From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756651Ab3A2NBZ (ORCPT ); Tue, 29 Jan 2013 08:01:25 -0500 Received: from mail-lb0-f182.google.com ([209.85.217.182]:34381 "EHLO mail-lb0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752364Ab3A2NBW (ORCPT ); Tue, 29 Jan 2013 08:01:22 -0500 Date: Tue, 29 Jan 2013 13:01:12 +0000 From: Dave Martin To: Keun-O Park Cc: rostedt@goodmis.org, sahara , linux@arm.linux.org.uk, fweisbec@gmail.com, linux-kernel@vger.kernel.org, mingo@redhat.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm: fix returning wrong CALLER_ADDRx Message-ID: <20130129130039.GA3817@linaro.org> References: <1357888690-24012-1-git-send-email-kpark3469@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1357888690-24012-1-git-send-email-kpark3469@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 11, 2013 at 04:18:10PM +0900, Keun-O Park wrote: > From: sahara > > This makes return_address return correct value for ftrace feature. > unwind_frame does not update frame->lr but frame->pc for backtrace. > And, the initialization for data.addr was missing so that wrong value > returned when unwind_frame failed. > > Signed-off-by: sahara Reviewed-by: Dave Martin This is the same as a patch I previously posted: http://lists.infradead.org/pipermail/linux-arm-kernel/2012-November/129381.html ...except for the initialisation of data.addr to NULL, which is needed in order to prevent a garbage pointer being returned in the case where the unwinder fails to unwind a frame before the required level is reached. Cheers ---Dave > --- > arch/arm/kernel/return_address.c | 5 +++-- > 1 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/kernel/return_address.c b/arch/arm/kernel/return_address.c > index 8085417..fafedd8 100644 > --- a/arch/arm/kernel/return_address.c > +++ b/arch/arm/kernel/return_address.c > @@ -26,7 +26,7 @@ static int save_return_addr(struct stackframe *frame, void *d) > struct return_address_data *data = d; > > if (!data->level) { > - data->addr = (void *)frame->lr; > + data->addr = (void *)frame->pc; > > return 1; > } else { > @@ -41,7 +41,8 @@ void *return_address(unsigned int level) > struct stackframe frame; > register unsigned long current_sp asm ("sp"); > > - data.level = level + 1; > + data.level = level + 2; > + data.addr = NULL; > > frame.fp = (unsigned long)__builtin_frame_address(0); > frame.sp = current_sp; > -- > 1.7.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel