1 #ifndef __LINUX_COMPILER_H
2 #define __LINUX_COMPILER_H
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)))
26 extern void __chk_user_ptr(const volatile void __user *);
27 extern void __chk_io_ptr(const volatile void __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)
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)
56 #include <linux/compiler-gcc.h>
59 #ifdef CC_USING_HOTPATCH
60 #define notrace __attribute__((hotpatch(0,0)))
62 #define notrace __attribute__((no_instrument_function))
65 /* Intel compiler defines __GNUC__. So we will overwrite implementations
66 * coming from above header files here
68 #ifdef __INTEL_COMPILER
69 # include <linux/compiler-intel.h>
72 /* Clang compiler defines __GNUC__. So we will overwrite implementations
73 * coming from above header files here
76 #include <linux/compiler-clang.h>
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
85 struct ftrace_branch_data {
91 unsigned long correct;
92 unsigned long incorrect;
98 unsigned long miss_hit[2];
103 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
104 * to disable branch tracing on a per file basis.
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);
110 #define likely_notrace(x) __builtin_expect(!!(x), 1)
111 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
113 #define __branch_check__(x, expect) ({ \
115 static struct ftrace_branch_data \
116 __attribute__((__aligned__(4))) \
117 __attribute__((section("_ftrace_annotated_branch"))) \
123 ______r = likely_notrace(x); \
124 ftrace_likely_update(&______f, ______r, expect); \
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.
134 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
137 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
140 #ifdef CONFIG_PROFILE_ALL_BRANCHES
142 * "Define 'is'", Bill Clinton
143 * "Define 'if'", Steven Rostedt
145 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
146 #define __trace_if(cond) \
147 if (__builtin_constant_p((cond)) ? !!(cond) : \
150 static struct ftrace_branch_data \
151 __attribute__((__aligned__(4))) \
152 __attribute__((section("_ftrace_branch"))) \
158 ______r = !!(cond); \
159 ______f.miss_hit[______r]++; \
162 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
165 # define likely(x) __builtin_expect(!!(x), 1)
166 # define unlikely(x) __builtin_expect(!!(x), 0)
169 /* Optimization barrier */
171 # define barrier() __memory_barrier()
175 # define barrier_data(ptr) barrier()
178 /* Unreachable code */
180 # define unreachable() do { } while (1)
184 # define RELOC_HIDE(ptr, off) \
185 ({ unsigned long __ptr; \
186 __ptr = (unsigned long) (ptr); \
187 (typeof(ptr)) (__ptr + (off)); })
190 #ifndef OPTIMIZER_HIDE_VAR
191 #define OPTIMIZER_HIDE_VAR(var) barrier()
194 /* Not-quite-unique ID. */
196 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
199 #include <uapi/linux/types.h>
201 #define __READ_ONCE_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; \
210 __builtin_memcpy((void *)res, (const void *)p, size); \
215 static __always_inline
216 void __read_once_size(const volatile void *p, void *res, int size)
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.
228 static __no_sanitize_address __maybe_unused
229 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
234 static __always_inline
235 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
241 static __always_inline void __write_once_size(volatile void *p, void *res, int 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;
250 __builtin_memcpy((void *)p, (const void *)res, size);
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.
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.
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
277 #define __READ_ONCE(x, check) \
279 union { typeof(x) __val; char __c[1]; } __u; \
281 __read_once_size(&(x), __u.__c, sizeof(x)); \
283 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
286 #define READ_ONCE(x) __READ_ONCE(x, 1)
289 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
290 * to hide memory access from KASAN.
292 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
294 #define WRITE_ONCE(x, val) \
296 union { typeof(x) __val; char __c[1]; } __u = \
297 { .__val = (__force typeof(x)) (val) }; \
298 __write_once_size(&(x), __u.__c, sizeof(x)); \
303 * READ_ONCE_CTRL - Read a value heading a control dependency
304 * @x: The value to be read, heading the control dependency
306 * Control dependencies are tricky. See Documentation/memory-barriers.txt
307 * for important information on how to use them. Note that in many cases,
308 * use of smp_load_acquire() will be much simpler. Control dependencies
309 * should be avoided except on the hottest of hotpaths.
311 #define READ_ONCE_CTRL(x) \
313 typeof(x) __val = READ_ONCE(x); \
314 smp_read_barrier_depends(); /* Enforce control dependency. */ \
318 #endif /* __KERNEL__ */
320 #endif /* __ASSEMBLY__ */
324 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
325 * warning for each use, in hopes of speeding the functions removal.
327 * int __deprecated foo(void)
330 # define __deprecated /* unimplemented */
334 #define __deprecated_for_modules __deprecated
336 #define __deprecated_for_modules
343 #ifndef CONFIG_ENABLE_MUST_CHECK
347 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
349 #undef __deprecated_for_modules
351 #define __deprecated_for_modules
355 * Allow us to avoid 'defined but not used' warnings on functions and data,
356 * as well as force them to be emitted to the assembly file.
