The per-pte get_and_clear/modify/set approach would result in
unfolding/refolding for contpte mappings on arm64. So we need
to override clear_young_dirty_ptes() for arm64 to avoid it.
Suggested-by: David Hildenbrand <[email protected]>
Suggested-by: Barry Song <[email protected]>
Suggested-by: Ryan Roberts <[email protected]>
Signed-off-by: Lance Yang <[email protected]>
---
arch/arm64/include/asm/pgtable.h | 55 ++++++++++++++++++++++++++++++++
arch/arm64/mm/contpte.c | 29 +++++++++++++++++
2 files changed, 84 insertions(+)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 9fd8613b2db2..1303d30287dc 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1223,6 +1223,46 @@ static inline void __wrprotect_ptes(struct mm_struct *mm, unsigned long address,
__ptep_set_wrprotect(mm, address, ptep);
}
+static inline void __clear_young_dirty_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t pte, cydp_t flags)
+{
+ pte_t old_pte;
+
+ do {
+ old_pte = pte;
+
+ if (flags & CYDP_CLEAR_YOUNG)
+ pte = pte_mkold(pte);
+ if (flags & CYDP_CLEAR_DIRTY)
+ pte = pte_mkclean(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 __clear_young_dirty_ptes(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, cydp_t flags)
+{
+ pte_t pte;
+
+ for (;;) {
+ pte = __ptep_get(ptep);
+
+ if (flags == (CYDP_CLEAR_YOUNG | CYDP_CLEAR_DIRTY))
+ __set_pte(ptep, pte_mkclean(pte_mkold(pte)));
+ else
+ __clear_young_dirty_pte(vma, addr, ptep, pte, flags);
+
+ if (--nr == 0)
+ break;
+ ptep++;
+ addr += PAGE_SIZE;
+ }
+}
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define __HAVE_ARCH_PMDP_SET_WRPROTECT
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
@@ -1379,6 +1419,9 @@ 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_clear_young_dirty_ptes(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, cydp_t flags);
static __always_inline void contpte_try_fold(struct mm_struct *mm,
unsigned long addr, pte_t *ptep, pte_t pte)
@@ -1603,6 +1646,17 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma,
return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirty);
}
+#define clear_young_dirty_ptes clear_young_dirty_ptes
+static inline void clear_young_dirty_ptes(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, cydp_t flags)
+{
+ if (likely(nr == 1 && !pte_cont(__ptep_get(ptep))))
+ __clear_young_dirty_ptes(vma, addr, ptep, nr, flags);
+ else
+ contpte_clear_young_dirty_ptes(vma, addr, ptep, nr, flags);
+}
+
#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 clear_young_dirty_ptes __clear_young_dirty_ptes
#endif /* CONFIG_ARM64_CONTPTE */
diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
index 1b64b4c3f8bf..9f9486de0004 100644
--- a/arch/arm64/mm/contpte.c
+++ b/arch/arm64/mm/contpte.c
@@ -361,6 +361,35 @@ void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
}
EXPORT_SYMBOL_GPL(contpte_wrprotect_ptes);
+void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ unsigned int nr, cydp_t flags)
+{
+ /*
+ * We can safely clear access/dirty without needing to unfold from
+ * the architectures perspective, even when contpte is set. If the
+ * range starts or ends midway through a contpte block, we can just
+ * expand to include the full contpte block. While this is not
+ * exactly what the core-mm asked for, it tracks access/dirty per
+ * folio, not per page. And since we only create a contpte block
+ * when it is covered by a single folio, we can get away with
+ * clearing access/dirty for the whole block.
