stackswitch.go

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build unix && !android && !openbsd
     6  
     7  package main
     8  
     9  /*
    10  void callStackSwitchCallbackFromThread(void);
    11  */
    12  import "C"
    13  
    14  import (
    15  	"fmt"
    16  	"runtime/debug"
    17  )
    18  
    19  func init() {
    20  	register("StackSwitchCallback", StackSwitchCallback)
    21  }
    22  
    23  //export stackSwitchCallback
    24  func stackSwitchCallback() {
    25  	// We want to trigger a bounds check on the g0 stack. To do this, we
    26  	// need to call a splittable function through systemstack().
    27  	// SetGCPercent contains such a systemstack call.
    28  	gogc := debug.SetGCPercent(100)
    29  	debug.SetGCPercent(gogc)
    30  }
    31  
    32  // Regression test for https://go.dev/issue/62440. It should be possible for C
    33  // threads to call into Go from different stacks without crashing due to g0
    34  // stack bounds checks.
    35  //
    36  // N.B. This is only OK for threads created in C. Threads with Go frames up the
    37  // stack must not change the stack out from under us.
    38  func StackSwitchCallback() {
    39  	C.callStackSwitchCallbackFromThread()
    40  
    41  	fmt.Printf("OK\n")
    42  }
    43
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