linux-kernel - Re: [PATCH] x86/ftrace: Exclude functions in head64.c from function-tracing

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Message-ID: <20170627093825.0d0276ba@gandalf.local.home>
Date:   Tue, 27 Jun 2017 09:38:25 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Ingo Molnar <mingo@...nel.org>, x86@...nel.org,
        Fengguang Wu <fengguang.wu@...el.com>, lkp@...org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/ftrace: Exclude functions in head64.c from
 function-tracing

On Tue, 27 Jun 2017 14:59:48 +0300
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> wrote:

> We've moved most logic of early boot up from startup_64() written in
> assembly to __startup_64() written in C.
> 
> Fengguang reported breakage due to the change. It was tracked down to
> CONFIG_FUNCTION_TRACER being enabled.

Is this due to code that is in linux-next or is this issue currently in
mainline?

If it is in linux-next, I'll give you:

 Acked-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

and you can take it. If the issue happens in current mainline, then I'll
take it and push it out.

-- Steve

> 
> Looks like function-tracing of the new code is harmful.
> 
> Let's not comple the code with -pg compiler option.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Reported-by: Fengguang Wu <fengguang.wu@...el.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> ---
>  arch/x86/kernel/Makefile | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 4b994232cb57..0db512092f37 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -18,6 +18,7 @@ CFLAGS_REMOVE_pvclock.o = -pg
>  CFLAGS_REMOVE_kvmclock.o = -pg
>  CFLAGS_REMOVE_ftrace.o = -pg
>  CFLAGS_REMOVE_early_printk.o = -pg
> +CFLAGS_REMOVE_head64.o = -pg
>  endif
>  
>  KASAN_SANITIZE_head$(BITS).o				:= n