[BUGFIX PATCH V2 0/3] kprobes/arm: Improve kprobes implementation on arm

On Fri, 17 Feb 2017 11:01:10 +0000
"Jon Medhurst (Tixy)" [off-list ref] wrote:

On Wed, 2017-02-15 at 09:27 +0900, Masami Hiramatsu wrote:

quoted

Hi,

Here is the 2nd version of the patches which improve kprobe
on arm implementation (a kind of bugfix). Version 1 is here;

https://lkml.org/lkml/2017/2/13/538

In this version I didn't update the code, just update the
patch description according to Tixy's comment and add his Ack.

Thank you,

---

Masami Hiramatsu (3):
      kprobes/arm: Allow to handle reentered kprobe on single-stepping
      kprobes/arm: Skip single-stepping in recursing path if possible
      kprobes/arm: Fix the return address of multiple kretprobes

Thanks for doing these. Am I correct in assuming we don't need to
consider these fixes urgent or critical? Only the first looks like it
could be serious, and the x86 fix for that is 3 years old and ARM has
gone without it all this time. So I'm guessing it's fine to wait for the
normal development process and deal with it after the about to open
merge window is completed?

Agreed. I'm not sure how frequently FIQ is used in ARM, but anyway
it happens only when root user intensively uses kprobes on FIQ handlers.

If so, I propose that I put the patches in a branch for Russell to pull
later (unless he pipes up with objections or says otherwise). Meantime
I'll investigate the kprobes test failures I see (which actually looks
like cache/TLB issues and not test code problems after all).

OK, btw, I couldn't reproduce the kprobes test failure with
CONFIG_DEBUG_RODATA=y on qemu...

BTW, I added the?ARM kernel list to the CC. I spotted you didn't add it
to you patch postings, which means people interested in ARM (other than
Russell) wouldn't have seen them.

Ah, I forgot that, Thank you!

Thanks

-- 
Tixy

-- 
Masami Hiramatsu [off-list ref]