[release-branch.go1.23] runtime: fix MutexProfile missing root frames
Fix a regression introduced in CL 598515 causing runtime.MutexProfile
stack traces to omit their root frames.
In most cases this was merely causing the `runtime.goexit` frame to go
missing. But in the case of runtime._LostContendedRuntimeLock, an empty
stack trace was being produced.
Add a test that catches this regression by checking for a stack trace
with the `runtime.goexit` frame.
Also fix a separate problem in expandFrame that could cause
out-of-bounds panics when profstackdepth is set to a value below 32.
There is no test for this fix because profstackdepth can't be changed at
runtime right now.
Fixes #69865
Change-Id: I1600fe62548ea84981df0916d25072c3ddf1ea1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/611615
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Nick Ripley <nick.ripley@datadoghq.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
(cherry picked from commit
c64ca8c6ef13723b9f25f4b5e1c7b6986b958d2e)
Reviewed-on: https://go-review.googlesource.com/c/go/+/621276
Reviewed-by: Cherry Mui <cherryyz@google.com>