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 70eda09fbdSEmil Medve static void relaswap(void *_x, void *_y, int size) 71eda09fbdSEmil Medve { 72eda09fbdSEmil Medve uint32_t *x, *y, tmp; 73eda09fbdSEmil Medve int i; 74eda09fbdSEmil Medve 75eda09fbdSEmil Medve y = (uint32_t *)_x; 76eda09fbdSEmil Medve x = (uint32_t *)_y; 77eda09fbdSEmil Medve 78eda09fbdSEmil Medve for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) { 79eda09fbdSEmil Medve tmp = x[i]; 80eda09fbdSEmil Medve x[i] = y[i]; 81eda09fbdSEmil Medve y[i] = tmp; 82eda09fbdSEmil Medve } 83ed981856SPaul Mackerras } 84ed981856SPaul Mackerras 85ed981856SPaul Mackerras /* Get the potential trampolines size required of the init and 86ed981856SPaul Mackerras non-init sections */ 87ed981856SPaul Mackerras static unsigned long get_plt_size(const Elf32_Ehdr *hdr, 88ed981856SPaul Mackerras const Elf32_Shdr *sechdrs, 89ed981856SPaul Mackerras const char *secstrings, 90ed981856SPaul Mackerras int is_init) 91ed981856SPaul Mackerras { 92ed981856SPaul Mackerras unsigned long ret = 0; 93ed981856SPaul Mackerras unsigned i; 94ed981856SPaul Mackerras 95ed981856SPaul Mackerras /* Everything marked ALLOC (this includes the exported 96ed981856SPaul Mackerras symbols) */ 97ed981856SPaul Mackerras for (i = 1; i < hdr->e_shnum; i++) { 98ed981856SPaul Mackerras /* If it's called *.init*, and we're not init, we're 99ed981856SPaul Mackerras not interested */ 100d8731527SMathieu Malaterre if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != NULL) 101ed981856SPaul Mackerras != is_init) 102ed981856SPaul Mackerras continue; 103ed981856SPaul Mackerras 104ed981856SPaul Mackerras /* We don't want to look at debug sections. */ 105d8731527SMathieu Malaterre if (strstr(secstrings + sechdrs[i].sh_name, ".debug")) 106ed981856SPaul Mackerras continue; 107ed981856SPaul Mackerras 108ed981856SPaul Mackerras if (sechdrs[i].sh_type == SHT_RELA) { 109c7d1f6afSAnton Blanchard pr_debug("Found relocations in section %u\n", i); 110c7d1f6afSAnton Blanchard pr_debug("Ptr: %p. Number: %u\n", 111ed981856SPaul Mackerras (void *)hdr + sechdrs[i].sh_offset, 112ed981856SPaul Mackerras sechdrs[i].sh_size / sizeof(Elf32_Rela)); 113eda09fbdSEmil Medve 114eda09fbdSEmil Medve /* Sort the relocation information based on a symbol and 115eda09fbdSEmil Medve * addend key. This is a stable O(n*log n) complexity 116eda09fbdSEmil Medve * alogrithm but it will reduce the complexity of 117eda09fbdSEmil Medve * count_relocs() to linear complexity O(n) 118eda09fbdSEmil Medve */ 119eda09fbdSEmil Medve sort((void *)hdr + sechdrs[i].sh_offset, 120eda09fbdSEmil Medve sechdrs[i].sh_size / sizeof(Elf32_Rela), 121eda09fbdSEmil Medve sizeof(Elf32_Rela), relacmp, relaswap); 122eda09fbdSEmil Medve 123ed981856SPaul Mackerras ret += count_relocs((void *)hdr 124ed981856SPaul Mackerras + sechdrs[i].sh_offset, 125ed981856SPaul Mackerras sechdrs[i].sh_size 126ed981856SPaul Mackerras / sizeof(Elf32_Rela)) 127ed981856SPaul Mackerras * sizeof(struct ppc_plt_entry); 128ed981856SPaul Mackerras } 129ed981856SPaul Mackerras } 130ed981856SPaul Mackerras 131ed981856SPaul Mackerras return ret; 132ed981856SPaul Mackerras } 133ed981856SPaul Mackerras 134ed981856SPaul Mackerras int module_frob_arch_sections(Elf32_Ehdr *hdr, 135ed981856SPaul Mackerras Elf32_Shdr *sechdrs, 136ed981856SPaul Mackerras char *secstrings, 137ed981856SPaul Mackerras struct module *me) 138ed981856SPaul Mackerras { 139ed981856SPaul Mackerras unsigned int i; 140ed981856SPaul Mackerras 141ed981856SPaul Mackerras /* Find .plt and .init.plt sections */ 142ed981856SPaul Mackerras for (i = 0; i < hdr->e_shnum; i++) { 143ed981856SPaul Mackerras if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) 144ed981856SPaul Mackerras me->arch.init_plt_section = i; 145ed981856SPaul Mackerras else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) 146ed981856SPaul Mackerras me->arch.core_plt_section = i; 147ed981856SPaul Mackerras } 148ed981856SPaul Mackerras if (!me->arch.core_plt_section || !me->arch.init_plt_section) { 149c7d1f6afSAnton Blanchard pr_err("Module doesn't contain .plt or .init.plt sections.