Re: [PATCH v2 05/20] ARM: LPAE: Introduce L_PTE_NOEXEC andL_PTE_NOWRITE

From: Russell King - ARM Linux
Date: Wed Nov 17 2010 - 12:16:43 EST


On Wed, Nov 17, 2010 at 05:02:37PM +0000, Catalin Marinas wrote:
> On 15 November 2010 18:30, Russell King - ARM Linux
> <linux@xxxxxxxxxxxxxxxx> wrote:
> > On Fri, Nov 12, 2010 at 06:00:25PM +0000, Catalin Marinas wrote:
> >> --- a/arch/arm/include/asm/pgtable-2level.h
> >> +++ b/arch/arm/include/asm/pgtable-2level.h
> >> @@ -128,6 +128,8 @@
> >>  #define L_PTE_USER           (1 << 8)
> >>  #define L_PTE_EXEC           (1 << 9)
> >>  #define L_PTE_SHARED         (1 << 10)       /* shared(v6), coherent(xsc3) */
> >> +#define L_PTE_NOEXEC         (0)
> >> +#define L_PTE_NOWRITE                (0)
> >
> > Let's not make this more complicated than it has to be.  If we need the
> > inverse of WRITE and EXEC, then that's what we should change everyone to,
> > not invent a new system to work along side the old system.
>
> Question on the pgprot_noncached/writecombine/dmacoherent - in the
> current implementation we pass L_PTE_EXEC on the dmacoherent macro.

Erm. Please look at the code again.
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