Re: [PATCH] powerpc/xmon: Fix data-breakpoint

From	Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] powerpc/xmon: Fix data-breakpoint
Date	2016-11-22 13:00 +0100
Message-ID	<sGhU2-6Ds-17@gated-at.bofh.it> (permalink)
References	<sGfyN-5hl-1@gated-at.bofh.it> <sGhAC-6wP-37@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

Thanks Michael,

On Tuesday 22 November 2016 05:03 PM, Michael Ellerman wrote:
> Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> writes:
>
>> Xmon data-breakpoint feature is broken.
>>
>> Whenever there is a watchpoint match occurs, hw_breakpoint_handler will
>> be called by do_break via notifier chains mechanism. If watchpoint is
>> registered by xmon, hw_breakpoint_handler won't find any associated
>> perf_event and returns immediately with NOTIFY_STOP. Similarly, do_break
>> also returns without notifying to xmon.
>>
>> Solve this by returning NOTIFY_DONE when hw_breakpoint_handler does not
>> find any perf_event associated with matched watchpoint.
> .. rather than NOTIFY_STOP, which tells the core code to continue
> calling the other breakpoint handlers including the xmon one.
>
> Right?

Yes.

> Also any idea when we broke this?

Hmm, not sure exactly. The code is same since it was merged in 2010 when
support for hw_breakpoint was added for server processor.

-Ravi

> cheers
>

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH] powerpc/xmon: Fix data-breakpoint Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> - 2016-11-22 10:30 +0100
  Re: [PATCH] powerpc/xmon: Fix data-breakpoint Michael Ellerman <mpe@ellerman.id.au> - 2016-11-22 12:40 +0100
    Re: [PATCH] powerpc/xmon: Fix data-breakpoint Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> - 2016-11-22 13:00 +0100

csiph-web