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 /*
56 * Minimal backport of compiler_attributes.h to add support for __copy
57 * to v4.9.y so that we can use it in init/exit_module to avoid
58 * -Werror=missing-attributes errors on GCC 9.
59 */
60 #ifndef __has_attribute
61 # define __has_attribute(x) __GCC4_has_attribute_##x
62 # define __GCC4_has_attribute___copy__ 0
63 #endif
64
65 #if __has_attribute(__copy__)
66 # define __copy(symbol) __attribute__((__copy__(symbol)))
67 #else
68 # define __copy(symbol)
69 #endif
70
71 #ifdef __GNUC__
72 #include <linux/compiler-gcc.h>
73 #endif
74
75 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
76 #define notrace __attribute__((hotpatch(0,0)))
77 #else
78 #define notrace __attribute__((no_instrument_function))
79 #endif
80
81 /* Intel compiler defines __GNUC__. So we will overwrite implementations
82 * coming from above header files here
83 */
84 #ifdef __INTEL_COMPILER
85 # include <linux/compiler-intel.h>
86 #endif
87
88 /* Clang compiler defines __GNUC__. So we will overwrite implementations
89 * coming from above header files here
90 */
91 #ifdef __clang__
92 #include <linux/compiler-clang.h>
93 #endif
94
95 /*
96 * Generic compiler-dependent macros required for kernel
97 * build go below this comment. Actual compiler/compiler version
98 * specific implementations come from the above header files
99 */
100
101 struct ftrace_branch_data {
102 const char *func;
103 const char *file;
104 unsigned line;
105 union {
106 struct {
107 unsigned long correct;
108 unsigned long incorrect;
109 };
110 struct {
111 unsigned long miss;
112 unsigned long hit;
113 };
114 unsigned long miss_hit[2];
115 };
116 };
117
118 /*
119 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
120 * to disable branch tracing on a per file basis.
121 */
122 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
123 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
124 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
125
126 #define likely_notrace(x) __builtin_expect(!!(x), 1)
127 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
128
129 #define __branch_check__(x, expect) ({ \
130 long ______r; \
131 static struct ftrace_branch_data \
132 __attribute__((__aligned__(4))) \
133 __attribute__((section("_ftrace_annotated_branch"))) \
134 ______f = { \
135 .func = __func__, \
136 .file = __FILE__, \
137 .line = __LINE__, \
138 }; \
139 ______r = likely_notrace(x); \
140 ftrace_likely_update(&______f, ______r, expect); \
141 ______r; \
142 })
143
144 /*
145 * Using __builtin_constant_p(x) to ignore cases where the return
146 * value is always the same. This idea is taken from a similar patch
147 * written by Daniel Walker.
148 */
149 # ifndef likely
150 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
151 # endif
152 # ifndef unlikely
153 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
154 # endif
155
156 #ifdef CONFIG_PROFILE_ALL_BRANCHES
157 /*
158 * "Define 'is'", Bill Clinton
159 * "Define 'if'", Steven Rostedt
160 */
161 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
162 #define __trace_if(cond) \
163 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
164 ({ \
165 int ______r; \
166 static struct ftrace_branch_data \
167 __attribute__((__aligned__(4))) \
168 __attribute__((section("_ftrace_branch"))) \
169 ______f = { \
170 .func = __func__, \
171 .file = __FILE__, \
172 .line = __LINE__, \
173 }; \
174 ______r = !!(cond); \
175 ______f.miss_hit[______r]++; \
176 ______r; \
177 }))
178 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
179
180 #else
181 # define likely(x) __builtin_expect(!!(x), 1)
182 # define unlikely(x) __builtin_expect(!!(x), 0)
183 #endif
184
185 /* Optimization barrier */
186 #ifndef barrier
187 # define barrier() __memory_barrier()
188 #endif
189
190 #ifndef barrier_data
191 # define barrier_data(ptr) barrier()
192 #endif
193
194 /* workaround for GCC PR82365 if needed */
195 #ifndef barrier_before_unreachable
