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#ifndef _LINUX_PERCPU_DEFS_H
#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
* '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 __PCPU_ATTRS(sec) \
__attribute__((section(PER_CPU_BASE_SECTION sec))) \
PER_CPU_ATTRIBUTES
#define __PCPU_DUMMY_ATTRS \
__attribute__((section(".discard"), unused))
/*
* 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) per_cpu__##name
#define DEFINE_PER_CPU_SECTION(type, name, sec) \
__PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
__PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
__PCPU_ATTRS(sec) __weak __typeof__(type) per_cpu__##name
#else
/*
* Normal declaration and definition macros.
*/
#define DECLARE_PER_CPU_SECTION(type, name, sec) \
extern __PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name
#define DEFINE_PER_CPU_SECTION(type, name, sec) \
__PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name
#endif
/*
* Variant on the per-CPU variable declaration/definition theme used for
* ordinary per-CPU variables.
*/
#define DECLARE_PER_CPU(type, name) \
DECLARE_PER_CPU_SECTION(type, name, "")
#define DEFINE_PER_CPU(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "")
/*
* Declaration/definition used for per-CPU variables that must come first in
* the set of variables.
*/
#define DECLARE_PER_CPU_FIRST(type, name) \
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
#define DEFINE_PER_CPU_FIRST(type, name) \
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
/*
* Declaration/definition used for per-CPU variables that must be cacheline
* aligned under SMP conditions so that, whilst a particular instance of the
* data corresponds to a particular CPU, inefficiencies due to direct access by
* other CPUs are reduced by preventing the data from unnecessarily spanning
* cachelines.
*
* An example of this would be statistical data, where each CPU's set of data
* is updated by that CPU alone, but the data from across all CPUs is collated
* by a CPU processing a read from a proc file.
*/
#define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
____cacheline_aligned_in_smp
#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
____cacheline_aligned_in_smp
/*
* 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 DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
DEFINE_PER_CPU_SECTION(type, name, ".page_aligned")
/*
* Intermodule exports for per-CPU variables.
*/
#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
#endif /* _LINUX_PERCPU_DEFS_H */
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