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1408 | serge | 1 | #ifndef __LINUX_COMPILER_H |
2 | #error "Please don't include |
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3 | #endif |
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4 | |||
5 | /* |
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6 | * Common definitions for all gcc versions go here. |
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7 | */ |
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6082 | serge | 8 | #define GCC_VERSION (__GNUC__ * 10000 \ |
9 | + __GNUC_MINOR__ * 100 \ |
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10 | + __GNUC_PATCHLEVEL__) |
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1408 | serge | 11 | |
6082 | serge | 12 | /* Optimization barrier */ |
1408 | serge | 13 | |
14 | /* The "volatile" is due to gcc bugs */ |
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15 | #define barrier() __asm__ __volatile__("": : :"memory") |
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6082 | serge | 16 | /* |
17 | * This version is i.e. to prevent dead stores elimination on @ptr |
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18 | * where gcc and llvm may behave differently when otherwise using |
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19 | * normal barrier(): while gcc behavior gets along with a normal |
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20 | * barrier(), llvm needs an explicit input variable to be assumed |
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21 | * clobbered. The issue is as follows: while the inline asm might |
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22 | * access any memory it wants, the compiler could have fit all of |
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23 | * @ptr into memory registers instead, and since @ptr never escaped |
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24 | * from that, it proofed that the inline asm wasn't touching any of |
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25 | * it. This version works well with both compilers, i.e. we're telling |
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26 | * the compiler that the inline asm absolutely may see the contents |
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27 | * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 |
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28 | */ |
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29 | #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") |
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1408 | serge | 30 | |
31 | /* |
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32 | * This macro obfuscates arithmetic on a variable address so that gcc |
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33 | * shouldn't recognize the original var, and make assumptions about it. |
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34 | * |
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35 | * This is needed because the C standard makes it undefined to do |
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36 | * pointer arithmetic on "objects" outside their boundaries and the |
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37 | * gcc optimizers assume this is the case. In particular they |
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38 | * assume such arithmetic does not wrap. |
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39 | * |
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40 | * A miscompilation has been observed because of this on PPC. |
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41 | * To work around it we hide the relationship of the pointer and the object |
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42 | * using this macro. |
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43 | * |
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44 | * Versions of the ppc64 compiler before 4.1 had a bug where use of |
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45 | * RELOC_HIDE could trash r30. The bug can be worked around by changing |
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46 | * the inline assembly constraint from =g to =r, in this particular |
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47 | * case either is valid. |
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48 | */ |
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6082 | serge | 49 | #define RELOC_HIDE(ptr, off) \ |
50 | ({ \ |
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51 | unsigned long __ptr; \ |
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52 | __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ |
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53 | (typeof(ptr)) (__ptr + (off)); \ |
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54 | }) |
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1408 | serge | 55 | |
5056 | serge | 56 | /* Make the optimizer believe the variable can be manipulated arbitrarily. */ |
6082 | serge | 57 | #define OPTIMIZER_HIDE_VAR(var) \ |
58 | __asm__ ("" : "=r" (var) : "0" (var)) |
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5056 | serge | 59 | |
1970 | serge | 60 | #ifdef __CHECKER__ |
6082 | serge | 61 | #define __must_be_array(a) 0 |
1970 | serge | 62 | #else |
1408 | serge | 63 | /* &a[0] degrades to a pointer: a different type from an array */ |
6082 | serge | 64 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) |
1970 | serge | 65 | #endif |
1408 | serge | 66 | |
67 | /* |
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68 | * Force always-inline if the user requests it so via the .config, |
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69 | * or if gcc is too old: |
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70 | */ |
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6082 | serge | 71 | #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ |
1408 | serge | 72 | !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) |
6082 | serge | 73 | #define inline inline __attribute__((always_inline)) notrace |
74 | #define __inline__ __inline__ __attribute__((always_inline)) notrace |
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75 | #define __inline __inline __attribute__((always_inline)) notrace |
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5056 | serge | 76 | #else |
77 | /* A lot of inline functions can cause havoc with function tracing */ |
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6082 | serge | 78 | #define inline inline notrace |
79 | #define __inline__ __inline__ notrace |
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80 | #define __inline __inline notrace |
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1408 | serge | 81 | #endif |
82 | |||
6082 | serge | 83 | #define __always_inline inline __attribute__((always_inline)) |
84 | #define noinline __attribute__((noinline)) |
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1408 | serge | 85 | |
6082 | serge | 86 | #define __deprecated __attribute__((deprecated)) |
87 | #define __packed __attribute__((packed)) |
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88 | #define __weak __attribute__((weak)) |
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89 | #define __alias(symbol) __attribute__((alias(#symbol))) |
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90 | |||
1408 | serge | 91 | /* |
6082 | serge | 92 | * it doesn't make sense on ARM (currently the only user of __naked) |
93 | * to trace naked functions because then mcount is called without |
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94 | * stack and frame pointer being set up and there is no chance to |
