Add a helper function to convert an arbitrary mapped virtual address to a
physical frame number. Adapted from code by Chris Wright, added support
for large pages.
Because of the placement, this needs to be a macro; pgd_offset_k requires
init_mm to be defined, and getting the include files right seemed more
complicated than a macroized implementation.
A more proper location would be in asm/page.h, but that gets confounded
by the use of pgd_offset_k() again.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Index: linux-2.6.13/include/asm-i386/pgtable.h
==================================================================---
linux-2.6.13.orig/include/asm-i386/pgtable.h 2005-08-24 09:43:27.000000000 -0700
+++ linux-2.6.13/include/asm-i386/pgtable.h 2005-08-24 09:47:38.000000000 -0700
@@ -388,6 +388,28 @@ static inline pte_t pte_modify(pte_t pte
extern pte_t *lookup_address(unsigned long address);
/*
+ * Helper function that returns physical page for virtual address.
+ * This assumes the mapping is valid.
+ */
+#define virt_to_pfn(_address) \
+({ \
+ unsigned long long __paddr; \
+ pgd_t *pgd = pgd_offset_k(_address); \
+ pud_t *pud = pud_offset(pgd, (_address)); \
+ pmd_t *pmd = pmd_offset(pud, (_address)); \
+ if (pmd_large(*pmd)) \
+ __paddr = (pmd_val(*pmd) & LARGE_PAGE_MASK) | \
+ ((_address) & ~LARGE_PAGE_MASK); \
+ else { \
+ pte_t *pte = pte_offset_kernel(pmd, (_address));\
+ __paddr = (pte_val(*pte) & PAGE_MASK) | \
+ ((_address) & ~PAGE_MASK); \
+ } \
+ __paddr >>= PAGE_SHIFT; \
+ __paddr; \
+})
+
+/*
* Make a given kernel text page executable/non-executable.
* Returns the previous executability setting of that page (which
* is used to restore the previous state). Used by the SMP bootup code.
