On 15/07/15 21:39, Russell King - ARM Linux wrote:
Back in September, I stumbled across a single CPU IRQs-off lockup of an
ARM SMP system, and decided to hack something together based on a much
older hacky implementation used with StrongARM CPUs from early 2000s.
This resulted in a copy of the x86 NMI backtrace code into ARM as it was
back then, and feedback indicated that it wasn't a good time to push
such an effort forward, as printk() in NMI context is dodgy.
Over time, the x86 code has had this problem addressed, and last week
I updated the patch which I've been carrying in my tree to move the
shared code out of arch/x86 into lib/ rather than duplicating it, and
switch the ARM implementation to use it.
Discussing this with Thomas Gliexner, he agreed to give it a test over
last weekend, and he has reported to me this evening "no explosion so
far". Since then, I've made a change to add the NOKPROBE_SYMBOL() to
the generic handler as per the x86 original code.
I'm aware that there are other competing implementations out there -
Daniel has one based on my patch from September time, but I don't think
that goes far enough with code sharing. I'm also partially aware of
an implementation from Petr too.
No worries. I agree this approach is much cleaner with regards to code
sharing.
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