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95 | * restore the lr register to the value before mcount was called. |
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1964 | serge | 96 | * |
6082 | serge | 97 | * The asm() bodies of naked functions often depend on standard calling |
98 | * conventions, therefore they must be noinline and noclone. |
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99 | * |
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100 | * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. |
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101 | * See GCC PR44290. |
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1408 | serge | 102 | */ |
6082 | serge | 103 | #define __naked __attribute__((naked)) noinline __noclone notrace |
1408 | serge | 104 | |
6082 | serge | 105 | #define __noreturn __attribute__((noreturn)) |
1408 | serge | 106 | |
107 | /* |
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108 | * From the GCC manual: |
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109 | * |
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110 | * Many functions have no effects except the return value and their |
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111 | * return value depends only on the parameters and/or global |
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112 | * variables. Such a function can be subject to common subexpression |
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113 | * elimination and loop optimization just as an arithmetic operator |
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114 | * would be. |
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115 | * [...] |
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116 | */ |
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6082 | serge | 117 | #define __pure __attribute__((pure)) |
118 | #define __aligned(x) __attribute__((aligned(x))) |
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119 | #define __printf(a, b) __attribute__((format(printf, a, b))) |
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120 | #define __scanf(a, b) __attribute__((format(scanf, a, b))) |
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121 | #define __attribute_const__ __attribute__((__const__)) |
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122 | #define __maybe_unused __attribute__((unused)) |
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123 | #define __always_unused __attribute__((unused)) |
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1408 | serge | 124 | |
6082 | serge | 125 | /* gcc version specific checks */ |
1964 | serge | 126 | |
6082 | serge | 127 | #if GCC_VERSION < 30200 |
128 | # error Sorry, your compiler is too old - please upgrade it. |
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129 | #endif |
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130 | |||
131 | #if GCC_VERSION < 30300 |
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132 | # define __used __attribute__((__unused__)) |
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133 | #else |
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134 | # define __used __attribute__((__used__)) |
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135 | #endif |
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136 | |||
137 | #ifdef CONFIG_GCOV_KERNEL |
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138 | # if GCC_VERSION < 30400 |
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139 | # error "GCOV profiling support for gcc versions below 3.4 not included" |
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140 | # endif /* __GNUC_MINOR__ */ |
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141 | #endif /* CONFIG_GCOV_KERNEL */ |
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142 | |||
143 | #if GCC_VERSION >= 30400 |
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144 | #define __must_check __attribute__((warn_unused_result)) |
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145 | #endif |
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146 | |||
147 | #if GCC_VERSION >= 40000 |
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148 | |||
149 | /* GCC 4.1.[01] miscompiles __weak */ |
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150 | #ifdef __KERNEL__ |
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151 | # if GCC_VERSION >= 40100 && GCC_VERSION <= 40101 |
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152 | # error Your version of gcc miscompiles the __weak directive |
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153 | # endif |
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154 | #endif |
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155 | |||
156 | #define __used __attribute__((__used__)) |
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157 | #define __compiler_offsetof(a, b) \ |
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158 | __builtin_offsetof(a, b) |
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159 | |||
160 | #if GCC_VERSION >= 40100 && GCC_VERSION < 40600 |
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161 | # define __compiletime_object_size(obj) __builtin_object_size(obj, 0) |
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162 | #endif |
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163 | |||
164 | #if GCC_VERSION >= 40300 |
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165 | /* Mark functions as cold. gcc will assume any path leading to a call |
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166 | * to them will be unlikely. This means a lot of manual unlikely()s |
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167 | * are unnecessary now for any paths leading to the usual suspects |
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168 | * like BUG(), printk(), panic() etc. [but let's keep them for now for |
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169 | * older compilers] |
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170 | * |
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171 | * Early snapshots of gcc 4.3 don't support this and we can't detect this |
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172 | * in the preprocessor, but we can live with this because they're unreleased. |
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173 | * Maketime probing would be overkill here. |
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174 | * |
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175 | * gcc also has a __attribute__((__hot__)) to move hot functions into |
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176 | * a special section, but I don't see any sense in this right now in |
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177 | * the kernel context |
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178 | */ |
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179 | #define __cold __attribute__((__cold__)) |
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180 | |||
181 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) |
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182 | |||
183 | #ifndef __CHECKER__ |
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184 | # define __compiletime_warning(message) __attribute__((warning(message))) |
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185 | # define __compiletime_error(message) __attribute__((error(message))) |
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186 | #endif /* __CHECKER__ */ |
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187 | #endif /* GCC_VERSION >= 40300 */ |
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188 | |||
