Source file src/runtime/cgocall.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  // Cgo call and callback support.
     6  //
     7  // To call into the C function f from Go, the cgo-generated code calls
     8  // runtime.cgocall(_cgo_Cfunc_f, frame), where _cgo_Cfunc_f is a
     9  // gcc-compiled function written by cgo.
    10  //
    11  // runtime.cgocall (below) calls entersyscall so as not to block
    12  // other goroutines or the garbage collector, and then calls
    13  // runtime.asmcgocall(_cgo_Cfunc_f, frame).
    14  //
    15  // runtime.asmcgocall (in asm_$GOARCH.s) switches to the m->g0 stack
    16  // (assumed to be an operating system-allocated stack, so safe to run
    17  // gcc-compiled code on) and calls _cgo_Cfunc_f(frame).
    18  //
    19  // _cgo_Cfunc_f invokes the actual C function f with arguments
    20  // taken from the frame structure, records the results in the frame,
    21  // and returns to runtime.asmcgocall.
    22  //
    23  // After it regains control, runtime.asmcgocall switches back to the
    24  // original g (m->curg)'s stack and returns to runtime.cgocall.
    25  //
    26  // After it regains control, runtime.cgocall calls exitsyscall, which blocks
    27  // until this m can run Go code without violating the $GOMAXPROCS limit,
    28  // and then unlocks g from m.
    29  //
    30  // The above description skipped over the possibility of the gcc-compiled
    31  // function f calling back into Go. If that happens, we continue down
    32  // the rabbit hole during the execution of f.
    33  //
    34  // To make it possible for gcc-compiled C code to call a Go function p.GoF,
    35  // cgo writes a gcc-compiled function named GoF (not p.GoF, since gcc doesn't
    36  // know about packages).  The gcc-compiled C function f calls GoF.
    37  //
    38  // GoF initializes "frame", a structure containing all of its
    39  // arguments and slots for p.GoF's results. It calls
    40  // crosscall2(_cgoexp_GoF, frame, framesize, ctxt) using the gcc ABI.
    41  //
    42  // crosscall2 (in cgo/asm_$GOARCH.s) is a four-argument adapter from
    43  // the gcc function call ABI to the gc function call ABI. At this
    44  // point we're in the Go runtime, but we're still running on m.g0's
    45  // stack and outside the $GOMAXPROCS limit. crosscall2 calls
    46  // runtime.cgocallback(_cgoexp_GoF, frame, ctxt) using the gc ABI.
    47  // (crosscall2's framesize argument is no longer used, but there's one
    48  // case where SWIG calls crosscall2 directly and expects to pass this
    49  // argument. See _cgo_panic.)
    50  //
    51  // runtime.cgocallback (in asm_$GOARCH.s) switches from m.g0's stack
    52  // to the original g (m.curg)'s stack, on which it calls
    53  // runtime.cgocallbackg(_cgoexp_GoF, frame, ctxt). As part of the
    54  // stack switch, runtime.cgocallback saves the current SP as
    55  // m.g0.sched.sp, so that any use of m.g0's stack during the execution
    56  // of the callback will be done below the existing stack frames.
    57  // Before overwriting m.g0.sched.sp, it pushes the old value on the
    58  // m.g0 stack, so that it can be restored later.
    59  //
    60  // runtime.cgocallbackg (below) is now running on a real goroutine
    61  // stack (not an m.g0 stack).  First it calls runtime.exitsyscall, which will
    62  // block until the $GOMAXPROCS limit allows running this goroutine.
    63  // Once exitsyscall has returned, it is safe to do things like call the memory
    64  // allocator or invoke the Go callback function.  runtime.cgocallbackg
    65  // first defers a function to unwind m.g0.sched.sp, so that if p.GoF
    66  // panics, m.g0.sched.sp will be restored to its old value: the m.g0 stack
    67  // and the m.curg stack will be unwound in lock step.
    68  // Then it calls _cgoexp_GoF(frame).
    69  //
    70  // _cgoexp_GoF, which was generated by cmd/cgo, unpacks the arguments
    71  // from frame, calls p.GoF, writes the results back to frame, and
    72  // returns. Now we start unwinding this whole process.
    73  //
    74  // runtime.cgocallbackg pops but does not execute the deferred
    75  // function to unwind m.g0.sched.sp, calls runtime.entersyscall, and
    76  // returns to runtime.cgocallback.
    77  //
    78  // After it regains control, runtime.cgocallback switches back to
    79  // m.g0's stack (the pointer is still in m.g0.sched.sp), restores the old
    80  // m.g0.sched.sp value from the stack, and returns to crosscall2.
    81  //
    82  // crosscall2 restores the callee-save registers for gcc and returns
    83  // to GoF, which unpacks any result values and returns to f.
    84  
    85  package runtime
    86  
    87  import (
    88  	"internal/goarch"
    89  	"runtime/internal/sys"
    90  	"unsafe"
    91  )
    92  
    93  // Addresses collected in a cgo backtrace when crashing.
    94  // Length must match arg.Max in x_cgo_callers in runtime/cgo/gcc_traceback.c.
    95  type cgoCallers [32]uintptr
    96  
    97  // argset matches runtime/cgo/linux_syscall.c:argset_t
    98  type argset struct {
    99  	args   unsafe.Pointer
   100  	retval uintptr
   101  }
   102  
   103  // wrapper for syscall package to call cgocall for libc (cgo) calls.
   104  //
   105  //go:linkname syscall_cgocaller syscall.cgocaller
   106  //go:nosplit
   107  //go:uintptrescapes
   108  func syscall_cgocaller(fn unsafe.Pointer, args ...uintptr) uintptr {
   109  	as := argset{args: unsafe.Pointer(&args[0])}
   110  	cgocall(fn, unsafe.Pointer(&as))
   111  	return as.retval
   112  }
   113  
   114  var ncgocall uint64 // number of cgo calls in total for dead m
   115  
   116  // Call from Go to C.
   117  //
   118  // This must be nosplit because it's used for syscalls on some
   119  // platforms. Syscalls may have untyped arguments on the stack, so
   120  // it's not safe to grow or scan the stack.
   121  //
   122  //go:nosplit
   123  func cgocall(fn, arg unsafe.Pointer) int32 {
   124  	if !iscgo && GOOS != "solaris" && GOOS != "illumos" && GOOS != "windows" {
   125  		throw("cgocall unavailable")
   126  	}
   127  
   128  	if fn == nil {
   129  		throw("cgocall nil")
   130  	}
   131  
   132  	if raceenabled {
   133  		racereleasemerge(unsafe.Pointer(&racecgosync))
   134  	}
   135  
   136  	mp := getg().m
   137  	mp.ncgocall++
   138  	mp.ncgo++
   139  
   140  	// Reset traceback.
   141  	mp.cgoCallers[0] = 0
   142  
   143  	// Announce we are entering a system call
   144  	// so that the scheduler knows to create another
   145  	// M to run goroutines while we are in the
   146  	// foreign code.
   147  	//
   148  	// The call to asmcgocall is guaranteed not to
   149  	// grow the stack and does not allocate memory,
   150  	// so it is safe to call while "in a system call", outside
   151  	// the $GOMAXPROCS accounting.
   152  	//
   153  	// fn may call back into Go code, in which case we'll exit the
   154  	// "system call", run the Go code (which may grow the stack),
   155  	// and then re-enter the "system call" reusing the PC and SP
   156  	// saved by entersyscall here.
   157  	entersyscall()
   158  
   159  	// Tell asynchronous preemption that we're entering external
   160  	// code. We do this after entersyscall because this may block
   161  	// and cause an async preemption to fail, but at this point a
   162  	// sync preemption will succeed (though this is not a matter
   163  	// of correctness).
   164  	osPreemptExtEnter(mp)
   165  
   166  	mp.incgo = true
   167  	errno := asmcgocall(fn, arg)
   168  
   169  	// Update accounting before exitsyscall because exitsyscall may
   170  	// reschedule us on to a different M.
   171  	mp.incgo = false
   172  	mp.ncgo--
   173  
   174  	osPreemptExtExit(mp)
   175  
   176  	exitsyscall()
   177  
   178  	// Note that raceacquire must be called only after exitsyscall has
   179  	// wired this M to a P.
   180  	if raceenabled {
   181  		raceacquire(unsafe.Pointer(&racecgosync))
   182  	}
   183  
   184  	// From the garbage collector's perspective, time can move
   185  	// backwards in the sequence above. If there's a callback into
   186  	// Go code, GC will see this function at the call to
   187  	// asmcgocall. When the Go call later returns to C, the
   188  	// syscall PC/SP is rolled back and the GC sees this function
   189  	// back at the call to entersyscall. Normally, fn and arg
   190  	// would be live at entersyscall and dead at asmcgocall, so if
   191  	// time moved backwards, GC would see these arguments as dead
   192  	// and then live. Prevent these undead arguments from crashing
   193  	// GC by forcing them to stay live across this time warp.
