11a59d1b8SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later 2ed981856SPaul Mackerras /* Kernel module help for PPC. 3ed981856SPaul Mackerras Copyright (C) 2001 Rusty Russell. 4ed981856SPaul Mackerras 5ed981856SPaul Mackerras */ 6c7d1f6afSAnton Blanchard 7c7d1f6afSAnton Blanchard #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8c7d1f6afSAnton Blanchard 9ed981856SPaul Mackerras #include <linux/module.h> 10ed981856SPaul Mackerras #include <linux/moduleloader.h> 11ed981856SPaul Mackerras #include <linux/elf.h> 12ed981856SPaul Mackerras #include <linux/vmalloc.h> 13ed981856SPaul Mackerras #include <linux/fs.h> 14ed981856SPaul Mackerras #include <linux/string.h> 15ed981856SPaul Mackerras #include <linux/kernel.h> 167cc45e64SSteven Rostedt #include <linux/ftrace.h> 17ed981856SPaul Mackerras #include <linux/cache.h> 1873c9ceabSJeremy Fitzhardinge #include <linux/bug.h> 19eda09fbdSEmil Medve #include <linux/sort.h> 20b88c4767SRobert Jennings #include <asm/setup.h> 2121c4ff80SBenjamin Herrenschmidt 22ed981856SPaul Mackerras /* Count how many different relocations (different symbol, different 23ed981856SPaul Mackerras addend) */ 24ed981856SPaul Mackerras static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) 25ed981856SPaul Mackerras { 26eda09fbdSEmil Medve unsigned int i, r_info, r_addend, _count_relocs; 27ed981856SPaul Mackerras 28eda09fbdSEmil Medve _count_relocs = 0; 29eda09fbdSEmil Medve r_info = 0; 30eda09fbdSEmil Medve r_addend = 0; 31eda09fbdSEmil Medve for (i = 0; i < num; i++) 32eda09fbdSEmil Medve /* Only count 24-bit relocs, others don't need stubs */ 33eda09fbdSEmil Medve if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 && 34eda09fbdSEmil Medve (r_info != ELF32_R_SYM(rela[i].r_info) || 35eda09fbdSEmil Medve r_addend != rela[i].r_addend)) { 36eda09fbdSEmil Medve _count_relocs++; 37eda09fbdSEmil Medve r_info = ELF32_R_SYM(rela[i].r_info); 38eda09fbdSEmil Medve r_addend = rela[i].r_addend; 39ed981856SPaul Mackerras } 40eda09fbdSEmil Medve 417cc45e64SSteven Rostedt #ifdef CONFIG_DYNAMIC_FTRACE 427cc45e64SSteven Rostedt _count_relocs++; /* add one for ftrace_caller */ 437cc45e64SSteven Rostedt #endif 44eda09fbdSEmil Medve return _count_relocs; 45ed981856SPaul Mackerras } 46eda09fbdSEmil Medve 47eda09fbdSEmil Medve static int relacmp(const void *_x, const void *_y) 48eda09fbdSEmil Medve { 49eda09fbdSEmil Medve const Elf32_Rela *x, *y; 50eda09fbdSEmil Medve 51eda09fbdSEmil Medve y = (Elf32_Rela *)_x; 52eda09fbdSEmil Medve x = (Elf32_Rela *)_y; 53eda09fbdSEmil Medve 54eda09fbdSEmil Medve /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to 55eda09fbdSEmil Medve * make the comparison cheaper/faster. It won't affect the sorting or 56eda09fbdSEmil Medve * the counting algorithms' performance 57eda09fbdSEmil Medve */ 58eda09fbdSEmil Medve if (x->r_info < y->r_info) 59eda09fbdSEmil Medve return -1; 60eda09fbdSEmil Medve else if (x->r_info > y->r_info) 61eda09fbdSEmil Medve return 1; 62eda09fbdSEmil Medve else if (x->r_addend < y->r_addend) 63eda09fbdSEmil Medve return -1; 64eda09fbdSEmil Medve else if (x->r_addend > y->r_addend) 65eda09fbdSEmil Medve return 1; 66eda09fbdSEmil Medve else 67eda09fbdSEmil Medve return 0; 68eda09fbdSEmil Medve } 69eda09fbdSEmil Medve 70ed981856SPaul Mackerras /* Get the potential trampolines size required of the init and 71ed981856SPaul Mackerras non-init sections */ 72ed981856SPaul Mackerras static unsigned long get_plt_size(const Elf32_Ehdr *hdr, 73ed981856SPaul Mackerras const Elf32_Shdr *sechdrs, 74ed981856SPaul Mackerras const char *secstrings, 75ed981856SPaul Mackerras int is_init) 76ed981856SPaul Mackerras { 77ed981856SPaul Mackerras unsigned long ret = 0; 78ed981856SPaul Mackerras unsigned i; 79ed981856SPaul Mackerras 80ed981856SPaul Mackerras /* Everything marked ALLOC (this includes the exported 81ed981856SPaul Mackerras symbols) */ 82ed981856SPaul Mackerras for (i = 1; i < hdr->e_shnum; i++) { 83ed981856SPaul Mackerras /* If it's called *.init*, and we're not init, we're 84ed981856SPaul Mackerras not interested */ 85d8731527SMathieu Malaterre if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != NULL) 86ed981856SPaul Mackerras != is_init) 87ed981856SPaul Mackerras continue; 88ed981856SPaul Mackerras 89ed981856SPaul Mackerras /* We don't want to look at debug sections. */ 90d8731527SMathieu Malaterre if (strstr(secstrings + sechdrs[i].sh_name, ".debug")) 91ed981856SPaul Mackerras continue; 92ed981856SPaul Mackerras 93ed981856SPaul Mackerras if (sechdrs[i].sh_type == SHT_RELA) { 94c7d1f6afSAnton Blanchard pr_debug("Found relocations in section %u\n", i); 95c7d1f6afSAnton Blanchard pr_debug("Ptr: %p. Number: %u\n", 96ed981856SPaul Mackerras (void *)hdr + sechdrs[i].sh_offset, 97ed981856SPaul Mackerras sechdrs[i].sh_size / sizeof(Elf32_Rela)); 98eda09fbdSEmil Medve 99eda09fbdSEmil Medve /* Sort the relocation information based on a symbol and 100eda09fbdSEmil Medve * addend key. This is a stable O(n*log n) complexity 101eda09fbdSEmil Medve * alogrithm but it will reduce the complexity of 102eda09fbdSEmil Medve * count_relocs() to linear complexity O(n) 103eda09fbdSEmil Medve */ 104eda09fbdSEmil Medve sort((void *)hdr + sechdrs[i].sh_offset, 105eda09fbdSEmil Medve sechdrs[i].sh_size / sizeof(Elf32_Rela), 106bac7ca7bSAndrey Abramov sizeof(Elf32_Rela), relacmp, NULL); 107eda09fbdSEmil Medve 108ed981856SPaul Mackerras ret += count_relocs((void *)hdr 109ed981856SPaul Mackerras + sechdrs[i].sh_offset, 110ed981856SPaul Mackerras sechdrs[i].sh_size 111ed981856SPaul Mackerras / sizeof(Elf32_Rela)) 112ed981856SPaul Mackerras * sizeof(struct ppc_plt_entry); 113ed981856SPaul Mackerras } 114ed981856SPaul Mackerras } 115ed981856SPaul Mackerras 116ed981856SPaul Mackerras return ret; 117ed981856SPaul Mackerras } 118ed981856SPaul Mackerras 119ed981856SPaul Mackerras int module_frob_arch_sections(Elf32_Ehdr *hdr, 120ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 121ed981856SPaul Mackerras char *secstrings, 122ed981856SPaul Mackerras struct module *me) 123ed981856SPaul Mackerras { 124ed981856SPaul Mackerras unsigned int i; 125ed981856SPaul Mackerras 126ed981856SPaul Mackerras /* Find .plt and .init.plt sections */ 127ed981856SPaul Mackerras for (i = 0; i < hdr->e_shnum; i++) { 128ed981856SPaul Mackerras if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) 129ed981856SPaul Mackerras me->arch.init_plt_section = i; 130ed981856SPaul Mackerras else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) 131ed981856SPaul Mackerras me->arch.core_plt_section = i; 132ed981856SPaul Mackerras } 133ed981856SPaul Mackerras if (!me->arch.core_plt_section || !me->arch.init_plt_section) { 134c7d1f6afSAnton Blanchard pr_err("Module doesn't contain .plt or .init.plt sections.\n"); 135ed981856SPaul Mackerras return -ENOEXEC; 136ed981856SPaul Mackerras } 137ed981856SPaul Mackerras 138ed981856SPaul Mackerras /* Override their sizes */ 139ed981856SPaul Mackerras sechdrs[me->arch.core_plt_section].sh_size 140ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 0); 141ed981856SPaul Mackerras sechdrs[me->arch.init_plt_section].sh_size 142ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 1); 143ed981856SPaul Mackerras return 0; 144ed981856SPaul Mackerras } 145ed981856SPaul Mackerras 146ed981856SPaul Mackerras static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) 