linux-kernel - Re: [patch 5/8] x86/entry/common: Provide trace/kprobe safe exit to user space functions

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Message-ID: <20200226081505.GP18400@hirez.programming.kicks-ass.net>
Date:   Wed, 26 Feb 2020 09:15:05 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [patch 5/8] x86/entry/common: Provide trace/kprobe safe exit to
 user space functions

On Tue, Feb 25, 2020 at 09:45:11PM -0800, Andy Lutomirski wrote:
> On 2/25/20 2:08 PM, Thomas Gleixner wrote:
> > Split prepare_enter_to_user_mode() and mark it notrace/noprobe so the irq
> > flags tracing on return can be put into it.
> 
> Is our tooling clever enough for thsi to do anything?  You have a static
> inline that is only called in one place, and the caller is notrace and
> NOKPROBE.  Does this actually allow tracing in the static inline callee?

tracing, no, but the NOKPROBE on inline functions is buggered afaiu.