From: Masami Hiramatsu <mhiramat@kernel.org>
To: "Jon Medhurst (Tixy)" <tixy@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H . Peter Anvin" <hpa@zytor.com>, Wang Nan <wangnan0@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
"David A . Long" <dave.long@linaro.org>,
Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
Subject: Re: [BUGFIX PATCH 3/3] kprobes/arm: Fix the return address of multiple kretprobes
Date: Wed, 15 Feb 2017 01:01:07 +0900 [thread overview]
Message-ID: <20170215010107.8aff7cb6f526502daf094879@kernel.org> (raw)
In-Reply-To: <1487080027.2978.8.camel@linaro.org>
On Tue, 14 Feb 2017 13:47:07 +0000
"Jon Medhurst (Tixy)" <tixy@linaro.org> wrote:
> On Tue, 2017-02-14 at 10:32 +0000, Jon Medhurst (Tixy) wrote:
> > On Tue, 2017-02-14 at 00:05 +0900, Masami Hiramatsu wrote:
> > > This is arm port of commit 737480a0d525 ("kprobes/x86:
> > > Fix the return address of multiple kretprobes").
> > >
> > > Fix the return address of subsequent kretprobes when multiple
> > > kretprobes are set on the same function.
> > >
> > > For example:
> > >
> > > # cd /sys/kernel/debug/tracing
> > > # echo "r:event1 sys_symlink" > kprobe_events
> > > # echo "r:event2 sys_symlink" >> kprobe_events
> > > # echo 1 > events/kprobes/enable
> > > # ln -s /tmp/foo /tmp/bar
> > >
> > > (without this patch)
> > >
> > > # cat trace | grep -v ^#
> > > ln-82 [000] dn.2 68.446525: event1: (kretprobe_trampoline+0x0/0x18 <- SyS_symlink)
> > > ln-82 [000] dn.2 68.447831: event2: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
> > >
> > > (with this patch)
> > >
> > > # cat trace | grep -v ^#
> > > ln-81 [000] dn.1 39.463469: event1: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
> > > ln-81 [000] dn.1 39.464701: event2: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
> > >
> > > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > > Cc: KUMANO Syuhei <kumano.prog@gmail.com>
> > > ---
> >
> > I don't fully understand this function, but I've checked that the ARM
> > version now matches the x86 version (apart from the x86 specific
> > register fixup and some comments). So, FWIW
> >
> > Acked-by: Jon Medhurst <tixy@linaro.org>
> >
> > I ran the before and after test case in the commit log on ARM and
> > verified the result is correct. I also tried running the ARM kprobe
> > tests with these 3 fixes but the tests fail. However, they also fail
> > without any of these changes, so I'll investigate that further...
>
> Bisecting the issue led me back to Linux 4.5 and commit 25362dc496ed
> ("ARM: 8501/1: mm: flip priority of CONFIG_DEBUG_RODATA")
>
> This sets CONFIG_DEBUG_RODATA to be enabled by default. If I disable
> that on 4.10-rc4, with the three patches in this series, then the ARM
> kprobes tests pass OK.
>
> I'll stick the DEBUG_RODATA issue on my todo list (it's been around for
> a year, so can probably wait a little longer).
Hmm, I'm running arm kernel on qemu, which maybe the reason why
the test case passed in my environment, since my kconfig also sets
CONFIG_DEBUG_RODATA=y.
BTW, would you see that any kprobe_events didn't work with
CONFIG_DEBUG_RODATA=y? (what the failure messages were?)
Thank you,
>
> --
> Tixy
>
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2017-02-14 16:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-13 15:02 [BUGFIX PATCH 0/3] kprobes/arm: Improve kprobes implementation on arm Masami Hiramatsu
2017-02-13 15:03 ` [BUGFIX PATCH 1/3] kprobes/arm: Allow to handle reentered kprobe on single-stepping Masami Hiramatsu
2017-02-14 10:01 ` Jon Medhurst (Tixy)
2017-02-14 15:32 ` Masami Hiramatsu
2017-02-13 15:04 ` [BUGFIX PATCH 2/3] kprobes/arm: Skip single-stepping in recursing path if possible Masami Hiramatsu
2017-02-14 10:07 ` Jon Medhurst (Tixy)
2017-02-14 15:31 ` Masami Hiramatsu
2017-02-13 15:05 ` [BUGFIX PATCH 3/3] kprobes/arm: Fix the return address of multiple kretprobes Masami Hiramatsu
2017-02-14 10:32 ` Jon Medhurst (Tixy)
2017-02-14 13:47 ` Jon Medhurst (Tixy)
2017-02-14 16:01 ` Masami Hiramatsu [this message]
2017-02-14 16:39 ` Jon Medhurst (Tixy)
2017-02-14 23:55 ` Masami Hiramatsu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170215010107.8aff7cb6f526502daf094879@kernel.org \
--to=mhiramat@kernel.org \
--cc=ananth@linux.vnet.ibm.com \
--cc=catalin.marinas@arm.com \
--cc=dave.long@linaro.org \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=sandeepa.s.prabhu@gmail.com \
--cc=tglx@linutronix.de \
--cc=tixy@linaro.org \
--cc=wangnan0@huawei.com \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).