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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2017-03-16 18:26:51 +0300
committerIngo Molnar <mingo@kernel.org>2017-03-18 09:48:02 +0100
commit0005d20b2ff1e501e186b3b3bc587085ac305fdc (patch)
treeb0f05c1dc037f034e533ead0a56eeeb9dd5f0b23 /mm
parente7884f8ead4a301b04687a3238527b06feef8ea0 (diff)
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mm/gup: Move page table entry dereference into helper function
This is a preparation patch for the transition of x86 to the generic GUP_fast() implementation. On x86 PAE, page table entry is larger than sizeof(long) and we would need to provide a helper that can read the entry atomically. Signed-off-by: Kirill 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/20170316152655.37789-4-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/gup.c20
1 files changed, 12 insertions, 8 deletions
diff --git a/mm/gup.c b/mm/gup.c
index a62a778ce4ec..e83db38deb17 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1189,6 +1189,17 @@ struct page *get_dump_page(unsigned long addr)
*/
#ifdef CONFIG_HAVE_GENERIC_RCU_GUP
+#ifndef gup_get_pte
+/*
+ * We assume that the PTE can be read atomically. If this is not the case for
+ * your architecture, please provide the helper.
+ */
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+ return READ_ONCE(*ptep);
+}
+#endif
+
#ifdef __HAVE_ARCH_PTE_SPECIAL
static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
@@ -1198,14 +1209,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
ptem = ptep = pte_offset_map(&pmd, addr);
do {
- /*
- * In the line below we are assuming that the pte can be read
- * atomically. If this is not the case for your architecture,
- * please wrap this in a helper function!
- *
- * for an example see gup_get_pte in arch/x86/mm/gup.c
- */
- pte_t pte = READ_ONCE(*ptep);
+ pte_t pte = gup_get_pte(ptep);
struct page *head, *page;
/*