[PATCH 5/7] x86: Add AVX2 optimized chacha20

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

It adds vectorized ChaCha20 implementation based on libgcrypt
cipher/chacha20-amd64-avx2.S.  It is used only if AVX2 is supported
and enabled by the architecture.

On a Ryzen 9 5900X it shows the following improvements (using
formatted bench-arc4random data):

SSSE3:
Function                                 MB/s
--------------------------------------------------
arc4random [single-thread]               576.55
arc4random_buf(0) [single-thread]        961.77
arc4random_buf(16) [single-thread]       1309.38
arc4random_buf(32) [single-thread]       1558.69
arc4random_buf(64) [single-thread]       1728.54
--------------------------------------------------
arc4random [multi-thread]                589.52
arc4random_buf(0) [multi-thread]         967.39
arc4random_buf(16) [multi-thread]        1319.27
arc4random_buf(32) [multi-thread]        1552.96
arc4random_buf(64) [multi-thread]        1734.27
--------------------------------------------------

AVX2:
Function                                 MB/s
--------------------------------------------------
arc4random [single-thread]               672.49
arc4random_buf(0) [single-thread]        1234.85
arc4random_buf(16) [single-thread]       1892.67
arc4random_buf(32) [single-thread]       2491.10
arc4random_buf(64) [single-thread]       2696.27
--------------------------------------------------
arc4random [multi-thread]                661.25
arc4random_buf(0) [multi-thread]         1214.65
arc4random_buf(16) [multi-thread]        1867.98
arc4random_buf(32) [multi-thread]        2474.70
arc4random_buf(64) [multi-thread]        2893.21
--------------------------------------------------

Checked on x86_64-linux-gnu.
---
 LICENSES                       |   4 +-
 stdlib/chacha20.c              |   7 +-
 sysdeps/x86_64/Makefile        |   1 +
 sysdeps/x86_64/chacha20-avx2.S | 317 +++++++++++++++++++++++++++++++++
 sysdeps/x86_64/chacha20_arch.h |  14 ++
 5 files changed, 339 insertions(+), 4 deletions(-)
 create mode 100644 sysdeps/x86_64/chacha20-avx2.S

diff --git a/LICENSES b/LICENSES
index 2563abd9e2..8ef0f023d7 100644
--- a/LICENSES
+++ b/LICENSES
@@ -390,8 +390,8 @@ Copyright 2001 by Stephen L. Moshier <moshier@na-net.ornl.gov>
  License along with this library; if not, see
  <https://www.gnu.org/licenses/>.  */
 \f
-sysdeps/x86_64/chacha20-ssse3.S import code from libgcrypt, with the
-following notices:
+sysdeps/x86_64/chacha20-ssse3.S and sysdeps/x86_64/chacha20-avx2.S
+import code from libgcrypt, with the following notices:
 
 Copyright (C) 2017-2019 Jussi Kivilinna <jussi.kivilinna@iki.fi>
 
diff --git a/stdlib/chacha20.c b/stdlib/chacha20.c
index dbd87bd942..8569e1e78d 100644
--- a/stdlib/chacha20.c
+++ b/stdlib/chacha20.c
@@ -190,8 +190,8 @@ memxorcpy (uint8_t *dst, const uint8_t *src1, const uint8_t *src2, size_t len)
 }
 
 static void
-chacha20_crypt (struct chacha20_state *state, uint8_t *dst,
-		const uint8_t *src, size_t bytes)
+chacha20_crypt_generic (struct chacha20_state *state, uint8_t *dst,
+			const uint8_t *src, size_t bytes)
 {
   uint8_t stream[CHACHA20_BLOCK_SIZE];
 
