From 80dca4734b3561be59879b02bce359b6f661e921 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Sun, 28 Sep 2014 22:23:59 +0200 Subject: crypto: aesni - fix counter overflow handling in "by8" variant The "by8" CTR AVX implementation fails to propperly handle counter overflows. That was the reason it got disabled in commit 7da4b29d496b ("crypto: aesni - disable "by8" AVX CTR optimization"). Fix the overflow handling by incrementing the counter block as a double quad word, i.e. a 128 bit, and testing for overflows afterwards. We need to use VPTEST to do so as VPADD* does not set the flags itself and silently drops the carry bit. As this change adds branches to the hot path, minor performance regressions might be a side effect. But, OTOH, we now have a conforming implementation -- the preferable goal. A tcrypt test on a SandyBridge system (i7-2620M) showed almost identical numbers for the old and this version with differences within the noise range. A dm-crypt test with the fixed version gave even slightly better results for this version. So the performance impact might not be as big as expected. Tested-by: Romain Francoise Signed-off-by: Mathias Krause Cc: Chandramouli Narayanan Signed-off-by: Herbert Xu --- arch/x86/crypto/aes_ctrby8_avx-x86_64.S | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) (limited to 'arch/x86/crypto/aes_ctrby8_avx-x86_64.S') diff --git a/arch/x86/crypto/aes_ctrby8_avx-x86_64.S b/arch/x86/crypto/aes_ctrby8_avx-x86_64.S index f091f122ed24..a029bc744244 100644 --- a/arch/x86/crypto/aes_ctrby8_avx-x86_64.S +++ b/arch/x86/crypto/aes_ctrby8_avx-x86_64.S @@ -108,6 +108,10 @@ byteswap_const: .octa 0x000102030405060708090A0B0C0D0E0F +ddq_low_msk: + .octa 0x0000000000000000FFFFFFFFFFFFFFFF +ddq_high_add_1: + .octa 0x00000000000000010000000000000000 ddq_add_1: .octa 0x00000000000000000000000000000001 ddq_add_2: @@ -169,7 +173,12 @@ ddq_add_8: .rept (by - 1) club DDQ_DATA, i club XDATA, i - vpaddd var_ddq_add(%rip), xcounter, var_xdata + vpaddq var_ddq_add(%rip), xcounter, var_xdata + vptest ddq_low_msk(%rip), var_xdata + jnz 1f + vpaddq ddq_high_add_1(%rip), var_xdata, var_xdata + vpaddq ddq_high_add_1(%rip), xcounter, xcounter + 1: vpshufb xbyteswap, var_xdata, var_xdata .set i, (i +1) .endr @@ -178,7 +187,11 @@ ddq_add_8: vpxor xkey0, xdata0, xdata0 club DDQ_DATA, by - vpaddd var_ddq_add(%rip), xcounter, xcounter + vpaddq var_ddq_add(%rip), xcounter, xcounter + vptest ddq_low_msk(%rip), xcounter + jnz 1f + vpaddq ddq_high_add_1(%rip), xcounter, xcounter + 1: .set i, 1 .rept (by - 1) -- cgit v1.2.3-59-g8ed1b