[PATCH v2 06/17] zinc: ChaCha20 MIPS32r2 implementation

["Jason A. Donenfeld" <Jason@zx2c4.com>]

This MIPS32r2 implementation comes from René van Dorst and me and
results in a nice speedup on the usual OpenWRT targets.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Samuel Neves <sneves@dei.uc.pt>
Cc: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
Cc: René van Dorst <opensource@vdorst.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: linux-crypto@vger.kernel.org
---
 lib/zinc/Makefile                      |   4 +
 lib/zinc/chacha20/chacha20-mips-glue.h |  19 +
 lib/zinc/chacha20/chacha20-mips.S      | 474 +++++++++++++++++++++++++
 3 files changed, 497 insertions(+)
 create mode 100644 lib/zinc/chacha20/chacha20-mips-glue.h
 create mode 100644 lib/zinc/chacha20/chacha20-mips.S

diff --git a/lib/zinc/Makefile b/lib/zinc/Makefile
index fc6ca1c84cd1..3ba830b51695 100644
--- a/lib/zinc/Makefile
+++ b/lib/zinc/Makefile
@@ -16,6 +16,10 @@ ifeq ($(CONFIG_ARM64),y)
 zinc-y += chacha20/chacha20-arm64.o
 CFLAGS_chacha20.o += -include $(srctree)/$(src)/chacha20/chacha20-arm-glue.h
 endif
+ifeq ($(CONFIG_MIPS)$(CONFIG_CPU_MIPS32_R2),yy)
+zinc-y += chacha20/chacha20-mips.o
+CFLAGS_chacha20.o += -include $(srctree)/$(src)/chacha20/chacha20-mips-glue.h
+endif
 endif
 
 zinc-y += main.o
diff --git a/lib/zinc/chacha20/chacha20-mips-glue.h b/lib/zinc/chacha20/chacha20-mips-glue.h
new file mode 100644
index 000000000000..54c71a0b5bd0
--- /dev/null
+++ b/lib/zinc/chacha20/chacha20-mips-glue.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include <zinc/chacha20.h>
+
+asmlinkage void chacha20_mips(u8 *out, const u8 *in, const size_t len, const u32 key[8], const u32 counter[4]);
+void __init chacha20_fpu_init(void) { }
+
+static inline bool chacha20_arch(u8 *dst, const u8 *src, const size_t len, const u32 key[8], const u32 counter[4], simd_context_t simd_context)
+{
+	chacha20_mips(dst, src, len, key, counter);
+	return true;
+}
+
+static inline bool hchacha20_arch(u8 *derived_key, const u8 *nonce, const u8 *key, simd_context_t simd_context) { return false; }
+
+#define HAVE_CHACHA20_ARCH_IMPLEMENTATION
diff --git a/lib/zinc/chacha20/chacha20-mips.S b/lib/zinc/chacha20/chacha20-mips.S
new file mode 100644
index 000000000000..77da2c2fb240
--- /dev/null
+++ b/lib/zinc/chacha20/chacha20-mips.S
@@ -0,0 +1,474 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2016-2018 René van Dorst <opensource@vdorst.com>. All Rights Reserved.
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#define MASK_U32	0x3c
+#define MASK_BYTES	0x03
+#define CHACHA20_BLOCK_SIZE 64
+#define STACK_SIZE	4*16
+
+#define X0  $t0
+#define X1  $t1
+#define X2  $t2
+#define X3  $t3
+#define X4  $t4
+#define X5  $t5
+#define X6  $t6
+#define X7  $t7
+#define X8  $v1
+#define X9  $fp
+#define X10 $s7
+#define X11 $s6
+#define X12 $s5
+#define X13 $s4
+#define X14 $s3
+#define X15 $s2
+/* Use regs which are overwritten on exit for Tx so we don't leak clear data. */
+#define T0  $s1
+#define T1  $s0
+#define T(n) T ## n
+#define X(n) X ## n
+
+/* Input arguments */
+#define OUT		$a0
+#define IN		$a1
+#define BYTES		$a2
+/* KEY and NONCE argument must be u32 aligned */
+#define KEY		$a3
+/* NONCE pointer is given via stack */
+#define NONCE		$t9
+
+/* Output argument */
+/* NONCE[0] is kept in a register and not in memory.
