// Copyright 2009 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package runtime import ( "runtime/internal/atomic" "runtime/internal/sys" "unsafe" ) // The code in this file implements stack trace walking for all architectures. // The most important fact about a given architecture is whether it uses a link register. // On systems with link registers, the prologue for a non-leaf function stores the // incoming value of LR at the bottom of the newly allocated stack frame. // On systems without link registers, the architecture pushes a return PC during // the call instruction, so the return PC ends up above the stack frame. // In this file, the return PC is always called LR, no matter how it was found. // // To date, the opposite of a link register architecture is an x86 architecture. // This code may need to change if some other kind of non-link-register // architecture comes along. // // The other important fact is the size of a pointer: on 32-bit systems the LR // takes up only 4 bytes on the stack, while on 64-bit systems it takes up 8 bytes. // Typically this is ptrSize. // // As an exception, amd64p32 has ptrSize == 4 but the CALL instruction still // stores an 8-byte return PC onto the stack. To accommodate this, we use regSize // as the size of the architecture-pushed return PC. // // usesLR is defined below in terms of minFrameSize, which is defined in // arch_$GOARCH.go. ptrSize and regSize are defined in stubs.go. const usesLR = sys.MinFrameSize > 0 var ( // initialized in tracebackinit goexitPC uintptr jmpdeferPC uintptr mcallPC uintptr morestackPC uintptr mstartPC uintptr rt0_goPC uintptr sigpanicPC uintptr runfinqPC uintptr bgsweepPC uintptr forcegchelperPC uintptr timerprocPC uintptr gcBgMarkWorkerPC uintptr systemstack_switchPC uintptr systemstackPC uintptr stackBarrierPC uintptr cgocallback_gofuncPC uintptr gogoPC uintptr externalthreadhandlerp uintptr // initialized elsewhere ) func tracebackinit() { // Go variable initialization happens late during runtime startup. // Instead of initializing the variables above in the declarations, // schedinit calls this function so that the variables are // initialized and available earlier in the startup sequence. goexitPC = funcPC(goexit) jmpdeferPC = funcPC(jmpdefer) mcallPC = funcPC(mcall) morestackPC = funcPC(morestack) mstartPC = funcPC(mstart) rt0_goPC = funcPC(rt0_go) sigpanicPC = funcPC(sigpanic) runfinqPC = funcPC(runfinq) bgsweepPC = funcPC(bgsweep) forcegchelperPC = funcPC(forcegchelper) timerprocPC = funcPC(timerproc) gcBgMarkWorkerPC = funcPC(gcBgMarkWorker) systemstack_switchPC = funcPC(systemstack_switch) systemstackPC = funcPC(systemstack) stackBarrierPC = funcPC(stackBarrier) cgocallback_gofuncPC = funcPC(cgocallback_gofunc) // used by sigprof handler gogoPC = funcPC(gogo) } // Traceback over the deferred function calls. // Report them like calls that have been invoked but not started executing yet. func tracebackdefers(gp *g, callback func(*stkframe, unsafe.Pointer) bool, v unsafe.Pointer) { var frame stkframe for d := gp._defer; d != nil; d = d.link { fn := d.fn if fn == nil { // Defer of nil function. Args don't matter. frame.pc = 0 frame.fn = nil frame.argp = 0 frame.arglen = 0 frame.argmap = nil } else { frame.pc = fn.fn f := findfunc(frame.pc) if f == nil { print("runtime: unknown pc in defer ", hex(frame.pc), "\n") throw("unknown pc") } frame.fn = f frame.argp = uintptr(deferArgs(d)) frame.arglen, frame.argmap = getArgInfo(&frame, f, true, fn) } frame.continpc = frame.pc if !callback((*stkframe)(noescape(unsafe.Pointer(&frame))), v) { return } } } // Generic traceback. Handles runtime stack prints (pcbuf == nil), // the runtime.Callers function (pcbuf != nil), as well as the garbage // collector (callback != nil). A little clunky to merge these, but avoids // duplicating the code and all its subtlety. func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max int, callback func(*stkframe, unsafe.Pointer) bool, v unsafe.Pointer, flags uint) int { if goexitPC == 0 { throw("gentraceback before goexitPC initialization") } g := getg() if g == gp && g == g.m.curg { // The starting sp has been passed in as a uintptr, and the caller may // have other uintptr-typed stack references as well. // If during one of the calls that got us here or during one of the // callbacks below the stack must be grown, all these uintptr references // to the stack will not