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 /* CONFIG_SPARSE_RCU_POINTER */
23 # define __rcu
24 #endif /* CONFIG_SPARSE_RCU_POINTER */
25 # define __private __attribute__((noderef))
26 extern void __chk_user_ptr(const volatile void __user *);
27 extern void __chk_io_ptr(const volatile void __iomem *);
28 # define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
29 #else /* __CHECKER__ */
30 # define __user
31 # define __kernel
32 # define __safe
33 # define __force
34 # define __nocast
35 # define __iomem
36 # define __chk_user_ptr(x) (void)0
37 # define __chk_io_ptr(x) (void)0
38 # define __builtin_warning(x, y...) (1)
39 # define __must_hold(x)
40 # define __acquires(x)
41 # define __releases(x)
42 # define __acquire(x) (void)0
43 # define __release(x) (void)0
44 # define __cond_lock(x,c) (c)
45 # define __percpu
46 # define __rcu
47 # define __private
48 # define ACCESS_PRIVATE(p, member) ((p)->member)
49 #endif /* __CHECKER__ */
50
51 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
52 #define ___PASTE(a,b) a##b
53 #define __PASTE(a,b) ___PASTE(a,b)
54
55 #ifdef __KERNEL__
56
57 #ifdef __GNUC__
58 #include <linux/compiler-gcc.h>
59 #endif
60
61 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
62 #define notrace __attribute__((hotpatch(0,0)))
63 #else
64 #define notrace __attribute__((no_instrument_function))
65 #endif
66
67 /* Intel compiler defines __GNUC__. So we will overwrite implementations
68 * coming from above header files here
69 */
70 #ifdef __INTEL_COMPILER
71 # include <linux/compiler-intel.h>
72 #endif
73
74 /* Clang compiler defines __GNUC__. So we will overwrite implementations
75 * coming from above header files here
76 */
77 #ifdef __clang__
78 #include <linux/compiler-clang.h>
79 #endif
80
81 /*
82 * Generic compiler-dependent macros required for kernel
83 * build go below this comment. Actual compiler/compiler version
84 * specific implementations come from the above header files
85 */
86
87 struct ftrace_branch_data {
88 const char *func;
89 const char *file;
90 unsigned line;
91 union {
92 struct {
93 unsigned long correct;
94 unsigned long incorrect;
95 };
96 struct {
97 unsigned long miss;
98 unsigned long hit;
99 };
100 unsigned long miss_hit[2];
101 };
102 };
103
104 /*
105 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
106 * to disable branch tracing on a per file basis.
107 */
108 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
109 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
110 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
111
112 #define likely_notrace(x) __builtin_expect(!!(x), 1)
113 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
114
115 #define __branch_check__(x, expect) ({ \
116 int ______r; \
117 static struct ftrace_branch_data \
118 __attribute__((__aligned__(4))) \
119 __attribute__((section("_ftrace_annotated_branch"))) \
120 ______f = { \
121 .func = __func__, \
122 .file = __FILE__, \
123 .line = __LINE__, \
124 }; \
125 ______r = likely_notrace(x); \
126 ftrace_likely_update(&______f, ______r, expect); \
127 ______r; \
128 })
129
130 /*
131 * Using __builtin_constant_p(x) to ignore cases where the return
132 * value is always the same. This idea is taken from a similar patch
133 * written by Daniel Walker.
134 */
135 # ifndef likely
136 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
137 # endif
138 # ifndef unlikely
139 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
140 # endif
141
142 #ifdef CONFIG_PROFILE_ALL_BRANCHES
143 /*
144 * "Define 'is'", Bill Clinton
145 * "Define 'if'", Steven Rostedt
146 */
147 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
148 #define __trace_if(cond) \
149 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
150 ({ \
151 int ______r; \
152 static struct ftrace_branch_data \
153 __attribute__((__aligned__(4))) \
154 __attribute__((section("_ftrace_branch"))) \
155 ______f = { \
156 .func = __func__, \
157 .file = __FILE__, \
158 .line = __LINE__, \
159 }; \
160 ______r = !!(cond); \
161 ______f.miss_hit[______r]++; \
162 ______r; \
163 }))
164 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
165
166 #else
167 # define likely(x) __builtin_expect(!!(x), 1)
168 # define unlikely(x) __builtin_expect(!!(x), 0)
169 #endif
170
171 /* Optimization barrier */
172 #ifndef barrier
173 # define barrier() __memory_barrier()
174 #endif
175
176 #ifndef barrier_data
177 # define barrier_data(ptr) barrier()
178 #endif
179
180 /* Unreachable code */
181 #ifndef unreachable
182 # define unreachable() do { } while (1)
183 #endif
184
185 /*
186 * KENTRY - kernel entry point
187 * This can be used to annotate symbols (functions or data) that are used
188 * without their linker symbol being referenced explicitly. For example,
189 * interrupt vector handlers, or functions in the kernel image that are found
190 * programatically.
