Source file src/runtime/os_windows.go

     1  // Copyright 2009 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 runtime
     6  
     7  import (
     8  	"internal/abi"
     9  	"internal/runtime/atomic"
    10  	"internal/runtime/sys"
    11  	"unsafe"
    12  )
    13  
    14  // TODO(brainman): should not need those
    15  const (
    16  	_NSIG = 65
    17  )
    18  
    19  //go:cgo_import_dynamic runtime._AddVectoredContinueHandler AddVectoredContinueHandler%2 "kernel32.dll"
    20  //go:cgo_import_dynamic runtime._AddVectoredExceptionHandler AddVectoredExceptionHandler%2 "kernel32.dll"
    21  //go:cgo_import_dynamic runtime._CloseHandle CloseHandle%1 "kernel32.dll"
    22  //go:cgo_import_dynamic runtime._CreateEventA CreateEventA%4 "kernel32.dll"
    23  //go:cgo_import_dynamic runtime._CreateIoCompletionPort CreateIoCompletionPort%4 "kernel32.dll"
    24  //go:cgo_import_dynamic runtime._CreateThread CreateThread%6 "kernel32.dll"
    25  //go:cgo_import_dynamic runtime._CreateWaitableTimerA CreateWaitableTimerA%3 "kernel32.dll"
    26  //go:cgo_import_dynamic runtime._CreateWaitableTimerExW CreateWaitableTimerExW%4 "kernel32.dll"
    27  //go:cgo_import_dynamic runtime._DuplicateHandle DuplicateHandle%7 "kernel32.dll"
    28  //go:cgo_import_dynamic runtime._ExitProcess ExitProcess%1 "kernel32.dll"
    29  //go:cgo_import_dynamic runtime._FreeEnvironmentStringsW FreeEnvironmentStringsW%1 "kernel32.dll"
    30  //go:cgo_import_dynamic runtime._GetConsoleMode GetConsoleMode%2 "kernel32.dll"
    31  //go:cgo_import_dynamic runtime._GetCurrentThreadId GetCurrentThreadId%0 "kernel32.dll"
    32  //go:cgo_import_dynamic runtime._GetEnvironmentStringsW GetEnvironmentStringsW%0 "kernel32.dll"
    33  //go:cgo_import_dynamic runtime._GetErrorMode GetErrorMode%0 "kernel32.dll"
    34  //go:cgo_import_dynamic runtime._GetProcAddress GetProcAddress%2 "kernel32.dll"
    35  //go:cgo_import_dynamic runtime._GetProcessAffinityMask GetProcessAffinityMask%3 "kernel32.dll"
    36  //go:cgo_import_dynamic runtime._GetQueuedCompletionStatusEx GetQueuedCompletionStatusEx%6 "kernel32.dll"
    37  //go:cgo_import_dynamic runtime._GetStdHandle GetStdHandle%1 "kernel32.dll"
    38  //go:cgo_import_dynamic runtime._GetSystemDirectoryA GetSystemDirectoryA%2 "kernel32.dll"
    39  //go:cgo_import_dynamic runtime._GetSystemInfo GetSystemInfo%1 "kernel32.dll"
    40  //go:cgo_import_dynamic runtime._GetThreadContext GetThreadContext%2 "kernel32.dll"
    41  //go:cgo_import_dynamic runtime._SetThreadContext SetThreadContext%2 "kernel32.dll"
    42  //go:cgo_import_dynamic runtime._LoadLibraryExW LoadLibraryExW%3 "kernel32.dll"
    43  //go:cgo_import_dynamic runtime._LoadLibraryW LoadLibraryW%1 "kernel32.dll"
    44  //go:cgo_import_dynamic runtime._PostQueuedCompletionStatus PostQueuedCompletionStatus%4 "kernel32.dll"
    45  //go:cgo_import_dynamic runtime._QueryPerformanceCounter QueryPerformanceCounter%1 "kernel32.dll"
    46  //go:cgo_import_dynamic runtime._QueryPerformanceFrequency QueryPerformanceFrequency%1 "kernel32.dll"
    47  //go:cgo_import_dynamic runtime._RaiseFailFastException RaiseFailFastException%3 "kernel32.dll"
    48  //go:cgo_import_dynamic runtime._ResumeThread ResumeThread%1 "kernel32.dll"
    49  //go:cgo_import_dynamic runtime._RtlLookupFunctionEntry RtlLookupFunctionEntry%3 "kernel32.dll"
    50  //go:cgo_import_dynamic runtime._RtlVirtualUnwind  RtlVirtualUnwind%8 "kernel32.dll"
    51  //go:cgo_import_dynamic runtime._SetConsoleCtrlHandler SetConsoleCtrlHandler%2 "kernel32.dll"
    52  //go:cgo_import_dynamic runtime._SetErrorMode SetErrorMode%1 "kernel32.dll"
    53  //go:cgo_import_dynamic runtime._SetEvent SetEvent%1 "kernel32.dll"
    54  //go:cgo_import_dynamic runtime._SetProcessPriorityBoost SetProcessPriorityBoost%2 "kernel32.dll"
    55  //go:cgo_import_dynamic runtime._SetThreadPriority SetThreadPriority%2 "kernel32.dll"
    56  //go:cgo_import_dynamic runtime._SetUnhandledExceptionFilter SetUnhandledExceptionFilter%1 "kernel32.dll"
    57  //go:cgo_import_dynamic runtime._SetWaitableTimer SetWaitableTimer%6 "kernel32.dll"
    58  //go:cgo_import_dynamic runtime._SuspendThread SuspendThread%1 "kernel32.dll"
    59  //go:cgo_import_dynamic runtime._SwitchToThread SwitchToThread%0 "kernel32.dll"
    60  //go:cgo_import_dynamic runtime._TlsAlloc TlsAlloc%0 "kernel32.dll"
    61  //go:cgo_import_dynamic runtime._VirtualAlloc VirtualAlloc%4 "kernel32.dll"
    62  //go:cgo_import_dynamic runtime._VirtualFree VirtualFree%3 "kernel32.dll"
    63  //go:cgo_import_dynamic runtime._VirtualQuery VirtualQuery%3 "kernel32.dll"
    64  //go:cgo_import_dynamic runtime._WaitForSingleObject WaitForSingleObject%2 "kernel32.dll"
    65  //go:cgo_import_dynamic runtime._WaitForMultipleObjects WaitForMultipleObjects%4 "kernel32.dll"
    66  //go:cgo_import_dynamic runtime._WerGetFlags WerGetFlags%2 "kernel32.dll"
    67  //go:cgo_import_dynamic runtime._WerSetFlags WerSetFlags%1 "kernel32.dll"
    68  //go:cgo_import_dynamic runtime._WriteConsoleW WriteConsoleW%5 "kernel32.dll"
    69  //go:cgo_import_dynamic runtime._WriteFile WriteFile%5 "kernel32.dll"
    70  
    71  type stdFunction unsafe.Pointer
    72  
    73  var (
    74  	// Following syscalls are available on every Windows PC.
    75  	// All these variables are set by the Windows executable
    76  	// loader before the Go program starts.
