blob: 668569844d37cef4d51c6c7652d5f34ded2a66d6 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __LINUX_COMPILER_H
2#define __LINUX_COMPILER_H
3
4#ifndef __ASSEMBLY__
5
6#ifdef __CHECKER__
7# define __user __attribute__((noderef, address_space(1)))
Rusty Russelle0fdb0e2009-10-29 22:34:15 +09008# define __kernel __attribute__((address_space(0)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07009# define __safe __attribute__((safe))
10# define __force __attribute__((force))
11# define __nocast __attribute__((nocast))
12# define __iomem __attribute__((noderef, address_space(2)))
Josh Triplett85290912012-12-17 16:03:24 -080013# define __must_hold(x) __attribute__((context(x,1,1)))
Josh Triplettc902e0a2006-09-30 23:28:21 -070014# 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)
Josh Triplettdcc8e552006-09-29 02:01:03 -070018# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
Rusty Russelle0fdb0e2009-10-29 22:34:15 +090019# define __percpu __attribute__((noderef, address_space(3)))
Paul E. McKenneyca5ecdd2010-04-28 14:39:09 -070020#ifdef CONFIG_SPARSE_RCU_POINTER
21# define __rcu __attribute__((noderef, address_space(4)))
Boqun Fengad315452015-12-29 12:18:46 +080022#else /* CONFIG_SPARSE_RCU_POINTER */
Paul E. McKenney71d1d5c2010-05-11 16:13:14 -070023# define __rcu
Boqun Fengad315452015-12-29 12:18:46 +080024#endif /* CONFIG_SPARSE_RCU_POINTER */
25# define __private __attribute__((noderef))
Al Viroc47ffe32007-07-26 17:35:29 +010026extern void __chk_user_ptr(const volatile void __user *);
27extern void __chk_io_ptr(const volatile void __iomem *);
Boqun Fengad315452015-12-29 12:18:46 +080028# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
29#else /* __CHECKER__ */
Linus Torvalds1da177e2005-04-16 15:20:36 -070030# define __user
31# define __kernel
32# define __safe
33# define __force
34# define __nocast
35# define __iomem
36# define __chk_user_ptr(x) (void)0
37# define __chk_io_ptr(x) (void)0
38# define __builtin_warning(x, y...) (1)
Josh Triplett85290912012-12-17 16:03:24 -080039# define __must_hold(x)
Linus Torvalds1da177e2005-04-16 15:20:36 -070040# define __acquires(x)
41# define __releases(x)
42# define __acquire(x) (void)0
43# define __release(x) (void)0
Josh Triplettdcc8e552006-09-29 02:01:03 -070044# define __cond_lock(x,c) (c)
Rusty Russelle0fdb0e2009-10-29 22:34:15 +090045# define __percpu
Paul E. McKenney71d1d5c2010-05-11 16:13:14 -070046# define __rcu
Boqun Fengad315452015-12-29 12:18:46 +080047# define __private
48# define ACCESS_PRIVATE(p, member) ((p)->member)
49#endif /* __CHECKER__ */
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Rusty Russell6f33d582012-11-22 12:30:25 +103051/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
52#define ___PASTE(a,b) a##b
53#define __PASTE(a,b) ___PASTE(a,b)
54
Linus Torvalds1da177e2005-04-16 15:20:36 -070055#ifdef __KERNEL__
56
Linus Torvaldsf153b822009-01-02 09:23:03 -080057#ifdef __GNUC__
58#include <linux/compiler-gcc.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070059#endif
60
Christian Borntraeger0c5a69f2015-10-07 10:54:36 +020061#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
Heiko Carstens61f55212015-01-18 16:45:42 +010062#define notrace __attribute__((hotpatch(0,0)))
63#else
Steven Rostedt28614882008-08-14 22:47:18 -040064#define notrace __attribute__((no_instrument_function))
Heiko Carstens61f55212015-01-18 16:45:42 +010065#endif
Steven Rostedt28614882008-08-14 22:47:18 -040066
Linus Torvalds1da177e2005-04-16 15:20:36 -070067/* Intel compiler defines __GNUC__. So we will overwrite implementations
68 * coming from above header files here
69 */
70#ifdef __INTEL_COMPILER
71# include <linux/compiler-intel.h>
72#endif
73
Mark Charlebois565cbdc2012-11-20 22:13:10 +010074/* Clang compiler defines __GNUC__. So we will overwrite implementations
75 * coming from above header files here
76 */
77#ifdef __clang__
78#include <linux/compiler-clang.h>
79#endif
80
Linus Torvalds1da177e2005-04-16 15:20:36 -070081/*
82 * Generic compiler-dependent macros required for kernel