be updated, and gentraceback will continue // to inspect the old stack memory, which may no longer be valid. // Even if all the variables were updated correctly, it is not clear that // we want to expose a traceback that begins on one stack and ends // on another stack. That could confuse callers quite a bit. // Instead, we require that gentraceback and any other function that // accepts an sp for the current goroutine (typically obtained by // calling getcallersp) must not run on that goroutine's stack but // instead on the g0 stack. throw("gentraceback cannot trace user goroutine on its own stack") } level, _, _ := gotraceback() // Fix up returns to the stack barrier by fetching the // original return PC from gp.stkbar. stkbarG := gp stkbar := stkbarG.stkbar[stkbarG.stkbarPos:] if pc0 == ^uintptr(0) && sp0 == ^uintptr(0) { // Signal to fetch saved values from gp. if gp.syscallsp != 0 { pc0 = gp.syscallpc sp0 = gp.syscallsp if usesLR { lr0 = 0 } } else { pc0 = gp.sched.pc sp0 = gp.sched.sp if usesLR { lr0 = gp.sched.lr } } } nprint := 0 var frame stkframe frame.pc = pc0 frame.sp = sp0 if usesLR { frame.lr = lr0 } waspanic := false cgoCtxt := gp.cgoCtxt printing := pcbuf == nil && callback == nil _defer := gp._defer for _defer != nil && _defer.sp == _NoArgs { _defer = _defer.link } // If the PC is zero, it's likely a nil function call. // Start in the caller's frame. if frame.pc == 0 { if usesLR { frame.pc = *(*uintptr)(unsafe.Pointer(frame.sp)) frame.lr = 0 } else { frame.pc = uintptr(*(*sys.Uintreg)(unsafe.Pointer(frame.sp))) frame.sp += sys.RegSize } } f := findfunc(frame.pc) if f != nil && f.entry == stackBarrierPC { // We got caught in the middle of a stack barrier // (presumably by a signal), so stkbar may be // inconsistent with the barriers on the stack. // Simulate the completion of the barrier. // // On x86, SP will be exactly one word above // savedLRPtr. On LR machines, SP will be above // savedLRPtr by some frame size. var stkbarPos uintptr if len(stkbar) > 0 && stkbar[0].savedLRPtr < sp0 { // stackBarrier has not incremented stkbarPos. stkbarPos = gp.stkbarPos } else if gp.stkbarPos > 0 && gp.stkbar[gp.stkbarPos-1].savedLRPtr < sp0 { // stackBarrier has incremented stkbarPos. stkbarPos = gp.stkbarPos - 1 } else { printlock() print("runtime: failed to unwind through stackBarrier at SP ", hex(sp0), "; ") gcPrintStkbars(gp, int(gp.stkbarPos)) print("\n") throw("inconsistent state in stackBarrier") } frame.pc = gp.stkbar[stkbarPos].savedLRVal stkbar = gp.stkbar[stkbarPos+1:] f = findfunc(frame.pc) } if f == nil { if callback != nil { print("runtime: unknown pc ", hex(frame.pc), "\n") throw("unknown pc") } return 0 } frame.fn = f var cache pcvalueCache n := 0 for n < max { // Typically: // pc is the PC of the running function. // sp is the stack pointer at that program counter. // fp is the frame pointer (caller's stack pointer) at that program counter, or nil if unknown. // stk is the stack containing sp. // The caller's program counter is lr, unless lr is zero, in which case it is *(uintptr*)sp. f = frame.fn if f.pcsp == 0 { // No frame information, must be external function, like race support. // See golang.org/issue/13568. break } // Found an actual function. // Derive frame pointer and link register. if frame.fp == 0 { // We want to jump over the systemstack switch. If we're running on the // g0, this systemstack is at the top of the stack. // if we're not on g0 or there's a no curg, then this is a regular call. sp := frame.sp if flags&_TraceJumpStack != 0 && f.entry == systemstackPC && gp == g.m.g0 && gp.m.curg != nil { sp = gp.m.curg.sched.sp frame.sp = sp stkbarG = gp.m.curg stkbar = stkbarG.stkbar[stkbarG.stkbarPos:] cgoCtxt = gp.m.curg.cgoCtxt } frame.fp = sp + uintptr(funcspdelta(f, frame.pc, &cache)) if !usesLR { // On x86, call instruction pushes return PC before entering new function. frame.fp += sys.RegSize } } var flr *_func if topofstack(f) { frame.lr = 0 flr = nil } else if usesLR && f.entry == jmpdeferPC { // jmpdefer modifies SP/LR/PC non-atomically. // If a profiling interrupt arrives during jmpdefer, // the stack unwind may see a mismatched register set // and get confused. Stop if we see PC within jmpdefer // to avoid that confusion. // See golang.org/issue/8153. if callback != nil { throw("traceback_arm: found jmpdefer when tracing with callback") } frame.lr = 0 } else { var lrPtr uintptr if usesLR { if n == 0 && frame.sp < frame.fp || frame.lr == 0 { lrPtr = frame.sp frame.lr = *(*uintptr)(unsafe.Pointer(lrPtr)) } } else { if frame.lr == 0 { lrPtr = frame.fp - sys.RegSize frame.lr = uintptr(*(*sys.Uintreg)(unsafe.Pointer(lrPtr))) } } if frame.lr == stackBarrierPC { // Recover original PC. if len(stkbar) == 0 || stkbar[0].savedLRPtr != lrPtr { print("found next stack barrier at ", hex(lrPtr), "; expected ") gcPrintStkbars(stkbarG, len(stkbarG.stkbar)-len(stkbar)) print("\n") throw("missed stack barrier") } frame.lr = stkbar[0].savedLRVal stkbar = stkbar[1:] } flr = findfunc(frame.lr) if flr == nil { // This happens if you get a profiling interrupt at just the wrong time. // In that context it is okay to stop early. // But if callback is set, we're doing a garbage collection and must // get everything, so crash loudly. if callback != nil { print("runtime: unexpected return pc for ", funcname(f), " called from ", hex(frame.lr), "\n") throw("unknown caller pc") } } } frame.varp = frame.fp if !usesLR { // On x86, call instruction pushes return PC before entering new function. frame.varp -= sys.RegSize } // If framepointer_enabled and there's a frame, then // there's a saved bp here. if framepointer_enabled && GOARCH == "amd64" && frame.varp > frame.sp { frame.varp -= sys.RegSize } // Derive size of arguments. // Most functions have a fixed-size argument block, // so we can use metadata about the function f. // Not all, though: there are some variadic functions // in package runtime and reflect, and for those we use call-specific // metadata recorded by f's caller. if callback != nil || printing { frame.argp = frame.fp + sys.MinFrameSize frame.arglen, frame.argmap = getArgInfo(&frame, f, callback != nil, nil) } // Determine frame's 'continuation PC', where it can continue. // Normally this is the return address on the stack, but if sigpanic // is immediately below this function on the stack, then the frame // stopped executing due to a trap, and frame.pc is probably not // a safe point for looking up liveness information. In this panicking case, // the function either doesn't return at all (if it has no defers or if the // defers do not recover) or it returns from one of the calls to // deferproc a second time (if the corresponding deferred func recovers). // It suffices to assume that the most recent deferproc is the one that // returns; everything live at earlier deferprocs is still live at that one. frame.continpc = frame.pc if waspanic { if _defer != nil && _defer.sp == frame.sp { frame.continpc = _defer.pc } else { frame.continpc = 0 } } // Unwind our local defer stack past this frame. for _defer != nil && (_defer.sp == frame.sp || _defer.sp == _NoArgs) { _defer = _defer.link } if skip > 0 { skip-- goto skipped } if pcbuf != nil { (*[1 << 20]uintptr)(unsafe.Pointer(pcbuf))[n] = frame.pc } if callback != nil { if !callback((*stkframe)(noescape(unsafe.Pointer(&frame))), v) { return n } } if printing { if (flags&_TraceRuntimeFrames) != 0 || showframe(f, gp, nprint == 0) { // Print during crash. // main(0x1, 0x2, 0x3) // /home/rsc/go/src/runtime/x.go:23 +0xf // tracepc := frame.pc // back up to CALL instruction for funcline. if (n > 0 || flags&_TraceTrap == 0) && frame.pc > f.entry && !waspanic { tracepc-- } name := funcname(f) if name == "runtime.gopanic" { name = "panic" } print(name, "(") argp := (*[100]uintptr)(unsafe.Pointer(frame.argp)) for i := uintptr(0); i < frame.arglen/sys.PtrSize; i++ { if i >= 10 { print(", ...") break } if i != 0 { print(", ") } print(hex(argp[i])) } print(")\n") file, line := funcline(f, tracepc) print("\t", file, ":", line) if frame.pc > f.entry { print(" +", hex(frame.pc-f.entry)) } if g.m.throwing > 0 && gp == g.m.curg || level >= 2 { print(" fp=", hex(frame.fp), " sp=", hex(frame.sp)) } print("\n") nprint++ } } n++ skipped: if f.entry == cgocallback_gofuncPC && len(cgoCtxt) > 0 { ctxt := cgoCtxt[len(cgoCtxt)-1] cgoCtxt = cgoCtxt[:len(cgoCtxt)-1] // skip only applies to Go frames. // callback != nil only used when we only care // about Go frames. if skip == 0 && callback == nil { n = tracebackCgoContext(pcbuf, printing, ctxt, n, max) } } waspanic = f.entry == sigpanicPC // Do not unwind past the bottom of the stack. if flr == nil { break } // Unwind to next frame. frame.fn = flr frame.pc = frame.lr frame.lr = 0 frame.sp = frame.fp frame.fp = 0 frame.argmap = nil // On link register