    77  	_AddVectoredContinueHandler,
    78  	_AddVectoredExceptionHandler,
    79  	_CloseHandle,
    80  	_CreateEventA,
    81  	_CreateIoCompletionPort,
    82  	_CreateThread,
    83  	_CreateWaitableTimerA,
    84  	_CreateWaitableTimerExW,
    85  	_DuplicateHandle,
    86  	_ExitProcess,
    87  	_FreeEnvironmentStringsW,
    88  	_GetConsoleMode,
    89  	_GetCurrentThreadId,
    90  	_GetEnvironmentStringsW,
    91  	_GetErrorMode,
    92  	_GetProcAddress,
    93  	_GetProcessAffinityMask,
    94  	_GetQueuedCompletionStatusEx,
    95  	_GetStdHandle,
    96  	_GetSystemDirectoryA,
    97  	_GetSystemInfo,
    98  	_GetThreadContext,
    99  	_SetThreadContext,
   100  	_LoadLibraryExW,
   101  	_LoadLibraryW,
   102  	_PostQueuedCompletionStatus,
   103  	_QueryPerformanceCounter,
   104  	_QueryPerformanceFrequency,
   105  	_RaiseFailFastException,
   106  	_ResumeThread,
   107  	_RtlLookupFunctionEntry,
   108  	_RtlVirtualUnwind,
   109  	_SetConsoleCtrlHandler,
   110  	_SetErrorMode,
   111  	_SetEvent,
   112  	_SetProcessPriorityBoost,
   113  	_SetThreadPriority,
   114  	_SetUnhandledExceptionFilter,
   115  	_SetWaitableTimer,
   116  	_SuspendThread,
   117  	_SwitchToThread,
   118  	_TlsAlloc,
   119  	_VirtualAlloc,
   120  	_VirtualFree,
   121  	_VirtualQuery,
   122  	_WaitForSingleObject,
   123  	_WaitForMultipleObjects,
   124  	_WerGetFlags,
   125  	_WerSetFlags,
   126  	_WriteConsoleW,
   127  	_WriteFile,
   128  	_ stdFunction
   129  
   130  	// Use ProcessPrng to generate cryptographically random data.
   131  	_ProcessPrng stdFunction
   132  
   133  	// Load ntdll.dll manually during startup, otherwise Mingw
   134  	// links wrong printf function to cgo executable (see issue
   135  	// 12030 for details).
   136  	_NtCreateWaitCompletionPacket    stdFunction
   137  	_NtAssociateWaitCompletionPacket stdFunction
   138  	_NtCancelWaitCompletionPacket    stdFunction
   139  	_RtlGetCurrentPeb                stdFunction
   140  	_RtlGetVersion                   stdFunction
   141  
   142  	// These are from non-kernel32.dll, so we prefer to LoadLibraryEx them.
   143  	_timeBeginPeriod,
   144  	_timeEndPeriod,
   145  	_ stdFunction
   146  )
   147  
   148  var (
   149  	bcryptprimitivesdll = [...]uint16{'b', 'c', 'r', 'y', 'p', 't', 'p', 'r', 'i', 'm', 'i', 't', 'i', 'v', 'e', 's', '.', 'd', 'l', 'l', 0}
   150  	ntdlldll            = [...]uint16{'n', 't', 'd', 'l', 'l', '.', 'd', 'l', 'l', 0}
   151  	powrprofdll         = [...]uint16{'p', 'o', 'w', 'r', 'p', 'r', 'o', 'f', '.', 'd', 'l', 'l', 0}
   152  	winmmdll            = [...]uint16{'w', 'i', 'n', 'm', 'm', '.', 'd', 'l', 'l', 0}
   153  )
   154  
   155  // Function to be called by windows CreateThread
   156  // to start new os thread.
   157  func tstart_stdcall(newm *m)
   158  
   159  // Init-time helper
   160  func wintls()
   161  
   162  type mOS struct {
   163  	threadLock mutex   // protects "thread" and prevents closing
   164  	thread     uintptr // thread handle
   165  
   166  	waitsema   uintptr // semaphore for parking on locks
   167  	resumesema uintptr // semaphore to indicate suspend/resume
   168  
   169  	highResTimer   uintptr // high resolution timer handle used in usleep
   170  	waitIocpTimer  uintptr // high resolution timer handle used in netpoll
   171  	waitIocpHandle uintptr // wait completion handle used in netpoll
   172  
   173  	// preemptExtLock synchronizes preemptM with entry/exit from
   174  	// external C code.
   175  	//
   176  	// This protects against races between preemptM calling
   177  	// SuspendThread and external code on this thread calling
   178  	// ExitProcess. If these happen concurrently, it's possible to
   179  	// exit the suspending thread and suspend the exiting thread,
   180  	// leading to deadlock.
   181  	//
   182  	// 0 indicates this M is not being preempted or in external
   183  	// code. Entering external code CASes this from 0 to 1. If
   184  	// this fails, a preemption is in progress, so the thread must
   185  	// wait for the preemption. preemptM also CASes this from 0 to
   186  	// 1. If this fails, the preemption fails (as it would if the
   187  	// PC weren't in Go code). The value is reset to 0 when
   188  	// returning from external code or after a preemption is
   189  	// complete.
   190  	//
   191  	// TODO(austin): We may not need this if preemption were more
   192  	// tightly synchronized on the G/P status and preemption
   193  	// blocked transition into _Gsyscall/_Psyscall.
   194  	preemptExtLock uint32
   195  }
   196  
   197  // Stubs so tests can link correctly. These should never be called.
   198  func open(name *byte, mode, perm int32) int32 {
   199  	throw("unimplemented")
   200  	return -1
   201  }
   202  func closefd(fd int32) int32 {
   203  	throw("unimplemented")
   204  	return -1
   205  }
   206  func read(fd int32, p unsafe.Pointer, n int32) int32 {
   207  	throw("unimplemented")
   208  	return -1
   209  }
   210  
   211  type sigset struct{}
   212  
   213  // Call a Windows function with stdcall conventions,
   214  // and switch to os stack during the call.
   215  func asmstdcall(fn unsafe.Pointer)
   216  
   217  var asmstdcallAddr unsafe.Pointer
   218  
   219  type winlibcall libcall
   220  
   221  func windowsFindfunc(lib uintptr, name []byte) stdFunction {
   222  	if name[len(name)-1] != 0 {
   223  		throw("usage")
   224  	}
   225  	f := stdcall2(_GetProcAddress, lib, uintptr(unsafe.Pointer(&name[0])))
   226  	return stdFunction(unsafe.Pointer(f))
   227  }
   228  
   229  const _MAX_PATH = 260 // https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
   230  var sysDirectory [_MAX_PATH + 1]byte
   231  var sysDirectoryLen uintptr
   232  
   233  func initSysDirectory() {
   234  	l := stdcall2(_GetSystemDirectoryA, uintptr(unsafe.Pointer(&sysDirectory[0])), uintptr(len(sysDirectory)-1))
   235  	if l == 0 || l > uintptr(len(sysDirectory)-1) {
   236  		throw("Unable to determine system directory")
   237  	}
   238  	sysDirectory[l] = '\\'
   239  	sysDirectoryLen = l + 1
   240  }
   241  
   242  //go:linkname windows_GetSystemDirectory internal/syscall/windows.GetSystemDirectory
   243  func windows_GetSystemDirectory() string {
   244  	return unsafe.String(&sysDirectory[0], sysDirectoryLen)
   245  }
   246  
   247  func windowsLoadSystemLib(name []uint16) uintptr {
   248  	return stdcall3(_LoadLibraryExW, uintptr(unsafe.Pointer(&name[0])), 0, _LOAD_LIBRARY_SEARCH_SYSTEM32)
   249  }
   250  
   251  //go:linkname windows_QueryPerformanceCounter internal/syscall/windows.QueryPerformanceCounter
   252  func windows_QueryPerformanceCounter() int64 {
   253  	var counter int64
   254  	stdcall1(_QueryPerformanceCounter, uintptr(unsafe.Pointer(&counter)))
   255  	return counter
   256  }
   257  
   258  //go:linkname windows_QueryPerformanceFrequency internal/syscall/windows.QueryPerformanceFrequency
   259  func windows_QueryPerformanceFrequency() int64 {
   260  	var frequency int64
   261  	stdcall1(_QueryPerformanceFrequency, uintptr(unsafe.Pointer(&frequency)))
   262  	return frequency
   263  }
   264  
   265  func loadOptionalSyscalls() {
   266  	bcryptPrimitives := windowsLoadSystemLib(bcryptprimitivesdll[:])
   267  	if bcryptPrimitives == 0 {
   268  		throw("bcryptprimitives.dll not found")
   269  	}
   270  	_ProcessPrng = windowsFindfunc(bcryptPrimitives, []byte("ProcessPrng\000"))
   271  
   272  	n32 := windowsLoadSystemLib(ntdlldll[:])
   273  	if n32 == 0 {
   274  		throw("ntdll.dll not found")
   275  	}
   276  	_NtCreateWaitCompletionPacket = windowsFindfunc(n32, []byte("NtCreateWaitCompletionPacket\000"))
   277  	if _NtCreateWaitCompletionPacket != nil {
   278  		// These functions should exists if NtCreateWaitCompletionPacket exists.
