1ed981856SPaul Mackerras /* Kernel module help for PPC. 2ed981856SPaul Mackerras Copyright (C) 2001 Rusty Russell. 3ed981856SPaul Mackerras 4ed981856SPaul Mackerras This program is free software; you can redistribute it and/or modify 5ed981856SPaul Mackerras it under the terms of the GNU General Public License as published by 6ed981856SPaul Mackerras the Free Software Foundation; either version 2 of the License, or 7ed981856SPaul Mackerras (at your option) any later version. 8ed981856SPaul Mackerras 9ed981856SPaul Mackerras This program is distributed in the hope that it will be useful, 10ed981856SPaul Mackerras but WITHOUT ANY WARRANTY; without even the implied warranty of 11ed981856SPaul Mackerras MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12ed981856SPaul Mackerras GNU General Public License for more details. 13ed981856SPaul Mackerras 14ed981856SPaul Mackerras You should have received a copy of the GNU General Public License 15ed981856SPaul Mackerras along with this program; if not, write to the Free Software 16ed981856SPaul Mackerras Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17ed981856SPaul Mackerras */ 18ed981856SPaul Mackerras #include <linux/module.h> 19ed981856SPaul Mackerras #include <linux/moduleloader.h> 20ed981856SPaul Mackerras #include <linux/elf.h> 21ed981856SPaul Mackerras #include <linux/vmalloc.h> 22ed981856SPaul Mackerras #include <linux/fs.h> 23ed981856SPaul Mackerras #include <linux/string.h> 24ed981856SPaul Mackerras #include <linux/kernel.h> 25ed981856SPaul Mackerras #include <linux/cache.h> 26ed981856SPaul Mackerras 27ed981856SPaul Mackerras #if 0 28ed981856SPaul Mackerras #define DEBUGP printk 29ed981856SPaul Mackerras #else 30ed981856SPaul Mackerras #define DEBUGP(fmt , ...) 31ed981856SPaul Mackerras #endif 32ed981856SPaul Mackerras 33ed981856SPaul Mackerras LIST_HEAD(module_bug_list); 34ed981856SPaul Mackerras 35ed981856SPaul Mackerras void *module_alloc(unsigned long size) 36ed981856SPaul Mackerras { 37ed981856SPaul Mackerras if (size == 0) 38ed981856SPaul Mackerras return NULL; 39ed981856SPaul Mackerras return vmalloc(size); 40ed981856SPaul Mackerras } 41ed981856SPaul Mackerras 42ed981856SPaul Mackerras /* Free memory returned from module_alloc */ 43ed981856SPaul Mackerras void module_free(struct module *mod, void *module_region) 44ed981856SPaul Mackerras { 45ed981856SPaul Mackerras vfree(module_region); 46ed981856SPaul Mackerras /* FIXME: If module_region == mod->init_region, trim exception 47ed981856SPaul Mackerras table entries. */ 48ed981856SPaul Mackerras } 49ed981856SPaul Mackerras 50ed981856SPaul Mackerras /* Count how many different relocations (different symbol, different 51ed981856SPaul Mackerras addend) */ 52ed981856SPaul Mackerras static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) 53ed981856SPaul Mackerras { 54ed981856SPaul Mackerras unsigned int i, j, ret = 0; 55ed981856SPaul Mackerras 56ed981856SPaul Mackerras /* Sure, this is order(n^2), but it's usually short, and not 57ed981856SPaul Mackerras time critical */ 58ed981856SPaul Mackerras for (i = 0; i < num; i++) { 59ed981856SPaul Mackerras for (j = 0; j < i; j++) { 60ed981856SPaul Mackerras /* If this addend appeared before, it's 61ed981856SPaul Mackerras already been counted */ 62ed981856SPaul Mackerras if (ELF32_R_SYM(rela[i].r_info) 63ed981856SPaul