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linux-sg2042/mm/memory.c

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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>
#include <linux/init.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>
#include <linux/swapops.h>
#include <linux/elf.h>
#ifndef CONFIG_DISCONTIGMEM
/* use the per-pgdat data instead for discontigmem - mbligh */
unsigned long max_mapnr;
struct page *mem_map;
EXPORT_SYMBOL(max_mapnr);
EXPORT_SYMBOL(mem_map);
#endif
unsigned long num_physpages;
/*
* A number of key systems in x86 including ioremap() rely on the assumption
* that high_memory defines the upper bound on direct map memory, then end
* of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
* highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
* and ZONE_HIGHMEM.
*/
void * high_memory;
unsigned long vmalloc_earlyreserve;
EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);
EXPORT_SYMBOL(vmalloc_earlyreserve);
/*
* 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.
*/
static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
{
struct page *page = pmd_page(*pmd);
pmd_clear(pmd);
pte_free_tlb(tlb, page);
dec_page_state(nr_page_table_pages);
tlb->mm->nr_ptes--;
}
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)
{
pmd_t *pmd;
unsigned long next;
unsigned long start;
start = addr;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
free_pte_range(tlb, pmd);
} while (pmd++, addr = next, addr != end);
start &= PUD_MASK;
if (start < floor)
return;
if (ceiling) {
ceiling &= PUD_MASK;
if (!ceiling)
return;
}
if (end - 1 > ceiling - 1)
return;
pmd = pmd_offset(pud, start);
pud_clear(pud);
pmd_free_tlb(tlb, pmd);
}
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)
{
pud_t *pud;
unsigned long next;
unsigned long start;
start = addr;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
free_pmd_range(tlb, pud, addr, next, floor, ceiling);
} while (pud++, addr = next, addr != end);
start &= PGDIR_MASK;
if (start < floor)
return;
if (ceiling) {
ceiling &= PGDIR_MASK;
if (!ceiling)
return;
}
if (end - 1 > ceiling - 1)
return;
pud = pud_offset(pgd, start);
pgd_clear(pgd);
pud_free_tlb(tlb, pud);
}
/*
* This function frees user-level page tables of a process.
*
* Must be called with pagetable lock held.
*/
static inline void free_pgd_range(struct mmu_gather *tlb,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
pgd_t *pgd;
unsigned long next;
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.
*/
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;
pgd = pgd_offset(tlb->mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
free_pud_range(tlb, pgd, addr, next, floor, ceiling);
} while (pgd++, addr = next, addr != end);
if (!tlb_is_full_mm(tlb))
flush_tlb_pgtables(tlb->mm, start, end);
}
void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
unsigned long floor, unsigned long ceiling)
{
while (vma) {
struct vm_area_struct *next = vma->vm_next;
unsigned long addr = vma->vm_start;
/* Optimization: gather nearby vmas into a single call down */
while (next && next->vm_start <= vma->vm_end + PMD_SIZE) {
vma = next;
next = vma->vm_next;
}
free_pgd_range(*tlb, addr, vma->vm_end,
floor, next? next->vm_start: ceiling);
vma = next;
}
}
pte_t fastcall * pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
{
if (!pmd_present(*pmd)) {
struct page *new;
spin_unlock(&mm->page_table_lock);
new = pte_alloc_one(mm, address);
spin_lock(&mm->page_table_lock);
if (!new)
return NULL;
/*
* Because we dropped the lock, we should re-check the
* entry, as somebody else could have populated it..
*/
if (pmd_present(*pmd)) {
pte_free(new);
goto out;
}
mm->nr_ptes++;
inc_page_state(nr_page_table_pages);
pmd_populate(mm, pmd, new);
}
out:
return pte_offset_map(pmd, address);
}
pte_t fastcall * pte_alloc_kernel(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
{
if (!pmd_present(*pmd)) {
pte_t *new;
spin_unlock(&mm->page_table_lock);
new = pte_alloc_one_kernel(mm, address);
spin_lock(&mm->page_table_lock);
if (!new)
return NULL;
/*
* Because we dropped the lock, we should re-check the
* entry, as somebody else could have populated it..
*/
if (pmd_present(*pmd)) {
pte_free_kernel(new);
goto out;
}
pmd_populate_kernel(mm, pmd, new);
}
out:
return pte_offset_kernel(pmd, address);
}
/*
* 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.
*
* dst->page_table_lock is held on entry and exit,
* but may be dropped within p[mg]d_alloc() and pte_alloc_map().
*/
static inline void
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte_t *dst_pte, pte_t *src_pte, unsigned long vm_flags,
unsigned long addr)
{
pte_t pte = *src_pte;
struct page *page;
unsigned long pfn;
/* pte contains position in swap or file, so copy. */
if (unlikely(!pte_present(pte))) {
if (!pte_file(pte)) {
swap_duplicate(pte_to_swp_entry(pte));
/* make sure dst_mm is on swapoff's mmlist. */
if (unlikely(list_empty(&dst_mm->mmlist))) {
spin_lock(&mmlist_lock);
list_add(&dst_mm->mmlist, &src_mm->mmlist);
spin_unlock(&mmlist_lock);
}
}
set_pte_at(dst_mm, addr, dst_pte, pte);
return;
}
pfn = pte_pfn(pte);
/* the pte points outside of valid memory, the
* mapping is assumed to be good, meaningful
* and not mapped via rmap - duplicate the
* mapping as is.
*/
page = NULL;
if (pfn_valid(pfn))
page = pfn_to_page(pfn);
if (!page || PageReserved(page)) {
set_pte_at(dst_mm, addr, dst_pte, pte);
return;
}
/*
* If it's a COW mapping, write protect it both
* in the parent and the child
*/
if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) {
ptep_set_wrprotect(src_mm, addr, src_pte);
pte = *src_pte;
}
/*
* If it's a shared mapping, mark it clean in
* the child
*/
if (vm_flags & VM_SHARED)
pte = pte_mkclean(pte);
pte = pte_mkold(pte);
get_page(page);
inc_mm_counter(dst_mm, rss);
if (PageAnon(page))
inc_mm_counter(dst_mm, anon_rss);
set_pte_at(dst_mm, addr, dst_pte, pte);
page_dup_rmap(page);
}
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;
unsigned long vm_flags = vma->vm_flags;
int progress;
again:
dst_pte = pte_alloc_map(dst_mm, dst_pmd, addr);
if (!dst_pte)
return -ENOMEM;
src_pte = pte_offset_map_nested(src_pmd, addr);
progress = 0;
spin_lock(&src_mm->page_table_lock);
do {
/*
* We are holding two locks at this point - either of them
* could generate latencies in another task on another CPU.
