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Message-Id: <20210830235927.6443-14-rick.p.edgecombe@intel.com>
Date: Mon, 30 Aug 2021 16:59:21 -0700
From: Rick Edgecombe <rick.p.edgecombe@...el.com>
To: dave.hansen@...el.com,
luto@...nel.org,
peterz@...radead.org,
x86@...nel.org,
akpm@...ux-foundation.org,
keescook@...omium.org,
shakeelb@...gle.com,
vbabka@...e.cz,
rppt@...nel.org
Cc: Rick Edgecombe <rick.p.edgecombe@...el.com>,
linux-mm@...ck.org,
linux-hardening@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
ira.weiny@...el.com,
dan.j.williams@...el.com,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH v2 13/19] mm/debug_vm_page_table: Use setters instead of WRITE_ONCE
Currently debug_vm_page_table uses some raw WRITE_ONCE invocations to
write to page tables, which PKS tables is designed to prevent. So use the
set_p**() helpers instead of WRITE_ONCE for x86, so debug_vm_page_table
will work with PKS tables enabled.
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
---
mm/debug_vm_pgtable.c | 36 +++++++++++++++++++++++++++++++++---
1 file changed, 33 insertions(+), 3 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 1c922691aa61..a0b8859ecf04 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -411,11 +411,17 @@ static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
return;
pr_debug("Validating PMD huge\n");
+
+#ifdef CONFIG_X86
+ /* Use setter so that protections can be toggled if needed */
+ set_pmd(pmdp, __pmd(0));
+#else
+ WRITE_ONCE(*pmdp, __pmd(0));
+#endif
/*
* X86 defined pmd_set_huge() verifies that the given
* PMD is not a populated non-leaf entry.
*/
- WRITE_ONCE(*pmdp, __pmd(0));
WARN_ON(!pmd_set_huge(pmdp, __pfn_to_phys(pfn), prot));
WARN_ON(!pmd_clear_huge(pmdp));
pmd = READ_ONCE(*pmdp);
@@ -430,11 +436,16 @@ static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
return;
pr_debug("Validating PUD huge\n");
+#ifdef CONFIG_X86
+ /* Use setter so that protections can be toggled if needed */
+ set_pud(pudp, __pud(0));
+#else
+ WRITE_ONCE(*pudp, __pud(0));
+#endif
/*
* X86 defined pud_set_huge() verifies that the given
* PUD is not a populated non-leaf entry.
*/
- WRITE_ONCE(*pudp, __pud(0));
WARN_ON(!pud_set_huge(pudp, __pfn_to_phys(pfn), prot));
WARN_ON(!pud_clear_huge(pudp));
pud = READ_ONCE(*pudp);
@@ -473,7 +484,12 @@ static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp)
pr_debug("Validating PUD clear\n");
pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
+#ifdef CONFIG_X86
+ /* Use setter so that protections can be toggled if needed */
+ set_pud(pudp, pud);
+#else
WRITE_ONCE(*pudp, pud);
+#endif
pud_clear(pudp);
pud = READ_ONCE(*pudp);
WARN_ON(!pud_none(pud));
@@ -514,7 +530,12 @@ static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp)
pr_debug("Validating P4D clear\n");
p4d = __p4d(p4d_val(p4d) | RANDOM_ORVALUE);
+#ifdef CONFIG_X86
+ /* Use setter so that protections can be toggled if needed */
+ set_p4d(p4dp, p4d);
+#else
WRITE_ONCE(*p4dp, p4d);
+#endif
p4d_clear(p4dp);
p4d = READ_ONCE(*p4dp);
WARN_ON(!p4d_none(p4d));
@@ -549,7 +570,12 @@ static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp)
pr_debug("Validating PGD clear\n");
pgd = __pgd(pgd_val(pgd) | RANDOM_ORVALUE);
+#ifdef CONFIG_X86
+ /* Use setter so that protections can be toggled if needed */
+ set_pgd(pgdp, pgd);
+#else
WRITE_ONCE(*pgdp, pgd);
+#endif
pgd_clear(pgdp);
pgd = READ_ONCE(*pgdp);
WARN_ON(!pgd_none(pgd));
@@ -610,8 +636,12 @@ static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp)
pr_debug("Validating PMD clear\n");
pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE);
- WRITE_ONCE(*pmdp, pmd);
+#ifdef CONFIG_X86
+ /* Use setter so that protections can be toggled if needed */
pmd_clear(pmdp);
+#else
+ WRITE_ONCE(*pmdp, pmd);
+#endif
pmd = READ_ONCE(*pmdp);
WARN_ON(!pmd_none(pmd));
}
--
2.17.1
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