RE: [RFC][PATCH] ia64: fix csum_ipv6_magic()

[Yu, Fenghua]

>I was seeing "nf_ct_icmpv6: ICMPv6 checksum failed" errors on
>every ICMPv6 packet received. The packets did not pass the
>netfilter checksum verification but they did pass the standard
>verification later and got processed. This happenns with hardware
>checksumming turned off or with adapters that do not checksum
>ICMP packets (e.g. tg3). I tracked the problem down to the ia64
>version of csum_ipv6_magic() introduced by 007d77d0c5.  For some
>arguments, it gives differrent results than the generic version.
>
>The following patch fixes the problem for me. IA64 experts, can
>you please have a look?
>
>Thanks!
>
>
>[IA64] fix csum_ipv6_magic()
>
>The 32-bit parameters (len and csum) of csum_ipv6_magic() are passed in 64-
>bit
>registers in3 and in4. The high order 32 bits of the registers were never
>cleared, and garbage was sometimes calculated into the checksum.
>
>Fix this by clearing the high order 32 bits of the registers.
>
>Signed-off-by: Jiri Bohac <jbohac@xxxxxxx>
>
>diff --git a/arch/ia64/lib/ip_fast_csum.S b/arch/ia64/lib/ip_fast_csum.S
>index 1f86aeb..9a8d23f 100644
>--- a/arch/ia64/lib/ip_fast_csum.S
>+++ b/arch/ia64/lib/ip_fast_csum.S
>@@ -96,20 +96,22 @@ END(ip_fast_csum)
> GLOBAL_ENTRY(csum_ipv6_magic)
> 	ld4	r20=[in0],4
> 	ld4	r21=[in1],4
>-	dep	r15=in3,in2,32,16
>+	zxt4	in3=in3
> 	;;
> 	ld4	r22=[in0],4
> 	ld4	r23=[in1],4
>-	mux1	r15=r15,@rev
>+	dep	r15=in3,in2,32,16
> 	;;
> 	ld4	r24=[in0],4
> 	ld4	r25=[in1],4
>-	shr.u	r15=r15,16
>+	mux1	r15=r15,@rev
> 	add	r16=r20,r21
> 	add	r17=r22,r23
>+	zxt4	in4=in4
> 	;;
> 	ld4	r26=[in0],4
> 	ld4	r27=[in1],4
>+	shr.u	r15=r15,16
> 	add	r18=r24,r25
> 	add	r8=r16,r17
> 	;;

Looks good to me. Do you know the caller function for the failed csum_ipv6_magic()?

Thanks.

-Fenghua
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