191 *
192 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
193 * are handled in their own way (with KEEP() in linker scripts).
194 *
195 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
196 * linker script. For example an architecture could KEEP() its entire
197 * boot/exception vector code rather than annotate each function and data.
198 */
199 #ifndef KENTRY
200 # define KENTRY(sym) \
201 extern typeof(sym) sym; \
202 static const unsigned long __kentry_##sym \
203 __used \
204 __attribute__((section("___kentry" "+" #sym ), used)) \
205 = (unsigned long)&sym;
206 #endif
207
208 #ifndef RELOC_HIDE
209 # define RELOC_HIDE(ptr, off) \
210 ({ unsigned long __ptr; \
211 __ptr = (unsigned long) (ptr); \
212 (typeof(ptr)) (__ptr + (off)); })
213 #endif
214
215 #ifndef OPTIMIZER_HIDE_VAR
216 #define OPTIMIZER_HIDE_VAR(var) barrier()
217 #endif
218
219 /* Not-quite-unique ID. */
220 #ifndef __UNIQUE_ID
221 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
222 #endif
223
224 #include <uapi/linux/types.h>
225
226 #define __READ_ONCE_SIZE \
227 ({ \
228 switch (size) { \
229 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
230 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
231 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
232 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
233 default: \
234 barrier(); \
235 __builtin_memcpy((void *)res, (const void *)p, size); \
236 barrier(); \
237 } \
238 })
239
240 static __always_inline
__read_once_size(const volatile void * p,void * res,int size)241 void __read_once_size(const volatile void *p, void *res, int size)
242 {
243 __READ_ONCE_SIZE;
244 }
245
246 #ifdef CONFIG_KASAN
247 /*
248 * This function is not 'inline' because __no_sanitize_address confilcts
249 * with inlining. Attempt to inline it may cause a build failure.
250 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
251 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
252 */
253 static __no_sanitize_address __maybe_unused
__read_once_size_nocheck(const volatile void * p,void * res,int size)254 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
255 {
256 __READ_ONCE_SIZE;
257 }
258 #else
259 static __always_inline
__read_once_size_nocheck(const volatile void * p,void * res,int size)260 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
261 {
262 __READ_ONCE_SIZE;
263 }
264 #endif
265
__write_once_size(volatile void * p,void * res,int size)266 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
267 {
268 switch (size) {
269 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
270 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
271 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
272 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
273 default:
274 barrier();
275 __builtin_memcpy((void *)p, (const void *)res, size);
276 barrier();
277 }
278 }
279
280 /*
281 * Prevent the compiler from merging or refetching reads or writes. The
282 * compiler is also forbidden from reordering successive instances of
283 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
284 * compiler is aware of some particular ordering. One way to make the
285 * compiler aware of ordering is to put the two invocations of READ_ONCE,
286 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
287 *
288 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
289 * data types like structs or unions. If the size of the accessed data
290 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
291 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at
292 * least two memcpy()s: one for the __builtin_memcpy() and then one for
293 * the macro doing the copy of variable - '__u' allocated on the stack.
294 *
295 * Their two major use cases are: (1) Mediating communication between
296 * process-level code and irq/NMI handlers, all running on the same CPU,
297 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
298 * mutilate accesses that either do not require ordering or that interact
299 * with an explicit memory barrier or atomic instruction that provides the
300 * required ordering.
301 */
302
303 #define __READ_ONCE(x, check) \
304 ({ \
305 union { typeof(x) __val; char __c[1]; } __u; \
306 if (check) \
307 __read_once_size(&(x), __u.__c, sizeof(x)); \
308 else \
309 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
310 __u.__val; \
311 })
312 #define READ_ONCE(x) __READ_ONCE(x, 1)
313
314 /*
315 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
316 * to hide memory access from KASAN.
