/* 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. */ /* Based on the code from GNU libc, but hacked up by John Beppu and Erik Andersen */ /* adapted by PaX Team for ET_DYN/PIE binaries */ /* When we enter this piece of code, the program stack looks like this: argc argument counter (integer) argv[0] program name (pointer) argv[1...N] program args (pointers) argv[argc-1] end of args (integer) NULL env[0...N] environment variables (pointers) NULL */ #include <features.h> .text .align 4 .global _start .type _start,%function #if defined L_crt0 || defined L_Scrt0 || ! defined __UCLIBC_CTOR_DTOR__ .type __uClibc_main,%function #else .weak _init .weak _fini .type __uClibc_start_main,%function #endif /* Stick in a dummy reference to main(), so that if an application * is linking when the main() function is in a static library (.a) * we can be sure that main() actually gets linked in */ .type main,%function _start: /* 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 */ #if defined L_Scrt0 || defined L_Scrt1 call .L0 .L0: pop %edx addl $_GLOBAL_OFFSET_TABLE_+[.-.L0],%edx #endif #if (defined L_crt1 || defined L_Scrt1 || defined L_gcrt1 ) && defined __UCLIBC_CTOR_DTOR__ /* Push .init and .fini arguments to __uClibc_start_main() on the stack */ #ifdef L_Scrt1 pushl _fini@GOT(%edx) pushl _init@GOT(%edx) #else pushl $_fini pushl $_init #endif /* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */ pushl %eax /* Environment pointer */ pushl %ebx /* Argument pointer */ pushl %ecx /* And the argument count */ /* Ok, now run uClibc's main() -- shouldn't return */ #ifdef L_Scrt1 call *__uClibc_start_main@GOT(%edx) #else call __uClibc_start_main #endif #else /* Push envp, argc, and argc arguments to __uClibc_start_main() on the stack */ pushl %eax /* Environment pointer */ pushl %ebx /* Argument pointer */ pushl %ecx /* And the argument count */ #ifdef L_Scrt0 call *__uClibc_main@GOT(%edx) #else call __uClibc_main #endif #endif /* Crash if somehow `exit' returns anyways. */ hlt .size _start,.-_start .section ".data" .globl __data_start __data_start: .long 0 #if defined L_gcrt1 && defined __UCLIBC_PROFILING__ # include "./gmon-start.S" #endif