memory.c 82.1 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

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

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#include "internal.h"

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

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

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

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	if (HAVE_PTE_SPECIAL) {
		if (likely(!pte_special(pte))) {
			VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
			return pte_page(pte);
		}
		VM_BUG_ON(!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)));
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

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

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	VM_BUG_ON(!pfn_valid(pfn));
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	/*
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	 * NOTE! We still have PageReserved() pages in the page tables.
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	 *
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	 * eg. VDSO mappings can cause them to exist.
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	 */
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out:
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	return pfn_to_page(pfn);
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}

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

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

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

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

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

	/*
	 * If it's a shared mapping, mark it clean in
	 * the child
	 */
	if (vm_flags & VM_SHARED)
		pte = pte_mkclean(pte);
	pte = pte_mkold(pte);
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	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
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		page_dup_rmap(page, vma, addr);
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		rss[!!PageAnon(page)]++;
	}
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out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
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}

static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pte_t *src_pte, *dst_pte;
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	spinlock_t *src_ptl, *dst_ptl;
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	int progress = 0;
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	int rss[2];
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again:
568
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
569
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
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	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
573
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
574
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
575
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
576 577 578 579 580 581

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
582 583 584
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
585
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
586 587
				break;
		}
L
Linus Torvalds 已提交
588 589 590 591
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
592
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
593 594 595
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

596
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
597
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
598
	pte_unmap_nested(src_pte - 1);
599
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
600 601
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
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Linus Torvalds 已提交
602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657
	if (addr != end)
		goto again;
	return 0;
}

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

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

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

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

int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		struct vm_area_struct *vma)
{
	pgd_t *src_pgd, *dst_pgd;
	unsigned long next;
	unsigned long addr = vma->vm_start;
	unsigned long end = vma->vm_end;
A
Andrea Arcangeli 已提交
658
	int ret;
L
Linus Torvalds 已提交
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660 661 662 663 664 665
	/*
	 * 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.
	 */
666
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
667 668 669 670
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
671 672 673
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

A
Andrea Arcangeli 已提交
674 675 676 677 678 679 680 681 682 683
	/*
	 * We need to invalidate the secondary MMU mappings only when
	 * there could be a permission downgrade on the ptes of the
	 * parent mm. And a permission downgrade will only happen if
	 * is_cow_mapping() returns true.
	 */
	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_start(src_mm, addr, end);

	ret = 0;
L
Linus Torvalds 已提交
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	dst_pgd = pgd_offset(dst_mm, addr);
	src_pgd = pgd_offset(src_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(src_pgd))
			continue;
A
Andrea Arcangeli 已提交
690 691 692 693 694
		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
					    vma, addr, next))) {
			ret = -ENOMEM;
			break;
		}
L
Linus Torvalds 已提交
695
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
696 697 698 699 700

	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_end(src_mm,
						  vma->vm_start, end);
	return ret;
L
Linus Torvalds 已提交
701 702
}

703
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
704
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
705
				unsigned long addr, unsigned long end,
706
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
707
{
N
Nick Piggin 已提交
708
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
709
	pte_t *pte;
710
	spinlock_t *ptl;
711 712
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
713

714
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
715
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
716 717
	do {
		pte_t ptent = *pte;
718 719
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
720
			continue;
721
		}
722 723 724

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
725
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
726
			struct page *page;
727

728
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
				/*
				 * Each page->index must be checked when
				 * invalidating or truncating nonlinear.
				 */
				if (details->nonlinear_vma &&
				    (page->index < details->first_index ||
				     page->index > details->last_index))
					continue;
			}
N
Nick Piggin 已提交
747
			ptent = ptep_get_and_clear_full(mm, addr, pte,
748
							tlb->fullmm);
L
Linus Torvalds 已提交
749 750 751 752 753 754
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (unlikely(details) && details->nonlinear_vma
			    && linear_page_index(details->nonlinear_vma,
						addr) != page->index)
N
Nick Piggin 已提交
755
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
756 757
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
758
				anon_rss--;
759 760 761 762
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
763
					SetPageReferenced(page);
H
Hugh Dickins 已提交
764
				file_rss--;
765
			}
N
Nick Piggin 已提交
766
			page_remove_rmap(page, vma);
L
Linus Torvalds 已提交
767 768 769 770 771 772 773 774 775 776 777
			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));
778
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
779
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
780

H
Hugh Dickins 已提交
781
	add_mm_rss(mm, file_rss, anon_rss);
782
	arch_leave_lazy_mmu_mode();
783
	pte_unmap_unlock(pte - 1, ptl);
784 785

	return addr;
L
Linus Torvalds 已提交
786 787
}

788
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
789
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
790
				unsigned long addr, unsigned long end,
791
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
792 793 794 795 796 797 798
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
799 800
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
801
			continue;
802 803 804 805 806 807
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
808 809
}

810
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
811
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
812
				unsigned long addr, unsigned long end,
813
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
814 815 816 817 818 819 820
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
821 822
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
823
			continue;
824 825 826 827 828 829
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
830 831
}

832 833
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
834
				unsigned long addr, unsigned long end,
835
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
836 837 838 839 840 841 842 843 844 845 846 847
{
	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);
848 849
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
850
			continue;
851 852 853 854
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
L
Linus Torvalds 已提交
855
	tlb_end_vma(tlb, vma);
856 857

	return addr;
L
Linus Torvalds 已提交
858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875
}

#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
 *
876
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
877
 *
878
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
879
 *
880 881
 * We aim to not hold locks for too long (for scheduling latency reasons).
 * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
L
Linus Torvalds 已提交
882 883 884 885 886 887 888 889 890 891 892
 * 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.
 */
893
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
894 895 896 897
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
898
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
899 900
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
901
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
902
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
903
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
904
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
905

