hwstub: rewrite exception catching

Since we can catch exceptions like data aborts on read/write, it takes very
little to also catch exceptions in calls. When extending this with the catching
of illegal instructions, the call instruction now becomes much more robust and
also for address and instruction probing. Since we can catch several types of
exception, rename set_data_abort_jmp to set_exception_jmp. At the same time,
simplify the logic in read/write request handlers. Also fix a bug in ARM
jump code: it was using
  stmia r1, {..., pc}
as if pc would get current pc + 8 but this is actually implementation defined
on older ARMs (typically pc + 12) and deprecated on newer ARMs, so rewrite the
code avoid that. The set_exception_jmp() function now also reports the exception
type.

Change-Id: Icd0dd52d2456b361b27c4776be09c3d13528ed93

1 files changed, 10 insertions, 5 deletions

diff --git a/utils/hwstub/stub/jz4760b/crt0.S b/utils/hwstub/stub/jz4760b/crt0.S
index 94d95b3e73..4e1bcc5dbc 100644
--- a/utils/hwstub/stub/jz4760b/crt0.S
+++ b/utils/hwstub/stub/jz4760b/crt0.S
@@ -1,4 +1,5 @@
 #include "mips.h"
+#include "system.h"
 
 .extern main
 .global start
@@ -137,26 +138,30 @@ die_blink:
     j       .blink_loop
     nop
 
-/* restore_data_abort_jmp restores the context and returns from exception */
-    .extern restore_data_abort_jmp
+/* restore_exception_jmp restores the context and returns from exception, it takes
+ * as argument the type of exception */
+    .extern restore_exception_jmp
 
     .global tlb_refill_handler
     .section .exception.tlb_refill,"ax",%progbits
 tlb_refill_handler:
-    la      k0, restore_data_abort_jmp
+    li      a0, EXCEPTION_ADDR
+    la      k0, restore_exception_jmp
     jr      k0
     nop
 
     .global cache_error_handler
     .section .exception.cache_error,"ax",%progbits
 cache_error_handler:
-    la      k0, restore_data_abort_jmp
+    li      a0, EXCEPTION_ADDR
+    la      k0, restore_exception_jmp
     jr      k0
     nop
 
     .global general_exception_handler
     .section .exception.general_exception,"ax",%progbits
 general_exception_handler:
-    la      k0, restore_data_abort_jmp
+    li      a0, EXCEPTION_UNSP
+    la      k0, restore_exception_jmp
     jr      k0
     nop