// 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 (
	
	
	
	
	
)

// 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

	// cache is used to cache pcvalue lookups.
	cache pcvalueCache
}

// 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 ( *unwinder) ( *g,  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.
	.initAt(^uintptr(0), ^uintptr(0), ^uintptr(0), , )
}

func ( *unwinder) (, ,  uintptr,  *g,  unwindFlags) {
	// Don't call this "g"; it's too easy get "g" and "gp" confused.
	if  := getg();  ==  &&  == .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  == ^uintptr(0) &&  == ^uintptr(0) { // Signal to fetch saved values from gp.
		if .syscallsp != 0 {
			 = .syscallpc
			 = .syscallsp
			if usesLR {
				 = 0
			}
		} else {
			 = .sched.pc
			 = .sched.sp
			if usesLR {
				 = .sched.lr
			}
		}
	}

	var  stkframe
	.pc = 
	.sp = 
	if usesLR {
		.lr = 
	}

	// If the PC is zero, it's likely a nil function call.
	// Start in the caller's frame.
	if .pc == 0 {
		if usesLR {
			.pc = *(*uintptr)(unsafe.Pointer(.sp))
			.lr = 0
		} else {
			.pc = uintptr(*(*uintptr)(unsafe.Pointer(.sp)))
			.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" && .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.
		.pc = .lr
		.lr = 0
	}

	 := findfunc(.pc)
	if !.valid() {
		if &unwindSilentErrors == 0 {
			print("runtime: g ", .goid, ": unknown pc ", hex(.pc), "\n")
			tracebackHexdump(.stack, &, 0)
		}
		if &(unwindPrintErrors|unwindSilentErrors) == 0 {
			throw("unknown pc")
		}
		* = unwinder{}
		return
	}
	.fn = 

	// Populate the unwinder.
	* = unwinder{
		frame:        ,
		g:            .guintptr(),
		cgoCtxt:      len(.cgoCtxt) - 1,
		calleeFuncID: abi.FuncIDNormal,
		flags:        ,
	}

	 := .pc ==  && .sp ==  &&  == .syscallpc &&  == .syscallsp
	.resolveInternal(true, )
}

func ( *unwinder) () bool {
	return .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 ( *unwinder) (,  bool) {
	 := &.frame
	 := .g.ptr()

	 := .fn
	if .pcsp == 0 {
		// No frame information, must be external function, like race support.
		// See golang.org/issue/13568.
		.finishInternal()
		return
	}

	// Compute function info flags.
	 := .flag
	if .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.
		 &^= abi.FuncFlagSPWrite
	}
	if  {
		// 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.
		 &^= abi.FuncFlagSPWrite
	}

	// Found an actual function.
	// Derive frame pointer.
	if .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 .flags&unwindJumpStack != 0 &&  == .m.g0 && .m.curg != nil && .m.curg.m == .m {
			switch .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.
				 = .m.curg
				.g.set()
				.pc = .sched.pc
				.fn = findfunc(.pc)
				 = .fn
				 = .flag
				.lr = .sched.lr
				.sp = .sched.sp
				.cgoCtxt = len(.cgoCtxt) - 1
			case abi.FuncID_systemstack:
				// systemstack returns normally, so just follow the
				// stack transition.
				if usesLR && funcspdelta(, .pc, &.cache) == 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.
					 &^= abi.FuncFlagSPWrite
					break
				}
				 = .m.curg
				.g.set()
				.sp = .sched.sp
				.cgoCtxt = len(.cgoCtxt) - 1
				 &^= abi.FuncFlagSPWrite
			}
		}
		.fp = .sp + uintptr(funcspdelta(, .pc, &.cache))
		if !usesLR {
			// On x86, call instruction pushes return PC before entering new function.
			.fp += goarch.PtrSize
		}
	}

	// Derive link register.
	if &abi.FuncFlagTopFrame != 0 {
		// This function marks the top of the stack. Stop the traceback.
		.lr = 0
	} else if &abi.FuncFlagSPWrite != 0 && (! || .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   F  | frame.lr = 0; print
		//  F   T   T  | frame.lr = 0
		//  F   F   F  | print; panic
		//  F   F   T  | ignore SPWrite
		if .flags&unwindSilentErrors == 0 && ! {
			println("traceback: unexpected SPWRITE function", funcname())
			if .flags&unwindPrintErrors == 0 {
				throw("traceback")
			}
		}
		.lr = 0
	} else {
		var  uintptr
		if usesLR {
			if  && .sp < .fp || .lr == 0 {
				 = .sp
				.lr = *(*uintptr)(unsafe.Pointer())
			}
		} else {
			if .lr == 0 {
				 = .fp - goarch.PtrSize
				.lr = *(*uintptr)(unsafe.Pointer())
			}
		}
	}

