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[/] [amber/] [trunk/] [hw/] [tests/] [cache_swap_bug.S] - Rev 66
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/*****************************************************************
// //
// Amber 2 Core Cache Test //
// //
// This file is part of the Amber project //
// http://www.opencores.org/project,amber //
// //
// Description //
// Tests the interaction between a swap instruction //
// and the cache. //
// //
// Author(s): //
// - Conor Santifort, csantifort.amber@gmail.com //
// //
//////////////////////////////////////////////////////////////////
// //
// Copyright (C) 2010 Authors and OPENCORES.ORG //
// //
// This source file may be used and distributed without //
// restriction provided that this copyright statement is not //
// removed from the file and that any derivative work contains //
// the original copyright notice and the associated disclaimer. //
// //
// This source file is free software; you can redistribute it //
// and/or modify it under the terms of the GNU Lesser General //
// Public License as published by the Free Software Foundation; //
// either version 2.1 of the License, or (at your option) any //
// later version. //
// //
// This source is distributed in the hope that it will be //
// useful, but WITHOUT ANY WARRANTY; without even the implied //
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //
// PURPOSE. See the GNU Lesser General Public License for more //
// details. //
// //
// You should have received a copy of the GNU Lesser General //
// Public License along with this source; if not, download it //
// from http://www.opencores.org/lgpl.shtml //
// //
*****************************************************************/
/*
Bug is caused by very subtle timing interactions in the Cache
It does not detect a hit, which it should, on the read phase of the swap
operation. It doesnt detect the hit because it is still completing
a fill started by the memory request to load an instructuion
at swap instruction + 8.
This only occurs when the swap target address is in the cache
but the cache instruction address is not, and the instruction
address the third of a group of 4 instruction words.
Test copies sequence to another bit of memory and runs it.
Repeats this a few times moving the sequence to slightly
different memory locations each time
*/
#include "amber_registers.h"
.section .text
.globl main
main:
@ ------------------------------------------
@ Copy code
@ ------------------------------------------
@ Copy code sequence to another area in memory
mov r13, #4
big_loop:
ldr r9, Loc1
add r9, r9, r13
mov r11, r9
ldr r8, Adrseq
ldr r10, Adrseqend
copy:
ldmia r8!, {r0-r7}
stmia r11!, {r0-r7}
cmp r8, r10
blt copy
@ ------------------------------------------
@ Enable and clear cache
@ ------------------------------------------
@ Enable the cache
mov r0, #0xffffffff
mcr 15, 0, r0, cr3, cr0, 0 @ cacheable area
mov r0, #1
mcr 15, 0, r0, cr2, cr0, 0 @ cache enable
nop
nop
@ flush the cache
mcr 15, 0, r0, cr1, cr0, 0
nop
nop
@ jump to special sequence
@ want to return to the instruction immediately after mov pc, r9
mov lr, pc
mov pc, r9
return:
ldr r3, [r5]
cmp r3, #0
movne r10, #10
bne testfail
cmp r13, #40
beq testpass
add r13, r13, #4
mov r0, r13
b big_loop
@ ------------------------------------------
@ ------------------------------------------
@ puts swap address into cache
@ move 0x7ff32c0 into r5
seq: mov r5, #0x000000c0
orr r5, r5, #0x00003200
orr r5, r5, #0x00ff0000
orr r5, r5, #0x07000000
ldr r8, [r5]
mov ip, #0
mov r2, #1
str r2, [r5]
nop
nop
nop
nop
@ ------------------------------------------
@ busybox code
@ ------------------------------------------
str r2, [r5, #4]
nop
nop
nop
nop
str ip, [r5, #4]
nop
nop
nop
nop
nop
nop
str ip, [r5, #8]
swp r3, ip, [r5]
nop
nop
nop
nop
ldr r3, [r5, #8]
nop
nop
nop
nop
mov pc, lr
nop
nop
nop
seqend: nop
@ ------------------------------------------
@ ------------------------------------------
testfail:
ldr r11, AdrTestStatus
str r10, [r11]
b testfail
testpass:
ldr r11, AdrTestStatus
mov r10, #17
str r10, [r11]
b testpass
Loc1: .word 0x200
Adrseq: .word seq
Adrseqend: .word seqend
/* Write 17 to this address to generate a Test Passed message */
AdrTestStatus: .word ADR_AMBER_TEST_STATUS
/* ========================================================================= */
/* ========================================================================= */
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