/*	$OpenBSD: ldasm.S,v 1.4 2002/05/24 04:17:01 deraadt Exp $ */

/*
 * Copyright (c) 1999 Dale Rahn
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed under OpenBSD by
 *	Dale Rahn.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * 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.
 *
 */

/*
 * #ifdef blrl_never_causes_illegal_access
 * background for the else of this define
 * On the machine this code is being written, on a large portion
 * of the tims this code is executed the blrl instruct causes an
 * illegal instruction, hopefully by touching the page with a load
 * will prevent the execute access from faulting.
 */

#define AUX_entry 9

#include <machine/asm.h>

ENTRY(_dl_start)
	mr	19, 1
	stwu	1, (-16 -((AUX_entry+3)*4))(1)	# Some space.

	mflr	27		/* save off old link register */
	stw	27, 4(19)	/* save in normal location */

	# squirrel away the arguments for main
	mr 20, 3	#argc
	mr 21, 4	#argv
	mr 22, 5	#envp
	mr 23, 6	# ???

	.local	.L___offset_sym
	.type .L___offset_sym,@function
	bl	1f
.L___offset_sym:
	# this instruction never gets executed but can be used
	# to find the virtual address where the page is loaded.
	bl _GLOBAL_OFFSET_TABLE_@local-4
	bl _DYNAMIC@local
1:
	mflr	5		# this stores where we are (+4)
	lwz	18, 0(5)	# load the instruction at offset_sym
				# it contains an offset to the location
				# of the GOT.

	rlwinm 18,18,0,8,30	# mask off the offset portion of the instr.

	/*
	 * these adds effectively calculates the value the
	 * bl _GLOBAL_OFFSET_TABLE_@local-4
	 * operation that would be below would calulate.
	 */
	add	28, 18, 5

	li	0, 0
	dcbf	5, 18
	sync
	isync
	icbi	5, 18		# make certain that the got table addr is
				# not in the icache

	sync
	isync

	addi	28, 28, 4
	mr	29, 28

	lwz	30, 0(28)	# this loads the first entry of the GOT
				# thus forcing it to be paged in when
				# we jump to it below.


	# calculate where we want to be (via the got)
	bl _GLOBAL_OFFSET_TABLE_@local-4
	mflr 28


	lwz	4, .L___offset_sym@got(28)
	mr	6, 4		# make copy of register for debugging

	/* This cheats and calculates the address of _DYNAMIC
	 * the same way that the GLOBAL_OFFSET_TABLE was calcuated
	 */
	lwz	18, 4(5)
	rlwinm 18,18,0,8,30	# mask off the offset portion of the instr.
	add	8, 18, 5	# address of _DYNAMIC (arg6 for _dl_boot)
	addi	18, 8, 4	# correction.

	sub	4, 5, 4		# calculate offset (arg1 for _dl_boot)
	mr	17, 4


	subi	3, 21, 4	# Get stack pointer (arg0 for _dl_boot).
	mr	4, 17		# loff
	mr	5, 18		# dynamicp
	addi	6, 1, 8		# dl_data

	bl	_dl_boot_bind@local

	mr	3, 21		# argv
	mr	4, 22		# envp
	mr	5, 17		# loff
	mr	6, 18		# dynamicp
	addi	7, 1, 8		# dl_data

	bl	_dl_boot@local

	mtctr 3			# put return value into ctr to execute

	# get back the squirreled away the arguments for main
	mr 3, 20
	mr 4, 21
	mr 5, 22
	mr 6, 23


	mtlr 27
	lwz	1, 0(1)		# Restore stack pointer.
	bctr			# Go execute the 'real' program.

	.globl	_dl_rt_resolve
	.data
_dl_rt_resolve:
	.long	0