1 #ifndef __LINUX_COMPILER_H
2 #define __LINUX_COMPILER_H
7 # define __user __attribute__((noderef, address_space(1)))
8 # define __kernel __attribute__((address_space(0)))
9 # define __safe __attribute__((safe))
10 # define __force __attribute__((force))
11 # define __nocast __attribute__((nocast))
12 # define __iomem __attribute__((noderef, address_space(2)))
13 # define __must_hold(x) __attribute__((context(x,1,1)))
14 # define __acquires(x) __attribute__((context(x,0,1)))
15 # define __releases(x) __attribute__((context(x,1,0)))
16 # define __acquire(x) __context__(x,1)
17 # define __release(x) __context__(x,-1)
18 # define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
19 # define __percpu __attribute__((noderef, address_space(3)))
20 #ifdef CONFIG_SPARSE_RCU_POINTER
21 # define __rcu __attribute__((noderef, address_space(4)))
25 extern void __chk_user_ptr(const volatile void __user *);
26 extern void __chk_io_ptr(const volatile void __iomem *);
34 # define __chk_user_ptr(x) (void)0
35 # define __chk_io_ptr(x) (void)0
36 # define __builtin_warning(x, y...) (1)
37 # define __must_hold(x)
38 # define __acquires(x)
39 # define __releases(x)
40 # define __acquire(x) (void)0
41 # define __release(x) (void)0
42 # define __cond_lock(x,c) (c)
47 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
48 #define ___PASTE(a,b) a##b
49 #define __PASTE(a,b) ___PASTE(a,b)
54 #include <linux/compiler-gcc.h>
57 #ifdef CC_USING_HOTPATCH
58 #define notrace __attribute__((hotpatch(0,0)))
60 #define notrace __attribute__((no_instrument_function))
63 /* Intel compiler defines __GNUC__. So we will overwrite implementations
64 * coming from above header files here
66 #ifdef __INTEL_COMPILER
67 # include <linux/compiler-intel.h>
70 /* Clang compiler defines __GNUC__. So we will overwrite implementations
71 * coming from above header files here
74 #include <linux/compiler-clang.h>
78 * Generic compiler-dependent macros required for kernel
79 * build go below this comment. Actual compiler/compiler version
80 * specific implementations come from the above header files
83 struct ftrace_branch_data {
89 unsigned long correct;
90 unsigned long incorrect;
96 unsigned long miss_hit[2];
101 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
102 * to disable branch tracing on a per file basis.
104 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
105 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
106 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
108 #define likely_notrace(x) __builtin_expect(!!(x), 1)
109 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
111 #define __branch_check__(x, expect) ({ \
113 static struct ftrace_branch_data \
114 __attribute__((__aligned__(4))) \
115 __attribute__((section("_ftrace_annotated_branch"))) \
121 ______r = likely_notrace(x); \
122 ftrace_likely_update(&______f, ______r, expect); \
127 * Using __builtin_constant_p(x) to ignore cases where the return
128 * value is always the same. This idea is taken from a similar patch
129 * written by Daniel Walker.
132 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
135 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
138 #ifdef CONFIG_PROFILE_ALL_BRANCHES
140 * "Define 'is'", Bill Clinton
141 * "Define 'if'", Steven Rostedt
143 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
144 #define __trace_if(cond) \
145 if (__builtin_constant_p((cond)) ? !!(cond) : \
148 static struct ftrace_branch_data \
149 __attribute__((__aligned__(4))) \
150 __attribute__((section("_ftrace_branch"))) \
156 ______r = !!(cond); \
157 ______f.miss_hit[______r]++; \
160 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
163 # define likely(x) __builtin_expect(!!(x), 1)
164 # define unlikely(x) __builtin_expect(!!(x), 0)
167 /* Optimization barrier */
169 # define barrier() __memory_barrier()
173 # define barrier_data(ptr) barrier()
176 /* Unreachable code */
178 # define unreachable() do { } while (1)
182 # define RELOC_HIDE(ptr, off) \
183 ({ unsigned long __ptr; \
184 __ptr = (unsigned long) (ptr); \
185 (typeof(ptr)) (__ptr + (off)); })
188 #ifndef OPTIMIZER_HIDE_VAR
189 #define OPTIMIZER_HIDE_VAR(var) barrier()
192 /* Not-quite-unique ID. */
194 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
197 #include <uapi/linux/types.h>
199 static __always_inline void __read_once_size(const volatile void *p, void *res, int size)
202 case 1: *(__u8 *)res = *(volatile __u8 *)p; break;
203 case 2: *(__u16 *)res = *(volatile __u16 *)p; break;
204 case 4: *(__u32 *)res = *(volatile __u32 *)p; break;
205 case 8: *(__u64 *)res = *(volatile __u64 *)p; break;
208 __builtin_memcpy((void *)res, (const void *)p, size);
213 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
216 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
217 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
218 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
219 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
222 __builtin_memcpy((void *)p, (const void *)res, size);
228 * Prevent the compiler from merging or refetching reads or writes. The
229 * compiler is also forbidden from reordering successive instances of
230 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
231 * compiler is aware of some particular ordering. One way to make the
232 * compiler aware of ordering is to put the two invocations of READ_ONCE,
233 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
235 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
236 * data types like structs or unions. If the size of the accessed data
237 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
238 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a
239 * compile-time warning.
241 * Their two major use cases are: (1) Mediating communication between
242 * process-level code and irq/NMI handlers, all running on the same CPU,
243 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
244 * mutilate accesses that either do not require ordering or that interact
245 * with an explicit memory barrier or atomic instruction that provides the
249 #define READ_ONCE(x) \
250 ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
252 #define WRITE_ONCE(x, val) \
253 ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
256 * READ_ONCE_CTRL - Read a value heading a control dependency
257 * @x: The value to be read, heading the control dependency
259 * Control dependencies are tricky. See Documentation/memory-barriers.txt
260 * for important information on how to use them. Note that in many cases,
261 * use of smp_load_acquire() will be much simpler. Control dependencies
262 * should be avoided except on the hottest of hotpaths.
