[RFC PATCH] crypto: arm64/speck - add NEON-accelerated implementation of Speck-XTS
Dave Martin
Dave.Martin at arm.com
Tue Mar 6 05:44:43 PST 2018
On Tue, Mar 06, 2018 at 12:47:45PM +0000, Ard Biesheuvel wrote:
> On 6 March 2018 at 12:35, Dave Martin <Dave.Martin at arm.com> wrote:
> > On Mon, Mar 05, 2018 at 11:17:07AM -0800, Eric Biggers wrote:
> >> Add a NEON-accelerated implementation of Speck128-XTS and Speck64-XTS
> >> for ARM64. This is ported from the 32-bit version. It may be useful on
> >> devices with 64-bit ARM CPUs that don't have the Cryptography
> >> Extensions, so cannot do AES efficiently -- e.g. the Cortex-A53
> >> processor on the Raspberry Pi 3.
> >>
> >> It generally works the same way as the 32-bit version, but there are
> >> some slight differences due to the different instructions, registers,
> >> and syntax available in ARM64 vs. in ARM32. For example, in the 64-bit
> >> version there are enough registers to hold the XTS tweaks for each
> >> 128-byte chunk, so they don't need to be saved on the stack.
> >>
> >> Benchmarks on a Raspberry Pi 3 running a 64-bit kernel:
> >>
> >> Algorithm Encryption Decryption
> >> --------- ---------- ----------
> >> Speck64/128-XTS (NEON) 92.2 MB/s 92.2 MB/s
> >> Speck128/256-XTS (NEON) 75.0 MB/s 75.0 MB/s
> >> Speck128/256-XTS (generic) 47.4 MB/s 35.6 MB/s
> >> AES-128-XTS (NEON bit-sliced) 33.4 MB/s 29.6 MB/s
> >> AES-256-XTS (NEON bit-sliced) 24.6 MB/s 21.7 MB/s
> >>
> >> The code performs well on higher-end ARM64 processors as well, though
> >> such processors tend to have the Crypto Extensions which make AES
> >> preferred. For example, here are the same benchmarks run on a HiKey960
> >> (with CPU affinity set for the A73 cores), with the Crypto Extensions
> >> implementation of AES-256-XTS added:
> >>
> >> Algorithm Encryption Decryption
> >> --------- ----------- -----------
> >> AES-256-XTS (Crypto Extensions) 1273.3 MB/s 1274.7 MB/s
> >> Speck64/128-XTS (NEON) 359.8 MB/s 348.0 MB/s
> >> Speck128/256-XTS (NEON) 292.5 MB/s 286.1 MB/s
> >> Speck128/256-XTS (generic) 186.3 MB/s 181.8 MB/s
> >> AES-128-XTS (NEON bit-sliced) 142.0 MB/s 124.3 MB/s
> >> AES-256-XTS (NEON bit-sliced) 104.7 MB/s 91.1 MB/s
> >>
> >> Signed-off-by: Eric Biggers <ebiggers at google.com>
> >> ---
> >> arch/arm64/crypto/Kconfig | 6 +
> >> arch/arm64/crypto/Makefile | 3 +
> >> arch/arm64/crypto/speck-neon-core.S | 352 ++++++++++++++++++++++++++++
> >> arch/arm64/crypto/speck-neon-glue.c | 282 ++++++++++++++++++++++
> >> 4 files changed, 643 insertions(+)
> >> create mode 100644 arch/arm64/crypto/speck-neon-core.S
> >> create mode 100644 arch/arm64/crypto/speck-neon-glue.c
> >>
> >> diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
> >> index 285c36c7b408..cb5a243110c4 100644
> >> --- a/arch/arm64/crypto/Kconfig
> >> +++ b/arch/arm64/crypto/Kconfig
> >> @@ -113,4 +113,10 @@ config CRYPTO_AES_ARM64_BS
> >> select CRYPTO_AES_ARM64
> >> select CRYPTO_SIMD
> >>
> >> +config CRYPTO_SPECK_NEON
> >> + tristate "NEON accelerated Speck cipher algorithms"
> >> + depends on KERNEL_MODE_NEON
> >> + select CRYPTO_BLKCIPHER
> >> + select CRYPTO_SPECK
> >> +
> >> endif
> >> diff --git a/arch/arm64/crypto/Makefile b/arch/arm64/crypto/Makefile
> >> index cee9b8d9830b..d94ebd15a859 100644
> >> --- a/arch/arm64/crypto/Makefile
> >> +++ b/arch/arm64/crypto/Makefile
> >> @@ -53,6 +53,9 @@ sha512-arm64-y := sha512-glue.o sha512-core.o
> >> obj-$(CONFIG_CRYPTO_CHACHA20_NEON) += chacha20-neon.o
> >> chacha20-neon-y := chacha20-neon-core.o chacha20-neon-glue.o
> >>
> >> +obj-$(CONFIG_CRYPTO_SPECK_NEON) += speck-neon.o