196 # define barrier_before_unreachable() do { } while (0)
197 #endif
198
199 /* Unreachable code */
200 #ifndef unreachable
201 # define unreachable() do { } while (1)
202 #endif
203
204 #ifndef RELOC_HIDE
205 # define RELOC_HIDE(ptr, off) \
206 ({ unsigned long __ptr; \
207 __ptr = (unsigned long) (ptr); \
208 (typeof(ptr)) (__ptr + (off)); })
209 #endif
210
211 #define absolute_pointer(val) RELOC_HIDE((void *)(val), 0)
212
213 #ifndef OPTIMIZER_HIDE_VAR
214 #define OPTIMIZER_HIDE_VAR(var) barrier()
215 #endif
216
217 /* Not-quite-unique ID. */
218 #ifndef __UNIQUE_ID
219 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
220 #endif
221
222 #include <uapi/linux/types.h>
223
224 #define __READ_ONCE_SIZE \
225 ({ \
226 switch (size) { \
227 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
228 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
229 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
230 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
231 default: \
232 barrier(); \
233 __builtin_memcpy((void *)res, (const void *)p, size); \
234 barrier(); \
235 } \
236 })
237
238 static __always_inline
__read_once_size(const volatile void * p,void * res,int size)239 void __read_once_size(const volatile void *p, void *res, int size)
240 {
241 __READ_ONCE_SIZE;
242 }
243
244 #ifdef CONFIG_KASAN
245 /*
246 * We can't declare function 'inline' because __no_sanitize_address confilcts
247 * with inlining. Attempt to inline it may cause a build failure.
248 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
249 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
250 */
251 # define __no_kasan_or_inline __no_sanitize_address __maybe_unused
252 #else
253 # define __no_kasan_or_inline __always_inline
254 #endif
255
256 static __no_kasan_or_inline
__read_once_size_nocheck(const volatile void * p,void * res,int size)257 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
258 {
259 __READ_ONCE_SIZE;
260 }
261
__write_once_size(volatile void * p,void * res,int size)262 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
263 {
264 switch (size) {
265 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
266 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
267 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
268 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
269 default:
270 barrier();
271 __builtin_memcpy((void *)p, (const void *)res, size);
272 barrier();
273 }
274 }
275
276 /*
277 * Prevent the compiler from merging or refetching reads or writes. The
278 * compiler is also forbidden from reordering successive instances of
279 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
280 * compiler is aware of some particular ordering. One way to make the
281 * compiler aware of ordering is to put the two invocations of READ_ONCE,
282 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
283 *
284 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
285 * data types like structs or unions. If the size of the accessed data
286 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
287 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a
288 * compile-time warning.
289 *
290 * Their two major use cases are: (1) Mediating communication between
291 * process-level code and irq/NMI handlers, all running on the same CPU,
292 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
293 * mutilate accesses that either do not require ordering or that interact
294 * with an explicit memory barrier or atomic instruction that provides the
295 * required ordering.
296 */
297 #include <linux/kasan-checks.h>
298
299 #define __READ_ONCE(x, check) \
300 ({ \
301 union { typeof(x) __val; char __c[1]; } __u; \
302 if (check) \
303 __read_once_size(&(x), __u.__c, sizeof(x)); \
304 else \
305 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
306 __u.__val; \
307 })
308 #define READ_ONCE(x) __READ_ONCE(x, 1)
309
310 /*
311 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
312 * to hide memory access from KASAN.
