[GitHub] [incubator-nuttx] gustavonihei commented on a change in pull request #3517: arch: Allocate the space from the beginning in up_stack_frame

[GitBox <gi...@apache.org>]

gustavonihei commented on a change in pull request #3517:
URL: https://github.com/apache/incubator-nuttx/pull/3517#discussion_r611905418



##########
File path: arch/arm/src/common/arm_vfork.c
##########
@@ -167,26 +146,27 @@ pid_t up_vfork(const struct vfork_s *context)
    * effort is overkill.
    */
 
-  newsp = (uint32_t)child->cmn.adj_stack_ptr - stackutil;
+  newtop = (uint32_t)child->cmn.adj_stack_ptr +
+                     child->cmn.adj_stack_size;
+  newsp = newtop - stackutil;
   memcpy((void *)newsp, (const void *)context->sp, stackutil);
 
   /* Was there a frame pointer in place before? */
 
-  if (context->fp <= (uint32_t)parent->adj_stack_ptr &&
-      context->fp >= (uint32_t)parent->adj_stack_ptr - stacksize)
+  if (context->fp >= context->sp && context->fp < stacktop)
     {
-      uint32_t frameutil = (uint32_t)parent->adj_stack_ptr - context->fp;
-      newfp = (uint32_t)child->cmn.adj_stack_ptr - frameutil;
+      uint32_t frameutil = stacktop - context->fp;
+      newfp = newtop - frameutil;
     }
   else
     {
       newfp = context->fp;
     }
 
-  sinfo("Parent: stack base:%p SP:%08" PRIx32 " FP:%08" PRIx32 "\n",
-        parent->adj_stack_ptr, context->sp, context->fp);
-  sinfo("Child:  stack base:%p SP:%08" PRIx32 " FP:%08" PRIx32 "\n",
-        child->cmn.adj_stack_ptr, newsp, newfp);
+  sinfo("Old stack top:%08" PRIx32 "SP:%08" PRIx32 " FP:%08" PRIx32 "\n",
+        stacktop, context->sp, context->fp);
+  sinfo("New stack top:%08" PRIx32 "SP:%08" PRIx32 " FP:%08" PRIx32 "\n",
+        newtop, newsp, newfp);

Review comment:
       ```suggestion
     sinfo("Old stack top:%08" PRIx32 " SP:%08" PRIx32 " FP:%08" PRIx32 "\n",
           stacktop, context->sp, context->fp);
     sinfo("New stack top:%08" PRIx32 " SP:%08" PRIx32 " FP:%08" PRIx32 "\n",
           newtop, newsp, newfp);
   ```
   Missing whitespace between printed values.




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