Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* Kernel module help for Alpha. |
| 2 | Copyright (C) 2002 Richard Henderson. |
| 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 | #include <linux/moduleloader.h> |
| 19 | #include <linux/elf.h> |
| 20 | #include <linux/vmalloc.h> |
| 21 | #include <linux/fs.h> |
| 22 | #include <linux/string.h> |
| 23 | #include <linux/kernel.h> |
| 24 | #include <linux/slab.h> |
| 25 | |
| 26 | #if 0 |
| 27 | #define DEBUGP printk |
| 28 | #else |
| 29 | #define DEBUGP(fmt...) |
| 30 | #endif |
| 31 | |
| 32 | void * |
| 33 | module_alloc(unsigned long size) |
| 34 | { |
| 35 | if (size == 0) |
| 36 | return NULL; |
| 37 | return vmalloc(size); |
| 38 | } |
| 39 | |
| 40 | void |
| 41 | module_free(struct module *mod, void *module_region) |
| 42 | { |
| 43 | vfree(module_region); |
| 44 | } |
| 45 | |
| 46 | /* Allocate the GOT at the end of the core sections. */ |
| 47 | |
| 48 | struct got_entry { |
| 49 | struct got_entry *next; |
| 50 | Elf64_Addr r_offset; |
| 51 | int got_offset; |
| 52 | }; |
| 53 | |
| 54 | static inline void |
| 55 | process_reloc_for_got(Elf64_Rela *rela, |
| 56 | struct got_entry *chains, Elf64_Xword *poffset) |
| 57 | { |
| 58 | unsigned long r_sym = ELF64_R_SYM (rela->r_info); |
| 59 | unsigned long r_type = ELF64_R_TYPE (rela->r_info); |
| 60 | Elf64_Addr r_offset = rela->r_offset; |
| 61 | struct got_entry *g; |
| 62 | |
| 63 | if (r_type != R_ALPHA_LITERAL) |
| 64 | return; |
| 65 | |
| 66 | for (g = chains + r_sym; g ; g = g->next) |
| 67 | if (g->r_offset == r_offset) { |
| 68 | if (g->got_offset == 0) { |
| 69 | g->got_offset = *poffset; |
| 70 | *poffset += 8; |
| 71 | } |
| 72 | goto found_entry; |
| 73 | } |
| 74 | |
| 75 | g = kmalloc (sizeof (*g), GFP_KERNEL); |
| 76 | g->next = chains[r_sym].next; |
| 77 | g->r_offset = r_offset; |
| 78 | g->got_offset = *poffset; |
| 79 | *poffset += 8; |
| 80 | chains[r_sym].next = g; |
| 81 | |
| 82 | found_entry: |
| 83 | /* Trick: most of the ELF64_R_TYPE field is unused. There are |
| 84 | 42 valid relocation types, and a 32-bit field. Co-opt the |
| 85 | bits above 256 to store the got offset for this reloc. */ |
| 86 | rela->r_info |= g->got_offset << 8; |
| 87 | } |
| 88 | |
| 89 | int |
| 90 | module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs, |
| 91 | char *secstrings, struct module *me) |
| 92 | { |
| 93 | struct got_entry *chains; |
| 94 | Elf64_Rela *rela; |
| 95 | Elf64_Shdr *esechdrs, *symtab, *s, *got; |
| 96 | unsigned long nsyms, nrela, i; |
| 97 | |
| 98 | esechdrs = sechdrs + hdr->e_shnum; |
| 99 | symtab = got = NULL; |
| 100 | |
| 101 | /* Find out how large the symbol table is. Allocate one got_entry |
| 102 | head per symbol. Normally this will be enough, but not always. |
| 103 | We'll chain different offsets for the symbol down each head. */ |
| 104 | for (s = sechdrs; s < esechdrs; ++s) |
| 105 | if (s->sh_type == SHT_SYMTAB) |
| 106 | symtab = s; |
| 107 | else if (!strcmp(".got", secstrings + s->sh_name)) { |
| 108 | got = s; |
| 109 | me->arch.gotsecindex = s - sechdrs; |
| 110 | } |
| 111 | |
| 112 | if (!symtab) { |
| 113 | printk(KERN_ERR "module %s: no symbol table\n", me->name); |
| 114 | return -ENOEXEC; |
| 115 | } |
| 116 | if (!got) { |