264 #define READ_ONCE_CTRL(x) \
266 typeof(x) __val = READ_ONCE(x); \
267 smp_read_barrier_depends(); /* Enforce control dependency. */ \
271 #endif /* __KERNEL__ */
273 #endif /* __ASSEMBLY__ */
277 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
278 * warning for each use, in hopes of speeding the functions removal.
280 * int __deprecated foo(void)
283 # define __deprecated /* unimplemented */
287 #define __deprecated_for_modules __deprecated
289 #define __deprecated_for_modules
296 #ifndef CONFIG_ENABLE_MUST_CHECK
300 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
302 #undef __deprecated_for_modules
304 #define __deprecated_for_modules
308 * Allow us to avoid 'defined but not used' warnings on functions and data,
309 * as well as force them to be emitted to the assembly file.
311 * As of gcc 3.4, static functions that are not marked with attribute((used))
312 * may be elided from the assembly file. As of gcc 3.4, static data not so
313 * marked will not be elided, but this may change in a future gcc version.
315 * NOTE: Because distributions shipped with a backported unit-at-a-time
316 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
317 * for gcc >=3.3 instead of 3.4.
319 * In prior versions of gcc, such functions and data would be emitted, but
320 * would be warned about except with attribute((unused)).
322 * Mark functions that are referenced only in inline assembly as __used so
323 * the code is emitted even though it appears to be unreferenced.
326 # define __used /* unimplemented */
329 #ifndef __maybe_unused
330 # define __maybe_unused /* unimplemented */
333 #ifndef __always_unused
334 # define __always_unused /* unimplemented */
342 * Rather then using noinline to prevent stack consumption, use
343 * noinline_for_stack instead. For documentation reasons.
345 #define noinline_for_stack noinline
347 #ifndef __always_inline
348 #define __always_inline inline
351 #endif /* __KERNEL__ */
354 * From the GCC manual:
356 * Many functions do not examine any values except their arguments,
357 * and have no effects except the return value. Basically this is
358 * just slightly more strict class than the `pure' attribute above,
359 * since function is not allowed to read global memory.
361 * Note that a function that has pointer arguments and examines the
362 * data pointed to must _not_ be declared `const'. Likewise, a
363 * function that calls a non-`const' function usually must not be
364 * `const'. It does not make sense for a `const' function to return
367 #ifndef __attribute_const__
368 # define __attribute_const__ /* unimplemented */
372 * Tell gcc if a function is cold. The compiler will assume any path
373 * directly leading to the call is unlikely.
380 /* Simple shorthand for a section definition */
382 # define __section(S) __attribute__ ((__section__(#S)))
389 /* Are two types/vars the same type (ignoring qualifiers)? */
391 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
394 /* Is this type a native word size -- useful for atomic operations */
395 #ifndef __native_word
396 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
399 /* Compile time object size, -1 for unknown */
400 #ifndef __compiletime_object_size
401 # define __compiletime_object_size(obj) -1
403 #ifndef __compiletime_warning
404 # define __compiletime_warning(message)
406 #ifndef __compiletime_error
407 # define __compiletime_error(message)
409 * Sparse complains of variable sized arrays due to the temporary variable in
410 * __compiletime_assert. Unfortunately we can't just expand it out to make
411 * sparse see a constant array size without breaking compiletime_assert on old
412 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
415 # define __compiletime_error_fallback(condition) \
416 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
419 #ifndef __compiletime_error_fallback
420 # define __compiletime_error_fallback(condition) do { } while (0)
423 #define __compiletime_assert(condition, msg, prefix, suffix) \
425 bool __cond = !(condition); \
426 extern void prefix ## suffix(void) __compiletime_error(msg); \
428 prefix ## suffix(); \
429 __compiletime_error_fallback(__cond); \
432 #define _compiletime_assert(condition, msg, prefix, suffix) \
433 __compiletime_assert(condition, msg, prefix, suffix)
436 * compiletime_assert - break build and emit msg if condition is false
437 * @condition: a compile-time constant condition to check
438 * @msg: a message to emit if condition is false
440 * In tradition of POSIX assert, this macro will break the build if the
441 * supplied condition is *false*, emitting the supplied error message if the
442 * compiler has support to do so.
444 #define compiletime_assert(condition, msg) \
445 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
447 #define compiletime_assert_atomic_type(t) \
448 compiletime_assert(__native_word(t), \
449 "Need native word sized stores/loads for atomicity.")
452 * Prevent the compiler from merging or refetching accesses. The compiler
453 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
454 * but only when the compiler is aware of some particular ordering. One way
455 * to make the compiler aware of ordering is to put the two invocations of
456 * ACCESS_ONCE() in different C statements.
458 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
459 * on a union member will work as long as the size of the member matches the
460 * size of the union and the size is smaller than word size.
462 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
463 * between process-level code and irq/NMI handlers, all running on the same CPU,
464 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
465 * mutilate accesses that either do not require ordering or that interact
466 * with an explicit memory barrier or atomic instruction that provides the
469 * If possible use READ_ONCE()/WRITE_ONCE() instead.
471 #define __ACCESS_ONCE(x) ({ \
472 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
473 (volatile typeof(x) *)&(x); })
474 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
476 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
477 #ifdef CONFIG_KPROBES
478 # define __kprobes __attribute__((__section__(".kprobes.text")))
479 # define nokprobe_inline __always_inline
482 # define nokprobe_inline inline
484 #endif /* __LINUX_COMPILER_H */