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 #include <uapi/linux/types.h>
190
191 static __always_inline void data_access_exceeds_word_size(void)
192 #ifdef __compiletime_warning
193 __compiletime_warning("data access exceeds word size and won't be atomic")
194 #endif
195 ;
196
data_access_exceeds_word_size(void)197 static __always_inline void data_access_exceeds_word_size(void)
198 {
199 }
200
__read_once_size(const volatile void * p,void * res,int size)201 static __always_inline void __read_once_size(const volatile void *p, void *res, int size)
202 {
203 switch (size) {
204 case 1: *(__u8 *)res = *(volatile __u8 *)p; break;
205 case 2: *(__u16 *)res = *(volatile __u16 *)p; break;
206 case 4: *(__u32 *)res = *(volatile __u32 *)p; break;
207 #ifdef CONFIG_64BIT
208 case 8: *(__u64 *)res = *(volatile __u64 *)p; break;
209 #endif
210 default:
211 barrier();
212 __builtin_memcpy((void *)res, (const void *)p, size);
213 data_access_exceeds_word_size();
214 barrier();
215 }
216 }
217
__write_once_size(volatile void * p,void * res,int size)218 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
219 {
220 switch (size) {
221 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
222 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
223 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
224 #ifdef CONFIG_64BIT
225 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
226 #endif
227 default:
228 barrier();
229 __builtin_memcpy((void *)p, (const void *)res, size);
230 data_access_exceeds_word_size();
231 barrier();
232 }
233 }
234
235 /*
236 * Prevent the compiler from merging or refetching reads or writes. The
237 * compiler is also forbidden from reordering successive instances of
238 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
239 * compiler is aware of some particular ordering. One way to make the
240 * compiler aware of ordering is to put the two invocations of READ_ONCE,
241 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
242 *
243 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
244 * data types like structs or unions. If the size of the accessed data
245 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
246 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a
247 * compile-time warning.
248 *
249 * Their two major use cases are: (1) Mediating communication between
250 * process-level code and irq/NMI handlers, all running on the same CPU,
251 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
252 * mutilate accesses that either do not require ordering or that interact
253 * with an explicit memory barrier or atomic instruction that provides the
254 * required ordering.
255 */
256
257 #define READ_ONCE(x) \
258 ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
259
260 #define WRITE_ONCE(x, val) \
261 ({ typeof(x) __val = (val); __write_once_size(&(x), &__val, sizeof(__val)); __val; })
262
263 #endif /* __KERNEL__ */
264
265 #endif /* __ASSEMBLY__ */
266
267 #ifdef __KERNEL__
268 /*
269 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
270 * warning for each use, in hopes of speeding the functions removal.
271 * Usage is:
272 * int __deprecated foo(void)
273 */
274 #ifndef __deprecated
275 # define __deprecated /* unimplemented */
276 #endif
277
278 #ifdef MODULE
279 #define __deprecated_for_modules __deprecated
280 #else
281 #define __deprecated_for_modules
282 #endif
283
284 #ifndef __must_check
285 #define __must_check
286 #endif
287
288 #ifndef CONFIG_ENABLE_MUST_CHECK
289 #undef __must_check
290 #define __must_check
291 #endif
292 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
293 #undef __deprecated
294 #undef __deprecated_for_modules
295 #define __deprecated
296 #define __deprecated_for_modules
297 #endif
298
299 /*
300 * Allow us to avoid 'defined but not used' warnings on functions and data,
301 * as well as force them to be emitted to the assembly file.
302 *
303 * As of gcc 3.4, static functions that are not marked with attribute((used))
304 * may be elided from the assembly file. As of gcc 3.4, static data not so
305 * marked will not be elided, but this may change in a future gcc version.
306 *
307 * NOTE: Because distributions shipped with a backported unit-at-a-time
308 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
309 * for gcc >=3.3 instead of 3.4.
310 *
311 * In prior versions of gcc, such functions and data would be emitted, but
312 * would be warned about except with attribute((unused)).
313 *
314 * Mark functions that are referenced only in inline assembly as __used so
315 * the code is emitted even though it appears to be unreferenced.
316 */
317 #ifndef __used
318 # define __used /* unimplemented */
319 #endif
320
321 #ifndef __maybe_unused
322 # define __maybe_unused /* unimplemented */
323 #endif
324
325 #ifndef __always_unused
326 # define __always_unused /* unimplemented */
327 #endif
328
329 #ifndef noinline
330 #define noinline
331 #endif
332
333 /*
334 * Rather then using noinline to prevent stack consumption, use
335 * noinline_for_stack instead. For documentation reasons.
