cpu_x86.go

     1  // Copyright 2017 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  //go:build 386 || amd64
     6  
     7  package cpu
     8  
     9  const CacheLinePadSize = 64
    10  
    11  // cpuid is implemented in cpu_x86.s.
    12  func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
    13  
    14  // xgetbv with ecx = 0 is implemented in cpu_x86.s.
    15  func xgetbv() (eax, edx uint32)
    16  
    17  // getGOAMD64level is implemented in cpu_x86.s. Returns number in [1,4].
    18  func getGOAMD64level() int32
    19  
    20  const (
    21  	// Bits returned in ECX for CPUID EAX=0x1 ECX=0x0
    22  	cpuid_SSE3      = 1 << 0
    23  	cpuid_PCLMULQDQ = 1 << 1
    24  	cpuid_SSSE3     = 1 << 9
    25  	cpuid_FMA       = 1 << 12
    26  	cpuid_SSE41     = 1 << 19
    27  	cpuid_SSE42     = 1 << 20
    28  	cpuid_POPCNT    = 1 << 23
    29  	cpuid_AES       = 1 << 25
    30  	cpuid_OSXSAVE   = 1 << 27
    31  	cpuid_AVX       = 1 << 28
    32  
    33  	// "Extended Feature Flag" bits returned in EBX for CPUID EAX=0x7 ECX=0x0
    34  	cpuid_BMI1     = 1 << 3
    35  	cpuid_AVX2     = 1 << 5
    36  	cpuid_BMI2     = 1 << 8
    37  	cpuid_ERMS     = 1 << 9
    38  	cpuid_AVX512F  = 1 << 16
    39  	cpuid_AVX512DQ = 1 << 17
    40  	cpuid_ADX      = 1 << 19
    41  	cpuid_AVX512CD = 1 << 28
    42  	cpuid_SHA      = 1 << 29
    43  	cpuid_AVX512BW = 1 << 30
    44  	cpuid_AVX512VL = 1 << 31
    45  
    46  	// "Extended Feature Flag" bits returned in ECX for CPUID EAX=0x7 ECX=0x0
    47  	cpuid_AVX512_VBMI      = 1 << 1
    48  	cpuid_AVX512_VBMI2     = 1 << 6
    49  	cpuid_GFNI             = 1 << 8
    50  	cpuid_AVX512VPCLMULQDQ = 1 << 10
    51  	cpuid_AVX512_BITALG    = 1 << 12
    52  
    53  	// edx bits
    54  	cpuid_FSRM = 1 << 4
    55  	// edx bits for CPUID 0x80000001
    56  	cpuid_RDTSCP = 1 << 27
    57  )
    58  
    59  var maxExtendedFunctionInformation uint32
    60  
    61  func doinit() {
    62  	options = []option{
    63  		{Name: "adx", Feature: &X86.HasADX},
    64  		{Name: "aes", Feature: &X86.HasAES},
    65  		{Name: "erms", Feature: &X86.HasERMS},
    66  		{Name: "fsrm", Feature: &X86.HasFSRM},
    67  		{Name: "pclmulqdq", Feature: &X86.HasPCLMULQDQ},
    68  		{Name: "rdtscp", Feature: &X86.HasRDTSCP},
    69  		{Name: "sha", Feature: &X86.HasSHA},
    70  		{Name: "vpclmulqdq", Feature: &X86.HasAVX512VPCLMULQDQ},
    71  	}
    72  	level := getGOAMD64level()
    73  	if level < 2 {
    74  		// These options are required at level 2. At lower levels
    75  		// they can be turned off.
    76  		options = append(options,
    77  			option{Name: "popcnt", Feature: &X86.HasPOPCNT},
    78  			option{Name: "sse3", Feature: &X86.HasSSE3},
    79  			option{Name: "sse41", Feature: &X86.HasSSE41},
    80  			option{Name: "sse42", Feature: &X86.HasSSE42},
    81  			option{Name: "ssse3", Feature: &X86.HasSSSE3})
    82  	}
    83  	if level < 3 {
    84  		// These options are required at level 3. At lower levels
    85  		// they can be turned off.
