From 6047a9fe146ad4b4e8b2dc7bffe92d9075db429f Mon Sep 17 00:00:00 2001
From: Ville Juven <ville.juven@unikie.com>
Date: Thu, 1 Aug 2024 12:41:41 +0300
Subject: [PATCH] task_fork.c: Fix vfork for BUILD_KERNEL

Two things need to be done when vfork'ing:
- Must attach to parent's address environment (the addrenv is shared)
- Must allocate a kernel stack (where would the register context go otherwise)

Note that this code assumes the address environment is shared, since we
don't support fork() which would _clone_ the address environment instead.
---
 sched/task/task_fork.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/sched/task/task_fork.c b/sched/task/task_fork.c
index 51b61f93fb..00ade225f3 100644
--- a/sched/task/task_fork.c
+++ b/sched/task/task_fork.c
@@ -145,6 +145,19 @@ FAR struct task_tcb_s *nxtask_setup_fork(start_t retaddr)
 
   child->cmn.flags |= TCB_FLAG_FREE_TCB;
 
+#if defined(CONFIG_ARCH_ADDRENV)
+  /* Join the parent address environment (REVISIT: vfork() only) */
+
+  if (ttype != TCB_FLAG_TTYPE_KERNEL)
+    {
+      ret = addrenv_join(parent, &child->cmn);
+      if (ret < 0)
+        {
+          goto errout_with_tcb;
+        }
+    }
+#endif
+
   /* Initialize the task join */
 
   nxtask_joininit(&child->cmn);
@@ -184,6 +197,19 @@ FAR struct task_tcb_s *nxtask_setup_fork(start_t retaddr)
       goto errout_with_tcb;
     }
 
+#if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_ARCH_KERNEL_STACK)
+  /* Allocate the kernel stack */
+
+  if (ttype != TCB_FLAG_TTYPE_KERNEL)
+    {
+      ret = up_addrenv_kstackalloc(&child->cmn);
+      if (ret < 0)
+        {
+          goto errout_with_tcb;
+        }
+    }
+#endif
+
   /* Setup thread local storage */
 
   ret = tls_dup_info(&child->cmn, parent);