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5270 | serge | 1 | #ifndef _ASM_X86_ALTERNATIVE_H |
2 | #define _ASM_X86_ALTERNATIVE_H |
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3 | |||
4 | #include |
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5 | #include |
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6 | #include |
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7 | #include |
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8 | |||
9 | /* |
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10 | * Alternative inline assembly for SMP. |
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11 | * |
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12 | * The LOCK_PREFIX macro defined here replaces the LOCK and |
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13 | * LOCK_PREFIX macros used everywhere in the source tree. |
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14 | * |
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15 | * SMP alternatives use the same data structures as the other |
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16 | * alternatives and the X86_FEATURE_UP flag to indicate the case of a |
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17 | * UP system running a SMP kernel. The existing apply_alternatives() |
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18 | * works fine for patching a SMP kernel for UP. |
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19 | * |
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20 | * The SMP alternative tables can be kept after boot and contain both |
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21 | * UP and SMP versions of the instructions to allow switching back to |
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22 | * SMP at runtime, when hotplugging in a new CPU, which is especially |
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23 | * useful in virtualized environments. |
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24 | * |
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25 | * The very common lock prefix is handled as special case in a |
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26 | * separate table which is a pure address list without replacement ptr |
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27 | * and size information. That keeps the table sizes small. |
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28 | */ |
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29 | |||
30 | #ifdef CONFIG_SMP |
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31 | #define LOCK_PREFIX_HERE \ |
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32 | ".pushsection .smp_locks,\"a\"\n" \ |
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33 | ".balign 4\n" \ |
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34 | ".long 671f - .\n" /* offset */ \ |
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35 | ".popsection\n" \ |
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36 | "671:" |
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37 | |||
38 | #define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; " |
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39 | |||
40 | #else /* ! CONFIG_SMP */ |
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41 | #define LOCK_PREFIX_HERE "" |
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42 | #define LOCK_PREFIX "" |
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43 | #endif |
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44 | |||
45 | struct alt_instr { |
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46 | s32 instr_offset; /* original instruction */ |
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47 | s32 repl_offset; /* offset to replacement instruction */ |
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48 | u16 cpuid; /* cpuid bit set for replacement */ |
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49 | u8 instrlen; /* length of original instruction */ |
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50 | u8 replacementlen; /* length of new instruction, <= instrlen */ |
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51 | }; |
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52 | |||
53 | extern void alternative_instructions(void); |
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54 | extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); |
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55 | |||
56 | struct module; |
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57 | |||
58 | #ifdef CONFIG_SMP |
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59 | extern void alternatives_smp_module_add(struct module *mod, char *name, |
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60 | void *locks, void *locks_end, |
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61 | void *text, void *text_end); |
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62 | extern void alternatives_smp_module_del(struct module *mod); |
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63 | extern void alternatives_enable_smp(void); |
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64 | extern int alternatives_text_reserved(void *start, void *end); |
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65 | extern bool skip_smp_alternatives; |
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66 | #else |
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67 | static inline void alternatives_smp_module_add(struct module *mod, char *name, |
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68 | void *locks, void *locks_end, |
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69 | void *text, void *text_end) {} |
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70 | static inline void alternatives_smp_module_del(struct module *mod) {} |
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71 | static inline void alternatives_enable_smp(void) {} |
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72 | static inline int alternatives_text_reserved(void *start, void *end) |
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73 | { |
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74 | return 0; |
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75 | } |
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76 | #endif /* CONFIG_SMP */ |
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77 | |||
78 | #define OLDINSTR(oldinstr) "661:\n\t" oldinstr "\n662:\n" |
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79 | |||
80 | #define b_replacement(number) "663"#number |
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81 | #define e_replacement(number) "664"#number |
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82 | |||
83 | #define alt_slen "662b-661b" |
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84 | #define alt_rlen(number) e_replacement(number)"f-"b_replacement(number)"f" |
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85 | |||
86 | #define ALTINSTR_ENTRY(feature, number) \ |
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87 | " .long 661b - .\n" /* label */ \ |
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88 | " .long " b_replacement(number)"f - .\n" /* new instruction */ \ |
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89 | " .word " __stringify(feature) "\n" /* feature bit */ \ |
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90 | " .byte " alt_slen "\n" /* source len */ \ |
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91 | " .byte " alt_rlen(number) "\n" /* replacement len */ |
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92 | |||
93 | #define DISCARD_ENTRY(number) /* rlen <= slen */ \ |
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94 | " .byte 0xff + (" alt_rlen(number) ") - (" alt_slen ")\n" |
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95 | |||
96 | #define ALTINSTR_REPLACEMENT(newinstr, feature, number) /* replacement */ \ |
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97 | b_replacement(number)":\n\t" newinstr "\n" e_replacement(number) ":\n\t" |
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98 | |||
99 | /* alternative assembly primitive: */ |
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100 | #define ALTERNATIVE(oldinstr, newinstr, feature) \ |
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101 | OLDINSTR(oldinstr) \ |
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102 | ".pushsection .altinstructions,\"a\"\n" \ |
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103 | ALTINSTR_ENTRY(feature, 1) \ |
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104 | ".popsection\n" \ |
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105 | ".pushsection .discard,\"aw\",@progbits\n" \ |
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106 | DISCARD_ENTRY(1) \ |
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107 | ".popsection\n" \ |
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108 | ".pushsection .altinstr_replacement, \"ax\"\n" \ |
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109 | ALTINSTR_REPLACEMENT(newinstr, feature, 1) \ |
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110 | ".popsection" |
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111 | |||
112 | #define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\ |
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113 | OLDINSTR(oldinstr) \ |
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114 | ".pushsection .altinstructions,\"a\"\n" \ |
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115 | ALTINSTR_ENTRY(feature1, 1) \ |
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116 | ALTINSTR_ENTRY(feature2, 2) \ |
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117 | ".popsection\n" \ |
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118 | ".pushsection .discard,\"aw\",@progbits\n" \ |
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119 | DISCARD_ENTRY(1) \ |
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120 | DISCARD_ENTRY(2) \ |
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121 | ".popsection\n" \ |
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122 | ".pushsection .altinstr_replacement, \"ax\"\n" \ |
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123 | ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \ |
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124 | ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \ |
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125 | ".popsection" |
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126 | |||
127 | /* |
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128 | * This must be included *after* the definition of ALTERNATIVE due to |
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129 | * |
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130 | */ |
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131 | #include |
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132 | |||
133 | /* |
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134 | * Alternative instructions for different CPU types or capabilities. |
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135 | * |
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136 | * This allows to use optimized instructions even on generic binary |
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137 | * kernels. |
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138 | * |
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139 | * length of oldinstr must be longer or equal the length of newinstr |
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140 | * It can be padded with nops as needed. |
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141 | * |
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142 | * For non barrier like inlines please define new variants |
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143 | * without volatile and memory clobber. |
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144 | */ |
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145 | #define alternative(oldinstr, newinstr, feature) \ |
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146 | asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory") |
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147 | |||
148 | /* |
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149 | * Alternative inline assembly with input. |
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150 | * |
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151 | * Pecularities: |
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152 | * No memory clobber here. |
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153 | * Argument numbers start with 1. |
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154 | * Best is to use constraints that are fixed size (like (%1) ... "r") |
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155 | * If you use variable sized constraints like "m" or "g" in the |
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156 | * replacement make sure to pad to the worst case length. |
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157 | * Leaving an unused argument 0 to keep API compatibility. |
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158 | */ |
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159 | #define alternative_input(oldinstr, newinstr, feature, input...) \ |
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160 | asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \ |
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161 | : : "i" (0), ## input) |
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162 | |||
163 | /* |
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164 | * This is similar to alternative_input. But it has two features and |
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165 | * respective instructions. |
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166 | * |
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167 | * If CPU has feature2, newinstr2 is used. |
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168 | * Otherwise, if CPU has feature1, newinstr1 is used. |
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169 | * Otherwise, oldinstr is used. |
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170 | */ |
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171 | #define alternative_input_2(oldinstr, newinstr1, feature1, newinstr2, \ |
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172 | feature2, input...) \ |
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173 | asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, \ |
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174 | newinstr2, feature2) \ |
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175 | : : "i" (0), ## input) |
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176 | |||
177 | /* Like alternative_input, but with a single output argument */ |
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178 | #define alternative_io(oldinstr, newinstr, feature, output, input...) \ |
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179 | asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \ |
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180 | : output : "i" (0), ## input) |
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181 | |||
182 | /* Like alternative_io, but for replacing a direct call with another one. */ |
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183 | #define alternative_call(oldfunc, newfunc, feature, output, input...) \ |
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184 | asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \ |
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185 | : output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input) |
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186 | |||
187 | /* |
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188 | * Like alternative_call, but there are two features and respective functions. |
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189 | * If CPU has feature2, function2 is used. |
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190 | * Otherwise, if CPU has feature1, function1 is used. |
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191 | * Otherwise, old function is used. |
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192 | */ |
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193 | #define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2, \ |
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194 | output, input...) \ |
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195 | asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\ |
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196 | "call %P[new2]", feature2) \ |
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197 | : output : [old] "i" (oldfunc), [new1] "i" (newfunc1), \ |
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198 | [new2] "i" (newfunc2), ## input) |
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199 | |||
200 | /* |
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201 | * use this macro(s) if you need more than one output parameter |
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202 | * in alternative_io |
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203 | */ |
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204 | #define ASM_OUTPUT2(a...) a |
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205 | |||
206 | /* |
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207 | * use this macro if you need clobbers but no inputs in |
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208 | * alternative_{input,io,call}() |
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209 | */ |
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210 | #define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr |
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211 | |||
212 | struct paravirt_patch_site; |
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213 | #ifdef CONFIG_PARAVIRT |
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214 | void apply_paravirt(struct paravirt_patch_site *start, |
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215 | struct paravirt_patch_site *end); |
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216 | #else |
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217 | static inline void apply_paravirt(struct paravirt_patch_site *start, |
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218 | struct paravirt_patch_site *end) |
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219 | {} |
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220 | #define __parainstructions NULL |
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221 | #define __parainstructions_end NULL |
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222 | #endif |
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223 | |||
224 | extern void *text_poke_early(void *addr, const void *opcode, size_t len); |
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225 | |||
226 | /* |
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227 | * Clear and restore the kernel write-protection flag on the local CPU. |
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228 | * Allows the kernel to edit read-only pages. |
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229 | * Side-effect: any interrupt handler running between save and restore will have |
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230 | * the ability to write to read-only pages. |
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231 | * |
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232 | * Warning: |
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233 | * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and |
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234 | * no thread can be preempted in the instructions being modified (no iret to an |
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235 | * invalid instruction possible) or if the instructions are changed from a |
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236 | * consistent state to another consistent state atomically. |
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237 | * On the local CPU you need to be protected again NMI or MCE handlers seeing an |
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238 | * inconsistent instruction while you patch. |
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239 | */ |
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240 | extern void *text_poke(void *addr, const void *opcode, size_t len); |
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241 | extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler); |
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242 | |||
243 | #endif /* _ASM_X86_ALTERNATIVE_H */=>=> |