The 'r4k_dma_cache_wback_inv' function will fail when the requested size equals 0 AND when the address is a multiple of the line size. I discovered this bug while using the National Semiconductor DP8381x series PCI ethernet driver. I have attached a test program showing the bug as well as a patch for comment. Okay to apply?
-Steve
/*
* Test program for faulty 'r4k_dma_cache_wback_inv' routine where
* calculated end address can be incorrect when the size = 0.
*
* Copyright (C) 2004 TimeSys Corp.
* S. James Hill (James.Hill@timesys.com)
* (sjhill@realitydiluted.com)
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* THIS SOFTWARE IS PROVIDED ``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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdio.h>
int main (void)
{
unsigned long addr, a, end;
unsigned int size, line_size;
/*
* Choose an arbitrary test start address and ending address
* (not the calculated end address).
*/
for (addr = 0x803e4000; addr < 0x803e8000; addr+=4)
{
/*
* We assume cache line sizes are always a multiple
* of 16 bytes.
*/
line_size = 16;
//line_size = 32;
{
/*
* We try all 4-byte aligned sizes up to
* the size of a page.
*/
for (size = 0; size < 4096; size+=4)
{
a = addr & ~(line_size - 1);
end = (addr + size - 1) & ~(line_size - 1);
if (end < a)
printf("FAIL: a=0x%08lx, end=0x%08lx,"
"line_size=%i, size=%i\n",
a, end, line_size, size);
}
}
}
return 0;
}
Index: c-r4k.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/mm/c-r4k.c,v
retrieving revision 1.3.2.67
diff -d -u -r1.3.2.67 c-r4k.c
--- c-r4k.c 5 Mar 2004 02:47:11 -0000 1.3.2.67
+++ c-r4k.c 15 Mar 2004 17:03:29 -0000
@@ -482,7 +482,7 @@
}
a = addr & ~(sc_lsize - 1);
- end = (addr + size - 1) & ~(sc_lsize - 1);
+ end = (addr + size + sc_lsize - 1) & ~(sc_lsize - 1);
while (1) {
flush_scache_line(a); /* Hit_Writeback_Inv_SD */
if (a == end)
@@ -504,7 +504,7 @@
R4600_HIT_CACHEOP_WAR_IMPL;
a = addr & ~(dc_lsize - 1);
- end = (addr + size - 1) & ~(dc_lsize - 1);
+ end = (addr + size + dc_lsize - 1) & ~(dc_lsize - 1);
while (1) {
flush_dcache_line(a); /* Hit_Writeback_Inv_D */
if (a == end)
@@ -529,7 +529,7 @@
}
a = addr & ~(sc_lsize - 1);
- end = (addr + size - 1) & ~(sc_lsize - 1);
+ end = (addr + size + sc_lsize - 1) & ~(sc_lsize - 1);
while (1) {
flush_scache_line(a); /* Hit_Writeback_Inv_SD */
if (a == end)
@@ -546,7 +546,7 @@
R4600_HIT_CACHEOP_WAR_IMPL;
a = addr & ~(dc_lsize - 1);
- end = (addr + size - 1) & ~(dc_lsize - 1);
+ end = (addr + size + dc_lsize - 1) & ~(dc_lsize - 1);
while (1) {
flush_dcache_line(a); /* Hit_Writeback_Inv_D */
if (a == end)
