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Commit acdac872 authored by travis@sgi.com's avatar travis@sgi.com Committed by Ingo Molnar
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percpu: make the asm-generic/percpu.h more "generic" 



- add support for PER_CPU_ATTRIBUTES

- fix generic smp percpu_modcopy to use per_cpu_offset() macro.

Add the ability to use generic/percpu even if the arch needs to override
several aspects of its operations. This will enable the use of generic
percpu.h for all arches.

An arch may define:

__per_cpu_offset	Do not use the generic pointer array. Arch must
			define per_cpu_offset(cpu) (used by x86_64, s390).

__my_cpu_offset		Can be defined to provide an optimized way to determine
			the offset for variables of the currently executing
			processor. Used by ia64, x86_64, x86_32, sparc64, s/390.

SHIFT_PTR(ptr, offset)	If an arch defines it then special handling
			of pointer arithmentic may be implemented. Used
			by s/390.

(Some of these special percpu arch implementations may be later consolidated
so that there are less cases to deal with.)

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarMike Travis <travis@sgi.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5280e004

arch/ia64/kernel/module.c

+1 −1
Original line number Diff line number Diff line
@@ -947,7 +947,7 @@ percpu_modcopy (void *pcpudst, const void *src, unsigned long size) 
{

	unsigned int i;

	for_each_possible_cpu(i) {

		memcpy(pcpudst + __per_cpu_offset[i], src, size);

		memcpy(pcpudst + per_cpu_offset(i), src, size);

	}

}

#endif /* CONFIG_SMP */

include/asm-generic/percpu.h

+63 −11
Original line number Diff line number Diff line
@@ -3,35 +3,87 @@ 
#include <linux/compiler.h>

#include <linux/threads.h>



/*

 * Determine the real variable name from the name visible in the

 * kernel sources.

 */

#define per_cpu_var(var) per_cpu__##var



#ifdef CONFIG_SMP



/*

 * per_cpu_offset() is the offset that has to be added to a

 * percpu variable to get to the instance for a certain processor.

 *

 * Most arches use the __per_cpu_offset array for those offsets but

 * some arches have their own ways of determining the offset (x86_64, s390).

 */

#ifndef __per_cpu_offset

extern unsigned long __per_cpu_offset[NR_CPUS];



#define per_cpu_offset(x) (__per_cpu_offset[x])

#endif



/*

 * Determine the offset for the currently active processor.

 * An arch may define __my_cpu_offset to provide a more effective

 * means of obtaining the offset to the per cpu variables of the

 * current processor.

 */

#ifndef __my_cpu_offset

#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())

#define my_cpu_offset per_cpu_offset(smp_processor_id())

#else

#define my_cpu_offset __my_cpu_offset

#endif



/*

 * Add a offset to a pointer but keep the pointer as is.

 *

 * Only S390 provides its own means of moving the pointer.

 */

#ifndef SHIFT_PERCPU_PTR

#define SHIFT_PERCPU_PTR(__p, __offset)	RELOC_HIDE((__p), (__offset))

#endif



/* var is in discarded region: offset to particular copy we want */

#define per_cpu(var, cpu) (*({				\

	extern int simple_identifier_##var(void);	\

	RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]); }))

#define __get_cpu_var(var) per_cpu(var, smp_processor_id())

#define __raw_get_cpu_var(var) per_cpu(var, raw_smp_processor_id())

/*

 * A percpu variable may point to a discarded reghions. The following are

 * established ways to produce a usable pointer from the percpu variable

 * offset.

 */

#define per_cpu(var, cpu) \

	(*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu)))

#define __get_cpu_var(var) \

	(*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset))

#define __raw_get_cpu_var(var) \

	(*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset))





#ifdef CONFIG_ARCH_SETS_UP_PER_CPU_AREA

extern void setup_per_cpu_areas(void);

#endif



/* A macro to avoid #include hell... */

#define percpu_modcopy(pcpudst, src, size)			\

do {								\

	unsigned int __i;					\

	for_each_possible_cpu(__i)				\

		memcpy((pcpudst)+__per_cpu_offset[__i],		\

		memcpy((pcpudst)+per_cpu_offset(__i),		\

		       (src), (size));				\

} while (0)

#else /* ! SMP */



#define per_cpu(var, cpu)			(*((void)(cpu), &per_cpu__##var))

#define __get_cpu_var(var)			per_cpu__##var

#define __raw_get_cpu_var(var)			per_cpu__##var

#define per_cpu(var, cpu)			(*((void)(cpu), &per_cpu_var(var)))

#define __get_cpu_var(var)			per_cpu_var(var)

#define __raw_get_cpu_var(var)			per_cpu_var(var)



#endif	/* SMP */



#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name

#ifndef PER_CPU_ATTRIBUTES

#define PER_CPU_ATTRIBUTES

#endif



#define DECLARE_PER_CPU(type, name) extern PER_CPU_ATTRIBUTES \

					__typeof__(type) per_cpu_var(name)



#endif /* _ASM_GENERIC_PERCPU_H_ */