cpu: read ARM64 registers using sysctl(3) on netbsd/arm64
Use sysctl("machdep.cpu0.cpu_id") to retrieve the ARM64 cpu_id
information on netbsd/arm64. This includes the ISAR0, ISAR1 and PFR0
registers which can be parsed using existing functionality.
In order to use sysctl(3) without depending on x/sys/unix, some
functionality needed to be copied and slightly adjusted.
Change-Id: Ic9a133917ae5da516e6794f375bd7602d9bd3aa6
Reviewed-on: https://go-review.googlesource.com/c/sys/+/264378
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Trust: Benny Siegert <bsiegert@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
diff --git a/cpu/cpu_arm64.go b/cpu/cpu_arm64.go
index 856dae3..87dd5e3 100644
--- a/cpu/cpu_arm64.go
+++ b/cpu/cpu_arm64.go
@@ -39,28 +39,26 @@
func archInit() {
switch runtime.GOOS {
- case "android", "darwin", "ios", "netbsd", "openbsd":
- // Android and iOS don't seem to allow reading these registers.
- //
- // NetBSD:
- // ID_AA64ISAR0_EL1 is a privileged register and cannot be read from EL0.
- // It can be read via sysctl(3). Example for future implementers:
- // https://nxr.netbsd.org/xref/src/usr.sbin/cpuctl/arch/aarch64.c
+ case "freebsd":
+ readARM64Registers()
+ case "linux", "netbsd":
+ doinit()
+ default:
+ // Most platforms don't seem to allow reading these registers.
//
// OpenBSD:
// See https://golang.org/issue/31746
- //
- // Fake the minimal features expected by
- // TestARM64minimalFeatures.
- ARM64.HasASIMD = true
- ARM64.HasFP = true
- case "linux":
- doinit()
- default:
- readARM64Registers()
+ setMinimalFeatures()
}
}
+// setMinimalFeatures fakes the minimal ARM64 features expected by
+// TestARM64minimalFeatures.
+func setMinimalFeatures() {
+ ARM64.HasASIMD = true
+ ARM64.HasFP = true
+}
+
func readARM64Registers() {
Initialized = true
diff --git a/cpu/cpu_netbsd_arm64.go b/cpu/cpu_netbsd_arm64.go
new file mode 100644
index 0000000..ebfb3fc
--- /dev/null
+++ b/cpu/cpu_netbsd_arm64.go
@@ -0,0 +1,173 @@
+// Copyright 2020 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.
+
+package cpu
+
+import (
+ "syscall"
+ "unsafe"
+)
+
+// Minimal copy of functionality from x/sys/unix so the cpu package can call
+// sysctl without depending on x/sys/unix.
+
+const (
+ _CTL_QUERY = -2
+
+ _SYSCTL_VERS_1 = 0x1000000
+)
+
+var _zero uintptr
+
+func sysctl(mib []int32, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
+ var _p0 unsafe.Pointer
+ if len(mib) > 0 {
+ _p0 = unsafe.Pointer(&mib[0])
+ } else {
+ _p0 = unsafe.Pointer(&_zero)
+ }
+ _, _, errno := syscall.Syscall6(
+ syscall.SYS___SYSCTL,
+ uintptr(_p0),
+ uintptr(len(mib)),
+ uintptr(unsafe.Pointer(old)),
+ uintptr(unsafe.Pointer(oldlen)),
+ uintptr(unsafe.Pointer(new)),
+ uintptr(newlen))
+ if errno != 0 {
+ return errno
+ }
+ return nil
+}
+
+type sysctlNode struct {
+ Flags uint32
+ Num int32
+ Name [32]int8
+ Ver uint32
+ __rsvd uint32
+ Un [16]byte
+ _sysctl_size [8]byte
+ _sysctl_func [8]byte
+ _sysctl_parent [8]byte
+ _sysctl_desc [8]byte
+}
+
+func sysctlNodes(mib []int32) ([]sysctlNode, error) {
+ var olen uintptr
+
+ // Get a list of all sysctl nodes below the given MIB by performing
+ // a sysctl for the given MIB with CTL_QUERY appended.
+ mib = append(mib, _CTL_QUERY)
+ qnode := sysctlNode{Flags: _SYSCTL_VERS_1}
+ qp := (*byte)(unsafe.Pointer(&qnode))
+ sz := unsafe.Sizeof(qnode)
+ if err := sysctl(mib, nil, &olen, qp, sz); err != nil {
+ return nil, err
+ }
+
+ // Now that we know the size, get the actual nodes.
