linux-kernel - Re: [GIT PULL] x86/paravirt for v2.6.33

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Date:	Wed, 9 Dec 2009 08:36:32 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] x86/paravirt for v2.6.33


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Thu, 3 Dec 2009, Ingo Molnar wrote:
> > 
> > Please pull the latest x86-paravirt-for-linus git tree from:
> > 
> >    git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-paravirt-for-linus
> 
> I _really_ don't like this:
> 
> > -long sys_iopl(struct pt_regs *regs)
> > +asmlinkage long sys_iopl(unsigned int level)
> >  {
> > -	unsigned int level = regs->bx;
> >  	struct thread_struct *t = &current->thread;
> > +	struct pt_regs *regs = task_pt_regs(current);
> 
> I do _not_ want to add any more task_pt_regs() crap, please.
> 
> Why? It's wrong for at least vm86 mode (and from kernel system calls). 
> Maybe we can't get into system calls from vm86 mode, and the kernel 
> hopefully doesn't do those things anyway, but the point is, you chose 
> the wrong way to go.
> 
> The old version that actually passed the stack frame was better. Why 
> pick the inferior version?

Yeah, agreed. I missed that detail.

Jeremy, mind sending a patch that updates this code to use the less 
obfuscated 32-bit version, not the 64-bit version? (a delta patch 
against tip:master would be nice, as there's a fair amount of testing in 
the unification change itself already, which we dont want to discard.)

Thanks,

	Ingo
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