feat(core): preallocate sys.modules to an appropriate size

core/embed/firmware/mpconfigport.h

@@ -40,6 +40,7 @@
 // memory allocation policies
 #define MICROPY_ALLOC_PATH_MAX      (128)
 #define MICROPY_ENABLE_PYSTACK      (1)
+#define MICROPY_LOADED_MODULES_DICT_SIZE (160)
 
 // emitters
 #define MICROPY_PERSISTENT_CODE_LOAD (0)

core/embed/unix/mpconfigport.h

@@ -45,6 +45,7 @@
 #define MICROPY_MALLOC_USES_ALLOCATED_SIZE (1)
 #define MICROPY_MEM_STATS           (1)
 #define MICROPY_ENABLE_PYSTACK      (1)
+#define MICROPY_LOADED_MODULES_DICT_SIZE (160)
 
 // emitters
 #define MICROPY_PERSISTENT_CODE_LOAD (0)

core/src/trezor/utils.py

@@ -41,6 +41,11 @@ def unimport_begin() -> Set[str]:
 
 
 def unimport_end(mods: Set[str], collect: bool = True) -> None:
+    # static check that the size of sys.modules never grows above value of
+    # MICROPY_LOADED_MODULES_DICT_SIZE, so that the sys.modules dict is never
+    # reallocated at run-time
+    assert len(sys.modules) <= 160, "Please bump preallocated size in mpconfigport.h"
+
     for mod in sys.modules:
         if mod not in mods:
             # remove reference from sys.modules

vendor/micropython

@@ -1 +1 @@
-Subproject commit 3a3068da97ee45b812db61f09af8fefd17dc80f8
+Subproject commit f7e780ae16bc62519e6b78672e43ecae9138ed0a