1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_COMPILER_TYPES_H 3 #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." 4 #endif 5 6 /* 7 * Common definitions for all gcc versions go here. 8 */ 9 #define GCC_VERSION (__GNUC__ * 10000 \ 10 + __GNUC_MINOR__ * 100 \ 11 + __GNUC_PATCHLEVEL__) 12 13 #if GCC_VERSION < 40600 14 # error Sorry, your compiler is too old - please upgrade it. 15 #endif 16 17 /* Optimization barrier */ 18 19 /* The "volatile" is due to gcc bugs */ 20 #define barrier() __asm__ __volatile__("": : :"memory") 21 /* 22 * This version is i.e. to prevent dead stores elimination on @ptr 23 * where gcc and llvm may behave differently when otherwise using 24 * normal barrier(): while gcc behavior gets along with a normal 25 * barrier(), llvm needs an explicit input variable to be assumed 26 * clobbered. The issue is as follows: while the inline asm might 27 * access any memory it wants, the compiler could have fit all of 28 * @ptr into memory registers instead, and since @ptr never escaped 29 * from that, it proved that the inline asm wasn't touching any of 30 * it. This version works well with both compilers, i.e. we're telling 31 * the compiler that the inline asm absolutely may see the contents 32 * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 33 */ 34 #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") 35 36 /* 37 * This macro obfuscates arithmetic on a variable address so that gcc 38 * shouldn't recognize the original var, and make assumptions about it. 39 * 40 * This is needed because the C standard makes it undefined to do 41 * pointer arithmetic on "objects" outside their boundaries and the 42 * gcc optimizers assume this is the case. In particular they 43 * assume such arithmetic does not wrap. 44 * 45 * A miscompilation has been observed because of this on PPC. 46 * To work around it we hide the relationship of the pointer and the object 47 * using this macro. 48 * 49 * Versions of the ppc64 compiler before 4.1 had a bug where use of 50 * RELOC_HIDE could trash r30. The bug can be worked around by changing 51 * the inline assembly constraint from =g to =r, in this particular 52 * case either is valid. 53 */ 54 #define RELOC_HIDE(ptr, off) \ 55 ({ \ 56 unsigned long __ptr; \ 57 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ 58 (typeof(ptr)) (__ptr + (off)); \ 59 }) 60 61 /* Make the optimizer believe the variable can be manipulated arbitrarily. */ 62 #define OPTIMIZER_HIDE_VAR(var) \ 63 __asm__ ("" : "=r" (var) : "0" (var)) 64 65 /* 66 * A trick to suppress uninitialized variable warning without generating any 67 * code 68 */ 69 #define uninitialized_var(x) x = x 70 71 #ifdef __CHECKER__ 72 #define __must_be_array(a) 0 73 #else 74 /* &a[0] degrades to a pointer: a different type from an array */ 75 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 76 #endif 77 78 #ifdef RETPOLINE 79 #define __noretpoline __attribute__((indirect_branch("keep"))) 80 #endif 81 82 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) 83 84 #define __optimize(level) __attribute__((__optimize__(level))) 85 86 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0) 87 88 #ifndef __CHECKER__ 89 #define __compiletime_warning(message) __attribute__((warning(message))) 90 #define __compiletime_error(message) __attribute__((error(message))) 91 92 #ifdef LATENT_ENTROPY_PLUGIN 93 #define __latent_entropy __attribute__((latent_entropy)) 94 #endif 95 #endif /* __CHECKER__ */ 96 97 /* 98 * calling noreturn functions, __builtin_unreachable() and __builtin_trap() 99 * confuse the stack allocation in gcc, leading to overly large stack 100 * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 101 * 102 * Adding an empty inline assembly before it works around the problem 103 */ 104 #define barrier_before_unreachable() asm volatile("") 105 106 /* 107 * Mark a position in code as unreachable. This can be used to 108 * suppress control flow warnings after asm blocks that transfer 109 * control elsewhere. 110 * 111 * Early snapshots of gcc 4.5 don't support this and we can't detect 112 * this in the preprocessor, but we can live with this because they're 113 * unreleased. Really, we need to have autoconf for the kernel. 