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94f582f8 RD |
1 | #ifndef __LINUX_COMPILER_H |
2 | #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." | |
3 | #endif | |
1da177e4 LT |
4 | |
5 | /* | |
6 | * Common definitions for all gcc versions go here. | |
7 | */ | |
f6d133f8 JP |
8 | #define GCC_VERSION (__GNUC__ * 10000 \ |
9 | + __GNUC_MINOR__ * 100 \ | |
10 | + __GNUC_PATCHLEVEL__) | |
1da177e4 | 11 | |
1da177e4 | 12 | /* Optimization barrier */ |
7829fb09 | 13 | |
1da177e4 LT |
14 | /* The "volatile" is due to gcc bugs */ |
15 | #define barrier() __asm__ __volatile__("": : :"memory") | |
7829fb09 DB |
16 | /* |
17 | * This version is i.e. to prevent dead stores elimination on @ptr | |
18 | * where gcc and llvm may behave differently when otherwise using | |
19 | * normal barrier(): while gcc behavior gets along with a normal | |
20 | * barrier(), llvm needs an explicit input variable to be assumed | |
21 | * clobbered. The issue is as follows: while the inline asm might | |
22 | * access any memory it wants, the compiler could have fit all of | |
23 | * @ptr into memory registers instead, and since @ptr never escaped | |
24 | * from that, it proofed that the inline asm wasn't touching any of | |
25 | * it. This version works well with both compilers, i.e. we're telling | |
26 | * the compiler that the inline asm absolutely may see the contents | |
27 | * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 | |
28 | */ | |
29 | #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") | |
1da177e4 | 30 | |
c8d52465 | 31 | /* |
85c210ed AK |
32 | * This macro obfuscates arithmetic on a variable address so that gcc |
33 | * shouldn't recognize the original var, and make assumptions about it. | |
34 | * | |
35 | * This is needed because the C standard makes it undefined to do | |
36 | * pointer arithmetic on "objects" outside their boundaries and the | |
37 | * gcc optimizers assume this is the case. In particular they | |
38 | * assume such arithmetic does not wrap. | |
39 | * | |
40 | * A miscompilation has been observed because of this on PPC. | |
41 | * To work around it we hide the relationship of the pointer and the object | |
42 | * using this macro. | |
43 | * | |
c8d52465 AB |
44 | * Versions of the ppc64 compiler before 4.1 had a bug where use of |
45 | * RELOC_HIDE could trash r30. The bug can be worked around by changing | |
46 | * the inline assembly constraint from =g to =r, in this particular | |
47 | * case either is valid. | |
48 | */ | |
f6d133f8 JP |
49 | #define RELOC_HIDE(ptr, off) \ |
50 | ({ \ | |
51 | unsigned long __ptr; \ | |
52 | __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ | |
53 | (typeof(ptr)) (__ptr + (off)); \ | |
54 | }) | |
a1365647 | 55 | |
fe8c8a12 | 56 | /* Make the optimizer believe the variable can be manipulated arbitrarily. */ |
f6d133f8 JP |
57 | #define OPTIMIZER_HIDE_VAR(var) \ |
58 | __asm__ ("" : "=r" (var) : "0" (var)) | |
fe8c8a12 | 59 | |
5bd7e6a3 | 60 | #ifdef __CHECKER__ |
f6d133f8 | 61 | #define __must_be_array(a) 0 |
5bd7e6a3 | 62 | #else |
c5e631cf | 63 | /* &a[0] degrades to a pointer: a different type from an array */ |
f6d133f8 | 64 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) |
5bd7e6a3 | 65 | #endif |
a1365647 | 66 | |
60a3cdd0 | 67 | /* |
ae3a0064 IM |
68 | * Force always-inline if the user requests it so via the .config, |
69 | * or if gcc is too old: | |
60a3cdd0 | 70 | */ |
f6d133f8 | 71 | #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ |
ae3a0064 | 72 | !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) |
f6d133f8 JP |
73 | #define inline inline __attribute__((always_inline)) notrace |
74 | #define __inline__ __inline__ __attribute__((always_inline)) notrace | |
75 | #define __inline __inline __attribute__((always_inline)) notrace | |
45959ee7 SR |
76 | #else |
77 | /* A lot of inline functions can cause havoc with function tracing */ | |
f6d133f8 JP |
78 | #define inline inline notrace |
79 | #define __inline__ __inline__ notrace | |
80 | #define __inline __inline notrace | |
60a3cdd0 IM |
81 | #endif |
82 | ||
f6d133f8 JP |
83 | #define __always_inline inline __attribute__((always_inline)) |
84 | #define noinline __attribute__((noinline)) | |
85 | ||