   194  	KeepAlive(fn)
   195  	KeepAlive(arg)
   196  	KeepAlive(mp)
   197  
   198  	return errno
   199  }
   200  
   201  // Call from C back to Go. fn must point to an ABIInternal Go entry-point.
   202  //
   203  //go:nosplit
   204  func cgocallbackg(fn, frame unsafe.Pointer, ctxt uintptr) {
   205  	gp := getg()
   206  	if gp != gp.m.curg {
   207  		println("runtime: bad g in cgocallback")
   208  		exit(2)
   209  	}
   210  
   211  	// The call from C is on gp.m's g0 stack, so we must ensure
   212  	// that we stay on that M. We have to do this before calling
   213  	// exitsyscall, since it would otherwise be free to move us to
   214  	// a different M. The call to unlockOSThread is in unwindm.
   215  	lockOSThread()
   216  
   217  	checkm := gp.m
   218  
   219  	// Save current syscall parameters, so m.syscall can be
   220  	// used again if callback decide to make syscall.
   221  	syscall := gp.m.syscall
   222  
   223  	// entersyscall saves the caller's SP to allow the GC to trace the Go
   224  	// stack. However, since we're returning to an earlier stack frame and
   225  	// need to pair with the entersyscall() call made by cgocall, we must
   226  	// save syscall* and let reentersyscall restore them.
   227  	savedsp := unsafe.Pointer(gp.syscallsp)
   228  	savedpc := gp.syscallpc
   229  	exitsyscall() // coming out of cgo call
   230  	gp.m.incgo = false
   231  
   232  	osPreemptExtExit(gp.m)
   233  
   234  	cgocallbackg1(fn, frame, ctxt) // will call unlockOSThread
   235  
   236  	// At this point unlockOSThread has been called.
   237  	// The following code must not change to a different m.
   238  	// This is enforced by checking incgo in the schedule function.
   239  
   240  	gp.m.incgo = true
   241  
   242  	if gp.m != checkm {
   243  		throw("m changed unexpectedly in cgocallbackg")
   244  	}
   245  
   246  	osPreemptExtEnter(gp.m)
   247  
   248  	// going back to cgo call
   249  	reentersyscall(savedpc, uintptr(savedsp))
   250  
   251  	gp.m.syscall = syscall
   252  }
   253  
   254  func cgocallbackg1(fn, frame unsafe.Pointer, ctxt uintptr) {
   255  	gp := getg()
   256  
   257  	// When we return, undo the call to lockOSThread in cgocallbackg.
   258  	// We must still stay on the same m.
   259  	defer unlockOSThread()
   260  
   261  	if gp.m.needextram || extraMWaiters.Load() > 0 {
   262  		gp.m.needextram = false
   263  		systemstack(newextram)
   264  	}
   265  
   266  	if ctxt != 0 {
   267  		s := append(gp.cgoCtxt, ctxt)
   268  
   269  		// Now we need to set gp.cgoCtxt = s, but we could get
   270  		// a SIGPROF signal while manipulating the slice, and
   271  		// the SIGPROF handler could pick up gp.cgoCtxt while
   272  		// tracing up the stack.  We need to ensure that the
   273  		// handler always sees a valid slice, so set the
   274  		// values in an order such that it always does.
   275  		p := (*slice)(unsafe.Pointer(&gp.cgoCtxt))
   276  		atomicstorep(unsafe.Pointer(&p.array), unsafe.Pointer(&s[0]))
   277  		p.cap = cap(s)
   278  		p.len = len(s)
   279  
   280  		defer func(gp *g) {
   281  			// Decrease the length of the slice by one, safely.
   282  			p := (*slice)(unsafe.Pointer(&gp.cgoCtxt))
   283  			p.len--
   284  		}(gp)
   285  	}
   286  
   287  	if gp.m.ncgo == 0 {
   288  		// The C call to Go came from a thread not currently running
   289  		// any Go. In the case of -buildmode=c-archive or c-shared,
   290  		// this call may be coming in before package initialization
   291  		// is complete. Wait until it is.
   292  		<-main_init_done
   293  	}
   294  
   295  	// Check whether the profiler needs to be turned on or off; this route to
   296  	// run Go code does not use runtime.execute, so bypasses the check there.
