Merge pull request #15338 from s-hadinger/berry_stack_resize

Berry stack resize debug mode

lib/libesp32/berry/default/berry_conf.h

@@ -175,6 +175,14 @@
  **/
 #define BE_USE_DEBUG_GC                  0
 
+/* Macro: BE_USE_DEBUG_STACK
+ * Enable Stack Resize debug mode. At each function call
+ * the stack is reallocated at a different memory location
+ * and the previous location is cleared with toxic data.
+ * Default: 0
+ **/
+#define BE_USE_DEBUG_STACK               0
+
 /* Macro: BE_USE_MEM_ALIGNED
  * Some embedded processors have special memory areas
  * with read/write constraints of being aligned to 32 bits boundaries.

lib/libesp32/berry/src/be_exec.c

@@ -15,6 +15,7 @@
 #include "be_bytecode.h"
 #include "be_decoder.h"
 #include <stdlib.h>
+#include <string.h>
 
 #if !BE_USE_SCRIPT_COMPILER && !BE_USE_BYTECODE_LOADER
   #error no compiler or bytecode loader enabled.
@@ -337,9 +338,13 @@ void be_stackpush(bvm *vm)
 /* check that the stack is able to store `count` items, and increase stack if needed */
 BERRY_API void be_stack_require(bvm *vm, int count)
 {
+#if BE_USE_DEBUG_STACK == 0
     if (vm->top + count >= vm->stacktop) {
         be_stack_expansion(vm, count);
     }
+#else
+    be_stack_expansion(vm, vm->top - vm->stacktop + count);     /* force exact resize each time */
+#endif
 }
 
 /* Scan the entire callstack and adjust all pointer by `offset` */
@@ -372,7 +377,16 @@ static void stack_resize(bvm *vm, size_t size)
     intptr_t offset;
     bvalue *old = vm->stack;  /* save original pointer of stack before resize */
     size_t os = (vm->stacktop - old) * sizeof(bvalue);  /* size of current stack allocated in bytes */
+#if BE_USE_DEBUG_STACK == 0
     vm->stack = be_realloc(vm, old, os, sizeof(bvalue) * size);  /* reallocate with the new size */
+#else   /* force a reallocation */
+    size_t ns = sizeof(bvalue) * size;
+    vm->stack = be_malloc(vm, ns);
+    size_t transf = (os < ns) ? os : ns;        /* min size */
+    memmove(vm->stack, old, transf);            /* copy to new location */
+    memset(old, 0xFF, os);                      /* fill the structure with invalid pointers */
+    be_free(vm, old, os);
+#endif
     vm->stacktop = vm->stack + size;  /* compute new stacktop */
     offset = ptr_offset(vm->stack, old);  /* compute the address difference between old and ne stack addresses */
     /* update callframes */
@@ -386,7 +400,7 @@ static void stack_resize(bvm *vm, size_t size)
 /* Check if we are above the max allowed stack */
 void be_stack_expansion(bvm *vm, int n)
 {
-    size_t size = vm->stacktop - vm->stack;
+    int size = vm->stacktop - vm->stack;    /* with debug enabled, stack increase may be negative */
     /* check new stack size */
     if (size + n > BE_STACK_TOTAL_MAX) {
         /* ensure the stack is enough when generating error messages. */

lib/libesp32/berry/src/be_vm.c

@@ -1207,11 +1207,12 @@ static void prep_closure(bvm *vm, int pos, int argc, int mode)
     for (v = vm->reg + argc; v <= end; ++v) {
         var_setnil(v);
     }
+    int v_offset = v - vm->stack;   /* offset from stack base, stack may be reallocated */
     if (proto->varg & BE_VA_VARARG) {  /* there are vararg at the last argument, build the list */
         /* code below uses mostly low-level calls for performance */
-        be_stack_require(vm, argc + 2);   /* make sure we don't overflow the stack */
-        bvalue *top_save = vm->top;  /* save original stack, we need fresh slots to create the 'list' instance */
-        vm->top = v;  /* move top of stack right after last argument */
+        be_stack_require(vm, argc + 4);   /* make sure we don't overflow the stack */
+        int top_save_offset = vm->top - vm->stack;  /* save original stack, we need fresh slots to create the 'list' instance */
+        vm->top = vm->stack + v_offset;  /* move top of stack right after last argument */
         be_newobject(vm, "list");  /* this creates 2 objects on stack: list instance, BE_LIST object */
         blist *list = var_toobj(vm->top-1);  /* get low-level BE_LIST structure */
         v = vm->reg + proto->argc - 1;  /* last argument */
@@ -1219,7 +1220,7 @@ static void prep_closure(bvm *vm, int pos, int argc, int mode)
             be_list_push(vm, list, v); /* push all varargs into list */       
         }
         *(vm->reg + proto->argc - 1) = *(vm->top-2);  /* change the vararg argument to now contain the list instance */
-        vm->top = top_save;  /* restore top of stack pointer */
+        vm->top = vm->stack + top_save_offset;  /* restore top of stack pointer */
     }
 }