Mackerras == ELF32_R_SYM(rela[j].r_info) 64ed981856SPaul Mackerras && rela[i].r_addend == rela[j].r_addend) 65ed981856SPaul Mackerras break; 66ed981856SPaul Mackerras } 67ed981856SPaul Mackerras if (j == i) ret++; 68ed981856SPaul Mackerras } 69ed981856SPaul Mackerras return ret; 70ed981856SPaul Mackerras } 71ed981856SPaul Mackerras 72ed981856SPaul Mackerras /* Get the potential trampolines size required of the init and 73ed981856SPaul Mackerras non-init sections */ 74ed981856SPaul Mackerras static unsigned long get_plt_size(const Elf32_Ehdr *hdr, 75ed981856SPaul Mackerras const Elf32_Shdr *sechdrs, 76ed981856SPaul Mackerras const char *secstrings, 77ed981856SPaul Mackerras int is_init) 78ed981856SPaul Mackerras { 79ed981856SPaul Mackerras unsigned long ret = 0; 80ed981856SPaul Mackerras unsigned i; 81ed981856SPaul Mackerras 82ed981856SPaul Mackerras /* Everything marked ALLOC (this includes the exported 83ed981856SPaul Mackerras symbols) */ 84ed981856SPaul Mackerras for (i = 1; i < hdr->e_shnum; i++) { 85ed981856SPaul Mackerras /* If it's called *.init*, and we're not init, we're 86ed981856SPaul Mackerras not interested */ 87ed981856SPaul Mackerras if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) 88ed981856SPaul Mackerras != is_init) 89ed981856SPaul Mackerras continue; 90ed981856SPaul Mackerras 91ed981856SPaul Mackerras /* We don't want to look at debug sections. */ 92ed981856SPaul Mackerras if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) 93ed981856SPaul Mackerras continue; 94ed981856SPaul Mackerras 95ed981856SPaul Mackerras if (sechdrs[i].sh_type == SHT_RELA) { 96ed981856SPaul Mackerras DEBUGP("Found relocations in section %u\n", i); 97ed981856SPaul Mackerras DEBUGP("Ptr: %p. Number: %u\n", 98ed981856SPaul Mackerras (void *)hdr + sechdrs[i].sh_offset, 99ed981856SPaul Mackerras sechdrs[i].sh_size / sizeof(Elf32_Rela)); 100ed981856SPaul Mackerras ret += count_relocs((void *)hdr 101ed981856SPaul Mackerras + sechdrs[i].sh_offset, 102ed981856SPaul Mackerras sechdrs[i].sh_size 103ed981856SPaul Mackerras / sizeof(Elf32_Rela)) 104ed981856SPaul Mackerras * sizeof(struct ppc_plt_entry); 105ed981856SPaul Mackerras } 106ed981856SPaul Mackerras } 107ed981856SPaul Mackerras 108ed981856SPaul Mackerras return ret; 109ed981856SPaul Mackerras } 110ed981856SPaul Mackerras 111ed981856SPaul Mackerras int module_frob_arch_sections(Elf32_Ehdr *hdr, 112ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 113ed981856SPaul Mackerras char *secstrings, 114ed981856SPaul Mackerras struct module *me) 115ed981856SPaul Mackerras { 116ed981856SPaul Mackerras unsigned int i; 117ed981856SPaul Mackerras 118ed981856SPaul Mackerras /* Find .plt and .init.plt sections */ 119ed981856SPaul Mackerras for (i = 0; i < hdr->e_shnum; i++) { 120ed981856SPaul Mackerras if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) 121ed981856SPaul Mackerras me->arch.init_plt_section = i; 122ed981856SPaul Mackerras else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) 123ed981856SPaul Mackerras me->arch.core_plt_section = i; 124ed981856SPaul Mackerras } 125ed981856SPaul Mackerras if (!me->arch.core_plt_section || !me->arch.init_plt_section) { 126ed981856SPaul Mackerras printk("Module doesn't contain .plt or .init.plt sections.