1 /* Kernel module help for x86. 2 Copyright (C) 2001 Rusty Russell. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software 16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/moduleloader.h> 22 #include <linux/elf.h> 23 #include <linux/vmalloc.h> 24 #include <linux/fs.h> 25 #include <linux/string.h> 26 #include <linux/kernel.h> 27 #include <linux/bug.h> 28 #include <linux/mm.h> 29 #include <linux/gfp.h> 30 #include <linux/jump_label.h> 31 32 #include <asm/page.h> 33 #include <asm/pgtable.h> 34 35 #if 0 36 #define DEBUGP(fmt, ...) \ 37 printk(KERN_DEBUG fmt, ##__VA_ARGS__) 38 #else 39 #define DEBUGP(fmt, ...) \ 40 do { \ 41 if (0) \ 42 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \ 43 } while (0) 44 #endif 45 46 void *module_alloc(unsigned long size) 47 { 48 if (PAGE_ALIGN(size) > MODULES_LEN) 49 return NULL; 50 return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, 51 GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC, 52 -1, __builtin_return_address(0)); 53 } 54 55 #ifdef CONFIG_X86_32 56 int apply_relocate(Elf32_Shdr *sechdrs, 57 const char *strtab, 58 unsigned int symindex, 59 unsigned int relsec, 60 struct module *me) 61 { 62 unsigned int i; 63 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr; 64 Elf32_Sym *sym; 65 uint32_t *location; 66 67 DEBUGP("Applying relocate section %u to %u\n", 68 relsec, sechdrs[relsec].sh_info); 69 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 70 /* This is where to make the change */ 71 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 72 + rel[i].r_offset; 73 /* This is the symbol it is referring to. Note that all 74 undefined symbols have been resolved. */ 75 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 76 + ELF32_R_SYM(rel[i].r_info); 77 78 switch (ELF32_R_TYPE(rel[i].r_info)) { 79 case R_386_32: 80 /* We add the value into the location given */ 81 *location += sym->st_value; 82 break; 83 case R_386_PC32: 84 /* Add the value, subtract its position */ 85 *location += sym->st_value - (uint32_t)location; 86 break; 87 default: 88 pr_err("%s: Unknown relocation: %u\n", 89 me->name, ELF32_R_TYPE(rel[i].r_info)); 90 return -ENOEXEC; 91 } 92 } 93 return 0; 94 } 95 #else /*X86_64*/ 96 int apply_relocate_add(Elf64_Shdr *sechdrs, 97 const char *strtab, 98 unsigned int symindex, 99 unsigned int relsec, 100 struct module *me) 101 { 102 unsigned int i; 103 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; 104 Elf64_Sym *sym; 105 void *loc; 106 u64 val; 107 108 DEBUGP("Applying relocate section %u to %u\n", 109 relsec, sechdrs[relsec].sh_info); 110 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 111 /* This is where to make the change */ 112 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 113 + rel[i].r_offset; 114 115 /* This is the symbol it is referring to. Note that all 116 undefined symbols have been resolved. */ 117 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr 118 + ELF64_R_SYM(rel[i].r_info); 119 120 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n", 121 (int)ELF64_R_TYPE(rel[i].r_info), 122 sym->st_value, rel[i].r_addend, (u64)loc); 123 124 val = sym->st_value + rel[i].r_addend; 125 126 switch (ELF64_R_TYPE(rel[i].r_info)) { 127 case R_X86_64_NONE: 128 break; 129 case R_X86_64_64: 130 *(u64 *)loc = val; 131 break; 132 case R_X86_64_32: 133 *(u32 *)loc = val; 134 if (val != *(u32 *)loc) 135 goto overflow; 136 break; 137 case R_X86_64_32S: 138 *(s32 *)loc = val; 139 if ((s64)val != *(s32 *)loc) 140 goto overflow; 141 break; 142 case R_X86_64_PC32: 143 val -= (u64)loc; 144 *(u32 *)loc = val; 145 #if 0 146 if ((s64)val != *(s32 *)loc) 147 goto overflow; 148 #endif 149 break; 150 default: 151 pr_err("%s: Unknown rela relocation: %llu\n", 152 me->name, ELF64_R_TYPE(rel[i].r_info)); 153 return -ENOEXEC; 154 } 155 } 156 return 0; 157 158 overflow: 159 pr_err("overflow in relocation type %d val %Lx\n", 160 (int)ELF64_R_TYPE(rel[i].r_info), val); 161 pr_err("`%s' likely not compiled with -mcmodel=kernel\n", 162 me->name); 163 return -ENOEXEC; 164 } 165 #endif 166 167 int module_finalize(const Elf_Ehdr *hdr, 168 const Elf_Shdr *sechdrs, 169 struct module *me) 170 { 171 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL, 172 *para = NULL; 173 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 174 175 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 176 if (!strcmp(".text", secstrings + s->sh_name)) 177 text = s; 178 if (!strcmp(".altinstructions", secstrings + s->sh_name)) 179 alt = s; 180 if (!strcmp(".smp_locks", secstrings + s->sh_name)) 181 locks = s; 182 if (!strcmp(".parainstructions", secstrings + s->sh_name)) 183 para = s; 184 } 185 186 if (alt) { 187 /* patch .altinstructions */ 188 void *aseg = (void *)alt->sh_addr; 189 apply_alternatives(aseg, aseg + alt->sh_size); 190 } 191 if (locks && text) { 192 void *lseg = (void *)locks->sh_addr; 193 void *tseg = (void *)text->sh_addr; 194 alternatives_smp_module_add(me, me->name, 195 lseg, lseg + locks->sh_size, 196 tseg, tseg + text->sh_size); 197 } 198 199 if (para) { 200 void *pseg = (void *)para->sh_addr; 201 apply_paravirt(pseg, pseg + para->sh_size); 202 } 203 204 /* make jump label nops */ 205 jump_label_apply_nops(me); 206 207 return 0; 208 } 209 210 void module_arch_cleanup(struct module *mod) 211 { 212 alternatives_smp_module_del(mod); 213 } 214