> >> +speck-neon-y := speck-neon-core.o speck-neon-glue.o
> >> +
> >> obj-$(CONFIG_CRYPTO_AES_ARM64) += aes-arm64.o
> >> aes-arm64-y := aes-cipher-core.o aes-cipher-glue.o
> >>
> >> diff --git a/arch/arm64/crypto/speck-neon-core.S b/arch/arm64/crypto/speck-neon-core.S
> >> new file mode 100644
> >> index 000000000000..b14463438b09
> >> --- /dev/null
> >> +++ b/arch/arm64/crypto/speck-neon-core.S
> >> @@ -0,0 +1,352 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * ARM64 NEON-accelerated implementation of Speck128-XTS and Speck64-XTS
> >> + *
> >> + * Copyright (c) 2018 Google, Inc
> >> + *
> >> + * Author: Eric Biggers <ebiggers at google.com>
> >> + */
> >> +
> >> +#include <linux/linkage.h>
> >> +
> >> + .text
> >> +
> >> + // arguments
> >> + ROUND_KEYS .req x0 // const {u64,u32} *round_keys
> >> + NROUNDS .req w1 // int nrounds
> >> + NROUNDS_X .req x1
> >> + DST .req x2 // void *dst
> >> + SRC .req x3 // const void *src
> >> + NBYTES .req w4 // unsigned int nbytes
> >> + TWEAK .req x5 // void *tweak
> >> +
> >> + // registers which hold the data being encrypted/decrypted
> >> + // (underscores avoid a naming collision with ARM64 registers x0-x3)
> >> + X_0 .req v0
> >> + Y_0 .req v1
> >> + X_1 .req v2
> >> + Y_1 .req v3
> >> + X_2 .req v4
> >> + Y_2 .req v5
> >> + X_3 .req v6
> >> + Y_3 .req v7
> >> +
> >> + // the round key, duplicated in all lanes
> >> + ROUND_KEY .req v8
> >> +
> >> + // index vector for tbl-based 8-bit rotates
> >> + ROTATE_TABLE .req v9
> >> + ROTATE_TABLE_Q .req q9
> >> +
> >> + // temporary registers
> >> + TMP0 .req v10
> >> + TMP1 .req v11
> >> + TMP2 .req v12
> >> + TMP3 .req v13
> >> +
> >> + // multiplication table for updating XTS tweaks
> >> + GFMUL_TABLE .req v14
> >> + GFMUL_TABLE_Q .req q14
> >> +
> >> + // next XTS tweak value(s)
> >> + TWEAKV_NEXT .req v15
> >> +
> >> + // XTS tweaks for the blocks currently being encrypted/decrypted
> >> + TWEAKV0 .req v16
> >> + TWEAKV1 .req v17
> >> + TWEAKV2 .req v18
> >> + TWEAKV3 .req v19
> >> + TWEAKV4 .req v20
> >> + TWEAKV5 .req v21
> >> + TWEAKV6 .req v22
> >> + TWEAKV7 .req v23
> >> +
> >> + .align 4
> >> +.Lror64_8_table:
> >> + .octa 0x080f0e0d0c0b0a090007060504030201
> >> +.Lror32_8_table:
> >> + .octa 0x0c0f0e0d080b0a090407060500030201
> >> +.Lrol64_8_table:
> >> + .octa 0x0e0d0c0b0a09080f0605040302010007
> >> +.Lrol32_8_table:
> >> + .octa 0x0e0d0c0f0a09080b0605040702010003
> >> +.Lgf128mul_table:
> >> + .octa 0x00000000000000870000000000000001
> >> +.Lgf64mul_table:
> >> + .octa 0x0000000000000000000000002d361b00
> >
> > Won't this put the data in the image in an endianness-dependent layout?
> > Alternatively, if this doesn't matter, then why doesn't it matter?
> >
> > (I don't claim to understand the code fully here...)
> >
>
> Since these constants get loaded using 'ldr q#, .Lxxxx' instructions,
> this arrangement is actually endian agnostic.
Ah, yes -- that seems correct.
> ...
> >> +static int __init speck_neon_module_init(void)
> >> +{
> >> + if (!(elf_hwcap & HWCAP_ASIMD))
> >> + return -ENODEV;
> >> + return crypto_register_skciphers(speck_algs, ARRAY_SIZE(speck_algs));
> >
> > I haven't tried to understand everything here, but the kernel-mode NEON
> > integration looks OK to me.
> >
>
> I agree that the conditional use of the NEON looks fine here. The RT
> folks will frown at handling all input inside a single
> kernel_mode_neon_begin/_end pair, but we can fix that later once my
> changes for yielding the NEON get merged (which may take a while)
OK
Cheers
---Dave
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