\n"); 127ed981856SPaul Mackerras return -ENOEXEC; 128ed981856SPaul Mackerras } 129ed981856SPaul Mackerras 130ed981856SPaul Mackerras /* Override their sizes */ 131ed981856SPaul Mackerras sechdrs[me->arch.core_plt_section].sh_size 132ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 0); 133ed981856SPaul Mackerras sechdrs[me->arch.init_plt_section].sh_size 134ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 1); 135ed981856SPaul Mackerras return 0; 136ed981856SPaul Mackerras } 137ed981856SPaul Mackerras 138ed981856SPaul Mackerras int apply_relocate(Elf32_Shdr *sechdrs, 139ed981856SPaul Mackerras const char *strtab, 140ed981856SPaul Mackerras unsigned int symindex, 141ed981856SPaul Mackerras unsigned int relsec, 142ed981856SPaul Mackerras struct module *module) 143ed981856SPaul Mackerras { 144ed981856SPaul Mackerras printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", 145ed981856SPaul Mackerras module->name); 146ed981856SPaul Mackerras return -ENOEXEC; 147ed981856SPaul Mackerras } 148ed981856SPaul Mackerras 149ed981856SPaul Mackerras static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) 150ed981856SPaul Mackerras { 151ed981856SPaul Mackerras if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16) 152ed981856SPaul Mackerras && entry->jump[1] == 0x396b0000 + (val & 0xffff)) 153ed981856SPaul Mackerras return 1; 154ed981856SPaul Mackerras return 0; 155ed981856SPaul Mackerras } 156ed981856SPaul Mackerras 157ed981856SPaul Mackerras /* Set up a trampoline in the PLT to bounce us to the distant function */ 158ed981856SPaul Mackerras static uint32_t do_plt_call(void *location, 159ed981856SPaul Mackerras Elf32_Addr val, 160ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 161ed981856SPaul Mackerras struct module *mod) 162ed981856SPaul Mackerras { 163ed981856SPaul Mackerras struct ppc_plt_entry *entry; 164ed981856SPaul Mackerras 165ed981856SPaul Mackerras DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); 166ed981856SPaul Mackerras /* Init, or core PLT? */ 167ed981856SPaul Mackerras if (location >= mod->module_core 168ed981856SPaul Mackerras && location < mod->module_core + mod->core_size) 169ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; 170ed981856SPaul Mackerras else 171ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 172ed981856SPaul Mackerras 173ed981856SPaul Mackerras /* Find this entry, or if that fails, the next avail. entry */ 174ed981856SPaul Mackerras while (entry->jump[0]) { 175ed981856SPaul Mackerras if (entry_matches(entry, val)) return (uint32_t)entry; 176ed981856SPaul Mackerras entry++; 177ed981856SPaul Mackerras } 178ed981856SPaul Mackerras 179ed981856SPaul Mackerras /* Stolen from Paul Mackerras as well... */ 180ed981856SPaul Mackerras entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */ 181ed981856SPaul Mackerras entry->jump[1] = 0x396b0000 + (val&0xffff); /* addi r11,r11,sym@l*/ 182ed981856SPaul Mackerras entry->jump[2] = 0x7d6903a6; /* mtctr r11 */ 183ed981856SPaul Mackerras entry->jump[3] = 0x4e800420; /* bctr */ 184ed981856SPaul Mackerras 185ed981856SPaul Mackerras DEBUGP("Initialized plt for 0x%x at %p\n", val, entry); 186ed981856SPaul Mackerras return (uint32_t)entry; 187ed981856SPaul Mackerras } 188ed981856SPaul Mackerras 189ed981856SPaul Mackerras int apply_relocate_add(Elf32_Shdr *sechdrs, 190ed981856SPaul Mackerras const char *strtab, 191ed981856SPaul Mackerras unsigned int symindex, 