architectures, sighandler saves the LR on stack // before faking a call to sigpanic. if usesLR && waspanic { x := *(*uintptr)(unsafe.Pointer(frame.sp)) frame.sp += sys.MinFrameSize if GOARCH == "arm64" { // arm64 needs 16-byte aligned SP, always frame.sp += sys.PtrSize } f = findfunc(frame.pc) frame.fn = f if f == nil { frame.pc = x } else if funcspdelta(f, frame.pc, &cache) == 0 { frame.lr = x } } } if printing { n = nprint } // If callback != nil, we're being called to gather stack information during // garbage collection or stack growth. In that context, require that we used // up the entire defer stack. If not, then there is a bug somewhere and the // garbage collection or stack growth may not have seen the correct picture // of the stack. Crash now instead of silently executing the garbage collection // or stack copy incorrectly and setting up for a mysterious crash later. // // Note that panic != nil is okay here: there can be leftover panics, // because the defers on the panic stack do not nest in frame order as // they do on the defer stack. If you have: // // frame 1 defers d1 // frame 2 defers d2 // frame 3 defers d3 // frame 4 panics // frame 4's panic starts running defers // frame 5, running d3, defers d4 // frame 5 panics // frame 5's panic starts running defers // frame 6, running d4, garbage collects // frame 6, running d2, garbage collects // // During the execution of d4, the panic stack is d4 -> d3, which // is nested properly, and we'll treat frame 3 as resumable, because we // can find d3. (And in fact frame 3 is resumable. If d4 recovers // and frame 5 continues running, d3, d3 can recover and we'll // resume execution in (returning from) frame 3.) // // During the execution of d2, however, the panic stack is d2 -> d3, // which is inverted. The scan will match d2 to frame 2 but having // d2 on the stack until then means it will not match d3 to frame 3. // This is okay: if we're running d2, then all the defers after d2 have // completed and their corresponding frames are dead. Not finding d3 // for frame 3 means we'll set frame 3's continpc == 0, which is correct // (frame 3 is dead). At the end of the walk the panic stack can thus // contain defers (d3 in this case) for dead frames. The inversion here // always indicates a dead frame, and the effect of the inversion on the // scan is to hide those dead frames, so the scan is still okay: // what's left on the panic stack are exactly (and only) the dead frames. // // We require callback != nil here because only when callback != nil // do we know that gentraceback is being called in a "must be correct" // context as opposed to a "best effort" context. The tracebacks with // callbacks only happen when everything is stopped nicely. // At other times, such as when gathering a stack for a profiling signal // or when printing a traceback during a crash, everything may not be // stopped nicely, and the stack walk may not be able to complete. // It's okay in those situations not to use up the entire defer stack: // incomplete information then is still better than nothing. if callback != nil && n < max && _defer != nil { if _defer != nil { print("runtime: g", gp.goid, ": leftover defer sp=", hex(_defer.sp), " pc=", hex(_defer.pc), "\n") } for _defer = gp._defer; _defer != nil; _defer = _defer.link { print("\tdefer ", _defer, " sp=", hex(_defer.sp), " pc=", hex(_defer.pc), "\n") } throw("traceback has leftover defers") } if callback != nil && n < max && len(stkbar) > 0 { print("runtime: g", gp.goid, ": leftover stack barriers ") gcPrintStkbars(stkbarG, len(stkbarG.stkbar)-len(stkbar)) print("\n") throw("traceback has leftover stack barriers") } if callback != nil && n < max && frame.sp != gp.stktopsp { print("runtime: g", gp.goid, ": frame.sp=", hex(frame.sp), " top=", hex(gp.stktopsp), "\n") print("\tstack=[", hex(gp.stack.lo), "-", hex(gp.stack.hi), "] n=", n, " max=", max, "\n") throw("traceback did not unwind completely") } return n } // reflectMethodValue is a partial duplicate of reflect.makeFuncImpl // and reflect.methodValue. type reflectMethodValue struct { fn uintptr stack *bitvector // args bitmap } // getArgInfo returns the argument frame information for a call to f // with call frame frame. // // This is used for both actual calls with active stack frames and for // deferred calls that are not yet executing. If this is an actual // call, ctxt must be nil (getArgInfo