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)))
22 #else /* CONFIG_SPARSE_RCU_POINTER */
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 # ifdef STRUCTLEAK_PLUGIN
31 # define __user __attribute__((user))
40 # define __chk_user_ptr(x) (void)0
41 # define __chk_io_ptr(x) (void)0
42 # define __builtin_warning(x, y...) (1)
43 # define __must_hold(x)
44 # define __acquires(x)
45 # define __releases(x)
46 # define __acquire(x) (void)0
47 # define __release(x) (void)0
48 # define __cond_lock(x,c) (c)
52 # define ACCESS_PRIVATE(p, member) ((p)->member)
53 #endif /* __CHECKER__ */
55 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
56 #define ___PASTE(a,b) a##b
57 #define __PASTE(a,b) ___PASTE(a,b)
62 #include <linux/compiler-gcc.h>
65 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
66 #define notrace __attribute__((hotpatch(0,0)))
68 #define notrace __attribute__((no_instrument_function))
71 /* Intel compiler defines __GNUC__. So we will overwrite implementations
72 * coming from above header files here
74 #ifdef __INTEL_COMPILER
75 # include <linux/compiler-intel.h>
78 /* Clang compiler defines __GNUC__. So we will overwrite implementations
79 * coming from above header files here
82 #include <linux/compiler-clang.h>
86 * Generic compiler-dependent macros required for kernel
87 * build go below this comment. Actual compiler/compiler version
88 * specific implementations come from the above header files
91 struct ftrace_branch_data {
97 unsigned long correct;
98 unsigned long incorrect;
104 unsigned long miss_hit[2];
109 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
110 * to disable branch tracing on a per file basis.
112 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
113 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
114 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
116 #define likely_notrace(x) __builtin_expect(!!(x), 1)
117 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
119 #define __branch_check__(x, expect) ({ \
121 static struct ftrace_branch_data \
122 __attribute__((__aligned__(4))) \
123 __attribute__((section("_ftrace_annotated_branch"))) \
129 ______r = likely_notrace(x); \
130 ftrace_likely_update(&______f, ______r, expect); \
135 * Using __builtin_constant_p(x) to ignore cases where the return
136 * value is always the same. This idea is taken from a similar patch
137 * written by Daniel Walker.
140 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
143 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
146 #ifdef CONFIG_PROFILE_ALL_BRANCHES
148 * "Define 'is'", Bill Clinton
149 * "Define 'if'", Steven Rostedt
151 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
152 #define __trace_if(cond) \
153 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
156 static struct ftrace_branch_data \
157 __attribute__((__aligned__(4))) \
158 __attribute__((section("_ftrace_branch"))) \
164 ______r = !!(cond); \
165 ______f.miss_hit[______r]++; \
168 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
171 # define likely(x) __builtin_expect(!!(x), 1)
172 # define unlikely(x) __builtin_expect(!!(x), 0)
175 /* Optimization barrier */
177 # define barrier() __memory_barrier()
181 # define barrier_data(ptr) barrier()
184 /* Unreachable code */
186 # define unreachable() do { } while (1)
190 * KENTRY - kernel entry point
191 * This can be used to annotate symbols (functions or data) that are used
192 * without their linker symbol being referenced explicitly. For example,
193 * interrupt vector handlers, or functions in the kernel image that are found
196 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
197 * are handled in their own way (with KEEP() in linker scripts).
199 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
200 * linker script. For example an architecture could KEEP() its entire
201 * boot/exception vector code rather than annotate each function and data.
204 # define KENTRY(sym) \
205 extern typeof(sym) sym; \
206 static const unsigned long __kentry_##sym \
208 __attribute__((section("___kentry" "+" #sym ), used)) \
209 = (unsigned long)&sym;
213 # define RELOC_HIDE(ptr, off) \
214 ({ unsigned long __ptr; \
215 __ptr = (unsigned long) (ptr); \
216 (typeof(ptr)) (__ptr + (off)); })
219 #ifndef OPTIMIZER_HIDE_VAR
220 #define OPTIMIZER_HIDE_VAR(var) barrier()
223 /* Not-quite-unique ID. */
225 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
228 #include <uapi/linux/types.h>
230 #define __READ_ONCE_SIZE \
233 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
234 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
235 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
236 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
239 __builtin_memcpy((void *)res, (const void *)p, size); \
244 static __always_inline
245 void __read_once_size(const volatile void *p, void *res, int size)
252 * This function is not 'inline' because __no_sanitize_address confilcts
253 * with inlining. Attempt to inline it may cause a build failure.
