runtime: don't inspect the stack for delayed signals from TSAN
Cgo TSAN (not the Go race detector) intercepts signals and calls
the signal handler at a later time. When the signal handler is
called, the memory may have changed, but the signal context
remains old. As the signal context and the memory don't match, it
is unsafe to unwind the stack from the signal PC and SP. We have
to ignore the signal.
It is probably also not safe to do async preemption, which relies
on the signal PC, and inspects and even writes to the stack (for
call injection).
We also inspect the stack for fatal signals (e.g. SIGSEGV), but I
think they are not delayed. For other signals we don't inspect
the stack, so they are probably fine.
Fixes #27540.
Change-Id: I5c80a7512265b8ea4a91422954dbff32c6c3a0d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/408218
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com> Reviewed-by: Michael Pratt <mpratt@google.com>