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
_preinit(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
_initarray(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
_finiarray(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
fix_iplta(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
fix_iplt(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
relocate_self(struct ps_strings * ps_strings)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
___start(void (* cleanup)(void),struct ps_strings * ps_strings)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