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#define DEBUGP(fmt...) 27 28void * 29module_alloc(unsigned long size) 30{ 31 if (size == 0) 32 return NULL; 33 return vmalloc(size); 34} 35 36void 37module_free(struct module *mod, void *module_region) 38{ 39 vfree(module_region); 40} 41 42/* Allocate the GOT at the end of the core sections. */ 43 44struct got_entry { 45 struct got_entry *next; 46 Elf64_Sxword r_addend; 47 int got_offset; 48}; 49 50static inline void 51process_reloc_for_got(Elf64_Rela *rela, 52 struct got_entry *chains, Elf64_Xword *poffset) 53{ 54 unsigned long r_sym = ELF64_R_SYM (rela->r_info); 55 unsigned long r_type = ELF64_R_TYPE (rela->r_info); 56 Elf64_Sxword r_addend = rela->r_addend; 57 struct got_entry *g; 58 59 if (r_type != R_ALPHA_LITERAL) 60 return; 61 62 for (g = chains + r_sym; g ; g = g->next) 63 if (g->r_addend == r_addend) { 64 if (g->got_offset == 0) { 65 g->got_offset = *poffset; 66 *poffset += 8; 67 } 68 goto found_entry; 69 } 70 71 g = kmalloc (sizeof (*g), GFP_KERNEL); 72 g->next = chains[r_sym].next; 73 g->r_addend = r_addend; 74 g->got_offset = *poffset; 75 *poffset += 8; 76 chains[r_sym].next = g; 77 78 found_entry: 79 /* Trick: most of the ELF64_R_TYPE field is unused. There are 80 42 valid relocation types, and a 32-bit field. Co-opt the 81 bits above 256 to store the got offset for this reloc. */ 82 rela->r_info |= g->got_offset << 8; 83} 84 85int 86module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs, 87 char *secstrings, struct module *me) 88{ 89 struct got_entry *chains; 90 Elf64_Rela *rela; 91 Elf64_Shdr *esechdrs, *symtab, *s, *got; 92 unsigned long nsyms, nrela, i; 93 94 esechdrs = sechdrs + hdr->e_shnum; 95 symtab = got = NULL; 96 97 /* Find out how large the symbol table is. Allocate one got_entry 98 head per symbol. Normally this will be enough, but not always. 99 We'll chain different offsets for the symbol down each head. */ 100 for (s = sechdrs; s < esechdrs; ++s) 101 if (s->sh_type == SHT_SYMTAB) 102 symtab = s; 103 else if (!strcmp(".got", secstrings + s->sh_name)) { 104 got = s; 105 me->arch.gotsecindex = s - sechdrs; 106 } 107 108 if (!symtab) { 109 printk(KERN_ERR "module %s: no symbol table\n", me->name); 110 return -ENOEXEC; 111 } 112 if (!got) { 113 printk(KERN_ERR "module %s: no got section\n", me->name); 114 return -ENOEXEC; 115 } 116 117 nsyms = symtab->sh_size / sizeof(Elf64_Sym); 118 chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL); 119 if (!chains) { 120 printk(KERN_ERR 121 "module %s: no memory for symbol chain buffer\n", 122 me->name); 123 return -ENOMEM; 124 } 125 126 got->sh_size = 0; 127 got->sh_addralign = 8; 128 got->sh_type = SHT_NOBITS; 129 130 /* Examine all LITERAL relocations to find out what GOT entries 131 are required. This sizes the GOT section as well. */ 132 for (s = sechdrs; s < esechdrs; ++s) 133 if (s->sh_type == SHT_RELA) { 134 nrela = s->sh_size / sizeof(Elf64_Rela); 135 rela = (void *)hdr + s->sh_offset; 136 for (i = 0; i < nrela; ++i) 137 process_reloc_for_got(rela+i, chains, 138 &got->sh_size); 139 } 140 141 /* Free the memory we allocated. */ 142 for (i = 0; i < nsyms; ++i) { 143 struct got_entry *g, *n; 144 for (g = chains[i].next; g ; g = n) { 145 n = g->next; 146 kfree(g); 147 } 148 } 149 kfree(chains); 150 151 return 0; 152} 153 154int 155apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, 156 unsigned int relsec, struct module *me) 157{ 158 printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name); 159 return -ENOEXEC; 160} 161 162int 163apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, 164 unsigned int symindex, unsigned int relsec, 165 struct module *me) 166{ 167 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; 168 unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela); 169 Elf64_Sym *symtab, *sym; 170 void *base, *location; 171 unsigned long got, gp; 172 173 DEBUGP("Applying relocate section %u to %u\n", relsec, 174 sechdrs[relsec].sh_info); 175 176 base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr; 177 symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr; 178 179 /* The small sections were sorted to the end of the segment. 