   279  		_NtAssociateWaitCompletionPacket = windowsFindfunc(n32, []byte("NtAssociateWaitCompletionPacket\000"))
   280  		if _NtAssociateWaitCompletionPacket == nil {
   281  			throw("NtCreateWaitCompletionPacket exists but NtAssociateWaitCompletionPacket does not")
   282  		}
   283  		_NtCancelWaitCompletionPacket = windowsFindfunc(n32, []byte("NtCancelWaitCompletionPacket\000"))
   284  		if _NtCancelWaitCompletionPacket == nil {
   285  			throw("NtCreateWaitCompletionPacket exists but NtCancelWaitCompletionPacket does not")
   286  		}
   287  	}
   288  	_RtlGetCurrentPeb = windowsFindfunc(n32, []byte("RtlGetCurrentPeb\000"))
   289  	_RtlGetVersion = windowsFindfunc(n32, []byte("RtlGetVersion\000"))
   290  }
   291  
   292  func monitorSuspendResume() {
   293  	const (
   294  		_DEVICE_NOTIFY_CALLBACK = 2
   295  	)
   296  	type _DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS struct {
   297  		callback uintptr
   298  		context  uintptr
   299  	}
   300  
   301  	powrprof := windowsLoadSystemLib(powrprofdll[:])
   302  	if powrprof == 0 {
   303  		return // Running on Windows 7, where we don't need it anyway.
   304  	}
   305  	powerRegisterSuspendResumeNotification := windowsFindfunc(powrprof, []byte("PowerRegisterSuspendResumeNotification\000"))
   306  	if powerRegisterSuspendResumeNotification == nil {
   307  		return // Running on Windows 7, where we don't need it anyway.
   308  	}
   309  	var fn any = func(context uintptr, changeType uint32, setting uintptr) uintptr {
   310  		for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink {
   311  			if mp.resumesema != 0 {
   312  				stdcall1(_SetEvent, mp.resumesema)
   313  			}
   314  		}
   315  		return 0
   316  	}
   317  	params := _DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS{
   318  		callback: compileCallback(*efaceOf(&fn), true),
   319  	}
   320  	handle := uintptr(0)
   321  	stdcall3(powerRegisterSuspendResumeNotification, _DEVICE_NOTIFY_CALLBACK,
   322  		uintptr(unsafe.Pointer(&params)), uintptr(unsafe.Pointer(&handle)))
   323  }
   324  
   325  func getCPUCount() int32 {
   326  	var mask, sysmask uintptr
   327  	ret := stdcall3(_GetProcessAffinityMask, currentProcess, uintptr(unsafe.Pointer(&mask)), uintptr(unsafe.Pointer(&sysmask)))
   328  	if ret != 0 {
   329  		n := 0
   330  		maskbits := int(unsafe.Sizeof(mask) * 8)
   331  		for i := 0; i < maskbits; i++ {
   332  			if mask&(1<<uint(i)) != 0 {
   333  				n++
   334  			}
   335  		}
   336  		if n != 0 {
   337  			return int32(n)
   338  		}
   339  	}
   340  	// use GetSystemInfo if GetProcessAffinityMask fails
   341  	var info systeminfo
   342  	stdcall1(_GetSystemInfo, uintptr(unsafe.Pointer(&info)))
   343  	return int32(info.dwnumberofprocessors)
   344  }
   345  
   346  func getPageSize() uintptr {
   347  	var info systeminfo
   348  	stdcall1(_GetSystemInfo, uintptr(unsafe.Pointer(&info)))
   349  	return uintptr(info.dwpagesize)
   350  }
   351  
   352  const (
   353  	currentProcess = ^uintptr(0) // -1 = current process
   354  	currentThread  = ^uintptr(1) // -2 = current thread
   355  )
   356  
   357  // in sys_windows_386.s and sys_windows_amd64.s:
   358  func getlasterror() uint32
   359  
   360  var timeBeginPeriodRetValue uint32
   361  
   362  // osRelaxMinNS indicates that sysmon shouldn't osRelax if the next
   363  // timer is less than 60 ms from now. Since osRelaxing may reduce
   364  // timer resolution to 15.6 ms, this keeps timer error under roughly 1
   365  // part in 4.
   366  const osRelaxMinNS = 60 * 1e6
   367  
   368  // osRelax is called by the scheduler when transitioning to and from
   369  // all Ps being idle.
   370  //
   371  // Some versions of Windows have high resolution timer. For those
   372  // versions osRelax is noop.
   373  // For Windows versions without high resolution timer, osRelax
   374  // adjusts the system-wide timer resolution. Go needs a
   375  // high resolution timer while running and there's little extra cost
   376  // if we're already using the CPU, but if all Ps are idle there's no
   377  // need to consume extra power to drive the high-res timer.
   378  func osRelax(relax bool) uint32 {
   379  	if haveHighResTimer {
   380  		// If the high resolution timer is available, the runtime uses the timer
   381  		// to sleep for short durations. This means there's no need to adjust
   382  		// the global clock frequency.
   383  		return 0
   384  	}
   385  
   386  	if relax {
   387  		return uint32(stdcall1(_timeEndPeriod, 1))
   388  	} else {
   389  		return uint32(stdcall1(_timeBeginPeriod, 1))
   390  	}
   391  }
   392  
   393  // haveHighResTimer indicates that the CreateWaitableTimerEx
   394  // CREATE_WAITABLE_TIMER_HIGH_RESOLUTION flag is available.
   395  var haveHighResTimer = false
   396  
   397  // haveHighResSleep indicates that NtCreateWaitCompletionPacket
   398  // exists and haveHighResTimer is true.
   399  // NtCreateWaitCompletionPacket has been available since Windows 10,
   400  // but has just been publicly documented, so some platforms, like Wine,
   401  // doesn't support it yet.
   402  var haveHighResSleep = false
   403  
   404  // createHighResTimer calls CreateWaitableTimerEx with
   405  // CREATE_WAITABLE_TIMER_HIGH_RESOLUTION flag to create high
   406  // resolution timer. createHighResTimer returns new timer
   407  // handle or 0, if CreateWaitableTimerEx failed.
   408  func createHighResTimer() uintptr {
   409  	const (
   410  		// As per @jstarks, see
   411  		// https://github.com/golang/go/issues/8687#issuecomment-656259353
   412  		_CREATE_WAITABLE_TIMER_HIGH_RESOLUTION = 0x00000002
   413  
   414  		_SYNCHRONIZE        = 0x00100000
   415  		_TIMER_QUERY_STATE  = 0x0001
   416  		_TIMER_MODIFY_STATE = 0x0002
   417  	)
   418  	return stdcall4(_CreateWaitableTimerExW, 0, 0,
   419  		_CREATE_WAITABLE_TIMER_HIGH_RESOLUTION,
   420  		_SYNCHRONIZE|_TIMER_QUERY_STATE|_TIMER_MODIFY_STATE)
   421  }
   422  
   423  func initHighResTimer() {
   424  	h := createHighResTimer()
   425  	if h != 0 {
   426  		haveHighResTimer = true
   427  		haveHighResSleep = _NtCreateWaitCompletionPacket != nil
   428  		stdcall1(_CloseHandle, h)
   429  	} else {
   430  		// Only load winmm.dll if we need it.
