crypto: arm64/speck - add NEON-accelerated implementation of Speck-XTS

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@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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

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
 

arch/arm64/crypto/speck-neon-core.S

+// 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@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
+
+/*
+ * _speck_round_128bytes() - Speck encryption round on 128 bytes at a time
+ *
+ * Do one Speck encryption round on the 128 bytes (8 blocks for Speck128, 16 for
+ * Speck64) stored in X0-X3 and Y0-Y3, using the round key stored in all lanes
+ * of ROUND_KEY.  'n' is the lane size: 64 for Speck128, or 32 for Speck64.
+ * 'lanes' is the lane specifier: "2d" for Speck128 or "4s" for Speck64.
+ */
+.macro _speck_round_128bytes	n, lanes
+
+	// x = ror(x, 8)
+	tbl		X_0.16b, {X_0.16b}, ROTATE_TABLE.16b
+	tbl		X_1.16b, {X_1.16b}, ROTATE_TABLE.16b
+	tbl		X_2.16b, {X_2.16b}, ROTATE_TABLE.16b
+	tbl		X_3.16b, {X_3.16b}, ROTATE_TABLE.16b
+
+	// x += y
+	add		X_0.\lanes, X_0.\lanes, Y_0.\lanes
+	add		X_1.\lanes, X_1.\lanes, Y_1.\lanes
+	add		X_2.\lanes, X_2.\lanes, Y_2.\lanes
+	add		X_3.\lanes, X_3.\lanes, Y_3.\lanes
+
+	// x ^= k
+	eor		X_0.16b, X_0.16b, ROUND_KEY.16b
+	eor		X_1.16b, X_1.16b, ROUND_KEY.16b
+	eor		X_2.16b, X_2.16b, ROUND_KEY.16b
+	eor		X_3.16b, X_3.16b, ROUND_KEY.16b
+
+	// y = rol(y, 3)
+	shl		TMP0.\lanes, Y_0.\lanes, #3
+	shl		TMP1.\lanes, Y_1.\lanes, #3
+	shl		TMP2.\lanes, Y_2.\lanes, #3
+	shl		TMP3.\lanes, Y_3.\lanes, #3
+	sri		TMP0.\lanes, Y_0.\lanes, #(\n - 3)
+	sri		TMP1.\lanes, Y_1.\lanes, #(\n - 3)
+	sri		TMP2.\lanes, Y_2.\lanes, #(\n - 3)
+	sri		TMP3.\lanes, Y_3.\lanes, #(\n - 3)
+
+	// y ^= x
+	eor		Y_0.16b, TMP0.16b, X_0.16b
+	eor		Y_1.16b, TMP1.16b, X_1.16b
+	eor		Y_2.16b, TMP2.16b, X_2.16b
+	eor		Y_3.16b, TMP3.16b, X_3.16b
+.endm
+
+/*
+ * _speck_unround_128bytes() - Speck decryption round on 128 bytes at a time
+ *
+ * This is the inverse of _speck_round_128bytes().
+ */
+.macro _speck_unround_128bytes	n, lanes
+
+	// y ^= x
+	eor		TMP0.16b, Y_0.16b, X_0.16b
+	eor		TMP1.16b, Y_1.16b, X_1.16b
+	eor		TMP2.16b, Y_2.16b, X_2.16b
+	eor		TMP3.16b, Y_3.16b, X_3.16b
+
+	// y = ror(y, 3)
+	ushr		Y_0.\lanes, TMP0.\lanes, #3
+	ushr		Y_1.\lanes, TMP1.\lanes, #3
+	ushr		Y_2.\lanes, TMP2.\lanes, #3
+	ushr		Y_3.\lanes, TMP3.\lanes, #3
+	sli		Y_0.\lanes, TMP0.\lanes, #(\n - 3)
+	sli		Y_1.\lanes, TMP1.\lanes, #(\n - 3)
+	sli		Y_2.\lanes, TMP2.\lanes, #(\n - 3)
+	sli		Y_3.\lanes, TMP3.\lanes, #(\n - 3)
+
+	// x ^= k
+	eor		X_0.16b, X_0.16b, ROUND_KEY.16b
+	eor		X_1.16b, X_1.16b, ROUND_KEY.16b
+	eor		X_2.16b, X_2.16b, ROUND_KEY.16b
+	eor		X_3.16b, X_3.16b, ROUND_KEY.16b
+
+	// x -= y
+	sub		X_0.\lanes, X_0.\lanes, Y_0.\lanes
+	sub		X_1.\lanes, X_1.\lanes, Y_1.\lanes
+	sub		X_2.\lanes, X_2.\lanes, Y_2.\lanes
+	sub		X_3.\lanes, X_3.\lanes, Y_3.\lanes
+
+	// x = rol(x, 8)
+	tbl		X_0.16b, {X_0.16b}, ROTATE_TABLE.16b
+	tbl		X_1.16b, {X_1.16b}, ROTATE_TABLE.16b
+	tbl		X_2.16b, {X_2.16b}, ROTATE_TABLE.16b
+	tbl		X_3.16b, {X_3.16b}, ROTATE_TABLE.16b
+.endm
+
+.macro _next_xts_tweak	next, cur, tmp, n
+.if \n == 64
+	/*
+	 * Calculate the next tweak by multiplying the current one by x,
+	 * modulo p(x) = x^128 + x^7 + x^2 + x + 1.
