275 lines
8.8 KiB
C
275 lines
8.8 KiB
C
/*
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* linux/percpu-defs.h - basic definitions for percpu areas
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*
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* DO NOT INCLUDE DIRECTLY OUTSIDE PERCPU IMPLEMENTATION PROPER.
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*
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* This file is separate from linux/percpu.h to avoid cyclic inclusion
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* dependency from arch header files. Only to be included from
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* asm/percpu.h.
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*
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* This file includes macros necessary to declare percpu sections and
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* variables, and definitions of percpu accessors and operations. It
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* should provide enough percpu features to arch header files even when
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* they can only include asm/percpu.h to avoid cyclic inclusion dependency.
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*/
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#ifndef _LINUX_PERCPU_DEFS_H
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#define _LINUX_PERCPU_DEFS_H
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#ifdef CONFIG_SMP
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#ifdef MODULE
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#define PER_CPU_SHARED_ALIGNED_SECTION ""
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#define PER_CPU_ALIGNED_SECTION ""
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#else
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#define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
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#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
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#endif
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#define PER_CPU_FIRST_SECTION "..first"
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#else
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#define PER_CPU_SHARED_ALIGNED_SECTION ""
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#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
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#define PER_CPU_FIRST_SECTION ""
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#endif
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/*
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* Base implementations of per-CPU variable declarations and definitions, where
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* the section in which the variable is to be placed is provided by the
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* 'sec' argument. This may be used to affect the parameters governing the
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* variable's storage.
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*
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* NOTE! The sections for the DECLARE and for the DEFINE must match, lest
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* linkage errors occur due the compiler generating the wrong code to access
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* that section.
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*/
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#define __PCPU_ATTRS(sec) \
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__percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \
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PER_CPU_ATTRIBUTES
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#define __PCPU_DUMMY_ATTRS \
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__attribute__((section(".discard"), unused))
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/*
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* Macro which verifies @ptr is a percpu pointer without evaluating
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* @ptr. This is to be used in percpu accessors to verify that the
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* input parameter is a percpu pointer.
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*
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* + 0 is required in order to convert the pointer type from a
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* potential array type to a pointer to a single item of the array.
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*/
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#define __verify_pcpu_ptr(ptr) do { \
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const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
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(void)__vpp_verify; \
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} while (0)
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/*
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* s390 and alpha modules require percpu variables to be defined as
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* weak to force the compiler to generate GOT based external
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* references for them. This is necessary because percpu sections
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* will be located outside of the usually addressable area.
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*
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* This definition puts the following two extra restrictions when
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* defining percpu variables.
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*
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* 1. The symbol must be globally unique, even the static ones.
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* 2. Static percpu variables cannot be defined inside a function.
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*
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* Archs which need weak percpu definitions should define
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* ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
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*
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* To ensure that the generic code observes the above two
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* restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
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* definition is used for all cases.
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*/
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#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
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/*
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* __pcpu_scope_* dummy variable is used to enforce scope. It
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* receives the static modifier when it's used in front of
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* DEFINE_PER_CPU() and will trigger build failure if
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* DECLARE_PER_CPU() is used for the same variable.
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*
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* __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
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* such that hidden weak symbol collision, which will cause unrelated
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* variables to share the same address, can be detected during build.
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*/
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#define DECLARE_PER_CPU_SECTION(type, name, sec) \
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extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
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extern __PCPU_ATTRS(sec) __typeof__(type) name
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#define DEFINE_PER_CPU_SECTION(type, name, sec) \
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__PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
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extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
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__PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
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extern __PCPU_ATTRS(sec) __typeof__(type) name; \
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__PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \
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__typeof__(type) name
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#else
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/*
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* Normal declaration and definition macros.
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*/
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#define DECLARE_PER_CPU_SECTION(type, name, sec) \
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extern __PCPU_ATTRS(sec) __typeof__(type) name
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#define DEFINE_PER_CPU_SECTION(type, name, sec) \
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__PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \
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__typeof__(type) name
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#endif
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/*
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* Variant on the per-CPU variable declaration/definition theme used for
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* ordinary per-CPU variables.
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*/
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#define DECLARE_PER_CPU(type, name) \
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DECLARE_PER_CPU_SECTION(type, name, "")
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#define DEFINE_PER_CPU(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, "")
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/*
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* Declaration/definition used for per-CPU variables that must come first in
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* the set of variables.
