On i386-PAE, clear_fixmap() results in ill use of set_pte(). In all contexts,
p2m translations shouldn't occur here. Note that this is not really an issue
on native linux, as there is
(a) no pfn-to-mfn translation and
(b) __set_fixmap() takes an unsigned long physical address rather than a
paddr_t, which makes it so that bits 32 and up of the physical address are
always zero, permitting either order store when clearing the entry.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Index: head-2006-11-06/arch/i386/mm/pgtable-xen.c
===================================================================
--- head-2006-11-06.orig/arch/i386/mm/pgtable-xen.c 2006-11-06
09:07:40.000000000 +0100
+++ head-2006-11-06/arch/i386/mm/pgtable-xen.c 2006-11-06 12:22:54.000000000
+0100
@@ -102,8 +102,11 @@ static void set_pte_pfn(unsigned long va
return;
}
pte = pte_offset_kernel(pmd, vaddr);
- /* <pfn,flags> stored as-is, to permit clearing entries */
- set_pte(pte, pfn_pte(pfn, flags));
+ if (pgprot_val(flags))
+ /* <pfn,flags> stored as-is, to permit clearing entries */
+ set_pte(pte, pfn_pte(pfn, flags));
+ else
+ pte_clear(&init_mm, vaddr, pte);
/*
* It's enough to flush this one mapping.
@@ -140,8 +143,11 @@ static void set_pte_pfn_ma(unsigned long
return;
}
pte = pte_offset_kernel(pmd, vaddr);
- /* <pfn,flags> stored as-is, to permit clearing entries */
- set_pte(pte, pfn_pte_ma(pfn, flags));
+ if (pgprot_val(flags))
+ /* <pfn,flags> stored as-is, to permit clearing entries */
+ set_pte(pte, pfn_pte_ma(pfn, flags));
+ else
+ pte_clear(&init_mm, vaddr, pte);
/*
* It's enough to flush this one mapping.
Index: head-2006-11-06/arch/x86_64/mm/init-xen.c
===================================================================
--- head-2006-11-06.orig/arch/x86_64/mm/init-xen.c 2006-11-06
09:10:06.000000000 +0100
+++ head-2006-11-06/arch/x86_64/mm/init-xen.c 2006-11-06 12:19:49.000000000
+0100
@@ -260,7 +260,10 @@ static __init void set_pte_phys(unsigned
return;
}
}
- new_pte = pfn_pte(phys >> PAGE_SHIFT, prot);
+ if (pgprot_val(prot))
+ new_pte = pfn_pte(phys >> PAGE_SHIFT, prot);
+ else
+ new_pte = __pte(0);
pte = pte_offset_kernel(pmd, vaddr);
if (!pte_none(*pte) &&
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