313 */
314 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
315
316 static __no_kasan_or_inline
read_word_at_a_time(const void * addr)317 unsigned long read_word_at_a_time(const void *addr)
318 {
319 kasan_check_read(addr, 1);
320 return *(unsigned long *)addr;
321 }
322
323 #define WRITE_ONCE(x, val) \
324 ({ \
325 union { typeof(x) __val; char __c[1]; } __u = \
326 { .__val = (__force typeof(x)) (val) }; \
327 __write_once_size(&(x), __u.__c, sizeof(x)); \
328 __u.__val; \
329 })
330
331 #endif /* __KERNEL__ */
332
333 #endif /* __ASSEMBLY__ */
334
335 #ifdef __KERNEL__
336 /*
337 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
338 * warning for each use, in hopes of speeding the functions removal.
339 * Usage is:
340 * int __deprecated foo(void)
341 */
342 #ifndef __deprecated
343 # define __deprecated /* unimplemented */
344 #endif
345
346 #ifdef MODULE
347 #define __deprecated_for_modules __deprecated
348 #else
349 #define __deprecated_for_modules
350 #endif
351
352 #ifndef __must_check
353 #define __must_check
354 #endif
355
356 #ifndef CONFIG_ENABLE_MUST_CHECK
357 #undef __must_check
358 #define __must_check
359 #endif
360 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
361 #undef __deprecated
362 #undef __deprecated_for_modules
363 #define __deprecated
364 #define __deprecated_for_modules
365 #endif
366
367 /*
368 * Allow us to avoid 'defined but not used' warnings on functions and data,
369 * as well as force them to be emitted to the assembly file.
370 *
371 * As of gcc 3.4, static functions that are not marked with attribute((used))
372 * may be elided from the assembly file. As of gcc 3.4, static data not so
373 * marked will not be elided, but this may change in a future gcc version.
374 *
375 * NOTE: Because distributions shipped with a backported unit-at-a-time
376 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
377 * for gcc >=3.3 instead of 3.4.
378 *
379 * In prior versions of gcc, such functions and data would be emitted, but
380 * would be warned about except with attribute((unused)).
381 *
382 * Mark functions that are referenced only in inline assembly as __used so
383 * the code is emitted even though it appears to be unreferenced.
384 */
385 #ifndef __used
386 # define __used /* unimplemented */
387 #endif
388
389 #ifndef __maybe_unused
390 # define __maybe_unused /* unimplemented */
391 #endif
392
393 #ifndef __always_unused
394 # define __always_unused /* unimplemented */
395 #endif
396
397 #ifndef noinline
398 #define noinline
399 #endif
400
401 /*
402 * Rather then using noinline to prevent stack consumption, use
403 * noinline_for_stack instead. For documentation reasons.
404 */
405 #define noinline_for_stack noinline
406
407 #ifndef __always_inline
408 #define __always_inline inline
409 #endif
410
411 #endif /* __KERNEL__ */
412
413 /*
414 * From the GCC manual:
415 *
416 * Many functions do not examine any values except their arguments,
417 * and have no effects except the return value. Basically this is
418 * just slightly more strict class than the `pure' attribute above,
419 * since function is not allowed to read global memory.
420 *
421 * Note that a function that has pointer arguments and examines the
422 * data pointed to must _not_ be declared `const'. Likewise, a
423 * function that calls a non-`const' function usually must not be
424 * `const'. It does not make sense for a `const' function to return
425 * `void'.
426 */
427 #ifndef __attribute_const__
428 # define __attribute_const__ /* unimplemented */
429 #endif
430
431 /*
432 * Tell gcc if a function is cold. The compiler will assume any path
433 * directly leading to the call is unlikely.
434 */
435
436 #ifndef __cold
437 #define __cold
438 #endif
439
440 /* Simple shorthand for a section definition */
441 #ifndef __section
442 # define __section(S) __attribute__ ((__section__(#S)))
443 #endif
444
445 #ifndef __visible
446 #define __visible
447 #endif
448
449 /*
450 * Assume alignment of return value.
451 */
452 #ifndef __assume_aligned
453 #define __assume_aligned(a, ...)
