Re: [RFC PATCH v2 10/12] crypto: arm/nhpoly1305 - add NEON-accelerated NHPoly1305

From: Ard Biesheuvel
Date: Sat Oct 20 2018 - 00:13:04 EST

On 16 October 2018 at 01:54, Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> Add an ARM NEON implementation of NHPoly1305, an Î-almost-â-universal
> hash function used in the Adiantum encryption mode. For now, only the
> NH portion is actually NEON-accelerated; the Poly1305 part is less
> performance-critical so is just implemented in C.
>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
> arch/arm/crypto/Kconfig | 5 ++
> arch/arm/crypto/Makefile | 2 +
> arch/arm/crypto/nh-neon-core.S | 116 +++++++++++++++++++++++++
> arch/arm/crypto/nhpoly1305-neon-glue.c | 78 +++++++++++++++++
> 4 files changed, 201 insertions(+)
> create mode 100644 arch/arm/crypto/nh-neon-core.S
> create mode 100644 arch/arm/crypto/nhpoly1305-neon-glue.c
>
> diff --git a/arch/arm/crypto/Kconfig b/arch/arm/crypto/Kconfig
> index cc932d9bba561..458562a34aabe 100644
> --- a/arch/arm/crypto/Kconfig
> +++ b/arch/arm/crypto/Kconfig
> @@ -122,4 +122,9 @@ config CRYPTO_CHACHA20_NEON
> select CRYPTO_BLKCIPHER
> select CRYPTO_CHACHA20
>
> +config CRYPTO_NHPOLY1305_NEON
> + tristate "NEON accelerated NHPoly1305 hash function (for Adiantum)"
> + depends on KERNEL_MODE_NEON
> + select CRYPTO_NHPOLY1305
> +
> endif
> diff --git a/arch/arm/crypto/Makefile b/arch/arm/crypto/Makefile
> index 005482ff95047..b65d6bfab8e6b 100644
> --- a/arch/arm/crypto/Makefile
> +++ b/arch/arm/crypto/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_CRYPTO_SHA1_ARM_NEON) += sha1-arm-neon.o
> obj-$(CONFIG_CRYPTO_SHA256_ARM) += sha256-arm.o
> obj-$(CONFIG_CRYPTO_SHA512_ARM) += sha512-arm.o
> obj-$(CONFIG_CRYPTO_CHACHA20_NEON) += chacha-neon.o
> +obj-$(CONFIG_CRYPTO_NHPOLY1305_NEON) += nhpoly1305-neon.o
>
> ce-obj-$(CONFIG_CRYPTO_AES_ARM_CE) += aes-arm-ce.o
> ce-obj-$(CONFIG_CRYPTO_SHA1_ARM_CE) += sha1-arm-ce.o
> @@ -53,6 +54,7 @@ ghash-arm-ce-y := ghash-ce-core.o ghash-ce-glue.o
> crct10dif-arm-ce-y := crct10dif-ce-core.o crct10dif-ce-glue.o
> crc32-arm-ce-y:= crc32-ce-core.o crc32-ce-glue.o
> chacha-neon-y := chacha-neon-core.o chacha-neon-glue.o
> +nhpoly1305-neon-y := nh-neon-core.o nhpoly1305-neon-glue.o
>
> ifdef REGENERATE_ARM_CRYPTO
> quiet_cmd_perl = PERL $@
> diff --git a/arch/arm/crypto/nh-neon-core.S b/arch/arm/crypto/nh-neon-core.S
> new file mode 100644
> index 0000000000000..434d80ab531c2
> --- /dev/null
> +++ b/arch/arm/crypto/nh-neon-core.S
> @@ -0,0 +1,116 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * NH - Î-almost-universal hash function, NEON accelerated version
> + *
> + * Copyright 2018 Google LLC
> + *
> + * Author: Eric Biggers <ebiggers@xxxxxxxxxx>
> + */
> +
> +#include <linux/linkage.h>
> +
> + .text
> + .fpu neon
> +
> + KEY .req r0
> + MESSAGE .req r1
> + MESSAGE_LEN .req r2
> + HASH .req r3
> +
> + PASS0_SUMS .req q0
> + PASS0_SUM_A .req d0
> + PASS0_SUM_B .req d1
> + PASS1_SUMS .req q1
> + PASS1_SUM_A .req d2
> + PASS1_SUM_B .req d3
> + PASS2_SUMS .req q2
> + PASS2_SUM_A .req d4
> + PASS2_SUM_B .req d5
> + PASS3_SUMS .req q3
> + PASS3_SUM_A .req d6
> + PASS3_SUM_B .req d7
> + K0 .req q4
> + K1 .req q5
> + K2 .req q6
> + K3 .req q7
> + T0 .req q8
> + T0_L .req d16
> + T0_H .req d17
> + T1 .req q9
> + T1_L .req d18
> + T1_H .req d19
> + T2 .req q10
> + T2_L .req d20
> + T2_H .req d21
> + T3 .req q11
> + T3_L .req d22
> + T3_H .req d23
> +
> +.macro _nh_stride k0, k1, k2, k3
> +
> + // Load next message stride
> + vld1.8 {T3}, [MESSAGE]!
> +
> + // Load next key stride
> + vld1.32 {\k3}, [KEY]!
> +
> + // Add message words to key words
> + vadd.u32 T0, T3, \k0
> + vadd.u32 T1, T3, \k1
> + vadd.u32 T2, T3, \k2
> + vadd.u32 T3, T3, \k3
> +
> + // Multiply 32x32 => 64 and accumulate
> + vmlal.u32 PASS0_SUMS, T0_L, T0_H
> + vmlal.u32 PASS1_SUMS, T1_L, T1_H
> + vmlal.u32 PASS2_SUMS, T2_L, T2_H
> + vmlal.u32 PASS3_SUMS, T3_L, T3_H
> +.endm
> +

Since we seem to have some spare NEON registers: would it help to have
a double round version of this macro?

