linux-kernel - Re: [PATCH 4/5] x86: add executable mapping support to ioremap

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Date:	Thu, 31 Jan 2008 17:28:11 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	huang ying <huang.ying.caritas@...il.com>
cc:	"Huang, Ying" <ying.huang@...el.com>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] x86: add executable mapping support to ioremap

On Thu, 31 Jan 2008, huang ying wrote:

> On Jan 31, 2008 9:00 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> > On Thu, 31 Jan 2008, Huang, Ying wrote:
> >
> > > This patch makes ioremap() can be used to map pages as executable,
> > > this is needed by EFI support.
> >
> > > +extern void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
> > > +                            enum ioremap_mode mode,
> > > +                            enum ioremap_xmode xmode);
> > > +
> >
> > Why do you want to add a new API?
> >
> >     addr = ioremap(phys_addr, len);
> >     set_memory_x(addr);
> >
> > should do what you want already. I think Arjan was not very clear in
> > his reply yesterday.
> 
> In current implementation, change_page_attr() can be used to change
> identity map only.  At least I can find __pa() are used in
> change_page_attr_addr() to get physical address. So I think
> change_page_attr() should be fixed firstly.

There is nothing to fix. It works on virtual addresses. 

The __pa() in change_page_attr_addr() is only used to check for the
high alias mapping of the kernel, but the call to change_page_attr
uses the virtual address.

Thanks,

     tglx
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