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Message-ID: <1338993986.13348.549.camel@gandalf.stny.rr.com>
Subject: Re: [PATCH -tip v2 3/9] ftrace/x86: Support SAVE_REGS feature on
 i386
From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>, linux-kernel@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
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Date: Wed, 06 Jun 2012 10:46:26 -0400
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On Wed, 2012-06-06 at 23:37 +0900, Masami Hiramatsu wrote:

> I agree with Frank. Register restoring should be done as far as the
> ftrace is used for kprobes. Of course, one reason is for the fault
> injection, which is very useful for debugging system failure. And
> another technical reason is that we should do "optimization"
> transparently. IMHO, kprobes works normally doing something,
> optimized kprobes also should do so.
> 
> But if you introduce FTRACE_OPS_FL_RSTR_REGS flag for restoring
> registers, it could be possible to provide corresponding flag
> from kprobes side. (perhaps KPROBE_FLAG_NOMODREGS? :))

That's fine, my patch set restores the regs anyway.

-- Steve


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