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-rw-r--r--arch/x86/include/asm/pgtable-invert.h11
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/include/asm/pgtable-invert.h b/arch/x86/include/asm/pgtable-invert.h
index 44b1203ece12..a0c1525f1b6f 100644
--- a/arch/x86/include/asm/pgtable-invert.h
+++ b/arch/x86/include/asm/pgtable-invert.h
@@ -4,9 +4,18 @@
#ifndef __ASSEMBLY__
+/*
+ * A clear pte value is special, and doesn't get inverted.
+ *
+ * Note that even users that only pass a pgprot_t (rather
+ * than a full pte) won't trigger the special zero case,
+ * because even PAGE_NONE has _PAGE_PROTNONE | _PAGE_ACCESSED
+ * set. So the all zero case really is limited to just the
+ * cleared page table entry case.
+ */
static inline bool __pte_needs_invert(u64 val)
{
- return !(val & _PAGE_PRESENT);
+ return val && !(val & _PAGE_PRESENT);
}
/* Get a mask to xor with the page table entry to get the correct pfn. */