sysdeps/unix/sparc/start.c

   1 /* Copyright (C) 1991, 1992, 1993, 1994, 1995 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
  45 #ifdef  HAVE_WEAK_SYMBOLS
  46 weak_alias (__environ, environ)
  47 #else
  48 #undef  environ
  49 #define __environ       environ
  50 #endif
  51
  52 char **__environ;
  53
  54 extern void EXFUN(__libc_init, (int argc, char **argv, char **envp));
  55 extern int EXFUN(main, (int argc, char **argv, char **envp));
  56
  57 register long int sp asm("%sp"), fp asm("%fp");
  58
  59 #ifndef NO_SHLIB
  60 static void EXFUN(init_shlib, (NOARGS));
  61 #endif
  62
  63 #ifndef NO_EXPLICIT_START
  64 /* Declare _start with an explicit assembly symbol name of `start'
  65    (note no leading underscore).  This is the name Sun's crt0.o uses,
  66    and programs are often linked with `ld -e start'.  */
  67 void _start (void) asm ("start");
  68 #endif
  69
  70 void
  71 _start (void)
  72 {
  73   /* It is important that these be declared `register'.
  74      Otherwise, when compiled without optimization, they are put on the
  75      stack, which loses completely after we zero the FP.  */
  76   register int argc;
  77   register char **argv, **envp;
  78
  79   /* Unwind the frame built when we entered the function.  */
  80   asm("restore");
  81
  82   /* And clear the frame pointer.  */
  83   fp = 0;
  84
  85   /* The argument info starts after one register
  86      window (64 bytes) past the SP.  */
  87   argc = ((int *) sp)[16];
  88   argv = (char **) &((int *) sp)[17];
  89   envp = &argv[argc + 1];
  90   __environ = envp;
  91
  92 #ifndef NO_SHLIB
  93   init_shlib ();
  94 #endif
  95
  96   /* Allocate 24 bytes of stack space for the register save area.  */
  97   sp -= 24;
  98   __libc_init (argc, argv, envp);
  99
 100   exit (main (argc, argv, envp));
 101 }
 102 \f
 103 #ifndef NO_SHLIB
 104
 105 /* System calls for use by the bootstrap routine.
 106    These are defined here since the usual calls may be dynamically linked.  */
 107
 108 int syscall (int sysno, ...) asm ("init_syscall");
 109 asm ("init_syscall:\n"
 110      "  clr %g1\n"
 111      "  ta 0\n"
 112      "  bcc 1f\n"
 113      "  sethi %hi(_errno), %g1\n"
 114      "  st %o0, [%g1 + %lo(_errno)]\n"
 115      "  sub %g0, 1, %o0\n"
 116      "1:retl\n"
 117      "  nop");
 118
 119 static void
 120 DEFUN_VOID(init_shlib)
 121 {
 122   extern struct link_dynamic _DYNAMIC;
 123   int so, zf;
 124   caddr_t somap;
 125   caddr_t sodmap;
 126   caddr_t sobssmap;
 127   void (*ldstart) (int, int);
 128   struct exec soexec;
 129   struct
 130     {
 131       caddr_t crt_ba;
 132       int crt_dzfd;
 133       int crt_ldfd;
 134       struct link_dynamic *crt_dp;
 135       char **crt_ep;
 136       caddr_t crt_bp;
 137     } soarg;
 138
 139   /* If not dynamically linked, do nothing.  */
 140   if (&_DYNAMIC == 0)
 141     return;
 142
 143   /* Map in the dynamic linker.  */
 144   so = syscall (SYS_open, "/usr/lib/ld.so", O_RDONLY);
 145   if (syscall (SYS_read, so, &soexec, sizeof (soexec)) != sizeof (soexec)
 146       || soexec.a_magic != ZMAGIC)
 147     {
 148       static CONST char emsg[] = "crt0: no /usr/lib/ld.so\n";
 149
 150       syscall (SYS_write, 2, emsg, sizeof (emsg) - 1);
 151       syscall (SYS_exit, 127);
 152     }
 153   somap = (caddr_t) syscall (SYS_mmap, 0,
 154                              soexec.a_text + soexec.a_data + soexec.a_bss,
 155                              PROT_READ | PROT_EXEC, _MAP_NEW | MAP_PRIVATE,
 156                              so, 0);
 157   sodmap = (caddr_t) syscall (SYS_mmap, somap + soexec.a_text, soexec.a_data,
 158                               PROT_READ | PROT_WRITE | PROT_EXEC,
 159                               _MAP_NEW | MAP_FIXED | MAP_PRIVATE,
 160                               so, soexec.a_text);
 161   zf = syscall (SYS_open, "/dev/zero", O_RDONLY);
 162   if (soexec.a_bss != 0)
 163     sobssmap = (caddr_t) syscall (SYS_mmap,
 164                                   somap + soexec.a_text + soexec.a_data,
 165                                   soexec.a_bss,
 166                                   PROT_READ | PROT_WRITE | PROT_EXEC,
 167                                   _MAP_NEW | MAP_FIXED | MAP_PRIVATE,
 168                                   zf, 0);
 169
 170   /* Call the entry point of the dynamic linker.  */
 171   soarg.crt_ba = somap;
 172   soarg.crt_dzfd = zf;
 173   soarg.crt_ldfd = so;
 174   soarg.crt_dp = &_DYNAMIC;
 175   soarg.crt_ep = __environ;
 176   soarg.crt_bp = (caddr_t) &&retaddr;
 177
 178   ldstart = (__typeof (ldstart)) (somap + soexec.a_entry);
 179   (*ldstart) (1, (char *) &soarg - (char *) sp);
 180
 181  retaddr:
 182 }
 183
 184 #endif