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/*-
* 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.
*
* $FreeBSD$
*/
.text
.align 4
.globl .rtld_start
.type .rtld_start,@function
.rtld_start:
xorl %ebp,%ebp # Clear frame pointer for good form
movl %esp,%eax # Save initial stack pointer
movl %esp,%esi # Save initial stack pointer
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 %eax # Pass initial stack pointer to rtld
call _rtld@PLT # 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
/*
* 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@PLT # 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
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