// 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 ( "internal/abi" "internal/bytealg" "internal/goarch" "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 (x86), 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. const usesLR = sys.MinFrameSize > 0 const ( // tracebackInnerFrames is the number of innermost frames to print in a // stack trace. The total maximum frames is tracebackInnerFrames + // tracebackOuterFrames. tracebackInnerFrames = 50 // tracebackOuterFrames is the number of outermost frames to print in a // stack trace. tracebackOuterFrames = 50 ) // unwindFlags control the behavior of various unwinders. type unwindFlags uint8 const ( // unwindPrintErrors indicates that if unwinding encounters an error, it // should print a message and stop without throwing. This is used for things // like stack printing, where it's better to get incomplete information than // to crash. This is also used in situations where everything may not be // stopped nicely and the stack walk may not be able to complete, such as // during profiling signals or during a crash. // // If neither unwindPrintErrors or unwindSilentErrors are set, unwinding // performs extra consistency checks and throws on any error. // // Note that there are a small number of fatal situations that will throw // regardless of unwindPrintErrors or unwindSilentErrors. unwindPrintErrors unwindFlags = 1 << iota // unwindSilentErrors silently ignores errors during unwinding. unwindSilentErrors // unwindTrap indicates that the initial PC and SP are from a trap, not a // return PC from a call. // // The unwindTrap flag is updated during unwinding. If set, frame.pc is the // address of a faulting instruction instead of the return address of a // call. It also means the liveness at pc may not be known. // // TODO: Distinguish frame.continpc, which is really the stack map PC, from // the actual continuation PC, which is computed differently depending on // this flag and a few other things. unwindTrap // unwindJumpStack indicates that, if the traceback is on a system stack, it // should resume tracing at the user stack when the system stack is // exhausted. unwindJumpStack ) // An unwinder iterates the physical stack frames of a Go sack. // // Typical use of an unwinder looks like: // // var u unwinder // for u.init(gp, 0); u.valid(); u.next() { // // ... use frame info in u ... // } // // Implementation note: This is carefully structured to be pointer-free because // tracebacks happen in places that disallow write barriers (e.g., signals). // Even if this is stack-allocated, its pointer-receiver methods don't know that // their receiver is on the stack, so they still emit write barriers. Here we // address that by carefully avoiding any pointers in this type. Another // approach would be to split this into a mutable part that's passed by pointer // but contains no pointers itself and an immutable part that's passed and // returned by value and can contain pointers. We could potentially hide that // we're doing that in trivial methods that are inlined into the caller that has // the stack allocation, but that's fragile. type unwinder struct { // frame is the current physical stack frame, or all 0s if // there is no frame. frame stkframe // g is the G who's stack is being unwound. If the // unwindJumpStack flag is set and the unwinder jumps stacks, // this will be different from the initial G. g guintptr // cgoCtxt is the index into g.cgoCtxt of the next frame on the cgo stack. // The cgo stack is unwound in tandem with the Go stack as we find marker frames. cgoCtxt int // calleeFuncID is the function ID of the caller of the current // frame. calleeFuncID abi.FuncID // flags are the flags to this unwind. Some of these are updated as we // unwind (see the flags documentation). flags unwindFlags } // init initializes u to start unwinding gp's stack and positions the // iterator on gp's innermost frame. gp must not be the current G. // // A single unwinder can be reused for multiple unwinds. func (u *unwinder) init(gp *g, flags unwindFlags) { // Implementation note: This starts the iterator on the first frame and we // provide a "valid" method. Alternatively, this could start in a "before // the first frame" state and "next" could return whether it was able to // move to the next frame, but that's both more awkward to use in a "for" // loop and is harder to implement because we have to do things differently // for the first frame. u.initAt(^uintptr(0), ^uintptr(0), ^uintptr(0), gp, flags) } func (u *unwinder) initAt(pc0, sp0, lr0 uintptr, gp *g, flags unwindFlags) { // Don't call this "g"; it's too easy get "g" and "gp" confused. if ourg := getg(); ourg == gp && ourg == ourg.