*/
if (progress >= 32 && (need_resched() ||
need_lockbreak(&src_mm->page_table_lock) ||
need_lockbreak(&dst_mm->page_table_lock)))
break;
if (pte_none(*src_pte)) {
progress++;
continue;
}
copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vm_flags, addr);
progress += 8;
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
spin_unlock(&src_mm->page_table_lock);
pte_unmap_nested(src_pte - 1);
pte_unmap(dst_pte - 1);
cond_resched_lock(&dst_mm->page_table_lock);
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;
if (is_vm_hugetlb_page(vma))
return copy_hugetlb_page_range(dst_mm, src_mm, vma);
dst_pgd = pgd_offset(dst_mm, addr);
src_pgd = pgd_offset(src_mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(src_pgd))
continue;
if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
vma, addr, next))
return -ENOMEM;
} while (dst_pgd++, src_pgd++, addr = next, addr != end);
return 0;
}
static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
pte_t *pte;
pte = pte_offset_map(pmd, addr);
do {
pte_t ptent = *pte;
if (pte_none(ptent))
continue;
if (pte_present(ptent)) {
struct page *page = NULL;
unsigned long pfn = pte_pfn(ptent);
if (pfn_valid(pfn)) {
page = pfn_to_page(pfn);
if (PageReserved(page))
page = NULL;
}
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;
}
ptent = ptep_get_and_clear(tlb->mm, addr, pte);
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)
set_pte_at(tlb->mm, addr, pte,
pgoff_to_pte(page->index));
if (pte_dirty(ptent))
set_page_dirty(page);
if (PageAnon(page))
dec_mm_counter(tlb->mm, anon_rss);
else if (pte_young(ptent))
mark_page_accessed(page);
tlb->freed++;
page_remove_rmap(page);
tlb_remove_page(tlb, page);
continue;
}
/*
* If details->check_mapping, we leave swap entries;
* if details->nonlinear_vma, we leave file entries.
*/
if (unlikely(details))
continue;
if (!pte_file(ptent))
free_swap_and_cache(pte_to_swp_entry(ptent));
pte_clear(tlb->mm, addr, pte);
} while (pte++, addr += PAGE_SIZE, addr != end);
pte_unmap(pte - 1);
}
static inline void zap_pmd_range(struct mmu_gather *tlb, pud_t *pud,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
zap_pte_range(tlb, pmd, addr, next, details);
} while (pmd++, addr = next, addr != end);
}
static inline void zap_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
pud_t *pud;
unsigned long next;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
zap_pmd_range(tlb, pud, addr, next, details);
} while (pud++, addr = next, addr != end);
}
static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
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);
if (pgd_none_or_clear_bad(pgd))
continue;
zap_pud_range(tlb, pgd, addr, next, details);
} while (pgd++, addr = next, addr != end);
tlb_end_vma(tlb, vma);
}
#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
* @mm: the controlling mm_struct
* @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
*
* Returns the number of vma's which were covered by the unmapping.
*
* Unmap all pages in the vma list. Called under page_table_lock.
*
* We aim to not hold page_table_lock for too long (for scheduling latency
* reasons). So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
* 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.
*/
int unmap_vmas(struct mmu_gather **tlbp, struct mm_struct *mm,
struct vm_area_struct *vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
struct zap_details *details)
{
unsigned long zap_bytes = ZAP_BLOCK_SIZE;
unsigned long tlb_start = 0; /* For tlb_finish_mmu */
int tlb_start_valid = 0;
int ret = 0;
spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
int fullmm = tlb_is_full_mm(*tlbp);
for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
unsigned long start;
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;
ret++;
while (start != end) {
unsigned long block;
if (!tlb_start_valid) {
tlb_start = start;
tlb_start_valid = 1;
}
if (is_vm_hugetlb_page(vma)) {
block = end - start;
unmap_hugepage_range(vma, start, end);
} else {
block = min(zap_bytes, end - start);
unmap_page_range(*tlbp, vma, start,
start + block, details);
}
start += block;
zap_bytes -= block;
if ((long)zap_bytes > 0)
continue;
tlb_finish_mmu(*tlbp, tlb_start, start);
if (need_resched() ||
need_lockbreak(&mm->page_table_lock) ||
(i_mmap_lock && need_lockbreak(i_mmap_lock))) {
if (i_mmap_lock) {
/* must reset count of rss freed */
*tlbp = tlb_gather_mmu(mm, fullmm);
details->break_addr = start;
goto out;
}
spin_unlock(&mm->page_table_lock);
cond_resched();
spin_lock(&mm->page_table_lock);
}
*tlbp = tlb_gather_mmu(mm, fullmm);
tlb_start_valid = 0;
zap_bytes = ZAP_BLOCK_SIZE;
}
}
out:
return ret;
}
/**
* 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
*/
void zap_page_range(struct vm_area_struct *vma, unsigned long address,
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;
if (is_vm_hugetlb_page(vma)) {
zap_hugepage_range(vma, address, size);
return;
}
lru_add_drain();
spin_lock(&mm->page_table_lock);
tlb = tlb_gather_mmu(mm, 0);
unmap_vmas(&tlb, mm, vma, address, end, &nr_accounted, details);
tlb_finish_mmu(tlb, address, end);
spin_unlock(&mm->page_table_lock);
}
/*
* Do a quick page-table lookup for a single page.
* mm->page_table_lock must be held.
