linux-kernel - Re: [PATCHv2] x86: Use v8086_mode helper, trivial unification

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Date:	Fri, 18 Jan 2008 01:22:00 -0800
From:	Harvey Harrison <harvey.harrison@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] x86: Use v8086_mode helper, trivial unification

On Fri, 2008-01-18 at 10:12 +0100, Ingo Molnar wrote:
> * Harvey Harrison <harvey.harrison@...il.com> wrote:
> 
> > Use v8086_mode inline in fault_32.c, no functional change also ifdef 
> > the section for 32-bit only and add to fault_64.c
> 
> > -	if (regs->flags & VM_MASK) {
> > +	if (v8086_mode(regs)) {
> 
> > --- a/arch/x86/mm/fault_64.c
> > +++ b/arch/x86/mm/fault_64.c
> > @@ -551,6 +551,16 @@ good_area:
> >  		tsk->maj_flt++;
> >  	else
> >  		tsk->min_flt++;
> > +
> > +	/*
> > +	 * Did it hit the DOS screen memory VA from vm86 mode?
> > +	 */
> > +	if (v8086_mode(regs)) {
> > +		unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT;
> > +		if (bit < 32)
> > +			tsk->thread.screen_bitmap |= 1 << bit;
> > +	}
> 
> hm, is there even vm86 mode in 64-bit? Anyway, gcc will eliminate it i 
> guess. I've applied your patch.
> 

No, it doesn't mean anything to 64-bit, but helps make the diff a little
bit smaller, getting pretty close now.

Still needs a bit of work to introduce oops_begin/end from 64-bit to
32-bit in traps_32.c and introduce a bad_pgtable-like function to
32bit, then we're down to small differences between 32/64 bit
do_page_fault and vmalloc_sync_all that should be relatively clean
to harmonize.

Got distracted with the ptrace stuff today, but patch coming soon.

Harvey

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