linux-kernel - [PATCH -tip v3 0/7] kprobes/x86: Preempt related enhancements

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Date:   Tue, 19 Sep 2017 18:58:17 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>, mingo@...hat.com
Cc:     x86@...nel.org, Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Alexei Starovoitov <ast@...com>
Subject: [PATCH -tip v3 0/7] kprobes/x86: Preempt related enhancements

Hi,

Here is the 3rd version of the series to improve preempt
related behavior in kprobes/x86. This actually includes
many enhancements/fixes from the 2nd version, which is

https://lkml.org/lkml/2017/9/11/482

With the previous patch, lkp-bot reported that an issue
( https://lkml.org/lkml/2017/9/14/3 ) and I couldn't
reproduce it. However, I found a suspicious bug and fixed
it ([2/7]).

Also, while I was checking the correct condition for 
*probe handlers in Documentation/kprobes.txt, I also
found that current implementations for ftrace-based kprobe
and optprobe were mis-reading the document.
>>From the document, handlers must be run with preempt-
disabled, but interrupt disabling is not guaranteed.
So in the middle of this series, patches ([4/7],[5/7],
[6/7]) adding preempt-disabling and removing irq-disabling.

And at last, I placed the original patch (Enable optprobe
with CONFIG_PREEMPT).

The others are just for making sure this fix works well.
- [1/7] is just adding preemptible checker in kprobe
  smake tests so that we can easily find mistake.
- [3/7] is adding an assert if user tries to change
  execution path in optprobe, which is obviously
  prohibited in the document (there also be how to
  avoid it.)

Thank you,

---

Masami Hiramatsu (7):
      kprobes: Improve smoke test to check preemptible
      kprobes/x86: Move get_kprobe_ctlblk in irq-disabled block
      kprobes: Warn if optprobe handler tries to change execution path
      kprobes/x86: Disable preempt in optprobe
      kprobes/x86: Disable preempt ftrace-based jprobe
      kprobes/x86: Remove disable_irq from ftrace-based/optimized kprobe
      kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT


 arch/Kconfig                     |    2 +-
 arch/x86/kernel/kprobes/ftrace.c |   32 ++++++++++++++++----------------
 arch/x86/kernel/kprobes/opt.c    |    8 +++-----
 kernel/kprobes.c                 |   23 +++++++++++++++++------
 kernel/test_kprobes.c            |   20 ++++++++++++++++++++
 5 files changed, 57 insertions(+), 28 deletions(-)

--
Masami Hiramatsu