163 lines
5.2 KiB
NASM
163 lines
5.2 KiB
NASM
! crt1.s for Solaris 2, x86
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! Copyright (C) 1993, 1998 Free Software Foundation, Inc.
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! Written By Fred Fish, Nov 1992
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!
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! This file is free software; you can redistribute it and/or modify it
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! under the terms of the GNU General Public License as published by the
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! Free Software Foundation; either version 2, or (at your option) any
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! later version.
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!
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! In addition to the permissions in the GNU General Public License, the
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! Free Software Foundation gives you unlimited permission to link the
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! compiled version of this file with other programs, and to distribute
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! those programs without any restriction coming from the use of this
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! file. (The General Public License restrictions do apply in other
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! respects; for example, they cover modification of the file, and
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! distribution when not linked into another program.)
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!
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! This file is distributed in the hope that it will be useful, but
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! WITHOUT ANY WARRANTY; without even the implied warranty of
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! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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! General Public License for more details.
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!
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! You should have received a copy of the GNU General Public License
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! along with this program; see the file COPYING. If not, write to
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! the Free Software Foundation, 59 Temple Place - Suite 330,
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! Boston, MA 02111-1307, USA.
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!
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! As a special exception, if you link this library with files
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! compiled with GCC to produce an executable, this does not cause
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! the resulting executable to be covered by the GNU General Public License.
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! This exception does not however invalidate any other reasons why
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! the executable file might be covered by the GNU General Public License.
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!
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! This file takes control of the process from the kernel, as specified
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! in section 3 of the System V Application Binary Interface, Intel386
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! Processor Supplement. It has been constructed from information obtained
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! from the ABI, information obtained from single stepping existing
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! Solaris executables through their startup code with gdb, and from
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! information obtained by single stepping executables on other i386 SVR4
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! implementations. This file is the first thing linked into any executable.
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.file "crt1.s"
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.ident "GNU C crt1.s"
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.weak _cleanup
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.weak _DYNAMIC
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.text
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! Start creating the initial frame by pushing a NULL value for the return
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! address of the initial frame, and mark the end of the stack frame chain
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! (the innermost stack frame) with a NULL value, per page 3-32 of the ABI.
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! Initialize the first stack frame pointer in %ebp (the contents of which
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! are unspecified at process initialization).
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.globl _start
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_start:
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pushl $0x0
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pushl $0x0
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movl %esp,%ebp
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! As specified per page 3-32 of the ABI, %edx contains a function
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! pointer that should be registered with atexit(), for proper
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! shared object termination. Just push it onto the stack for now
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! to preserve it. We want to register _cleanup() first.
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pushl %edx
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! Check to see if there is an _cleanup() function linked in, and if
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! so, register it with atexit() as the last thing to be run by
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! atexit().
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movl $_cleanup,%eax
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testl %eax,%eax
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je .L1
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pushl $_cleanup
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call atexit
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addl $0x4,%esp
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.L1:
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! Now check to see if we have an _DYNAMIC table, and if so then
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! we need to register the function pointer previously in %edx, but
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! now conveniently saved on the stack as the argument to pass to
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! atexit().
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movl $_DYNAMIC,%eax
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testl %eax,%eax
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je .L2
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call atexit
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.L2:
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! Register _fini() with atexit(). We will take care of calling _init()
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! directly.
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pushl $_fini
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call atexit
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! Compute the address of the environment vector on the stack and load
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! it into the global variable _environ. Currently argc is at 8 off
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! the frame pointer. Fetch the argument count into %eax, scale by the
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! size of each arg (4 bytes) and compute the address of the environment
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! vector which is 16 bytes (the two zero words we pushed, plus argc,
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! plus the null word terminating the arg vector) further up the stack,
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! off the frame pointer (whew!).
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movl 8(%ebp),%eax
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leal 16(%ebp,%eax,4),%edx
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movl %edx,_environ
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! Push the environment vector pointer, the argument vector pointer,
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! and the argument count on to the stack to set up the arguments
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! for _init(), _fpstart(), and main(). Note that the environment
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! vector pointer and the arg count were previously loaded into
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! %edx and %eax respectively. The only new value we need to compute
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! is the argument vector pointer, which is at a fixed address off
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! the initial frame pointer.
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!
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! Make sure the stack is properly aligned.
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!
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andl $0xfffffff0,%esp
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subl $4,%esp
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pushl %edx
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leal 12(%ebp),%edx
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pushl %edx
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pushl %eax
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! Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and
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! main(argc, argv, environ).
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call _init
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call __fpstart
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call main
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! Pop the argc, argv, and environ arguments off the stack, push the
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! value returned from main(), and call exit().
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addl $12,%esp
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pushl %eax
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call exit
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! An inline equivalent of _exit, as specified in Figure 3-26 of the ABI.
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pushl $0x0
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movl $0x1,%eax
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lcall $7,$0
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! If all else fails, just try a halt!
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hlt
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.type _start,@function
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.size _start,.-_start
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! A dummy profiling support routine for non-profiling executables,
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! in case we link in some objects that have been compiled for profiling.
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.weak _mcount
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_mcount:
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ret
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.type _mcount,@function
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.size _mcount,.-_mcount
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