[PATCH 1/5] arm64: PIE: Skip fixups if distance is zero

[Andre Przywara]

When the actual offset between link and runtime address is zero, there
is no need for patching up U-Boot early when running with
CONFIG_POSITION_INDEPENDENT.

Skip the whole routine when the distance is 0.

This helps when U-Boot is loaded into ROM, or in otherwise sensitive
memory locations.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 arch/arm/cpu/armv8/start.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
index 002698b501c..02b952bb328 100644
--- a/arch/arm/cpu/armv8/start.S
+++ b/arch/arm/cpu/armv8/start.S
@@ -66,7 +66,8 @@ save_boot_params_ret:
 pie_fixup:
 	adr	x0, _start		/* x0 <- Runtime value of _start */
 	ldr	x1, _TEXT_BASE		/* x1 <- Linked value of _start */
-	sub	x9, x0, x1		/* x9 <- Run-vs-link offset */
+	subs	x9, x0, x1		/* x9 <- Run-vs-link offset */
+	beq	pie_fixup_done
 	adr	x2, __rel_dyn_start	/* x2 <- Runtime &__rel_dyn_start */
 	adr	x3, __rel_dyn_end	/* x3 <- Runtime &__rel_dyn_end */
 pie_fix_loop:
-- 
2.17.5