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OpenBSD 7.1 onwards expose the aarch64 ISAR0 and ISAR1 registers via sysctl: $ sysctl machdep machdep.compatible=apple,j274 machdep.id_aa64isar0=153421459058925856 machdep.id_aa64isar1=1172796674562 Implement CPU feature detection for openbsd/arm64 based on this information. Updates golang/go#31746 Change-Id: I6dc473d93ccff720582c05b75456de51269bc3e5 Reviewed-on: https://go-review.googlesource.com/c/sys/+/421799 Run-TryBot: Joel Sing <joel@sing.id.au> Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Than McIntosh <thanm@google.com> Run-TryBot: Ian Lance Taylor <iant@google.com>
66 lines
1.7 KiB
Go
66 lines
1.7 KiB
Go
// Copyright 2022 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package cpu
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import (
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"syscall"
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"unsafe"
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)
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// Minimal copy of functionality from x/sys/unix so the cpu package can call
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// sysctl without depending on x/sys/unix.
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const (
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// From OpenBSD's sys/sysctl.h.
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_CTL_MACHDEP = 7
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// From OpenBSD's machine/cpu.h.
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_CPU_ID_AA64ISAR0 = 2
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_CPU_ID_AA64ISAR1 = 3
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)
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// Implemented in the runtime package (runtime/sys_openbsd3.go)
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func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
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//go:linkname syscall_syscall6 syscall.syscall6
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func sysctl(mib []uint32, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
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_, _, 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))
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if errno != 0 {
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return errno
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}
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return nil
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}
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var libc_sysctl_trampoline_addr uintptr
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//go:cgo_import_dynamic libc_sysctl sysctl "libc.so"
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func sysctlUint64(mib []uint32) (uint64, bool) {
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var out uint64
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nout := unsafe.Sizeof(out)
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if err := sysctl(mib, (*byte)(unsafe.Pointer(&out)), &nout, nil, 0); err != nil {
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return 0, false
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}
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return out, true
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}
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func doinit() {
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setMinimalFeatures()
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// Get ID_AA64ISAR0 and ID_AA64ISAR1 from sysctl.
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isar0, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR0})
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if !ok {
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return
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}
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isar1, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR1})
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if !ok {
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return
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}
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parseARM64SystemRegisters(isar0, isar1, 0)
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Initialized = true
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}
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