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// Copyright 2016 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.
// Traceback support for gccgo.
// The actual traceback code is written in C.
package runtime
import (
"runtime/internal/sys"
"unsafe"
)
func printcreatedby(gp *g) {
// Show what created goroutine, except main goroutine (goid 1).
pc := gp.gopc
tracepc := pc // back up to CALL instruction for funcfileline.
entry := funcentry(tracepc)
if entry != 0 && tracepc > entry {
tracepc -= sys.PCQuantum
}
function, file, line, _ := funcfileline(tracepc, -1, false)
if function != "" && showframe(function, gp, false) && gp.goid != 1 {
printcreatedby1(function, file, line, entry, pc)
}
}
func printcreatedby1(function, file string, line int, entry, pc uintptr) {
print("created by ", function, "\n")
print("\t", file, ":", line)
if entry != 0 && pc > entry {
print(" +", hex(pc-entry))
}
print("\n")
}
// tracebackg is used to collect stack traces from other goroutines.
type tracebackg struct {
gp *g
locbuf [_TracebackMaxFrames]location
c int
}
// location is a location in the program, used for backtraces.
type location struct {
pc uintptr
filename string
function string
lineno int
}
//go:noescape
//extern runtime_callers
func c_callers(skip int32, locbuf *location, max int32, keepThunks bool) int32
// callers returns a stack trace of the current goroutine.
// The gc version of callers takes []uintptr, but we take []location.
func callers(skip int, locbuf []location) int {
n := c_callers(int32(skip)+1, &locbuf[0], int32(len(locbuf)), false)
return int(n)
}
//go:noescape
//extern runtime_callersRaw
func c_callersRaw(pcs *uintptr, max int32) int32
// callersRaw returns a raw (PCs only) stack trace of the current goroutine.
func callersRaw(pcbuf []uintptr) int {
n := c_callersRaw(&pcbuf[0], int32(len(pcbuf)))
return int(n)
}
// traceback prints a traceback of the current goroutine.
// This differs from the gc version, which is given pc, sp, lr and g and
// can print a traceback of any goroutine.
func traceback(skip int32) {
var locbuf [100]location
c := c_callers(skip+1, &locbuf[0], int32(len(locbuf)), false)
gp := getg()
printtrace(locbuf[:c], gp)
printcreatedby(gp)
if gp.ancestors == nil {
return
}
for _, ancestor := range *gp.ancestors {
printAncestorTraceback(ancestor)
}
}
// printAncestorTraceback prints the traceback of the given ancestor.
func printAncestorTraceback(ancestor ancestorInfo) {
print("[originating from goroutine ", ancestor.goid, "]:\n")
for fidx, pc := range ancestor.pcs {
function, file, line, _ := funcfileline(pc, -1, false)
if showfuncinfo(function, fidx == 0) {
printAncestorTracebackFuncInfo(function, file, line, pc)
}
}
if len(ancestor.pcs) == _TracebackMaxFrames {
print("...additional frames elided...\n")
}
// Show what created goroutine, except main goroutine (goid 1).
function, file, line, _ := funcfileline(ancestor.gopc, -1, false)
if function != "" && showfuncinfo(function, false) && ancestor.goid != 1 {
printcreatedby1(function, file, line, funcentry(ancestor.gopc), ancestor.gopc)
}
}
// printAncestorTraceback 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(name, file string, line int, pc uintptr) {
if name == "runtime.gopanic" {
name = "panic"
}
print(name, "(...)\n")
print("\t", file, ":", line)
entry := funcentry(pc)
if pc > entry {
print(" +", hex(pc-entry))
}
print("\n")
}
// printtrace prints a traceback from locbuf.
func printtrace(locbuf []location, gp *g) {
nprint := 0
for i := range locbuf {
if showframe(locbuf[i].function, gp, nprint == 0) {
name := locbuf[i].function
if name == "runtime.gopanic" {
name = "panic"
}
print(name, "\n\t", locbuf[i].filename, ":", locbuf[i].lineno, "\n")
nprint++
}
}
}
// showframe returns whether to print a frame in a traceback.
// name is the function name.
func showframe(name string, gp *g, firstFrame bool) bool {
g := getg()
if g.m.throwing > 0 && gp != nil && (gp == g.m.curg || gp == g.m.caughtsig.ptr()) {
return true
}
return showfuncinfo(name, firstFrame)
}
func showfuncinfo(name string, firstFrame bool) bool {
// Gccgo can trace back through C functions called via cgo.
