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Commit c137a275 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Linus Torvalds
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powerpc/mm/autonuma: switch ppc64 to its own implementation of saved write 

With this our protnone becomes a present pte with READ/WRITE/EXEC bit
cleared.  By default we also set _PAGE_PRIVILEGED on such pte.  This is
now used to help us identify a protnone pte that as saved write bit.
For such pte, we will clear the _PAGE_PRIVILEGED bit.  The pte still
remain non-accessible from both user and kernel.

[aneesh.kumar@linux.vnet.ibm.com: v3]
  Link: http://lkml.kernel.org/r/1487498625-10891-4-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1487050314-3892-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com


Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: default avatarMichael Neuling <mikey@neuling.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 595cd8f2

arch/powerpc/include/asm/book3s/64/pgtable.h

+45 −7
Original line number Diff line number Diff line 
#ifndef _ASM_POWERPC_BOOK3S_64_PGTABLE_H_

#define _ASM_POWERPC_BOOK3S_64_PGTABLE_H_



#ifndef __ASSEMBLY__

#include <linux/mmdebug.h>

#endif

/*

 * Common bits between hash and Radix page table

 */
@@ -434,15 +437,47 @@ static inline pte_t pte_clear_soft_dirty(pte_t pte) 
#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */



#ifdef CONFIG_NUMA_BALANCING

static inline int pte_protnone(pte_t pte)

{

	return (pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_PTE | _PAGE_RWX)) ==

		cpu_to_be64(_PAGE_PRESENT | _PAGE_PTE);

}



#define pte_mk_savedwrite pte_mk_savedwrite

static inline pte_t pte_mk_savedwrite(pte_t pte)

{

	/*

 * These work without NUMA balancing but the kernel does not care. See the

 * comment in include/asm-generic/pgtable.h . On powerpc, this will only

 * work for user pages and always return true for kernel pages.

	 * Used by Autonuma subsystem to preserve the write bit

	 * while marking the pte PROT_NONE. Only allow this

	 * on PROT_NONE pte

	 */

static inline int pte_protnone(pte_t pte)

	VM_BUG_ON((pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_RWX | _PAGE_PRIVILEGED)) !=

		  cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED));

	return __pte(pte_val(pte) & ~_PAGE_PRIVILEGED);

}



#define pte_clear_savedwrite pte_clear_savedwrite

static inline pte_t pte_clear_savedwrite(pte_t pte)

{

	/*

	 * Used by KSM subsystem to make a protnone pte readonly.

	 */

	VM_BUG_ON(!pte_protnone(pte));

	return __pte(pte_val(pte) | _PAGE_PRIVILEGED);

}



#define pte_savedwrite pte_savedwrite

static inline bool pte_savedwrite(pte_t pte)

{

	return (pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED)) ==

		cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED);

	/*

	 * Saved write ptes are prot none ptes that doesn't have

	 * privileged bit sit. We mark prot none as one which has

	 * present and pviliged bit set and RWX cleared. To mark

	 * protnone which used to have _PAGE_WRITE set we clear

	 * the privileged bit.

	 */

	VM_BUG_ON(!pte_protnone(pte));

	return !(pte_raw(pte) & cpu_to_be64(_PAGE_RWX | _PAGE_PRIVILEGED));

}

#endif /* CONFIG_NUMA_BALANCING */
@@ -873,6 +908,8 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd) 
#define pmd_mkclean(pmd)	pte_pmd(pte_mkclean(pmd_pte(pmd)))

#define pmd_mkyoung(pmd)	pte_pmd(pte_mkyoung(pmd_pte(pmd)))

#define pmd_mkwrite(pmd)	pte_pmd(pte_mkwrite(pmd_pte(pmd)))

#define pmd_mk_savedwrite(pmd)	pte_pmd(pte_mk_savedwrite(pmd_pte(pmd)))

#define pmd_clear_savedwrite(pmd)	pte_pmd(pte_clear_savedwrite(pmd_pte(pmd)))



#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY

#define pmd_soft_dirty(pmd)    pte_soft_dirty(pmd_pte(pmd))
@@ -889,6 +926,7 @@ static inline int pmd_protnone(pmd_t pmd) 


#define __HAVE_ARCH_PMD_WRITE

#define pmd_write(pmd)		pte_write(pmd_pte(pmd))

#define pmd_savedwrite(pmd)	pte_savedwrite(pmd_pte(pmd))



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);