public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>, lkml <linux-kernel@vger.kernel.org>,
	systemtap <systemtap@sources.redhat.com>,
	DLE <dle-develop@lists.sourceforge.net>,
	Dieter Ries <mail@dieterries.net>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Subject: Re: [PATCH -tip 1/3] kprobes: Hide CONFIG_OPTPROBES and set if arch support optimized kprobes
Date: Sun, 14 Mar 2010 09:15:35 +0900	[thread overview]
Message-ID: <87k4tfyd08.fsf@devron.myhome.or.jp> (raw)
In-Reply-To: <20100312232208.2017.55337.stgit@localhost6.localdomain6> (Masami Hiramatsu's message of "Fri, 12 Mar 2010 18:22:09 -0500")

Masami Hiramatsu <mhiramat@redhat.com> writes:

> Hide CONFIG_OPTPROBES and set if arch support optimized kprobes, since
> this option doesn't change the behavior of kprobes, but just reduces
> the overhead.

I don't so care whether this is configurable or not, but this confuses
me now. The following seems to say it's changed, but now this comment
says it wasn't changed. The following docs was obsoleted?

Thanks.

NOTE for geeks:
The jump optimization changes the kprobe's pre_handler behavior.
Without optimization, the pre_handler can change the kernel's execution
path by changing regs->ip and returning 1.  However, when the probe
is optimized, that modification is ignored.  Thus, if you want to
tweak the kernel's execution path, you need to suppress optimization,
using one of the following techniques:
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

  parent reply	other threads:[~2010-03-14  0:15 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-12 23:22 [PATCH -tip 1/3] kprobes: Hide CONFIG_OPTPROBES and set if arch support optimized kprobes Masami Hiramatsu
2010-03-12 23:22 ` [PATCH -tip 2/3] [BUGFIX] perf probe: Fix probe_point buffer overrun Masami Hiramatsu
2010-03-13 12:26   ` [tip:perf/urgent] " tip-bot for Masami Hiramatsu
2010-03-12 23:22 ` [PATCH -tip 3/3] [BUGFIX] perf probe: Set need_dwarf if lazy matching is used Masami Hiramatsu
2010-03-13 12:26   ` [tip:perf/urgent] perf probe: Fix need_dwarf flag " tip-bot for Masami Hiramatsu
2010-03-13  7:27 ` [PATCH -tip 1/3] kprobes: Hide CONFIG_OPTPROBES and set if arch support optimized kprobes Ingo Molnar
2010-03-15 17:00   ` [PATCH -tip v3] " Masami Hiramatsu
2010-03-16 14:47     ` [tip:perf/core] kprobes: Hide CONFIG_OPTPROBES and set if arch supports " tip-bot for Masami Hiramatsu
2010-03-14  0:15 ` OGAWA Hirofumi [this message]
2010-03-14  2:05   ` [PATCH -tip 1/3] kprobes: Hide CONFIG_OPTPROBES and set if arch support " 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=87k4tfyd08.fsf@devron.myhome.or.jp \
    --to=hirofumi@mail.parknet.co.jp \
    --cc=ananth@in.ibm.com \
    --cc=dle-develop@lists.sourceforge.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mail@dieterries.net \
    --cc=mhiramat@redhat.com \
    --cc=mingo@elte.hu \
    --cc=systemtap@sources.redhat.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