Hi Ard, I love your patch! Yet something to improve:
[auto build test ERROR on linus/master] [also build test ERROR on v4.18-rc3 next-20180702] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Ard-Biesheuvel/add-support-for-relative-references-in-jump-tables/20180703-031712 config: um-x86_64_defconfig (attached as .config) compiler: gcc-7 (Debian 7.3.0-16) 7.3.0 reproduce: # save the attached .config to linux build tree make ARCH=um SUBARCH=x86_64 All errors (new ones prefixed by >>): arch/x86/um/../kernel/module.c: In function 'apply_relocate_add': >> arch/x86/um/../kernel/module.c:204:8: error: 'R_X86_64_PC64' undeclared >> (first use in this function); did you mean 'R_X86_64_PC16'? case R_X86_64_PC64: ^~~~~~~~~~~~~ R_X86_64_PC16 arch/x86/um/../kernel/module.c:204:8: note: each undeclared identifier is reported only once for each function it appears in vim +204 arch/x86/um/../kernel/module.c 99 100 #ifdef CONFIG_X86_32 101 int apply_relocate(Elf32_Shdr *sechdrs, 102 const char *strtab, 103 unsigned int symindex, 104 unsigned int relsec, 105 struct module *me) 106 { 107 unsigned int i; 108 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr; 109 Elf32_Sym *sym; 110 uint32_t *location; 111 112 DEBUGP("Applying relocate section %u to %u\n", 113 relsec, sechdrs[relsec].sh_info); 114 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 115 /* This is where to make the change */ 116 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 117 + rel[i].r_offset; 118 /* This is the symbol it is referring to. Note that all 119 undefined symbols have been resolved. */ 120 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 121 + ELF32_R_SYM(rel[i].r_info); 122 123 switch (ELF32_R_TYPE(rel[i].r_info)) { 124 case R_386_32: 125 /* We add the value into the location given */ 126 *location += sym->st_value; 127 break; 128 case R_386_PC32: 129 /* Add the value, subtract its position */ 130 *location += sym->st_value - (uint32_t)location; 131 break; 132 default: 133 pr_err("%s: Unknown relocation: %u\n", 134 me->name, ELF32_R_TYPE(rel[i].r_info)); 135 return -ENOEXEC; 136 } 137 } 138 return 0; 139 } 140 #else /*X86_64*/ 141 int apply_relocate_add(Elf64_Shdr *sechdrs, 142 const char *strtab, 143 unsigned int symindex, 144 unsigned int relsec, 145 struct module *me) 146 { 147 unsigned int i; 148 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; 149 Elf64_Sym *sym; 150 void *loc; 151 u64 val; 152 153 DEBUGP("Applying relocate section %u to %u\n", 154 relsec, sechdrs[relsec].sh_info); 155 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 156 /* This is where to make the change */ 157 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 158 + rel[i].r_offset; 159 160 /* This is the symbol it is referring to. Note that all 161 undefined symbols have been resolved. */ 162 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr 163 + ELF64_R_SYM(rel[i].r_info); 164 165 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n", 166 (int)ELF64_R_TYPE(rel[i].r_info), 167 sym->st_value, rel[i].r_addend, (u64)loc); 168 169 val = sym->st_value + rel[i].r_addend; 170 171 switch (ELF64_R_TYPE(rel[i].r_info)) { 172 case R_X86_64_NONE: 173 break; 174 case R_X86_64_64: 175 if (*(u64 *)loc != 0) 176 goto invalid_relocation; 177 *(u64 *)loc = val; 178 break; 179 case R_X86_64_32: 180 if (*(u32 *)loc != 0) 181 goto invalid_relocation; 182 *(u32 *)loc = val; 183 if (val != *(u32 *)loc) 184 goto overflow; 185 break; 186 case R_X86_64_32S: 187 if (*(s32 *)loc != 0) 188 goto invalid_relocation; 189 *(s32 *)loc = val; 190 if ((s64)val != *(s32 *)loc) 191 goto overflow; 192 break; 193 case R_X86_64_PC32: 194 case R_X86_64_PLT32: 195 if (*(u32 *)loc != 0) 196 goto invalid_relocation; 197 val -= (u64)loc; 198 *(u32 *)loc = val; 199 #if 0 200 if ((s64)val != *(s32 *)loc) 201 goto overflow; 202 #endif 203 break; > 204 case R_X86_64_PC64: 205 if (*(u64 *)loc != 0) 206 goto invalid_relocation; 207 val -= (u64)loc; 208 *(u64 *)loc = val; 209 break; 210 default: 211 pr_err("%s: Unknown rela relocation: %llu\n", 212 me->name, ELF64_R_TYPE(rel[i].r_info)); 213 return -ENOEXEC; 214 } 215 } 216 return 0; 217 218 invalid_relocation: 219 pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n", 220 (int)ELF64_R_TYPE(rel[i].r_info), loc, val); 221 return -ENOEXEC; 222 223 overflow: 224 pr_err("overflow in relocation type %d val %Lx\n", 225 (int)ELF64_R_TYPE(rel[i].r_info), val); 226 pr_err("`%s' likely not compiled with -mcmodel=kernel\n", 227 me->name); 228 return -ENOEXEC; 229 } 230 #endif 231 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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