1 /* $NetBSD: crt0-common.c,v 1.27 2022/06/21 06:52:17 skrll 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 1.27 2022/06/21 06:52:17 skrll 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 extern void _libc_init(void); 59 60 /* 61 * Arrange for _DYNAMIC to be weak and undefined (and therefore to show up 62 * as being at address zero, unless something else defines it). That way, 63 * if we happen to be compiling without -static but with without any 64 * shared libs present, things will still work. 65 */ 66 67 __weakref_visible int rtld_DYNAMIC __weak_reference(_DYNAMIC); 68 69 #ifdef MCRT0 70 extern void monstartup(u_long, u_long); 71 extern void _mcleanup(void); 72 extern unsigned char __etext, __eprol; 73 #endif /* MCRT0 */ 74 75 static char empty_string[] = ""; 76 77 char **environ __common; 78 struct ps_strings *__ps_strings __common = 0; 79 char *__progname __common = empty_string; 80 81 __dead __dso_hidden void ___start(void (*)(void), struct ps_strings *); 82 83 #define write(fd, s, n) __syscall(SYS_write, (fd), (s), (n)) 84 85 #define _FATAL(str) \ 86 do { \ 87 write(2, str, sizeof(str)-1); \ 88 _exit(1); \ 89 } while (0) 90 91 /* 92 * If we are using INIT_ARRAY/FINI_ARRAY and we are linked statically, 93 * we have to process these instead of relying on RTLD to do it for us. 94 * 95 * Since we don't need .init or .fini sections, just code them in C 96 * to make life easier. 97 */ 98 extern const fptr_t __preinit_array_start[] __dso_hidden; 99 extern const fptr_t __preinit_array_end[] __dso_hidden __weak; 100 extern const fptr_t __init_array_start[] __dso_hidden; 101 extern const fptr_t __init_array_end[] __dso_hidden __weak; 102 extern const fptr_t __fini_array_start[] __dso_hidden; 103 extern const fptr_t __fini_array_end[] __dso_hidden __weak; 104 105 static inline void 106 _preinit(void) 107 { 108 for (const fptr_t *f = __preinit_array_start; f < __preinit_array_end; f++) { 109 (*f)(); 110 } 111 } 112 113 static inline void 114 _initarray(void) 115 { 116 for (const fptr_t *f = __init_array_start; f < __init_array_end; f++) { 117 (*f)(); 118 } 119 } 120 121 static void 122 _finiarray(void) 123 { 124 for (const fptr_t *f = __fini_array_start; f < __fini_array_end; f++) { 125 (*f)(); 126 } 127 } 128 129 #if \ 130 defined(__aarch64__) || \ 131 defined(__powerpc__) || \ 132 defined(__sparc__) || \ 133 defined(__x86_64__) 134 #define HAS_IPLTA 135 static void fix_iplta(void) __noinline; 136 #elif \ 137 defined(__arm__) || \ 138 defined(__i386__) 139 #define HAS_IPLT 140 static void fix_iplt(void) __noinline; 141 #endif 142 143 144 #ifdef HAS_IPLTA 145 #include <stdio.h> 146 extern const Elf_Rela __rela_iplt_start[] __dso_hidden __weak; 147 extern const Elf_Rela __rela_iplt_end[] __dso_hidden __weak; 148 #ifdef __sparc__ 149 #define IFUNC_RELOCATION R_TYPE(JMP_IREL) 150 #include <machine/elf_support.h> 151 #define write_plt(where, value) sparc_write_branch((void *)where, (void *)value) 152 #else 153 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 154 #define write_plt(where, value) *where = value 155 #endif 156 157 static void 158 fix_iplta(void) 159 { 160 const Elf_Rela *rela, *relalim; 161 uintptr_t relocbase = 0; 162 Elf_Addr *where, target; 163 164 rela = __rela_iplt_start; 165 relalim = __rela_iplt_end; 166 for (; rela < relalim; ++rela) { 167 if (ELF_R_TYPE(rela->r_info) != IFUNC_RELOCATION) 168 abort(); 169 where = (Elf_Addr *)(relocbase + rela->r_offset); 170 target = (Elf_Addr)(relocbase + rela->r_addend); 171 target = ((Elf_Addr(*)(void))target)(); 172 write_plt(where, target); 173 } 174 } 175 #endif 176 #ifdef HAS_IPLT 177 extern const Elf_Rel __rel_iplt_start[] __dso_hidden __weak; 178 extern const Elf_Rel __rel_iplt_end[] __dso_hidden __weak; 179 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 180 181 static void 182 fix_iplt(void) 183 { 184 const