os3_plan9.go

     1  // Copyright 2010 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/goarch"
    10  	"unsafe"
    11  )
    12  
    13  // May run during STW, so write barriers are not allowed.
    14  //
    15  //go:nowritebarrierrec
    16  func sighandler(_ureg *ureg, note *byte, gp *g) int {
    17  	gsignal := getg()
    18  	mp := gsignal.m
    19  
    20  	var t sigTabT
    21  	var docrash bool
    22  	var sig int
    23  	var flags int
    24  	var level int32
    25  
    26  	c := &sigctxt{_ureg}
    27  	notestr := gostringnocopy(note)
    28  
    29  	// The kernel will never pass us a nil note or ureg so we probably
    30  	// made a mistake somewhere in sigtramp.
    31  	if _ureg == nil || note == nil {
    32  		print("sighandler: ureg ", _ureg, " note ", note, "\n")
    33  		goto Throw
    34  	}
    35  	// Check that the note is no more than ERRMAX bytes (including
    36  	// the trailing NUL). We should never receive a longer note.
    37  	if len(notestr) > _ERRMAX-1 {
    38  		print("sighandler: note is longer than ERRMAX\n")
    39  		goto Throw
    40  	}
    41  	if isAbortPC(c.pc()) {
    42  		// Never turn abort into a panic.
    43  		goto Throw
    44  	}
    45  	// See if the note matches one of the patterns in sigtab.
    46  	// Notes that do not match any pattern can be handled at a higher
    47  	// level by the program but will otherwise be ignored.
    48  	flags = _SigNotify
    49  	for sig, t = range sigtable {
    50  		if hasPrefix(notestr, t.name) {
    51  			flags = t.flags
    52  			break
    53  		}
    54  	}
    55  	if flags&_SigPanic != 0 && gp.throwsplit {
    56  		// We can't safely sigpanic because it may grow the
    57  		// stack. Abort in the signal handler instead.
    58  		flags = (flags &^ _SigPanic) | _SigThrow
    59  	}
    60  	if flags&_SigGoExit != 0 {
    61  		exits((*byte)(add(unsafe.Pointer(note), 9))) // Strip "go: exit " prefix.
    62  	}
    63  	if flags&_SigPanic != 0 {
    64  		// Copy the error string from sigtramp's stack into m->notesig so
    65  		// we can reliably access it from the panic routines.
    66  		memmove(unsafe.Pointer(mp.notesig), unsafe.Pointer(note), uintptr(len(notestr)+1))
    67  		gp.sig = uint32(sig)
    68  		gp.sigpc = c.pc()
    69  
    70  		pc := c.pc()
    71  		sp := c.sp()
    72  
    73  		// If we don't recognize the PC as code
    74  		// but we do recognize the top pointer on the stack as code,
    75  		// then assume this was a call to non-code and treat like
    76  		// pc == 0, to make unwinding show the context.
    77  		if pc != 0 && !findfunc(pc).valid() && findfunc(*(*uintptr)(unsafe.Pointer(sp))).valid() {
    78  			pc = 0
    79  		}
    80  
    81  		// IF LR exists, sigpanictramp must save it to the stack
    82  		// before entry to sigpanic so that panics in leaf
    83  		// functions are correctly handled. This will smash
    84  		// the stack frame but we're not going back there
    85  		// anyway.
    86  		if usesLR {
    87  			c.savelr(c.lr())
    88  		}
    89  
    90  		// If PC == 0, probably panicked because of a call to a nil func.
    91  		// Not faking that as the return address will make the trace look like a call
    92  		// to sigpanic instead. (Otherwise the trace will end at
    93  		// sigpanic and we won't get to see who faulted).
    94  		if pc != 0 {
    95  			if usesLR {
    96  				c.setlr(pc)
    97  			} else {
    98  				sp -= goarch.PtrSize
    99  				*(*uintptr)(unsafe.Pointer(sp)) = pc
   100  				c.setsp(sp)
   101  			}
   102  		}
   103  		if usesLR {
   104  			c.setpc(abi.FuncPCABI0(sigpanictramp))
   105  		} else {
   106  			c.setpc(abi.FuncPCABI0(sigpanic0))
   107  		}
   108  		return _NCONT
   109  	}
   110  	if flags&_SigNotify != 0 {
   111  		if ignoredNote(note) {
   112  			return _NCONT
   113  		}
   114  		if sendNote(note) {
   115  			return _NCONT
   116  		}
   117  	}
   118  	if flags&_SigKill != 0 {
   119  		goto Exit
   120  	}
   121  	if flags&_SigThrow == 0 {
   122  		return _NCONT
   123  	}
   124  Throw:
   125  	mp.throwing = throwTypeRuntime
   126  	mp.caughtsig.set(gp)
   127  	startpanic_m()
   128  	print(notestr, "\n")
   129  	print("PC=", hex(c.pc()), "\n")
   130  	print("\n")
   131  	level, _, docrash = gotraceback()
   132  	if level > 0 {
   133  		goroutineheader(gp)
   134  		tracebacktrap(c.pc(), c.sp(), c.lr(), gp)
   135  		tracebackothers(gp)
   136  		print("\n")
   137  		dumpregs(_ureg)
   138  	}
   139  	if docrash {
   140  		crash()
   141  	}
   142  Exit:
   143  	goexitsall(note)
   144  	exits(note)
   145  	return _NDFLT // not reached
   146  }
   147  
   148  func sigenable(sig uint32) {
   149  }
   150  
   151  func sigdisable(sig uint32) {
   152  }
   153  
   154  func sigignore(sig uint32) {
   155  }
   156  
   157  func setProcessCPUProfiler(hz int32) {
   158  }
   159  
   160  func setThreadCPUProfiler(hz int32) {
   161  	// TODO: Enable profiling interrupts.
   162  	getg().m.profilehz = hz
   163  }
   164  
   165  // gsignalStack is unused on Plan 9.
   166  type gsignalStack struct{}
   167
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