[tip:x86/mm] mm/gup: Move permission checks into helpers

[tip-bot for Kirill A. Shutemov]

Commit-ID:  e7884f8ead4a301b04687a3238527b06feef8ea0
Gitweb: http://git.kernel.org/tip/e7884f8ead4a301b04687a3238527b06feef8ea0
Author: Kirill A. Shutemov 
AuthorDate: Thu, 16 Mar 2017 18:26:50 +0300
Committer:  Ingo Molnar 
CommitDate: Sat, 18 Mar 2017 09:48:01 +0100

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: Kirill A. Shutemov 
Cc: Andrew Morton 
Cc: Aneesh Kumar K . V 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Dann Frazier 
Cc: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Steve Capper 
Cc: Thomas Gleixner 
Cc: linux-a...@vger.kernel.org
Cc: linux...@kvack.org
Link: 
http://lkml.kernel.org/r/20170316152655.37789-3-kirill.shute...@linux.intel.com
Signed-off-by: Ingo Molnar 
---
 include/asm-generic/pgtable.h | 25 +
 mm/gup.c  | 15 ++-
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 1fad160..7dfa767 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -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)
diff --git a/mm/gup.c b/mm/gup.c
index 3f2338b..a62a778c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -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;

[tip:x86/mm] mm/gup: Move permission checks into helpers

[tip-bot for Kirill A. Shutemov]

Commit-ID:  e7884f8ead4a301b04687a3238527b06feef8ea0
Gitweb: http://git.kernel.org/tip/e7884f8ead4a301b04687a3238527b06feef8ea0
Author: Kirill A. Shutemov 
AuthorDate: Thu, 16 Mar 2017 18:26:50 +0300
Committer:  Ingo Molnar 
CommitDate: Sat, 18 Mar 2017 09:48:01 +0100

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: Kirill A. Shutemov 
Cc: Andrew Morton 
Cc: Aneesh Kumar K . V 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Dann Frazier 
Cc: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Steve Capper 
Cc: Thomas Gleixner 
Cc: linux-a...@vger.kernel.org
Cc: linux...@kvack.org
Link: 
http://lkml.kernel.org/r/20170316152655.37789-3-kirill.shute...@linux.intel.com
Signed-off-by: Ingo Molnar 
---
 include/asm-generic/pgtable.h | 25 +
 mm/gup.c  | 15 ++-
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 1fad160..7dfa767 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -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)
diff --git a/mm/gup.c b/mm/gup.c
index 3f2338b..a62a778c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -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;