The per-pte get_and_clear/modify/set approach would result in
unfolding/refolding for contpte mappings on arm64. So we need
to override mkold_clean_ptes() for arm64 to avoid it.
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Suggested-by: Barry Song <21cnbao@xxxxxxxxx>
Suggested-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: Lance Yang <ioworker0@xxxxxxxxx>
---
arch/arm64/include/asm/pgtable.h | 55 ++++++++++++++++++++++++++++++++
arch/arm64/mm/contpte.c | 15 +++++++++
2 files changed, 70 insertions(+)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 9fd8613b2db2..395754638a9a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1223,6 +1223,34 @@ static inline void __wrprotect_ptes(struct mm_struct *mm, unsigned long address,
__ptep_set_wrprotect(mm, address, ptep);
}
+static inline void ___ptep_mkold_clean(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, pte_t pte)
+{
+ pte_t old_pte;
+
+ do {
+ old_pte = pte;
+ pte = pte_mkclean(pte_mkold(pte));
+ pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
+ pte_val(old_pte), pte_val(pte));
+ } while (pte_val(pte) != pte_val(old_pte));
+}
+
+static inline void __ptep_mkold_clean(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep)
+{
+ ___ptep_mkold_clean(mm, addr, ptep, __ptep_get(ptep));
+}
+
+static inline void __mkold_clean_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr)
+{
+ unsigned int i;
+
+ for (i = 0; i < nr; i++, addr += PAGE_SIZE, ptep++)
+ __ptep_mkold_clean(mm, addr, ptep);
+}
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define __HAVE_ARCH_PMDP_SET_WRPROTECT
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
@@ -1379,6 +1407,8 @@ extern void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
extern int contpte_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t entry, int dirty);
+extern void contpte_mkold_clean_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr);
static __always_inline void contpte_try_fold(struct mm_struct *mm,
unsigned long addr, pte_t *ptep, pte_t pte)
@@ -1603,6 +1633,30 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma,
return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirty);
}
+#define mkold_clean_ptes mkold_clean_ptes
+static inline void mkold_clean_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr)
+{
+ if (likely(nr == 1)) {
+ /*
+ * Optimization: mkold_clean_ptes() can only be called for present
+ * ptes so we only need to check contig bit as condition for unfold,
+ * and we can remove the contig bit from the pte we read to avoid
+ * re-reading. This speeds up madvise(MADV_FREE) which is sensitive
+ * for order-0 folios. Equivalent to contpte_try_unfold().
+ */
+ pte_t orig_pte = __ptep_get(ptep);
+
+ if (unlikely(pte_cont(orig_pte))) {
+ __contpte_try_unfold(mm, addr, ptep, orig_pte);
+ orig_pte = pte_mknoncont(orig_pte);
+ }
+ ___ptep_mkold_clean(mm, addr, ptep, orig_pte);
+ } else {
+ contpte_mkold_clean_ptes(mm, addr, ptep, nr);
+ }
+}
+
#else /* CONFIG_ARM64_CONTPTE */
#define ptep_get __ptep_get
@@ -1622,6 +1676,7 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma,
#define wrprotect_ptes __wrprotect_ptes
#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
#define ptep_set_access_flags __ptep_set_access_flags
+#define mkold_clean_ptes __mkold_clean_ptes
#endif /* CONFIG_ARM64_CONTPTE */
diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
index 1b64b4c3f8bf..dbff9c5e9eff 100644
--- a/arch/arm64/mm/contpte.c
+++ b/arch/arm64/mm/contpte.c
@@ -361,6 +361,21 @@ void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
}
EXPORT_SYMBOL_GPL(contpte_wrprotect_ptes);
+void contpte_mkold_clean_ptes(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep, unsigned int nr)
+{
+ /*
+ * If clearing the young and dirty bits for an entire contig range, we can
+ * avoid unfolding. Just set old/clean and wait for the later mmu_gather
+ * flush to invalidate the tlb. If it's a partial range though, we need to
+ * unfold.
+ */
+
+ contpte_try_unfold_partial(mm, addr, ptep, nr);
+ __mkold_clean_ptes(mm, addr, ptep, nr);
+}
+EXPORT_SYMBOL_GPL(contpte_mkold_clean_ptes);
+
int contpte_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t entry, int dirty)
--
2.33.1
