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percpu-defs.h
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/* * linux/percpu-defs.h - basic definitions for percpu areas * * DO NOT INCLUDE DIRECTLY OUTSIDE PERCPU IMPLEMENTATION PROPER. * * This file is separate from linux/percpu.h to avoid cyclic inclusion * dependency from arch header files. Only to be included from * asm/percpu.h. * * This file includes macros necessary to declare percpu sections and * variables, and definitions of percpu accessors and operations. It * should provide enough percpu features to arch header files even when * they can only include asm/percpu.h to avoid cyclic inclusion dependency. */ #ifndef _LINUX_PERCPU_DEFS_H #define _LINUX_PERCPU_DEFS_H #ifdef CONFIG_SMP #ifdef MODULE #define PER_CPU_SHARED_ALIGNED_SECTION "" #define PER_CPU_ALIGNED_SECTION "" #else #define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned" #define PER_CPU_ALIGNED_SECTION "..shared_aligned" #endif #define PER_CPU_FIRST_SECTION "..first" #else #define PER_CPU_SHARED_ALIGNED_SECTION "" #define PER_CPU_ALIGNED_SECTION "..shared_aligned" #define PER_CPU_FIRST_SECTION "" #endif #ifdef CONFIG_PAGE_TABLE_ISOLATION #define USER_MAPPED_SECTION "..user_mapped" #else #define USER_MAPPED_SECTION "" #endif /* * 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) \ __percpu __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) 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; \ extern __PCPU_ATTRS(sec) __typeof__(type) 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 * 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, "") #define DECLARE_PER_CPU_USER_MAPPED(type, name) \ DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION) #define DEFINE_PER_CPU_USER_MAPPED(type, name) \ DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION) /* * 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 #define DECLARE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(type, name) \ DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION PER_CPU_SHARED_ALIGNED_SECTION) \ ____cacheline_aligned_in_smp #define DEFINE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(type, name) \ DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION 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") \ __aligned(PAGE_SIZE) #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \ __aligned(PAGE_SIZE) /* * Declaration/definition used for per-CPU variables that must be page aligned and need to be mapped in user mode. */ #define DECLARE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(type, name) \ DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION"..page_aligned") \ __aligned(PAGE_SIZE) #define DEFINE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(type, name) \ DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION"..page_aligned") \ __aligned(PAGE_SIZE) /* * Declaration/definition used for per-CPU variables that must be read mostly. */ #define DECLARE_PER_CPU_READ_MOSTLY(type, name) \ DECLARE_PER_CPU_SECTION(type, name, "..read_mostly") #define DEFINE_PER_CPU_READ_MOSTLY(type, name) \ DEFINE_PER_CPU_SECTION(type, name, "..read_mostly") /* * 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 /* * Accessors and operations. */ #ifndef __ASSEMBLY__ /* * __verify_pcpu_ptr() verifies @ptr is a percpu pointer without evaluating * @ptr and is invoked once before a percpu area is accessed by all * accessors and operations. This is performed in the generic part of * percpu and arch overrides don't need to worry about it; however, if an * arch wants to implement an arch-specific percpu accessor or operation, * it may use __verify_pcpu_ptr() to verify the parameters. * * + 0 is required in order to convert the pointer type from a * potential array type to a pointer to a single item of the array. */ #define __verify_pcpu_ptr(ptr) \ do { \ const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \ (void)__vpp_verify; \ } while (0) #ifdef CONFIG_SMP /* * Add an offset to a pointer but keep the pointer as-is. Use RELOC_HIDE() * to prevent the compiler from making incorrect assumptions about the * pointer value. The weird cast keeps both GCC and sparse happy. */ #define SHIFT_PERCPU_PTR(__p, __offset) \ RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset)) #define per_cpu_ptr(ptr, cpu) \ ({ \ __verify_pcpu_ptr(ptr); \ SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))); \ }) #define raw_cpu_ptr(ptr) \ ({ \ __verify_pcpu_ptr(ptr); \ arch_raw_cpu_ptr(ptr); \ }) #ifdef CONFIG_DEBUG_PREEMPT #define this_cpu_ptr(ptr) \ ({ \ __verify_pcpu_ptr(ptr); \ SHIFT_PERCPU_PTR(ptr, my_cpu_offset); \ }) #else #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr) #endif #else /* CONFIG_SMP */ #define VERIFY_PERCPU_PTR(__p) \ ({ \ __verify_pcpu_ptr(__p); \ (typeof(*(__p)) __kernel __force *)(__p); \ }) #define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); VERIFY_PERCPU_PTR(ptr); }) #define raw_cpu_ptr(ptr) per_cpu_ptr(ptr, 0) #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr) #endif /* CONFIG_SMP */ #define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu)) /* * Must be an lvalue. Since @var must be a simple identifier, * we force a syntax error here if it isn't. */ #define get_cpu_var(var) \ (*({ \ preempt_disable(); \ this_cpu_ptr(&var); \ })) /* * The weird & is necessary because sparse considers (void)(var) to be * a direct dereference of percpu variable (var). */ #define put_cpu_var(var) \ do { \ (void)&(var); \ preempt_enable(); \ } while (0) #define get_cpu_ptr(var) \ ({ \ preempt_disable(); \ this_cpu_ptr(var); \ }) #define put_cpu_ptr(var) \ do { \ (void)(var); \ preempt_enable(); \ } while (0) /* * Branching function to split up a function into a set of functions that * are called for different scalar sizes of the objects handled. */ extern void __bad_size_call_parameter(void); #ifdef CONFIG_DEBUG_PREEMPT extern void __this_cpu_preempt_check(const char *op); #else static inline void __this_cpu_preempt_check(const char *op) { } #endif #define __pcpu_size_call_return(stem, variable) \ ({ \ typeof(variable) pscr_ret__; \ __verify_pcpu_ptr(&(variable)); \ switch(sizeof(variable)) { \ case 1: pscr_ret__ = stem##1(variable); break; \ case 2: pscr_ret__ = stem##2(variable); break; \ case 4: pscr_ret__ = stem##4(variable); break; \ case 8: pscr_ret__ = stem##8(variable); break; \ default: \ __bad_size_call_parameter(); break; \ } \ pscr_ret__; \ }) #define __pcpu_size_call_return2(stem, variable, ...) \ ({ \ typeof(variable) pscr2_ret__; \ __verify_pcpu_ptr(&(variable)); \ switch(sizeof(variable)) { \ case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break; \ case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break; \ case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break; \ case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break; \ default: \ __bad_size_call_parameter(); break; \ } \ pscr2_ret__; \ }) /* * Special handling for cmpxchg_double. cmpxchg_double is passed two * percpu variables. The first has to be aligned to a double word * boundary and the second has to follow directly thereafter. * We enforce this on all architectures even if they don't support * a double cmpxchg instruction, since it's a cheap requirement, and it * avoids breaking the requirement for architectures with the instruction. */ #define __pcpu_double_call_return_bool(stem, pcp1, pcp2, ...) \ ({ \ bool pdcrb_ret__; \ __verify_pcpu_ptr(&(pcp1)); \ BUILD_BUG_ON(sizeof(pcp1) != sizeof(pcp2)); \ VM_BUG_ON((unsigned long)(&(pcp1)) % (2 * sizeof(pcp1))); \ VM_BUG_ON((unsigned long)(&(pcp2)) != \ (unsigned long)(&(pcp1)) + sizeof(pcp1)); \ switch(sizeof(pcp1)) { \ case 1: pdcrb_ret__ = stem##1(pcp1, pcp2, __VA_ARGS__); break; \ case 2: pdcrb_ret__ = stem##2(pcp1, pcp2, __VA_ARGS__); break; \ case 4: pdcrb_ret__ = stem##4(pcp1, pcp2, __VA_ARGS__); break; \ case 8: pdcrb_ret__ = stem##8(pcp1, pcp2, __VA_ARGS__); break; \ default: \ __bad_size_call_parameter(); break; \ } \ pdcrb_ret__; \ }) #define __pcpu_size_call(stem, variable, ...) \ do { \ __verify_pcpu_ptr(&(variable)); \ switch(sizeof(variable)) { \ case 1: stem##1(variable, __VA_ARGS__);break; \ case 2: stem##2(variable, __VA_ARGS__);break; \ case 4: stem##4(variable, __VA_ARGS__);break; \ case 8: stem##8(variable, __VA_ARGS__);break; \ default: \ __bad_size_call_parameter();break; \ } \ } while (0) /* * this_cpu operations (C) 2008-2013 Christoph Lameter <cl@linux.com> * * Optimized manipulation for memory allocated through the per cpu * allocator or for addresses of per cpu variables. * * These operation guarantee exclusivity of access for other operations * on the *same* processor. The assumption is that per cpu data is only * accessed by a single processor instance (the current one). * * The arch code can provide optimized implementation by defining macros * for certain scalar sizes. F.e. provide this_cpu_add_2() to provide per * cpu atomic operations for 2 byte sized RMW actions. If arch code does * not provide operations for a scalar size then the fallback in the * generic code will be used. * * cmpxchg_double replaces two adjacent scalars at once. The first two * parameters are per cpu variables which have to be of the same size. A * truth value is returned to indicate success or failure (since a double * register result is difficult