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1 | /* SPDX-License-Identifier: GPL-2.0 */ | |
2 | #ifndef __LINUX_COMPILER_TYPES_H | |
3 | #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." | |
4 | #endif | |
5 | ||
6 | /* | |
7 | * Common definitions for all gcc versions go here. | |
8 | */ | |
9 | #define GCC_VERSION (__GNUC__ * 10000 \ | |
10 | + __GNUC_MINOR__ * 100 \ | |
11 | + __GNUC_PATCHLEVEL__) | |
12 | ||
13 | /* Optimization barrier */ | |
14 | ||
15 | /* The "volatile" is due to gcc bugs */ | |
16 | #define barrier() __asm__ __volatile__("": : :"memory") | |
17 | /* | |
18 | * This version is i.e. to prevent dead stores elimination on @ptr | |
19 | * where gcc and llvm may behave differently when otherwise using | |
20 | * normal barrier(): while gcc behavior gets along with a normal | |
21 | * barrier(), llvm needs an explicit input variable to be assumed | |
22 | * clobbered. The issue is as follows: while the inline asm might | |
23 | * access any memory it wants, the compiler could have fit all of | |
24 | * @ptr into memory registers instead, and since @ptr never escaped | |
25 | * from that, it proved that the inline asm wasn't touching any of | |
26 | * it. This version works well with both compilers, i.e. we're telling | |
27 | * the compiler that the inline asm absolutely may see the contents | |
28 | * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 | |
29 | */ | |
30 | #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") | |
31 | ||
32 | /* | |
33 | * This macro obfuscates arithmetic on a variable address so that gcc | |
34 | * shouldn't recognize the original var, and make assumptions about it. | |
35 | * | |
36 | * This is needed because the C standard makes it undefined to do | |
37 | * pointer arithmetic on "objects" outside their boundaries and the | |
38 | * gcc optimizers assume this is the case. In particular they | |
39 | * assume such arithmetic does not wrap. | |
40 | * | |
41 | * A miscompilation has been observed because of this on PPC. | |
42 | * To work around it we hide the relationship of the pointer and the object | |
43 | * using this macro. | |
44 | * | |
45 | * Versions of the ppc64 compiler before 4.1 had a bug where use of | |
46 | * RELOC_HIDE could trash r30. The bug can be worked around by changing | |
47 | * the inline assembly constraint from =g to =r, in this particular | |
48 | * case either is valid. | |
49 | */ | |
50 | #define RELOC_HIDE(ptr, off) \ | |
51 | ({ \ | |
52 | unsigned long __ptr; \ | |
53 | __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ | |
54 | (typeof(ptr)) (__ptr + (off)); \ | |
55 | }) | |
56 | ||
57 | /* Make the optimizer believe the variable can be manipulated arbitrarily. */ | |
58 | #define OPTIMIZER_HIDE_VAR(var) \ | |
59 | __asm__ ("" : "=r" (var) : "0" (var)) | |
60 | ||
61 | #ifdef __CHECKER__ | |
62 | #define __must_be_array(a) 0 | |
63 | #else | |
64 | /* &a[0] degrades to a pointer: a different type from an array */ | |
65 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) | |
66 | #endif | |
67 | ||
68 | /* | |
69 | * Feature detection for gnu_inline (gnu89 extern inline semantics). Either | |
70 | * __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics, | |
71 | * and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not | |
72 | * defined so the gnu89 semantics are the default. | |
73 | */ | |
74 | #ifdef __GNUC_STDC_INLINE__ | |
75 | # define __gnu_inline __attribute__((gnu_inline)) | |
76 | #else | |
77 | # define __gnu_inline | |
78 | #endif | |
79 | ||
80 | /* | |
81 | * Force always-inline if the user requests it so via the .config, | |
82 | * or if gcc is too old. | |
83 | * GCC does not warn about unused static inline functions for | |
84 | * -Wunused-function. This turns out to avoid the need for complex #ifdef | |
85 | * directives. Suppress the warning in clang as well by using "unused" | |