   431  		// This avoids a dependency on winmm.dll for Go programs
   432  		// that run on new Windows versions.
   433  		m32 := windowsLoadSystemLib(winmmdll[:])
   434  		if m32 == 0 {
   435  			print("runtime: LoadLibraryExW failed; errno=", getlasterror(), "\n")
   436  			throw("winmm.dll not found")
   437  		}
   438  		_timeBeginPeriod = windowsFindfunc(m32, []byte("timeBeginPeriod\000"))
   439  		_timeEndPeriod = windowsFindfunc(m32, []byte("timeEndPeriod\000"))
   440  		if _timeBeginPeriod == nil || _timeEndPeriod == nil {
   441  			print("runtime: GetProcAddress failed; errno=", getlasterror(), "\n")
   442  			throw("timeBegin/EndPeriod not found")
   443  		}
   444  	}
   445  }
   446  
   447  //go:linkname canUseLongPaths internal/syscall/windows.CanUseLongPaths
   448  var canUseLongPaths bool
   449  
   450  // initLongPathSupport enables long path support.
   451  func initLongPathSupport() {
   452  	const (
   453  		IsLongPathAwareProcess = 0x80
   454  		PebBitFieldOffset      = 3
   455  	)
   456  
   457  	// Check that we're ≥ 10.0.15063.
   458  	info := _OSVERSIONINFOW{}
   459  	info.osVersionInfoSize = uint32(unsafe.Sizeof(info))
   460  	stdcall1(_RtlGetVersion, uintptr(unsafe.Pointer(&info)))
   461  	if info.majorVersion < 10 || (info.majorVersion == 10 && info.minorVersion == 0 && info.buildNumber < 15063) {
   462  		return
   463  	}
   464  
   465  	// Set the IsLongPathAwareProcess flag of the PEB's bit field.
   466  	// This flag is not documented, but it's known to be used
   467  	// by Windows to enable long path support.
   468  	bitField := (*byte)(unsafe.Pointer(stdcall0(_RtlGetCurrentPeb) + PebBitFieldOffset))
   469  	*bitField |= IsLongPathAwareProcess
   470  
   471  	canUseLongPaths = true
   472  }
   473  
   474  func osinit() {
   475  	asmstdcallAddr = unsafe.Pointer(abi.FuncPCABI0(asmstdcall))
   476  
   477  	loadOptionalSyscalls()
   478  
   479  	preventErrorDialogs()
   480  
   481  	initExceptionHandler()
   482  
   483  	initHighResTimer()
   484  	timeBeginPeriodRetValue = osRelax(false)
   485  
   486  	initSysDirectory()
   487  	initLongPathSupport()
   488  
   489  	numCPUStartup = getCPUCount()
   490  
   491  	physPageSize = getPageSize()
   492  
   493  	// Windows dynamic priority boosting assumes that a process has different types
   494  	// of dedicated threads -- GUI, IO, computational, etc. Go processes use
   495  	// equivalent threads that all do a mix of GUI, IO, computations, etc.
   496  	// In such context dynamic priority boosting does nothing but harm, so we turn it off.
   497  	stdcall2(_SetProcessPriorityBoost, currentProcess, 1)
   498  }
   499  
   500  //go:nosplit
   501  func readRandom(r []byte) int {
   502  	n := 0
   503  	if stdcall2(_ProcessPrng, uintptr(unsafe.Pointer(&r[0])), uintptr(len(r)))&0xff != 0 {
   504  		n = len(r)
   505  	}
   506  	return n
   507  }
   508  
   509  func goenvs() {
   510  	// strings is a pointer to environment variable pairs in the form:
   511  	//     "envA=valA\x00envB=valB\x00\x00" (in UTF-16)
   512  	// Two consecutive zero bytes end the list.
   513  	strings := unsafe.Pointer(stdcall0(_GetEnvironmentStringsW))
   514  	p := (*[1 << 24]uint16)(strings)[:]
   515  
   516  	n := 0
   517  	for from, i := 0, 0; true; i++ {
   518  		if p[i] == 0 {
   519  			// empty string marks the end
   520  			if i == from {
   521  				break
   522  			}
   523  			from = i + 1
   524  			n++
   525  		}
   526  	}
   527  	envs = make([]string, n)
   528  
   529  	for i := range envs {
   530  		envs[i] = gostringw(&p[0])
   531  		for p[0] != 0 {
   532  			p = p[1:]
   533  		}
   534  		p = p[1:] // skip nil byte
   535  	}
   536  
   537  	stdcall1(_FreeEnvironmentStringsW, uintptr(strings))
   538  
   539  	// We call these all the way here, late in init, so that malloc works
   540  	// for the callback functions these generate.
   541  	var fn any = ctrlHandler
   542  	ctrlHandlerPC := compileCallback(*efaceOf(&fn), true)
   543  	stdcall2(_SetConsoleCtrlHandler, ctrlHandlerPC, 1)
   544  
   545  	monitorSuspendResume()
   546  }
   547  
   548  // exiting is set to non-zero when the process is exiting.
   549  var exiting uint32
   550  
   551  //go:nosplit
   552  func exit(code int32) {
   553  	// Disallow thread suspension for preemption. Otherwise,
   554  	// ExitProcess and SuspendThread can race: SuspendThread
   555  	// queues a suspension request for this thread, ExitProcess
   556  	// kills the suspending thread, and then this thread suspends.
   557  	lock(&suspendLock)
   558  	atomic.Store(&exiting, 1)
   559  	stdcall1(_ExitProcess, uintptr(code))
   560  }
   561  
   562  // write1 must be nosplit because it's used as a last resort in
   563  // functions like badmorestackg0. In such cases, we'll always take the
   564  // ASCII path.
   565  //
   566  //go:nosplit
   567  func write1(fd uintptr, buf unsafe.Pointer, n int32) int32 {
   568  	const (
   569  		_STD_OUTPUT_HANDLE = ^uintptr(10) // -11
   570  		_STD_ERROR_HANDLE  = ^uintptr(11) // -12
   571  	)
   572  	var handle uintptr
   573  	switch fd {
   574  	case 1:
   575  		handle = stdcall1(_GetStdHandle, _STD_OUTPUT_HANDLE)
   576  	case 2:
   577  		handle = stdcall1(_GetStdHandle, _STD_ERROR_HANDLE)
   578  	default:
   579  		// assume fd is real windows handle.
   580  		handle = fd
   581  	}
   582  	isASCII := true
   583  	b := (*[1 << 30]byte)(buf)[:n]
   584  	for _, x := range b {
   585  		if x >= 0x80 {
   586  			isASCII = false
   587  			break
   588  		}
   589  	}
   590  
   591  	if !isASCII {
   592  		var m uint32
   593  		isConsole := stdcall2(_GetConsoleMode, handle, uintptr(unsafe.Pointer(&m))) != 0
   594  		// If this is a console output, various non-unicode code pages can be in use.
   595  		// Use the dedicated WriteConsole call to ensure unicode is printed correctly.
   596  		if isConsole {
   597  			return int32(writeConsole(handle, buf, n))
   598  		}
   599  	}
   600  	var written uint32
   601  	stdcall5(_WriteFile, handle, uintptr(buf), uintptr(n), uintptr(unsafe.Pointer(&written)), 0)
   602  	return int32(written)
   603  }
   604  
   605  var (
   606  	utf16ConsoleBack     [1000]uint16
   607  	utf16ConsoleBackLock mutex
   608  )
   609  
   610  // writeConsole writes bufLen bytes from buf to the console File.
   611  // It returns the number of bytes written.
   612  func writeConsole(handle uintptr, buf unsafe.Pointer, bufLen int32) int {
   613  	const surr2 = (surrogateMin + surrogateMax + 1) / 2
   614  
   615  	// Do not use defer for unlock. May cause issues when printing a panic.
   616  	lock(&utf16ConsoleBackLock)
   617  
   618  	b := (*[1 << 30]byte)(buf)[:bufLen]
   619  	s := *(*string)(unsafe.Pointer(&b))
   620  
   621  	utf16tmp := utf16ConsoleBack[:]
   622  
   623  	total := len(s)
   624  	w := 0
   625  	for _, r := range s {
   626  		if w >= len(utf16tmp)-2 {
   627  			writeConsoleUTF16(handle, utf16tmp[:w])
   628  			w = 0
   629  		}
   630  		if r < 0x10000 {
   631  			utf16tmp[w] = uint16(r)
   632  			w++
   633  		} else {
   634  			r -= 0x10000
   635  			utf16tmp[w] = surrogateMin + uint16(r>>10)&0x3ff
   636  			utf16tmp[w+1] = surr2 + uint16(r)&0x3ff
   637  			w += 2
   638  		}
   639  	}
   640  	writeConsoleUTF16(handle, utf16tmp[:w])
   641  	unlock(&utf16ConsoleBackLock)
   642  	return total
   643  }
   644  
   645  // writeConsoleUTF16 is the dedicated windows calls that correctly prints
   646  // to the console regardless of the current code page. Input is utf-16 code points.
   647  // The handle must be a console handle.
   648  func writeConsoleUTF16(handle uintptr, b []uint16) {
   649  	l := uint32(len(b))
   650  	if l == 0 {
   651  		return
   652  	}
   653  	var written uint32
   654  	stdcall5(_WriteConsoleW,
   655  		handle,
   656  		uintptr(unsafe.Pointer(&b[0])),
   657  		uintptr(l),
   658  		uintptr(unsafe.Pointer(&written)),
   659  		0,
   660  	)
   661  	return
   662  }
   663  
   664  //go:nosplit
   665  func semasleep(ns int64) int32 {
   666  	const (
   667  		_WAIT_ABANDONED = 0x00000080
   668  		_WAIT_OBJECT_0  = 0x00000000
   669  		_WAIT_TIMEOUT   = 0x00000102
   670  		_WAIT_FAILED    = 0xFFFFFFFF
   671  	)
   672  
   673  	var result uintptr
   674  	if ns < 0 {
   675  		result = stdcall2(_WaitForSingleObject, getg().m.waitsema, uintptr(_INFINITE))
   676  	} else {
   677  		start := nanotime()
   678  		elapsed := int64(0)
   679  		for {
   680  			ms := int64(timediv(ns-elapsed, 1000000, nil))
   681  			if ms == 0 {
   682  				ms = 1
   683  			}
   684  			result = stdcall4(_WaitForMultipleObjects, 2,
   685  				uintptr(unsafe.Pointer(&[2]uintptr{getg().m.waitsema, getg().m.resumesema})),
   686  				0, uintptr(ms))
   687  			if result != _WAIT_OBJECT_0+1 {
   688  				// Not a suspend/resume event
   689  				break
   690  			}
   691  			elapsed = nanotime() - start
   692  			if elapsed >= ns {
   693  				return -1
   694  			}
   695  		}
   696  	}
   697  	switch result {
   698  	case _WAIT_OBJECT_0: // Signaled
   699  		return 0
   700  
   701  	case _WAIT_TIMEOUT:
   702  		return -1
   703  
   704  	case _WAIT_ABANDONED:
   705  		systemstack(func() {
   706  			throw("runtime.semasleep wait_abandoned")
   707  		})
   708  
   709  	case _WAIT_FAILED:
   710  		systemstack(func() {
   711  			print("runtime: waitforsingleobject wait_failed; errno=", getlasterror(), "\n")
   712  			throw("runtime.semasleep wait_failed")
   713  		})
   714  
   715  	default:
   716  		systemstack(func() {
   717  			print("runtime: waitforsingleobject unexpected; result=", result, "\n")
   718  			throw("runtime.semasleep unexpected")
   719  		})
   720  	}
   721  
   722  	return -1 // unreachable
   723  }
   724  
   725  //go:nosplit
   726  func semawakeup(mp *m) {
   727  	if stdcall1(_SetEvent, mp.waitsema) == 0 {
   728  		systemstack(func() {
   729  			print("runtime: setevent failed; errno=", getlasterror(), "\n")
   730  			throw("runtime.semawakeup")
   731  		})
   732  	}
   733  }
   734  
   735  //go:nosplit
   736  func semacreate(mp *m) {
   737  	if mp.waitsema != 0 {
   738  		return
   739  	}
   740  	mp.waitsema = stdcall4(_CreateEventA, 0, 0, 0, 0)
   741  	if mp.waitsema == 0 {
   742  		systemstack(func() {
   743  			print("runtime: createevent failed; errno=", getlasterror(), "\n")
   744  			throw("runtime.semacreate")
   745  		})
   746  	}
   747  	mp.resumesema = stdcall4(_CreateEventA, 0, 0, 0, 0)
   748  	if mp.resumesema == 0 {
   749  		systemstack(func() {
   750  			print("runtime: createevent failed; errno=", getlasterror(), "\n")
   751  			throw("runtime.semacreate")
   752  		})
   753  		stdcall1(_CloseHandle, mp.waitsema)
   754  		mp.waitsema = 0
   755  	}
   756  }
   757  
   758  // May run with m.p==nil, so write barriers are not allowed. This
   759  // function is called by newosproc0, so it is also required to
   760  // operate without stack guards.
   761  //
   762  //go:nowritebarrierrec
   763  //go:nosplit
   764  func newosproc(mp *m) {
   765  	// We pass 0 for the stack size to use the default for this binary.
   766  	thandle := stdcall6(_CreateThread, 0, 0,
   767  		abi.FuncPCABI0(tstart_stdcall), uintptr(unsafe.Pointer(mp)),
   768  		0, 0)
   769  
   770  	if thandle == 0 {
   771  		if atomic.Load(&exiting) != 0 {
   772  			// CreateThread may fail if called
   773  			// concurrently with ExitProcess. If this
   774  			// happens, just freeze this thread and let
   775  			// the process exit. See issue #18253.
   776  			lock(&deadlock)
   777  			lock(&deadlock)
   778  		}
   779  		print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", getlasterror(), ")\n")
   780  		throw("runtime.newosproc")
   781  	}
   782  
   783  	// Close thandle to avoid leaking the thread object if it exits.
   784  	stdcall1(_CloseHandle, thandle)
   785  }
   786  
   787  // Used by the C library build mode. On Linux this function would allocate a
   788  // stack, but that's not necessary for Windows. No stack guards are present
   789  // and the GC has not been initialized, so write barriers will fail.
   790  //
   791  //go:nowritebarrierrec
   792  //go:nosplit
   793  func newosproc0(mp *m, stk unsafe.Pointer) {
   794  	// TODO: this is completely broken. The args passed to newosproc0 (in asm_amd64.s)
   795  	// are stacksize and function, not *m and stack.
   796  	// Check os_linux.go for an implementation that might actually work.
   797  	throw("bad newosproc0")
   798  }
   799  
   800  func exitThread(wait *atomic.Uint32) {
   801  	// We should never reach exitThread on Windows because we let
   802  	// the OS clean up threads.
   803  	throw("exitThread")
   804  }
   805  
   806  // Called to initialize a new m (including the bootstrap m).
   807  // Called on the parent thread (main thread in case of bootstrap), can allocate memory.
   808  func mpreinit(mp *m) {
   809  }
   810  
   811  //go:nosplit
   812  func sigsave(p *sigset) {
   813  }
   814  
   815  //go:nosplit
   816  func msigrestore(sigmask sigset) {
   817  }
   818  
   819  //go:nosplit
   820  //go:nowritebarrierrec
   821  func clearSignalHandlers() {
   822  }
   823  
   824  //go:nosplit
   825  func sigblock(exiting bool) {
   826  }
   827  
   828  // Called to initialize a new m (including the bootstrap m).