A
Andrea Arcangeli 已提交
906
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925
	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;
			}

926
			if (unlikely(is_vm_hugetlb_page(vma))) {
927 928 929 930 931 932 933 934 935 936 937 938 939 940
				/*
				 * It is undesirable to test vma->vm_file as it
				 * should be non-null for valid hugetlb area.
				 * However, vm_file will be NULL in the error
				 * cleanup path of do_mmap_pgoff. When
				 * hugetlbfs ->mmap method fails,
				 * do_mmap_pgoff() nullifies vma->vm_file
				 * before calling this function to clean up.
				 * Since no pte has actually been setup, it is
				 * safe to do nothing in this case.
				 */
				if (vma->vm_file) {
					unmap_hugepage_range(vma, start, end, NULL);
					zap_work -= (end - start) /
941
					pages_per_huge_page(hstate_vma(vma));
942 943
				}

944 945 946 947 948 949 950 951
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

			if (zap_work > 0) {
				BUG_ON(start != end);
				break;
L
Linus Torvalds 已提交
952 953 954 955 956
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
957
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
958
				if (i_mmap_lock) {
959
					*tlbp = NULL;
L
Linus Torvalds 已提交
960 961 962 963 964
					goto out;
				}
				cond_resched();
			}

965
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
966
			tlb_start_valid = 0;
967
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
968 969 970
		}
	}
out:
A
Andrea Arcangeli 已提交
971
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
972
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
973 974 975 976 977 978 979 980 981
}

/**
 * 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
 */
982
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
983 984 985 986 987 988 989 990 991
		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);
992
	update_hiwater_rss(mm);
993 994 995
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
996
	return end;
L
Linus Torvalds 已提交
997 998
}

999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
/**
 * zap_vma_ptes - remove ptes mapping the vma
 * @vma: vm_area_struct holding ptes to be zapped
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 *
 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
 *
 * The entire address range must be fully contained within the vma.
 *
 * Returns 0 if successful.
 */
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
		unsigned long size)
{
	if (address < vma->vm_start || address + size > vma->vm_end ||
	    		!(vma->vm_flags & VM_PFNMAP))
		return -1;
	zap_page_range(vma, address, size, NULL);
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

L
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1022 1023 1024
/*
 * Do a quick page-table lookup for a single page.
 */
1025
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1026
			unsigned int flags)
L
Linus Torvalds 已提交
1027 1028 1029 1030 1031
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1032
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1033
	struct page *page;
1034
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1035

1036 1037 1038 1039 1040
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
Linus Torvalds 已提交
1041

1042
	page = NULL;
L
Linus Torvalds 已提交
1043 1044
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1045
		goto no_page_table;
L
Linus Torvalds 已提交
1046 1047

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1048
	if (pud_none(*pud))
1049
		goto no_page_table;
A
Andi Kleen 已提交
1050 1051 1052 1053 1054 1055 1056 1057
	if (pud_huge(*pud)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
		goto out;
	}
	if (unlikely(pud_bad(*pud)))
		goto no_page_table;

L
Linus Torvalds 已提交
1058
	pmd = pmd_offset(pud, address);
1059
	if (pmd_none(*pmd))
1060 1061 1062 1063
		goto no_page_table;
	if (pmd_huge(*pmd)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
1064
		goto out;
1065
	}
1066 1067 1068
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1069
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1070 1071

	pte = *ptep;
1072
	if (!pte_present(pte))
1073
		goto no_page;
1074 1075
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
1076 1077
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
1078
		goto bad_page;
L
Linus Torvalds 已提交
1079

1080 1081 1082 1083 1084 1085 1086 1087 1088 1089
	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);
L
Linus Torvalds 已提交
1090
out:
1091
	return page;
L
Linus Torvalds 已提交
1092

1093 1094 1095 1096 1097 1098 1099 1100 1101
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
	/* Fall through to ZERO_PAGE handling */
1102 1103 1104 1105 1106 1107
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
N
Nick Piggin 已提交
1108
		page = ZERO_PAGE(0);
1109 1110 1111 1112 1113
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1114 1115
}

1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128
/* Can we do the FOLL_ANON optimization? */
static inline int use_zero_page(struct vm_area_struct *vma)
{
	/*
	 * We don't want to optimize FOLL_ANON for make_pages_present()
	 * when it tries to page in a VM_LOCKED region. As to VM_SHARED,
	 * we want to get the page from the page tables to make sure
	 * that we serialize and update with any other user of that
	 * mapping.
	 */
	if (vma->vm_flags & (VM_LOCKED | VM_SHARED))
		return 0;
	/*
N
Nick Piggin 已提交
1129
	 * And if we have a fault routine, it's not an anonymous region.
1130
	 */
N
Nick Piggin 已提交
1131
	return !vma->vm_ops || !vma->vm_ops->fault;
1132 1133
}

N
Nick Piggin 已提交
1134 1135 1136 1137


int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		     unsigned long start, int len, int flags,
L
Linus Torvalds 已提交
1138 1139 1140
		struct page **pages, struct vm_area_struct **vmas)
{
	int i;
N
Nick Piggin 已提交
1141 1142 1143 1144
	unsigned int vm_flags = 0;
	int write = !!(flags & GUP_FLAGS_WRITE);
	int force = !!(flags & GUP_FLAGS_FORCE);
	int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
L
Linus Torvalds 已提交
1145