317 */
318 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
319
320 #define WRITE_ONCE(x, val) \
321 ({ \
322 union { typeof(x) __val; char __c[1]; } __u = \
323 { .__val = (__force typeof(x)) (val) }; \
324 __write_once_size(&(x), __u.__c, sizeof(x)); \
325 __u.__val; \
326 })
327
328 #endif /* __KERNEL__ */
329
330 #endif /* __ASSEMBLY__ */
331
332 #ifdef __KERNEL__
333 /*
334 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
335 * warning for each use, in hopes of speeding the functions removal.
336 * Usage is:
337 * int __deprecated foo(void)
338 */
339 #ifndef __deprecated
340 # define __deprecated /* unimplemented */
341 #endif
342
343 #ifdef MODULE
344 #define __deprecated_for_modules __deprecated
345 #else
346 #define __deprecated_for_modules
347 #endif
348
349 #ifndef __must_check
350 #define __must_check
351 #endif
352
353 #ifndef CONFIG_ENABLE_MUST_CHECK
354 #undef __must_check
355 #define __must_check
356 #endif
357 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
358 #undef __deprecated
359 #undef __deprecated_for_modules
360 #define __deprecated
361 #define __deprecated_for_modules
362 #endif
363
364 #ifndef __malloc
365 #define __malloc
366 #endif
367
368 /*
369 * Allow us to avoid 'defined but not used' warnings on functions and data,
370 * as well as force them to be emitted to the assembly file.
371 *
372 * As of gcc 3.4, static functions that are not marked with attribute((used))
373 * may be elided from the assembly file. As of gcc 3.4, static data not so
374 * marked will not be elided, but this may change in a future gcc version.
375 *
376 * NOTE: Because distributions shipped with a backported unit-at-a-time
377 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
378 * for gcc >=3.3 instead of 3.4.
379 *
380 * In prior versions of gcc, such functions and data would be emitted, but
381 * would be warned about except with attribute((unused)).
382 *
383 * Mark functions that are referenced only in inline assembly as __used so
384 * the code is emitted even though it appears to be unreferenced.
385 */
386 #ifndef __used
387 # define __used /* unimplemented */
388 #endif
389
390 #ifndef __maybe_unused
391 # define __maybe_unused /* unimplemented */
392 #endif
393
394 #ifndef __always_unused
395 # define __always_unused /* unimplemented */
396 #endif
397
398 #ifndef noinline
399 #define noinline
400 #endif
401
402 /*
403 * Rather then using noinline to prevent stack consumption, use
404 * noinline_for_stack instead. For documentation reasons.
405 */
406 #define noinline_for_stack noinline
407
408 #ifndef __always_inline
409 #define __always_inline inline
410 #endif
411
412 #endif /* __KERNEL__ */
413
414 /*
415 * From the GCC manual:
416 *
417 * Many functions do not examine any values except their arguments,
418 * and have no effects except the return value. Basically this is
419 * just slightly more strict class than the `pure' attribute above,
420 * since function is not allowed to read global memory.
421 *
422 * Note that a function that has pointer arguments and examines the
423 * data pointed to must _not_ be declared `const'. Likewise, a
424 * function that calls a non-`const' function usually must not be
425 * `const'. It does not make sense for a `const' function to return
426 * `void'.
427 */
428 #ifndef __attribute_const__
429 # define __attribute_const__ /* unimplemented */
430 #endif
431
432 #ifndef __latent_entropy
433 # define __latent_entropy
434 #endif
435
436 /*
437 * Tell gcc if a function is cold. The compiler will assume any path
438 * directly leading to the call is unlikely.
439 */
440
441 #ifndef __cold
442 #define __cold
443 #endif
444
445 /* Simple shorthand for a section definition */
446 #ifndef __section
447 # define __section(S) __attribute__ ((__section__(#S)))
448 #endif
449
450 #ifndef __visible
451 #define __visible
452 #endif
453
454 #ifndef __norecordmcount
455 #define __norecordmcount
456 #endif
457
458 #ifndef __nocfi
459 #define __nocfi
460 #endif
461
462 /*
463 * Assume alignment of return value.
