[PATCH v1] arm64: Add support for on-demand backtrace of other CPUs

[Daniel Thompson]

On 07/04/17 18:02, Catalin Marinas wrote:
> On Fri, Mar 17, 2017 at 09:27:43AM +0200, Oleksandr Andrushchenko wrote:
>> From: Daniel Thompson <daniel.thompson at linaro.org>
>>
>> Currently arm64 has no implementation of arch_trigger_cpumask_backtrace.
>> The patch provides one using library code recently added by Russell King
>> for for the majority of the implementation. Currently this is realized
>> using regular irqs but could, in the future, be implemented using
>> NMI-like mechanisms.
>>
>> Note: There is a small (and nasty) change to the generic code to ensure
>>       good stack traces. The generic code currently assumes that
>>       show_regs() will include a stack trace but arch/arm64 does not do
>>       this so we must add extra code here. Ideas on a better approach
>>       here would be very welcome (is there any appetite to change arm64
>>       show_regs() or should we just tease out the dump code into a
>>       callback
>
> Please see this discussion here:
>
> http://lkml.kernel.org/r/20170323150357.GH9287@leverpostej
>
> I'm not a ware of a follow up but if we change the arm64 show_regs() to
> dump the stack, we no longer need the generic code hunk in your patch.

Great. That hack did always irk me!

I'll tidy it up the next time I push out the PMR interrupt masking patch 
set.

Is there any interest in taking the patch before that. I don't mind 
separating it out... I'm just not sure how useful it is.