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__ */
36 # define __chk_user_ptr(x) (void)0
37 # define __chk_io_ptr(x) (void)0
38 # define __builtin_warning(x, y...) (1)
39 # define __must_hold(x)
40 # define __acquires(x)
41 # define __releases(x)
42 # define __acquire(x) (void)0
43 # define __release(x) (void)0
44 # define __cond_lock(x,c) (c)
48 # define ACCESS_PRIVATE(p, member) ((p)->member)
49 #endif /* __CHECKER__ */
51 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
52 #define ___PASTE(a,b) a##b
53 #define __PASTE(a,b) ___PASTE(a,b)
58 * Minimal backport of compiler_attributes.h to add support for __copy
59 * to v4.9.y so that we can use it in init/exit_module to avoid
60 * -Werror=missing-attributes errors on GCC 9.
62 #ifndef __has_attribute
63 # define __has_attribute(x) __GCC4_has_attribute_##x
64 # define __GCC4_has_attribute___copy__ 0
67 #if __has_attribute(__copy__)
68 # define __copy(symbol) __attribute__((__copy__(symbol)))
70 # define __copy(symbol)
74 #include <linux/compiler-gcc.h>
77 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
78 #define notrace __attribute__((hotpatch(0,0)))
80 #define notrace __attribute__((no_instrument_function))
83 /* Intel compiler defines __GNUC__. So we will overwrite implementations
84 * coming from above header files here
86 #ifdef __INTEL_COMPILER
87 # include <linux/compiler-intel.h>
90 /* Clang compiler defines __GNUC__. So we will overwrite implementations
91 * coming from above header files here
94 #include <linux/compiler-clang.h>
98 * Generic compiler-dependent macros required for kernel
99 * build go below this comment. Actual compiler/compiler version
100 * specific implementations come from the above header files
103 struct ftrace_branch_data {
109 unsigned long correct;
110 unsigned long incorrect;
116 unsigned long miss_hit[2];
121 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
122 * to disable branch tracing on a per file basis.
124 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
125 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
126 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
128 #define likely_notrace(x) __builtin_expect(!!(x), 1)
129 #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
131 #define __branch_check__(x, expect) ({ \
133 static struct ftrace_branch_data \
134 __attribute__((__aligned__(4))) \
135 __attribute__((section("_ftrace_annotated_branch"))) \
141 ______r = likely_notrace(x); \
142 ftrace_likely_update(&______f, ______r, expect); \
147 * Using __builtin_constant_p(x) to ignore cases where the return
148 * value is always the same. This idea is taken from a similar patch
149 * written by Daniel Walker.
152 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
155 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
158 #ifdef CONFIG_PROFILE_ALL_BRANCHES
160 * "Define 'is'", Bill Clinton
161 * "Define 'if'", Steven Rostedt
163 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
164 #define __trace_if(cond) \
165 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
168 static struct ftrace_branch_data \
169 __attribute__((__aligned__(4))) \
170 __attribute__((section("_ftrace_branch"))) \
176 ______r = !!(cond); \
177 ______f.miss_hit[______r]++; \
180 #endif /* CONFIG_PROFILE_ALL_BRANCHES */
183 # define likely(x) __builtin_expect(!!(x), 1)
184 # define unlikely(x) __builtin_expect(!!(x), 0)
187 /* Optimization barrier */
189 # define barrier() __memory_barrier()
193 # define barrier_data(ptr) barrier()
196 /* workaround for GCC PR82365 if needed */
197 #ifndef barrier_before_unreachable
198 # define barrier_before_unreachable() do { } while (0)
201 /* Unreachable code */
203 # define unreachable() do { } while (1)
207 * KENTRY - kernel entry point
208 * This can be used to annotate symbols (functions or data) that are used
209 * without their linker symbol being referenced explicitly. For example,
210 * interrupt vector handlers, or functions in the kernel image that are found
213 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
214 * are handled in their own way (with KEEP() in linker scripts).
216 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
217 * linker script. For example an architecture could KEEP() its entire
218 * boot/exception vector code rather than annotate each function and data.
