ab41713c70
A branch instruction in a branch delay slot confuses the execution pipeline and causes an exception. bootblock.S was written 'by hand', has a branch instruction in branch delay slot and includes '.set noreorder' directive, which causes it to crash when trying to branch to main(). Adding a nop instruction fixes the problem. Also adding a nop after the last branch in the file just in case main() returns and the object linked next starts with a branch. BUG=chrome-os-partner:31438 TEST=Running on the simulator can reach main() now Change-Id: I0882b2eb5ce426f5a311018ffbb6f37a2ca64d98 Signed-off-by: Vadim Bendebury <vbendeb@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/221421 Reviewed-by: Aaron Durbin <adurbin@chromium.org>
48 lines
1.3 KiB
ArmAsm
48 lines
1.3 KiB
ArmAsm
/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2014 Imagination Technologies
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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.set noreorder /* Prevent assembler from "optimizing" this code. */
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.section ".text._start", "ax", %progbits
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.globl _start
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_start:
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/* Set the stack pointer */
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la $sp, _estack
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/*
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* Initialise the stack to a known value, used later to check for
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* overflow.
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*/
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la $t0, _stack
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addi $t1, $sp, -4
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li $t2, 0xdeadbeef
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1: sw $t2, 0($t0)
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bne $t0, $t1, 1b
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addi $t0, $t0, 4
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/* Run main */
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b main
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/*
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* Should never return from main. Make sure there is no branch in the
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* branch delay slot.
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*/
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2: nop
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b 2b
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nop /* Make sure there is no branch after this either. */
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