	.varp = .fp
	if !usesLR {
		// On x86, call instruction pushes return PC before entering new function.
		.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 .varp > .sp && framepointer_enabled {
		.varp -= goarch.PtrSize
	}

	.argp = .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.
	.continpc = .pc
	if .calleeFuncID == abi.FuncID_sigpanic {
		if .fn.deferreturn != 0 {
			.continpc = .fn.entry() + uintptr(.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 {
			.continpc = 0
		}
	}
}

func ( *unwinder) () {
	 := &.frame
	 := .fn
	 := .g.ptr()

	// Do not unwind past the bottom of the stack.
	if .lr == 0 {
		.finishInternal()
		return
	}
	 := findfunc(.lr)
	if !.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.
		 := .flags&(unwindPrintErrors|unwindSilentErrors) == 0
		 := .flags&unwindSilentErrors == 0
		if  && .m.incgo && .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.
			 = false
		}
		if  ||  {
			print("runtime: g ", .goid, ": unexpected return pc for ", funcname(), " called from ", hex(.lr), "\n")
			tracebackHexdump(.stack, , 0)
		}
		if  {
			throw("unknown caller pc")
		}
		.lr = 0
		.finishInternal()
		return
	}

	if .pc == .lr && .sp == .fp {
		// If the next frame is identical to the current frame, we cannot make progress.
		print("runtime: traceback stuck. pc=", hex(.pc), " sp=", hex(.sp), "\n")
		tracebackHexdump(.stack, , .sp)
		throw("traceback stuck")
	}

	 := .funcID == abi.FuncID_sigpanic || .funcID == abi.FuncID_asyncPreempt || .funcID == abi.FuncID_debugCallV2
	if  {
		.flags |= unwindTrap
	} else {
		.flags &^= unwindTrap
	}

	// Unwind to next frame.
	.calleeFuncID = .funcID
	.fn = 
	.pc = .lr
	.lr = 0
	.sp = .fp
	.fp = 0

	// On link register architectures, sighandler saves the LR on stack
	// before faking a call.
	if usesLR &&  {
		 := *(*uintptr)(unsafe.Pointer(.sp))
		.sp += alignUp(sys.MinFrameSize, sys.StackAlign)
		 = findfunc(.pc)
		.fn = 
		if !.valid() {
			.pc = 
		} else if funcspdelta(, .pc, &.cache) == 0 {
			.lr = 
		}
	}

	.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 ( *unwinder) () {
	.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.
	 := .g.ptr()
	if .flags&(unwindPrintErrors|unwindSilentErrors) == 0 && .frame.sp != .stktopsp {
		print("runtime: g", .goid, ": frame.sp=", hex(.frame.sp), " top=", hex(.stktopsp), "\n")
		print("\tstack=[", hex(.stack.lo), "-", hex(.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 ( *unwinder) () uintptr {
	if .flags&unwindTrap == 0 && .frame.pc > .frame.fn.entry() {
		// Regular call.
		return .frame.pc - 1
	}
	// Trapping instruction or we're at the function entry point.
	return .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 ( *unwinder) ( []uintptr) int {
	if cgoTraceback == nil || .frame.fn.funcID != abi.FuncID_cgocallback || .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
	}

	 := .g.ptr().cgoCtxt[.cgoCtxt]
	.cgoCtxt--
	cgoContextPCs(, )
	for ,  := range  {
		if  == 0 {
			return 
		}
	}
	return len()
}

// 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 ( *unwinder,  int,  []uintptr) int {
	var  [32]uintptr
	 := 0
	for ;  < len() && .valid(); .next() {
		 := .frame.fn
		 := .cgoCallers([:])

		// TODO: Why does &u.cache cause u to escape? (Same in traceback2)
		for ,  := newInlineUnwinder(, .symPC(), noEscapePtr(&.cache));  < len() && .valid();  = .next() {
			 := .srcFunc()
			if .funcID == abi.FuncIDWrapper && elideWrapperCalling(.calleeFuncID) {
				// ignore wrappers
			} else if  > 0 {
				--
			} 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.
				[] = .pc + 1
				++
			}
			.calleeFuncID = .funcID
		}
		// Add cgo frames (if we're done skipping over the requested number of
		// Go frames).
		if  == 0 {
			 += copy([:], [:])
		}
	}
	return 
}

