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+/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
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+This file is part of the GNU C Library.
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+
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+The GNU C Library is free software; you can redistribute it and/or
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+modify it under the terms of the GNU Library General Public License as
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+published by the Free Software Foundation; either version 2 of the
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+License, or (at your option) any later version.
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+
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+The GNU C Library is distributed in the hope that it will be useful,
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+but 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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+Library General Public License for more details.
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+
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+You should have received a copy of the GNU Library General Public
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+License along with the GNU C Library; see the file COPYING.LIB. If
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+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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+Cambridge, MA 02139, USA. */
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+
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+
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+/* Based on the code from GNU libc, but hacked up by John Beppu and Erik Andersen */
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+/* adapted by PaX Team for ET_DYN/PIE binaries */
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+
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+/*
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+ When we enter this piece of code, the program stack looks like this:
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+ argc argument counter (integer)
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+ argv[0] program name (pointer)
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+ argv[1...N] program args (pointers)
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+ argv[argc-1] end of args (integer)
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+ NULL
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+ env[0...N] environment variables (pointers)
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+ NULL
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+*/
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+
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+#include <features.h>
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+
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+.text
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+ .align 4
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+
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+ .global _start
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+ .type _start,%function
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+ .weak _init
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+ .weak _fini
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+ .type __uClibc_start_main,%function
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+
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+_start:
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+ /* locate the start of the environment variables */
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+ popl %ecx /* Store argc into %ecx */
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+ movl %esp,%ebx /* Store argv into ebx */
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+ movl %esp,%eax /* Store argv into eax as well*/
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+ movl %edx,%esi /* Store edx(FINI ptr) in %esi */
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+ movl %ecx,%edx /* Stick argc into %edx so we can do some math in a sec */
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+ leal 4(%eax,%edx,4),%eax
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+
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+ /* [ register layout ]
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+
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+ sizeof(char*) == 4
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+ %ecx = argc ; 0(esp)
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+ %ebx = argv ; 4(esp)
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+ %eax = env ; argv + (argc * 4) + 4
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+ */
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+ xorl %ebp,%ebp /* NULL */
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+ /*
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+ Before pushing the arguments align the stack to a 16-byte
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+ (SSE needs 16-byte alignment) boundary to avoid penalties from
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+ misaligned accesses. Thanks to Edward Seidl <seidl@janed.com>
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+ for pointing this out.
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+ */
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+ andl $0xfffffff0, %esp
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+ /* Push NULL to make sure stack ptr
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+ is 16 byte aligned when calling __uClibc_start_main */
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+ pushl %ebp
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+ pushl %ebp
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+
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+ /* Set up an invalid (NULL return address, NULL frame pointer)
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+ callers stack frame so anybody unrolling the stack knows where
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+ to stop */
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+ pushl %ebp /* callers %cs */
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+ pushl %ebp /* callers %eip (return address) */
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+ pushl %ebp /* callers %ebp (frame pointer) */
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+ movl %esp,%ebp /* mark callers stack frame as invalid */
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+
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+#if defined L_Scrt1
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+ call .L0
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+.L0:
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+ pop %edx
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+ addl $_GLOBAL_OFFSET_TABLE_+[.-.L0],%edx
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+#endif
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+ pushl %esi /* Push FINI pointer */
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+
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+ /* Push apps .init, .fini and main arguments to __uClibc_start_main() on the stack */
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+#ifdef L_Scrt1
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+ pushl main@GOT(%edx)
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+ pushl _fini@GOT(%edx)
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+ pushl _init@GOT(%edx)
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+#else
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+ pushl $main
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+ pushl $_fini
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+ pushl $_init
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+#endif
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+
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+ /* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */
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+ pushl %eax /* Environment pointer */
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+ pushl %ebx /* Argument pointer */
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+ pushl %ecx /* And the argument count */
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+
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+ /* Ok, now run uClibc's main() -- shouldn't return */
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+#ifdef L_Scrt1
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+ call *__uClibc_start_main@GOT(%edx)
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+#else
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+ call __uClibc_start_main
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+#endif
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+
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+ /* Crash if somehow `exit' returns anyways. */
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+ hlt
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+.size _start,.-_start
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+
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+
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+/* Define a symbol for the first piece of initialized data. */
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+ .data
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+ .globl __data_start
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+__data_start:
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+ .long 0
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+ .weak data_start
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+ data_start = __data_start
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+
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Joakim Tjernlund