147ed981856SPaul Mackerras { 148*47b04699SChristophe Leroy if (entry->jump[0] != PPC_RAW_LIS(_R12, PPC_HA(val))) 149ed981856SPaul Mackerras return 0; 150*47b04699SChristophe Leroy if (entry->jump[1] != PPC_RAW_ADDI(_R12, _R12, PPC_LO(val))) 1514eb4516eSChristophe Leroy return 0; 1524eb4516eSChristophe Leroy return 1; 153ed981856SPaul Mackerras } 154ed981856SPaul Mackerras 155ed981856SPaul Mackerras /* Set up a trampoline in the PLT to bounce us to the distant function */ 156ed981856SPaul Mackerras static uint32_t do_plt_call(void *location, 157ed981856SPaul Mackerras Elf32_Addr val, 158136cd345SMichael Ellerman const Elf32_Shdr *sechdrs, 159ed981856SPaul Mackerras struct module *mod) 160ed981856SPaul Mackerras { 161ed981856SPaul Mackerras struct ppc_plt_entry *entry; 162ed981856SPaul Mackerras 163c7d1f6afSAnton Blanchard pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); 164ed981856SPaul Mackerras /* Init, or core PLT? */ 1657523e4dcSRusty Russell if (location >= mod->core_layout.base 1667523e4dcSRusty Russell && location < mod->core_layout.base + mod->core_layout.size) 167ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; 168ed981856SPaul Mackerras else 169ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 170ed981856SPaul Mackerras 171ed981856SPaul Mackerras /* Find this entry, or if that fails, the next avail. entry */ 172ed981856SPaul Mackerras while (entry->jump[0]) { 173ed981856SPaul Mackerras if (entry_matches(entry, val)) return (uint32_t)entry; 174ed981856SPaul Mackerras entry++; 175ed981856SPaul Mackerras } 176ed981856SPaul Mackerras 177*47b04699SChristophe Leroy entry->jump[0] = PPC_RAW_LIS(_R12, PPC_HA(val)); 178*47b04699SChristophe Leroy entry->jump[1] = PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)); 179*47b04699SChristophe Leroy entry->jump[2] = PPC_RAW_MTCTR(_R12); 180*47b04699SChristophe Leroy entry->jump[3] = PPC_RAW_BCTR(); 181ed981856SPaul Mackerras 182c7d1f6afSAnton Blanchard pr_debug("Initialized plt for 0x%x at %p\n", val, entry); 183ed981856SPaul Mackerras return (uint32_t)entry; 184ed981856SPaul Mackerras } 185ed981856SPaul Mackerras 186ed981856SPaul Mackerras int apply_relocate_add(Elf32_Shdr *sechdrs, 187ed981856SPaul Mackerras const char *strtab, 188ed981856SPaul Mackerras unsigned int symindex, 189ed981856SPaul Mackerras unsigned int relsec, 190ed981856SPaul Mackerras struct module *module) 191ed981856SPaul Mackerras { 192ed981856SPaul Mackerras unsigned int i; 193ed981856SPaul Mackerras Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; 194ed981856SPaul Mackerras Elf32_Sym *sym; 195ed981856SPaul Mackerras uint32_t *location; 196ed981856SPaul Mackerras uint32_t value; 197ed981856SPaul Mackerras 198c7d1f6afSAnton Blanchard pr_debug("Applying ADD relocate section %u to %u\n", relsec, 199ed981856SPaul Mackerras sechdrs[relsec].sh_info); 200ed981856SPaul Mackerras for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 201ed981856SPaul Mackerras /* This is where to make the change */ 202ed981856SPaul Mackerras location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 203ed981856SPaul Mackerras + rela[i].r_offset; 204ed981856SPaul Mackerras /* This is the symbol it is referring to. Note that all 205ed981856SPaul Mackerras undefined symbols have been resolved. */ 206ed981856SPaul Mackerras sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 207ed981856SPaul Mackerras + ELF32_R_SYM(rela[i].r_info); 208ed981856SPaul Mackerras /* `Everything is relative'. */ 209ed981856SPaul Mackerras value = sym->st_value + rela[i].r_addend; 210ed981856SPaul Mackerras 211ed981856SPaul Mackerras switch (ELF32_R_TYPE(rela[i].r_info)) { 212ed981856SPaul Mackerras case R_PPC_ADDR32: 