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// Copyright 2017 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.
package cpu
const CacheLinePadSize = 64
// HWCap may be initialized by archauxv and
// should not be changed after it was initialized.
var HWCap uint
// HWCAP bits. These are exposed by Linux.
const (
hwcap_AES = 1 << 3
hwcap_PMULL = 1 << 4
hwcap_SHA1 = 1 << 5
hwcap_SHA2 = 1 << 6
hwcap_CRC32 = 1 << 7
hwcap_ATOMICS = 1 << 8
)
func doinit() {
options = []option{
{Name: "aes", Feature: &ARM64.HasAES},
{Name: "pmull", Feature: &ARM64.HasPMULL},
{Name: "sha1", Feature: &ARM64.HasSHA1},
{Name: "sha2", Feature: &ARM64.HasSHA2},
{Name: "crc32", Feature: &ARM64.HasCRC32},
{Name: "atomics", Feature: &ARM64.HasATOMICS},
}
switch GOOS {
case "linux", "android":
// HWCap was populated by the runtime from the auxillary vector.
// Use HWCap information since reading aarch64 system registers
// is not supported in user space on older linux kernels.
ARM64.HasAES = isSet(HWCap, hwcap_AES)
ARM64.HasPMULL = isSet(HWCap, hwcap_PMULL)
ARM64.HasSHA1 = isSet(HWCap, hwcap_SHA1)
ARM64.HasSHA2 = isSet(HWCap, hwcap_SHA2)
ARM64.HasCRC32 = isSet(HWCap, hwcap_CRC32)
// 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.
ARM64.HasATOMICS = isSet(HWCap, hwcap_ATOMICS) && GOOS != "android"
case "freebsd":
// Retrieve info from system register ID_AA64ISAR0_EL1.
isar0 := getisar0()
// ID_AA64ISAR0_EL1
switch extractBits(isar0, 4, 7) {
case 1:
ARM64.HasAES = true
case 2:
ARM64.HasAES = true
ARM64.HasPMULL = true
}
switch extractBits(isar0, 8, 11) {
case 1:
ARM64.HasSHA1 = true
}
switch extractBits(isar0, 12, 15) {
case 1, 2:
ARM64.HasSHA2 = true
}
switch extractBits(isar0, 16, 19) {
case 1:
ARM64.HasCRC32 = true
}
switch extractBits(isar0, 20, 23) {
case 2:
ARM64.HasATOMICS = true
}
default:
// Other operating systems do not support reading HWCap from auxillary vector
// or reading privileged aarch64 system registers in user space.
}
}
func extractBits(data uint64, start, end uint) uint {
return (uint)(data>>start) & ((1 << (end - start + 1)) - 1)
}
func isSet(hwc uint, value uint) bool {
return hwc&value != 0
}
func getisar0() uint64
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