+ */
+ unsigned long start = addr;
+ unsigned long end = start + nr;
+
+ if (pte_cont(__ptep_get(ptep + nr - 1)))
+ end = ALIGN(end, CONT_PTE_SIZE);
+
+ if (pte_cont(__ptep_get(ptep))) {
+ start = ALIGN_DOWN(start, CONT_PTE_SIZE);
+ ptep = contpte_align_down(ptep);
+ }
+
+ __clear_young_dirty_ptes(vma, start, ptep, end - start, flags);
+}
+EXPORT_SYMBOL_GPL(contpte_clear_young_dirty_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
On 16.04.24 05:34, Lance Yang wrote:
> The per-pte get_and_clear/modify/set approach would result in
> unfolding/refolding for contpte mappings on arm64. So we need
> to override clear_young_dirty_ptes() for arm64 to avoid it.
>
> Suggested-by: David Hildenbrand <[email protected]>
I could have sworn my suggestion would have better applied to patch #1 :)
--
Cheers,
David / dhildenb
On 16/04/2024 04:34, Lance Yang wrote:
> The per-pte get_and_clear/modify/set approach would result in
> unfolding/refolding for contpte mappings on arm64. So we need
> to override clear_young_dirty_ptes() for arm64 to avoid it.
>
> Suggested-by: David Hildenbrand <[email protected]>
> Suggested-by: Barry Song <[email protected]>
> Suggested-by: Ryan Roberts <[email protected]>
> Signed-off-by: Lance Yang <[email protected]>
Reviewed-by: Ryan Roberts <[email protected]>
> ---
> arch/arm64/include/asm/pgtable.h | 55 ++++++++++++++++++++++++++++++++
> arch/arm64/mm/contpte.c | 29 +++++++++++++++++
> 2 files changed, 84 insertions(+)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 9fd8613b2db2..1303d30287dc 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -1223,6 +1223,46 @@ static inline void __wrprotect_ptes(struct mm_struct *mm, unsigned long address,
> __ptep_set_wrprotect(mm, address, ptep);
> }
>
> +static inline void __clear_young_dirty_pte(struct vm_area_struct *vma,
> + unsigned long addr, pte_t *ptep,
> + pte_t pte, cydp_t flags)
> +{
> + pte_t old_pte;
> +
> + do {
> + old_pte = pte;
> +
> + if (flags & CYDP_CLEAR_YOUNG)
> + pte = pte_mkold(pte);
> + if (flags & CYDP_CLEAR_DIRTY)
> + pte = pte_mkclean(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 __clear_young_dirty_ptes(struct vm_area_struct *vma,
> + unsigned long addr, pte_t *ptep,
> + unsigned int nr, cydp_t flags)
> +{
> + pte_t pte;
> +
> + for (;;) {
> + pte = __ptep_get(ptep);
> +
> + if (flags == (CYDP_CLEAR_YOUNG | CYDP_CLEAR_DIRTY))
> + __set_pte(ptep, pte_mkclean(pte_mkold(pte)));
> + else
> + __clear_young_dirty_pte(vma, addr, ptep, pte, flags);
> +
> + if (--nr == 0)
> + break;
> + ptep++;
> + addr += PAGE_SIZE;
> + }
> +}
> +
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> #define __HAVE_ARCH_PMDP_SET_WRPROTECT
> static inline void pmdp_set_wrprotect(struct mm_struct *mm,
> @@ -1379,6 +1419,9 @@ 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_clear_young_dirty_ptes(struct vm_area_struct *vma,
> + unsigned long addr, pte_t *ptep,
> + unsigned int nr, cydp_t flags);
>
> static __always_inline void contpte_try_fold(struct mm_struct *mm,
> unsigned long addr, pte_t *ptep, pte_t pte)
> @@ -1603,6 +1646,17 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma,
> return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirty);
> }
>
> +#define clear_young_dirty_ptes clear_young_dirty_ptes
> +static inline void clear_young_dirty_ptes(struct vm_area_struct *vma,
> + unsigned long addr, pte_t *ptep,
