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Commit 53f82452 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

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



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

Suggested-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarJeremy 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: default avatarIngo Molnar <mingo@elte.hu>
parent 1ea0d14e

arch/x86/include/asm/processor.h

+1 −1
Original line number Diff line number Diff line
@@ -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 */

arch/x86/kernel/cpu/common.c

+1 −1
Original line number Diff line number Diff line
@@ -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 */

include/asm-generic/percpu.h

+3 −0
Original line number Diff line number Diff line
@@ -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

include/linux/percpu-defs.h

+8 −0
Original line number Diff line number Diff line
@@ -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.

 */