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/atomic"
    90  	"runtime/internal/sys"
    91  	"unsafe"
    92  )
    93  
    94  // Addresses collected in a cgo backtrace when crashing.
    95  // Length must match arg.Max in x_cgo_callers in runtime/cgo/gcc_traceback.c.
    96  type cgoCallers [32]uintptr
    97  
    98  // argset matches runtime/cgo/linux_syscall.c:argset_t
    99  type argset struct {
   100  	args   unsafe.Pointer
   101  	retval uintptr
   102  }
   103  
   104  // wrapper for syscall package to call cgocall for libc (cgo) calls.
   105  //
   106  //go:linkname syscall_cgocaller syscall.cgocaller
   107  //go:nosplit
   108  //go:uintptrescapes
   109  func syscall_cgocaller(fn unsafe.Pointer, args ...uintptr) uintptr {
   110  	as := argset{args: unsafe.Pointer(&args[0])}
   111  	cgocall(fn, unsafe.Pointer(&as))
   112  	return as.retval
   113  }
   114  
   115  var ncgocall uint64 // number of cgo calls in total for dead m
   116  
   117  // Call from Go to C.
   118  //
   119  // This must be nosplit because it's used for syscalls on some
   120  // platforms. Syscalls may have untyped arguments on the stack, so
   121  // it's not safe to grow or scan the stack.
   122  //
   123  //go:nosplit
   124  func cgocall(fn, arg unsafe.Pointer) int32 {
   125  	if !iscgo && GOOS != "solaris" && GOOS != "illumos" && GOOS != "windows" {
   126  		throw("cgocall unavailable")
   127  	}
   128  
   129  	if fn == nil {
   130  		throw("cgocall nil")
   131  	}
   132  
   133  	if raceenabled {
   134  		racereleasemerge(unsafe.Pointer(&racecgosync))
   135  	}
   136  
   137  	mp := getg().m
   138  	mp.ncgocall++
   139  	mp.ncgo++
   140  
   141  	// Reset traceback.
   142  	mp.cgoCallers[0] = 0
   143  
   144  	// Announce we are entering a system call
   145  	// so that the scheduler knows to create another
   146  	// M to run goroutines while we are in the
   147  	// foreign code.
   148  	//
   149  	// The call to asmcgocall is guaranteed not to
   150  	// grow the stack and does not allocate memory,
   151  	// so it is safe to call while "in a system call", outside
   152  	// the $GOMAXPROCS accounting.
   153  	//
   154  	// fn may call back into Go code, in which case we'll exit the
   155  	// "system call", run the Go code (which may grow the stack),
   156  	// and then re-enter the "system call" reusing the PC and SP
   157  	// saved by entersyscall here.
   158  	entersyscall()
   159  
   160  	// Tell asynchronous preemption that we're entering external
   161  	// code. We do this after entersyscall because this may block
   162  	// and cause an async preemption to fail, but at this point a
   163  	// sync preemption will succeed (though this is not a matter
   164  	// of correctness).
   165  	osPreemptExtEnter(mp)
   166  
   167  	mp.incgo = true
   168  	errno := asmcgocall(fn, arg)
   169  
   170  	// Update accounting before exitsyscall because exitsyscall may
   171  	// reschedule us on to a different M.
   172  	mp.incgo = false
   173  	mp.ncgo--
   174  
   175  	osPreemptExtExit(mp)
   176  
   177  	exitsyscall()
   178  
   179  	// Note that raceacquire must be called only after exitsyscall has
   180  	// wired this M to a P.
   181  	if raceenabled {
   182  		raceacquire(unsafe.Pointer(&racecgosync))
   183  	}
   184  
   185  	// From the garbage collector's perspective, time can move
   186  	// backwards in the sequence above. If there's a callback into
   187  	// Go code, GC will see this function at the call to
   188  	// asmcgocall. When the Go call later returns to C, the
   189  	// syscall PC/SP is rolled back and the GC sees this function
   190  	// back at the call to entersyscall. Normally, fn and arg
   191  	// would be live at entersyscall and dead at asmcgocall, so if
   192  	// time moved backwards, GC would see these arguments as dead
   193  	// and then live. Prevent these undead arguments from crashing
   194  	// GC by forcing them to stay live across this time warp.
