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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef __LINUX_COMPILER_H |
3 | #define __LINUX_COMPILER_H | |
4 | ||
d1515582 | 5 | #include <linux/compiler_types.h> |
1da177e4 | 6 | |
d1515582 | 7 | #ifndef __ASSEMBLY__ |
6f33d587 | 8 | |
1da177e4 LT |
9 | #ifdef __KERNEL__ |
10 | ||
2ed84eeb SR |
11 | /* |
12 | * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code | |
13 | * to disable branch tracing on a per file basis. | |
14 | */ | |
d9ad8bc0 BVA |
15 | #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ |
16 | && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) | |
134e6a03 | 17 | void ftrace_likely_update(struct ftrace_likely_data *f, int val, |
d45ae1f7 | 18 | int expect, int is_constant); |
1f0d69a9 SR |
19 | |
20 | #define likely_notrace(x) __builtin_expect(!!(x), 1) | |
21 | #define unlikely_notrace(x) __builtin_expect(!!(x), 0) | |
22 | ||
d45ae1f7 | 23 | #define __branch_check__(x, expect, is_constant) ({ \ |
1f0d69a9 | 24 | int ______r; \ |
134e6a03 | 25 | static struct ftrace_likely_data \ |
1f0d69a9 | 26 | __attribute__((__aligned__(4))) \ |
45b79749 | 27 | __attribute__((section("_ftrace_annotated_branch"))) \ |
1f0d69a9 | 28 | ______f = { \ |
134e6a03 SRV |
29 | .data.func = __func__, \ |
30 | .data.file = __FILE__, \ | |
31 | .data.line = __LINE__, \ | |
1f0d69a9 | 32 | }; \ |
d45ae1f7 SRV |
33 | ______r = __builtin_expect(!!(x), expect); \ |
34 | ftrace_likely_update(&______f, ______r, \ | |
35 | expect, is_constant); \ | |
1f0d69a9 SR |
36 | ______r; \ |
37 | }) | |
38 | ||
39 | /* | |
40 | * Using __builtin_constant_p(x) to ignore cases where the return | |
41 | * value is always the same. This idea is taken from a similar patch | |
42 | * written by Daniel Walker. | |
43 | */ | |
44 | # ifndef likely | |
d45ae1f7 | 45 | # define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x))) |
1f0d69a9 SR |
46 | # endif |
47 | # ifndef unlikely | |
d45ae1f7 | 48 | # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) |
1f0d69a9 | 49 | # endif |
2bcd521a SR |
50 | |
51 | #ifdef CONFIG_PROFILE_ALL_BRANCHES | |
52 | /* | |
53 | * "Define 'is'", Bill Clinton | |
54 | * "Define 'if'", Steven Rostedt | |
55 | */ | |
ab3c9c68 LT |
56 | #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) |
57 | #define __trace_if(cond) \ | |
b33c8ff4 | 58 | if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ |
2bcd521a SR |
59 | ({ \ |
60 | int ______r; \ | |
61 | static struct ftrace_branch_data \ | |
62 | __attribute__((__aligned__(4))) \ | |
63 | __attribute__((section("_ftrace_branch"))) \ | |
64 | ______f = { \ | |
65 | .func = __func__, \ | |
66 | .file = __FILE__, \ | |
67 | .line = __LINE__, \ | |
68 | }; \ | |
69 | ______r = !!(cond); \ | |
97e7e4f3 | 70 | ______f.miss_hit[______r]++; \ |
2bcd521a SR |
71 | ______r; \ |
72 | })) | |
73 | #endif /* CONFIG_PROFILE_ALL_BRANCHES */ | |
74 | ||
1f0d69a9 SR |
75 | #else |
76 | # define likely(x) __builtin_expect(!!(x), 1) | |
77 | # define unlikely(x) __builtin_expect(!!(x), 0) | |
78 | #endif | |
1da177e4 LT |
79 | |
80 | /* Optimization barrier */ | |
81 | #ifndef barrier | |
82 | # define barrier() __memory_barrier() | |
83 | #endif | |
84 | ||
7829fb09 DB |
85 | #ifndef barrier_data |
86 | # define barrier_data(ptr) barrier() | |
87 | #endif | |
88 | ||
38938c87 | 89 | /* Unreachable code */ |
649ea4d5 | 90 | #ifdef CONFIG_STACK_VALIDATION |
d0c2e691 JP |
