This is a note to let you know that I've just added the patch titled
powerpc/64: Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: powerpc-64-fix-checksum-folding-in-csum_tcpudp_nofold-and-ip_fast_csum_nofold.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From b492f7e4e07a28e706db26cf4943bb0911435426 Mon Sep 17 00:00:00 2001
From: Paul Mackerras paulus@ozlabs.org Date: Thu, 3 Nov 2016 16:10:55 +1100 Subject: powerpc/64: Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold
From: Paul Mackerras paulus@ozlabs.org
commit b492f7e4e07a28e706db26cf4943bb0911435426 upstream.
These functions compute an IP checksum by computing a 64-bit sum and folding it to 32 bits (the "nofold" in their names refers to folding down to 16 bits). However, doing (u32) (s + (s >> 32)) is not sufficient to fold a 64-bit sum to 32 bits correctly. The addition can produce a carry out from bit 31, which needs to be added in to the sum to produce the correct result.
To fix this, we copy the from64to32() function from lib/checksum.c and use that.
Signed-off-by: Paul Mackerras paulus@ozlabs.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/include/asm/checksum.h | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
--- a/arch/powerpc/include/asm/checksum.h +++ b/arch/powerpc/include/asm/checksum.h @@ -53,17 +53,25 @@ static inline __sum16 csum_fold(__wsum s return (__force __sum16)(~((__force u32)sum + tmp) >> 16); }
+static inline u32 from64to32(u64 x) +{ + /* add up 32-bit and 32-bit for 32+c bit */ + x = (x & 0xffffffff) + (x >> 32); + /* add up carry.. */ + x = (x & 0xffffffff) + (x >> 32); + return (u32)x; +} + static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, __wsum sum) { #ifdef __powerpc64__ - unsigned long s = (__force u32)sum; + u64 s = (__force u32)sum;
s += (__force u32)saddr; s += (__force u32)daddr; s += proto + len; - s += (s >> 32); - return (__force __wsum) s; + return (__force __wsum) from64to32(s); #else __asm__("\n\ addc %0,%0,%1 \n\ @@ -123,8 +131,7 @@ static inline __wsum ip_fast_csum_nofold
for (i = 0; i < ihl - 1; i++, ptr++) s += *ptr; - s += (s >> 32); - return (__force __wsum)s; + return (__force __wsum)from64to32(s); #else __wsum sum, tmp;
Patches currently in stable-queue which might be from paulus@ozlabs.org are
queue-4.9/powerpc-64-fix-checksum-folding-in-csum_tcpudp_nofold-and-ip_fast_csum_nofold.patch queue-4.9/powerpc-64-fix-checksum-folding-in-csum_add.patch queue-4.9/powerpc-64-invalidate-process-table-caching-after-setting-process-table.patch