Add simics breakpoint for exceptions

Created a new magic instruction handler that can be enabled via
environment variable to stop the simulation for Hostboot
exceptions.  This is useful when we want to get a backtrace at
the failing spot without recompiling code or having to manually
insert breakpoints in simics directly.

Enable the function by setting HB_BREAK_ON_ERROR
The trigger call is MAGIC_BREAK_ON_ERROR

Change-Id: I17e008281d010e3f8c5e5817e5f30fd0ccb624d0
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/24600
Tested-by: Jenkins Server
Tested-by: FSP CI Jenkins
Reviewed-by: William G. Hoffa <wghoffa@us.ibm.com>
Reviewed-by: Marshall J. Wilks <mjwilks@us.ibm.com>
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>

3 files changed, 21 insertions, 4 deletions

diff --git a/src/build/debug/simics-debug-framework.py b/src/build/debug/simics-debug-framework.py
index 48a8d4818..cae13c134 100755
--- a/src/build/debug/simics-debug-framework.py
+++ b/src/build/debug/simics-debug-framework.py
@@ -485,9 +485,6 @@ except:
 # See src/include/arch/ppc.H for the definitions of the magic args.
 # Hostboot magic args should range 7000..7999.
 def magic_instruction_callback(user_arg, cpu, arg):
-    if arg == 7008:
-        cpu.r3 = random.randint(1, 0xffffffffffffffffL)
-
     if arg == 7006:   # MAGIC_SHUTDOWN
         # KernelMisc::shutdown()
         print "KernelMisc::shutdown() called."
@@ -499,6 +496,9 @@ def magic_instruction_callback(user_arg, cpu, arg):
         # Stop the simulation, much like a hard-coded breakpoint
         SIM_break_simulation( "Simulation stopped. (hap 7007)"  )
 
+    if arg == 7008:
+        cpu.r3 = random.randint(1, 0xffffffffffffffffL)
+
     if arg == 7009:   # MAGIC_MEMORYLEAK_FUNCTION
         magic_memoryleak_function(cpu)
 
@@ -552,6 +552,11 @@ def magic_instruction_callback(user_arg, cpu, arg):
         enableCore1 = "%s; %s; %s; %s"%(enable4,enable5,enable6,enable7)
         SIM_run_alone(run_command, enableCore1 )
 
+    if arg == 7018:   # MAGIC_BREAK_ON_ERROR
+        # Stop the simulation if an env var is set
+        if( os.environ.has_key('HB_BREAK_ON_ERROR') ):
+            SIM_break_simulation( "Stopping sim on HB error. (hap 7018)"  )
+
     if arg == 7055:   # MAGIC_CONTINUOUS_TRACE
         hb_tracBinaryBuffer = cpu.r4
         hb_tracBinaryBufferSz = cpu.r5
diff --git a/src/include/arch/ppc.H b/src/include/arch/ppc.H
index 455728500..7e8b768c2 100644
--- a/src/include/arch/ppc.H
+++ b/src/include/arch/ppc.H
@@ -5,7 +5,7 @@
 /*                                                                        */
 /* OpenPOWER HostBoot Project                                             */
 /*                                                                        */
-/* Contributors Listed Below - COPYRIGHT 2011,2015                        */
+/* Contributors Listed Below - COPYRIGHT 2011,2016                        */
 /* [+] Google Inc.                                                        */
 /* [+] International Business Machines Corp.                              */
 /*                                                                        */
@@ -466,6 +466,8 @@ enum
     MAGIC_WAKE_MASTER_THREAD  =  7015, // Wake master thread
     MAGIC_WAKE_OTHER_THREADS  =  7016, // Wake other threads on initial CORE
     MAGIC_WAKE_FUSED_THREADS  =  7017, // Wake up fused core threads
+    MAGIC_BREAK_ON_ERROR      =  7018, // Breakpoint in error cases if
+                                       //  env var HB_BREAK_ON_ERROR
 
     MAGIC_CONTINUOUS_TRACE    =  7055, // extract mixed trace buffer
 };
diff --git a/src/kernel/exception.C b/src/kernel/exception.C
index 686d3012c..5b891ff63 100644
--- a/src/kernel/exception.C
+++ b/src/kernel/exception.C
@@ -63,6 +63,7 @@ void kernel_execute_prog_ex()
     if (!handled)
     {
         printk("Program exception, killing task %d\n", t->tid);
+        MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
         TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
     }
 }
@@ -102,6 +103,7 @@ void kernel_execute_data_storage()
     {
         printk("Data Storage exception on %d: %lx, %lx @ %p\n",
                t->tid, getDAR(), getDSISR(), t->context.nip);
+        MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
         TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
     }
 }
@@ -112,6 +114,7 @@ void kernel_execute_data_segment()
     task_t* t = TaskManager::getCurrentTask();
     printk("Data Segment exception on %d: %lx @ %p\n",
            t->tid, getDAR(), t->context.nip);
+    MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
     TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
 }
 
@@ -135,6 +138,7 @@ void kernel_execute_inst_storage()
     {
         printk("Inst Storage exception on %d: %lx, %lx\n",
                t->tid, getSRR0(), getSRR1());
+        MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
         TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
     }
 }
@@ -144,6 +148,7 @@ void kernel_execute_inst_segment()
 {
     task_t* t = TaskManager::getCurrentTask();
     printk("Inst Segment exception on %d: %p\n", t->tid, t->context.nip);
+    MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
     TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
 }
 
@@ -152,6 +157,7 @@ void kernel_execute_alignment()
 {
     task_t* t = TaskManager::getCurrentTask();
     printk("Alignment exception, killing task %d\n", t->tid);
+    MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
     TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
 }
 
@@ -161,6 +167,7 @@ void kernel_execute_hype_emu_assist()
     task_t* t = TaskManager::getCurrentTask();
     printk("HypeEmu: Illegal instruction in task %d\n"
            "\tHSSR0 = %lx, HEIR = %lx\n", t->tid, getHSRR0(), getHEIR());
+    MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
     TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
 }
 
@@ -311,6 +318,7 @@ void kernel_execute_machine_check()
                "\tDSISR = %lx, DAR = %lx\n",
                t->tid, getPIR(),
                getSRR0(), getSRR1(), getDSISR(), getDAR());
+        MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
         kassert(false);
     }
 
@@ -366,6 +374,7 @@ void kernel_execute_machine_check()
                 "\tDSISR = %lx, DAR = %lx\n",
                 t->tid, getPIR(),
                 getSRR0(), getSRR1(), getDSISR(), getDAR());
+        MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
         TaskManager::endTask(t, NULL, TASK_STATUS_CRASHED);
     }
 }
@@ -388,6 +397,7 @@ void kernel_execute_unhandled_exception()
 
     printk("Unhandled exception %lx by task %d @ %p\n",
            exception, t->tid, t->context.nip);
+    MAGIC_INSTRUCTION(MAGIC_BREAK_ON_ERROR);
 
     termWriteSRC(TI_UNHANDLED_EX, RC_UNHANDLED_EX, exception);
     terminateExecuteTI();