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From: Arnd Bergmann <arnd@arndb.de>
To: Greg KH <gregkh@linuxfoundation.org>
Subject: Re: v4.7.5 build: 0 failures 2 warnings (v4.7.5)
Date: Mon, 26 Sep 2016 01:46:51 +0200
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On Sunday 25 September 2016, Greg KH wrote:
> 
> Hi Arnd,
> 
> I'm getting the following build warnings on the 4.7-stable tree, any
> ideas what they are from:
> 
> In file included from ../kernel/trace/trace_irqsoff.c:15:0:
> ../kernel/trace/trace_irqsoff.c: In function ‘stop_critical_timings’:
> ../include/linux/ftrace.h:703:36: warning: calling ‘__builtin_return_address’ with a nonzero argument is unsafe [-Wframe-address]
>  #  define ftrace_return_address(n) __builtin_return_address(n)
>                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../include/linux/ftrace.h:710:38: note: in expansion of macro ‘ftrace_return_address’
>  #define CALLER_ADDR1 ((unsigned long)ftrace_return_address(1))
>                                       ^~~~~~~~~~~~~~~~~~~~~
> ../kernel/trace/trace_irqsoff.c:433:38: note: in expansion of macro ‘CALLER_ADDR1’
>    stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
>                                       ^~~~~~~~~~~~
> 
> It shows up in a few other places as well with this signature.
> 
> Same goes for the 4.4-stable tree

In mainline, this warning got disabled with 124a3d88fa20 ("Disable "frame-address"
warning") and then later that change was partially reverted wtih 377ccbb48373
("Makefile: Mute warning for __builtin_return_address(>0) for tracing only").

It's probably fine if you apply both to the stable kernel.

I think I never saw this particular warning in my ARM build tests.

	Arnd