189 | #if GCC_VERSION >= 40500 |
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190 | /* |
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191 | * Mark a position in code as unreachable. This can be used to |
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192 | * suppress control flow warnings after asm blocks that transfer |
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193 | * control elsewhere. |
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194 | * |
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195 | * Early snapshots of gcc 4.5 don't support this and we can't detect |
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196 | * this in the preprocessor, but we can live with this because they're |
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197 | * unreleased. Really, we need to have autoconf for the kernel. |
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198 | */ |
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199 | #define unreachable() __builtin_unreachable() |
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200 | |||
201 | /* Mark a function definition as prohibited from being cloned. */ |
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6588 | serge | 202 | #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) |
6082 | serge | 203 | |
204 | #endif /* GCC_VERSION >= 40500 */ |
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205 | |||
206 | #if GCC_VERSION >= 40600 |
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207 | /* |
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208 | * When used with Link Time Optimization, gcc can optimize away C functions or |
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209 | * variables which are referenced only from assembly code. __visible tells the |
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210 | * optimizer that something else uses this function or variable, thus preventing |
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211 | * this. |
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212 | */ |
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213 | #define __visible __attribute__((externally_visible)) |
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214 | #endif |
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215 | |||
216 | |||
217 | #if GCC_VERSION >= 40900 && !defined(__CHECKER__) |
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218 | /* |
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219 | * __assume_aligned(n, k): Tell the optimizer that the returned |
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220 | * pointer can be assumed to be k modulo n. The second argument is |
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221 | * optional (default 0), so we use a variadic macro to make the |
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222 | * shorthand. |
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223 | * |
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224 | * Beware: Do not apply this to functions which may return |
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225 | * ERR_PTRs. Also, it is probably unwise to apply it to functions |
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226 | * returning extra information in the low bits (but in that case the |
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227 | * compiler should see some alignment anyway, when the return value is |
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228 | * massaged by 'flags = ptr & 3; ptr &= ~3;'). |
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229 | */ |
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230 | #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) |
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231 | #endif |
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232 | |||
233 | /* |
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234 | * GCC 'asm goto' miscompiles certain code sequences: |
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235 | * |
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236 | * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 |
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237 | * |
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238 | * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. |
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239 | * |
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240 | * (asm goto is automatically volatile - the naming reflects this.) |
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241 | */ |
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242 | #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) |
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243 | |||
244 | #ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP |
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245 | #if GCC_VERSION >= 40400 |
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246 | #define __HAVE_BUILTIN_BSWAP32__ |
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247 | #define __HAVE_BUILTIN_BSWAP64__ |
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248 | #endif |
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249 | #if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600) |
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250 | #define __HAVE_BUILTIN_BSWAP16__ |
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251 | #endif |
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252 | #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */ |
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253 | |||
6936 | serge | 254 | #if GCC_VERSION >= 50000 |
6082 | serge | 255 | #define KASAN_ABI_VERSION 4 |
256 | #elif GCC_VERSION >= 40902 |
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257 | #define KASAN_ABI_VERSION 3 |
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258 | #endif |
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259 | |||
260 | #if GCC_VERSION >= 40902 |
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261 | /* |
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262 | * Tell the compiler that address safety instrumentation (KASAN) |
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263 | * should not be applied to that function. |
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264 | * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 |
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265 | */ |
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266 | #define __no_sanitize_address __attribute__((no_sanitize_address)) |
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267 | #endif |
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268 | |||
269 | #endif /* gcc version >= 40000 specific checks */ |
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270 | |||
1964 | serge | 271 | #if !defined(__noclone) |
272 | #define __noclone /* not needed */ |
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273 | #endif |
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1970 | serge | 274 | |
6082 | serge | 275 | #if !defined(__no_sanitize_address) |
276 | #define __no_sanitize_address |
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277 | #endif |
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278 | |||
1970 | serge | 279 | /* |
280 | * A trick to suppress uninitialized variable warning without generating any |
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281 | * code |
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282 | */ |
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283 | #define uninitialized_var(x) x = x>=>>>>> |