@@ -209,3 +209,6 @@ chacha20_crypt (struct chacha20_state *state, uint8_t *dst,
       memxorcpy (dst, src, stream, bytes);
     }
 }
+
+/* Get the arch-optimized implementation, if any.  */
+#include <chacha20_arch.h>
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
index f43b6a1180..afb4d173e8 100644
--- a/sysdeps/x86_64/Makefile
+++ b/sysdeps/x86_64/Makefile
@@ -7,6 +7,7 @@ endif
 
 ifeq ($(subdir),stdlib)
 sysdep_routines += \
+  chacha20-avx2 \
   chacha20-ssse3 \
   # sysdep_routines
 endif
diff --git a/sysdeps/x86_64/chacha20-avx2.S b/sysdeps/x86_64/chacha20-avx2.S
new file mode 100644
index 0000000000..96174c0e40
--- /dev/null
+++ b/sysdeps/x86_64/chacha20-avx2.S
@@ -0,0 +1,317 @@
+/* Optimized AVX2 implementation of ChaCha20 cipher.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+/* Based on D. J. Bernstein reference implementation at
+   http://cr.yp.to/chacha.html:
+
+   chacha-regs.c version 20080118
+   D. J. Bernstein
+   Public domain.  */
+
+#ifdef PIC
+#  define rRIP (%rip)
+#else
+#  define rRIP
+#endif
+
+/* register macros */
+#define INPUT %rdi
+#define DST   %rsi
+#define SRC   %rdx
+#define NBLKS %rcx
+#define ROUND %eax
+
+/* stack structure */
+#define STACK_VEC_X12 (32)
+#define STACK_VEC_X13 (32 + STACK_VEC_X12)
+#define STACK_TMP     (32 + STACK_VEC_X13)
+#define STACK_TMP1    (32 + STACK_TMP)
+
+#define STACK_MAX     (32 + STACK_TMP1)
+
+/* vector registers */
+#define X0 %ymm0
+#define X1 %ymm1
+#define X2 %ymm2
+#define X3 %ymm3
+#define X4 %ymm4
+#define X5 %ymm5
+#define X6 %ymm6
+#define X7 %ymm7
+#define X8 %ymm8
+#define X9 %ymm9
+#define X10 %ymm10
+#define X11 %ymm11
+#define X12 %ymm12
+#define X13 %ymm13
+#define X14 %ymm14
+#define X15 %ymm15
+
+#define X0h %xmm0
+#define X1h %xmm1
+#define X2h %xmm2
+#define X3h %xmm3
+#define X4h %xmm4
+#define X5h %xmm5
+#define X6h %xmm6
+#define X7h %xmm7
+#define X8h %xmm8
+#define X9h %xmm9
+#define X10h %xmm10
+#define X11h %xmm11
+#define X12h %xmm12
+#define X13h %xmm13
+#define X14h %xmm14
+#define X15h %xmm15
+
+/**********************************************************************
+  helper macros
+ **********************************************************************/
+
+/* 4x4 32-bit integer matrix transpose */
+#define transpose_4x4(x0,x1,x2,x3,t1,t2) \
+	vpunpckhdq x1, x0, t2; \
+	vpunpckldq x1, x0, x0; \
+	\
+	vpunpckldq x3, x2, t1; \
+	vpunpckhdq x3, x2, x2; \
+	\
+	vpunpckhqdq t1, x0, x1; \
+	vpunpcklqdq t1, x0, x0; \
+	\
+	vpunpckhqdq x2, t2, x3; \
+	vpunpcklqdq x2, t2, x2;
+
+/* 2x2 128-bit matrix transpose */
+#define transpose_16byte_2x2(x0,x1,t1) \
+	vmovdqa    x0, t1; \
+	vperm2i128 $0x20, x1, x0, x0; \
+	vperm2i128 $0x31, x1, t1, x1;
+
+/* xor register with unaligned src and save to unaligned dst */
+#define xor_src_dst(dst, src, offset, xreg) \
+	vpxor offset(src), xreg, xreg; \
+	vmovdqu xreg, offset(dst);
+
+/**********************************************************************
+  8-way chacha20
+ **********************************************************************/
