[RFC PATCH 7/7] crypto: arm64/polyval: Add PMULL accelerated implementation of POLYVAL

Nathan Huckleberry
2022-01-25T01:48:58Z

Add hardware accelerated version of POLYVAL for ARM64 CPUs with
Crypto Extension support.

This implementation is accelerated using PMULL instructions to perform
the finite field computations. For added efficiency, 8 blocks of the
plaintext are processed simultaneously by precomputing the first 8
powers of the key.

Karatsuba multiplication is used instead of Schoolbook multiplication
because it was found to be slightly faster on ARM64 CPUs. Montgomery
reduction must be used instead of Barrett reduction due to the
difference in modulus between POLYVAL's field and other finite fields.

Signed-off-by: Nathan Huckleberry <nhuck@google.com>
---
arch/arm64/crypto/Kconfig | 6 +
arch/arm64/crypto/Makefile | 3 +
arch/arm64/crypto/polyval-ce-core.S | 317 ++++++++++++++++++++++++++++
arch/arm64/crypto/polyval-ce-glue.c | 164 ++++++++++++++
4 files changed, 490 insertions(+)
create mode 100644 arch/arm64/crypto/polyval-ce-core.S
create mode 100644 arch/arm64/crypto/polyval-ce-glue.c

diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
index cab469e279ec..b858f84b85eb 100644
--- a/arch/arm64/crypto/Kconfig
+++ b/arch/arm64/crypto/Kconfig
@@ -60,6 +60,12 @@ config CRYPTO_GHASH_ARM64_CE
select CRYPTO_GF128MUL
select CRYPTO_LIB_AES

+config CRYPTO_POLYVAL_ARM64_CE
+ tristate "POLYVAL using ARMv8 Crypto Extensions (for HCTR2)"
+ depends on KERNEL_MODE_NEON
+ select CRYPTO_HASH
+ select CRYPTO_POLYVAL
+
config CRYPTO_CRCT10DIF_ARM64_CE
tristate "CRCT10DIF digest algorithm using PMULL instructions"
depends on KERNEL_MODE_NEON && CRC_T10DIF
diff --git a/arch/arm64/crypto/Makefile b/arch/arm64/crypto/Makefile
index 09a805cc32d7..53f9af962b86 100644
--- a/arch/arm64/crypto/Makefile
+++ b/arch/arm64/crypto/Makefile
@@ -26,6 +26,9 @@ sm4-ce-y := sm4-ce-glue.o sm4-ce-core.o
obj-$(CONFIG_CRYPTO_GHASH_ARM64_CE) += ghash-ce.o
ghash-ce-y := ghash-ce-glue.o ghash-ce-core.o

+obj-$(CONFIG_CRYPTO_POLYVAL_ARM64_CE) += polyval-ce.o
+polyval-ce-y := polyval-ce-glue.o polyval-ce-core.o
+
obj-$(CONFIG_CRYPTO_CRCT10DIF_ARM64_CE) += crct10dif-ce.o
crct10dif-ce-y := crct10dif-ce-core.o crct10dif-ce-glue.o

