linux-kernel - Re: [GIT PULL] x86: unify sys

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Message-ID: <4AD4F0C8.9080205@zytor.com>
Date:	Tue, 13 Oct 2009 14:27:36 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] x86: unify sys_iopl

On 10/13/2009 09:53 AM, Jeremy Fitzhardinge wrote:
> On 10/13/09 09:24, H. Peter Anvin wrote:
>> First of all, the unification looks good.
>>
>> As far as .32 is concerned... this *is* a bug even if this is only for
>> paravirt, and given the small amount of code I am personally OK with
>> taking the whole patch for .32.
>>
>> However, the patch is not complete!  The patch incidentally eliminates
>> the need to have assembly stubs for sys_iopl, and those assembly stubs
>> should be removed.  I have a patch for that currently test building.
>>   
> 
> I wasn't sure whether task_pt_regs() needed the full register set to be
> saved to correctly return rflags (that is, does PTREGSCALL change the
> shape of the stack, or just the contents?).
> 

Erk, I was right but still wrong... it isn't safe to modify the partial
pt_regs because of the magic sync stuff that goes on in entry_64.S.

I have to say the entry_64.S stuff gives me a headache in the extreme.
It really can't be the sanest way to do this stuff.

/me makes a mental note to try to work through this code at some point.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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