sched/addrenv, binfmt: Always allocate address environment from heap

Instead of using a volatile storage for the address environment in the
binfmt / loadinfo structures, always allocate the address environment
from kheap.

This serves two purposes:
- If the task creation fails, any kernel thread that depends on the
  address environment created during task creation will not lose their
  mappings (because they hold a reference to it)
- The current address environment variable (g_addrenv) will NEVER contain
  a stale / incorrect value
- Releasing the address environment is simplified as any pointer given
  to addrenv_drop() can be assumed to be heap memory
- Makes the kludge function addrenv_clear_current irrelevant, as the
  system will NEVER have invalid mappings any more

binfmt/binfmt_execmodule.c

@@ -117,7 +117,7 @@ int exec_module(FAR struct binary_s *binp,
 {
   FAR struct task_tcb_s *tcb;
 #if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_BUILD_KERNEL)
-  FAR struct arch_addrenv_s *addrenv = &binp->addrenv.addrenv;
+  FAR struct arch_addrenv_s *addrenv = &binp->addrenv->addrenv;
   FAR void *vheap;
 #endif
   FAR void *stackaddr = NULL;
@@ -165,7 +165,7 @@ int exec_module(FAR struct binary_s *binp,
 #if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_BUILD_KERNEL)
   /* Instantiate the address environment containing the user heap */
 
-  ret = addrenv_select(&binp->addrenv);
+  ret = addrenv_select(binp->addrenv);
   if (ret < 0)
     {
       berr("ERROR: addrenv_select() failed: %d\n", ret);
@@ -242,7 +242,7 @@ int exec_module(FAR struct binary_s *binp,
 #ifdef CONFIG_ARCH_ADDRENV
   /* Attach the address environment to the new task */
 
-  ret = addrenv_attach((FAR struct tcb_s *)tcb, &binp->addrenv);
+  ret = addrenv_attach((FAR struct tcb_s *)tcb, binp->addrenv);
   if (ret < 0)
     {
       berr("ERROR: addrenv_attach() failed: %d\n", ret);

binfmt/elf.c

@@ -271,11 +271,7 @@ static int elf_loadbinary(FAR struct binary_s *binp,
    * needed when the module is executed.
    */
 
-  up_addrenv_clone(&loadinfo.addrenv.addrenv, &binp->addrenv.addrenv);
-
-  /* Take a reference to the address environment, so it won't get freed */
-
-  addrenv_take(&binp->addrenv);
+  binp->addrenv = loadinfo.addrenv;
 
 #else
   binp->alloc[0]  = (FAR void *)loadinfo.textalloc;

binfmt/libelf/libelf_addrenv.c

@@ -84,24 +84,30 @@ int elf_addrenv_alloc(FAR struct elf_loadinfo_s *loadinfo, size_t textsize,
                       size_t datasize, size_t heapsize)
 {
 #ifdef CONFIG_ARCH_ADDRENV
-  FAR struct arch_addrenv_s *addrenv = &loadinfo->addrenv.addrenv;
+  FAR struct arch_addrenv_s *addrenv;
   FAR void *vtext;
   FAR void *vdata;
   int ret;
 
   /* Create an address environment for the new ELF task */
 
+  loadinfo->addrenv = addrenv_allocate();
+  if (!loadinfo->addrenv)
+    {
+      return -ENOMEM;
+    }
+
+  /* Start creating the address environment sections */
+
+  addrenv = &loadinfo->addrenv->addrenv;
+
   ret = up_addrenv_create(textsize, datasize, heapsize, addrenv);
   if (ret < 0)
     {
       berr("ERROR: up_addrenv_create failed: %d\n", ret);
-      return ret;
+      goto errout_with_addrenv;
     }
 
-  /* Take a reference to the address environment, so it won't get freed */
-
-  addrenv_take(&loadinfo->addrenv);
-
   /* Get the virtual address associated with the start of the address
    * environment.  This is the base address that we will need to use to
    * access the ELF image (but only if the address environment has been
@@ -112,19 +118,24 @@ int elf_addrenv_alloc(FAR struct elf_loadinfo_s *loadinfo, size_t textsize,
   if (ret < 0)
     {
       berr("ERROR: up_addrenv_vtext failed: %d\n", ret);
-      return ret;
+      goto errout_with_addrenv;
     }
 
   ret = up_addrenv_vdata(addrenv, textsize, &vdata);
   if (ret < 0)
     {
       berr("ERROR: up_addrenv_vdata failed: %d\n", ret);
-      return ret;
+      goto errout_with_addrenv;
     }
 
   loadinfo->textalloc = (uintptr_t)vtext;
   loadinfo->dataalloc = (uintptr_t)vdata;
+
   return OK;
+
+errout_with_addrenv:
+  addrenv_drop(loadinfo->addrenv, false);
+  return ret;
 #else
   /* Allocate memory to hold the ELF image */
 
@@ -177,7 +188,7 @@ int elf_addrenv_select(FAR struct elf_loadinfo_s *loadinfo)
 
   /* Instantiate the new address environment */
 
-  ret = addrenv_select(&loadinfo->addrenv);
+  ret = addrenv_select(loadinfo->addrenv);
   if (ret < 0)
     {
       berr("ERROR: addrenv_select failed: %d\n", ret);
@@ -186,7 +197,7 @@ int elf_addrenv_select(FAR struct elf_loadinfo_s *loadinfo)
 
   /* Allow write access to .text */
 
-  ret = up_addrenv_mprot(&loadinfo->addrenv.addrenv, loadinfo->textalloc,
+  ret = up_addrenv_mprot(&loadinfo->addrenv->addrenv, loadinfo->textalloc,
                          loadinfo->textsize, ELF_TEXT_WRE);
   if (ret < 0)
     {
@@ -219,7 +230,7 @@ int elf_addrenv_restore(FAR struct elf_loadinfo_s *loadinfo)
 
   /* Remove write access to .text */
 
-  ret = up_addrenv_mprot(&loadinfo->addrenv.addrenv, loadinfo->textalloc,
+  ret = up_addrenv_mprot(&loadinfo->addrenv->addrenv, loadinfo->textalloc,
                          loadinfo->textsize, ELF_TEXT_WRD);
   if (ret < 0)
     {
@@ -261,15 +272,10 @@ int elf_addrenv_restore(FAR struct elf_loadinfo_s *loadinfo)
 void elf_addrenv_free(FAR struct elf_loadinfo_s *loadinfo)
 {
 #ifdef CONFIG_ARCH_ADDRENV
-  int ret;
 
   /* Free the address environment */
 
-  ret = up_addrenv_destroy(&loadinfo->addrenv.addrenv);
-  if (ret < 0)
-    {
-      berr("ERROR: up_addrenv_destroy failed: %d\n", ret);
-    }
+  addrenv_drop(loadinfo->addrenv, false);
 #else
 
   if (loadinfo->textalloc != 0)