will retrieve what it needs from // the active stack frame). If this is a deferred call, ctxt must be // the function object that was deferred. func getArgInfo(frame *stkframe, f *_func, needArgMap bool, ctxt *funcval) (arglen uintptr, argmap *bitvector) { arglen = uintptr(f.args) if needArgMap && f.args == _ArgsSizeUnknown { // Extract argument bitmaps for reflect stubs from the calls they made to reflect. switch funcname(f) { case "reflect.makeFuncStub", "reflect.methodValueCall": // These take a *reflect.methodValue as their // context register. var mv *reflectMethodValue if ctxt != nil { // This is not an actual call, but a // deferred call. The function value // is itself the *reflect.methodValue. mv = (*reflectMethodValue)(unsafe.Pointer(ctxt)) } else { // This is a real call that took the // *reflect.methodValue as its context // register and immediately saved it // to 0(SP). Get the methodValue from // 0(SP). arg0 := frame.sp + sys.MinFrameSize mv = *(**reflectMethodValue)(unsafe.Pointer(arg0)) } if mv.fn != f.entry { print("runtime: confused by ", funcname(f), "\n") throw("reflect mismatch") } bv := mv.stack arglen = uintptr(bv.n * sys.PtrSize) argmap = bv } } return } // tracebackCgoContext handles tracing back a cgo context value, from // the context argument to setCgoTraceback, for the gentraceback // function. It returns the new value of n. func tracebackCgoContext(pcbuf *uintptr, printing bool, ctxt uintptr, n, max int) int { var cgoPCs [32]uintptr cgoContextPCs(ctxt, cgoPCs[:]) var arg cgoSymbolizerArg anySymbolized := false for _, pc := range cgoPCs { if pc == 0 || n >= max { break } if pcbuf != nil { (*[1 << 20]uintptr)(unsafe.Pointer(pcbuf))[n] = pc } if printing { if cgoSymbolizer == nil { print("non-Go function at pc=", hex(pc), "\n") } else { c := printOneCgoTraceback(pc, max-n, &arg) n += c - 1 // +1 a few lines down anySymbolized = true } } n++ } if anySymbolized { arg.pc = 0 callCgoSymbolizer(&arg) } return n } func printcreatedby(gp *g) { // Show what created goroutine, except main goroutine (goid 1). pc := gp.gopc f := findfunc(pc) if f != nil && showframe(f, gp, false) && gp.goid != 1 { print("created by ", funcname(f), "\n") tracepc := pc // back up to CALL instruction for funcline. if pc > f.entry { tracepc -= sys.PCQuantum } file, line := funcline(f, tracepc) print("\t", file, ":", line) if pc > f.entry { print(" +", hex(pc-f.entry)) } print("\n") } } func traceback(pc, sp, lr uintptr, gp *g) { traceback1(pc, sp, lr, gp, 0) } // tracebacktrap is like traceback but expects that the PC and SP were obtained // from a trap, not from gp->sched or gp->syscallpc/gp->syscallsp or getcallerpc/getcallersp. // Because they are from a trap instead of from a saved pair, // the initial PC must not be rewound to the previous instruction. // (All the saved pairs record a PC that is a return address, so we // rewind it into the CALL instruction.) func tracebacktrap(pc, sp, lr uintptr, gp *g) { traceback1(pc, sp, lr, gp, _TraceTrap) } func traceback1(pc, sp, lr uintptr, gp *g, flags uint) { // If the goroutine is in cgo, and we have a cgo traceback, print that. if iscgo && gp.m != nil && gp.m.ncgo > 0 && gp.syscallsp != 0 && gp.m.cgoCallers != nil && gp.m.cgoCallers[0] != 0 { // Lock cgoCallers so that a signal handler won't // change it, copy the array, reset it, unlock it. // We are locked to the thread and are not running // concurrently with a signal handler. // We just have to stop a signal handler from interrupting // in the middle of our copy. atomic.Store(&gp.m.cgoCallersUse, 1) cgoCallers := *gp.m.cgoCallers gp.m.cgoCallers[0] = 0 atomic.Store(&gp.m.cgoCallersUse, 0) printCgoTraceback(&cgoCallers) } var n int if readgstatus(gp)&^_Gscan == _Gsyscall { // Override registers if blocked in system call. pc = gp.syscallpc sp = gp.syscallsp flags &^= _TraceTrap } // Print traceback. By default, omits runtime frames. // If that means we print nothing at all, repeat forcing all frames printed. n = gentraceback(pc, sp, lr, gp, 0, nil, _TracebackMaxFrames, nil, nil, flags) if n == 0 && (flags&_TraceRuntimeFrames) == 0 { n = gentraceback(pc, sp, lr, gp, 0, nil, _TracebackMaxFrames, nil, nil, flags|_TraceRuntimeFrames) } if n == _TracebackMaxFrames { print("...additional frames elided...