+
+#define ROTATE2(v1,v2,c,tmp)	\
+	vpsrld $(32 - (c)), v1, tmp;	\
+	vpslld $(c), v1, v1;		\
+	vpaddb tmp, v1, v1;		\
+	vpsrld $(32 - (c)), v2, tmp;	\
+	vpslld $(c), v2, v2;		\
+	vpaddb tmp, v2, v2;
+
+#define ROTATE_SHUF_2(v1,v2,shuf)	\
+	vpshufb shuf, v1, v1;		\
+	vpshufb shuf, v2, v2;
+
+#define XOR(ds,s) \
+	vpxor s, ds, ds;
+
+#define PLUS(ds,s) \
+	vpaddd s, ds, ds;
+
+#define QUARTERROUND2(a1,b1,c1,d1,a2,b2,c2,d2,ign,tmp1,\
+		      interleave_op1,interleave_op2,\
+		      interleave_op3,interleave_op4)		\
+	vbroadcasti128 .Lshuf_rol16 rRIP, tmp1;			\
+		interleave_op1;					\
+	PLUS(a1,b1); PLUS(a2,b2); XOR(d1,a1); XOR(d2,a2);	\
+	    ROTATE_SHUF_2(d1, d2, tmp1);			\
+		interleave_op2;					\
+	PLUS(c1,d1); PLUS(c2,d2); XOR(b1,c1); XOR(b2,c2);	\
+	    ROTATE2(b1, b2, 12, tmp1);				\
+	vbroadcasti128 .Lshuf_rol8 rRIP, tmp1;			\
+		interleave_op3;					\
+	PLUS(a1,b1); PLUS(a2,b2); XOR(d1,a1); XOR(d2,a2);	\
+	    ROTATE_SHUF_2(d1, d2, tmp1);			\
+		interleave_op4;					\
+	PLUS(c1,d1); PLUS(c2,d2); XOR(b1,c1); XOR(b2,c2);	\
+	    ROTATE2(b1, b2,  7, tmp1);
+
+	.text
+	.align 32
+chacha20_data:
+L(shuf_rol16):
+	.byte 2,3,0,1,6,7,4,5,10,11,8,9,14,15,12,13
+L(shuf_rol8):
+	.byte 3,0,1,2,7,4,5,6,11,8,9,10,15,12,13,14
+L(inc_counter):
+	.byte 0,1,2,3,4,5,6,7
+L(unsigned_cmp):
+	.long 0x80000000
+
+ENTRY (__chacha20_avx2_blocks8)
+	/* input:
+	 *	%rdi: input
+	 *	%rsi: dst
+	 *	%rdx: src
+	 *	%rcx: nblks (multiple of 8)
+	 */
+	vzeroupper;
+
+	pushq %rbp;
+	cfi_adjust_cfa_offset(8);
+	cfi_rel_offset(rbp, 0)
+	movq %rsp, %rbp;
+	cfi_def_cfa_register(rbp);
+
+	subq $STACK_MAX, %rsp;
+	andq $~31, %rsp;
+
+L(loop8):
+	mov $20, ROUND;
+
+	/* Construct counter vectors X12 and X13 */
+	vpmovzxbd L(inc_counter) rRIP, X0;
+	vpbroadcastd L(unsigned_cmp) rRIP, X2;
+	vpbroadcastd (12 * 4)(INPUT), X12;
+	vpbroadcastd (13 * 4)(INPUT), X13;
+	vpaddd X0, X12, X12;
+	vpxor X2, X0, X0;
+	vpxor X2, X12, X1;
+	vpcmpgtd X1, X0, X0;
+	vpsubd X0, X13, X13;
+	vmovdqa X12, (STACK_VEC_X12)(%rsp);
+	vmovdqa X13, (STACK_VEC_X13)(%rsp);
+
+	/* Load vectors */
+	vpbroadcastd (0 * 4)(INPUT), X0;
+	vpbroadcastd (1 * 4)(INPUT), X1;
+	vpbroadcastd (2 * 4)(INPUT), X2;
+	vpbroadcastd (3 * 4)(INPUT), X3;
+	vpbroadcastd (4 * 4)(INPUT), X4;
+	vpbroadcastd (5 * 4)(INPUT), X5;
+	vpbroadcastd (6 * 4)(INPUT), X6;
+	vpbroadcastd (7 * 4)(INPUT), X7;
+	vpbroadcastd (8 * 4)(INPUT), X8;
+	vpbroadcastd (9 * 4)(INPUT), X9;
+	vpbroadcastd (10 * 4)(INPUT), X10;
+	vpbroadcastd (11 * 4)(INPUT), X11;
+	vpbroadcastd (14 * 4)(INPUT), X14;
+	vpbroadcastd (15 * 4)(INPUT), X15;
+	vmovdqa X15, (STACK_TMP)(%rsp);
+
+L(round2):
+	QUARTERROUND2(X0, X4,  X8, X12,   X1, X5,  X9, X13, tmp:=,X15,,,,)
+	vmovdqa (STACK_TMP)(%rsp), X15;
+	vmovdqa X8, (STACK_TMP)(%rsp);
+	QUARTERROUND2(X2, X6, X10, X14,   X3, X7, X11, X15, tmp:=,X8,,,,)
+	QUARTERROUND2(X0, X5, X10, X15,   X1, X6, X11, X12, tmp:=,X8,,,,)
+	vmovdqa (STACK_TMP)(%rsp), X8;
+	vmovdqa X15, (STACK_TMP)(%rsp);
