1382
	 */
1383
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1384
		if (addr != vma->vm_start || end != vma->vm_end)
1385
			return -EINVAL;
L
Linus Torvalds 已提交
1386 1387 1388
		vma->vm_pgoff = pfn;
	}

1389
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405

	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);

1406 1407 1408 1409 1410 1411 1412 1413 1414
/*
 * 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
1415
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1416 1417 1418 1419 1420
				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
1421 1422
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1423
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1424
		spin_unlock(ptl);
1425 1426 1427 1428 1429 1430
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443
/*
 * 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;
}

1444
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1445 1446 1447 1448 1449 1450 1451 1452 1453
{
	/*
	 * 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
1454 1455 1456 1457 1458 1459 1460 1461 1462
		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))
1463 1464
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1465
		flush_dcache_page(dst);
1466
		return;
1467

1468
	}
1469
	copy_user_highpage(dst, src, va, vma);
1470 1471
}

L
Linus Torvalds 已提交
1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485
/*
 * 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.
 *
1486 1487 1488
 * 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
1489
 */
1490 1491
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1492
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1493
{
1494
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1495
	pte_t entry;
1496 1497
	int reuse = 0, ret = VM_FAULT_MINOR;
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1498

1499 1500 1501
	old_page = vm_normal_page(vma, address, orig_pte);
	if (!old_page)
		goto gotten;
L
Linus Torvalds 已提交
1502

1503
	/*
P
Peter Zijlstra 已提交
1504 1505
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1506
	 */
P
Peter Zijlstra 已提交
1507 1508 1509 1510 1511 1512
	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)) ==
1513
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1514 1515 1516 1517 1518
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
			/*
			 * Notify the address space that the page is about to
			 * become writable so that it can prohibit this or wait
			 * for the page to get into an appropriate state.
			 *
			 * We do this without the lock held, so that it can
			 * sleep if it needs to.
			 */
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);

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

			page_cache_release(old_page);

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
L
Linus Torvalds 已提交
1546
		}
1547 1548
		dirty_page = old_page;
		get_page(dirty_page);
1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560
		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);
		ptep_set_access_flags(vma, address, page_table, entry, 1);
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(entry);
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1561 1562 1563 1564 1565
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1566
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1567
gotten:
1568
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1569 1570

	if (unlikely(anon_vma_prepare(vma)))
1571
		goto oom;
1572
	if (old_page == ZERO_PAGE(address)) {
L
Linus Torvalds 已提交
1573 1574
		new_page = alloc_zeroed_user_highpage(vma, address);
		if (!new_page)
1575
			goto oom;
L
Linus Torvalds 已提交
1576 1577 1578
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
		if (!new_page)
1579
			goto oom;
1580
		cow_user_page(new_page, old_page, address, vma);
L
Linus Torvalds 已提交
1581
	}
1582

L
Linus Torvalds 已提交
1583 1584 1585
	/*
	 * Re-check the pte - we dropped the lock
	 */
1586
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1587
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1588
		if (old_page) {
N
Nick Piggin 已提交
1589
			page_remove_rmap(old_page, vma);
H
Hugh Dickins 已提交
1590 1591 1592 1593 1594
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1595
			inc_mm_counter(mm, anon_rss);
1596
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1597 1598
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1599
		lazy_mmu_prot_update(entry);
1600 1601 1602 1603 1604 1605 1606 1607
		/*
		 * 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);
1608
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1609
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1610
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1611 1612 1613

		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1614
		ret |= VM_FAULT_WRITE;
L
Linus Torvalds 已提交
1615
	}
H
Hugh Dickins 已提交
1616 1617 1618 1619
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1620
unlock:
1621
	pte_unmap_unlock(page_table, ptl);
1622
	if (dirty_page) {
P
Peter Zijlstra 已提交
1623
		set_page_dirty_balance(dirty_page);
1624 1625
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1626
	return ret;
1627
oom:
H
Hugh Dickins 已提交
1628 1629
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1630
	return VM_FAULT_OOM;
1631 1632 1633 1634

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661
}

/*
 * 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
1662
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699
 * and restart from that address when we reach that vma again.  It might
 * have been split or merged, shrunk or extended, but never shifted: so
 * restart_addr remains valid so long as it remains in the vma's range.
 * unmap_mapping_range forces truncate_count to leap over page-aligned
 * values so we can save vma's restart_addr in its truncate_count field.
 */
#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))