254 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
255 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
257 static __no_sanitize_address __maybe_unused
258 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
263 static __always_inline
264 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
270 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
273 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
274 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
275 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
276 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
279 __builtin_memcpy((void *)p, (const void *)res, size);
285 * Prevent the compiler from merging or refetching reads or writes. The
286 * compiler is also forbidden from reordering successive instances of
287 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
288 * compiler is aware of some particular ordering. One way to make the
289 * compiler aware of ordering is to put the two invocations of READ_ONCE,
290 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
292 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
293 * data types like structs or unions. If the size of the accessed data
294 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
295 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at
296 * least two memcpy()s: one for the __builtin_memcpy() and then one for
297 * the macro doing the copy of variable - '__u' allocated on the stack.
299 * Their two major use cases are: (1) Mediating communication between
300 * process-level code and irq/NMI handlers, all running on the same CPU,
301 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
302 * mutilate accesses that either do not require ordering or that interact
303 * with an explicit memory barrier or atomic instruction that provides the
307 #define __READ_ONCE(x, check) \
309 union { typeof(x) __val; char __c[1]; } __u; \
311 __read_once_size(&(x), __u.__c, sizeof(x)); \
313 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
316 #define READ_ONCE(x) __READ_ONCE(x, 1)
319 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
320 * to hide memory access from KASAN.
322 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
324 #define WRITE_ONCE(x, val) \
326 union { typeof(x) __val; char __c[1]; } __u = \
327 { .__val = (__force typeof(x)) (val) }; \
328 __write_once_size(&(x), __u.__c, sizeof(x)); \
332 #endif /* __KERNEL__ */
334 #endif /* __ASSEMBLY__ */
338 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
339 * warning for each use, in hopes of speeding the functions removal.
341 * int __deprecated foo(void)
344 # define __deprecated /* unimplemented */
348 #define __deprecated_for_modules __deprecated
350 #define __deprecated_for_modules
357 #ifndef CONFIG_ENABLE_MUST_CHECK
361 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
363 #undef __deprecated_for_modules
365 #define __deprecated_for_modules
373 * Allow us to avoid 'defined but not used' warnings on functions and data,
374 * as well as force them to be emitted to the assembly file.
376 * As of gcc 3.4, static functions that are not marked with attribute((used))
377 * may be elided from the assembly file. As of gcc 3.4, static data not so
378 * marked will not be elided, but this may change in a future gcc version.
380 * NOTE: Because distributions shipped with a backported unit-at-a-time
381 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
382 * for gcc >=3.3 instead of 3.4.
384 * In prior versions of gcc, such functions and data would be emitted, but
385 * would be warned about except with attribute((unused)).
387 * Mark functions that are referenced only in inline assembly as __used so
388 * the code is emitted even though it appears to be unreferenced.
391 # define __used /* unimplemented */
394 #ifndef __maybe_unused
395 # define __maybe_unused /* unimplemented */
398 #ifndef __always_unused
399 # define __always_unused /* unimplemented */
407 * Rather then using noinline to prevent stack consumption, use
408 * noinline_for_stack instead. For documentation reasons.
410 #define noinline_for_stack noinline
412 #ifndef __always_inline
413 #define __always_inline inline
416 #endif /* __KERNEL__ */
419 * From the GCC manual:
421 * Many functions do not examine any values except their arguments,
422 * and have no effects except the return value. Basically this is
423 * just slightly more strict class than the `pure' attribute above,
424 * since function is not allowed to read global memory.