91 | /* |
92 | * These macros help objtool understand GCC code flow for unreachable code. | |
93 | * The __COUNTER__ based labels are a hack to make each instance of the macros | |
94 | * unique, to convince GCC not to merge duplicate inline asm statements. | |
95 | */ | |
649ea4d5 | 96 | #define annotate_reachable() ({ \ |
10259821 JP |
97 | asm volatile("%c0:\n\t" \ |
98 | ".pushsection .discard.reachable\n\t" \ | |
99 | ".long %c0b - .\n\t" \ | |
100 | ".popsection\n\t" : : "i" (__COUNTER__)); \ | |
649ea4d5 JP |
101 | }) |
102 | #define annotate_unreachable() ({ \ | |
10259821 JP |
103 | asm volatile("%c0:\n\t" \ |
104 | ".pushsection .discard.unreachable\n\t" \ | |
105 | ".long %c0b - .\n\t" \ | |
106 | ".popsection\n\t" : : "i" (__COUNTER__)); \ | |
649ea4d5 JP |
107 | }) |
108 | #define ASM_UNREACHABLE \ | |
109 | "999:\n\t" \ | |
110 | ".pushsection .discard.unreachable\n\t" \ | |
111 | ".long 999b - .\n\t" \ | |
112 | ".popsection\n\t" | |
113 | #else | |
114 | #define annotate_reachable() | |
115 | #define annotate_unreachable() | |
116 | #endif | |
117 | ||
aa5d1b81 KC |
118 | #ifndef ASM_UNREACHABLE |
119 | # define ASM_UNREACHABLE | |
120 | #endif | |
38938c87 | 121 | #ifndef unreachable |
649ea4d5 | 122 | # define unreachable() do { annotate_reachable(); do { } while (1); } while (0) |
38938c87 DD |
123 | #endif |
124 | ||
b67067f1 NP |
125 | /* |
126 | * KENTRY - kernel entry point | |
127 | * This can be used to annotate symbols (functions or data) that are used | |
128 | * without their linker symbol being referenced explicitly. For example, | |
129 | * interrupt vector handlers, or functions in the kernel image that are found | |
130 | * programatically. | |
131 | * | |
132 | * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those | |
133 | * are handled in their own way (with KEEP() in linker scripts). | |
134 | * | |
135 | * KENTRY can be avoided if the symbols in question are marked as KEEP() in the | |
136 | * linker script. For example an architecture could KEEP() its entire | |
137 | * boot/exception vector code rather than annotate each function and data. | |
138 | */ | |
139 | #ifndef KENTRY | |
140 | # define KENTRY(sym) \ | |
141 | extern typeof(sym) sym; \ | |
142 | static const unsigned long __kentry_##sym \ | |
143 | __used \ | |
144 | __attribute__((section("___kentry" "+" #sym ), used)) \ | |
145 | = (unsigned long)&sym; | |
146 | #endif | |
147 | ||
1da177e4 LT |
148 | #ifndef RELOC_HIDE |
149 | # define RELOC_HIDE(ptr, off) \ | |
150 | ({ unsigned long __ptr; \ | |
151 | __ptr = (unsigned long) (ptr); \ | |
152 | (typeof(ptr)) (__ptr + (off)); }) | |
153 | #endif | |
154 | ||
fe8c8a12 CEB |
155 | #ifndef OPTIMIZER_HIDE_VAR |
156 | #define OPTIMIZER_HIDE_VAR(var) barrier() | |
157 | #endif | |
158 | ||
6f33d587 RR |
159 | /* Not-quite-unique ID. */ |
160 | #ifndef __UNIQUE_ID | |
161 | # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) | |
162 | #endif | |
163 | ||
230fa253 CB |
164 | #include <uapi/linux/types.h> |
165 | ||
d976441f AR |
166 | #define __READ_ONCE_SIZE \ |
167 | ({ \ | |
168 | switch (size) { \ | |
169 | case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ | |
170 | case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ | |
171 | case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ | |
172 | case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ | |
173 | default: \ | |
174 | barrier(); \ | |