221 # define KENTRY(sym) \
222 extern typeof(sym) sym; \
223 static const unsigned long __kentry_##sym \
225 __attribute__((section("___kentry" "+" #sym ), used)) \
226 = (unsigned long)&sym;
230 # define RELOC_HIDE(ptr, off) \
231 ({ unsigned long __ptr; \
232 __ptr = (unsigned long) (ptr); \
233 (typeof(ptr)) (__ptr + (off)); })
236 #define absolute_pointer(val) RELOC_HIDE((void *)(val), 0)
238 #ifndef OPTIMIZER_HIDE_VAR
239 #define OPTIMIZER_HIDE_VAR(var) barrier()
242 /* Not-quite-unique ID. */
244 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
247 #include <uapi/linux/types.h>
249 #define __READ_ONCE_SIZE \
252 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
253 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
254 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
255 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
258 __builtin_memcpy((void *)res, (const void *)p, size); \
263 static __always_inline
264 void __read_once_size(const volatile void *p, void *res, int size)
271 * We can't declare function 'inline' because __no_sanitize_address confilcts
272 * with inlining. Attempt to inline it may cause a build failure.
273 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
274 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
276 # define __no_kasan_or_inline __no_sanitize_address __maybe_unused
278 # define __no_kasan_or_inline __always_inline
281 static __no_kasan_or_inline
282 void __read_once_size_nocheck(const volatile void *p, void *res, int size)
287 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
290 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
291 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
292 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
293 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
296 __builtin_memcpy((void *)p, (const void *)res, size);
302 * Prevent the compiler from merging or refetching reads or writes. The
303 * compiler is also forbidden from reordering successive instances of
304 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
305 * compiler is aware of some particular ordering. One way to make the
306 * compiler aware of ordering is to put the two invocations of READ_ONCE,
307 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
309 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
310 * data types like structs or unions. If the size of the accessed data
311 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
312 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at
313 * least two memcpy()s: one for the __builtin_memcpy() and then one for
314 * the macro doing the copy of variable - '__u' allocated on the stack.
316 * Their two major use cases are: (1) Mediating communication between
317 * process-level code and irq/NMI handlers, all running on the same CPU,
318 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
319 * mutilate accesses that either do not require ordering or that interact
320 * with an explicit memory barrier or atomic instruction that provides the
323 #include <linux/kasan-checks.h>
325 #define __READ_ONCE(x, check) \
327 union { typeof(x) __val; char __c[1]; } __u; \
329 __read_once_size(&(x), __u.__c, sizeof(x)); \
331 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
334 #define READ_ONCE(x) __READ_ONCE(x, 1)
337 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
338 * to hide memory access from KASAN.
340 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
342 static __no_kasan_or_inline
343 unsigned long read_word_at_a_time(const void *addr)
345 kasan_check_read(addr, 1);
346 return *(unsigned long *)addr;
349 #define WRITE_ONCE(x, val) \
351 union { typeof(x) __val; char __c[1]; } __u = \
352 { .__val = (__force typeof(x)) (val) }; \
353 __write_once_size(&(x), __u.__c, sizeof(x)); \
357 #endif /* __KERNEL__ */
359 #endif /* __ASSEMBLY__ */
363 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
364 * warning for each use, in hopes of speeding the functions removal.
366 * int __deprecated foo(void)
369 # define __deprecated /* unimplemented */
373 #define __deprecated_for_modules __deprecated
375 #define __deprecated_for_modules
382 #ifndef CONFIG_ENABLE_MUST_CHECK
386 #ifndef CONFIG_ENABLE_WARN_DEPRECATED
388 #undef __deprecated_for_modules
390 #define __deprecated_for_modules
398 * Allow us to avoid 'defined but not used' warnings on functions and data,
399 * as well as force them to be emitted to the assembly file.
401 * As of gcc 3.4, static functions that are not marked with attribute((used))
402 * may be elided from the assembly file. As of gcc 3.4, static data not so
403 * marked will not be elided, but this may change in a future gcc version.
405 * NOTE: Because distributions shipped with a backported unit-at-a-time
406 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
407 * for gcc >=3.3 instead of 3.4.
409 * In prior versions of gcc, such functions and data would be emitted, but
410 * would be warned about except with attribute((unused)).
412 * Mark functions that are referenced only in inline assembly as __used so
413 * the code is emitted even though it appears to be unreferenced.
416 # define __used /* unimplemented */
419 #ifndef __maybe_unused
420 # define __maybe_unused /* unimplemented */
423 #ifndef __always_unused
424 # define __always_unused /* unimplemented */
432 * Rather then using noinline to prevent stack consumption, use
433 * noinline_for_stack instead. For documentation reasons.
435 #define noinline_for_stack noinline
437 #ifndef __always_inline
438 #define __always_inline inline
441 #endif /* __KERNEL__ */
444 * From the GCC manual:
446 * Many functions do not examine any values except their arguments,
447 * and have no effects except the return value. Basically this is
448 * just slightly more strict class than the `pure' attribute above,
449 * since function is not allowed to read global memory.