426 * Note that a function that has pointer arguments and examines the
427 * data pointed to must _not_ be declared `const'. Likewise, a
428 * function that calls a non-`const' function usually must not be
429 * `const'. It does not make sense for a `const' function to return
432 #ifndef __attribute_const__
433 # define __attribute_const__ /* unimplemented */
436 #ifndef __latent_entropy
437 # define __latent_entropy
441 * Tell gcc if a function is cold. The compiler will assume any path
442 * directly leading to the call is unlikely.
449 /* Simple shorthand for a section definition */
451 # define __section(S) __attribute__ ((__section__(#S)))
459 * Assume alignment of return value.
461 #ifndef __assume_aligned
462 #define __assume_aligned(a, ...)
466 /* Are two types/vars the same type (ignoring qualifiers)? */
468 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
471 /* Is this type a native word size -- useful for atomic operations */
472 #ifndef __native_word
473 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
476 /* Compile time object size, -1 for unknown */
477 #ifndef __compiletime_object_size
478 # define __compiletime_object_size(obj) -1
480 #ifndef __compiletime_warning
481 # define __compiletime_warning(message)
483 #ifndef __compiletime_error
484 # define __compiletime_error(message)
486 * Sparse complains of variable sized arrays due to the temporary variable in
487 * __compiletime_assert. Unfortunately we can't just expand it out to make
488 * sparse see a constant array size without breaking compiletime_assert on old
489 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
492 # define __compiletime_error_fallback(condition) \
493 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
496 #ifndef __compiletime_error_fallback
497 # define __compiletime_error_fallback(condition) do { } while (0)
500 #define __compiletime_assert(condition, msg, prefix, suffix) \
502 bool __cond = !(condition); \
503 extern void prefix ## suffix(void) __compiletime_error(msg); \
505 prefix ## suffix(); \
506 __compiletime_error_fallback(__cond); \
509 #define _compiletime_assert(condition, msg, prefix, suffix) \
510 __compiletime_assert(condition, msg, prefix, suffix)
513 * compiletime_assert - break build and emit msg if condition is false
514 * @condition: a compile-time constant condition to check
515 * @msg: a message to emit if condition is false
517 * In tradition of POSIX assert, this macro will break the build if the
518 * supplied condition is *false*, emitting the supplied error message if the
519 * compiler has support to do so.
521 #define compiletime_assert(condition, msg) \
522 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
524 #define compiletime_assert_atomic_type(t) \
525 compiletime_assert(__native_word(t), \
526 "Need native word sized stores/loads for atomicity.")
529 * Prevent the compiler from merging or refetching accesses. The compiler
530 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
531 * but only when the compiler is aware of some particular ordering. One way
532 * to make the compiler aware of ordering is to put the two invocations of
533 * ACCESS_ONCE() in different C statements.
535 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
536 * on a union member will work as long as the size of the member matches the
537 * size of the union and the size is smaller than word size.
539 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
540 * between process-level code and irq/NMI handlers, all running on the same CPU,
541 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
542 * mutilate accesses that either do not require ordering or that interact
543 * with an explicit memory barrier or atomic instruction that provides the
546 * If possible use READ_ONCE()/WRITE_ONCE() instead.
548 #define __ACCESS_ONCE(x) ({ \
549 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
550 (volatile typeof(x) *)&(x); })
551 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
554 * lockless_dereference() - safely load a pointer for later dereference
555 * @p: The pointer to load
557 * Similar to rcu_dereference(), but for situations where the pointed-to
558 * object's lifetime is managed by something other than RCU. That
559 * "something other" might be reference counting or simple immortality.
561 * The seemingly unused variable ___typecheck_p validates that @p is
562 * indeed a pointer type by using a pointer to typeof(*p) as the type.
563 * Taking a pointer to typeof(*p) again is needed in case p is void *.
565 #define lockless_dereference(p) \
567 typeof(p) _________p1 = READ_ONCE(p); \
568 typeof(*(p)) *___typecheck_p __maybe_unused; \
569 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
573 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
574 #ifdef CONFIG_KPROBES
575 # define __kprobes __attribute__((__section__(".kprobes.text")))
576 # define nokprobe_inline __always_inline
579 # define nokprobe_inline inline
581 #endif /* __LINUX_COMPILER_H */