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| author | Wang Haitao <wang.haitao1@zte.com.cn> | 2013-08-22 19:32:38 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-04 11:05:25 -0800 |
| commit | 7524987e3c505dd4e96c1eae5001e06c91d481e9 (patch) | |
| tree | cf18f774ad2c299e0441b52d8856fc9ea0c8cc55 /include | |
| parent | 0e2155bedf934f446edf64ffc3c21f09b61d6b4d (diff) | |
mtd: map: fixed bug in 64-bit systems
commit a4d62babf988fe5dfde24437fa135ef147bc7aa0 upstream.
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>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -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 4b02512e421..5f487d77641 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; |