From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Jessica Yu <jeyu@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: livepatch/kprobes incompatibility
Date: Thu, 25 Aug 2016 11:08:14 -0500 [thread overview]
Message-ID: <20160825160814.5gawgk4222vusrj5@treble> (raw)
In-Reply-To: <20160824093959.GG4866@pathway.suse.cz>
On Wed, Aug 24, 2016 at 11:39:59AM +0200, Petr Mladek wrote:
> + kretprobe is safe as well; the kprobe handler does not modify regs->ip;
> it just modifies the return address from the function; it does not affect
> livepatching because the address is defined by the function caller
> and livepatching keeps it as is
BTW, I think there's still a kretprobe issue which affects the accuracy
of the unwinder and the consistency model. The unwinder will report
kretprobe_trampoline instead of the real caller's return address.
It can probably be fixed similarly to how ftrace function_graph tracing
does it with a ftrace_graph_ret_addr() helper:
https://lkml.kernel.org/r/cover.1471607358.git.jpoimboe@redhat.com
--
Josh
next prev parent reply other threads:[~2016-08-25 16:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-24 1:13 Jessica Yu
2016-08-24 9:39 ` Petr Mladek
2016-08-24 15:23 ` Masami Hiramatsu
2016-08-25 16:08 ` Josh Poimboeuf [this message]
2016-08-24 15:16 ` Masami Hiramatsu
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