mdreloc.c revision 1.22
1 /* $NetBSD: mdreloc.c,v 1.22 2003/07/24 10:12:27 skrll Exp $ */ 2 3 #include <sys/types.h> 4 #include <sys/stat.h> 5 6 #include "debug.h" 7 #include "rtld.h" 8 9 void _rtld_bind_start(void); 10 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 11 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 12 13 void 14 _rtld_setup_pltgot(const Obj_Entry *obj) 15 { 16 obj->pltgot[1] = (Elf_Addr) obj; 17 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 18 } 19 20 void 21 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 22 { 23 const Elf_Rel *rel = 0, *rellim; 24 Elf_Addr relsz = 0; 25 Elf_Addr *where; 26 27 for (; dynp->d_tag != DT_NULL; dynp++) { 28 switch (dynp->d_tag) { 29 case DT_REL: 30 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); 31 break; 32 case DT_RELSZ: 33 relsz = dynp->d_un.d_val; 34 break; 35 } 36 } 37 rellim = (const Elf_Rel *)((caddr_t)rel + relsz); 38 for (; rel < rellim; rel++) { 39 where = (Elf_Addr *)(relocbase + rel->r_offset); 40 *where += (Elf_Addr)relocbase; 41 } 42 } 43 44 /* 45 * It is possible for the compiler to emit relocations for unaligned data. 46 * We handle this situation with these inlines. 47 */ 48 #define RELOC_ALIGNED_P(x) \ 49 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 50 51 static __inline Elf_Addr 52 load_ptr(void *where) 53 { 54 Elf_Addr res; 55 56 memcpy(&res, where, sizeof(res)); 57 58 return (res); 59 } 60 61 static __inline void 62 store_ptr(void *where, Elf_Addr val) 63 { 64 65 memcpy(where, &val, sizeof(val)); 66 } 67 68 int 69 _rtld_relocate_nonplt_objects(const Obj_Entry *obj) 70 { 71 const Elf_Rel *rel; 72 73 for (rel = obj->rel; rel < obj->rellim; rel++) { 74 Elf_Addr *where; 75 const Elf_Sym *def; 76 const Obj_Entry *defobj; 77 Elf_Addr tmp; 78 unsigned long symnum; 79 80 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 81 symnum = ELF_R_SYM(rel->r_info); 82 83 switch (ELF_R_TYPE(rel->r_info)) { 84 case R_TYPE(NONE): 85 break; 86 87 #if 1 /* XXX should not occur */ 88 case R_TYPE(PC24): { /* word32 S - P + A */ 89 Elf32_Sword addend; 90 91 /* 92 * Extract addend and sign-extend if needed. 93 */ 94 addend = *where; 95 if (addend & 0x00800000) 96 addend |= 0xff000000; 97 98 def = _rtld_find_symdef(symnum, obj, &defobj, false); 99 if (def == NULL) 100 return -1; 101 tmp = (Elf_Addr)obj->relocbase + def->st_value 102 - (Elf_Addr)where + (addend << 2); 103 if ((tmp & 0xfe000000) != 0xfe000000 && 104 (tmp & 0xfe000000) != 0) { 105 _rtld_error( 106 "%s: R_ARM_PC24 relocation @ %p to %s failed " 107 "(displacement %ld (%#lx) out of range)", 108 obj->path, where, 109 obj->strtab + obj->symtab[symnum].st_name, 110 (long) tmp, (long) tmp); 111 return -1; 112 } 113 tmp >>= 2; 114 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 115 rdbg(("PC24 %s in %s --> %p @ %p in %s", 116 obj->strtab + obj->symtab[symnum].st_name, 117 obj->path, (void *)*where, where, defobj->path)); 118 break; 119 } 120 #endif 121 122 case R_TYPE(ABS32): /* word32 B + S + A */ 123 case R_TYPE(GLOB_DAT): /* word32 B + S */ 124 def = _rtld_find_symdef(symnum, obj, &defobj, false); 125 if (def == NULL) 126 return -1; 127 if (__predict_true(RELOC_ALIGNED_P(where))) { 128 tmp = *where + (Elf_Addr)defobj->relocbase + 129 def->st_value; 130 *where = tmp; 131 } else { 132 tmp = load_ptr(where) + 133 (Elf_Addr)defobj->relocbase + 134 def->st_value; 135 store_ptr(where, tmp); 136 } 137 rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s", 138 obj->strtab + obj->symtab[symnum].st_name, 139 obj->path, (void *)tmp, where, defobj->path)); 140 break; 141 142 case R_TYPE(RELATIVE): /* word32 B + A */ 143 if (__predict_true(RELOC_ALIGNED_P(where))) { 144 tmp = *where + (Elf_Addr)obj->relocbase; 145 *where = tmp; 146 } else { 147 tmp = load_ptr(where) + 148 (Elf_Addr)obj->relocbase; 149 store_ptr(where, tmp); 150 } 151 rdbg(("RELATIVE in %s --> %p", obj->path, 152 (void *)tmp)); 153 break; 154 155 case R_TYPE(COPY): 156 /* 157 * These are deferred until all other relocations have 158 * been done. All we do here is make sure that the 159 * COPY relocation is not in a shared library. They 160 * are allowed only in executable files. 161 */ 162 if (obj->isdynamic) { 163 _rtld_error( 164 "%s: Unexpected R_COPY relocation in shared library", 165 obj->path); 166 return -1; 167 } 168 rdbg(("COPY (avoid in main)")); 169 break; 170 171 default: 172 rdbg(("sym = %lu, type = %lu, offset = %p, " 173 "contents = %p, symbol = %s", 174 symnum, (u_long)ELF_R_TYPE(rel->r_info), 175 (void *)rel->r_offset, (void *)load_ptr(where), 176 obj->strtab + obj->symtab[symnum].st_name)); 177 _rtld_error("%s: Unsupported relocation type %ld " 178 "in non-PLT relocations\n", 179 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 180 return -1; 181 } 182 } 183 return 0; 184 } 185 186 int 187 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 188 { 189 const Elf_Rel *rel; 190 191 if (!obj->relocbase) 192 return 0; 193 194 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 195 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 196 197 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 198 199 /* Just relocate the GOT slots pointing into the PLT */ 200 *where += (Elf_Addr)obj->relocbase; 201 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 202 } 203 204 return 0; 205 } 206 207 caddr_t 208 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 209 { 210 const Elf_Rel *rel = (const Elf_Rel *)((caddr_t)obj->pltrel + reloff); 211 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 212 Elf_Addr new_value; 213 const Elf_Sym *def; 214 const Obj_Entry *defobj; 215 216 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 217 218 def = _rtld_find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true); 219 if (def == NULL) 220 _rtld_die(); 221 222 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 223 rdbg(("bind now/fixup in %s --> old=%p new=%p", 224 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 225 if (*where != new_value) 226 *where = new_value; 227 228 return (caddr_t)new_value; 229 } 230 231 int 232 _rtld_relocate_plt_objects(const Obj_Entry *obj) 233 { 234 const Elf_Rel *rel; 235 236 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 237 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 238 Elf_Addr target; 239 const Elf_Sym *def; 240 const Obj_Entry *defobj; 241 242 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 243 244 def = _rtld_find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, 245 true); 246 if (def == NULL) 247 return -1; 248 target = (Elf_Addr)(defobj->relocbase + def->st_value); 249 rdbg(("bind now/fixup in %s --> old=%p new=%p", 250 defobj->strtab + def->st_name, (void *)*where, 251 (void *)target)); 252 if (*where != target) 253 *where = target; 254 } 255 return 0; 256 } 257
Indexes created Mon Sep 29 21:09:56 GMT 2025