\n") } printcreatedby(gp) } func callers(skip int, pcbuf []uintptr) int { sp := getcallersp(unsafe.Pointer(&skip)) pc := getcallerpc(unsafe.Pointer(&skip)) gp := getg() var n int systemstack(func() { n = gentraceback(pc, sp, 0, gp, skip, &pcbuf[0], len(pcbuf), nil, nil, 0) }) return n } func gcallers(gp *g, skip int, pcbuf []uintptr) int { return gentraceback(^uintptr(0), ^uintptr(0), 0, gp, skip, &pcbuf[0], len(pcbuf), nil, nil, 0) } func showframe(f *_func, gp *g, firstFrame bool) bool { g := getg() if g.m.throwing > 0 && gp != nil && (gp == g.m.curg || gp == g.m.caughtsig.ptr()) { return true } level, _, _ := gotraceback() name := funcname(f) // Special case: always show runtime.gopanic frame // in the middle of a stack trace, so that we can // see the boundary between ordinary code and // panic-induced deferred code. // See golang.org/issue/5832. if name == "runtime.gopanic" && !firstFrame { return true } return level > 1 || f != nil && contains(name, ".") && (!hasprefix(name, "runtime.") || isExportedRuntime(name)) } // isExportedRuntime reports whether name is an exported runtime function. // It is only for runtime functions, so ASCII A-Z is fine. func isExportedRuntime(name string) bool { const n = len("runtime.") return len(name) > n && name[:n] == "runtime." && 'A' <= name[n] && name[n] <= 'Z' } var gStatusStrings = [...]string{ _Gidle: "idle", _Grunnable: "runnable", _Grunning: "running", _Gsyscall: "syscall", _Gwaiting: "waiting", _Gdead: "dead", _Gcopystack: "copystack", } func goroutineheader(gp *g) { gpstatus := readgstatus(gp) isScan := gpstatus&_Gscan != 0 gpstatus &^= _Gscan // drop the scan bit // Basic string status var status string if 0 <= gpstatus && gpstatus < uint32(len(gStatusStrings)) { status = gStatusStrings[gpstatus] } else { status = "???" } // Override. if gpstatus == _Gwaiting && gp.waitreason != "" { status = gp.waitreason } // approx time the G is blocked, in minutes var waitfor int64 if (gpstatus == _Gwaiting || gpstatus == _Gsyscall) && gp.waitsince != 0 { waitfor = (nanotime() - gp.waitsince) / 60e9 } print("goroutine ", gp.goid, " [", status) if isScan { print(" (scan)") } if waitfor >= 1 { print(", ", waitfor, " minutes") } if gp.lockedm != nil { print(", locked to thread") } print("]:\n") } func tracebackothers(me *g) { level, _, _ := gotraceback() // Show the current goroutine first, if we haven't already. g := getg() gp := g.m.curg if gp != nil && gp != me { print("\n") goroutineheader(gp) traceback(^uintptr(0), ^uintptr(0), 0, gp) } lock(&allglock) for _, gp := range allgs { if gp == me || gp == g.m.curg || readgstatus(gp) == _Gdead || isSystemGoroutine(gp) && level < 2 { continue } print("\n") goroutineheader(gp) // Note: gp.m == g.m occurs when tracebackothers is // called from a signal handler initiated during a // systemstack call. The original G is still in the // running state, and we want to print its stack. if gp.m != g.m && readgstatus(gp)&^_Gscan == _Grunning { print("\tgoroutine running on other thread; stack unavailable\n") printcreatedby(gp) } else { traceback(^uintptr(0), ^uintptr(0), 0, gp) } } unlock(&allglock) } // Does f mark the top of a goroutine stack? func topofstack(f *_func) bool { pc := f.entry return pc == goexitPC || pc == mstartPC || pc == mcallPC || pc == morestackPC || pc == rt0_goPC || externalthreadhandlerp != 0 && pc == externalthreadhandlerp } // isSystemGoroutine reports whether the goroutine g must be omitted in // stack dumps and deadlock detector. func isSystemGoroutine(gp *g) bool { pc := gp.startpc return pc == runfinqPC && !fingRunning || pc == bgsweepPC || pc == forcegchelperPC || pc == timerprocPC || pc == gcBgMarkWorkerPC } // SetCgoTraceback records three C functions to use to gather // traceback information from C code and to convert that traceback // information into symbolic information. These are used when printing // stack traces for a program that uses cgo. // // The traceback and context functions may be called from a signal // handler, and must therefore use only async-signal safe functions. // The symbolizer function may be called while the program is // crashing, and so must be cautious about using memory. None of the // functions may call back into Go. // // The context function will be called with a single argument, a // pointer to a struct: // // struct { // Context uintptr // } // // In C syntax, this struct will be // // struct { // uintptr_t Context; // }; // // If the Context field is 0, the context function is being called to // record the current traceback context. It