From: Daniel Jacobowitz <dan@debian.org>
To: linux-mips@linux-mips.org
Cc: ralf@linux-mips.org
Subject: [PATCH] Fix TCP/UDP checksums on the Broadcom SB-1
Date: Mon, 19 Sep 2005 23:28:18 -0400 [thread overview]
Message-ID: <20050920032818.GA7199@nevyn.them.org> (raw)
The type of sum in csum_tcpudp_nofold is "unsigned int", so when we assign
to it in an asm() block, and we're running on a system with 64-bit
registers, it is vitally important that we sign extend it correctly before
returning to C. Otherwise the stray high bits will be preserved into
csum_fold, and on the SB-1 processor, 32-bit arithmetic on a non
sign-extended register will yield surprising results.
This caused incorrect checksums in some UDP packets for NFS root. The
problem was mild when using a 10.0.1.x IP address, but severe when
using 192.168.1.x.
Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com>
Index: linux/include/asm-mips/checksum.h
===================================================================
--- linux.orig/include/asm-mips/checksum.h 2005-09-19 21:00:48.000000000 -0400
+++ linux/include/asm-mips/checksum.h 2005-09-19 21:52:11.000000000 -0400
@@ -149,7 +149,7 @@ static inline unsigned int csum_tcpudp_n
" daddu %0, %4 \n"
" dsll32 $1, %0, 0 \n"
" daddu %0, $1 \n"
- " dsrl32 %0, %0, 0 \n"
+ " dsra32 %0, %0, 0 \n"
#endif
" .set pop"
: "=r" (sum)
--
Daniel Jacobowitz
CodeSourcery, LLC
next reply other threads:[~2005-09-20 3:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-20 3:28 Daniel Jacobowitz [this message]
2005-09-20 10:43 ` [PATCH] Fix TCP/UDP checksums on the Broadcom SB-1 Maciej W. Rozycki
2005-09-20 11:00 ` Matej Kupljen
2005-09-20 11:06 ` Ralf Baechle
2005-09-20 14:26 ` Michael Uhler
2005-09-20 14:26 ` Michael Uhler
2005-09-20 14:59 ` Ralf Baechle
2005-09-20 11:01 ` Ralf Baechle
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