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authorAnton Blanchard <anton@samba.org>2009-02-22 01:50:06 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-02-23 15:53:21 +1100
commit002b0ec73dd8b784004e5a013ad9f2fa6274af5a (patch)
tree8d614f85805a4884fcf485f292eb158c7aceb0af /arch/powerpc
parenta5adc91a4b44b5d1706b9d906cc14fe4f312afe9 (diff)
powerpc: Increase stack gap on 64bit binaries
On 64bit there is a possibility our stack and mmap randomisation will put the two close enough such that we can't expand our stack to match the ulimit specified. To avoid this, start the upper mmap address at 1GB + 128MB below the top of our address space, so in the worst case we end up with the same ~128MB hole as in 32bit. This works because we randomise the stack over a 1GB range. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/mm/mmap.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
index 75dc7faaf91..0d957a4c70f 100644
--- a/arch/powerpc/mm/mmap.c
+++ b/arch/powerpc/mm/mmap.c
@@ -30,9 +30,16 @@
/*
* Top of mmap area (just below the process stack).
*
- * Leave an at least ~128 MB hole.
+ * Leave at least a ~128 MB hole on 32bit applications.
+ *
+ * On 64bit applications we randomise the stack by 1GB so we need to
+ * space our mmap start address by a further 1GB, otherwise there is a
+ * chance the mmap area will end up closer to the stack than our ulimit
+ * requires.
*/
-#define MIN_GAP (128*1024*1024)
+#define MIN_GAP32 (128*1024*1024)
+#define MIN_GAP64 ((128 + 1024)*1024*1024UL)
+#define MIN_GAP ((is_32bit_task()) ? MIN_GAP32 : MIN_GAP64)
#define MAX_GAP (TASK_SIZE/6*5)
static inline int mmap_is_legacy(void)