diff --git a/arch/arm64/crypto/polyval-ce-core.S b/arch/arm64/crypto/polyval-ce-core.S
new file mode 100644
index 000000000000..04677c636aa1
--- /dev/null
+++ b/arch/arm64/crypto/polyval-ce-core.S
@@ -0,0 +1,317 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2021 Google LLC
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+/*
+ * This is an efficient implementation of POLYVAL using ARMv8 Crypto Extension
+ * instructions. It works on 8 blocks at a time, computing the 256 degree
+ * polynomial p(x) = h^8m_0 + ... + h^1m_7. It then computes the modular
+ * reduction of p(x) and XORs with the current digest.
+ */
+
+#include <linux/linkage.h>
+#define NUM_PRECOMPUTE_POWERS 8
+
+BLOCKS_LEFT .req x2
+OP1 .req x9
+KEY_START .req x10
+EXTRA_BYTES .req x11
+IDX .req x12
+TMP .req x13
+PARTIAL_LEFT .req x14
+
+M0 .req v0
+M1 .req v1
+M2 .req v2
+M3 .req v3
+M4 .req v4
+M5 .req v5
+M6 .req v6
+M7 .req v7
+KEY8 .req v8
+KEY7 .req v9
+KEY6 .req v10
+KEY5 .req v11
+KEY4 .req v12
+KEY3 .req v13
+KEY2 .req v14
+KEY1 .req v15
+PL .req v16
+PH .req v17
+T .req v18
+Z .req v19
+C .req v20
+D .req v21
+E .req v22
+SUM .req v23
+GSTAR .req v24
+
+ .text
+ .align 4
+
+ .arch armv8-a+crypto
+ .align 4
+
+.Lgstar:
+ .quad 0xc200000000000000, 0xc200000000000000
+
+/*
+ * Computes the first step of Karatsuba multiplication of
+ * registers X, Y.
+ *
+ * Updates C, D, E
+ * Clobbers v25, v26, X, Y
+ */
+.macro karatsuba1 X Y
+ X .req \X
+ Y .req \Y
+ ext v25.16b, X.16b, Y.16b, #8
+ eor v25.16b, v25.16b, X.16b
+ ext v26.16b, Y.16b, Y.16b, #8
+ eor v26.16b, v26.16b, Y.16b
+ pmull v26.1q, v25.1d, v26.1d
+ pmull2 v25.1q, X.2d, Y.2d
+ pmull X.1q, X.1d, Y.1d
+ eor E.16b, E.16b, v26.16b
+ eor C.16b, C.16b, v25.16b
+ eor D.16b, D.16b, X.16b
+ .unreq X
+ .unreq Y
+.endm
+
+/*
+ * Computes the 256-bit polynomial represented by C, D, E.
+ * Stores this polynomial in PH, PL.
+ *
+ * Sets PH, PL
+ * Clobbers C, D, E, v4
+ */
+.macro karatsuba2
+ ext v4.16b, D.16b, C.16b, #8
+ eor E.16b, E.16b, v4.16b //[E1 ^ C0 : E0 ^ D1]
+ eor v4.16b, C.16b, D.16b //[C1 ^ D1 : C0 ^ D0]
+ eor v4.16b, E.16b, v4.16b //[C0 ^ C1 ^ D1 ^ E1 : D1 ^ C0 ^ D0 ^ E0]
+ ext C.16b, C.16b, C.16b, #8 // [C0 : C1]
+ ext D.16b, D.16b, D.16b, #8 // [D0 : D1]
+ ext PH.16b, v4.16b, C.16b, #8 //[C1 : C1 ^ D1 ^ E1 ^ C0]
+ ext PL.16b, D.16b, v4.16b, #8 //[D1 ^ C0 ^ D0 ^ E0 : D0]
+.endm
+
+/*
+ * Perform montgomery reduction of the polynomial
+ * represented by PH, PL. Stores the reduced polynomial
+ * in PH.
+ *
+ * Sets PH
+ * Clobbers T, Z, PL
+ */
+.macro montgomery_reduction
+ pmull T.1q, GSTAR.1d, PL.1d
+ ext T.16b, T.16b, T.16b, #8
+ eor PL.16b, PL.16b, T.16b
+ pmull2 Z.1q, GSTAR.2d, PL.2d
+ eor Z.16b, PL.16b, Z.16b
+ eor PH.16b, PH.16b, Z.16b
+.endm
+
+/*
+ * Compute Polyval on 8 blocks.
+ *
+ * If reduce is set, performs interleaved montgomery reduction
+ * on the last full_stride iteration's PL, PH.
+ *