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 traceback 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 initAt 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("cannot trace user goroutine on its own stack") } 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 } } } var frame stkframe frame.pc = pc0 frame.sp = sp0 if usesLR { frame.lr = lr0 } // 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)(unsafe.Pointer(frame.sp)) frame.sp += goarch.PtrSize } } // runtime/internal/atomic functions call into kernel helpers on // arm < 7. See runtime/internal/atomic/sys_linux_arm.s. // // Start in the caller's frame. if GOARCH == "arm" && goarm < 7 && GOOS == "linux" && frame.pc&0xffff0000 == 0xffff0000 { // Note that the calls are simple BL without pushing the return // address, so we use LR directly. // // The kernel helpers are frameless leaf functions, so SP and // LR are not touched. frame.pc = frame.lr frame.lr = 0 } f := findfunc(frame.pc) if !f.valid() { if flags&unwindSilentErrors == 0 { print("runtime: g ", gp.goid, " gp=", gp, ": unknown pc ", hex(frame.pc), "\n") tracebackHexdump(gp.stack, &frame, 0) } if flags&(unwindPrintErrors|unwindSilentErrors) == 0 { throw("unknown pc") } *u = unwinder{} return } frame.fn = f // Populate the unwinder. *u = unwinder{ frame: frame, g: gp.guintptr(), cgoCtxt: len(gp.cgoCtxt) - 1, calleeFuncID: abi.FuncIDNormal, flags: flags, } isSyscall := frame.pc == pc0 && frame.sp == sp0 && pc0 == gp.syscallpc && sp0 == gp.syscallsp u.resolveInternal(true, isSyscall) } func (u *unwinder) valid() bool { return u.frame.pc != 0 } // resolveInternal fills in u.frame based on u.frame.fn, pc, and sp. // // innermost indicates that this is the first resolve on this stack. If // innermost is set, isSyscall indicates that the PC/SP was retrieved from // gp.syscall*; this is otherwise ignored. // // On entry, u.frame contains: // - fn is the running function. // - pc is the PC in the running function. // - sp is the stack pointer at that program counter. // - For the innermost frame on LR machines, lr is the program counter that called fn. // // On return, u.frame contains: // - fp is the stack pointer of the caller. // - lr is the program counter that called fn. // - varp, argp, and continpc are populated for the current frame. // // If fn is a stack-jumping function, resolveInternal can change the entire // frame state to follow that stack jump. // // This is internal to unwinder. func (u *unwinder) resolveInternal(innermost, isSyscall bool) { frame := &u.frame gp := u.g.ptr() f := frame.fn if f.pcsp == 0 { // No frame information, must be external function, like race support. // See golang.org/issue/13568. u.finishInternal() return } // Compute function info flags. flag := f.flag if f.funcID == abi.FuncID_cgocallback { // cgocallback does write SP to switch from the g0 to the curg stack, // but it carefully arranges that during the transition BOTH stacks // have cgocallback frame valid for unwinding through. // So we don't need to exclude it with the other SP-writing functions. flag &^= abi.FuncFlagSPWrite } if isSyscall { // Some Syscall functions write to SP, but they do so only after // saving the entry PC/SP using entersyscall. // Since we are using the entry PC/SP, the later SP write doesn't matter. flag &^= abi.FuncFlagSPWrite } // Found an actual function. // Derive frame pointer. if frame.fp == 0 { // Jump over system stack transitions. If we're on g0 and there's a user // goroutine, try to jump. Otherwise this is a regular call. // We also defensively check that this won't switch M's on us, // which could happen at critical points in the scheduler. // This ensures gp.m doesn't change from a stack jump. if u.flags&unwindJumpStack != 0 && gp == gp.m.g0 && gp.m.curg != nil && gp.m.curg.m == gp.m { switch f.funcID { case abi.FuncID_morestack: // morestack does not return normally -- newstack() // gogo's to curg.sched. Match that. // This keeps morestack() from showing up in the backtrace, // but that makes some sense since it'll never be returned // to. gp = gp.m.curg u.g.set(gp) frame.pc = gp.sched.pc frame.fn = findfunc(frame.pc) f = frame.fn flag = f.flag frame.lr = gp.sched.lr frame.sp = gp.sched.sp u.cgoCtxt = len(gp.cgoCtxt) - 1 case abi.FuncID_systemstack: // systemstack returns normally, so just follow the // stack transition. if usesLR && funcspdelta(f, frame.pc) == 0 { // We're at the function prologue and the stack // switch hasn't happened, or epilogue where we're // about to return. Just unwind normally. // Do this only on LR machines because on x86 // systemstack doesn't have an SP delta (the CALL // instruction opens the frame), therefore no way // to check. flag &^= abi.FuncFlagSPWrite break } gp = gp.m.curg u.g.set(gp) frame.sp = gp.sched.sp u.cgoCtxt = len(gp.cgoCtxt) - 1 flag &^= abi.FuncFlagSPWrite } } frame.fp = frame.sp + uintptr(funcspdelta(f, frame.pc)) if !usesLR { // On x86, call instruction pushes return PC before entering new function. frame.fp += goarch.PtrSize } } // Derive link register. if flag&abi.FuncFlagTopFrame != 0 { // This function marks the top of the stack. Stop the traceback. frame.lr = 0 } else if flag&abi.FuncFlagSPWrite != 0 && (!innermost || u.flags&(unwindPrintErrors|unwindSilentErrors) != 0) { // The function we are in does a write to SP that we don't know // how to encode in the spdelta table. Examples include context // switch routines like runtime.gogo but also any code that switches // to the g0 stack to run host C code. // We can't reliably unwind the SP (we might not even be on // the stack we think we are), so stop the traceback here. // // The one exception (encoded in the complex condition above) is that // we assume if we're doing a precise traceback, and this is the // innermost frame, that the SPWRITE function voluntarily preempted itself on entry // during the stack growth check. In that case, the function has // not yet had a chance to do any writes to SP and is safe to unwind. // isAsyncSafePoint does not allow assembly functions to be async preempted, // and preemptPark double-checks that SPWRITE functions are not async preempted. // So for GC stack traversal, we can safely ignore SPWRITE for the innermost frame, // but farther up the stack we'd better not find any. // This is somewhat imprecise because we're just guessing that we're in the stack // growth check. It would be better if SPWRITE were encoded in the spdelta // table so we would know for sure that we were still in safe code. // // uSE uPE inn | action // T _ _ | frame.lr = 0 // F T _ | frame.lr = 0 // F F F | print; panic // F F T | ignore SPWrite if u.flags&(unwindPrintErrors|unwindSilentErrors) == 0 && !innermost { println("traceback: unexpected SPWRITE function", funcname(f)) throw("traceback") } frame.lr = 0 } else { var lrPtr uintptr if usesLR { if innermost && frame.sp < frame.fp || frame.lr == 0 { lrPtr = frame.sp frame.lr = *(*uintptr)(unsafe.Pointer(lrPtr)) } } else { if frame.lr == 0 { lrPtr = frame.fp - goarch.PtrSize frame.lr = *(*uintptr)(unsafe.Pointer(lrPtr)) } } } frame.varp = frame.fp if !usesLR { // On x86, call instruction pushes return PC before entering new function. frame.varp -= goarch.PtrSize } // For architectures with frame pointers, if there's // a frame, then there's a saved frame pointer here. // // NOTE: This code is not as general as it looks. // On x86, the ABI is to save the frame pointer word at the // top of the stack frame, so we have to back down over it. // On arm64, the frame pointer should be at the bottom of // the stack (with R29 (aka FP) = RSP), in which case we would // not want to do the subtraction here. But we started out without // any frame pointer, and when we wanted to add it, we didn't // want to break all the assembly doing direct writes to 8(RSP) // to set the first parameter to a called function. // So we decided to write the FP link *below* the stack pointer // (with R29 = RSP - 8 in Go functions). // This is technically ABI-compatible but not standard. // And it happens to end up mimicking the x86 layout. // Other architectures may make different decisions. if frame.varp > frame.sp && framepointer_enabled { frame.varp -= goarch.PtrSize } frame.argp = frame.fp + sys.MinFrameSize // 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). // In the latter case, use a deferreturn call site as the continuation pc. frame.continpc = frame.pc if u.calleeFuncID == abi.FuncID_sigpanic { if frame.fn.deferreturn != 0 { frame.continpc = frame.fn.entry() + uintptr(frame.fn.deferreturn) + 1 // Note: this may perhaps keep return variables alive longer than // strictly necessary, as we are using "function has a defer statement" // as a proxy for "function actually deferred something". It seems // to be a minor drawback. (We used to actually look through the // gp._defer for a defer corresponding to this function, but that // is hard to do with defer records on the stack during a stack copy.) // Note: the +1 is to offset the -1 that // stack.go:getStackMap does to back up a return // address make sure the pc is in the CALL instruction. } else { frame.continpc = 0 } } } func (u *unwinder) next() { frame := &u.frame f := frame.fn gp := u.g.ptr() // Do not unwind past the bottom of the stack. if frame.lr == 0 { u.finishInternal() return } flr := findfunc(frame.lr) if !flr.valid() { // This happens if you get a profiling interrupt at just the wrong time. // In that context it is okay to stop early. // But if no error flags are set, we're doing a garbage collection and must // get everything, so crash loudly. fail := u.flags&(unwindPrintErrors|unwindSilentErrors) == 0 doPrint := u.flags&unwindSilentErrors == 0 if doPrint && gp.m.incgo && f.funcID == abi.FuncID_sigpanic { // We can inject sigpanic // calls directly into C code, // in which case we'll see a C // return PC. Don't complain. doPrint = false } if fail || doPrint { print("runtime: g ", gp.goid, ": unexpected return pc for ", funcname(f), " called from ", hex(frame.lr), "\n") tracebackHexdump(gp.stack, frame, 0) } if fail { throw("unknown caller pc") } frame.lr = 0 u.finishInternal() return } if frame.pc == frame.lr && frame.sp == frame.fp { // If the next frame is identical to the current frame, we cannot make progress. print("runtime: traceback stuck. pc=", hex(frame.pc), " sp=", hex(frame.sp), "\n") tracebackHexdump(gp.stack, frame, frame.sp) throw("traceback stuck") } injectedCall := f.funcID == abi.FuncID_sigpanic || f.funcID == abi.FuncID_asyncPreempt || f.funcID == abi.FuncID_debugCallV2 if injectedCall { u.flags |= unwindTrap } else { u.flags &^= unwindTrap } // Unwind to next frame. u.calleeFuncID = f.funcID frame.fn = flr frame.pc = frame.lr frame.lr = 0 frame.sp = frame.fp frame.fp = 0 // On link register architectures, sighandler saves the LR on stack // before faking a call. if usesLR && injectedCall { x := *(*uintptr)(unsafe.Pointer(frame.sp)) frame.sp += alignUp(sys.MinFrameSize, sys.StackAlign) f = findfunc(frame.pc) frame.fn = f if !f.valid() { frame.pc = x } else if funcspdelta(f, frame.pc) == 0 { frame.lr = x } } u.resolveInternal(false, false) } // finishInternal is an unwinder-internal helper called after the stack has been // exhausted. It sets the unwinder to an invalid state and checks that it // successfully unwound the entire stack. func (u *unwinder) finishInternal() { u.frame.pc = 0 // 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. gp := u.g.ptr() if u.flags&(unwindPrintErrors|unwindSilentErrors) == 0 && u.frame.sp != gp.stktopsp { print("runtime: g", gp.goid, ": frame.sp=", hex(u.frame.sp), " top=", hex(gp.stktopsp), "\n") print("\tstack=[", hex(gp.stack.lo), "-", hex(gp.stack.hi), "\n") throw("traceback did not unwind completely") } } // symPC returns the PC that should be used for symbolizing the current frame. // Specifically, this is the PC of the last instruction executed in this frame. // // If this frame did a normal call, then frame.pc is a return PC, so this will // return frame.pc-1, which points into the CALL instruction. If the frame was // interrupted by a signal (e.g., profiler, segv, etc) then frame.pc is for the // trapped instruction, so this returns frame.pc. See issue #34123. Finally, // frame.pc can be at function entry when the frame is initialized without // actually running code, like in runtime.mstart, in which case this returns // frame.pc because that's the best we can do. func (u *unwinder) symPC() uintptr { if u.flags&unwindTrap == 0 && u.frame.pc > u.frame.fn.entry() { // Regular call. return u.frame.pc - 1 } // Trapping instruction or we're at the function entry point. return u.frame.pc } // cgoCallers populates pcBuf with the cgo callers of the current frame using // the registered cgo unwinder. It returns the number of PCs written to pcBuf. // If the current frame is not a cgo frame or if there's no registered cgo // unwinder, it returns 0. func (u *unwinder) cgoCallers(pcBuf []uintptr) int { if cgoTraceback == nil || u.frame.fn.funcID != abi.FuncID_cgocallback || u.cgoCtxt < 0 { // We don't have a cgo unwinder (typical case), or we do but we're not // in a cgo frame or we're out of cgo context. return 0 } ctxt := u.g.ptr().cgoCtxt[u.cgoCtxt] u.cgoCtxt-- cgoContextPCs(ctxt, pcBuf) for i, pc := range pcBuf { if pc == 0 { return i } } return len(pcBuf) } // tracebackPCs populates pcBuf with the return addresses for each frame from u // and returns the number of PCs written to pcBuf. The returned PCs correspond // to "logical frames" rather than "physical frames"; that is if A is inlined // into B, this will still return a PCs for both A and B. This also includes PCs // generated by the cgo unwinder, if one is registered. // // If skip != 0, this skips this many logical frames. // // Callers should set the unwindSilentErrors flag on u. func tracebackPCs(u *unwinder, skip int, pcBuf []uintptr) int { var cgoBuf [32]uintptr n := 0 for ; n < len(pcBuf) && u.valid(); u.next() { f := u.frame.fn cgoN := u.cgoCallers(cgoBuf[:]) // TODO: Why does &u.cache cause u to escape? (Same in traceback2) for iu, uf := newInlineUnwinder(f, u.symPC()); n < len(pcBuf) && uf.valid(); uf = iu.next(uf) { sf := iu.srcFunc(uf) if sf.funcID == abi.FuncIDWrapper && elideWrapperCalling(u.calleeFuncID) { // ignore wrappers } else if skip > 0 { skip-- } else { // Callers expect the pc buffer to contain return addresses // and do the -1 themselves, so we add 1 to the call PC to // create a return PC. pcBuf[n] = uf.pc + 1 n++ } u.calleeFuncID = sf.funcID } // Add cgo frames (if we're done skipping over the requested number of // Go frames). if skip == 0 { n += copy(pcBuf[n:], cgoBuf[:cgoN]) } } return n } // printArgs prints function arguments in traceback. func printArgs(f funcInfo, argp unsafe.Pointer, pc uintptr) { // The "instruction" of argument printing is encoded in _FUNCDATA_ArgInfo. // See cmd/compile/internal/ssagen.emitArgInfo for the description of the // encoding. // These constants need to be in sync with the compiler. const ( _endSeq = 0xff _startAgg = 0xfe _endAgg = 0xfd _dotdotdot = 0xfc _offsetTooLarge = 0xfb ) const ( limit = 10 // print no more than 10 args/components maxDepth = 5 // no more than 5 layers of nesting maxLen = (maxDepth*3+2)*limit + 1 // max length of _FUNCDATA_ArgInfo (see the compiler side for reasoning) ) p := (*[maxLen]uint8)(funcdata(f, abi.FUNCDATA_ArgInfo)) if p == nil { return } liveInfo := funcdata(f, abi.FUNCDATA_ArgLiveInfo) liveIdx := pcdatavalue(f, abi.PCDATA_ArgLiveIndex, pc) startOffset := uint8(0xff) // smallest offset that needs liveness info (slots with a lower offset is always live) if liveInfo != nil { startOffset = *(*uint8)(liveInfo) } isLive := func(off, slotIdx uint8) bool { if liveInfo == nil || liveIdx <= 0 { return true // no liveness info, always live } if off < startOffset { return true } bits := *(*uint8)(add(liveInfo, uintptr(liveIdx)+uintptr(slotIdx/8))) return bits&(1<<(slotIdx%8)) != 0 } print1 := func(off, sz, slotIdx uint8) { x := readUnaligned64(add(argp, uintptr(off))) // mask out irrelevant bits if sz < 8 { shift := 64 - sz*8 if goarch.BigEndian { x = x >> shift } else { x = x << shift >> shift } } print(hex(x)) if !isLive(off, slotIdx) { print("?") } } start := true printcomma := func() { if !start { print(", ") } } pi := 0 slotIdx := uint8(0) // register arg spill slot index printloop: for { o := p[pi] pi++ switch o { case _endSeq: break printloop case _startAgg: printcomma() print("{") start = true continue case _endAgg: print("}") case _dotdotdot: printcomma() print("...") case _offsetTooLarge: printcomma() print("_") default: printcomma() sz := p[pi] pi++ print1(o, sz, slotIdx) if o >= startOffset { slotIdx++ } } start = false } } // funcNamePiecesForPrint returns the function name for printing to the user. // It returns three pieces so it doesn't need an allocation for string // concatenation. func funcNamePiecesForPrint(name string) (string, string, string) { // Replace the shape name in generic function with "...". i := bytealg.IndexByteString(name, '[') if i < 0 { return name, "", "" } j := len(name) - 1 for name[j] != ']' { j-- } if j <= i { return name, "", "" } return name[:i], "[...]", name[j+1:] } // funcNameForPrint returns the function name for printing to the user. func funcNameForPrint(name string) string { a, b, c := funcNamePiecesForPrint(name) return a + b + c } // printFuncName prints a function name. name is the function name in // the binary's func data table. func printFuncName(name string) { if name == "runtime.gopanic" { print("panic") return } a, b, c := funcNamePiecesForPrint(name) print(a, b, c) } func printcreatedby(gp *g) { // Show what created goroutine, except main goroutine (goid 1). pc := gp.gopc f := findfunc(pc) if f.valid() && showframe(f.srcFunc(), gp, false, abi.FuncIDNormal) && gp.goid != 1 { printcreatedby1(f, pc, gp.parentGoid) } } func printcreatedby1(f funcInfo, pc uintptr, goid uint64) { print("created by ") printFuncName(funcname(f)) if goid != 0 { print(" in goroutine ", goid) } print("\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.) // If gp.m.libcall{g,pc,sp} information is available, it uses that information in preference to // the pc/sp/lr passed in. func tracebacktrap(pc, sp, lr uintptr, gp *g) { if gp.m.libcallsp != 0 { // We're in C code somewhere, traceback from the saved position. traceback1(gp.m.libcallpc, gp.m.libcallsp, 0, gp.m.libcallg.ptr(), 0) return } traceback1(pc, sp, lr, gp, unwindTrap) } func traceback1(pc, sp, lr uintptr, gp *g, flags unwindFlags) { // 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. gp.m.cgoCallersUse.Store(1) cgoCallers := *gp.m.cgoCallers gp.m.cgoCallers[0] = 0 gp.m.cgoCallersUse.Store(0) printCgoTraceback(&cgoCallers) } if readgstatus(gp)&^_Gscan == _Gsyscall { // Override registers if blocked in system call. pc = gp.syscallpc sp = gp.syscallsp flags &^= unwindTrap } if gp.m != nil && gp.m.vdsoSP != 0 { // Override registers if running in VDSO. This comes after the // _Gsyscall check to cover VDSO calls after entersyscall. pc = gp.m.vdsoPC sp = gp.m.vdsoSP flags &^= unwindTrap } // Print traceback. // // We print the first tracebackInnerFrames frames, and the last // tracebackOuterFrames frames. There are many possible approaches to this. // There are various complications to this: // // - We'd prefer to walk the stack