1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef __LINUX_COMPILER_H |
3 | #define __LINUX_COMPILER_H |
4 | |
5 | #include <linux/compiler_types.h> |
6 | |
7 | #ifndef __ASSEMBLY__ |
8 | |
9 | #ifdef __KERNEL__ |
10 | |
11 | /* |
12 | * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code |
13 | * to disable branch tracing on a per file basis. |
14 | */ |
15 | #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ |
16 | && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) |
17 | void ftrace_likely_update(struct ftrace_likely_data *f, int val, |
18 | int expect, int is_constant); |
19 | |
20 | #define likely_notrace(x) __builtin_expect(!!(x), 1) |
21 | #define unlikely_notrace(x) __builtin_expect(!!(x), 0) |
22 | |
23 | #define __branch_check__(x, expect, is_constant) ({ \ |
24 | long ______r; \ |
25 | static struct ftrace_likely_data \ |
26 | __aligned(4) \ |
27 | __section("_ftrace_annotated_branch") \ |
28 | ______f = { \ |
29 | .data.func = __func__, \ |
30 | .data.file = __FILE__, \ |
31 | .data.line = __LINE__, \ |
32 | }; \ |
33 | ______r = __builtin_expect(!!(x), expect); \ |
34 | ftrace_likely_update(&______f, ______r, \ |
35 | expect, is_constant); \ |
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 |
45 | # define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x))) |
46 | # endif |
47 | # ifndef unlikely |
48 | # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) |
49 | # endif |
50 | |
51 | #ifdef CONFIG_PROFILE_ALL_BRANCHES |
52 | /* |
53 | * "Define 'is'", Bill Clinton |
54 | * "Define 'if'", Steven Rostedt |
55 | */ |
56 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) |
57 | |
58 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) |
59 | |
60 | #define __trace_if_value(cond) ({ \ |
61 | static struct ftrace_branch_data \ |
62 | __aligned(4) \ |
63 | __section("_ftrace_branch") \ |
64 | __if_trace = { \ |
65 | .func = __func__, \ |
66 | .file = __FILE__, \ |
67 | .line = __LINE__, \ |
68 | }; \ |
69 | (cond) ? \ |
70 | (__if_trace.miss_hit[1]++,1) : \ |
71 | (__if_trace.miss_hit[0]++,0); \ |
72 | }) |
73 | |
74 | #endif /* CONFIG_PROFILE_ALL_BRANCHES */ |
75 | |
76 | #else |
77 | # define likely(x) __builtin_expect(!!(x), 1) |
78 | # define unlikely(x) __builtin_expect(!!(x), 0) |
79 | # define likely_notrace(x) likely(x) |
80 | # define unlikely_notrace(x) unlikely(x) |
81 | #endif |
82 | |
83 | /* Optimization barrier */ |
84 | #ifndef barrier |
85 | /* The "volatile" is due to gcc bugs */ |
86 | # define barrier() __asm__ __volatile__("": : :"memory") |
87 | #endif |
88 | |
89 | #ifndef barrier_data |
90 | /* |
91 | * This version is i.e. to prevent dead stores elimination on @ptr |
92 | * where gcc and llvm may behave differently when otherwise using |
93 | * normal barrier(): while gcc behavior gets along with a normal |
94 | * barrier(), llvm needs an explicit input variable to be assumed |
95 | * clobbered. The issue is as follows: while the inline asm might |
96 | * access any memory it wants, the compiler could have fit all of |
97 | * @ptr into memory registers instead, and since @ptr never escaped |
98 | * from that, it proved that the inline asm wasn't touching any of |
99 | * it. This version works well with both compilers, i.e. we're telling |
100 | * the compiler that the inline asm absolutely may see the contents |
101 | * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 |
102 | */ |
103 | # define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") |
104 | #endif |
105 | |
106 | /* workaround for GCC PR82365 if needed */ |
107 | #ifndef barrier_before_unreachable |
108 | # define barrier_before_unreachable() do { } while (0) |
109 | #endif |
110 | |
111 | /* Unreachable code */ |
112 | #ifdef CONFIG_OBJTOOL |
113 | /* |
114 | * These macros help objtool understand GCC code flow for unreachable code. |
115 | * The __COUNTER__ based labels are a hack to make each instance of the macros |
116 | * unique, to convince GCC not to merge duplicate inline asm statements. |
117 | */ |
118 | #define __stringify_label(n) #n |
119 | |
120 | #define __annotate_unreachable(c) ({ \ |
121 | asm volatile(__stringify_label(c) ":\n\t" \ |
122 | ".pushsection .discard.unreachable\n\t" \ |
123 | ".long " __stringify_label(c) "b - .\n\t" \ |
124 | ".popsection\n\t" : : "i" (c)); \ |
125 | }) |
126 | #define annotate_unreachable() __annotate_unreachable(__COUNTER__) |
127 | |
128 | /* Annotate a C jump table to allow objtool to follow the code flow */ |