+	QUARTERROUND2(X2, X7,  X8, X13,   X3, X4,  X9, X14, tmp:=,X15,,,,)
+	sub $2, ROUND;
+	jnz L(round2);
+
+	vmovdqa X8, (STACK_TMP1)(%rsp);
+
+	/* tmp := X15 */
+	vpbroadcastd (0 * 4)(INPUT), X15;
+	PLUS(X0, X15);
+	vpbroadcastd (1 * 4)(INPUT), X15;
+	PLUS(X1, X15);
+	vpbroadcastd (2 * 4)(INPUT), X15;
+	PLUS(X2, X15);
+	vpbroadcastd (3 * 4)(INPUT), X15;
+	PLUS(X3, X15);
+	vpbroadcastd (4 * 4)(INPUT), X15;
+	PLUS(X4, X15);
+	vpbroadcastd (5 * 4)(INPUT), X15;
+	PLUS(X5, X15);
+	vpbroadcastd (6 * 4)(INPUT), X15;
+	PLUS(X6, X15);
+	vpbroadcastd (7 * 4)(INPUT), X15;
+	PLUS(X7, X15);
+	transpose_4x4(X0, X1, X2, X3, X8, X15);
+	transpose_4x4(X4, X5, X6, X7, X8, X15);
+	vmovdqa (STACK_TMP1)(%rsp), X8;
+	transpose_16byte_2x2(X0, X4, X15);
+	transpose_16byte_2x2(X1, X5, X15);
+	transpose_16byte_2x2(X2, X6, X15);
+	transpose_16byte_2x2(X3, X7, X15);
+	vmovdqa (STACK_TMP)(%rsp), X15;
+	xor_src_dst(DST, SRC, (64 * 0 + 16 * 0), X0);
+	xor_src_dst(DST, SRC, (64 * 1 + 16 * 0), X1);
+	vpbroadcastd (8 * 4)(INPUT), X0;
+	PLUS(X8, X0);
+	vpbroadcastd (9 * 4)(INPUT), X0;
+	PLUS(X9, X0);
+	vpbroadcastd (10 * 4)(INPUT), X0;
+	PLUS(X10, X0);
+	vpbroadcastd (11 * 4)(INPUT), X0;
+	PLUS(X11, X0);
+	vmovdqa (STACK_VEC_X12)(%rsp), X0;
+	PLUS(X12, X0);
+	vmovdqa (STACK_VEC_X13)(%rsp), X0;
+	PLUS(X13, X0);
+	vpbroadcastd (14 * 4)(INPUT), X0;
+	PLUS(X14, X0);
+	vpbroadcastd (15 * 4)(INPUT), X0;
+	PLUS(X15, X0);
+	xor_src_dst(DST, SRC, (64 * 2 + 16 * 0), X2);
+	xor_src_dst(DST, SRC, (64 * 3 + 16 * 0), X3);
+
+	/* Update counter */
+	addq $8, (12 * 4)(INPUT);
+
+	transpose_4x4(X8, X9, X10, X11, X0, X1);
+	transpose_4x4(X12, X13, X14, X15, X0, X1);
+	xor_src_dst(DST, SRC, (64 * 4 + 16 * 0), X4);
+	xor_src_dst(DST, SRC, (64 * 5 + 16 * 0), X5);
+	transpose_16byte_2x2(X8, X12, X0);
+	transpose_16byte_2x2(X9, X13, X0);
+	transpose_16byte_2x2(X10, X14, X0);
+	transpose_16byte_2x2(X11, X15, X0);
+	xor_src_dst(DST, SRC, (64 * 6 + 16 * 0), X6);
+	xor_src_dst(DST, SRC, (64 * 7 + 16 * 0), X7);
+	xor_src_dst(DST, SRC, (64 * 0 + 16 * 2), X8);
+	xor_src_dst(DST, SRC, (64 * 1 + 16 * 2), X9);
+	xor_src_dst(DST, SRC, (64 * 2 + 16 * 2), X10);
+	xor_src_dst(DST, SRC, (64 * 3 + 16 * 2), X11);
+	xor_src_dst(DST, SRC, (64 * 4 + 16 * 2), X12);
+	xor_src_dst(DST, SRC, (64 * 5 + 16 * 2), X13);
+	xor_src_dst(DST, SRC, (64 * 6 + 16 * 2), X14);
+	xor_src_dst(DST, SRC, (64 * 7 + 16 * 2), X15);
+
+	sub $8, NBLKS;
+	lea (8 * 64)(DST), DST;
+	lea (8 * 64)(SRC), SRC;
+	jnz L(loop8);
+
+	/* clear the used vector registers and stack */
+	vpxor X0, X0, X0;
+	vmovdqa X0, (STACK_VEC_X12)(%rsp);
+	vmovdqa X0, (STACK_VEC_X13)(%rsp);
+	vmovdqa X0, (STACK_TMP)(%rsp);
+	vmovdqa X0, (STACK_TMP1)(%rsp);
+	vzeroall;
+
+	/* eax zeroed by round loop. */
+	leave;
+	cfi_adjust_cfa_offset(-8)
+	cfi_def_cfa_register(%rsp);
+	ret;
+	int3;
+END(__chacha20_avx2_blocks8)
diff --git a/sysdeps/x86_64/chacha20_arch.h b/sysdeps/x86_64/chacha20_arch.h
index 37a4fdfb1f..7e9e7755f3 100644
--- a/sysdeps/x86_64/chacha20_arch.h
+++ b/sysdeps/x86_64/chacha20_arch.h
@@ -22,11 +22,25 @@
 