   297  	hz := sched.profilehz
   298  	if gp.m.profilehz != hz {
   299  		setThreadCPUProfiler(hz)
   300  	}
   301  
   302  	// Add entry to defer stack in case of panic.
   303  	restore := true
   304  	defer unwindm(&restore)
   305  
   306  	if raceenabled {
   307  		raceacquire(unsafe.Pointer(&racecgosync))
   308  	}
   309  
   310  	// Invoke callback. This function is generated by cmd/cgo and
   311  	// will unpack the argument frame and call the Go function.
   312  	var cb func(frame unsafe.Pointer)
   313  	cbFV := funcval{uintptr(fn)}
   314  	*(*unsafe.Pointer)(unsafe.Pointer(&cb)) = noescape(unsafe.Pointer(&cbFV))
   315  	cb(frame)
   316  
   317  	if raceenabled {
   318  		racereleasemerge(unsafe.Pointer(&racecgosync))
   319  	}
   320  
   321  	// Do not unwind m->g0->sched.sp.
   322  	// Our caller, cgocallback, will do that.
   323  	restore = false
   324  }
   325  
   326  func unwindm(restore *bool) {
   327  	if *restore {
   328  		// Restore sp saved by cgocallback during
   329  		// unwind of g's stack (see comment at top of file).
   330  		mp := acquirem()
   331  		sched := &mp.g0.sched
   332  		sched.sp = *(*uintptr)(unsafe.Pointer(sched.sp + alignUp(sys.MinFrameSize, sys.StackAlign)))
   333  
   334  		// Do the accounting that cgocall will not have a chance to do
   335  		// during an unwind.
   336  		//
   337  		// In the case where a Go call originates from C, ncgo is 0
   338  		// and there is no matching cgocall to end.
   339  		if mp.ncgo > 0 {
   340  			mp.incgo = false
   341  			mp.ncgo--
   342  			osPreemptExtExit(mp)
   343  		}
   344  
   345  		releasem(mp)
   346  	}
   347  }
   348  
   349  // called from assembly.
   350  func badcgocallback() {
   351  	throw("misaligned stack in cgocallback")
   352  }
   353  
   354  // called from (incomplete) assembly.
   355  func cgounimpl() {
   356  	throw("cgo not implemented")
   357  }
   358  
   359  var racecgosync uint64 // represents possible synchronization in C code
   360  
   361  // Pointer checking for cgo code.
   362  
   363  // We want to detect all cases where a program that does not use
   364  // unsafe makes a cgo call passing a Go pointer to memory that
   365  // contains a Go pointer. Here a Go pointer is defined as a pointer
   366  // to memory allocated by the Go runtime. Programs that use unsafe
   367  // can evade this restriction easily, so we don't try to catch them.
   368  // The cgo program will rewrite all possibly bad pointer arguments to
   369  // call cgoCheckPointer, where we can catch cases of a Go pointer
   370  // pointing to a Go pointer.
   371  
   372  // Complicating matters, taking the address of a slice or array
   373  // element permits the C program to access all elements of the slice
   374  // or array. In that case we will see a pointer to a single element,
   375  // but we need to check the entire data structure.
   376  
   377  // The cgoCheckPointer call takes additional arguments indicating that
   378  // it was called on an address expression. An additional argument of
   379  // true means that it only needs to check a single element. An
   380  // additional argument of a slice or array means that it needs to
   381  // check the entire slice/array, but nothing else. Otherwise, the
   382  // pointer could be anything, and we check the entire heap object,
   383  // which is conservative but safe.
   384  
   385  // When and if we implement a moving garbage collector,
   386  // cgoCheckPointer will pin the pointer for the duration of the cgo
   387  // call.  (This is necessary but not sufficient; the cgo program will
   388  // also have to change to pin Go pointers that cannot point to Go
   389  // pointers.)
   390  
   391  // cgoCheckPointer checks if the argument contains a Go pointer that
   392  // points to a Go pointer, and panics if it does.
