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_Sxword r_addend; 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_Sxword r_addend = rela->r_addend; 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_addend == r_addend) { 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_addend = r_addend; 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 = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL); 123 if (!chains) { 124 printk(KERN_ERR 125 "module %s: no memory for symbol chain buffer\n", 126 me->name); 127 return -ENOMEM; 128 } 129 130 got->sh_size = 0; 131 got->sh_addralign = 8; 132 got->sh_type = SHT_NOBITS; 133 134 /* Examine all LITERAL relocations to find out what GOT entries 135 are required. This sizes the GOT section as well. */ 136 for (s = sechdrs; s < esechdrs; ++s) 137 if (s->sh_type == SHT_RELA) { 138 nrela = s->sh_size / sizeof(Elf64_Rela); 139 rela = (void *)hdr + s->sh_offset; 140 for (i = 0; i < nrela; ++i) 141 process_reloc_for_got(rela+i, chains, 142 &got->sh_size); 143 } 144 145 /* Free the memory we allocated. */ 146 for (i = 0; i < nsyms; ++i) { 147 struct got_entry *g, *n; 148 for (g = chains[i].next; g ; g = n) { 149 n = g->next; 150 kfree(g); 151 } 152 } 153 kfree(chains); 154 155 return 0; 156 } 157 158 int 159 apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, 160 unsigned int relsec, struct module *me) 161 { 162 printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name); 163 return -ENOEXEC; 164 } 165 166 int 167 apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, 168 unsigned int symindex, unsigned int relsec, 169 struct module *me) 170 { 171 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; 172 unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela); 173 Elf64_Sym *symtab, *sym; 174 void *base, *location; 175 unsigned long got, gp; 176 177 DEBUGP("Applying relocate section %u to %u\n", relsec, 178 sechdrs[relsec].sh_info); 179 180 base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr; 181 symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr; 182 183 /* The small sections were sorted to the end of the segment. 184 The following should definitely cover them. */ 185 gp = (u64)me->module_core + me->core_size - 0x8000; 186 got = sechdrs[me->arch.gotsecindex].sh_addr; 187 188 for (i = 0; i < n; i++) { 189 unsigned long r_sym = ELF64_R_SYM (rela[i].r_info); 190 unsigned long r_type = ELF64_R_TYPE (rela[i].r_info); 191 unsigned long r_got_offset = r_type >> 8; 192 unsigned long value, hi, lo; 193 r_type &= 0xff; 194 195 /* This is where to make the change. */ 196 location = base + rela[i].r_offset; 197 198 /* This is the symbol it is referring to. Note that all 199 unresolved symbols have been resolved. */ 200 sym = symtab + r_sym; 201 value = sym->st_value + rela[i].r_addend; 202 203 switch (r_type) { 204 case R_ALPHA_NONE: 205 break; 206 case R_ALPHA_REFQUAD: 207 /* BUG() can produce misaligned relocations. */ 208 ((u32 *)location)[0] = value; 209 ((u32 *)location)[1] = value >> 32; 210 break; 211 case R_ALPHA_GPREL32: 212 value -= gp; 213 if ((int)value != value) 214 goto reloc_overflow; 215 *(u32 *)location = value; 216 break; 217 case R_ALPHA_LITERAL: 218 hi = got + r_got_offset; 219 lo = hi - gp; 220 if ((short)lo != lo) 221 goto reloc_overflow; 222 *(u16 *)location = lo; 223 *(u64 *)hi = value; 224 break; 225 case R_ALPHA_LITUSE: 226 break; 227 case R_ALPHA_GPDISP: 228 value = gp - (u64)location; 229 lo = (short)value; 230 hi = (int)(value - lo); 231 if (hi + lo != value) 232 goto reloc_overflow; 233 *(u16 *)location = hi >> 16; 234 *(u16 *)(location + rela[i].r_addend) = lo; 235 break; 236 case R_ALPHA_BRSGP: 237 /* BRSGP is only allowed to bind to local symbols. 238 If the section is undef, this means that the 239 value was resolved from somewhere else. */ 240 if (sym->st_shndx == SHN_UNDEF) 241 goto reloc_overflow; 242 if ((sym->st_other & STO_ALPHA_STD_GPLOAD) == 243 STO_ALPHA_STD_GPLOAD) 244 /* Omit the prologue. */ 245 value += 8; 246 /* FALLTHRU */ 247 case R_ALPHA_BRADDR: 248 value -= (u64)location + 4; 249 if (value & 3) 250 goto reloc_overflow; 251 value = (long)value >> 2; 252 if (value + (1<<21) >= 1<<22) 253 goto reloc_overflow; 254 value &= 0x1fffff; 255 value |= *(u32 *)location & ~0x1fffff; 256 *(u32 *)location = value; 257 break; 258 case R_ALPHA_HINT: 259 break; 260 case R_ALPHA_SREL32: 261 value -= (u64)location; 262 if ((int)value != value) 263 goto reloc_overflow; 264 *(u32 *)location = value; 265 break; 266 case R_ALPHA_SREL64: 267 value -= (u64)location; 268 *(u64 *)location = value; 269 break; 270 case R_ALPHA_GPRELHIGH: 271 value = (long)(value - gp + 0x8000) >> 16; 272 if ((short) value != value) 273 goto reloc_overflow; 274 *(u16 *)location = value; 275 break; 276 case R_ALPHA_GPRELLOW: 277 value -= gp; 278 *(u16 *)location = value; 279 break; 280 case R_ALPHA_GPREL16: 281 value -= gp; 282 if ((short) value != value) 283 goto reloc_overflow; 284 *(u16 *)location = value; 285 break; 286 default: 287 printk(KERN_ERR "module %s: Unknown relocation: %lu\n", 288 me->name, r_type); 289 return -ENOEXEC; 290 reloc_overflow: 291 if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION) 292 printk(KERN_ERR 293 "module %s: Relocation (type %lu) overflow vs section %d\n", 294 me->name, r_type, sym->st_shndx); 295 else 296 printk(KERN_ERR 297 "module %s: Relocation (type %lu) overflow vs %s\n", 298 me->name, r_type, strtab + sym->st_name); 299 return -ENOEXEC; 300 } 301 } 302 303 return 0; 304 } 305 306 int 307 module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, 308 struct module *me) 309 { 310 return 0; 311 } 312 313 void 314 module_arch_cleanup(struct module *mod) 315 { 316 } 317