lib/csu/mips/crt0.c

   1 /* $NetBSD: crt0.c,v 1.20 2009/12/14 01:04:02 matt Exp $ */
   2
   3 /*
   4  * Copyright (c) 1995 Christopher G. Demetriou
   5  * All rights reserved.
   6  *
   7  * Modifications for NetBSD/mips:
   8  *
   9  *      Jonathan Stone
  10  *      Jason R. Thorpe, Numerical Aerospace Simulation Facility,
  11  *          NASA Ames Research Center
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. All advertising materials mentioning features or use of this software
  22  *    must display the following acknowledgement:
  23  *      This product includes software developed by Christopher G. Demetriou
  24  *      for the NetBSD Project.
  25  * 4. The name of the author may not be used to endorse or promote products
  26  *    derived from this software without specific prior written permission
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  29  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  30  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  31  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  32  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  33  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  34  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  35  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  36  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  37  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  38  */
  39
  40 #include "common.h"
  41
  42 /*
  43  *      C start-up.  Assumes kernel (or ld.so) passes the
  44  *      following parameters to user-space in registers:
  45  *
  46  *      a0      stack pointer (0 if setregs didn't fill this in)
  47  *      a1      cleanup
  48  *      a2      Obj_Entry
  49  *      a3      ps_strings
  50  *
  51  *      XXX Does this violate the ABI?
  52  *      as well as the usual registers (pc, sp, and t9 == pc for ABI).
  53  */
  54
  55 void __start(u_long, void (*)(void), const Obj_Entry *,
  56                 struct ps_strings *);
  57
  58 __asm(".text; .align 4;  .globl _start; _start:");
  59
  60 void
  61 __start(u_long sp,
  62     void (*cleanup)(void),              /* from shared loader */
  63     const Obj_Entry *obj,               /* from shared loader */
  64     struct ps_strings *ps_strings)
  65 {
  66         char **ksp;
  67         char **argv, *namep;
  68         int argc;
  69
  70         /*
  71          * Grab the argc, argv, and envp set up by the kernel.
  72          * Layout of stuff on the stack:
  73          *
  74          *      [ high ]
  75          *      char    kenvstr[1];     // size varies
  76          *      char    kargstr[1];     // size varies
  77          *      char    *argv[1];       // varies on argc
  78          *      int     argc;
  79          *      [ low ]                 <--- kernel's SP points here
  80          *      .
  81          *      .
  82          *      .
  83          *      [ current stack pointer ]
  84          *
  85          * WARNING!  There is an implicit sizeof(int) == sizeof(char *) here!
  86          */
  87
  88 #ifndef DYNAMIC
  89 #ifdef _LP64
  90         __asm volatile("dla $28,_gp");
  91 #else
  92         __asm volatile("la $28,_gp");
  93 #endif
  94 #endif
  95
  96         ksp = (char**)sp;
  97 #if defined(__mips_n32) || defined(__mips_n64)
  98         if (ksp == 0) {
  99                 /*
 100                  * Uh, oh. We're running on a old kernel that passed
 101                  * us zero in $a0-$a3.  Try adjusting the current
 102                  * $sp for our own stack-frame size and see  what
 103                  * we find.
 104                  * WARNING!  The constants 56 and 64 below were determined
 105                  * by examining GCC assembler output of __start to find the
 106                  * frame size.  If you change the code or compiler,
 107                  * you _will_ lose!
 108                  */
 109
 110 #ifndef DYNAMIC
 111                 /* XXX 56 is compiler and stackframe dependent */
 112                 __asm volatile("        addiu   %0,$29,56" : "=r" (ksp));
 113 #else
 114                 /* XXX 64 is compiler and stackframe dependent */
 115                 __asm volatile("        addiu   %0,$29,64" : "=r" (ksp));
 116 #endif
 117         }
 118 #endif
 119
 120
 121         argc = *(int *)ksp;
 122         argv = ksp + 1;
 123         environ = ksp + 2 + argc;       /* 2: argc + NULL ending argv */
 124
 125         if ((namep = argv[0]) != NULL) {        /* NULL ptr if argc = 0 */
 126                 if ((__progname = _strrchr(namep, '/')) == NULL)
 127                         __progname = namep;
 128                 else
 129                         __progname++;
 130         }
 131
 132         /*
 133          * Deal with stuff that is only provided if setregs() did
 134          * did the right thing.
 135          */
 136         if (sp != 0) {
 137                 if (ps_strings != (struct ps_strings *)0)
 138                         __ps_strings = ps_strings;
 139 #ifdef DYNAMIC
 140                 /*
 141                  * XXX Old MIPS ld.so didn't do any of this at all.
 142                  * XXX If we were loaded by that loader, just abort
 143                  * XXX the rtld setup.
 144                  */
 145                 if (&_DYNAMIC != NULL && cleanup != NULL && obj != NULL)
 146                         _rtld_setup(cleanup, obj);
 147 #endif
 148         }
 149
 150 #ifdef MCRT0
 151         atexit(_mcleanup);
 152         monstartup((u_long)&_eprol, (u_long)&_etext);
 153 #endif
 154
 155         atexit(_fini);
 156         _init();
 157
 158         exit(main(argc, argv, environ));
 159 }
 160
 161 /*
 162  * RCSid. Place after __start for programs that assume start of text
 163  *  is the entrypoint. (Only needed for old toolchains).
 164  */
 165 #if defined(LIBC_SCCS) && !defined(lint)
 166 __RCSID("$NetBSD: crt0.c,v 1.20 2009/12/14 01:04:02 matt Exp $");
 167 #endif /* LIBC_SCCS and not lint */
 168
 169 #include "common.c"