+	 */
+	sshr		\tmp\().2d, \cur\().2d, #63
+	and		\tmp\().16b, \tmp\().16b, GFMUL_TABLE.16b
+	shl		\next\().2d, \cur\().2d, #1
+	ext		\tmp\().16b, \tmp\().16b, \tmp\().16b, #8
+	eor		\next\().16b, \next\().16b, \tmp\().16b
+.else
+	/*
+	 * Calculate the next two tweaks by multiplying the current ones by x^2,
+	 * modulo p(x) = x^64 + x^4 + x^3 + x + 1.
+	 */
+	ushr		\tmp\().2d, \cur\().2d, #62
+	shl		\next\().2d, \cur\().2d, #2
+	tbl		\tmp\().16b, {GFMUL_TABLE.16b}, \tmp\().16b
+	eor		\next\().16b, \next\().16b, \tmp\().16b
+.endif
+.endm
+
+/*
+ * _speck_xts_crypt() - Speck-XTS encryption/decryption
+ *
+ * Encrypt or decrypt NBYTES bytes of data from the SRC buffer to the DST buffer
+ * using Speck-XTS, specifically the variant with a block size of '2n' and round
+ * count given by NROUNDS.  The expanded round keys are given in ROUND_KEYS, and
+ * the current XTS tweak value is given in TWEAK.  It's assumed that NBYTES is a
+ * nonzero multiple of 128.
+ */
+.macro _speck_xts_crypt	n, lanes, decrypting
+
+	/*
+	 * If decrypting, modify the ROUND_KEYS parameter to point to the last
+	 * round key rather than the first, since for decryption the round keys
+	 * are used in reverse order.
+	 */
+.if \decrypting
+	mov		NROUNDS, NROUNDS	/* zero the high 32 bits */
+.if \n == 64
+	add		ROUND_KEYS, ROUND_KEYS, NROUNDS_X, lsl #3
+	sub		ROUND_KEYS, ROUND_KEYS, #8
+.else
+	add		ROUND_KEYS, ROUND_KEYS, NROUNDS_X, lsl #2
+	sub		ROUND_KEYS, ROUND_KEYS, #4
+.endif
+.endif
+
+	// Load the index vector for tbl-based 8-bit rotates
+.if \decrypting
+	ldr		ROTATE_TABLE_Q, .Lrol\n\()_8_table
+.else
+	ldr		ROTATE_TABLE_Q, .Lror\n\()_8_table
+.endif
+
+	// One-time XTS preparation
+.if \n == 64
+	// Load first tweak
+	ld1		{TWEAKV0.16b}, [TWEAK]
+
+	// Load GF(2^128) multiplication table
+	ldr		GFMUL_TABLE_Q, .Lgf128mul_table
+.else
+	// Load first tweak
+	ld1		{TWEAKV0.8b}, [TWEAK]
+
+	// Load GF(2^64) multiplication table
+	ldr		GFMUL_TABLE_Q, .Lgf64mul_table
+
+	// Calculate second tweak, packing it together with the first
+	ushr		TMP0.2d, TWEAKV0.2d, #63
+	shl		TMP1.2d, TWEAKV0.2d, #1
+	tbl		TMP0.8b, {GFMUL_TABLE.16b}, TMP0.8b
+	eor		TMP0.8b, TMP0.8b, TMP1.8b
+	mov		TWEAKV0.d[1], TMP0.d[0]
+.endif
+
+.Lnext_128bytes_\@:
+
+	// Calculate XTS tweaks for next 128 bytes
+	_next_xts_tweak	TWEAKV1, TWEAKV0, TMP0, \n
+	_next_xts_tweak	TWEAKV2, TWEAKV1, TMP0, \n
+	_next_xts_tweak	TWEAKV3, TWEAKV2, TMP0, \n
+	_next_xts_tweak	TWEAKV4, TWEAKV3, TMP0, \n
+	_next_xts_tweak	TWEAKV5, TWEAKV4, TMP0, \n
+	_next_xts_tweak	TWEAKV6, TWEAKV5, TMP0, \n
+	_next_xts_tweak	TWEAKV7, TWEAKV6, TMP0, \n
+	_next_xts_tweak	TWEAKV_NEXT, TWEAKV7, TMP0, \n
+
+	// Load the next source blocks into {X,Y}[0-3]
+	ld1		{X_0.16b-Y_1.16b}, [SRC], #64
+	ld1		{X_2.16b-Y_3.16b}, [SRC], #64
+
+	// XOR the source blocks with their XTS tweaks