1146 1147
	if (len <= 0)
		return 0;
L
Linus Torvalds 已提交
1148 1149 1150 1151
	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
1152 1153
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
1154 1155 1156
	i = 0;

	do {
1157 1158
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
1159 1160 1161 1162 1163 1164 1165 1166 1167

		vma = find_extend_vma(mm, start);
		if (!vma && in_gate_area(tsk, start)) {
			unsigned long pg = start & PAGE_MASK;
			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
N
Nick Piggin 已提交
1168 1169 1170

			/* user gate pages are read-only */
			if (!ignore && write)
L
Linus Torvalds 已提交
1171 1172 1173 1174 1175 1176 1177 1178 1179
				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);
1180 1181
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1182
			pte = pte_offset_map(pmd, pg);
1183 1184 1185 1186
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1187
			if (pages) {
1188
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1189 1190 1191
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

N
Nick Piggin 已提交
1202 1203 1204
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
		    (!ignore && !(vm_flags & vma->vm_flags)))
L
Linus Torvalds 已提交
1205 1206 1207 1208
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1209
						&start, &len, i, write);
L
Linus Torvalds 已提交
1210 1211
			continue;
		}
1212 1213 1214 1215

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
1216
		if (!write && use_zero_page(vma))
1217 1218
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1219
		do {
1220
			struct page *page;
L
Linus Torvalds 已提交
1221

1222 1223 1224 1225 1226 1227
			/*
			 * If tsk is ooming, cut off its access to large memory
			 * allocations. It has a pending SIGKILL, but it can't
			 * be processed until returning to user space.
			 */
			if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
1228
				return i ? i : -ENOMEM;
1229

1230 1231
			if (write)
				foll_flags |= FOLL_WRITE;
1232

1233
			cond_resched();
1234
			while (!(page = follow_page(vma, start, foll_flags))) {
1235
				int ret;
N
Nick Piggin 已提交
1236
				ret = handle_mm_fault(mm, vma, start,
1237
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
					else if (ret & VM_FAULT_SIGBUS)
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1250
				/*
N
Nick Piggin 已提交
1251 1252 1253 1254 1255
				 * 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.
1256 1257
				 */
				if (ret & VM_FAULT_WRITE)
1258
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1259

1260
				cond_resched();
L
Linus Torvalds 已提交
1261
			}
1262 1263
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1264
			if (pages) {
1265
				pages[i] = page;
1266

1267
				flush_anon_page(vma, page, start);
1268
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1269 1270 1271 1272 1273 1274
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1275 1276
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1277 1278
	return i;
}
N
Nick Piggin 已提交
1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295

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

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

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

L
Linus Torvalds 已提交
1296 1297
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1298 1299
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1300 1301 1302 1303
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1304
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1305 1306 1307 1308 1309 1310
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1311 1312 1313 1314 1315 1316 1317
/*
 * This is the old fallback for page remapping.
 *
 * For historical reasons, it only allows reserved pages. Only
 * old drivers should use this, and they needed to mark their
 * pages reserved for the old functions anyway.
 */
N
Nick Piggin 已提交
1318 1319
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1320
{
N
Nick Piggin 已提交
1321
	struct mm_struct *mm = vma->vm_mm;
1322
	int retval;
1323
	pte_t *pte;
1324 1325
	spinlock_t *ptl;

1326
	retval = mem_cgroup_charge(page, mm, GFP_KERNEL);
1327 1328
	if (retval)
		goto out;
1329 1330

	retval = -EINVAL;
1331
	if (PageAnon(page))
1332
		goto out_uncharge;
1333 1334
	retval = -ENOMEM;
	flush_dcache_page(page);
1335
	pte = get_locked_pte(mm, addr, &ptl);
1336
	if (!pte)
1337
		goto out_uncharge;
1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348
	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;
1349 1350
	pte_unmap_unlock(pte, ptl);
	return retval;
1351 1352
out_unlock:
	pte_unmap_unlock(pte, ptl);
1353 1354
out_uncharge:
	mem_cgroup_uncharge_page(page);
1355 1356 1357 1358
out:
	return retval;
}

1359 1360 1361 1362 1363 1364
/**
 * 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
 *
1365 1366 1367 1368 1369 1370
 * 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
1371
 * (see split_page()).
1372 1373 1374 1375 1376 1377 1378 1379 1380
 *
 * NOTE! Traditionally this was done with "remap_pfn_range()" which
 * took an arbitrary page protection parameter. This doesn't allow
 * that. Your vma protection will have to be set up correctly, which
 * means that if you want a shared writable mapping, you'd better
 * ask for a shared writable mapping!
 *
 * The page does not need to be reserved.
 */
N
Nick Piggin 已提交
1381 1382
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1383 1384 1385 1386 1387
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1388
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1389
	return insert_page(vma, addr, page, vma->vm_page_prot);
1390
}
1391
EXPORT_SYMBOL(vm_insert_page);
1392

N
Nick Piggin 已提交
1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn, pgprot_t prot)
{
	struct mm_struct *mm = vma->vm_mm;
	int retval;
	pte_t *pte, entry;
	spinlock_t *ptl;

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

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

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

N
Nick Piggin 已提交
1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431
/**
 * vm_insert_pfn - insert single pfn into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @pfn: source kernel pfn
 *
 * Similar to vm_inert_page, this allows drivers to insert individual pages
 * they've allocated into a user vma. Same comments apply.
 *
 * This function should only be called from a vm_ops->fault handler, and
 * in that case the handler should return NULL.
N
Nick Piggin 已提交
1432 1433 1434 1435 1436
 *
 * vma cannot be a COW mapping.
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
N
Nick Piggin 已提交
1437 1438
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1439
			unsigned long pfn)
N
Nick Piggin 已提交
1440
{
N
Nick Piggin 已提交
1441 1442 1443 1444 1445 1446
	/*
	 * Technically, architectures with pte_special can avoid all these
	 * restrictions (same for remap_pfn_range).  However we would like
	 * consistency in testing and feature parity among all, so we should
	 * try to keep these invariants in place for everybody.
	 */
J
Jared Hulbert 已提交
1447 1448 1449 1450 1451
	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
						(VM_PFNMAP|VM_MIXEDMAP));
	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
N
Nick Piggin 已提交
1452