358 * As of gcc 3.4, static functions that are not marked with attribute((used))
359 * may be elided from the assembly file. As of gcc 3.4, static data not so
360 * marked will not be elided, but this may change in a future gcc version.
362 * NOTE: Because distributions shipped with a backported unit-at-a-time
363 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
364 * for gcc >=3.3 instead of 3.4.
366 * In prior versions of gcc, such functions and data would be emitted, but
367 * would be warned about except with attribute((unused)).
369 * Mark functions that are referenced only in inline assembly as __used so
370 * the code is emitted even though it appears to be unreferenced.
373 # define __used /* unimplemented */
376 #ifndef __maybe_unused
377 # define __maybe_unused /* unimplemented */
380 #ifndef __always_unused
381 # define __always_unused /* unimplemented */
389 * Rather then using noinline to prevent stack consumption, use
390 * noinline_for_stack instead. For documentation reasons.
392 #define noinline_for_stack noinline
394 #ifndef __always_inline
395 #define __always_inline inline
398 #endif /* __KERNEL__ */
401 * From the GCC manual:
403 * Many functions do not examine any values except their arguments,
404 * and have no effects except the return value. Basically this is
405 * just slightly more strict class than the `pure' attribute above,
406 * since function is not allowed to read global memory.
408 * Note that a function that has pointer arguments and examines the
409 * data pointed to must _not_ be declared `const'. Likewise, a
410 * function that calls a non-`const' function usually must not be
411 * `const'. It does not make sense for a `const' function to return
414 #ifndef __attribute_const__
415 # define __attribute_const__ /* unimplemented */
419 * Tell gcc if a function is cold. The compiler will assume any path
420 * directly leading to the call is unlikely.
427 /* Simple shorthand for a section definition */
429 # define __section(S) __attribute__ ((__section__(#S)))
436 /* Are two types/vars the same type (ignoring qualifiers)? */
438 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
441 /* Is this type a native word size -- useful for atomic operations */
442 #ifndef __native_word
443 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
446 /* Compile time object size, -1 for unknown */
447 #ifndef __compiletime_object_size
448 # define __compiletime_object_size(obj) -1
450 #ifndef __compiletime_warning
451 # define __compiletime_warning(message)
453 #ifndef __compiletime_error
454 # define __compiletime_error(message)
456 * Sparse complains of variable sized arrays due to the temporary variable in
457 * __compiletime_assert. Unfortunately we can't just expand it out to make
458 * sparse see a constant array size without breaking compiletime_assert on old
459 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
462 # define __compiletime_error_fallback(condition) \
463 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
466 #ifndef __compiletime_error_fallback
467 # define __compiletime_error_fallback(condition) do { } while (0)
470 #define __compiletime_assert(condition, msg, prefix, suffix) \
472 bool __cond = !(condition); \
473 extern void prefix ## suffix(void) __compiletime_error(msg); \
475 prefix ## suffix(); \
476 __compiletime_error_fallback(__cond); \
479 #define _compiletime_assert(condition, msg, prefix, suffix) \
480 __compiletime_assert(condition, msg, prefix, suffix)
483 * compiletime_assert - break build and emit msg if condition is false
484 * @condition: a compile-time constant condition to check
485 * @msg: a message to emit if condition is false
487 * In tradition of POSIX assert, this macro will break the build if the
488 * supplied condition is *false*, emitting the supplied error message if the
489 * compiler has support to do so.
491 #define compiletime_assert(condition, msg) \
492 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
494 #define compiletime_assert_atomic_type(t) \
495 compiletime_assert(__native_word(t), \
496 "Need native word sized stores/loads for atomicity.")
499 * Prevent the compiler from merging or refetching accesses. The compiler
500 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
501 * but only when the compiler is aware of some particular ordering. One way
502 * to make the compiler aware of ordering is to put the two invocations of
503 * ACCESS_ONCE() in different C statements.
505 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
506 * on a union member will work as long as the size of the member matches the
507 * size of the union and the size is smaller than word size.
509 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
510 * between process-level code and irq/NMI handlers, all running on the same CPU,
511 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
512 * mutilate accesses that either do not require ordering or that interact
513 * with an explicit memory barrier or atomic instruction that provides the
516 * If possible use READ_ONCE()/WRITE_ONCE() instead.
518 #define __ACCESS_ONCE(x) ({ \
519 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
520 (volatile typeof(x) *)&(x); })
521 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
524 * lockless_dereference() - safely load a pointer for later dereference
525 * @p: The pointer to load
527 * Similar to rcu_dereference(), but for situations where the pointed-to
528 * object's lifetime is managed by something other than RCU. That
529 * "something other" might be reference counting or simple immortality.
531 #define lockless_dereference(p) \
533 typeof(p) _________p1 = READ_ONCE(p); \
534 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
538 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
539 #ifdef CONFIG_KPROBES
540 # define __kprobes __attribute__((__section__(".kprobes.text")))
541 # define nokprobe_inline __always_inline
544 # define nokprobe_inline inline
546 #endif /* __LINUX_COMPILER_H */