efi/gop: Use helper macros for find_bits

Use the __ffs/__fls macros to calculate the position and size of the
mask.

Correct type of mask to u32 instead of unsigned long.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200320020028.1936003-9-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
index 7b0baf9..8bf424f 100644 (file)
--- a/drivers/firmware/efi/libstub/gop.c
+++ b/drivers/firmware/efi/libstub/gop.c
@@ -5,6 +5,7 @@
  *
  * ----------------------------------------------------------------------- */
 
+#include <linux/bitops.h>
 #include <linux/efi.h>
 #include <linux/screen_info.h>
 #include <asm/efi.h>
@@ -12,27 +13,16 @@
 
 #include "efistub.h"
 
-static void find_bits(unsigned long mask, u8 *pos, u8 *size)
+static void find_bits(u32 mask, u8 *pos, u8 *size)
 {
-       u8 first, len;
-
-       first = 0;
-       len = 0;
-
-       if (mask) {
-               while (!(mask & 0x1)) {
-                       mask = mask >> 1;
-                       first++;
-               }
-
-               while (mask & 0x1) {
-                       mask = mask >> 1;
-                       len++;
-               }
+       if (!mask) {
+               *pos = *size = 0;
+               return;
        }
 
-       *pos = first;
-       *size = len;
+       /* UEFI spec guarantees that the set bits are contiguous */
+       *pos  = __ffs(mask);
+       *size = __fls(mask) - *pos + 1;
 }
 
 static void