1 /* $NetBSD: crt0-common.c,v 1.28 2024/01/19 19:22:17 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 1.28 2024/01/19 19:22:17 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 #include "csu-common.h" 50 51 extern int main(int, char **, char **); 52 53 typedef void (*fptr_t)(void); 54 #ifndef HAVE_INITFINI_ARRAY 55 extern void _init(void); 56 extern void _fini(void); 57 #endif 58 59 /* 60 * Arrange for _DYNAMIC to be weak and undefined (and therefore to show up 61 * as being at address zero, unless something else defines it). That way, 62 * if we happen to be compiling without -static but with without any 63 * shared libs present, things will still work. 64 */ 65 66 __weakref_visible int rtld_DYNAMIC __weak_reference(_DYNAMIC); 67 68 #ifdef MCRT0 69 extern void monstartup(u_long, u_long); 70 extern void _mcleanup(void); 71 extern unsigned char __etext, __eprol; 72 #endif /* MCRT0 */ 73 74 static char empty_string[] = ""; 75 76 char **environ __common; 77 struct ps_strings *__ps_strings __common = 0; 78 char *__progname __common = empty_string; 79 80 __dead __dso_hidden void ___start(void (*)(void), struct ps_strings *); 81 82 #define write(fd, s, n) __syscall(SYS_write, (fd), (s), (n)) 83 84 #define _FATAL(str) \ 85 do { \ 86 write(2, str, sizeof(str)-1); \ 87 _exit(1); \ 88 } while (0) 89 90 /* 91 * If we are using INIT_ARRAY/FINI_ARRAY and we are linked statically, 92 * we have to process these instead of relying on RTLD to do it for us. 93 * 94 * Since we don't need .init or .fini sections, just code them in C 95 * to make life easier. 96 */ 97 extern const fptr_t __preinit_array_start[] __dso_hidden; 98 extern const fptr_t __preinit_array_end[] __dso_hidden __weak; 99 extern const fptr_t __init_array_start[] __dso_hidden; 100 extern const fptr_t __init_array_end[] __dso_hidden __weak; 101 extern const fptr_t __fini_array_start[] __dso_hidden; 102 extern const fptr_t __fini_array_end[] __dso_hidden __weak; 103 104 static inline void 105 _preinit(void) 106 { 107 for (const fptr_t *f = __preinit_array_start; f < __preinit_array_end; f++) { 108 (*f)(); 109 } 110 } 111 112 static inline void 113 _initarray(void) 114 { 115 for (const fptr_t *f = __init_array_start; f < __init_array_end; f++) { 116 (*f)(); 117 } 118 } 119 120 static void 121 _finiarray(void) 122 { 123 for (const fptr_t *f = __fini_array_start; f < __fini_array_end; f++) { 124 (*f)(); 125 } 126 } 127 128 #if \ 129 defined(__aarch64__) || \ 130 defined(__powerpc__) || \ 131 defined(__sparc__) || \ 132 defined(__x86_64__) 133 #define HAS_IPLTA 134 static void fix_iplta(void) __noinline; 135 #elif \ 136 defined(__arm__) || \ 137 defined(__i386__) 138 #define HAS_IPLT 139 static void fix_iplt(void) __noinline; 140 #endif 141 142 143 #ifdef HAS_IPLTA 144 #include <stdio.h> 145 extern const Elf_Rela __rela_iplt_start[] __dso_hidden __weak; 146 extern const Elf_Rela __rela_iplt_end[] __dso_hidden __weak; 147 #ifdef __sparc__ 148 #define IFUNC_RELOCATION R_TYPE(JMP_IREL) 149 #include <machine/elf_support.h> 150 #define write_plt(where, value) sparc_write_branch((void *)where, (void *)value) 151 #else 152 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 153 #define write_plt(where, value) *where = value 154 #endif 155 156 static void 157 fix_iplta(void) 158 { 159 const Elf_Rela *rela, *relalim; 160 uintptr_t relocbase = 0; 161 Elf_Addr *where, target; 162 163 rela = __rela_iplt_start; 164 relalim = __rela_iplt_end; 165 for (; rela < relalim; ++rela) { 166 if (ELF_R_TYPE(rela->r_info) != IFUNC_RELOCATION) 167 abort(); 168 where = (Elf_Addr *)(relocbase + rela->r_offset); 169 target = (Elf_Addr)(relocbase + rela->r_addend); 170 target = ((Elf_Addr(*)(void))target)(); 171 write_plt(where, target); 172 } 173 } 174 #endif 175 #ifdef HAS_IPLT 176 extern const Elf_Rel __rel_iplt_start[] __dso_hidden __weak; 177 extern const Elf_Rel __rel_iplt_end[] __dso_hidden __weak; 178 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 