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 #ifdef CONFIG_SPARSE_RCU_POINTER
21 # define __rcu __attribute__((noderef, address_space(4)))
25 extern void __chk_user_ptr(const volatile void __user *);
26 extern void __chk_io_ptr(const volatile void __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)
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)
54 #include <linux/compiler-gcc.h>
57 #ifdef CC_USING_HOTPATCH
58 #define notrace __attribute__((hotpatch(0,0)))
60 #define notrace __attribute__((no_instrument_function))
63 /* Intel compiler defines __GNUC__. So we will overwrite implementations
64 * coming from above header files here
66 #ifdef __INTEL_COMPILER
67 # include <linux/compiler-intel.h>
70 /* Clang compiler defines __GNUC__. So we will overwrite implementations
71 * coming from above header files here
74 #include <linux/compiler-clang.h>
78 * Generic compiler-dependent macros required for kernel
79 * build go below this comment. Actual compiler/compiler version
80 * specific implementations come from the above header files
83 struct ftrace_branch_data {
89 unsigned long correct;
90 unsigned long incorrect;
96 unsigned long miss_hit[2];
101 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
102 * to disable branch tracing on a per file basis.
104 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
105 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
106 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
108 #define likely_notrace(x) __builtin_expect(!!(x), 1)
109 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
111 #define __branch_check__(x, expect) ({ \
113 static struct ftrace_branch_data \
114 __attribute__((__aligned__(4))) \
115 __attribute__((section("_ftrace_annotated_branch"))) \
121 ______r = likely_notrace(x); \
122 ftrace_likely_update(&______f, ______r, expect); \
127 * Using __builtin_constant_p(x) to ignore cases where the return
128 * value is always the same. This idea is taken from a similar patch
129 * written by Daniel Walker.
132 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
135 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
138 #ifdef CONFIG_PROFILE_ALL_BRANCHES
140 * "Define 'is'", Bill Clinton
141 * "Define 'if'", Steven Rostedt
143 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
144 #define __trace_if(cond) \
145 if (__builtin_constant_p((cond)) ? !!(cond) : \
148 static struct ftrace_branch_data \
149 __attribute__((__aligned__(4))) \
150 __attribute__((section("_ftrace_branch"))) \
156 ______r = !!(cond); \
157 ______f.miss_hit[______r]++; \
160 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
163 # define likely(x) __builtin_expect(!!(x), 1)
164 # define unlikely(x) __builtin_expect(!!(x), 0)
167 /* Optimization barrier */
169 # define barrier() __memory_barrier()
172 /* Unreachable code */
174 # define unreachable() do { } while (1)
178 # define RELOC_HIDE(ptr, off) \
179 ({ unsigned long __ptr; \
180 __ptr = (unsigned long) (ptr); \
181 (typeof(ptr)) (__ptr + (off)); })
184 #ifndef OPTIMIZER_HIDE_VAR
185 #define OPTIMIZER_HIDE_VAR(var) barrier()
188 /* Not-quite-unique ID. */
190 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
193 #include <uapi/linux/types.h>
195 static __always_inline void data_access_exceeds_word_size(void)
196 #ifdef __compiletime_warning
197 __compiletime_warning("data access exceeds word size and won't be atomic")
201 static __always_inline void data_access_exceeds_word_size(void)
205 static __always_inline void __read_once_size(volatile void *p, void *res, int size)
208 case 1: *(__u8 *)res = *(volatile __u8 *)p; break;
209 case 2: *(__u16 *)res = *(volatile __u16 *)p; break;
210 case 4: *(__u32 *)res = *(volatile __u32 *)p; break;
212 case 8: *(__u64 *)res = *(volatile __u64 *)p; break;
216 __builtin_memcpy((void *)res, (const void *)p, size);
217 data_access_exceeds_word_size();
222 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
225 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
226 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
227 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
229 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
233 __builtin_memcpy((void *)p, (const void *)res, size);
234 data_access_exceeds_word_size();
240 * Prevent the compiler from merging or refetching reads or writes. The
241 * compiler is also forbidden from reordering successive instances of
242 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
243 * compiler is aware of some particular ordering. One way to make the
244 * compiler aware of ordering is to put the two invocations of READ_ONCE,
245 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
247 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
248 * data types like structs or unions. If the size of the accessed data
249 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
250 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a
251 * compile-time warning.
253 * Their two major use cases are: (1) Mediating communication between
254 * process-level code and irq/NMI handlers, all running on the same CPU,
255 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
256 * mutilate accesses that either do not require ordering or that interact
257 * with an explicit memory barrier or atomic instruction that provides the
261 #define READ_ONCE(x) \
262 ({ typeof(x) __val; __read_once_size(&x, &__val, sizeof(__val)); __val; })
264 #define WRITE_ONCE(x, val) \
265 ({ typeof(x) __val; __val = val; __write_once_size(&x, &__val, sizeof(__val)); __val; })
267 #endif /* __KERNEL__ */
269 #endif /* __ASSEMBLY__ */
273 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
274 * warning for each use, in hopes of speeding the functions removal.
