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powerpc: Fix handling of strncmp with zero len

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Commit 0119536c, which added the assembly version of strncmp to
powerpc, mentions that it adds two instructions to the version from
boot/string.S to allow it to handle len=0. Unfortunately, it doesn't
always return 0 when that is the case. The length is passed in r5, but
the return value is passed back in r3. In certain cases, this will
happen to work. Otherwise it will pass back the address of the first
string as the return value.

This patch lifts the len <= 0 handling code from memcpy to handle that
case.

Reported by: Christian_Sellars@symantec.com
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
CC: <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Jeff Mahoney 2010-03-17 10:55:51 +00:00 committed by Benjamin Herrenschmidt
parent 6d1bdd2afb
commit 637a99022f
1 changed files with 3 additions and 1 deletions
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4
arch/powerpc/lib/string.S
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@ -71,7 +71,7 @@ _GLOBAL(strcmp)
_GLOBAL(strncmp)
PPC_LCMPI r5,0
beqlr
ble- 2f
mtctr r5
addi r5,r3,-1
addi r4,r4,-1
@ -82,6 +82,8 @@ _GLOBAL(strncmp)
beqlr 1
bdnzt eq,1b
blr
2: li r3,0
blr
_GLOBAL(strlen)
addi r4,r3,-1