192ed981856SPaul Mackerras unsigned int relsec, 193ed981856SPaul Mackerras struct module *module) 194ed981856SPaul Mackerras { 195ed981856SPaul Mackerras unsigned int i; 196ed981856SPaul Mackerras Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; 197ed981856SPaul Mackerras Elf32_Sym *sym; 198ed981856SPaul Mackerras uint32_t *location; 199ed981856SPaul Mackerras uint32_t value; 200ed981856SPaul Mackerras 201ed981856SPaul Mackerras DEBUGP("Applying ADD relocate section %u to %u\n", relsec, 202ed981856SPaul Mackerras sechdrs[relsec].sh_info); 203ed981856SPaul Mackerras for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 204ed981856SPaul Mackerras /* This is where to make the change */ 205ed981856SPaul Mackerras location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 206ed981856SPaul Mackerras + rela[i].r_offset; 207ed981856SPaul Mackerras /* This is the symbol it is referring to. Note that all 208ed981856SPaul Mackerras undefined symbols have been resolved. */ 209ed981856SPaul Mackerras sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 210ed981856SPaul Mackerras + ELF32_R_SYM(rela[i].r_info); 211ed981856SPaul Mackerras /* `Everything is relative'. */ 212ed981856SPaul Mackerras value = sym->st_value + rela[i].r_addend; 213ed981856SPaul Mackerras 214ed981856SPaul Mackerras switch (ELF32_R_TYPE(rela[i].r_info)) { 215ed981856SPaul Mackerras case R_PPC_ADDR32: 216ed981856SPaul Mackerras /* Simply set it */ 217ed981856SPaul Mackerras *(uint32_t *)location = value; 218ed981856SPaul Mackerras break; 219ed981856SPaul Mackerras 220ed981856SPaul Mackerras case R_PPC_ADDR16_LO: 221ed981856SPaul Mackerras /* Low half of the symbol */ 222ed981856SPaul Mackerras *(uint16_t *)location = value; 223ed981856SPaul Mackerras break; 224ed981856SPaul Mackerras 225ed981856SPaul Mackerras case R_PPC_ADDR16_HA: 226ed981856SPaul Mackerras /* Sign-adjusted lower 16 bits: PPC ELF ABI says: 227ed981856SPaul Mackerras (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. 228ed981856SPaul Mackerras This is the same, only sane. 229ed981856SPaul Mackerras */ 230ed981856SPaul Mackerras *(uint16_t *)location = (value + 0x8000) >> 16; 231ed981856SPaul Mackerras break; 232ed981856SPaul Mackerras 233ed981856SPaul Mackerras case R_PPC_REL24: 234ed981856SPaul Mackerras if ((int)(value - (uint32_t)location) < -0x02000000 235ed981856SPaul Mackerras || (int)(value - (uint32_t)location) >= 0x02000000) 236ed981856SPaul Mackerras value = do_plt_call(location, value, 237ed981856SPaul Mackerras sechdrs, module); 238ed981856SPaul Mackerras 239ed981856SPaul Mackerras /* Only replace bits 2 through 26 */ 240ed981856SPaul Mackerras DEBUGP("REL24 value = %08X. location = %08X\n", 241ed981856SPaul Mackerras value, (uint32_t)location); 242ed981856SPaul Mackerras DEBUGP("Location before: %08X.\n", 243ed981856SPaul Mackerras *(uint32_t *)location); 244ed981856SPaul Mackerras *(uint32_t *)location 245ed981856SPaul Mackerras = (*(uint32_t *)location & ~0x03fffffc) 246ed981856SPaul Mackerras | ((value - (uint32_t)location) 247ed981856SPaul Mackerras & 0x03fffffc); 248ed981856SPaul Mackerras DEBUGP("Location after: %08X.