| Message ID | 20241105160859.1459261-8-ardb+git@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Clean up and improve ARM/arm64 CRC-T10DIF code | expand |
On Tue, Nov 05, 2024 at 05:09:00PM +0100, Ard Biesheuvel wrote: > From: Ard Biesheuvel <ardb@kernel.org> > > I realized that the generic sequence implementing 64x64 polynomial > multiply using 8x8 PMULL instructions, which is used in the CRC-T10DIF > code to implement a fallback version for cores that lack the 64x64 PMULL > instruction, is not very efficient. > > The folding coefficients that are used when processing the bulk of the > data are only 16 bits wide, and so 3/4 of the partial results of all those > 8x8->16 bit multiplications do not contribute anything to the end result. > > This means we can use a much faster implementation, producing a speedup > of 3.3x on Cortex-A72 without Crypto Extensions (Raspberry Pi 4). > > The same logic can be ported to 32-bit ARM too, where it produces a > speedup of 6.6x compared with the generic C implementation on the same > platform. > > Changes since v1: > - fix bug introduced in refactoring > - add asm comments to explain the fallback algorithm > - type 'u8 *out' parameter as 'u8 out[16]' > - avoid asm code for 16 byte inputs (a higher threshold might be more > appropriate but 16 is nonsensical given that the folding routine > returns a 16 byte output) > > Ard Biesheuvel (6): > crypto: arm64/crct10dif - Remove obsolete chunking logic > crypto: arm64/crct10dif - Use faster 16x64 bit polynomial multiply > crypto: arm64/crct10dif - Remove remaining 64x64 PMULL fallback code > crypto: arm/crct10dif - Use existing mov_l macro instead of __adrl > crypto: arm/crct10dif - Macroify PMULL asm code > crypto: arm/crct10dif - Implement plain NEON variant > > arch/arm/crypto/crct10dif-ce-core.S | 249 ++++++++++----- > arch/arm/crypto/crct10dif-ce-glue.c | 55 +++- > arch/arm64/crypto/crct10dif-ce-core.S | 335 +++++++++----------- > arch/arm64/crypto/crct10dif-ce-glue.c | 48 ++- > 4 files changed, 376 insertions(+), 311 deletions(-) Reviewed-by: Eric Biggers <ebiggers@google.com> - Eric
From: Ard Biesheuvel <ardb@kernel.org> I realized that the generic sequence implementing 64x64 polynomial multiply using 8x8 PMULL instructions, which is used in the CRC-T10DIF code to implement a fallback version for cores that lack the 64x64 PMULL instruction, is not very efficient. The folding coefficients that are used when processing the bulk of the data are only 16 bits wide, and so 3/4 of the partial results of all those 8x8->16 bit multiplications do not contribute anything to the end result. This means we can use a much faster implementation, producing a speedup of 3.3x on Cortex-A72 without Crypto Extensions (Raspberry Pi 4). The same logic can be ported to 32-bit ARM too, where it produces a speedup of 6.6x compared with the generic C implementation on the same platform. Changes since v1: - fix bug introduced in refactoring - add asm comments to explain the fallback algorithm - type 'u8 *out' parameter as 'u8 out[16]' - avoid asm code for 16 byte inputs (a higher threshold might be more appropriate but 16 is nonsensical given that the folding routine returns a 16 byte output) Ard Biesheuvel (6): crypto: arm64/crct10dif - Remove obsolete chunking logic crypto: arm64/crct10dif - Use faster 16x64 bit polynomial multiply crypto: arm64/crct10dif - Remove remaining 64x64 PMULL fallback code crypto: arm/crct10dif - Use existing mov_l macro instead of __adrl crypto: arm/crct10dif - Macroify PMULL asm code crypto: arm/crct10dif - Implement plain NEON variant arch/arm/crypto/crct10dif-ce-core.S | 249 ++++++++++----- arch/arm/crypto/crct10dif-ce-glue.c | 55 +++- arch/arm64/crypto/crct10dif-ce-core.S | 335 +++++++++----------- arch/arm64/crypto/crct10dif-ce-glue.c | 48 ++- 4 files changed, 376 insertions(+), 311 deletions(-)