Use get top and limit stack functions

Author: kamtom480

main.c

@@ -477,7 +477,7 @@ void gc_collect(void) {
 
     // This naively collects all object references from an approximate stack
     // range.
-    gc_collect_root((void**)sp, ((uint32_t)&_estack - sp) / sizeof(uint32_t));
+    gc_collect_root((void**)sp, ((uint32_t)port_stack_get_top() - sp) / sizeof(uint32_t));
     gc_collect_end();
 }
 

supervisor/shared/memory.c

@@ -25,6 +25,7 @@
  */
 
 #include "supervisor/memory.h"
+#include "supervisor/port.h"
 
 #include <stddef.h>
 
@@ -36,12 +37,10 @@ static supervisor_allocation allocations[CIRCUITPY_SUPERVISOR_ALLOC_COUNT];
 // We use uint32_t* to ensure word (4 byte) alignment.
 uint32_t* low_address;
 uint32_t* high_address;
-extern uint32_t _ebss;
-extern uint32_t _estack;
 
 void memory_init(void) {
-    low_address = &_ebss;
-    high_address = &_estack;
+    low_address = port_stack_get_limit();
+    high_address = port_stack_get_top();
 }
 
 void free_memory(supervisor_allocation* allocation) {

supervisor/shared/stack.c

@@ -29,6 +29,7 @@
 #include "py/mpconfig.h"
 #include "py/runtime.h"
 #include "supervisor/cpu.h"
+#include "supervisor/port.h"
 #include "supervisor/shared/safe_mode.h"
 
 extern uint32_t _estack;
@@ -43,7 +44,7 @@ void allocate_stack(void) {
     mp_uint_t regs[10];
     mp_uint_t sp = cpu_get_regs_and_sp(regs);
 
-    mp_uint_t c_size = (uint32_t) &_estack - sp;
+    mp_uint_t c_size = (uint32_t) port_stack_get_top() - sp;
 
     stack_alloc = allocate_memory(c_size + next_stack_size + EXCEPTION_STACK_SIZE, true);
     if (stack_alloc == NULL) {