RE: [Patch 00/16 v2] Linux extended-remote fork and exec events

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

Ping..
Thanks
--Don

> -----Original Message-----
> From: gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] On Behalf Of Breazeal, Don
> Sent: Wednesday, August 20, 2014 5:29 PM
> To: gdb-patches@sourceware.org
> Subject: [Patch 00/16 v2] Linux extended-remote fork and exec events
> 
> This is an update to the patch series implementing fork events for
> extended-remote Linux targets.  Changes from the previous version:
> 
>  * Exec Events: integrated the previous patch series that implemented
> exec
>    events for extended-remote Linux targets.  The exec patches had
>    significant overlap with the fork event patch series, and it no
> longer
>    made sense to maintain them separately.
> 
>  * Exec Catchpoints: the previous exec event patch series did not
>    implement 'catch exec'.  That is included here.
> 
>  * GDBserver Extended Feature Query: patch 4 has been completely
> rewritten.
>    The previous version attempted to determine whether extended events
>    were supported by gdbserver using information only on the host.  This
>    approach was flawed and did not work at all once follow-exec was
>    introduced.  This mechanism now uses an new RSP message to determine
>    which extended events are supported prior to attempting any activity
>    that would require that support.  There is more detail in the patch
>    4 description.
> 
>  * Coding Style: fixed a number of coding style violations.
> 
>  * Line Breaks in Descriptions: formatted the patch descriptions with
> line
>    breaks in each paragraph, which might make them more accessible via
>    web pages.
> 
> Maintainers may find it useful to consider this patch series as having
> three parts:
> 
>  1) Patches 1-3: these refactor existing code without making any
>     significant functional changes (aside from some new verbose
>     messages).
> 
>  2) Patches 4-10: these implement all the fork event functionality.
> 
>  3) Patches 11-16: these implement all the exec event functionality.
> 
> Dividing it like this may help make the large size of the patch series
> more manageable.  Again, please let me know if there is anything I can
> do to make this easier to review.
> 
> Eli approved patches 10 and 15 when they were posted previously.  The
> only changes to these patches since then were those that he requested.
> 
> ====================================================================
> 
> This patch series implements fork and exec events for extended-remote
> linux targets.  Features that are enabled include:
> 
>  * follow-fork-mode
>  * detach-on-fork
>  * follow-exec-mode
>  * catch fork/vfork/exec
> 
> This work addresses PR gdb/13584, and is part of the local/remote
> debugging feature parity project
> (https://sourceware.org/gdb/wiki/LocalRemoteFeatureParity).
> 
> My final test results showed the following changes:
> 
>  * native: PASS +46
>    - this is due the addition of non-stop mode tests to
>      gdb.threads/non-ldr-exc-*.exp.
> 
>  * remote: no change
> 
>  * extended-remote: PASS: +329, FAIL: -134, KFAIL: +1,
>                     UNTESTED: +8, UNSUPPORTED: -6
> 
> Some items to note about the extended-remote results:
> 
>  - there are some extended-remote failures in
>    gdb.base/disp-step-syscall.exp that don't show up in the unmodified
>    version on the native target.  Investigation shows that these tests
>    are producing a bogus PASS result on the native target.  I did not
>    pursue this further.
> 
>  - the new non-stop tests in gdb.threads/non-ldr-exc-*.exp give an
>    UNTESTED result for extended-remote.  This is due to an RSP
>    error in non-stop mode when running to main.  I spent some time
>    investigating this and concluded that I should leave it alone for
> now,
>    for fear of having an ever-growing, never-ending project.  My plan is
>    to track this with a bug report once that is appropriate.
> 
>  - gdb.threads/thread-execl.exp gives a couple of failures related to
>    scheduler locking.  As with the previous item, after spending some
>    time on this I concluded that pursuing it further now would be
>    feature-creep, and that this should be tracked with a bug report.
> 
>  - gdb.trace/tspeed.exp got some timeout failures one time, but I
>    was unable to reproduce it.  I'm unsure whether this is significant.
> 
> I can provide test logs or .sum diffs if anybody is interested in
> specifics.
> 
> The contents of the patch series are as follows:
> 
> Patch 1: refactor native follow-fork implementation to move target-
> independent code from target-dependent file (linux-nat.c) to make it
> useful for extended-remote targets.
> 
> Patch 2: encapsulate the code used to print verbose/debug messages
> related to folow-fork into functions, and add a message in one case.
> Also make messages distinguish between fork and vfork.
> 
> Patch 3: encapsulate code that identifies and extracts extended ptrace
> events found in the Linux wait status into functions, and call them
