memory.c 71.0 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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	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
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		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
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			    need_lockbreak(src_ptl) ||
			    need_lockbreak(dst_ptl))
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				break;
		}
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		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
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		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
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		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

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

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

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

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

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

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

592 593 594 595 596 597
	/*
	 * 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.
	 */
598
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
599 600 601 602
		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;
}

619
static unsigned long zap_pte_range(struct mmu_gather *tlb,
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				struct vm_area_struct *vma, pmd_t *pmd,
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				unsigned long addr, unsigned long end,
622
				long *zap_work, struct zap_details *details)
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{
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	struct mm_struct *mm = tlb->mm;
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	pte_t *pte;
626
	spinlock_t *ptl;
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	int file_rss = 0;
	int anon_rss = 0;
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630
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
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	do {
		pte_t ptent = *pte;
633 634
		if (pte_none(ptent)) {
			(*zap_work)--;
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			continue;
636
		}
637 638 639

		(*zap_work) -= PAGE_SIZE;

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		if (pte_present(ptent)) {
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			struct page *page;
642

643
			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,
663
							tlb->fullmm);
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			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (unlikely(details) && details->nonlinear_vma
			    && linear_page_index(details->nonlinear_vma,
						addr) != page->index)
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				set_pte_at(mm, addr, pte,
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					   pgoff_to_pte(page->index));
			if (PageAnon(page))
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				anon_rss--;
674 675 676 677 678
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
					mark_page_accessed(page);
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				file_rss--;
680
			}
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			page_remove_rmap(page);
			tlb_remove_page(tlb, page);
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
		if (!pte_file(ptent))
			free_swap_and_cache(pte_to_swp_entry(ptent));
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		pte_clear_full(mm, addr, pte, tlb->fullmm);
694
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
695

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	add_mm_rss(mm, file_rss, anon_rss);
697
	pte_unmap_unlock(pte - 1, ptl);
698 699

	return addr;
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}

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

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
713 714
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
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			continue;
716 717 718 719 720 721
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
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}

724
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
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				struct vm_area_struct *vma, pgd_t *pgd,
L
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				unsigned long addr, unsigned long end,
727
				long *zap_work, struct zap_details *details)
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{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
735 736
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
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			continue;
738 739 740 741 742 743
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
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}

746 747
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
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				unsigned long addr, unsigned long end,
749
				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);
762 763
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
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			continue;
765 766 767 768
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
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	tlb_end_vma(tlb, vma);
770 771

	return addr;
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}

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

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
 * @tlbp: address of the caller's struct mmu_gather
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 * @details: details of nonlinear truncation or shared cache invalidation
 *
790
 * Returns the end address of the unmapping (restart addr if interrupted).
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 *
792
 * Unmap all pages in the vma list.
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 *
794 795
 * We aim to not hold locks for too long (for scheduling latency reasons).
 * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
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 * return the ending mmu_gather to the caller.
 *
 * Only addresses between `start' and `end' will be unmapped.
 *
 * The VMA list must be sorted in ascending virtual address order.
 *
 * unmap_vmas() assumes that the caller will flush the whole unmapped address
 * range after unmap_vmas() returns.  So the only responsibility here is to
 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 * drops the lock and schedules.
 */
807
unsigned long unmap_vmas(struct mmu_gather **tlbp,
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		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
812
	long zap_work = ZAP_BLOCK_SIZE;
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	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
815
	unsigned long start = start_addr;
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	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
817
	int fullmm = (*tlbp)->fullmm;
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	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
		unsigned long end;

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

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

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

838
			if (unlikely(is_vm_hugetlb_page(vma))) {
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				unmap_hugepage_range(vma, start, end);
840 841 842 843 844 845 846 847 848 849
				zap_work -= (end - start) /
						(HPAGE_SIZE / PAGE_SIZE);
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

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

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
				(i_mmap_lock && need_lockbreak(i_mmap_lock))) {
				if (i_mmap_lock) {
857
					*tlbp = NULL;
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					goto out;
				}
				cond_resched();
			}

863
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
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			tlb_start_valid = 0;
865
			zap_work = ZAP_BLOCK_SIZE;
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		}
	}
out:
869
	return start;	/* which is now the end (or restart) address */
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}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
 */
879
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
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		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
	struct mmu_gather *tlb;
	unsigned long end = address + size;
	unsigned long nr_accounted = 0;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
889
	update_hiwater_rss(mm);
890 891 892
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
893
	return end;
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}

