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From: Jan Kratochvil <jan.kratochvil@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>, mosix@mosix.com.au
Cc: Amnon Shiloh <u3557@miso.sublimeip.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	Pedro Alves <palves@redhat.com>,
	Cyrill Gorcunov <gorcunov@openvz.org>,
	Pavel Emelyanov <xemul@parallels.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-kernel@vger.kernel.org
Subject: Re: PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace: fix the range check)
Date: Wed, 5 Dec 2012 10:29:51 +0100	[thread overview]
Message-ID: <20121205092951.GA14280@host2.jankratochvil.net> (raw)
In-Reply-To: <841b7a319f9d22402d269eed23d03835.squirrel@mail.sublimeip.com> <20121202193058.GA4264@redhat.com>

On Sun, 02 Dec 2012 20:30:58 +0100, Oleg Nesterov wrote:
> Yes, that is why I said this needs the new option.

I do not mind new options although personally I do not find them meaningful
for an already deprecated ABI compatibility-only issue.


> If the tracer does PTRACE_SYSCALL the tracee reports syscall exit
> _after_ gettimeofday/etc. The tracer can look at regs->orig_ax == -1
> and detect that this is not syscall but vsyscall, it can look at
> regs->ip then (not with the patch below).

I believe applications just call PTRACE_SYSCALL twice, without checking
orig_eax.  At least strace and its TCB_INSYSCALL looks so.


On Mon, 03 Dec 2012 00:54:58 +0100, u3557@miso.sublimeip.com wrote:
> The beauty of using the x86 debug-registers,

x86 debug registers are already very scarce.  Besides that userland
applications know they have 4 of them available so it would also break them.


Regards,
Jan

  parent reply	other threads:[~2012-12-05 10:04 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-09 18:29 [PATCH] arch_check_bp_in_kernelspace: fix the range check Oleg Nesterov
2012-11-09 18:30 ` Oleg Nesterov
2012-11-19 17:47   ` Oleg Nesterov
2012-11-19 18:25     ` Steven Rostedt
2012-11-20 10:33       ` u3557
2012-11-20 15:48       ` Oleg Nesterov
2012-11-20 15:55         ` Steven Rostedt
2012-11-20 18:32         ` Oleg Nesterov
2012-11-20 23:16           ` u3557
2012-11-21 14:16             ` Oleg Nesterov
2012-11-21 17:30               ` Amnon Shiloh
2012-11-22 16:12                 ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range check) Oleg Nesterov
2012-11-22 20:57                   ` Pavel Emelyanov
2012-11-23  0:20                     ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range Amnon Shiloh
2012-11-23 17:45                       ` Oleg Nesterov
2012-11-24 12:47                         ` Amnon Shiloh
2012-11-23 17:42                     ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range check) Oleg Nesterov
2012-11-23  9:14                   ` arch_check_bp_in_kernelspace: fix the range check Amnon Shiloh
2012-11-23 16:33                     ` Oleg Nesterov
2012-11-23 17:05                       ` Oleg Nesterov
2012-11-24 14:14                         ` Amnon Shiloh
2012-11-24 13:45                       ` Amnon Shiloh
2012-11-25 22:55                         ` Oleg Nesterov
2012-11-25 23:48                           ` Amnon Shiloh
2012-12-02 19:30                             ` PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace: fix the range check) Oleg Nesterov
2012-12-02 23:54                               ` u3557
2012-12-04 17:59                                 ` Oleg Nesterov
2012-12-04 22:44                                   ` u3557
2013-01-08 17:08                                   ` Pedro Alves
2013-01-09 17:52                                     ` Oleg Nesterov
2013-01-10  6:54                                       ` u3557
2013-01-12 18:12                                         ` Oleg Nesterov
2013-01-14  2:31                                           ` u3557
2013-01-14 16:01                                             ` Oleg Nesterov
2013-02-18  1:39                                               ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-18  5:44                                                 ` prctl(PR_SET_MM) Randy Dunlap
2013-02-18 15:21                                                 ` prctl(PR_SET_MM) Steven Rostedt
2013-02-18 16:33                                                   ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-18 19:49                                                     ` prctl(PR_SET_MM) Steven Rostedt
2013-02-19  6:25                                                       ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-20  8:39                                                         ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-20  9:38                                                           ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-20 10:51                                                             ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-20 11:16                                                               ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-21  7:46                                                               ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-21  8:00                                                                 ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-21  8:03                                                                   ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-21  8:09                                                                     ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-21 22:18                                                                   ` prctl(PR_SET_MM) Andrew Morton
2013-02-21 22:42                                                                     ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-22  1:18                                                                     ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-22 14:23                                                         ` prctl(PR_SET_MM) Denys Vlasenko
2012-12-05  9:29                               ` Jan Kratochvil [this message]
2012-12-05 13:14                                 ` PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace: fix the range check) u3557
2012-11-26  9:44                   ` vdso && cr " Cyrill Gorcunov
2012-11-26 12:27                     ` Andrey Wagin
2012-11-26 12:55                       ` Amnon Shiloh
2012-11-26 14:18                         ` Cyrill Gorcunov
2012-11-26 14:26                           ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range Amnon Shiloh
2012-11-26 14:41                             ` vdso && cr Cyrill Gorcunov

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