   195  	KeepAlive(fn)
   196  	KeepAlive(arg)
   197  	KeepAlive(mp)
   198  
   199  	return errno
   200  }
   201  
   202  // Call from C back to Go. fn must point to an ABIInternal Go entry-point.
   203  //
   204  //go:nosplit
   205  func cgocallbackg(fn, frame unsafe.Pointer, ctxt uintptr) {
   206  	gp := getg()
   207  	if gp != gp.m.curg {
   208  		println("runtime: bad g in cgocallback")
   209  		exit(2)
   210  	}
   211  
   212  	// The call from C is on gp.m's g0 stack, so we must ensure
   213  	// that we stay on that M. We have to do this before calling
   214  	// exitsyscall, since it would otherwise be free to move us to
   215  	// a different M. The call to unlockOSThread is in unwindm.
   216  	lockOSThread()
   217  
   218  	checkm := gp.m
   219  
   220  	// Save current syscall parameters, so m.syscall can be
   221  	// used again if callback decide to make syscall.
   222  	syscall := gp.m.syscall
   223  
   224  	// entersyscall saves the caller's SP to allow the GC to trace the Go
   225  	// stack. However, since we're returning to an earlier stack frame and
   226  	// need to pair with the entersyscall() call made by cgocall, we must
   227  	// save syscall* and let reentersyscall restore them.
   228  	savedsp := unsafe.Pointer(gp.syscallsp)
   229  	savedpc := gp.syscallpc
   230  	exitsyscall() // coming out of cgo call
   231  	gp.m.incgo = false
   232  
   233  	osPreemptExtExit(gp.m)
   234  
   235  	cgocallbackg1(fn, frame, ctxt) // will call unlockOSThread
   236  
   237  	// At this point unlockOSThread has been called.
   238  	// The following code must not change to a different m.
   239  	// This is enforced by checking incgo in the schedule function.
   240  
   241  	gp.m.incgo = true
   242  
   243  	if gp.m != checkm {
   244  		throw("m changed unexpectedly in cgocallbackg")
   245  	}
   246  
   247  	osPreemptExtEnter(gp.m)
   248  
   249  	// going back to cgo call
   250  	reentersyscall(savedpc, uintptr(savedsp))
   251  
   252  	gp.m.syscall = syscall
   253  }
   254  
   255  func cgocallbackg1(fn, frame unsafe.Pointer, ctxt uintptr) {
   256  	gp := getg()
   257  
   258  	// When we return, undo the call to lockOSThread in cgocallbackg.
   259  	// We must still stay on the same m.
   260  	defer unlockOSThread()
   261  
   262  	if gp.m.needextram || atomic.Load(&extraMWaiters) > 0 {
   263  		gp.m.needextram = false
   264  		systemstack(newextram)
   265  	}
   266  
   267  	if ctxt != 0 {
   268  		s := append(gp.cgoCtxt, ctxt)
   269  
   270  		// Now we need to set gp.cgoCtxt = s, but we could get
   271  		// a SIGPROF signal while manipulating the slice, and
   272  		// the SIGPROF handler could pick up gp.cgoCtxt while
   273  		// tracing up the stack.  We need to ensure that the
   274  		// handler always sees a valid slice, so set the
   275  		// values in an order such that it always does.
   276  		p := (*slice)(unsafe.Pointer(&gp.cgoCtxt))
   277  		atomicstorep(unsafe.Pointer(&p.array), unsafe.Pointer(&s[0]))
   278  		p.cap = cap(s)
   279  		p.len = len(s)
   280  
   281  		defer func(gp *g) {
   282  			// Decrease the length of the slice by one, safely.
   283  			p := (*slice)(unsafe.Pointer(&gp.cgoCtxt))
   284  			p.len--
   285  		}(gp)
   286  	}
   287  
   288  	if gp.m.ncgo == 0 {
   289  		// The C call to Go came from a thread not currently running
   290  		// any Go. In the case of -buildmode=c-archive or c-shared,
   291  		// this call may be coming in before package initialization
   292  		// is complete. Wait until it is.
   293  		<-main_init_done
   294  	}
   295  
   296  	// Check whether the profiler needs to be turned on or off; this route to
   297  	// run Go code does not use runtime.execute, so bypasses the check there.
   298  	hz := sched.profilehz
   299  	if gp.m.profilehz != hz {
   300  		setThreadCPUProfiler(hz)
   301  	}
   302  
   303  	// Add entry to defer stack in case of panic.
