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authorWang Haitao <wang.haitao1@zte.com.cn>2013-08-22 19:32:38 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-04 10:56:22 -0800
commit1da42d7c5ff4dbee6b7c60cbcba9035422a7a1f8 (patch)
treec6d7cd5e13f0f3bdd720b7ea226fef7ce7c17d0c /include
parent017beeafb0bd8a13118b71d568ed0912b6bf9f69 (diff)
downloadlwn-1da42d7c5ff4dbee6b7c60cbcba9035422a7a1f8.tar.gz
lwn-1da42d7c5ff4dbee6b7c60cbcba9035422a7a1f8.zip
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.h4
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;