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

	if (pmd_huge(*pmd)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
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		goto out;
933
	}
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935
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
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	if (!ptep)
		goto out;

	pte = *ptep;
940 941 942 943
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
944 945
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
946
		goto unlock;
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948 949 950 951 952 953 954 955 956 957
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
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out:
959
	return page;
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961 962 963 964 965 966 967 968 969 970 971 972
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;
980
	unsigned int vm_flags;
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	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
986 987
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
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	i = 0;

	do {
991 992
		struct vm_area_struct *vma;
		unsigned int foll_flags;
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		vma = find_extend_vma(mm, start);
		if (!vma && in_gate_area(tsk, start)) {
			unsigned long pg = start & PAGE_MASK;
			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
			if (write) /* user gate pages are read-only */
				return i ? : -EFAULT;
			if (pg > TASK_SIZE)
				pgd = pgd_offset_k(pg);
			else
				pgd = pgd_offset_gate(mm, pg);
			BUG_ON(pgd_none(*pgd));
			pud = pud_offset(pgd, pg);
			BUG_ON(pud_none(*pud));
			pmd = pmd_offset(pud, pg);
1012 1013
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
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			pte = pte_offset_map(pmd, pg);
1015 1016 1017 1018
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
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			if (pages) {
1020
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1021 1022 1023
				pages[i] = page;
				if (page)
					get_page(page);
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			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1034
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1035
				|| !(vm_flags & vma->vm_flags))
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			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
						&start, &len, i);
			continue;
		}
1043 1044 1045 1046 1047 1048 1049 1050

		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 {
1052
			struct page *page;
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1054 1055
			if (write)
				foll_flags |= FOLL_WRITE;
1056

1057
			cond_resched();
1058
			while (!(page = follow_page(vma, start, foll_flags))) {
1059 1060 1061
				int ret;
				ret = __handle_mm_fault(mm, vma, start,
						foll_flags & FOLL_WRITE);
1062 1063 1064 1065 1066 1067 1068
				/*
				 * 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)
1069
					foll_flags &= ~FOLL_WRITE;
1070 1071
				
				switch (ret & ~VM_FAULT_WRITE) {
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				case VM_FAULT_MINOR:
					tsk->min_flt++;
					break;
				case VM_FAULT_MAJOR:
					tsk->maj_flt++;
					break;
				case VM_FAULT_SIGBUS:
					return i ? i : -EFAULT;
				case VM_FAULT_OOM:
					return i ? i : -ENOMEM;
				default:
					BUG();
				}
			}
			if (pages) {
1087
				pages[i] = page;
1088 1089

				flush_anon_page(page, start);
1090
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1091 1092 1093 1094 1095 1096
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1097 1098
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1099 1100 1101 1102 1103 1104 1105 1106
	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
1107
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1108

H
Hugh Dickins 已提交
1109
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1110 1111 1112
	if (!pte)
		return -ENOMEM;
	do {
N
Nick Piggin 已提交
1113 1114 1115 1116 1117
		struct page *page = ZERO_PAGE(addr);
		pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
		page_cache_get(page);
		page_add_file_rmap(page);
		inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
1118 1119 1120
		BUG_ON(!pte_none(*pte));
		set_pte_at(mm, addr, pte, zero_pte);
	} while (pte++, addr += PAGE_SIZE, addr != end);
H
Hugh Dickins 已提交
1121
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179
	return 0;
}

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

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

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

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

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

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

1180
pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1181 1182 1183 1184
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1185
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1186 1187 1188 1189 1190 1191
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1192 1193 1194 1195 1196 1197 1198 1199 1200 1201
/*
 * 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;
1202
	pte_t *pte;
1203 1204 1205
	spinlock_t *ptl;  

	retval = -EINVAL;
1206
	if (PageAnon(page))
1207 1208 1209
		goto out;
	retval = -ENOMEM;
	flush_dcache_page(page);
1210
	pte = get_locked_pte(mm, addr, &ptl);
1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229
	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;
}

