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authorJeremy Fitzhardinge <jeremy@goop.org>2009-09-03 23:27:15 +0400
committerIngo Molnar <mingo@elte.hu>2009-09-03 23:30:51 +0400
commit1ea0d14e480c245683927eecc03a70faf06e80c8 (patch)
treecc43a6966799aa55c0f076c1217c557fb107563c /arch/x86/include/asm/stackprotector.h
parent23386d63bbb3199cf247313ec088878d72debcfd (diff)
downloadlinux-1ea0d14e480c245683927eecc03a70faf06e80c8.tar.xz
x86/i386: Make sure stack-protector segment base is cache aligned
The Intel Optimization Reference Guide says: In Intel Atom microarchitecture, the address generation unit assumes that the segment base will be 0 by default. Non-zero segment base will cause load and store operations to experience a delay. - If the segment base isn't aligned to a cache line boundary, the max throughput of memory operations is reduced to one [e]very 9 cycles. [...] Assembly/Compiler Coding Rule 15. (H impact, ML generality) For Intel Atom processors, use segments with base set to 0 whenever possible; avoid non-zero segment base address that is not aligned to cache line boundary at all cost. We can't avoid having a non-zero base for the stack-protector segment, but we can make it cache-aligned. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: <stable@kernel.org> LKML-Reference: <4AA01893.6000507@goop.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/stackprotector.h')
-rw-r--r--arch/x86/include/asm/stackprotector.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index 44efdff3975d..157517763565 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -78,14 +78,14 @@ static __always_inline void boot_init_stack_canary(void)
#ifdef CONFIG_X86_64
percpu_write(irq_stack_union.stack_canary, canary);
#else
- percpu_write(stack_canary, canary);
+ percpu_write(stack_canary.canary, canary);
#endif
}
static inline void setup_stack_canary_segment(int cpu)
{
#ifdef CONFIG_X86_32
- unsigned long canary = (unsigned long)&per_cpu(stack_canary, cpu) - 20;
+ unsigned long canary = (unsigned long)&per_cpu(stack_canary, cpu);
struct desc_struct *gdt_table = get_cpu_gdt_table(cpu);
struct desc_struct desc;