   829  // Called on the new thread, cannot allocate Go memory.
   830  func minit() {
   831  	var thandle uintptr
   832  	if stdcall7(_DuplicateHandle, currentProcess, currentThread, currentProcess, uintptr(unsafe.Pointer(&thandle)), 0, 0, _DUPLICATE_SAME_ACCESS) == 0 {
   833  		print("runtime.minit: duplicatehandle failed; errno=", getlasterror(), "\n")
   834  		throw("runtime.minit: duplicatehandle failed")
   835  	}
   836  
   837  	mp := getg().m
   838  	lock(&mp.threadLock)
   839  	mp.thread = thandle
   840  	mp.procid = uint64(stdcall0(_GetCurrentThreadId))
   841  
   842  	// Configure usleep timer, if possible.
   843  	if mp.highResTimer == 0 && haveHighResTimer {
   844  		mp.highResTimer = createHighResTimer()
   845  		if mp.highResTimer == 0 {
   846  			print("runtime: CreateWaitableTimerEx failed; errno=", getlasterror(), "\n")
   847  			throw("CreateWaitableTimerEx when creating timer failed")
   848  		}
   849  	}
   850  	if mp.waitIocpHandle == 0 && haveHighResSleep {
   851  		mp.waitIocpTimer = createHighResTimer()
   852  		if mp.waitIocpTimer == 0 {
   853  			print("runtime: CreateWaitableTimerEx failed; errno=", getlasterror(), "\n")
   854  			throw("CreateWaitableTimerEx when creating timer failed")
   855  		}
   856  		const GENERIC_ALL = 0x10000000
   857  		errno := stdcall3(_NtCreateWaitCompletionPacket, uintptr(unsafe.Pointer(&mp.waitIocpHandle)), GENERIC_ALL, 0)
   858  		if mp.waitIocpHandle == 0 {
   859  			print("runtime: NtCreateWaitCompletionPacket failed; errno=", errno, "\n")
   860  			throw("NtCreateWaitCompletionPacket failed")
   861  		}
   862  	}
   863  	unlock(&mp.threadLock)
   864  
   865  	// Query the true stack base from the OS. Currently we're
   866  	// running on a small assumed stack.
   867  	var mbi memoryBasicInformation
   868  	res := stdcall3(_VirtualQuery, uintptr(unsafe.Pointer(&mbi)), uintptr(unsafe.Pointer(&mbi)), unsafe.Sizeof(mbi))
   869  	if res == 0 {
   870  		print("runtime: VirtualQuery failed; errno=", getlasterror(), "\n")
   871  		throw("VirtualQuery for stack base failed")
   872  	}
   873  	// The system leaves an 8K PAGE_GUARD region at the bottom of
   874  	// the stack (in theory VirtualQuery isn't supposed to include
   875  	// that, but it does). Add an additional 8K of slop for
   876  	// calling C functions that don't have stack checks and for
   877  	// lastcontinuehandler. We shouldn't be anywhere near this
   878  	// bound anyway.
   879  	base := mbi.allocationBase + 16<<10
   880  	// Sanity check the stack bounds.
   881  	g0 := getg()
   882  	if base > g0.stack.hi || g0.stack.hi-base > 64<<20 {
   883  		print("runtime: g0 stack [", hex(base), ",", hex(g0.stack.hi), ")\n")
   884  		throw("bad g0 stack")
   885  	}
   886  	g0.stack.lo = base
   887  	g0.stackguard0 = g0.stack.lo + stackGuard
   888  	g0.stackguard1 = g0.stackguard0
   889  	// Sanity check the SP.
   890  	stackcheck()
   891  }
   892  
   893  // Called from dropm to undo the effect of an minit.
   894  //
   895  //go:nosplit
   896  func unminit() {
   897  	mp := getg().m
   898  	lock(&mp.threadLock)
   899  	if mp.thread != 0 {
   900  		stdcall1(_CloseHandle, mp.thread)
   901  		mp.thread = 0
   902  	}
   903  	unlock(&mp.threadLock)
   904  
   905  	mp.procid = 0
   906  }
   907  
   908  // Called from mexit, but not from dropm, to undo the effect of thread-owned
   909  // resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
   910  //
   911  // This always runs without a P, so //go:nowritebarrierrec is required.
   912  //
   913  //go:nowritebarrierrec
   914  //go:nosplit
   915  func mdestroy(mp *m) {
   916  	if mp.highResTimer != 0 {
   917  		stdcall1(_CloseHandle, mp.highResTimer)
   918  		mp.highResTimer = 0
   919  	}
   920  	if mp.waitIocpTimer != 0 {
   921  		stdcall1(_CloseHandle, mp.waitIocpTimer)
   922  		mp.waitIocpTimer = 0
   923  	}
   924  	if mp.waitIocpHandle != 0 {
   925  		stdcall1(_CloseHandle, mp.waitIocpHandle)
   926  		mp.waitIocpHandle = 0
   927  	}
   928  	if mp.waitsema != 0 {
   929  		stdcall1(_CloseHandle, mp.waitsema)
   930  		mp.waitsema = 0
   931  	}
   932  	if mp.resumesema != 0 {
   933  		stdcall1(_CloseHandle, mp.resumesema)
   934  		mp.resumesema = 0
   935  	}
   936  }
   937  
   938  // asmstdcall_trampoline calls asmstdcall converting from Go to C calling convention.
   939  func asmstdcall_trampoline(args unsafe.Pointer)
   940  
   941  // stdcall_no_g calls asmstdcall on os stack without using g.
   942  //
   943  //go:nosplit
   944  func stdcall_no_g(fn stdFunction, n int, args uintptr) uintptr {
   945  	libcall := libcall{
   946  		fn:   uintptr(unsafe.Pointer(fn)),
   947  		n:    uintptr(n),
   948  		args: args,
   949  	}
   950  	asmstdcall_trampoline(noescape(unsafe.Pointer(&libcall)))
   951  	return libcall.r1
   952  }
   953  
   954  // Calling stdcall on os stack.
   955  // May run during STW, so write barriers are not allowed.
