armv8 has support for optional CRC32C instructions. This patch checks if they are

available and if that is true make use of them.
Thank you very much to Andrew Turner for providing help and review the patch!
Reviewed by:		andrew
MFC after:		1 week
Differential Revision:	https://reviews.freebsd.org/D10499

sys/conf/files.arm64

@@ -191,6 +191,7 @@ libkern/fls.c			standard
 libkern/flsl.c			standard
 libkern/flsll.c			standard
 libkern/memset.c		standard
+libkern/arm64/crc32c_armv8.S	standard
 cddl/contrib/opensolaris/common/atomic/aarch64/opensolaris_atomic.S	optional zfs | dtrace compile-with "${CDDL_C}"
 cddl/dev/dtrace/aarch64/dtrace_asm.S			optional dtrace compile-with "${DTRACE_S}"
 cddl/dev/dtrace/aarch64/dtrace_subr.c			optional dtrace compile-with "${DTRACE_C}"

sys/libkern/arm64/crc32c_armv8.S

@@ -0,0 +1,78 @@
+/*-
+ * Copyright (c) 2017 Michael Tuexen
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ * uint32_t
+ * armv8_crc32c(uint32_t crc, const unsigned char *buf, unsigned int len)
+ */
+
+ENTRY(armv8_crc32c)
+	cbz	w2, end
+	tbz	x1, #0x0, half_word_aligned
+	sub	w2, w2, 0x1
+	ldr	w10, [x1], #0x1
+	crc32cb	w0, w0, w10
+half_word_aligned:
+	cmp	w2, #0x2
+	b.lo	last_byte
+	tbz	x1, #0x1, word_aligned
+	sub	w2, w2, 0x2
+	ldr	w10, [x1], #0x2
+	crc32ch	w0, w0, w10
+word_aligned:
+	cmp	w2, #0x4
+	b.lo	last_half_word
+	tbz	x1, #0x2, double_word_aligned
+	sub	w2, w2, 0x4
+	ldr	w10, [x1], #0x4
+	crc32cw	w0, w0, w10
+double_word_aligned:
+	lsr	w9, w2, #0x3
+	cbz	w9, last_word
+loop:
+	ldr	x10, [x1], #0x8
+	crc32cx	w0, w0, x10
+	subs	w9, w9, #1
+	b.ne	loop
+last_word:
+	tbz	w2, #0x2, last_half_word
+	ldr	w10, [x1], #0x4
+	crc32cw	w0, w0, w10
+last_half_word:
+	tbz	w2, #0x1, last_byte
+	ldr	w10, [x1], #0x2
+	crc32ch	w0, w0, w10
+last_byte:
+	tbz	w2, #0x0, end 
+	ldr	w10, [x1], #0x1
+	crc32cb	w0, w0, w10
+end:
+	ret
+END(armv8_crc32c)

sys/libkern/crc32.c

@@ -54,6 +54,10 @@ __FBSDID("$FreeBSD$");
 #include <machine/specialreg.h>
 #endif
 
+#if defined(__aarch64__)
+#include <machine/cpu.h>
+#endif
+
 const uint32_t crc32_tab[] = {
 	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
 	0xe963a535, 0x9e6495a3,	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
@@ -759,6 +763,18 @@ calculate_crc32c(uint32_t crc32c,
 	if ((cpu_feature2 & CPUID2_SSE42) != 0) {
 		return (sse42_crc32c(crc32c, buffer, length));
 	} else
+#endif
+#if defined(__aarch64__)
+	uint64_t reg;
+
+	/*
+	 * We only test for CRC32 support on the CPU with index 0 assuming that
+	 * this applies to all CPUs.
+	 */
+	reg = READ_SPECIALREG(id_aa64isar0_el1);
+	if (ID_AA64ISAR0_CRC32(reg) != ID_AA64ISAR0_CRC32_NONE) {
+		return (armv8_crc32c(crc32c, buffer, length));
+	} else
 #endif
 	if (length < 4) {
 		return (singletable_crc32c(crc32c, buffer, length));

sys/sys/libkern.h

@@ -210,6 +210,9 @@ calculate_crc32c(uint32_t crc32c, const unsigned char *buffer,
 #if defined(__amd64__) || defined(__i386__)
 uint32_t sse42_crc32c(uint32_t, const unsigned char *, unsigned);
 #endif
+#if defined(__aarch64__)
+uint32_t armv8_crc32c(uint32_t, const unsigned char *, unsigned int);
+#endif
 #endif
 