once because in really bad situations // traceback may crash (and we want as much output as possible) or the stack // may be changing. // // - Each physical frame can represent several logical frames, so we might // have to pause in the middle of a physical frame and pick up in the middle // of a physical frame. // // - The cgo symbolizer can expand a cgo PC to more than one logical frame, // and involves juggling state on the C side that we don't manage. Since its // expansion state is managed on the C side, we can't capture the expansion // state part way through, and because the output strings are managed on the // C side, we can't capture the output. Thus, our only choice is to replay a // whole expansion, potentially discarding some of it. // // Rejected approaches: // // - Do two passes where the first pass just counts and the second pass does // all the printing. This is undesirable if the stack is corrupted or changing // because we won't see a partial stack if we panic. // // - Keep a ring buffer of the last N logical frames and use this to print // the bottom frames once we reach the end of the stack. This works, but // requires keeping a surprising amount of state on the stack, and we have // to run the cgo symbolizer twice—once to count frames, and a second to // print them—since we can't retain the strings it returns. // // Instead, we print the outer frames, and if we reach that limit, we clone // the unwinder, count the remaining frames, and then skip forward and // finish printing from the clone. This makes two passes over the outer part // of the stack, but the single pass over the inner part ensures that's // printed immediately and not revisited. It keeps minimal state on the // stack. And through a combination of skip counts and limits, we can do all // of the steps we need with a single traceback printer implementation. // // We could be more lax about exactly how many frames we print, for example // always stopping and resuming on physical frame boundaries, or at least // cgo expansion boundaries. It's not clear that's much simpler. flags |= unwindPrintErrors var u unwinder tracebackWithRuntime := func(showRuntime bool) int { const maxInt int = 0x7fffffff u.initAt(pc, sp, lr, gp, flags) n, lastN := traceback2(&u, showRuntime, 0, tracebackInnerFrames) if n < tracebackInnerFrames { // We printed the whole stack. return n } // Clone the unwinder and figure out how many frames are left. This // count will include any logical frames already printed for u's current // physical frame. u2 := u remaining, _ := traceback2(&u, showRuntime, maxInt, 0) elide := remaining - lastN - tracebackOuterFrames if elide > 0 { print("...", elide, " frames elided...\n") traceback2(&u2, showRuntime, lastN+elide, tracebackOuterFrames) } else if elide <= 0 { // There are tracebackOuterFrames or fewer frames left to print. // Just print the rest of the stack. traceback2(&u2, showRuntime, lastN, tracebackOuterFrames) } return n } // By default, omits runtime frames. If that means we print nothing at all, // repeat forcing all frames printed. if tracebackWithRuntime(false) == 0 { tracebackWithRuntime(true) } printcreatedby(gp) if gp.ancestors == nil { return } for _, ancestor := range *gp.ancestors { printAncestorTraceback(ancestor) } } // traceback2 prints a stack trace starting at u. It skips the first "skip" // logical frames, after which it prints at most "max" logical frames. It // returns n, which is the number of logical frames skipped and printed, and // lastN, which is the number of logical frames skipped or printed just in the // physical frame that u references. func traceback2(u *unwinder, showRuntime bool, skip, max int) (n, lastN int) { // commitFrame commits to a logical frame and returns whether this frame // should be printed and whether iteration should stop. commitFrame := func() (pr, stop bool) { if skip == 0 && max == 0 { // Stop return false, true } n++ lastN++ if skip > 0 { // Skip skip-- return false, false } // Print max-- return true, false } gp := u.g.ptr() level, _, _ := gotraceback() var cgoBuf [32]uintptr for ; u.valid(); u.next() { lastN = 0 f := u.frame.fn for iu, uf := newInlineUnwinder(f, u.symPC()); uf.valid(); uf = iu.next(uf) { sf := iu.srcFunc(uf) callee := u.calleeFuncID u.calleeFuncID = sf.funcID if !