86 | #define __deprecated __attribute__((deprecated)) | |
87 | #define __packed __attribute__((packed)) | |
88 | #define __weak __attribute__((weak)) | |
89 | #define __alias(symbol) __attribute__((alias(#symbol))) | |
446c92b2 UKK |
90 | |
91 | /* | |
f6d133f8 JP |
92 | * it doesn't make sense on ARM (currently the only user of __naked) |
93 | * to trace naked functions because then mcount is called without | |
94 | * stack and frame pointer being set up and there is no chance to | |
95 | * restore the lr register to the value before mcount was called. | |
96 | * | |
97 | * The asm() bodies of naked functions often depend on standard calling | |
98 | * conventions, therefore they must be noinline and noclone. | |
9c695203 | 99 | * |
f6d133f8 JP |
100 | * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. |
101 | * See GCC PR44290. | |
446c92b2 | 102 | */ |
f6d133f8 | 103 | #define __naked __attribute__((naked)) noinline __noclone notrace |
446c92b2 | 104 | |
f6d133f8 | 105 | #define __noreturn __attribute__((noreturn)) |
e8c44319 RB |
106 | |
107 | /* | |
108 | * From the GCC manual: | |
109 | * | |
110 | * Many functions have no effects except the return value and their | |
111 | * return value depends only on the parameters and/or global | |
112 | * variables. Such a function can be subject to common subexpression | |
113 | * elimination and loop optimization just as an arithmetic operator | |
114 | * would be. | |
115 | * [...] | |
116 | */ | |
f6d133f8 JP |
117 | #define __pure __attribute__((pure)) |
118 | #define __aligned(x) __attribute__((aligned(x))) | |
119 | #define __printf(a, b) __attribute__((format(printf, a, b))) | |
120 | #define __scanf(a, b) __attribute__((format(scanf, a, b))) | |
121 | #define __attribute_const__ __attribute__((__const__)) | |
122 | #define __maybe_unused __attribute__((unused)) | |
123 | #define __always_unused __attribute__((unused)) | |
f153b821 | 124 | |
cb984d10 JP |
125 | /* gcc version specific checks */ |
126 | ||
127 | #if GCC_VERSION < 30200 | |
128 | # error Sorry, your compiler is too old - please upgrade it. | |
129 | #endif | |
130 | ||
131 | #if GCC_VERSION < 30300 | |
132 | # define __used __attribute__((__unused__)) | |
133 | #else | |
134 | # define __used __attribute__((__used__)) | |
135 | #endif | |
136 | ||
137 | #ifdef CONFIG_GCOV_KERNEL | |
138 | # if GCC_VERSION < 30400 | |
139 | # error "GCOV profiling support for gcc versions below 3.4 not included" | |
140 | # endif /* __GNUC_MINOR__ */ | |
141 | #endif /* CONFIG_GCOV_KERNEL */ | |
142 | ||
143 | #if GCC_VERSION >= 30400 | |
144 | #define __must_check __attribute__((warn_unused_result)) | |
d64e85d3 | 145 | #define __malloc __attribute__((__malloc__)) |
cb984d10 JP |
146 | #endif |
147 | ||
148 | #if GCC_VERSION >= 40000 | |
149 | ||
150 | /* GCC 4.1.[01] miscompiles __weak */ | |
151 | #ifdef __KERNEL__ | |
152 | # if GCC_VERSION >= 40100 && GCC_VERSION <= 40101 | |
153 | # error Your version of gcc miscompiles the __weak directive | |
154 | # endif | |
155 | #endif | |
156 | ||
157 | #define __used __attribute__((__used__)) | |
158 | #define __compiler_offsetof(a, b) \ | |
159 | __builtin_offsetof(a, b) | |
160 | ||
161 | #if GCC_VERSION >= 40100 && GCC_VERSION < 40600 | |
162 | # define __compiletime_object_size(obj) __builtin_object_size(obj, 0) | |
163 | #endif | |
164 | ||
165 | #if GCC_VERSION >= 40300 | |
166 | /* Mark functions as cold. gcc will assume any path leading to a call | |
167 | * to them will be unlikely. This means a lot of manual unlikely()s | |
168 | * are unnecessary now for any paths leading to the usual suspects | |
169 | * like BUG(), printk(), panic() etc. [but let's keep them for now for | |
170 | * older compilers] | |
171 | * | |
172 | * Early snapshots of gcc 4.3 don't support this and we can't detect this | |
173 | * in the preprocessor, but we can live with this because they're unreleased. | |
174 | * Maketime probing would be overkill here. | |
175 | * | |
176 | * gcc also has a __attribute__((__hot__)) to move hot functions into | |
177 | * a special section, but I don't see any sense in this right now in | |
178 | * the kernel context | |
179 | */ | |
180 | #define __cold __attribute__((__cold__)) | |
181 | ||
