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 # define __pmem __attribute__((noderef, address_space(5)))
21 #ifdef CONFIG_SPARSE_RCU_POINTER
22 # define __rcu __attribute__((noderef, address_space(4)))
23 #else
24 # define __rcu
25 #endif
26 extern void __chk_user_ptr(const volatile void __user *);
27 extern void __chk_io_ptr(const volatile void __iomem *);
28 #else
29 # define __user
30 # define __kernel
31 # define __safe
32 # define __force
33 # define __nocast
34 # define __iomem
35 # define __chk_user_ptr(x) (void)0
36 # define __chk_io_ptr(x) (void)0
37 # define __builtin_warning(x, y...) (1)
38 # define __must_hold(x)
39 # define __acquires(x)
40 # define __releases(x)
41 # define __acquire(x) (void)0
42 # define __release(x) (void)0
43 # define __cond_lock(x,c) (c)
44 # define __percpu
45 # define __rcu
46 # define __pmem
47 #endif
48
49 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
50 #define ___PASTE(a,b) a##b
51 #define __PASTE(a,b) ___PASTE(a,b)
52
53 #ifdef __KERNEL__
54
55 #ifdef __GNUC__
56 #include <linux/compiler-gcc.h>
57 #endif
58
59 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
60 #define notrace __attribute__((hotpatch(0,0)))
61 #else
62 #define notrace __attribute__((no_instrument_function))
63 #endif
64
65 /* Intel compiler defines __GNUC__. So we will overwrite implementations
66 * coming from above header files here
67 */
68 #ifdef __INTEL_COMPILER
69 # include <linux/compiler-intel.h>
70 #endif
71
72 /* Clang compiler defines __GNUC__. So we will overwrite implementations
73 * coming from above header files here
74 */
75 #ifdef __clang__
76 #include <linux/compiler-clang.h>
77 #endif
78
79 /*
80 * Generic compiler-dependent macros required for kernel
81 * build go below this comment. Actual compiler/compiler version
82 * specific implementations come from the above header files
83 */
84
85 struct ftrace_branch_data {
86 const char *func;
87 const char *file;
88 unsigned line;
89 union {
90 struct {
91 unsigned long correct;
92 unsigned long incorrect;
93 };
94 struct {
95 unsigned long miss;
96 unsigned long hit;
97 };
98 unsigned long miss_hit[2];
99 };
100 };
101
102 /*
103 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
104 * to disable branch tracing on a per file basis.
105 */
106 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
107 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
108 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
109
110 #define likely_notrace(x) __builtin_expect(!!(x), 1)
111 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
112
113 #define __branch_check__(x, expect) ({ \
114 int ______r; \
115 static struct ftrace_branch_data \
116 __attribute__((__aligned__(4))) \
117 __attribute__((section("_ftrace_annotated_branch"))) \
118 ______f = { \
119 .func = __func__, \
120 .file = __FILE__, \
121 .line = __LINE__, \
122 }; \
123 ______r = likely_notrace(x); \
124 ftrace_likely_update(&______f, ______r, expect); \
125 ______r; \
126 })
127
128 /*
129 * Using __builtin_constant_p(x) to ignore cases where the return
130 * value is always the same. This idea is taken from a similar patch
131 * written by Daniel Walker.
