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 #endif 80 81 /* Optimization barrier */ 82 #ifndef barrier 83 # define barrier() __memory_barrier() 84 #endif 85 86 #ifndef barrier_data 87 # define barrier_data(ptr) barrier() 88 #endif 89 90 /* workaround for GCC PR82365 if needed */ 91 #ifndef barrier_before_unreachable 92 # define barrier_before_unreachable() do { } while (0) 93 #endif 94 95 /* Unreachable code */ 96 #ifdef CONFIG_STACK_VALIDATION 97 /* 98 * These macros help objtool understand GCC code flow for unreachable code. 99 * The __COUNTER__ based labels are a hack to make each instance of the macros 100 * unique, to convince GCC not to merge duplicate inline asm statements. 101 */ 102 #define annotate_reachable() ({ \ 103 asm volatile("%c0:\n\t" \ 104 ".pushsection .discard.reachable\n\t" \ 105 ".long %c0b - .\n\t" \ 106 ".popsection\n\t" : : "i" (__COUNTER__)); \ 107 }) 108 #define annotate_unreachable() ({ \ 109 asm volatile("%c0:\n\t" \ 110 ".pushsection .discard.unreachable\n\t" \ 111 ".long %c0b - .\n\t" \ 112 ".popsection\n\t" : : "i" (__COUNTER__)); \ 113 }) 114 #define ASM_UNREACHABLE \ 115 "999:\n\t" \ 116 ".pushsection .discard.unreachable\n\t" \ 117 ".long 999b - .\n\t" \ 118 ".popsection\n\t" 119 120 /* Annotate a C jump table to allow objtool to follow the code flow */ 121 #define __annotate_jump_table __section(".rodata..c_jump_table") 122 123 #else 124 #define annotate_reachable() 125 #define annotate_unreachable() 126 #define __annotate_jump_table 127 #endif 128 129 #ifndef ASM_UNREACHABLE 130 # define ASM_UNREACHABLE 131 #endif 132 #ifndef unreachable 133 # define unreachable() do { \ 134 annotate_unreachable(); \ 135 __builtin_unreachable(); \ 136 } while (0) 137 #endif 138 139 /* 140 * KENTRY - kernel entry point 141 * This can be used to annotate symbols (functions or data) that are used 142 * without their linker symbol being referenced explicitly. For example, 143 * interrupt vector handlers, or functions in the kernel image that are found 144 * programatically. 145 * 146 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 147 * are handled in their own way (with KEEP() in linker scripts). 148 * 149 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 150 * linker script. For example an architecture could KEEP() its entire 151 * boot/exception vector code rather than annotate each function and data. 152 */ 153 #ifndef KENTRY 154 # define KENTRY(sym) \ 155 extern typeof(sym) sym; \ 156 static const unsigned long __kentry_##sym \ 157 __used \ 158 __attribute__((__section__("___kentry+" #sym))) \ 159 = (unsigned long)&sym; 160 #endif 161 162 #ifndef RELOC_HIDE 163 # define RELOC_HIDE(ptr, off) \ 164 ({ unsigned long __ptr; \ 165 __ptr = (unsigned long) (ptr); \ 166 (typeof(ptr)) (__ptr + (off)); }) 167 #endif 168 169 #ifndef OPTIMIZER_HIDE_VAR 170 /* Make the optimizer believe the variable can be manipulated arbitrarily. */ 171 #define OPTIMIZER_HIDE_VAR(var) \ 172 __asm__ ("" : "=r" (var) : "0" (var)) 173 #endif 174 175 /* Not-quite-unique ID. */ 176 #ifndef __UNIQUE_ID 177 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 178 #endif 179 180 /** 181 * data_race - mark an expression as containing intentional data races 182 * 183 * This data_race() macro is useful for situations in which data races 184 * should be forgiven. One example is diagnostic code that accesses 185 * shared variables but is not a part of the core synchronization design. 186 * 187 * This macro *does not* affect normal code generation, but is a hint 188 * to tooling that data races here are to be ignored. 189 */ 190 #define data_race(expr) \ 191 ({ \ 192 __unqual_scalar_typeof(({ expr; })) __v = ({ \ 193 __kcsan_disable_current(); \ 194 expr; \ 195 }); \ 196 __kcsan_enable_current(); \ 197 __v; \ 198 }) 199 200 #endif /* __KERNEL__ */ 201 202 /* 203 * Force the compiler to emit 'sym' as a symbol, so that we can reference 204 * it from inline assembler. Necessary in case 'sym' could be inlined 205 * otherwise, or eliminated entirely due to lack of references that are 206 * visible to the compiler. 207 */ 208 #define __ADDRESSABLE(sym) \ 209 static void * __section(".discard.addressable") __used \ 210 __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym; 211 212 /** 213 * offset_to_ptr - convert a relative memory offset to an absolute pointer 214 * @off: the address of the 32-bit offset value 215 */ 216 static inline void *offset_to_ptr(const int *off) 217 { 218 return (void *)((unsigned long)off + *off); 219 } 220 221 #endif /* __ASSEMBLY__ */ 222 223 /* &a[0] degrades to a pointer: a different type from an array */ 224 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 225 226 /* 227 * This is needed in functions which generate the stack canary, see 228 * arch/x86/kernel/smpboot.c::start_secondary() for an example. 229 */ 230 #define prevent_tail_call_optimization() mb() 231 232 #include <asm/rwonce.h> 233 234 #endif /* __LINUX_COMPILER_H */ 235