efi, x86: Rearrange efi_mem_attributes()

x86 and ia64 implement efi_mem_attributes() differently. This
function needs to be available for other architectures
(such as arm64) as well, such as for the purpose of ACPI/APEI.

ia64 EFI does not set up a 'memmap' variable and does not set
the EFI_MEMMAP flag, so it needs to have its unique implementation
of efi_mem_attributes().

Move efi_mem_attributes() implementation from x86 to the core
EFI code, and declare it with __weak.

It is recommended that other architectures should not override
the default implementation.

Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Reviewed-by: Matt Fleming <matt.fleming@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438936621-5215-4-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index d7a9160008d3..afee2880e0fd 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -607,3 +607,34 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
                          attr & EFI_MEMORY_UC      ? "UC"  : "");
         return buf;
 }
+
+/*
+ * efi_mem_attributes - lookup memmap attributes for physical address
+ * @phys_addr: the physical address to lookup
+ *
+ * Search in the EFI memory map for the region covering
+ * @phys_addr. Returns the EFI memory attributes if the region
+ * was found in the memory map, 0 otherwise.
+ *
+ * Despite being marked __weak, most architectures should *not*
+ * override this function. It is __weak solely for the benefit
+ * of ia64 which has a funky EFI memory map that doesn't work
+ * the same way as other architectures.
+ */
+u64 __weak efi_mem_attributes(unsigned long phys_addr)
+{
+        efi_memory_desc_t *md;
+        void *p;
+
+        if (!efi_enabled(EFI_MEMMAP))
+                return 0;
+
+        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
+                md = p;
+                if ((md->phys_addr <= phys_addr) &&
+                    (phys_addr < (md->phys_addr +
+                    (md->num_pages << EFI_PAGE_SHIFT))))
+                        return md->attribute;
+        }
+        return 0;
+}