83 * build go below this comment. Actual compiler/compiler version
84 * specific implementations come from the above header files
85 */
86
Steven Rostedt2ed84ee2008-11-12 15:24:24 -050087struct ftrace_branch_data {
Steven Rostedt1f0d69a2008-11-12 00:14:39 -050088 const char *func;
89 const char *file;
90 unsigned line;
Steven Rostedt2bcd5212008-11-21 01:30:54 -050091 union {
92 struct {
93 unsigned long correct;
94 unsigned long incorrect;
95 };
96 struct {
97 unsigned long miss;
98 unsigned long hit;
99 };
Witold Baryluk97e7e4f2009-03-17 21:15:44 +0100100 unsigned long miss_hit[2];
Steven Rostedt2bcd5212008-11-21 01:30:54 -0500101 };
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500102};
Steven Rostedt2ed84ee2008-11-12 15:24:24 -0500103
104/*
105 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
106 * to disable branch tracing on a per file basis.
107 */
Bart Van Assched9ad8bc2009-04-05 16:20:02 +0200108#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
109 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
Steven Rostedt2ed84ee2008-11-12 15:24:24 -0500110void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500111
112#define likely_notrace(x) __builtin_expect(!!(x), 1)
113#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
114
Steven Rostedt45b79742008-11-21 00:40:40 -0500115#define __branch_check__(x, expect) ({ \
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500116 int ______r; \
Steven Rostedt2ed84ee2008-11-12 15:24:24 -0500117 static struct ftrace_branch_data \
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500118 __attribute__((__aligned__(4))) \
Steven Rostedt45b79742008-11-21 00:40:40 -0500119 __attribute__((section("_ftrace_annotated_branch"))) \
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500120 ______f = { \
121 .func = __func__, \
122 .file = __FILE__, \
123 .line = __LINE__, \
124 }; \
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500125 ______r = likely_notrace(x); \
Steven Rostedt45b79742008-11-21 00:40:40 -0500126 ftrace_likely_update(&______f, ______r, expect); \
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500127 ______r; \
128 })
129
130/*
131 * Using __builtin_constant_p(x) to ignore cases where the return
132 * value is always the same. This idea is taken from a similar patch
133 * written by Daniel Walker.
134 */
135# ifndef likely
Steven Rostedt45b79742008-11-21 00:40:40 -0500136# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500137# endif
138# ifndef unlikely
Steven Rostedt45b79742008-11-21 00:40:40 -0500139# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500140# endif
Steven Rostedt2bcd5212008-11-21 01:30:54 -0500141
142#ifdef CONFIG_PROFILE_ALL_BRANCHES
143/*
144 * "Define 'is'", Bill Clinton
145 * "Define 'if'", Steven Rostedt
146 */
Linus Torvaldsab3c9c62009-04-07 07:59:41 -0700147#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
148#define __trace_if(cond) \
Arnd Bergmannb33c8ff2016-02-12 22:26:42 +0100149 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
Steven Rostedt2bcd5212008-11-21 01:30:54 -0500150 ({ \
151 int ______r; \
152 static struct ftrace_branch_data \
153 __attribute__((__aligned__(4))) \
154 __attribute__((section("_ftrace_branch"))) \
155 ______f = { \
156 .func = __func__, \
157 .file = __FILE__, \
158 .line = __LINE__, \
159 }; \
160 ______r = !!(cond); \
Witold Baryluk97e7e4f2009-03-17 21:15:44 +0100161 ______f.miss_hit[______r]++; \
Steven Rostedt2bcd5212008-11-21 01:30:54 -0500162 ______r; \
163 }))
164#endif /* CONFIG_PROFILE_ALL_BRANCHES */
165
Steven Rostedt1f0d69a2008-11-12 00:14:39 -0500166#else
167# define likely(x) __builtin_expect(!!(x), 1)
168# define unlikely(x) __builtin_expect(!!(x), 0)
169#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
171/* Optimization barrier */
172#ifndef barrier
173# define barrier() __memory_barrier()
174#endif
175
Daniel Borkmann7829fb02015-04-30 04:13:52 +0200176#ifndef barrier_data
177# define barrier_data(ptr) barrier()
178#endif
179
