Subject: Re: [PATCH] powerpc/mm: Merge various PTE bits and accessors definitions

From: Benjamin Herrenschmidt <[email-masked]>
Date: Mon, 02 Mar 2009 18:57:52 +1100

On Mon, 2009-03-02 at 18:38 +1100, Michael Ellerman wrote:
> On Mon, 2009-03-02 at 17:22 +1100, Benjamin Herrenschmidt wrote:
> > Now that they are almost identical, we can merge some of the definitions
> > related to the PTE format into common files.
> 
> <snip>
> 
> > +/* Protection used for kernel text. We want the debuggers to be able to
> > + * set breakpoints anywhere, so don't write protect the kernel text
> > + * on platforms where such control is possible.
> > + */
> > +#if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) ||\
> > +	defined(CONFIG_KPROBES)
> > +#define PAGE_KERNEL_TEXT	PAGE_KERNEL_X
> > +#else
> > +#define PAGE_KERNEL_TEXT	PAGE_KERNEL_ROX
> > +#endif
> 
> What about FTRACE? ∞TRACE etc.

Well, I'm just moving those bits around from pgtable-ppc32.h (ie, only
ppc32 uses PAGE_KERNEL_TEXT for now anyway).

Note also that as it is, with ppc32 hash, we don't honor the read-only
restriction on the BAT mapping anyway.

So yes, there's room for fixing things but that isn't what this patch
does.

Cheers,
Ben.