*/
static struct page *
__follow_page(struct mm_struct *mm, unsigned long address, int read, int write)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *ptep, pte;
unsigned long pfn;
struct page *page;
page = follow_huge_addr(mm, address, write);
if (! IS_ERR(page))
return page;
pgd = pgd_offset(mm, address);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
goto out;
pud = pud_offset(pgd, address);
if (pud_none(*pud) || unlikely(pud_bad(*pud)))
goto out;
pmd = pmd_offset(pud, address);
if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
goto out;
if (pmd_huge(*pmd))
return follow_huge_pmd(mm, address, pmd, write);
ptep = pte_offset_map(pmd, address);
if (!ptep)
goto out;
pte = *ptep;
pte_unmap(ptep);
if (pte_present(pte)) {
if (write && !pte_write(pte))
goto out;
if (read && !pte_read(pte))
goto out;
pfn = pte_pfn(pte);
if (pfn_valid(pfn)) {
page = pfn_to_page(pfn);
if (write && !pte_dirty(pte) && !PageDirty(page))
set_page_dirty(page);
mark_page_accessed(page);
return page;
}
}
out:
return NULL;
}
struct page *
follow_page(struct mm_struct *mm, unsigned long address, int write)
{
return __follow_page(mm, address, /*read*/0, write);
}
int
check_user_page_readable(struct mm_struct *mm, unsigned long address)
{
return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL;
}
EXPORT_SYMBOL(check_user_page_readable);
/*
* Given a physical address, is there a useful struct page pointing to
* it? This may become more complex in the future if we start dealing
* with IO-aperture pages for direct-IO.
*/
static inline struct page *get_page_map(struct page *page)
{
if (!pfn_valid(page_to_pfn(page)))
return NULL;
return page;
}
static inline int
untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
/* Check if the vma is for an anonymous mapping. */
if (vma->vm_ops && vma->vm_ops->nopage)
return 0;
/* Check if page directory entry exists. */
pgd = pgd_offset(mm, address);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
return 1;
pud = pud_offset(pgd, address);
if (pud_none(*pud) || unlikely(pud_bad(*pud)))
return 1;
/* Check if page middle directory entry exists. */
pmd = pmd_offset(pud, address);
if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
return 1;
/* There is a pte slot for 'address' in 'mm'. */
return 0;
}
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int len, int write, int force,
struct page **pages, struct vm_area_struct **vmas)
{
int i;
unsigned int flags;
/*
* Require read or write permissions.
* If 'force' is set, we only require the "MAY" flags.
*/
flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
i = 0;
do {
struct vm_area_struct * vma;
vma = find_extend_vma(mm, start);
if (!vma && in_gate_area(tsk, start)) {
unsigned long pg = start & PAGE_MASK;
struct vm_area_struct *gate_vma = get_gate_vma(tsk);
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
if (write) /* user gate pages are read-only */
return i ? : -EFAULT;
if (pg > TASK_SIZE)
pgd = pgd_offset_k(pg);
else
pgd = pgd_offset_gate(mm, pg);
BUG_ON(pgd_none(*pgd));
pud = pud_offset(pgd, pg);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, pg);
BUG_ON(pmd_none(*pmd));
pte = pte_offset_map(pmd, pg);
BUG_ON(pte_none(*pte));
if (pages) {
pages[i] = pte_page(*pte);
get_page(pages[i]);
}
pte_unmap(pte);
if (vmas)
vmas[i] = gate_vma;
i++;
start += PAGE_SIZE;
len--;
continue;
}
if (!vma || (vma->vm_flags & VM_IO)
|| !(flags & vma->vm_flags))
return i ? : -EFAULT;
if (is_vm_hugetlb_page(vma)) {
i = follow_hugetlb_page(mm, vma, pages, vmas,
&start, &len, i);
continue;
}
spin_lock(&mm->page_table_lock);
do {
struct page *map;
int lookup_write = write;
cond_resched_lock(&mm->page_table_lock);
while (!(map = follow_page(mm, start, lookup_write))) {
/*
* Shortcut for anonymous pages. We don't want
* to force the creation of pages tables for
* insanly big anonymously mapped areas that
* nobody touched so far. This is important
* for doing a core dump for these mappings.
*/
if (!lookup_write &&
untouched_anonymous_page(mm,vma,start)) {
map = ZERO_PAGE(start);
break;
}
spin_unlock(&mm->page_table_lock);
switch (handle_mm_fault(mm,vma,start,write)) {
case VM_FAULT_MINOR:
tsk->min_flt++;
break;
case VM_FAULT_MAJOR:
tsk->maj_flt++;
break;
case VM_FAULT_SIGBUS:
return i ? i : -EFAULT;
case VM_FAULT_OOM:
return i ? i : -ENOMEM;
default:
BUG();
}
/*
* Now that we have performed a write fault
* and surely no longer have a shared page we
* shouldn't write, we shouldn't ignore an
* unwritable page in the page table if
* we are forcing write access.
