arm64: support running at addr other than linked to

[u-boot] / arch / arm / cpu / armv8 / start.S

diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
index 5c500be51d1f5fb616e04539e5fd2cb9e7287e3b..03e744e4a673a27115c29e001c295037d75548d1 100644 (file)
--- a/arch/arm/cpu/armv8/start.S
+++ b/arch/arm/cpu/armv8/start.S
@@ -57,6 +57,32 @@ reset:
 .globl save_boot_params_ret
 save_boot_params_ret:
 
+#if CONFIG_POSITION_INDEPENDENT
+       /*
+        * Fix .rela.dyn relocations. This allows U-Boot to be loaded to and
+        * executed at a different address than it was linked at.
+        */
+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 */
+       adr     x2, __rel_dyn_start     /* x2 <- Runtime &__rel_dyn_start */
+       adr     x3, __rel_dyn_end       /* x3 <- Runtime &__rel_dyn_end */
+pie_fix_loop:
+       ldp     x0, x1, [x2], #16       /* (x0, x1) <- (Link location, fixup) */
+       ldr     x4, [x2], #8            /* x4 <- addend */
+       cmp     w1, #1027               /* relative fixup? */
+       bne     pie_skip_reloc
+       /* relative fix: store addend plus offset at dest location */
+       add     x0, x0, x9
+       add     x4, x4, x9
+       str     x4, [x0]
+pie_skip_reloc:
+       cmp     x2, x3
+       b.lo    pie_fix_loop
+pie_fixup_done:
+#endif
+
 #ifdef CONFIG_SYS_RESET_SCTRL
        bl reset_sctrl
 #endif