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 Cc: Andi Kleen Signed-off-by: Christoph Lameter --- include/asm-generic/percpu.h | 64 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 53 insertions(+), 11 deletions(-) Index: linux-2.6/include/asm-generic/percpu.h =================================================================== --- linux-2.6.orig/include/asm-generic/percpu.h 2007-11-24 19:33:55.416103196 -0800 +++ linux-2.6/include/asm-generic/percpu.h 2007-11-24 19:36:35.016350539 -0800 @@ -3,27 +3,69 @@ #include #include +/* + * 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_PTR +#define SHIFT_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_PTR(&per_cpu_var(var), per_cpu_offset(cpu))) +#define __get_cpu_var(var) (*SHIFT_PTR(&per_cpu_var(var), my_cpu_offset)) +#define __raw_get_cpu_var(var) (*SHIFT_PTR(&per_cpu_var(var), __my_cpu_offset)) + +#ifdef CONFIG_ARCH_SETS_UP_PER_CPU_AREA +extern void setup_per_cpu_areas(void); +#endif #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 +#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu_var(name) #endif /* _ASM_GENERIC_PERCPU_H_ */ -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/