banner stub: preserve lr, pop-return to caller

2026-09-11 07:15:31 +00:00
parent 61ddf9de6b
commit e473826732
2 changed files with 10 additions and 12 deletions
@@ -1,11 +1,13 @@
    .syntax unified
    .cpu cortex-a7
    .thumb
-    @ Banner stub for SBL1 logger call at 0x802f690 (blx r3 patched to bl here).
-    @ r0 = string. Print raw bytes via UARTDM until NUL (cap 256), return 0.
+    @ Banner stub for SBL1 logger call at 0x802f690 (patched to bl here).
+    @ r0 = string. Print raw bytes via UARTDM until NUL (cap 256).
+    @ Preserve lr (set by bl) and return to caller with r0=0.
    .text
    .global banner_stub
 banner_stub:
+    push {r4, lr}
    movw r3, #0xf000
    movt r3, #0x78a
 bn_loop:
@@ -15,4 +17,4 @@ bn_loop:
    b bn_loop
 bn_done:
    movs r0, #0
-    bx lr
+    pop {r4, pc}