Release 4.7 include/linux/compiler.h
#ifndef __LINUX_COMPILER_H
#define __LINUX_COMPILER_H
#ifndef __ASSEMBLY__
#ifdef __CHECKER__
# define __user __attribute__((noderef, address_space(1)))
# define __kernel __attribute__((address_space(0)))
# define __safe __attribute__((safe))
# define __force __attribute__((force))
# define __nocast __attribute__((nocast))
# define __iomem __attribute__((noderef, address_space(2)))
# define __must_hold(x) __attribute__((context(x,1,1)))
# define __acquires(x) __attribute__((context(x,0,1)))
# define __releases(x) __attribute__((context(x,1,0)))
# define __acquire(x) __context__(x,1)
# define __release(x) __context__(x,-1)
# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
# define __percpu __attribute__((noderef, address_space(3)))
# define __pmem __attribute__((noderef, address_space(5)))
#ifdef CONFIG_SPARSE_RCU_POINTER
# define __rcu __attribute__((noderef, address_space(4)))
#else /* CONFIG_SPARSE_RCU_POINTER */
# define __rcu
#endif /* CONFIG_SPARSE_RCU_POINTER */
# define __private __attribute__((noderef))
extern void __chk_user_ptr(const volatile void __user *);
extern void __chk_io_ptr(const volatile void __iomem *);
# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
#else /* __CHECKER__ */
# define __user
# define __kernel
# define __safe
# define __force
# define __nocast
# define __iomem
# define __chk_user_ptr(x) (void)0
# define __chk_io_ptr(x) (void)0
# define __builtin_warning(x, y...) (1)
# define __must_hold(x)
# define __acquires(x)
# define __releases(x)
# define __acquire(x) (void)0
# define __release(x) (void)0
# define __cond_lock(x,c) (c)
# define __percpu
# define __rcu
# define __pmem
# define __private
# define ACCESS_PRIVATE(p, member) ((p)->member)
#endif /* __CHECKER__ */
/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
#define ___PASTE(a,b) a##b
#define __PASTE(a,b) ___PASTE(a,b)
#ifdef __KERNEL__
#ifdef __GNUC__
#include <linux/compiler-gcc.h>
#endif
#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
#define notrace __attribute__((hotpatch(0,0)))
#else
#define notrace __attribute__((no_instrument_function))
#endif
/* Intel compiler defines __GNUC__. So we will overwrite implementations
* coming from above header files here
*/
#ifdef __INTEL_COMPILER
# include <linux/compiler-intel.h>
#endif
/* Clang compiler defines __GNUC__. So we will overwrite implementations
* coming from above header files here
*/
#ifdef __clang__
#include <linux/compiler-clang.h>
#endif
/*
* Generic compiler-dependent macros required for kernel
* build go below this comment. Actual compiler/compiler version
* specific implementations come from the above header files
*/
struct ftrace_branch_data {
const char *func;
const char *file;
unsigned line;
union {
struct {
unsigned long correct;
unsigned long incorrect;
};
struct {
unsigned long miss;
unsigned long hit;
};
unsigned long miss_hit[2];
};
};
/*
* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
* to disable branch tracing on a per file basis.
*/
#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
#define likely_notrace(x) __builtin_expect(!!(x), 1)
#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
#define __branch_check__(x, expect) ({ \
int ______r; \
static struct ftrace_branch_data \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_annotated_branch"))) \
______f = { \
.func = __func__, \
.file = __FILE__, \
.line = __LINE__, \
}; \
______r = likely_notrace(x); \
ftrace_likely_update(&______f, ______r, expect); \
______r; \
})
/*
* Using __builtin_constant_p(x) to ignore cases where the return
* value is always the same. This idea is taken from a similar patch
* written by Daniel Walker.
