5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Guenter Roeck linux@roeck-us.net
[ Upstream commit a2abae8f0b638c31bb9799d9dd847306e0d005bd ]
IP checksum unit tests report the following error when run on hppa/hppa64.
# test_ip_fast_csum: ASSERTION FAILED at lib/checksum_kunit.c:463 Expected ( u64)csum_result == ( u64)expected, but ( u64)csum_result == 33754 (0x83da) ( u64)expected == 10946 (0x2ac2) not ok 4 test_ip_fast_csum
0x83da is the expected result if the IP header length is 20 bytes. 0x2ac2 is the expected result if the IP header length is 24 bytes. The test fails with an IP header length of 24 bytes. It appears that ip_fast_csum() always returns the checksum for a 20-byte header, no matter how long the header actually is.
Code analysis shows a suspicious assembler sequence in ip_fast_csum().
" addc %0, %3, %0\n" "1: ldws,ma 4(%1), %3\n" " addib,< 0, %2, 1b\n" <---
While my understanding of HPPA assembler is limited, it does not seem to make much sense to subtract 0 from a register and to expect the result to ever be negative. Subtracting 1 from the length parameter makes more sense. On top of that, the operation should be repeated if and only if the result is still > 0, so change the suspicious instruction to " addib,> -1, %2, 1b\n"
The IP checksum unit test passes after this change.
Cc: Palmer Dabbelt palmer@rivosinc.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Guenter Roeck linux@roeck-us.net Tested-by: Charlie Jenkins charlie@rivosinc.com Reviewed-by: Charlie Jenkins charlie@rivosinc.com Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Sasha Levin sashal@kernel.org --- arch/parisc/include/asm/checksum.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/parisc/include/asm/checksum.h b/arch/parisc/include/asm/checksum.h index c1c22819a04d1..7efcd901b9656 100644 --- a/arch/parisc/include/asm/checksum.h +++ b/arch/parisc/include/asm/checksum.h @@ -55,7 +55,7 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) " addc %0, %5, %0\n" " addc %0, %3, %0\n" "1: ldws,ma 4(%1), %3\n" -" addib,< 0, %2, 1b\n" +" addib,> -1, %2, 1b\n" " addc %0, %3, %0\n" "\n" " extru %0, 31, 16, %4\n"