213ed981856SPaul Mackerras /* Simply set it */ 214ed981856SPaul Mackerras *(uint32_t *)location = value; 215ed981856SPaul Mackerras break; 216ed981856SPaul Mackerras 217ed981856SPaul Mackerras case R_PPC_ADDR16_LO: 218ed981856SPaul Mackerras /* Low half of the symbol */ 219ed981856SPaul Mackerras *(uint16_t *)location = value; 220ed981856SPaul Mackerras break; 221ed981856SPaul Mackerras 2229a3d6458SSimon Vallet case R_PPC_ADDR16_HI: 2239a3d6458SSimon Vallet /* Higher half of the symbol */ 2249a3d6458SSimon Vallet *(uint16_t *)location = (value >> 16); 2259a3d6458SSimon Vallet break; 2269a3d6458SSimon Vallet 227ed981856SPaul Mackerras case R_PPC_ADDR16_HA: 228ed981856SPaul Mackerras /* Sign-adjusted lower 16 bits: PPC ELF ABI says: 229ed981856SPaul Mackerras (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. 230ed981856SPaul Mackerras This is the same, only sane. 231ed981856SPaul Mackerras */ 232ed981856SPaul Mackerras *(uint16_t *)location = (value + 0x8000) >> 16; 233ed981856SPaul Mackerras break; 234ed981856SPaul Mackerras 235ed981856SPaul Mackerras case R_PPC_REL24: 236ed981856SPaul Mackerras if ((int)(value - (uint32_t)location) < -0x02000000 237ed981856SPaul Mackerras || (int)(value - (uint32_t)location) >= 0x02000000) 238ed981856SPaul Mackerras value = do_plt_call(location, value, 239ed981856SPaul Mackerras sechdrs, module); 240ed981856SPaul Mackerras 241ed981856SPaul Mackerras /* Only replace bits 2 through 26 */ 242c7d1f6afSAnton Blanchard pr_debug("REL24 value = %08X. location = %08X\n", 243ed981856SPaul Mackerras value, (uint32_t)location); 244c7d1f6afSAnton Blanchard pr_debug("Location before: %08X.\n", 245ed981856SPaul Mackerras *(uint32_t *)location); 246ed981856SPaul Mackerras *(uint32_t *)location 247ed981856SPaul Mackerras = (*(uint32_t *)location & ~0x03fffffc) 248ed981856SPaul Mackerras | ((value - (uint32_t)location) 249ed981856SPaul Mackerras & 0x03fffffc); 250c7d1f6afSAnton Blanchard pr_debug("Location after: %08X.\n", 251ed981856SPaul Mackerras *(uint32_t *)location); 252c7d1f6afSAnton Blanchard pr_debug("ie. jump to %08X+%08X = %08X\n", 253ed981856SPaul Mackerras *(uint32_t *)location & 0x03fffffc, 254ed981856SPaul Mackerras (uint32_t)location, 255ed981856SPaul Mackerras (*(uint32_t *)location & 0x03fffffc) 256ed981856SPaul Mackerras + (uint32_t)location); 257ed981856SPaul Mackerras break; 258ed981856SPaul Mackerras 259ed981856SPaul Mackerras case R_PPC_REL32: 260ed981856SPaul Mackerras /* 32-bit relative jump. */ 261ed981856SPaul Mackerras *(uint32_t *)location = value - (uint32_t)location; 262ed981856SPaul Mackerras break; 263ed981856SPaul Mackerras 264ed981856SPaul Mackerras default: 265c7d1f6afSAnton Blanchard pr_err("%s: unknown ADD relocation: %u\n", 266ed981856SPaul Mackerras module->name, 267ed981856SPaul Mackerras ELF32_R_TYPE(rela[i].r_info)); 268ed981856SPaul Mackerras return -ENOEXEC; 269ed981856SPaul Mackerras } 270ed981856SPaul Mackerras } 271136cd345SMichael Ellerman 272ed981856SPaul Mackerras return 0; 273ed981856SPaul Mackerras } 274136cd345SMichael Ellerman 275136cd345SMichael Ellerman #ifdef CONFIG_DYNAMIC_FTRACE 276136cd345SMichael Ellerman int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs) 277136cd345SMichael Ellerman { 278136cd345SMichael Ellerman module->arch.tramp = do_plt_call(module->core_layout.base, 279136cd345SMichael Ellerman (unsigned long)ftrace_caller, 280136cd345SMichael Ellerman sechdrs, module); 281136cd345SMichael Ellerman if (!module->arch.tramp) 282136cd345SMichael Ellerman return -ENOENT; 283136cd345SMichael Ellerman 284136cd345SMichael Ellerman return 0; 285136cd345SMichael Ellerman } 286136cd345SMichael Ellerman #endif 287