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> 257cc45e64SSteven Rostedt #include <linux/ftrace.h> 26ed981856SPaul Mackerras #include <linux/cache.h> 2773c9ceabSJeremy Fitzhardinge #include <linux/bug.h> 28eda09fbdSEmil Medve #include <linux/sort.h> 29b88c4767SRobert Jennings #include <asm/setup.h> 3021c4ff80SBenjamin Herrenschmidt 31ed981856SPaul Mackerras #if 0 32ed981856SPaul Mackerras #define DEBUGP printk 33ed981856SPaul Mackerras #else 34ed981856SPaul Mackerras #define DEBUGP(fmt , ...) 35ed981856SPaul Mackerras #endif 36ed981856SPaul Mackerras 37ed981856SPaul Mackerras /* Count how many different relocations (different symbol, different 38ed981856SPaul Mackerras addend) */ 39ed981856SPaul Mackerras static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) 40ed981856SPaul Mackerras { 41eda09fbdSEmil Medve unsigned int i, r_info, r_addend, _count_relocs; 42ed981856SPaul Mackerras 43eda09fbdSEmil Medve _count_relocs = 0; 44eda09fbdSEmil Medve r_info = 0; 45eda09fbdSEmil Medve r_addend = 0; 46eda09fbdSEmil Medve for (i = 0; i < num; i++) 47eda09fbdSEmil Medve /* Only count 24-bit relocs, others don't need stubs */ 48eda09fbdSEmil Medve if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 && 49eda09fbdSEmil Medve (r_info != ELF32_R_SYM(rela[i].r_info) || 50eda09fbdSEmil Medve r_addend != rela[i].r_addend)) { 51eda09fbdSEmil Medve _count_relocs++; 52eda09fbdSEmil Medve r_info = ELF32_R_SYM(rela[i].r_info); 53eda09fbdSEmil Medve r_addend = rela[i].r_addend; 54ed981856SPaul Mackerras } 55eda09fbdSEmil Medve 567cc45e64SSteven Rostedt #ifdef CONFIG_DYNAMIC_FTRACE 577cc45e64SSteven Rostedt _count_relocs++; /* add one for ftrace_caller */ 587cc45e64SSteven Rostedt #endif 59eda09fbdSEmil Medve return _count_relocs; 60ed981856SPaul Mackerras } 61eda09fbdSEmil Medve 62eda09fbdSEmil Medve static int relacmp(const void *_x, const void *_y) 63eda09fbdSEmil Medve { 64eda09fbdSEmil Medve const Elf32_Rela *x, *y; 65eda09fbdSEmil Medve 66eda09fbdSEmil Medve y = (Elf32_Rela *)_x; 67eda09fbdSEmil Medve x = (Elf32_Rela *)_y; 68eda09fbdSEmil Medve 69eda09fbdSEmil Medve /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to 70eda09fbdSEmil Medve * make the comparison cheaper/faster. It won't affect the sorting or 71eda09fbdSEmil Medve * the counting algorithms' performance 72eda09fbdSEmil Medve */ 73eda09fbdSEmil Medve if (x->r_info < y->r_info) 74eda09fbdSEmil Medve return -1; 75eda09fbdSEmil Medve else if (x->r_info > y->r_info) 76eda09fbdSEmil Medve return 1; 77eda09fbdSEmil Medve else if (x->r_addend < y->r_addend) 78eda09fbdSEmil Medve return -1; 79eda09fbdSEmil Medve else if (x->r_addend > y->r_addend) 80eda09fbdSEmil Medve return 1; 81eda09fbdSEmil Medve else 82eda09fbdSEmil Medve return 0; 83eda09fbdSEmil Medve } 84eda09fbdSEmil Medve 85eda09fbdSEmil Medve static void relaswap(void *_x, void *_y, int size) 86eda09fbdSEmil Medve { 87eda09fbdSEmil Medve uint32_t *x, *y, tmp; 88eda09fbdSEmil Medve int i; 89eda09fbdSEmil Medve 90eda09fbdSEmil Medve y = (uint32_t *)_x; 91eda09fbdSEmil Medve x = (uint32_t *)_y; 92eda09fbdSEmil Medve 93eda09fbdSEmil Medve for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) { 94eda09fbdSEmil Medve tmp = x[i]; 95eda09fbdSEmil Medve x[i] = y[i]; 96eda09fbdSEmil Medve y[i] = tmp; 97eda09fbdSEmil Medve } 98ed981856SPaul Mackerras } 99ed981856SPaul Mackerras 100ed981856SPaul Mackerras /* Get the potential trampolines size required of the init and 101ed981856SPaul Mackerras non-init sections */ 102ed981856SPaul Mackerras static unsigned long get_plt_size(const Elf32_Ehdr *hdr, 103ed981856SPaul