RE: [PATCH 0/4] Exec events in gdbserver on Linux

["Breazeal, Don" <donb@codesourcery.com>]

Ping for maintainer comments on this patch series:
https://sourceware.org/ml/gdb-patches/2014-04/msg00037.html
https://sourceware.org/ml/gdb-patches/2014-04/msg00040.html
https://sourceware.org/ml/gdb-patches/2014-04/msg00072.html

The documentation piece was previously approved:
https://sourceware.org/ml/gdb-patches/2014-04/msg00071.html

Thanks,
--Don


> -----Original Message-----
> From: gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] On Behalf Of Breazeal, Don
> Sent: Wednesday, April 02, 2014 3:24 PM
> To: gdb-patches@sourceware.org
> Subject: [PATCH 0/4] Exec events in gdbserver on Linux
> 
> This patch implements support for exec events in gdbserver on GNU/Linux.
> This is a step towards the "follow fork/exec" item in the local/remote
> debugging feature parity project:
> (https://sourceware.org/gdb/wiki/LocalRemoteFeatureParity).  Luis had
> started work on this last year, and handed it off to me at the end of
> January.  (BTW, thanks to Luis for his advice on this, although any
> problems with this patch are entirely mine.)
> 
> Follow-exec-mode and rerun behave as expected in multiprocess mode
> (target extended-remote), where follow-exec-mode maintains the specified
> inferiors and rerun runs the last executable file to be exec'd.
> Catchpoints for exec are not implemented in this patch series, since
> this will be easier to do once fork and vfork events are also supported.
> 
> - Patch 1/4 implements support for the extended ptrace event
> PTRACE_EVENT_EXIT, which is a prerequisite for the exec event support.
> - Patch 2/4 implements the exec event support.
> - Patch 3/4 adds documentation for the new RSP "Stop Reply" message.
> - Patch 4/4 extends the tests gdb.threads/non-ldr-exc-[1-4].exp to test
> in non-stop mode as well as in all-stop mode.
> 
> There are a couple of significant aspects to this patch.  First, it uses
> the ptrace extension PTRACE_EVENT_EXIT to detect thread exit, in
> particular the exit of a thread group leader when a non-leader calls
> exec.  Use of this event was necessary due to a race condition in the
> two-thread case.  It is only used internally; exit events detected this
> way are not exposed to the user, and exit processing was changed as
> little as possible.
> 
> Second, it sends a signal to each lwp after an exec event in order to
> identify and clean up the lwp entry for the exec'ing thread.  This
> happens in the normal course of things for all-stop mode, but in non-
> stop mode gdbserver uses SIGSTOP to stop, then resume all of the non-
> leader threads to accomplish this.
> 
> More detailed explanations of these issues is included in the patch 2/4
> email.
> 
> My intent is to follow up with implementations of remote fork/vfork
> events and associated catchpoints.
> 
> --Don
> 
>  gdb/common/linux-ptrace.c                   |  45 ++++-
>  gdb/doc/gdb.texinfo                         |   6 +
>  gdb/gdbserver/linux-low.c                   | 274
> +++++++++++++++++++++++++---
>  gdb/gdbserver/linux-low.h                   |   5 +
>  gdb/gdbserver/remote-utils.c                |  28 ++-
>  gdb/remote.c                                |  27 ++-
>  gdb/testsuite/gdb.threads/non-ldr-exc-1.exp |  15 +-
> gdb/testsuite/gdb.threads/non-ldr-exc-2.exp |  15 +-
> gdb/testsuite/gdb.threads/non-ldr-exc-3.exp |  15 +-
> gdb/testsuite/gdb.threads/non-ldr-exc-4.exp |  15 +-
>  10 files changed, 395 insertions(+), 50 deletions(-)