1230 1231 1232 1233 1234 1235
/**
 * 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
 *
1236 1237 1238 1239 1240 1241
 * 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
1242
 * (see split_page()).
1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257
 *
 * 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;
1258
	vma->vm_flags |= VM_INSERTPAGE;
1259 1260
	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
1261
EXPORT_SYMBOL(vm_insert_page);
1262

L
Linus Torvalds 已提交
1263 1264 1265 1266 1267 1268 1269 1270 1271 1272
/*
 * 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
1273
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1274

H
Hugh Dickins 已提交
1275
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1276 1277 1278 1279
	if (!pte)
		return -ENOMEM;
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1280
		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
L
Linus Torvalds 已提交
1281 1282
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
H
Hugh Dickins 已提交
1283
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326
	return 0;
}

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

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

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

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

1327 1328 1329 1330 1331 1332 1333 1334 1335 1336
/**
 * 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
1337 1338 1339 1340 1341
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;
1342
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1343 1344 1345 1346 1347 1348 1349 1350
	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
1351 1352 1353 1354 1355
	 *   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.
1356 1357 1358
	 *   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
1359 1360 1361 1362
	 *
	 * 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
1363
	 */
1364
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1365
		if (addr != vma->vm_start || end != vma->vm_end)
1366
			return -EINVAL;
L
Linus Torvalds 已提交
1367 1368 1369
		vma->vm_pgoff = pfn;
	}

1370
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386

	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);

1387 1388 1389 1390 1391 1392 1393 1394 1395
/*
 * 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
1396
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1397 1398 1399 1400 1401
				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
1402 1403
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1404
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1405
		spin_unlock(ptl);
1406 1407 1408 1409 1410 1411
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424
/*
 * 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;
}

1425 1426 1427 1428 1429 1430 1431 1432 1433 1434
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
{
	/*
	 * If the source page was a PFN mapping, we don't have
	 * a "struct page" for it. We do a best-effort copy by
	 * just copying from the original user address. If that
	 * fails, we just zero-fill it. Live with it.
	 */
	if (unlikely(!src)) {
		void *kaddr = kmap_atomic(dst, KM_USER0);
L
Linus Torvalds 已提交
1435 1436 1437 1438 1439 1440 1441 1442 1443
		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))
1444 1445 1446 1447 1448 1449 1450 1451
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
		return;
		
	}
	copy_user_highpage(dst, src, va);
}

L
Linus Torvalds 已提交
1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465
/*
 * 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.
 *
1466 1467 1468
 * 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
1469
 */
1470 1471
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1472
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1473
{
1474
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1475
	pte_t entry;
1476 1477
	int reuse = 0, ret = VM_FAULT_MINOR;
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1478

1479 1480 1481
	old_page = vm_normal_page(vma, address, orig_pte);
	if (!old_page)
		goto gotten;
L
Linus Torvalds 已提交
1482

1483
	/*
P
Peter Zijlstra 已提交
1484 1485
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1486
	 */
P
Peter Zijlstra 已提交
1487 1488 1489 1490 1491 1492
	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)) ==
1493
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1494 1495 1496 1497 1498
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525
		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
1526
		}
1527 1528
		dirty_page = old_page;
		get_page(dirty_page);
1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540
		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
1541 1542 1543 1544 1545
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1546
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1547
gotten:
1548
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1549 1550

	if (unlikely(anon_vma_prepare(vma)))
1551
		goto oom;
1552
	if (old_page == ZERO_PAGE(address)) {
L
Linus Torvalds 已提交
1553 1554
		new_page = alloc_zeroed_user_highpage(vma, address);
		if (!new_page)
1555
			goto oom;
L
Linus Torvalds 已提交
1556 1557 1558
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
		if (!new_page)
1559
			goto oom;
1560
		cow_user_page(new_page, old_page, address);
L
Linus Torvalds 已提交
1561
	}
1562

L
Linus Torvalds 已提交
1563 1564 1565
	/*
	 * Re-check the pte - we dropped the lock
	 */
1566
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1567
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1568 1569 1570 1571 1572 1573 1574
		if (old_page) {
			page_remove_rmap(old_page);
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1575
			inc_mm_counter(mm, anon_rss);
1576
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1577 1578
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1579
		lazy_mmu_prot_update(entry);
1580 1581 1582 1583 1584 1585 1586 1587
		/*
		 * 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);
1588
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1589
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1590
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1591 1592 1593

