sched/addrenv.c: Implement re-entrancy for addrenv_select()

Store the old environment in a local context so another temporary address
environment can be selected. This can happen especially when a process
is being loaded (the new process's mappings are temporarily instantiated)
and and interrupt occurs.

sched/addrenv/addrenv.c

@@ -338,7 +338,8 @@ int addrenv_leave(FAR struct tcb_s *tcb)
  *   running process.
  *
  * Input Parameters:
- *   addrenv - The address environment.
+ *   addrenv - The address environment to instantiate.
+ *   oldenv  - The old active address environment is placed here.
  *
  * Returned Value:
  *   This is a NuttX internal function so it follows the convention that
@@ -347,10 +348,12 @@ int addrenv_leave(FAR struct tcb_s *tcb)
  *
  ****************************************************************************/
 
-int addrenv_select(FAR struct addrenv_s *addrenv)
+int addrenv_select(FAR struct addrenv_s *addrenv,
+                   FAR struct addrenv_s **oldenv)
 {
   FAR struct tcb_s *tcb = this_task();
   addrenv_take(addrenv);
+  *oldenv = tcb->addrenv_curr;
   tcb->addrenv_curr = addrenv;
   return addrenv_switch(tcb);
 }
@@ -359,10 +362,10 @@ int addrenv_select(FAR struct addrenv_s *addrenv)
  * Name: addrenv_restore
  *
  * Description:
- *   Switch back to the procces's own address environment.
+ *   Switch back to the procces's previous address environment.
  *
  * Input Parameters:
- *   None
+ *   addrenv - The address environment to restore.
  *
  * Returned Value:
  *   This is a NuttX internal function so it follows the convention that
@@ -371,11 +374,11 @@ int addrenv_select(FAR struct addrenv_s *addrenv)
  *
  ****************************************************************************/
 
-int addrenv_restore(void)
+int addrenv_restore(FAR struct addrenv_s *addrenv)
 {
   FAR struct tcb_s *tcb = this_task();
   addrenv_give(tcb->addrenv_curr);
-  tcb->addrenv_curr = tcb->addrenv_own;
+  tcb->addrenv_curr = addrenv;
   return addrenv_switch(tcb);
 }
 

sched/group/group_argvstr.c

@@ -59,6 +59,9 @@
 size_t group_argvstr(FAR struct tcb_s *tcb, FAR char *args, size_t size)
 {
   size_t n = 0;
+#ifdef CONFIG_ARCH_ADDRENV
+  FAR struct addrenv_s *oldenv;
+#endif
 
   /* Perform sanity checks */
 
@@ -73,7 +76,7 @@ size_t group_argvstr(FAR struct tcb_s *tcb, FAR char *args, size_t size)
 #ifdef CONFIG_ARCH_ADDRENV
   if (tcb->addrenv_own != NULL)
     {
-      addrenv_select(tcb->addrenv_own);
+      addrenv_select(tcb->addrenv_own, &oldenv);
     }
 #endif
 
@@ -98,7 +101,7 @@ size_t group_argvstr(FAR struct tcb_s *tcb, FAR char *args, size_t size)
 #ifdef CONFIG_ARCH_ADDRENV
   if (tcb->addrenv_own != NULL)
     {
-      addrenv_restore();
+      addrenv_restore(oldenv);
     }
 #endif
 

sched/sched/sched_get_stateinfo.c

@@ -83,6 +83,15 @@ void nxsched_get_stateinfo(FAR struct tcb_s *tcb, FAR char *state,
 {
   irqstate_t flags;
 
+#ifdef CONFIG_ARCH_ADDRENV
+  FAR struct addrenv_s *oldenv;
+
+  if (tcb->addrenv_own)
+    {
+      addrenv_select(tcb->addrenv_own, &oldenv);
+    }
+#endif
+
   /* if the state is waiting mutex */
 
   flags = enter_critical_section();
@@ -100,4 +109,11 @@ void nxsched_get_stateinfo(FAR struct tcb_s *tcb, FAR char *state,
       leave_critical_section(flags);
       strlcpy(state, g_statenames[tcb->task_state], length);
     }
+
+#ifdef CONFIG_ARCH_ADDRENV
+  if (tcb->addrenv_own)
+    {
+      addrenv_restore(oldenv);
+    }
+#endif
 }

sched/semaphore/sem_waitirq.c

@@ -73,9 +73,11 @@ void nxsem_wait_irq(FAR struct tcb_s *wtcb, int errcode)
   FAR sem_t *sem = wtcb->waitobj;
 
 #ifdef CONFIG_ARCH_ADDRENV
+  FAR struct addrenv_s *oldenv;
+
   if (wtcb->addrenv_own)
     {
-      addrenv_select(wtcb->addrenv_own);
+      addrenv_select(wtcb->addrenv_own, &oldenv);
     }
 #endif
 
@@ -106,7 +108,7 @@ void nxsem_wait_irq(FAR struct tcb_s *wtcb, int errcode)
 #ifdef CONFIG_ARCH_ADDRENV
   if (wtcb->addrenv_own)
     {
-      addrenv_restore();
+      addrenv_restore(oldenv);
     }
 #endif