N
Nick Piggin 已提交
1453 1454 1455 1456 1457
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1458

N
Nick Piggin 已提交
1459 1460 1461 1462
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn)
{
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1463

N
Nick Piggin 已提交
1464 1465
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1466

N
Nick Piggin 已提交
1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479
	/*
	 * If we don't have pte special, then we have to use the pfn_valid()
	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
	 * refcount the page if pfn_valid is true (hence insert_page rather
	 * than insert_pfn).
	 */
	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
		struct page *page;

		page = pfn_to_page(pfn);
		return insert_page(vma, addr, page, vma->vm_page_prot);
	}
	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
N
Nick Piggin 已提交
1480
}
N
Nick Piggin 已提交
1481
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1482

L
Linus Torvalds 已提交
1483 1484 1485 1486 1487 1488 1489 1490 1491 1492
/*
 * 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
1493
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1494

H
Hugh Dickins 已提交
1495
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1496 1497
	if (!pte)
		return -ENOMEM;
1498
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1499 1500
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1501
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1502 1503
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1504
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1505
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548
	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;
}

1549 1550 1551 1552 1553 1554 1555 1556 1557 1558
/**
 * 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
1559 1560 1561 1562 1563
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;
1564
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1565 1566 1567 1568 1569 1570 1571 1572
	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
1573 1574 1575 1576 1577
	 *   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.
1578 1579 1580
	 *   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
1581 1582 1583 1584
	 *
	 * 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
1585
	 */
1586
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1587
		if (addr != vma->vm_start || end != vma->vm_end)
1588
			return -EINVAL;
L
Linus Torvalds 已提交
1589 1590 1591
		vma->vm_pgoff = pfn;
	}

1592
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608

	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);

1609 1610 1611 1612 1613 1614
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pte_t *pte;
	int err;
1615
	pgtable_t token;
1616
	spinlock_t *uninitialized_var(ptl);
1617 1618 1619 1620 1621 1622 1623 1624 1625

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

	BUG_ON(pmd_huge(*pmd));

1626
	token = pmd_pgtable(*pmd);
1627 1628

	do {
1629
		err = fn(pte, token, addr, data);
1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

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

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

A
Andi Kleen 已提交
1647 1648
	BUG_ON(pud_huge(*pud));

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 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);
	return err;
}

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

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

/*
 * Scan a region of virtual memory, filling in page tables as necessary
 * and calling a provided function on each leaf page table.
 */
int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
			unsigned long size, pte_fn_t fn, void *data)
{
	pgd_t *pgd;
	unsigned long next;
A
Andrea Arcangeli 已提交
1690
	unsigned long start = addr, end = addr + size;
1691 1692 1693
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1694
	mmu_notifier_invalidate_range_start(mm, start, end);
1695 1696 1697 1698 1699 1700 1701
	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1702
	mmu_notifier_invalidate_range_end(mm, start, end);
1703 1704 1705 1706
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1707 1708 1709 1710 1711 1712 1713 1714 1715
/*
 * 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
1716
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1717 1718 1719 1720 1721
				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
1722 1723
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1724
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1725
		spin_unlock(ptl);
1726 1727 1728 1729 1730 1731
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744
/*
 * 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;
}

1745
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1746 1747 1748 1749 1750 1751 1752 1753 1754
{
	/*
	 * 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
1755 1756 1757 1758 1759 1760 1761 1762 1763
		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))
1764 1765
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1766
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1767 1768
	} else
		copy_user_highpage(dst, src, va, vma);
1769 1770
}

L
Linus Torvalds 已提交
1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784
/*
 * 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.
 *
1785 1786 1787
 * 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
1788
 */
1789 1790
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1791
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1792
{
1793
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1794
	pte_t entry;
N
Nick Piggin 已提交
1795
	int reuse = 0, ret = 0;
1796
	int page_mkwrite = 0;
1797
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1798

1799
	old_page = vm_normal_page(vma, address, orig_pte);
1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810
	if (!old_page) {
		/*
		 * VM_MIXEDMAP !pfn_valid() case
		 *
		 * We should not cow pages in a shared writeable mapping.
		 * Just mark the pages writable as we can't do any dirty
		 * accounting on raw pfn maps.
		 */
		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
				     (VM_WRITE|VM_SHARED))
			goto reuse;
1811
		goto gotten;
1812
	}
L
Linus Torvalds 已提交
1813

1814
	/*
P
Peter Zijlstra 已提交
1815 1816
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1817
	 */
P
Peter Zijlstra 已提交
1818
	if (PageAnon(old_page)) {
N
Nick Piggin 已提交
1819
		if (trylock_page(old_page)) {
P
Peter Zijlstra 已提交
1820 1821 1822 1823
			reuse = can_share_swap_page(old_page);
			unlock_page(old_page);
		}
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1824
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1825 1826 1827 1828 1829
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
			/*
			 * Notify the address space that the page is about to
			 * become writable so that it can prohibit this or wait
			 * for the page to get into an appropriate state.
			 *
			 * We do this without the lock held, so that it can
			 * sleep if it needs to.
			 */
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);

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

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
1853
			page_cache_release(old_page);
1854 1855
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1856 1857