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

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

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

again:
	restart_addr = vma->vm_truncate_count;
	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
		start_addr = restart_addr;
		if (start_addr >= end_addr) {
			/* Top of vma has been split off since last time */
			vma->vm_truncate_count = details->truncate_count;
			return 0;
		}
	}

1700 1701
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
L
Linus Torvalds 已提交
1702 1703 1704
	need_break = need_resched() ||
			need_lockbreak(details->i_mmap_lock);

1705
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1706 1707 1708 1709 1710 1711
		/* 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 */
1712
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 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 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781
		if (!need_break)
			goto again;
	}

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

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

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

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

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

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

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

/**
 * unmap_mapping_range - unmap the portion of all mmaps
 * in the specified address_space corresponding to the specified
 * page range in the underlying file.
M
Martin Waitz 已提交
1782
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
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
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
 * boundary.  Note that this is different from vmtruncate(), which
 * must keep the partial page.  In contrast, we must get rid of
 * partial pages.
 * @holelen: size of prospective hole in bytes.  This will be rounded
 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
 * end of the file.
 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
 * but 0 when invalidating pagecache, don't throw away private data.
 */
void unmap_mapping_range(struct address_space *mapping,
		loff_t const holebegin, loff_t const holelen, int even_cows)
{
	struct zap_details details;
	pgoff_t hba = holebegin >> PAGE_SHIFT;
	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;

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

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

	spin_lock(&mapping->i_mmap_lock);

	/* serialize i_size write against truncate_count write */
	smp_wmb();
	/* Protect against page faults, and endless unmapping loops */
	mapping->truncate_count++;
	/*
	 * For archs where spin_lock has inclusive semantics like ia64
	 * this smp_mb() will prevent to read pagetable contents
	 * before the truncate_count increment is visible to
	 * other cpus.
	 */
	smp_mb();
	if (unlikely(is_restart_addr(mapping->truncate_count))) {
		if (mapping->truncate_count == 0)
			reset_vma_truncate_counts(mapping);
		mapping->truncate_count++;
	}
	details.truncate_count = mapping->truncate_count;

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

1845 1846 1847 1848
/**
 * 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
1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode * inode, loff_t offset)
{
	struct address_space *mapping = inode->i_mapping;
	unsigned long limit;

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

do_expand:
	limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
	if (limit != RLIM_INFINITY && offset > limit)
		goto out_sig;
	if (offset > inode->i_sb->s_maxbytes)
		goto out_big;
	i_size_write(inode, offset);

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

1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904
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;

1905
	mutex_lock(&inode->i_mutex);
1906 1907 1908 1909 1910
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
1911
	mutex_unlock(&inode->i_mutex);
1912 1913 1914 1915

	return 0;
}

1916 1917 1918 1919 1920 1921
/**
 * swapin_readahead - swap in pages in hope we need them soon
 * @entry: swap entry of this memory
 * @addr: address to start
 * @vma: user vma this addresses belong to
 *
L
Linus Torvalds 已提交
1922 1923 1924
 * Primitive swap readahead code. We simply read an aligned block of
 * (1 << page_cluster) entries in the swap area. This method is chosen
 * because it doesn't cost us any seek time.  We also make sure to queue
1925
 * the 'original' request together with the readahead ones...
L
Linus Torvalds 已提交
1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977
 *
 * This has been extended to use the NUMA policies from the mm triggering
 * the readahead.
 *
 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
 */
void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
{
#ifdef CONFIG_NUMA
	struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
#endif
	int i, num;
	struct page *new_page;
	unsigned long offset;

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

/*
1978 1979 1980
 * 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
1981
 */
1982 1983 1984
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
1985
{
1986
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1987
	struct page *page;
1988
	swp_entry_t entry;
L
Linus Torvalds 已提交
1989 1990 1991
	pte_t pte;
	int ret = VM_FAULT_MINOR;

H
Hugh Dickins 已提交
1992
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1993
		goto out;
1994 1995

	entry = pte_to_swp_entry(orig_pte);
1996 1997 1998 1999
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2000
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2001 2002
	page = lookup_swap_cache(entry);
	if (!page) {
2003
		grab_swap_token(); /* Contend for token _before_ read-in */
L
Linus Torvalds 已提交
2004 2005 2006 2007
 		swapin_readahead(entry, address, vma);
 		page = read_swap_cache_async(entry, vma, address);
		if (!page) {
			/*
2008 2009
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2010
			 */
2011
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2012 2013
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2014
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2015
			goto unlock;
L
Linus Torvalds 已提交
2016 2017 2018 2019
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2020
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2021 2022
	}