   304  	restore := true
   305  	defer unwindm(&restore)
   306  
   307  	if raceenabled {
   308  		raceacquire(unsafe.Pointer(&racecgosync))
   309  	}
   310  
   311  	// Invoke callback. This function is generated by cmd/cgo and
   312  	// will unpack the argument frame and call the Go function.
   313  	var cb func(frame unsafe.Pointer)
   314  	cbFV := funcval{uintptr(fn)}
   315  	*(*unsafe.Pointer)(unsafe.Pointer(&cb)) = noescape(unsafe.Pointer(&cbFV))
   316  	cb(frame)
   317  
   318  	if raceenabled {
   319  		racereleasemerge(unsafe.Pointer(&racecgosync))
   320  	}
   321  
   322  	// Do not unwind m->g0->sched.sp.
   323  	// Our caller, cgocallback, will do that.
   324  	restore = false
   325  }
   326  
   327  func unwindm(restore *bool) {
   328  	if *restore {
   329  		// Restore sp saved by cgocallback during
   330  		// unwind of g's stack (see comment at top of file).
   331  		mp := acquirem()
   332  		sched := &mp.g0.sched
   333  		sched.sp = *(*uintptr)(unsafe.Pointer(sched.sp + alignUp(sys.MinFrameSize, sys.StackAlign)))
   334  
   335  		// Do the accounting that cgocall will not have a chance to do
   336  		// during an unwind.
   337  		//
   338  		// In the case where a Go call originates from C, ncgo is 0
   339  		// and there is no matching cgocall to end.
   340  		if mp.ncgo > 0 {
   341  			mp.incgo = false
   342  			mp.ncgo--
   343  			osPreemptExtExit(mp)
   344  		}
   345  
   346  		releasem(mp)
   347  	}
   348  }
   349  
   350  // called from assembly
   351  func badcgocallback() {
   352  	throw("misaligned stack in cgocallback")
   353  }
   354  
   355  // called from (incomplete) assembly
   356  func cgounimpl() {
   357  	throw("cgo not implemented")
   358  }
   359  
   360  var racecgosync uint64 // represents possible synchronization in C code
   361  
   362  // Pointer checking for cgo code.
   363  
   364  // We want to detect all cases where a program that does not use
   365  // unsafe makes a cgo call passing a Go pointer to memory that
   366  // contains a Go pointer. Here a Go pointer is defined as a pointer
   367  // to memory allocated by the Go runtime. Programs that use unsafe
   368  // can evade this restriction easily, so we don't try to catch them.
   369  // The cgo program will rewrite all possibly bad pointer arguments to
   370  // call cgoCheckPointer, where we can catch cases of a Go pointer
   371  // pointing to a Go pointer.
   372  
   373  // Complicating matters, taking the address of a slice or array
   374  // element permits the C program to access all elements of the slice
   375  // or array. In that case we will see a pointer to a single element,
   376  // but we need to check the entire data structure.
   377  
   378  // The cgoCheckPointer call takes additional arguments indicating that
   379  // it was called on an address expression. An additional argument of
   380  // true means that it only needs to check a single element. An
   381  // additional argument of a slice or array means that it needs to
   382  // check the entire slice/array, but nothing else. Otherwise, the
   383  // pointer could be anything, and we check the entire heap object,
   384  // which is conservative but safe.
   385  
   386  // When and if we implement a moving garbage collector,
   387  // cgoCheckPointer will pin the pointer for the duration of the cgo
   388  // call.  (This is necessary but not sufficient; the cgo program will
   389  // also have to change to pin Go pointers that cannot point to Go
   390  // pointers.)
   391  
   392  // cgoCheckPointer checks if the argument contains a Go pointer that
   393  // points to a Go pointer, and panics if it does.
   394  func cgoCheckPointer(ptr any, arg any) {
   395  	if debug.cgocheck == 0 {
   396  		return
   397  	}
   398  
   399  	ep := efaceOf(&ptr)
   400  	t := ep._type
   401  
   402  	top := true
   403  	if arg != nil && (t.kind&kindMask == kindPtr || t.kind&kindMask == kindUnsafePointer) {
   404  		p := ep.data
   405  		if t.kind&kindDirectIface == 0 {
   406  			p = *(*unsafe.Pointer)(p)
   407  		}
   408  		if p == nil || !cgoIsGoPointer(p) {
   409  			return
   410  		}
   411  		aep := efaceOf(&arg)
   412  		switch aep._type.kind & kindMask {
   413  		case kindBool:
   414  			if t.kind&kindMask == kindUnsafePointer {
   415  				// We don't know the type of the element.
