From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC 1/1] orc: mark it as reliable
Date: Wed, 4 Oct 2017 09:04:22 -0500 [thread overview]
Message-ID: <20171004140422.wikfoodyhoas2eae@treble> (raw)
In-Reply-To: <20171004092315.17129-1-jslaby@suse.cz>
On Wed, Oct 04, 2017 at 11:23:15AM +0200, Jiri Slaby wrote:
> We need a reliable stack unwinder for kernel live patching, but we do
> not want to enable frame pointers for performance reasons. So let ORC be
> a reliable stack unwinder on x86 as it performs nicely wrt reliability
> of traces.
>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> Cc: Josh Poimboeuf <jpoimboe@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: x86@kernel.org
> ---
>
> I am sending this as an RFC. Do you still consider ORC to be not-enough
> reliable?
Off the top of my head, at least the following is missing:
- save_stack_trace_reliable() assumes that kernel mode pt_regs on the
stack make the stack trace unreliable. This is an FP-specific
assumption which no longer applies for ORC.
- The ORC unwinder needs to set unwind_state.error if it doesn't reach
all the way to the end (user pt_regs).
--
Josh
prev parent reply other threads:[~2017-10-04 14:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-04 9:23 [RFC 1/1] orc: mark it as reliable Jiri Slaby
2017-10-04 14:04 ` Josh Poimboeuf [this message]
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