cpu: detect zbc extension on riscv64

Change-Id: Icdd4c279693c67982f37c80a891ecadda8ec108a
Reviewed-on: https://go-review.googlesource.com/c/sys/+/776280
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Florian Lehner <lehner.florian86@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

Author: tklauser

cpu/cpu.go

@@ -236,6 +236,7 @@ var RISCV64 struct {
 	HasZba            bool // Address generation instructions extension
 	HasZbb            bool // Basic bit-manipulation extension
 	HasZbs            bool // Single-bit instructions extension
+	HasZbc            bool // Carryless multiplication extension
 	HasZvbb           bool // Vector Basic Bit-manipulation
 	HasZvbc           bool // Vector Carryless Multiplication
 	HasZvkb           bool // Vector Cryptography Bit-manipulation

cpu/cpu_linux_riscv64.go

@@ -58,6 +58,7 @@ const (
 	riscv_HWPROBE_EXT_ZBA         = 0x8
 	riscv_HWPROBE_EXT_ZBB         = 0x10
 	riscv_HWPROBE_EXT_ZBS         = 0x20
+	riscv_HWPROBE_EXT_ZBC         = 0x80
 	riscv_HWPROBE_EXT_ZVBB        = 0x20000
 	riscv_HWPROBE_EXT_ZVBC        = 0x40000
 	riscv_HWPROBE_EXT_ZVKB        = 0x80000
@@ -108,6 +109,7 @@ func doinit() {
 			RISCV64.HasZba = isSet(v, riscv_HWPROBE_EXT_ZBA)
 			RISCV64.HasZbb = isSet(v, riscv_HWPROBE_EXT_ZBB)
 			RISCV64.HasZbs = isSet(v, riscv_HWPROBE_EXT_ZBS)
+			RISCV64.HasZbc = isSet(v, riscv_HWPROBE_EXT_ZBC)
 			RISCV64.HasZvbb = isSet(v, riscv_HWPROBE_EXT_ZVBB)
 			RISCV64.HasZvbc = isSet(v, riscv_HWPROBE_EXT_ZVBC)
 			RISCV64.HasZvkb = isSet(v, riscv_HWPROBE_EXT_ZVKB)

cpu/cpu_riscv64.go

@@ -16,6 +16,7 @@ func initOptions() {
 		{Name: "zba", Feature: &RISCV64.HasZba},
 		{Name: "zbb", Feature: &RISCV64.HasZbb},
 		{Name: "zbs", Feature: &RISCV64.HasZbs},
+		{Name: "zbc", Feature: &RISCV64.HasZbc},
 		// RISC-V Cryptography Extensions
 		{Name: "zvbb", Feature: &RISCV64.HasZvbb},
 		{Name: "zvbc", Feature: &RISCV64.HasZvbc},