   393  func cgoCheckPointer(ptr any, arg any) {
   394  	if debug.cgocheck == 0 {
   395  		return
   396  	}
   397  
   398  	ep := efaceOf(&ptr)
   399  	t := ep._type
   400  
   401  	top := true
   402  	if arg != nil && (t.kind&kindMask == kindPtr || t.kind&kindMask == kindUnsafePointer) {
   403  		p := ep.data
   404  		if t.kind&kindDirectIface == 0 {
   405  			p = *(*unsafe.Pointer)(p)
   406  		}
   407  		if p == nil || !cgoIsGoPointer(p) {
   408  			return
   409  		}
   410  		aep := efaceOf(&arg)
   411  		switch aep._type.kind & kindMask {
   412  		case kindBool:
   413  			if t.kind&kindMask == kindUnsafePointer {
   414  				// We don't know the type of the element.
   415  				break
   416  			}
   417  			pt := (*ptrtype)(unsafe.Pointer(t))
   418  			cgoCheckArg(pt.elem, p, true, false, cgoCheckPointerFail)
   419  			return
   420  		case kindSlice:
   421  			// Check the slice rather than the pointer.
   422  			ep = aep
   423  			t = ep._type
   424  		case kindArray:
   425  			// Check the array rather than the pointer.
   426  			// Pass top as false since we have a pointer
   427  			// to the array.
   428  			ep = aep
   429  			t = ep._type
   430  			top = false
   431  		default:
   432  			throw("can't happen")
   433  		}
   434  	}
   435  
   436  	cgoCheckArg(t, ep.data, t.kind&kindDirectIface == 0, top, cgoCheckPointerFail)
   437  }
   438  
   439  const cgoCheckPointerFail = "cgo argument has Go pointer to Go pointer"
   440  const cgoResultFail = "cgo result has Go pointer"
   441  
   442  // cgoCheckArg is the real work of cgoCheckPointer. The argument p
   443  // is either a pointer to the value (of type t), or the value itself,
   444  // depending on indir. The top parameter is whether we are at the top
   445  // level, where Go pointers are allowed.
   446  func cgoCheckArg(t *_type, p unsafe.Pointer, indir, top bool, msg string) {
   447  	if t.ptrdata == 0 || p == nil {
   448  		// If the type has no pointers there is nothing to do.
   449  		return
   450  	}
   451  
   452  	switch t.kind & kindMask {
   453  	default:
   454  		throw("can't happen")
   455  	case kindArray:
   456  		at := (*arraytype)(unsafe.Pointer(t))
   457  		if !indir {
   458  			if at.len != 1 {
   459  				throw("can't happen")
   460  			}
   461  			cgoCheckArg(at.elem, p, at.elem.kind&kindDirectIface == 0, top, msg)
   462  			return
   463  		}
   464  		for i := uintptr(0); i < at.len; i++ {
   465  			cgoCheckArg(at.elem, p, true, top, msg)
   466  			p = add(p, at.elem.size)
   467  		}
   468  	case kindChan, kindMap:
   469  		// These types contain internal pointers that will
   470  		// always be allocated in the Go heap. It's never OK
   471  		// to pass them to C.
   472  		panic(errorString(msg))
   473  	case kindFunc:
   474  		if indir {
   475  			p = *(*unsafe.Pointer)(p)
   476  		}
   477  		if !cgoIsGoPointer(p) {
   478  			return
   479  		}
   480  		panic(errorString(msg))
   481  	case kindInterface:
   482  		it := *(**_type)(p)
   483  		if it == nil {
   484  			return
   485  		}
   486  		// A type known at compile time is OK since it's
   487  		// constant. A type not known at compile time will be
   488  		// in the heap and will not be OK.
