[PATCH] arm64: fix dump_backtrace with NULL tsk

[James Morse]

Hi Mark,

On 23/09/16 15:56, Mark Rutland wrote:
> In some places, dump_backtrace() is called with a NULL tsk parameter,
> e.g. in bug_handler() in arch/arm64, or indirectly via show_stack() in
> core code. The expectation is that this is treated as if current were
> passed instead of NULL.
> 
> Commit a80a0eb70c358f8c ("arm64: make irq_stack_ptr more robust") didn't
> take this into account, and compares tsk against current *before* we
> check if tsk is NULL.
> 
> Due to this, we won't initialise irq_stack_ptr, and when we try to dump
> the exception regs we may call dump_mem() for memory immediately above
> the IRQ stack range, rather than for the relevant range on the task
> stack.

Bother, I should have spotted that.
Thanks for catching this!

Acked-by: James Morse <james.morse at arm.com>



Thanks,

James