1 /* Kernel module help for PPC. 2 Copyright (C) 2001 Rusty Russell. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software 16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 */ 18 #include <linux/module.h> 19 #include <linux/moduleloader.h> 20 #include <linux/elf.h> 21 #include <linux/vmalloc.h> 22 #include <linux/fs.h> 23 #include <linux/string.h> 24 #include <linux/kernel.h> 25 #include <linux/cache.h> 26 #include <linux/bug.h> 27 #include <linux/sort.h> 28 29 #include "setup.h" 30 31 #if 0 32 #define DEBUGP printk 33 #else 34 #define DEBUGP(fmt , ...) 35 #endif 36 37 LIST_HEAD(module_bug_list); 38 39 void *module_alloc(unsigned long size) 40 { 41 if (size == 0) 42 return NULL; 43 return vmalloc(size); 44 } 45 46 /* Free memory returned from module_alloc */ 47 void module_free(struct module *mod, void *module_region) 48 { 49 vfree(module_region); 50 /* FIXME: If module_region == mod->init_region, trim exception 51 table entries. */ 52 } 53 54 /* Count how many different relocations (different symbol, different 55 addend) */ 56 static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) 57 { 58 unsigned int i, r_info, r_addend, _count_relocs; 59 60 _count_relocs = 0; 61 r_info = 0; 62 r_addend = 0; 63 for (i = 0; i < num; i++) 64 /* Only count 24-bit relocs, others don't need stubs */ 65 if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 && 66 (r_info != ELF32_R_SYM(rela[i].r_info) || 67 r_addend != rela[i].r_addend)) { 68 _count_relocs++; 69 r_info = ELF32_R_SYM(rela[i].r_info); 70 r_addend = rela[i].r_addend; 71 } 72 73 return _count_relocs; 74 } 75 76 static int relacmp(const void *_x, const void *_y) 77 { 78 const Elf32_Rela *x, *y; 79 80 y = (Elf32_Rela *)_x; 81 x = (Elf32_Rela *)_y; 82 83 /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to 84 * make the comparison cheaper/faster. It won't affect the sorting or 85 * the counting algorithms' performance 86 */ 87 if (x->r_info < y->r_info) 88 return -1; 89 else if (x->r_info > y->r_info) 90 return 1; 91 else if (x->r_addend < y->r_addend) 92 return -1; 93 else if (x->r_addend > y->r_addend) 94 return 1; 95 else 96 return 0; 97 } 98 99 static void relaswap(void *_x, void *_y, int size) 100 { 101 uint32_t *x, *y, tmp; 102 int i; 103 104 y = (uint32_t *)_x; 105 x = (uint32_t *)_y; 106 107 for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) { 108 tmp = x[i]; 109 x[i] = y[i]; 110 y[i] = tmp; 111 } 112 } 113 114 /* Get the potential trampolines size required of the init and 115 non-init sections */ 116 static unsigned long get_plt_size(const Elf32_Ehdr *hdr, 117 const Elf32_Shdr *sechdrs, 118 const char *secstrings, 119 int is_init) 120 { 121 unsigned long ret = 0; 122 unsigned i; 123 124 /* Everything marked ALLOC (this includes the exported 125 symbols) */ 126 for (i = 1; i < hdr->e_shnum; i++) { 127 /* If it's called *.init*, and we're not init, we're 128 not interested */ 129 if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) 130 != is_init) 131 continue; 132 133 /* We don't want to look at debug sections. */ 134 if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) 135 continue; 136 137 if (sechdrs[i].sh_type == SHT_RELA) { 138 DEBUGP("Found relocations in section %u\n", i); 139 DEBUGP("Ptr: %p. Number: %u\n", 140 (void *)hdr + sechdrs[i].sh_offset, 141 sechdrs[i].sh_size / sizeof(Elf32_Rela)); 142 143 /* Sort the relocation information based on a symbol and 144 * addend key. This is a stable O(n*log n) complexity 145 * alogrithm but it will reduce the complexity of 146 * count_relocs() to linear complexity O(n) 147 */ 148 sort((void *)hdr + sechdrs[i].sh_offset, 149 sechdrs[i].sh_size / sizeof(Elf32_Rela), 150 sizeof(Elf32_Rela), relacmp, relaswap); 151 152 ret += count_relocs((void *)hdr 153 + sechdrs[i].sh_offset, 154 sechdrs[i].sh_size 155 / sizeof(Elf32_Rela)) 156 * sizeof(struct ppc_plt_entry); 157 } 158 } 159 160 return ret; 161 } 162 163 int module_frob_arch_sections(Elf32_Ehdr *hdr, 164 Elf32_Shdr *sechdrs, 165 char *secstrings, 166 struct module *me) 167 { 168 unsigned int i; 169 170 /* Find .plt and .init.plt sections */ 171 for (i = 0; i < hdr->e_shnum; i++) { 172 if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) 173 me->arch.init_plt_section = i; 174 else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) 175 me->arch.core_plt_section = i; 176 } 177 if (!me->arch.core_plt_section || !me->arch.init_plt_section) { 178 printk("Module doesn't contain .plt or .init.plt sections.\n"); 179 return -ENOEXEC; 180 } 181 182 /* Override their sizes */ 183 sechdrs[me->arch.core_plt_section].sh_size 184 = get_plt_size(hdr, sechdrs, secstrings, 0); 185 sechdrs[me->arch.init_plt_section].sh_size 186 = get_plt_size(hdr, sechdrs, secstrings, 1); 187 return 0; 188 } 189 190 int apply_relocate(Elf32_Shdr *sechdrs, 191 const char *strtab, 192 unsigned int symindex, 193 unsigned int relsec, 194 struct module *module) 195 { 196 printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", 197 module->name); 198 return -ENOEXEC; 199 } 200 201 static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) 202 { 203 if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16) 204 && entry->jump[1] == 0x396b0000 + (val & 0xffff)) 205 return 1; 206 return 0; 207 } 208 209 /* Set up a trampoline in the PLT to bounce us to the distant function */ 210 static uint32_t do_plt_call(void *location, 211 Elf32_Addr val, 212 Elf32_Shdr *sechdrs, 213 struct module *mod) 214 { 215 struct ppc_plt_entry *entry; 216 217 DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); 218 /* Init, or core PLT? */ 219 if (location >= mod->module_core 220 && location < mod->module_core + mod->core_size) 221 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; 222 else 223 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 224 225 /* Find this entry, or if that fails, the next avail. entry */ 226 while (entry->jump[0]) { 227 if (entry_matches(entry, val)) return (uint32_t)entry; 228 entry++; 229 } 230 231 /* Stolen from Paul Mackerras as well... */ 232 entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */ 233 entry->jump[1] = 0x396b0000 + (val&0xffff); /* addi r11,r11,sym@l*/ 234 entry->jump[2] = 0x7d6903a6; /* mtctr r11 */ 235 entry->jump[3] = 0x4e800420; /* bctr */ 236 237 DEBUGP("Initialized plt for 0x%x at %p\n", val, entry); 238 return (uint32_t)entry; 239 } 240 241 int apply_relocate_add(Elf32_Shdr *sechdrs, 242 const char *strtab, 243 unsigned int symindex, 244 unsigned int relsec, 245 struct module *module) 246 { 247 unsigned int i; 248 Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; 249 Elf32_Sym *sym; 250 uint32_t *location; 251 uint32_t value; 252 253 DEBUGP("Applying ADD relocate section %u to %u\n", relsec, 254 sechdrs[relsec].sh_info); 255 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 256 /* This is where to make the change */ 257 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 258 + rela[i].r_offset; 259 /* This is the symbol it is referring to. Note that all 260 undefined symbols have been resolved. */ 261 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 262 + ELF32_R_SYM(rela[i].r_info); 263 /* `Everything is relative'. */ 264 value = sym->st_value + rela[i].r_addend; 265 266 switch (ELF32_R_TYPE(rela[i].r_info)) { 267 case R_PPC_ADDR32: 268 /* Simply set it */ 269 *(uint32_t *)location = value; 270 break; 271 272 case R_PPC_ADDR16_LO: 273 /* Low half of the symbol */ 274 *(uint16_t *)location = value; 275 break; 276 277 case R_PPC_ADDR16_HI: 278 /* Higher half of the symbol */ 279 *(uint16_t *)location = (value >> 16); 280 break; 281 282 case R_PPC_ADDR16_HA: 283 /* Sign-adjusted lower 16 bits: PPC ELF ABI says: 284 (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. 285 This is the same, only sane. 286 */ 287 *(uint16_t *)location = (value + 0x8000) >> 16; 288 break; 289 290 case R_PPC_REL24: 291 if ((int)(value - (uint32_t)location) < -0x02000000 292 || (int)(value - (uint32_t)location) >= 0x02000000) 293 value = do_plt_call(location, value, 294 sechdrs, module); 295 296 /* Only replace bits 2 through 26 */ 297 DEBUGP("REL24 value = %08X. location = %08X\n", 298 value, (uint32_t)location); 299 DEBUGP("Location before: %08X.\n", 300 *(uint32_t *)location); 301 *(uint32_t *)location 302 = (*(uint32_t *)location & ~0x03fffffc) 303 | ((value - (uint32_t)location) 304 & 0x03fffffc); 305 DEBUGP("Location after: %08X.\n", 306 *(uint32_t *)location); 307 DEBUGP("ie. jump to %08X+%08X = %08X\n", 308 *(uint32_t *)location & 0x03fffffc, 309 (uint32_t)location, 310 (*(uint32_t *)location & 0x03fffffc) 311 + (uint32_t)location); 312 break; 313 314 case R_PPC_REL32: 315 /* 32-bit relative jump. */ 316 *(uint32_t *)location = value - (uint32_t)location; 317 break; 318 319 default: 320 printk("%s: unknown ADD relocation: %u\n", 321 module->name, 322 ELF32_R_TYPE(rela[i].r_info)); 323 return -ENOEXEC; 324 } 325 } 326 return 0; 327 } 328 329 static const Elf_Shdr *find_section(const Elf_Ehdr *hdr, 330 const Elf_Shdr *sechdrs, 331 const char *name) 332 { 333 char *secstrings; 334 unsigned int i; 335 336 secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 337 for (i = 1; i < hdr->e_shnum; i++) 338 if (strcmp(secstrings+sechdrs[i].sh_name, name) == 0) 339 return &sechdrs[i]; 340 return NULL; 341 } 342 343 int module_finalize(const Elf_Ehdr *hdr, 344 const Elf_Shdr *sechdrs, 345 struct module *me) 346 { 347 const Elf_Shdr *sect; 348 int err; 349 350 err = module_bug_finalize(hdr, sechdrs, me); 351 if (err) /* never true, currently */ 352 return err; 353 354 /* Apply feature fixups */ 355 sect = find_section(hdr, sechdrs, "__ftr_fixup"); 356 if (sect != NULL) 357 do_feature_fixups(cur_cpu_spec->cpu_features, 358 (void *)sect->sh_addr, 359 (void *)sect->sh_addr + sect->sh_size); 360 361 return 0; 362 } 363 364 void module_arch_cleanup(struct module *mod) 365 { 366 module_bug_cleanup(mod); 367 } 368 369 struct bug_entry *module_find_bug(unsigned long bugaddr) 370 { 371 struct mod_arch_specific *mod; 372 unsigned int i; 373 struct bug_entry *bug; 374 375 list_for_each_entry(mod, &module_bug_list, bug_list) { 376 bug = mod->bug_table; 377 for (i = 0; i < mod->num_bugs; ++i, ++bug) 378 if (bugaddr == bug->bug_addr) 379 return bug; 380 } 381 return NULL; 382 } 383