should record in the // Context field whatever information is needed about the current // point of execution to later produce a stack trace, probably the // stack pointer and PC. In this case the context function will be // called from C code. // // If the Context field is not 0, then it is a value returned by a // previous call to the context function. This case is called when the // context is no longer needed; that is, when the Go code is returning // to its C code caller. This permits the context function to release // any associated resources. // // While it would be correct for the context function to record a // complete a stack trace whenever it is called, and simply copy that // out in the traceback function, in a typical program the context // function will be called many times without ever recording a // traceback for that context. Recording a complete stack trace in a // call to the context function is likely to be inefficient. // // The traceback function will be called with a single argument, a // pointer to a struct: // // struct { // Context uintptr // SigContext uintptr // Buf *uintptr // Max uintptr // } // // In C syntax, this struct will be // // struct { // uintptr_t Context; // uintptr_t SigContext; // uintptr_t* Buf; // uintptr_t Max; // }; // // The Context field will be zero to gather a traceback from the // current program execution point. In this case, the traceback // function will be called from C code. // // Otherwise Context will be a value previously returned by a call to // the context function. The traceback function should gather a stack // trace from that saved point in the program execution. The traceback // function may be called from an execution thread other than the one // that recorded the context, but only when the context is known to be // valid and unchanging. The traceback function may also be called // deeper in the call stack on the same thread that recorded the // context. The traceback function may be called multiple times with // the same Context value; it will usually be appropriate to cache the // result, if possible, the first time this is called for a specific // context value. // // If the traceback function is called from a signal handler on a Unix // system, SigContext will be the signal context argument passed to // the signal handler (a C ucontext_t* cast to uintptr_t). This may be // used to start tracing at the point where the signal occurred. If // the traceback function is not called from a signal handler, // SigContext will be zero. // // Buf is where the traceback information should be stored. It should // be PC values, such that Buf[0] is the PC of the caller, Buf[1] is // the PC of that function's caller, and so on. Max is the maximum // number of entries to store. The function should store a zero to // indicate the top of the stack, or that the caller is on a different // stack, presumably a Go stack. // // Unlike runtime.Callers, the PC values returned should, when passed // to the symbolizer function, return the file/line of the call // instruction. No additional subtraction is required or appropriate. // // The symbolizer function will be called with a single argument, a // pointer to a struct: // // struct { // PC uintptr // program counter to fetch information for // File *byte // file name (NUL terminated) // Lineno uintptr // line number // Func *byte // function name (NUL terminated) // Entry uintptr // function entry point // More uintptr // set non-zero if more info for this PC // Data uintptr // unused by runtime, available for function // } // // In C syntax, this struct will be // // struct { // uintptr_t PC; // char* File; // uintptr_t Lineno; // char* Func; // uintptr_t Entry; // uintptr_t More; // uintptr_t Data; // }; // // The PC field will be a value returned by a call to the traceback // function. // // The first time the function is called for a particular traceback, // all the fields except PC will be 0. The function should fill in the // other fields if possible, setting them to 0/nil if the information // is not available. The Data field may be used to store any useful // information across calls. The More field should be set to non-zero // if there is more information for this PC, zero otherwise. If More // is set non-zero, the function will be called again with the same // PC, and may return different information (this is intended