132 */
133 # ifndef likely
134 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
135 # endif
136 # ifndef unlikely
137 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
138 # endif
139
140 #ifdef CONFIG_PROFILE_ALL_BRANCHES
141 /*
142 * "Define 'is'", Bill Clinton
143 * "Define 'if'", Steven Rostedt
144 */
145 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
146 #define __trace_if(cond) \
147 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
148 ({ \
149 int ______r; \
150 static struct ftrace_branch_data \
151 __attribute__((__aligned__(4))) \
152 __attribute__((section("_ftrace_branch"))) \
153 ______f = { \
154 .func = __func__, \
155 .file = __FILE__, \
156 .line = __LINE__, \
157 }; \
158 ______r = !!(cond); \
159 ______f.miss_hit[______r]++; \
160 ______r; \
161 }))
162 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
163
164 #else
165 # define likely(x) __builtin_expect(!!(x), 1)
166 # define unlikely(x) __builtin_expect(!!(x), 0)
167 #endif
168
169 /* Optimization barrier */
170 #ifndef barrier
171 # define barrier() __memory_barrier()
172 #endif
173
174 #ifndef barrier_data
175 # define barrier_data(ptr) barrier()
176 #endif
177
178 /* Unreachable code */
179 #ifndef unreachable
180 # define unreachable() do { } while (1)
181 #endif
182
183 #ifndef RELOC_HIDE
184 # define RELOC_HIDE(ptr, off) \
185 ({ unsigned long __ptr; \
186 __ptr = (unsigned long) (ptr); \
187 (typeof(ptr)) (__ptr + (off)); })
188 #endif
189
190 #ifndef OPTIMIZER_HIDE_VAR
191 #define OPTIMIZER_HIDE_VAR(var) barrier()
192 #endif
193
194 /* Not-quite-unique ID. */
195 #ifndef __UNIQUE_ID
196 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
197 #endif
198
199 #include <linux/types.h>
200
201 #define __READ_ONCE_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 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
208 default: \
209 barrier(); \
210 __builtin_memcpy((void *)res, (const void *)p, size); \
211 barrier(); \
212 } \
213 })
214
215 static __always_inline
__read_once_size(const volatile void * p,void * res,int size)216 void __read_once_size(const volatile void *p, void *res, int size)
217 {
218 __READ_ONCE_SIZE;
219 }
220
221 #ifdef CONFIG_KASAN
222 /*
223 * This function is not 'inline' because __no_sanitize_address confilcts
224 * with inlining. Attempt to inline it may cause a build failure.
225 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
226 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
227 */
228 static __no_sanitize_address __maybe_unused
__read_once_size_nocheck(const volatile void * p,void * res,int size)229 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
230 {
231 __READ_ONCE_SIZE;
232 }
233 #else
234 static __always_inline
__read_once_size_nocheck(const volatile void * p,void * res,int size)235 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
236 {
237 __READ_ONCE_SIZE;
238 }
239 #endif
240
__write_once_size(volatile void * p,void * res,int size)241 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
242 {
243 switch (size) {
244 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
245 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
246 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
247 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
248 default:
249 barrier();
250 __builtin_memcpy((void *)p, (const void *)res, size);
251 barrier();
252 }
253 }
254
255 /*
256 * Prevent the compiler from merging or refetching reads or writes. The
257 * compiler is also forbidden from reordering successive instances of
258 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
259 * compiler is aware of some particular ordering. One way to make the
260 * compiler aware of ordering is to put the two invocations of READ_ONCE,
261 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
262 *
263 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
264 * data types like structs or unions. If the size of the accessed data
265 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
266 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a
267 * compile-time warning.
268 *
269 * Their two major use cases are: (1) Mediating communication between
270 * process-level code and irq/NMI handlers, all running on the same CPU,
271 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
272 * mutilate accesses that either do not require ordering or that interact
273 * with an explicit memory barrier or atomic instruction that provides the
274 * required ordering.
275 */
276
277 #define __READ_ONCE(x, check) \
278 ({ \
279 union { typeof(x) __val; char __c[1]; } __u; \
280 if (check) \
281 __read_once_size(&(x), __u.__c, sizeof(x)); \
282 else \
283 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
284 __u.__val; \
285 })
286 #define READ_ONCE(x) __READ_ONCE(x, 1)
287
288 /*
289 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
290 * to hide memory access from KASAN.
291 */
292 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
293
294 #define WRITE_ONCE(x, val) \
295 ({ \
296 union { typeof(x) __val; char __c[1]; } __u = \
297 { .__val = (__force typeof(x)) (val) }; \
298 __write_once_size(&(x), __u.__c, sizeof(x)); \
299 __u.__val; \
300 })
301
302 /**
303 * smp_cond_acquire() - Spin wait for cond with ACQUIRE ordering
304 * @cond: boolean expression to wait for
305 *
306 * Equivalent to using smp_load_acquire() on the condition variable but employs
307 * the control dependency of the wait to reduce the barrier on many platforms.