| 117 | printk(KERN_ERR "module %s: no got section\n", me->name); |
| 118 | return -ENOEXEC; |
| 119 | } |
| 120 | |
| 121 | nsyms = symtab->sh_size / sizeof(Elf64_Sym); |
| 122 | chains = kmalloc(nsyms * sizeof(struct got_entry), GFP_KERNEL); |
| 123 | memset(chains, 0, nsyms * sizeof(struct got_entry)); |
| 124 | |
| 125 | got->sh_size = 0; |
| 126 | got->sh_addralign = 8; |
| 127 | got->sh_type = SHT_NOBITS; |
| 128 | |
| 129 | /* Examine all LITERAL relocations to find out what GOT entries |
| 130 | are required. This sizes the GOT section as well. */ |
| 131 | for (s = sechdrs; s < esechdrs; ++s) |
| 132 | if (s->sh_type == SHT_RELA) { |
| 133 | nrela = s->sh_size / sizeof(Elf64_Rela); |
| 134 | rela = (void *)hdr + s->sh_offset; |
| 135 | for (i = 0; i < nrela; ++i) |
| 136 | process_reloc_for_got(rela+i, chains, |
| 137 | &got->sh_size); |
| 138 | } |
| 139 | |
| 140 | /* Free the memory we allocated. */ |
| 141 | for (i = 0; i < nsyms; ++i) { |
| 142 | struct got_entry *g, *n; |
| 143 | for (g = chains[i].next; g ; g = n) { |
| 144 | n = g->next; |
| 145 | kfree(g); |
| 146 | } |
| 147 | } |
| 148 | kfree(chains); |
| 149 | |
| 150 | return 0; |
| 151 | } |
| 152 | |
| 153 | int |
| 154 | apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, |
| 155 | unsigned int relsec, struct module *me) |
| 156 | { |
| 157 | printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name); |
| 158 | return -ENOEXEC; |
| 159 | } |
| 160 | |
| 161 | int |
| 162 | apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, |
| 163 | unsigned int symindex, unsigned int relsec, |
| 164 | struct module *me) |
| 165 | { |
| 166 | Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; |
| 167 | unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela); |
| 168 | Elf64_Sym *symtab, *sym; |
| 169 | void *base, *location; |
| 170 | unsigned long got, gp; |
| 171 | |
| 172 | DEBUGP("Applying relocate section %u to %u\n", relsec, |
| 173 | sechdrs[relsec].sh_info); |
| 174 | |
| 175 | base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr; |
| 176 | symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr; |
| 177 | |
| 178 | /* The small sections were sorted to the end of the segment. |
| 179 | The following should definitely cover them. */ |
| 180 | gp = (u64)me->module_core + me->core_size - 0x8000; |
| 181 | got = sechdrs[me->arch.gotsecindex].sh_addr; |
| 182 | |
| 183 | for (i = 0; i < n; i++) { |
| 184 | unsigned long r_sym = ELF64_R_SYM (rela[i].r_info); |
| 185 | unsigned long r_type = ELF64_R_TYPE (rela[i].r_info); |
| 186 | unsigned long r_got_offset = r_type >> 8; |
| 187 | unsigned long value, hi, lo; |
| 188 | r_type &= 0xff; |
| 189 | |
| 190 | /* This is where to make the change. */ |
| 191 | location = base + rela[i].r_offset; |
| 192 | |
| 193 | /* This is the symbol it is referring to. Note that all |
| 194 | unresolved symbols have been resolved. */ |
| 195 | sym = symtab + r_sym; |
| 196 | value = sym->st_value + rela[i].r_addend; |
| 197 | |
| 198 | switch (r_type) { |
| 199 | case R_ALPHA_NONE: |
| 200 | break; |
| 201 | case R_ALPHA_REFQUAD: |
| 202 | /* BUG() can produce misaligned relocations. */ |
| 203 | ((u32 *)location)[0] = value; |
| 204 | ((u32 *)location)[1] = value >> 32; |
| 205 | break; |