129 | #define __annotate_jump_table __section(".rodata..c_jump_table") |
130 | |
131 | #else /* !CONFIG_OBJTOOL */ |
132 | #define annotate_unreachable() |
133 | #define __annotate_jump_table |
134 | #endif /* CONFIG_OBJTOOL */ |
135 | |
136 | #ifndef unreachable |
137 | # define unreachable() do { \ |
138 | annotate_unreachable(); \ |
139 | __builtin_unreachable(); \ |
140 | } while (0) |
141 | #endif |
142 | |
143 | /* |
144 | * KENTRY - kernel entry point |
145 | * This can be used to annotate symbols (functions or data) that are used |
146 | * without their linker symbol being referenced explicitly. For example, |
147 | * interrupt vector handlers, or functions in the kernel image that are found |
148 | * programatically. |
149 | * |
150 | * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those |
151 | * are handled in their own way (with KEEP() in linker scripts). |
152 | * |
153 | * KENTRY can be avoided if the symbols in question are marked as KEEP() in the |
154 | * linker script. For example an architecture could KEEP() its entire |
155 | * boot/exception vector code rather than annotate each function and data. |
156 | */ |
157 | #ifndef KENTRY |
158 | # define KENTRY(sym) \ |
159 | extern typeof(sym) sym; \ |
160 | static const unsigned long __kentry_##sym \ |
161 | __used \ |
162 | __attribute__((__section__("___kentry+" #sym))) \ |
163 | = (unsigned long)&sym; |
164 | #endif |
165 | |
166 | #ifndef RELOC_HIDE |
167 | # define RELOC_HIDE(ptr, off) \ |
168 | ({ unsigned long __ptr; \ |
169 | __ptr = (unsigned long) (ptr); \ |
170 | (typeof(ptr)) (__ptr + (off)); }) |
171 | #endif |
172 | |
173 | #define absolute_pointer(val) RELOC_HIDE((void *)(val), 0) |
174 | |
175 | #ifndef OPTIMIZER_HIDE_VAR |
176 | /* Make the optimizer believe the variable can be manipulated arbitrarily. */ |
177 | #define OPTIMIZER_HIDE_VAR(var) \ |
178 | __asm__ ("" : "=r" (var) : "0" (var)) |
179 | #endif |
180 | |
181 | /* Not-quite-unique ID. */ |
182 | #ifndef __UNIQUE_ID |
183 | # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) |
184 | #endif |
185 | |
186 | /** |
187 | * data_race - mark an expression as containing intentional data races |
188 | * |
189 | * This data_race() macro is useful for situations in which data races |
190 | * should be forgiven. One example is diagnostic code that accesses |
191 | * shared variables but is not a part of the core synchronization design. |
192 | * |
193 | * This macro *does not* affect normal code generation, but is a hint |
194 | * to tooling that data races here are to be ignored. |
195 | */ |
196 | #define data_race(expr) \ |
197 | ({ \ |
198 | __unqual_scalar_typeof(({ expr; })) __v = ({ \ |
199 | __kcsan_disable_current(); \ |
200 | expr; \ |
201 | }); \ |
202 | __kcsan_enable_current(); \ |
203 | __v; \ |
204 | }) |
205 | |
206 | /* |
207 | * With CONFIG_CFI_CLANG, the compiler replaces function addresses in |
208 | * instrumented C code with jump table addresses. Architectures that |
209 | * support CFI can define this macro to return the actual function address |
210 | * when needed. |
211 | */ |
212 | #ifndef function_nocfi |
213 | #define function_nocfi(x) (x) |
214 | #endif |
215 | |
216 | #endif /* __KERNEL__ */ |
217 | |
218 | /* |
219 | * Force the compiler to emit 'sym' as a symbol, so that we can reference |
220 | * it from inline assembler. Necessary in case 'sym' could be inlined |
221 | * otherwise, or eliminated entirely due to lack of references that are |
222 | * visible to the compiler. |
223 | */ |
224 | #define __ADDRESSABLE(sym) \ |
225 | static void * __section(".discard.addressable") __used \ |
226 | __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym; |
227 | |
228 | /** |
229 | * offset_to_ptr - convert a relative memory offset to an absolute pointer |
230 | * @off: the address of the 32-bit offset value |
231 | */ |
232 | static inline void *offset_to_ptr(const int *off) |
233 | { |
234 | return (void *)((unsigned long)off + *off); |
235 | } |
236 | |
237 | #endif /* __ASSEMBLY__ */ |
238 | |
239 | /* &a[0] degrades to a pointer: a different type from an array */ |
240 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) |
241 | |
242 | /* |
243 | * This is needed in functions which generate the stack canary, see |
244 | * arch/x86/kernel/smpboot.c::start_secondary() for an example. |
245 | */ |
246 | #define prevent_tail_call_optimization() mb() |
247 | |
248 | #include <asm/rwonce.h> |
249 | |
250 | #endif /* __LINUX_COMPILER_H */ |
251 | |