x86, realmode: Pointer walk cleanups, pull out invariant use of __pa()

The pointer arithmetic in this function was really bizarre, where in
fact all we really wanted was a simple pointer array walk.  Use the
much more idiomatic construction for that (*ptr++).

Factor an invariant use of __pa() out of the relocation loop.  At
least on 64 bits it seems gcc isn't capable of doing that
automatically.

Change the scope of a couple of variables to make it extra obvious
that they are extremely local temp variables.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-rd908t9c8kvcojdabtmm94mb@git.kernel.org

1 files changed, 12 insertions, 14 deletions

diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index a44f457e70a1..bad628a620c4 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -29,12 +29,10 @@ void __init reserve_real_mode(void)
 void __init setup_real_mode(void)
 {
         u16 real_mode_seg;
-        u32 *rel;
+        const u32 *rel;
         u32 count;
-        u32 *ptr;
-        u16 *seg;
-        int i;
         unsigned char *base;
+        unsigned long phys_base;
         struct trampoline_header *trampoline_header;
         size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 #ifdef CONFIG_X86_64
@@ -46,23 +44,23 @@ void __init setup_real_mode(void)
 
         memcpy(base, real_mode_blob, size);
 
-        real_mode_seg = __pa(base) >> 4;
+        phys_base = __pa(base);
+        real_mode_seg = phys_base >> 4;
+
         rel = (u32 *) real_mode_relocs;
 
         /* 16-bit segment relocations. */
-        count = rel[0];
-        rel = &rel[1];
-        for (i = 0; i < count; i++) {
-                seg = (u16 *) (base + rel[i]);
+        count = *rel++;
+        while (count--) {
+                u16 *seg = (u16 *) (base + *rel++);
                 *seg = real_mode_seg;
         }
 
         /* 32-bit linear relocations. */
-        count = rel[i];
-        rel =  &rel[i + 1];
-        for (i = 0; i < count; i++) {
-                ptr = (u32 *) (base + rel[i]);
-                *ptr += __pa(base);
+        count = *rel++;
+        while (count--) {
+                u32 *ptr = (u32 *) (base + *rel++);
+                *ptr += phys_base;
         }
 
         /* Must be perfomed *after* relocation. */