linux-kernel - Re: [PATCH v2 0/4] vDSO fixes, on top of tip/x86/vdso

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Message-ID: <CALCETrW5Z07cn+-r2qnyUDaC_XMujYtcT4zV2ztCOwo4qbfj9w@mail.gmail.com>
Date:	Fri, 28 Feb 2014 12:15:36 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Stefani Seibold <stefani@...bold.net>
Cc:	X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	John Stultz <john.stultz@...aro.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	andriy.shevchenko@...ux.intel.com, Martin.Runge@...de-schwarz.com,
	Andreas.Brief@...de-schwarz.com
Subject: Re: [PATCH v2 0/4] vDSO fixes, on top of tip/x86/vdso

On Thu, Feb 27, 2014 at 11:33 PM, Stefani Seibold <stefani@...bold.net> wrote:
> Am Donnerstag, den 27.02.2014, 16:18 -0800 schrieb Andy Lutomirski:
>> I'd still like someone else to confirm that the 32-bit vDSO is working
>> on all common configurations before I'm happy with it, but this should
>> be a considerable improvement.
>>
>> Someone who maintains the clock code should review the changes in:
>>
>>     commit 0fc8a237cbe98a06962f5ea37d24fc2369e23c74
>>     Author: Stefani Seibold <stefani@...bold.net>
>>     Date:   Wed Feb 19 10:09:10 2014 +0100
>>
>>         x86, vdso: Add 32-bit VDSO time support for the 64-bit kernel
>>
>> very carefully.
>>
>> There's still something extremely questionable about VDSO_PAGES in the
>> 32-bit vDSO code.  It appears to be terminally screwed up, and AFAICS it
>> only works at all because none of the 32-bit vDSO images ever exceed
>> 4096 bytes.
>>
>
> The 4096 bytes limit was not introduced by the patch set. It is still
> there for compatibility reason.

Compatibility with what?  And it doesn't look like there's a sane 4k
"limit".  It looks like the code with confuse itself and crash if the
image exceeds 4k.

But yes, this issue predates your code.

--Andy
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