175 | __builtin_memcpy((void *)res, (const void *)p, size); \ | |
176 | barrier(); \ | |
177 | } \ | |
178 | }) | |
179 | ||
180 | static __always_inline | |
181 | void __read_once_size(const volatile void *p, void *res, int size) | |
230fa253 | 182 | { |
d976441f AR |
183 | __READ_ONCE_SIZE; |
184 | } | |
185 | ||
186 | #ifdef CONFIG_KASAN | |
187 | /* | |
188 | * This function is not 'inline' because __no_sanitize_address confilcts | |
189 | * with inlining. Attempt to inline it may cause a build failure. | |
190 | * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 | |
191 | * '__maybe_unused' allows us to avoid defined-but-not-used warnings. | |
192 | */ | |
193 | static __no_sanitize_address __maybe_unused | |
194 | void __read_once_size_nocheck(const volatile void *p, void *res, int size) | |
195 | { | |
196 | __READ_ONCE_SIZE; | |
197 | } | |
198 | #else | |
199 | static __always_inline | |
200 | void __read_once_size_nocheck(const volatile void *p, void *res, int size) | |
201 | { | |
202 | __READ_ONCE_SIZE; | |
230fa253 | 203 | } |
d976441f | 204 | #endif |
230fa253 | 205 | |
43239cbe | 206 | static __always_inline void __write_once_size(volatile void *p, void *res, int size) |
230fa253 CB |
207 | { |
208 | switch (size) { | |
209 | case 1: *(volatile __u8 *)p = *(__u8 *)res; break; | |
210 | case 2: *(volatile __u16 *)p = *(__u16 *)res; break; | |
211 | case 4: *(volatile __u32 *)p = *(__u32 *)res; break; | |
230fa253 | 212 | case 8: *(volatile __u64 *)p = *(__u64 *)res; break; |
230fa253 CB |
213 | default: |
214 | barrier(); | |
215 | __builtin_memcpy((void *)p, (const void *)res, size); | |
230fa253 CB |
216 | barrier(); |
217 | } | |
218 | } | |
219 | ||
220 | /* | |
221 | * Prevent the compiler from merging or refetching reads or writes. The | |
222 | * compiler is also forbidden from reordering successive instances of | |
b899a850 MR |
223 | * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some |
224 | * particular ordering. One way to make the compiler aware of ordering is to | |
225 | * put the two invocations of READ_ONCE or WRITE_ONCE in different C | |
226 | * statements. | |
230fa253 | 227 | * |
b899a850 MR |
228 | * These two macros will also work on aggregate data types like structs or |
229 | * unions. If the size of the accessed data type exceeds the word size of | |
230 | * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will | |
231 | * fall back to memcpy(). There's at least two memcpy()s: one for the | |
232 | * __builtin_memcpy() and then one for the macro doing the copy of variable | |
233 | * - '__u' allocated on the stack. | |
230fa253 CB |
234 | * |
235 | * Their two major use cases are: (1) Mediating communication between | |
236 | * process-level code and irq/NMI handlers, all running on the same CPU, | |
b899a850 | 237 | * and (2) Ensuring that the compiler does not fold, spindle, or otherwise |
230fa253 CB |
238 | * mutilate accesses that either do not require ordering or that interact |
239 | * with an explicit memory barrier or atomic instruction that provides the | |
240 | * required ordering. | |
241 | */ | |
d1515582 | 242 | #include <asm/barrier.h> |
230fa253 | 243 | |
d976441f AR |
244 | #define __READ_ONCE(x, check) \ |
245 | ({ \ | |
246 | union { typeof(x) __val; char __c[1]; } __u; \ | |
247 | if (check) \ | |
248 | __read_once_size(&(x), __u.__c, sizeof(x)); \ | |
249 | else \ | |
250 | __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ | |
76ebbe78 | 251 | smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ |
d976441f AR |
252 | __u.__val; \ |
253 | }) | |
254 | #define READ_ONCE(x) __READ_ONCE(x, 1) | |
255 | ||
256 | /* | |
257 | * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need | |
258 | * to hide memory access from KASAN. | |
259 | */ | |
260 | #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) | |
230fa253 | 261 | |
43239cbe | 262 | #define WRITE_ONCE(x, val) \ |
ba33034f CB |
263 | ({ \ |
264 | union { typeof(x) __val; char __c[1]; } __u = \ | |
265 | { .__val = (__force typeof(x)) (val) }; \ | |
266 | __write_once_size(&(x), __u.__c, sizeof(x)); \ | |
267 | __u.__val; \ | |
268 | }) | |
230fa253 | 269 | |
1da177e4 LT |
270 | #endif /* __KERNEL__ */ |
271 | ||
272 | #endif /* __ASSEMBLY__ */ | |
273 | ||
9f0cf4ad AV |
274 | /* Compile time object size, -1 for unknown */ |
275 | #ifndef __compiletime_object_size | |
276 | # define __compiletime_object_size(obj) -1 | |
277 | #endif | |
4a312769 AV |
278 | #ifndef __compiletime_warning |
279 | # define __compiletime_warning(message) | |
280 | #endif | |
63312b6a AV |
281 | #ifndef __compiletime_error |
282 | # define __compiletime_error(message) | |
2c0d259e JH |
283 | /* |
284 | * Sparse complains of variable sized arrays due to the temporary variable in | |
285 | * __compiletime_assert. Unfortunately we can't just expand it out to make | |
286 | * sparse see a constant array size without breaking compiletime_assert on old | |
287 | * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. | |
288 | */ | |
289 | # ifndef __CHECKER__ | |
290 | # define __compiletime_error_fallback(condition) \ | |
9a8ab1c3 | 291 | do { ((void)sizeof(char[1 - 2 * condition])); } while (0) |
2c0d259e JH |
292 | # endif |
293 | #endif | |
294 | #ifndef __compiletime_error_fallback | |
c361d3e5 | 295 | # define __compiletime_error_fallback(condition) do { } while (0) |
63312b6a | 296 | #endif |
c361d3e5 | 297 | |
c03567a8 JS |
298 | #ifdef __OPTIMIZE__ |
299 | # define __compiletime_assert(condition, msg, prefix, suffix) \ | |
9a8ab1c3 DS |
300 | do { \ |
301 | bool __cond = !(condition); \ | |
302 | extern void prefix ## suffix(void) __compiletime_error(msg); \ | |
303 | if (__cond) \ | |
304 | prefix ## suffix(); \ | |
305 | __compiletime_error_fallback(__cond); \ | |
306 | } while (0) | |
c03567a8 JS |
307 | #else |
308 | # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) | |
309 | #endif | |
9a8ab1c3 DS |
310 | |
311 | #define _compiletime_assert(condition, msg, prefix, suffix) \ | |
312 | __compiletime_assert(condition, msg, prefix, suffix) | |
313 | ||
314 | /** | |
315 | * compiletime_assert - break build and emit msg if condition is false | |
316 | * @condition: a compile-time constant condition to check | |
317 | * @msg: a message to emit if condition is false | |
318 | * | |
319 | * In tradition of POSIX assert, this macro will break the build if the | |
320 | * supplied condition is *false*, emitting the supplied error message if the | |
321 | * compiler has support to do so. | |
322 | */ | |
323 | #define compiletime_assert(condition, msg) \ | |
324 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) | |
325 | ||
47933ad4 PZ |
326 | #define compiletime_assert_atomic_type(t) \ |
327 | compiletime_assert(__native_word(t), \ | |
328 | "Need native word sized stores/loads for atomicity.") | |
329 | ||
1da177e4 | 330 | #endif /* __LINUX_COMPILER_H */ |