308 *
309 * The control dependency provides a LOAD->STORE order, the additional RMB
310 * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
311 * aka. ACQUIRE.
312 */
313 #define smp_cond_acquire(cond) do { \
314 while (!(cond)) \
315 cpu_relax(); \
316 smp_rmb(); /* ctrl + rmb := acquire */ \
317 } while (0)
318
319 #endif /* __KERNEL__ */
320
321 #endif /* __ASSEMBLY__ */
322
323 #ifdef __KERNEL__
324 /*
325 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
326 * warning for each use, in hopes of speeding the functions removal.
327 * Usage is:
328 * int __deprecated foo(void)
329 */
330 #ifndef __deprecated
331 # define __deprecated /* unimplemented */
332 #endif
333
334 #ifdef MODULE
335 #define __deprecated_for_modules __deprecated
336 #else
337 #define __deprecated_for_modules
338 #endif
339
340 #ifndef __must_check
341 #define __must_check
342 #endif
343
344 #ifndef CONFIG_ENABLE_MUST_CHECK
345 #undef __must_check
346 #define __must_check
347 #endif
348 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
349 #undef __deprecated
350 #undef __deprecated_for_modules
351 #define __deprecated
352 #define __deprecated_for_modules
353 #endif
354
355 /*
356 * Allow us to avoid 'defined but not used' warnings on functions and data,
357 * as well as force them to be emitted to the assembly file.
358 *
359 * As of gcc 3.4, static functions that are not marked with attribute((used))
360 * may be elided from the assembly file. As of gcc 3.4, static data not so
361 * marked will not be elided, but this may change in a future gcc version.
362 *
363 * NOTE: Because distributions shipped with a backported unit-at-a-time
364 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
365 * for gcc >=3.3 instead of 3.4.
366 *
367 * In prior versions of gcc, such functions and data would be emitted, but
368 * would be warned about except with attribute((unused)).
369 *
370 * Mark functions that are referenced only in inline assembly as __used so
371 * the code is emitted even though it appears to be unreferenced.
372 */
373 #ifndef __used
374 # define __used /* unimplemented */
375 #endif
376
377 #ifndef __maybe_unused
378 # define __maybe_unused /* unimplemented */
379 #endif
380
381 #ifndef __always_unused
382 # define __always_unused /* unimplemented */
383 #endif
384
385 #ifndef noinline
386 #define noinline
387 #endif
388
389 /*
390 * Rather then using noinline to prevent stack consumption, use
391 * noinline_for_stack instead. For documentation reasons.
392 */
393 #define noinline_for_stack noinline
394
395 #ifndef __always_inline
396 #define __always_inline inline
397 #endif
398
399 #endif /* __KERNEL__ */
400
401 /*
402 * From the GCC manual:
403 *
404 * Many functions do not examine any values except their arguments,
405 * and have no effects except the return value. Basically this is
406 * just slightly more strict class than the `pure' attribute above,
407 * since function is not allowed to read global memory.
408 *
409 * Note that a function that has pointer arguments and examines the
410 * data pointed to must _not_ be declared `const'. Likewise, a
411 * function that calls a non-`const' function usually must not be
412 * `const'. It does not make sense for a `const' function to return
413 * `void'.
414 */
415 #ifndef __attribute_const__
416 # define __attribute_const__ /* unimplemented */
417 #endif
418
419 /*
420 * Tell gcc if a function is cold. The compiler will assume any path
421 * directly leading to the call is unlikely.
422 */
423
424 #ifndef __cold
425 #define __cold
426 #endif
427
428 /* Simple shorthand for a section definition */
429 #ifndef __section
430 # define __section(S) __attribute__ ((__section__(#S)))
431 #endif
432
433 #ifndef __visible
434 #define __visible
435 #endif
436
437 /*
438 * Assume alignment of return value.
