golang.org/x/sys@v0.20.1-0.20240517151509-673e0f94c16d/cpu/cpu_linux_arm64.go (about) 1 // Copyright 2018 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package cpu 6 7 import ( 8 "strings" 9 "syscall" 10 ) 11 12 // HWCAP/HWCAP2 bits. These are exposed by Linux. 13 const ( 14 hwcap_FP = 1 << 0 15 hwcap_ASIMD = 1 << 1 16 hwcap_EVTSTRM = 1 << 2 17 hwcap_AES = 1 << 3 18 hwcap_PMULL = 1 << 4 19 hwcap_SHA1 = 1 << 5 20 hwcap_SHA2 = 1 << 6 21 hwcap_CRC32 = 1 << 7 22 hwcap_ATOMICS = 1 << 8 23 hwcap_FPHP = 1 << 9 24 hwcap_ASIMDHP = 1 << 10 25 hwcap_CPUID = 1 << 11 26 hwcap_ASIMDRDM = 1 << 12 27 hwcap_JSCVT = 1 << 13 28 hwcap_FCMA = 1 << 14 29 hwcap_LRCPC = 1 << 15 30 hwcap_DCPOP = 1 << 16 31 hwcap_SHA3 = 1 << 17 32 hwcap_SM3 = 1 << 18 33 hwcap_SM4 = 1 << 19 34 hwcap_ASIMDDP = 1 << 20 35 hwcap_SHA512 = 1 << 21 36 hwcap_SVE = 1 << 22 37 hwcap_ASIMDFHM = 1 << 23 38 39 hwcap2_SVE2 = 1 << 1 40 ) 41 42 // linuxKernelCanEmulateCPUID reports whether we're running 43 // on Linux 4.11+. Ideally we'd like to ask the question about 44 // whether the current kernel contains 45 // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=77c97b4ee21290f5f083173d957843b615abbff2 46 // but the version number will have to do. 47 func linuxKernelCanEmulateCPUID() bool { 48 var un syscall.Utsname 49 syscall.Uname(&un) 50 var sb strings.Builder 51 for _, b := range un.Release[:] { 52 if b == 0 { 53 break 54 } 55 sb.WriteByte(byte(b)) 56 } 57 major, minor, _, ok := parseRelease(sb.String()) 58 return ok && (major > 4 || major == 4 && minor >= 11) 59 } 60 61 func doinit() { 62 if err := readHWCAP(); err != nil { 63 // We failed to read /proc/self/auxv. This can happen if the binary has 64 // been given extra capabilities(7) with /bin/setcap. 65 // 66 // When this happens, we have two options. If the Linux kernel is new 67 // enough (4.11+), we can read the arm64 registers directly which'll 68 // trap into the kernel and then return back to userspace. 69 // 70 // But on older kernels, such as Linux 4.4.180 as used on many Synology 71 // devices, calling readARM64Registers (specifically getisar0) will 72 // cause a SIGILL and we'll die. So for older kernels, parse /proc/cpuinfo 73 // instead. 74 // 75 // See golang/go#57336. 76 if linuxKernelCanEmulateCPUID() { 77 readARM64Registers() 78 } else { 79 readLinuxProcCPUInfo() 80 } 81 return 82 } 83 84 // HWCAP feature bits 85 ARM64.HasFP = isSet(hwCap, hwcap_FP) 86 ARM64.HasASIMD = isSet(hwCap, hwcap_ASIMD) 87 ARM64.HasEVTSTRM = isSet(hwCap, hwcap_EVTSTRM) 88 ARM64.HasAES = isSet(hwCap, hwcap_AES) 89 ARM64.HasPMULL = isSet(hwCap, hwcap_PMULL) 90 ARM64.HasSHA1 = isSet(hwCap, hwcap_SHA1) 91 ARM64.HasSHA2 = isSet(hwCap, hwcap_SHA2) 92 ARM64.HasCRC32 = isSet(hwCap, hwcap_CRC32) 93 ARM64.HasATOMICS = isSet(hwCap, hwcap_ATOMICS) 94 ARM64.HasFPHP = isSet(hwCap, hwcap_FPHP) 95 ARM64.HasASIMDHP = isSet(hwCap, hwcap_ASIMDHP) 96 ARM64.HasCPUID = isSet(hwCap, hwcap_CPUID) 97 ARM64.HasASIMDRDM = isSet(hwCap, hwcap_ASIMDRDM) 98 ARM64.HasJSCVT = isSet(hwCap, hwcap_JSCVT) 99 ARM64.HasFCMA = isSet(hwCap, hwcap_FCMA) 100 ARM64.HasLRCPC = isSet(hwCap, hwcap_LRCPC) 101 ARM64.HasDCPOP = isSet(hwCap, hwcap_DCPOP) 102 ARM64.HasSHA3 = isSet(hwCap, hwcap_SHA3) 103 ARM64.HasSM3 = isSet(hwCap, hwcap_SM3) 104 ARM64.HasSM4 = isSet(hwCap, hwcap_SM4) 105 ARM64.HasASIMDDP = isSet(hwCap, hwcap_ASIMDDP) 106 ARM64.HasSHA512 = isSet(hwCap, hwcap_SHA512) 107 ARM64.HasSVE = isSet(hwCap, hwcap_SVE) 108 ARM64.HasASIMDFHM = isSet(hwCap, hwcap_ASIMDFHM) 109 110 // HWCAP2 feature bits 111 ARM64.HasSVE2 = isSet(hwCap2, hwcap2_SVE2) 112 } 113 114 func isSet(hwc uint, value uint) bool { 115 return hwc&value != 0 116 }