// printArgs prints function arguments in traceback.
func ( funcInfo,  unsafe.Pointer,  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 (
		         = 0xff
		       = 0xfe
		         = 0xfd
		      = 0xfc
		 = 0xfb
	)

	const (
		    = 10                       // print no more than 10 args/components
		 = 5                        // no more than 5 layers of nesting
		   = (*3+2)* + 1 // max length of _FUNCDATA_ArgInfo (see the compiler side for reasoning)
	)

	 := (*[]uint8)(funcdata(, abi.FUNCDATA_ArgInfo))
	if  == nil {
		return
	}

	 := funcdata(, abi.FUNCDATA_ArgLiveInfo)
	 := pcdatavalue(, abi.PCDATA_ArgLiveIndex, , nil)
	 := uint8(0xff) // smallest offset that needs liveness info (slots with a lower offset is always live)
	if  != nil {
		 = *(*uint8)()
	}

	 := func(,  uint8) bool {
		if  == nil ||  <= 0 {
			return true // no liveness info, always live
		}
		if  <  {
			return true
		}
		 := *(*uint8)(add(, uintptr()+uintptr(/8)))
		return &(1<<(%8)) != 0
	}

	 := func(, ,  uint8) {
		 := readUnaligned64(add(, uintptr()))
		// mask out irrelevant bits
		if  < 8 {
			 := 64 - *8
			if goarch.BigEndian {
				 =  >> 
			} else {
				 =  <<  >> 
			}
		}
		print(hex())
		if !(, ) {
			print("?")
		}
	}

	 := true
	 := func() {
		if ! {
			print(", ")
		}
	}
	 := 0
	 := uint8(0) // register arg spill slot index
:
	for {
		 := []
		++
		switch  {
		case :
			break 
		case :
			()
			print("{")
			 = true
			continue
		case :
			print("}")
		case :
			()
			print("...")
		case :
			()
			print("_")
		default:
			()
			 := []
			++
			(, , )
			if  >=  {
				++
			}
		}
		 = 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 ( string) (string, string, string) {
	// Replace the shape name in generic function with "...".
	 := bytealg.IndexByteString(, '[')
	if  < 0 {
		return , "", ""
	}
	 := len() - 1
	for [] != ']' {
		--
	}
	if  <=  {
		return , "", ""
	}
	return [:], "[...]", [+1:]
}

// funcNameForPrint returns the function name for printing to the user.
func ( string) string {
	, ,  := funcNamePiecesForPrint()
	return  +  + 
}

// printFuncName prints a function name. name is the function name in
// the binary's func data table.
func ( string) {
	if  == "runtime.gopanic" {
		print("panic")
		return
	}
	, ,  := funcNamePiecesForPrint()
	print(, , )
}

func ( *g) {
	// Show what created goroutine, except main goroutine (goid 1).
	 := .gopc
	 := findfunc()
	if .valid() && showframe(.srcFunc(), , false, abi.FuncIDNormal) && .goid != 1 {
		printcreatedby1(, , .parentGoid)
	}
}

func ( funcInfo,  uintptr,  uint64) {
	print("created by ")
	printFuncName(funcname())
	if  != 0 {
		print(" in goroutine ", )
	}
	print("\n")
	 :=  // back up to CALL instruction for funcline.
	if  > .entry() {
		 -= sys.PCQuantum
	}
	,  := funcline(, )
	print("\t", , ":", )
	if  > .entry() {
		print(" +", hex(-.entry()))
	}
	print("\n")
}

func (, ,  uintptr,  *g) {
	traceback1(, , , , 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 (, ,  uintptr,  *g) {
	if .m.libcallsp != 0 {
		// We're in C code somewhere, traceback from the saved position.
		traceback1(.m.libcallpc, .m.libcallsp, 0, .m.libcallg.ptr(), 0)
		return
	}
	traceback1(, , , , unwindTrap)
}

func (, ,  uintptr,  *g,  unwindFlags) {
	// If the goroutine is in cgo, and we have a cgo traceback, print that.
	if iscgo && .m != nil && .m.ncgo > 0 && .syscallsp != 0 && .m.cgoCallers != nil && .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.
		.m.cgoCallersUse.Store(1)
		 := *.m.cgoCallers
		.m.cgoCallers[0] = 0
		.m.cgoCallersUse.Store(0)