*/
lookup_write = write && !force;
spin_lock(&mm->page_table_lock);
}
if (pages) {
pages[i] = get_page_map(map);
if (!pages[i]) {
spin_unlock(&mm->page_table_lock);
while (i--)
page_cache_release(pages[i]);
i = -EFAULT;
goto out;
}
flush_dcache_page(pages[i]);
if (!PageReserved(pages[i]))
page_cache_get(pages[i]);
}
if (vmas)
vmas[i] = vma;
i++;
start += PAGE_SIZE;
len--;
} while(len && start < vma->vm_end);
spin_unlock(&mm->page_table_lock);
} while(len);
out:
return i;
}
EXPORT_SYMBOL(get_user_pages);
static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t prot)
{
pte_t *pte;
pte = pte_alloc_map(mm, pmd, addr);
if (!pte)
return -ENOMEM;
do {
pte_t zero_pte = pte_wrprotect(mk_pte(ZERO_PAGE(addr), prot));
BUG_ON(!pte_none(*pte));
set_pte_at(mm, addr, pte, zero_pte);
} while (pte++, addr += PAGE_SIZE, addr != end);
pte_unmap(pte - 1);
return 0;
}
static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
unsigned long addr, unsigned long end, pgprot_t prot)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_alloc(mm, pud, addr);
if (!pmd)
return -ENOMEM;
do {
next = pmd_addr_end(addr, end);
if (zeromap_pte_range(mm, pmd, addr, next, prot))
return -ENOMEM;
} while (pmd++, addr = next, addr != end);
return 0;
}
static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
unsigned long addr, unsigned long end, pgprot_t prot)
{
pud_t *pud;
unsigned long next;
pud = pud_alloc(mm, pgd, addr);
if (!pud)
return -ENOMEM;
do {
next = pud_addr_end(addr, end);
if (zeromap_pmd_range(mm, pud, addr, next, prot))
return -ENOMEM;
} while (pud++, addr = next, addr != end);
return 0;
}
int zeromap_page_range(struct vm_area_struct *vma,
unsigned long addr, unsigned long size, pgprot_t prot)
{
pgd_t *pgd;
unsigned long next;
unsigned long end = addr + size;
struct mm_struct *mm = vma->vm_mm;
int err;
BUG_ON(addr >= end);
pgd = pgd_offset(mm, addr);
flush_cache_range(vma, addr, end);
spin_lock(&mm->page_table_lock);
do {
next = pgd_addr_end(addr, end);
err = zeromap_pud_range(mm, pgd, addr, next, prot);
if (err)
break;
} while (pgd++, addr = next, addr != end);
spin_unlock(&mm->page_table_lock);
return err;
}
/*
* 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;
pte = pte_alloc_map(mm, pmd, addr);
if (!pte)
return -ENOMEM;
do {
BUG_ON(!pte_none(*pte));
if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn)))
set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
pfn++;
} while (pte++, addr += PAGE_SIZE, addr != end);
pte_unmap(pte - 1);
return 0;
}
static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
unsigned long addr, unsigned long end,
unsigned long pfn, pgprot_t prot)
{
pmd_t *pmd;
unsigned long next;
pfn -= addr >> PAGE_SHIFT;
pmd = pmd_alloc(mm, pud, addr);
if (!pmd)
return -ENOMEM;
do {
next = pmd_addr_end(addr, end);
if (remap_pte_range(mm, pmd, addr, next,
pfn + (addr >> PAGE_SHIFT), prot))
return -ENOMEM;
} while (pmd++, addr = next, addr != end);
return 0;
}
static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
unsigned long addr, unsigned long end,
unsigned long pfn, pgprot_t prot)
{
pud_t *pud;
unsigned long next;
pfn -= addr >> PAGE_SHIFT;
pud = pud_alloc(mm, pgd, addr);
if (!pud)
return -ENOMEM;
do {
next = pud_addr_end(addr, end);
if (remap_pmd_range(mm, pud, addr, next,
pfn + (addr >> PAGE_SHIFT), prot))
return -ENOMEM;
} while (pud++, addr = next, addr != end);
return 0;
}
/* Note: this is only safe if the mm semaphore is held when called. */
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t prot)
{
pgd_t *pgd;
unsigned long next;
unsigned long end = addr + size;
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).
* VM_RESERVED tells swapout not to try to touch
* this region.
*/
vma->vm_flags |= VM_IO | VM_RESERVED;
BUG_ON(addr >= end);
pfn -= addr >> PAGE_SHIFT;
pgd = pgd_offset(mm, addr);
flush_cache_range(vma, addr, end);
spin_lock(&mm->page_table_lock);
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);
spin_unlock(&mm->page_table_lock);
return err;
}
EXPORT_SYMBOL(remap_pfn_range);
/*
* 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;
}
/*
* We hold the mm semaphore for reading and vma->vm_mm->page_table_lock
*/
static inline void break_cow(struct vm_area_struct * vma, struct page * new_page, unsigned long address,
pte_t *page_table)
{
pte_t entry;
entry = maybe_mkwrite(pte_mkdirty(mk_pte(new_page, vma->vm_page_prot)),
vma);
ptep_establish(vma, address, page_table, entry);
update_mmu_cache(vma, address, entry);
lazy_mmu_prot_update(entry);
}
/*
* 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.
*
* Goto-purists beware: the only reason for goto's here is that it results
* in better assembly code.. The "default" path will see no jumps at all.
*
* 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.
*
* We hold the mm semaphore and the page_table_lock on entry and exit
* with the page_table_lock released.
*/
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
unsigned long address, pte_t *page_table, pmd_t *pmd, pte_t pte)
{
struct page *old_page, *new_page;
unsigned long pfn = pte_pfn(pte);
pte_t entry;
if (unlikely(!pfn_valid(pfn))) {
/*
* This should really halt the system so it can be debugged or
* at least the kernel stops what it's doing before it corrupts
* data, but for the moment just pretend this is OOM.
*/
pte_unmap(page_table);
printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n",
address);
spin_unlock(&mm->page_table_lock);
return VM_FAULT_OOM;
}
old_page = pfn_to_page(pfn);
if (!TestSetPageLocked(old_page)) {
int reuse = can_share_swap_page(old_page);
unlock_page(old_page);
if (reuse) {
flush_cache_page(vma, address, pfn);
entry = maybe_mkwrite(pte_mkyoung(pte_mkdirty(pte)),
vma);
ptep_set_access_flags(vma, address, page_table, entry, 1);
update_mmu_cache(vma, address, entry);
lazy_mmu_prot_update(entry);
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
return VM_FAULT_MINOR;
}
}
pte_unmap(page_table);
/*
* Ok, we need to copy. Oh, well..
*/
if (!PageReserved(old_page))
page_cache_get(old_page);
spin_unlock(&mm->page_table_lock);
if (unlikely(anon_vma_prepare(vma)))
goto no_new_page;
if (old_page == ZERO_PAGE(address)) {
new_page = alloc_zeroed_user_highpage(vma, address);
if (!new_page)
goto no_new_page;
} else {
new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
if (!new_page)
goto no_new_page;
copy_user_highpage(new_page, old_page, address);
}
/*
* Re-check the pte - we dropped the lock
*/
spin_lock(&mm->page_table_lock);
page_table = pte_offset_map(pmd, address);
if (likely(pte_same(*page_table, pte))) {
if (PageAnon(old_page))
dec_mm_counter(mm, anon_rss);
if (PageReserved(old_page))
inc_mm_counter(mm, rss);
else
page_remove_rmap(old_page);
flush_cache_page(vma, address, pfn);
break_cow(vma, new_page, address, page_table);
lru_cache_add_active(new_page);
page_add_anon_rmap(new_page, vma, address);
/* Free the old page.. */
new_page = old_page;
}
pte_unmap(page_table);
page_cache_release(new_page);
page_cache_release(old_page);
spin_unlock(&mm->page_table_lock);
return VM_FAULT_MINOR;
no_new_page:
page_cache_release(old_page);
return VM_FAULT_OOM;
}
/*
* 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
* large vma, note the break_addr set by unmap_vmas when it breaks out:
* and restart from that address when we reach that vma again. It might
* have been split or merged, shrunk or extended, but never shifted: so
* restart_addr remains valid so long as it remains in the vma's range.
