Rework safe mode and have heap overwrite trigger it.

This creates a common safe mode mechanic that ports can share.
As a result, the nRF52 now has safe mode support as well.

The common safe mode adds a 700ms delay at startup where a reset
during that window will cause a reset into safe mode. This window
is designated by a yellow status pixel and flashing the single led
three times.

A couple NeoPixel fixes are included for the nRF52 as well.

Fixes #1034. Fixes #990. Fixes #615.

1 files changed, 2 insertions, 5 deletions

diff --git a/supervisor/shared/stack.c b/supervisor/shared/stack.c
index 8f4da4ce6..71e239c0a 100755
--- a/supervisor/shared/stack.c
+++ b/supervisor/shared/stack.c
@@ -29,6 +29,7 @@
 #include "py/mpconfig.h"
 #include "py/runtime.h"
 #include "supervisor/cpu.h"
+#include "supervisor/shared/safe_mode.h"
 
 extern uint32_t _estack;
 
@@ -38,8 +39,6 @@ supervisor_allocation* stack_alloc = NULL;
 
 #define EXCEPTION_STACK_SIZE 1024
 
-#define STACK_CANARY_VALUE 0x017829ef
-
 void allocate_stack(void) {
     mp_uint_t regs[10];
     mp_uint_t sp = cpu_get_regs_and_sp(regs);
@@ -62,9 +61,7 @@ inline bool stack_ok(void) {
 
 inline void assert_heap_ok(void) {
     if (!stack_ok()) {
-        asm("nop");
-        while(true) {}
-        mp_raise_RuntimeError(translate("Stack clobbered heap."));
+        reset_into_safe_mode(HEAP_OVERWRITTEN);
     }
 }