linux/x86: utilize lookup_address() for virt_to_ptep()

Index: head-2008-05-08/arch/x86_64/mm/pageattr-xen.c
===================================================================
@@ -276,7 +276,7 @@
 }
 #endif	/* CONFIG_XEN */
 
-static inline pte_t *lookup_address(unsigned long address) 
+pte_t *lookup_address(unsigned long address) 
 { 
 	pgd_t *pgd = pgd_offset_k(address);
 	pud_t *pud;

Index: head-2008-05-08/include/asm-i386/mach-xen/asm/pgtable.h
===================================================================
@@ -477,19 +477,16 @@ void make_page_writable(void *va, unsign
 void make_pages_readonly(void *va, unsigned int nr, unsigned int feature);
 void make_pages_writable(void *va, unsigned int nr, unsigned int feature);
 
-#define virt_to_ptep(__va)						\
-({									\
-	pgd_t *__pgd = pgd_offset_k((unsigned long)(__va));		\
-	pud_t *__pud = pud_offset(__pgd, (unsigned long)(__va));	\
-	pmd_t *__pmd = pmd_offset(__pud, (unsigned long)(__va));	\
-	pte_offset_kernel(__pmd, (unsigned long)(__va));		\
-})
-
-#define arbitrary_virt_to_machine(__va)					\
-({									\
-	maddr_t m = (maddr_t)pte_mfn(*virt_to_ptep(__va)) << PAGE_SHIFT;\
-	m | ((unsigned long)(__va) & (PAGE_SIZE-1));			\
-})
+#define virt_to_ptep(va)						\
+({									\
+	pte_t *__ptep = lookup_address((unsigned long)(va));		\
+	BUG_ON(!__ptep || !pte_present(*__ptep));			\
+	__ptep;								\
+})
+
+#define arbitrary_virt_to_machine(va)					\
+	(((maddr_t)pte_mfn(*virt_to_ptep(va)) << PAGE_SHIFT)		\
+	 | ((unsigned long)(va) & (PAGE_SIZE - 1)))
 
 #endif /* !__ASSEMBLY__ */
 

Index: head-2008-05-08/include/asm-x86_64/mach-xen/asm/pgtable.h
===================================================================
@@ -18,19 +18,18 @@
 
 extern void xen_init_pt(void);
 
-#define virt_to_ptep(__va)						\
-({									\
-	pgd_t *__pgd = pgd_offset_k((unsigned long)(__va));		\
-	pud_t *__pud = pud_offset(__pgd, (unsigned long)(__va));	\
-	pmd_t *__pmd = pmd_offset(__pud, (unsigned long)(__va));	\
-	pte_offset_kernel(__pmd, (unsigned long)(__va));		\
-})
-
-#define arbitrary_virt_to_machine(__va)					\
-({									\
-	maddr_t m = (maddr_t)pte_mfn(*virt_to_ptep(__va)) << PAGE_SHIFT;\
-	m | ((unsigned long)(__va) & (PAGE_SIZE-1));			\
-})
+extern pte_t *lookup_address(unsigned long address);
+
+#define virt_to_ptep(va)						\
+({									\
+	pte_t *__ptep = lookup_address((unsigned long)(va));		\
+	BUG_ON(!__ptep || !pte_present(*__ptep));			\
+	__ptep;								\
+})
+
+#define arbitrary_virt_to_machine(va)					\
+	(((maddr_t)pte_mfn(*virt_to_ptep(va)) << PAGE_SHIFT)		\
+	 | ((unsigned long)(va) & (PAGE_SIZE - 1)))
 #endif
 
 extern pud_t level3_kernel_pgt[512];