diff options
| author | Wang Haitao <wang.haitao1@zte.com.cn> | 2013-08-22 19:32:38 +0800 |
|---|---|---|
| committer | Brian Norris <computersforpeace@gmail.com> | 2013-11-06 23:32:59 -0800 |
| commit | a4d62babf988fe5dfde24437fa135ef147bc7aa0 (patch) | |
| tree | 6f34c5f7eaafcb6d76273845ebfaeb88bc377f20 | |
| parent | f83c3838b9146b891d0405d3a83660e8f6aed02f (diff) | |
mtd: map: fixed bug in 64-bit systems
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
| -rw-r--r-- | include/linux/mtd/map.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/mtd/map.h b/include/linux/mtd/map.h index 4b02512e421c..5f487d776411 100644 --- a/include/linux/mtd/map.h +++ b/include/linux/mtd/map.h @@ -365,7 +365,7 @@ 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; @@ -384,7 +384,7 @@ 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; |