cpu_openbsd_arm64.mx raw

   1  // Copyright 2022 The Go Authors. All rights reserved.
   2  // Use of this source code is governed by a BSD-style
   3  // license that can be found in the LICENSE file.
   4  
   5  package cpu
   6  
   7  import (
   8  	"syscall"
   9  	"unsafe"
  10  )
  11  
  12  // Minimal copy of functionality from x/sys/unix so the cpu package can call
  13  // sysctl without depending on x/sys/unix.
  14  
  15  const (
  16  	// From OpenBSD's sys/sysctl.h.
  17  	_CTL_MACHDEP = 7
  18  
  19  	// From OpenBSD's machine/cpu.h.
  20  	_CPU_ID_AA64ISAR0 = 2
  21  	_CPU_ID_AA64ISAR1 = 3
  22  )
  23  
  24  // Implemented in the runtime package (runtime/sys_openbsd3.go)
  25  func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
  26  
  27  //go:linkname syscall_syscall6 syscall.syscall6
  28  
  29  func sysctl(mib []uint32, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
  30  	_, _, 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))
  31  	if errno != 0 {
  32  		return errno
  33  	}
  34  	return nil
  35  }
  36  
  37  var libc_sysctl_trampoline_addr uintptr
  38  
  39  //go:cgo_import_dynamic libc_sysctl sysctl "libc.so"
  40  
  41  func sysctlUint64(mib []uint32) (uint64, bool) {
  42  	var out uint64
  43  	nout := unsafe.Sizeof(out)
  44  	if err := sysctl(mib, (*byte)(unsafe.Pointer(&out)), &nout, nil, 0); err != nil {
  45  		return 0, false
  46  	}
  47  	return out, true
  48  }
  49  
  50  func doinit() {
  51  	setMinimalFeatures()
  52  
  53  	// Get ID_AA64ISAR0 and ID_AA64ISAR1 from sysctl.
  54  	isar0, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR0})
  55  	if !ok {
  56  		return
  57  	}
  58  	isar1, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR1})
  59  	if !ok {
  60  		return
  61  	}
  62  	parseARM64SystemRegisters(isar0, isar1, 0)
  63  
  64  	Initialized = true
  65  }
  66