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 28 #include "setup.h" 29 30 #if 0 31 #define DEBUGP printk 32 #else 33 #define DEBUGP(fmt , ...) 34 #endif 35 36 LIST_HEAD(module_bug_list); 37 38 void *module_alloc(unsigned long size) 39 { 40 if (size == 0) 41 return NULL; 42 return vmalloc(size); 43 } 44 45 /* Free memory returned from module_alloc */ 46 void module_free(struct module *mod, void *module_region) 47 { 48 vfree(module_region); 49 /* FIXME: If module_region == mod->init_region, trim exception 50 table entries. */ 51 } 52 53 /* Count how many different relocations (different symbol, different 54 addend) */ 55 static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) 56 { 57 unsigned int i, j, ret = 0; 58 59 /* Sure, this is order(n^2), but it's usually short, and not 60 time critical */ 61 for (i = 0; i < num; i++) { 62 for (j = 0; j < i; j++) { 63 /* If this addend appeared before, it's 64 already been counted */ 65 if (ELF32_R_SYM(rela[i].r_info) 66 == ELF32_R_SYM(rela[j].r_info) 67 && rela[i].r_addend == rela[j].r_addend) 68 break; 69 } 70 if (j == i) ret++; 71 } 72 return ret; 73 } 74 75 /* Get the potential trampolines size required of the init and 76 non-init sections */ 77 static unsigned long get_plt_size(const Elf32_Ehdr *hdr, 78 const Elf32_Shdr *sechdrs, 79 const char *secstrings, 80 int is_init) 81 { 82 unsigned long ret = 0; 83 unsigned i; 84 85 /* Everything marked ALLOC (this includes the exported 86 symbols) */ 87 for (i = 1; i < hdr->e_shnum; i++) { 88 /* If it's called *.init*, and we're not init, we're 89 not interested */ 90 if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) 91 != is_init) 92 continue; 93 94 /* We don't want to look at debug sections. */ 95 if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) 96 continue; 97 98 if (sechdrs[i].sh_type == SHT_RELA) { 99 DEBUGP("Found relocations in section %u\n", i); 100 DEBUGP("Ptr: %p. Number: %u\n", 101 (void *)hdr + sechdrs[i].sh_offset, 102 sechdrs[i].sh_size / sizeof(Elf32_Rela)); 103 ret += count_relocs((void *)hdr 104 + sechdrs[i].sh_offset, 105 sechdrs[i].sh_size 106 / sizeof(Elf32_Rela)) 107 * sizeof(struct ppc_plt_entry); 108 } 109 } 110 111 return ret; 112 } 113 114 int module_frob_arch_sections(Elf32_Ehdr *hdr, 115 Elf32_Shdr *sechdrs, 116 char *secstrings, 117 struct module *me) 118 { 119 unsigned int i; 120 121 /* Find .plt and .init.plt sections */ 122 for (i = 0; i < hdr->e_shnum; i++) { 123 if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) 124 me->arch.init_plt_section = i; 125 else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) 126 me->arch.core_plt_section = i; 127 } 128 if (!me->arch.core_plt_section || !me->arch.init_plt_section) { 129 printk("Module doesn't contain .plt or .init.plt sections.\n"); 130 return -ENOEXEC; 131 } 132 133 /* Override their sizes */ 134 sechdrs[me->arch.core_plt_section].sh_size 135 = get_plt_size(hdr, sechdrs, secstrings, 0); 136 sechdrs[me->arch.init_plt_section].sh_size 137 = get_plt_size(hdr, sechdrs, secstrings, 1); 138 return 0; 139 } 140 141 int apply_relocate(Elf32_Shdr *sechdrs, 142 const char *strtab, 143 unsigned int symindex, 144 unsigned int relsec, 145 struct module *module) 146 { 147 printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", 148 module->name); 149 return -ENOEXEC; 150 } 151 152 static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) 153 { 154 if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16) 155 && entry->jump[1] == 0x396b0000 + (val & 0xffff)) 156 return 1; 157 return 0; 158 } 159 160 /* Set up a trampoline in the PLT to bounce us to the distant function */ 161 static uint32_t do_plt_call(void *location, 162 Elf32_Addr val, 163 Elf32_Shdr *sechdrs, 164 struct module *mod) 165 { 166 struct ppc_plt_entry *entry; 167 168 DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); 169 /* Init, or core PLT? */ 170 if (location >= mod->module_core 171 && location < mod->module_core + mod->core_size) 172 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; 173 else 174 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 175 176 /* Find this entry, or if that fails, the next avail. entry */ 177 while (entry->jump[0]) { 178 if (entry_matches(entry, val)) return (uint32_t)entry; 179 entry++; 180 } 