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, 8 insertions, 7 deletions

diff --git a/utils/hwstub/stub/atj213x/crt0.S b/utils/hwstub/stub/atj213x/crt0.S
index 93cc57fc5e..5a3c81dc78 100644
--- a/utils/hwstub/stub/atj213x/crt0.S
+++ b/utils/hwstub/stub/atj213x/crt0.S
@@ -1,4 +1,5 @@
 #include "mips.h"
+#include "system.h"
 
     .extern main
     .global start
@@ -134,12 +135,12 @@ stack_munge_loop:
     jr.hb t0
     ei
 
-    .extern data_abort_jmp_ctx_ptr
+    .extern exception_jmp_ctx_ptr
     .global tlb_refill_handler
     .section .exception.tlb_refill,"ax",%progbits
 
 tlb_refill_handler:
-    la k1, data_abort_jmp_ctx_ptr
+    la k1, exception_jmp_ctx_ptr
     lw s0,  0(k1)
     lw s1,  4(k1)
     lw s2,  8(k1)
@@ -153,7 +154,7 @@ tlb_refill_handler:
     lw k1, 40(k1)
     mtc0 k1, C0_EPC
     ehb
-    li v0, 1
+    li v0, EXCEPTION_ADDR
     eret
     nop
 
@@ -161,7 +162,7 @@ tlb_refill_handler:
     .section .exception.cache_error,"ax",%progbits
 
 cache_error_handler:
-    la k1, data_abort_jmp_ctx_ptr
+    la k1, exception_jmp_ctx_ptr
     lw s0,  0(k1)
     lw s1,  4(k1)
     lw s2,  8(k1)
@@ -175,7 +176,7 @@ cache_error_handler:
     lw k1, 40(k1)
     mtc0 k1, C0_EPC
     ehb
-    li v0, 1
+    li v0, EXCEPTION_ADDR
     eret
     nop
 
@@ -183,7 +184,7 @@ cache_error_handler:
     .section .exception.general_exception,"ax",%progbits
 
 general_exception_handler:
-    la k1, data_abort_jmp_ctx_ptr
+    la k1, exception_jmp_ctx_ptr
     lw s0,  0(k1)
     lw s1,  4(k1)
     lw s2,  8(k1)
@@ -197,7 +198,7 @@ general_exception_handler:
     lw k1, 40(k1)
     mtc0 k1, C0_EPC
     ehb
-    li v0, 1
+    li v0, EXCEPTION_UNSP
     eret
     nop