From: Oleg Nesterov <oleg@redhat.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alan Stern <stern@rowland.harvard.edu>,
Ingo Molnar <mingo@elte.hu>,
Jan Kratochvil <jan.kratochvil@redhat.com>,
Maneesh Soni <maneesh@linux.vnet.ibm.com>,
Prasad <prasad@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] ptrace/x86: simplify ptrace_write_dr7()
Date: Tue, 16 Apr 2013 15:25:45 +0200 [thread overview]
Message-ID: <20130416132545.GA9189@redhat.com> (raw)
In-Reply-To: <20130415233652.GE17561@somewhere.redhat.com>
On 04/16, Frederic Weisbecker wrote:
>
> On Sun, Apr 14, 2013 at 09:12:05PM +0200, Oleg Nesterov wrote:
>
> Looking at the bug report, it seems they only reproduced with a homemade
> test. No real app has reported that issue?
iirc (Jan can correct me) gdb hit this problem, but it was already
changed to change DR0 first.
> > Jan, Frederic, et all. What do you think we should do?
> >
> > 1. Change ptrace_write_dr7() to do register_user_hw_breakpoint()
> > if necessary.
> >
> > This is what I was going to do, but I am no longer sure
> > we want this. For what? Unlikely it is very useful to use
> > the "default" addr == 0 for debugging.
>
> So you mean assume that the addr is 0 in dr[0-3] if we write dr7 before writing
> the addr register?
Yes,
> Yes, I'm convinced that's the right direction!
OK. Thanks Jan and Frederic.
I'll send v2 tomorrow with the 3rd patch which adds _register into
write_dr7. Plus another minor/offtopic fix I forgot to send.
Oleg.
next prev parent reply other threads:[~2013-04-16 13:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-14 19:12 [PATCH 0/2] ptrace/x86: simplify ptrace_write_dr7() Oleg Nesterov
2013-04-14 19:12 ` [PATCH 1/2] ptrace/x86: simplify the "disable" logic in ptrace_write_dr7() Oleg Nesterov
2013-04-16 0:03 ` Frederic Weisbecker
2013-04-14 19:12 ` [PATCH 2/2] ptrace/x86: dont delay perf_event_disable() till second pass " Oleg Nesterov
2013-04-16 0:44 ` Frederic Weisbecker
2013-04-16 13:30 ` Oleg Nesterov
2013-04-16 22:00 ` Frederic Weisbecker
2013-04-17 12:40 ` Oleg Nesterov
2013-04-14 19:30 ` [PATCH 0/2] ptrace/x86: simplify ptrace_write_dr7() Jan Kratochvil
2013-04-14 19:40 ` Oleg Nesterov
2013-04-15 23:36 ` Frederic Weisbecker
2013-04-16 13:25 ` Oleg Nesterov [this message]
2013-04-17 4:57 ` Jan Kratochvil
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