		printCgoTraceback(&)
	}

	if readgstatus()&^_Gscan == _Gsyscall {
		// Override registers if blocked in system call.
		 = .syscallpc
		 = .syscallsp
		 &^= unwindTrap
	}
	if .m != nil && .m.vdsoSP != 0 {
		// Override registers if running in VDSO. This comes after the
		// _Gsyscall check to cover VDSO calls after entersyscall.
		 = .m.vdsoPC
		 = .m.vdsoSP
		 &^= 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.
	 |= unwindPrintErrors
	var  unwinder
	 := func( bool) int {
		const  int = 0x7fffffff
		.initAt(, , , , )
		,  := traceback2(&, , 0, tracebackInnerFrames)
		if  < tracebackInnerFrames {
			// We printed the whole stack.
			return 
		}
		// 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.
		 := 
		,  := traceback2(&, , , 0)
		 :=  -  - tracebackOuterFrames
		if  > 0 {
			print("...", , " frames elided...\n")
			traceback2(&, , +, tracebackOuterFrames)
		} else if  <= 0 {
			// There are tracebackOuterFrames or fewer frames left to print.
			// Just print the rest of the stack.
			traceback2(&, , , tracebackOuterFrames)
		}
		return 
	}
	// By default, omits runtime frames. If that means we print nothing at all,
	// repeat forcing all frames printed.
	if (false) == 0 {
		(true)
	}
	printcreatedby()

	if .ancestors == nil {
		return
	}
	for ,  := range *.ancestors {
		printAncestorTraceback()
	}
}

// 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 ( *unwinder,  bool, ,  int) (,  int) {
	// commitFrame commits to a logical frame and returns whether this frame
	// should be printed and whether iteration should stop.
	 := func() (,  bool) {
		if  == 0 &&  == 0 {
			// Stop
			return false, true
		}
		++
		++
		if  > 0 {
			// Skip
			--
			return false, false
		}
		// Print
		--
		return true, false
	}

	 := .g.ptr()
	, ,  := gotraceback()
	var  [32]uintptr
	for ; .valid(); .next() {
		 = 0
		 := .frame.fn
		for ,  := newInlineUnwinder(, .symPC(), noEscapePtr(&.cache)); .valid();  = .next() {
			 := .srcFunc()
			 := .calleeFuncID
			.calleeFuncID = .funcID
			if !( || showframe(, ,  == 0, )) {
				continue
			}

			if ,  := ();  {
				return
			} else if ! {
				continue
			}

			 := .name()
			,  := .fileLine()
			// Print during crash.
			//	main(0x1, 0x2, 0x3)
			//		/home/rsc/go/src/runtime/x.go:23 +0xf
			//
			printFuncName()
			print("(")
			if .isInlined() {
				print("...")
			} else {
				 := unsafe.Pointer(.frame.argp)
				printArgs(, , .symPC())
			}
			print(")\n")
			print("\t", , ":", )
			if !.isInlined() {
				if .frame.pc > .entry() {
					print(" +", hex(.frame.pc-.entry()))
				}
				if .m != nil && .m.throwing >= throwTypeRuntime &&  == .m.curg ||  >= 2 {
					print(" fp=", hex(.frame.fp), " sp=", hex(.frame.sp), " pc=", hex(.frame.pc))
				}
			}
			print("\n")
		}

		// Print cgo frames.
		if  := .cgoCallers([:]);  > 0 {
			var  cgoSymbolizerArg
			 := false
			 := false
			for ,  := range [:] {
				if cgoSymbolizer == nil {
					if ,  := ();  {
						break
					} else if  {
						print("non-Go function at pc=", hex(), "\n")
					}
				} else {
					 = printOneCgoTraceback(, , &)
					 = true
					if  {
						break
					}
				}
			}
			if  {
				// Free symbolization state.
				.pc = 0
				callCgoSymbolizer(&)
			}
			if  {
				return
			}
		}
	}
	return , 0
}