| 206 | case R_ALPHA_GPREL32: |
| 207 | value -= gp; |
| 208 | if ((int)value != value) |
| 209 | goto reloc_overflow; |
| 210 | *(u32 *)location = value; |
| 211 | break; |
| 212 | case R_ALPHA_LITERAL: |
| 213 | hi = got + r_got_offset; |
| 214 | lo = hi - gp; |
| 215 | if ((short)lo != lo) |
| 216 | goto reloc_overflow; |
| 217 | *(u16 *)location = lo; |
| 218 | *(u64 *)hi = value; |
| 219 | break; |
| 220 | case R_ALPHA_LITUSE: |
| 221 | break; |
| 222 | case R_ALPHA_GPDISP: |
| 223 | value = gp - (u64)location; |
| 224 | lo = (short)value; |
| 225 | hi = (int)(value - lo); |
| 226 | if (hi + lo != value) |
| 227 | goto reloc_overflow; |
| 228 | *(u16 *)location = hi >> 16; |
| 229 | *(u16 *)(location + rela[i].r_addend) = lo; |
| 230 | break; |
| 231 | case R_ALPHA_BRSGP: |
| 232 | /* BRSGP is only allowed to bind to local symbols. |
| 233 | If the section is undef, this means that the |
| 234 | value was resolved from somewhere else. */ |
| 235 | if (sym->st_shndx == SHN_UNDEF) |
| 236 | goto reloc_overflow; |
| 237 | if ((sym->st_other & STO_ALPHA_STD_GPLOAD) == |
| 238 | STO_ALPHA_STD_GPLOAD) |
| 239 | /* Omit the prologue. */ |
| 240 | value += 8; |
| 241 | /* FALLTHRU */ |
| 242 | case R_ALPHA_BRADDR: |
| 243 | value -= (u64)location + 4; |
| 244 | if (value & 3) |
| 245 | goto reloc_overflow; |
| 246 | value = (long)value >> 2; |
| 247 | if (value + (1<<21) >= 1<<22) |
| 248 | goto reloc_overflow; |
| 249 | value &= 0x1fffff; |
| 250 | value |= *(u32 *)location & ~0x1fffff; |
| 251 | *(u32 *)location = value; |
| 252 | break; |
| 253 | case R_ALPHA_HINT: |
| 254 | break; |
| 255 | case R_ALPHA_SREL32: |
| 256 | value -= (u64)location; |
| 257 | if ((int)value != value) |
| 258 | goto reloc_overflow; |
| 259 | *(u32 *)location = value; |
| 260 | break; |
| 261 | case R_ALPHA_SREL64: |
| 262 | value -= (u64)location; |
| 263 | *(u64 *)location = value; |
| 264 | break; |
| 265 | case R_ALPHA_GPRELHIGH: |
| 266 | value = (long)(value - gp + 0x8000) >> 16; |
| 267 | if ((short) value != value) |
| 268 | goto reloc_overflow; |
| 269 | *(u16 *)location = value; |
| 270 | break; |
| 271 | case R_ALPHA_GPRELLOW: |
| 272 | value -= gp; |
| 273 | *(u16 *)location = value; |
| 274 | break; |
| 275 | case R_ALPHA_GPREL16: |
| 276 | value -= gp; |
| 277 | if ((short) value != value) |
| 278 | goto reloc_overflow; |
| 279 | *(u16 *)location = value; |
| 280 | break; |
| 281 | default: |
| 282 | printk(KERN_ERR "module %s: Unknown relocation: %lu\n", |
| 283 | me->name, r_type); |
| 284 | return -ENOEXEC; |
| 285 | reloc_overflow: |
| 286 | if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION) |
| 287 | printk(KERN_ERR |
| 288 | "module %s: Relocation overflow vs section %d\n", |
| 289 | me->name, sym->st_shndx); |
| 290 | else |
| 291 | printk(KERN_ERR |
| 292 | "module %s: Relocation overflow vs %s\n", |
| 293 | me->name, strtab + sym->st_name); |
| 294 | return -ENOEXEC; |
| 295 | } |
| 296 | } |
| 297 | |
| 298 | return 0; |
| 299 | } |
| 300 | |
| 301 | int |
| 302 | module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, |
| 303 | struct module *me) |
| 304 | { |
| 305 | return 0; |
| 306 | } |
| 307 | |
| 308 | void |
| 309 | module_arch_cleanup(struct module *mod) |
| 310 | { |
| 311 | } |