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*/
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#define DECLARE_PER_CPU_FIRST(type, name) \
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DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
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#define DEFINE_PER_CPU_FIRST(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
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/*
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* Declaration/definition used for per-CPU variables that must be cacheline
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* aligned under SMP conditions so that, whilst a particular instance of the
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* data corresponds to a particular CPU, inefficiencies due to direct access by
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* other CPUs are reduced by preventing the data from unnecessarily spanning
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* cachelines.
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*
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* An example of this would be statistical data, where each CPU's set of data
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* is updated by that CPU alone, but the data from across all CPUs is collated
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* by a CPU processing a read from a proc file.
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*/
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#define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
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DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
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____cacheline_aligned_in_smp
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#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
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____cacheline_aligned_in_smp
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#define DECLARE_PER_CPU_ALIGNED(type, name) \
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DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
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____cacheline_aligned
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#define DEFINE_PER_CPU_ALIGNED(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
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____cacheline_aligned
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/*
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* Declaration/definition used for per-CPU variables that must be page aligned.
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*/
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#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
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DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \
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__aligned(PAGE_SIZE)
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#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \
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__aligned(PAGE_SIZE)
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/*
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* Declaration/definition used for per-CPU variables that must be read mostly.
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*/
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#define DECLARE_PER_CPU_READ_MOSTLY(type, name) \
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DECLARE_PER_CPU_SECTION(type, name, "..readmostly")
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#define DEFINE_PER_CPU_READ_MOSTLY(type, name) \
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DEFINE_PER_CPU_SECTION(type, name, "..readmostly")
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/*
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* Intermodule exports for per-CPU variables. sparse forgets about
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* address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
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* noop if __CHECKER__.
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*/
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#ifndef __CHECKER__
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#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var)
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#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var)
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#else
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#define EXPORT_PER_CPU_SYMBOL(var)
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#define EXPORT_PER_CPU_SYMBOL_GPL(var)
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#endif
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/*
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* Accessors and operations.
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*/
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#ifndef __ASSEMBLY__
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#ifdef CONFIG_SMP
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/*
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* Add an offset to a pointer but keep the pointer as-is. Use RELOC_HIDE()
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* to prevent the compiler from making incorrect assumptions about the
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* pointer value. The weird cast keeps both GCC and sparse happy.
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*/
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#define SHIFT_PERCPU_PTR(__p, __offset) ({ \
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__verify_pcpu_ptr((__p)); \
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RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset)); \
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})
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#define per_cpu_ptr(ptr, cpu) SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
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#define raw_cpu_ptr(ptr) arch_raw_cpu_ptr(ptr)
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#ifdef CONFIG_DEBUG_PREEMPT
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#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
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#else
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#define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
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#endif
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#else /* CONFIG_SMP */
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#define VERIFY_PERCPU_PTR(__p) ({ \
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__verify_pcpu_ptr((__p)); \
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(typeof(*(__p)) __kernel __force *)(__p); \
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})
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#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); VERIFY_PERCPU_PTR((ptr)); })
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#define raw_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)
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#define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
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#endif /* CONFIG_SMP */
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#define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu))
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#define __raw_get_cpu_var(var) (*raw_cpu_ptr(&(var)))
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#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
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/* keep until we have removed all uses of __this_cpu_ptr */
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#define __this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
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/*
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* Must be an lvalue. Since @var must be a simple identifier,
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* we force a syntax error here if it isn't.
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*/
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#define get_cpu_var(var) (*({ \
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preempt_disable(); \
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this_cpu_ptr(&var); }))
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/*
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* The weird & is necessary because sparse considers (void)(var) to be
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* a direct dereference of percpu variable (var).
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*/
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#define put_cpu_var(var) do { \
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(void)&(var); \
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preempt_enable(); \
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} while (0)
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#define get_cpu_ptr(var) ({ \
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preempt_disable(); \
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this_cpu_ptr(var); })
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#define put_cpu_ptr(var) do { \
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(void)(var); \
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preempt_enable(); \
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} while (0)
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#endif /* __ASSEMBLY__ */
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#endif /* _LINUX_PERCPU_DEFS_H */
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