181 182 /* Stolen from Paul Mackerras as well... */ 183 entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */ 184 entry->jump[1] = 0x396b0000 + (val&0xffff); /* addi r11,r11,sym@l*/ 185 entry->jump[2] = 0x7d6903a6; /* mtctr r11 */ 186 entry->jump[3] = 0x4e800420; /* bctr */ 187 188 DEBUGP("Initialized plt for 0x%x at %p\n", val, entry); 189 return (uint32_t)entry; 190 } 191 192 int apply_relocate_add(Elf32_Shdr *sechdrs, 193 const char *strtab, 194 unsigned int symindex, 195 unsigned int relsec, 196 struct module *module) 197 { 198 unsigned int i; 199 Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; 200 Elf32_Sym *sym; 201 uint32_t *location; 202 uint32_t value; 203 204 DEBUGP("Applying ADD relocate section %u to %u\n", relsec, 205 sechdrs[relsec].sh_info); 206 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 207 /* This is where to make the change */ 208 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 209 + rela[i].r_offset; 210 /* This is the symbol it is referring to. Note that all 211 undefined symbols have been resolved. */ 212 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 213 + ELF32_R_SYM(rela[i].r_info); 214 /* `Everything is relative'. */ 215 value = sym->st_value + rela[i].r_addend; 216 217 switch (ELF32_R_TYPE(rela[i].r_info)) { 218 case R_PPC_ADDR32: 219 /* Simply set it */ 220 *(uint32_t *)location = value; 221 break; 222 223 case R_PPC_ADDR16_LO: 224 /* Low half of the symbol */ 225 *(uint16_t *)location = value; 226 break; 227 228 case R_PPC_ADDR16_HI: 229 /* Higher half of the symbol */ 230 *(uint16_t *)location = (value >> 16); 231 break; 232 233 case R_PPC_ADDR16_HA: 234 /* Sign-adjusted lower 16 bits: PPC ELF ABI says: 235 (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. 236 This is the same, only sane. 237 */ 238 *(uint16_t *)location = (value + 0x8000) >> 16; 239 break; 240 241 case R_PPC_REL24: 242 if ((int)(value - (uint32_t)location) < -0x02000000 243 || (int)(value - (uint32_t)location) >= 0x02000000) 244 value = do_plt_call(location, value, 245 sechdrs, module); 246 247 /* Only replace bits 2 through 26 */ 248 DEBUGP("REL24 value = %08X. location = %08X\n", 249 value, (uint32_t)location); 250 DEBUGP("Location before: %08X.\n", 251 *(uint32_t *)location); 252 *(uint32_t *)location 253 = (*(uint32_t *)location & ~0x03fffffc) 254 | ((value - (uint32_t)location) 255 & 0x03fffffc); 256 DEBUGP("Location after: %08X.\n", 257 *(uint32_t *)location); 258 DEBUGP("ie. jump to %08X+%08X = %08X\n", 259 *(uint32_t *)location & 0x03fffffc, 260 (uint32_t)location, 261 (*(uint32_t *)location & 0x03fffffc) 262 + (uint32_t)location); 263 break; 264 265 case R_PPC_REL32: 266 /* 32-bit relative jump. */ 267 *(uint32_t *)location = value - (uint32_t)location; 268 break; 269 270 default: 271 printk("%s: unknown ADD relocation: %u\n", 272 module->name, 273 ELF32_R_TYPE(rela[i].r_info)); 274 return -ENOEXEC; 275 } 276 } 277 return 0; 278 } 279 280 static const Elf_Shdr *find_section(const Elf_Ehdr *hdr, 281 const Elf_Shdr *sechdrs, 282 const char *name) 283 { 284 char *secstrings; 285 unsigned int i; 286 287 secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 288 for (i = 1; i < hdr->e_shnum; i++) 289 if (strcmp(secstrings+sechdrs[i].sh_name, name) == 0) 290 return &sechdrs[i]; 291 return NULL; 292 } 293 294 int module_finalize(const Elf_Ehdr *hdr, 295 const Elf_Shdr *sechdrs, 296 struct module *me) 297 { 298 const Elf_Shdr *sect; 299 int err; 300 301 err = module_bug_finalize(hdr, sechdrs, me); 302 if (err) /* never true, currently */ 303 return err; 304 305 /* Apply feature fixups */ 306 sect = find_section(hdr, sechdrs, "__ftr_fixup"); 307 if (sect != NULL) 308 do_feature_fixups(cur_cpu_spec->cpu_features, 309 (void *)sect->sh_addr, 310 (void *)sect->sh_addr + sect->sh_size); 311 312 return 0; 313 } 314 315 void module_arch_cleanup(struct module *mod) 316 { 317 module_bug_cleanup(mod); 318 } 319 320 struct bug_entry *module_find_bug(unsigned long bugaddr) 321 { 322 struct mod_arch_specific *mod; 323 unsigned int i; 324 struct bug_entry *bug; 325 326 list_for_each_entry(mod, &module_bug_list, bug_list) { 327 bug = mod->bug_table; 328 for (i = 0; i < mod->num_bugs; ++i, ++bug) 329 if (bugaddr == bug->bug_addr) 330 return bug; 331 } 332 return NULL; 333 } 334