182 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) | |
183 | ||
184 | #ifndef __CHECKER__ | |
185 | # define __compiletime_warning(message) __attribute__((warning(message))) | |
186 | # define __compiletime_error(message) __attribute__((error(message))) | |
187 | #endif /* __CHECKER__ */ | |
188 | #endif /* GCC_VERSION >= 40300 */ | |
189 | ||
190 | #if GCC_VERSION >= 40500 | |
191 | /* | |
192 | * Mark a position in code as unreachable. This can be used to | |
193 | * suppress control flow warnings after asm blocks that transfer | |
194 | * control elsewhere. | |
195 | * | |
196 | * Early snapshots of gcc 4.5 don't support this and we can't detect | |
197 | * this in the preprocessor, but we can live with this because they're | |
198 | * unreleased. Really, we need to have autoconf for the kernel. | |
199 | */ | |
200 | #define unreachable() __builtin_unreachable() | |
201 | ||
202 | /* Mark a function definition as prohibited from being cloned. */ | |
95272c29 | 203 | #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) |
cb984d10 JP |
204 | |
205 | #endif /* GCC_VERSION >= 40500 */ | |
206 | ||
207 | #if GCC_VERSION >= 40600 | |
208 | /* | |
9add850c AM |
209 | * When used with Link Time Optimization, gcc can optimize away C functions or |
210 | * variables which are referenced only from assembly code. __visible tells the | |
211 | * optimizer that something else uses this function or variable, thus preventing | |
212 | * this. | |
cb984d10 JP |
213 | */ |
214 | #define __visible __attribute__((externally_visible)) | |
215 | #endif | |
216 | ||
a744fd17 | 217 | |
8748dd5c | 218 | #if GCC_VERSION >= 40900 && !defined(__CHECKER__) |
a744fd17 RV |
219 | /* |
220 | * __assume_aligned(n, k): Tell the optimizer that the returned | |
221 | * pointer can be assumed to be k modulo n. The second argument is | |
222 | * optional (default 0), so we use a variadic macro to make the | |
223 | * shorthand. | |
224 | * | |
225 | * Beware: Do not apply this to functions which may return | |
226 | * ERR_PTRs. Also, it is probably unwise to apply it to functions | |
227 | * returning extra information in the low bits (but in that case the | |
228 | * compiler should see some alignment anyway, when the return value is | |
229 | * massaged by 'flags = ptr & 3; ptr &= ~3;'). | |
230 | */ | |
231 | #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) | |
232 | #endif | |
233 | ||
cb984d10 JP |
234 | /* |
235 | * GCC 'asm goto' miscompiles certain code sequences: | |
236 | * | |
237 | * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 | |
238 | * | |
239 | * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. | |
240 | * | |
241 | * (asm goto is automatically volatile - the naming reflects this.) | |
242 | */ | |
243 | #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) | |
244 | ||
245 | #ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP | |
246 | #if GCC_VERSION >= 40400 | |
247 | #define __HAVE_BUILTIN_BSWAP32__ | |
248 | #define __HAVE_BUILTIN_BSWAP64__ | |
249 | #endif | |
8634de6d | 250 | #if GCC_VERSION >= 40800 |
cb984d10 JP |
251 | #define __HAVE_BUILTIN_BSWAP16__ |
252 | #endif | |
253 | #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */ | |
254 | ||
255 | #if GCC_VERSION >= 50000 | |
256 | #define KASAN_ABI_VERSION 4 | |
257 | #elif GCC_VERSION >= 40902 | |
258 | #define KASAN_ABI_VERSION 3 | |
259 | #endif | |
260 | ||
d976441f AR |
261 | #if GCC_VERSION >= 40902 |
262 | /* | |
263 | * Tell the compiler that address safety instrumentation (KASAN) | |
264 | * should not be applied to that function. | |
265 | * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 | |
266 | */ | |
267 | #define __no_sanitize_address __attribute__((no_sanitize_address)) | |
268 | #endif | |
269 | ||
cb984d10 | 270 | #endif /* gcc version >= 40000 specific checks */ |
9c695203 MP |
271 | |
272 | #if !defined(__noclone) | |
273 | #define __noclone /* not needed */ | |
274 | #endif | |
c837fb37 | 275 | |
d976441f AR |
276 | #if !defined(__no_sanitize_address) |
277 | #define __no_sanitize_address | |
278 | #endif | |
279 | ||
c837fb37 BP |
280 | /* |
281 | * A trick to suppress uninitialized variable warning without generating any | |
282 | * code | |
283 | */ | |
284 | #define uninitialized_var(x) x = x |