   956  //
   957  //go:nowritebarrier
   958  //go:nosplit
   959  func stdcall(fn stdFunction) uintptr {
   960  	gp := getg()
   961  	mp := gp.m
   962  	mp.libcall.fn = uintptr(unsafe.Pointer(fn))
   963  	resetLibcall := false
   964  	if mp.profilehz != 0 && mp.libcallsp == 0 {
   965  		// leave pc/sp for cpu profiler
   966  		mp.libcallg.set(gp)
   967  		mp.libcallpc = sys.GetCallerPC()
   968  		// sp must be the last, because once async cpu profiler finds
   969  		// all three values to be non-zero, it will use them
   970  		mp.libcallsp = sys.GetCallerSP()
   971  		resetLibcall = true // See comment in sys_darwin.go:libcCall
   972  	}
   973  	asmcgocall(asmstdcallAddr, unsafe.Pointer(&mp.libcall))
   974  	if resetLibcall {
   975  		mp.libcallsp = 0
   976  	}
   977  	return mp.libcall.r1
   978  }
   979  
   980  //go:nosplit
   981  func stdcall0(fn stdFunction) uintptr {
   982  	mp := getg().m
   983  	mp.libcall.n = 0
   984  	mp.libcall.args = 0
   985  	return stdcall(fn)
   986  }
   987  
   988  //go:nosplit
   989  //go:cgo_unsafe_args
   990  func stdcall1(fn stdFunction, a0 uintptr) uintptr {
   991  	mp := getg().m
   992  	mp.libcall.n = 1
   993  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
   994  	return stdcall(fn)
   995  }
   996  
   997  //go:nosplit
   998  //go:cgo_unsafe_args
   999  func stdcall2(fn stdFunction, a0, a1 uintptr) uintptr {
  1000  	mp := getg().m
  1001  	mp.libcall.n = 2
  1002  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
  1003  	return stdcall(fn)
  1004  }
  1005  
  1006  //go:nosplit
  1007  //go:cgo_unsafe_args
  1008  func stdcall3(fn stdFunction, a0, a1, a2 uintptr) uintptr {
  1009  	mp := getg().m
  1010  	mp.libcall.n = 3
  1011  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
  1012  	return stdcall(fn)
  1013  }
  1014  
  1015  //go:nosplit
  1016  //go:cgo_unsafe_args
  1017  func stdcall4(fn stdFunction, a0, a1, a2, a3 uintptr) uintptr {
  1018  	mp := getg().m
  1019  	mp.libcall.n = 4
  1020  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
  1021  	return stdcall(fn)
  1022  }
  1023  
  1024  //go:nosplit
  1025  //go:cgo_unsafe_args
  1026  func stdcall5(fn stdFunction, a0, a1, a2, a3, a4 uintptr) uintptr {
  1027  	mp := getg().m
  1028  	mp.libcall.n = 5
  1029  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
  1030  	return stdcall(fn)
  1031  }
  1032  
  1033  //go:nosplit
  1034  //go:cgo_unsafe_args
  1035  func stdcall6(fn stdFunction, a0, a1, a2, a3, a4, a5 uintptr) uintptr {
  1036  	mp := getg().m
  1037  	mp.libcall.n = 6
  1038  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
  1039  	return stdcall(fn)
  1040  }
  1041  
  1042  //go:nosplit
  1043  //go:cgo_unsafe_args
  1044  func stdcall7(fn stdFunction, a0, a1, a2, a3, a4, a5, a6 uintptr) uintptr {
  1045  	mp := getg().m
  1046  	mp.libcall.n = 7
  1047  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
  1048  	return stdcall(fn)
  1049  }
  1050  
  1051  //go:nosplit
  1052  //go:cgo_unsafe_args
  1053  func stdcall8(fn stdFunction, a0, a1, a2, a3, a4, a5, a6, a7 uintptr) uintptr {
  1054  	mp := getg().m
  1055  	mp.libcall.n = 8
  1056  	mp.libcall.args = uintptr(noescape(unsafe.Pointer(&a0)))
  1057  	return stdcall(fn)
  1058  }
  1059  
  1060  // These must run on the system stack only.
  1061  
  1062  //go:nosplit
  1063  func osyield_no_g() {
  1064  	stdcall_no_g(_SwitchToThread, 0, 0)
  1065  }
  1066  
  1067  //go:nosplit
  1068  func osyield() {
  1069  	systemstack(func() {
  1070  		stdcall0(_SwitchToThread)
  1071  	})
  1072  }
  1073  
  1074  //go:nosplit
  1075  func usleep_no_g(us uint32) {
  1076  	timeout := uintptr(us) / 1000 // ms units
  1077  	args := [...]uintptr{_INVALID_HANDLE_VALUE, timeout}
  1078  	stdcall_no_g(_WaitForSingleObject, len(args), uintptr(noescape(unsafe.Pointer(&args[0]))))
  1079  }
  1080  
  1081  //go:nosplit
  1082  func usleep(us uint32) {
  1083  	systemstack(func() {
  1084  		var h, timeout uintptr
  1085  		// If the high-res timer is available and its handle has been allocated for this m, use it.
  1086  		// Otherwise fall back to the low-res one, which doesn't need a handle.
  1087  		if haveHighResTimer && getg().m.highResTimer != 0 {
  1088  			h = getg().m.highResTimer
  1089  			dt := -10 * int64(us) // relative sleep (negative), 100ns units
  1090  			stdcall6(_SetWaitableTimer, h, uintptr(unsafe.Pointer(&dt)), 0, 0, 0, 0)
  1091  			timeout = _INFINITE
  1092  		} else {
  1093  			h = _INVALID_HANDLE_VALUE
  1094  			timeout = uintptr(us) / 1000 // ms units
  1095  		}
  1096  		stdcall2(_WaitForSingleObject, h, timeout)
  1097  	})
  1098  }
  1099  
  1100  func ctrlHandler(_type uint32) uintptr {
  1101  	var s uint32
  1102  
  1103  	switch _type {
  1104  	case _CTRL_C_EVENT, _CTRL_BREAK_EVENT:
  1105  		s = _SIGINT
  1106  	case _CTRL_CLOSE_EVENT, _CTRL_LOGOFF_EVENT, _CTRL_SHUTDOWN_EVENT:
  1107  		s = _SIGTERM
  1108  	default:
  1109  		return 0
  1110  	}
  1111  
  1112  	if sigsend(s) {
  1113  		if s == _SIGTERM {
  1114  			// Windows terminates the process after this handler returns.
  1115  			// Block indefinitely to give signal handlers a chance to clean up,
  1116  			// but make sure to be properly parked first, so the rest of the
  1117  			// program can continue executing.
  1118  			block()
  1119  		}
  1120  		return 1
  1121  	}
  1122  	return 0
  1123  }
  1124  
  1125  // called from zcallback_windows_*.s to sys_windows_*.s
  1126  func callbackasm1()
  1127  
  1128  var profiletimer uintptr
  1129  
  1130  func profilem(mp *m, thread uintptr) {
  1131  	// Align Context to 16 bytes.
  1132  	var c *context
  1133  	var cbuf [unsafe.Sizeof(*c) + 15]byte
  1134  	c = (*context)(unsafe.Pointer((uintptr(unsafe.Pointer(&cbuf[15]))) &^ 15))
  1135  
  1136  	c.contextflags = _CONTEXT_CONTROL
  1137  	stdcall2(_GetThreadContext, thread, uintptr(unsafe.Pointer(c)))
  1138  
  1139  	gp := gFromSP(mp, c.sp())
  1140  
  1141  	sigprof(c.ip(), c.sp(), c.lr(), gp, mp)
  1142  }
  1143  
  1144  func gFromSP(mp *m, sp uintptr) *g {
  1145  	if gp := mp.g0; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
  1146  		return gp
  1147  	}
  1148  	if gp := mp.gsignal; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
  1149  		return gp
  1150  	}
  1151  	if gp := mp.curg; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
  1152  		return gp
  1153  	}
  1154  	return nil
  1155  }
  1156  
  1157  func profileLoop() {
  1158  	stdcall2(_SetThreadPriority, currentThread, _THREAD_PRIORITY_HIGHEST)
  1159  
  1160  	for {
  1161  		stdcall2(_WaitForSingleObject, profiletimer, _INFINITE)
  1162  		first := (*m)(atomic.Loadp(unsafe.Pointer(&allm)))
  1163  		for mp := first; mp != nil; mp = mp.alllink {
  1164  			if mp == getg().m {
  1165  				// Don't profile ourselves.
  1166  				continue
  1167  			}
  1168  
  1169  			lock(&mp.threadLock)
  1170  			// Do not profile threads blocked on Notes,
  1171  			// this includes idle worker threads,
  1172  			// idle timer thread, idle heap scavenger, etc.
  1173  			if mp.thread == 0 || mp.profilehz == 0 || mp.blocked {
  1174  				unlock(&mp.threadLock)
  1175  				continue
  1176  			}
  1177  			// Acquire our own handle to the thread.
  1178  			var thread uintptr
  1179  			if stdcall7(_DuplicateHandle, currentProcess, mp.thread, currentProcess, uintptr(unsafe.Pointer(&thread)), 0, 0, _DUPLICATE_SAME_ACCESS) == 0 {
  1180  				print("runtime: duplicatehandle failed; errno=", getlasterror(), "\n")
  1181  				throw("duplicatehandle failed")
  1182  			}
  1183  			unlock(&mp.threadLock)
  1184  
  1185  			// mp may exit between the DuplicateHandle
  1186  			// above and the SuspendThread. The handle
  1187  			// will remain valid, but SuspendThread may
  1188  			// fail.
