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// Copyright 2022 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 (
// From OpenBSD's sys/sysctl.h.
_CTL_MACHDEP = 7
// From OpenBSD's machine/cpu.h.
_CPU_ID_AA64ISAR0 = 2
_CPU_ID_AA64ISAR1 = 3
)
// Implemented in the runtime package (runtime/sys_openbsd3.go)
func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
//go:linkname syscall_syscall6 syscall.syscall6
func sysctl(mib []uint32, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
_, _, errno := syscall_syscall6(libc_sysctl_trampoline_addr, uintptr(unsafe.Pointer(&mib[0])), uintptr(len(mib)), uintptr(unsafe.Pointer(old)), uintptr(unsafe.Pointer(oldlen)), uintptr(unsafe.Pointer(new)), uintptr(newlen))
if errno != 0 {
return errno
}
return nil
}
var libc_sysctl_trampoline_addr uintptr
//go:cgo_import_dynamic libc_sysctl sysctl "libc.so"
func sysctlUint64(mib []uint32) (uint64, bool) {
var out uint64
nout := unsafe.Sizeof(out)
if err := sysctl(mib, (*byte)(unsafe.Pointer(&out)), &nout, nil, 0); err != nil {
return 0, false
}
return out, true
}
func doinit() {
setMinimalFeatures()
// Get ID_AA64ISAR0 and ID_AA64ISAR1 from sysctl.
isar0, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR0})
if !ok {
return
}
isar1, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR1})
if !ok {
return
}
parseARM64SystemRegisters(isar0, isar1, 0)
Initialized = true
}
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