From: Oleg Nesterov <oleg@redhat.com>
To: Amnon Shiloh <u3557@miso.sublimeip.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Pavel Emelyanov <xemul@parallels.com>
Cc: 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: vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range check)
Date: Thu, 22 Nov 2012 17:12:38 +0100 [thread overview]
Message-ID: <20121122161238.GA27078@redhat.com> (raw)
In-Reply-To: <20121121173043.F0319592076@miso.sublimeip.com>
On 11/22, Amnon Shiloh wrote:
>
> Now however, that "vsyscall" was effectively replaced by vdso, it
> creates a new problem for me and probably for anyone else who uses
> some form of checkpoint/restore:
Oh, sorry, I can't help here. I can only add Cyrill and Pavel, they
seem to enjoy trying to solve the c/r problems.
> Suppose a process is checkpointed because the system needs to reboot
> for a kernel-upgrade, then restored on the new and different kernel.
> The new VDSO page may no longer match the new kernel - it could for
> example fetch data from addresses in the vsyscall page that now
> contain different things; or in case the hardware also was changed,
> it may use machine-instructions that are now illegal.
Sure. You shouldn't try to save/restore this page(s) directly. But
I do not really understand why do you need. IOW, I don't really
understand the problem, it depends on what c/r actually does.
> As I don't mind to forego the "fast" sys_time(), my obvious solution
> is to disable the vdso for traced processes that may be checkpointed.
>
> One way to do it would be by brute-force: straight after "execve"
> unmap the tracee's vdso page,
Not sure this will be always possible. For example, my (old) glibc
assumes that vsyscall() must work, I won't be surprised if some time
later it won't work without vdso. But again, I do not know.
> then manipulate the ELF tables in
> its memory so the VDSO entry is gone and the library will not go
> looking for it.
Probably it would be enough to simply erase AT_SYSINFO_EHDR note,
but again, I can be easily wrong.
> I just wonder whether you know of an easier and more standard way
> to disable the vdso in user-mode
Only the kernel parameter, afaics. vdso=0
> - ideally on a per-process basis,
> or otherwise, if it's too hard, on the whole computer. I searched
> the web and found references to "/proc/sys/vm/vdso_enable", but I
> have no such file or "sysctl" option on my system.
sys/vm/vdso_enabled, but only if CONFIG_X86_32 for some reason. See
kernel/sysctl.c
Oleg.
next prev parent reply other threads:[~2012-11-22 18:29 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 ` Oleg Nesterov [this message]
2012-11-22 20:57 ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range check) 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 ` PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace: fix the range check) Jan Kratochvil
2012-12-05 13:14 ` 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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