+	eor		TMP0.16b, X_0.16b, TWEAKV0.16b
+	eor		Y_0.16b,  Y_0.16b, TWEAKV1.16b
+	eor		TMP1.16b, X_1.16b, TWEAKV2.16b
+	eor		Y_1.16b,  Y_1.16b, TWEAKV3.16b
+	eor		TMP2.16b, X_2.16b, TWEAKV4.16b
+	eor		Y_2.16b,  Y_2.16b, TWEAKV5.16b
+	eor		TMP3.16b, X_3.16b, TWEAKV6.16b
+	eor		Y_3.16b,  Y_3.16b, TWEAKV7.16b
+
+	/*
+	 * De-interleave the 'x' and 'y' elements of each block, i.e. make it so
+	 * that the X[0-3] registers contain only the second halves of blocks,
+	 * and the Y[0-3] registers contain only the first halves of blocks.
+	 * (Speck uses the order (y, x) rather than the more intuitive (x, y).)
+	 */
+	uzp2		X_0.\lanes, TMP0.\lanes, Y_0.\lanes
+	uzp1		Y_0.\lanes, TMP0.\lanes, Y_0.\lanes
+	uzp2		X_1.\lanes, TMP1.\lanes, Y_1.\lanes
+	uzp1		Y_1.\lanes, TMP1.\lanes, Y_1.\lanes
+	uzp2		X_2.\lanes, TMP2.\lanes, Y_2.\lanes
+	uzp1		Y_2.\lanes, TMP2.\lanes, Y_2.\lanes
+	uzp2		X_3.\lanes, TMP3.\lanes, Y_3.\lanes
+	uzp1		Y_3.\lanes, TMP3.\lanes, Y_3.\lanes
+
+	// Do the cipher rounds
+	mov		x6, ROUND_KEYS
+	mov		w7, NROUNDS
+.Lnext_round_\@:
+.if \decrypting
+	ld1r		{ROUND_KEY.\lanes}, [x6]
+	sub		x6, x6, #( \n / 8 )
+	_speck_unround_128bytes	\n, \lanes
+.else
+	ld1r		{ROUND_KEY.\lanes}, [x6], #( \n / 8 )
+	_speck_round_128bytes	\n, \lanes
+.endif
+	subs		w7, w7, #1
+	bne		.Lnext_round_\@
+
+	// Re-interleave the 'x' and 'y' elements of each block
+	zip1		TMP0.\lanes, Y_0.\lanes, X_0.\lanes
+	zip2		Y_0.\lanes,  Y_0.\lanes, X_0.\lanes
+	zip1		TMP1.\lanes, Y_1.\lanes, X_1.\lanes
+	zip2		Y_1.\lanes,  Y_1.\lanes, X_1.\lanes
+	zip1		TMP2.\lanes, Y_2.\lanes, X_2.\lanes
+	zip2		Y_2.\lanes,  Y_2.\lanes, X_2.\lanes
+	zip1		TMP3.\lanes, Y_3.\lanes, X_3.\lanes
+	zip2		Y_3.\lanes,  Y_3.\lanes, X_3.\lanes
+
+	// XOR the encrypted/decrypted blocks with the tweaks calculated earlier
+	eor		X_0.16b, TMP0.16b, TWEAKV0.16b
+	eor		Y_0.16b, Y_0.16b,  TWEAKV1.16b
+	eor		X_1.16b, TMP1.16b, TWEAKV2.16b
+	eor		Y_1.16b, Y_1.16b,  TWEAKV3.16b
+	eor		X_2.16b, TMP2.16b, TWEAKV4.16b
+	eor		Y_2.16b, Y_2.16b,  TWEAKV5.16b
+	eor		X_3.16b, TMP3.16b, TWEAKV6.16b
+	eor		Y_3.16b, Y_3.16b,  TWEAKV7.16b
+	mov		TWEAKV0.16b, TWEAKV_NEXT.16b
+
+	// Store the ciphertext in the destination buffer
+	st1		{X_0.16b-Y_1.16b}, [DST], #64
+	st1		{X_2.16b-Y_3.16b}, [DST], #64
+
+	// Continue if there are more 128-byte chunks remaining
+	subs		NBYTES, NBYTES, #128
+	bne		.Lnext_128bytes_\@
+
+	// Store the next tweak and return
+.if \n == 64
+	st1		{TWEAKV_NEXT.16b}, [TWEAK]
+.else
+	st1		{TWEAKV_NEXT.8b}, [TWEAK]
+.endif
+	ret
+.endm
+
+ENTRY(speck128_xts_encrypt_neon)
+	_speck_xts_crypt	n=64, lanes=2d, decrypting=0
+ENDPROC(speck128_xts_encrypt_neon)
+
+ENTRY(speck128_xts_decrypt_neon)
+	_speck_xts_crypt	n=64, lanes=2d, decrypting=1
+ENDPROC(speck128_xts_decrypt_neon)
+
+ENTRY(speck64_xts_encrypt_neon)