2023
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2024 2025 2026 2027
	mark_page_accessed(page);
	lock_page(page);

	/*
2028
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2029
	 */
2030
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2031
	if (unlikely(!pte_same(*page_table, orig_pte)))
2032 2033 2034 2035 2036
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2037 2038 2039 2040
	}

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

2041
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2042 2043 2044 2045 2046 2047 2048 2049 2050 2051
	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);

2052 2053 2054 2055 2056
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2057 2058
	if (write_access) {
		if (do_wp_page(mm, vma, address,
2059
				page_table, pmd, ptl, pte) == VM_FAULT_OOM)
L
Linus Torvalds 已提交
2060 2061 2062 2063 2064 2065 2066
			ret = VM_FAULT_OOM;
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
	lazy_mmu_prot_update(pte);
2067
unlock:
2068
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2069 2070
out:
	return ret;
2071
out_nomap:
2072
	pte_unmap_unlock(page_table, ptl);
2073 2074
	unlock_page(page);
	page_cache_release(page);
2075
	return ret;
L
Linus Torvalds 已提交
2076 2077 2078
}

/*
2079 2080 2081
 * 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
2082
 */
2083 2084 2085
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
2086
{
2087 2088
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2089 2090
	pte_t entry;

2091
	if (write_access) {
L
Linus Torvalds 已提交
2092 2093 2094 2095
		/* Allocate our own private page. */
		pte_unmap(page_table);

		if (unlikely(anon_vma_prepare(vma)))
2096 2097
			goto oom;
		page = alloc_zeroed_user_highpage(vma, address);
L
Linus Torvalds 已提交
2098
		if (!page)
2099
			goto oom;
L
Linus Torvalds 已提交
2100

2101 2102
		entry = mk_pte(page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2103 2104 2105 2106 2107

		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
		if (!pte_none(*page_table))
			goto release;
		inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2108
		lru_cache_add_active(page);
N
Nick Piggin 已提交
2109
		page_add_new_anon_rmap(page, vma, address);
N
Nick Piggin 已提交
2110
	} else {
2111 2112 2113 2114 2115
		/* Map the ZERO_PAGE - vm_page_prot is readonly */
		page = ZERO_PAGE(address);
		page_cache_get(page);
		entry = mk_pte(page, vma->vm_page_prot);

H
Hugh Dickins 已提交
2116
		ptl = pte_lockptr(mm, pmd);
2117 2118 2119
		spin_lock(ptl);
		if (!pte_none(*page_table))
			goto release;
N
Nick Piggin 已提交
2120 2121
		inc_mm_counter(mm, file_rss);
		page_add_file_rmap(page);
L
Linus Torvalds 已提交
2122 2123
	}

2124
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2125 2126

	/* No need to invalidate - it was non-present before */
2127
	update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2128
	lazy_mmu_prot_update(entry);
2129
unlock:
2130
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2131
	return VM_FAULT_MINOR;
2132 2133 2134
release:
	page_cache_release(page);
	goto unlock;
2135
oom:
L
Linus Torvalds 已提交
2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147
	return VM_FAULT_OOM;
}

/*
 * do_no_page() tries to create a new page mapping. It aggressively
 * tries to share with existing pages, but makes a separate copy if
 * the "write_access" parameter is true in order to avoid the next
 * page fault.
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2148 2149 2150
 * 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
2151
 */
2152 2153 2154
static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access)
L
Linus Torvalds 已提交
2155
{
2156
	spinlock_t *ptl;
2157
	struct page *new_page;
L
Linus Torvalds 已提交
2158 2159 2160 2161 2162
	struct address_space *mapping = NULL;
	pte_t entry;
	unsigned int sequence = 0;
	int ret = VM_FAULT_MINOR;
	int anon = 0;
2163
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2164 2165

	pte_unmap(page_table);
2166 2167
	BUG_ON(vma->vm_flags & VM_PFNMAP);

L
Linus Torvalds 已提交
2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;
		sequence = mapping->truncate_count;
		smp_rmb(); /* serializes i_size against truncate_count */
	}
retry:
	new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
	/*
	 * No smp_rmb is needed here as long as there's a full
	 * spin_lock/unlock sequence inside the ->nopage callback
	 * (for the pagecache lookup) that acts as an implicit
	 * smp_mb() and prevents the i_size read to happen
	 * after the next truncate_count read.
	 */

