@@ -342,7 +342,7 @@ static inline map_word map_word_load_partial(struct map_info *map, map_word orig
bitpos = (map_bankwidth(map)-1-i)*8;
#endif
orig.x[0] &= ~(0xff << bitpos);
- orig.x[0] |= buf[i-start] << bitpos;
+ orig.x[0] |= (unsigned long)buf[i-start] << bitpos;
}
}
return orig;
@@ -361,7 +361,7 @@ static inline map_word map_word_ff(struct map_info *map)
if (map_bankwidth(map) < MAP_FF_LIMIT) {
int bw = 8 * map_bankwidth(map);
- r.x[0] = (1 << bw) - 1;
+ r.x[0] = (1UL << bw) - 1;
} else {
for (i=0; i<map_words(map); i++)
r.x[i] = ~0UL;
Hardware： CPU：XLP832,the 64-bit OS NOR Flash:S29GL128S 128M Software: Kernel:2.6.32.41 Filesystem:JFFS2 When writing files, errors appear: Write len 182 but return retlen 180 Write of 182 bytes at 0x072c815c failed. returned -5, retlen 180 Write len 186 but return retlen 184 Write of 186 bytes at 0x072caff4 failed. returned -5, retlen 184 These errors exist only in 64-bit systems,not in 32-bit systems. After analysis, we found that the left shift operation is wrong in map_word_load_partial. For instance： unsigned char buf[3] ={0x9e,0x3a,0xea}; map_bankwidth(map) is 4; for (i=0; i < 3; i++) { int bitpos; bitpos = (map_bankwidth(map)-1-i)*8; orig.x[0] &= ~(0xff << bitpos); orig.x[0] |= buf[i] << bitpos; } The value of orig.x[0] is expected to be 0x9e3aeaff, but in this situation(64-bit System) we'll get the wrong value of 0xffffffff9e3aeaff due to the 64-bit sign extension: buf[i] is defined as "unsigned char" and the left-shift operation will convert it to the type of "signed int", so when left-shift buf[i] by 24 bits, the final result will get the wrong value: 0xffffffff9e3aeaff. If the left-shift bits are less than 24, then sign extension will not occur. Whereas the bankwidth of the nor flash we used is 4, therefore this BUG emerges. Signed-off-by:Pang Xunlei <pang.xunlei@zte.com.cn> Signed-off-by: Zhang Yi <zhang.yi20@zte.com.cn> Signed-off-by:Lu Zhongjun <lu.zhongjun@zte.com.cn> Brian Norris <computersforpeace@gmail.com> 2013-08-21 16:57 To Wang Haitao <wang.haitao1@zte.com.cn> cc linux-mtd@lists.infradead.org, artem.bityutskiy@linux.intel.com, dwmw2@infradead.org Subject Re: [PATCH]mtd: map: fixed bug in 64-bit systems Hi Wang, Can you please resend this patch with a few fixups? The description below is good, but please wrap it to ~70 characters. It is hard to read. Also, you need to test your patch with scripts/checkpatch.pl both before and after you email it -- all your whitespace is mangled (i.e., you use spaces where there should be tabs). See the kernel documentation: Documentation/SubmittingPatches Documentation/email-clients.txt On Wed, Aug 07, 2013 at 03:34:20PM +0800, Wang Haitao wrote: > Hardware： > CPU：XLP832,the 64-bit OS > NOR Flash:S29GL128S 128M > Software: > Kernel:2.6.32.41 > Filesystem:JFFS2 > > When writing files, errors appear: > Write len 182 but return retlen 180 > Write of 182 bytes at 0x072c815c failed. returned -5, retlen 180 > Write len 186 but return retlen 184 > Write of 186 bytes at 0x072caff4 failed. returned -5, retlen 184 > These errors exist only in 64-bit systems,not in 32-bit systems. After analysis, we found that the left shift operation is wrong in map_word_load_partial. For instance： > unsigned char buf[3] ={0x9e,0x3a,0xea}; > map_bankwidth(map) is 4; > > for (i=0; i < 3; i++) { > int bitpos; > bitpos = (map_bankwidth(map)-1-i)*8; > orig.x[0] &= ~(0xff << bitpos); > orig.x[0] |= buf[i] << bitpos; > } > > The value of orig.x[0] is expected to be 0x9e3aeaff, but in this situation(64-bit System) we'll get the wrong value of 0xffffffff9e3aeaff due to the 64-bit sign extension: > buf[i] is defined as "unsigned char" and the left-shift operation will convert it to the type of "signed int", so when left-shift buf[i] by 24 bits, the final result will get the wrong value: 0xffffffff9e3aeaff. > > If the left-shift bits are less than 24, then sign extension will not occur. Whereas the bankwidth of the nor flash we used is 4, therefore this BUG emerges. > > Signed-off-by:Pang Xunlei <pang.xunlei@zte.com.cn> > Signed-off-by: Zhang Yi <zhang.yi20@zte.com.cn> > Signed-off-by:Lu Zhongjun <lu.zhongjun@zte.com.cn> > Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn> > Tested-by: Ma Chenggong <ma.chenggong@zte.com.cn> [...] Thanks, Brian