Re: [PATCH/AARCH64] Fix hardware break points

[Will Newton <will.newton@linaro.org>]

On 16 September 2013 13:43, Pedro Alves <palves@redhat.com> wrote:
> On 09/12/2013 08:15 AM, Andrew Pinski wrote:
>> On Tue, Sep 10, 2013 at 7:37 AM, Will Newton <will.newton@linaro.org> wrote:
>>> On 27 July 2013 23:42, Andrew Pinski <pinskia@gmail.com> wrote:
>>>
>>> Hi Andrew,
>>>
>>>> On Sat, Jul 27, 2013 at 2:34 PM, Andreas Schwab <schwab@linux-m68k.org> wrote:
>>>>> Andrew Pinski <pinskia@gmail.com> writes:
>>>>>
>>>>>> OK?  Built and tested on aarch64-linux-gnu with no regressions.
>>>>>
>>>>> Did you?
>>>>>
>>>>>> +  memset (&regs, 0, size(regs));
>>>>
>>>> This is what I get for copying and pasting from one source file to another.
>>>>
>>>> Here is the fixed one which was definitely tested.
>>>
>>> What's the status of this patch? It seems like it fixes real problems
>>> people are seeing in the field.
>
>> After not much thought, I decided this was an obvious patch as regs is
>> used uninitialized otherwise when passed to ptrace.
>
> Leaves me wondering what field of regs other than regs.dbg_regs is
> the kernel actually looking at then for NT_ARM_HW_WATCH/NT_ARM_HW_BREAK,
> given regs.dbg_regs _is_ initialized:

The dbg_info field is probably the important one, so it may be
possible to optimize the clearing slightly but I'm not sure if it's
worth it.

>   for (i = 0; i < count; i++)
>     {
>       regs.dbg_regs[i].addr = addr[i];
>       regs.dbg_regs[i].ctrl = ctrl[i];
>     }
>
>   if (ptrace (PTRACE_SETREGSET, tid,
>               watchpoint ? NT_ARM_HW_WATCH : NT_ARM_HW_BREAK,
>               (void *) &iov))
>
> Makes me wonder whether the issue is that "count" isn't right for
> the running kernel.
>
> Was a patch for gdbserver ever posted/committed?  AFAICS,
> gdbserver's aarch64_linux_set_debug_regs is an exact copy of gdb's.

I posted a patch for that here:

https://sourceware.org/ml/gdb-patches/2013-09/msg00381.html

-- 
Will Newton
Toolchain Working Group, Linaro