go1.16 (#14783)

vendor/github.com/klauspost/cpuid/v2/os_linux_arm64.go

@@ -0,0 +1,161 @@
+// 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"
+	"unsafe"
+)
+
+// 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
+)
+
+//go:linkname hwcap internal/cpu.HWCap
+var hwcap uint
+
+func detectOS(c *CPUInfo) bool {
+	// For now assuming no hyperthreading is reasonable.
+	c.LogicalCores = int(getproccount())
+	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
+}
+
+//go:noescape
+//go:linkname sched_getaffinity runtime.sched_getaffinity
+func sched_getaffinity(pid, len uintptr, buf *byte) int32
+
+func getproccount() int32 {
+	// This buffer is huge (8 kB) but we are on the system stack
+	// and there should be plenty of space (64 kB).
+	// Also this is a leaf, so we're not holding up the memory for long.
+	const maxCPUs = 64 * 1024
+	var buf [maxCPUs / 8]byte
+	r := sched_getaffinity(0, unsafe.Sizeof(buf), &buf[0])
+	if r < 0 {
+		return 0
+	}
+	n := int32(0)
+	for _, v := range buf[:r] {
+		for v != 0 {
+			n += int32(v & 1)
+			v >>= 1
+		}
+	}
+	if n == 0 {
+		n = 1
+	}
+	return n
+}