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arm64: PIE: Skip fixups if distance is zero

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@arm.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Andre Przywara 3 years ago
parent
commit
9a984f100e
1 changed files with 2 additions and 1 deletions
  1. 2 1
      arch/arm/cpu/armv8/start.S

+ 2 - 1
arch/arm/cpu/armv8/start.S

@@ -83,7 +83,8 @@ 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
 	adrp    x2, __rel_dyn_start     /* x2 <- Runtime &__rel_dyn_start */
 	add     x2, x2, #:lo12:__rel_dyn_start
 	adrp    x3, __rel_dyn_end       /* x3 <- Runtime &__rel_dyn_end */