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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_STACK_VALIDATION
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 annotate_reachable() ({ \
119 : asm volatile("%c0:\n\t" \
120 : ".pushsection .discard.reachable\n\t" \
121 : ".long %c0b - .\n\t" \
122 : ".popsection\n\t" : : "i" (__COUNTER__)); \
123 : })
124 : #define annotate_unreachable() ({ \
125 : asm volatile("%c0:\n\t" \
126 : ".pushsection .discard.unreachable\n\t" \
127 : ".long %c0b - .\n\t" \
128 : ".popsection\n\t" : : "i" (__COUNTER__)); \
129 : })
130 : #define ASM_UNREACHABLE \
131 : "999:\n\t" \
132 : ".pushsection .discard.unreachable\n\t" \
133 : ".long 999b - .\n\t" \
134 : ".popsection\n\t"
135 :
136 : /* Annotate a C jump table to allow objtool to follow the code flow */
137 : #define __annotate_jump_table __section(".rodata..c_jump_table")
138 :
139 : #else
140 : #define annotate_reachable()
141 : #define annotate_unreachable()
142 : #define __annotate_jump_table
143 : #endif
144 :
145 : #ifndef ASM_UNREACHABLE
146 : # define ASM_UNREACHABLE
147 : #endif
148 : #ifndef unreachable
149 : # define unreachable() do { \
150 : annotate_unreachable(); \
151 : __builtin_unreachable(); \
152 : } while (0)
153 : #endif
154 :
155 : /*
156 : * KENTRY - kernel entry point
157 : * This can be used to annotate symbols (functions or data) that are used
158 : * without their linker symbol being referenced explicitly. For example,
159 : * interrupt vector handlers, or functions in the kernel image that are found
160 : * programatically.
161 : *
162 : * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
163 : * are handled in their own way (with KEEP() in linker scripts).
164 : *
165 : * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
166 : * linker script. For example an architecture could KEEP() its entire
167 : * boot/exception vector code rather than annotate each function and data.
168 : */
169 : #ifndef KENTRY
170 : # define KENTRY(sym) \
171 : extern typeof(sym) sym; \
172 : static const unsigned long __kentry_##sym \
173 : __used \
174 : __attribute__((__section__("___kentry+" #sym))) \
175 : = (unsigned long)&sym;
176 : #endif
177 :
178 : #ifndef RELOC_HIDE
179 : # define RELOC_HIDE(ptr, off) \
180 : ({ unsigned long __ptr; \
181 : __ptr = (unsigned long) (ptr); \
182 : (typeof(ptr)) (__ptr + (off)); })
183 : #endif
184 :
185 : #ifndef OPTIMIZER_HIDE_VAR
186 : /* Make the optimizer believe the variable can be manipulated arbitrarily. */
187 : #define OPTIMIZER_HIDE_VAR(var) \
188 : __asm__ ("" : "=r" (var) : "0" (var))
189 : #endif
190 :
191 : /* Not-quite-unique ID. */
192 : #ifndef __UNIQUE_ID
193 : # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
194 : #endif
195 :
196 : /**
197 : * data_race - mark an expression as containing intentional data races
198 : *
199 : * This data_race() macro is useful for situations in which data races
200 : * should be forgiven. One example is diagnostic code that accesses
201 : * shared variables but is not a part of the core synchronization design.
202 : *
203 : * This macro *does not* affect normal code generation, but is a hint
204 : * to tooling that data races here are to be ignored.
205 : */
206 : #define data_race(expr) \
207 : ({ \
208 : __unqual_scalar_typeof(({ expr; })) __v = ({ \
209 : __kcsan_disable_current(); \
210 : expr; \
211 : }); \
212 : __kcsan_enable_current(); \
213 : __v; \
214 : })
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 : */
232 259 : static inline void *offset_to_ptr(const int *off)
233 : {
234 259 : 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 */
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