3dd221a94d
Introduce a new m.incgocallback field that is true while C code calls
into Go code. Use it in the tracer in order to fallback to the default
unwinder instead of frame pointer unwinding for this scenario. The
existing fields (incgo, ncgo) were not sufficient to detect the case
where a thread created in C calls into Go code.
Motivation:
1. Take advantage of a cgo symbolizer, if registered, to unwind through
C stacks without frame pointers.
2. Reduce the chance of crashes. It seems unsafe to follow frame
pointers when there could be C code that was compiled without frame
pointers.
Removing the curgp.m.incgocallback check in traceStackID shows the
following minor differences between frame pointer unwinding and the
default unwinder when there is no cgo symbolizer involved.
trace_test.go:60: "goCalledFromCThread": got stack:
main.goCalledFromCThread
/src/runtime/testdata/testprogcgo/trace.go:58
_cgoexp_45c15a3efb3a_goCalledFromCThread
_cgo_gotypes.go:694
runtime.cgocallbackg1
/src/runtime/cgocall.go:318
runtime.cgocallbackg
/src/runtime/cgocall.go:236
runtime.cgocallback
/src/runtime/asm_amd64.s:998
crosscall2
/src/runtime/cgo/asm_amd64.s:30
want stack:
main.goCalledFromCThread
/src/runtime/testdata/testprogcgo/trace.go:58
_cgoexp_45c15a3efb3a_goCalledFromCThread
_cgo_gotypes.go:694
runtime.cgocallbackg1
/src/runtime/cgocall.go:318
runtime.cgocallbackg
/src/runtime/cgocall.go:236
runtime.cgocallback
/src/runtime/asm_amd64.s:998
trace_test.go:60: "goCalledFromC": got stack:
main.goCalledFromC
/src/runtime/testdata/testprogcgo/trace.go:51
_cgoexp_45c15a3efb3a_goCalledFromC
_cgo_gotypes.go:687
runtime.cgocallbackg1
/src/runtime/cgocall.go:318
runtime.cgocallbackg
/src/runtime/cgocall.go:236
runtime.cgocallback
/src/runtime/asm_amd64.s:998
crosscall2
/src/runtime/cgo/asm_amd64.s:30
runtime.asmcgocall
/src/runtime/asm_amd64.s:848
main._Cfunc_cCalledFromGo
_cgo_gotypes.go:263
main.goCalledFromGo
/src/runtime/testdata/testprogcgo/trace.go:46
main.Trace
/src/runtime/testdata/testprogcgo/trace.go:37
main.main
/src/runtime/testdata/testprogcgo/main.go:34
want stack:
main.goCalledFromC
/src/runtime/testdata/testprogcgo/trace.go:51
_cgoexp_45c15a3efb3a_goCalledFromC
_cgo_gotypes.go:687
runtime.cgocallbackg1
/src/runtime/cgocall.go:318
runtime.cgocallbackg
/src/runtime/cgocall.go:236
runtime.cgocallback
/src/runtime/asm_amd64.s:998
runtime.systemstack_switch
/src/runtime/asm_amd64.s:463
runtime.cgocall
/src/runtime/cgocall.go:168
main._Cfunc_cCalledFromGo
_cgo_gotypes.go:263
main.goCalledFromGo
/src/runtime/testdata/testprogcgo/trace.go:46
main.Trace
/src/runtime/testdata/testprogcgo/trace.go:37
main.main
/src/runtime/testdata/testprogcgo/main.go:34
For #16638
Change-Id: I95fa27a3170c5abd923afc6eadab4eae777ced31
Reviewed-on: https://go-review.googlesource.com/c/go/+/474916
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com>
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|---|---|---|
| .github | ||
| api | ||
| doc | ||
| lib/time | ||
| misc | ||
| src | ||
| test | ||
| .gitattributes | ||
| .gitignore | ||
| codereview.cfg | ||
| CONTRIBUTING.md | ||
| go.env | ||
| LICENSE | ||
| PATENTS | ||
| README.md | ||
| SECURITY.md | ||
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