336 */
337 #define noinline_for_stack noinline
338
339 #ifndef __always_inline
340 #define __always_inline inline
341 #endif
342
343 #endif /* __KERNEL__ */
344
345 /*
346 * From the GCC manual:
347 *
348 * Many functions do not examine any values except their arguments,
349 * and have no effects except the return value. Basically this is
350 * just slightly more strict class than the `pure' attribute above,
351 * since function is not allowed to read global memory.
352 *
353 * Note that a function that has pointer arguments and examines the
354 * data pointed to must _not_ be declared `const'. Likewise, a
355 * function that calls a non-`const' function usually must not be
356 * `const'. It does not make sense for a `const' function to return
357 * `void'.
358 */
359 #ifndef __attribute_const__
360 # define __attribute_const__ /* unimplemented */
361 #endif
362
363 /*
364 * Tell gcc if a function is cold. The compiler will assume any path
365 * directly leading to the call is unlikely.
366 */
367
368 #ifndef __cold
369 #define __cold
370 #endif
371
372 /* Simple shorthand for a section definition */
373 #ifndef __section
374 # define __section(S) __attribute__ ((__section__(#S)))
375 #endif
376
377 #ifndef __visible
378 #define __visible
379 #endif
380
381 /* Are two types/vars the same type (ignoring qualifiers)? */
382 #ifndef __same_type
383 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
384 #endif
385
386 /* Is this type a native word size -- useful for atomic operations */
387 #ifndef __native_word
388 # define __native_word(t) (sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
389 #endif
390
391 /* Compile time object size, -1 for unknown */
392 #ifndef __compiletime_object_size
393 # define __compiletime_object_size(obj) -1
394 #endif
395 #ifndef __compiletime_warning
396 # define __compiletime_warning(message)
397 #endif
398 #ifndef __compiletime_error
399 # define __compiletime_error(message)
400 /*
401 * Sparse complains of variable sized arrays due to the temporary variable in
402 * __compiletime_assert. Unfortunately we can't just expand it out to make
403 * sparse see a constant array size without breaking compiletime_assert on old
404 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
405 */
406 # ifndef __CHECKER__
407 # define __compiletime_error_fallback(condition) \
408 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
409 # endif
410 #endif
411 #ifndef __compiletime_error_fallback
412 # define __compiletime_error_fallback(condition) do { } while (0)
413 #endif
414
415 #define __compiletime_assert(condition, msg, prefix, suffix) \
416 do { \
417 bool __cond = !(condition); \
418 extern void prefix ## suffix(void) __compiletime_error(msg); \
419 if (__cond) \
420 prefix ## suffix(); \
421 __compiletime_error_fallback(__cond); \
422 } while (0)
423
424 #define _compiletime_assert(condition, msg, prefix, suffix) \
425 __compiletime_assert(condition, msg, prefix, suffix)
426
427 /**
428 * compiletime_assert - break build and emit msg if condition is false
429 * @condition: a compile-time constant condition to check
430 * @msg: a message to emit if condition is false
431 *
432 * In tradition of POSIX assert, this macro will break the build if the
433 * supplied condition is *false*, emitting the supplied error message if the
434 * compiler has support to do so.
435 */
436 #define compiletime_assert(condition, msg) \
437 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
438
439 #define compiletime_assert_atomic_type(t) \
440 compiletime_assert(__native_word(t), \
441 "Need native word sized stores/loads for atomicity.")
442
443 /*
444 * Prevent the compiler from merging or refetching accesses. The compiler
445 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
446 * but only when the compiler is aware of some particular ordering. One way
447 * to make the compiler aware of ordering is to put the two invocations of
448 * ACCESS_ONCE() in different C statements.
449 *
450 * This macro does absolutely -nothing- to prevent the CPU from reordering,
451 * merging, or refetching absolutely anything at any time. Its main intended
452 * use is to mediate communication between process-level code and irq/NMI
453 * handlers, all running on the same CPU.
454 */
455 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
456
457 /**
458 * lockless_dereference() - safely load a pointer for later dereference
459 * @p: The pointer to load
460 *
461 * Similar to rcu_dereference(), but for situations where the pointed-to
462 * object's lifetime is managed by something other than RCU. That
463 * "something other" might be reference counting or simple immortality.
464 */
465 #define lockless_dereference(p) \
466 ({ \
467 typeof(p) _________p1 = ACCESS_ONCE(p); \
468 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
469 (_________p1); \
470 })
471
472 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
473 #ifdef CONFIG_KPROBES
474 # define __kprobes __attribute__((__section__(".kprobes.text")))
475 # define nokprobe_inline __always_inline
476 #else
477 # define __kprobes
478 # define nokprobe_inline inline
479 #endif
480 #endif /* __LINUX_COMPILER_H */
481