179 180 static void 181 fix_iplt(void) 182 { 183 const Elf_Rel *rel, *rellim; 184 uintptr_t relocbase = 0; 185 Elf_Addr *where, target; 186 187 rel = __rel_iplt_start; 188 rellim = __rel_iplt_end; 189 for (; rel < rellim; ++rel) { 190 if (ELF_R_TYPE(rel->r_info) != IFUNC_RELOCATION) 191 abort(); 192 where = (Elf_Addr *)(relocbase + rel->r_offset); 193 target = ((Elf_Addr(*)(void))*where)(); 194 *where = target; 195 } 196 } 197 #endif 198 199 #if defined(__x86_64__) || defined(__i386__) 200 # define HAS_RELOCATE_SELF 201 # if defined(__x86_64__) 202 # define RELA 203 # define REL_TAG DT_RELA 204 # define RELSZ_TAG DT_RELASZ 205 # define REL_TYPE Elf_Rela 206 # else 207 # define REL_TAG DT_REL 208 # define RELSZ_TAG DT_RELSZ 209 # define REL_TYPE Elf_Rel 210 # endif 211 212 #include <elf.h> 213 214 static void relocate_self(struct ps_strings *) __noinline; 215 216 static void 217 relocate_self(struct ps_strings *ps_strings) 218 { 219 AuxInfo *aux = (AuxInfo *)(ps_strings->ps_argvstr + ps_strings->ps_nargvstr + 220 ps_strings->ps_nenvstr + 2); 221 uintptr_t relocbase = (uintptr_t)~0U; 222 const Elf_Phdr *phdr = NULL; 223 Elf_Half phnum = (Elf_Half)~0; 224 225 for (; aux->a_type != AT_NULL; ++aux) { 226 switch (aux->a_type) { 227 case AT_BASE: 228 if (aux->a_v) 229 return; 230 break; 231 case AT_PHDR: 232 phdr = (void *)aux->a_v; 233 break; 234 case AT_PHNUM: 235 phnum = (Elf_Half)aux->a_v; 236 break; 237 } 238 } 239 240 if (phdr == NULL || phnum == (Elf_Half)~0) 241 return; 242 243 const Elf_Phdr *phlimit = phdr + phnum, *dynphdr = NULL; 244 245 for (; phdr < phlimit; ++phdr) { 246 if (phdr->p_type == PT_DYNAMIC) 247 dynphdr = phdr; 248 if (phdr->p_type == PT_PHDR) 249 relocbase = (uintptr_t)phdr - phdr->p_vaddr; 250 } 251 if (dynphdr == NULL || relocbase == (uintptr_t)~0U) 252 return; 253 254 Elf_Dyn *dynp = (Elf_Dyn *)((uint8_t *)dynphdr->p_vaddr + relocbase); 255 256 const REL_TYPE *relocs = 0, *relocslim; 257 Elf_Addr relocssz = 0; 258 259 for (; dynp->d_tag != DT_NULL; dynp++) { 260 switch (dynp->d_tag) { 261 case REL_TAG: 262 relocs = 263 (const REL_TYPE *)(relocbase + dynp->d_un.d_ptr); 264 break; 265 case RELSZ_TAG: 266 relocssz = dynp->d_un.d_val; 267 break; 268 } 269 } 270 relocslim = (const REL_TYPE *)((const uint8_t *)relocs + relocssz); 271 for (; relocs < relocslim; ++relocs) { 272 Elf_Addr *where; 273 274 where = (Elf_Addr *)(relocbase + relocs->r_offset); 275 276 switch (ELF_R_TYPE(relocs->r_info)) { 277 case R_TYPE(RELATIVE): /* word64 B + A */ 278 #ifdef RELA 279 *where = (Elf_Addr)(relocbase + relocs->r_addend); 280 #else 281 *where += (Elf_Addr)relocbase; 282 #endif 283 break; 284 #ifdef IFUNC_RELOCATION 285 case IFUNC_RELOCATION: 286 break; 287 #endif 288 default: 289 abort(); 290 } 291 } 292 } 293 #endif 294 295 void 296 ___start(void (*cleanup)(void), /* from shared loader */ 297 struct ps_strings *ps_strings) 298 { 299 #if defined(HAS_RELOCATE_SELF) 300 relocate_self(ps_strings); 301 #endif 302 303 if (ps_strings == NULL) 304 _FATAL("ps_strings missing\n"); 305 __ps_strings = ps_strings; 306 307 environ = ps_strings->ps_envstr; 308 309 if (ps_strings->ps_argvstr[0] != NULL) { 310 char *c; 311 __progname = ps_strings->ps_argvstr[0]; 312 for (c = ps_strings->ps_argvstr[0]; *c; ++c) { 313 if (*c == '/') 314 __progname = c + 1; 315 } 316 } else { 317 __progname = empty_string; 318 } 319 320 if (cleanup != NULL) 321 atexit(cleanup); 322 323 _libc_init(); 324 325 if (&rtld_DYNAMIC == NULL) { 326 #ifdef HAS_IPLTA 327 fix_iplta(); 328 #endif 329 #ifdef HAS_IPLT 330 fix_iplt(); 331 #endif 332 } 333 334 _preinit(); 335 336 #ifdef MCRT0 337 atexit(_mcleanup); 338 monstartup((u_long)&__eprol, (u_long)&__etext); 339 #endif 340 341 atexit(_finiarray); 342 _initarray(); 343 344 #ifndef HAVE_INITFINI_ARRAY 345 atexit(_fini); 346 _init(); 347 #endif 348 349 exit(main(ps_strings->ps_nargvstr, ps_strings->ps_argvstr, environ)); 350 } 351