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-rw-r--r--libc/sysdeps/linux/i386/crt0.S123
1 files changed, 123 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/i386/crt0.S b/libc/sysdeps/linux/i386/crt0.S
new file mode 100644
index 000000000..08e406cc6
--- /dev/null
+++ b/libc/sysdeps/linux/i386/crt0.S
@@ -0,0 +1,123 @@
+/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+
+/* If you don't know what is going on here, check out
+ http://linuxassembly.org/startup.html
+ For a description of the stack layout.
+ -John Beppu, and Erik Andersen
+*/
+
+.global __environ
+.global __errno
+.global _start
+.global exit
+.global main
+.global __stdio_close_all
+.global _void_void_null_func
+.global _start_exit
+
+.text
+_start:
+ /* First locate the start of the environment variables */
+ popl %ecx /* Store argc into %ecx */
+ movl %esp,%ebx /* Store argv into ebx */
+ movl %esp,%eax /* Store argv into eax as well*/
+ movl %ecx,%edx /* Stick argc into %edx so we can do some math in a sec */
+ leal 4(%eax,%edx,4),%eax
+
+ /* [ register layout ]
+
+ sizeof(char*) == 4
+ %ecx = argc ; 0(esp)
+ %ebx = argv ; 4(esp)
+ %eax = env ; argv + (argc * 4) + 4
+ */
+
+
+ /* Set up an invalid (NULL return address, NULL frame pointer)
+ callers stack frame so anybody unrolling the stack knows where
+ to stop */
+ xorl %ebp,%ebp /* NULL */
+ pushl %ebp /* callers %cs */
+ pushl %ebp /* callers %eip (return address) */
+ pushl %ebp /* callers %ebp (frame pointer) */
+ movl %esp,%ebp /* mark callers stack frame as invalid */
+
+ /* Now set the environment, argc, and argv where the app can get to them */
+ pushl %eax /* Environment pointer */
+ pushl %ebx /* Argument pointer */
+ pushl %ecx /* And the argument count */
+
+ /* Make sure we are not using iBCS2 personality. (i.e. force linux). */
+ movl $136,%eax
+ sub %ebx,%ebx
+ int $0x80
+
+ /* set up __environ */
+ movl 8(%esp),%eax
+ movl %eax,__environ
+
+ /* Tell libc to initialize anything it needs to do */
+ call __libc_init
+ /* call __malloc_init */
+ call __init_stdio
+
+ /* Ok, now run main() */
+ call main
+ pushl %eax
+ call exit
+
+ /* Just in case _exit fails... We use int $0x80 for __exit(). */
+ popl %ebx
+ .align 4,0x90
+_start_exit:
+ movl $1,%eax
+ int $0x80
+ jmp _start_exit
+ .align 4,0x90
+_void_void_null_func:
+ ret
+
+.weak __libc_init
+__libc_init = _void_void_null_func
+
+/*
+.weak __malloc_init
+__malloc_init = _void_void_null_func
+*/
+
+.weak __init_stdio
+__init_stdio = _void_void_null_func
+
+.weak __stdio_close_all
+__stdio_close_all = _void_void_null_func
+
+.data
+__environ:
+ .long 0
+.weak environ
+.align 4
+environ = __environ
+
+.data
+__errno:
+ .long 0
+.weak errno
+.align 4
+errno = __errno