// printAncestorTraceback prints the traceback of the given ancestor.
// TODO: Unify this with gentraceback and CallersFrames.
func ( ancestorInfo) {
	print("[originating from goroutine ", .goid, "]:\n")
	for ,  := range .pcs {
		 := findfunc() // f previously validated
		if showfuncinfo(.srcFunc(),  == 0, abi.FuncIDNormal) {
			printAncestorTracebackFuncInfo(, )
		}
	}
	if len(.pcs) == tracebackInnerFrames {
		print("...additional frames elided...\n")
	}
	// Show what created goroutine, except main goroutine (goid 1).
	 := findfunc(.gopc)
	if .valid() && showfuncinfo(.srcFunc(), false, abi.FuncIDNormal) && .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(, .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 ( funcInfo,  uintptr) {
	,  := newInlineUnwinder(, , nil)
	,  := .fileLine()
	printFuncName(.srcFunc().name())
	print("(...)\n")
	print("\t", , ":", )
	if  > .entry() {
		print(" +", hex(-.entry()))
	}
	print("\n")
}

func ( int,  []uintptr) int {
	 := getcallersp()
	 := getcallerpc()
	 := getg()
	var  int
	systemstack(func() {
		var  unwinder
		.initAt(, , 0, , unwindSilentErrors)
		 = tracebackPCs(&, , )
	})
	return 
}

func ( *g,  int,  []uintptr) int {
	var  unwinder
	.init(, unwindSilentErrors)
	return tracebackPCs(&, , )
}

// showframe reports whether the frame with the given characteristics should
// be printed during a traceback.
func ( srcFunc,  *g,  bool,  abi.FuncID) bool {
	 := getg().m
	if .throwing >= throwTypeRuntime &&  != nil && ( == .curg ||  == .caughtsig.ptr()) {
		return true
	}
	return showfuncinfo(, , )
}

// showfuncinfo reports whether a function with the given characteristics should
// be printed during a traceback.
func ( srcFunc,  bool,  abi.FuncID) bool {
	, ,  := gotraceback()
	if  > 1 {
		// Show all frames.
		return true
	}

	if .funcID == abi.FuncIDWrapper && elideWrapperCalling() {
		return false
	}

	 := .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  == "runtime.gopanic" && ! {
		return true
	}

	return bytealg.IndexByteString(, '.') >= 0 && (!hasPrefix(, "runtime.") || isExportedRuntime())
}

// 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 ( string) bool {
	const  = len("runtime.")
	return len() >  && [:] == "runtime." && 'A' <= [] && [] <= 'Z'
}

// elideWrapperCalling reports whether a wrapper function that called
// function id should be elided from stack traces.
func ( abi.FuncID) bool {
	// If the wrapper called a panic function instead of the
	// wrapped function, we want to include it in stacks.
	return !( == abi.FuncID_gopanic ||  == abi.FuncID_sigpanic ||  == abi.FuncID_panicwrap)
}

var gStatusStrings = [...]string{
	_Gidle:      "idle",
	_Grunnable:  "runnable",
	_Grunning:   "running",
	_Gsyscall:   "syscall",
	_Gwaiting:   "waiting",
	_Gdead:      "dead",
	_Gcopystack: "copystack",
	_Gpreempted: "preempted",
}

func ( *g) {
	 := readgstatus()

	 := &_Gscan != 0
	 &^= _Gscan // drop the scan bit

	// Basic string status
	var  string
	if 0 <=  &&  < uint32(len(gStatusStrings)) {
		 = gStatusStrings[]
	} else {
		 = "???"
	}

	// Override.
	if  == _Gwaiting && .waitreason != waitReasonZero {
		 = .waitreason.String()
	}

	// approx time the G is blocked, in minutes
	var  int64
	if ( == _Gwaiting ||  == _Gsyscall) && .waitsince != 0 {
		 = (nanotime() - .waitsince) / 60e9
	}
	print("goroutine ", .goid, " [", )
	if  {
		print(" (scan)")
	}
	if  >= 1 {
		print(", ", , " minutes")
	}
	if .lockedm != 0 {
		print(", locked to thread")
	}
	print("]:\n")
}

func ( *g) {
	, ,  := gotraceback()

	// Show the current goroutine first, if we haven't already.
	 := getg().m.curg
	if  != nil &&  !=  {
		print("\n")
		goroutineheader()
		traceback(^uintptr(0), ^uintptr(0), 0, )
	}

	// 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( *g) {
		if  ==  ||  ==  || readgstatus() == _Gdead || isSystemGoroutine(, false) &&  < 2 {
			return
		}
		print("\n")
		goroutineheader()
		// 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 .m != getg().m && readgstatus()&^_Gscan == _Grunning {
			print("\tgoroutine running on other thread; stack unavailable\n")
			printcreatedby()
		} else {
			traceback(^uintptr(0), ^uintptr(0), 0, )
		}
	})
}

