xref: /linux/include/linux/compiler.h (revision 00a6d7b6762c27d441e9ac8faff36384bc0fc180)
1 #ifndef __LINUX_COMPILER_H
2 #define __LINUX_COMPILER_H
3 
4 #ifndef __ASSEMBLY__
5 
6 #ifdef __CHECKER__
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)))
22 #else
23 # define __rcu
24 #endif
25 extern void __chk_user_ptr(const volatile void __user *);
26 extern void __chk_io_ptr(const volatile void __iomem *);
27 #else
28 # define __user
29 # define __kernel
30 # define __safe
31 # define __force
32 # define __nocast
33 # define __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)
43 # define __percpu
44 # define __rcu
45 #endif
46 
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)
50 
51 #ifdef __KERNEL__
52 
53 #ifdef __GNUC__
54 #include <linux/compiler-gcc.h>
55 #endif
56 
57 #define notrace __attribute__((no_instrument_function))
58 
59 /* Intel compiler defines __GNUC__. So we will overwrite implementations
60  * coming from above header files here
61  */
62 #ifdef __INTEL_COMPILER
63 # include <linux/compiler-intel.h>
64 #endif
65 
66 /* Clang compiler defines __GNUC__. So we will overwrite implementations
67  * coming from above header files here
68  */
69 #ifdef __clang__
70 #include <linux/compiler-clang.h>
71 #endif
72 
73 /*
74  * Generic compiler-dependent macros required for kernel
75  * build go below this comment. Actual compiler/compiler version
76  * specific implementations come from the above header files
77  */
78 
79 struct ftrace_branch_data {
80 	const char *func;
81 	const char *file;
82 	unsigned line;
83 	union {
84 		struct {
85 			unsigned long correct;
86 			unsigned long incorrect;
87 		};
88 		struct {
89 			unsigned long miss;
90 			unsigned long hit;
91 		};
92 		unsigned long miss_hit[2];
93 	};
94 };
95 
96 /*
97  * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
98  * to disable branch tracing on a per file basis.
99  */
100 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
101     && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
102 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
103 
104 #define likely_notrace(x)	__builtin_expect(!!(x), 1)
105 #define unlikely_notrace(x)	__builtin_expect(!!(x), 0)
106 
107 #define __branch_check__(x, expect) ({					\
108 			int ______r;					\
109 			static struct ftrace_branch_data		\
110 				__attribute__((__aligned__(4)))		\
111 				__attribute__((section("_ftrace_annotated_branch"))) \
112 				______f = {				\
113 				.func = __func__,			\
114 				.file = __FILE__,			\
115 				.line = __LINE__,			\
116 			};						\
117 			______r = likely_notrace(x);			\
118 			ftrace_likely_update(&______f, ______r, expect); \
119 			______r;					\
120 		})
121 
122 /*
123  * Using __builtin_constant_p(x) to ignore cases where the return
124  * value is always the same.  This idea is taken from a similar patch
125  * written by Daniel Walker.
126  */
127 # ifndef likely
128 #  define likely(x)	(__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
129 # endif
130 # ifndef unlikely
131 #  define unlikely(x)	(__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
132 # endif
133 
134 #ifdef CONFIG_PROFILE_ALL_BRANCHES
135 /*
136  * "Define 'is'", Bill Clinton
137  * "Define 'if'", Steven Rostedt
138  */
139 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
140 #define __trace_if(cond) \
141 	if (__builtin_constant_p((cond)) ? !!(cond) :			\
142 	({								\
143 		int ______r;						\
144 		static struct ftrace_branch_data			\
145 			__attribute__((__aligned__(4)))			\
146 			__attribute__((section("_ftrace_branch")))	\
147 			______f = {					\
148 				.func = __func__,			\
149 				.file = __FILE__,			\
150 				.line = __LINE__,			\
151 			};						\
152 		______r = !!(cond);					\
153 		______f.miss_hit[______r]++;					\
154 		______r;						\
155 	}))
156 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
157 
158 #else
159 # define likely(x)	__builtin_expect(!!(x), 1)
160 # define unlikely(x)	__builtin_expect(!!(x), 0)
161 #endif
162 
163 /* Optimization barrier */
164 #ifndef barrier
165 # define barrier() __memory_barrier()
166 #endif
167 
168 /* Unreachable code */
169 #ifndef unreachable
170 # define unreachable() do { } while (1)
171 #endif
172 
173 #ifndef RELOC_HIDE
174 # define RELOC_HIDE(ptr, off)					\
175   ({ unsigned long __ptr;					\
176      __ptr = (unsigned long) (ptr);				\
177     (typeof(ptr)) (__ptr + (off)); })
178 #endif
179 
180 #ifndef OPTIMIZER_HIDE_VAR
181 #define OPTIMIZER_HIDE_VAR(var) barrier()
182 #endif
183 
184 /* Not-quite-unique ID. */
185 #ifndef __UNIQUE_ID
186 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
187 #endif
188 
189 #endif /* __KERNEL__ */
190 
191 #endif /* __ASSEMBLY__ */
192 
193 #ifdef __KERNEL__
194 /*
195  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
196  * warning for each use, in hopes of speeding the functions removal.