*/
# ifndef likely
# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
# endif
# ifndef unlikely
# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
# endif
#ifdef CONFIG_PROFILE_ALL_BRANCHES
/*
* "Define 'is'", Bill Clinton
* "Define 'if'", Steven Rostedt
*/
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
#define __trace_if(cond) \
if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
({ \
int ______r; \
static struct ftrace_branch_data \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_branch"))) \
______f = { \
.func = __func__, \
.file = __FILE__, \
.line = __LINE__, \
}; \
______r = !!(cond); \
______f.miss_hit[______r]++; \
______r; \
}))
#endif /* CONFIG_PROFILE_ALL_BRANCHES */
#else
# define likely(x) __builtin_expect(!!(x), 1)
# define unlikely(x) __builtin_expect(!!(x), 0)
#endif
/* Optimization barrier */
#ifndef barrier
# define barrier() __memory_barrier()
#endif
#ifndef barrier_data
# define barrier_data(ptr) barrier()
#endif
/* Unreachable code */
#ifndef unreachable
# define unreachable() do { } while (1)
#endif
#ifndef RELOC_HIDE
# define RELOC_HIDE(ptr, off) \
({ unsigned long __ptr; \
__ptr = (unsigned long) (ptr); \
(typeof(ptr)) (__ptr + (off)); })
#endif
#ifndef OPTIMIZER_HIDE_VAR
#define OPTIMIZER_HIDE_VAR(var) barrier()
#endif
/* Not-quite-unique ID. */
#ifndef __UNIQUE_ID
# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
#endif
#include <uapi/linux/types.h>
#define __READ_ONCE_SIZE \
({ \
switch (size) { \
case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
default: \
barrier(); \
__builtin_memcpy((void *)res, (const void *)p, size); \
barrier(); \
} \
})
static __always_inline
void __read_once_size(const volatile void *p, void *res, int size)
{
__READ_ONCE_SIZE;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| christian borntraeger | christian borntraeger | 19 | 86.36% | 1 | 33.33% |
| andrey ryabinin | andrey ryabinin | 2 | 9.09% | 1 | 33.33% |
| linus torvalds | linus torvalds | 1 | 4.55% | 1 | 33.33% |
| Total | 22 | 100.00% | 3 | 100.00% |
#ifdef CONFIG_KASAN
/*
* This function is not 'inline' because __no_sanitize_address confilcts
* with inlining. Attempt to inline it may cause a build failure.
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
* '__maybe_unused' allows us to avoid defined-but-not-used warnings.
*/
static __no_sanitize_address __maybe_unused
void __read_once_size_nocheck(const volatile void *p, void *res, int size)
{
__READ_ONCE_SIZE;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| andrey ryabinin | andrey ryabinin | 19 | 82.61% | 1 | 50.00% |
| christian borntraeger | christian borntraeger | 4 | 17.39% | 1 | 50.00% |
| Total | 23 | 100.00% | 2 | 100.00% |
#else
static __always_inline
void __read_once_size_nocheck(const volatile void *p, void *res, int size)
{
__READ_ONCE_SIZE;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| andrey ryabinin | andrey ryabinin | 15 | 68.18% | 1 | 50.00% |
| christian borntraeger | christian borntraeger | 7 | 31.82% | 1 | 50.00% |
| Total | 22 | 100.00% | 2 | 100.00% |
#endif
static __always_inline void __write_once_size(volatile void *p, void *res, int size)
{
switch (size) {
case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
default:
barrier();
__builtin_memcpy((void *)p, (const void *)res, size);
barrier();
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| christian borntraeger | christian borntraeger | 126 | 100.00% | 2 | 100.00% |
| Total | 126 | 100.00% | 2 | 100.00% |
/*
* Prevent the compiler from merging or refetching reads or writes. The
* compiler is also forbidden from reordering successive instances of
* READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
* compiler is aware of some particular ordering. One way to make the
* compiler aware of ordering is to put the two invocations of READ_ONCE,
* WRITE_ONCE or ACCESS_ONCE() in different C statements.
*
* In contrast to ACCESS_ONCE these two macros will also work on aggregate
* data types like structs or unions. If the size of the accessed data
* type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
* READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at
* least two memcpy()s: one for the __builtin_memcpy() and then one for
* the macro doing the copy of variable - '__u' allocated on the stack.