86 | * function attribute, which is redundant but not harmful for gcc. | |
87 | * Prefer gnu_inline, so that extern inline functions do not emit an | |
88 | * externally visible function. This makes extern inline behave as per gnu89 | |
89 | * semantics rather than c99. This prevents multiple symbol definition errors | |
90 | * of extern inline functions at link time. | |
91 | * A lot of inline functions can cause havoc with function tracing. | |
92 | */ | |
93 | #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ | |
94 | !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) | |
95 | #define inline \ | |
96 | inline __attribute__((always_inline, unused)) notrace __gnu_inline | |
97 | #else | |
98 | #define inline inline __attribute__((unused)) notrace __gnu_inline | |
99 | #endif | |
100 | ||
101 | #define __inline__ inline | |
102 | #define __inline inline | |
103 | #define __always_inline inline __attribute__((always_inline)) | |
104 | #define noinline __attribute__((noinline)) | |
105 | ||
106 | #define __deprecated __attribute__((deprecated)) | |
107 | #define __packed __attribute__((packed)) | |
108 | #define __weak __attribute__((weak)) | |
109 | #define __alias(symbol) __attribute__((alias(#symbol))) | |
110 | ||
111 | #ifdef CONFIG_RETPOLINE | |
112 | #define __noretpoline __attribute__((indirect_branch("keep"))) | |
113 | #endif | |
114 | ||
115 | /* | |
116 | * it doesn't make sense on ARM (currently the only user of __naked) | |
117 | * to trace naked functions because then mcount is called without | |
118 | * stack and frame pointer being set up and there is no chance to | |
119 | * restore the lr register to the value before mcount was called. | |
120 | * | |
121 | * The asm() bodies of naked functions often depend on standard calling | |
122 | * conventions, therefore they must be noinline and noclone. | |
123 | * | |
124 | * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. | |
125 | * See GCC PR44290. | |
126 | */ | |
127 | #define __naked __attribute__((naked)) noinline __noclone notrace | |
128 | ||
129 | #define __noreturn __attribute__((noreturn)) | |
130 | ||
131 | /* | |
132 | * From the GCC manual: | |
133 | * | |
134 | * Many functions have no effects except the return value and their | |
135 | * return value depends only on the parameters and/or global | |
136 | * variables. Such a function can be subject to common subexpression | |
137 | * elimination and loop optimization just as an arithmetic operator | |
138 | * would be. | |
139 | * [...] | |
140 | */ | |
141 | #define __pure __attribute__((pure)) | |
142 | #define __aligned(x) __attribute__((aligned(x))) | |
143 | #define __aligned_largest __attribute__((aligned)) | |
144 | #define __printf(a, b) __attribute__((format(printf, a, b))) | |
145 | #define __scanf(a, b) __attribute__((format(scanf, a, b))) | |
146 | #define __attribute_const__ __attribute__((__const__)) | |
147 | #define __maybe_unused __attribute__((unused)) | |
148 | #define __always_unused __attribute__((unused)) | |
149 | #define __mode(x) __attribute__((mode(x))) | |
150 | ||
151 | /* gcc version specific checks */ | |
152 | ||
153 | #if GCC_VERSION < 30200 | |
154 | # error Sorry, your compiler is too old - please upgrade it. | |
155 | #endif | |
156 | ||
157 | #if GCC_VERSION < 30300 | |
158 | # define __used __attribute__((__unused__)) | |
159 | #else | |
160 | # define __used __attribute__((__used__)) | |
161 | #endif | |
162 | ||
163 | #ifdef CONFIG_GCOV_KERNEL | |
164 | # if GCC_VERSION < 30400 | |
165 | # error "GCOV profiling support for gcc versions below 3.4 not included" | |
166 | # endif /* __GNUC_MINOR__ */ | |
167 | #endif /* CONFIG_GCOV_KERNEL */ | |
168 | ||
169 | #if GCC_VERSION >= 30400 | |
170 | #define __must_check __attribute__((warn_unused_result)) | |
171 | #define __malloc __attribute__((__malloc__)) | |
172 | #endif | |
173 | ||
174 | #if GCC_VERSION >= 40000 | |