180 The following should definitely cover them. */ 181 gp = (u64)me->module_core + me->core_size - 0x8000; 182 got = sechdrs[me->arch.gotsecindex].sh_addr; 183 184 for (i = 0; i < n; i++) { 185 unsigned long r_sym = ELF64_R_SYM (rela[i].r_info); 186 unsigned long r_type = ELF64_R_TYPE (rela[i].r_info); 187 unsigned long r_got_offset = r_type >> 8; 188 unsigned long value, hi, lo; 189 r_type &= 0xff; 190 191 /* This is where to make the change. */ 192 location = base + rela[i].r_offset; 193 194 /* This is the symbol it is referring to. Note that all 195 unresolved symbols have been resolved. */ 196 sym = symtab + r_sym; 197 value = sym->st_value + rela[i].r_addend; 198 199 switch (r_type) { 200 case R_ALPHA_NONE: 201 break; 202 case R_ALPHA_REFQUAD: 203 /* BUG() can produce misaligned relocations. */ 204 ((u32 *)location)[0] = value; 205 ((u32 *)location)[1] = value >> 32; 206 break; 207 case R_ALPHA_GPREL32: 208 value -= gp; 209 if ((int)value != value) 210 goto reloc_overflow; 211 *(u32 *)location = value; 212 break; 213 case R_ALPHA_LITERAL: 214 hi = got + r_got_offset; 215 lo = hi - gp; 216 if ((short)lo != lo) 217 goto reloc_overflow; 218 *(u16 *)location = lo; 219 *(u64 *)hi = value; 220 break; 221 case R_ALPHA_LITUSE: 222 break; 223 case R_ALPHA_GPDISP: 224 value = gp - (u64)location; 225 lo = (short)value; 226 hi = (int)(value - lo); 227 if (hi + lo != value) 228 goto reloc_overflow; 229 *(u16 *)location = hi >> 16; 230 *(u16 *)(location + rela[i].r_addend) = lo; 231 break; 232 case R_ALPHA_BRSGP: 233 /* BRSGP is only allowed to bind to local symbols. 234 If the section is undef, this means that the 235 value was resolved from somewhere else. */ 236 if (sym->st_shndx == SHN_UNDEF) 237 goto reloc_overflow; 238 if ((sym->st_other & STO_ALPHA_STD_GPLOAD) == 239 STO_ALPHA_STD_GPLOAD) 240 /* Omit the prologue. */ 241 value += 8; 242 /* FALLTHRU */ 243 case R_ALPHA_BRADDR: 244 value -= (u64)location + 4; 245 if (value & 3) 246 goto reloc_overflow; 247 value = (long)value >> 2; 248 if (value + (1<<21) >= 1<<22) 249 goto reloc_overflow; 250 value &= 0x1fffff; 251 value |= *(u32 *)location & ~0x1fffff; 252 *(u32 *)location = value; 253 break; 254 case R_ALPHA_HINT: 255 break; 256 case R_ALPHA_SREL32: 257 value -= (u64)location; 258 if ((int)value != value) 259 goto reloc_overflow; 260 *(u32 *)location = value; 261 break; 262 case R_ALPHA_SREL64: 263 value -= (u64)location; 264 *(u64 *)location = value; 265 break; 266 case R_ALPHA_GPRELHIGH: 267 value = (long)(value - gp + 0x8000) >> 16; 268 if ((short) value != value) 269 goto reloc_overflow; 270 *(u16 *)location = value; 271 break; 272 case R_ALPHA_GPRELLOW: 273 value -= gp; 274 *(u16 *)location = value; 275 break; 276 case R_ALPHA_GPREL16: 277 value -= gp; 278 if ((short) value != value) 279 goto reloc_overflow; 280 *(u16 *)location = value; 281 break; 282 default: 283 printk(KERN_ERR "module %s: Unknown relocation: %lu\n", 284 me->name, r_type); 285 return -ENOEXEC; 286 reloc_overflow: 287 if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION) 288 printk(KERN_ERR 289 "module %s: Relocation (type %lu) overflow vs section %d\n", 290 me->name, r_type, sym->st_shndx); 291 else 292 printk(KERN_ERR 293 "module %s: Relocation (type %lu) overflow vs %s\n", 294 me->name, r_type, strtab + sym->st_name); 295 return -ENOEXEC; 296 } 297 } 298 299 return 0; 300} 301 302int 303module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, 304 struct module *me) 305{ 306 return 0; 307} 308 309void 310module_arch_cleanup(struct module *mod) 311{ 312} 313