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MIPS: Add 'memory' clobber to csum_ipv6_magic() inline assembler

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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@rivosinc.com>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Guenter Roeck 2024-02-11 08:08:37 -08:00 committed by Thomas Bogendoerfer
parent 841c351693
commit d55347bfe4
1 changed files with 2 additions and 1 deletions
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3
arch/mips/include/asm/checksum.h
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@ -241,7 +241,8 @@ 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);
}