> everywhere that the hard-coded wait status processing was used.
> 
> Patch 4: implements a mechanism for determining what extended-mode
> features gdbserver supports.  There are several issues that this
> addresses, which are detailed in the patch 4 description.  Basically,
> the patch implements a new RSP packet "qExtendedFeatures" that allows
> GDB to ask gdbserver for the list of extended features that are enabled
> prior to doing anything that would require such a feature.  In
> gdbserver, it splits checking whether the OS supports the features from
> actually enabling them, and enables them only when it is clear that
> extended mode is active.  To facilitate this the patch also extends the
> changes that Gary Benson implemented to reduce the use of #ifdef
> GDBSERVER in linux-ptrace.c
> here:
> https://support urceware.org/ml/gdb-patches/2014-07/msg00633.html.
> 
> Patch 5: implements some functions to clone the breakpoint lists in
> gdbserver.  These are needed because in gdbserver, each process
> maintains a separate breakpoint list.  When a fork occurs, the child
> process needs a copy of the parent's breakpoint list so that it can
> manage the breakpoints using existing mechanisms in gdbserver.
> 
> Patch 6: implements follow-fork, but only for 'fork', not 'vfork'.  I
> split these apart in an attempt to keep the size of the patches down to
> a reviewable size.
> 
> Patch 7: adds the architecture-specific pieces of follow-fork.  This is
> the mechanism that handles copying the debug register state from the
> parent to the child.
> 
> Patch 8: adds follow-fork for vfork.
> 
> Patch 9: adds 'catch fork' and 'catch vfork', along with some code to
> make sure that killing a process that has forked, but before the fork is
> followed, also kills the child process.
> 
> Patch 10: implements changes to the manual and the NEWS file for the
> fork event changes.
> 
> Patch 11: implements support for the extended ptrace event
> PTRACE_EVENT_EXIT, which is a prerequisite for the exec event support.
> 
> Patch 12: implements exec event support and follow-exec.
> 
> Patch 13: implements exec catchpoints.
> 
> Patch 14: suppresses some spurious warnings that were generated after an
> exec.  These warnings were caused when gdbserver attempted to check the
> version number from the r_debug structure in the new image before the
> structure had been initialized.
> 
> Patch 15: implements changed to the manual and NEWS file for the exec
> event changes.
> 
> Patch 16: changes how gdb.base/foll-exec.exp starts GDB and loads the
> program so that it will work with extended-remote.  It also extends the
> tests gdb.threads/non-ldr-exc-[1-4].exp to test in non-stop mode as well
> as in all-stop mode.
> 
> thanks
> --Don
> 
>  gdb/NEWS                                          |   18 +
>  gdb/doc/gdb.texinfo                               |   42 ++-
>  gdb/gdbserver/gdbthread.h                         |    5 +
>  gdb/gdbserver/linux-aarch64-low.c                 |   28 ++
>  gdb/gdbserver/linux-arm-low.c                     |   26 +
>  gdb/gdbserver/linux-low.c                         |  511
> +++++++++++++++++++--
>  gdb/gdbserver/linux-low.h                         |    8 +
>  gdb/gdbserver/linux-mips-low.c                    |   76 +++-
>  gdb/gdbserver/linux-x86-low.c                     |   29 ++
>  gdb/gdbserver/lynx-low.c                          |    4 +
>  gdb/gdbserver/mem-break.c                         |  104 +++++
>  gdb/gdbserver/mem-break.h                         |    6 +
>  gdb/gdbserver/nto-low.c                           |    4 +
>  gdb/gdbserver/remote-utils.c                      |   45 ++-
>  gdb/gdbserver/server.c                            |   92 ++++
>  gdb/gdbserver/server.h                            |    3 +
>  gdb/gdbserver/spu-low.c                           |    4 +
>  gdb/gdbserver/target.h                            |   33 ++
>  gdb/gdbserver/win32-low.c                         |    4 +
>  gdb/infrun.c                                      |  296 +++++++++++-
>  gdb/infrun.h                                      |    2 -
>  gdb/linux-nat.c                                   |  264 ++----------
>  gdb/nat/linux-procfs.c                            |   18 +
>  gdb/nat/linux-procfs.h                            |    4 +
>  gdb/nat/linux-ptrace.c                            |  150 +++++--
>  gdb/nat/linux-ptrace.h                            |   10 +-
>  gdb/remote.c                                      |  337 +++++++++++++-
> -
>  gdb/testsuite/gdb.base/foll-exec.exp              |   44 +--
>  gdb/testsuite/gdb.base/foll-fork.exp              |   12 +-
>  gdb/testsuite/gdb.base/foll-vfork.exp             |    8 +-
>  gdb/testsuite/gdb.threads/fork-thread-pending.exp |   23 +-
>  gdb/testsuite/gdb.threads/non-ldr-exc-1.exp       |   20 +-
>  gdb/testsuite/gdb.threads/non-ldr-exc-2.exp       |   36 ++-
>  gdb/testsuite/gdb.threads/non-ldr-exc-3.exp       |   36 ++-
>  gdb/testsuite/gdb.threads/non-ldr-exc-4.exp       |   20 +-
>  35 files changed, 1891 insertions(+), 431 deletions(-)