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x86/i386: Put aligned stack-canary in percpu shared_aligned section

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Pack aligned things together into a special section to minimize
padding holes.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Tejun Heo <tj@kernel.org>
LKML-Reference: <4AA035C0.9070202@goop.org>
[ queued up in tip:x86/asm because it depends on this commit:
  x86/i386: Make sure stack-protector segment base is cache aligned ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge 2009-09-03 14:31:44 -07:00 committed by Ingo Molnar
parent 1ea0d14e48
commit 53f824520b
4 changed files with 13 additions and 2 deletions
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2
arch/x86/include/asm/processor.h
View file

@ -413,7 +413,7 @@ struct stack_canary {
char __pad[20]; /* canary at %gs:20 */
unsigned long canary;
};
DECLARE_PER_CPU(struct stack_canary, stack_canary) ____cacheline_aligned;
DECLARE_PER_CPU_ALIGNED(struct stack_canary, stack_canary);
#endif
#endif /* X86_64 */

2
arch/x86/kernel/cpu/common.c
View file

@ -1043,7 +1043,7 @@ DEFINE_PER_CPU(struct orig_ist, orig_ist);
#else /* CONFIG_X86_64 */
#ifdef CONFIG_CC_STACKPROTECTOR
DEFINE_PER_CPU(struct stack_canary, stack_canary) ____cacheline_aligned;
DEFINE_PER_CPU_ALIGNED(struct stack_canary, stack_canary);
#endif
/* Make sure %fs and %gs are initialized properly in idle threads */

3
include/asm-generic/percpu.h
View file

@ -81,14 +81,17 @@ extern void setup_per_cpu_areas(void);
#ifdef MODULE
#define PER_CPU_SHARED_ALIGNED_SECTION ""
#define PER_CPU_ALIGNED_SECTION ""
#else
#define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
#define PER_CPU_ALIGNED_SECTION ".shared_aligned"
#endif
#define PER_CPU_FIRST_SECTION ".first"
#else
#define PER_CPU_SHARED_ALIGNED_SECTION ""
#define PER_CPU_ALIGNED_SECTION ".shared_aligned"
#define PER_CPU_FIRST_SECTION ""
#endif

8
include/linux/percpu-defs.h
View file

@ -66,6 +66,14 @@
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
____cacheline_aligned_in_smp
#define DECLARE_PER_CPU_ALIGNED(type, name) \
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
____cacheline_aligned
#define DEFINE_PER_CPU_ALIGNED(type, name) \
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
____cacheline_aligned
/*
* Declaration/definition used for per-CPU variables that must be page aligned.
*/