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.

Christophe Leroy committed 6 years ago

Commit 481e9801 parent 55ca2263 files · +9 −2Browse files

Unified · Split

3 files

include/asm-generic/hugetlb.h +1 −1
include/linux/pgtable.h +7 −0
mm/gup.c +1 −1

include/asm-generic/hugetlb.h+1−1

@@ -122,7 +122,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma, · 121 unmodified lines
122	122	#ifndef __HAVE_ARCH_HUGE_PTEP_GET
123	123	static inline pte_t huge_ptep_get(pte_t *ptep)
124	124	{
125		− return READ_ONCE(*ptep);
	125	+ return ptep_get(ptep);
126	126	}
127	127	#endif
128	128

include/linux/pgtable.h+7−0

@@ -249,6 +249,13 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, · 248 unmodified lines
249	249	}
250	250	#endif
251	251
	252	+#ifndef __HAVE_ARCH_PTEP_GET
	253	+static inline pte_t ptep_get(pte_t *ptep)
	254	+{
	255	+ return READ_ONCE(*ptep);
	256	+}
	257	+#endif
	258	+
252	259	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
253	260	#ifndef __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
254	261	static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,

mm/gup.c+1−1

@@ -2196,7 +2196,7 @@ static inline pte_t gup_get_pte(pte_t *ptep) · 2195 unmodified lines
2196	2196	*/
2197	2197	static inline pte_t gup_get_pte(pte_t *ptep)
2198	2198	{
2199		− return READ_ONCE(*ptep);
	2199	+ return ptep_get(ptep);
2200	2200	}
2201	2201	#endif /* CONFIG_GUP_GET_PTE_LOW_HIGH */
2202	2202