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authorJeremy Fitzhardinge <jeremy@goop.org>2010-10-13 16:02:24 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2010-10-13 16:07:13 -0700
commitfef5ba797991f9335bcfc295942b684f9bf613a1 (patch)
tree25aa49f656def959f5380d1320ebbf1f469e3c07 /arch/x86/mm/ioremap.c
parentc7fc2de0c83dbd2eaf759c5cd0e2b9cf1eb4df3a (diff)
xen: Cope with unmapped pages when initializing kernel pagetable
Xen requires that all pages containing pagetable entries to be mapped read-only. If pages used for the initial pagetable are already mapped then we can change the mapping to RO. However, if they are initially unmapped, we need to make sure that when they are later mapped, they are also mapped RO. We do this by knowing that the kernel pagetable memory is pre-allocated in the range e820_table_start - e820_table_end, so any pfn within this range should be mapped read-only. However, the pagetable setup code early_ioremaps the pages to write their entries, so we must make sure that mappings created in the early_ioremap fixmap area are mapped RW. (Those mappings are removed before the pages are presented to Xen as pagetable pages.) Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> LKML-Reference: <4CB63A80.8060702@goop.org> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/mm/ioremap.c')
-rw-r--r--arch/x86/mm/ioremap.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 3ba6e0608c5..0369843511d 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -362,6 +362,11 @@ static inline pte_t * __init early_ioremap_pte(unsigned long addr)
return &bm_pte[pte_index(addr)];
}
+bool __init is_early_ioremap_ptep(pte_t *ptep)
+{
+ return ptep >= &bm_pte[0] && ptep < &bm_pte[PAGE_SIZE/sizeof(pte_t)];
+}
+
static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;
void __init early_ioremap_init(void)