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 * 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.
60 #ifndef __has_attribute
61 # define __has_attribute(x) __GCC4_has_attribute_##x
62 # define __GCC4_has_attribute___copy__ 0
65 #if __has_attribute(__copy__)
66 # define __copy(symbol) __attribute__((__copy__(symbol)))
68 # define __copy(symbol)
72 #include <linux/compiler-gcc.h>
75 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
76 #define notrace __attribute__((hotpatch(0,0)))
78 #define notrace __attribute__((no_instrument_function))
81 /* Intel compiler defines __GNUC__. So we will overwrite implementations
82 * coming from above header files here
84 #ifdef __INTEL_COMPILER
85 # include <linux/compiler-intel.h>
88 /* Clang compiler defines __GNUC__. So we will overwrite implementations
89 * coming from above header files here
92 #include <linux/compiler-clang.h>
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
101 struct ftrace_branch_data {
107 unsigned long correct;
108 unsigned long incorrect;
114 unsigned long miss_hit[2];
119 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
120 * to disable branch tracing on a per file basis.
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);
126 #define likely_notrace(x) __builtin_expect(!!(x), 1)
127 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
129 #define __branch_check__(x, expect) ({ \
131 static struct ftrace_branch_data \
132 __attribute__((__aligned__(4))) \
133 __attribute__((section("_ftrace_annotated_branch"))) \
139 ______r = likely_notrace(x); \
140 ftrace_likely_update(&______f, ______r, expect); \
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.
150 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
153 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
156 #ifdef CONFIG_PROFILE_ALL_BRANCHES
158 * "Define 'is'", Bill Clinton
159 * "Define 'if'", Steven Rostedt
161 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
162 #define __trace_if(cond) \
163 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
166 static struct ftrace_branch_data \
167 __attribute__((__aligned__(4))) \
168 __attribute__((section("_ftrace_branch"))) \
174 ______r = !!(cond); \
175 ______f.miss_hit[______r]++; \
178 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
181 # define likely(x) __builtin_expect(!!(x), 1)
182 # define unlikely(x) __builtin_expect(!!(x), 0)
185 /* Optimization barrier */
187 # define barrier() __memory_barrier()
191 # define barrier_data(ptr) barrier()
194 /* workaround for GCC PR82365 if needed */
195 #ifndef barrier_before_unreachable
196 # define barrier_before_unreachable() do { } while (0)
199 /* Unreachable code */
201 # define unreachable() do { } while (1)
205 # define RELOC_HIDE(ptr, off) \
206 ({ unsigned long __ptr; \
207 __ptr = (unsigned long) (ptr); \
208 (typeof(ptr)) (__ptr + (off)); })
211 #ifndef OPTIMIZER_HIDE_VAR
212 #define OPTIMIZER_HIDE_VAR(var) barrier()
215 /* Not-quite-unique ID. */
217 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
220 #include <uapi/linux/types.h>
222 #define __READ_ONCE_SIZE \
225 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
226 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
227 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
228 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
231 __builtin_memcpy((void *)res, (const void *)p, size); \
236 static __always_inline
237 void __read_once_size(const volatile void *p, void *res, int size)
244 * This function is not 'inline' because __no_sanitize_address confilcts
245 * with inlining. Attempt to inline it may cause a build failure.
246 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
247 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
249 static __no_sanitize_address __maybe_unused
250 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
255 static __always_inline
256 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
262 static __always_inline void __write_once_size(volatile void *p, void *res, int 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;
271 __builtin_memcpy((void *)p, (const void *)res, size);
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.
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.
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
298 #define __READ_ONCE(x, check) \
300 union { typeof(x) __val; char __c[1]; } __u; \
302 __read_once_size(&(x), __u.__c, sizeof(x)); \
304 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
307 #define READ_ONCE(x) __READ_ONCE(x, 1)
310 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
311 * to hide memory access from KASAN.
313 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
315 #define WRITE_ONCE(x, val) \
317 union { typeof(x) __val; char __c[1]; } __u = \
318 { .__val = (__force typeof(x)) (val) }; \
319 __write_once_size(&(x), __u.__c, sizeof(x)); \
323 #endif /* __KERNEL__ */
325 #endif /* __ASSEMBLY__ */
329 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
330 * warning for each use, in hopes of speeding the functions removal.
