/*- * Copyright 1996-1998 John D. Polstra. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ .text .align 4 .globl .rtld_start .type .rtld_start,@function .rtld_start: .cfi_startproc .cfi_undefined %eip xorl %ebp,%ebp # Clear frame pointer for good form movl %esp,%esi # Save initial stack pointer pushl %ebp .cfi_def_cfa_offset 4 movl %esp,%ebp .cfi_offset %ebp,-4 .cfi_def_cfa_register %ebp andl $0xfffffff0,%esp # Align stack pointer subl $16,%esp # A place to store exit procedure addr movl %esp,%ebx # save address of exit proc movl %esp,%ecx # construct address of obj_main addl $4,%ecx subl $4,%esp # Keep stack aligned pushl %ecx # Pass address of obj_main pushl %ebx # Pass address of exit proc pushl %esi # Pass initial stack pointer to rtld call _rtld # Call rtld(sp); returns entry point addl $16,%esp # Remove arguments from stack popl %edx # Get exit procedure address movl %esi,%esp # Ignore obj_main /* * At this point, %eax contains the entry point of the main program, and * %edx contains a pointer to a termination function that should be * registered with atexit(). (crt1.o registers it.) */ .globl .rtld_goto_main .rtld_goto_main: # This symbol exists just to make debugging easier. jmp *%eax # Enter main program .cfi_endproc /* * Binder entry point. Control is transferred to here by code in the PLT. * On entry, there are two arguments on the stack. In ascending address * order, they are (1) "obj", a pointer to the calling object's Obj_Entry, * and (2) "reloff", the byte offset of the appropriate relocation entry * in the PLT relocation table. * * We are careful to preserve all registers, even the caller-save * registers. That is because this code may be invoked by low-level * assembly-language code that is not ABI-compliant. */ .align 4 .globl _rtld_bind_start .type _rtld_bind_start,@function _rtld_bind_start: pushf # Save eflags pushl %eax # Save %eax pushl %edx # Save %edx pushl %ecx # Save %ecx pushl 20(%esp) # Copy reloff argument pushl 20(%esp) # Copy obj argument call _rtld_bind # Transfer control to the binder /* Now %eax contains the entry point of the function being called. */ addl $8,%esp # Discard binder arguments movl %eax,20(%esp) # Store target over obj argument popl %ecx # Restore %ecx popl %edx # Restore %edx popl %eax # Restore %eax popf # Restore eflags leal 4(%esp),%esp # Discard reloff, do not change eflags ret # "Return" to target address .section .note.GNU-stack,"",%progbits
