From 481e980a7c199c5a4634fd7ea308067dd4ba75fa Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Mon, 15 Jun 2020 12:57:58 +0000 Subject: 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 Acked-by: Will Deacon Acked-by: Peter Zijlstra (Intel) Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/087fa12b6e920e32315136b998aa834f99242695.1592225558.git.christophe.leroy@csgroup.eu --- include/asm-generic/hugetlb.h | 2 +- include/linux/pgtable.h | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) (limited to 'include') 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, -- cgit v1.2.3-59-g8ed1b