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Commit e7884f8e authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Ingo Molnar
Browse files

mm/gup: Move permission checks into helpers 



This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

On x86, we would need to do additional permission checks to determine if
access is allowed.

Let's abstract it out into separate helpers.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-3-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9a804fec

include/asm-generic/pgtable.h

+25 −0
Original line number Diff line number Diff line
@@ -341,6 +341,31 @@ static inline int pte_unused(pte_t pte) 
}

#endif



#ifndef pte_access_permitted

#define pte_access_permitted(pte, write) \

	(pte_present(pte) && (!(write) || pte_write(pte)))

#endif



#ifndef pmd_access_permitted

#define pmd_access_permitted(pmd, write) \

	(pmd_present(pmd) && (!(write) || pmd_write(pmd)))

#endif



#ifndef pud_access_permitted

#define pud_access_permitted(pud, write) \

	(pud_present(pud) && (!(write) || pud_write(pud)))

#endif



#ifndef p4d_access_permitted

#define p4d_access_permitted(p4d, write) \

	(p4d_present(p4d) && (!(write) || p4d_write(p4d)))

#endif



#ifndef pgd_access_permitted

#define pgd_access_permitted(pgd, write) \

	(pgd_present(pgd) && (!(write) || pgd_write(pgd)))

#endif



#ifndef __HAVE_ARCH_PMD_SAME

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)

mm/gup.c

+10 −5
Original line number Diff line number Diff line
@@ -1212,8 +1212,13 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, 
		 * Similar to the PMD case below, NUMA hinting must take slow

		 * path using the pte_protnone check.

		 */

		if (!pte_present(pte) || pte_special(pte) ||

			pte_protnone(pte) || (write && !pte_write(pte)))

		if (pte_protnone(pte))

			goto pte_unmap;



		if (!pte_access_permitted(pte, write))

			goto pte_unmap;



		if (pte_special(pte))

			goto pte_unmap;



		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
@@ -1264,7 +1269,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, 
	struct page *head, *page;

	int refs;



	if (write && !pmd_write(orig))

	if (!pmd_access_permitted(orig, write))

		return 0;



	refs = 0;
@@ -1299,7 +1304,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, 
	struct page *head, *page;

	int refs;



	if (write && !pud_write(orig))

	if (!pud_access_permitted(orig, write))

		return 0;



	refs = 0;
@@ -1335,7 +1340,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr, 
	int refs;

	struct page *head, *page;



	if (write && !pgd_write(orig))

	if (!pgd_access_permitted(orig, write))

		return 0;



	refs = 0;