(showRuntime || showframe(sf, gp, n == 0, callee)) { continue } if pr, stop := commitFrame(); stop { return } else if !pr { continue } name := sf.name() file, line := iu.fileLine(uf) // Print during crash. // main(0x1, 0x2, 0x3) // /home/rsc/go/src/runtime/x.go:23 +0xf // printFuncName(name) print("(") if iu.isInlined(uf) { print("...") } else { argp := unsafe.Pointer(u.frame.argp) printArgs(f, argp, u.symPC()) } print(")\n") print("\t", file, ":", line) if !iu.isInlined(uf) { if u.frame.pc > f.entry() { print(" +", hex(u.frame.pc-f.entry())) } if gp.m != nil && gp.m.throwing >= throwTypeRuntime && gp == gp.m.curg || level >= 2 { print(" fp=", hex(u.frame.fp), " sp=", hex(u.frame.sp), " pc=", hex(u.frame.pc)) } } print("\n") } // Print cgo frames. if cgoN := u.cgoCallers(cgoBuf[:]); cgoN > 0 { var arg cgoSymbolizerArg anySymbolized := false stop := false for _, pc := range cgoBuf[:cgoN] { if cgoSymbolizer == nil { if pr, stop := commitFrame(); stop { break } else if pr { print("non-Go function at pc=", hex(pc), "\n") } } else { stop = printOneCgoTraceback(pc, commitFrame, &arg) anySymbolized = true if stop { break } } } if anySymbolized { // Free symbolization state. arg.pc = 0 callCgoSymbolizer(&arg) } if stop { return } } } return n, 0 } // printAncestorTraceback prints the traceback of the given ancestor. // TODO: Unify this with gentraceback and CallersFrames. func printAncestorTraceback(ancestor ancestorInfo) { print("[originating from goroutine ", ancestor.goid, "]:\n") for fidx, pc := range ancestor.pcs { f := findfunc(pc) // f previously validated if showfuncinfo(f.srcFunc(), fidx == 0, abi.FuncIDNormal) { printAncestorTracebackFuncInfo(f, pc) } } if len(ancestor.pcs) == tracebackInnerFrames { print("...additional frames elided...\n") } // Show what created goroutine, except main goroutine (goid 1). f := findfunc(ancestor.gopc) if f.valid() && showfuncinfo(f.srcFunc(), false, abi.FuncIDNormal) && ancestor.goid != 1 { // In ancestor mode, we'll already print the goroutine ancestor. // Pass 0 for the goid parameter so we don't print it again. printcreatedby1(f, ancestor.gopc, 0) } } // printAncestorTracebackFuncInfo prints the given function info at a given pc // within an ancestor traceback. The precision of this info is reduced // due to only have access to the pcs at the time of the caller // goroutine being created. func printAncestorTracebackFuncInfo(f funcInfo, pc uintptr) { u, uf := newInlineUnwinder(f, pc) file, line := u.fileLine(uf) printFuncName(u.srcFunc(uf).name()) print("(...)\n") print("\t", file, ":", line) if pc > f.entry() { print(" +", hex(pc-f.entry())) } print("\n") } func callers(skip int, pcbuf []uintptr) int { sp := getcallersp() pc := getcallerpc() gp := getg() var n int systemstack(func() { var u unwinder u.initAt(pc, sp, 0, gp, unwindSilentErrors) n = tracebackPCs(&u, skip, pcbuf) }) return n } func gcallers(gp *g, skip int, pcbuf []uintptr) int { var u unwinder u.init(gp, unwindSilentErrors) return tracebackPCs(&u, skip, pcbuf) } // showframe reports whether the frame with the given characteristics should // be printed during a traceback. func showframe(sf srcFunc, gp *g, firstFrame bool, calleeID abi.FuncID) bool { mp := getg().m if mp.throwing >= throwTypeRuntime && gp != nil && (gp == mp.curg || gp == mp.caughtsig.ptr()) { return true } return showfuncinfo(sf, firstFrame, calleeID) } // showfuncinfo reports whether a function with the given characteristics should // be printed during a traceback. func showfuncinfo(sf srcFunc, firstFrame bool, calleeID abi.FuncID) bool { level, _, _ := gotraceback() if level > 1 { // Show all frames. return true } if sf.funcID == abi.FuncIDWrapper && elideWrapperCalling(calleeID) { return false } name := sf.name() // 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 bytealg.IndexByteString(name, '.') >= 0 && (!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. // TODO: this handles exported functions but not exported methods. func isExportedRuntime(name string) bool { const n = len("runtime.") return len(name) > n && name[:n] == "runtime." && 'A' <= name[n] && name[n] <= 'Z' } // elideWrapperCalling reports whether a wrapper function that called // function id should be elided from stack traces. func elideWrapperCalling(id abi.FuncID) bool { // If the wrapper called a panic function instead of the // wrapped function, we want to include it in stacks. return !(id == abi.FuncID_gopanic || id == abi.FuncID_sigpanic || id == abi.FuncID_panicwrap) } var gStatusStrings = [...]string{ _Gidle: "idle", _Grunnable: "runnable", _Grunning: "running", _Gsyscall: "syscall", _Gwaiting: "waiting", _Gdead: "dead", _Gcopystack: "copystack", _Gpreempted: "preempted", } func goroutineheader(gp *g) { level, _, _ := gotraceback() 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 != waitReasonZero { status = gp.waitreason.String() } // 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) if gp.m != nil && gp.m.throwing >= throwTypeRuntime && gp == gp.m.curg || level >= 2 { print(" gp=", gp) if gp.m != nil { print(" m=", gp.m.id, " mp=", gp.m) } else { print(" m=nil") } } print(" [", status) if isScan { print(" (scan)") } if waitfor >= 1 { print(", ", waitfor, " minutes") } if gp.lockedm != 0 { print(", locked to thread") } print("]:\n") } func tracebackothers(me *g) { level, _, _ := gotraceback() // Show the current goroutine first, if we haven't already. curgp := getg().m.curg if curgp != nil && curgp != me { print("\n") goroutineheader(curgp) traceback(^uintptr(0), ^uintptr(0), 0, curgp) } // We can't call locking forEachG here because this may be during fatal // throw/panic, where locking could be out-of-order or a direct // deadlock. // // Instead, use forEachGRace, which requires no locking. We don't lock // against concurrent creation of new Gs, but even with allglock we may // miss Gs created after this loop. forEachGRace(func(gp *g) { if gp == me || gp == curgp || readgstatus(gp) == _Gdead || isSystemGoroutine(gp, false) && level < 2 { return } print("\n") goroutineheader(gp) // Note: gp.m == getg().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 != getg().m && readgstatus(gp)&^_Gscan == _Grunning { print("\tgoroutine running on other thread; stack unavailable\n") printcreatedby(gp) } else { traceback(^uintptr(0), ^uintptr(0), 0, gp) } }) } // tracebackHexdump hexdumps part of stk around frame.sp and frame.fp // for debugging purposes. If the address bad is included in the // hexdumped range, it will mark it as well. func tracebackHexdump(stk stack, frame *stkframe, bad uintptr) { const expand = 32 * goarch.PtrSize const maxExpand = 256 * goarch.PtrSize // Start around frame.sp. lo, hi := frame.sp, frame.sp // Expand to include frame.fp. if frame.fp != 0 && frame.fp < lo { lo = frame.fp } if frame.fp != 0 && frame.fp > hi { hi = frame.fp } // Expand a bit more. lo, hi = lo-expand, hi+expand // But don't go too far from frame.sp. if lo < frame.sp-maxExpand { lo = frame.sp - maxExpand } if hi > frame.sp+maxExpand { hi = frame.sp + maxExpand } // And don't go outside the stack bounds. if lo < stk.lo { lo = stk.lo } if hi > stk.hi { hi = stk.hi } // Print the hex dump. print("stack: frame={sp:", hex(frame.sp), ", fp:", hex(frame.fp), "} stack=[", hex(stk.lo), ",", hex(stk.hi), ")\n") hexdumpWords(lo, hi, func(p uintptr) byte { switch p { case frame.fp: return '>' case frame.sp: return '<' case bad: return '!' } return 0 }) } // isSystemGoroutine reports whether the goroutine g must be omitted // in stack dumps and deadlock detector. This is any goroutine that // starts at a runtime.* entry point, except for runtime.main, // runtime.handleAsyncEvent (wasm only) and sometimes runtime.runfinq. // // If fixed is true, any goroutine that can vary between user and // system (that is, the finalizer goroutine) is considered a user // goroutine. func isSystemGoroutine(gp *g, fixed bool) bool { // Keep this in sync with internal/trace.IsSystemGoroutine. f := findfunc(gp.startpc) if !f.valid() { return false } if f.funcID == abi.FuncID_runtime_main || f.funcID == abi.FuncID_corostart || f.funcID == abi.FuncID_handleAsyncEvent { return false } if f.funcID == abi.FuncID_runfinq { // We include the finalizer goroutine if it's calling // back into user code. if fixed { // This goroutine can vary. In fixed mode, // always consider it a user goroutine. return false } return fingStatus.Load()&fingRunningFinalizer == 0 } return hasPrefix(funcname(f), "runtime.") } // 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. // // On all platforms, the traceback function is invoked when a call from // Go to C to Go requests a stack trace. On linux/amd64, linux/ppc64le, // linux/arm64, and freebsd/amd64, the traceback function is also invoked // when a signal is received by a thread that is executing a cgo call. // The traceback function should not make assumptions about when it is // called, as future versions of Go may make additional calls. // // 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 } // printCgoTraceback 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 } commitFrame := func() (pr, stop bool) { return true, false } var arg cgoSymbolizerArg for _, c := range callers { if c == 0 { break } printOneCgoTraceback(c, commitFrame, &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. // It returns the "stop" result of commitFrame. func printOneCgoTraceback(pc uintptr, commitFrame func() (pr, stop bool), arg *cgoSymbolizerArg) bool { arg.pc = pc for { if pr, stop := commitFrame(); stop { return true } else if !pr { continue } 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") if arg.more == 0 { return false } } } // callCgoSymbolizer calls the cgoSymbolizer function. func callCgoSymbolizer(arg *cgoSymbolizerArg) { call := cgocall if panicking.Load() > 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{})) } if asanenabled { asanwrite(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.Load() > 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)) } if asanenabled { asanwrite(unsafe.Pointer(&arg), unsafe.Sizeof(arg)) } call(cgoTraceback, noescape(unsafe.Pointer(&arg))) }