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 */ 18c7d1f6afSAnton Blanchard 19c7d1f6afSAnton Blanchard #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20c7d1f6afSAnton Blanchard 21ed981856SPaul Mackerras #include <linux/module.h> 22ed981856SPaul Mackerras #include <linux/moduleloader.h> 23ed981856SPaul Mackerras #include <linux/elf.h> 24ed981856SPaul Mackerras #include <linux/vmalloc.h> 25ed981856SPaul Mackerras #include <linux/fs.h> 26ed981856SPaul Mackerras #include <linux/string.h> 27ed981856SPaul Mackerras #include <linux/kernel.h> 287cc45e64SSteven Rostedt #include <linux/ftrace.h> 29ed981856SPaul Mackerras #include <linux/cache.h> 3073c9ceabSJeremy Fitzhardinge #include <linux/bug.h> 31eda09fbdSEmil Medve #include <linux/sort.h> 32b88c4767SRobert Jennings #include <asm/setup.h> 3321c4ff80SBenjamin Herrenschmidt 34ed981856SPaul Mackerras /* Count how many different relocations (different symbol, different 35ed981856SPaul Mackerras addend) */ 36ed981856SPaul Mackerras static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) 37ed981856SPaul Mackerras { 38eda09fbdSEmil Medve unsigned int i, r_info, r_addend, _count_relocs; 39ed981856SPaul Mackerras 40eda09fbdSEmil Medve _count_relocs = 0; 41eda09fbdSEmil Medve r_info = 0; 42eda09fbdSEmil Medve r_addend = 0; 43eda09fbdSEmil Medve for (i = 0; i < num; i++) 44eda09fbdSEmil Medve /* Only count 24-bit relocs, others don't need stubs */ 45eda09fbdSEmil Medve if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 && 46eda09fbdSEmil Medve (r_info != ELF32_R_SYM(rela[i].r_info) || 47eda09fbdSEmil Medve r_addend != rela[i].r_addend)) { 48eda09fbdSEmil Medve _count_relocs++; 49eda09fbdSEmil Medve r_info = ELF32_R_SYM(rela[i].r_info); 50eda09fbdSEmil Medve r_addend = rela[i].r_addend; 51ed981856SPaul Mackerras } 52eda09fbdSEmil Medve 537cc45e64SSteven Rostedt #ifdef CONFIG_DYNAMIC_FTRACE 547cc45e64SSteven Rostedt _count_relocs++; /* add one for ftrace_caller */ 557cc45e64SSteven Rostedt #endif 56eda09fbdSEmil Medve return _count_relocs; 57ed981856SPaul Mackerras } 58eda09fbdSEmil Medve 59eda09fbdSEmil Medve static int relacmp(const void *_x, const void *_y) 60eda09fbdSEmil Medve { 61eda09fbdSEmil Medve const Elf32_Rela *x, *y; 62eda09fbdSEmil Medve 63eda09fbdSEmil Medve y = (Elf32_Rela *)_x; 64eda09fbdSEmil Medve x = (Elf32_Rela *)_y; 65eda09fbdSEmil Medve 66eda09fbdSEmil Medve /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to 67eda09fbdSEmil Medve * make the comparison cheaper/faster. It won't affect the sorting or 68eda09fbdSEmil Medve * the counting algorithms' performance 69eda09fbdSEmil Medve */ 70eda09fbdSEmil Medve if (x->r_info < y->r_info) 71eda09fbdSEmil Medve return -1; 72eda09fbdSEmil Medve else if (x->r_info > y->r_info) 73eda09fbdSEmil Medve return 1; 74eda09fbdSEmil Medve else if (x->r_addend < y->r_addend) 75eda09fbdSEmil Medve return -1; 76eda09fbdSEmil Medve else if (x->r_addend > y->r_addend) 77eda09fbdSEmil Medve return 1; 78eda09fbdSEmil Medve else 79eda09fbdSEmil Medve return 0; 80eda09fbdSEmil Medve } 81eda09fbdSEmil Medve 82eda09fbdSEmil Medve static void relaswap(void *_x, void *_y, int size) 83eda09fbdSEmil Medve { 84eda09fbdSEmil Medve uint32_t *x, *y, tmp; 85eda09fbdSEmil Medve int i; 86eda09fbdSEmil Medve 87eda09fbdSEmil Medve y = (uint32_t *)_x; 88eda09fbdSEmil Medve x = (uint32_t *)_y; 89eda09fbdSEmil Medve 90eda09fbdSEmil Medve for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) { 91eda09fbdSEmil Medve tmp = x[i]; 92eda09fbdSEmil Medve x[i] = y[i]; 93eda09fbdSEmil Medve y[i] = tmp; 94eda09fbdSEmil Medve } 95ed981856SPaul Mackerras } 96ed981856SPaul Mackerras 97ed981856SPaul Mackerras /* Get the potential trampolines size required of the init and 98ed981856SPaul Mackerras non-init sections */ 99ed981856SPaul Mackerras static unsigned long get_plt_size(const Elf32_Ehdr *hdr, 100ed981856SPaul Mackerras const Elf32_Shdr *sechdrs, 101ed981856SPaul Mackerras const char *secstrings, 102ed981856SPaul Mackerras int is_init) 103ed981856SPaul Mackerras { 104ed981856SPaul Mackerras unsigned long ret = 0; 105ed981856SPaul Mackerras unsigned i; 106ed981856SPaul Mackerras 107ed981856SPaul Mackerras /* Everything marked ALLOC (this includes the exported 108ed981856SPaul Mackerras symbols) */ 109ed981856SPaul Mackerras for (i = 1; i < hdr->e_shnum; i++) { 110ed981856SPaul Mackerras /* If it's called *.init*, and we're not init, we're 111ed981856SPaul Mackerras not interested */ 112ed981856SPaul Mackerras if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) 113ed981856SPaul Mackerras != is_init) 114ed981856SPaul Mackerras continue; 115ed981856SPaul Mackerras 116ed981856SPaul Mackerras /* We don't want to look at debug sections. */ 117ed981856SPaul Mackerras if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) 118ed981856SPaul Mackerras continue; 119ed981856SPaul Mackerras 120ed981856SPaul Mackerras if (sechdrs[i].sh_type == SHT_RELA) { 121c7d1f6afSAnton Blanchard pr_debug("Found relocations in section %u\n", i); 122c7d1f6afSAnton Blanchard pr_debug("Ptr: %p. Number: %u\n", 123ed981856SPaul Mackerras (void *)hdr + sechdrs[i].sh_offset, 124ed981856SPaul Mackerras sechdrs[i].sh_size / sizeof(Elf32_Rela)); 125eda09fbdSEmil Medve 126eda09fbdSEmil Medve /* Sort the relocation information based on a symbol and 127eda09fbdSEmil Medve * addend key. This is a stable O(n*log n) complexity 128eda09fbdSEmil Medve * alogrithm but it will reduce the complexity of 129eda09fbdSEmil Medve * count_relocs() to linear complexity O(n) 130eda09fbdSEmil Medve */ 131eda09fbdSEmil Medve sort((void *)hdr + sechdrs[i].sh_offset, 132eda09fbdSEmil Medve sechdrs[i].sh_size / sizeof(Elf32_Rela), 133eda09fbdSEmil Medve sizeof(Elf32_Rela), relacmp, relaswap); 134eda09fbdSEmil Medve 135ed981856SPaul Mackerras ret += count_relocs((void *)hdr 136ed981856SPaul Mackerras + sechdrs[i].sh_offset, 137ed981856SPaul Mackerras sechdrs[i].sh_size 138ed981856SPaul Mackerras / sizeof(Elf32_Rela)) 139ed981856SPaul Mackerras * sizeof(struct ppc_plt_entry); 140ed981856SPaul Mackerras } 141ed981856SPaul Mackerras } 142ed981856SPaul Mackerras 143ed981856SPaul Mackerras return ret; 144ed981856SPaul Mackerras } 145ed981856SPaul Mackerras 146ed981856SPaul Mackerras int module_frob_arch_sections(Elf32_Ehdr *hdr, 147ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 148ed981856SPaul Mackerras char *secstrings, 149ed981856SPaul Mackerras struct module *me) 150ed981856SPaul Mackerras { 151ed981856SPaul Mackerras unsigned int i; 152ed981856SPaul Mackerras 153ed981856SPaul Mackerras /* Find .plt and .init.plt sections */ 154ed981856SPaul Mackerras for (i = 0; i < hdr->e_shnum; i++) { 155ed981856SPaul Mackerras if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) 156ed981856SPaul Mackerras me->arch.init_plt_section = i; 157ed981856SPaul Mackerras else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) 158ed981856SPaul Mackerras me->arch.core_plt_section = i; 159ed981856SPaul Mackerras } 160ed981856SPaul Mackerras if (!me->arch.core_plt_section || !me->arch.init_plt_section) { 161c7d1f6afSAnton Blanchard pr_err("Module doesn't contain .plt or .init.plt sections.\n"); 162ed981856SPaul Mackerras return -ENOEXEC; 163ed981856SPaul Mackerras } 164ed981856SPaul Mackerras 165ed981856SPaul Mackerras /* Override their sizes */ 166ed981856SPaul Mackerras sechdrs[me->arch.core_plt_section].sh_size 167ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 0); 168ed981856SPaul Mackerras sechdrs[me->arch.init_plt_section].sh_size 169ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 1); 170ed981856SPaul Mackerras return 0; 171ed981856SPaul Mackerras } 172ed981856SPaul Mackerras 173ed981856SPaul Mackerras static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) 174ed981856SPaul Mackerras { 1753c752965SSteffen Rumler if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16) 1763c752965SSteffen Rumler && entry->jump[1] == 0x398c0000 + (val & 0xffff)) 177ed981856SPaul Mackerras return 1; 178ed981856SPaul Mackerras return 0; 179ed981856SPaul Mackerras } 180ed981856SPaul Mackerras 181ed981856SPaul Mackerras /* Set up a trampoline in the PLT to bounce us to the distant function */ 182ed981856SPaul Mackerras static uint32_t do_plt_call(void *location, 183ed981856SPaul Mackerras Elf32_Addr val, 184ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 185ed981856SPaul Mackerras struct module *mod) 186ed981856SPaul Mackerras { 187ed981856SPaul Mackerras struct ppc_plt_entry *entry; 188ed981856SPaul Mackerras 189c7d1f6afSAnton Blanchard pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); 190ed981856SPaul Mackerras /* Init, or core PLT? */ 191ed981856SPaul Mackerras if (location >= mod->module_core 192ed981856SPaul Mackerras && location < mod->module_core + mod->core_size) 193ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; 194ed981856SPaul Mackerras else 195ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 196ed981856SPaul Mackerras 197ed981856SPaul Mackerras /* Find this entry, or if that fails, the next avail. entry */ 198ed981856SPaul Mackerras while (entry->jump[0]) { 199ed981856SPaul Mackerras if (entry_matches(entry, val)) return (uint32_t)entry; 200ed981856SPaul Mackerras entry++; 201ed981856SPaul Mackerras } 202ed981856SPaul Mackerras 2033c752965SSteffen Rumler entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */ 2043c752965SSteffen Rumler entry->jump[1] = 0x398c0000 + (val&0xffff); /* addi r12,r12,sym@l*/ 2053c752965SSteffen Rumler entry->jump[2] = 0x7d8903a6; /* mtctr r12 */ 206ed981856SPaul Mackerras entry->jump[3] = 0x4e800420; /* bctr */ 207ed981856SPaul Mackerras 208c7d1f6afSAnton Blanchard pr_debug("Initialized plt for 0x%x at %p\n", val, entry); 209ed981856SPaul Mackerras return (uint32_t)entry; 210ed981856SPaul Mackerras } 211ed981856SPaul Mackerras 212ed981856SPaul Mackerras int apply_relocate_add(Elf32_Shdr *sechdrs, 213ed981856SPaul Mackerras const char *strtab, 214ed981856SPaul Mackerras unsigned int symindex, 215ed981856SPaul Mackerras unsigned int relsec, 216ed981856SPaul Mackerras struct module *module) 217ed981856SPaul Mackerras { 218ed981856SPaul Mackerras unsigned int i; 219ed981856SPaul Mackerras Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; 220ed981856SPaul Mackerras Elf32_Sym *sym; 221ed981856SPaul Mackerras uint32_t *location; 222ed981856SPaul Mackerras uint32_t value; 223ed981856SPaul Mackerras 224c7d1f6afSAnton Blanchard pr_debug("Applying ADD relocate section %u to %u\n", relsec, 225ed981856SPaul Mackerras sechdrs[relsec].sh_info); 226ed981856SPaul Mackerras for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 227ed981856SPaul Mackerras /* This is where to make the change */ 228ed981856SPaul Mackerras location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 229ed981856SPaul Mackerras + rela[i].r_offset; 230ed981856SPaul Mackerras /* This is the symbol it is referring to. Note that all 231ed981856SPaul Mackerras undefined symbols have been resolved. */ 232ed981856SPaul Mackerras sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 233ed981856SPaul Mackerras + ELF32_R_SYM(rela[i].r_info); 234ed981856SPaul Mackerras /* `Everything is relative'. */ 235ed981856SPaul Mackerras value = sym->st_value + rela[i].r_addend; 236ed981856SPaul Mackerras 237ed981856SPaul Mackerras switch (ELF32_R_TYPE(rela[i].r_info)) { 238ed981856SPaul Mackerras case R_PPC_ADDR32: 239ed981856SPaul Mackerras /* Simply set it */ 240ed981856SPaul Mackerras *(uint32_t *)location = value; 241ed981856SPaul Mackerras break; 242ed981856SPaul Mackerras 243ed981856SPaul Mackerras case R_PPC_ADDR16_LO: 244ed981856SPaul Mackerras /* Low half of the symbol */ 245ed981856SPaul Mackerras *(uint16_t *)location = value; 246ed981856SPaul Mackerras break; 247ed981856SPaul Mackerras 2489a3d6458SSimon Vallet case R_PPC_ADDR16_HI: 2499a3d6458SSimon Vallet /* Higher half of the symbol */ 2509a3d6458SSimon Vallet *(uint16_t *)location = (value >> 16); 2519a3d6458SSimon Vallet break; 2529a3d6458SSimon Vallet 253ed981856SPaul Mackerras case R_PPC_ADDR16_HA: 254ed981856SPaul Mackerras /* Sign-adjusted lower 16 bits: PPC ELF ABI says: 255ed981856SPaul Mackerras (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. 256ed981856SPaul Mackerras This is the same, only sane. 257ed981856SPaul Mackerras */ 258ed981856SPaul Mackerras *(uint16_t *)location = (value + 0x8000) >> 16; 259ed981856SPaul Mackerras break; 260ed981856SPaul Mackerras 261ed981856SPaul Mackerras case R_PPC_REL24: 262ed981856SPaul Mackerras if ((int)(value - (uint32_t)location) < -0x02000000 263ed981856SPaul Mackerras || (int)(value - (uint32_t)location) >= 0x02000000) 264ed981856SPaul Mackerras value = do_plt_call(location, value, 265ed981856SPaul Mackerras sechdrs, module); 266ed981856SPaul Mackerras 267ed981856SPaul Mackerras /* Only replace bits 2 through 26 */ 268c7d1f6afSAnton Blanchard pr_debug("REL24 value = %08X. location = %08X\n", 269ed981856SPaul Mackerras value, (uint32_t)location); 270c7d1f6afSAnton Blanchard pr_debug("Location before: %08X.\n", 271ed981856SPaul Mackerras *(uint32_t *)location); 272ed981856SPaul Mackerras *(uint32_t *)location 273ed981856SPaul Mackerras = (*(uint32_t *)location & ~0x03fffffc) 274ed981856SPaul Mackerras | ((value - (uint32_t)location) 275ed981856SPaul Mackerras & 0x03fffffc); 276c7d1f6afSAnton Blanchard pr_debug("Location after: %08X.\n", 277ed981856SPaul Mackerras *(uint32_t *)location); 278c7d1f6afSAnton Blanchard pr_debug("ie. jump to %08X+%08X = %08X\n", 279ed981856SPaul Mackerras *(uint32_t *)location & 0x03fffffc, 280ed981856SPaul Mackerras (uint32_t)location, 281ed981856SPaul Mackerras (*(uint32_t *)location & 0x03fffffc) 282ed981856SPaul Mackerras + (uint32_t)location); 283ed981856SPaul Mackerras break; 284ed981856SPaul Mackerras 285ed981856SPaul Mackerras case R_PPC_REL32: 286ed981856SPaul Mackerras /* 32-bit relative jump. */ 287ed981856SPaul Mackerras *(uint32_t *)location = value - (uint32_t)location; 288ed981856SPaul Mackerras break; 289ed981856SPaul Mackerras 290ed981856SPaul Mackerras default: 291c7d1f6afSAnton Blanchard pr_err("%s: unknown ADD relocation: %u\n", 292ed981856SPaul Mackerras module->name, 293ed981856SPaul Mackerras ELF32_R_TYPE(rela[i].r_info)); 294ed981856SPaul Mackerras return -ENOEXEC; 295ed981856SPaul Mackerras } 296ed981856SPaul Mackerras } 2977cc45e64SSteven Rostedt #ifdef CONFIG_DYNAMIC_FTRACE 2987cc45e64SSteven Rostedt module->arch.tramp = 2997cc45e64SSteven Rostedt do_plt_call(module->module_core, 3007cc45e64SSteven Rostedt (unsigned long)ftrace_caller, 3017cc45e64SSteven Rostedt sechdrs, module); 3027cc45e64SSteven Rostedt #endif 303ed981856SPaul Mackerras return 0; 304ed981856SPaul Mackerras } 305