* [patch] tidy up return value of ip_fast_csum
@ 2006-11-09 0:29 Chen, Kenneth W
0 siblings, 0 replies; only message in thread
From: Chen, Kenneth W @ 2006-11-09 0:29 UTC (permalink / raw)
To: linux-ia64
While working on implementing csum_ipv6_magic, I noticed that current version of ip_fast_csum will potentially return bits above
"unsigned short" as 1. While no
harm is done right now because all call sites will chop off the upper bits when
it uses the return value. However, this is still dangerous and buggy. Here is
a patch to enforce that the function really returns unsigned short in the native
register format.
The fix is free as there are plenty open slot to add one more asm instruction.
Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
--- ./arch/ia64/lib/ip_fast_csum.S.orig 2006-11-08 17:09:36.000000000 -0800
+++ ./arch/ia64/lib/ip_fast_csum.S 2006-11-08 17:10:04.000000000 -0800
@@ -68,8 +68,9 @@ GLOBAL_ENTRY(ip_fast_csum)
zxt2 r20=r20
;;
add r20=ret0,r20
+ mov r9=0xffff
;;
- andcm ret0=-1,r20
+ andcm ret0=r9,r20
.restore sp // reset frame state
br.ret.sptk.many b0
;;
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2006-11-09 0:29 [patch] tidy up return value of ip_fast_csum Chen, Kenneth W
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