114 */ 115 #define unreachable() \ 116 do { \ 117 annotate_unreachable(); \ 118 barrier_before_unreachable(); \ 119 __builtin_unreachable(); \ 120 } while (0) 121 122 /* Mark a function definition as prohibited from being cloned. */ 123 #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) 124 125 #if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__) 126 #define __randomize_layout __attribute__((randomize_layout)) 127 #define __no_randomize_layout __attribute__((no_randomize_layout)) 128 /* This anon struct can add padding, so only enable it under randstruct. */ 129 #define randomized_struct_fields_start struct { 130 #define randomized_struct_fields_end } __randomize_layout; 131 #endif 132 133 /* 134 * When used with Link Time Optimization, gcc can optimize away C functions or 135 * variables which are referenced only from assembly code. __visible tells the 136 * optimizer that something else uses this function or variable, thus preventing 137 * this. 138 */ 139 #define __visible __attribute__((externally_visible)) 140 141 /* gcc version specific checks */ 142 143 #if GCC_VERSION >= 40900 && !defined(__CHECKER__) 144 /* 145 * __assume_aligned(n, k): Tell the optimizer that the returned 146 * pointer can be assumed to be k modulo n. The second argument is 147 * optional (default 0), so we use a variadic macro to make the 148 * shorthand. 149 * 150 * Beware: Do not apply this to functions which may return 151 * ERR_PTRs. Also, it is probably unwise to apply it to functions 152 * returning extra information in the low bits (but in that case the 153 * compiler should see some alignment anyway, when the return value is 154 * massaged by 'flags = ptr & 3; ptr &= ~3;'). 155 */ 156 #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) 157 #endif 158 159 /* 160 * GCC 'asm goto' miscompiles certain code sequences: 161 * 162 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 163 * 164 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. 165 * 166 * (asm goto is automatically volatile - the naming reflects this.) 167 */ 168 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) 169 170 /* 171 * sparse (__CHECKER__) pretends to be gcc, but can't do constant 172 * folding in __builtin_bswap*() (yet), so don't set these for it. 173 */ 174 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__) 175 #define __HAVE_BUILTIN_BSWAP32__ 176 #define __HAVE_BUILTIN_BSWAP64__ 177 #if GCC_VERSION >= 40800 178 #define __HAVE_BUILTIN_BSWAP16__ 179 #endif 180 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */ 181 182 #if GCC_VERSION >= 70000 183 #define KASAN_ABI_VERSION 5 184 #elif GCC_VERSION >= 50000 185 #define KASAN_ABI_VERSION 4 186 #elif GCC_VERSION >= 40902 187 #define KASAN_ABI_VERSION 3 188 #endif 189 190 #if GCC_VERSION >= 40902 191 /* 192 * Tell the compiler that address safety instrumentation (KASAN) 193 * should not be applied to that function. 194 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 195 */ 196 #define __no_sanitize_address __attribute__((no_sanitize_address)) 197 #endif 198 199 #if GCC_VERSION >= 50100 200 /* 201 * Mark structures as requiring designated initializers. 202 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html 203 */ 204 #define __designated_init __attribute__((designated_init)) 205 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 206 #endif 207 208 #if !defined(__noclone) 209 #define __noclone /* not needed */ 210 #endif 211 212 #if !defined(__no_sanitize_address) 213 #define __no_sanitize_address 214 #endif 215 216 /* 217 * Turn individual warnings and errors on and off locally, depending 218 * on version. 219 */ 220 #define __diag_GCC(version, severity, s) \ 221 __diag_GCC_ ## version(__diag_GCC_ ## severity s) 222 223 /* Severity used in pragma directives */ 224 #define __diag_GCC_ignore ignored 225 #define __diag_GCC_warn warning 226 #define __diag_GCC_error error 227 228 #define __diag_str1(s) #s 229 #define __diag_str(s) __diag_str1(s) 230 #define __diag(s) _Pragma(__diag_str(GCC diagnostic s)) 231 232 #if GCC_VERSION >= 80000 233 #define __diag_GCC_8(s) __diag(s) 234 #else 235 #define __diag_GCC_8(s) 236 #endif 237
