1 files changed, 11 insertions, 5 deletions

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 14f9890eb495..635f03bb4995 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -118,14 +118,20 @@ enum fixed_addresses {
          * 256 temporary boot-time mappings, used by early_ioremap(),
          * before ioremap() is functional.
          *
-         * We round it up to the next 256 pages boundary so that we
-         * can have a single pgd entry and a single pte table:
+         * If necessary we round it up to the next 256 pages boundary so
+         * that we can have a single pgd entry and a single pte table:
          */
 #define NR_FIX_BTMAPS           64
 #define FIX_BTMAPS_SLOTS        4
-        FIX_BTMAP_END = __end_of_permanent_fixed_addresses + 256 -
-                        (__end_of_permanent_fixed_addresses & 255),
-        FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS*FIX_BTMAPS_SLOTS - 1,
+#define TOTAL_FIX_BTMAPS        (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
+        FIX_BTMAP_END =
+         (__end_of_permanent_fixed_addresses ^
+          (__end_of_permanent_fixed_addresses + TOTAL_FIX_BTMAPS - 1)) &
+         -PTRS_PER_PTE
+         ? __end_of_permanent_fixed_addresses + TOTAL_FIX_BTMAPS -
+           (__end_of_permanent_fixed_addresses & (TOTAL_FIX_BTMAPS - 1))
+         : __end_of_permanent_fixed_addresses,
+        FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
         FIX_OHCI1394_BASE,
 #endif