Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753818AbaDWNEG (ORCPT <rfc822;w@1wt.eu>);
	Wed, 23 Apr 2014 09:04:06 -0400
Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.231]:44489 "EHLO
	cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL)
	by vger.kernel.org with ESMTP id S1752062AbaDWNEE (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 23 Apr 2014 09:04:04 -0400
Date: Wed, 23 Apr 2014 09:03:55 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Lin Yongting <linyongting@gmail.com>
Cc: linux@arm.linux.org.uk, k.khlebnikov@samsung.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linyongting@huawei.com
Subject: Re: [PATCH] ftrace/arm: add save_stack_trace_regs() implementation
Message-ID: <20140423090355.5a0a98cd@gandalf.local.home>
In-Reply-To: <1398257541-18201-1-git-send-email-linyongting@gmail.com>
References: <1398257541-18201-1-git-send-email-linyongting@gmail.com>
X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.22; x86_64-pc-linux-gnu)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
X-RR-Connecting-IP: 107.14.168.142:25
X-Cloudmark-Score: 0
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, 23 Apr 2014 20:52:21 +0800
Lin Yongting <linyongting@gmail.com> wrote:

> When configure kprobe events of ftrace with "stacktrace" option enabled
> in arm, there is no stacktrace was recorded after the kprobe event was
> triggered. The root cause is no save_stack_trace_regs() function implemented.
> 
> Implement the save_stack_trace_regs() function in arm, then ftrace will
> call this architecture-related function to record the stacktrace into
> ring buffer.
> 
> After this fix, stacktrace can be recorded, for example:
> 
> # mount -t debugfs nodev /sys/kernel/debug
> # echo "p:netrx net_rx_action" >> /sys/kernel/debug/tracing/kprobe_events
> # echo 1 > /sys/kernel/debug/tracing/events/kprobes/netrx/enable
> # echo 1 > /sys/kernel/debug/tracing/options/stacktrace
> # echo 1 > /sys/kernel/debug/tracing/tracing_on
> # ping 127.0.0.1 -c 1
> # echo 0 > /sys/kernel/debug/tracing/tracing_on
> 
> # cat /sys/kernel/debug/tracing/trace
> # tracer: nop
> #
> # entries-in-buffer/entries-written: 12/12   #P:1
> #
> #                              _-----=> irqs-off
> #                             / _----=> need-resched
> #                            | / _---=> hardirq/softirq
> #                            || / _--=> preempt-depth
> #                            ||| /     delay
> #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
> #              | |       |   ||||       |         |
>             <------ missing some entries ---------------->
>             ping-1200  [000] dNs1   667.603250: netrx: (net_rx_action+0x0/0x1f8)
>             ping-1200  [000] dNs1   667.604738: <stack trace>
>  => net_rx_action
>  => do_softirq
>  => local_bh_enable
>  => ip_finish_output
>  => ip_output
>  => ip_local_out
>  => ip_send_skb
>  => ip_push_pending_frames
>  => raw_sendmsg
>  => inet_sendmsg
>  => sock_sendmsg
>  => SyS_sendto
>  => ret_fast_syscall
> 
> Signed-off-by: Lin Yongting <linyongting@gmail.com>
> ---

As this affects ftrace for ARM...

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

>  arch/arm/kernel/stacktrace.c |   19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
> index af4e8c8..c558db6 100644
> --- a/arch/arm/kernel/stacktrace.c
> +++ b/arch/arm/kernel/stacktrace.c
> @@ -123,6 +123,25 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
>  		trace->entries[trace->nr_entries++] = ULONG_MAX;
>  }
>  
> +void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
> +{
> +	struct stack_trace_data data;
> +	struct stackframe frame;
> +
> +	data.trace = trace;
> +	data.skip = trace->skip;
> +	data.no_sched_functions = 0;
> +
> +	frame.fp = regs->ARM_fp;
> +	frame.sp = regs->ARM_sp;
> +	frame.lr = regs->ARM_lr;
> +	frame.pc = regs->ARM_pc;
> +
> +	walk_stackframe(&frame, save_trace, &data);
> +	if (trace->nr_entries < trace->max_entries)
> +		trace->entries[trace->nr_entries++] = ULONG_MAX;
> +}
> +
>  void save_stack_trace(struct stack_trace *trace)
>  {
>  	save_stack_trace_tsk(current, trace);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/