+ * Sets PL, PH.
+ */
+.macro full_stride reduce
+ .set reduce, \reduce
+ eor C.16b, C.16b, C.16b
+ eor D.16b, D.16b, D.16b
+ eor E.16b, E.16b, E.16b
+
+ ld1 {M0.16b, M1.16b, M2.16b, M3.16b}, [x0], #64
+ ld1 {M4.16b, M5.16b, M6.16b, M7.16b}, [x0], #64
+
+ karatsuba1 M7 KEY1
+ .if(reduce)
+ pmull T.1q, GSTAR.1d, PL.1d
+ .endif
+
+ karatsuba1 M6 KEY2
+ .if(reduce)
+ ext T.16b, T.16b, T.16b, #8
+ .endif
+
+ karatsuba1 M5 KEY3
+ .if(reduce)
+ eor PL.16b, PL.16b, T.16b
+ .endif
+
+ karatsuba1 M4 KEY4
+ .if(reduce)
+ pmull2 Z.1q, GSTAR.2d, PL.2d
+ .endif
+
+ karatsuba1 M3 KEY5
+ .if(reduce)
+ eor Z.16b, PL.16b, Z.16b
+ .endif
+
+ karatsuba1 M2 KEY6
+ .if(reduce)
+ eor PH.16b, PH.16b, Z.16b
+ .endif
+
+ karatsuba1 M1 KEY7
+ .if(reduce)
+ mov SUM.16b, PH.16b
+ .endif
+ eor M0.16b, M0.16b, SUM.16b
+
+ karatsuba1 M0 KEY8
+
+ karatsuba2
+.endm
+
+/*
+ * Handle any extra blocks before
+ * full_stride loop.
+ */
+.macro partial_stride
+ eor C.16b, C.16b, C.16b
+ eor D.16b, D.16b, D.16b
+ eor E.16b, E.16b, E.16b
+ add KEY_START, x1, #(NUM_PRECOMPUTE_POWERS << 4)
+ sub KEY_START, KEY_START, PARTIAL_LEFT, lsl #4
+ ld1 {v0.16b}, [KEY_START]
+ mov v1.16b, SUM.16b
+ karatsuba1 v0 v1
+ karatsuba2
+ montgomery_reduction
+ mov SUM.16b, PH.16b
+ eor C.16b, C.16b, C.16b
+ eor D.16b, D.16b, D.16b
+ eor E.16b, E.16b, E.16b
+ mov IDX, XZR
+.LloopPartial:
+ cmp IDX, PARTIAL_LEFT
+ bge .LloopExitPartial
+
+ sub TMP, IDX, PARTIAL_LEFT
+
+ cmp TMP, #-4
+ bgt .Lgt4Partial
+ ld1 {M0.16b, M1.16b, M2.16b, M3.16b}, [x0], #64
+ // Clobber key registers
+ ld1 {KEY8.16b, KEY7.16b, KEY6.16b, KEY5.16b}, [KEY_START], #64
+ karatsuba1 M0 KEY8
+ karatsuba1 M1 KEY7
+ karatsuba1 M2 KEY6
+ karatsuba1 M3 KEY5
+ add IDX, IDX, #4
+ b .LoutPartial
+
+.Lgt4Partial:
+ cmp TMP, #-3
+ bgt .Lgt3Partial
+ ld1 {M0.16b, M1.16b, M2.16b}, [x0], #48
+ // Clobber key registers
+ ld1 {KEY8.16b, KEY7.16b, KEY6.16b}, [KEY_START], #48
+ karatsuba1 M0 KEY8
+ karatsuba1 M1 KEY7
+ karatsuba1 M2 KEY6
+ add IDX, IDX, #3
+ b .LoutPartial
+
+.Lgt3Partial:
+ cmp TMP, #-2
+ bgt .Lgt2Partial
+ ld1 {M0.16b, M1.16b}, [x0], #32
+ // Clobber key registers
+ ld1 {KEY8.16b, KEY7.16b}, [KEY_START], #32
+ karatsuba1 M0 KEY8
+ karatsuba1 M1 KEY7
+ add IDX, IDX, #2
+ b .LoutPartial
+
+.Lgt2Partial:
+ ld1 {M0.16b}, [x0], #16
+ // Clobber key registers
+ ld1 {KEY8.16b}, [KEY_START], #16
+ karatsuba1 M0 KEY8
+ add IDX, IDX, #1
+.LoutPartial:
+ b .LloopPartial
+.LloopExitPartial:
+ karatsuba2
+ montgomery_reduction
+ eor SUM.16b, SUM.16b, PH.16b
+.endm
+
+/*
+ * Perform montgomery multiplication in GF(2^128) and store result in op1.
+ *
+ * Computes op1*op2*x^{-128} mod x^128 + x^127 + x^126 + x^121 + 1
+ * If op1, op2 are in montgomery form, this computes the montgomery
+ * form of op1*op2.
+ *
+ * void pmull_polyval_mul(ble128 *op1, const ble128 *op2);
+ */
+SYM_FUNC_START(pmull_polyval_mul)
+ adr TMP, .Lgstar
+ ld1 {GSTAR.2d}, [TMP]