+ * We don't want to touch original value in memory.
+ * Must be incremented every loop iteration.
+ */
+#define NONCE_0		$v0
+
+/* SAVED_X and SAVED_CA are set in the jump table.
+ * Use regs which are overwritten on exit else we don't leak clear data.
+ * They are used to handling the last bytes which are not multiple of 4.
+ */
+#define SAVED_X		X15
+#define SAVED_CA	$ra
+
+#define PTR_LAST_ROUND	$t8
+
+/* ChaCha20 constants and stack location */
+#define CONSTANT_OFS_SP	48
+#define UNALIGNED_OFS_SP 40
+
+#define CONSTANT_1	0x61707865
+#define CONSTANT_2	0x3320646e
+#define CONSTANT_3	0x79622d32
+#define CONSTANT_4	0x6b206574
+
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define MSB 0
+#define LSB 3
+#define ROTx rotl
+#define ROTR(n) rotr n, 24
+#define	CPU_TO_LE32(n) \
+	wsbh	n; \
+	rotr	n, 16;
+#else
+#define MSB 3
+#define LSB 0
+#define ROTx rotr
+#define CPU_TO_LE32(n)
+#define ROTR(n)
+#endif
+
+#define STORE_UNALIGNED(x, a, s, o) \
+.Lchacha20_mips_xor_unaligned_ ## x ## _b: ; \
+	.if ((s != NONCE) || (o != 0)); \
+		lw	T0, o(s); \
+	.endif; \
+	lwl	T1, x-4+MSB ## (IN); \
+	lwr	T1, x-4+LSB ## (IN); \
+	.if ((s == NONCE) && (o == 0)); \
+		addu	X ## a, NONCE_0; \
+	.else; \
+		addu	X ## a, T0; \
+	.endif; \
+	CPU_TO_LE32(X ## a); \
+	xor	X ## a, T1; \
+	swl	X ## a, x-4+MSB ## (OUT); \
+	swr	X ## a, x-4+LSB ## (OUT);
+
+#define STORE_ALIGNED(x, a, s, o) \
+.Lchacha20_mips_xor_aligned_ ## x ## _b: ; \
+	.if ((s != NONCE) || (o != 0)); \
+		lw	T0, o(s); \
+	.endif; \
+	lw	T1, x-4 ## (IN); \
+	.if ((s == NONCE) && (o == 0)); \
+		addu	X ## a, NONCE_0; \
+	.else; \
+		addu	X ## a, T0; \
+	.endif; \
+	CPU_TO_LE32(X ## a); \
+	xor	X ## a, T1; \
+	sw	X ## a, x-4 ## (OUT);
+
+/* Jump table macro.
+ * Used for setup and handling the last bytes, which are not multiple of 4.
+ * X15 is free to store Xn
+ * Every jumptable entry must be equal in size.