454 #endif
455
456
457 /* Are two types/vars the same type (ignoring qualifiers)? */
458 #ifndef __same_type
459 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
460 #endif
461
462 /* Is this type a native word size -- useful for atomic operations */
463 #ifndef __native_word
464 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
465 #endif
466
467 /* Compile time object size, -1 for unknown */
468 #ifndef __compiletime_object_size
469 # define __compiletime_object_size(obj) -1
470 #endif
471 #ifndef __compiletime_warning
472 # define __compiletime_warning(message)
473 #endif
474 #ifndef __compiletime_error
475 # define __compiletime_error(message)
476 /*
477 * Sparse complains of variable sized arrays due to the temporary variable in
478 * __compiletime_assert. Unfortunately we can't just expand it out to make
479 * sparse see a constant array size without breaking compiletime_assert on old
480 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
481 */
482 # ifndef __CHECKER__
483 # define __compiletime_error_fallback(condition) \
484 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
485 # endif
486 #endif
487 #ifndef __compiletime_error_fallback
488 # define __compiletime_error_fallback(condition) do { } while (0)
489 #endif
490
491 #define __compiletime_assert(condition, msg, prefix, suffix) \
492 do { \
493 bool __cond = !(condition); \
494 extern void prefix ## suffix(void) __compiletime_error(msg); \
495 if (__cond) \
496 prefix ## suffix(); \
497 __compiletime_error_fallback(__cond); \
498 } while (0)
499
500 #define _compiletime_assert(condition, msg, prefix, suffix) \
501 __compiletime_assert(condition, msg, prefix, suffix)
502
503 /**
504 * compiletime_assert - break build and emit msg if condition is false
505 * @condition: a compile-time constant condition to check
506 * @msg: a message to emit if condition is false
507 *
508 * In tradition of POSIX assert, this macro will break the build if the
509 * supplied condition is *false*, emitting the supplied error message if the
510 * compiler has support to do so.
511 */
512 #define compiletime_assert(condition, msg) \
513 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
514
515 #define compiletime_assert_atomic_type(t) \
516 compiletime_assert(__native_word(t), \
517 "Need native word sized stores/loads for atomicity.")
518
519 /*
520 * Prevent the compiler from merging or refetching accesses. The compiler
521 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
522 * but only when the compiler is aware of some particular ordering. One way
523 * to make the compiler aware of ordering is to put the two invocations of
524 * ACCESS_ONCE() in different C statements.
525 *
526 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
527 * on a union member will work as long as the size of the member matches the
528 * size of the union and the size is smaller than word size.
529 *
530 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
531 * between process-level code and irq/NMI handlers, all running on the same CPU,
532 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
533 * mutilate accesses that either do not require ordering or that interact
534 * with an explicit memory barrier or atomic instruction that provides the
535 * required ordering.
536 *
537 * If possible use READ_ONCE()/WRITE_ONCE() instead.
538 */
539 #define __ACCESS_ONCE(x) ({ \
540 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
541 (volatile typeof(x) *)&(x); })
542 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
543
544 /**
545 * lockless_dereference() - safely load a pointer for later dereference
546 * @p: The pointer to load
547 *
548 * Similar to rcu_dereference(), but for situations where the pointed-to
549 * object's lifetime is managed by something other than RCU. That
550 * "something other" might be reference counting or simple immortality.
551 */
552 #define lockless_dereference(p) \
553 ({ \
554 typeof(p) _________p1 = READ_ONCE(p); \
555 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
556 (_________p1); \
557 })
558
559 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
560 #ifdef CONFIG_KPROBES
561 # define __kprobes __attribute__((__section__(".kprobes.text")))
562 # define nokprobe_inline __always_inline
563 #else
564 # define __kprobes
565 # define nokprobe_inline inline
566 #endif
567
568 /*
569 * This is needed in functions which generate the stack canary, see
570 * arch/x86/kernel/smpboot.c::start_secondary() for an example.
571 */
572 #define prevent_tail_call_optimization() mb()
573
574 #endif /* __LINUX_COMPILER_H */
575