   489  		if inheap(uintptr(unsafe.Pointer(it))) {
   490  			panic(errorString(msg))
   491  		}
   492  		p = *(*unsafe.Pointer)(add(p, goarch.PtrSize))
   493  		if !cgoIsGoPointer(p) {
   494  			return
   495  		}
   496  		if !top {
   497  			panic(errorString(msg))
   498  		}
   499  		cgoCheckArg(it, p, it.kind&kindDirectIface == 0, false, msg)
   500  	case kindSlice:
   501  		st := (*slicetype)(unsafe.Pointer(t))
   502  		s := (*slice)(p)
   503  		p = s.array
   504  		if p == nil || !cgoIsGoPointer(p) {
   505  			return
   506  		}
   507  		if !top {
   508  			panic(errorString(msg))
   509  		}
   510  		if st.elem.ptrdata == 0 {
   511  			return
   512  		}
   513  		for i := 0; i < s.cap; i++ {
   514  			cgoCheckArg(st.elem, p, true, false, msg)
   515  			p = add(p, st.elem.size)
   516  		}
   517  	case kindString:
   518  		ss := (*stringStruct)(p)
   519  		if !cgoIsGoPointer(ss.str) {
   520  			return
   521  		}
   522  		if !top {
   523  			panic(errorString(msg))
   524  		}
   525  	case kindStruct:
   526  		st := (*structtype)(unsafe.Pointer(t))
   527  		if !indir {
   528  			if len(st.fields) != 1 {
   529  				throw("can't happen")
   530  			}
   531  			cgoCheckArg(st.fields[0].typ, p, st.fields[0].typ.kind&kindDirectIface == 0, top, msg)
   532  			return
   533  		}
   534  		for _, f := range st.fields {
   535  			if f.typ.ptrdata == 0 {
   536  				continue
   537  			}
   538  			cgoCheckArg(f.typ, add(p, f.offset), true, top, msg)
   539  		}
   540  	case kindPtr, kindUnsafePointer:
   541  		if indir {
   542  			p = *(*unsafe.Pointer)(p)
   543  			if p == nil {
   544  				return
   545  			}
   546  		}
   547  
   548  		if !cgoIsGoPointer(p) {
   549  			return
   550  		}
   551  		if !top {
   552  			panic(errorString(msg))
   553  		}
   554  
   555  		cgoCheckUnknownPointer(p, msg)
   556  	}
   557  }
   558  
   559  // cgoCheckUnknownPointer is called for an arbitrary pointer into Go
   560  // memory. It checks whether that Go memory contains any other
   561  // pointer into Go memory. If it does, we panic.
   562  // The return values are unused but useful to see in panic tracebacks.
   563  func cgoCheckUnknownPointer(p unsafe.Pointer, msg string) (base, i uintptr) {
   564  	if inheap(uintptr(p)) {
   565  		b, span, _ := findObject(uintptr(p), 0, 0)
   566  		base = b
   567  		if base == 0 {
   568  			return
   569  		}
   570  		n := span.elemsize
   571  		hbits := heapBitsForAddr(base, n)
   572  		for {
   573  			var addr uintptr
   574  			if hbits, addr = hbits.next(); addr == 0 {
   575  				break
   576  			}
   577  			if cgoIsGoPointer(*(*unsafe.Pointer)(unsafe.Pointer(addr))) {
   578  				panic(errorString(msg))
   579  			}
   580  		}
   581  
   582  		return
   583  	}
   584  
   585  	for _, datap := range activeModules() {
   586  		if cgoInRange(p, datap.data, datap.edata) || cgoInRange(p, datap.bss, datap.ebss) {
   587  			// We have no way to know the size of the object.
   588  			// We have to assume that it might contain a pointer.
   589  			panic(errorString(msg))
   590  		}
   591  		// In the text or noptr sections, we know that the
   592  		// pointer does not point to a Go pointer.
   593  	}
   594  
   595  	return
   596  }
   597  
   598  // cgoIsGoPointer reports whether the pointer is a Go pointer--a
   599  // pointer to Go memory. We only care about Go memory that might
   600  // contain pointers.
   601  //
   602  //go:nosplit
   603  //go:nowritebarrierrec
   604  func cgoIsGoPointer(p unsafe.Pointer) bool {
   605  	if p == nil {
   606  		return false
   607  	}
   608  
   609  	if inHeapOrStack(uintptr(p)) {
   610  		return true
   611  	}
   612  
   613  	for _, datap := range activeModules() {
   614  		if cgoInRange(p, datap.data, datap.edata) || cgoInRange(p, datap.bss, datap.ebss) {
   615  			return true
   616  		}
   617  	}
   618  
   619  	return false
   620  }
   621  
   622  // cgoInRange reports whether p is between start and end.
   623  //
   624  //go:nosplit
   625  //go:nowritebarrierrec
   626  func cgoInRange(p unsafe.Pointer, start, end uintptr) bool {
   627  	return start <= uintptr(p) && uintptr(p) < end
   628  }
   629  
   630  // cgoCheckResult is called to check the result parameter of an
   631  // exported Go function. It panics if the result is or contains a Go
   632  // pointer.
   633  func cgoCheckResult(val any) {
   634  	if debug.cgocheck == 0 {
   635  		return
   636  	}
   637  
   638  	ep := efaceOf(&val)
   639  	t := ep._type
   640  	cgoCheckArg(t, ep.data, t.kind&kindDirectIface == 0, false, cgoResultFail)
   641  }
   642  

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