1 /* $NetBSD: crt0-common.c,v 1.24 2021/04/20 21:42:31 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 1.24 2021/04/20 21:42:31 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 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 defined(__x86_64__) || defined(__powerpc__) || defined(__sparc__) 130 #define HAS_IPLTA 131 static void fix_iplta(void) __noinline; 132 #elif defined(__i386__) || defined(__arm__) 133 #define HAS_IPLT 134 static void fix_iplt(void) __noinline; 135 #endif 136 137 138 #ifdef HAS_IPLTA 139 #include <stdio.h> 140 extern const Elf_Rela __rela_iplt_start[] __dso_hidden __weak; 141 extern const Elf_Rela __rela_iplt_end[] __dso_hidden __weak; 142 #ifdef __sparc__ 143 #define IFUNC_RELOCATION R_TYPE(JMP_IREL) 144 #include <machine/elf_support.h> 145 #define write_plt(where, value) sparc_write_branch((void *)where, (void *)value) 146 #else 147 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 148 #define write_plt(where, value) *where = value 149 #endif 150 151 static void 152 fix_iplta(void) 153 { 154 const Elf_Rela *rela, *relalim; 155 uintptr_t relocbase = 0; 156 Elf_Addr *where, target; 157 158 rela = __rela_iplt_start; 159 relalim = __rela_iplt_end; 160 for (; rela < relalim; ++rela) { 161 if (ELF_R_TYPE(rela->r_info) != IFUNC_RELOCATION) 162 abort(); 163 where = (Elf_Addr *)(relocbase + rela->r_offset); 164 target = (Elf_Addr)(relocbase + rela->r_addend); 165 target = ((Elf_Addr(*)(void))target)(); 166 write_plt(where, target); 167 } 168 } 169 #endif 170 #ifdef HAS_IPLT 171 extern const Elf_Rel __rel_iplt_start[] __dso_hidden __weak; 172 extern const Elf_Rel __rel_iplt_end[] __dso_hidden __weak; 173 #define IFUNC_RELOCATION R_TYPE(IRELATIVE) 174 175 static void 176 fix_iplt(void) 177 { 178 const Elf_Rel *rel, *rellim; 179 uintptr_t relocbase = 0; 180 Elf_Addr *where, target; 181 182 rel = __rel_iplt_start; 183 rellim = __rel_iplt_end; 184 for (; rel < rellim; ++rel) { 185 if (ELF_R_TYPE(rel->r_info) != IFUNC_RELOCATION) 186 abort(); 187 where = (Elf_Addr *)(relocbase + rel->r_offset); 188 target = ((Elf_Addr(*)(void))*where)(); 189 *where = target; 190 } 191 } 192 #endif 193 194 #if defined(__x86_64__) || defined(__i386__) 195 # define HAS_RELOCATE_SELF 196 # if defined(__x86_64__) 197 # define RELA 198 # define REL_TAG DT_RELA 199 # define RELSZ_TAG DT_RELASZ 200 # define REL_TYPE Elf_Rela 201 # else 202 # define REL_TAG DT_REL 203 # define RELSZ_TAG DT_RELSZ 204 # define REL_TYPE Elf_Rel 205 # endif 206 207 #include <elf.h> 208 209 static void relocate_self(struct ps_strings *) __noinline; 210 211 static void 212 relocate_self(struct ps_strings *ps_strings) 213 { 214 AuxInfo *aux = (AuxInfo *)(ps_strings->ps_argvstr + ps_strings->ps_nargvstr + 215 ps_strings->ps_nenvstr + 2); 216 uintptr_t relocbase = (uintptr_t)~0U; 217 