+ eor C.16b, C.16b, C.16b
+ eor D.16b, D.16b, D.16b
+ eor E.16b, E.16b, E.16b
+ ld1 {v0.16b}, [x0]
+ ld1 {v1.16b}, [x1]
+ karatsuba1 v0 v1
+ karatsuba2
+ montgomery_reduction
+ st1 {PH.16b}, [x0]
+ ret
+SYM_FUNC_END(pmull_polyval_mul)
+
+/*
+ * Perform polynomial evaluation as specified by POLYVAL. Multiplies the value
+ * stored at accumulator by h^n and XORs the evaluated polynomial into it.
+ *
+ * Computes h^k*accumulator + h^kM_0 + ... + h^1M_{k-1} (No constant term)
+ *
+ * x0 (OP1) - pointer to message blocks
+ * x1 - pointer to precomputed key struct
+ * x2 - number of blocks to hash
+ * x3 - location to XOR with evaluated polynomial
+ *
+ * void pmull_polyval_update(const u8 *in, const struct polyhash_key *keys,
+ * size_t nblocks, ble128 *accumulator);
+ */
+SYM_FUNC_START(pmull_polyval_update)
+ adr TMP, .Lgstar
+ ld1 {GSTAR.2d}, [TMP]
+ ld1 {SUM.16b}, [x3]
+ ands PARTIAL_LEFT, BLOCKS_LEFT, #7
+ beq .LskipPartial
+ partial_stride
+.LskipPartial:
+ subs BLOCKS_LEFT, BLOCKS_LEFT, #NUM_PRECOMPUTE_POWERS
+ blt .LstrideLoopExit
+ ld1 {KEY8.16b, KEY7.16b, KEY6.16b, KEY5.16b}, [x1], #64
+ ld1 {KEY4.16b, KEY3.16b, KEY2.16b, KEY1.16b}, [x1], #64
+ full_stride 0
+ subs BLOCKS_LEFT, BLOCKS_LEFT, #NUM_PRECOMPUTE_POWERS
+ blt .LstrideLoopExitReduce
+.LstrideLoop:
+ full_stride 1
+ subs BLOCKS_LEFT, BLOCKS_LEFT, #NUM_PRECOMPUTE_POWERS
+ bge .LstrideLoop
+.LstrideLoopExitReduce:
+ montgomery_reduction
+ mov SUM.16b, PH.16b
+.LstrideLoopExit:
+ st1 {SUM.16b}, [x3]
+ ret
+SYM_FUNC_END(pmull_polyval_update)
diff --git a/arch/arm64/crypto/polyval-ce-glue.c b/arch/arm64/crypto/polyval-ce-glue.c
new file mode 100644
index 000000000000..2a83a931069a
--- /dev/null
+++ b/arch/arm64/crypto/polyval-ce-glue.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Accelerated POLYVAL implementation with ARMv8 Crypto Extension
+ * instructions. This file contains glue code.
+ *
+ * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
+ * Copyright (c) 2009 Intel Corp.
+ * Author: Huang Ying <ying.huang@intel.com>
+ * Copyright 2021 Google LLC
+ */
+/*
+ * Glue code based on ghash-clmulni-intel_glue.c.
+ *
+ * This implementation of POLYVAL uses montgomery multiplication accelerated by
+ * ARMv8 Crypto Extension instructions to implement the finite field operations.
+ *
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/gf128mul.h>
+#include <crypto/internal/hash.h>
+#include <linux/crypto.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <asm/neon.h>
+
+#define POLYVAL_BLOCK_SIZE 16
+#define POLYVAL_DIGEST_SIZE 16
+#define NUM_PRECOMPUTE_POWERS 8
+
+struct polyval_ctx {
+ be128 key_powers[NUM_PRECOMPUTE_POWERS];
+};
+
+struct polyval_desc_ctx {
+ u8 buffer[POLYVAL_BLOCK_SIZE];
+ u32 bytes;
+};
+
+asmlinkage void pmull_polyval_update(const u8 *in, const be128 *keys, size_t
+ nblocks, be128 *accumulator);
+asmlinkage void pmull_polyval_mul(be128 *op1, const be128 *op2);
