commit 491c1e7e951bd6fc6ba37ef91be45ca14654eb05
author Michael Pratt <mpratt@google.com> Mon Sep 04 09:55:01 2023 -0400
committer Gopher Robot <gobot@golang.org> Wed Jan 10 19:40:13 2024 +0000
tree 6875bbba15962050144a06e22158d154cab62a8d
parent caafb50c0dd65b3f5c53a73eb5fdb6cf92462964

[release-branch.go1.21] runtime: allow update of system stack bounds on callback from C thread

[This cherry-pick combines CL 527715, CL 527775, CL 527797, and
CL 529216.]

[This is a redo of CL 525455 with the test fixed on darwin by defining
_XOPEN_SOURCE, and disabled with android, musl, and openbsd, which do
not provide getcontext.]

Since CL 495855, Ms are cached for C threads calling into Go, including
the stack bounds of the system stack.

Some C libraries (e.g., coroutine libraries) do manual stack management
and may change stacks between calls to Go on the same thread.

Changing the stack if there is more Go up the stack would be
problematic. But if the calls are completely independent there is no
particular reason for Go to care about the changing stack boundary.

Thus, this CL allows the stack bounds to change in such cases. The
primary downside here (besides additional complexity) is that normal
systems that do not manipulate the stack may not notice unintentional
stack corruption as quickly as before.

Note that callbackUpdateSystemStack is written to be usable for the
initial setup in needm as well as updating the stack in cgocallbackg.

For #62440.
For #62130.
For #63209.

Change-Id: I0fe0134f865932bbaff1fc0da377c35c013bd768
Reviewed-on: https://go-review.googlesource.com/c/go/+/527715
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
(cherry picked from commit 4f9fe6d50965020053ab80bf115f08070ce97f33)
(cherry picked from commit e8ba0579e2913f96c65b96e0696d64ff5f1599c5)
(cherry picked from commit a843991fdd079c931d4e98c0a17c9ac6dc254fe8)
(cherry picked from commit d110d7c42dd8025465153e4008ba807f1e69b359)
Reviewed-on: https://go-review.googlesource.com/c/go/+/530480
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Bypass: Michael Pratt <mpratt@google.com>