mdreloc.c revision 1.23
1 /* $NetBSD: mdreloc.c,v 1.23 2003/07/26 15:04:38 mrg Exp $ */ 2 3 #include <sys/types.h> 4 #include <sys/stat.h> 5 6 #include <string.h> 7 8 #include "debug.h" 9 #include "rtld.h" 10 11 void _rtld_bind_start(void); 12 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 13 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 14 15 void 16 _rtld_setup_pltgot(const Obj_Entry *obj) 17 { 18 obj->pltgot[1] = (Elf_Addr) obj; 19 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 20 } 21 22 void 23 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 24 { 25 const Elf_Rel *rel = 0, *rellim; 26 Elf_Addr relsz = 0; 27 Elf_Addr *where; 28 29 for (; dynp->d_tag != DT_NULL; dynp++) { 30 switch (dynp->d_tag) { 31 case DT_REL: 32 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); 33 break; 34 case DT_RELSZ: 35 relsz = dynp->d_un.d_val; 36 break; 37 } 38 } 39 rellim = (const Elf_Rel *)((caddr_t)rel + relsz); 40 for (; rel < rellim; rel++) { 41 where = (Elf_Addr *)(relocbase + rel->r_offset); 42 *where += (Elf_Addr)relocbase; 43 } 44 } 45 46 /* 47 * It is possible for the compiler to emit relocations for unaligned data. 48 * We handle this situation with these inlines. 49 */ 50 #define RELOC_ALIGNED_P(x) \ 51 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 52 53 static __inline Elf_Addr 54 load_ptr(void *where) 55 { 56 Elf_Addr res; 57 58 memcpy(&res, where, sizeof(res)); 59 60 return (res); 61 } 62 63 static __inline void 64 store_ptr(void *where, Elf_Addr val) 65 { 66 67 memcpy(where, &val, sizeof(val)); 68 } 69 70 int 71 _rtld_relocate_nonplt_objects(const Obj_Entry *obj) 72 { 73 const Elf_Rel *rel; 74 75 for (rel = obj->rel; rel < obj->rellim; rel++) { 76 Elf_Addr *where; 77 const Elf_Sym *def; 78 const Obj_Entry *defobj; 79 Elf_Addr tmp; 80 unsigned long symnum; 81 82 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 83 symnum = ELF_R_SYM(rel->r_info); 84 85 switch (ELF_R_TYPE(rel->r_info)) { 86 case R_TYPE(NONE): 87 break; 88 89 #if 1 /* XXX should not occur */ 90 case R_TYPE(PC24): { /* word32 S - P + A */ 91 Elf32_Sword addend; 92 93 /* 94 * Extract addend and sign-extend if needed. 95 */ 96 addend = *where; 97 if (addend & 0x00800000) 98 addend |= 0xff000000; 99 100 def = _rtld_find_symdef(symnum, obj, &defobj, false); 101 if (def == NULL) 102 return -1; 103 tmp = (Elf_Addr)obj->relocbase + def->st_value 104 - (Elf_Addr)where + (addend << 2); 105 if ((tmp & 0xfe000000) != 0xfe000000 && 106 (tmp & 0xfe000000) != 0) { 107 _rtld_error( 108 "%s: R_ARM_PC24 relocation @ %p to %s failed " 109 "(displacement %ld (%#lx) out of range)", 110 obj->path, where, 111 obj->strtab + obj->symtab[symnum].st_name, 112 (long) tmp, (long) tmp); 113 return -1; 114 } 115 tmp >>= 2; 116 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 117 rdbg(("PC24 %s in %s --> %p @ %p in %s", 118 obj->strtab + obj->symtab[symnum].st_name, 119 obj->path, (void *)*where, where, defobj->path)); 120 break; 121 } 122 #endif 123 124 case R_TYPE(ABS32): /* word32 B + S + A */ 125 case R_TYPE(GLOB_DAT): /* word32 B + S */ 126 def = _rtld_find_symdef(symnum, obj, &defobj, false); 127 if (def == NULL) 128 return -1; 129 if (__predict_true(RELOC_ALIGNED_P(where))) { 130 tmp = *where + (Elf_Addr)defobj->relocbase + 131 def->st_value; 132 *where = tmp; 133 } else { 134 tmp = load_ptr(where) + 135 (Elf_Addr)defobj->relocbase + 136 def->st_value; 137 store_ptr(where, tmp); 138 } 139 rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s", 140 obj->strtab + obj->symtab[symnum].st_name, 141 obj->path, (void *)tmp, where, defobj->path)); 142 break; 143 144 case R_TYPE(RELATIVE): /* word32 B + A */ 145 if (__predict_true(RELOC_ALIGNED_P(where))) { 146 tmp = *where + (Elf_Addr)obj->relocbase; 147 *where = tmp; 148 } else { 149 tmp = load_ptr(where) + 150 (Elf_Addr)obj->relocbase; 151 store_ptr(where, tmp); 152 } 153 rdbg(("RELATIVE in %s --> %p", obj->path, 154 (void *)tmp)); 155 break; 156 157 case R_TYPE(COPY): 158 /* 159 * These are deferred until all other relocations have 160 * been done. All we do here is make sure that the 161 * COPY relocation is not in a shared library. They 162 * are allowed only in executable files. 163 */ 164 if (obj->isdynamic) { 165 _rtld_error( 166 "%s: Unexpected R_COPY relocation in shared library", 167 obj->path); 168 return -1; 169 } 170 rdbg(("COPY (avoid in main)")); 171 break; 172 173 default: 174 rdbg(("sym = %lu, type = %lu, offset = %p, " 175 "contents = %p, symbol = %s", 176 symnum, (u_long)ELF_R_TYPE(rel->r_info), 177 (void *)rel->r_offset, (void *)load_ptr(where), 178 obj->strtab + obj->symtab[symnum].st_name)); 179 _rtld_error("%s: Unsupported relocation type %ld " 180 "in non-PLT relocations\n", 181 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 182 return -1; 183 } 184 } 185 return 0; 186 } 187 188 int 189 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 190 { 191 const Elf_Rel *rel; 192 193 if (!obj->relocbase) 194 return 0; 195 196 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 197 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 198 199 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 200 201 /* Just relocate the GOT slots pointing into the PLT */ 202 *where += (Elf_Addr)obj->relocbase; 203 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 204 } 205 206 return 0; 207 } 208 209 caddr_t 210 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 211 { 212 const Elf_Rel *rel = (const Elf_Rel *)((caddr_t)obj->pltrel + reloff); 213 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 214 Elf_Addr new_value; 215 const Elf_Sym *def; 216 const Obj_Entry *defobj; 217 218 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 219 220 def = _rtld_find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true); 221 if (def == NULL) 222 _rtld_die(); 223 224 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 225 rdbg(("bind now/fixup in %s --> old=%p new=%p", 226 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 227 if (*where != new_value) 228 *where = new_value; 229 230 return (caddr_t)new_value; 231 } 232 233 int 234 _rtld_relocate_plt_objects(const Obj_Entry *obj) 235 { 236 const Elf_Rel *rel; 237 238 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 239 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 240 Elf_Addr target; 241 const Elf_Sym *def; 242 const Obj_Entry *defobj; 243 244 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 245 246 def = _rtld_find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, 247 true); 248 if (def == NULL) 249 return -1; 250 target = (Elf_Addr)(defobj->relocbase + def->st_value); 251 rdbg(("bind now/fixup in %s --> old=%p new=%p", 252 defobj->strtab + def->st_name, (void *)*where, 253 (void *)target)); 254 if (*where != target) 255 *where = target; 256 } 257 return 0; 258 } 259
Indexes created Mon Sep 29 21:09:56 GMT 2025