175 | ||
176 | /* GCC 4.1.[01] miscompiles __weak */ | |
177 | #ifdef __KERNEL__ | |
178 | # if GCC_VERSION >= 40100 && GCC_VERSION <= 40101 | |
179 | # error Your version of gcc miscompiles the __weak directive | |
180 | # endif | |
181 | #endif | |
182 | ||
183 | #define __used __attribute__((__used__)) | |
184 | #define __compiler_offsetof(a, b) \ | |
185 | __builtin_offsetof(a, b) | |
186 | ||
187 | #if GCC_VERSION >= 40100 | |
188 | # define __compiletime_object_size(obj) __builtin_object_size(obj, 0) | |
189 | #endif | |
190 | ||
191 | #if GCC_VERSION >= 40300 | |
192 | /* Mark functions as cold. gcc will assume any path leading to a call | |
193 | * to them will be unlikely. This means a lot of manual unlikely()s | |
194 | * are unnecessary now for any paths leading to the usual suspects | |
195 | * like BUG(), printk(), panic() etc. [but let's keep them for now for | |
196 | * older compilers] | |
197 | * | |
198 | * Early snapshots of gcc 4.3 don't support this and we can't detect this | |
199 | * in the preprocessor, but we can live with this because they're unreleased. | |
200 | * Maketime probing would be overkill here. | |
201 | * | |
202 | * gcc also has a __attribute__((__hot__)) to move hot functions into | |
203 | * a special section, but I don't see any sense in this right now in | |
204 | * the kernel context | |
205 | */ | |
206 | #define __cold __attribute__((__cold__)) | |
207 | ||
208 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) | |
209 | ||
210 | #ifndef __CHECKER__ | |
211 | # define __compiletime_warning(message) __attribute__((warning(message))) | |
212 | # define __compiletime_error(message) __attribute__((error(message))) | |
213 | #endif /* __CHECKER__ */ | |
214 | #endif /* GCC_VERSION >= 40300 */ | |
215 | ||
216 | #if GCC_VERSION >= 40400 | |
217 | #define __optimize(level) __attribute__((__optimize__(level))) | |
218 | #define __nostackprotector __optimize("no-stack-protector") | |
219 | #endif /* GCC_VERSION >= 40400 */ | |
220 | ||
221 | #if GCC_VERSION >= 40500 | |
222 | ||
223 | #ifndef __CHECKER__ | |
224 | #ifdef LATENT_ENTROPY_PLUGIN | |
225 | #define __latent_entropy __attribute__((latent_entropy)) | |
226 | #endif | |
227 | #endif | |
228 | ||
229 | /* | |
230 | * calling noreturn functions, __builtin_unreachable() and __builtin_trap() | |
231 | * confuse the stack allocation in gcc, leading to overly large stack | |
232 | * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 | |
233 | * | |
234 | * Adding an empty inline assembly before it works around the problem | |
235 | */ | |
236 | #define barrier_before_unreachable() asm volatile("") | |
237 | ||
238 | /* | |
239 | * Mark a position in code as unreachable. This can be used to | |
240 | * suppress control flow warnings after asm blocks that transfer | |
241 | * control elsewhere. | |
242 | * | |
243 | * Early snapshots of gcc 4.5 don't support this and we can't detect | |
244 | * this in the preprocessor, but we can live with this because they're | |
245 | * unreleased. Really, we need to have autoconf for the kernel. | |
246 | */ | |
247 | #define unreachable() \ | |
248 | do { \ | |
249 | annotate_unreachable(); \ | |
250 | barrier_before_unreachable(); \ | |
251 | __builtin_unreachable(); \ | |
252 | } while (0) | |
253 | ||
254 | /* Mark a function definition as prohibited from being cloned. */ | |
255 | #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) | |
256 | ||
257 | #if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__) | |
258 | #define __randomize_layout __attribute__((randomize_layout)) | |
259 | #define __no_randomize_layout __attribute__((no_randomize_layout)) | |
260 | /* This anon struct can add padding, so only enable it under randstruct. */ | |
261 | #define randomized_struct_fields_start struct { | |
262 | #define randomized_struct_fields_end } __randomize_layout; | |
263 | #endif | |
264 | ||