2183 2184
	/* no page was available -- either SIGBUS, OOM or REFAULT */
	if (unlikely(new_page == NOPAGE_SIGBUS))
L
Linus Torvalds 已提交
2185
		return VM_FAULT_SIGBUS;
2186
	else if (unlikely(new_page == NOPAGE_OOM))
L
Linus Torvalds 已提交
2187
		return VM_FAULT_OOM;
2188 2189
	else if (unlikely(new_page == NOPAGE_REFAULT))
		return VM_FAULT_MINOR;
L
Linus Torvalds 已提交
2190 2191 2192 2193

	/*
	 * Should we do an early C-O-W break?
	 */
2194 2195 2196
	if (write_access) {
		if (!(vma->vm_flags & VM_SHARED)) {
			struct page *page;
L
Linus Torvalds 已提交
2197

2198 2199 2200 2201 2202
			if (unlikely(anon_vma_prepare(vma)))
				goto oom;
			page = alloc_page_vma(GFP_HIGHUSER, vma, address);
			if (!page)
				goto oom;
2203
			copy_user_highpage(page, new_page, address, vma);
2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218
			page_cache_release(new_page);
			new_page = page;
			anon = 1;

		} else {
			/* if the page will be shareable, see if the backing
			 * address space wants to know that the page is about
			 * to become writable */
			if (vma->vm_ops->page_mkwrite &&
			    vma->vm_ops->page_mkwrite(vma, new_page) < 0
			    ) {
				page_cache_release(new_page);
				return VM_FAULT_SIGBUS;
			}
		}
L
Linus Torvalds 已提交
2219 2220
	}

2221
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2222 2223 2224 2225 2226 2227
	/*
	 * For a file-backed vma, someone could have truncated or otherwise
	 * invalidated this page.  If unmap_mapping_range got called,
	 * retry getting the page.
	 */
	if (mapping && unlikely(sequence != mapping->truncate_count)) {
2228
		pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2229
		page_cache_release(new_page);
2230 2231 2232
		cond_resched();
		sequence = mapping->truncate_count;
		smp_rmb();
L
Linus Torvalds 已提交
2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253
		goto retry;
	}

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
	 * Note that if write_access is true, we either now have
	 * an exclusive copy of the page, or this is a shared mapping,
	 * so we can make it writable and dirty to avoid having to
	 * handle that later.
	 */
	/* Only go through if we didn't race with anybody else... */
	if (pte_none(*page_table)) {
		flush_icache_page(vma, new_page);
		entry = mk_pte(new_page, vma->vm_page_prot);
		if (write_access)
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2254
			inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2255
			lru_cache_add_active(new_page);
N
Nick Piggin 已提交
2256
			page_add_new_anon_rmap(new_page, vma, address);
2257
		} else {
2258
			inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
2259
			page_add_file_rmap(new_page);
2260 2261 2262 2263
			if (write_access) {
				dirty_page = new_page;
				get_page(dirty_page);
			}
2264
		}
L
Linus Torvalds 已提交
2265 2266 2267
	} else {
		/* One of our sibling threads was faster, back out. */
		page_cache_release(new_page);
2268
		goto unlock;
L
Linus Torvalds 已提交
2269 2270 2271 2272 2273
	}

	/* no need to invalidate: a not-present page shouldn't be cached */
	update_mmu_cache(vma, address, entry);
	lazy_mmu_prot_update(entry);
2274
unlock:
2275
	pte_unmap_unlock(page_table, ptl);
2276
	if (dirty_page) {
P
Peter Zijlstra 已提交
2277
		set_page_dirty_balance(dirty_page);
2278 2279
		put_page(dirty_page);
	}
L
Linus Torvalds 已提交
2280 2281 2282
	return ret;
oom:
	page_cache_release(new_page);
2283
	return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2284 2285
}

J
Jes Sorensen 已提交
2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333
/*
 * 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;
	int ret = VM_FAULT_MINOR;

	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);
	if (pfn == NOPFN_OOM)
		return VM_FAULT_OOM;
	if (pfn == NOPFN_SIGBUS)
		return VM_FAULT_SIGBUS;

	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);
	return ret;
}

L
Linus Torvalds 已提交
2334 2335 2336 2337
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2338 2339 2340 2341
 *
 * 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
2342
 */
2343 2344 2345
static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2346
{
2347
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2348 2349
	int err;

H
Hugh Dickins 已提交
2350
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2351
		return VM_FAULT_MINOR;
L
Linus Torvalds 已提交
2352

