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authorChristophe Leroy <christophe.leroy@csgroup.eu>2020-06-15 12:57:58 +0000
committerMichael Ellerman <mpe@ellerman.id.au>2020-06-20 22:14:53 +1000
commit481e980a7c199c5a4634fd7ea308067dd4ba75fa (patch)
tree8cb8ccaf80bd171a3745a034ac6647fc2865eeba
parent55ca22633a9faa34c6a61d99433f9cc8e28dd7cc (diff)
downloadlinux-stericsson-481e980a7c199c5a4634fd7ea308067dd4ba75fa.tar.gz
mm: Allow arches to provide ptep_get()
Since commit 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses") it is not possible anymore to use READ_ONCE() to access complex page table entries like the one defined for powerpc 8xx with 16k size pages. Define a ptep_get() helper that architectures can override instead of performing a READ_ONCE() on the page table entry pointer. Fixes: 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Will Deacon <will@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/087fa12b6e920e32315136b998aa834f99242695.1592225558.git.christophe.leroy@csgroup.eu
-rw-r--r--include/asm-generic/hugetlb.h2
-rw-r--r--include/linux/pgtable.h7
-rw-r--r--mm/gup.c2
3 files changed, 9 insertions, 2 deletions
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 40f85decc2ee..8e1e6244a89d 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -122,7 +122,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
#ifndef __HAVE_ARCH_HUGE_PTEP_GET
static inline pte_t huge_ptep_get(pte_t *ptep)
{
- return READ_ONCE(*ptep);
+ return ptep_get(ptep);
}
#endif
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 32b6c52d41b9..56c1e8eb7bb0 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -249,6 +249,13 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
}
#endif
+#ifndef __HAVE_ARCH_PTEP_GET
+static inline pte_t ptep_get(pte_t *ptep)
+{
+ return READ_ONCE(*ptep);
+}
+#endif
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#ifndef __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
diff --git a/mm/gup.c b/mm/gup.c
index 761df4944ef5..6f47697f8fb0 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2196,7 +2196,7 @@ static inline pte_t gup_get_pte(pte_t *ptep)
*/
static inline pte_t gup_get_pte(pte_t *ptep)
{
- return READ_ONCE(*ptep);
+ return ptep_get(ptep);
}
#endif /* CONFIG_GUP_GET_PTE_LOW_HIGH */