linux-kernel - Re: [PATCH v4 1/6] x86-64: Clean up vdso/kernel shared variables

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Message-ID: <BANLkTikjFnRv-TJYZEuF=6WZ4S-VomDH4w@mail.gmail.com>
Date:	Mon, 16 May 2011 13:34:09 -0400
From:	Andrew Lutomirski <luto@....edu>
To:	Borislav Petkov <bp@...64.org>
Cc:	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v4 1/6] x86-64: Clean up vdso/kernel shared variables

On Mon, May 16, 2011 at 1:23 PM, Borislav Petkov <bp@...64.org> wrote:
> On Mon, May 16, 2011 at 12:00:58PM -0400, Andy Lutomirski wrote:
>> Variables that are shared between the vdso and the kernel are
>> currently a bit of a mess.  They are each defined with their own
>> magic, they are accessed differently in the kernel, the vsyscall page,
>> and the vdso, and one of them (vsyscall_clock) doesn't even really
>> exist.
>>
>> This changes them all to use a common mechanism.  All of them are
>> delcared in vvar.h with a fixed address (validated by the linker
>> script).  In the kernel (as before), they look like ordinary
>> read-write variables.  In the vsyscall page and the vdso, they are
>> accessed through a new macro VVAR, which gives read-only access.
>>
>> The vdso is now loaded verbatim into memory without any fixups.  As a
>> side bonus, access from the vdso is faster because a level of
>> indirection is removed.
>>
>> While we're at it, pack jiffies and vgetcpu_mode into the same
>> cacheline.
>
> How about
>
> Signed-off-by:...

Signed-off-by: Andy Lutomirski <luto@....edu>

If whoever wants to pick up these patches wants it (or if there's a
v5), I'll send a new patch.

>
> or you don't wanna? :)

Nope.  I probably just hit the delete button too hard or something.

--Andy
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