    86  		options = append(options,
    87  			option{Name: "avx", Feature: &X86.HasAVX},
    88  			option{Name: "avx2", Feature: &X86.HasAVX2},
    89  			option{Name: "bmi1", Feature: &X86.HasBMI1},
    90  			option{Name: "bmi2", Feature: &X86.HasBMI2},
    91  			option{Name: "fma", Feature: &X86.HasFMA})
    92  	}
    93  	if level < 4 {
    94  		// These options are required at level 4. At lower levels
    95  		// they can be turned off.
    96  		options = append(options,
    97  			option{Name: "avx512f", Feature: &X86.HasAVX512F},
    98  			option{Name: "avx512cd", Feature: &X86.HasAVX512CD},
    99  			option{Name: "avx512bw", Feature: &X86.HasAVX512BW},
   100  			option{Name: "avx512dq", Feature: &X86.HasAVX512DQ},
   101  			option{Name: "avx512vl", Feature: &X86.HasAVX512VL},
   102  		)
   103  	}
   104  
   105  	maxID, _, _, _ := cpuid(0, 0)
   106  
   107  	if maxID < 1 {
   108  		return
   109  	}
   110  
   111  	maxExtendedFunctionInformation, _, _, _ = cpuid(0x80000000, 0)
   112  
   113  	_, _, ecx1, _ := cpuid(1, 0)
   114  
   115  	X86.HasSSE3 = isSet(ecx1, cpuid_SSE3)
   116  	X86.HasPCLMULQDQ = isSet(ecx1, cpuid_PCLMULQDQ)
   117  	X86.HasSSSE3 = isSet(ecx1, cpuid_SSSE3)
   118  	X86.HasSSE41 = isSet(ecx1, cpuid_SSE41)
   119  	X86.HasSSE42 = isSet(ecx1, cpuid_SSE42)
   120  	X86.HasPOPCNT = isSet(ecx1, cpuid_POPCNT)
   121  	X86.HasAES = isSet(ecx1, cpuid_AES)
   122  
   123  	// OSXSAVE can be false when using older Operating Systems
   124  	// or when explicitly disabled on newer Operating Systems by
   125  	// e.g. setting the xsavedisable boot option on Windows 10.
   126  	X86.HasOSXSAVE = isSet(ecx1, cpuid_OSXSAVE)
   127  
   128  	// The FMA instruction set extension only has VEX prefixed instructions.
   129  	// VEX prefixed instructions require OSXSAVE to be enabled.
   130  	// See Intel 64 and IA-32 Architecture Software Developer’s Manual Volume 2
   131  	// Section 2.4 "AVX and SSE Instruction Exception Specification"
   132  	X86.HasFMA = isSet(ecx1, cpuid_FMA) && X86.HasOSXSAVE
   133  
   134  	osSupportsAVX := false
   135  	osSupportsAVX512 := false
   136  	// For XGETBV, OSXSAVE bit is required and sufficient.
   137  	if X86.HasOSXSAVE {
   138  		eax, _ := xgetbv()
   139  		// Check if XMM and YMM registers have OS support.
   140  		osSupportsAVX = isSet(eax, 1<<1) && isSet(eax, 1<<2)
   141  
   142  		// AVX512 detection does not work on Darwin,
   143  		// see https://github.com/golang/go/issues/49233
   144  		//
   145  		// Check if opmask, ZMMhi256 and Hi16_ZMM have OS support.