+ */
+#define JMPTBL_ALIGNED(x, a, s, o) \
+.Lchacha20_mips_jmptbl_aligned_ ## a: ; \
+	.if ((s == NONCE) && (o == 0)); \
+		move	SAVED_CA, NONCE_0; \
+	.else; \
+		lw	SAVED_CA, o(s);\
+	.endif; \
+	b	.Lchacha20_mips_xor_aligned_ ## x ## _b; \
+	move	SAVED_X, X ## a;
+
+#define JMPTBL_UNALIGNED(x, a, s, o) \
+.Lchacha20_mips_jmptbl_unaligned_ ## a: ; \
+	.if ((s == NONCE) && (o == 0)); \
+		move	SAVED_CA, NONCE_0; \
+	.else; \
+		lw	SAVED_CA, o(s);\
+	.endif; \
+	b	.Lchacha20_mips_xor_unaligned_ ## x ## _b; \
+	move	SAVED_X, X ## a;
+
+#define AXR(A, B, C, D,  K, L, M, N,  V, W, Y, Z,  S) \
+	addu	X(A), X(K); \
+	addu	X(B), X(L); \
+	addu	X(C), X(M); \
+	addu	X(D), X(N); \
+	xor	X(V), X(A); \
+	xor	X(W), X(B); \
+	xor	X(Y), X(C); \
+	xor	X(Z), X(D); \
+	rotl	X(V), S;    \
+	rotl	X(W), S;    \
+	rotl	X(Y), S;    \
+	rotl	X(Z), S;
+
+.text
+.set reorder
+.set noat
+.globl chacha20_mips
+.ent   chacha20_mips
+chacha20_mips:
+	.frame $sp, STACK_SIZE, $ra
+	/* This is in the fifth argument */
+	lw	NONCE, 16($sp)
+
+	/* Return bytes = 0. */
+	.set noreorder
+	beqz	BYTES, .Lchacha20_mips_end
+	addiu	$sp, -STACK_SIZE
+	.set reorder
+
+	/* Calculate PTR_LAST_ROUND */
+	addiu	PTR_LAST_ROUND, BYTES, -1
+	ins	PTR_LAST_ROUND, $zero, 0, 6
+	addu	PTR_LAST_ROUND, OUT
+
+	/* Save s0-s7, fp, ra. */
+	sw	$ra,  0($sp)
+	sw	$fp,  4($sp)
+	sw	$s0,  8($sp)
+	sw	$s1, 12($sp)
+	sw	$s2, 16($sp)
+	sw	$s3, 20($sp)
+	sw	$s4, 24($sp)
+	sw	$s5, 28($sp)
+	sw	$s6, 32($sp)
+	sw	$s7, 36($sp)
+
+	lw	NONCE_0, 0(NONCE)
+	/* Test IN or OUT is unaligned.
+	 * UNALIGNED (T1) = ( IN | OUT ) & 0x00000003
+	 */
+	or	T1, IN, OUT
+	andi	T1, 0x3
+
+	/* Load constant */
+	lui	X0, %hi(CONSTANT_1)
+	lui	X1, %hi(CONSTANT_2)
+	lui	X2, %hi(CONSTANT_3)
+	lui	X3, %hi(CONSTANT_4)
+	ori	X0, %lo(CONSTANT_1)
+	ori	X1, %lo(CONSTANT_2)
+	ori	X2, %lo(CONSTANT_3)
+	ori	X3, %lo(CONSTANT_4)
+
+	/* Store constant on stack. */
+	sw	X0,  0+CONSTANT_OFS_SP($sp)
+	sw	X1,  4+CONSTANT_OFS_SP($sp)
+	sw	X2,  8+CONSTANT_OFS_SP($sp)
+	sw	X3, 12+CONSTANT_OFS_SP($sp)
+
+	sw	T1, UNALIGNED_OFS_SP($sp)
+
+	.set	noreorder
+	b	.Lchacha20_rounds_start
+	andi	BYTES, (CHACHA20_BLOCK_SIZE-1)
+	.set	reorder
+
+.align 4
+.Loop_chacha20_rounds:
+	addiu	IN,  CHACHA20_BLOCK_SIZE