		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1594
		ret |= VM_FAULT_WRITE;
L
Linus Torvalds 已提交
1595
	}
H
Hugh Dickins 已提交
1596 1597 1598 1599
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1600
unlock:
1601
	pte_unmap_unlock(page_table, ptl);
1602
	if (dirty_page) {
P
Peter Zijlstra 已提交
1603
		set_page_dirty_balance(dirty_page);
1604 1605
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1606
	return ret;
1607
oom:
H
Hugh Dickins 已提交
1608 1609
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1610
	return VM_FAULT_OOM;
1611 1612 1613 1614

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641
}

/*
 * 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
1642
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679
 * 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;
		}
	}

1680 1681
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
L
Linus Torvalds 已提交
1682 1683 1684
	need_break = need_resched() ||
			need_lockbreak(details->i_mmap_lock);

1685
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1686 1687 1688 1689 1690 1691
		/* 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 */
1692
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 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
		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
1762
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824
 * @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);

1825 1826 1827 1828
/**
 * 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
1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872
 *
 * 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);

1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884
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;

1885
	mutex_lock(&inode->i_mutex);
1886 1887 1888 1889 1890
	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);
1891
	mutex_unlock(&inode->i_mutex);
1892 1893 1894

	return 0;
}
1895
EXPORT_UNUSED_SYMBOL(vmtruncate_range);  /*  June 2006  */
1896

1897 1898 1899 1900 1901 1902
/**
 * 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
1903 1904 1905
 * 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
1906
 * the 'original' request together with the readahead ones...
L
Linus Torvalds 已提交
1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958
 *
 * 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 */
}

/*
1959 1960 1961
 * 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
1962
 */
1963 1964 1965
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
1966
{
1967
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1968
	struct page *page;
1969
	swp_entry_t entry;
L
Linus Torvalds 已提交
1970 1971 1972
	pte_t pte;
	int ret = VM_FAULT_MINOR;

H
Hugh Dickins 已提交
1973
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1974
		goto out;
1975 1976

	entry = pte_to_swp_entry(orig_pte);
1977 1978 1979 1980
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
1981
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
1982 1983 1984 1985 1986 1987
	page = lookup_swap_cache(entry);
	if (!page) {
 		swapin_readahead(entry, address, vma);
 		page = read_swap_cache_async(entry, vma, address);
		if (!page) {
			/*
1988 1989
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
1990
			 */
1991
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1992 1993
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
1994
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
1995
			goto unlock;
L
Linus Torvalds 已提交
1996 1997 1998 1999
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2000
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2001 2002 2003
		grab_swap_token();
	}

2004
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2005 2006 2007 2008
	mark_page_accessed(page);
	lock_page(page);

	/*
2009
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2010
	 */
2011
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2012
	if (unlikely(!pte_same(*page_table, orig_pte)))
2013 2014 2015 2016 2017
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2018 2019 2020 2021
	}

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

2022
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2023 2024 2025 2026 2027 2028 2029 2030 2031 2032
	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);

2033 2034 2035 2036 2037
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2038 2039
	if (write_access) {
		if (do_wp_page(mm, vma, address,
2040
				page_table, pmd, ptl, pte) == VM_FAULT_OOM)
L
Linus Torvalds 已提交
2041 2042 2043 2044 2045 2046 2047
			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);
2048
unlock:
2049
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2050 2051
out:
	return ret;
2052
out_nomap:
2053
	pte_unmap_unlock(page_table, ptl);
2054 2055
	unlock_page(page);
	page_cache_release(page);
2056
	return ret;
L
Linus Torvalds 已提交
2057 2058 2059
}

/*
2060 2061 2062
 * 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
2063
 */
2064 2065 2066
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
2067
{
2068 2069
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2070 2071
	pte_t entry;

2072
	if (write_access) {
L
Linus Torvalds 已提交
2073 2074 2075 2076
		/* Allocate our own private page. */
		pte_unmap(page_table);

		if (unlikely(anon_vma_prepare(vma)))
2077 2078
			goto oom;
		page = alloc_zeroed_user_highpage(vma, address);
L
Linus Torvalds 已提交
2079
		if (!page)
2080
			goto oom;
L
Linus Torvalds 已提交
2081

