Home | History | Annotate | Line # | Download | only in common
crt0-common.c revision 1.16.2.1 
      1 /* $NetBSD: crt0-common.c,v 1.16.2.1 2019/06/10 22:05:15 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 1.16.2.1 2019/06/10 22:05:15 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