\n", 249ed981856SPaul Mackerras *(uint32_t *)location); 250ed981856SPaul Mackerras DEBUGP("ie. jump to %08X+%08X = %08X\n", 251ed981856SPaul Mackerras *(uint32_t *)location & 0x03fffffc, 252ed981856SPaul Mackerras (uint32_t)location, 253ed981856SPaul Mackerras (*(uint32_t *)location & 0x03fffffc) 254ed981856SPaul Mackerras + (uint32_t)location); 255ed981856SPaul Mackerras break; 256ed981856SPaul Mackerras 257ed981856SPaul Mackerras case R_PPC_REL32: 258ed981856SPaul Mackerras /* 32-bit relative jump. */ 259ed981856SPaul Mackerras *(uint32_t *)location = value - (uint32_t)location; 260ed981856SPaul Mackerras break; 261ed981856SPaul Mackerras 262ed981856SPaul Mackerras default: 263ed981856SPaul Mackerras printk("%s: unknown ADD relocation: %u\n", 264ed981856SPaul Mackerras module->name, 265ed981856SPaul Mackerras ELF32_R_TYPE(rela[i].r_info)); 266ed981856SPaul Mackerras return -ENOEXEC; 267ed981856SPaul Mackerras } 268ed981856SPaul Mackerras } 269ed981856SPaul Mackerras return 0; 270ed981856SPaul Mackerras } 271ed981856SPaul Mackerras 272ed981856SPaul Mackerras int module_finalize(const Elf_Ehdr *hdr, 273ed981856SPaul Mackerras const Elf_Shdr *sechdrs, 274ed981856SPaul Mackerras struct module *me) 275ed981856SPaul Mackerras { 276ed981856SPaul Mackerras char *secstrings; 277ed981856SPaul Mackerras unsigned int i; 278ed981856SPaul Mackerras 279ed981856SPaul Mackerras me->arch.bug_table = NULL; 280ed981856SPaul Mackerras me->arch.num_bugs = 0; 281ed981856SPaul Mackerras 282ed981856SPaul Mackerras /* Find the __bug_table section, if present */ 283ed981856SPaul Mackerras secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 284ed981856SPaul Mackerras for (i = 1; i < hdr->e_shnum; i++) { 285ed981856SPaul Mackerras if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table")) 286ed981856SPaul Mackerras continue; 287ed981856SPaul Mackerras me->arch.bug_table = (void *) sechdrs[i].sh_addr; 288ed981856SPaul Mackerras me->arch.num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry); 289ed981856SPaul Mackerras break; 290ed981856SPaul Mackerras } 291ed981856SPaul Mackerras 292ed981856SPaul Mackerras /* 293ed981856SPaul Mackerras * Strictly speaking this should have a spinlock to protect against 294ed981856SPaul Mackerras * traversals, but since we only traverse on BUG()s, a spinlock 295ed981856SPaul Mackerras * could potentially lead to deadlock and thus be counter-productive. 296ed981856SPaul Mackerras */ 297ed981856SPaul Mackerras list_add(&me->arch.bug_list, &module_bug_list); 298ed981856SPaul Mackerras 299ed981856SPaul Mackerras return 0; 300ed981856SPaul Mackerras } 301ed981856SPaul Mackerras 302ed981856SPaul Mackerras void module_arch_cleanup(struct module *mod) 303ed981856SPaul Mackerras { 304ed981856SPaul Mackerras list_del(&mod->arch.bug_list); 305ed981856SPaul Mackerras } 306ed981856SPaul Mackerras 307ed981856SPaul Mackerras struct bug_entry *module_find_bug(unsigned long bugaddr) 308ed981856SPaul Mackerras { 309ed981856SPaul Mackerras struct mod_arch_specific *mod; 310ed981856SPaul Mackerras unsigned int i; 311ed981856SPaul Mackerras struct bug_entry *bug; 312ed981856SPaul Mackerras 313ed981856SPaul Mackerras list_for_each_entry(mod, &module_bug_list, bug_list) { 314ed981856SPaul Mackerras bug = mod->bug_table; 315ed981856SPaul Mackerras for (i = 0; i < mod->num_bugs; ++i, ++bug) 316ed981856SPaul Mackerras if (bugaddr == bug->bug_addr) 317ed981856SPaul Mackerras return bug; 318ed981856SPaul Mackerras } 319ed981856SPaul Mackerras return NULL; 320ed981856SPaul Mackerras } 321