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 643ccc6960c..07bd02b6c37 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);