*
* Their two major use cases are: (1) Mediating communication between
* process-level code and irq/NMI handlers, all running on the same CPU,
* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
* mutilate accesses that either do not require ordering or that interact
* with an explicit memory barrier or atomic instruction that provides the
* required ordering.
*/
#define __READ_ONCE(x, check) \
({ \
union { typeof(x) __val; char __c[1]; } __u; \
if (check) \
__read_once_size(&(x), __u.__c, sizeof(x)); \
else \
__read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
__u.__val; \
})
#define READ_ONCE(x) __READ_ONCE(x, 1)
/*
* Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
* to hide memory access from KASAN.
*/
#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
#define WRITE_ONCE(x, val) \
({ \
union { typeof(x) __val; char __c[1]; } __u = \
{ .__val = (__force typeof(x)) (val) }; \
__write_once_size(&(x), __u.__c, sizeof(x)); \
__u.__val; \
})
/**
* smp_cond_acquire() - Spin wait for cond with ACQUIRE ordering
* @cond: boolean expression to wait for
*
* Equivalent to using smp_load_acquire() on the condition variable but employs
* the control dependency of the wait to reduce the barrier on many platforms.
*
* The control dependency provides a LOAD->STORE order, the additional RMB
* provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
* aka. ACQUIRE.
*/
#define smp_cond_acquire(cond) do { \
while (!(cond)) \
cpu_relax(); \
smp_rmb(); /* ctrl + rmb := acquire */ \
} while (0)
#endif /* __KERNEL__ */
#endif /* __ASSEMBLY__ */
#ifdef __KERNEL__
/*
* Allow us to mark functions as 'deprecated' and have gcc emit a nice
* warning for each use, in hopes of speeding the functions removal.
* Usage is:
* int __deprecated foo(void)
*/
#ifndef __deprecated
# define __deprecated
/* unimplemented */
#endif
#ifdef MODULE
#define __deprecated_for_modules __deprecated
#else
#define __deprecated_for_modules
#endif
#ifndef __must_check
#define __must_check
#endif
#ifndef CONFIG_ENABLE_MUST_CHECK
#undef __must_check
#define __must_check
#endif
#ifndef CONFIG_ENABLE_WARN_DEPRECATED
#undef __deprecated
#undef __deprecated_for_modules
#define __deprecated
#define __deprecated_for_modules
#endif
#ifndef __malloc
#define __malloc
#endif
/*
* Allow us to avoid 'defined but not used' warnings on functions and data,
* as well as force them to be emitted to the assembly file.
*
* As of gcc 3.4, static functions that are not marked with attribute((used))
* may be elided from the assembly file. As of gcc 3.4, static data not so
* marked will not be elided, but this may change in a future gcc version.
*
* NOTE: Because distributions shipped with a backported unit-at-a-time
* compiler in gcc 3.3, we must define __used to be __attribute__((used))
* for gcc >=3.3 instead of 3.4.
*
* In prior versions of gcc, such functions and data would be emitted, but
* would be warned about except with attribute((unused)).
*
* Mark functions that are referenced only in inline assembly as __used so
* the code is emitted even though it appears to be unreferenced.
*/
#ifndef __used
# define __used
/* unimplemented */
#endif
#ifndef __maybe_unused
# define __maybe_unused
/* unimplemented */
#endif
#ifndef __always_unused
# define __always_unused
/* unimplemented */
#endif
#ifndef noinline
#define noinline
#endif
/*
* Rather then using noinline to prevent stack consumption, use
* noinline_for_stack instead. For documentation reasons.
*/
#define noinline_for_stack noinline
#ifndef __always_inline
#define __always_inline inline
#endif
#endif /* __KERNEL__ */
/*
* From the GCC manual:
*
* Many functions do not examine any values except their arguments,
* and have no effects except the return value. Basically this is
* just slightly more strict class than the `pure' attribute above,
* since function is not allowed to read global memory.