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1858
		}
1859 1860
		dirty_page = old_page;
		get_page(dirty_page);
1861 1862 1863 1864
		reuse = 1;
	}

	if (reuse) {
1865
reuse:
1866 1867 1868
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1869
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1870
			update_mmu_cache(vma, address, entry);
1871 1872
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1873 1874 1875 1876 1877
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1878
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1879
gotten:
1880
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1881 1882

	if (unlikely(anon_vma_prepare(vma)))
1883
		goto oom;
N
Nick Piggin 已提交
1884 1885 1886 1887
	VM_BUG_ON(old_page == ZERO_PAGE(0));
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
	if (!new_page)
		goto oom;
N
Nick Piggin 已提交
1888 1889 1890 1891 1892 1893 1894 1895 1896
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
	if (vma->vm_flags & VM_LOCKED) {
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
N
Nick Piggin 已提交
1897
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
1898
	__SetPageUptodate(new_page);
1899

1900
	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
1901 1902
		goto oom_free_new;

L
Linus Torvalds 已提交
1903 1904 1905
	/*
	 * Re-check the pte - we dropped the lock
	 */
1906
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1907
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1908 1909 1910 1911 1912 1913
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1914
			inc_mm_counter(mm, anon_rss);
1915
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1916 1917
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1918 1919 1920 1921 1922 1923
		/*
		 * Clear the pte entry and flush it first, before updating the
		 * pte with the new entry. This will avoid a race condition
		 * seen in the presence of one thread doing SMC and another
		 * thread doing COW.
		 */
A
Andrea Arcangeli 已提交
1924
		ptep_clear_flush_notify(vma, address, page_table);
R
Rik van Riel 已提交
1925
		SetPageSwapBacked(new_page);
1926
		lru_cache_add_active_or_unevictable(new_page, vma);
N
Nick Piggin 已提交
1927
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1928

1929 1930 1931
//TODO:  is this safe?  do_anonymous_page() does it this way.
		set_pte_at(mm, address, page_table, entry);
		update_mmu_cache(vma, address, entry);
N
Nick Piggin 已提交
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
		if (old_page) {
			/*
			 * Only after switching the pte to the new page may
			 * we remove the mapcount here. Otherwise another
			 * process may come and find the rmap count decremented
			 * before the pte is switched to the new page, and
			 * "reuse" the old page writing into it while our pte
			 * here still points into it and can be read by other
			 * threads.
			 *
			 * The critical issue is to order this
			 * page_remove_rmap with the ptp_clear_flush above.
			 * Those stores are ordered by (if nothing else,)
			 * the barrier present in the atomic_add_negative
			 * in page_remove_rmap.
			 *
			 * Then the TLB flush in ptep_clear_flush ensures that
			 * no process can access the old page before the
			 * decremented mapcount is visible. And the old page
			 * cannot be reused until after the decremented
			 * mapcount is visible. So transitively, TLBs to
			 * old page will be flushed before it can be reused.
			 */
			page_remove_rmap(old_page, vma);
		}

L
Linus Torvalds 已提交
1958 1959
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1960
		ret |= VM_FAULT_WRITE;
1961 1962 1963
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
1964 1965 1966 1967
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1968
unlock:
1969
	pte_unmap_unlock(page_table, ptl);
1970
	if (dirty_page) {
1971 1972 1973
		if (vma->vm_file)
			file_update_time(vma->vm_file);

1974 1975 1976 1977 1978 1979 1980 1981 1982
		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
		 * do_no_page is protected similarly.
		 */
		wait_on_page_locked(dirty_page);
1983
		set_page_dirty_balance(dirty_page, page_mkwrite);
1984 1985
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1986
	return ret;
1987
oom_free_new:
1988
	page_cache_release(new_page);
1989
oom:
H
Hugh Dickins 已提交
1990 1991
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1992
	return VM_FAULT_OOM;
1993 1994 1995 1996

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023
}

/*
 * 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
2024
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050
 * 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;

2051 2052
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2053
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2054 2055
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2056 2057
	 */

L
Linus Torvalds 已提交
2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068
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;
		}
	}

2069 2070
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2071
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2072

2073
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2074 2075 2076 2077 2078 2079
		/* 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 */
2080
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146
		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;
	}
}

/**
2147
 * 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
2148
 * @mapping: the address space containing mmaps to be unmapped.
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 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184
 * @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);

2185
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201
	mapping->truncate_count++;
	if (unlikely(is_restart_addr(mapping->truncate_count))) {
		if (mapping->truncate_count == 0)
			reset_vma_truncate_counts(mapping);
		mapping->truncate_count++;
	}
	details.truncate_count = mapping->truncate_count;

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

2202 2203 2204 2205
/**
 * 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
2206 2207 2208 2209 2210 2211 2212
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode * inode, loff_t offset)
{
C
Christoph Hellwig 已提交
2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223
	if (inode->i_size < offset) {
		unsigned long limit;

		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
		if (limit != RLIM_INFINITY && offset > limit)
			goto out_sig;
		if (offset > inode->i_sb->s_maxbytes)
			goto out_big;
		i_size_write(inode, offset);
	} else {
		struct address_space *mapping = inode->i_mapping;
L
Linus Torvalds 已提交
2224

C
Christoph Hellwig 已提交
2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246
		/*
		 * truncation of in-use swapfiles is disallowed - it would
		 * cause subsequent swapout to scribble on the now-freed
		 * blocks.
		 */
		if (IS_SWAPFILE(inode))
			return -ETXTBSY;
		i_size_write(inode, offset);

		/*
		 * unmap_mapping_range is called twice, first simply for
		 * efficiency so that truncate_inode_pages does fewer
		 * single-page unmaps.  However after this first call, and
		 * before truncate_inode_pages finishes, it is possible for
		 * private pages to be COWed, which remain after
		 * truncate_inode_pages finishes, hence the second
		 * unmap_mapping_range call must be made for correctness.
		 */
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
		truncate_inode_pages(mapping, offset);
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	}
2247