 

tests/sys/kern/Makefile

@@ -30,10 +30,16 @@ NETBSD_ATF_TESTS_C+=	mqueue_test
 CFLAGS.mqueue_test+=	-I${SRCTOP}/tests
 LIBADD.mqueue_test+=	rt
 
-.if ${MACHINE_ARCH} == "amd64" || ${MACHINE_ARCH} == "i386"
+.if ${MACHINE_ARCH} == "amd64" || \
+    ${MACHINE_ARCH} == "i386" || \
+    ${MACHINE_ARCH} == "aarch64"
 ATF_TESTS_C+=	libkern_crc32
 CFLAGS.libkern_crc32+=	-DUSERSPACE_TESTING
+.if ${MACHINE_ARCH} == "amd64" || ${MACHINE_ARCH} == "i386"
 LDADD.libkern_crc32+=	${SRCTOP}/sys/libkern/x86/crc32_sse42.c
+.else
+LDADD.libkern_crc32+=	${SRCTOP}/sys/libkern/arm64/crc32c_armv8.S
+.endif
 .endif
 
 # subr_unit.c contains functions whose prototypes lie in headers that cannot be

tests/sys/kern/libkern_crc32.c

@@ -32,7 +32,13 @@
 
 #include <atf-c.h>
 
+#if defined(__amd64__) || defined(__i386__)
 extern uint32_t sse42_crc32c(uint32_t, const unsigned char *, unsigned);
+#elif defined(__aarch64__)
+extern uint32_t armv8_crc32c(uint32_t, const unsigned char *, unsigned);
+#else
+#error These tests are not supported on this platform
+#endif
 
 ATF_TC_WITHOUT_HEAD(crc32c_basic_correctness);
 ATF_TC_BODY(crc32c_basic_correctness, tc)
@@ -79,8 +85,13 @@ ATF_TC_BODY(crc32c_basic_correctness, tc)
 	ATF_REQUIRE(nitems(inputs) == nitems(results));
 
 	for (i = 0; i < nitems(inputs); i++) {
+#if defined(__amd64__) || defined(__i386__)
 		act = sse42_crc32c(~0, (const void *)&inputs[i],
 		    sizeof(inputs[0]));
+#else
+		act = armv8_crc32c(~0, (const void *)&inputs[i],
+		    sizeof(inputs[0]));
+#endif
 		ATF_REQUIRE_MSG(act == results[i],
 		    "crc32c(0x%jx) = 0x%08x, got 0x%08x", (uintmax_t)inputs[i],
 		    results[i], act);
@@ -100,7 +111,11 @@ ATF_TC_BODY(crc32c_alignment, tc)
 	for (i = 1; i < 8; i++) {
 		memcpy(&buf[i], &input, sizeof(input));
 
+#if defined(__amd64__) || defined(__i386__)
 		act = sse42_crc32c(~0, (const void *)&buf[i], sizeof(input));
+#else
+		act = armv8_crc32c(~0, (const void *)&buf[i], sizeof(input));
+#endif
 		ATF_REQUIRE_MSG(act == result,
 		    "crc32c(0x%jx) = 0x%08x, got 0x%08x", (uintmax_t)input,
 		    result, act);
@@ -117,7 +132,11 @@ ATF_TC_BODY(crc32c_trailing_bytes, tc)
 	const uint32_t result = 0xec638d62;
 	uint32_t act;
 
+#if defined(__amd64__) || defined(__i386__)
 	act = sse42_crc32c(~0, input, sizeof(input));
+#else
+	act = armv8_crc32c(~0, input, sizeof(input));
+#endif
 	ATF_REQUIRE_MSG(act == result, "expected 0x%08x, got 0x%08x", result,
 	    act);
 }