> + unsigned int nr, cydp_t flags)
> +{
> + if (likely(nr == 1 && !pte_cont(__ptep_get(ptep))))
> + __clear_young_dirty_ptes(vma, addr, ptep, nr, flags);
> + else
> + contpte_clear_young_dirty_ptes(vma, addr, ptep, nr, flags);
> +}
> +
> #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 clear_young_dirty_ptes __clear_young_dirty_ptes
>
> #endif /* CONFIG_ARM64_CONTPTE */
>
> diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
> index 1b64b4c3f8bf..9f9486de0004 100644
> --- a/arch/arm64/mm/contpte.c
> +++ b/arch/arm64/mm/contpte.c
> @@ -361,6 +361,35 @@ void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
> }
> EXPORT_SYMBOL_GPL(contpte_wrprotect_ptes);
>
> +void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma,
> + unsigned long addr, pte_t *ptep,
> + unsigned int nr, cydp_t flags)
> +{
> + /*
> + * We can safely clear access/dirty without needing to unfold from
> + * the architectures perspective, even when contpte is set. If the
> + * range starts or ends midway through a contpte block, we can just
> + * expand to include the full contpte block. While this is not
> + * exactly what the core-mm asked for, it tracks access/dirty per
> + * folio, not per page. And since we only create a contpte block
> + * when it is covered by a single folio, we can get away with
> + * clearing access/dirty for the whole block.
> + */
> + unsigned long start = addr;
> + unsigned long end = start + nr;
> +
> + if (pte_cont(__ptep_get(ptep + nr - 1)))
> + end = ALIGN(end, CONT_PTE_SIZE);
> +
> + if (pte_cont(__ptep_get(ptep))) {
> + start = ALIGN_DOWN(start, CONT_PTE_SIZE);
> + ptep = contpte_align_down(ptep);
> + }
> +
> + __clear_young_dirty_ptes(vma, start, ptep, end - start, flags);
> +}
> +EXPORT_SYMBOL_GPL(contpte_clear_young_dirty_ptes);
> +
> int contpte_ptep_set_access_flags(struct vm_area_struct *vma,
> unsigned long addr, pte_t *ptep,
> pte_t entry, int dirty)
On Wed, Apr 17, 2024 at 12:29 AM Ryan Roberts <[email protected]> wrote:
>
> On 16/04/2024 04:34, Lance Yang wrote:
> > The per-pte get_and_clear/modify/set approach would result in
> > unfolding/refolding for contpte mappings on arm64. So we need
> > to override clear_young_dirty_ptes() for arm64 to avoid it.
> >
> > Suggested-by: David Hildenbrand <[email protected]>
> > Suggested-by: Barry Song <[email protected]>
> > Suggested-by: Ryan Roberts <[email protected]>
> > Signed-off-by: Lance Yang <[email protected]>
>
> Reviewed-by: Ryan Roberts <[email protected]>
Hey Ryan,
Thanks for taking time to review!
Best,
Lance
>
> > ---
> > arch/arm64/include/asm/pgtable.h | 55 ++++++++++++++++++++++++++++++++
> > arch/arm64/mm/contpte.c | 29 +++++++++++++++++
> > 2 files changed, 84 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> > index 9fd8613b2db2..1303d30287dc 100644
> > --- a/arch/arm64/include/asm/pgtable.h
> > +++ b/arch/arm64/include/asm/pgtable.h
> > @@ -1223,6 +1223,46 @@ static inline void __wrprotect_ptes(struct mm_struct *mm, unsigned long address,
> > __ptep_set_wrprotect(mm, address, ptep);
> > }
> >
> > +static inline void __clear_young_dirty_pte(struct vm_area_struct *vma,
> > + unsigned long addr, pte_t *ptep,
> > + pte_t pte, cydp_t flags)
> > +{
> > + pte_t old_pte;
> > +
> > + do {
> > + old_pte = pte;
> > +
> > + if (flags & CYDP_CLEAR_YOUNG)
> > + pte = pte_mkold(pte);
> > + if (flags & CYDP_CLEAR_DIRTY)
