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RE: [Patch 00/16 v2] Linux extended-remote fork and exec events
- From: "Breazeal, Don" <donb at codesourcery dot com>
- To: "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Thu, 4 Sep 2014 20:57:04 +0000
- Subject: RE: [Patch 00/16 v2] Linux extended-remote fork and exec events
- Authentication-results: sourceware.org; auth=none
- References: <1407434395-19089-1-git-send-email-donb at codesourcery dot com> <1408580964-27916-1-git-send-email-donb at codesourcery dot com>
> -----Original Message-----
> From: firstname.lastname@example.org [mailto:gdb-patches-
> email@example.com] On Behalf Of Breazeal, Don
> Sent: Wednesday, August 20, 2014 5:29 PM
> To: firstname.lastname@example.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
> events for extended-remote Linux targets. The exec patches had
> significant overlap with the fork event patch series, and it no
> 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
> 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
> 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
> 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
> My final test results showed the following changes:
> * native: PASS +46
> - this is due the addition of non-stop mode tests to
> * 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
> 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
> 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
> 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.
> 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(-)