   416  				break
   417  			}
   418  			pt := (*ptrtype)(unsafe.Pointer(t))
   419  			cgoCheckArg(pt.elem, p, true, false, cgoCheckPointerFail)
   420  			return
   421  		case kindSlice:
   422  			// Check the slice rather than the pointer.
   423  			ep = aep
   424  			t = ep._type
   425  		case kindArray:
   426  			// Check the array rather than the pointer.
   427  			// Pass top as false since we have a pointer
   428  			// to the array.
   429  			ep = aep
   430  			t = ep._type
   431  			top = false
   432  		default:
   433  			throw("can't happen")
   434  		}
   435  	}
   436  
   437  	cgoCheckArg(t, ep.data, t.kind&kindDirectIface == 0, top, cgoCheckPointerFail)
   438  }
   439  
   440  const cgoCheckPointerFail = "cgo argument has Go pointer to Go pointer"
   441  const cgoResultFail = "cgo result has Go pointer"
   442  
   443  // cgoCheckArg is the real work of cgoCheckPointer. The argument p
   444  // is either a pointer to the value (of type t), or the value itself,
   445  // depending on indir. The top parameter is whether we are at the top
   446  // level, where Go pointers are allowed.
   447  func cgoCheckArg(t *_type, p unsafe.Pointer, indir, top bool, msg string) {
   448  	if t.ptrdata == 0 || p == nil {
   449  		// If the type has no pointers there is nothing to do.
   450  		return
   451  	}
   452  
   453  	switch t.kind & kindMask {
   454  	default:
   455  		throw("can't happen")
   456  	case kindArray:
   457  		at := (*arraytype)(unsafe.Pointer(t))
   458  		if !indir {
   459  			if at.len != 1 {
   460  				throw("can't happen")
   461  			}
   462  			cgoCheckArg(at.elem, p, at.elem.kind&kindDirectIface == 0, top, msg)
   463  			return
   464  		}
   465  		for i := uintptr(0); i < at.len; i++ {
   466  			cgoCheckArg(at.elem, p, true, top, msg)
   467  			p = add(p, at.elem.size)
   468  		}
   469  	case kindChan, kindMap:
   470  		// These types contain internal pointers that will
   471  		// always be allocated in the Go heap. It's never OK
   472  		// to pass them to C.
   473  		panic(errorString(msg))
   474  	case kindFunc:
   475  		if indir {
   476  			p = *(*unsafe.Pointer)(p)
   477  		}
   478  		if !cgoIsGoPointer(p) {
   479  			return
   480  		}
   481  		panic(errorString(msg))
   482  	case kindInterface:
   483  		it := *(**_type)(p)
   484  		if it == nil {
   485  			return
   486  		}
   487  		// A type known at compile time is OK since it's
   488  		// constant. A type not known at compile time will be
   489  		// in the heap and will not be OK.