  1189  			if int32(stdcall1(_SuspendThread, thread)) == -1 {
  1190  				// The thread no longer exists.
  1191  				stdcall1(_CloseHandle, thread)
  1192  				continue
  1193  			}
  1194  			if mp.profilehz != 0 && !mp.blocked {
  1195  				// Pass the thread handle in case mp
  1196  				// was in the process of shutting down.
  1197  				profilem(mp, thread)
  1198  			}
  1199  			stdcall1(_ResumeThread, thread)
  1200  			stdcall1(_CloseHandle, thread)
  1201  		}
  1202  	}
  1203  }
  1204  
  1205  func setProcessCPUProfiler(hz int32) {
  1206  	if profiletimer == 0 {
  1207  		var timer uintptr
  1208  		if haveHighResTimer {
  1209  			timer = createHighResTimer()
  1210  		} else {
  1211  			timer = stdcall3(_CreateWaitableTimerA, 0, 0, 0)
  1212  		}
  1213  		atomic.Storeuintptr(&profiletimer, timer)
  1214  		newm(profileLoop, nil, -1)
  1215  	}
  1216  }
  1217  
  1218  func setThreadCPUProfiler(hz int32) {
  1219  	ms := int32(0)
  1220  	due := ^int64(^uint64(1 << 63))
  1221  	if hz > 0 {
  1222  		ms = 1000 / hz
  1223  		if ms == 0 {
  1224  			ms = 1
  1225  		}
  1226  		due = int64(ms) * -10000
  1227  	}
  1228  	stdcall6(_SetWaitableTimer, profiletimer, uintptr(unsafe.Pointer(&due)), uintptr(ms), 0, 0, 0)
  1229  	atomic.Store((*uint32)(unsafe.Pointer(&getg().m.profilehz)), uint32(hz))
  1230  }
  1231  
  1232  const preemptMSupported = true
  1233  
  1234  // suspendLock protects simultaneous SuspendThread operations from
  1235  // suspending each other.
  1236  var suspendLock mutex
  1237  
  1238  func preemptM(mp *m) {
  1239  	if mp == getg().m {
  1240  		throw("self-preempt")
  1241  	}
  1242  
  1243  	// Synchronize with external code that may try to ExitProcess.
  1244  	if !atomic.Cas(&mp.preemptExtLock, 0, 1) {
  1245  		// External code is running. Fail the preemption
  1246  		// attempt.
  1247  		mp.preemptGen.Add(1)
  1248  		return
  1249  	}
  1250  
  1251  	// Acquire our own handle to mp's thread.
  1252  	lock(&mp.threadLock)
  1253  	if mp.thread == 0 {
  1254  		// The M hasn't been minit'd yet (or was just unminit'd).
  1255  		unlock(&mp.threadLock)
  1256  		atomic.Store(&mp.preemptExtLock, 0)
  1257  		mp.preemptGen.Add(1)
  1258  		return
  1259  	}
  1260  	var thread uintptr
  1261  	if stdcall7(_DuplicateHandle, currentProcess, mp.thread, currentProcess, uintptr(unsafe.Pointer(&thread)), 0, 0, _DUPLICATE_SAME_ACCESS) == 0 {
  1262  		print("runtime.preemptM: duplicatehandle failed; errno=", getlasterror(), "\n")
  1263  		throw("runtime.preemptM: duplicatehandle failed")
  1264  	}
  1265  	unlock(&mp.threadLock)
  1266  
  1267  	// Prepare thread context buffer. This must be aligned to 16 bytes.
  1268  	var c *context
  1269  	var cbuf [unsafe.Sizeof(*c) + 15]byte
  1270  	c = (*context)(unsafe.Pointer((uintptr(unsafe.Pointer(&cbuf[15]))) &^ 15))
  1271  	c.contextflags = _CONTEXT_CONTROL
  1272  
  1273  	// Serialize thread suspension. SuspendThread is asynchronous,
  1274  	// so it's otherwise possible for two threads to suspend each
  1275  	// other and deadlock. We must hold this lock until after
  1276  	// GetThreadContext, since that blocks until the thread is
  1277  	// actually suspended.
  1278  	lock(&suspendLock)
  1279  
  1280  	// Suspend the thread.
  1281  	if int32(stdcall1(_SuspendThread, thread)) == -1 {
  1282  		unlock(&suspendLock)
  1283  		stdcall1(_CloseHandle, thread)
  1284  		atomic.Store(&mp.preemptExtLock, 0)
  1285  		// The thread no longer exists. This shouldn't be
  1286  		// possible, but just acknowledge the request.
  1287  		mp.preemptGen.Add(1)
  1288  		return
  1289  	}
  1290  
  1291  	// We have to be very careful between this point and once
  1292  	// we've shown mp is at an async safe-point. This is like a
  1293  	// signal handler in the sense that mp could have been doing
  1294  	// anything when we stopped it, including holding arbitrary
  1295  	// locks.
  1296  
  1297  	// We have to get the thread context before inspecting the M
  1298  	// because SuspendThread only requests a suspend.
  1299  	// GetThreadContext actually blocks until it's suspended.
  1300  	stdcall2(_GetThreadContext, thread, uintptr(unsafe.Pointer(c)))
  1301  
  1302  	unlock(&suspendLock)
  1303  
  1304  	// Does it want a preemption and is it safe to preempt?
  1305  	gp := gFromSP(mp, c.sp())
  1306  	if gp != nil && wantAsyncPreempt(gp) {
  1307  		if ok, resumePC := isAsyncSafePoint(gp, c.ip(), c.sp(), c.lr()); ok {
  1308  			// Inject call to asyncPreempt
  1309  			targetPC := abi.FuncPCABI0(asyncPreempt)
  1310  			c.pushCall(targetPC, resumePC)
  1311  			stdcall2(_SetThreadContext, thread, uintptr(unsafe.Pointer(c)))
  1312  		}
  1313  	}
  1314  
  1315  	atomic.Store(&mp.preemptExtLock, 0)
  1316  
  1317  	// Acknowledge the preemption.
  1318  	mp.preemptGen.Add(1)
  1319  
  1320  	stdcall1(_ResumeThread, thread)
  1321  	stdcall1(_CloseHandle, thread)
  1322  }
  1323  
  1324  // osPreemptExtEnter is called before entering external code that may
  1325  // call ExitProcess.
  1326  //
  1327  // This must be nosplit because it may be called from a syscall with
  1328  // untyped stack slots, so the stack must not be grown or scanned.
  1329  //
  1330  //go:nosplit
  1331  func osPreemptExtEnter(mp *m) {
  1332  	for !atomic.Cas(&mp.preemptExtLock, 0, 1) {
  1333  		// An asynchronous preemption is in progress. It's not
  1334  		// safe to enter external code because it may call
  1335  		// ExitProcess and deadlock with SuspendThread.
  1336  		// Ideally we would do the preemption ourselves, but
  1337  		// can't since there may be untyped syscall arguments
  1338  		// on the stack. Instead, just wait and encourage the
  1339  		// SuspendThread APC to run. The preemption should be
  1340  		// done shortly.
  1341  		osyield()
  1342  	}
  1343  	// Asynchronous preemption is now blocked.
  1344  }
  1345  
  1346  // osPreemptExtExit is called after returning from external code that
  1347  // may call ExitProcess.
  1348  //
  1349  // See osPreemptExtEnter for why this is nosplit.
  1350  //
  1351  //go:nosplit
  1352  func osPreemptExtExit(mp *m) {
  1353  	atomic.Store(&mp.preemptExtLock, 0)
  1354  }
  1355  

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