From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/5] powerpc/kprobes: Do not suppress instruction emulation if a single run failed
Date: Thu, 14 Sep 2017 15:33:04 +0530 [thread overview]
Message-ID: <20170914100304.loobdbpt6swg4t4m@naverao1-tp.localdomain> (raw)
In-Reply-To: <20170914024527.c5e52b918372e00061371014@kernel.org>
On 2017/09/14 02:45AM, Masami Hiramatsu wrote:
> On Thu, 14 Sep 2017 12:08:07 +0530
> "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
>
> > On 2017/09/13 04:53PM, Masami Hiramatsu wrote:
> > > On Thu, 14 Sep 2017 02:50:33 +0530
> > > "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> > >
> > > > Currently, we disable instruction emulation if emulate_step() fails for
> > > > any reason. However, such failures could be transient and specific to a
> > > > particular run. Instead, only disable instruction emulation if we have
> > > > never been able to emulate this. If we had emulated this instruction
> > > > successfully at least once, then we single step only this probe hit and
> > > > continue to try emulating the instruction in subsequent probe hits.
> > >
> > > Hmm, would this mean that the instruction is emulatable or not depends
> > > on context? What kind of situation is considerable?
> >
> > Yes, as an example, a load/store instruction can cause exceptions
> > depending on the address. In some of those cases, we will have to single
> > step the instruction, but we will be able to emulate in most scenarios.
>
> OK, I got it.
> Could you add this example as comment in the code so that readers can
> easily understand?
Sure.
Thanks,
Naveen
next prev parent reply other threads:[~2017-09-14 10:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-13 21:20 [PATCH 1/5] powerpc/kprobes: Some cosmetic updates to try_to_emulate() Naveen N. Rao
2017-09-13 21:20 ` [PATCH 2/5] powerpc/kprobes: Do not suppress instruction emulation if a single run failed Naveen N. Rao
2017-09-13 23:53 ` Masami Hiramatsu
2017-09-14 6:38 ` Naveen N. Rao
2017-09-14 9:45 ` Masami Hiramatsu
2017-09-14 10:03 ` Naveen N. Rao [this message]
2017-09-13 21:20 ` [PATCH 3/5] powerpc/kprobes: Fix warnings from __this_cpu_read() on preempt kernels Naveen N. Rao
2017-09-14 0:36 ` Masami Hiramatsu
2017-09-14 6:47 ` Naveen N. Rao
2017-09-14 10:10 ` Masami Hiramatsu
2017-09-16 11:25 ` Naveen N. Rao
2017-09-14 9:48 ` Kamalesh Babulal
2017-09-13 21:20 ` [PATCH 4/5] powerpc/jprobes: Disable preemption when triggered through ftrace Naveen N. Rao
2017-09-14 0:05 ` Masami Hiramatsu
2017-09-14 10:25 ` Naveen N. Rao
2017-09-14 10:53 ` Masami Hiramatsu
2017-09-13 21:20 ` [PATCH 5/5] powerpc/jprobes: Validate break handler invocation as being due to a jprobe_return() Naveen N. Rao
2017-09-14 0:38 ` Masami Hiramatsu
2017-09-13 23:18 ` [PATCH 1/5] powerpc/kprobes: Some cosmetic updates to try_to_emulate() Masami Hiramatsu
2017-09-14 6:16 ` Kamalesh Babulal
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=20170914100304.loobdbpt6swg4t4m@naverao1-tp.localdomain \
--to=naveen.n.rao@linux.vnet.ibm.com \
--cc=ananth@linux.vnet.ibm.com \
--cc=kamalesh@linux.vnet.ibm.com \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mhiramat@kernel.org \
--cc=mpe@ellerman.id.au \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.