[PATCH] arm64: kernel: Fix unmasked debug exceptions when restoring mdscr_el1

Hi Lorenzo,

On 26/08/16 17:39, Lorenzo Pieralisi wrote:

On Fri, Aug 26, 2016 at 04:03:42PM +0100, James Morse wrote:

quoted

Changes to make the resume from cpu_suspend() code behave more like
secondary boot caused debug exceptions to be unmasked early by
__cpu_setup(). We then go on to restore mdscr_el1 in cpu_do_resume(),
potentially taking break or watch points based on uninitialised registers.

Another option would be moving enable_dbg() out of __cpu_setup() and
calling when it returns in the cold boot path, that would not change
much in terms of debugging but we would avoid fiddling about with
daif three times in the resume path just to restore it to what it
was on suspend entry :)

I agree, but there is/will-be quite a lot of churn in the code that calls
enable_mmu() if Ard's cleanup series is taken. I think this is the tidiest fix
to backport. I will post a patch to tidy this up as you suggest for v4.9-rc1.


Thanks,

James