const Elf_Phdr *phdr = NULL; 218 Elf_Half phnum = (Elf_Half)~0; 219 220 for (; aux->a_type != AT_NULL; ++aux) { 221 switch (aux->a_type) { 222 case AT_BASE: 223 if (aux->a_v) 224 return; 225 break; 226 case AT_PHDR: 227 phdr = (void *)aux->a_v; 228 break; 229 case AT_PHNUM: 230 phnum = (Elf_Half)aux->a_v; 231 break; 232 } 233 } 234 235 if (phdr == NULL || phnum == (Elf_Half)~0) 236 return; 237 238 const Elf_Phdr *phlimit = phdr + phnum, *dynphdr = NULL; 239 240 for (; phdr < phlimit; ++phdr) { 241 if (phdr->p_type == PT_DYNAMIC) 242 dynphdr = phdr; 243 if (phdr->p_type == PT_PHDR) 244 relocbase = (uintptr_t)phdr - phdr->p_vaddr; 245 } 246 if (dynphdr == NULL || relocbase == (uintptr_t)~0U) 247 return; 248 249 Elf_Dyn *dynp = (Elf_Dyn *)((uint8_t *)dynphdr->p_vaddr + relocbase); 250 251 const REL_TYPE *relocs = 0, *relocslim; 252 Elf_Addr relocssz = 0; 253 254 for (; dynp->d_tag != DT_NULL; dynp++) { 255 switch (dynp->d_tag) { 256 case REL_TAG: 257 relocs = 258 (const REL_TYPE *)(relocbase + dynp->d_un.d_ptr); 259 break; 260 case RELSZ_TAG: 261 relocssz = dynp->d_un.d_val; 262 break; 263 } 264 } 265 relocslim = (const REL_TYPE *)((const uint8_t *)relocs + relocssz); 266 for (; relocs < relocslim; ++relocs) { 267 Elf_Addr *where; 268 269 where = (Elf_Addr *)(relocbase + relocs->r_offset); 270 271 switch (ELF_R_TYPE(relocs->r_info)) { 272 case R_TYPE(RELATIVE): /* word64 B + A */ 273 #ifdef RELA 274 *where = (Elf_Addr)(relocbase + relocs->r_addend); 275 #else 276 *where += (Elf_Addr)relocbase; 277 #endif 278 break; 279 #ifdef IFUNC_RELOCATION 280 case IFUNC_RELOCATION: 281 break; 282 #endif 283 default: 284 abort(); 285 } 286 } 287 } 288 #endif 289 290 void 291 ___start(void (*cleanup)(void), /* from shared loader */ 292 struct ps_strings *ps_strings) 293 { 294 #if defined(HAS_RELOCATE_SELF) 295 relocate_self(ps_strings); 296 #endif 297 298 if (ps_strings == NULL) 299 _FATAL("ps_strings missing\n"); 300 __ps_strings = ps_strings; 301 302 environ = ps_strings->ps_envstr; 303 304 if (ps_strings->ps_argvstr[0] != NULL) { 305 char *c; 306 __progname = ps_strings->ps_argvstr[0]; 307 for (c = ps_strings->ps_argvstr[0]; *c; ++c) { 308 if (*c == '/') 309 __progname = c + 1; 310 } 311 } else { 312 __progname = empty_string; 313 } 314 315 if (cleanup != NULL) 316 atexit(cleanup); 317 318 _libc_init(); 319 320 if (&rtld_DYNAMIC == NULL) { 321 #ifdef HAS_IPLTA 322 fix_iplta(); 323 #endif 324 #ifdef HAS_IPLT 325 fix_iplt(); 326 #endif 327 } 328 329 _preinit(); 330 331 #ifdef MCRT0 332 atexit(_mcleanup); 333 monstartup((u_long)&__eprol, (u_long)&__etext); 334 #endif 335 336 atexit(_finiarray); 337 _initarray(); 338 339 #ifndef HAVE_INITFINI_ARRAY 340 atexit(_fini); 341 _init(); 342 #endif 343 344 exit(main(ps_strings->ps_nargvstr, ps_strings->ps_argvstr, environ)); 345 } 346