L
Linus Torvalds 已提交
2248 2249 2250
	if (inode->i_op && inode->i_op->truncate)
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2251

L
Linus Torvalds 已提交
2252 2253 2254 2255 2256 2257 2258
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270
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;

2271
	mutex_lock(&inode->i_mutex);
2272 2273 2274
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2275
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2276 2277
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2278
	mutex_unlock(&inode->i_mutex);
2279 2280 2281 2282

	return 0;
}

L
Linus Torvalds 已提交
2283
/*
2284 2285 2286
 * 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
2287
 */
2288 2289 2290
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
2291
{
2292
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2293
	struct page *page;
2294
	swp_entry_t entry;
L
Linus Torvalds 已提交
2295
	pte_t pte;
N
Nick Piggin 已提交
2296
	int ret = 0;
L
Linus Torvalds 已提交
2297

H
Hugh Dickins 已提交
2298
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2299
		goto out;
2300 2301

	entry = pte_to_swp_entry(orig_pte);
2302 2303 2304 2305
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2306
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2307 2308
	page = lookup_swap_cache(entry);
	if (!page) {
2309
		grab_swap_token(); /* Contend for token _before_ read-in */
2310 2311
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2312 2313
		if (!page) {
			/*
2314 2315
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2316
			 */
2317
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2318 2319
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2320
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2321
			goto unlock;
L
Linus Torvalds 已提交
2322 2323 2324 2325
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2326
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2327 2328
	}

2329
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2330 2331 2332 2333 2334
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
		ret = VM_FAULT_OOM;
		goto out;
	}

L
Linus Torvalds 已提交
2335 2336
	mark_page_accessed(page);
	lock_page(page);
2337
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2338 2339

	/*
2340
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2341
	 */
2342
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2343
	if (unlikely(!pte_same(*page_table, orig_pte)))
2344 2345 2346 2347 2348
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2349 2350 2351 2352
	}

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

2353
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2354 2355 2356 2357 2358 2359 2360 2361 2362 2363
	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);

2364
	swap_free(entry);
N
Nick Piggin 已提交
2365
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2366 2367 2368
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2369
	if (write_access) {
2370 2371 2372
		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
		if (ret & VM_FAULT_ERROR)
			ret &= VM_FAULT_ERROR;
L
Linus Torvalds 已提交
2373 2374 2375 2376 2377
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2378
unlock:
2379
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2380 2381
out:
	return ret;
2382
out_nomap:
2383
	mem_cgroup_uncharge_page(page);
2384
	pte_unmap_unlock(page_table, ptl);
2385 2386
	unlock_page(page);
	page_cache_release(page);
2387
	return ret;
L
Linus Torvalds 已提交
2388 2389 2390
}

/*
2391 2392 2393
 * 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
2394
 */
2395 2396 2397
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
2398
{
2399 2400
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2401 2402
	pte_t entry;

N
Nick Piggin 已提交
2403 2404
	/* Allocate our own private page. */
	pte_unmap(page_table);
2405

N
Nick Piggin 已提交
2406 2407 2408 2409 2410
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
N
Nick Piggin 已提交
2411
	__SetPageUptodate(page);
2412

2413
	if (mem_cgroup_charge(page, mm, GFP_KERNEL))
2414 2415
		goto oom_free_page;

N
Nick Piggin 已提交
2416 2417
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2418

N
Nick Piggin 已提交
2419 2420 2421 2422
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!pte_none(*page_table))
		goto release;
	inc_mm_counter(mm, anon_rss);
R
Rik van Riel 已提交
2423
	SetPageSwapBacked(page);
2424
	lru_cache_add_active_or_unevictable(page, vma);
N
Nick Piggin 已提交
2425
	page_add_new_anon_rmap(page, vma, address);
2426
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2427 2428

	/* No need to invalidate - it was non-present before */
2429 2430
	update_mmu_cache(vma, address, entry);
unlock:
2431
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2432
	return 0;
2433
release:
2434
	mem_cgroup_uncharge_page(page);
2435 2436
	page_cache_release(page);
	goto unlock;
2437
oom_free_page:
2438
	page_cache_release(page);
2439
oom:
L
Linus Torvalds 已提交
2440 2441 2442 2443
	return VM_FAULT_OOM;
}

/*
2444
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2445
 * tries to share with existing pages, but makes a separate copy if
2446 2447
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2448 2449 2450 2451
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2452
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2453
 * but allow concurrent faults), and pte neither mapped nor locked.
2454
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2455
 */
2456
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2457
		unsigned long address, pmd_t *pmd,
2458
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2459
{
2460
	pte_t *page_table;
2461
	spinlock_t *ptl;
N
Nick Piggin 已提交
2462
	struct page *page;
L
Linus Torvalds 已提交
2463 2464
	pte_t entry;
	int anon = 0;
2465
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2466 2467
	struct vm_fault vmf;
	int ret;
2468
	int page_mkwrite = 0;
2469

N
Nick Piggin 已提交
2470 2471 2472 2473
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2474

N
Nick Piggin 已提交
2475 2476 2477
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2478

2479
	/*
N
Nick Piggin 已提交
2480
	 * For consistency in subsequent calls, make the faulted page always
2481 2482
	 * locked.
	 */
N
Nick Piggin 已提交
2483
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2484
		lock_page(vmf.page);
2485
	else
N
Nick Piggin 已提交
2486
		VM_BUG_ON(!PageLocked(vmf.page));
2487