+	addiu	OUT, CHACHA20_BLOCK_SIZE
+	addiu	NONCE_0, 1
+
+	lw	X0,  0+CONSTANT_OFS_SP($sp)
+	lw	X1,  4+CONSTANT_OFS_SP($sp)
+	lw	X2,  8+CONSTANT_OFS_SP($sp)
+	lw	X3, 12+CONSTANT_OFS_SP($sp)
+	lw	T1,   UNALIGNED_OFS_SP($sp)
+
+.Lchacha20_rounds_start:
+	lw	X4,   0(KEY)
+	lw	X5,   4(KEY)
+	lw	X6,   8(KEY)
+	lw	X7,  12(KEY)
+	lw	X8,  16(KEY)
+	lw	X9,  20(KEY)
+	lw	X10, 24(KEY)
+	lw	X11, 28(KEY)
+
+	move	X12, NONCE_0
+	lw	X13,  4(NONCE)
+	lw	X14,  8(NONCE)
+	lw	X15, 12(NONCE)
+
+	li	$at, 9
+.Loop_chacha20_xor_rounds:
+	AXR( 0, 1, 2, 3,  4, 5, 6, 7, 12,13,14,15, 16);
+	AXR( 8, 9,10,11, 12,13,14,15,  4, 5, 6, 7, 12);
+	AXR( 0, 1, 2, 3,  4, 5, 6, 7, 12,13,14,15,  8);
+	AXR( 8, 9,10,11, 12,13,14,15,  4, 5, 6, 7,  7);
+	AXR( 0, 1, 2, 3,  5, 6, 7, 4, 15,12,13,14, 16);
+	AXR(10,11, 8, 9, 15,12,13,14,  5, 6, 7, 4, 12);
+	AXR( 0, 1, 2, 3,  5, 6, 7, 4, 15,12,13,14,  8);
+	AXR(10,11, 8, 9, 15,12,13,14,  5, 6, 7, 4,  7);
+	.set noreorder
+	bnez	$at, .Loop_chacha20_xor_rounds
+	addiu	$at, -1
+
+	/* Unaligned? Jump */
+	bnez	T1, .Loop_chacha20_unaligned
+	andi	$at, BYTES, MASK_U32
+
+	/* Last round? No jump */
+	bne	OUT, PTR_LAST_ROUND, .Lchacha20_mips_xor_aligned_64_b
+	/* Load upper half of jump table addr */
+	lui	T0, %hi(.Lchacha20_mips_jmptbl_aligned_0)
+
+	/* Full block? Jump */
+	beqz	BYTES, .Lchacha20_mips_xor_aligned_64_b
+	/* Calculate lower half jump table addr and offset */
+	ins	T0, $at, 2, 6
+
+	subu	T0, $at
+	addiu	T0, %lo(.Lchacha20_mips_jmptbl_aligned_0)
+
+	jr	T0
+	/* Delay slot */
+	nop
+
+	.set	reorder
+
+.Loop_chacha20_unaligned:
+	.set noreorder
+
+	/* Last round? no jump */
+	bne	OUT, PTR_LAST_ROUND, .Lchacha20_mips_xor_unaligned_64_b
+	/* Load upper half of jump table addr */
+	lui	T0, %hi(.Lchacha20_mips_jmptbl_unaligned_0)
+
+	/* Full block? Jump */
+	beqz	BYTES, .Lchacha20_mips_xor_unaligned_64_b
+
+	/* Calculate lower half jump table addr and offset */
+	ins     T0, $at, 2, 6
+	subu	T0, $at
+	addiu	T0, %lo(.Lchacha20_mips_jmptbl_unaligned_0)
+
+	jr	T0
+	/* Delay slot */
+	nop
+
+	.set	reorder
+
+/* Aligned code path
+ */
+.align 4
+	STORE_ALIGNED(64, 15, NONCE,12)
+	STORE_ALIGNED(60, 14, NONCE, 8)
+	STORE_ALIGNED(56, 13, NONCE, 4)
+	STORE_ALIGNED(52, 12, NONCE, 0)
+	STORE_ALIGNED(48, 11, KEY, 28)
