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path: root/src/runtime/testdata/testprogcgo/stackswitch.c
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2023-10-26runtime: clear g0 stack bounds in dropmMichael Pratt
After CL 527715, needm uses callbackUpdateSystemStack to set the stack bounds for g0 on an M from the extra M list. Since callbackUpdateSystemStack is also used for recursive cgocallback, it does nothing if the stack is already in bounds. Currently, the stack bounds in an extra M may contain stale bounds from a previous thread that used this M and then returned it to the extra list in dropm. Typically a new thread will not have an overlapping stack with an old thread, but because the old thread has exited there is a small chance that the C memory allocator will allocate the new thread's stack partially or fully overlapping with the old thread's stack. If this occurs, then callbackUpdateSystemStack will not update the stack bounds. If in addition, the overlap is partial such that SP on cgocallback is close to the recorded stack lower bound, then Go may quickly "overflow" the stack and crash with "morestack on g0". Fix this by clearing the stack bounds in dropm, which ensures that callbackUpdateSystemStack will unconditionally update the bounds in needm. For #62440. Change-Id: Ic9e2052c2090dd679ed716d1a23a86d66cbcada7 Reviewed-on: https://go-review.googlesource.com/c/go/+/537695 Reviewed-by: Cherry Mui <cherryyz@google.com> Run-TryBot: Michael Pratt <mpratt@google.com> Auto-Submit: Michael Pratt <mpratt@google.com> TryBot-Bypass: Michael Pratt <mpratt@google.com>
2023-09-12runtime: set _XOPEN_SORUCE_EXTENDED to 1 for aixMichael Pratt
aix requires that _XOPEN_SOURCE_EXTENDED is set to a number, not simply defined. For #62440. Change-Id: Iee221d558b5ad5b8dcb874d4d9fdf94593f7d0a1 Reviewed-on: https://go-review.googlesource.com/c/go/+/527797 TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Cherry Mui <cherryyz@google.com> Auto-Submit: Michael Pratt <mpratt@google.com> Run-TryBot: Michael Pratt <mpratt@google.com>
2023-09-12runtime: set _XOPEN_SOURCE_EXTENDED for netbsdMichael Pratt
If _XOPEN_SOURCE is defined, then netbsd also requires _XOPEN_SOURCE_EXTENDED to define stack_t. For #62440. Change-Id: Ib05658c3ca7fae1f6b051566e713ce7bc7c037a0 Reviewed-on: https://go-review.googlesource.com/c/go/+/527775 Run-TryBot: Michael Pratt <mpratt@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
2023-09-12runtime: allow update of system stack bounds on callback from C threadMichael Pratt
[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. Fixes #62440. For #62130. 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>
2023-09-11Revert "runtime: allow update of system stack bounds on callback from C thread"Michael Pratt
This reverts CL 525455. The test fails to build on darwin, alpine, and android. For #62440. Change-Id: I39c6b1e16499bd61e0f166de6c6efe7a07961e62 Reviewed-on: https://go-review.googlesource.com/c/go/+/527317 Auto-Submit: Michael Pratt <mpratt@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Bryan Mills <bcmills@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
2023-09-11runtime: allow update of system stack bounds on callback from C threadMichael Pratt
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. Fixes #62440. For #62130. Change-Id: I7841b056acea1111bdae3b718345a3bd3961b4a8 Reviewed-on: https://go-review.googlesource.com/c/go/+/525455 Run-TryBot: Michael Pratt <mpratt@google.com> Reviewed-by: Ian Lance Taylor <iant@golang.org> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Cherry Mui <cherryyz@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>