From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linuxppc-dev@ozlabs.org, Ingo Molnar <mingo@elte.hu>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH] powerpc/ftrace: fix constraint to be early clobber
Date: Sat, 16 May 2009 08:27:18 +1000 [thread overview]
Message-ID: <1242426438.9691.5.camel@pasglop> (raw)
In-Reply-To: <alpine.DEB.2.00.0905141236420.30591@gandalf.stny.rr.com>
On Fri, 2009-05-15 at 10:33 -0400, Steven Rostedt wrote:
> After upgrading my distcc boxes from gcc 4.2.2 to 4.4.0, the function
> graph tracer broke. This was discovered on my x86 boxes.
>
> The issue is that gcc used the same register for an output as it did for
> an input in an asm statement. I first thought this was a bug in gcc and
> reported it. I was notified that gcc was correct and that the output had
> to be flagged as an "early clobber".
>
> I noticed that powerpc had the same issue and this patch fixes it.
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Ack. You merge this or I do ?
Cheers,
Ben.
> diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
> index 70e2a73..68fd74e 100644
> --- a/arch/powerpc/kernel/ftrace.c
> +++ b/arch/powerpc/kernel/ftrace.c
> @@ -594,7 +594,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
> PPC_LONG "2b,4b\n"
> ".previous"
>
> - : [old] "=r" (old), [faulted] "=r" (faulted)
> + : [old] "=&r" (old), [faulted] "=r" (faulted)
> : [parent] "r" (parent), [return_hooker] "r" (return_hooker)
> : "memory"
> );
>
> --
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prev parent reply other threads:[~2009-05-15 22:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-15 14:33 [PATCH] powerpc/ftrace: fix constraint to be early clobber Steven Rostedt
2009-05-15 22:27 ` Benjamin Herrenschmidt [this message]
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