S12v4 smart dispatcher baked

tools/sbl_uni.py

@@ -385,14 +385,16 @@ def main():
     # to the dispatcher via stale lr (TZ bringup deferred).
     # NOTE: overwrites 4B of real ARM trampoline (recoverable from ELF).
     mu.mem_write(0x00221EF8, bytes([0x00, 0x20, 0x70, 0x47]))
-    # S12-stub (b25): blx #0x8006964 (BLX-imm to even => ARM mode!) lands
-    # in file-zero padding (PBL would place an ARM helper). ARM version:
-    # ldr ip,[sp,#4] (=pushed lr, for the B66 bx-ip chain); ldr r3,[pc]
-    # (literal [0x8006980] = 0x073A100); ACK peripheral bit1 (the real
-    # helper's side effect that poll#2 waits for); bx lr.
+    # S12-stub (b27, 84B @0x08006964, ARM): blx-to-padding becomes
+    # smart dispatcher: ldr ip,[sp,#4] (=pushed lr); ip==STUBV/even/
+    # non-code => ip=poll resumption 0x8007779; else keep pushed-lr;
+    # then ACK peripheral bit1 ([literal 0x073A100]); bx lr.
+    # PBL would place the real ARM helper here.
     mu.mem_write(0x08006964, bytes.fromhex(
-        "04c09de50c309fe5002093e5022082e3002083e51eff2fe1"
-        "00a17300"))
+        "04c09de58d3b06e3003840e303005ce10700000a0100"
+        "1ce30500000a2c3ca0e1080053e30400000a2c3ea0e1"
+        "080053e30100000a79c707e300c840e30c309fe50020"
+        "93e5022082e3002083e51eff2fe100a17300"))
     # S16-stublet (b27, 64B @0x08006CC0): smart return for B66 bx ip.
     # ip==STUBV (fill/maze, never a legit return) => default;
     # ip odd + top 8 (code) => add sp,#8 (pop the helper frame B66