From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@amacapital.net>,
Stefani Seibold <stefani@seibold.net>
Cc: Greg KH <gregkh@linuxfoundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Andi Kleen <ak@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
John Stultz <john.stultz@linaro.org>,
Pavel Emelyanov <xemul@parallels.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
andriy.shevchenko@linux.intel.com,
Martin.Runge@rohde-schwarz.com, Andreas.Brief@rohde-schwarz.com
Subject: Re: [PATCH 0/4] Add 32 bit VDSO time function support
Date: Thu, 30 Jan 2014 10:03:16 -0800 [thread overview]
Message-ID: <52EA93E4.6010504@zytor.com> (raw)
In-Reply-To: <CALCETrVaKxY22=4S=mWhUgQ--H77kqnay5G8f847H=Cfper86w@mail.gmail.com>
On 01/30/2014 09:57 AM, Andy Lutomirski wrote:
>
> By definition there aren't any broken users of the new functions,
> because there aren't any users at all. So... should we start
> randomizing this thing from the beginning?
>
The vdso already exists. It isn't new. Randomizing it might be a good
idea, though; it already is randomized on 64 bits.
> Also, since the VVAR page has a real vma, should something be done to
> prevent mprotect or ptrace from COWing it? Users will be rather
> surprised if it suddenly stops updating.
What happens currently on 64 bits? I think we just take the attitude
that "don't do that, then", and it hasn't seemed to be a problem.
> Finally, this might be the time to kill off the userspace mapping of
> the HPET. I suspect that there are few if any machines for which the
> HPET is fast enough that avoiding a syscall matters at all. (On my
> box at work, reading the HPET takes ~500 nanoseconds. I can do a lot
> of syscalls in that amount of time.)
I think this can be independent of extending the current 64-bit
functionality to 32 bits. It is a valid question, though.
-hpa
next prev parent reply other threads:[~2014-01-30 18:04 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 10:49 [PATCH 0/4] Add 32 bit VDSO time function support stefani
2014-01-30 10:49 ` [PATCH 1/4] Make vsyscall_gtod_data handling x86 generic stefani
2014-01-30 18:05 ` Andy Lutomirski
2014-01-30 19:27 ` Stefani Seibold
2014-01-30 19:51 ` Andy Lutomirski
2014-01-30 20:19 ` Stefani Seibold
2014-01-31 0:10 ` Andi Kleen
2014-02-01 14:51 ` Stefani Seibold
2014-01-30 10:49 ` [PATCH 2/4] Add new func _install_special_mapping() to mmap.c stefani
2014-01-30 10:49 ` [PATCH 3/4] Add 32 bit VDSO support for 32 kernel stefani
2014-01-30 15:30 ` H. Peter Anvin
2014-01-30 15:53 ` Stefani Seibold
2014-01-30 18:17 ` Andy Lutomirski
2014-01-30 19:39 ` Stefani Seibold
2014-01-30 19:50 ` Andy Lutomirski
2014-01-30 10:49 ` [PATCH 4/4] Add 32 bit VDSO support for 64 kernel stefani
2014-01-30 18:21 ` Andy Lutomirski
2014-01-30 19:43 ` Stefani Seibold
2014-01-31 23:12 ` Andy Lutomirski
2014-01-30 15:31 ` [PATCH 0/4] Add 32 bit VDSO time function support H. Peter Anvin
2014-01-30 15:52 ` Stefani Seibold
2014-01-30 15:54 ` H. Peter Anvin
2014-01-30 17:57 ` Andy Lutomirski
2014-01-30 18:03 ` H. Peter Anvin [this message]
2014-01-30 18:08 ` Andy Lutomirski
-- strict thread matches above, loose matches on Subject: below --
2014-02-01 15:32 stefani
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=52EA93E4.6010504@zytor.com \
--to=hpa@zytor.com \
--cc=Andreas.Brief@rohde-schwarz.com \
--cc=Martin.Runge@rohde-schwarz.com \
--cc=aarcange@redhat.com \
--cc=ak@linux.intel.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=gorcunov@openvz.org \
--cc=gregkh@linuxfoundation.org \
--cc=john.stultz@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=mingo@redhat.com \
--cc=stefani@seibold.net \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=xemul@parallels.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.