cpu: add linux/arm64
Port from Go internal/cpu
Updates golang/go#25185
Change-Id: I8390980e38b61f6c428fafa0665a03952e7b00bb
Reviewed-on: https://go-review.googlesource.com/c/150718
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
diff --git a/cpu/cpu_linux.go b/cpu/cpu_linux.go
new file mode 100644
index 0000000..126bb68
--- /dev/null
+++ b/cpu/cpu_linux.go
@@ -0,0 +1,55 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//+build !amd64,!amd64p32,!386
+
+package cpu
+
+import (
+ "encoding/binary"
+ "io/ioutil"
+)
+
+const (
+ _AT_HWCAP = 16
+ _AT_HWCAP2 = 26
+
+ procAuxv = "/proc/self/auxv"
+
+ uintSize uint = 32 << (^uint(0) >> 63)
+)
+
+// For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
+// These are initialized in cpu_$GOARCH.go
+// and should not be changed after they are initialized.
+var HWCap uint
+var HWCap2 uint
+
+func init() {
+ buf, err := ioutil.ReadFile(procAuxv)
+ if err != nil {
+ panic("read proc auxv failed: " + err.Error())
+ }
+
+ pb := int(uintSize / 8)
+
+ for i := 0; i < len(buf)-pb*2; i += pb * 2 {
+ var tag, val uint
+ switch uintSize {
+ case 32:
+ tag = uint(binary.LittleEndian.Uint32(buf[i:]))
+ val = uint(binary.LittleEndian.Uint32(buf[i+pb:]))
+ case 64:
+ tag = uint(binary.LittleEndian.Uint64(buf[i:]))
+ val = uint(binary.LittleEndian.Uint64(buf[i+pb:]))
+ }
+ switch tag {
+ case _AT_HWCAP:
+ HWCap = val
+ case _AT_HWCAP2:
+ HWCap2 = val
+ }
+ }
+ doinit()
+}