> > + pte = pte_mkclean(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 __clear_young_dirty_ptes(struct vm_area_struct *vma,
> > + unsigned long addr, pte_t *ptep,
> > + unsigned int nr, cydp_t flags)
> > +{
> > + pte_t pte;
> > +
> > + for (;;) {
> > + pte = __ptep_get(ptep);
> > +
> > + if (flags == (CYDP_CLEAR_YOUNG | CYDP_CLEAR_DIRTY))
> > + __set_pte(ptep, pte_mkclean(pte_mkold(pte)));
> > + else
> > + __clear_young_dirty_pte(vma, addr, ptep, pte, flags);
> > +
> > + if (--nr == 0)
> > + break;
> > + ptep++;
> > + addr += PAGE_SIZE;
> > + }
> > +}
> > +
> > #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> > #define __HAVE_ARCH_PMDP_SET_WRPROTECT
> > static inline void pmdp_set_wrprotect(struct mm_struct *mm,
> > @@ -1379,6 +1419,9 @@ 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_clear_young_dirty_ptes(struct vm_area_struct *vma,
> > + unsigned long addr, pte_t *ptep,
> > + unsigned int nr, cydp_t flags);
> >
> > static __always_inline void contpte_try_fold(struct mm_struct *mm,
> > unsigned long addr, pte_t *ptep, pte_t pte)
> > @@ -1603,6 +1646,17 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma,
> > return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirty);
> > }
> >
> > +#define clear_young_dirty_ptes clear_young_dirty_ptes
> > +static inline void clear_young_dirty_ptes(struct vm_area_struct *vma,
> > + unsigned long addr, pte_t *ptep,
> > + unsigned int nr, cydp_t flags)
> > +{
> > + if (likely(nr == 1 && !pte_cont(__ptep_get(ptep))))
> > + __clear_young_dirty_ptes(vma, addr, ptep, nr, flags);
> > + else
> > + contpte_clear_young_dirty_ptes(vma, addr, ptep, nr, flags);
> > +}
> > +
> > #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 clear_young_dirty_ptes __clear_young_dirty_ptes
> >
> > #endif /* CONFIG_ARM64_CONTPTE */
> >
> > diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
> > index 1b64b4c3f8bf..9f9486de0004 100644
> > --- a/arch/arm64/mm/contpte.c
> > +++ b/arch/arm64/mm/contpte.c
> > @@ -361,6 +361,35 @@ void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
> > }
> > EXPORT_SYMBOL_GPL(contpte_wrprotect_ptes);
> >
> > +void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma,
> > + unsigned long addr, pte_t *ptep,
> > + unsigned int nr, cydp_t flags)
> > +{
> > + /*
> > + * We can safely clear access/dirty without needing to unfold from
> > + * the architectures perspective, even when contpte is set. If the
> > + * range starts or ends midway through a contpte block, we can just
> > + * expand to include the full contpte block. While this is not
> > + * exactly what the core-mm asked for, it tracks access/dirty per
> > + * folio, not per page. And since we only create a contpte block
> > + * when it is covered by a single folio, we can get away with
> > + * clearing access/dirty for the whole block.
> > + */
> > + unsigned long start = addr;
> > + unsigned long end = start + nr;
> > +
> > + if (pte_cont(__ptep_get(ptep + nr - 1)))
> > + end = ALIGN(end, CONT_PTE_SIZE);
> > +
> > + if (pte_cont(__ptep_get(ptep))) {
> > + start = ALIGN_DOWN(start, CONT_PTE_SIZE);
> > + ptep = contpte_align_down(ptep);
> > + }
> > +
> > + __clear_young_dirty_ptes(vma, start, ptep, end - start, flags);
> > +}
> > +EXPORT_SYMBOL_GPL(contpte_clear_young_dirty_ptes);
> > +
> > int contpte_ptep_set_access_flags(struct vm_area_struct *vma,
> > unsigned long addr, pte_t *ptep,
> > pte_t entry, int dirty)
>