// 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 ( stack,  *stkframe,  uintptr) {
	const  = 32 * goarch.PtrSize
	const  = 256 * goarch.PtrSize
	// Start around frame.sp.
	,  := .sp, .sp
	// Expand to include frame.fp.
	if .fp != 0 && .fp <  {
		 = .fp
	}
	if .fp != 0 && .fp >  {
		 = .fp
	}
	// Expand a bit more.
	,  = -, +
	// But don't go too far from frame.sp.
	if  < .sp- {
		 = .sp - 
	}
	if  > .sp+ {
		 = .sp + 
	}
	// And don't go outside the stack bounds.
	if  < .lo {
		 = .lo
	}
	if  > .hi {
		 = .hi
	}

	// Print the hex dump.
	print("stack: frame={sp:", hex(.sp), ", fp:", hex(.fp), "} stack=[", hex(.lo), ",", hex(.hi), ")\n")
	hexdumpWords(, , func( uintptr) byte {
		switch  {
		case .fp:
			return '>'
		case .sp:
			return '<'
		case :
			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 ( *g,  bool) bool {
	// Keep this in sync with internal/trace.IsSystemGoroutine.
	 := findfunc(.startpc)
	if !.valid() {
		return false
	}
	if .funcID == abi.FuncID_runtime_main || .funcID == abi.FuncID_handleAsyncEvent {
		return false
	}
	if .funcID == abi.FuncID_runfinq {
		// We include the finalizer goroutine if it's calling
		// back into user code.
		if  {
			// This goroutine can vary. In fixed mode,
			// always consider it a user goroutine.
			return false
		}
		return fingStatus.Load()&fingRunningFinalizer == 0
	}
	return hasPrefix(funcname(), "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 ( int, , ,  unsafe.Pointer) {
	if  != 0 {
		panic("unsupported version")
	}

	if cgoTraceback != nil && cgoTraceback !=  ||
		cgoContext != nil && cgoContext !=  ||
		cgoSymbolizer != nil && cgoSymbolizer !=  {
		panic("call SetCgoTraceback only once")
	}

	cgoTraceback = 
	cgoContext = 
	cgoSymbolizer = 

	// 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, )
	}
}

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 ( *cgoCallers) {
	if cgoSymbolizer == nil {
		for ,  := range  {
			if  == 0 {
				break
			}
			print("non-Go function at pc=", hex(), "\n")
		}
		return
	}

	 := func() (,  bool) { return true, false }
	var  cgoSymbolizerArg
	for ,  := range  {
		if  == 0 {
			break
		}
		printOneCgoTraceback(, , &)
	}
	.pc = 0
	callCgoSymbolizer(&)
}

// 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 ( uintptr,  func() (,  bool),  *cgoSymbolizerArg) bool {
	.pc = 
	for {
		if ,  := ();  {
			return true
		} else if ! {
			continue
		}

		callCgoSymbolizer()
		if .funcName != nil {
			// Note that we don't print any argument
			// information here, not even parentheses.
			// The symbolizer must add that if appropriate.
			println(gostringnocopy(.funcName))
		} else {
			println("non-Go function")
		}
		print("\t")
		if .file != nil {
			print(gostringnocopy(.file), ":", .lineno, " ")
		}
		print("pc=", hex(), "\n")
		if .more == 0 {
			return false
		}
	}
}

// callCgoSymbolizer calls the cgoSymbolizer function.
func ( *cgoSymbolizerArg) {
	 := 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.
		 = asmcgocall
	}
	if msanenabled {
		msanwrite(unsafe.Pointer(), unsafe.Sizeof(cgoSymbolizerArg{}))
	}
	if asanenabled {
		asanwrite(unsafe.Pointer(), unsafe.Sizeof(cgoSymbolizerArg{}))
	}
	(cgoSymbolizer, noescape(unsafe.Pointer()))
}

// cgoContextPCs gets the PC values from a cgo traceback.
func ( uintptr,  []uintptr) {
	if cgoTraceback == nil {
		return
	}
	 := 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.
		 = asmcgocall
	}
	 := cgoTracebackArg{
		context: ,
		buf:     (*uintptr)(noescape(unsafe.Pointer(&[0]))),
		max:     uintptr(len()),
	}
	if msanenabled {
		msanwrite(unsafe.Pointer(&), unsafe.Sizeof())
	}
	if asanenabled {
		asanwrite(unsafe.Pointer(&), unsafe.Sizeof())
	}
	(cgoTraceback, noescape(unsafe.Pointer(&)))
}