core: Treat stack overflows as an unrecoverable error

Presently, RIOT just emits a warning when a stack overflow is
encountered but still resumes execution. In my view, execution should be
aborted as the detection of a stack overflows via the heuristic provided
by the scheduler is an unrecoverable error.

I ran into this while performing automated tests of a RIOT application
where a stack overflow occurred but I only noticed this after inspecting
the application output more closely.

Similar to SSP failures, I added crash_code for stack overflows.

core/lib/include/panic.h

@@ -51,6 +51,7 @@ typedef enum {
     PANIC_DUMMY_HANDLER,        /**< unhandled interrupt */
 #endif
     PANIC_SSP,                  /**< stack smashing protector failure */
+    PANIC_STACK_OVERFLOW,       /**< stack overflow detected */
     PANIC_UNDEFINED
 } core_panic_t;
 

core/sched.c

@@ -30,6 +30,7 @@
 #include "log.h"
 #include "sched.h"
 #include "thread.h"
+#include "panic.h"
 
 #ifdef MODULE_MPU_STACK_GUARD
 #include "mpu.h"
@@ -130,9 +131,10 @@ static void _unschedule(thread_t *active_thread)
      */
     if (*((uintptr_t *)(uintptr_t)active_thread->stack_start) !=
         (uintptr_t)active_thread->stack_start) {
-        LOG_WARNING(
+        LOG_ERROR(
             "scheduler(): stack overflow detected, pid=%" PRIkernel_pid "\n",
             active_thread->pid);
+        core_panic(PANIC_STACK_OVERFLOW, "STACK OVERFLOW");
     }
 #endif
 #ifdef MODULE_SCHED_CB