[PATCH v2 2/6] arm64: PIE: Skip fixups if distance is zero

Andre Przywara
2020-09-30T16:39:14Z

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>
---
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