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 = kmalloc(nsyms * sizeof(struct got_entry), GFP_KERNEL); 119 memset(chains, 0, nsyms * sizeof(struct got_entry)); 120 121 got->sh_size = 0; 122 got->sh_addralign = 8; 123 got->sh_type = SHT_NOBITS; 124 125 /* Examine all LITERAL relocations to find out what GOT entries 126 are required. This sizes the GOT section as well. */ 127 for (s = sechdrs; s < esechdrs; ++s) 128 if (s->sh_type == SHT_RELA) { 129 nrela = s->sh_size / sizeof(Elf64_Rela); 130 rela = (void *)hdr + s->sh_offset; 131 for (i = 0; i < nrela; ++i) 132 process_reloc_for_got(rela+i, chains, 133 &got->sh_size); 134 } 135 136 /* Free the memory we allocated. */ 137 for (i = 0; i < nsyms; ++i) { 138 struct got_entry *g, *n; 139 for (g = chains[i].next; g ; g = n) { 140 n = g->next; 141 kfree(g); 142 } 143 } 144 kfree(chains); 145 146 return 0; 147} 148 149int 150apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, 151 unsigned int relsec, struct module *me) 152{ 153 printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name); 154 return -ENOEXEC; 155} 156 157int 158apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, 159 unsigned int symindex, unsigned int relsec, 160 struct module *me) 161{ 162 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; 163 unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela); 164 Elf64_Sym *symtab, *sym; 165 void *base, *location; 166 unsigned long got, gp; 167 168 DEBUGP("Applying relocate section %u to %u\n", relsec, 169 sechdrs[relsec].sh_info); 170 171 base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr; 172 symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr; 173 174 /* The small sections were sorted to the end of the segment. 175 The following should definitely cover them. */ 176 gp = (u64)me->module_core + me->core_size - 0x8000; 177 got = sechdrs[me->arch.gotsecindex].sh_addr; 178 179 for (i = 0; i < n; i++) { 180 unsigned long r_sym = ELF64_R_SYM (rela[i].r_info); 181 unsigned long r_type = ELF64_R_TYPE (rela[i].r_info); 182 unsigned long r_got_offset = r_type >> 8; 183 unsigned long value, hi, lo; 184 r_type &= 0xff; 185 186 /* This is where to make the change. */ 187 location = base + rela[i].r_offset; 188 189 /* This is the symbol it is referring to. Note that all 190 unresolved symbols have been resolved. */ 191 sym = symtab + r_sym; 192 value = sym->st_value + rela[i].r_addend; 193 194 switch (r_type) { 195 case R_ALPHA_NONE: 196 break; 197 case R_ALPHA_REFQUAD: 198 /* BUG() can produce misaligned relocations. */ 199 ((u32 *)location)[0] = value; 200 ((u32 *)location)[1] = value >> 32; 201 break; 202 case R_ALPHA_GPREL32: 203 value -= gp; 204 if ((int)value != value) 205 goto reloc_overflow; 206 *(u32 *)location = value; 207 break; 208 case R_ALPHA_LITERAL: 209 hi = got + r_got_offset; 210 lo = hi - gp; 211 if ((short)lo != lo) 212 goto reloc_overflow; 213 *(u16 *)location = lo; 214 *(u64 *)hi = value; 215 break; 216 case R_ALPHA_LITUSE: 217 break; 218 case R_ALPHA_GPDISP: 219 value = gp - (u64)location; 220 lo = (short)value; 221 hi = (int)(value - lo); 222 if (hi + lo != value) 223 goto reloc_overflow; 224 *(u16 *)location = hi >> 16; 225 *(u16 *)(location + rela[i].r_addend) = lo; 226 break; 227 case R_ALPHA_BRSGP: 228 /* BRSGP is only allowed to bind to local symbols. 229 If the section is undef, this means that the 230 value was resolved from somewhere else. */ 231 if (sym->st_shndx == SHN_UNDEF) 232 goto reloc_overflow; 233 if ((sym->st_other & STO_ALPHA_STD_GPLOAD) == 234 STO_ALPHA_STD_GPLOAD) 235 /* Omit the prologue. */ 236 value += 8; 237 /* FALLTHRU */ 238 case R_ALPHA_BRADDR: 239 value -= (u64)location + 4; 240 if (value & 3) 241 goto reloc_overflow; 242 value = (long)value >> 2; 243 if (value + (1<<21) >= 1<<22) 244 goto reloc_overflow; 245 value &= 0x1fffff; 246 value |= *(u32 *)location & ~0x1fffff; 247 *(u32 *)location = value; 248 break; 249 case R_ALPHA_HINT: 250 break; 251 case R_ALPHA_SREL32: 252 value -= (u64)location; 253 if ((int)value != value) 254 goto reloc_overflow; 255 *(u32 *)location = value; 256 break; 257 case R_ALPHA_SREL64: 258 value -= (u64)location; 259 *(u64 *)location = value; 260 break; 261 case R_ALPHA_GPRELHIGH: 262 value = (long)(value - gp + 0x8000) >> 16; 263 if ((short) value != value) 264 goto reloc_overflow; 265 *(u16 *)location = value; 266 break; 267 case R_ALPHA_GPRELLOW: 268 value -= gp; 269 *(u16 *)location = value; 270 break; 271 case R_ALPHA_GPREL16: 272 value -= gp; 273 if ((short) value != value) 274 goto reloc_overflow; 275 *(u16 *)location = value; 276 break; 277 default: 278 printk(KERN_ERR "module %s: Unknown relocation: %lu\n", 279 me->name, r_type); 280 return -ENOEXEC; 281 reloc_overflow: 282 if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION) 283 printk(KERN_ERR 284 "module %s: Relocation (type %lu) overflow vs section %d\n", 285 me->name, r_type, sym->st_shndx); 286 else 287 printk(KERN_ERR 288 "module %s: Relocation (type %lu) overflow vs %s\n", 289 me->name, r_type, strtab + sym->st_name); 290 return -ENOEXEC; 291 } 292 } 293 294 return 0; 295} 296 297int 298module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, 299 struct module *me) 300{ 301 return 0; 302} 303 304void 305module_arch_cleanup(struct module *mod) 306{ 307} 308