+	_speck_xts_crypt	n=32, lanes=4s, decrypting=0
+ENDPROC(speck64_xts_encrypt_neon)
+
+ENTRY(speck64_xts_decrypt_neon)
+	_speck_xts_crypt	n=32, lanes=4s, decrypting=1
+ENDPROC(speck64_xts_decrypt_neon)

arch/arm64/crypto/speck-neon-glue.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NEON-accelerated implementation of Speck128-XTS and Speck64-XTS
+ * (64-bit version; based on the 32-bit version)
+ *
+ * Copyright (c) 2018 Google, Inc
+ */
+
+#include <asm/hwcap.h>
+#include <asm/neon.h>
+#include <asm/simd.h>
+#include <crypto/algapi.h>
+#include <crypto/gf128mul.h>
+#include <crypto/internal/skcipher.h>
+#include <crypto/speck.h>
+#include <crypto/xts.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+/* The assembly functions only handle multiples of 128 bytes */
+#define SPECK_NEON_CHUNK_SIZE	128
+
+/* Speck128 */
+
+struct speck128_xts_tfm_ctx {
+	struct speck128_tfm_ctx main_key;
+	struct speck128_tfm_ctx tweak_key;
+};
+
+asmlinkage void speck128_xts_encrypt_neon(const u64 *round_keys, int nrounds,
+					  void *dst, const void *src,
+					  unsigned int nbytes, void *tweak);
+
+asmlinkage void speck128_xts_decrypt_neon(const u64 *round_keys, int nrounds,
+					  void *dst, const void *src,
+					  unsigned int nbytes, void *tweak);
+
+typedef void (*speck128_crypt_one_t)(const struct speck128_tfm_ctx *,
+				     u8 *, const u8 *);
+typedef void (*speck128_xts_crypt_many_t)(const u64 *, int, void *,
+					  const void *, unsigned int, void *);
+
+static __always_inline int
+__speck128_xts_crypt(struct skcipher_request *req,
+		     speck128_crypt_one_t crypt_one,
+		     speck128_xts_crypt_many_t crypt_many)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	const struct speck128_xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
+	struct skcipher_walk walk;
+	le128 tweak;
+	int err;
+
+	err = skcipher_walk_virt(&walk, req, true);
+
+	crypto_speck128_encrypt(&ctx->tweak_key, (u8 *)&tweak, walk.iv);
+
+	while (walk.nbytes > 0) {
+		unsigned int nbytes = walk.nbytes;
+		u8 *dst = walk.dst.virt.addr;
+		const u8 *src = walk.src.virt.addr;
+
+		if (nbytes >= SPECK_NEON_CHUNK_SIZE && may_use_simd()) {
+			unsigned int count;
+
+			count = round_down(nbytes, SPECK_NEON_CHUNK_SIZE);
+			kernel_neon_begin();
+			(*crypt_many)(ctx->main_key.round_keys,
+				      ctx->main_key.nrounds,
+				      dst, src, count, &tweak);
+			kernel_neon_end();
+			dst += count;
+			src += count;
+			nbytes -= count;
+		}
+
+		/* Handle any remainder with generic code */
+		while (nbytes >= sizeof(tweak)) {
+			le128_xor((le128 *)dst, (const le128 *)src, &tweak);
+			(*crypt_one)(&ctx->main_key, dst, dst);
+			le128_xor((le128 *)dst, (const le128 *)dst, &tweak);
+			gf128mul_x_ble(&tweak, &tweak);
+
+			dst += sizeof(tweak);
+			src += sizeof(tweak);
