[PATCH] powerpc64/hw_breakpoints: Handle data breakpoints in radix mode

[Michael Ellerman]

Anshuman Khandual <khandual at linux.vnet.ibm.com> writes:

> On 06/14/2017 12:12 AM, Naveen N. Rao wrote:
>> On P9, trying to use data breakpoints throws the splat shown below (*).
>> This is because the check for a data breakpoint in DSISR is in
>> do_hash_page(). Move this check to handle_page_fault() so as to catch
>> data breakpoints in both hash and radix MMU modes.
>
> Why cant we check for DSISR inside do_hash_page() on P9 ?

We can.

But we also need to check inside handle_page_fault(), because when we're
in Radix mode we don't go via do_hash_page().

So rather than doing it in two places, the patch changes the logic so we
check in handle_page_fault(), and teaches the do_hash_page() code to go
there if DSISR_DABRMATCH is set.

cheers