mm: Allow arches to provide ptep_get() (481e980a) · Commits · 戴 / test

Since commit ("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: ("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

include/asm-generic/hugetlb.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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

include/linux/pgtable.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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,

mm/gup.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 */

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