From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Timo Juhani Lindfors <timo.lindfors@iki.fi>,
yrl.pp-manager.tt@hitachi.com,
Steven Rostedt <rostedt@goodmis.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH -tip v2 2/2] [BUGFIX] kprobes/x86: Check Interrupt Flag modifier when registering probe
Date: Fri, 15 Mar 2013 10:10:41 +0530 [thread overview]
Message-ID: <20130315044041.GC31866@in.ibm.com> (raw)
In-Reply-To: <20130314115242.19690.33573.stgit@mhiramat-M0-7522>
On Thu, Mar 14, 2013 at 08:52:43PM +0900, Masami Hiramatsu wrote:
> Currently kprobes check whether the copied instruction modifies
> IF (interrupt flag) on each probe hit. This means not only
> introducing overhead but also involving inat_get_opcode_attribute
> into kprobes hot path, and it can cause an infinit recursive
> call (and kernel panic in the end).
>
> Actually, since the copied instruction itself never be modified
> on the buffer, it is needless to analyze the instruction every
> probe hit.
>
> To fix this issue, we checks it only once when registering probe
> and store the result on ainsn->if_modifier.
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Reported-by: Timo Juhani Lindfors <timo.lindfors@iki.fi>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
next prev parent reply other threads:[~2013-03-15 4:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-14 11:52 [PATCH -tip v2 1/2] [BUGFIX] kprobes: make hash_64() as always inlined Masami Hiramatsu
2013-03-14 11:52 ` [PATCH -tip v2 2/2] [BUGFIX] kprobes/x86: Check Interrupt Flag modifier when registering probe Masami Hiramatsu
2013-03-15 4:40 ` Ananth N Mavinakayanahalli [this message]
2013-03-18 11:11 ` [tip:perf/urgent] " tip-bot for Masami Hiramatsu
2013-03-15 4:40 ` [PATCH -tip v2 1/2] [BUGFIX] kprobes: make hash_64() as always inlined Ananth N Mavinakayanahalli
2013-03-18 11:10 ` [tip:perf/urgent] kprobes: Make " tip-bot for Masami Hiramatsu
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