atmel-samd: Turn on stack checking so infinite recursion doesn't completely crash.

atmel-samd/main.c

@@ -7,6 +7,7 @@
 #include "py/runtime.h"
 #include "py/repl.h"
 #include "py/gc.h"
+#include "py/stackctrl.h"
 
 #include "lib/fatfs/ff.h"
 #include "lib/fatfs/diskio.h"
@@ -503,6 +504,9 @@ void samd21_init(void) {
     nvm_set_config(&config_nvm);
 }
 
+extern uint32_t _estack;
+extern uint32_t _ebss;
+
 int main(void) {
     // initialise the cpu and peripherals
     samd21_init();
@@ -513,6 +517,11 @@ int main(void) {
     // stack between here and where gc_collect is called.
     stack_top = (char*)&stack_dummy;
 
+    // Stack limit should be less than real stack size, so we have a chance
+    // to recover from limit hit.  (Limit is measured in bytes.)
+    mp_stack_ctrl_init();
+    mp_stack_set_limit((char*)&_estack - (char*)&_ebss - 1024);
+
     // Initialise the local flash filesystem after the gc in case we need to
     // grab memory from it. Create it if needed, mount in on /flash, and set it
     // as current dir.

atmel-samd/mpconfigport.h

@@ -100,6 +100,8 @@
 
 #define MICROPY_MAKE_POINTER_CALLABLE(p) ((void*)((mp_uint_t)(p) | 1))
 
+#define MICROPY_STACK_CHECK         (1)
+
 // This port is intended to be 32-bit, but unfortunately, int32_t for
 // different targets may be defined in different ways - either as int
 // or as long. This requires different printf formatting specifiers