When working on mprotect() on 1G dax entries, I hit an zap bad pud
error when zapping a huge pud that is with PROT_NONE permission.
Here the problem is x86's pud_leaf() requires both PRESENT and PSE bits
set to report a pud entry as a leaf, but that doesn't look right, as
it's not following the pXd_leaf() definition that we stick with so far,
where PROT_NONE entries should be reported as leaves.
To fix it, change x86's pud_leaf() implementation to only check against
PSE bit to report a leaf, irrelevant of whether PRESENT bit is set.
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
arch/x86/include/asm/pgtable.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index e39311a89bf4..a2a3bd4c1bda 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1078,8 +1078,7 @@ static inline pmd_t *pud_pgtable(pud_t pud)
#define pud_leaf pud_leaf
static inline bool pud_leaf(pud_t pud)
{
- return (pud_val(pud) & (_PAGE_PSE | _PAGE_PRESENT)) ==
- (_PAGE_PSE | _PAGE_PRESENT);
+ return pud_val(pud) & _PAGE_PSE;
}
static inline int pud_bad(pud_t pud)
--
2.45.0
