Source file src/runtime/syscall_windows.go

     1	// Copyright 2014 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		"unsafe"
     9	)
    10	
    11	type callbacks struct {
    12		lock mutex
    13		ctxt [cb_max]*wincallbackcontext
    14		n    int
    15	}
    16	
    17	func (c *wincallbackcontext) isCleanstack() bool {
    18		return c.cleanstack
    19	}
    20	
    21	func (c *wincallbackcontext) setCleanstack(cleanstack bool) {
    22		c.cleanstack = cleanstack
    23	}
    24	
    25	var (
    26		cbs     callbacks
    27		cbctxts **wincallbackcontext = &cbs.ctxt[0] // to simplify access to cbs.ctxt in sys_windows_*.s
    28	)
    29	
    30	func callbackasm()
    31	
    32	// callbackasmAddr returns address of runtime.callbackasm
    33	// function adjusted by i.
    34	// On x86 and amd64, runtime.callbackasm is a series of CALL instructions,
    35	// and we want callback to arrive at
    36	// correspondent call instruction instead of start of
    37	// runtime.callbackasm.
    38	// On ARM, runtime.callbackasm is a series of mov and branch instructions.
    39	// R12 is loaded with the callback index. Each entry is two instructions,
    40	// hence 8 bytes.
    41	func callbackasmAddr(i int) uintptr {
    42		var entrySize int
    43		switch GOARCH {
    44		default:
    45			panic("unsupported architecture")
    46		case "386", "amd64":
    47			entrySize = 5
    48		case "arm":
    49			// On ARM, each entry is a MOV instruction
    50			// followed by a branch instruction
    51			entrySize = 8
    52		}
    53		return funcPC(callbackasm) + uintptr(i*entrySize)
    54	}
    55	
    56	//go:linkname compileCallback syscall.compileCallback
    57	func compileCallback(fn eface, cleanstack bool) (code uintptr) {
    58		if fn._type == nil || (fn._type.kind&kindMask) != kindFunc {
    59			panic("compileCallback: expected function with one uintptr-sized result")
    60		}
    61		ft := (*functype)(unsafe.Pointer(fn._type))
    62		if len(ft.out()) != 1 {
    63			panic("compileCallback: expected function with one uintptr-sized result")
    64		}
    65		uintptrSize := unsafe.Sizeof(uintptr(0))
    66		if ft.out()[0].size != uintptrSize {
    67			panic("compileCallback: expected function with one uintptr-sized result")
    68		}
    69		argsize := uintptr(0)
    70		for _, t := range ft.in() {
    71			if t.size > uintptrSize {
    72				panic("compileCallback: argument size is larger than uintptr")
    73			}
    74			argsize += uintptrSize
    75		}
    76	
    77		lock(&cbs.lock) // We don't unlock this in a defer because this is used from the system stack.
    78	
    79		n := cbs.n
    80		for i := 0; i < n; i++ {
    81			if cbs.ctxt[i].gobody == fn.data && cbs.ctxt[i].isCleanstack() == cleanstack {
    82				r := callbackasmAddr(i)
    83				unlock(&cbs.lock)
    84				return r
    85			}
    86		}
    87		if n >= cb_max {
    88			unlock(&cbs.lock)
    89			throw("too many callback functions")
    90		}
    91	
    92		c := new(wincallbackcontext)
    93		c.gobody = fn.data
    94		c.argsize = argsize
    95		c.setCleanstack(cleanstack)
    96		if cleanstack && argsize != 0 {
    97			c.restorestack = argsize
    98		} else {
    99			c.restorestack = 0
   100		}
   101		cbs.ctxt[n] = c
   102		cbs.n++
   103	
   104		r := callbackasmAddr(n)
   105		unlock(&cbs.lock)
   106		return r
   107	}
   108	
   109	const _LOAD_LIBRARY_SEARCH_SYSTEM32 = 0x00000800
   110	
   111	// When available, this function will use LoadLibraryEx with the filename
   112	// parameter and the important SEARCH_SYSTEM32 argument. But on systems that
   113	// do not have that option, absoluteFilepath should contain a fallback
   114	// to the full path inside of system32 for use with vanilla LoadLibrary.
   115	//go:linkname syscall_loadsystemlibrary syscall.loadsystemlibrary
   116	//go:nosplit
   117	func syscall_loadsystemlibrary(filename *uint16, absoluteFilepath *uint16) (handle, err uintptr) {
   118		lockOSThread()
   119		c := &getg().m.syscall
   120	
   121		if useLoadLibraryEx {
   122			c.fn = getLoadLibraryEx()
   123			c.n = 3
   124			args := struct {
   125				lpFileName *uint16
   126				hFile      uintptr // always 0
   127				flags      uint32
   128			}{filename, 0, _LOAD_LIBRARY_SEARCH_SYSTEM32}
   129			c.args = uintptr(noescape(unsafe.Pointer(&args)))
   130		} else {
   131			c.fn = getLoadLibrary()
   132			c.n = 1
   133			c.args = uintptr(noescape(unsafe.Pointer(&absoluteFilepath)))
   134		}
   135	
   136		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   137		handle = c.r1
   138		if handle == 0 {
   139			err = c.err
   140		}
   141		unlockOSThread() // not defer'd after the lockOSThread above to save stack frame size.
   142		return
   143	}
   144	
   145	//go:linkname syscall_loadlibrary syscall.loadlibrary
   146	//go:nosplit
   147	func syscall_loadlibrary(filename *uint16) (handle, err uintptr) {
   148		lockOSThread()
   149		defer unlockOSThread()
   150		c := &getg().m.syscall
   151		c.fn = getLoadLibrary()
   152		c.n = 1
   153		c.args = uintptr(noescape(unsafe.Pointer(&filename)))
   154		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   155		handle = c.r1
   156		if handle == 0 {
   157			err = c.err
   158		}
   159		return
   160	}
   161	
   162	//go:linkname syscall_getprocaddress syscall.getprocaddress
   163	//go:nosplit
   164	func syscall_getprocaddress(handle uintptr, procname *byte) (outhandle, err uintptr) {
   165		lockOSThread()
   166		defer unlockOSThread()
   167		c := &getg().m.syscall
   168		c.fn = getGetProcAddress()
   169		c.n = 2
   170		c.args = uintptr(noescape(unsafe.Pointer(&handle)))
   171		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   172		outhandle = c.r1
   173		if outhandle == 0 {
   174			err = c.err
   175		}
   176		return
   177	}
   178	
   179	//go:linkname syscall_Syscall syscall.Syscall
   180	//go:nosplit
   181	func syscall_Syscall(fn, nargs, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
   182		lockOSThread()
   183		defer unlockOSThread()
   184		c := &getg().m.syscall
   185		c.fn = fn
   186		c.n = nargs
   187		c.args = uintptr(noescape(unsafe.Pointer(&a1)))
   188		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   189		return c.r1, c.r2, c.err
   190	}
   191	
   192	//go:linkname syscall_Syscall6 syscall.Syscall6
   193	//go:nosplit
   194	func syscall_Syscall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
   195		lockOSThread()
   196		defer unlockOSThread()
   197		c := &getg().m.syscall
   198		c.fn = fn
   199		c.n = nargs
   200		c.args = uintptr(noescape(unsafe.Pointer(&a1)))
   201		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   202		return c.r1, c.r2, c.err
   203	}
   204	
   205	//go:linkname syscall_Syscall9 syscall.Syscall9
   206	//go:nosplit
   207	func syscall_Syscall9(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2, err uintptr) {
   208		lockOSThread()
   209		defer unlockOSThread()
   210		c := &getg().m.syscall
   211		c.fn = fn
   212		c.n = nargs
   213		c.args = uintptr(noescape(unsafe.Pointer(&a1)))
   214		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   215		return c.r1, c.r2, c.err
   216	}
   217	
   218	//go:linkname syscall_Syscall12 syscall.Syscall12
   219	//go:nosplit
   220	func syscall_Syscall12(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12 uintptr) (r1, r2, err uintptr) {
   221		lockOSThread()
   222		defer unlockOSThread()
   223		c := &getg().m.syscall
   224		c.fn = fn
   225		c.n = nargs
   226		c.args = uintptr(noescape(unsafe.Pointer(&a1)))
   227		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   228		return c.r1, c.r2, c.err
   229	}
   230	
   231	//go:linkname syscall_Syscall15 syscall.Syscall15
   232	//go:nosplit
   233	func syscall_Syscall15(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 uintptr) (r1, r2, err uintptr) {
   234		lockOSThread()
   235		defer unlockOSThread()
   236		c := &getg().m.syscall
   237		c.fn = fn
   238		c.n = nargs
   239		c.args = uintptr(noescape(unsafe.Pointer(&a1)))
   240		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   241		return c.r1, c.r2, c.err
   242	}
   243	
   244	//go:linkname syscall_Syscall18 syscall.Syscall18
   245	//go:nosplit
   246	func syscall_Syscall18(fn, nargs, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16, a17, a18 uintptr) (r1, r2, err uintptr) {
   247		lockOSThread()
   248		defer unlockOSThread()
   249		c := &getg().m.syscall
   250		c.fn = fn
   251		c.n = nargs
   252		c.args = uintptr(noescape(unsafe.Pointer(&a1)))
   253		cgocall(asmstdcallAddr, unsafe.Pointer(c))
   254		return c.r1, c.r2, c.err
   255	}
   256	

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