From: Pedro Alves <palves@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>,
Pavel Emelyanov <xemul@parallels.com>,
Jan Kratochvil <jan.kratochvil@redhat.com>,
Tejun Heo <tj@kernel.org>, Andrew Vagin <avagin@openvz.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ptrace: add ability to get clear_tid_address
Date: Wed, 08 Feb 2012 18:04:20 +0000 [thread overview]
Message-ID: <4F32B924.8080407@redhat.com> (raw)
In-Reply-To: <20120208173103.GA20853@redhat.com>
On 02/08/2012 05:31 PM, Oleg Nesterov wrote:
> On 02/08, Pedro Alves wrote:
>>
>> I just tried it. This is &pthread->tid in glibc/libpthread, so with debug
>> info it's easy to figure out where to set the watchpoint manually with gdb
>> without asking the kernel. Doesn't work. ptrace doesn't show any trap
>> for the kernel writes.
>
> The tracee simply can't report this trap. it is already dead ;) and
> hw breakpoint (used by ptrace) is "pinned" to the thread.
Right, as I said. :-) I saw that a watchpoint trap isn't reported either
for the CLONE_CHILD_SETTID case (that is, within clone, when the kernel
writes the tid to the memory address passed in to the clone syscall).
I wouldn't have been surprised to see the trap in userspace in either
the parent or the child, though I'm not really surprised to not
see it either.
--
Pedro Alves
next prev parent reply other threads:[~2012-02-08 18:04 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-03 11:11 [PATCH] ptrace: add ability to get clear_tid_address Andrew Vagin
2012-02-03 16:25 ` Tejun Heo
2012-02-03 16:30 ` Cyrill Gorcunov
2012-02-03 16:41 ` Oleg Nesterov
2012-02-03 16:54 ` Cyrill Gorcunov
2012-02-03 16:45 ` Pavel Emelyanov
2012-02-03 16:51 ` Oleg Nesterov
2012-02-07 20:07 ` Pedro Alves
2012-02-07 20:56 ` Cyrill Gorcunov
2012-02-07 21:15 ` Pedro Alves
2012-02-07 21:51 ` Cyrill Gorcunov
2012-02-08 12:30 ` Pedro Alves
2012-02-08 12:42 ` Cyrill Gorcunov
2012-02-08 17:31 ` Oleg Nesterov
2012-02-08 18:04 ` Pedro Alves [this message]
2012-02-08 19:02 ` Oleg Nesterov
2012-02-08 19:20 ` Cyrill Gorcunov
2012-02-08 19:21 ` Jan Kratochvil
2012-02-08 19:42 ` Pedro Alves
2012-02-08 13:41 ` Andrew Vagin
2012-02-08 18:12 ` Jan Kratochvil
2012-02-10 3:02 ` Jamie Lokier
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