David Daney38938c82009-12-04 17:44:50 -0800180/* Unreachable code */
181#ifndef unreachable
182# define unreachable() do { } while (1)
183#endif
184
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185#ifndef RELOC_HIDE
186# define RELOC_HIDE(ptr, off) \
187 ({ unsigned long __ptr; \
188 __ptr = (unsigned long) (ptr); \
189 (typeof(ptr)) (__ptr + (off)); })
190#endif
191
Cesar Eduardo Barrosfe8c8a12013-11-25 22:00:41 -0200192#ifndef OPTIMIZER_HIDE_VAR
193#define OPTIMIZER_HIDE_VAR(var) barrier()
194#endif
195
Rusty Russell6f33d582012-11-22 12:30:25 +1030196/* Not-quite-unique ID. */
197#ifndef __UNIQUE_ID
198# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
199#endif
200
Christian Borntraeger230fa252014-11-25 10:01:16 +0100201#include <uapi/linux/types.h>
202
Andrey Ryabinind9764412015-10-19 11:37:17 +0300203#define __READ_ONCE_SIZE \
204({ \
205 switch (size) { \
206 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
207 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
208 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
209 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
210 default: \
211 barrier(); \
212 __builtin_memcpy((void *)res, (const void *)p, size); \
213 barrier(); \
214 } \
215})
216
217static __always_inline
218void __read_once_size(const volatile void *p, void *res, int size)
Christian Borntraeger230fa252014-11-25 10:01:16 +0100219{
Andrey Ryabinind9764412015-10-19 11:37:17 +0300220 __READ_ONCE_SIZE;
Christian Borntraeger230fa252014-11-25 10:01:16 +0100221}
222
Andrey Ryabinind9764412015-10-19 11:37:17 +0300223#ifdef CONFIG_KASAN
224/*
225 * This function is not 'inline' because __no_sanitize_address confilcts
226 * with inlining. Attempt to inline it may cause a build failure.
227 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
228 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
229 */
230static __no_sanitize_address __maybe_unused
231void __read_once_size_nocheck(const volatile void *p, void *res, int size)
232{
233 __READ_ONCE_SIZE;
234}
235#else
236static __always_inline
237void __read_once_size_nocheck(const volatile void *p, void *res, int size)
238{
239 __READ_ONCE_SIZE;
240}
241#endif
242
Christian Borntraeger43239cb2015-01-13 10:46:42 +0100243static __always_inline void __write_once_size(volatile void *p, void *res, int size)
Christian Borntraeger230fa252014-11-25 10:01:16 +0100244{
245 switch (size) {
246 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
247 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
248 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
Christian Borntraeger230fa252014-11-25 10:01:16 +0100249 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
Christian Borntraeger230fa252014-11-25 10:01:16 +0100250 default:
251 barrier();
252 __builtin_memcpy((void *)p, (const void *)res, size);
Christian Borntraeger230fa252014-11-25 10:01:16 +0100253 barrier();
254 }
255}
256
257/*
258 * Prevent the compiler from merging or refetching reads or writes. The
259 * compiler is also forbidden from reordering successive instances of
Christian Borntraeger43239cb2015-01-13 10:46:42 +0100260 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
Christian Borntraeger230fa252014-11-25 10:01:16 +0100261 * compiler is aware of some particular ordering. One way to make the
262 * compiler aware of ordering is to put the two invocations of READ_ONCE,
Christian Borntraeger43239cb2015-01-13 10:46:42 +0100263 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
Christian Borntraeger230fa252014-11-25 10:01:16 +0100264 *
265 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
266 * data types like structs or unions. If the size of the accessed data
267 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
Konrad Rzeszutek Wilkfed07642016-01-25 16:33:20 -0500268 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at
269 * least two memcpy()s: one for the __builtin_memcpy() and then one for
270 * the macro doing the copy of variable - '__u' allocated on the stack.