+	STORE_ALIGNED(44, 10, KEY, 24)
+	STORE_ALIGNED(40,  9, KEY, 20)
+	STORE_ALIGNED(36,  8, KEY, 16)
+	STORE_ALIGNED(32,  7, KEY, 12)
+	STORE_ALIGNED(28,  6, KEY,  8)
+	STORE_ALIGNED(24,  5, KEY,  4)
+	STORE_ALIGNED(20,  4, KEY,  0)
+	STORE_ALIGNED(16,  3, $sp, 12+CONSTANT_OFS_SP)
+	STORE_ALIGNED(12,  2, $sp,  8+CONSTANT_OFS_SP)
+	STORE_ALIGNED( 8,  1, $sp,  4+CONSTANT_OFS_SP)
+.Lchacha20_mips_xor_aligned_4_b:
+	/* STORE_ALIGNED( 4,  0, $sp, 0+CONSTANT_OFS_SP) */
+	lw	T0, 0+CONSTANT_OFS_SP($sp)
+	lw	T1, 0(IN)
+	addu	X0, T0
+	CPU_TO_LE32(X0)
+	xor	X0, T1
+	.set noreorder
+	bne	OUT, PTR_LAST_ROUND, .Loop_chacha20_rounds
+	sw	X0, 0(OUT)
+	.set reorder
+
+	.set noreorder
+	bne	$at, BYTES, .Lchacha20_mips_xor_bytes
+	/* Empty delayslot, Increase NONCE_0, return NONCE_0 value */
+	addiu	NONCE_0, 1
+	.set noreorder
+
+.Lchacha20_mips_xor_done:
+	/* Restore used registers */
+	lw	$ra,  0($sp)
+	lw	$fp,  4($sp)
+	lw	$s0,  8($sp)
+	lw	$s1, 12($sp)
+	lw	$s2, 16($sp)
+	lw	$s3, 20($sp)
+	lw	$s4, 24($sp)
+	lw	$s5, 28($sp)
+	lw	$s6, 32($sp)
+	lw	$s7, 36($sp)
+.Lchacha20_mips_end:
+	.set noreorder
+	jr	$ra
+	addiu	$sp, STACK_SIZE
+	.set reorder
+
+	.set noreorder
+	/* Start jump table */
+	JMPTBL_ALIGNED( 0,  0, $sp,  0+CONSTANT_OFS_SP)
+	JMPTBL_ALIGNED( 4,  1, $sp,  4+CONSTANT_OFS_SP)
+	JMPTBL_ALIGNED( 8,  2, $sp,  8+CONSTANT_OFS_SP)
+	JMPTBL_ALIGNED(12,  3, $sp, 12+CONSTANT_OFS_SP)
+	JMPTBL_ALIGNED(16,  4, KEY,  0)
+	JMPTBL_ALIGNED(20,  5, KEY,  4)
+	JMPTBL_ALIGNED(24,  6, KEY,  8)
+	JMPTBL_ALIGNED(28,  7, KEY, 12)
+	JMPTBL_ALIGNED(32,  8, KEY, 16)
+	JMPTBL_ALIGNED(36,  9, KEY, 20)
+	JMPTBL_ALIGNED(40, 10, KEY, 24)
+	JMPTBL_ALIGNED(44, 11, KEY, 28)
+	JMPTBL_ALIGNED(48, 12, NONCE, 0)
+	JMPTBL_ALIGNED(52, 13, NONCE, 4)
+	JMPTBL_ALIGNED(56, 14, NONCE, 8)
+	JMPTBL_ALIGNED(60, 15, NONCE,12)
+	/* End jump table */
+	.set reorder
+
+/* Unaligned code path
+ */
+	STORE_UNALIGNED(64, 15, NONCE,12)
+	STORE_UNALIGNED(60, 14, NONCE, 8)
+	STORE_UNALIGNED(56, 13, NONCE, 4)
+	STORE_UNALIGNED(52, 12, NONCE, 0)
+	STORE_UNALIGNED(48, 11, KEY, 28)
+	STORE_UNALIGNED(44, 10, KEY, 24)
+	STORE_UNALIGNED(40,  9, KEY, 20)
+	STORE_UNALIGNED(36,  8, KEY, 16)
+	STORE_UNALIGNED(32,  7, KEY, 12)
+	STORE_UNALIGNED(28,  6, KEY,  8)
