x86/mm/kmmio: Fix mmiotrace for page unaligned addresses

If something calls ioremap() with an address not aligned to PAGE_SIZE, the
returned address might be not aligned as well. This led to a probe
registered on exactly the returned address, but the entire page was armed
for mmiotracing.

On calling iounmap() the address passed to unregister_kmmio_probe() was
PAGE_SIZE aligned by the caller leading to a complete freeze of the
machine.

We should always page align addresses while (un)registerung mappings,
because the mmiotracer works on top of pages, not mappings. We still keep
track of the probes based on their real addresses and lengths though,
because the mmiotrace still needs to know what are mapped memory regions.

Also move the call to mmiotrace_iounmap() prior page aligning the address,
so that all probes are unregistered properly, otherwise the kernel ends up
failing memory allocations randomly after disabling the mmiotracer.

Tested-by: Lyude <[email protected]>
Signed-off-by: Karol Herbst <[email protected]>
Acked-by: Pekka Paalanen <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions