1 /* $NetBSD: crt0-common.c,v 1.23 2018/12/28 20:12:35 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1998 Christos Zoulas 5 * Copyright (c) 1995 Christopher G. Demetriou 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed for the 19 * NetBSD Project. See http://www.NetBSD.org/ for 20 * information about NetBSD. 21 * 4. The name of the author may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 * 35 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>> 36 */ 37 38 #include <sys/cdefs.h> 39 __RCSID("$NetBSD: crt0-common.c,v 1.23 2018/12/28 20:12:35 christos Exp $"); 40 41 #include <sys/types.h> 42 #include <sys/exec.h> 43 #include <sys/exec_elf.h> 44 #include <sys/syscall.h> 45 #include <machine/profile.h> 46 #include <stdlib.h> 47 #include <unistd.h> 48 49 extern int main(int, char **, char **); 50 51 typedef void (*fptr_t)(void); 52 #ifndef HAVE_INITFINI_ARRAY 53 extern void _init(void); 54 extern void _fini(void); 55 #endif 56 extern void _libc_init(void); 57 58 /* 59 * Arrange for _DYNAMIC to be weak and undefined (and therefore to show up 60 * as being at address zero, unless something else defines it). That way, 61 * if we happen to be compiling without -static but with without any 62 * shared libs present, things will still work. 63 */ 64 65 __weakref_visible int rtld_DYNAMIC __weak_reference(_DYNAMIC); 66 67 #ifdef MCRT0 68 extern void monstartup(u_long, u_long); 69 extern void _mcleanup(void); 70 extern unsigned char __etext, __eprol; 71 #endif /* MCRT0 */ 72 73 char **environ; 74 struct ps_strings *__ps_strings = 0; 75 76 static char empty_string[] = ""; 77 char *__progname = empty_string; 78 79 __dead __dso_hidden void ___start(void (*)(void), struct ps_strings *); 80 81 #define write(fd, s, n) __syscall(SYS_write, (fd), (s), (n)) 82 83 #define _FATAL(str) \ 84 do { \ 85 write(2, str, sizeof(str)-1); \ 86 _exit(1); \ 87 } while (0) 88 89 /* 90 * If we are using INIT_ARRAY/FINI_ARRAY and we are linked statically, 91 * we have to process these instead of relying on RTLD to do it for us. 92 * 93 * Since we don't need .init or .fini sections, just code them in C 94 * to make life easier. 95 */ 96 extern const fptr_t __preinit_array_start[] __dso_hidden; 97 extern const fptr_t __preinit_array_end[] __dso_hidden __weak; 98 extern const fptr_t __init_array_start[] __dso_hidden; 99 extern const fptr_t __init_array_end[] __dso_hidden __weak; 100 extern const fptr_t __fini_array_start[] __dso_hidden; 101 extern const fptr_t __fini_array_end[] __dso_hidden __weak; 102 103 static inline void 104 _preinit(void) 105 { 106 for (const fptr_t *f = __preinit_array_start; f < __preinit_array_end; f++) { 107 (*f)(); 108 } 109 } 110 111 static inline void 112 _initarray(void) 113 { 114 for (const fptr_t *f = __init_array_start; f < __init_array_end; f++) { 115 (*f)(); 116 } 117 } 118 119 static void 120 _finiarray(void) 121 { 122 for (const fptr_t *f = __fini_array_start; f < __fini_array_end; f++) { 123 (*f)(); 124 } 125 } 126 127 #if defined(__x86_64__) || defined(__powerpc__) || defined(__sparc__) 128 #define HAS_IPLTA 129 static void fix_iplta(void) __noinline; 130 #elif defined(__i386__) || defined(__arm__) 131 #define HAS_IPLT 132 static void fix_iplt(void) __noinline; 133 #endif 134 135 136 #ifdef HAS_IPLTA 137 #include <stdio.h> 138 extern const Elf_Rela __rela_iplt_start[] __dso_hidden __weak; 139 extern const Elf_Rela __rela_iplt_end[] __dso_hidden __weak; 140 #ifdef __sparc__ 141 #define IFUNC_RELOCATION R_TYPE(JMP_IREL) 142 #include <machine/elf_support.h> 143 #define write_plt(where, value) sparc_write_branch((void *)where, (void *)value) 144 #else 145 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 146 #define write_plt(where, value) *where = value 147 #endif 148 149 static void 150 fix_iplta(void) 151 { 152 const Elf_Rela *rela, *relalim; 153 uintptr_t relocbase = 0; 154 Elf_Addr *where, target; 155 156 rela = __rela_iplt_start; 157 relalim = __rela_iplt_end; 158 for (; rela < relalim; ++rela) { 159 if (ELF_R_TYPE(rela->r_info) != IFUNC_RELOCATION) 160 abort(); 161 where = (Elf_Addr *)(relocbase + rela->r_offset); 162 target = (Elf_Addr)(relocbase + rela->r_addend); 163 target = ((Elf_Addr(*)(void))target)(); 164 write_plt(where, target); 165 } 166 } 167 #endif 168 #ifdef HAS_IPLT 169 extern const Elf_Rel __rel_iplt_start[] __dso_hidden __weak; 170 extern const Elf_Rel __rel_iplt_end[] __dso_hidden __weak; 171 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 172 173 static void 174 fix_iplt(void) 175 { 176 const Elf_Rel *rel, *rellim; 177 uintptr_t relocbase = 0; 178 Elf_Addr *where, target; 179 180 rel = __rel_iplt_start; 181 rellim = __rel_iplt_end; 182 for (; rel < rellim; ++rel) { 183 if (ELF_R_TYPE(rel->r_info) != IFUNC_RELOCATION) 184 abort(); 185 where = (Elf_Addr *)(relocbase + rel->r_offset); 186 target = ((Elf_Addr(*)(void))*where)(); 187 *where = target; 188 } 189 } 190 #endif 191 192 #if defined(__x86_64__) || defined(__i386__) 193 # define HAS_RELOCATE_SELF 194 # if defined(__x86_64__) 195 # define RELA 196 # define REL_TAG DT_RELA 197 # define RELSZ_TAG DT_RELASZ 198 # define REL_TYPE Elf_Rela 199 # else 200 # define REL_TAG DT_REL 201 # define RELSZ_TAG DT_RELSZ 202 # define REL_TYPE Elf_Rel 203 # endif 204 205 #include <elf.h> 206 207 static void relocate_self(struct ps_strings *) __noinline; 208 209 static void 210 relocate_self(struct ps_strings *ps_strings) 211 { 212 AuxInfo *aux = (AuxInfo *)(ps_strings->ps_argvstr + ps_strings->ps_nargvstr + 213 ps_strings->ps_nenvstr + 2); 214 uintptr_t relocbase = (uintptr_t)~0U; 215 const Elf_Phdr *phdr = NULL; 216 Elf_Half phnum = (Elf_Half)~0; 217 218 for (; aux->a_type != AT_NULL; ++aux) { 219 switch (aux->a_type) { 220 case AT_BASE: 221 if (aux->a_v) 222 return; 223 break; 224 case AT_PHDR: 225 phdr = (void *)aux->a_v; 226 break; 227 case AT_PHNUM: 228 phnum = (Elf_Half)aux->a_v; 229 break; 230 } 231 } 232 233 if (phdr == NULL || phnum == (Elf_Half)~0) 234 return; 235 236 const Elf_Phdr *phlimit = phdr + phnum, *dynphdr = NULL; 237 238 for (; phdr < phlimit; ++phdr) { 239 if (phdr->p_type == PT_DYNAMIC) 240 dynphdr = phdr; 241 if (phdr->p_type == PT_PHDR) 242 relocbase = (uintptr_t)phdr - phdr->p_vaddr; 243 } 244 if (dynphdr == NULL || relocbase == (uintptr_t)~0U) 245 return; 246 247 Elf_Dyn *dynp = (Elf_Dyn *)((uint8_t *)dynphdr->p_vaddr + relocbase); 248 249 const REL_TYPE *relocs = 0, *relocslim; 250 Elf_Addr relocssz = 0; 251 252 for (; dynp->d_tag != DT_NULL; dynp++) { 253 switch (dynp->d_tag) { 254 case REL_TAG: 255 relocs = 256 (const REL_TYPE *)(relocbase + dynp->d_un.d_ptr); 257 break; 258 case RELSZ_TAG: 259 relocssz = dynp->d_un.d_val; 260 break; 261 } 262 } 263 relocslim = (const REL_TYPE *)((const uint8_t *)relocs + relocssz); 264 for (; relocs < relocslim; ++relocs) { 265 Elf_Addr *where; 266 267 where = (Elf_Addr *)(relocbase + relocs->r_offset); 268 269 switch (ELF_R_TYPE(relocs->r_info)) { 270 case R_TYPE(RELATIVE): /* word64 B + A */ 271 #ifdef RELA 272 *where = (Elf_Addr)(relocbase + relocs->r_addend); 273 #else 274 *where += (Elf_Addr)relocbase; 275 #endif 276 break; 277 #ifdef IFUNC_RELOCATION 278 case IFUNC_RELOCATION: 279 break; 280 #endif 281 default: 282 abort(); 283 } 284 } 285 } 286 #endif 287 288 void 289 ___start(void (*cleanup)(void), /* from shared loader */ 290 struct ps_strings *ps_strings) 291 { 292 #if defined(HAS_RELOCATE_SELF) 293 relocate_self(ps_strings); 294 #endif 295 296 if (ps_strings == NULL) 297 _FATAL("ps_strings missing\n"); 298 __ps_strings = ps_strings; 299 300 environ = ps_strings->ps_envstr; 301 302 if (ps_strings->ps_argvstr[0] != NULL) { 303 char *c; 304 __progname = ps_strings->ps_argvstr[0]; 305 for (c = ps_strings->ps_argvstr[0]; *c; ++c) { 306 if (*c == '/') 307 __progname = c + 1; 308 } 309 } else { 310 __progname = empty_string; 311 } 312 313 if (cleanup != NULL) 314 atexit(cleanup); 315 316 _libc_init(); 317 318 if (&rtld_DYNAMIC == NULL) { 319 #ifdef HAS_IPLTA 320 fix_iplta(); 321 #endif 322 #ifdef HAS_IPLT 323 fix_iplt(); 324 #endif 325 } 326 327 _preinit(); 328 329 #ifdef MCRT0 330 atexit(_mcleanup); 331 monstartup((u_long)&__eprol, (u_long)&__etext); 332 #endif 333 334 atexit(_finiarray); 335 _initarray(); 336 337 #ifndef HAVE_INITFINI_ARRAY 338 atexit(_fini); 339 _init(); 340 #endif 341 342 exit(main(ps_strings->ps_nargvstr, ps_strings->ps_argvstr, environ)); 343 } 344