linux-kernel - Re: [PATCH 5/8] x86,tracing: Mark debug_stack_{set

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Date:   Wed, 12 Feb 2020 16:04:40 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        mingo@...nel.org, joel@...lfernandes.org,
        gregkh@...uxfoundation.org, gustavo@...eddedor.com,
        tglx@...utronix.de, paulmck@...nel.org, josh@...htriplett.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com
Subject: Re: [PATCH 5/8] x86,tracing: Mark debug_stack_{set_zero,reset)()
 notrace

On Wed, Feb 12, 2020 at 09:25:39AM -0500, Steven Rostedt wrote:
> On Wed, 12 Feb 2020 10:32:15 +0100
> Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > Because do_nmi() must not call into tracing outside of
> > nmi_enter()/nmi_exit(), these functions must be notrace.
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> > ---
> >  arch/x86/kernel/cpu/common.c |    4 ++--
> >  arch/x86/kernel/nmi.c        |    6 ++++++
> >  2 files changed, 8 insertions(+), 2 deletions(-)
> > 
> > --- a/arch/x86/kernel/cpu/common.c
> > +++ b/arch/x86/kernel/cpu/common.c
> 
> This entire file is notrace:
> 
>  arch/x86/kernel/cpu/Makefile:
> 
>    CFLAGS_REMOVE_common.o = -pg

Urgh, I hate it that that annotation is so hard to find :/ Also, there
seem to be various flavours of that Makefile magic around.

  CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)

is another variant I encountered.