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// Copyright (c) 2020 Klaus Post, released under MIT License. See LICENSE file.
// Copyright 2018 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 located
// here https://github.com/golang/sys/blob/master/LICENSE
package cpuid
import (
"encoding/binary"
"io/ioutil"
"runtime"
)
// HWCAP bits.
const (
hwcap_FP = 1 << 0
hwcap_ASIMD = 1 << 1
hwcap_EVTSTRM = 1 << 2
hwcap_AES = 1 << 3
hwcap_PMULL = 1 << 4
hwcap_SHA1 = 1 << 5
hwcap_SHA2 = 1 << 6
hwcap_CRC32 = 1 << 7
hwcap_ATOMICS = 1 << 8
hwcap_FPHP = 1 << 9
hwcap_ASIMDHP = 1 << 10
hwcap_CPUID = 1 << 11
hwcap_ASIMDRDM = 1 << 12
hwcap_JSCVT = 1 << 13
hwcap_FCMA = 1 << 14
hwcap_LRCPC = 1 << 15
hwcap_DCPOP = 1 << 16
hwcap_SHA3 = 1 << 17
hwcap_SM3 = 1 << 18
hwcap_SM4 = 1 << 19
hwcap_ASIMDDP = 1 << 20
hwcap_SHA512 = 1 << 21
hwcap_SVE = 1 << 22
hwcap_ASIMDFHM = 1 << 23
)
func detectOS(c *CPUInfo) bool {
// For now assuming no hyperthreading is reasonable.
c.LogicalCores = runtime.NumCPU()
c.PhysicalCores = c.LogicalCores
c.ThreadsPerCore = 1
if hwcap == 0 {
// We did not get values from the runtime.
// Try reading /proc/self/auxv
// From https://github.com/golang/sys
const (
_AT_HWCAP = 16
_AT_HWCAP2 = 26
uintSize = int(32 << (^uint(0) >> 63))
)
buf, err := ioutil.ReadFile("/proc/self/auxv")
if err != nil {
// e.g. on android /proc/self/auxv is not accessible, so silently
// ignore the error and leave Initialized = false. On some
// architectures (e.g. arm64) doinit() implements a fallback
// readout and will set Initialized = true again.
return false
}
bo := binary.LittleEndian
for len(buf) >= 2*(uintSize/8) {
var tag, val uint
switch uintSize {
case 32:
tag = uint(bo.Uint32(buf[0:]))
val = uint(bo.Uint32(buf[4:]))
buf = buf[8:]
case 64:
tag = uint(bo.Uint64(buf[0:]))
val = uint(bo.Uint64(buf[8:]))
buf = buf[16:]
}
switch tag {
case _AT_HWCAP:
hwcap = val
case _AT_HWCAP2:
// Not used
}
}
if hwcap == 0 {
return false
}
}
// HWCap was populated by the runtime from the auxiliary vector.
// Use HWCap information since reading aarch64 system registers
// is not supported in user space on older linux kernels.
c.featureSet.setIf(isSet(hwcap, hwcap_AES), AESARM)
c.featureSet.setIf(isSet(hwcap, hwcap_ASIMD), ASIMD)
c.featureSet.setIf(isSet(hwcap, hwcap_ASIMDDP), ASIMDDP)
c.featureSet.setIf(isSet(hwcap, hwcap_ASIMDHP), ASIMDHP)
c.featureSet.setIf(isSet(hwcap, hwcap_ASIMDRDM), ASIMDRDM)
c.featureSet.setIf(isSet(hwcap, hwcap_CPUID), ARMCPUID)
c.featureSet.setIf(isSet(hwcap, hwcap_CRC32), CRC32)
c.featureSet.setIf(isSet(hwcap, hwcap_DCPOP), DCPOP)
c.featureSet.setIf(isSet(hwcap, hwcap_EVTSTRM), EVTSTRM)
c.featureSet.setIf(isSet(hwcap, hwcap_FCMA), FCMA)
c.featureSet.setIf(isSet(hwcap, hwcap_FP), FP)
c.featureSet.setIf(isSet(hwcap, hwcap_FPHP), FPHP)
c.featureSet.setIf(isSet(hwcap, hwcap_JSCVT), JSCVT)
c.featureSet.setIf(isSet(hwcap, hwcap_LRCPC), LRCPC)
c.featureSet.setIf(isSet(hwcap, hwcap_PMULL), PMULL)
c.featureSet.setIf(isSet(hwcap, hwcap_SHA1), SHA1)
c.featureSet.setIf(isSet(hwcap, hwcap_SHA2), SHA2)
c.featureSet.setIf(isSet(hwcap, hwcap_SHA3), SHA3)
c.featureSet.setIf(isSet(hwcap, hwcap_SHA512), SHA512)
c.featureSet.setIf(isSet(hwcap, hwcap_SM3), SM3)
c.featureSet.setIf(isSet(hwcap, hwcap_SM4), SM4)
c.featureSet.setIf(isSet(hwcap, hwcap_SVE), SVE)
// The Samsung S9+ kernel reports support for atomics, but not all cores
// actually support them, resulting in SIGILL. See issue #28431.
// TODO(elias.naur): Only disable the optimization on bad chipsets on android.
c.featureSet.setIf(isSet(hwcap, hwcap_ATOMICS) && runtime.GOOS != "android", ATOMICS)
return true
}
func isSet(hwc uint, value uint) bool {
return hwc&value != 0
}
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