sysdeps/unix/sparc/start.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96 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
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <fcntl.h>
  24
  25 #ifndef NO_SHLIB
  26 #include <sys/exec.h>
  27 #include <sys/types.h>
  28 #include <sys/mman.h>
  29 #include <link.h>
  30 #include <syscall.h>
  31 #endif
  32
  33 #if !defined (__GNUC__) || __GNUC__ < 2
  34   #error This file uses GNU C extensions; you must compile with GCC version 2.
  35 #endif
  36
  37 /* The first piece of initialized data.  */
  38 int __data_start = 0;
  39 #ifdef HAVE_WEAK_SYMBOLS
  40 weak_alias (__data_start, data_start)
  41 #endif
  42
  43 VOLATILE int __errno;
  44 strong_alias (__errno, errno)
  45
  46
  47 extern void EXFUN(__libc_init, (int argc, char **argv, char **envp));
  48 extern int EXFUN(main, (int argc, char **argv, char **envp));
  49
  50 register long int sp asm("%sp"), fp asm("%fp");
  51
  52 #ifndef NO_SHLIB
  53 static void EXFUN(init_shlib, (NOARGS));
  54 #endif
  55
  56 #ifndef NO_EXPLICIT_START
  57 /* Declare _start with an explicit assembly symbol name of `start'
  58    (note no leading underscore).  This is the name Sun's crt0.o uses,
  59    and programs are often linked with `ld -e start'.  */
  60 void _start (void) asm ("start");
  61 #endif
  62
  63 void
  64 _start (void)
  65 {
  66   /* It is important that these be declared `register'.
  67      Otherwise, when compiled without optimization, they are put on the
  68      stack, which loses completely after we zero the FP.  */
  69   register int argc;
  70   register char **argv, **envp;
  71
  72   /* Unwind the frame built when we entered the function.  */
  73   asm("restore");
  74
  75   /* And clear the frame pointer.  */
  76   fp = 0;
  77
  78   /* The argument info starts after one register
  79      window (64 bytes) past the SP.  */
  80   argc = ((int *) sp)[16];
  81   argv = (char **) &((int *) sp)[17];
  82   envp = &argv[argc + 1];
  83   __environ = envp;
  84
  85 #ifndef NO_SHLIB
  86   init_shlib ();
  87 #endif
  88
  89   /* Allocate 24 bytes of stack space for the register save area.  */
  90   sp -= 24;
  91   __libc_init (argc, argv, envp);
  92
  93   exit (main (argc, argv, envp));
  94 }
  95 \f
  96 #ifndef NO_SHLIB
  97
  98 /* System calls for use by the bootstrap routine.
  99    These are defined here since the usual calls may be dynamically linked.  */
 100
 101 int syscall (int sysno, ...) asm ("init_syscall");
 102 asm ("init_syscall:\n"
 103      "  clr %g1\n"
 104      "  ta 0\n"
 105      "  bcc 1f\n"
 106      "  sethi %hi(_errno), %g1\n"
 107      "  st %o0, [%g1 + %lo(_errno)]\n"
 108      "  sub %g0, 1, %o0\n"
 109      "1:retl\n"
 110      "  nop");
 111
 112 static void
 113 DEFUN_VOID(init_shlib)
 114 {
 115   extern struct link_dynamic _DYNAMIC;
 116   int so, zf;
 117   caddr_t somap;
 118   caddr_t sodmap;
 119   caddr_t sobssmap;
 120   void (*ldstart) (int, int);
 121   struct exec soexec;
 122   struct
 123     {
 124       caddr_t crt_ba;
 125       int crt_dzfd;
 126       int crt_ldfd;
 127       struct link_dynamic *crt_dp;
 128       char **crt_ep;
 129       caddr_t crt_bp;
 130     } soarg;
 131
 132   /* If not dynamically linked, do nothing.  */
 133   if (&_DYNAMIC == 0)
 134     return;
 135
 136   /* Map in the dynamic linker.  */
 137   so = syscall (SYS_open, "/usr/lib/ld.so", O_RDONLY);
 138   if (syscall (SYS_read, so, &soexec, sizeof (soexec)) != sizeof (soexec)
 139       || soexec.a_magic != ZMAGIC)
 140     {
 141       static CONST char emsg[] = "crt0: no /usr/lib/ld.so\n";
 142
 143       syscall (SYS_write, 2, emsg, sizeof (emsg) - 1);
 144       syscall (SYS_exit, 127);
 145     }
 146   somap = (caddr_t) syscall (SYS_mmap, 0,
 147                              soexec.a_text + soexec.a_data + soexec.a_bss,
 148                              PROT_READ | PROT_EXEC, _MAP_NEW | MAP_PRIVATE,
 149                              so, 0);
 150   sodmap = (caddr_t) syscall (SYS_mmap, somap + soexec.a_text, soexec.a_data,
 151                               PROT_READ | PROT_WRITE | PROT_EXEC,
 152                               _MAP_NEW | MAP_FIXED | MAP_PRIVATE,
 153                               so, soexec.a_text);
 154   zf = syscall (SYS_open, "/dev/zero", O_RDONLY);
 155   if (soexec.a_bss != 0)
 156     sobssmap = (caddr_t) syscall (SYS_mmap,
 157                                   somap + soexec.a_text + soexec.a_data,
 158                                   soexec.a_bss,
 159                                   PROT_READ | PROT_WRITE | PROT_EXEC,
 160                                   _MAP_NEW | MAP_FIXED | MAP_PRIVATE,
 161                                   zf, 0);
 162
 163   /* Call the entry point of the dynamic linker.  */
 164   soarg.crt_ba = somap;
 165   soarg.crt_dzfd = zf;
 166   soarg.crt_ldfd = so;
 167   soarg.crt_dp = &_DYNAMIC;
 168   soarg.crt_ep = __environ;
 169   soarg.crt_bp = (caddr_t) &&retaddr;
 170
 171   ldstart = (__typeof (ldstart)) (somap + soexec.a_entry);
 172   (*ldstart) (1, (char *) &soarg - (char *) sp);
 173
 174  retaddr:
 175 }
 176
 177 #endif