powerpc/32: Make clear_fixmap actually work

The clear_fixmap() routine issues map_page() with flags set to 0. Currently this causes a BUG_ON() inside the map_page(), as it assumes that a PTE should be clear before mapping.

This patch makes the map_page() to trigger the BUG_ON() only if the flags were set.

Signed-off-by Anton Vorontsov <[email protected]>

---
arch/powerpc/mm/pgtable_32.c | 3 ++-

1 files changed, 2 insertions(+), 1 deletions(-)

arch/powerpc/mm/pgtable_32.c +2 -1

index 3414724..23553a7 100644
@@ -259,7 +259,8 @@ int map_page(unsigned long va, phys_addr_t pa,  
 int flags)
 		/* The PTE should never be already set nor present in the
 		 * hash table
 		 */
-		BUG_ON(pte_val(*pg) & (_PAGE_PRESENT | _PAGE_HASHPTE));
+		BUG_ON((pte_val(*pg) & (_PAGE_PRESENT | _PAGE_HASHPTE)) &&
+		       flags);
 		set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
 						     __pgprot(flags)));

	}