+/*
+ * 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
+
/*
* Base implementations of per-CPU variable declarations and definitions, where
* the section in which the variable is to be placed is provided by the
#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.
- *
- * + 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)
-
/*
* s390 and alpha modules require percpu variables to be defined as
* weak to force the compiler to generate GOT based external
#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))
+#define __raw_get_cpu_var(var) (*raw_cpu_ptr(&(var)))
+#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
+
+/* keep until we have removed all uses of __this_cpu_ptr */
+#define __this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
+
+/*
+ * 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 protection. These operations can be
+ * used without worrying about preemption. Note that interrupts may still
+ * occur while an operation is in progress and if the interrupt modifies
+ * the variable too then RMW actions may not be reliable.
+ */
+#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 */
projects / firefly-linux-kernel-4.4.55.git / blobdiff