L
Linus Torvalds 已提交
2488 2489 2490
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2491
	page = vmf.page;
2492
	if (flags & FAULT_FLAG_WRITE) {
2493
		if (!(vma->vm_flags & VM_SHARED)) {
2494
			anon = 1;
2495
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2496
				ret = VM_FAULT_OOM;
2497
				goto out;
2498
			}
N
Nick Piggin 已提交
2499 2500
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2501
			if (!page) {
N
Nick Piggin 已提交
2502
				ret = VM_FAULT_OOM;
2503
				goto out;
2504
			}
N
Nick Piggin 已提交
2505 2506 2507 2508 2509 2510
			/*
			 * Don't let another task, with possibly unlocked vma,
			 * keep the mlocked page.
			 */
			if (vma->vm_flags & VM_LOCKED)
				clear_page_mlock(vmf.page);
N
Nick Piggin 已提交
2511
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2512
			__SetPageUptodate(page);
2513
		} else {
2514 2515
			/*
			 * If the page will be shareable, see if the backing
2516
			 * address space wants to know that the page is about
2517 2518
			 * to become writable
			 */
2519 2520 2521
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2522 2523
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2524 2525 2526
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2527 2528 2529 2530 2531 2532 2533 2534
				/*
				 * XXX: this is not quite right (racy vs
				 * invalidate) to unlock and relock the page
				 * like this, however a better fix requires
				 * reworking page_mkwrite locking API, which
				 * is better done later.
				 */
				if (!page->mapping) {
N
Nick Piggin 已提交
2535
					ret = 0;
N
Nick Piggin 已提交
2536 2537 2538
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2539
				page_mkwrite = 1;
2540 2541
			}
		}
2542

L
Linus Torvalds 已提交
2543 2544
	}

2545
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2546 2547 2548 2549
		ret = VM_FAULT_OOM;
		goto out;
	}

2550
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562

	/*
	 * 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... */
2563
	if (likely(pte_same(*page_table, orig_pte))) {
2564 2565
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2566
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2567 2568
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2569
			inc_mm_counter(mm, anon_rss);
R
Rik van Riel 已提交
2570
			SetPageSwapBacked(page);
2571 2572
			lru_cache_add_active_or_unevictable(page, vma);
			page_add_new_anon_rmap(page, vma, address);
2573
		} else {
2574
			inc_mm_counter(mm, file_rss);
2575
			page_add_file_rmap(page);
2576
			if (flags & FAULT_FLAG_WRITE) {
2577
				dirty_page = page;
2578 2579
				get_page(dirty_page);
			}
2580
		}
2581 2582
//TODO:  is this safe?  do_anonymous_page() does it this way.
		set_pte_at(mm, address, page_table, entry);
2583 2584 2585

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2586
	} else {
2587
		mem_cgroup_uncharge_page(page);
2588 2589 2590
		if (anon)
			page_cache_release(page);
		else
2591
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2592 2593
	}

2594
	pte_unmap_unlock(page_table, ptl);
2595 2596

out:
N
Nick Piggin 已提交
2597
	unlock_page(vmf.page);
2598
out_unlocked:
2599
	if (anon)
N
Nick Piggin 已提交
2600
		page_cache_release(vmf.page);
2601
	else if (dirty_page) {
2602 2603 2604
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2605
		set_page_dirty_balance(dirty_page, page_mkwrite);
2606 2607
		put_page(dirty_page);
	}
2608

N
Nick Piggin 已提交
2609
	return ret;
2610
}
2611

2612 2613 2614 2615 2616
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2617
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2618 2619
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2620 2621
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2622 2623
}

L
Linus Torvalds 已提交
2624 2625 2626 2627
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2628 2629 2630 2631
 *
 * 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
2632
 */
N
Nick Piggin 已提交
2633
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2634 2635
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2636
{
N
Nick Piggin 已提交
2637 2638
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2639
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2640

H
Hugh Dickins 已提交
2641
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2642
		return 0;
L
Linus Torvalds 已提交
2643

N
Nick Piggin 已提交
2644 2645
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2646 2647 2648
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2649
		print_bad_pte(vma, orig_pte, address);
2650 2651 2652 2653
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2654
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665
}

/*
 * 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
2666 2667 2668
 * 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
2669 2670
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2671 2672
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2673 2674
{
	pte_t entry;
2675
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2676

2677
	entry = *pte;
L
Linus Torvalds 已提交
2678
	if (!pte_present(entry)) {
2679
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2680
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2681
				if (likely(vma->vm_ops->fault))
2682 2683
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2684 2685 2686
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2687
		}
L
Linus Torvalds 已提交
2688
		if (pte_file(entry))
N
Nick Piggin 已提交
2689
			return do_nonlinear_fault(mm, vma, address,
2690 2691 2692
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2693 2694
	}

H
Hugh Dickins 已提交
2695
	ptl = pte_lockptr(mm, pmd);
2696 2697 2698
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2699 2700
	if (write_access) {
		if (!pte_write(entry))
2701 2702
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2703 2704 2705
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2706
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717
		update_mmu_cache(vma, address, entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2718 2719
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2720
	return 0;
L
Linus Torvalds 已提交
2721 2722 2723 2724 2725
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2726
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2727 2728 2729 2730 2731 2732 2733 2734 2735
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2736
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2737

2738 2739
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2740 2741 2742 2743

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2744
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2745 2746
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2747
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2748 2749
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2750
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2751

H
Hugh Dickins 已提交
2752
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2753 2754 2755 2756 2757
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2758
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2759
 */
2760
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2761
{
H
Hugh Dickins 已提交
2762 2763
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2764
		return -ENOMEM;
L
Linus Torvalds 已提交
2765