*
* Note that a function that has pointer arguments and examines the
* data pointed to must _not_ be declared `const'. Likewise, a
* function that calls a non-`const' function usually must not be
* `const'. It does not make sense for a `const' function to return
* `void'.
*/
#ifndef __attribute_const__
# define __attribute_const__
/* unimplemented */
#endif
/*
* Tell gcc if a function is cold. The compiler will assume any path
* directly leading to the call is unlikely.
*/
#ifndef __cold
#define __cold
#endif
/* Simple shorthand for a section definition */
#ifndef __section
# define __section(S) __attribute__ ((__section__(#S)))
#endif
#ifndef __visible
#define __visible
#endif
/*
* Assume alignment of return value.
*/
#ifndef __assume_aligned
#define __assume_aligned(a, ...)
#endif
/* Are two types/vars the same type (ignoring qualifiers)? */
#ifndef __same_type
# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
#endif
/* Is this type a native word size -- useful for atomic operations */
#ifndef __native_word
# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
#endif
/* Compile time object size, -1 for unknown */
#ifndef __compiletime_object_size
# define __compiletime_object_size(obj) -1
#endif
#ifndef __compiletime_warning
# define __compiletime_warning(message)
#endif
#ifndef __compiletime_error
# define __compiletime_error(message)
/*
* Sparse complains of variable sized arrays due to the temporary variable in
* __compiletime_assert. Unfortunately we can't just expand it out to make
* sparse see a constant array size without breaking compiletime_assert on old
* versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
*/
# ifndef __CHECKER__
# define __compiletime_error_fallback(condition) \
do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
# endif
#endif
#ifndef __compiletime_error_fallback
# define __compiletime_error_fallback(condition) do { } while (0)
#endif
#define __compiletime_assert(condition, msg, prefix, suffix) \
do { \
bool __cond = !(condition); \
extern void prefix ## suffix(void) __compiletime_error(msg); \
if (__cond) \
prefix ## suffix(); \
__compiletime_error_fallback(__cond); \
} while (0)
#define _compiletime_assert(condition, msg, prefix, suffix) \
__compiletime_assert(condition, msg, prefix, suffix)
/**
* compiletime_assert - break build and emit msg if condition is false
* @condition: a compile-time constant condition to check
* @msg: a message to emit if condition is false
*
* In tradition of POSIX assert, this macro will break the build if the
* supplied condition is *false*, emitting the supplied error message if the
* compiler has support to do so.
*/
#define compiletime_assert(condition, msg) \
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
#define compiletime_assert_atomic_type(t) \
compiletime_assert(__native_word(t), \
"Need native word sized stores/loads for atomicity.")
/*
* Prevent the compiler from merging or refetching accesses. The compiler
* is also forbidden from reordering successive instances of ACCESS_ONCE(),
* but only when the compiler is aware of some particular ordering. One way
* to make the compiler aware of ordering is to put the two invocations of
* ACCESS_ONCE() in different C statements.
*
* ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
* on a union member will work as long as the size of the member matches the
* size of the union and the size is smaller than word size.
*
* The major use cases of ACCESS_ONCE used to be (1) Mediating communication
* between process-level code and irq/NMI handlers, all running on the same CPU,
* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
* mutilate accesses that either do not require ordering or that interact
* with an explicit memory barrier or atomic instruction that provides the
* required ordering.
*
* If possible use READ_ONCE()/WRITE_ONCE() instead.
*/
#define __ACCESS_ONCE(x) ({ \
__maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
(volatile typeof(x) *)&(x); })
#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
/**
* lockless_dereference() - safely load a pointer for later dereference
* @p: The pointer to load
*
* Similar to rcu_dereference(), but for situations where the pointed-to
* object's lifetime is managed by something other than RCU. That
* "something other" might be reference counting or simple immortality.
