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

Masami Hiramatsu
2017-09-19T09:58:56Z

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