197  * Usage is:
198  * 		int __deprecated foo(void)
199  */
200 #ifndef __deprecated
201 # define __deprecated		/* unimplemented */
202 #endif
203 
204 #ifdef MODULE
205 #define __deprecated_for_modules __deprecated
206 #else
207 #define __deprecated_for_modules
208 #endif
209 
210 #ifndef __must_check
211 #define __must_check
212 #endif
213 
214 #ifndef CONFIG_ENABLE_MUST_CHECK
215 #undef __must_check
216 #define __must_check
217 #endif
218 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
219 #undef __deprecated
220 #undef __deprecated_for_modules
221 #define __deprecated
222 #define __deprecated_for_modules
223 #endif
224 
225 /*
226  * Allow us to avoid 'defined but not used' warnings on functions and data,
227  * as well as force them to be emitted to the assembly file.
228  *
229  * As of gcc 3.4, static functions that are not marked with attribute((used))
230  * may be elided from the assembly file.  As of gcc 3.4, static data not so
231  * marked will not be elided, but this may change in a future gcc version.
232  *
233  * NOTE: Because distributions shipped with a backported unit-at-a-time
234  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
235  * for gcc >=3.3 instead of 3.4.
236  *
237  * In prior versions of gcc, such functions and data would be emitted, but
238  * would be warned about except with attribute((unused)).
239  *
240  * Mark functions that are referenced only in inline assembly as __used so
241  * the code is emitted even though it appears to be unreferenced.
242  */
243 #ifndef __used
244 # define __used			/* unimplemented */
245 #endif
246 
247 #ifndef __maybe_unused
248 # define __maybe_unused		/* unimplemented */
249 #endif
250 
251 #ifndef __always_unused
252 # define __always_unused	/* unimplemented */
253 #endif
254 
255 #ifndef noinline
256 #define noinline
257 #endif
258 
259 /*
260  * Rather then using noinline to prevent stack consumption, use
261  * noinline_for_stack instead.  For documentation reasons.
262  */
263 #define noinline_for_stack noinline
264 
265 #ifndef __always_inline
266 #define __always_inline inline
267 #endif
268 
269 #endif /* __KERNEL__ */
270 
271 /*
272  * From the GCC manual:
273  *
274  * Many functions do not examine any values except their arguments,
275  * and have no effects except the return value.  Basically this is
276  * just slightly more strict class than the `pure' attribute above,
277  * since function is not allowed to read global memory.
278  *
279  * Note that a function that has pointer arguments and examines the
280  * data pointed to must _not_ be declared `const'.  Likewise, a
281  * function that calls a non-`const' function usually must not be
282  * `const'.  It does not make sense for a `const' function to return
283  * `void'.
284  */
285 #ifndef __attribute_const__
286 # define __attribute_const__	/* unimplemented */
287 #endif
288 
289 /*
290  * Tell gcc if a function is cold. The compiler will assume any path
291  * directly leading to the call is unlikely.
292  */
293 
294 #ifndef __cold
295 #define __cold
296 #endif
297 
298 /* Simple shorthand for a section definition */
299 #ifndef __section
300 # define __section(S) __attribute__ ((__section__(#S)))
301 #endif
302 
303 #ifndef __visible
304 #define __visible
305 #endif
306 
307 /* Are two types/vars the same type (ignoring qualifiers)? */
308 #ifndef __same_type
309 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
310 #endif
311 
312 /* Is this type a native word size -- useful for atomic operations */
313 #ifndef __native_word
314 # define __native_word(t) (sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
315 #endif
316 
317 /* Compile time object size, -1 for unknown */
318 #ifndef __compiletime_object_size
319 # define __compiletime_object_size(obj) -1
320 #endif
321 #ifndef __compiletime_warning
322 # define __compiletime_warning(message)
323 #endif
324 #ifndef __compiletime_error
325 # define __compiletime_error(message)
326 # define __compiletime_error_fallback(condition) \
327 	do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
328 #else
329 # define __compiletime_error_fallback(condition) do { } while (0)
330 #endif
331 
332 #define __compiletime_assert(condition, msg, prefix, suffix)		\
333 	do {								\
334 		bool __cond = !(condition);				\
335 		extern void prefix ## suffix(void) __compiletime_error(msg); \
336 		if (__cond)						\
337 			prefix ## suffix();				\
338 		__compiletime_error_fallback(__cond);			\
339 	} while (0)
340 
341 #define _compiletime_assert(condition, msg, prefix, suffix) \
342 	__compiletime_assert(condition, msg, prefix, suffix)
343 
344 /**
345  * compiletime_assert - break build and emit msg if condition is false
346  * @condition: a compile-time constant condition to check
347  * @msg:       a message to emit if condition is false
348  *
349  * In tradition of POSIX assert, this macro will break the build if the
350  * supplied condition is *false*, emitting the supplied error message if the
351  * compiler has support to do so.
352  */
353 #define compiletime_assert(condition, msg) \
354 	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
355 
356 #define compiletime_assert_atomic_type(t)				\
357 	compiletime_assert(__native_word(t),				\
358 		"Need native word sized stores/loads for atomicity.")
359 
360 /*
361  * Prevent the compiler from merging or refetching accesses.  The compiler
362  * is also forbidden from reordering successive instances of ACCESS_ONCE(),
363  * but only when the compiler is aware of some particular ordering.  One way
364  * to make the compiler aware of ordering is to put the two invocations of
365  * ACCESS_ONCE() in different C statements.
366  *
367  * This macro does absolutely -nothing- to prevent the CPU from reordering,
368  * merging, or refetching absolutely anything at any time.  Its main intended
369  * use is to mediate communication between process-level code and irq/NMI
370  * handlers, all running on the same CPU.
371  */
372 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
373 
374 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
375 #ifdef CONFIG_KPROBES
376 # define __kprobes	__attribute__((__section__(".kprobes.text")))
377 #else
378 # define __kprobes
379 #endif
380 #endif /* __LINUX_COMPILER_H */
381