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Commit fa0f281c authored by Cyrill Gorcunov's avatar Cyrill Gorcunov Committed by Linus Torvalds
Browse files

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: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Acked-by: default avatarPavel Emelyanov <xemul@parallels.com>
Acked-by: default avatarJan Beulich <jbeulich@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5a537485

arch/x86/include/asm/pgtable.h

+19 −15
Original line number Diff line number Diff line
@@ -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__ */

arch/x86/include/asm/pgtable_types.h

+3 −0
Original line number Diff line number Diff line
@@ -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