Le 19/08/2020 à 15:01, Aneesh Kumar K.V a écrit :
set_pte_at() should not be used to set a pte entry at locations that
already holds a valid pte entry. Architectures like ppc64 don't do TLB
invalidate in set_pte_at() and hence expect it to be used to set locations
that are not a valid PTE.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 35 +++++++++++++++--------------------
1 file changed, 15 insertions(+), 20 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 76f4c713e5a3..9c7e2c9cfc76 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -74,15 +74,18 @@ static void __init pte_advanced_tests(struct mm_struct *mm,
{
pte_t pte = pfn_pte(pfn, prot);
+ /*
+ * Architectures optimize set_pte_at by avoiding TLB flush.
+ * This requires set_pte_at to be not used to update an
+ * existing pte entry. Clear pte before we do set_pte_at
+ */
+
pr_debug("Validating PTE advanced\n");
pte = pfn_pte(pfn, prot);
set_pte_at(mm, vaddr, ptep, pte);
ptep_set_wrprotect(mm, vaddr, ptep);
pte = ptep_get(ptep);
WARN_ON(pte_write(pte));
-
- pte = pfn_pte(pfn, prot);
- set_pte_at(mm, vaddr, ptep, pte);
ptep_get_and_clear(mm, vaddr, ptep);
pte = ptep_get(ptep);
WARN_ON(!pte_none(pte));
@@ -96,13 +99,11 @@ static void __init pte_advanced_tests(struct mm_struct *mm,
ptep_set_access_flags(vma, vaddr, ptep, pte, 1);
pte = ptep_get(ptep);
WARN_ON(!(pte_write(pte) && pte_dirty(pte)));
-
- pte = pfn_pte(pfn, prot);
- set_pte_at(mm, vaddr, ptep, pte);
ptep_get_and_clear_full(mm, vaddr, ptep, 1);
pte = ptep_get(ptep);
WARN_ON(!pte_none(pte));
+ pte = pfn_pte(pfn, prot);
pte = pte_mkyoung(pte);
set_pte_at(mm, vaddr, ptep, pte);
ptep_test_and_clear_young(vma, vaddr, ptep);
@@ -164,9 +165,6 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
pmdp_set_wrprotect(mm, vaddr, pmdp);
pmd = READ_ONCE(*pmdp);
WARN_ON(pmd_write(pmd));
-
- pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
- set_pmd_at(mm, vaddr, pmdp, pmd);
pmdp_huge_get_and_clear(mm, vaddr, pmdp);
pmd = READ_ONCE(*pmdp);
WARN_ON(!pmd_none(pmd));
@@ -180,13 +178,11 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
pmdp_set_access_flags(vma, vaddr, pmdp, pmd, 1);
pmd = READ_ONCE(*pmdp);
WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd)));
-
- pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
- set_pmd_at(mm, vaddr, pmdp, pmd);
pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1);
pmd = READ_ONCE(*pmdp);
WARN_ON(!pmd_none(pmd));
+ pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
pmd = pmd_mkyoung(pmd);
set_pmd_at(mm, vaddr, pmdp, pmd);
pmdp_test_and_clear_young(vma, vaddr, pmdp);
@@ -283,18 +279,10 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
WARN_ON(pud_write(pud));
#ifndef __PAGETABLE_PMD_FOLDED
Same as below, once set_put_at() is gone, I don't think this #ifndef
__PAGETABLE_PMD_FOLDED is still need, should be possible to replace by
'if (mm_pmd_folded())'
-
- pud = pud_mkhuge(pfn_pud(pfn, prot));
- set_pud_at(mm, vaddr, pudp, pud);
pudp_huge_get_and_clear(mm, vaddr, pudp);
pud = READ_ONCE(*pudp);
WARN_ON(!pud_none(pud));
- pud = pud_mkhuge(pfn_pud(pfn, prot));
- set_pud_at(mm, vaddr, pudp, pud);
- pudp_huge_get_and_clear_full(mm, vaddr, pudp, 1);
- pud = READ_ONCE(*pudp);
- WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */
pud = pud_mkhuge(pfn_pud(pfn, prot));
@@ -307,6 +295,13 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
pud = READ_ONCE(*pudp);
WARN_ON(!(pud_write(pud) && pud_dirty(pud)));
+#ifndef __PAGETABLE_PMD_FOLDED
+ pudp_huge_get_and_clear_full(vma, vaddr, pudp, 1);
+ pud = READ_ONCE(*pudp);
+ WARN_ON(!pud_none(pud));
+#endif /* __PAGETABLE_PMD_FOLDED */
pudp_huge_get_and_clear_full() and pud_none() are always defined, I
think this #ifndef can be replaced by an 'if (mm_pmd_folded())'
+
+ pud = pud_mkhuge(pfn_pud(pfn, prot));
pud = pud_mkyoung(pud);
set_pud_at(mm, vaddr, pudp, pud);
pudp_test_and_clear_young(vma, vaddr, pudp);
Christophe