332 * int __deprecated foo(void)
335 # define __deprecated /* unimplemented */
339 #define __deprecated_for_modules __deprecated
341 #define __deprecated_for_modules
348 #ifndef CONFIG_ENABLE_MUST_CHECK
352 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
354 #undef __deprecated_for_modules
356 #define __deprecated_for_modules
360 * Allow us to avoid 'defined but not used' warnings on functions and data,
361 * as well as force them to be emitted to the assembly file.
363 * As of gcc 3.4, static functions that are not marked with attribute((used))
364 * may be elided from the assembly file. As of gcc 3.4, static data not so
365 * marked will not be elided, but this may change in a future gcc version.
367 * NOTE: Because distributions shipped with a backported unit-at-a-time
368 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
369 * for gcc >=3.3 instead of 3.4.
371 * In prior versions of gcc, such functions and data would be emitted, but
372 * would be warned about except with attribute((unused)).
374 * Mark functions that are referenced only in inline assembly as __used so
375 * the code is emitted even though it appears to be unreferenced.
378 # define __used /* unimplemented */
381 #ifndef __maybe_unused
382 # define __maybe_unused /* unimplemented */
385 #ifndef __always_unused
386 # define __always_unused /* unimplemented */
394 * Rather then using noinline to prevent stack consumption, use
395 * noinline_for_stack instead. For documentation reasons.
397 #define noinline_for_stack noinline
399 #ifndef __always_inline
400 #define __always_inline inline
403 #endif /* __KERNEL__ */
406 * From the GCC manual:
408 * Many functions do not examine any values except their arguments,
409 * and have no effects except the return value. Basically this is
410 * just slightly more strict class than the `pure' attribute above,
411 * since function is not allowed to read global memory.
413 * Note that a function that has pointer arguments and examines the
414 * data pointed to must _not_ be declared `const'. Likewise, a
415 * function that calls a non-`const' function usually must not be
416 * `const'. It does not make sense for a `const' function to return
419 #ifndef __attribute_const__
420 # define __attribute_const__ /* unimplemented */
424 * Tell gcc if a function is cold. The compiler will assume any path
425 * directly leading to the call is unlikely.
432 /* Simple shorthand for a section definition */
434 # define __section(S) __attribute__ ((__section__(#S)))
442 * Assume alignment of return value.
444 #ifndef __assume_aligned
445 #define __assume_aligned(a, ...)
449 /* Are two types/vars the same type (ignoring qualifiers)? */
451 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
454 /* Is this type a native word size -- useful for atomic operations */
455 #ifndef __native_word
456 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
459 /* Compile time object size, -1 for unknown */
460 #ifndef __compiletime_object_size
461 # define __compiletime_object_size(obj) -1
463 #ifndef __compiletime_warning
464 # define __compiletime_warning(message)
466 #ifndef __compiletime_error
467 # define __compiletime_error(message)
469 * Sparse complains of variable sized arrays due to the temporary variable in
470 * __compiletime_assert. Unfortunately we can't just expand it out to make
471 * sparse see a constant array size without breaking compiletime_assert on old
472 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
475 # define __compiletime_error_fallback(condition) \
476 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
479 #ifndef __compiletime_error_fallback
480 # define __compiletime_error_fallback(condition) do { } while (0)
483 #define __compiletime_assert(condition, msg, prefix, suffix) \
485 bool __cond = !(condition); \
486 extern void prefix ## suffix(void) __compiletime_error(msg); \
488 prefix ## suffix(); \
489 __compiletime_error_fallback(__cond); \
492 #define _compiletime_assert(condition, msg, prefix, suffix) \
493 __compiletime_assert(condition, msg, prefix, suffix)
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
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.
504 #define compiletime_assert(condition, msg) \
505 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
507 #define compiletime_assert_atomic_type(t) \
508 compiletime_assert(__native_word(t), \
509 "Need native word sized stores/loads for atomicity.")
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.
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.
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
529 * If possible use READ_ONCE()/WRITE_ONCE() instead.
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))
537 * lockless_dereference() - safely load a pointer for later dereference
538 * @p: The pointer to load
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.
544 #define lockless_dereference(p) \
546 typeof(p) _________p1 = READ_ONCE(p); \
547 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
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
557 # define nokprobe_inline inline
559 #endif /* __LINUX_COMPILER_H */