This is a note to let you know that I've just added the patch titled
MIPS: Add 'memory' clobber to csum_ipv6_magic() inline assembler
to the 5.4-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:
mips-add-memory-clobber-to-csum_ipv6_magic-inline-as.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4eda2b263a30ea2df68f14185e0e489250b3a42d
Author: Guenter Roeck <linux@xxxxxxxxxxxx>
Date: Sun Feb 11 08:08:37 2024 -0800
MIPS: Add 'memory' clobber to csum_ipv6_magic() inline assembler
[ Upstream commit d55347bfe4e66dce2e1e7501e5492f4af3e315f8 ]
After 'lib: checksum: Use aligned accesses for ip_fast_csum and
csum_ipv6_magic tests' was applied, the test_csum_ipv6_magic unit test
started failing for all mips platforms, both little and bit endian.
Oddly enough, adding debug code into test_csum_ipv6_magic() made the
problem disappear.
The gcc manual says:
"The "memory" clobber tells the compiler that the assembly code performs
memory reads or writes to items other than those listed in the input
and output operands (for example, accessing the memory pointed to by one
of the input parameters)
"
This is definitely the case for csum_ipv6_magic(). Indeed, adding the
'memory' clobber fixes the problem.
Cc: Charlie Jenkins <charlie@xxxxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Reviewed-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
Signed-off-by: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/mips/include/asm/checksum.h b/arch/mips/include/asm/checksum.h
index dcebaaf8c862..803f2a6f9960 100644
--- a/arch/mips/include/asm/checksum.h
+++ b/arch/mips/include/asm/checksum.h
@@ -276,7 +276,8 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
" .set pop"
: "=&r" (sum), "=&r" (tmp)
: "r" (saddr), "r" (daddr),
- "0" (htonl(len)), "r" (htonl(proto)), "r" (sum));
+ "0" (htonl(len)), "r" (htonl(proto)), "r" (sum)
+ : "memory");
return csum_fold(sum);
}