> +/*
> + * void nh_neon(const u32 *key, const u8 *message, size_t message_len,
> + * u8 hash[NH_HASH_BYTES])
> + *
> + * It's guaranteed that message_len % 16 == 0.
> + */
> +ENTRY(nh_neon)
> +
> + vld1.32 {K0,K1}, [KEY]!
> + vmov.u64 PASS0_SUMS, #0
> + vmov.u64 PASS1_SUMS, #0
> + vld1.32 {K2}, [KEY]!
> + vmov.u64 PASS2_SUMS, #0
> + vmov.u64 PASS3_SUMS, #0
> +
> + subs MESSAGE_LEN, MESSAGE_LEN, #64
> + blt .Lloop4_done
> +.Lloop4:
> + _nh_stride K0, K1, K2, K3
> + _nh_stride K1, K2, K3, K0
> + _nh_stride K2, K3, K0, K1
> + _nh_stride K3, K0, K1, K2
> + subs MESSAGE_LEN, MESSAGE_LEN, #64
> + bge .Lloop4
> +
> +.Lloop4_done:
> + ands MESSAGE_LEN, MESSAGE_LEN, #63
> + beq .Ldone
> + _nh_stride K0, K1, K2, K3
> +
> + subs MESSAGE_LEN, MESSAGE_LEN, #16
> + beq .Ldone
> + _nh_stride K1, K2, K3, K0
> +
> + subs MESSAGE_LEN, MESSAGE_LEN, #16
> + beq .Ldone
> + _nh_stride K2, K3, K0, K1
> +
> +.Ldone:
> + // Sum the accumulators for each pass, then store the sums to 'hash'
> + vadd.u64 T0_L, PASS0_SUM_A, PASS0_SUM_B
> + vadd.u64 T0_H, PASS1_SUM_A, PASS1_SUM_B
> + vadd.u64 T1_L, PASS2_SUM_A, PASS2_SUM_B
> + vadd.u64 T1_H, PASS3_SUM_A, PASS3_SUM_B
> + vst1.8 {T0-T1}, [HASH]
> + bx lr
> +ENDPROC(nh_neon)
> diff --git a/arch/arm/crypto/nhpoly1305-neon-glue.c b/arch/arm/crypto/nhpoly1305-neon-glue.c
> new file mode 100644
> index 0000000000000..df48a00f4c50f
> --- /dev/null
> +++ b/arch/arm/crypto/nhpoly1305-neon-glue.c
> @@ -0,0 +1,78 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * NHPoly1305 - Î-almost-â-universal hash function for Adiantum
> + * (NEON accelerated version)
> + *
> + * Copyright 2018 Google LLC
> + */
> +
> +#include <asm/neon.h>
> +#include <asm/simd.h>
> +#include <crypto/internal/hash.h>
> +#include <crypto/nhpoly1305.h>
> +#include <linux/module.h>
> +
> +asmlinkage void nh_neon(const u32 *key, const u8 *message, size_t message_len,
> + u8 hash[NH_HASH_BYTES]);
> +
> +static void _nh_neon(const u32 *key, const u8 *message, size_t message_len,
> + __le64 hash[NH_NUM_PASSES])
> +{
> + nh_neon(key, message, message_len, (u8 *)hash);
> +}
> +

Why do we need this function?

> +static int nhpoly1305_neon_update(struct shash_desc *desc,
> + const u8 *src, unsigned int srclen)
> +{
> + if (srclen < 64 || !may_use_simd())
> + return crypto_nhpoly1305_update(desc, src, srclen);
> +
> + do {
> + unsigned int n = min_t(unsigned int, srclen, PAGE_SIZE);
> +
> + kernel_neon_begin();
> + crypto_nhpoly1305_update_helper(desc, src, n, _nh_neon);
> + kernel_neon_end();
> + src += n;
> + srclen -= n;
> + } while (srclen);
> + return 0;
> +}
> +
> +static struct shash_alg nhpoly1305_alg = {
> + .digestsize = POLY1305_DIGEST_SIZE,
> + .init = crypto_nhpoly1305_init,
> + .update = nhpoly1305_neon_update,
> + .final = crypto_nhpoly1305_final,
> + .setkey = crypto_nhpoly1305_setkey,
> + .descsize = sizeof(struct nhpoly1305_state),
> + .base = {
> + .cra_name = "nhpoly1305",
> + .cra_driver_name = "nhpoly1305-neon",
> + .cra_priority = 200,
> + .cra_ctxsize = sizeof(struct nhpoly1305_key),
> + .cra_module = THIS_MODULE,
> + },

Can we use .base.xxx please?

> +};
> +
> +static int __init nhpoly1305_mod_init(void)
> +{
> + if (!(elf_hwcap & HWCAP_NEON))
> + return -ENODEV;
> +
> + return crypto_register_shash(&nhpoly1305_alg);
> +}
> +
> +static void __exit nhpoly1305_mod_exit(void)
> +{
> + crypto_unregister_shash(&nhpoly1305_alg);
> +}
> +
> +module_init(nhpoly1305_mod_init);
> +module_exit(nhpoly1305_mod_exit);
> +
> +MODULE_DESCRIPTION("NHPoly1305 Î-almost-â-universal hash function (NEON-accelerated)");
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Eric Biggers <ebiggers@xxxxxxxxxx>");
> +MODULE_ALIAS_CRYPTO("nhpoly1305");
> +MODULE_ALIAS_CRYPTO("nhpoly1305-neon");
> --
> 2.19.1.331.ge82ca0e54c-goog
>