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internal/cpu: implement CPU feature detection for openbsd/arm64
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. Fixes #31746 Change-Id: If8a9b2b8fc557e1aaefbcb52f4d1bd9efc43856d Reviewed-on: https://go-review.googlesource.com/c/go/+/421875 Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com> Auto-Submit: Ian Lance Taylor <iant@google.com> Run-TryBot: Joel Sing <joel@sing.id.au> Run-TryBot: Ian Lance Taylor <iant@google.com>
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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. | ||
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//go:build arm64 | ||
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package cpu | ||
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const ( | ||
// From OpenBSD's sys/sysctl.h. | ||
_CTL_MACHDEP = 7 | ||
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// From OpenBSD's machine/cpu.h. | ||
_CPU_ID_AA64ISAR0 = 2 | ||
_CPU_ID_AA64ISAR1 = 3 | ||
) | ||
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func extractBits(data uint64, start, end uint) uint { | ||
return (uint)(data>>start) & ((1 << (end - start + 1)) - 1) | ||
} | ||
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//go:noescape | ||
func sysctlUint64(mib []uint32) (uint64, bool) | ||
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func osInit() { | ||
// Get ID_AA64ISAR0 from sysctl. | ||
isar0, ok := sysctlUint64([]uint32{_CTL_MACHDEP, _CPU_ID_AA64ISAR0}) | ||
if !ok { | ||
return | ||
} | ||
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// ID_AA64ISAR0_EL1 | ||
switch extractBits(isar0, 4, 7) { | ||
case 1: | ||
ARM64.HasAES = true | ||
case 2: | ||
ARM64.HasAES = true | ||
ARM64.HasPMULL = true | ||
} | ||
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switch extractBits(isar0, 8, 11) { | ||
case 1: | ||
ARM64.HasSHA1 = true | ||
} | ||
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switch extractBits(isar0, 12, 15) { | ||
case 1, 2: | ||
ARM64.HasSHA2 = true | ||
} | ||
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switch extractBits(isar0, 16, 19) { | ||
case 1: | ||
ARM64.HasCRC32 = true | ||
} | ||
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switch extractBits(isar0, 20, 23) { | ||
case 2: | ||
ARM64.HasATOMICS = true | ||
} | ||
} |
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