2766 2767
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2768
	spin_lock(&mm->page_table_lock);
2769
	if (pgd_present(*pgd))		/* Another has populated it */
2770
		pud_free(mm, new);
2771 2772
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2773
	spin_unlock(&mm->page_table_lock);
2774
	return 0;
L
Linus Torvalds 已提交
2775 2776 2777 2778 2779 2780
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2781
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2782
 */
2783
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2784
{
H
Hugh Dickins 已提交
2785 2786
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2787
		return -ENOMEM;
L
Linus Torvalds 已提交
2788

2789 2790
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2791
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2792
#ifndef __ARCH_HAS_4LEVEL_HACK
2793
	if (pud_present(*pud))		/* Another has populated it */
2794
		pmd_free(mm, new);
2795 2796
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2797
#else
2798
	if (pgd_present(*pud))		/* Another has populated it */
2799
		pmd_free(mm, new);
2800 2801
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2802
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2803
	spin_unlock(&mm->page_table_lock);
2804
	return 0;
2805
}
L
Linus Torvalds 已提交
2806 2807 2808 2809 2810 2811 2812 2813 2814
#endif /* __PAGETABLE_PMD_FOLDED */

int make_pages_present(unsigned long addr, unsigned long end)
{
	int ret, len, write;
	struct vm_area_struct * vma;

	vma = find_vma(current->mm, addr);
	if (!vma)
K
KOSAKI Motohiro 已提交
2815
		return -ENOMEM;
L
Linus Torvalds 已提交
2816
	write = (vma->vm_flags & VM_WRITE) != 0;
2817 2818
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2819
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2820 2821
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
K
KOSAKI Motohiro 已提交
2822 2823 2824 2825 2826 2827 2828 2829 2830 2831
	if (ret < 0) {
		/*
		   SUS require strange return value to mlock
		    - invalid addr generate to ENOMEM.
		    - out of memory should generate EAGAIN.
		*/
		if (ret == -EFAULT)
			ret = -ENOMEM;
		else if (ret == -ENOMEM)
			ret = -EAGAIN;
L
Linus Torvalds 已提交
2832
		return ret;
K
KOSAKI Motohiro 已提交
2833 2834
	}
	return ret == len ? 0 : -ENOMEM;
L
Linus Torvalds 已提交
2835 2836 2837 2838 2839
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2840
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2841 2842 2843 2844 2845 2846

static int __init gate_vma_init(void)
{
	gate_vma.vm_mm = NULL;
	gate_vma.vm_start = FIXADDR_USER_START;
	gate_vma.vm_end = FIXADDR_USER_END;
R
Roland McGrath 已提交
2847 2848
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2849 2850 2851 2852 2853 2854 2855
	/*
	 * Make sure the vDSO gets into every core dump.
	 * Dumping its contents makes post-mortem fully interpretable later
	 * without matching up the same kernel and hardware config to see
	 * what PC values meant.
	 */
	gate_vma.vm_flags |= VM_ALWAYSDUMP;
L
Linus Torvalds 已提交
2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879
	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 */
2880

2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960
#ifdef CONFIG_HAVE_IOREMAP_PROT
static resource_size_t follow_phys(struct vm_area_struct *vma,
			unsigned long address, unsigned int flags,
			unsigned long *prot)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
	spinlock_t *ptl;
	resource_size_t phys_addr = 0;
	struct mm_struct *mm = vma->vm_mm;

	VM_BUG_ON(!(vma->vm_flags & (VM_IO | VM_PFNMAP)));

	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
		goto no_page_table;

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
		goto no_page_table;

	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
		goto no_page_table;

	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
	if (pmd_huge(*pmd))
		goto no_page_table;

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

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

	*prot = pgprot_val(pte_pgprot(pte));

unlock:
	pte_unmap_unlock(ptep, ptl);
out:
	return phys_addr;
no_page_table:
	return 0;
}

int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
			void *buf, int len, int write)
{
	resource_size_t phys_addr;
	unsigned long prot = 0;
	void *maddr;
	int offset = addr & (PAGE_SIZE-1);

	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		return -EINVAL;

	phys_addr = follow_phys(vma, addr, write, &prot);

	if (!phys_addr)
		return -EINVAL;

	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
#endif

2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976
/*
 * Access another process' address space.
 * Source/target buffer must be kernel space,
 * Do not walk the page table directly, use get_user_pages
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	void *old_buf = buf;

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

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
2977
	/* ignore errors, just check how much was successfully transferred */
2978 2979 2980
	while (len) {
		int bytes, ret, offset;
		void *maddr;
2981
		struct page *page = NULL;
2982 2983 2984

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000
		if (ret <= 0) {
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
#ifdef CONFIG_HAVE_IOREMAP_PROT
			vma = find_vma(mm, addr);
			if (!vma)
				break;
			if (vma->vm_ops && vma->vm_ops->access)
				ret = vma->vm_ops->access(vma, addr, buf,
							  len, write);
			if (ret <= 0)
#endif
				break;
			bytes = ret;
3001
		} else {
3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017
			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);
3018 3019 3020 3021 3022 3023 3024 3025 3026 3027
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
3028 3029 3030 3031 3032 3033 3034 3035 3036

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

3037 3038 3039 3040 3041 3042 3043
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3044 3045 3046 3047 3048 3049 3050 3051
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, ip);
	if (vma && vma->vm_file) {
		struct file *f = vma->vm_file;
		char *buf = (char *)__get_free_page(GFP_KERNEL);
		if (buf) {
			char *p, *s;

3052
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065
			if (IS_ERR(p))
				p = "?";
			s = strrchr(p, '/');
			if (s)
				p = s+1;
			printk("%s%s[%lx+%lx]", prefix, p,
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
	up_read(&current->mm->mmap_sem);
}