276 * int __deprecated foo(void)
279 # define __deprecated /* unimplemented */
283 #define __deprecated_for_modules __deprecated
285 #define __deprecated_for_modules
292 #ifndef CONFIG_ENABLE_MUST_CHECK
296 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
298 #undef __deprecated_for_modules
300 #define __deprecated_for_modules
304 * Allow us to avoid 'defined but not used' warnings on functions and data,
305 * as well as force them to be emitted to the assembly file.
307 * As of gcc 3.4, static functions that are not marked with attribute((used))
308 * may be elided from the assembly file. As of gcc 3.4, static data not so
309 * marked will not be elided, but this may change in a future gcc version.
311 * NOTE: Because distributions shipped with a backported unit-at-a-time
312 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
313 * for gcc >=3.3 instead of 3.4.
315 * In prior versions of gcc, such functions and data would be emitted, but
316 * would be warned about except with attribute((unused)).
318 * Mark functions that are referenced only in inline assembly as __used so
319 * the code is emitted even though it appears to be unreferenced.
322 # define __used /* unimplemented */
325 #ifndef __maybe_unused
326 # define __maybe_unused /* unimplemented */
329 #ifndef __always_unused
330 # define __always_unused /* unimplemented */
338 * Rather then using noinline to prevent stack consumption, use
339 * noinline_for_stack instead. For documentation reasons.
341 #define noinline_for_stack noinline
343 #ifndef __always_inline
344 #define __always_inline inline
347 #endif /* __KERNEL__ */
350 * From the GCC manual:
352 * Many functions do not examine any values except their arguments,
353 * and have no effects except the return value. Basically this is
354 * just slightly more strict class than the `pure' attribute above,
355 * since function is not allowed to read global memory.
357 * Note that a function that has pointer arguments and examines the
358 * data pointed to must _not_ be declared `const'. Likewise, a
359 * function that calls a non-`const' function usually must not be
360 * `const'. It does not make sense for a `const' function to return
363 #ifndef __attribute_const__
364 # define __attribute_const__ /* unimplemented */
368 * Tell gcc if a function is cold. The compiler will assume any path
369 * directly leading to the call is unlikely.
376 /* Simple shorthand for a section definition */
378 # define __section(S) __attribute__ ((__section__(#S)))
385 /* Are two types/vars the same type (ignoring qualifiers)? */
387 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
390 /* Is this type a native word size -- useful for atomic operations */
391 #ifndef __native_word
392 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
395 /* Compile time object size, -1 for unknown */
396 #ifndef __compiletime_object_size
397 # define __compiletime_object_size(obj) -1
399 #ifndef __compiletime_warning
400 # define __compiletime_warning(message)
402 #ifndef __compiletime_error
403 # define __compiletime_error(message)
405 * Sparse complains of variable sized arrays due to the temporary variable in
406 * __compiletime_assert. Unfortunately we can't just expand it out to make
407 * sparse see a constant array size without breaking compiletime_assert on old
408 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
411 # define __compiletime_error_fallback(condition) \
412 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
415 #ifndef __compiletime_error_fallback
416 # define __compiletime_error_fallback(condition) do { } while (0)
419 #define __compiletime_assert(condition, msg, prefix, suffix) \
421 bool __cond = !(condition); \
422 extern void prefix ## suffix(void) __compiletime_error(msg); \
424 prefix ## suffix(); \
425 __compiletime_error_fallback(__cond); \
428 #define _compiletime_assert(condition, msg, prefix, suffix) \
429 __compiletime_assert(condition, msg, prefix, suffix)
432 * compiletime_assert - break build and emit msg if condition is false
433 * @condition: a compile-time constant condition to check
434 * @msg: a message to emit if condition is false
436 * In tradition of POSIX assert, this macro will break the build if the
437 * supplied condition is *false*, emitting the supplied error message if the
438 * compiler has support to do so.
440 #define compiletime_assert(condition, msg) \
441 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
443 #define compiletime_assert_atomic_type(t) \
444 compiletime_assert(__native_word(t), \
445 "Need native word sized stores/loads for atomicity.")
448 * Prevent the compiler from merging or refetching accesses. The compiler
449 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
450 * but only when the compiler is aware of some particular ordering. One way
451 * to make the compiler aware of ordering is to put the two invocations of
452 * ACCESS_ONCE() in different C statements.
454 * This macro does absolutely -nothing- to prevent the CPU from reordering,
455 * merging, or refetching absolutely anything at any time. Its main intended
456 * use is to mediate communication between process-level code and irq/NMI
457 * handlers, all running on the same CPU.
459 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
461 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
462 #ifdef CONFIG_KPROBES
463 # define __kprobes __attribute__((__section__(".kprobes.text")))
464 # define nokprobe_inline __always_inline
467 # define nokprobe_inline inline
469 #endif /* __LINUX_COMPILER_H */