2082 2083
		entry = mk_pte(page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2084 2085 2086 2087 2088

		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
2089
		lru_cache_add_active(page);
N
Nick Piggin 已提交
2090
		page_add_new_anon_rmap(page, vma, address);
N
Nick Piggin 已提交
2091
	} else {
2092 2093 2094 2095 2096
		/* 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
2097
		ptl = pte_lockptr(mm, pmd);
2098 2099 2100
		spin_lock(ptl);
		if (!pte_none(*page_table))
			goto release;
N
Nick Piggin 已提交
2101 2102
		inc_mm_counter(mm, file_rss);
		page_add_file_rmap(page);
L
Linus Torvalds 已提交
2103 2104
	}

2105
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2106 2107

	/* No need to invalidate - it was non-present before */
2108
	update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2109
	lazy_mmu_prot_update(entry);
2110
unlock:
2111
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2112
	return VM_FAULT_MINOR;
2113 2114 2115
release:
	page_cache_release(page);
	goto unlock;
2116
oom:
L
Linus Torvalds 已提交
2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128
	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.
 *
2129 2130 2131
 * 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
2132
 */
2133 2134 2135
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
2136
{
2137
	spinlock_t *ptl;
2138
	struct page *new_page;
L
Linus Torvalds 已提交
2139 2140 2141 2142 2143
	struct address_space *mapping = NULL;
	pte_t entry;
	unsigned int sequence = 0;
	int ret = VM_FAULT_MINOR;
	int anon = 0;
2144
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2145 2146

	pte_unmap(page_table);
2147 2148
	BUG_ON(vma->vm_flags & VM_PFNMAP);

L
Linus Torvalds 已提交
2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;
		sequence = mapping->truncate_count;
		smp_rmb(); /* serializes i_size against truncate_count */
	}
retry:
	new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
	/*
	 * No smp_rmb is needed here as long as there's a full
	 * spin_lock/unlock sequence inside the ->nopage callback
	 * (for the pagecache lookup) that acts as an implicit
	 * smp_mb() and prevents the i_size read to happen
	 * after the next truncate_count read.
	 */

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

	/*
	 * Should we do an early C-O-W break?
	 */
2173 2174 2175
	if (write_access) {
		if (!(vma->vm_flags & VM_SHARED)) {
			struct page *page;
L
Linus Torvalds 已提交
2176

2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197
			if (unlikely(anon_vma_prepare(vma)))
				goto oom;
			page = alloc_page_vma(GFP_HIGHUSER, vma, address);
			if (!page)
				goto oom;
			copy_user_highpage(page, new_page, address);
			page_cache_release(new_page);
			new_page = page;
			anon = 1;

		} else {
			/* if the page will be shareable, see if the backing
			 * address space wants to know that the page is about
			 * to become writable */
			if (vma->vm_ops->page_mkwrite &&
			    vma->vm_ops->page_mkwrite(vma, new_page) < 0
			    ) {
				page_cache_release(new_page);
				return VM_FAULT_SIGBUS;
			}
		}
L
Linus Torvalds 已提交
2198 2199
	}

2200
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
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2201 2202 2203 2204 2205 2206
	/*
	 * 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)) {
2207
		pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2208
		page_cache_release(new_page);
2209 2210 2211
		cond_resched();
		sequence = mapping->truncate_count;
		smp_rmb();
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2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232
		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) {
2233
			inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2234
			lru_cache_add_active(new_page);
N
Nick Piggin 已提交
2235
			page_add_new_anon_rmap(new_page, vma, address);
2236
		} else {
2237
			inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
2238
			page_add_file_rmap(new_page);
2239 2240 2241 2242
			if (write_access) {
				dirty_page = new_page;
				get_page(dirty_page);
			}
2243
		}
L
Linus Torvalds 已提交
2244 2245 2246
	} else {
		/* One of our sibling threads was faster, back out. */
		page_cache_release(new_page);
2247
		goto unlock;
L
Linus Torvalds 已提交
2248 2249 2250 2251 2252
	}