to handle). There is very limited hardware * support for these operations, so only certain sizes may work. */ /* * Operations for contexts where we do not want to do any checks for * preemptions. Unless strictly necessary, always use [__]this_cpu_*() * instead. * * If there is no other protection through preempt disable and/or disabling * interupts then one of these RMW operations can show unexpected behavior * because the execution thread was rescheduled on another processor or an * interrupt occurred and the same percpu variable was modified from the * interrupt context. */ #define raw_cpu_read(pcp) __pcpu_size_call_return(raw_cpu_read_, pcp) #define raw_cpu_write(pcp, val) __pcpu_size_call(raw_cpu_write_, pcp, val) #define raw_cpu_add(pcp, val) __pcpu_size_call(raw_cpu_add_, pcp, val) #define raw_cpu_and(pcp, val) __pcpu_size_call(raw_cpu_and_, pcp, val) #define raw_cpu_or(pcp, val) __pcpu_size_call(raw_cpu_or_, pcp, val) #define raw_cpu_add_return(pcp, val) __pcpu_size_call_return2(raw_cpu_add_return_, pcp, val) #define raw_cpu_xchg(pcp, nval) __pcpu_size_call_return2(raw_cpu_xchg_, pcp, nval) #define raw_cpu_cmpxchg(pcp, oval, nval) \ __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval) #define raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \ __pcpu_double_call_return_bool(raw_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2) #define raw_cpu_sub(pcp, val) raw_cpu_add(pcp, -(val)) #define raw_cpu_inc(pcp) raw_cpu_add(pcp, 1) #define raw_cpu_dec(pcp) raw_cpu_sub(pcp, 1) #define raw_cpu_sub_return(pcp, val) raw_cpu_add_return(pcp, -(typeof(pcp))(val)) #define raw_cpu_inc_return(pcp) raw_cpu_add_return(pcp, 1) #define raw_cpu_dec_return(pcp) raw_cpu_add_return(pcp, -1) /* * Operations for contexts that are safe from preemption/interrupts. These * operations verify that preemption is disabled. */ #define __this_cpu_read(pcp) \ ({ \ __this_cpu_preempt_check("read"); \ raw_cpu_read(pcp); \ }) #define __this_cpu_write(pcp, val) \ ({ \ __this_cpu_preempt_check("write"); \ raw_cpu_write(pcp, val); \ }) #define __this_cpu_add(pcp, val) \ ({ \ __this_cpu_preempt_check("add"); \ raw_cpu_add(pcp, val); \ }) #define __this_cpu_and(pcp, val) \ ({ \ __this_cpu_preempt_check("and"); \ raw_cpu_and(pcp, val); \ }) #define __this_cpu_or(pcp, val) \ ({ \ __this_cpu_preempt_check("or"); \ raw_cpu_or(pcp, val); \ }) #define __this_cpu_add_return(pcp, val) \ ({ \ __this_cpu_preempt_check("add_return"); \ raw_cpu_add_return(pcp, val); \ }) #define __this_cpu_xchg(pcp, nval) \ ({ \ __this_cpu_preempt_check("xchg"); \ raw_cpu_xchg(pcp, nval); \ }) #define __this_cpu_cmpxchg(pcp, oval, nval) \ ({ \ __this_cpu_preempt_check("cmpxchg"); \ raw_cpu_cmpxchg(pcp, oval, nval); \ }) #define __this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \ ({ __this_cpu_preempt_check("cmpxchg_double"); \ raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2); \ }) #define __this_cpu_sub(pcp, val) __this_cpu_add(pcp, -(typeof(pcp))(val)) #define __this_cpu_inc(pcp) __this_cpu_add(pcp, 1) #define __this_cpu_dec(pcp) __this_cpu_sub(pcp, 1) #define __this_cpu_sub_return(pcp, val) __this_cpu_add_return(pcp, -(typeof(pcp))(val)) #define __this_cpu_inc_return(pcp) __this_cpu_add_return(pcp, 1) #define __this_cpu_dec_return(pcp) __this_cpu_add_return(pcp, -1) /* * Operations with implied preemption/interrupt protection. These * operations can be used without worrying about preemption or interrupt. */ #define this_cpu_read(pcp) __pcpu_size_call_return(this_cpu_read_, pcp) #define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val) #define this_cpu_add(pcp, val) __pcpu_size_call(this_cpu_add_, pcp, val) #define this_cpu_and(pcp, val) __pcpu_size_call(this_cpu_and_, pcp, val) #define this_cpu_or(pcp, val) __pcpu_size_call(this_cpu_or_, pcp, val) #define this_cpu_add_return(pcp, val) __pcpu_size_call_return2(this_cpu_add_return_, pcp, val) #define this_cpu_xchg(pcp, nval) __pcpu_size_call_return2(this_cpu_xchg_, pcp, nval) #define this_cpu_cmpxchg(pcp, oval, nval) \ __pcpu_size_call_return2(this_cpu_cmpxchg_, pcp, oval, nval) #define this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \ __pcpu_double_call_return_bool(this_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2) #define this_cpu_sub(pcp, val) this_cpu_add(pcp, -(typeof(pcp))(val)) #define this_cpu_inc(pcp) this_cpu_add(pcp, 1) #define this_cpu_dec(pcp) this_cpu_sub(pcp, 1) #define this_cpu_sub_return(pcp, val) this_cpu_add_return(pcp, -(typeof(pcp))(val)) #define this_cpu_inc_return(pcp) this_cpu_add_return(pcp, 1) #define this_cpu_dec_return(pcp) this_cpu_add_return(pcp, -1) #endif /* __ASSEMBLY__ */ #endif /* _LINUX_PERCPU_DEFS_H */