diff options
| author | Scott Wood <scottwood@freescale.com> | 2008-02-06 06:43:26 +1100 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2008-02-06 16:30:01 +1100 |
| commit | 551ed332da2f52daf5d01fc76d2a894aba79d316 (patch) | |
| tree | a7b6ef800cf9d32344fe3e6989eb17607e00fd3c | |
| parent | f5903ede0015db5b53458092b6ae2af074fa49d4 (diff) | |
[POWERPC] update_mmu_cache: Don't cache-flush non-readable pages
Currently, update_mmu_cache will crash if given a no-access PTE.
There's no need to synchronize dcache/icache unless it's an exec
mapping -- however, due to the existence of older glibc versions that
execute out of a read-but-no-exec page, readability is tested instead.
This assumes no exec-only mappings; if such mappings become supported,
they will need to go through the kmap_atomic() version of
dcache/icache synchronization.
This fixes a bug reported by some users where the kernel would crash
while dumping core on a threaded program.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
| -rw-r--r-- | arch/powerpc/mm/mem.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index e8122447f01..c7d7bd43a25 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -483,7 +483,12 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, */ _tlbie(address, 0 /* 8xx doesn't care about PID */); #endif - if (!PageReserved(page) + /* The _PAGE_USER test should really be _PAGE_EXEC, but + * older glibc versions execute some code from no-exec + * pages, which for now we are supporting. If exec-only + * pages are ever implemented, this will have to change. + */ + if (!PageReserved(page) && (pte_val(pte) & _PAGE_USER) && !test_bit(PG_arch_1, &page->flags)) { if (vma->vm_mm == current->active_mm) { __flush_dcache_icache((void *) address); |