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From: Marcus Shawcroft <marcus.shawcroft@gmail.com>
To: Pedro Alves <palves@redhat.com>
Cc: Terry Guo <terry.guo@arm.com>,
	Marcus Shawcroft <marcus.shawcroft@arm.com>,
		lgustavo@codesourcery.com,
	Joel Brobecker <brobecker@adacore.com>,
		Yao Qi <yao@codesourcery.com>,
		"gdb-patches@sourceware.org" <gdb-patches@sourceware.org>,
	Will Deacon <will.deacon@arm.com>,
	peter.maydell@arm.com
Subject: Re: [RFA/commit] arm-tdep.c: Do not single-step after hitting a watchpoint.
Date: Thu, 18 Sep 2014 11:40:00 -0000	[thread overview]
Message-ID: <CAFqB+PxZM3Zb0J2HRoULU+e30jMP9OowRFsgJCjaWf7tNvagTA@mail.gmail.com> (raw)
In-Reply-To: <5418556E.7010502@redhat.com>

On 16 September 2014 16:21, Pedro Alves <palves@redhat.com> wrote:
> Hi Terry, Marcus,
>
> Can someone at ARM shed some light on this, please?
>
> This thread is here:
>
>  https://sourceware.org/ml/gdb-patches/2014-09/msg00498.html
>
> And the discussion started in another thread here:
>
>   https://sourceware.org/ml/gdb/2014-09/msg00000.html
>
> I've just added a test that hopefully helps with this, btw:
>
>  https://sourceware.org/ml/gdb-patches/2014-09/msg00535.html
>
> I'm also wondering whether Aarch64 needs adjustment as well.
>
> Thanks,
> Pedro Alves


Hi,

In aarch32 execution state a watch point event is taken as a data
abort with the PC containing the address of the faulting instruction +
8 irrespective of thumb mode.

The linux kernel adjusts the reported PC by subtracting 8 such that
the ptrace interface will indicate the address of the faulting
instruction.

Peter Maydell's proposed qemu patch referenced in the thread above
appears to me to align the gdbstub behaviour in qemu with the linux
kernel ptrace() interface behaviour.

w.r.t DBGWFAR, it's use is described as deprecated in  ARM ARMv7-A&R
Issue C.c  c11.11.45. It is not used by linux kernel.

Cheers
/Marcus


  reply	other threads:[~2014-09-18 11:40 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-15 13:01 Joel Brobecker
2014-09-16 11:12 ` Yao Qi
2014-09-16 11:59   ` Joel Brobecker
2014-09-16 12:05     ` Luis Machado
2014-09-16 12:48       ` Joel Brobecker
2014-09-16 13:09         ` Luis Machado
2014-09-16 15:21           ` Pedro Alves
2014-09-18 11:40             ` Marcus Shawcroft [this message]
2014-09-19 17:31               ` Pedro Alves
2014-09-29 17:51                 ` Joel Brobecker
2014-09-29 17:57                   ` Luis Machado
2014-09-29 21:04                   ` Pedro Alves
2014-09-30  8:54                     ` Will Deacon
2014-09-29 18:23 Peter Maydell
2014-09-29 22:15 ` Pedro Alves
2014-09-29 22:54   ` Peter Maydell
2014-09-30  9:08     ` Pedro Alves
2014-09-30  9:18       ` Will Deacon
2014-09-30 10:07         ` Pedro Alves
2014-09-30 10:18           ` Peter Maydell
2014-09-30 10:38             ` Pedro Alves
2014-09-30 10:01       ` Peter Maydell
2014-09-30 10:34         ` Pedro Alves
2014-09-30 12:54           ` Pedro Alves
2014-09-30 13:50             ` Joel Brobecker
2014-09-30 14:11               ` Pedro Alves
2014-09-30 14:26                 ` Joel Brobecker
2014-09-30 14:50                   ` Peter Maydell
2014-09-30  8:57 ` Will Deacon
2014-09-30  9:04   ` Will Deacon
2014-09-30  9:14   ` Pedro Alves
2014-09-30  9:24     ` Will Deacon

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