*/
#define lockless_dereference(p) \
({ \
typeof(p) _________p1 = READ_ONCE(p); \
smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
(_________p1); \
})
/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
#ifdef CONFIG_KPROBES
# define __kprobes __attribute__((__section__(".kprobes.text")))
# define nokprobe_inline __always_inline
#else
# define __kprobes
# define nokprobe_inline inline
#endif
#endif /* __LINUX_COMPILER_H */
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| linus torvalds | linus torvalds | 203 | 16.90% | 18 | 19.57% |
| christian borntraeger | christian borntraeger | 194 | 16.15% | 6 | 6.52% |
| steven rostedt | steven rostedt | 143 | 11.91% | 5 | 5.43% |
| andrew morton | andrew morton | 72 | 6.00% | 7 | 7.61% |
| andrey ryabinin | andrey ryabinin | 68 | 5.66% | 1 | 1.09% |
| rusty russell | rusty russell | 55 | 4.58% | 3 | 3.26% |
| daniel santos | daniel santos | 54 | 4.50% | 2 | 2.17% |
| arjan van de ven | arjan van de ven | 43 | 3.58% | 4 | 4.35% |
| peter zijlstra | peter zijlstra | 40 | 3.33% | 3 | 3.26% |
| paul e. mckenney | paul e. mckenney | 32 | 2.66% | 4 | 4.35% |
| boqun feng | boqun feng | 29 | 2.41% | 1 | 1.09% |
| andi kleen | andi kleen | 26 | 2.16% | 3 | 3.26% |
| josh triplett | josh triplett | 23 | 1.92% | 3 | 3.26% |
| masami hiramatsu | masami hiramatsu | 23 | 1.92% | 2 | 2.17% |
| rasmus villemoes | rasmus villemoes | 22 | 1.83% | 2 | 2.17% |
| jeff garzik | jeff garzik | 17 | 1.42% | 1 | 1.09% |
| david woodhouse | david woodhouse | 16 | 1.33% | 2 | 2.17% |
| david rientjes | david rientjes | 14 | 1.17% | 1 | 1.09% |
| sam ravnborg | sam ravnborg | 13 | 1.08% | 1 | 1.09% |
| cesar eduardo barros | cesar eduardo barros | 12 | 1.00% | 1 | 1.09% |
| daniel borkmann | daniel borkmann | 12 | 1.00% | 1 | 1.09% |
| david daney | david daney | 11 | 0.92% | 1 | 1.09% |
| james hogan | james hogan | 11 | 0.92% | 1 | 1.09% |
| mark charlebois | mark charlebois | 9 | 0.75% | 1 | 1.09% |
| li zefan | li zefan | 9 | 0.75% | 1 | 1.09% |
| heiko carstens | heiko carstens | 9 | 0.75% | 1 | 1.09% |
| witold baryluk | witold baryluk | 7 | 0.58% | 1 | 1.09% |
| bart van assche | bart van assche | 7 | 0.58% | 1 | 1.09% |
| robert love | robert love | 5 | 0.42% | 2 | 2.17% |
| dan williams | dan williams | 4 | 0.33% | 1 | 1.09% |
| ross zwisler | ross zwisler | 3 | 0.25% | 1 | 1.09% |
| al viro | al viro | 2 | 0.17% | 1 | 1.09% |
| richard henderson | richard henderson | 2 | 0.17% | 1 | 1.09% |
| russ cox | russ cox | 2 | 0.17% | 1 | 1.09% |
| christoph hellwig | christoph hellwig | 2 | 0.17% | 1 | 1.09% |
| olaf hering | olaf hering | 2 | 0.17% | 1 | 1.09% |
| preeti u. murthy | preeti u. murthy | 1 | 0.08% | 1 | 1.09% |
| konrad rzeszutek wilk | konrad rzeszutek wilk | 1 | 0.08% | 1 | 1.09% |
| arnd bergmann | arnd bergmann | 1 | 0.08% | 1 | 1.09% |
| alexander stein | alexander stein | 1 | 0.08% | 1 | 1.09% |
| stephen rothwell | stephen rothwell | 1 | 0.08% | 1 | 1.09% |
| Total | 1201 | 100.00% | 92 | 100.00% |
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