+			nbytes -= sizeof(tweak);
+		}
+		err = skcipher_walk_done(&walk, nbytes);
+	}
+
+	return err;
+}
+
+static int speck128_xts_encrypt(struct skcipher_request *req)
+{
+	return __speck128_xts_crypt(req, crypto_speck128_encrypt,
+				    speck128_xts_encrypt_neon);
+}
+
+static int speck128_xts_decrypt(struct skcipher_request *req)
+{
+	return __speck128_xts_crypt(req, crypto_speck128_decrypt,
+				    speck128_xts_decrypt_neon);
+}
+
+static int speck128_xts_setkey(struct crypto_skcipher *tfm, const u8 *key,
+			       unsigned int keylen)
+{
+	struct speck128_xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
+	int err;
+
+	err = xts_verify_key(tfm, key, keylen);
+	if (err)
+		return err;
+
+	keylen /= 2;
+
+	err = crypto_speck128_setkey(&ctx->main_key, key, keylen);
+	if (err)
+		return err;
+
+	return crypto_speck128_setkey(&ctx->tweak_key, key + keylen, keylen);
+}
+
+/* Speck64 */
+
+struct speck64_xts_tfm_ctx {
+	struct speck64_tfm_ctx main_key;
+	struct speck64_tfm_ctx tweak_key;
+};
+
+asmlinkage void speck64_xts_encrypt_neon(const u32 *round_keys, int nrounds,
+					 void *dst, const void *src,
+					 unsigned int nbytes, void *tweak);
+
+asmlinkage void speck64_xts_decrypt_neon(const u32 *round_keys, int nrounds,
+					 void *dst, const void *src,
+					 unsigned int nbytes, void *tweak);
+
+typedef void (*speck64_crypt_one_t)(const struct speck64_tfm_ctx *,
+				    u8 *, const u8 *);
+typedef void (*speck64_xts_crypt_many_t)(const u32 *, int, void *,
+					 const void *, unsigned int, void *);
+
+static __always_inline int
+__speck64_xts_crypt(struct skcipher_request *req, speck64_crypt_one_t crypt_one,
+		    speck64_xts_crypt_many_t crypt_many)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	const struct speck64_xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
+	struct skcipher_walk walk;
+	__le64 tweak;
+	int err;
+
+	err = skcipher_walk_virt(&walk, req, true);
+
+	crypto_speck64_encrypt(&ctx->tweak_key, (u8 *)&tweak, walk.iv);
+
+	while (walk.nbytes > 0) {
+		unsigned int nbytes = walk.nbytes;
+		u8 *dst = walk.dst.virt.addr;
+		const u8 *src = walk.src.virt.addr;
+
+		if (nbytes >= SPECK_NEON_CHUNK_SIZE && may_use_simd()) {
+			unsigned int count;
+
+			count = round_down(nbytes, SPECK_NEON_CHUNK_SIZE);
+			kernel_neon_begin();
+			(*crypt_many)(ctx->main_key.round_keys,
+				      ctx->main_key.nrounds,
+				      dst, src, count, &tweak);
+			kernel_neon_end();
+			dst += count;
+			src += count;
+			nbytes -= count;
+		}
+
+		/* Handle any remainder with generic code */
+		while (nbytes >= sizeof(tweak)) {
+			*(__le64 *)dst = *(__le64 *)src ^ tweak;
+			(*crypt_one)(&ctx->main_key, dst, dst);
+			*(__le64 *)dst ^= tweak;
+			tweak = cpu_to_le64((le64_to_cpu(tweak) << 1) ^
+					    ((tweak & cpu_to_le64(1ULL << 63)) ?
