sysdeps/unix/sparc/start.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96, 97 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <fcntl.h>
  23
  24 #ifndef NO_SHLIB
  25 #include <sys/exec.h>
  26 #include <sys/types.h>
  27 #include <sys/mman.h>
  28 #include <link.h>
  29 #include <syscall.h>
  30 #endif
  31
  32 #if !defined (__GNUC__) || __GNUC__ < 2
  33   #error This file uses GNU C extensions; you must compile with GCC version 2.
  34 #endif
  35
  36 /* The first piece of initialized data.  */
  37 int __data_start = 0;
  38 #ifdef HAVE_WEAK_SYMBOLS
  39 weak_alias (__data_start, data_start)
  40 #endif
  41
  42 VOLATILE int __errno;
  43 strong_alias (__errno, errno)
  44
  45
  46 extern void __libc_init __P ((int argc, char **argv, char **envp));
  47 extern int main __P ((int argc, char **argv, char **envp));
  48
  49 register long int sp asm("%sp"), fp asm("%fp");
  50
  51 #ifndef NO_SHLIB
  52 static void init_shlib __P ((void));
  53 #endif
  54
  55 #ifndef NO_EXPLICIT_START
  56 /* Declare _start with an explicit assembly symbol name of `start'
  57    (note no leading underscore).  This is the name Sun's crt0.o uses,
  58    and programs are often linked with `ld -e start'.  */
  59 void _start (void) asm ("start");
  60 #endif
  61
  62 void
  63 _start (void)
  64 {
  65   /* It is important that these be declared `register'.
  66      Otherwise, when compiled without optimization, they are put on the
  67      stack, which loses completely after we zero the FP.  */
  68   register int argc;
  69   register char **argv, **envp;
  70
  71   /* Unwind the frame built when we entered the function.  */
  72   asm("restore");
  73
  74   /* And clear the frame pointer.  */
  75   fp = 0;
  76
  77   /* The argument info starts after one register
  78      window (64 bytes) past the SP.  */
  79   argc = ((int *) sp)[16];
  80   argv = (char **) &((int *) sp)[17];
  81   envp = &argv[argc + 1];
  82   __environ = envp;
  83
  84 #ifndef NO_SHLIB
  85   init_shlib ();
  86 #endif
  87
  88   /* Allocate 24 bytes of stack space for the register save area.  */
  89   sp -= 24;
  90   __libc_init (argc, argv, envp);
  91
  92   exit (main (argc, argv, envp));
  93 }
  94 \f
  95 #ifndef NO_SHLIB
  96
  97 /* System calls for use by the bootstrap routine.
  98    These are defined here since the usual calls may be dynamically linked.  */
  99
 100 int syscall (int sysno, ...) asm ("init_syscall");
 101 asm ("init_syscall:\n"
 102      "  clr %g1\n"
 103      "  ta 0\n"
 104      "  bcc 1f\n"
 105      "  sethi %hi(_errno), %g1\n"
 106      "  st %o0, [%g1 + %lo(_errno)]\n"
 107      "  sub %g0, 1, %o0\n"
 108      "1:retl\n"
 109      "  nop");
 110
 111 static void
 112 init_shlib ()
 113 {
 114   extern struct link_dynamic _DYNAMIC;
 115   int so, zf;
 116   caddr_t somap;
 117   caddr_t sodmap;
 118   caddr_t sobssmap;
 119   void (*ldstart) (int, int);
 120   struct exec soexec;
 121   struct
 122     {
 123       caddr_t crt_ba;
 124       int crt_dzfd;
 125       int crt_ldfd;
 126       struct link_dynamic *crt_dp;
 127       char **crt_ep;
 128       caddr_t crt_bp;
 129     } soarg;
 130
 131   /* If not dynamically linked, do nothing.  */
 132   if (&_DYNAMIC == 0)
 133     return;
 134
 135   /* Map in the dynamic linker.  */
 136   so = syscall (SYS_open, "/usr/lib/ld.so", O_RDONLY);
 137   if (syscall (SYS_read, so, &soexec, sizeof (soexec)) != sizeof (soexec)
 138       || soexec.a_magic != ZMAGIC)
 139     {
 140       static const char emsg[] = "crt0: no /usr/lib/ld.so\n";
 141
 142       syscall (SYS_write, 2, emsg, sizeof (emsg) - 1);
 143       syscall (SYS_exit, 127);
 144     }
 145   somap = (caddr_t) syscall (SYS_mmap, 0,
 146                              soexec.a_text + soexec.a_data + soexec.a_bss,
 147                              PROT_READ | PROT_EXEC, _MAP_NEW | MAP_PRIVATE,
 148                              so, 0);
 149   sodmap = (caddr_t) syscall (SYS_mmap, somap + soexec.a_text, soexec.a_data,
 150                               PROT_READ | PROT_WRITE | PROT_EXEC,
 151                               _MAP_NEW | MAP_FIXED | MAP_PRIVATE,
 152                               so, soexec.a_text);
 153   zf = syscall (SYS_open, "/dev/zero", O_RDONLY);
 154   if (soexec.a_bss != 0)
 155     sobssmap = (caddr_t) syscall (SYS_mmap,
 156                                   somap + soexec.a_text + soexec.a_data,
 157                                   soexec.a_bss,
 158                                   PROT_READ | PROT_WRITE | PROT_EXEC,
 159                                   _MAP_NEW | MAP_FIXED | MAP_PRIVATE,
 160                                   zf, 0);
 161
 162   /* Call the entry point of the dynamic linker.  */
 163   soarg.crt_ba = somap;
 164   soarg.crt_dzfd = zf;
 165   soarg.crt_ldfd = so;
 166   soarg.crt_dp = &_DYNAMIC;
 167   soarg.crt_ep = __environ;
 168   soarg.crt_bp = (caddr_t) &&retaddr;
 169
 170   ldstart = (__typeof (ldstart)) (somap + soexec.a_entry);
 171   (*ldstart) (1, (char *) &soarg - (char *) sp);
 172
 173  retaddr:
 174 }
 175
 176 #endif