* unmap_mapping_range forces truncate_count to leap over page-aligned
* values so we can save vma's restart_addr in its truncate_count field.
*/
#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
static void reset_vma_truncate_counts(struct address_space *mapping)
{
struct vm_area_struct *vma;
struct prio_tree_iter iter;
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
vma->vm_truncate_count = 0;
list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
vma->vm_truncate_count = 0;
}
static int unmap_mapping_range_vma(struct vm_area_struct *vma,
unsigned long start_addr, unsigned long end_addr,
struct zap_details *details)
{
unsigned long restart_addr;
int need_break;
again:
restart_addr = vma->vm_truncate_count;
if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
start_addr = restart_addr;
if (start_addr >= end_addr) {
/* Top of vma has been split off since last time */
vma->vm_truncate_count = details->truncate_count;
return 0;
}
}
details->break_addr = end_addr;
zap_page_range(vma, start_addr, end_addr - start_addr, details);
/*
* We cannot rely on the break test in unmap_vmas:
* on the one hand, we don't want to restart our loop
* just because that broke out for the page_table_lock;
* on the other hand, it does no test when vma is small.
*/
need_break = need_resched() ||
need_lockbreak(details->i_mmap_lock);
if (details->break_addr >= end_addr) {
/* 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 */
vma->vm_truncate_count = details->break_addr;
if (!need_break)
goto again;
}
spin_unlock(details->i_mmap_lock);
cond_resched();
spin_lock(details->i_mmap_lock);
return -EINTR;
}
static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
struct zap_details *details)
{
struct vm_area_struct *vma;
struct prio_tree_iter iter;
pgoff_t vba, vea, zba, zea;
restart:
vma_prio_tree_foreach(vma, &iter, root,
details->first_index, details->last_index) {
/* Skip quickly over those we have already dealt with */
if (vma->vm_truncate_count == details->truncate_count)
continue;
vba = vma->vm_pgoff;
vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
zba = details->first_index;
if (zba < vba)
zba = vba;
zea = details->last_index;
if (zea > vea)
zea = vea;
if (unmap_mapping_range_vma(vma,
((zba - vba) << PAGE_SHIFT) + vma->vm_start,
((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
details) < 0)
goto restart;
}
}
static inline void unmap_mapping_range_list(struct list_head *head,
struct zap_details *details)
{
struct vm_area_struct *vma;
/*
* In nonlinear VMAs there is no correspondence between virtual address
* offset and file offset. So we must perform an exhaustive search
* across *all* the pages in each nonlinear VMA, not just the pages
* whose virtual address lies outside the file truncation point.
*/
restart:
list_for_each_entry(vma, head, shared.vm_set.list) {
/* Skip quickly over those we have already dealt with */
if (vma->vm_truncate_count == details->truncate_count)
continue;
details->nonlinear_vma = vma;
if (unmap_mapping_range_vma(vma, vma->vm_start,
vma->vm_end, details) < 0)
goto restart;
}
}
/**
* unmap_mapping_range - unmap the portion of all mmaps
* in the specified address_space corresponding to the specified
* page range in the underlying file.
* @address_space: the address space containing mmaps to be unmapped.
* @holebegin: byte in first page to unmap, relative to the start of
* the underlying file. This will be rounded down to a PAGE_SIZE
* boundary. Note that this is different from vmtruncate(), which
* must keep the partial page. In contrast, we must get rid of
* partial pages.
* @holelen: size of prospective hole in bytes. This will be rounded
* up to a PAGE_SIZE boundary. A holelen of zero truncates to the
* end of the file.
* @even_cows: 1 when truncating a file, unmap even private COWed pages;
* but 0 when invalidating pagecache, don't throw away private data.
*/
void unmap_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen, int even_cows)
{
struct zap_details details;
pgoff_t hba = holebegin >> PAGE_SHIFT;
pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
/* Check for overflow. */
if (sizeof(holelen) > sizeof(hlen)) {
long long holeend =
(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (holeend & ~(long long)ULONG_MAX)
hlen = ULONG_MAX - hba + 1;
}
details.check_mapping = even_cows? NULL: mapping;
details.nonlinear_vma = NULL;
details.first_index = hba;
details.last_index = hba + hlen - 1;
if (details.last_index < details.first_index)
details.last_index = ULONG_MAX;
details.i_mmap_lock = &mapping->i_mmap_lock;
spin_lock(&mapping->i_mmap_lock);
/* serialize i_size write against truncate_count write */
smp_wmb();
/* Protect against page faults, and endless unmapping loops */
mapping->truncate_count++;
/*
* For archs where spin_lock has inclusive semantics like ia64
* this smp_mb() will prevent to read pagetable contents
* before the truncate_count increment is visible to
* other cpus.
*/
smp_mb();
if (unlikely(is_restart_addr(mapping->truncate_count))) {
if (mapping->truncate_count == 0)
reset_vma_truncate_counts(mapping);
mapping->truncate_count++;
}
details.truncate_count = mapping->truncate_count;
if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
unmap_mapping_range_tree(&mapping->i_mmap, &details);
if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
spin_unlock(&mapping->i_mmap_lock);
}
EXPORT_SYMBOL(unmap_mapping_range);
/*
* Handle all mappings that got truncated by a "truncate()"
* system call.
*
* NOTE! We have to be ready to update the memory sharing
* between the file and the memory map for a potential last
* incomplete page. Ugly, but necessary.