464 */
465 #ifndef __assume_aligned
466 #define __assume_aligned(a, ...)
467 #endif
468
469
470 /* Are two types/vars the same type (ignoring qualifiers)? */
471 #ifndef __same_type
472 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
473 #endif
474
475 /* Is this type a native word size -- useful for atomic operations */
476 #ifndef __native_word
477 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
478 #endif
479
480 #ifndef __optimize
481 # define __optimize(level)
482 #endif
483
484 /* Compile time object size, -1 for unknown */
485 #ifndef __compiletime_object_size
486 # define __compiletime_object_size(obj) -1
487 #endif
488 #ifndef __compiletime_warning
489 # define __compiletime_warning(message)
490 #endif
491 #ifndef __compiletime_error
492 # define __compiletime_error(message)
493 /*
494 * Sparse complains of variable sized arrays due to the temporary variable in
495 * __compiletime_assert. Unfortunately we can't just expand it out to make
496 * sparse see a constant array size without breaking compiletime_assert on old
497 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
498 */
499 # ifndef __CHECKER__
500 # define __compiletime_error_fallback(condition) \
501 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
502 # endif
503 #endif
504 #ifndef __compiletime_error_fallback
505 # define __compiletime_error_fallback(condition) do { } while (0)
506 #endif
507
508 #define __compiletime_assert(condition, msg, prefix, suffix) \
509 do { \
510 bool __cond = !(condition); \
511 extern void prefix ## suffix(void) __compiletime_error(msg); \
512 if (__cond) \
513 prefix ## suffix(); \
514 __compiletime_error_fallback(__cond); \
515 } while (0)
516
517 #define _compiletime_assert(condition, msg, prefix, suffix) \
518 __compiletime_assert(condition, msg, prefix, suffix)
519
520 /**
521 * compiletime_assert - break build and emit msg if condition is false
522 * @condition: a compile-time constant condition to check
523 * @msg: a message to emit if condition is false
524 *
525 * In tradition of POSIX assert, this macro will break the build if the
526 * supplied condition is *false*, emitting the supplied error message if the
527 * compiler has support to do so.
528 */
529 #define compiletime_assert(condition, msg) \
530 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
531
532 #define compiletime_assert_atomic_type(t) \
533 compiletime_assert(__native_word(t), \
534 "Need native word sized stores/loads for atomicity.")
535
536 /*
537 * Prevent the compiler from merging or refetching accesses. The compiler
538 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
539 * but only when the compiler is aware of some particular ordering. One way
540 * to make the compiler aware of ordering is to put the two invocations of
541 * ACCESS_ONCE() in different C statements.
542 *
543 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
544 * on a union member will work as long as the size of the member matches the
545 * size of the union and the size is smaller than word size.
546 *
547 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
548 * between process-level code and irq/NMI handlers, all running on the same CPU,
549 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
550 * mutilate accesses that either do not require ordering or that interact
551 * with an explicit memory barrier or atomic instruction that provides the
552 * required ordering.
553 *
554 * If possible use READ_ONCE()/WRITE_ONCE() instead.
555 */
556 #define __ACCESS_ONCE(x) ({ \
557 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
558 (volatile typeof(x) *)&(x); })
559 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
560
561 /**
562 * lockless_dereference() - safely load a pointer for later dereference
563 * @p: The pointer to load
564 *
565 * Similar to rcu_dereference(), but for situations where the pointed-to
566 * object's lifetime is managed by something other than RCU. That
567 * "something other" might be reference counting or simple immortality.
568 *
569 * The seemingly unused variable ___typecheck_p validates that @p is
570 * indeed a pointer type by using a pointer to typeof(*p) as the type.
571 * Taking a pointer to typeof(*p) again is needed in case p is void *.
572 */
573 #define lockless_dereference(p) \
574 ({ \
575 typeof(p) _________p1 = READ_ONCE(p); \
576 typeof(*(p)) *___typecheck_p __maybe_unused; \
577 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
578 (_________p1); \
579 })
580
581 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
582 #ifdef CONFIG_KPROBES
583 # define __kprobes __attribute__((__section__(".kprobes.text")))
584 # define nokprobe_inline __always_inline
585 #else
586 # define __kprobes
587 # define nokprobe_inline inline
588 #endif
589 #endif /* __LINUX_COMPILER_H */
590