1 /* $NetBSD: mdreloc.c,v 1.34 2010/08/06 16:33:17 joerg Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.34 2010/08/06 16:33:17 joerg Exp $"); 6 #endif /* not lint */ 7 8 #include <sys/types.h> 9 #include <string.h> 10 11 #include "debug.h" 12 #include "rtld.h" 13 14 void _rtld_bind_start(void); 15 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 16 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 17 18 void 19 _rtld_setup_pltgot(const Obj_Entry *obj) 20 { 21 obj->pltgot[1] = (Elf_Addr) obj; 22 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 23 } 24 25 void 26 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 27 { 28 const Elf_Rel *rel = 0, *rellim; 29 Elf_Addr relsz = 0; 30 Elf_Addr *where; 31 32 for (; dynp->d_tag != DT_NULL; dynp++) { 33 switch (dynp->d_tag) { 34 case DT_REL: 35 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); 36 break; 37 case DT_RELSZ: 38 relsz = dynp->d_un.d_val; 39 break; 40 } 41 } 42 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); 43 for (; rel < rellim; rel++) { 44 where = (Elf_Addr *)(relocbase + rel->r_offset); 45 *where += (Elf_Addr)relocbase; 46 } 47 } 48 49 /* 50 * It is possible for the compiler to emit relocations for unaligned data. 51 * We handle this situation with these inlines. 52 */ 53 #define RELOC_ALIGNED_P(x) \ 54 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 55 56 static inline Elf_Addr 57 load_ptr(void *where) 58 { 59 Elf_Addr res; 60 61 memcpy(&res, where, sizeof(res)); 62 63 return (res); 64 } 65 66 static inline void 67 store_ptr(void *where, Elf_Addr val) 68 { 69 70 memcpy(where, &val, sizeof(val)); 71 } 72 73 int 74 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 75 { 76 const Elf_Rel *rel; 77 78 for (rel = obj->rel; rel < obj->rellim; rel++) { 79 Elf_Addr *where; 80 const Elf_Sym *def; 81 const Obj_Entry *defobj; 82 Elf_Addr tmp; 83 unsigned long symnum; 84 85 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 86 symnum = ELF_R_SYM(rel->r_info); 87 88 switch (ELF_R_TYPE(rel->r_info)) { 89 case R_TYPE(NONE): 90 break; 91 92 #if 1 /* XXX should not occur */ 93 case R_TYPE(PC24): { /* word32 S - P + A */ 94 Elf32_Sword addend; 95 96 /* 97 * Extract addend and sign-extend if needed. 98 */ 99 addend = *where; 100 if (addend & 0x00800000) 101 addend |= 0xff000000; 102 103 def = _rtld_find_symdef(symnum, obj, &defobj, false); 104 if (def == NULL) 105 return -1; 106 tmp = (Elf_Addr)obj->relocbase + def->st_value 107 - (Elf_Addr)where + (addend << 2); 108 if ((tmp & 0xfe000000) != 0xfe000000 && 109 (tmp & 0xfe000000) != 0) { 110 _rtld_error( 111 "%s: R_ARM_PC24 relocation @ %p to %s failed " 112 "(displacement %ld (%#lx) out of range)", 113 obj->path, where, 114 obj->strtab + obj->symtab[symnum].st_name, 115 (long) tmp, (long) tmp); 116 return -1; 117 } 118 tmp >>= 2; 119 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 120 rdbg(("PC24 %s in %s --> %p @ %p in %s", 121 obj->strtab + obj->symtab[symnum].st_name, 122 obj->path, (void *)*where, where, defobj->path)); 123 break; 124 } 125 #endif 126 127 case R_TYPE(ABS32): /* word32 B + S + A */ 128 case R_TYPE(GLOB_DAT): /* word32 B + S */ 129 def = _rtld_find_symdef(symnum, obj, &defobj, false); 130 if (def == NULL) 131 return -1; 132 if (__predict_true(RELOC_ALIGNED_P(where))) { 133 tmp = *where + (Elf_Addr)defobj->relocbase + 134 def->st_value; 135 /* Set the Thumb bit, if needed. */ 136 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 137 tmp |= 1; 138 *where = tmp; 139 } else { 140 tmp = load_ptr(where) + 141 (Elf_Addr)defobj->relocbase + 142 def->st_value; 143 /* Set the Thumb bit, if needed. */ 144 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 145 tmp |= 1; 146 store_ptr(where, tmp); 147 } 148 rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s", 149 obj->strtab + obj->symtab[symnum].st_name, 150 obj->path, (void *)tmp, where, defobj->path)); 151 break; 152 153 case R_TYPE(RELATIVE): /* word32 B + A */ 154 if (__predict_true(RELOC_ALIGNED_P(where))) { 155 tmp = *where + (Elf_Addr)obj->relocbase; 156 *where = tmp; 157 } else { 158 tmp = load_ptr(where) + 159 (Elf_Addr)obj->relocbase; 160 store_ptr(where, tmp); 161 } 162 rdbg(("RELATIVE in %s --> %p", obj->path, 163 (void *)tmp)); 164 break; 165 166 case R_TYPE(COPY): 167 /* 168 * These are deferred until all other relocations have 169 * been done. All we do here is make sure that the 170 * COPY relocation is not in a shared library. They 171 * are allowed only in executable files. 172 */ 173 if (obj->isdynamic) { 174 _rtld_error( 175 "%s: Unexpected R_COPY relocation in shared library", 176 obj->path); 177 return -1; 178 } 179 rdbg(("COPY (avoid in main)")); 180 break; 181 182 default: 183 rdbg(("sym = %lu, type = %lu, offset = %p, " 184 "contents = %p, symbol = %s", 185 symnum, (u_long)ELF_R_TYPE(rel->r_info), 186 (void *)rel->r_offset, (void *)load_ptr(where), 187 obj->strtab + obj->symtab[symnum].st_name)); 188 _rtld_error("%s: Unsupported relocation type %ld " 189 "in non-PLT relocations", 190 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 191 return -1; 192 } 193 } 194 return 0; 195 } 196 197 int 198 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 199 { 200 const Elf_Rel *rel; 201 202 if (!obj->relocbase) 203 return 0; 204 205 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 206 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 207 208 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 209 210 /* Just relocate the GOT slots pointing into the PLT */ 211 *where += (Elf_Addr)obj->relocbase; 212 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 213 } 214 215 return 0; 216 } 217 218 static int 219 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, 220 Elf_Addr *tp) 221 { 222 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 223 Elf_Addr new_value; 224 const Elf_Sym *def; 225 const Obj_Entry *defobj; 226 unsigned long info = rel->r_info; 227 228 assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT)); 229 230 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 231 if (__predict_false(def == NULL)) 232 return -1; 233 if (__predict_false(def == &_rtld_sym_zero)) 234 return 0; 235 236 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 237 /* Set the Thumb bit, if needed. */ 238 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 239 new_value |= 1; 240 rdbg(("bind now/fixup in %s --> old=%p new=%p", 241 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 242 if (*where != new_value) 243 *where = new_value; 244 if (tp) 245 *tp = new_value; 246 247 return 0; 248 } 249 250 caddr_t 251 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 252 { 253 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel + reloff); 254 Elf_Addr new_value = 0; /* XXX gcc */ 255 int err; 256 257 err = _rtld_relocate_plt_object(obj, rel, &new_value); 258 if (err) 259 _rtld_die(); 260 261 return (caddr_t)new_value; 262 } 263 int 264 _rtld_relocate_plt_objects(const Obj_Entry *obj) 265 { 266 const Elf_Rel *rel; 267 int err = 0; 268 269 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 270 err = _rtld_relocate_plt_object(obj, rel, NULL); 271 if (err) 272 break; 273 } 274 275 return err; 276 } 277