*/
int vmtruncate(struct inode * inode, loff_t offset)
{
struct address_space *mapping = inode->i_mapping;
unsigned long limit;
if (inode->i_size < offset)
goto do_expand;
/*
* truncation of in-use swapfiles is disallowed - it would cause
* subsequent swapout to scribble on the now-freed blocks.
*/
if (IS_SWAPFILE(inode))
goto out_busy;
i_size_write(inode, offset);
unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
truncate_inode_pages(mapping, offset);
goto out_truncate;
do_expand:
limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
if (limit != RLIM_INFINITY && offset > limit)
goto out_sig;
if (offset > inode->i_sb->s_maxbytes)
goto out_big;
i_size_write(inode, offset);
out_truncate:
if (inode->i_op && inode->i_op->truncate)
inode->i_op->truncate(inode);
return 0;
out_sig:
send_sig(SIGXFSZ, current, 0);
out_big:
return -EFBIG;
out_busy:
return -ETXTBSY;
}
EXPORT_SYMBOL(vmtruncate);
/*
* Primitive swap readahead code. We simply read an aligned block of
* (1 << page_cluster) entries in the swap area. This method is chosen
* because it doesn't cost us any seek time. We also make sure to queue
* the 'original' request together with the readahead ones...
*
* This has been extended to use the NUMA policies from the mm triggering
* the readahead.
*
* Caller must hold down_read on the vma->vm_mm if vma is not NULL.
*/
void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
{
#ifdef CONFIG_NUMA
struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
#endif
int i, num;
struct page *new_page;
unsigned long offset;
/*
* Get the number of handles we should do readahead io to.
*/
num = valid_swaphandles(entry, &offset);
for (i = 0; i < num; offset++, i++) {
/* Ok, do the async read-ahead now */
new_page = read_swap_cache_async(swp_entry(swp_type(entry),
offset), vma, addr);
if (!new_page)
break;
page_cache_release(new_page);
#ifdef CONFIG_NUMA
/*
* Find the next applicable VMA for the NUMA policy.
*/
addr += PAGE_SIZE;
if (addr == 0)
vma = NULL;
if (vma) {
if (addr >= vma->vm_end) {
vma = next_vma;
next_vma = vma ? vma->vm_next : NULL;
}
if (vma && addr < vma->vm_start)
vma = NULL;
} else {
if (next_vma && addr >= next_vma->vm_start) {
vma = next_vma;
next_vma = vma->vm_next;
}
}
#endif
}
lru_add_drain(); /* Push any new pages onto the LRU now */
}
/*
* We hold the mm semaphore and the page_table_lock on entry and
* should release the pagetable lock on exit..
*/
static int do_swap_page(struct mm_struct * mm,
struct vm_area_struct * vma, unsigned long address,
pte_t *page_table, pmd_t *pmd, pte_t orig_pte, int write_access)
{
struct page *page;
swp_entry_t entry = pte_to_swp_entry(orig_pte);
pte_t pte;
int ret = VM_FAULT_MINOR;
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
page = lookup_swap_cache(entry);
if (!page) {
swapin_readahead(entry, address, vma);
page = read_swap_cache_async(entry, vma, address);
if (!page) {
/*
* Back out if somebody else faulted in this pte while
* we released the page table lock.
*/
spin_lock(&mm->page_table_lock);
page_table = pte_offset_map(pmd, address);
if (likely(pte_same(*page_table, orig_pte)))
ret = VM_FAULT_OOM;
else
ret = VM_FAULT_MINOR;
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
goto out;
}
/* Had to read the page from swap area: Major fault */
ret = VM_FAULT_MAJOR;
inc_page_state(pgmajfault);
grab_swap_token();
}
mark_page_accessed(page);
lock_page(page);
/*
* Back out if somebody else faulted in this pte while we
* released the page table lock.
*/
spin_lock(&mm->page_table_lock);
page_table = pte_offset_map(pmd, address);
if (unlikely(!pte_same(*page_table, orig_pte))) {
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
unlock_page(page);
page_cache_release(page);
ret = VM_FAULT_MINOR;
goto out;
}
/* The page isn't present yet, go ahead with the fault. */
swap_free(entry);
if (vm_swap_full())
remove_exclusive_swap_page(page);
inc_mm_counter(mm, rss);
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;
}
unlock_page(page);
flush_icache_page(vma, page);
set_pte_at(mm, address, page_table, pte);
page_add_anon_rmap(page, vma, address);
if (write_access) {
if (do_wp_page(mm, vma, address,
page_table, pmd, pte) == VM_FAULT_OOM)
ret = VM_FAULT_OOM;
goto out;
}
/* No need to invalidate - it was non-present before */
update_mmu_cache(vma, address, pte);
lazy_mmu_prot_update(pte);
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
out:
return ret;
}
/*
* We are called with the MM semaphore and page_table_lock
* spinlock held to protect against concurrent faults in
* multithreaded programs.
*/
static int
do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
pte_t *page_table, pmd_t *pmd, int write_access,
unsigned long addr)
{
pte_t entry;
struct page * page = ZERO_PAGE(addr);
/* Read-only mapping of ZERO_PAGE. */
entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot));
/* ..except if it's a write access */
if (write_access) {
/* Allocate our own private page. */
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
if (unlikely(anon_vma_prepare(vma)))
goto no_mem;
page = alloc_zeroed_user_highpage(vma, addr);
if (!page)
goto no_mem;
spin_lock(&mm->page_table_lock);
page_table = pte_offset_map(pmd, addr);
if (!pte_none(*page_table)) {
pte_unmap(page_table);
page_cache_release(page);
spin_unlock(&mm->page_table_lock);
goto out;
}
inc_mm_counter(mm, rss);
entry = maybe_mkwrite(pte_mkdirty(mk_pte(page,
vma->vm_page_prot)),
vma);
lru_cache_add_active(page);
SetPageReferenced(page);
page_add_anon_rmap(page, vma, addr);
}
set_pte_at(mm, addr, page_table, entry);
pte_unmap(page_table);
/* No need to invalidate - it was non-present before */
update_mmu_cache(vma, addr, entry);
lazy_mmu_prot_update(entry);
spin_unlock(&mm->page_table_lock);
out:
return VM_FAULT_MINOR;
no_mem:
return VM_FAULT_OOM;
}
/*
* do_no_page() tries to create a new page mapping. It aggressively
* tries to share with existing pages, but makes a separate copy if
* the "write_access" parameter is true in order to avoid the next
* page fault.