Christian Borntraeger230fa252014-11-25 10:01:16 +0100271 *
272 * Their two major use cases are: (1) Mediating communication between
273 * process-level code and irq/NMI handlers, all running on the same CPU,
274 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
275 * mutilate accesses that either do not require ordering or that interact
276 * with an explicit memory barrier or atomic instruction that provides the
277 * required ordering.
278 */
279
Andrey Ryabinind9764412015-10-19 11:37:17 +0300280#define __READ_ONCE(x, check) \
281({ \
282 union { typeof(x) __val; char __c[1]; } __u; \
283 if (check) \
284 __read_once_size(&(x), __u.__c, sizeof(x)); \
285 else \
286 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
287 __u.__val; \
288})
289#define READ_ONCE(x) __READ_ONCE(x, 1)
290
291/*
292 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
293 * to hide memory access from KASAN.
294 */
295#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
Christian Borntraeger230fa252014-11-25 10:01:16 +0100296
Christian Borntraeger43239cb2015-01-13 10:46:42 +0100297#define WRITE_ONCE(x, val) \
Christian Borntraegerba330342015-08-04 09:55:48 +0200298({ \
299 union { typeof(x) __val; char __c[1]; } __u = \
300 { .__val = (__force typeof(x)) (val) }; \
301 __write_once_size(&(x), __u.__c, sizeof(x)); \
302 __u.__val; \
303})
Christian Borntraeger230fa252014-11-25 10:01:16 +0100304
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305#endif /* __KERNEL__ */
306
307#endif /* __ASSEMBLY__ */
308
David Woodhouse4f79c3f2006-05-02 10:41:25 +0100309#ifdef __KERNEL__
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310/*
311 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
312 * warning for each use, in hopes of speeding the functions removal.
313 * Usage is:
314 * int __deprecated foo(void)
315 */
316#ifndef __deprecated
317# define __deprecated /* unimplemented */
318#endif
319
Paul E. McKenney512345b2005-05-01 08:59:03 -0700320#ifdef MODULE
321#define __deprecated_for_modules __deprecated
322#else
323#define __deprecated_for_modules
324#endif
325
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326#ifndef __must_check
327#define __must_check
328#endif
329
Andrew Mortoncebc04b2006-08-14 22:43:18 -0700330#ifndef CONFIG_ENABLE_MUST_CHECK
331#undef __must_check
332#define __must_check
333#endif
Jeff Garzikde488442007-10-25 04:06:13 -0400334#ifndef CONFIG_ENABLE_WARN_DEPRECATED
335#undef __deprecated
336#undef __deprecated_for_modules
337#define __deprecated
338#define __deprecated_for_modules
339#endif
Andrew Mortoncebc04b2006-08-14 22:43:18 -0700340
Rasmus Villemoesd64e85d2016-05-19 17:10:52 -0700341#ifndef __malloc
342#define __malloc
343#endif
344
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345/*
346 * Allow us to avoid 'defined but not used' warnings on functions and data,
347 * as well as force them to be emitted to the assembly file.
348 *
David Rientjes0d7ebbb2007-05-09 02:35:27 -0700349 * As of gcc 3.4, static functions that are not marked with attribute((used))
350 * may be elided from the assembly file. As of gcc 3.4, static data not so
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 * marked will not be elided, but this may change in a future gcc version.
352 *
David Rientjes0d7ebbb2007-05-09 02:35:27 -0700353 * NOTE: Because distributions shipped with a backported unit-at-a-time
354 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
355 * for gcc >=3.3 instead of 3.4.
356 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 * In prior versions of gcc, such functions and data would be emitted, but
358 * would be warned about except with attribute((unused)).
David Rientjes0d7ebbb2007-05-09 02:35:27 -0700359 *
360 * Mark functions that are referenced only in inline assembly as __used so
361 * the code is emitted even though it appears to be unreferenced.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 */
David Rientjes0d7ebbb2007-05-09 02:35:27 -0700363#ifndef __used
364# define __used /* unimplemented */
365#endif
366
367#ifndef __maybe_unused
368# define __maybe_unused /* unimplemented */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369#endif
370
Li Zefan7b2a3512009-11-02 08:50:52 +0800371#ifndef __always_unused
372# define __always_unused /* unimplemented */
373#endif
374
David Woodhouse423bc7b2006-05-04 00:41:02 +0100375#ifndef noinline
376#define noinline
377#endif
378
Andrew Morton735c4fb2008-03-04 14:28:40 -0800379/*
380 * Rather then using noinline to prevent stack consumption, use
Alexander Steine6be0c92012-02-23 13:42:30 +0100381 * noinline_for_stack instead. For documentation reasons.
