Jan Beulich
2006-Nov-13 11:12 UTC
[Xen-devel] [PATCH, resend] linux/x86: fix clear_fixmap()
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@novell.com> 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) && _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel