104 lines
3.4 KiB
ArmAsm
104 lines
3.4 KiB
ArmAsm
/*-
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* Copyright (c) 2013-2014 Robert N. M. Watson
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* All rights reserved.
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*
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* This software was developed by SRI International and the University of
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* Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
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* ("CTSRD"), as part of the DARPA CRASH research programme.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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.set mips64
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.set noreorder
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.set nobopt
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.set noat
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/*
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* Save arguments from the BERI firmware for use in C-land, and jump into
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* main. Assume that registers/stack/etc are sufficiently initialised to get
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* going. Notice that we use only temporaries while relocating, as we want to
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* retain argument registers to pass in to main().
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*
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* Note slightly surprising structure: boot2 is linked for a specific address,
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* but we may start running the code somewhere else (e.g., in DRAM as inserted
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* with JTAG, or in flash). The starting assembly is therefore PIC, but the
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* main body of the code is not PIC.
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*/
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.text
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.global prerelocate_start
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.ent prerelocate_start
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prerelocate_start:
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/*
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* Calculate the actual run-time, pre-relocated value of
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* 'start', which we will use as the source address for
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* memcpy(). Note that although a symbol is used here, this
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* should generate code for a short relative branch, leaving
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* the previous $pc in $ra.
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*/
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bal baltarget
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nop
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baltarget:
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dsub $t1, $ra, 8 /* Src. */
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/*
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* Relocate boot2 to DRAM where we can write back global
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* variable values; jump to it. Assume all values are 32-bit
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* aligned. Use an inline PIC version of memcpy()
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* pre-relocation; strong alignment assumptions.
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*/
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dla $t0, __boot2_base_vaddr__ /* Dst. */
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dla $t2, __boot_loader_len__ /* Len. */
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memcpy_loop:
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beq $t2, 0, memcopy_done
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nop
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lw $at, 0($t1)
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sw $at, 0($t0)
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daddiu $t0, 4
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daddiu $t1, 4
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daddi $t2, -4
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b memcpy_loop
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nop
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memcopy_done:
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/*
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* We can now jump into the relocated code, running from
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* cached DRAM rather than uncached flash. Note that a
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* relative branch instruction cannot be used.
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*/
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dla $at, relocated_start
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jr $at
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nop
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relocated_start:
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dla $at, start
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jr $at
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nop
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.end prerelocate_start
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