mirror of
https://github.com/refraction-networking/utls.git
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63 lines
2 KiB
Go
63 lines
2 KiB
Go
// Copyright 2020 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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//go:build arm64 && linux
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// +build arm64,linux
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package cpu
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// HWCap may be initialized by archauxv and
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// should not be changed after it was initialized.
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var HWCap uint
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// HWCAP bits. These are exposed by Linux.
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const (
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hwcap_AES = 1 << 3
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hwcap_PMULL = 1 << 4
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hwcap_SHA1 = 1 << 5
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hwcap_SHA2 = 1 << 6
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hwcap_CRC32 = 1 << 7
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hwcap_ATOMICS = 1 << 8
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hwcap_CPUID = 1 << 11
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)
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func hwcapInit(os string) {
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// HWCap was populated by the runtime from the auxiliary vector.
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// Use HWCap information since reading aarch64 system registers
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// is not supported in user space on older linux kernels.
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ARM64.HasAES = isSet(HWCap, hwcap_AES)
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ARM64.HasPMULL = isSet(HWCap, hwcap_PMULL)
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ARM64.HasSHA1 = isSet(HWCap, hwcap_SHA1)
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ARM64.HasSHA2 = isSet(HWCap, hwcap_SHA2)
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ARM64.HasCRC32 = isSet(HWCap, hwcap_CRC32)
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ARM64.HasCPUID = isSet(HWCap, hwcap_CPUID)
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// The Samsung S9+ kernel reports support for atomics, but not all cores
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// actually support them, resulting in SIGILL. See issue #28431.
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// TODO(elias.naur): Only disable the optimization on bad chipsets on android.
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ARM64.HasATOMICS = isSet(HWCap, hwcap_ATOMICS) && os != "android"
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// Check to see if executing on a NeoverseN1 and in order to do that,
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// check the AUXV for the CPUID bit. The getMIDR function executes an
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// instruction which would normally be an illegal instruction, but it's
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// trapped by the kernel, the value sanitized and then returned. Without
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// the CPUID bit the kernel will not trap the instruction and the process
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// will be terminated with SIGILL.
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if ARM64.HasCPUID {
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midr := getMIDR()
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part_num := uint16((midr >> 4) & 0xfff)
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implementor := byte((midr >> 24) & 0xff)
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if implementor == 'A' && part_num == 0xd0c {
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ARM64.IsNeoverseN1 = true
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}
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if implementor == 'A' && part_num == 0xd40 {
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ARM64.IsZeus = true
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}
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}
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}
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func isSet(hwc uint, value uint) bool {
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return hwc&value != 0
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}
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