microblaze: Optimize register usage in relocate_code

There are additional operations which can be done simpler that's why
improve logic around relocation address r7 handling and _start symbol.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/c8b60f72f1605c2ba6b4b7be1893d7e6ec3d8597.1655299267.git.michal.simek@amd.com

diff --git a/arch/microblaze/cpu/start.S b/arch/microblaze/cpu/start.S
index 2aae4a0b7ccb7b4c63591efe5e5452e135458c0e..f2d6d12deb73b43bdabfca1bde1f4fa7a1c187cb 100644 (file)
--- a/arch/microblaze/cpu/start.S
+++ b/arch/microblaze/cpu/start.S
@@ -271,7 +271,6 @@ relocate_code:
        mts     rshr, r1
        addi    r31, r6, 0 /* Start to use new GD */
 
-       add     r23, r0, r7 /* Move reloc addr to r23 */
        /* Relocate text and data - r12 temp value */
        addi    r21, r0, _start
        addi    r22, r0, _end /* Include BSS too */
@@ -280,15 +279,13 @@ relocate_code:
        rsub    r6, r21, r22
        or      r5, r0, r0
 1:     lw      r12, r21, r5 /* Load u-boot data */
-       sw      r12, r23, r5 /* Write zero to loc */
+       sw      r12, r7, r5 /* Write zero to loc */
        cmp     r12, r5, r6 /* Check if we have reach the end */
        bneid   r12, 1b
        addi    r5, r5, 4 /* Increment to next loc - relocate code */
 
        /* R23 points to the base address. */
-       add     r23, r0, r7 /* Move reloc addr to r23 */
-       addi    r24, r0, _start /* Get reloc offset */
-       rsub    r23, r24, r23 /* keep - this is already here gd->reloc_off */
+       rsub    r23, r21, r7 /* keep - this is already here gd->reloc_off */
 
        /* Setup vectors with post-relocation symbols */
        add     r5, r0, r23 /* load gd->reloc_off to r5 */