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Message-ID: <55250780.6090408@linaro.org>
Date: Wed, 08 Apr 2015 11:48:32 +0100
From: Daniel Thompson <daniel.thompson@linaro.org>
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To: Hillf Danton <hillf.zj@alibaba-inc.com>
CC: linux-kernel <linux-kernel@vger.kernel.org>,
        Russell King <rmk+kernel@arm.linux.org.uk>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RESEND PATCH 4.0-rc5 v19 6/6] ARM: Add support for on-demand
 backtrace of other CPUs
References: <089101d071d6$4ebe2a90$ec3a7fb0$@alibaba-inc.com> <089201d071d6$f4eb8480$dec28d80$@alibaba-inc.com>
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On 08/04/15 09:35, Hillf Danton wrote:
>>
>> +void ipi_cpu_backtrace(struct pt_regs *regs)
>> +{
>> +	int cpu = smp_processor_id();
>> +
>> +	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
>> +		printk_nmi_backtrace_this_cpu_begin();
>> +		pr_warn("FIQ backtrace for cpu %d\n", cpu);
>> +		if (regs != NULL)
>> +			show_regs(regs);
>> +		else
>> +			dump_stack();
>
> Help more if we could print both register and stack info.

I think this code already prints as much as it can in all cases.

The arch/arm implementation of show_regs() calls dump_stack() internally 
so the first case does show register and stack info.

In the second case, where regs is NULL because we have been called 
directly from task context, there aren't any saved regs for us to show.


Daniel.