Andrew Morton735c4fb2008-03-04 14:28:40 -0800382 */
383#define noinline_for_stack noinline
384
David Woodhouse423bc7b2006-05-04 00:41:02 +0100385#ifndef __always_inline
386#define __always_inline inline
387#endif
388
389#endif /* __KERNEL__ */
390
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391/*
392 * From the GCC manual:
393 *
394 * Many functions do not examine any values except their arguments,
395 * and have no effects except the return value. Basically this is
396 * just slightly more strict class than the `pure' attribute above,
397 * since function is not allowed to read global memory.
398 *
399 * Note that a function that has pointer arguments and examines the
400 * data pointed to must _not_ be declared `const'. Likewise, a
401 * function that calls a non-`const' function usually must not be
402 * `const'. It does not make sense for a `const' function to return
403 * `void'.
404 */
405#ifndef __attribute_const__
406# define __attribute_const__ /* unimplemented */
407#endif
408
Andi Kleena586df02007-07-21 17:10:00 +0200409/*
410 * Tell gcc if a function is cold. The compiler will assume any path
411 * directly leading to the call is unlikely.
412 */
413
414#ifndef __cold
415#define __cold
416#endif
417
Sam Ravnborgf3fe8662008-01-20 18:54:48 +0100418/* Simple shorthand for a section definition */
419#ifndef __section
420# define __section(S) __attribute__ ((__section__(#S)))
421#endif
422
Andi Kleen9a858dc2012-09-17 14:09:15 -0700423#ifndef __visible
424#define __visible
425#endif
426
Rasmus Villemoesa744fd12015-11-05 18:45:02 -0800427/*
428 * Assume alignment of return value.
429 */
430#ifndef __assume_aligned
431#define __assume_aligned(a, ...)
432#endif
433
434
Rusty Russelld2c123c2009-06-12 21:46:56 -0600435/* Are two types/vars the same type (ignoring qualifiers)? */
436#ifndef __same_type
437# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
438#endif
439
Peter Zijlstra47933ad2013-11-06 14:57:36 +0100440/* Is this type a native word size -- useful for atomic operations */
441#ifndef __native_word
Paul E. McKenney536fa402014-09-05 11:14:48 -0700442# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
Peter Zijlstra47933ad2013-11-06 14:57:36 +0100443#endif
444
Arjan van de Ven9f0cf4a2009-09-26 14:33:01 +0200445/* Compile time object size, -1 for unknown */
446#ifndef __compiletime_object_size
447# define __compiletime_object_size(obj) -1
448#endif
Arjan van de Ven4a312762009-09-30 13:05:23 +0200449#ifndef __compiletime_warning
450# define __compiletime_warning(message)
451#endif
Arjan van de Ven63312b62009-10-02 07:50:50 -0700452#ifndef __compiletime_error
453# define __compiletime_error(message)
James Hogan2c0d2592014-06-04 16:11:16 -0700454/*
455 * Sparse complains of variable sized arrays due to the temporary variable in
456 * __compiletime_assert. Unfortunately we can't just expand it out to make
457 * sparse see a constant array size without breaking compiletime_assert on old
458 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
459 */
460# ifndef __CHECKER__
461# define __compiletime_error_fallback(condition) \
Daniel Santos9a8ab1c2013-02-21 16:41:55 -0800462 do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
James Hogan2c0d2592014-06-04 16:11:16 -0700463# endif
464#endif
465#ifndef __compiletime_error_fallback
Daniel Santosc361d3e2013-02-21 16:41:54 -0800466# define __compiletime_error_fallback(condition) do { } while (0)
Arjan van de Ven63312b62009-10-02 07:50:50 -0700467#endif
Daniel Santosc361d3e2013-02-21 16:41:54 -0800468
Daniel Santos9a8ab1c2013-02-21 16:41:55 -0800469#define __compiletime_assert(condition, msg, prefix, suffix) \
470 do { \
471 bool __cond = !(condition); \
472 extern void prefix ## suffix(void) __compiletime_error(msg); \
473 if (__cond) \
474 prefix ## suffix(); \
475 __compiletime_error_fallback(__cond); \
476 } while (0)
477
478#define _compiletime_assert(condition, msg, prefix, suffix) \
479 __compiletime_assert(condition, msg, prefix, suffix)
480
481/**
482 * compiletime_assert - break build and emit msg if condition is false
483 * @condition: a compile-time constant condition to check
484 * @msg: a message to emit if condition is false
485 *
486 * In tradition of POSIX assert, this macro will break the build if the
487 * supplied condition is *false*, emitting the supplied error message if the
488 * compiler has support to do so.
489 */
490#define compiletime_assert(condition, msg) \
491 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
492
Peter Zijlstra47933ad2013-11-06 14:57:36 +0100493#define compiletime_assert_atomic_type(t) \
494 compiletime_assert(__native_word(t), \
495 "Need native word sized stores/loads for atomicity.")
496
Linus Torvalds9c3cdc12008-05-10 19:51:16 -0700497/*
498 * Prevent the compiler from merging or refetching accesses. The compiler
499 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
500 * but only when the compiler is aware of some particular ordering. One way
501 * to make the compiler aware of ordering is to put the two invocations of
502 * ACCESS_ONCE() in different C statements.
503 *
Christian Borntraeger927609d2014-11-25 10:16:39 +0100504 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
505 * on a union member will work as long as the size of the member matches the
506 * size of the union and the size is smaller than word size.
507 *
508 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
509 * between process-level code and irq/NMI handlers, all running on the same CPU,
510 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
511 * mutilate accesses that either do not require ordering or that interact
512 * with an explicit memory barrier or atomic instruction that provides the
513 * required ordering.
514 *
Preeti U Murthy663fdcb2015-04-30 17:27:21 +0530515 * If possible use READ_ONCE()/WRITE_ONCE() instead.
Linus Torvalds9c3cdc12008-05-10 19:51:16 -0700516 */
Christian Borntraeger927609d2014-11-25 10:16:39 +0100517#define __ACCESS_ONCE(x) ({ \
Christian Borntraegerc5b19942015-01-12 12:13:39 +0100518 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
Christian Borntraeger927609d2014-11-25 10:16:39 +0100519 (volatile typeof(x) *)&(x); })
520#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
Linus Torvalds9c3cdc12008-05-10 19:51:16 -0700521
Peter Zijlstra0a04b012015-05-27 11:09:36 +0930522/**
523 * lockless_dereference() - safely load a pointer for later dereference
524 * @p: The pointer to load
525 *
526 * Similar to rcu_dereference(), but for situations where the pointed-to
527 * object's lifetime is managed by something other than RCU. That
528 * "something other" might be reference counting or simple immortality.
Peter Zijlstra331b6d82016-05-22 12:48:27 +0200529 *
Johannes Bergd7127b52016-08-26 08:16:00 +0200530 * The seemingly unused variable ___typecheck_p validates that @p is
531 * indeed a pointer type by using a pointer to typeof(*p) as the type.
532 * Taking a pointer to typeof(*p) again is needed in case p is void *.
Peter Zijlstra0a04b012015-05-27 11:09:36 +0930533 */
534#define lockless_dereference(p) \
535({ \
Stephen Rothwell38183b92015-05-28 17:20:58 +1000536 typeof(p) _________p1 = READ_ONCE(p); \
Johannes Bergd7127b52016-08-26 08:16:00 +0200537 typeof(*(p)) *___typecheck_p __maybe_unused; \
Peter Zijlstra0a04b012015-05-27 11:09:36 +0930538 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
539 (_________p1); \
540})
541
Masami Hiramatsu324670b2013-04-04 19:40:50 +0900542/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
543#ifdef CONFIG_KPROBES
544# define __kprobes __attribute__((__section__(".kprobes.text")))
Masami Hiramatsu376e2422014-04-17 17:17:05 +0900545# define nokprobe_inline __always_inline
Masami Hiramatsu324670b2013-04-04 19:40:50 +0900546#else
547# define __kprobes
Masami Hiramatsu376e2422014-04-17 17:17:05 +0900548# define nokprobe_inline inline
Masami Hiramatsu324670b2013-04-04 19:40:50 +0900549#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550#endif /* __LINUX_COMPILER_H */