+					     0x1B : 0));
+			dst += sizeof(tweak);
+			src += sizeof(tweak);
+			nbytes -= sizeof(tweak);
+		}
+		err = skcipher_walk_done(&walk, nbytes);
+	}
+
+	return err;
+}
+
+static int speck64_xts_encrypt(struct skcipher_request *req)
+{
+	return __speck64_xts_crypt(req, crypto_speck64_encrypt,
+				   speck64_xts_encrypt_neon);
+}
+
+static int speck64_xts_decrypt(struct skcipher_request *req)
+{
+	return __speck64_xts_crypt(req, crypto_speck64_decrypt,
+				   speck64_xts_decrypt_neon);
+}
+
+static int speck64_xts_setkey(struct crypto_skcipher *tfm, const u8 *key,
+			      unsigned int keylen)
+{
+	struct speck64_xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
+	int err;
+
+	err = xts_verify_key(tfm, key, keylen);
+	if (err)
+		return err;
+
+	keylen /= 2;
+
+	err = crypto_speck64_setkey(&ctx->main_key, key, keylen);
+	if (err)
+		return err;
+
+	return crypto_speck64_setkey(&ctx->tweak_key, key + keylen, keylen);
+}
+
+static struct skcipher_alg speck_algs[] = {
+	{
+		.base.cra_name		= "xts(speck128)",
+		.base.cra_driver_name	= "xts-speck128-neon",
+		.base.cra_priority	= 300,
+		.base.cra_blocksize	= SPECK128_BLOCK_SIZE,
+		.base.cra_ctxsize	= sizeof(struct speck128_xts_tfm_ctx),
+		.base.cra_alignmask	= 7,
+		.base.cra_module	= THIS_MODULE,
+		.min_keysize		= 2 * SPECK128_128_KEY_SIZE,
+		.max_keysize		= 2 * SPECK128_256_KEY_SIZE,
+		.ivsize			= SPECK128_BLOCK_SIZE,
+		.walksize		= SPECK_NEON_CHUNK_SIZE,
+		.setkey			= speck128_xts_setkey,
+		.encrypt		= speck128_xts_encrypt,
+		.decrypt		= speck128_xts_decrypt,
+	}, {
+		.base.cra_name		= "xts(speck64)",
+		.base.cra_driver_name	= "xts-speck64-neon",
+		.base.cra_priority	= 300,
+		.base.cra_blocksize	= SPECK64_BLOCK_SIZE,
+		.base.cra_ctxsize	= sizeof(struct speck64_xts_tfm_ctx),
+		.base.cra_alignmask	= 7,
+		.base.cra_module	= THIS_MODULE,
+		.min_keysize		= 2 * SPECK64_96_KEY_SIZE,
+		.max_keysize		= 2 * SPECK64_128_KEY_SIZE,
+		.ivsize			= SPECK64_BLOCK_SIZE,
+		.walksize		= SPECK_NEON_CHUNK_SIZE,
+		.setkey			= speck64_xts_setkey,
+		.encrypt		= speck64_xts_encrypt,
+		.decrypt		= speck64_xts_decrypt,
+	}
+};
+
+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));
+}
+
+static void __exit speck_neon_module_exit(void)
+{
+	crypto_unregister_skciphers(speck_algs, ARRAY_SIZE(speck_algs));
+}
+
+module_init(speck_neon_module_init);
+module_exit(speck_neon_module_exit);
+
+MODULE_DESCRIPTION("Speck block cipher (NEON-accelerated)");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>");
+MODULE_ALIAS_CRYPTO("xts(speck128)");
+MODULE_ALIAS_CRYPTO("xts-speck128-neon");
+MODULE_ALIAS_CRYPTO("xts(speck64)");
+MODULE_ALIAS_CRYPTO("xts-speck64-neon");