Date: Tue, 5 Jun 2012 17:24:11 -0400
From: "Frank Ch. Eigler" <fche@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.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>,
        yrl.pp-manager.tt@hitachi.com
Subject: Re: [PATCH -tip v2 3/9] ftrace/x86: Support SAVE_REGS feature on i386
Message-ID: <20120605212411.GC11575@redhat.com>
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Hi -

On Tue, Jun 05, 2012 at 04:37:46PM -0400, Steven Rostedt wrote:
> [...]
> I'm not sure we really need to restore all the regs. I'll keep this for
> now, but for an optimization, we can just restore the ones that mcount
> mcount needs to.
> 
> Or do you expect kprobes to change any of theses?

That would be the way for a kprobe to modify variables/values that
happen to be in the registers.  In systemtap, for example:

# stap -g -e 'probe kernel.function("foo") { $bar = 1 }'

- FChE
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