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authorAnton Blanchard <anton@samba.org>2009-02-22 01:50:02 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-02-23 15:53:07 +1100
commit2dadb987e09995b2910c419cdfe2307e66537649 (patch)
tree963530a0ee6a54f6067e6d267f5861094426e1be
parent9f14c42d7582bf33bbe1e133d897a6942ceae08e (diff)
powerpc: More stack randomisation for 64bit binaries
At the moment we randomise the stack by 8MB on 32bit and 64bit tasks. Since we have a lot more address space to play with on 64bit, lets do what x86 does and increase that randomisation to 1GB: before: # for i in seq `1 10` ; do sleep 1 & cat /proc/${!}/maps | grep stack; done fffffebc000-fffffed1000 rw-p ffffffeb000 00:00 0 [stack] ffffff5a000-ffffff6f000 rw-p ffffffeb000 00:00 0 [stack] fffffdb2000-fffffdc7000 rw-p ffffffeb000 00:00 0 [stack] fffffd3e000-fffffd53000 rw-p ffffffeb000 00:00 0 [stack] fffffad9000-fffffaee000 rw-p ffffffeb000 00:00 0 [stack] after: # for i in seq `1 10` ; do sleep 1 & cat /proc/${!}/maps | grep stack; done ffff5c27000-ffff5c3c000 rw-p ffffffeb000 00:00 0 [stack] fffebe5e000-fffebe73000 rw-p ffffffeb000 00:00 0 [stack] fffcb298000-fffcb2ad000 rw-p ffffffeb000 00:00 0 [stack] fffc719d000-fffc71b2000 rw-p ffffffeb000 00:00 0 [stack] fffe01af000-fffe01c4000 rw-p ffffffeb000 00:00 0 [stack] Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/include/asm/elf.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index c125da793b0..3f94d8880e6 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -271,6 +271,11 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp);
#define VDSO_AUX_ENT(a,b) NEW_AUX_ENT(a,b);
+/* 1GB for 64bit, 8MB for 32bit */
+#define STACK_RND_MASK (is_32bit_task() ? \
+ (0x7ff >> (PAGE_SHIFT - 12)) : \
+ (0x3ffff >> (PAGE_SHIFT - 12)))
+
#endif /* __KERNEL__ */
/*