1 files changed, 19 insertions, 15 deletions

diff --git a/firmware/target/arm/s5l8702/crt0.S b/firmware/target/arm/s5l8702/crt0.S
index da2f49c971..e894e8f157 100644
--- a/firmware/target/arm/s5l8702/crt0.S
+++ b/firmware/target/arm/s5l8702/crt0.S
@@ -150,15 +150,6 @@ start_loc:
     bhi     1b
 #endif
 
-    /* Set up some stack and munge it with 0xdeadbeef */
-    ldr     sp, =stackend
-    ldr     r2, =stackbegin
-    ldr     r3, =0xdeadbeef
-1:
-    cmp     sp, r2
-    strhi   r3, [r2], #4
-    bhi     1b
-
     /* Set up stack for IRQ mode */ 
     msr     cpsr_c, #0xd2
     ldr     sp, =_irqstackend
@@ -167,14 +158,25 @@ start_loc:
     msr     cpsr_c, #0xd1
     ldr     sp, =_fiqstackend
 
-    /* Let abort and undefined modes use IRQ stack */
+    /* Let svc, abort and undefined modes use irq stack */
+    msr     cpsr_c, #0xd3
+    ldr     sp, =_irqstackend
     msr     cpsr_c, #0xd7
     ldr     sp, =_irqstackend
     msr     cpsr_c, #0xdb
     ldr     sp, =_irqstackend
 
-    /* Switch back to supervisor mode */
-    msr     cpsr_c, #0xd3
+    /* Switch to sys mode */
+    msr     cpsr_c, #0xdf
+
+    /* Set up some stack and munge it with 0xdeadbeef */
+    ldr     sp, =stackend
+    ldr     r2, =stackbegin
+    ldr     r3, =0xdeadbeef
+1:
+    cmp     sp, r2
+    strhi   r3, [r2], #4
+    bhi     1b
 
     bl      main
 
@@ -190,11 +192,13 @@ undef_instr_handler:
     mov    r1, #0
     b      UIE
 
-/* We run supervisor mode most of the time, and should never see a software
- * exception being thrown. Perhaps make it illegal and call UIE? */
+/* We run sys mode most of the time, and should never see a software
+ * exception being thrown. Make it illegal and call UIE. */
 software_int_handler:
 reserved_handler:
-    movs   pc, lr
+    sub    r0, lr, #4
+    mov    r1, #4
+    b      UIE
 
 prefetch_abort_handler:
     sub    r0, lr, #4