From: oleg@redhat.com (Oleg Nesterov)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/9] uprobes: allow ignoring of probe hits
Date: Sun, 21 Oct 2012 21:40:58 +0200 [thread overview]
Message-ID: <20121021194058.GA29137@redhat.com> (raw)
In-Reply-To: <20121021181504.GA4840@ubuntu>
On 10/21, Rabin Vincent wrote:
>
> On Wed, Oct 17, 2012 at 07:35:10PM +0200, Oleg Nesterov wrote:
> >
> > And, to clarify, I am not arguing. Just curious.
> >
> > So, is this like cmov on x86? And this patch allows to not report if
> > the condition is not true? Or there are other issues on arm?
>
> Yes, I guess this is like CMOV on x86. In the ARM instruction set most
> instructions can be conditionally executed.
>
> In order to set the probe on a conditional instruction, we use an
> undefined instruction with the same condition as the instruction we
> replace. However, it is implementation defined whether an undefined
> instruction with a failing condition code will trigger an undefined
> instruction exception or just be executed as a NOP. So for those
> processor implementations where we do get the undefined instruction
> exception even for a failing condition code, we have to ignore it in
> order to provide consistent behaviour.
OK, I see, thanks for your explanation.
Oleg.
WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: Rabin Vincent <rabin@rab.in>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Peter Zijlstra <peterz@infradead.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Subject: Re: [PATCH 3/9] uprobes: allow ignoring of probe hits
Date: Sun, 21 Oct 2012 21:40:58 +0200 [thread overview]
Message-ID: <20121021194058.GA29137@redhat.com> (raw)
In-Reply-To: <20121021181504.GA4840@ubuntu>
On 10/21, Rabin Vincent wrote:
>
> On Wed, Oct 17, 2012 at 07:35:10PM +0200, Oleg Nesterov wrote:
> >
> > And, to clarify, I am not arguing. Just curious.
> >
> > So, is this like cmov on x86? And this patch allows to not report if
> > the condition is not true? Or there are other issues on arm?
>
> Yes, I guess this is like CMOV on x86. In the ARM instruction set most
> instructions can be conditionally executed.
>
> In order to set the probe on a conditional instruction, we use an
> undefined instruction with the same condition as the instruction we
> replace. However, it is implementation defined whether an undefined
> instruction with a failing condition code will trigger an undefined
> instruction exception or just be executed as a NOP. So for those
> processor implementations where we do get the undefined instruction
> exception even for a failing condition code, we have to ignore it in
> order to provide consistent behaviour.
OK, I see, thanks for your explanation.
Oleg.
next prev parent reply other threads:[~2012-10-21 19:40 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-14 19:23 [PATCH 1/9] uprobes: move function declarations out of arch Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-14 19:23 ` [PATCH 2/9] uprobes: check for single step support Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-17 16:40 ` Srikar Dronamraju
2012-10-17 16:40 ` Srikar Dronamraju
2012-10-17 17:02 ` Oleg Nesterov
2012-10-17 17:02 ` Oleg Nesterov
2012-10-14 19:23 ` [PATCH 3/9] uprobes: allow ignoring of probe hits Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-15 16:52 ` Oleg Nesterov
2012-10-15 16:52 ` Oleg Nesterov
2012-10-16 20:11 ` Rabin Vincent
2012-10-16 20:11 ` Rabin Vincent
2012-10-17 17:35 ` Oleg Nesterov
2012-10-17 17:35 ` Oleg Nesterov
2012-10-21 18:15 ` Rabin Vincent
2012-10-21 18:15 ` Rabin Vincent
2012-10-21 19:40 ` Oleg Nesterov [this message]
2012-10-21 19:40 ` Oleg Nesterov
2012-10-17 16:52 ` Srikar Dronamraju
2012-10-17 16:52 ` Srikar Dronamraju
2012-10-14 19:23 ` [PATCH 4/9] uprobes: allow arch access to xol slot Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-17 17:17 ` Srikar Dronamraju
2012-10-17 17:17 ` Srikar Dronamraju
2012-10-14 19:23 ` [PATCH 5/9] uprobes: allow arch-specific initialization Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-18 9:39 ` Srikar Dronamraju
2012-10-18 9:39 ` Srikar Dronamraju
2012-10-14 19:23 ` [PATCH 6/9] uprobes: flush cache after xol write Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-15 16:57 ` Oleg Nesterov
2012-10-15 16:57 ` Oleg Nesterov
2012-10-16 20:29 ` Rabin Vincent
2012-10-16 20:29 ` Rabin Vincent
2012-10-25 14:58 ` Oleg Nesterov
2012-10-25 14:58 ` Oleg Nesterov
2012-10-26 5:52 ` Ananth N Mavinakayanahalli
2012-10-26 5:52 ` Ananth N Mavinakayanahalli
2012-10-26 16:39 ` Oleg Nesterov
2012-10-26 16:39 ` Oleg Nesterov
2012-10-29 5:35 ` Ananth N Mavinakayanahalli
2012-10-29 5:35 ` Ananth N Mavinakayanahalli
2012-11-03 16:33 ` Oleg Nesterov
2012-11-03 16:33 ` Oleg Nesterov
2012-11-04 14:29 ` Ananth N Mavinakayanahalli
2012-11-04 14:29 ` Ananth N Mavinakayanahalli
2012-11-14 17:37 ` Oleg Nesterov
2012-11-14 17:37 ` Oleg Nesterov
2012-10-14 19:23 ` [PATCH 7/9] uprobes: add arch write opcode hook Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-14 19:23 ` [PATCH 8/9] ARM: support uprobe handling Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-11-04 10:13 ` Russell King - ARM Linux
2012-11-04 10:13 ` Russell King - ARM Linux
2012-11-12 17:26 ` Rabin Vincent
2012-11-12 17:26 ` Rabin Vincent
2012-10-14 19:23 ` [PATCH 9/9] ARM: add uprobes support Rabin Vincent
2012-10-14 19:23 ` Rabin Vincent
2012-10-15 11:14 ` Dave Martin
2012-10-15 11:14 ` Dave Martin
2012-10-15 11:44 ` Rabin Vincent
2012-10-15 11:44 ` Rabin Vincent
2012-10-15 17:44 ` Dave Martin
2012-10-15 17:44 ` Dave Martin
2012-10-17 14:50 ` Jon Medhurst (Tixy)
2012-10-17 14:50 ` Jon Medhurst (Tixy)
2012-10-21 18:43 ` Rabin Vincent
2012-10-21 18:43 ` Rabin Vincent
2012-10-21 18:59 ` Rabin Vincent
2012-10-21 18:59 ` Rabin Vincent
2012-10-15 17:31 ` Dave Martin
2012-10-15 17:31 ` Dave Martin
2012-10-21 18:27 ` Rabin Vincent
2012-10-21 18:27 ` Rabin Vincent
2012-10-17 17:54 ` Oleg Nesterov
2012-10-17 17:54 ` Oleg Nesterov
2012-10-15 17:19 ` [PATCH 1/9] uprobes: move function declarations out of arch Srikar Dronamraju
2012-10-15 17:19 ` Srikar Dronamraju
2012-10-16 20:30 ` Rabin Vincent
2012-10-16 20:30 ` Rabin Vincent
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