From: Cyrill Gorcunov <gorcunov@openvz.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
aarcange@redhat.com, ak@linux.intel.com,
Pavel Emelyanov <xemul@parallels.com>,
Stefani Seibold <stefani@seibold.net>,
x86@kernel.org, linux-kernel@vger.kernel.org, criu@openvz.org,
mingo@redhat.com, john.stultz@linaro.org, tglx@linutronix.de
Subject: Re: [CRIU] [PATCH] Add VDSO time function support for x86 32-bit kernel
Date: Sat, 15 Dec 2012 02:25:17 +0400 [thread overview]
Message-ID: <20121214222517.GG6582@moon> (raw)
In-Reply-To: <50CBA171.4080403@zytor.com>
On Fri, Dec 14, 2012 at 02:00:17PM -0800, H. Peter Anvin wrote:
> On 12/14/2012 01:27 PM, Andy Lutomirski wrote:
> >
> > I don't know all that much about the linux vm. Can we create a
> > special vdso address_space or struct inode or something so that a
> > single vma can contain pages with different flags?
> >
>
> No, that is still different vmas, but it probably isn't a big deal.
>
> The advantage of having an inode/namespace is that it lets you use
> mmap() as opposed to mremap() with it, which might be useful, I don't know.
>
> One option for the checkpoint people might actually be to not use the
> vdso for a process that needs to be checkpointed and restarted on a
> different machine or different kernel version. Instead they can install
> a pseudo-vdso which just calls normal system calls, and is simply a
> static piece of code that makes normal system calls ... since the
> internals of the kernel are hidden from userspace it is "clean" that way.
>
> With any actual vdso you risk something like:
>
Is there a chance to make it something like that (assuming the
dumpee is ptraced)
> -> vdso entry
mark task as vdso-entered
> -> signal received, transfer to signal handler
> -> signal handler exit
before task leave vdso the task mark vdso-entered get cleaned
and if ptraced, the ptracing task is notified
> ... and now you return to the address in the old vdso, but the internals
> of the vdso may have changed.
this would allow us to defer checkpoint until task finish vdso code. Peter,
if I understand you correctly you propose we provide some own proxy-vdso
which would redirect calls to real ones, right? But the main problem
is that is exactly the idea to be able to c/r existing programs without
recompiling and such (or I miss something here?).
Cyrill
next prev parent reply other threads:[~2012-12-14 22:25 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-12 20:19 [PATCH] Add VDSO time function support for x86 32-bit kernel stefani
2012-12-12 23:34 ` H. Peter Anvin
2012-12-13 5:53 ` Stefani Seibold
2012-12-13 6:10 ` H. Peter Anvin
2012-12-13 6:14 ` H. Peter Anvin
2012-12-13 6:17 ` Stefani Seibold
2012-12-13 6:47 ` H. Peter Anvin
2012-12-13 7:17 ` Stefani Seibold
2012-12-13 19:32 ` Andy Lutomirski
2012-12-14 0:09 ` H. Peter Anvin
2012-12-14 0:20 ` Andy Lutomirski
2012-12-14 0:36 ` H. Peter Anvin
2012-12-14 1:32 ` H. Peter Anvin
2012-12-14 1:42 ` Andy Lutomirski
2012-12-14 1:49 ` H. Peter Anvin
2012-12-14 2:11 ` Andy Lutomirski
2012-12-14 2:18 ` H. Peter Anvin
2012-12-14 2:20 ` Andy Lutomirski
2012-12-14 8:34 ` [CRIU] " Pavel Emelyanov
2012-12-14 18:35 ` H. Peter Anvin
2012-12-14 18:44 ` Andy Lutomirski
2012-12-14 18:47 ` H. Peter Anvin
2012-12-14 20:12 ` Cyrill Gorcunov
2012-12-14 21:08 ` H. Peter Anvin
2012-12-14 21:20 ` Cyrill Gorcunov
2012-12-14 21:21 ` H. Peter Anvin
2012-12-14 21:27 ` Andy Lutomirski
2012-12-14 22:00 ` H. Peter Anvin
2012-12-14 22:25 ` Cyrill Gorcunov [this message]
2012-12-14 22:27 ` H. Peter Anvin
2012-12-14 22:43 ` Cyrill Gorcunov
2012-12-14 22:48 ` H. Peter Anvin
2012-12-14 23:48 ` John Stultz
2012-12-14 23:55 ` H. Peter Anvin
2012-12-17 9:05 ` Pavel Emelyanov
[not found] ` <fb2e871b-3e2a-4e96-9eb9-cb2dd4f66eaa@email.android! .com>
2012-12-17 15:21 ` H. Peter Anvin
2012-12-17 18:56 ` Pavel Emelyanov
2012-12-17 18:57 ` H. Peter Anvin
2012-12-14 22:46 ` H. Peter Anvin
2012-12-14 23:09 ` Stefani Seibold
2012-12-14 23:29 ` H. Peter Anvin
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