   490  		if inheap(uintptr(unsafe.Pointer(it))) {
   491  			panic(errorString(msg))
   492  		}
   493  		p = *(*unsafe.Pointer)(add(p, goarch.PtrSize))
   494  		if !cgoIsGoPointer(p) {
   495  			return
   496  		}
   497  		if !top {
   498  			panic(errorString(msg))
   499  		}
   500  		cgoCheckArg(it, p, it.kind&kindDirectIface == 0, false, msg)
   501  	case kindSlice:
   502  		st := (*slicetype)(unsafe.Pointer(t))
   503  		s := (*slice)(p)
   504  		p = s.array
   505  		if p == nil || !cgoIsGoPointer(p) {
   506  			return
   507  		}
   508  		if !top {
   509  			panic(errorString(msg))
   510  		}
   511  		if st.elem.ptrdata == 0 {
   512  			return
   513  		}
   514  		for i := 0; i < s.cap; i++ {
   515  			cgoCheckArg(st.elem, p, true, false, msg)
   516  			p = add(p, st.elem.size)
   517  		}
   518  	case kindString:
   519  		ss := (*stringStruct)(p)
   520  		if !cgoIsGoPointer(ss.str) {
   521  			return
   522  		}
   523  		if !top {
   524  			panic(errorString(msg))
   525  		}
   526  	case kindStruct:
   527  		st := (*structtype)(unsafe.Pointer(t))
   528  		if !indir {
   529  			if len(st.fields) != 1 {
   530  				throw("can't happen")
   531  			}
   532  			cgoCheckArg(st.fields[0].typ, p, st.fields[0].typ.kind&kindDirectIface == 0, top, msg)
   533  			return
   534  		}
   535  		for _, f := range st.fields {
   536  			if f.typ.ptrdata == 0 {
   537  				continue
   538  			}
   539  			cgoCheckArg(f.typ, add(p, f.offset), true, top, msg)
   540  		}
   541  	case kindPtr, kindUnsafePointer:
   542  		if indir {
   543  			p = *(*unsafe.Pointer)(p)
   544  			if p == nil {
   545  				return
   546  			}
   547  		}
   548  
   549  		if !cgoIsGoPointer(p) {
   550  			return
   551  		}
   552  		if !top {
   553  			panic(errorString(msg))
   554  		}
   555  
   556  		cgoCheckUnknownPointer(p, msg)
   557  	}
   558  }
   559  
   560  // cgoCheckUnknownPointer is called for an arbitrary pointer into Go
   561  // memory. It checks whether that Go memory contains any other
   562  // pointer into Go memory. If it does, we panic.
   563  // The return values are unused but useful to see in panic tracebacks.
   564  func cgoCheckUnknownPointer(p unsafe.Pointer, msg string) (base, i uintptr) {
   565  	if inheap(uintptr(p)) {
   566  		b, span, _ := findObject(uintptr(p), 0, 0)
   567  		base = b
   568  		if base == 0 {
   569  			return
   570  		}
   571  		hbits := heapBitsForAddr(base)
   572  		n := span.elemsize
   573  		for i = uintptr(0); i < n; i += goarch.PtrSize {
   574  			if !hbits.morePointers() {
   575  				// No more possible pointers.
   576  				break
   577  			}
   578  			if hbits.isPointer() && cgoIsGoPointer(*(*unsafe.Pointer)(unsafe.Pointer(base + i))) {
   579  				panic(errorString(msg))
   580  			}
   581  			hbits = hbits.next()
   582  		}
   583  
   584  		return
   585  	}
   586  
   587  	for _, datap := range activeModules() {
   588  		if cgoInRange(p, datap.data, datap.edata) || cgoInRange(p, datap.bss, datap.ebss) {
   589  			// We have no way to know the size of the object.
   590  			// We have to assume that it might contain a pointer.
   591  			panic(errorString(msg))
   592  		}
   593  		// In the text or noptr sections, we know that the
   594  		// pointer does not point to a Go pointer.
   595  	}
   596  
   597  	return
   598  }
   599  
   600  // cgoIsGoPointer reports whether the pointer is a Go pointer--a
   601  // pointer to Go memory. We only care about Go memory that might
   602  // contain pointers.
   603  //
   604  //go:nosplit
   605  //go:nowritebarrierrec
   606  func cgoIsGoPointer(p unsafe.Pointer) bool {
   607  	if p == nil {
   608  		return false
   609  	}
   610  
   611  	if inHeapOrStack(uintptr(p)) {
   612  		return true
   613  	}
   614  
   615  	for _, datap := range activeModules() {
   616  		if cgoInRange(p, datap.data, datap.edata) || cgoInRange(p, datap.bss, datap.ebss) {
   617  			return true
   618  		}
   619  	}
   620  
   621  	return false
   622  }
   623  
   624  // cgoInRange reports whether p is between start and end.
   625  //
   626  //go:nosplit
   627  //go:nowritebarrierrec
   628  func cgoInRange(p unsafe.Pointer, start, end uintptr) bool {
   629  	return start <= uintptr(p) && uintptr(p) < end
   630  }
   631  
   632  // cgoCheckResult is called to check the result parameter of an
   633  // exported Go function. It panics if the result is or contains a Go
   634  // pointer.
   635  func cgoCheckResult(val any) {
   636  	if debug.cgocheck == 0 {
   637  		return
   638  	}
   639  
   640  	ep := efaceOf(&val)
   641  	t := ep._type
   642  	cgoCheckArg(t, ep.data, t.kind&kindDirectIface == 0, false, cgoResultFail)
   643  }
   644  

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