Introduce instruction memory allocator

Necessary for dlfcn etc on ESP32, which has separate memory regions
for instruction and data.

known issues/todo
 * consider something similar to dual heaps for PROTOECTED
 * consider to adapt binfmt as well

arch/xtensa/src/esp32/Make.defs

@@ -106,3 +106,7 @@ endif
 ifeq ($(CONFIG_ESP32_UART),y)
 CMN_CSRCS += esp32_serial.c
 endif
+
+ifeq ($(CONFIG_ARCH_USE_MODULE_TEXT),y)
+CHIP_CSRCS += esp32_modtext.c
+endif

arch/xtensa/src/esp32/esp32_modtext.c

@@ -0,0 +1,86 @@
+/****************************************************************************
+ * arch/xtensa/src/esp32/esp32_modtext.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/arch.h>
+#include <nuttx/mm/mm.h>
+
+#include <sys/types.h>
+#include <debug.h>
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+extern uint32_t _smodtext;
+extern uint32_t _emodtext;
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+struct mm_heap_s g_module_text;
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_module_text_init
+ *
+ * Description:
+ *   Initialize the module text allocator
+ *
+ ****************************************************************************/
+
+void up_module_text_init()
+{
+  mm_initialize(&g_module_text, &_smodtext, &_emodtext - &_smodtext);
+}
+
+/****************************************************************************
+ * Name: up_module_text_alloc
+ *
+ * Description:
+ *   Allocate memory for module text.
+ *
+ ****************************************************************************/
+
+FAR void *up_module_text_alloc(size_t size)
+{
+  return mm_malloc(&g_module_text, size);
+}
+
+/****************************************************************************
+ * Name: up_module_text_free
+ *
+ * Description:
+ *   Free memory for module text.
+ *
+ ****************************************************************************/
+
+void up_module_text_free(FAR void *p)
+{
+  return mm_free(&g_module_text, p);
+}

boards/xtensa/esp32/esp32-core/scripts/esp32.template

@@ -60,3 +60,7 @@ MEMORY
 /* Heap ends at top of dram0_0_seg */
 
 _eheap = 0x40000000 - CONFIG_ESP32_TRACEMEM_RESERVE_DRAM;
+
+/* Module text area ends at top of dram0_0_seg */
+
+_emodtext = 0x400a0000;

boards/xtensa/esp32/esp32-core/scripts/esp32_flash.ld

@@ -59,6 +59,10 @@ SECTIONS
     *libpp.a:(.literal .text .literal.* .text.*)
     *libhal.a:(.literal .text .literal.* .text.*)
     _iram_text_end = ABSOLUTE(.);
+
+    /* Module text area starts at the end of iram0_0_seg */
+
+    _smodtext = ABSOLUTE(.);
   } > iram0_0_seg
 
   /* Shared RAM */

boards/xtensa/esp32/esp32-core/scripts/esp32_iram.ld

@@ -70,6 +70,9 @@ SECTIONS
     _text_end = ABSOLUTE(.);
     _etext = .;
 
+    /* Module text area starts at the end of iram0_0_seg */
+
+    _smodtext = ABSOLUTE(.);
   } > iram0_0_seg
 
   /* Shared RAM */

include/nuttx/arch.h

@@ -160,6 +160,7 @@ EXTERN volatile bool g_rtc_enabled;
  */
 
 /* EXTERN const irq_mapped_t g_irqmap[NR_IRQS]; */
+
 #endif
 
 /****************************************************************************
@@ -732,6 +733,42 @@ void up_allocate_pgheap(FAR void **heap_start, size_t *heap_size);
 uintptr_t pgalloc(uintptr_t brkaddr, unsigned int npages);
 #endif
 
+/****************************************************************************
+ * Name: up_module_text_init
+ *
+ * Description:
+ *   Initialize the module text allocator
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_ARCH_USE_MODULE_TEXT)
+void up_module_text_init(void);
+#endif
+
+/****************************************************************************
+ * Name: up_module_text_alloc
+ *
+ * Description:
+ *   Allocate memory for module text.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_ARCH_USE_MODULE_TEXT)
+FAR void *up_module_text_alloc(size_t size);
+#endif
+
+/****************************************************************************
+ * Name: up_module_text_free
+ *
+ * Description:
+ *   Free memory for module text.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_ARCH_USE_MODULE_TEXT)
+void up_module_text_free(FAR void *p);
+#endif
+
 /****************************************************************************
  * Name: up_sched_have_garbage and up_sched_garbage_collection
  *