cpu: support reading arm64 CPU feature registers
This allows to detect ARM64 CPU features on non-Linux systems. On Linux,
this is used in case /proc/self/auxv cannot be read.
Change-Id: I67d55e989f2beda0c05a97ca5e55781840a8e01c
Reviewed-on: https://go-review.googlesource.com/c/sys/+/209478
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/cpu/cpu_linux.go b/cpu/cpu_linux.go
index 10e712d..fe13918 100644
--- a/cpu/cpu_linux.go
+++ b/cpu/cpu_linux.go
@@ -2,58 +2,14 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// +build !amd64,!amd64p32,!386
+// +build !386,!amd64,!amd64p32,!arm64
package cpu
-import (
- "io/ioutil"
-)
-
-const (
- _AT_HWCAP = 16
- _AT_HWCAP2 = 26
-
- procAuxv = "/proc/self/auxv"
-
- uintSize = int(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 {
- // e.g. on android /proc/self/auxv is not accessible, so silently
- // ignore the error and leave Initialized = false
+ if err := readHWCAP(); err != nil {
return
}
-
- bo := hostByteOrder()
- for len(buf) >= 2*(uintSize/8) {
- var tag, val uint
- switch uintSize {
- case 32:
- tag = uint(bo.Uint32(buf[0:]))
- val = uint(bo.Uint32(buf[4:]))
- buf = buf[8:]
- case 64:
- tag = uint(bo.Uint64(buf[0:]))
- val = uint(bo.Uint64(buf[8:]))
- buf = buf[16:]
- }
- switch tag {
- case _AT_HWCAP:
- hwCap = val
- case _AT_HWCAP2:
- hwCap2 = val
- }
- }
doinit()
-
Initialized = true
}