   146  		osSupportsAVX512 = osSupportsAVX && isSet(eax, 1<<5) && isSet(eax, 1<<6) && isSet(eax, 1<<7)
   147  	}
   148  
   149  	X86.HasAVX = isSet(ecx1, cpuid_AVX) && osSupportsAVX
   150  
   151  	if maxID < 7 {
   152  		return
   153  	}
   154  
   155  	_, ebx7, ecx7, edx7 := cpuid(7, 0)
   156  	X86.HasBMI1 = isSet(ebx7, cpuid_BMI1)
   157  	X86.HasAVX2 = isSet(ebx7, cpuid_AVX2) && osSupportsAVX
   158  	X86.HasBMI2 = isSet(ebx7, cpuid_BMI2)
   159  	X86.HasERMS = isSet(ebx7, cpuid_ERMS)
   160  	X86.HasADX = isSet(ebx7, cpuid_ADX)
   161  	X86.HasSHA = isSet(ebx7, cpuid_SHA)
   162  
   163  	X86.HasAVX512F = isSet(ebx7, cpuid_AVX512F) && osSupportsAVX512
   164  	if X86.HasAVX512F {
   165  		X86.HasAVX512CD = isSet(ebx7, cpuid_AVX512CD)
   166  		X86.HasAVX512BW = isSet(ebx7, cpuid_AVX512BW)
   167  		X86.HasAVX512DQ = isSet(ebx7, cpuid_AVX512DQ)
   168  		X86.HasAVX512VL = isSet(ebx7, cpuid_AVX512VL)
   169  		X86.HasAVX512VPCLMULQDQ = isSet(ecx7, cpuid_AVX512VPCLMULQDQ)
   170  		X86.HasAVX512VBMI = isSet(ecx7, cpuid_AVX512_VBMI)
   171  		X86.HasAVX512VBMI2 = isSet(ecx7, cpuid_AVX512_VBMI2)
   172  		X86.HasGFNI = isSet(ecx7, cpuid_GFNI)
   173  		X86.HasAVX512BITALG = isSet(ecx7, cpuid_AVX512_BITALG)
   174  	}
   175  
   176  	X86.HasFSRM = isSet(edx7, cpuid_FSRM)
   177  
   178  	var maxExtendedInformation uint32
   179  	maxExtendedInformation, _, _, _ = cpuid(0x80000000, 0)
   180  
   181  	if maxExtendedInformation < 0x80000001 {
   182  		return
   183  	}
   184  
   185  	_, _, _, edxExt1 := cpuid(0x80000001, 0)
   186  	X86.HasRDTSCP = isSet(edxExt1, cpuid_RDTSCP)
   187  
   188  	doDerived = func() {
   189  		// Rather than carefully gating on fundamental AVX-512 features, we have
   190  		// a virtual "AVX512" feature that captures F+CD+BW+DQ+VL. BW, DQ, and
   191  		// VL have a huge effect on which AVX-512 instructions are available,
   192  		// and these have all been supported on everything except the earliest
   193  		// Phi chips with AVX-512. No CPU has had CD without F, so we include
   194  		// it. GOAMD64=v4 also implies exactly this set, and these are all
   195  		// included in AVX10.1.
   196  		X86.HasAVX512 = X86.HasAVX512F && X86.HasAVX512CD && X86.HasAVX512BW && X86.HasAVX512DQ && X86.HasAVX512VL
   197  	}
   198  }
   199  
   200  func isSet(hwc uint32, value uint32) bool {
   201  	return hwc&value != 0
   202  }
   203  
   204  // Name returns the CPU name given by the vendor.
   205  // If the CPU name can not be determined an
   206  // empty string is returned.
   207  func Name() string {
   208  	if maxExtendedFunctionInformation < 0x80000004 {
   209  		return ""
   210  	}
   211  
   212  	data := make([]byte, 0, 3*4*4)
   213  
   214  	var eax, ebx, ecx, edx uint32
   215  	eax, ebx, ecx, edx = cpuid(0x80000002, 0)
   216  	data = appendBytes(data, eax, ebx, ecx, edx)
   217  	eax, ebx, ecx, edx = cpuid(0x80000003, 0)
   218  	data = appendBytes(data, eax, ebx, ecx, edx)
   219  	eax, ebx, ecx, edx = cpuid(0x80000004, 0)
   220  	data = appendBytes(data, eax, ebx, ecx, edx)
   221  
   222  	// Trim leading spaces.
   223  	for len(data) > 0 && data[0] == ' ' {
   224  		data = data[1:]
   225  	}
   226  
   227  	// Trim tail after and including the first null byte.
   228  	for i, c := range data {
   229  		if c == '\x00' {
   230  			data = data[:i]
   231  			break
   232  		}
   233  	}
   234  
   235  	return string(data)
   236  }
   237  
   238  func appendBytes(b []byte, args ...uint32) []byte {
   239  	for _, arg := range args {
   240  		b = append(b,
   241  			byte((arg >> 0)),
   242  			byte((arg >> 8)),
   243  			byte((arg >> 16)),
   244  			byte((arg >> 24)))
   245  	}
   246  	return b
   247  }
   248
View as plain text