x86: debug pmd_bad()

Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 12 insertions, 1 deletions

diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
index 2f9e9afcb9f4..76e4f4d26272 100644
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -381,3 +381,10 @@ void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
 }
 
 #endif
+
+int pmd_bad(pmd_t pmd)
+{
+        WARN_ON_ONCE(pmd_bad_v1(pmd) != pmd_bad_v2(pmd));
+
+        return pmd_bad_v1(pmd);
+}
diff --git a/include/asm-x86/pgtable_32.h b/include/asm-x86/pgtable_32.h
index 997c36c6b4d7..1e2c0d839528 100644
--- a/include/asm-x86/pgtable_32.h
+++ b/include/asm-x86/pgtable_32.h
@@ -90,7 +90,11 @@ extern unsigned long pg0[];
 /* To avoid harmful races, pmd_none(x) should check only the lower when PAE */
 #define pmd_none(x)     (!(unsigned long)pmd_val(x))
 #define pmd_present(x)  (pmd_val(x) & _PAGE_PRESENT)
-#define pmd_bad(x)      ((pmd_val(x) \
+
+extern int pmd_bad(pmd_t pmd);
+
+#define pmd_bad_v1(x)   ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
+#define pmd_bad_v2(x)   ((pmd_val(x) \
                           & ~(PAGE_MASK | _PAGE_USER | _PAGE_PSE | _PAGE_NX)) \
                          != _KERNPG_TABLE)