sched/addrenv: Miscellaneous clean-up and fixes

- Remove the temporary "saved" variable when temporarily changing MMU
  mappings to access another process's memory. The fact that it has an
  address environment is enough to make the choice
- Restore nxflat_addrenv_restore-macro. It was accidentally lost when
  the address environment handling was re-factored.

arch/arm/src/common/arm_checkstack.c

@@ -203,19 +203,16 @@ size_t up_check_tcbstack(struct tcb_s *tcb)
   size_t size;
 
 #ifdef CONFIG_ARCH_ADDRENV
-  bool saved = false;
-
   if (tcb->addrenv_own != NULL)
     {
       addrenv_select(tcb->addrenv_own);
-      saved = true;
     }
 #endif
 
   size = arm_stack_check(tcb->stack_base_ptr, tcb->adj_stack_size);
 
 #ifdef CONFIG_ARCH_ADDRENV
-  if (saved)
+  if (tcb->addrenv_own != NULL)
     {
       addrenv_restore();
     }

arch/risc-v/src/common/riscv_checkstack.c

@@ -159,12 +159,9 @@ size_t up_check_tcbstack(struct tcb_s *tcb)
   size_t size;
 
 #ifdef CONFIG_ARCH_ADDRENV
-  bool saved = false;
-
   if (tcb->addrenv_own != NULL)
     {
       addrenv_select(tcb->addrenv_own);
-      saved = true;
     }
 #endif
 
@@ -172,7 +169,7 @@ size_t up_check_tcbstack(struct tcb_s *tcb)
                            tcb->adj_stack_size);
 
 #ifdef CONFIG_ARCH_ADDRENV
-  if (saved)
+  if (tcb->addrenv_own != NULL)
     {
       addrenv_restore();
     }

binfmt/libnxflat/libnxflat.h

@@ -79,6 +79,25 @@ int nxflat_addrenv_alloc(FAR struct nxflat_loadinfo_s *loadinfo,
 #  define nxflat_addrenv_select(l) addrenv_select(&(l)->addrenv)
 #endif
 
+/****************************************************************************
+ * Name: nxflat_addrenv_restore
+ *
+ * Description:
+ *   Restore the address environment before nxflat_addrenv_select() was
+ *   called..
+ *
+ * Input Parameters:
+ *   loadinfo - Load state information
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_ADDRENV
+#  define nxflat_addrenv_restore(l) addrenv_restore()
+#endif
+
 /****************************************************************************
  * Name: nxflat_addrenv_free
  *

sched/group/group_argvstr.c

@@ -59,9 +59,6 @@
 size_t group_argvstr(FAR struct tcb_s *tcb, FAR char *args, size_t size)
 {
   size_t n = 0;
-#ifdef CONFIG_ARCH_ADDRENV
-  bool saved = false;
-#endif
 
   /* Perform sanity checks */
 
@@ -77,7 +74,6 @@ size_t group_argvstr(FAR struct tcb_s *tcb, FAR char *args, size_t size)
   if (tcb->addrenv_own != NULL)
     {
       addrenv_select(tcb->addrenv_own);
-      saved = true;
     }
 #endif
 
@@ -100,7 +96,7 @@ size_t group_argvstr(FAR struct tcb_s *tcb, FAR char *args, size_t size)
     }
 
 #ifdef CONFIG_ARCH_ADDRENV
-  if (saved)
+  if (tcb->addrenv_own != NULL)
     {
       addrenv_restore();
     }