*
* As this is called only for pages that do not currently exist, we
* do not need to flush old virtual caches or the TLB.
*
* This is called with the MM semaphore held and the page table
* spinlock held. Exit with the spinlock released.
*/
static int
do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, int write_access, pte_t *page_table, pmd_t *pmd)
{
struct page * new_page;
struct address_space *mapping = NULL;
pte_t entry;
unsigned int sequence = 0;
int ret = VM_FAULT_MINOR;
int anon = 0;
if (!vma->vm_ops || !vma->vm_ops->nopage)
return do_anonymous_page(mm, vma, page_table,
pmd, write_access, address);
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
sequence = mapping->truncate_count;
smp_rmb(); /* serializes i_size against truncate_count */
}
retry:
cond_resched();
new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
/*
* No smp_rmb is needed here as long as there's a full
* spin_lock/unlock sequence inside the ->nopage callback
* (for the pagecache lookup) that acts as an implicit
* smp_mb() and prevents the i_size read to happen
* after the next truncate_count read.
*/
/* no page was available -- either SIGBUS or OOM */
if (new_page == NOPAGE_SIGBUS)
return VM_FAULT_SIGBUS;
if (new_page == NOPAGE_OOM)
return VM_FAULT_OOM;
/*
* Should we do an early C-O-W break?
*/
if (write_access && !(vma->vm_flags & VM_SHARED)) {
struct page *page;
if (unlikely(anon_vma_prepare(vma)))
goto oom;
page = alloc_page_vma(GFP_HIGHUSER, vma, address);
if (!page)
goto oom;
copy_user_highpage(page, new_page, address);
page_cache_release(new_page);
new_page = page;
anon = 1;
}
spin_lock(&mm->page_table_lock);
/*
* For a file-backed vma, someone could have truncated or otherwise
* invalidated this page. If unmap_mapping_range got called,
* retry getting the page.
*/
if (mapping && unlikely(sequence != mapping->truncate_count)) {
sequence = mapping->truncate_count;
spin_unlock(&mm->page_table_lock);
page_cache_release(new_page);
goto retry;
}
page_table = pte_offset_map(pmd, address);
/*
* This silly early PAGE_DIRTY setting removes a race
* due to the bad i386 page protection. But it's valid
* for other architectures too.
*
* Note that if write_access is true, we either now have
* an exclusive copy of the page, or this is a shared mapping,
* so we can make it writable and dirty to avoid having to
* handle that later.
*/
/* Only go through if we didn't race with anybody else... */
if (pte_none(*page_table)) {
if (!PageReserved(new_page))
inc_mm_counter(mm, rss);
flush_icache_page(vma, new_page);
entry = mk_pte(new_page, vma->vm_page_prot);
if (write_access)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
set_pte_at(mm, address, page_table, entry);
if (anon) {
lru_cache_add_active(new_page);
page_add_anon_rmap(new_page, vma, address);
} else
page_add_file_rmap(new_page);
pte_unmap(page_table);
} else {
/* One of our sibling threads was faster, back out. */
pte_unmap(page_table);
page_cache_release(new_page);
spin_unlock(&mm->page_table_lock);
goto out;
}
/* no need to invalidate: a not-present page shouldn't be cached */
update_mmu_cache(vma, address, entry);
lazy_mmu_prot_update(entry);
spin_unlock(&mm->page_table_lock);
out:
return ret;
oom:
page_cache_release(new_page);
ret = VM_FAULT_OOM;
goto out;
}
/*
* Fault of a previously existing named mapping. Repopulate the pte
* from the encoded file_pte if possible. This enables swappable
* nonlinear vmas.
*/
static int do_file_page(struct mm_struct * mm, struct vm_area_struct * vma,
unsigned long address, int write_access, pte_t *pte, pmd_t *pmd)
{
unsigned long pgoff;
int err;
BUG_ON(!vma->vm_ops || !vma->vm_ops->nopage);
/*
* Fall back to the linear mapping if the fs does not support
* ->populate:
*/
if (!vma->vm_ops || !vma->vm_ops->populate ||
(write_access && !(vma->vm_flags & VM_SHARED))) {
pte_clear(mm, address, pte);
return do_no_page(mm, vma, address, write_access, pte, pmd);
}
pgoff = pte_to_pgoff(*pte);
pte_unmap(pte);
spin_unlock(&mm->page_table_lock);
err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, vma->vm_page_prot, pgoff, 0);
if (err == -ENOMEM)
return VM_FAULT_OOM;
if (err)
return VM_FAULT_SIGBUS;
return VM_FAULT_MAJOR;
}
/*
* These routines also need to handle stuff like marking pages dirty
* and/or accessed for architectures that don't do it in hardware (most
* RISC architectures). The early dirtying is also good on the i386.
*
* There is also a hook called "update_mmu_cache()" that architectures
* with external mmu caches can use to update those (ie the Sparc or
* PowerPC hashed page tables that act as extended TLBs).
*
* Note the "page_table_lock". It is to protect against kswapd removing
* pages from under us. Note that kswapd only ever _removes_ pages, never
* adds them. As such, once we have noticed that the page is not present,
* we can drop the lock early.
*
* The adding of pages is protected by the MM semaphore (which we hold),
* so we don't need to worry about a page being suddenly been added into
* our VM.
*
* We enter with the pagetable spinlock held, we are supposed to
* release it when done.
*/
static inline int handle_pte_fault(struct mm_struct *mm,
struct vm_area_struct * vma, unsigned long address,
int write_access, pte_t *pte, pmd_t *pmd)
{
pte_t entry;
entry = *pte;
if (!pte_present(entry)) {
/*
* If it truly wasn't present, we know that kswapd
* and the PTE updates will not touch it later. So
* drop the lock.
