iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[PATCH] mm: optimize the new mprotect() code a bit

Browse Source 
mprotect() resets the page protections, which could result in extra write
faults for those pages whose dirty state we track using write faults and are
dirty already.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Peter Zijlstra 2006-09-25 23:30:59 -07:00 committed by Linus Torvalds
parent edc79b2a46
commit c1e6098b23
1 changed files with 24 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
mm/mprotect.c
View File

@ -27,7 +27,8 @@
#include <asm/tlbflush.h> #include <asm/tlbflush.h>
static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot) unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{ {
pte_t *pte, oldpte; pte_t *pte, oldpte;
spinlock_t *ptl; spinlock_t *ptl;
@ -42,7 +43,14 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
* bits by wiping the pte and then setting the new pte * bits by wiping the pte and then setting the new pte
* into place. * into place.
*/ */
ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot); ptent = ptep_get_and_clear(mm, addr, pte);
ptent = pte_modify(ptent, newprot);
/*
* Avoid taking write faults for pages we know to be
* dirty.
*/
if (dirty_accountable && pte_dirty(ptent))
ptent = pte_mkwrite(ptent);
set_pte_at(mm, addr, pte, ptent); set_pte_at(mm, addr, pte, ptent);
lazy_mmu_prot_update(ptent); lazy_mmu_prot_update(ptent);
#ifdef CONFIG_MIGRATION #ifdef CONFIG_MIGRATION
@ -66,7 +74,8 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
} }
static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
unsigned long addr, unsigned long end, pgprot_t newprot) unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{ {
pmd_t *pmd; pmd_t *pmd;
unsigned long next; unsigned long next;
@ -76,12 +85,13 @@ static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
next = pmd_addr_end(addr, end); next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd)) if (pmd_none_or_clear_bad(pmd))
continue; continue;
change_pte_range(mm, pmd, addr, next, newprot); change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
} while (pmd++, addr = next, addr != end); } while (pmd++, addr = next, addr != end);
} }
static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
unsigned long addr, unsigned long end, pgprot_t newprot) unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{ {
pud_t *pud; pud_t *pud;
unsigned long next; unsigned long next;
@ -91,12 +101,13 @@ static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
next = pud_addr_end(addr, end); next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud)) if (pud_none_or_clear_bad(pud))
continue; continue;
change_pmd_range(mm, pud, addr, next, newprot); change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
} while (pud++, addr = next, addr != end); } while (pud++, addr = next, addr != end);
} }
static void change_protection(struct vm_area_struct *vma, static void change_protection(struct vm_area_struct *vma,
unsigned long addr, unsigned long end, pgprot_t newprot) unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{ {
struct mm_struct *mm = vma->vm_mm; struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd; pgd_t *pgd;
@ -110,7 +121,7 @@ static void change_protection(struct vm_area_struct *vma,
next = pgd_addr_end(addr, end); next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd)) if (pgd_none_or_clear_bad(pgd))
continue; continue;
change_pud_range(mm, pgd, addr, next, newprot); change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
} while (pgd++, addr = next, addr != end); } while (pgd++, addr = next, addr != end);
flush_tlb_range(vma, start, end); flush_tlb_range(vma, start, end);
} }
@ -125,6 +136,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
unsigned long charged = 0; unsigned long charged = 0;
pgoff_t pgoff; pgoff_t pgoff;
int error; int error;
int dirty_accountable = 0;
if (newflags == oldflags) { if (newflags == oldflags) {
*pprev = vma; *pprev = vma;
@ -181,14 +193,16 @@ success:
vma->vm_flags = newflags; vma->vm_flags = newflags;
vma->vm_page_prot = protection_map[newflags & vma->vm_page_prot = protection_map[newflags &
(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
if (vma_wants_writenotify(vma)) if (vma_wants_writenotify(vma)) {
vma->vm_page_prot = protection_map[newflags & vma->vm_page_prot = protection_map[newflags &
(VM_READ|VM_WRITE|VM_EXEC)]; (VM_READ|VM_WRITE|VM_EXEC)];
dirty_accountable = 1;
}
if (is_vm_hugetlb_page(vma)) if (is_vm_hugetlb_page(vma))
hugetlb_change_protection(vma, start, end, vma->vm_page_prot); hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
else else
change_protection(vma, start, end, vma->vm_page_prot); change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
vm_stat_account(mm, newflags, vma->vm_file, nrpages); vm_stat_account(mm, newflags, vma->vm_file, nrpages);
return 0; return 0;