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percpu: make the asm-generic/percpu.h more "generic"

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- 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: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
travis@sgi.com 2008-01-30 13:32:52 +01:00 committed by Ingo Molnar
parent 5280e004fc
commit acdac87202
2 changed files with 64 additions and 12 deletions
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2
arch/ia64/kernel/module.c
View file

@ -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 */

74
include/asm-generic/percpu.h
View file

@ -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
/* 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())
/*
* 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
/*
* 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_ */