diff options
Diffstat (limited to 'include/linux/percpu-defs.h')
| -rw-r--r-- | include/linux/percpu-defs.h | 119 |
1 files changed, 99 insertions, 20 deletions
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h index 8f921d74f49f..27ef6b190ea6 100644 --- a/include/linux/percpu-defs.h +++ b/include/linux/percpu-defs.h @@ -2,29 +2,83 @@ #define _LINUX_PERCPU_DEFS_H /* - * Determine the real variable name from the name visible in the - * kernel sources. - */ -#define per_cpu_var(var) per_cpu__##var - -/* * Base implementations of per-CPU variable declarations and definitions, where * the section in which the variable is to be placed is provided by the - * 'section' argument. This may be used to affect the parameters governing the + * 'sec' argument. This may be used to affect the parameters governing the * variable's storage. * * NOTE! The sections for the DECLARE and for the DEFINE must match, lest * linkage errors occur due the compiler generating the wrong code to access * that section. */ -#define DECLARE_PER_CPU_SECTION(type, name, section) \ - extern \ - __attribute__((__section__(PER_CPU_BASE_SECTION section))) \ - PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name +#define __PCPU_ATTRS(sec) \ + __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \ + PER_CPU_ATTRIBUTES -#define DEFINE_PER_CPU_SECTION(type, name, section) \ - __attribute__((__section__(PER_CPU_BASE_SECTION section))) \ - PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name +#define __PCPU_DUMMY_ATTRS \ + __attribute__((section(".discard"), unused)) + +/* + * Macro which verifies @ptr is a percpu pointer without evaluating + * @ptr. This is to be used in percpu accessors to verify that the + * input parameter is a percpu pointer. + */ +#define __verify_pcpu_ptr(ptr) do { \ + const void __percpu *__vpp_verify = (typeof(ptr))NULL; \ + (void)__vpp_verify; \ +} while (0) + +/* + * s390 and alpha modules require percpu variables to be defined as + * weak to force the compiler to generate GOT based external + * references for them. This is necessary because percpu sections + * will be located outside of the usually addressable area. + * + * This definition puts the following two extra restrictions when + * defining percpu variables. + * + * 1. The symbol must be globally unique, even the static ones. + * 2. Static percpu variables cannot be defined inside a function. + * + * Archs which need weak percpu definitions should define + * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. + * + * To ensure that the generic code observes the above two + * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak + * definition is used for all cases. + */ +#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU) +/* + * __pcpu_scope_* dummy variable is used to enforce scope. It + * receives the static modifier when it's used in front of + * DEFINE_PER_CPU() and will trigger build failure if + * DECLARE_PER_CPU() is used for the same variable. + * + * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness + * such that hidden weak symbol collision, which will cause unrelated + * variables to share the same address, can be detected during build. + */ +#define DECLARE_PER_CPU_SECTION(type, name, sec) \ + extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ + extern __PCPU_ATTRS(sec) __typeof__(type) name + +#define DEFINE_PER_CPU_SECTION(type, name, sec) \ + __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ + extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ + __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ + __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ + __typeof__(type) name +#else +/* + * Normal declaration and definition macros. + */ +#define DECLARE_PER_CPU_SECTION(type, name, sec) \ + extern __PCPU_ATTRS(sec) __typeof__(type) name + +#define DEFINE_PER_CPU_SECTION(type, name, sec) \ + __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \ + __typeof__(type) name +#endif /* * Variant on the per-CPU variable declaration/definition theme used for @@ -65,20 +119,45 @@ 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. */ -#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ - DECLARE_PER_CPU_SECTION(type, name, ".page_aligned") +#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ + DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \ + __aligned(PAGE_SIZE) #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ - DEFINE_PER_CPU_SECTION(type, name, ".page_aligned") + DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \ + __aligned(PAGE_SIZE) /* - * Intermodule exports for per-CPU variables. + * Declaration/definition used for per-CPU variables that must be read mostly. */ -#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var) -#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var) +#define DECLARE_PER_CPU_READ_MOSTLY(type, name) \ + DECLARE_PER_CPU_SECTION(type, name, "..readmostly") +#define DEFINE_PER_CPU_READ_MOSTLY(type, name) \ + DEFINE_PER_CPU_SECTION(type, name, "..readmostly") + +/* + * Intermodule exports for per-CPU variables. sparse forgets about + * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to + * noop if __CHECKER__. + */ +#ifndef __CHECKER__ +#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var) +#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var) +#else +#define EXPORT_PER_CPU_SYMBOL(var) +#define EXPORT_PER_CPU_SYMBOL_GPL(var) +#endif #endif /* _LINUX_PERCPU_DEFS_H */ |