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 /* The "volatile" is due to gcc bugs */ 84 # define barrier() __asm__ __volatile__("": : :"memory") 85 #endif 86 87 #ifndef barrier_data 88 /* 89 * This version is i.e. to prevent dead stores elimination on @ptr 90 * where gcc and llvm may behave differently when otherwise using 91 * normal barrier(): while gcc behavior gets along with a normal 92 * barrier(), llvm needs an explicit input variable to be assumed 93 * clobbered. The issue is as follows: while the inline asm might 94 * access any memory it wants, the compiler could have fit all of 95 * @ptr into memory registers instead, and since @ptr never escaped 96 * from that, it proved that the inline asm wasn't touching any of 97 * it. This version works well with both compilers, i.e. we're telling 98 * the compiler that the inline asm absolutely may see the contents 99 * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 100 */ 101 # define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") 102 #endif 103 104 /* workaround for GCC PR82365 if needed */ 105 #ifndef barrier_before_unreachable 106 # define barrier_before_unreachable() do { } while (0) 107 #endif 108 109 /* Unreachable code */ 110 #ifdef CONFIG_STACK_VALIDATION 111 /* 112 * These macros help objtool understand GCC code flow for unreachable code. 113 * The __COUNTER__ based labels are a hack to make each instance of the macros 114 * unique, to convince GCC not to merge duplicate inline asm statements. 115 */ 116 #define annotate_reachable() ({ \ 117 asm volatile("%c0:\n\t" \ 118 ".pushsection .discard.reachable\n\t" \ 119 ".long %c0b - .\n\t" \ 120 ".popsection\n\t" : : "i" (__COUNTER__)); \ 121 }) 122 #define annotate_unreachable() ({ \ 123 asm volatile("%c0:\n\t" \ 124 ".pushsection .discard.unreachable\n\t" \ 125 ".long %c0b - .\n\t" \ 126 ".popsection\n\t" : : "i" (__COUNTER__)); \ 127 }) 128 #define ASM_UNREACHABLE \ 129 "999:\n\t" \ 130 ".pushsection .discard.unreachable\n\t" \ 131 ".long 999b - .\n\t" \ 132 ".popsection\n\t" 133 134 /* Annotate a C jump table to allow objtool to follow the code flow */ 135 #define __annotate_jump_table __section(".rodata..c_jump_table") 136 137 #else 138 #define annotate_reachable() 139 #define annotate_unreachable() 140 #define __annotate_jump_table 141 #endif 142 143 #ifndef ASM_UNREACHABLE 144 # define ASM_UNREACHABLE 145 #endif 146 #ifndef unreachable 147 # define unreachable() do { \ 148 annotate_unreachable(); \ 149 __builtin_unreachable(); \ 150 } while (0) 151 #endif 152 153 /* 154 * KENTRY - kernel entry point 155 * This can be used to annotate symbols (functions or data) that are used 156 * without their linker symbol being referenced explicitly. For example, 157 * interrupt vector handlers, or functions in the kernel image that are found 158 * programatically. 159 * 160 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 161 * are handled in their own way (with KEEP() in linker scripts). 162 * 163 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 164 * linker script. For example an architecture could KEEP() its entire 165 * boot/exception vector code rather than annotate each function and data. 166 */ 167 #ifndef KENTRY 168 # define KENTRY(sym) \ 169 extern typeof(sym) sym; \ 170 static const unsigned long __kentry_##sym \ 171 __used \ 172 __attribute__((__section__("___kentry+" #sym))) \ 173 = (unsigned long)&sym; 174 #endif 175 176 #ifndef RELOC_HIDE 177 # define RELOC_HIDE(ptr, off) \ 178 ({ unsigned long __ptr; \ 179 __ptr = (unsigned long) (ptr); \ 180 (typeof(ptr)) (__ptr + (off)); }) 181 #endif 182 183 #ifndef OPTIMIZER_HIDE_VAR 184 /* Make the optimizer believe the variable can be manipulated arbitrarily. */ 185 #define OPTIMIZER_HIDE_VAR(var) \ 186 __asm__ ("" : "=r" (var) : "0" (var)) 187 #endif 188 189 /* Not-quite-unique ID. */ 190 #ifndef __UNIQUE_ID 191 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 192 #endif 193 194 /** 195 * data_race - mark an expression as containing intentional data races 196 * 197 * This data_race() macro is useful for situations in which data races 198 * should be forgiven. One example is diagnostic code that accesses 199 * shared variables but is not a part of the core synchronization design. 200 * 201 * This macro *does not* affect normal code generation, but is a hint 202 * to tooling that data races here are to be ignored. 203 */ 204 #define data_race(expr) \ 205 ({ \ 206 __unqual_scalar_typeof(({ expr; })) __v = ({ \ 207 __kcsan_disable_current(); \ 208 expr; \ 209 }); \ 210 __kcsan_enable_current(); \ 211 __v; \ 212 }) 213 214 #endif /* __KERNEL__ */ 215 216 /* 217 * Force the compiler to emit 'sym' as a symbol, so that we can reference 218 * it from inline assembler. Necessary in case 'sym' could be inlined 219 * otherwise, or eliminated entirely due to lack of references that are 220 * visible to the compiler. 221 */ 222 #define __ADDRESSABLE(sym) \ 223 static void * __section(".discard.addressable") __used \ 224 __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym; 225 226 /** 227 * offset_to_ptr - convert a relative memory offset to an absolute pointer 228 * @off: the address of the 32-bit offset value 229 */ 230 static inline void *offset_to_ptr(const int *off) 231 { 232 return (void *)((unsigned long)off + *off); 233 } 234 235 #endif /* __ASSEMBLY__ */ 236 237 /* &a[0] degrades to a pointer: a different type from an array */ 238 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 239 240 /* 241 * This is needed in functions which generate the stack canary, see 242 * arch/x86/kernel/smpboot.c::start_secondary() for an example. 243 */ 244 #define prevent_tail_call_optimization() mb() 245 246 #include <asm/rwonce.h> 247 248 #endif /* __LINUX_COMPILER_H */ 249