+ nodes := make([]sysctlNode, olen/sz)
+ np := (*byte)(unsafe.Pointer(&nodes[0]))
+ if err := sysctl(mib, np, &olen, qp, sz); err != nil {
+ return nil, err
+ }
+
+ return nodes, nil
+}
+
+func nametomib(name string) ([]int32, error) {
+ // Split name into components.
+ var parts []string
+ last := 0
+ for i := 0; i < len(name); i++ {
+ if name[i] == '.' {
+ parts = append(parts, name[last:i])
+ last = i + 1
+ }
+ }
+ parts = append(parts, name[last:])
+
+ mib := []int32{}
+ // Discover the nodes and construct the MIB OID.
+ for partno, part := range parts {
+ nodes, err := sysctlNodes(mib)
+ if err != nil {
+ return nil, err
+ }
+ for _, node := range nodes {
+ n := make([]byte, 0)
+ for i := range node.Name {
+ if node.Name[i] != 0 {
+ n = append(n, byte(node.Name[i]))
+ }
+ }
+ if string(n) == part {
+ mib = append(mib, int32(node.Num))
+ break
+ }
+ }
+ if len(mib) != partno+1 {
+ return nil, err
+ }
+ }
+
+ return mib, nil
+}
+
+// aarch64SysctlCPUID is struct aarch64_sysctl_cpu_id from NetBSD's <aarch64/armreg.h>
+type aarch64SysctlCPUID struct {
+ midr uint64 /* Main ID Register */
+ revidr uint64 /* Revision ID Register */
+ mpidr uint64 /* Multiprocessor Affinity Register */
+ aa64dfr0 uint64 /* A64 Debug Feature Register 0 */
+ aa64dfr1 uint64 /* A64 Debug Feature Register 1 */
+ aa64isar0 uint64 /* A64 Instruction Set Attribute Register 0 */
+ aa64isar1 uint64 /* A64 Instruction Set Attribute Register 1 */
+ aa64mmfr0 uint64 /* A64 Memory Model Feature Register 0 */
+ aa64mmfr1 uint64 /* A64 Memory Model Feature Register 1 */
+ aa64mmfr2 uint64 /* A64 Memory Model Feature Register 2 */
+ aa64pfr0 uint64 /* A64 Processor Feature Register 0 */
+ aa64pfr1 uint64 /* A64 Processor Feature Register 1 */
+ aa64zfr0 uint64 /* A64 SVE Feature ID Register 0 */
+ mvfr0 uint32 /* Media and VFP Feature Register 0 */
+ mvfr1 uint32 /* Media and VFP Feature Register 1 */
+ mvfr2 uint32 /* Media and VFP Feature Register 2 */
+ pad uint32
+ clidr uint64 /* Cache Level ID Register */
+ ctr uint64 /* Cache Type Register */
+}
+
+func sysctlCPUID(name string) (*aarch64SysctlCPUID, error) {
+ mib, err := nametomib(name)
+ if err != nil {
+ return nil, err
+ }
+
+ out := aarch64SysctlCPUID{}
+ n := unsafe.Sizeof(out)
+ _, _, errno := syscall.Syscall6(
+ syscall.SYS___SYSCTL,
+ uintptr(unsafe.Pointer(&mib[0])),
+ uintptr(len(mib)),
+ uintptr(unsafe.Pointer(&out)),
+ uintptr(unsafe.Pointer(&n)),
+ uintptr(0),
+ uintptr(0))
+ if errno != 0 {
+ return nil, errno
+ }
+ return &out, nil
+}
+
+func doinit() {
+ cpuid, err := sysctlCPUID("machdep.cpu0.cpu_id")
+ if err != nil {
+ setMinimalFeatures()
+ return
+ }
+ parseARM64SystemRegisters(cpuid.aa64isar0, cpuid.aa64isar1, cpuid.aa64pfr0)
+
+ Initialized = true
+}
diff --git a/cpu/cpu_other_arm64.go b/cpu/cpu_other_arm64.go
index 3ffc4af..16c1c40 100644
--- a/cpu/cpu_other_arm64.go
+++ b/cpu/cpu_other_arm64.go
@@ -2,7 +2,8 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// +build !linux,arm64
+// +build !linux,!netbsd
+// +build arm64
package cpu