451 * Note that a function that has pointer arguments and examines the
452 * data pointed to must _not_ be declared `const'. Likewise, a
453 * function that calls a non-`const' function usually must not be
454 * `const'. It does not make sense for a `const' function to return
457 #ifndef __attribute_const__
458 # define __attribute_const__ /* unimplemented */
461 #ifndef __latent_entropy
462 # define __latent_entropy
466 * Tell gcc if a function is cold. The compiler will assume any path
467 * directly leading to the call is unlikely.
474 /* Simple shorthand for a section definition */
476 # define __section(S) __attribute__ ((__section__(#S)))
484 * Assume alignment of return value.
486 #ifndef __assume_aligned
487 #define __assume_aligned(a, ...)
491 /* Are two types/vars the same type (ignoring qualifiers)? */
493 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
496 /* Is this type a native word size -- useful for atomic operations */
497 #ifndef __native_word
498 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
502 # define __optimize(level)
505 /* Compile time object size, -1 for unknown */
506 #ifndef __compiletime_object_size
507 # define __compiletime_object_size(obj) -1
509 #ifndef __compiletime_warning
510 # define __compiletime_warning(message)
512 #ifndef __compiletime_error
513 # define __compiletime_error(message)
515 * Sparse complains of variable sized arrays due to the temporary variable in
516 * __compiletime_assert. Unfortunately we can't just expand it out to make
517 * sparse see a constant array size without breaking compiletime_assert on old
518 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
521 # define __compiletime_error_fallback(condition) \
522 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
525 #ifndef __compiletime_error_fallback
526 # define __compiletime_error_fallback(condition) do { } while (0)
529 #define __compiletime_assert(condition, msg, prefix, suffix) \
531 bool __cond = !(condition); \
532 extern void prefix ## suffix(void) __compiletime_error(msg); \
534 prefix ## suffix(); \
535 __compiletime_error_fallback(__cond); \
538 #define _compiletime_assert(condition, msg, prefix, suffix) \
539 __compiletime_assert(condition, msg, prefix, suffix)
542 * compiletime_assert - break build and emit msg if condition is false
543 * @condition: a compile-time constant condition to check
544 * @msg: a message to emit if condition is false
546 * In tradition of POSIX assert, this macro will break the build if the
547 * supplied condition is *false*, emitting the supplied error message if the
548 * compiler has support to do so.
550 #define compiletime_assert(condition, msg) \
551 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
553 #define compiletime_assert_atomic_type(t) \
554 compiletime_assert(__native_word(t), \
555 "Need native word sized stores/loads for atomicity.")
558 * Prevent the compiler from merging or refetching accesses. The compiler
559 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
560 * but only when the compiler is aware of some particular ordering. One way
561 * to make the compiler aware of ordering is to put the two invocations of
562 * ACCESS_ONCE() in different C statements.
564 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
565 * on a union member will work as long as the size of the member matches the
566 * size of the union and the size is smaller than word size.
568 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
569 * between process-level code and irq/NMI handlers, all running on the same CPU,
570 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
571 * mutilate accesses that either do not require ordering or that interact
572 * with an explicit memory barrier or atomic instruction that provides the
575 * If possible use READ_ONCE()/WRITE_ONCE() instead.
577 #define __ACCESS_ONCE(x) ({ \
578 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
579 (volatile typeof(x) *)&(x); })
580 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
583 * lockless_dereference() - safely load a pointer for later dereference
584 * @p: The pointer to load
586 * Similar to rcu_dereference(), but for situations where the pointed-to
587 * object's lifetime is managed by something other than RCU. That
588 * "something other" might be reference counting or simple immortality.
590 * The seemingly unused variable ___typecheck_p validates that @p is
591 * indeed a pointer type by using a pointer to typeof(*p) as the type.
592 * Taking a pointer to typeof(*p) again is needed in case p is void *.
594 #define lockless_dereference(p) \
596 typeof(p) _________p1 = READ_ONCE(p); \
597 typeof(*(p)) *___typecheck_p __maybe_unused; \
598 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
602 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
603 #ifdef CONFIG_KPROBES
604 # define __kprobes __attribute__((__section__(".kprobes.text")))
605 # define nokprobe_inline __always_inline
608 # define nokprobe_inline inline
612 * This is needed in functions which generate the stack canary, see
613 * arch/x86/kernel/smpboot.c::start_secondary() for an example.
615 #define prevent_tail_call_optimization() mb()
617 #endif /* __LINUX_COMPILER_H */