\n"); 150ed981856SPaul Mackerras return -ENOEXEC; 151ed981856SPaul Mackerras } 152ed981856SPaul Mackerras 153ed981856SPaul Mackerras /* Override their sizes */ 154ed981856SPaul Mackerras sechdrs[me->arch.core_plt_section].sh_size 155ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 0); 156ed981856SPaul Mackerras sechdrs[me->arch.init_plt_section].sh_size 157ed981856SPaul Mackerras = get_plt_size(hdr, sechdrs, secstrings, 1); 158ed981856SPaul Mackerras return 0; 159ed981856SPaul Mackerras } 160ed981856SPaul Mackerras 161ed981856SPaul Mackerras static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) 162ed981856SPaul Mackerras { 1633c752965SSteffen Rumler if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16) 1643c752965SSteffen Rumler && entry->jump[1] == 0x398c0000 + (val & 0xffff)) 165ed981856SPaul Mackerras return 1; 166ed981856SPaul Mackerras return 0; 167ed981856SPaul Mackerras } 168ed981856SPaul Mackerras 169ed981856SPaul Mackerras /* Set up a trampoline in the PLT to bounce us to the distant function */ 170ed981856SPaul Mackerras static uint32_t do_plt_call(void *location, 171ed981856SPaul Mackerras Elf32_Addr val, 172136cd345SMichael Ellerman const Elf32_Shdr *sechdrs, 173ed981856SPaul Mackerras struct module *mod) 174ed981856SPaul Mackerras { 175ed981856SPaul Mackerras struct ppc_plt_entry *entry; 176ed981856SPaul Mackerras 177c7d1f6afSAnton Blanchard pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); 178ed981856SPaul Mackerras /* Init, or core PLT? */ 1797523e4dcSRusty Russell if (location >= mod->core_layout.base 1807523e4dcSRusty Russell && location < mod->core_layout.base + mod->core_layout.size) 181ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; 182ed981856SPaul Mackerras else 183ed981856SPaul Mackerras entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; 184ed981856SPaul Mackerras 185ed981856SPaul Mackerras /* Find this entry, or if that fails, the next avail. entry */ 186ed981856SPaul Mackerras while (entry->jump[0]) { 187ed981856SPaul Mackerras if (entry_matches(entry, val)) return (uint32_t)entry; 188ed981856SPaul Mackerras entry++; 189ed981856SPaul Mackerras } 190ed981856SPaul Mackerras 1913c752965SSteffen Rumler entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */ 1923c752965SSteffen Rumler entry->jump[1] = 0x398c0000 + (val&0xffff); /* addi r12,r12,sym@l*/ 1933c752965SSteffen Rumler entry->jump[2] = 0x7d8903a6; /* mtctr r12 */ 194ed981856SPaul Mackerras entry->jump[3] = 0x4e800420; /* bctr */ 195ed981856SPaul Mackerras 196c7d1f6afSAnton Blanchard pr_debug("Initialized plt for 0x%x at %p\n", val, entry); 197ed981856SPaul Mackerras return (uint32_t)entry; 198ed981856SPaul Mackerras } 199ed981856SPaul Mackerras 200ed981856SPaul Mackerras int apply_relocate_add(Elf32_Shdr *sechdrs, 201ed981856SPaul Mackerras const char *strtab, 202ed981856SPaul Mackerras unsigned int symindex, 203ed981856SPaul Mackerras unsigned int relsec, 204ed981856SPaul Mackerras struct module *module) 205ed981856SPaul Mackerras { 206ed981856SPaul Mackerras unsigned int i; 207ed981856SPaul Mackerras Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; 208ed981856SPaul Mackerras Elf32_Sym *sym; 209ed981856SPaul Mackerras uint32_t *location; 210ed981856SPaul Mackerras uint32_t value; 211ed981856SPaul Mackerras 212c7d1f6afSAnton Blanchard pr_debug("Applying ADD relocate section %u to %u\n", relsec, 213ed981856SPaul Mackerras sechdrs[relsec].sh_info); 214ed981856SPaul Mackerras for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { 215ed981856SPaul Mackerras /* This is where to make the change */ 216ed981856SPaul Mackerras location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 217ed981856SPaul Mackerras + rela[i].r_offset; 218ed981856SPaul Mackerras /* This is the symbol it is referring to. Note that all 219ed981856SPaul Mackerras undefined symbols have been resolved. */ 220ed981856SPaul Mackerras sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 221ed981856SPaul Mackerras + ELF32_R_SYM(rela[i].r_info); 222ed981856SPaul Mackerras /* `Everything is relative'. */ 223ed981856SPaul Mackerras value = sym->st_value + rela[i].r_addend; 224ed981856SPaul Mackerras 225ed981856SPaul Mackerras switch (ELF32_R_TYPE(rela[i].r_info)) { 226ed981856SPaul Mackerras case R_PPC_ADDR32: 227ed981856SPaul Mackerras /* Simply set it */ 228ed981856SPaul Mackerras *(uint32_t *)location = value; 229ed981856SPaul Mackerras break; 230ed981856SPaul Mackerras 231ed981856SPaul Mackerras case R_PPC_ADDR16_LO: 232ed981856SPaul Mackerras /* Low half of the symbol */ 233ed981856SPaul Mackerras *(uint16_t *)location = value; 234ed981856SPaul Mackerras break; 235ed981856SPaul Mackerras 2369a3d6458SSimon Vallet case R_PPC_ADDR16_HI: 2379a3d6458SSimon Vallet /* Higher half of the symbol */ 2389a3d6458SSimon Vallet *(uint16_t *)location = (value >> 16); 2399a3d6458SSimon Vallet break; 2409a3d6458SSimon Vallet 241ed981856SPaul Mackerras case R_PPC_ADDR16_HA: 242ed981856SPaul Mackerras /* Sign-adjusted lower 16 bits: PPC ELF ABI says: 243ed981856SPaul Mackerras (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. 244ed981856SPaul Mackerras This is the same, only sane. 245ed981856SPaul Mackerras */ 246ed981856SPaul Mackerras *(uint16_t *)location = (value + 0x8000) >> 16; 247ed981856SPaul Mackerras break; 248ed981856SPaul Mackerras 249ed981856SPaul Mackerras case R_PPC_REL24: 250ed981856SPaul Mackerras if ((int)(value - (uint32_t)location) < -0x02000000 251ed981856SPaul Mackerras || (int)(value - (uint32_t)location) >= 0x02000000) 252ed981856SPaul Mackerras value = do_plt_call(location, value, 253ed981856SPaul Mackerras sechdrs, module); 254ed981856SPaul Mackerras 255ed981856SPaul Mackerras /* Only replace bits 2 through 26 */ 256c7d1f6afSAnton Blanchard pr_debug("REL24 value = %08X. location = %08X\n", 257ed981856SPaul Mackerras value, (uint32_t)location); 258c7d1f6afSAnton Blanchard pr_debug("Location before: %08X.\n", 259ed981856SPaul Mackerras *(uint32_t *)location); 260ed981856SPaul Mackerras *(uint32_t *)location 261ed981856SPaul Mackerras = (*(uint32_t *)location & ~0x03fffffc) 262ed981856SPaul Mackerras | ((value - (uint32_t)location) 263ed981856SPaul Mackerras & 0x03fffffc); 264c7d1f6afSAnton Blanchard pr_debug("Location after: %08X.\n", 265ed981856SPaul Mackerras *(uint32_t *)location); 266c7d1f6afSAnton Blanchard pr_debug("ie. jump to %08X+%08X = %08X\n", 267ed981856SPaul Mackerras *(uint32_t *)location & 0x03fffffc, 268ed981856SPaul Mackerras (uint32_t)location, 269ed981856SPaul Mackerras (*(uint32_t *)location & 0x03fffffc) 270ed981856SPaul Mackerras + (uint32_t)location); 271ed981856SPaul Mackerras break; 272ed981856SPaul Mackerras 273ed981856SPaul Mackerras case R_PPC_REL32: 274ed981856SPaul Mackerras /* 32-bit relative jump. */ 275ed981856SPaul Mackerras *(uint32_t *)location = value - (uint32_t)location; 276ed981856SPaul Mackerras break; 277ed981856SPaul Mackerras 278ed981856SPaul Mackerras default: 279c7d1f6afSAnton Blanchard pr_err("%s: unknown ADD relocation: %u\n", 280ed981856SPaul Mackerras module->name, 281ed981856SPaul Mackerras ELF32_R_TYPE(rela[i].r_info)); 282ed981856SPaul Mackerras return -ENOEXEC; 283ed981856SPaul Mackerras } 284ed981856SPaul Mackerras } 285136cd345SMichael Ellerman 286ed981856SPaul Mackerras return 0; 287ed981856SPaul Mackerras } 288136cd345SMichael Ellerman 289136cd345SMichael Ellerman #ifdef CONFIG_DYNAMIC_FTRACE 290136cd345SMichael Ellerman int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs) 291136cd345SMichael Ellerman { 292136cd345SMichael Ellerman module->arch.tramp = do_plt_call(module->core_layout.base, 293136cd345SMichael Ellerman (unsigned long)ftrace_caller, 294136cd345SMichael Ellerman sechdrs, module); 295136cd345SMichael Ellerman if (!module->arch.tramp) 296136cd345SMichael Ellerman return -ENOENT; 297136cd345SMichael Ellerman 298136cd345SMichael Ellerman return 0; 299136cd345SMichael Ellerman } 300136cd345SMichael Ellerman #endif 301