diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2008-02-04 16:48:07 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-02-04 16:48:07 +0100 |
| commit | 9a14aefc1d28c6037122965ee8c10d92a970ade0 (patch) | |
| tree | 8f1342c4f18d075009abc9e4f05a6d4e4ba97640 | |
| parent | 34508f66b69ff1708192654f631eb8f1d4c52005 (diff) | |
x86: cpa, fix lookup_address
lookup_address() returns a wrong level and a wrong pointer to a non
existing pte, when pmd or pud entries are marked !present. This
happens for example due to boot time mapping of GART into the low
memory space.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/mm/pageattr.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 3810f7a83b1..7d21cd658ed 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -188,6 +188,14 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address) return prot; } +/* + * Lookup the page table entry for a virtual address. Return a pointer + * to the entry and the level of the mapping. + * + * Note: We return pud and pmd either when the entry is marked large + * or when the present bit is not set. Otherwise we would return a + * pointer to a nonexisting mapping. + */ pte_t *lookup_address(unsigned long address, int *level) { pgd_t *pgd = pgd_offset_k(address); @@ -206,7 +214,7 @@ pte_t *lookup_address(unsigned long address, int *level) return NULL; *level = PG_LEVEL_2M; - if (pmd_large(*pmd)) + if (pmd_large(*pmd) || !pmd_present(*pmd)) return (pte_t *)pmd; *level = PG_LEVEL_4K; |