Pull rework-memory-attribute-aliasing into release branch

1 files changed, 22 insertions, 5 deletions

diff --git a/arch/ia64/mm/ioremap.c b/arch/ia64/mm/ioremap.c
index 643ccc6960ce..07bd02b6c372 100644
--- a/arch/ia64/mm/ioremap.c
+++ b/arch/ia64/mm/ioremap.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/efi.h>
 #include <asm/io.h>
+#include <asm/meminit.h>
 
 static inline void __iomem *
 __ioremap (unsigned long offset, unsigned long size)
@@ -21,16 +22,29 @@ __ioremap (unsigned long offset, unsigned long size)
 void __iomem *
 ioremap (unsigned long offset, unsigned long size)
 {
-        if (efi_mem_attribute_range(offset, size, EFI_MEMORY_WB))
-                return phys_to_virt(offset);
+        u64 attr;
+        unsigned long gran_base, gran_size;
 
-        if (efi_mem_attribute_range(offset, size, EFI_MEMORY_UC))
+        /*
+         * For things in kern_memmap, we must use the same attribute
+         * as the rest of the kernel.  For more details, see
+         * Documentation/ia64/aliasing.txt.
+         */
+        attr = kern_mem_attribute(offset, size);
+        if (attr & EFI_MEMORY_WB)
+                return phys_to_virt(offset);
+        else if (attr & EFI_MEMORY_UC)
                 return __ioremap(offset, size);
 
         /*
-         * Someday this should check ACPI resources so we
-         * can do the right thing for hot-plugged regions.
+         * Some chipsets don't support UC access to memory.  If
+         * WB is supported for the whole granule, we prefer that.
          */
+        gran_base = GRANULEROUNDDOWN(offset);
+        gran_size = GRANULEROUNDUP(offset + size) - gran_base;
+        if (efi_mem_attribute(gran_base, gran_size) & EFI_MEMORY_WB)
+                return phys_to_virt(offset);
+
         return __ioremap(offset, size);
 }
 EXPORT_SYMBOL(ioremap);
@@ -38,6 +52,9 @@ EXPORT_SYMBOL(ioremap);
 void __iomem *
 ioremap_nocache (unsigned long offset, unsigned long size)
 {
+        if (kern_mem_attribute(offset, size) & EFI_MEMORY_WB)
+                return 0;
+
         return __ioremap(offset, size);
 }
 EXPORT_SYMBOL(ioremap_nocache);