linux-kernel - Re: [PATCH v4 05/27] x86: Replace ist_enter() with nmi

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Message-ID: <20200224114754.0fb798c1@gandalf.local.home>
Date:   Mon, 24 Feb 2020 11:47:54 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Andy Lutomirski <luto@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Greg KH <gregkh@...uxfoundation.org>, gustavo@...eddedor.com,
        Thomas Gleixner <tglx@...utronix.de>, paulmck@...nel.org,
        Josh Triplett <josh@...htriplett.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Tony Luck <tony.luck@...el.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH v4 05/27] x86: Replace ist_enter() with nmi_enter()

On Mon, 24 Feb 2020 17:34:09 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> Looking at nmi_enter(), that leaves trace_hardirq_enter(), since we know
> we marked rcu_nmi_enter() as NOKPROBES, per the patches elsewhere in
> this series.

Maybe this was addressed already in the series, but I'm just looking at
Linus's master branch we have:

#define nmi_enter()                                             \
        do {                                                    \
                arch_nmi_enter();                               \
                printk_nmi_enter();                             \
                lockdep_off();                                  \
                ftrace_nmi_enter();                             \
                BUG_ON(in_nmi());                               \
                preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \
                rcu_nmi_enter();                                \
                trace_hardirq_enter();                          \
        } while (0)


Just want to confirm that printk_nmi_enter(), lockdep_off(),
and ftrace_nmi_enter() are all marked fully with NOKPROBE.

-- Steve