for use // with inlined functions). If More is zero, the function will be // called with the next PC value in the traceback. When the traceback // is complete, the function will be called once more with PC set to // zero; this may be used to free any information. Each call will // leave the fields of the struct set to the same values they had upon // return, except for the PC field when the More field is zero. The // function must not keep a copy of the struct pointer between calls. // // When calling SetCgoTraceback, the version argument is the version // number of the structs that the functions expect to receive. // Currently this must be zero. // // The symbolizer function may be nil, in which case the results of // the traceback function will be displayed as numbers. If the // traceback function is nil, the symbolizer function will never be // called. The context function may be nil, in which case the // traceback function will only be called with the context field set // to zero. If the context function is nil, then calls from Go to C // to Go will not show a traceback for the C portion of the call stack. // // SetCgoTraceback should be called only once, ideally from an init function. func SetCgoTraceback(version int, traceback, context, symbolizer unsafe.Pointer) { if version != 0 { panic("unsupported version") } if cgoTraceback != nil && cgoTraceback != traceback || cgoContext != nil && cgoContext != context || cgoSymbolizer != nil && cgoSymbolizer != symbolizer { panic("call SetCgoTraceback only once") } cgoTraceback = traceback cgoContext = context cgoSymbolizer = symbolizer // The context function is called when a C function calls a Go // function. As such it is only called by C code in runtime/cgo. if _cgo_set_context_function != nil { cgocall(_cgo_set_context_function, context) } } var cgoTraceback unsafe.Pointer var cgoContext unsafe.Pointer var cgoSymbolizer unsafe.Pointer // cgoTracebackArg is the type passed to cgoTraceback. type cgoTracebackArg struct { context uintptr sigContext uintptr buf *uintptr max uintptr } // cgoContextArg is the type passed to the context function. type cgoContextArg struct { context uintptr } // cgoSymbolizerArg is the type passed to cgoSymbolizer. type cgoSymbolizerArg struct { pc uintptr file *byte lineno uintptr funcName *byte entry uintptr more uintptr data uintptr } // cgoTraceback prints a traceback of callers. func printCgoTraceback(callers *cgoCallers) { if cgoSymbolizer == nil { for _, c := range callers { if c == 0 { break } print("non-Go function at pc=", hex(c), "\n") } return } var arg cgoSymbolizerArg for _, c := range callers { if c == 0 { break } printOneCgoTraceback(c, 0x7fffffff, &arg) } arg.pc = 0 callCgoSymbolizer(&arg) } // printOneCgoTraceback prints the traceback of a single cgo caller. // This can print more than one line because of inlining. // Returns the number of frames printed. func printOneCgoTraceback(pc uintptr, max int, arg *cgoSymbolizerArg) int { c := 0 arg.pc = pc for { if c > max { break } callCgoSymbolizer(arg) if arg.funcName != nil { // Note that we don't print any argument // information here, not even parentheses. // The symbolizer must add that if appropriate. println(gostringnocopy(arg.funcName)) } else { println("non-Go function") } print("\t") if arg.file != nil { print(gostringnocopy(arg.file), ":", arg.lineno, " ") } print("pc=", hex(pc), "\n") c++ if arg.more == 0 { break } } return c } // callCgoSymbolizer calls the cgoSymbolizer function. func callCgoSymbolizer(arg *cgoSymbolizerArg) { call := cgocall if panicking > 0 || getg().m.curg != getg() { // We do not want to call into the scheduler when panicking // or when on the system stack. call = asmcgocall } if msanenabled { msanwrite(unsafe.Pointer(arg), unsafe.Sizeof(cgoSymbolizerArg{})) } call(cgoSymbolizer, noescape(unsafe.Pointer(arg))) } // cgoContextPCs gets the PC values from a cgo traceback. func cgoContextPCs(ctxt uintptr, buf []uintptr) { if cgoTraceback == nil { return } call := cgocall if panicking > 0 || getg().m.curg != getg() { // We do not want to call into the scheduler when panicking // or when on the system stack. call = asmcgocall } arg := cgoTracebackArg{ context: ctxt, buf: (*uintptr)(noescape(unsafe.Pointer(&buf[0]))), max: uintptr(len(buf)), } if msanenabled { msanwrite(unsafe.Pointer(&arg), unsafe.Sizeof(arg)) } call(cgoTraceback, noescape(unsafe.Pointer(&arg))) }