This is a note to let you know that I've just added the patch titled
parisc: Strip upper 32 bit of sum in csum_ipv6_magic for 64-bit builds
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
parisc-strip-upper-32-bit-of-sum-in-csum_ipv6_magic-.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bea02ef5fdaa91218a8b2fe20159eb3944ea2464
Author: Guenter Roeck <linux@xxxxxxxxxxxx>
Date: Tue Feb 27 12:33:51 2024 -0800
parisc: Strip upper 32 bit of sum in csum_ipv6_magic for 64-bit builds
[ Upstream commit 0568b6f0d863643db2edcc7be31165740c89fa82 ]
IPv6 checksum tests with unaligned addresses on 64-bit builds result
in unexpected failures.
Expected expected == csum_result, but
expected == 46591 (0xb5ff)
csum_result == 46381 (0xb52d)
with alignment offset 1
Oddly enough, the problem disappeared after adding test code into
the beginning of csum_ipv6_magic().
As it turns out, the 'sum' parameter of csum_ipv6_magic() is declared as
__wsum, which is a 32-bit variable. However, it is treated as 64-bit
variable in the 64-bit assembler code. Tests showed that the upper 32 bit
of the register used to pass the variable are _not_ cleared when entering
the function. This can result in checksum calculation errors.
Clearing the upper 32 bit of 'sum' as first operation in the assembler
code fixes the problem.
Acked-by: Helge Deller <deller@xxxxxx>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/parisc/include/asm/checksum.h b/arch/parisc/include/asm/checksum.h
index c949aa20fa162..2aceebcd695c8 100644
--- a/arch/parisc/include/asm/checksum.h
+++ b/arch/parisc/include/asm/checksum.h
@@ -126,6 +126,7 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
** Try to keep 4 registers with "live" values ahead of the ALU.
*/
+" depdi 0, 31, 32, %0\n"/* clear upper half of incoming checksum */
" ldd,ma 8(%1), %4\n" /* get 1st saddr word */
" ldd,ma 8(%2), %5\n" /* get 1st daddr word */
" add %4, %0, %0\n"
