py/runtime: mp_stack_ctrl_init() should be called immediately on startup.

Calling it from mp_init() is too late for some ports (like Unix), and leads
to incomplete stack frame being captured, with following GC issues. So, now
each port should call mp_stack_ctrl_init() on its own, ASAP after startup,
and taking special precautions so it really was called before stack variables
get allocated (because if such variable with a pointer is missed, it may lead
to over-collecting (typical symptom is segfaulting)).

2 files changed, 16 insertions, 0 deletions

diff --git a/unix/main.c b/unix/main.c
index 03902a3e9..4ba68dcb9 100644
--- a/unix/main.c
+++ b/unix/main.c
@@ -376,7 +376,19 @@ STATIC void set_sys_argv(char *argv[], int argc, int start_arg) {
 #define PATHLIST_SEP_CHAR ':'
 #endif
 
+MP_NOINLINE int main_(int argc, char **argv);
+
 int main(int argc, char **argv) {
+    // 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();
+    return main_(argc, argv);
+}
+
+MP_NOINLINE int main_(int argc, char **argv) {
     mp_stack_set_limit(40000 * (BYTES_PER_WORD / 4));
 
     pre_process_options(argc, argv);
diff --git a/unix/mpconfigport.h b/unix/mpconfigport.h
index 2f992fdf0..f7fdeec07 100644
--- a/unix/mpconfigport.h
+++ b/unix/mpconfigport.h
@@ -214,6 +214,10 @@ void mp_unix_mark_exec(void);
 #define MP_PLAT_ALLOC_EXEC(min_size, ptr, size) mp_unix_alloc_exec(min_size, ptr, size)
 #define MP_PLAT_FREE_EXEC(ptr, size) mp_unix_free_exec(ptr, size)
 
+#ifndef MP_NOINLINE
+#define MP_NOINLINE __attribute__((noinline))
+#endif
+
 #if MICROPY_PY_OS_DUPTERM
 #define MP_PLAT_PRINT_STRN(str, len) mp_hal_stdout_tx_strn_cooked(str, len)
 #else