439 */
440 #ifndef __assume_aligned
441 #define __assume_aligned(a, ...)
442 #endif
443
444
445 /* Are two types/vars the same type (ignoring qualifiers)? */
446 #ifndef __same_type
447 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
448 #endif
449
450 /* Is this type a native word size -- useful for atomic operations */
451 #ifndef __native_word
452 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
453 #endif
454
455 /* Compile time object size, -1 for unknown */
456 #ifndef __compiletime_object_size
457 # define __compiletime_object_size(obj) -1
458 #endif
459 #ifndef __compiletime_warning
460 # define __compiletime_warning(message)
461 #endif
462 #ifndef __compiletime_error
463 # define __compiletime_error(message)
464 /*
465 * Sparse complains of variable sized arrays due to the temporary variable in
466 * __compiletime_assert. Unfortunately we can't just expand it out to make
467 * sparse see a constant array size without breaking compiletime_assert on old
468 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
469 */
470 # ifndef __CHECKER__
471 # define __compiletime_error_fallback(condition) \
472 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
473 # endif
474 #endif
475 #ifndef __compiletime_error_fallback
476 # define __compiletime_error_fallback(condition) do { } while (0)
477 #endif
478
479 #ifdef __OPTIMIZE__
480 # define __compiletime_assert(condition, msg, prefix, suffix) \
481 do { \
482 bool __cond = !(condition); \
483 extern void prefix ## suffix(void) __compiletime_error(msg); \
484 if (__cond) \
485 prefix ## suffix(); \
486 __compiletime_error_fallback(__cond); \
487 } while (0)
488 #else
489 # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
490 #endif
491
492 #define _compiletime_assert(condition, msg, prefix, suffix) \
493 __compiletime_assert(condition, msg, prefix, suffix)
494
495 /**
496 * compiletime_assert - break build and emit msg if condition is false
497 * @condition: a compile-time constant condition to check
498 * @msg: a message to emit if condition is false
499 *
500 * In tradition of POSIX assert, this macro will break the build if the
501 * supplied condition is *false*, emitting the supplied error message if the
502 * compiler has support to do so.
503 */
504 #define compiletime_assert(condition, msg) \
505 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
506
507 #define compiletime_assert_atomic_type(t) \
508 compiletime_assert(__native_word(t), \
509 "Need native word sized stores/loads for atomicity.")
510
511 /*
512 * Prevent the compiler from merging or refetching accesses. The compiler
513 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
514 * but only when the compiler is aware of some particular ordering. One way
515 * to make the compiler aware of ordering is to put the two invocations of
516 * ACCESS_ONCE() in different C statements.
517 *
518 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
519 * on a union member will work as long as the size of the member matches the
520 * size of the union and the size is smaller than word size.
521 *
522 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
523 * between process-level code and irq/NMI handlers, all running on the same CPU,
524 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
525 * mutilate accesses that either do not require ordering or that interact
526 * with an explicit memory barrier or atomic instruction that provides the
527 * required ordering.
528 *
529 * If possible use READ_ONCE()/WRITE_ONCE() instead.
530 */
531 #define __ACCESS_ONCE(x) ({ \
532 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
533 (volatile typeof(x) *)&(x); })
534 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
535
536 /**
537 * lockless_dereference() - safely load a pointer for later dereference
538 * @p: The pointer to load
539 *
540 * Similar to rcu_dereference(), but for situations where the pointed-to
541 * object's lifetime is managed by something other than RCU. That
542 * "something other" might be reference counting or simple immortality.
543 */
544 #define lockless_dereference(p) \
545 ({ \
546 typeof(p) _________p1 = READ_ONCE(p); \
547 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
548 (_________p1); \
549 })
550
551 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
552 #ifdef CONFIG_KPROBES
553 # define __kprobes __attribute__((__section__(".kprobes.text")))
554 # define nokprobe_inline __always_inline
555 #else
556 # define __kprobes
557 # define nokprobe_inline inline
558 #endif
559 #endif /* __LINUX_COMPILER_H */
560