// We want to print those in the traceback.
// But unless GOTRACEBACK > 1 (checked below), still skip
// internal C functions and cgo-generated functions.
if name != "" && !contains(name, ".") && !hasPrefix(name, "__go_") && !hasPrefix(name, "_cgo_") {
return true
}
level, _, _ := gotraceback()
if level > 1 {
// Show all frames.
return true
}
if name == "" {
return false
}
// 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 contains(name, ".") && (!hasPrefix(name, "runtime.") || isExportedRuntime(name))
}
// isExportedRuntime reports whether name is an exported runtime function.
// It is only for runtime functions, so ASCII A-Z is fine. Here also check
// for mangled functions from runtime/<...>, which will be prefixed with
// "runtime..z2f".
func isExportedRuntime(name string) bool {
const n = len("runtime.")
if hasPrefix(name, "runtime..z2f") {
return true
}
return len(name) > n && name[:n] == "runtime." && 'A' <= name[n] && name[n] <= 'Z'
}
var gStatusStrings = [...]string{
_Gidle: "idle",
_Grunnable: "runnable",
_Grunning: "running",
_Gsyscall: "syscall",
_Gwaiting: "waiting",
_Gdead: "dead",
_Gcopystack: "copystack",
_Gexitingsyscall: "exiting syscall",
}
func goroutineheader(gp *g) {
gpstatus := readgstatus(gp)
isScan := gpstatus&_Gscan != 0
gpstatus &^= _Gscan // drop the scan bit
// Basic string status
var status string
if 0 <= gpstatus && gpstatus < uint32(len(gStatusStrings)) {
status = gStatusStrings[gpstatus]
} else {
status = "???"
}
// Override.
if gpstatus == _Gwaiting && gp.waitreason != 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, " [", status)
if isScan {
print(" (scan)")
}
if waitfor >= 1 {
print(", ", waitfor, " minutes")
}
if gp.lockedm != 0 {
print(", locked to thread")
}
print("]:\n")
}
// 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 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 {
if !gp.isSystemGoroutine {
return false
}
if fixed && gp.isFinalizerGoroutine {
// This goroutine can vary. In fixed mode,
// always consider it a user goroutine.
return false
}
return true
}
func tracebackothers(me *g) {
var tb tracebackg
tb.gp = me
// The getTraceback function will modify me's stack context.
// Preserve it in case we have been called via systemstack.
context := me.context
stackcontext := me.stackcontext
level, _, _ := gotraceback()
// Show the current goroutine first, if we haven't already.
g := getg()
gp := g.m.curg
if gp != nil && gp != me {
print("\n")
goroutineheader(gp)
gp.traceback = (uintptr)(noescape(unsafe.Pointer(&tb)))
getTraceback(me, gp)
printtrace(tb.locbuf[:tb.c], nil)
printcreatedby(gp)
}
lock(&allglock)
for _, gp := range allgs {
if gp == me || gp == g.m.curg || readgstatus(gp) == _Gdead || isSystemGoroutine(gp, false) && level < 2 {
continue
}
print("\n")
goroutineheader(gp)
// gccgo's only mechanism for doing a stack trace is
// _Unwind_Backtrace. And that only works for the
// current thread, not for other random goroutines.
// So we need to switch context to the goroutine, get
// the backtrace, and then switch back.
//
// This means that if g is running or in a syscall, we
// can't reliably print a stack trace. FIXME.
// Note: gp.m == g.m occurs when tracebackothers is
// called from a signal handler initiated during a
// systemstack call. The original G is still in the
// running state, and we want to print its stack.
if gp.m != g.m && readgstatus(gp)&^_Gscan == _Grunning {
print("\tgoroutine running on other thread; stack unavailable\n")
printcreatedby(gp)
} else if readgstatus(gp)&^_Gscan == _Gsyscall {
print("\tgoroutine in C code; stack unavailable\n")
printcreatedby(gp)
} else {
gp.traceback = (uintptr)(noescape(unsafe.Pointer(&tb)))
getTraceback(me, gp)
printtrace(tb.locbuf[:tb.c], nil)
printcreatedby(gp)
}
}
unlock(&allglock)
me.context = context
me.stackcontext = stackcontext
}