265 | #endif /* GCC_VERSION >= 40500 */ | |
266 | ||
267 | #if GCC_VERSION >= 40600 | |
268 | ||
269 | /* | |
270 | * When used with Link Time Optimization, gcc can optimize away C functions or | |
271 | * variables which are referenced only from assembly code. __visible tells the | |
272 | * optimizer that something else uses this function or variable, thus preventing | |
273 | * this. | |
274 | */ | |
275 | #define __visible __attribute__((externally_visible)) | |
276 | ||
277 | #endif /* GCC_VERSION >= 40600 */ | |
278 | ||
279 | ||
280 | #if GCC_VERSION >= 40900 && !defined(__CHECKER__) | |
281 | /* | |
282 | * __assume_aligned(n, k): Tell the optimizer that the returned | |
283 | * pointer can be assumed to be k modulo n. The second argument is | |
284 | * optional (default 0), so we use a variadic macro to make the | |
285 | * shorthand. | |
286 | * | |
287 | * Beware: Do not apply this to functions which may return | |
288 | * ERR_PTRs. Also, it is probably unwise to apply it to functions | |
289 | * returning extra information in the low bits (but in that case the | |
290 | * compiler should see some alignment anyway, when the return value is | |
291 | * massaged by 'flags = ptr & 3; ptr &= ~3;'). | |
292 | */ | |
293 | #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) | |
294 | #endif | |
295 | ||
296 | /* | |
297 | * GCC 'asm goto' miscompiles certain code sequences: | |
298 | * | |
299 | * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 | |
300 | * | |
301 | * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. | |
302 | * | |
303 | * (asm goto is automatically volatile - the naming reflects this.) | |
304 | */ | |
305 | #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) | |
306 | ||
307 | /* | |
308 | * sparse (__CHECKER__) pretends to be gcc, but can't do constant | |
309 | * folding in __builtin_bswap*() (yet), so don't set these for it. | |
310 | */ | |
311 | #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__) | |
312 | #if GCC_VERSION >= 40400 | |
313 | #define __HAVE_BUILTIN_BSWAP32__ | |
314 | #define __HAVE_BUILTIN_BSWAP64__ | |
315 | #endif | |
316 | #if GCC_VERSION >= 40800 | |
317 | #define __HAVE_BUILTIN_BSWAP16__ | |
318 | #endif | |
319 | #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */ | |
320 | ||
321 | #if GCC_VERSION >= 70000 | |
322 | #define KASAN_ABI_VERSION 5 | |
323 | #elif GCC_VERSION >= 50000 | |
324 | #define KASAN_ABI_VERSION 4 | |
325 | #elif GCC_VERSION >= 40902 | |
326 | #define KASAN_ABI_VERSION 3 | |
327 | #endif | |
328 | ||
329 | #if GCC_VERSION >= 40902 | |
330 | /* | |
331 | * Tell the compiler that address safety instrumentation (KASAN) | |
332 | * should not be applied to that function. | |
333 | * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 | |
334 | */ | |
335 | #define __no_sanitize_address __attribute__((no_sanitize_address)) | |
336 | #endif | |
337 | ||
338 | #if GCC_VERSION >= 50100 | |
339 | /* | |
340 | * Mark structures as requiring designated initializers. | |
341 | * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html | |
342 | */ | |
343 | #define __designated_init __attribute__((designated_init)) | |
344 | #endif | |
345 | ||
346 | #if GCC_VERSION >= 90100 | |
347 | #define __copy(symbol) __attribute__((__copy__(symbol))) | |
348 | #endif | |
349 | ||
350 | #endif /* gcc version >= 40000 specific checks */ | |
351 | ||
352 | #if !defined(__noclone) | |
353 | #define __noclone /* not needed */ | |
354 | #endif | |
355 | ||
356 | #if !defined(__no_sanitize_address) | |
357 | #define __no_sanitize_address | |
358 | #endif | |
359 | ||
360 | /* | |
361 | * A trick to suppress uninitialized variable warning without generating any | |
362 | * code | |
363 | */ | |
364 | #define uninitialized_var(x) x = x | |
365 | ||
366 | #if GCC_VERSION >= 50100 | |
367 | #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 | |
368 | #endif |