+
+static int polyval_init(struct shash_desc *desc)
+{
+ struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
+
+ memset(dctx, 0, sizeof(*dctx));
+
+ return 0;
+}
+
+static int polyval_setkey(struct crypto_shash *tfm,
+ const u8 *key, unsigned int keylen)
+{
+ struct polyval_ctx *ctx = crypto_shash_ctx(tfm);
+ int i;
+
+ if (keylen != POLYVAL_BLOCK_SIZE)
+ return -EINVAL;
+
+ memcpy(&ctx->key_powers[NUM_PRECOMPUTE_POWERS-1], key, sizeof(be128));
+
+ for (i = NUM_PRECOMPUTE_POWERS-2; i >= 0; i--) {
+ memcpy(&ctx->key_powers[i], key, sizeof(be128));
+ pmull_polyval_mul(&ctx->key_powers[i], &ctx->key_powers[i+1]);
+ }
+
+ return 0;
+}
+
+static int polyval_update(struct shash_desc *desc,
+ const u8 *src, unsigned int srclen)
+{
+ struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
+ struct polyval_ctx *ctx = crypto_shash_ctx(desc->tfm);
+ u8 *dst = dctx->buffer;
+ u8 *pos;
+ unsigned int nblocks;
+ unsigned int n;
+
+ kernel_neon_begin();
+ if (dctx->bytes) {
+ n = min(srclen, dctx->bytes);
+ pos = dst + POLYVAL_BLOCK_SIZE - dctx->bytes;
+
+ dctx->bytes -= n;
+ srclen -= n;
+
+ while (n--)
+ *pos++ ^= *src++;
+
+ if (!dctx->bytes)
+ pmull_polyval_mul((be128 *)dst, &ctx->key_powers[NUM_PRECOMPUTE_POWERS-1]);
+ }
+
+ nblocks = srclen/POLYVAL_BLOCK_SIZE;
+ pmull_polyval_update(src, ctx->key_powers, nblocks, (be128 *)dst);
+ srclen -= nblocks*POLYVAL_BLOCK_SIZE;
+ kernel_neon_end();
+
+ if (srclen) {
+ dctx->bytes = POLYVAL_BLOCK_SIZE - srclen;
+ src += nblocks*POLYVAL_BLOCK_SIZE;
+ pos = dst;
+ while (srclen--)
+ *pos++ ^= *src++;
+ }
+
+ return 0;
+}
+
+static int polyval_final(struct shash_desc *desc, u8 *dst)
+{
+ struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
+ struct polyval_ctx *ctx = crypto_shash_ctx(desc->tfm);
+ u8 *buf = dctx->buffer;
+
+ if (dctx->bytes) {
+ kernel_neon_begin();
+ pmull_polyval_mul((be128 *)dst, &ctx->key_powers[NUM_PRECOMPUTE_POWERS-1]);
+ kernel_neon_end();
+ }
+
+ dctx->bytes = 0;
+ memcpy(dst, buf, POLYVAL_BLOCK_SIZE);
+
+ return 0;
+}
+
+static struct shash_alg polyval_alg = {
+ .digestsize = POLYVAL_DIGEST_SIZE,
+ .init = polyval_init,
+ .update = polyval_update,
+ .final = polyval_final,
+ .setkey = polyval_setkey,
+ .descsize = sizeof(struct polyval_desc_ctx),
+ .base = {
+ .cra_name = "polyval",
+ .cra_driver_name = "polyval-ce",
+ .cra_priority = 200,
+ .cra_blocksize = POLYVAL_BLOCK_SIZE,
+ .cra_ctxsize = sizeof(struct polyval_ctx),
+ .cra_module = THIS_MODULE,
+ },
+};
+
+static int __init polyval_mod_init(void)
+{
+ return crypto_register_shash(&polyval_alg);
+}
+
+static void __exit polyval_mod_exit(void)
+{
+ crypto_unregister_shash(&polyval_alg);
+}
+
+subsys_initcall(polyval_mod_init);
+module_exit(polyval_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("POLYVAL hash function accelerated by ARMv8 Crypto Extension");
+MODULE_ALIAS_CRYPTO("polyval");
--
2.35.0.rc0.227.g00780c9af4-goog