Mackerras const Elf32_Shdr *sechdrs, 104ed981856SPaul Mackerras const char *secstrings, 105ed981856SPaul Mackerras int is_init) 106ed981856SPaul Mackerras { 107ed981856SPaul Mackerras unsigned long ret = 0; 108ed981856SPaul Mackerras unsigned i; 109ed981856SPaul Mackerras 110ed981856SPaul Mackerras /* Everything marked ALLOC (this includes the exported 111ed981856SPaul Mackerras symbols) */ 112ed981856SPaul Mackerras for (i = 1; i < hdr->e_shnum; i++) { 113ed981856SPaul Mackerras /* If it's called *.init*, and we're not init, we're 114ed981856SPaul Mackerras not interested */ 115ed981856SPaul Mackerras if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) 116ed981856SPaul Mackerras != is_init) 117ed981856SPaul Mackerras continue; 118ed981856SPaul Mackerras 119ed981856SPaul Mackerras /* We don't want to look at debug sections. */ 120ed981856SPaul Mackerras if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) 121ed981856SPaul Mackerras continue; 122ed981856SPaul Mackerras 123ed981856SPaul Mackerras if (sechdrs[i].sh_type == SHT_RELA) { 124ed981856SPaul Mackerras DEBUGP("Found relocations in section %u\n", i); 125ed981856SPaul Mackerras DEBUGP("Ptr: %p. Number: %u\n", 126ed981856SPaul Mackerras (void *)hdr + sechdrs[i].sh_offset, 127ed981856SPaul Mackerras sechdrs[i].sh_size / sizeof(Elf32_Rela)); 128eda09fbdSEmil Medve 129eda09fbdSEmil Medve /* Sort the relocation information based on a symbol and 130eda09fbdSEmil Medve * addend key. This is a stable O(n*log n) complexity 131eda09fbdSEmil Medve * alogrithm but it will reduce the complexity of 132eda09fbdSEmil Medve * count_relocs() to linear complexity O(n) 133eda09fbdSEmil Medve */ 134eda09fbdSEmil Medve sort((void *)hdr + sechdrs[i].sh_offset, 135eda09fbdSEmil Medve sechdrs[i].sh_size / sizeof(Elf32_Rela), 136eda09fbdSEmil Medve sizeof(Elf32_Rela), relacmp, relaswap); 137eda09fbdSEmil Medve 138ed981856SPaul Mackerras ret += count_relocs((void *)hdr 139ed981856SPaul Mackerras + sechdrs[i].sh_offset, 140ed981856SPaul Mackerras sechdrs[i].sh_size 141ed981856SPaul Mackerras / sizeof(Elf32_Rela)) 142ed981856SPaul Mackerras * sizeof(struct ppc_plt_entry); 143ed981856SPaul Mackerras } 144ed981856SPaul Mackerras } 145ed981856SPaul Mackerras 146ed981856SPaul Mackerras return ret; 147ed981856SPaul Mackerras } 148ed981856SPaul Mackerras 149ed981856SPaul Mackerras int module_frob_arch_sections(Elf32_Ehdr *hdr, 150ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 151ed981856SPaul Mackerras char *secstrings, 152ed981856SPaul Mackerras struct module *me) 153ed981856SPaul Mackerras { 154ed981856SPaul Mackerras unsigned int i; 155ed981856SPaul Mackerras 156ed981856SPaul Mackerras /* Find .plt and .init.plt sections */ 157ed981856SPaul Mackerras for (i = 0; i < hdr->e_shnum; i++) { 158ed981856SPaul Mackerras if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) 159ed981856SPaul Mackerras me->arch.init_plt_section = i; 160ed981856SPaul Mackerras else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) 161ed981856SPaul Mackerras me->arch.core_plt_section = i; 162ed981856SPaul Mackerras } 163ed981856SPaul Mackerras if (!me->arch.core_plt_section || !me->arch.init_plt_section) { 164ed981856SPaul Mackerras printk("Module doesn't contain .plt or .init.plt sections.