Elf_Rel *rel, *rellim; 185 uintptr_t relocbase = 0; 186 Elf_Addr *where, target; 187 188 rel = __rel_iplt_start; 189 rellim = __rel_iplt_end; 190 for (; rel < rellim; ++rel) { 191 if (ELF_R_TYPE(rel->r_info) != IFUNC_RELOCATION) 192 abort(); 193 where = (Elf_Addr *)(relocbase + rel->r_offset); 194 target = ((Elf_Addr(*)(void))*where)(); 195 *where = target; 196 } 197 } 198 #endif 199 200 #if defined(__x86_64__) || defined(__i386__) 201 # define HAS_RELOCATE_SELF 202 # if defined(__x86_64__) 203 # define RELA 204 # define REL_TAG DT_RELA 205 # define RELSZ_TAG DT_RELASZ 206 # define REL_TYPE Elf_Rela 207 # else 208 # define REL_TAG DT_REL 209 # define RELSZ_TAG DT_RELSZ 210 # define REL_TYPE Elf_Rel 211 # endif 212 213 #include <elf.h> 214 215 static void relocate_self(struct ps_strings *) __noinline; 216 217 static void 218 relocate_self(struct ps_strings *ps_strings) 219 { 220 AuxInfo *aux = (AuxInfo *)(ps_strings->ps_argvstr + ps_strings->ps_nargvstr + 221 ps_strings->ps_nenvstr + 2); 222 uintptr_t relocbase = (uintptr_t)~0U; 223 const Elf_Phdr *phdr = NULL; 224 Elf_Half phnum = (Elf_Half)~0; 225 226 for (; aux->a_type != AT_NULL; ++aux) { 227 switch (aux->a_type) { 228 case AT_BASE: 229 if (aux->a_v) 230 return; 231 break; 232 case AT_PHDR: 233 phdr = (void *)aux->a_v; 234 break; 235 case AT_PHNUM: 236 phnum = (Elf_Half)aux->a_v; 237 break; 238 } 239 } 240 241 if (phdr == NULL || phnum == (Elf_Half)~0) 242 return; 243 244 const Elf_Phdr *phlimit = phdr + phnum, *dynphdr = NULL; 245 246 for (; phdr < phlimit; ++phdr) { 247 if (phdr->p_type == PT_DYNAMIC) 248 dynphdr = phdr; 249 if (phdr->p_type == PT_PHDR) 250 relocbase = (uintptr_t)phdr - phdr->p_vaddr; 251 } 252 if (dynphdr == NULL || relocbase == (uintptr_t)~0U) 253 return; 254 255 Elf_Dyn *dynp = (Elf_Dyn *)((uint8_t *)dynphdr->p_vaddr + relocbase); 256 257 const REL_TYPE *relocs = 0, *relocslim; 258 Elf_Addr relocssz = 0; 259 260 for (; dynp->d_tag != DT_NULL; dynp++) { 261 switch (dynp->d_tag) { 262 case REL_TAG: 263 relocs = 264 (const REL_TYPE *)(relocbase + dynp->d_un.d_ptr); 265 break; 266 case RELSZ_TAG: 267 relocssz = dynp->d_un.d_val; 268 break; 269 } 270 } 271 relocslim = (const REL_TYPE *)((const uint8_t *)relocs + relocssz); 272 for (; relocs < relocslim; ++relocs) { 273 Elf_Addr *where; 274 275 where = (Elf_Addr *)(relocbase + relocs->r_offset); 276 277 switch (ELF_R_TYPE(relocs->r_info)) { 278 case R_TYPE(RELATIVE): /* word64 B + A */ 279 #ifdef RELA 280 *where = (Elf_Addr)(relocbase + relocs->r_addend); 281 #else 282 *where += (Elf_Addr)relocbase; 283 #endif 284 break; 285 #ifdef IFUNC_RELOCATION 286 case IFUNC_RELOCATION: 287 break; 288 #endif 289 default: 290 abort(); 291 } 292 } 293 } 294 #endif 295 296 void 297 ___start(void (*cleanup)(void), /* from shared loader */ 298 struct ps_strings *ps_strings) 299 { 300 #if defined(HAS_RELOCATE_SELF) 301 relocate_self(ps_strings); 302 #endif 303 304 if (ps_strings == NULL) 305 _FATAL("ps_strings missing\n"); 306 __ps_strings = ps_strings; 307 308 environ = ps_strings->ps_envstr; 309 310 if (ps_strings->ps_argvstr[0] != NULL) { 311 char *c; 312 __progname = ps_strings->ps_argvstr[0]; 313 for (c = ps_strings->ps_argvstr[0]; *c; ++c) { 314 if (*c == '/') 315 __progname = c + 1; 316 } 317 } else { 318 __progname = empty_string; 319 } 320 321 if (cleanup != NULL) 322 atexit(cleanup); 323 324 _libc_init(); 325 326 if (&rtld_DYNAMIC == NULL) { 327 #ifdef HAS_IPLTA 328 fix_iplta(); 329 #endif 330 #ifdef HAS_IPLT 331 fix_iplt(); 332 #endif 333 } 334 335 _preinit(); 336 337 #ifdef MCRT0 338 atexit(_mcleanup); 339 monstartup((u_long)&__eprol, (u_long)&__etext); 340 #endif 341 342 atexit(_finiarray); 343 _initarray(); 344 345 #ifndef HAVE_INITFINI_ARRAY 346 atexit(_fini); 347 _init(); 348 #endif 349 350 exit(main(ps_strings->ps_nargvstr, ps_strings->ps_argvstr, environ)); 351 } 352