freebsd-dev/stand/mips/beri/boot2/start.S
2017-11-14 23:02:19 +00:00

83 lines
2.6 KiB
ArmAsm

/*-
* Copyright (c) 2013-2014 Robert N. M. Watson
* All rights reserved.
*
* This software was developed by SRI International and the University of
* Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
* ("CTSRD"), as part of the DARPA CRASH research programme.
*
* 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*
* $FreeBSD$
*/
.set mips64
.set noreorder
.set nobopt
.set noat
/*
* Save arguments from the BERI firmware for use in C-land, and jump into
* main. Assume that registers/stack/etc are sufficiently initialised to get
* going. Notice that we use only temporaries while relocating, as we want to
* retain argument registers to pass in to main().
*
* Note slightly surprising structure: boot2 is linked for a specific address,
* but we may start running the code somewhere else (e.g., in DRAM as inserted
* with JTAG, or in flash). The starting assembly is therefore PIC, but the
* main body of the code is not PIC.
*/
.text
.global start
.ent start
start:
/*
* Zero BSS. Run from cached memory as this will speed up
* code execution noticeably. Assuming 64-bit alignment of
* everything here.
*/
dla $t0, __bss_start
dla $t1, __bss_end
bss_loop:
beq $t0, $t1, bss_done
nop
sd $zero, 0($t0)
daddiu $t0, 8
b bss_loop
nop
bss_done:
jal main
nop
/*
* Ideally we wouldn't get here, but just in case.
*/
loop:
b loop
nop
.end start