From 1163acf3eaedf870d069058b540bfef5c470f520 Mon Sep 17 00:00:00 2001
From: Joel Sing <joel@sing.id.au>
Date: Tue, 9 Aug 2022 18:09:46 +1000
Subject: [PATCH] internal/cpu: deduplicate arm64 ISAR parsing code

Deduplicate code for parsing system registers - this matches what is done
in golang.org/x/sys/cpu.

Change-Id: If3524eb2e361179c68678f8214230d7068fe4c60
Reviewed-on: https://go-review.googlesource.com/c/go/+/422217
Reviewed-by: Meng Zhuo <mzh@golangcn.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---
 src/internal/cpu/cpu_arm64.go         | 38 +++++++++++++++++++++++++++
 src/internal/cpu/cpu_arm64_freebsd.go | 36 +------------------------
 src/internal/cpu/cpu_arm64_openbsd.go | 37 +-------------------------
 3 files changed, 40 insertions(+), 71 deletions(-)

diff --git a/src/internal/cpu/cpu_arm64.go b/src/internal/cpu/cpu_arm64.go
index 18ec636112..1d4431753d 100644
--- a/src/internal/cpu/cpu_arm64.go
+++ b/src/internal/cpu/cpu_arm64.go
@@ -30,3 +30,41 @@ func doinit() {
 func getisar0() uint64
 
 func getMIDR() uint64
+
+func extractBits(data uint64, start, end uint) uint {
+	return (uint)(data>>start) & ((1 << (end - start + 1)) - 1)
+}
+
+func parseARM64SystemRegisters(isar0 uint64) {
+	// ID_AA64ISAR0_EL1
+	switch extractBits(isar0, 4, 7) {
+	case 1:
+		ARM64.HasAES = true
+	case 2:
+		ARM64.HasAES = true
+		ARM64.HasPMULL = true
+	}
+
+	switch extractBits(isar0, 8, 11) {
+	case 1:
+		ARM64.HasSHA1 = true
+	}
+
+	switch extractBits(isar0, 12, 15) {
+	case 1:
+		ARM64.HasSHA2 = true
+	case 2:
+		ARM64.HasSHA2 = true
+		ARM64.HasSHA512 = true
+	}
+
+	switch extractBits(isar0, 16, 19) {
+	case 1:
+		ARM64.HasCRC32 = true
+	}
+
+	switch extractBits(isar0, 20, 23) {
+	case 2:
+		ARM64.HasATOMICS = true
+	}
+}
diff --git a/src/internal/cpu/cpu_arm64_freebsd.go b/src/internal/cpu/cpu_arm64_freebsd.go
index 40ebfaf6ff..96ed359ca0 100644
--- a/src/internal/cpu/cpu_arm64_freebsd.go
+++ b/src/internal/cpu/cpu_arm64_freebsd.go
@@ -10,39 +10,5 @@ func osInit() {
 	// Retrieve info from system register ID_AA64ISAR0_EL1.
 	isar0 := getisar0()
 
-	// ID_AA64ISAR0_EL1
-	switch extractBits(isar0, 4, 7) {
-	case 1:
-		ARM64.HasAES = true
-	case 2:
-		ARM64.HasAES = true
-		ARM64.HasPMULL = true
-	}
-
-	switch extractBits(isar0, 8, 11) {
-	case 1:
-		ARM64.HasSHA1 = true
-	}
-
-	switch extractBits(isar0, 12, 15) {
-	case 1:
-		ARM64.HasSHA2 = true
-	case 2:
-		ARM64.HasSHA2 = true
-		ARM64.HasSHA512 = true
-	}
-
-	switch extractBits(isar0, 16, 19) {
-	case 1:
-		ARM64.HasCRC32 = true
-	}
-
-	switch extractBits(isar0, 20, 23) {
-	case 2:
-		ARM64.HasATOMICS = true
-	}
-}
-
-func extractBits(data uint64, start, end uint) uint {
-	return (uint)(data>>start) & ((1 << (end - start + 1)) - 1)
+	parseARM64SystemRegisters(isar0)
 }
diff --git a/src/internal/cpu/cpu_arm64_openbsd.go b/src/internal/cpu/cpu_arm64_openbsd.go
index 54e1f4b931..12593098eb 100644
--- a/src/internal/cpu/cpu_arm64_openbsd.go
+++ b/src/internal/cpu/cpu_arm64_openbsd.go
@@ -15,10 +15,6 @@ const (
 	_CPU_ID_AA64ISAR1 = 3
 )
 
-func extractBits(data uint64, start, end uint) uint {
-	return (uint)(data>>start) & ((1 << (end - start + 1)) - 1)
-}
-
 //go:noescape
 func sysctlUint64(mib []uint32) (uint64, bool)
 
@@ -28,36 +24,5 @@ func osInit() {
 	if !ok {
 		return
 	}
-
-	// ID_AA64ISAR0_EL1
-	switch extractBits(isar0, 4, 7) {
-	case 1:
-		ARM64.HasAES = true
-	case 2:
-		ARM64.HasAES = true
-		ARM64.HasPMULL = true
-	}
-
-	switch extractBits(isar0, 8, 11) {
-	case 1:
-		ARM64.HasSHA1 = true
-	}
-
-	switch extractBits(isar0, 12, 15) {
-	case 1:
-		ARM64.HasSHA2 = true
-	case 2:
-		ARM64.HasSHA2 = true
-		ARM64.HasSHA512 = true
-	}
-
-	switch extractBits(isar0, 16, 19) {
-	case 1:
-		ARM64.HasCRC32 = true
-	}
-
-	switch extractBits(isar0, 20, 23) {
-	case 2:
-		ARM64.HasATOMICS = true
-	}
+	parseARM64SystemRegisters(isar0)
 }
-- 
2.48.1