+	STORE_UNALIGNED(24,  5, KEY,  4)
+	STORE_UNALIGNED(20,  4, KEY,  0)
+	STORE_UNALIGNED(16,  3, $sp, 12+CONSTANT_OFS_SP)
+	STORE_UNALIGNED(12,  2, $sp,  8+CONSTANT_OFS_SP)
+	STORE_UNALIGNED( 8,  1, $sp,  4+CONSTANT_OFS_SP)
+.Lchacha20_mips_xor_unaligned_4_b:
+	/* STORE_UNALIGNED( 4,  0, $sp, 0+CONSTANT_OFS_SP) */
+	lw	T0, 0+CONSTANT_OFS_SP($sp)
+	lwl	T1, 0+MSB(IN)
+	lwr	T1, 0+LSB(IN)
+	addu	X0, T0
+	CPU_TO_LE32(X0)
+	xor	X0, T1
+	swl	X0, 0+MSB(OUT)
+	.set noreorder
+	bne	OUT, PTR_LAST_ROUND, .Loop_chacha20_rounds
+	swr	X0, 0+LSB(OUT)
+	.set reorder
+
+	/* Fall through to byte handling */
+	.set noreorder
+	beq	$at, BYTES, .Lchacha20_mips_xor_done
+	/* Empty delayslot, increase NONCE_0, return NONCE_0 value */
+.Lchacha20_mips_xor_unaligned_0_b:
+.Lchacha20_mips_xor_aligned_0_b:
+	addiu	NONCE_0, 1
+	.set reorder
+
+.Lchacha20_mips_xor_bytes:
+	addu	OUT, $at
+	addu	IN, $at
+	addu	SAVED_X, SAVED_CA
+	/* First byte */
+	lbu	T1, 0(IN)
+	andi	$at, BYTES, 2
+	CPU_TO_LE32(SAVED_X)
+	ROTR(SAVED_X)
+	xor	T1, SAVED_X
+	.set noreorder
+	beqz	$at, .Lchacha20_mips_xor_done
+	sb	T1, 0(OUT)
+	.set reorder
+	/* Second byte */
+	lbu	T1, 1(IN)
+	andi	$at, BYTES, 1
+	ROTx	SAVED_X, 8
+	xor	T1, SAVED_X
+	.set noreorder
+	beqz	$at, .Lchacha20_mips_xor_done
+	sb	T1, 1(OUT)
+	.set reorder
+	/* Third byte */
+	lbu	T1, 2(IN)
+	ROTx	SAVED_X, 8
+	xor	T1, SAVED_X
+	.set noreorder
+	b	.Lchacha20_mips_xor_done
+	sb	T1, 2(OUT)
+	.set reorder
+.set noreorder
+
+.Lchacha20_mips_jmptbl_unaligned:
+	/* Start jump table */
+	JMPTBL_UNALIGNED( 0,  0, $sp,  0+CONSTANT_OFS_SP)
+	JMPTBL_UNALIGNED( 4,  1, $sp,  4+CONSTANT_OFS_SP)
+	JMPTBL_UNALIGNED( 8,  2, $sp,  8+CONSTANT_OFS_SP)
+	JMPTBL_UNALIGNED(12,  3, $sp, 12+CONSTANT_OFS_SP)
+	JMPTBL_UNALIGNED(16,  4, KEY,  0)
+	JMPTBL_UNALIGNED(20,  5, KEY,  4)
+	JMPTBL_UNALIGNED(24,  6, KEY,  8)
+	JMPTBL_UNALIGNED(28,  7, KEY, 12)
+	JMPTBL_UNALIGNED(32,  8, KEY, 16)
+	JMPTBL_UNALIGNED(36,  9, KEY, 20)
+	JMPTBL_UNALIGNED(40, 10, KEY, 24)
+	JMPTBL_UNALIGNED(44, 11, KEY, 28)
+	JMPTBL_UNALIGNED(48, 12, NONCE, 0)
+	JMPTBL_UNALIGNED(52, 13, NONCE, 4)
+	JMPTBL_UNALIGNED(56, 14, NONCE, 8)
+	JMPTBL_UNALIGNED(60, 15, NONCE,12)
+	/* End jump table */
+.set reorder
+
+.end chacha20_mips
+.set at
-- 
2.18.0