Re: [patch 2/4] x86: PAT followup - Remove KERNPG_TABLE from pte entry

Venki Pallipadi
2008-01-17T00:18:35Z

On Wed, Jan 16, 2008 at 10:14:00AM +0200, Mika Penttilä wrote:
> venkatesh.pallipadi@intel.com kirjoitti:
> >KERNPG_TABLE was a bug in earlier patch. Remove it from pte.
> >pte_val() check is redundant as this routine is called immediately after a
> >ptepage is allocated afresh.
> >
> >Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> >Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
> >
> >Index: linux-2.6.git/arch/x86/mm/init_64.c
> >===================================================================
> >--- linux-2.6.git.orig/arch/x86/mm/init_64.c 2008-01-15
> >11:02:23.000000000 -0800
> >+++ linux-2.6.git/arch/x86/mm/init_64.c 2008-01-15
> >11:06:37.000000000 -0800
> >@@ -541,9 +541,6 @@
> > if (address >= end)
> > break;
> >
> >- if (pte_val(*pte))
> >- continue;
> >-
> > /* Nothing to map. Map the null page */
> > if (!(address & (~PAGE_MASK)) &&
> > (address + PAGE_SIZE <= end) &&
> >@@ -561,9 +558,9 @@
> > }
> >
> > if (exec)
> >- entry = _PAGE_NX|_KERNPG_TABLE|_PAGE_GLOBAL|address;
> >+ entry = _PAGE_NX|_PAGE_GLOBAL|address;
> > else
> >- entry = _KERNPG_TABLE|_PAGE_GLOBAL|address;
> >+ entry = _PAGE_GLOBAL|address;
> > entry &= __supported_pte_mask;
> > set_pte(pte, __pte(entry));
> > }
> >
> >
>
> Hmm then what's the point of mapping not present 4k pages for valid mem
> here?
>

Ingo,

Below incremental patch fixes this pte entry setting correctly. Thanks to
Mika for catching this.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

Index: linux-2.6.git/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.git.orig/arch/x86/mm/init_64.c 2008-01-16 03:38:32.000000000 -0800
+++ linux-2.6.git/arch/x86/mm/init_64.c 2008-01-16 03:51:34.000000000 -0800
@@ -515,9 +515,9 @@
}

if (exec)
- entry = _PAGE_NX|_PAGE_GLOBAL|address;
+ entry = __PAGE_KERNEL_EXEC | _PAGE_GLOBAL | address;
else
- entry = _PAGE_GLOBAL|address;
+ entry = __PAGE_KERNEL | _PAGE_GLOBAL | address;
entry &= __supported_pte_mask;
set_pte(pte, __pte(entry));
}