[PATCH 12/33] efi/gop: Use helper macros for find_bits

Ard Biesheuvel
2020-04-24T13:06:43Z

From: Arvind Sankar <nivedita@alum.mit.edu>

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>
---
drivers/firmware/efi/libstub/gop.c | 26 ++++++++------------------
1 file changed, 8 insertions(+), 18 deletions(-)

diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
index 7b0baf9a912f..8bf424f35759 100644
--- 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
--
2.17.1