\n"); 165ed981856SPaul Mackerras return -ENOEXEC; 166ed981856SPaul Mackerras } 167ed981856SPaul Mackerras 168ed981856SPaul Mackerras /* Override their sizes */ 169ed981856SPaul Mackerras sechdrs[me->arch.core_plt_section].sh_size 170ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 0); 171ed981856SPaul Mackerras sechdrs[me->arch.init_plt_section].sh_size 172ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 1); 173ed981856SPaul Mackerras return 0; 174ed981856SPaul Mackerras } 175ed981856SPaul Mackerras 176ed981856SPaul Mackerras static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) 177ed981856SPaul Mackerras { 1783c752965SSteffen Rumler if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16) 1793c752965SSteffen Rumler && entry->jump[1] == 0x398c0000 + (val & 0xffff)) 180ed981856SPaul Mackerras return 1; 181ed981856SPaul Mackerras return 0; 182ed981856SPaul Mackerras } 183ed981856SPaul Mackerras 184ed981856SPaul Mackerras /* Set up a trampoline in the PLT to bounce us to the distant function */ 185ed981856SPaul Mackerras static uint32_t do_plt_call(void *location, 186ed981856SPaul Mackerras Elf32_Addr val, 187ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 188ed981856SPaul Mackerras struct module *mod) 189ed981856SPaul Mackerras { 190ed981856SPaul Mackerras struct ppc_plt_entry *entry; 191ed981856SPaul Mackerras 192ed981856SPaul Mackerras DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); 193ed981856SPaul Mackerras /* Init, or core PLT? */ 194ed981856SPaul Mackerras if (location >= mod->module_core 195ed981856SPaul Mackerras && location < mod->module_core + mod->core_size) 196ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; 197ed981856SPaul Mackerras else 198ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 199ed981856SPaul Mackerras 200ed981856SPaul Mackerras /* Find this entry, or if that fails, the next avail. entry */ 201ed981856SPaul Mackerras while (entry->jump[0]) { 202ed981856SPaul Mackerras if (entry_matches(entry, val)) return (uint32_t)entry; 203ed981856SPaul Mackerras entry++; 204ed981856SPaul Mackerras } 205ed981856SPaul Mackerras 2063c752965SSteffen Rumler entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */ 2073c752965SSteffen Rumler entry->jump[1] = 0x398c0000 + (val&0xffff); /* addi r12,r12,sym@l*/ 2083c752965SSteffen Rumler entry->jump[2] = 0x7d8903a6; /* mtctr r12 */ 209ed981856SPaul Mackerras entry->jump[3] = 0x4e800420; /* bctr */ 210ed981856SPaul Mackerras 211ed981856SPaul Mackerras DEBUGP("Initialized plt for 0x%x at %p\n", val, entry); 212ed981856SPaul Mackerras return (uint32_t)entry; 213ed981856SPaul Mackerras } 214ed981856SPaul Mackerras 215ed981856SPaul Mackerras int apply_relocate_add(Elf32_Shdr *sechdrs, 216ed981856SPaul Mackerras const char *strtab, 217ed981856SPaul Mackerras unsigned int symindex, 218ed981856SPaul Mackerras unsigned int relsec, 219ed981856SPaul Mackerras struct module *module) 220ed981856SPaul Mackerras { 221ed981856SPaul Mackerras unsigned int i; 222ed981856SPaul Mackerras Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; 223ed981856SPaul Mackerras Elf32_Sym *sym; 224ed981856SPaul Mackerras uint32_t *location; 225ed981856SPaul Mackerras uint32_t value; 226ed981856SPaul Mackerras 227ed981856SPaul Mackerras DEBUGP("Applying ADD relocate section %u to %u\n", relsec, 228ed981856SPaul Mackerras sechdrs[relsec].sh_info); 229ed981856SPaul Mackerras for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 230ed981856SPaul Mackerras /* This is where to make the change */ 231ed981856SPaul Mackerras location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 232ed981856SPaul Mackerras + rela[i].r_offset; 233ed981856SPaul Mackerras /* This is the symbol it is referring to. Note that all 234ed981856SPaul Mackerras undefined symbols have been resolved. */ 235ed981856SPaul Mackerras sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 236ed981856SPaul Mackerras + ELF32_R_SYM(rela[i].r_info); 237ed981856SPaul Mackerras /* `Everything is relative'. */ 238ed981856SPaul Mackerras value = sym->st_value + rela[i].r_addend; 239ed981856SPaul Mackerras 240ed981856SPaul Mackerras switch (ELF32_R_TYPE(rela[i].r_info)) { 241ed981856SPaul Mackerras case R_PPC_ADDR32: 242ed981856SPaul Mackerras /* Simply set it */ 243ed981856SPaul Mackerras *(uint32_t *)location = value; 244ed981856SPaul Mackerras break; 245ed981856SPaul Mackerras 246ed981856SPaul Mackerras case R_PPC_ADDR16_LO: 247ed981856SPaul Mackerras /* Low half of the symbol */ 248ed981856SPaul Mackerras *(uint16_t *)location = value; 249ed981856SPaul Mackerras break; 250ed981856SPaul Mackerras 2519a3d6458SSimon Vallet case R_PPC_ADDR16_HI: 2529a3d6458SSimon Vallet /* Higher half of the symbol */ 2539a3d6458SSimon Vallet *(uint16_t *)location = (value >> 16); 2549a3d6458SSimon Vallet break; 2559a3d6458SSimon Vallet 256ed981856SPaul Mackerras case R_PPC_ADDR16_HA: 257ed981856SPaul Mackerras /* Sign-adjusted lower 16 bits: PPC ELF ABI says: 258ed981856SPaul Mackerras (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. 259ed981856SPaul Mackerras This is the same, only sane. 260ed981856SPaul Mackerras */ 261ed981856SPaul Mackerras *(uint16_t *)location = (value + 0x8000) >> 16; 262ed981856SPaul Mackerras break; 263ed981856SPaul Mackerras 264ed981856SPaul Mackerras case R_PPC_REL24: 265ed981856SPaul Mackerras if ((int)(value - (uint32_t)location) < -0x02000000 266ed981856SPaul Mackerras || (int)(value - (uint32_t)location) >= 0x02000000) 267ed981856SPaul Mackerras value = do_plt_call(location, value, 268ed981856SPaul Mackerras sechdrs, module); 269ed981856SPaul Mackerras 270ed981856SPaul Mackerras /* Only replace bits 2 through 26 */ 271ed981856SPaul Mackerras DEBUGP("REL24 value = %08X. location = %08X\n", 272ed981856SPaul Mackerras value, (uint32_t)location); 273ed981856SPaul Mackerras DEBUGP("Location before: %08X.\n", 274ed981856SPaul Mackerras *(uint32_t *)location); 275ed981856SPaul Mackerras *(uint32_t *)location 276ed981856SPaul Mackerras = (*(uint32_t *)location & ~0x03fffffc) 277ed981856SPaul Mackerras | ((value - (uint32_t)location) 278ed981856SPaul Mackerras & 0x03fffffc); 279ed981856SPaul Mackerras DEBUGP("Location after: %08X.\n", 280ed981856SPaul Mackerras *(uint32_t *)location); 281ed981856SPaul Mackerras DEBUGP("ie. jump to %08X+%08X = %08X\n", 282ed981856SPaul Mackerras *(uint32_t *)location & 0x03fffffc, 283ed981856SPaul Mackerras (uint32_t)location, 284ed981856SPaul Mackerras (*(uint32_t *)location & 0x03fffffc) 285ed981856SPaul Mackerras + (uint32_t)location); 286ed981856SPaul Mackerras break; 287ed981856SPaul Mackerras 288ed981856SPaul Mackerras case R_PPC_REL32: 289ed981856SPaul Mackerras /* 32-bit relative jump. */ 290ed981856SPaul Mackerras *(uint32_t *)location = value - (uint32_t)location; 291ed981856SPaul Mackerras break; 292ed981856SPaul Mackerras 293ed981856SPaul Mackerras default: 294ed981856SPaul Mackerras printk("%s: unknown ADD relocation: %u\n", 295ed981856SPaul Mackerras module->name, 296ed981856SPaul Mackerras ELF32_R_TYPE(rela[i].r_info)); 297ed981856SPaul Mackerras return -ENOEXEC; 298ed981856SPaul Mackerras } 299ed981856SPaul Mackerras } 3007cc45e64SSteven Rostedt #ifdef CONFIG_DYNAMIC_FTRACE 3017cc45e64SSteven Rostedt module->arch.tramp = 3027cc45e64SSteven Rostedt do_plt_call(module->module_core, 3037cc45e64SSteven Rostedt (unsigned long)ftrace_caller, 3047cc45e64SSteven Rostedt sechdrs, module); 3057cc45e64SSteven Rostedt #endif 306ed981856SPaul Mackerras return 0; 307ed981856SPaul Mackerras } 308