 unsigned int __chacha20_ssse3_blocks8 (uint32_t *state, uint8_t *dst,
 				       const uint8_t *src, size_t nblks);
+unsigned int __chacha20_avx2_blocks8 (uint32_t *state, uint8_t *dst,
+				      const uint8_t *src, size_t nblks);
 
 static inline void
 chacha20_crypt (struct chacha20_state *state, uint8_t *dst, const uint8_t *src,
 		size_t bytes)
 {
+  const struct cpu_features* cpu_features = __get_cpu_features ();
+
+  if (CPU_FEATURE_USABLE_P (cpu_features, AVX2) && bytes >= CHACHA20_BLOCK_SIZE * 8)
+    {
+      size_t nblocks = bytes / CHACHA20_BLOCK_SIZE;
+      nblocks -= nblocks % 8;
+      __chacha20_avx2_blocks8 (state->ctx, dst, src, nblocks);
+      bytes -= nblocks * CHACHA20_BLOCK_SIZE;
+      dst += nblocks * CHACHA20_BLOCK_SIZE;
+      src += nblocks * CHACHA20_BLOCK_SIZE;
+    }
+
   if (CPU_FEATURE_USABLE_P (cpu_features, SSSE3) && bytes >= CHACHA20_BLOCK_SIZE * 4)
     {
       size_t nblocks = bytes / CHACHA20_BLOCK_SIZE;
-- 
2.32.0