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mm: make sure _PAGE_SWP_SOFT_DIRTY bit is not set on present pte 

_PAGE_SOFT_DIRTY bit should never be set on present pte so add VM_BUG_ON
to catch any potential future abuse.

Also add a comment on _PAGE_SWP_SOFT_DIRTY definition explaining scope of
its usage.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Cyrill Gorcunov 2013-09-11 14:22:47 -07:00 committed by Linus Torvalds
parent 5a53748568
commit fa0f281cf9
2 changed files with 22 additions and 15 deletions
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34
arch/x86/include/asm/pgtable.h
View File

@ -315,21 +315,6 @@ static inline pmd_t pmd_mksoft_dirty(pmd_t pmd)
return pmd_set_flags(pmd, _PAGE_SOFT_DIRTY);
}
static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
{
return pte_set_flags(pte, _PAGE_SWP_SOFT_DIRTY);
}
static inline int pte_swp_soft_dirty(pte_t pte)
{
return pte_flags(pte) & _PAGE_SWP_SOFT_DIRTY;
}
static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
{
return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY);
}
static inline pte_t pte_file_clear_soft_dirty(pte_t pte)
{
return pte_clear_flags(pte, _PAGE_SOFT_DIRTY);
@ -446,6 +431,7 @@ pte_t *populate_extra_pte(unsigned long vaddr);
#ifndef __ASSEMBLY__
#include <linux/mm_types.h>
#include <linux/mmdebug.h>
#include <linux/log2.h>
static inline int pte_none(pte_t pte)
@ -864,6 +850,24 @@ static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
{
}
static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
{
VM_BUG_ON(pte_present(pte));
return pte_set_flags(pte, _PAGE_SWP_SOFT_DIRTY);
}
static inline int pte_swp_soft_dirty(pte_t pte)
{
VM_BUG_ON(pte_present(pte));
return pte_flags(pte) & _PAGE_SWP_SOFT_DIRTY;
}
static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
{
VM_BUG_ON(pte_present(pte));
return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY);
}
#include <asm-generic/pgtable.h>
#endif /* __ASSEMBLY__ */

3
arch/x86/include/asm/pgtable_types.h
View File

@ -75,6 +75,9 @@
* with swap entry format. On x86 bits 6 and 7 are *not* involved
* into swap entry computation, but bit 6 is used for nonlinear
* file mapping, so we borrow bit 7 for soft dirty tracking.
*
* Please note that this bit must be treated as swap dirty page
* mark if and only if the PTE has present bit clear!
*/
#ifdef CONFIG_MEM_SOFT_DIRTY
#define _PAGE_SWP_SOFT_DIRTY _PAGE_PSE