2353 2354 2355 2356
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2357
		print_bad_pte(vma, orig_pte, address);
2358 2359 2360 2361 2362 2363 2364
		return VM_FAULT_OOM;
	}
	/* We can then assume vm->vm_ops && vma->vm_ops->populate */

	pgoff = pte_to_pgoff(orig_pte);
	err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
					vma->vm_page_prot, pgoff, 0);
L
Linus Torvalds 已提交
2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380
	if (err == -ENOMEM)
		return VM_FAULT_OOM;
	if (err)
		return VM_FAULT_SIGBUS;
	return VM_FAULT_MAJOR;
}

/*
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 *
H
Hugh Dickins 已提交
2381 2382 2383
 * 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
2384 2385
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2386 2387
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2388 2389
{
	pte_t entry;
2390
	pte_t old_entry;
2391
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2392

2393
	old_entry = entry = *pte;
L
Linus Torvalds 已提交
2394
	if (!pte_present(entry)) {
2395
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406
			if (vma->vm_ops) {
				if (vma->vm_ops->nopage)
					return do_no_page(mm, vma, address,
							  pte, pmd,
							  write_access);
				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);
2407
		}
L
Linus Torvalds 已提交
2408
		if (pte_file(entry))
2409 2410 2411 2412
			return do_file_page(mm, vma, address,
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2413 2414
	}

H
Hugh Dickins 已提交
2415
	ptl = pte_lockptr(mm, pmd);
2416 2417 2418
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2419 2420
	if (write_access) {
		if (!pte_write(entry))
2421 2422
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2423 2424 2425
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439
	if (!pte_same(old_entry, entry)) {
		ptep_set_access_flags(vma, address, pte, entry, write_access);
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2440 2441
unlock:
	pte_unmap_unlock(pte, ptl);
L
Linus Torvalds 已提交
2442 2443 2444 2445 2446 2447
	return VM_FAULT_MINOR;
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
2448
int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2449 2450 2451 2452 2453 2454 2455 2456 2457
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2458
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2459

2460 2461
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2462 2463 2464 2465

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2466
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2467 2468
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2469
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2470 2471
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2472
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2473

H
Hugh Dickins 已提交
2474
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2475 2476
}

2477 2478
EXPORT_SYMBOL_GPL(__handle_mm_fault);

L
Linus Torvalds 已提交
2479 2480 2481
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2482
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2483
 */
2484
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2485
{
H
Hugh Dickins 已提交
2486 2487
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2488
		return -ENOMEM;
L
Linus Torvalds 已提交
2489

H
Hugh Dickins 已提交
2490
	spin_lock(&mm->page_table_lock);
2491
	if (pgd_present(*pgd))		/* Another has populated it */
L
Linus Torvalds 已提交
2492
		pud_free(new);
2493 2494
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2495
	spin_unlock(&mm->page_table_lock);
2496
	return 0;
L
Linus Torvalds 已提交
2497
}
2498 2499 2500 2501 2502 2503
#else
/* Workaround for gcc 2.96 */
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
	return 0;
}
L
Linus Torvalds 已提交
2504 2505 2506 2507 2508
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2509
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2510
 */
2511
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2512
{
H
Hugh Dickins 已提交
2513 2514
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2515
		return -ENOMEM;
L
Linus Torvalds 已提交
2516

H
Hugh Dickins 已提交
2517
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2518
#ifndef __ARCH_HAS_4LEVEL_HACK
2519
	if (pud_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2520
		pmd_free(new);
2521 2522
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2523
#else
2524
	if (pgd_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2525
		pmd_free(new);
2526 2527
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2528
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2529
	spin_unlock(&mm->page_table_lock);
2530
	return 0;
2531 2532 2533 2534 2535 2536
}
#else
/* Workaround for gcc 2.96 */
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
	return 0;
L
Linus Torvalds 已提交
2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548
}
#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;
2549 2550
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
L
Linus Torvalds 已提交
2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601
	len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
	if (ret < 0)
		return ret;
	return ret == len ? 0 : -1;
}

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

EXPORT_SYMBOL(vmalloc_to_page);

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

EXPORT_SYMBOL(vmalloc_to_pfn);

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2602
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2603 2604 2605 2606 2607 2608

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
2609 2610
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2611 2612 2613 2614 2615 2616 2617
	/*
	 * Make sure the vDSO gets into every core dump.
	 * Dumping its contents makes post-mortem fully interpretable later
	 * without matching up the same kernel and hardware config to see
	 * what PC values meant.
	 */
	gate_vma.vm_flags |= VM_ALWAYSDUMP;
L
Linus Torvalds 已提交
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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);
	/* ignore errors, just check how much was sucessfully transfered */
	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;
}