unix: Switch stack limit check to new cstack API.

Necessary to pass CI when testing the V2 preview APIs.

Also adds an extra coverage test for the legacy stackctrl API, to maintain
coverage and check for any regression.

This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>

ports/unix/coverage.c

@@ -7,6 +7,7 @@
 #include "py/objint.h"
 #include "py/objstr.h"
 #include "py/runtime.h"
+#include "py/stackctrl.h"
 #include "py/gc.h"
 #include "py/repl.h"
 #include "py/mpz.h"
@@ -739,6 +740,32 @@ static mp_obj_t extra_coverage(void) {
         mp_printf(&mp_plat_print, "%d %d\n", mp_obj_is_int(MP_OBJ_NEW_SMALL_INT(1)), mp_obj_is_int(mp_obj_new_int_from_ll(1)));
     }
 
+    // Legacy stackctrl.h API, this has been replaced by cstack.h
+    {
+        mp_printf(&mp_plat_print, "# stackctrl\n");
+        char *old_stack_top = MP_STATE_THREAD(stack_top);
+        size_t old_stack_limit = 0;
+        size_t new_stack_limit = SIZE_MAX;
+        #if MICROPY_STACK_CHECK
+        old_stack_limit = MP_STATE_THREAD(stack_limit);
+        MP_STACK_CHECK();
+        #endif
+
+        mp_stack_ctrl_init(); // Will set stack top incorrectly
+        mp_stack_set_top(old_stack_top); // ... and restore it
+
+        #if MICROPY_STACK_CHECK
+        mp_stack_set_limit(MP_STATE_THREAD(stack_limit));
+        MP_STACK_CHECK();
+        new_stack_limit = MP_STATE_THREAD(stack_limit);
+        #endif
+
+        // Nothing should have changed
+        mp_printf(&mp_plat_print, "%d %d\n",
+            old_stack_top == MP_STATE_THREAD(stack_top),
+            MICROPY_STACK_CHECK == 0 || old_stack_limit == new_stack_limit);
+    }
+
     mp_printf(&mp_plat_print, "# end coverage.c\n");
 
     mp_obj_streamtest_t *s = mp_obj_malloc(mp_obj_streamtest_t, &mp_type_stest_fileio);

ports/unix/main.c

@@ -44,7 +44,7 @@
 #include "py/repl.h"
 #include "py/gc.h"
 #include "py/objstr.h"
-#include "py/stackctrl.h"
+#include "py/cstack.h"
 #include "py/mphal.h"
 #include "py/mpthread.h"
 #include "extmod/misc.h"
@@ -468,12 +468,20 @@ int main(int argc, char **argv) {
     #if MICROPY_PY_THREAD
     mp_thread_init();
     #endif
+
+    // Define a reasonable stack limit to detect stack overflow.
+    mp_uint_t stack_size = 40000 * (sizeof(void *) / 4);
+    #if defined(__arm__) && !defined(__thumb2__)
+    // ARM (non-Thumb) architectures require more stack.
+    stack_size *= 2;
+    #endif
+
     // We should capture stack top ASAP after start, and it should be
     // captured guaranteedly before any other stack variables are allocated.
     // For this, actual main (renamed main_) should not be inlined into
     // this function. main_() itself may have other functions inlined (with
     // their own stack variables), that's why we need this main/main_ split.
-    mp_stack_ctrl_init();
+    mp_cstack_init_with_sp_here(stack_size);
     return main_(argc, argv);
 }
 
@@ -492,14 +500,6 @@ MP_NOINLINE int main_(int argc, char **argv) {
     signal(SIGPIPE, SIG_IGN);
     #endif
 
-    // Define a reasonable stack limit to detect stack overflow.
-    mp_uint_t stack_limit = 40000 * (sizeof(void *) / 4);
-    #if defined(__arm__) && !defined(__thumb2__)
-    // ARM (non-Thumb) architectures require more stack.
-    stack_limit *= 2;
-    #endif
-    mp_stack_set_limit(stack_limit);
-
     pre_process_options(argc, argv);
 
     #if MICROPY_ENABLE_GC

tests/ports/unix/extra_coverage.py.exp

@@ -164,6 +164,8 @@ pop all: 1 2 4 5
 1 1
 0 0
 1 1
+# stackctrl
+1 1
 # end coverage.c
 0123456789 b'0123456789'
 7300