*/
if (pte_none(entry))
return do_no_page(mm, vma, address, write_access, pte, pmd);
if (pte_file(entry))
return do_file_page(mm, vma, address, write_access, pte, pmd);
return do_swap_page(mm, vma, address, pte, pmd, entry, write_access);
}
if (write_access) {
if (!pte_write(entry))
return do_wp_page(mm, vma, address, pte, pmd, entry);
entry = pte_mkdirty(entry);
}
entry = pte_mkyoung(entry);
ptep_set_access_flags(vma, address, pte, entry, write_access);
update_mmu_cache(vma, address, entry);
lazy_mmu_prot_update(entry);
pte_unmap(pte);
spin_unlock(&mm->page_table_lock);
return VM_FAULT_MINOR;
}
/*
* By the time we get here, we already hold the mm semaphore
*/
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma,
unsigned long address, int write_access)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
__set_current_state(TASK_RUNNING);
inc_page_state(pgfault);
if (is_vm_hugetlb_page(vma))
return VM_FAULT_SIGBUS; /* mapping truncation does this. */
/*
* We need the page table lock to synchronize with kswapd
* and the SMP-safe atomic PTE updates.
*/
pgd = pgd_offset(mm, address);
spin_lock(&mm->page_table_lock);
pud = pud_alloc(mm, pgd, address);
if (!pud)
goto oom;
pmd = pmd_alloc(mm, pud, address);
if (!pmd)
goto oom;
pte = pte_alloc_map(mm, pmd, address);
if (!pte)
goto oom;
return handle_pte_fault(mm, vma, address, write_access, pte, pmd);
oom:
spin_unlock(&mm->page_table_lock);
return VM_FAULT_OOM;
}
#ifndef __PAGETABLE_PUD_FOLDED
/*
* Allocate page upper directory.
*
* We've already handled the fast-path in-line, and we own the
* page table lock.
*/
pud_t fastcall *__pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
pud_t *new;
spin_unlock(&mm->page_table_lock);
new = pud_alloc_one(mm, address);
spin_lock(&mm->page_table_lock);
if (!new)
return NULL;
/*
* Because we dropped the lock, we should re-check the
* entry, as somebody else could have populated it..
*/
if (pgd_present(*pgd)) {
pud_free(new);
goto out;
}
pgd_populate(mm, pgd, new);
out:
return pud_offset(pgd, address);
}
#endif /* __PAGETABLE_PUD_FOLDED */
#ifndef __PAGETABLE_PMD_FOLDED
/*
* Allocate page middle directory.
*
* We've already handled the fast-path in-line, and we own the
* page table lock.
*/
pmd_t fastcall *__pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
pmd_t *new;
spin_unlock(&mm->page_table_lock);
new = pmd_alloc_one(mm, address);
spin_lock(&mm->page_table_lock);
if (!new)
return NULL;
/*
* Because we dropped the lock, we should re-check the
* entry, as somebody else could have populated it..
*/
#ifndef __ARCH_HAS_4LEVEL_HACK
if (pud_present(*pud)) {
pmd_free(new);
goto out;
}
pud_populate(mm, pud, new);
#else
if (pgd_present(*pud)) {
pmd_free(new);
goto out;
}
pgd_populate(mm, pud, new);
#endif /* __ARCH_HAS_4LEVEL_HACK */
out:
return pmd_offset(pud, address);
}
#endif /* __PAGETABLE_PMD_FOLDED */
int make_pages_present(unsigned long addr, unsigned long end)
{
int ret, len, write;
struct vm_area_struct * vma;
vma = find_vma(current->mm, addr);
if (!vma)
return -1;
write = (vma->vm_flags & VM_WRITE) != 0;
if (addr >= end)
BUG();
if (end > vma->vm_end)
BUG();
len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
ret = get_user_pages(current, current->mm, addr,
len, write, 0, NULL, NULL);
if (ret < 0)
return ret;
return ret == len ? 0 : -1;
}
/*
* Map a vmalloc()-space virtual address to the physical page.
*/
struct page * vmalloc_to_page(void * vmalloc_addr)
{
unsigned long addr = (unsigned long) vmalloc_addr;
struct page *page = NULL;
pgd_t *pgd = pgd_offset_k(addr);
pud_t *pud;
pmd_t *pmd;
pte_t *ptep, pte;
if (!pgd_none(*pgd)) {
pud = pud_offset(pgd, addr);
if (!pud_none(*pud)) {
pmd = pmd_offset(pud, addr);
if (!pmd_none(*pmd)) {
ptep = pte_offset_map(pmd, addr);
pte = *ptep;
if (pte_present(pte))
page = pte_page(pte);
pte_unmap(ptep);
}
}
}
return page;
}
EXPORT_SYMBOL(vmalloc_to_page);
/*
* Map a vmalloc()-space virtual address to the physical page frame number.
*/
unsigned long vmalloc_to_pfn(void * vmalloc_addr)
{
return page_to_pfn(vmalloc_to_page(vmalloc_addr));
}
EXPORT_SYMBOL(vmalloc_to_pfn);
/*
* update_mem_hiwater
* - update per process rss and vm high water data
*/
void update_mem_hiwater(struct task_struct *tsk)
{
if (tsk->mm) {
unsigned long rss = get_mm_counter(tsk->mm, rss);
if (tsk->mm->hiwater_rss < rss)
tsk->mm->hiwater_rss = rss;
if (tsk->mm->hiwater_vm < tsk->mm->total_vm)
tsk->mm->hiwater_vm = tsk->mm->total_vm;
}
}
#if !defined(__HAVE_ARCH_GATE_AREA)
#if defined(AT_SYSINFO_EHDR)
struct vm_area_struct gate_vma;
static int __init gate_vma_init(void)
{
gate_vma.vm_mm = NULL;
gate_vma.vm_start = FIXADDR_USER_START;
gate_vma.vm_end = FIXADDR_USER_END;
gate_vma.vm_page_prot = PAGE_READONLY;
gate_vma.vm_flags = 0;
return 0;
}
__initcall(gate_vma_init);
#endif
struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
#ifdef AT_SYSINFO_EHDR
return &gate_vma;
#else
return NULL;
#endif
}
int in_gate_area_no_task(unsigned long addr)
{
#ifdef AT_SYSINFO_EHDR
if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
return 1;
#endif
return 0;
}
#endif /* __HAVE_ARCH_GATE_AREA */
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