	/* no need to invalidate: a not-present page shouldn't be cached */
	update_mmu_cache(vma, address, entry);
	lazy_mmu_prot_update(entry);
2253
unlock:
2254
	pte_unmap_unlock(page_table, ptl);
2255
	if (dirty_page) {
P
Peter Zijlstra 已提交
2256
		set_page_dirty_balance(dirty_page);
2257 2258
		put_page(dirty_page);
	}
L
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2259 2260 2261
	return ret;
oom:
	page_cache_release(new_page);
2262
	return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2263 2264
}

J
Jes Sorensen 已提交
2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312
/*
 * 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
2313 2314 2315 2316
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2317 2318 2319 2320
 *
 * 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
2321
 */
2322 2323 2324
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
2325
{
2326
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2327 2328
	int err;

H
Hugh Dickins 已提交
2329
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2330
		return VM_FAULT_MINOR;
L
Linus Torvalds 已提交
2331

2332 2333 2334 2335
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2336
		print_bad_pte(vma, orig_pte, address);
2337 2338 2339 2340 2341 2342 2343
		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
2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359
	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
2360 2361 2362
 * 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
2363 2364
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2365 2366
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2367 2368
{
	pte_t entry;
2369
	pte_t old_entry;
2370
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2371

2372
	old_entry = entry = *pte;
L
Linus Torvalds 已提交
2373
	if (!pte_present(entry)) {
2374
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385
			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);
2386
		}
L
Linus Torvalds 已提交
2387
		if (pte_file(entry))
2388 2389 2390 2391
			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
2392 2393
	}

H
Hugh Dickins 已提交
2394
	ptl = pte_lockptr(mm, pmd);
2395 2396 2397
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2398 2399
	if (write_access) {
		if (!pte_write(entry))
2400 2401
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2402 2403 2404
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418
	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);
	}
2419 2420
unlock:
	pte_unmap_unlock(pte, ptl);
L
Linus Torvalds 已提交
2421 2422 2423 2424 2425 2426
	return VM_FAULT_MINOR;
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
2427
int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2428 2429 2430 2431 2432 2433 2434 2435 2436
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2437
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2438

2439 2440
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2441 2442 2443 2444

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2445
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2446 2447
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2448
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2449 2450
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2451
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2452

H
Hugh Dickins 已提交
2453
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2454 2455
}

2456 2457
EXPORT_SYMBOL_GPL(__handle_mm_fault);

L
Linus Torvalds 已提交
2458 2459 2460
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2461
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2462
 */
2463
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2464
{
H
Hugh Dickins 已提交
2465 2466
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2467
		return -ENOMEM;
L
Linus Torvalds 已提交
2468

H
Hugh Dickins 已提交
2469
	spin_lock(&mm->page_table_lock);
2470
	if (pgd_present(*pgd))		/* Another has populated it */
L
Linus Torvalds 已提交
2471
		pud_free(new);
2472 2473
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2474
	spin_unlock(&mm->page_table_lock);
2475
	return 0;
L
Linus Torvalds 已提交
2476
}
2477 2478 2479 2480 2481 2482
#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
2483 2484 2485 2486 2487
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2488
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2489
 */
2490
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2491
{
H
Hugh Dickins 已提交
2492 2493
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2494
		return -ENOMEM;
L
Linus Torvalds 已提交
2495

H
Hugh Dickins 已提交
2496
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2497
#ifndef __ARCH_HAS_4LEVEL_HACK
2498
	if (pud_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2499
		pmd_free(new);
2500 2501
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2502
#else
2503
	if (pgd_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2504
		pmd_free(new);
2505 2506
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2507
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2508
	spin_unlock(&mm->page_table_lock);
2509
	return 0;
2510 2511 2512 2513 2514 2515
}
#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
2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527
}
#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;
2528 2529
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
L
Linus Torvalds 已提交
2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 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
	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)
2581
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2582 2583 2584 2585 2586 2587 2588

static int __init gate_vma_init(void)
{
	gate_vma.vm_mm = NULL;
	gate_vma.vm_start = FIXADDR_USER_START;
	gate_vma.vm_end = FIXADDR_USER_END;
	gate_vma.vm_page_prot = PAGE_READONLY;
H
Hugh Dickins 已提交
2589
	gate_vma.vm_flags = 0;
L
Linus Torvalds 已提交
2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613
	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 */
2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666

/*
 * 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;
}