arch/xtensa: add crt0 to initialize environment

arch/xtensa/src/Makefile

@@ -145,11 +145,14 @@ $(AOBJS) $(UAOBJS) $(HEAD_AOBJ): %$(OBJEXT): %.S
 $(COBJS) $(UCOBJS) $(HEAD_COBJ): %$(OBJEXT): %.c
 	$(call COMPILE, $<, $@)
 
+$(STARTUP_ELF_OBJS): %$(OBJEXT): %.c
+	$(Q) $(CC) $(CELFFLAGS) -c common$(DELIM)crt0.c -o crt0$(OBJEXT)
+
 ifeq ($(CONFIG_BUILD_FLAT),y)
-$(BIN): $(OBJS)
+$(BIN): $(STARTUP_ELF_OBJS) $(OBJS)
 	$(call ARCHIVE, $@, $(OBJS))
 else
-$(BIN): $(UOBJS)
+$(BIN): $(STARTUP_ELF_OBJS) $(UOBJS)
 	$(call ARCHIVE, $@, $(UOBJS))
 endif
 

arch/xtensa/src/common/Make.defs

@@ -22,6 +22,8 @@
 
 # The start-up, "head", file.  May be either a .S or a .c file.
 
+STARTUP_ELF_OBJS = crt0$(OBJEXT)
+
 HEAD_ASRC  = xtensa_vectors.S xtensa_window_vector.S xtensa_windowspill.S
 HEAD_ASRC += xtensa_int_handlers.S xtensa_user_handler.S
 

arch/xtensa/src/common/crt0.c

@@ -0,0 +1,153 @@
+/****************************************************************************
+ * arch/xtensa/src/common/crt0.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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 <sys/types.h>
+#include <stdlib.h>
+
+#include <nuttx/addrenv.h>
+#include <nuttx/arch.h>
+
+#include <arch/syscall.h>
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/* Linker defined symbols to .ctors and .dtors */
+
+extern initializer_t _sctors[];
+extern initializer_t _ectors[];
+extern initializer_t _sdtors[];
+extern initializer_t _edtors[];
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+int main(int argc, char *argv[]);
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+#ifdef CONFIG_HAVE_CXXINITIALIZE
+
+/****************************************************************************
+ * Name: exec_ctors
+ *
+ * Description:
+ *   Call static constructors
+ *
+ ****************************************************************************/
+
+static void exec_ctors(void)
+{
+  for (initializer_t *ctor = _sctors; ctor != _ectors; ctor++)
+    {
+      (*ctor)();
+    }
+}
+
+/****************************************************************************
+ * Name: exec_dtors
+ *
+ * Description:
+ *   Call static destructors
+ *
+ ****************************************************************************/
+
+static void exec_dtors(void)
+{
+  for (initializer_t *dtor = _sdtors; dtor != _edtors; dtor++)
+    {
+      (*dtor)();
+    }
+}
+
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: __start
+ *
+ * Description:
+ *   This function is the low level entry point into the main thread of
+ *   execution of a task.  It receives initial control when the task is
+ *   started and calls main entry point of the newly started task.
+ *
+ * Input Parameters:
+ *   argc - The number of parameters being passed.
+ *   argv - The parameters being passed. These lie in kernel-space memory
+ *     and will have to be reallocated  in user-space memory.
+ *
+ * Returned Value:
+ *   This function should not return.  It should call the user-mode start-up
+ *   main() function.  If that function returns, this function will call
+ *   exit.
+ *
+ ****************************************************************************/
+
+void __start(int argc, char *argv[])
+{
+  int ret;
+
+  /* Initialize the reserved area at the beginning of the .bss/.data region
+   * that is visible to the RTOS.
+   */
+
+#ifdef CONFIG_BUILD_KERNEL
+  ARCH_DATA_RESERVE->ar_sigtramp = (addrenv_sigtramp_t)sig_trampoline;
+#endif
+
+#ifdef CONFIG_HAVE_CXXINITIALIZE
+  /* Call C++ constructors */
+
+  exec_ctors();
+
+  /* Setup so that C++ destructors called on task exit */
+
+#  if CONFIG_LIBC_MAX_EXITFUNS > 0
+  atexit(exec_dtors);
+#  endif
+#endif
+
+  /* Call the main() entry point passing argc and argv. */
+
+  ret = main(argc, argv);
+
+#if defined(CONFIG_HAVE_CXXINITIALIZE) && CONFIG_LIBC_MAX_EXITFUNS <= 0
+  exec_dtors();
+#endif
+
+  /* Call exit() if/when the main() returns */
+
+  exit(ret);
+}

arch/xtensa/src/lx6/Toolchain.defs

@@ -219,3 +219,9 @@ CXXELFFLAGS = $(CXXFLAGS) -fvisibility=hidden -mtext-section-literals
 
 LDELFFLAGS = -r -e __start
 LDELFFLAGS += -T $(call CONVERT_PATH,$(TOPDIR)$(DELIM)libs$(DELIM)libc$(DELIM)elf$(DELIM)gnu-elf.ld)
+ifneq ($(CONFIG_BUILD_KERNEL),y)
+  # Flat build and protected elf entry point use crt0,
+  # Kernel build will use apps/import/scripts/crt0
+
+  LDELFFLAGS += $(TOPDIR)$(DELIM)arch$(DELIM)xtensa$(DELIM)src$(DELIM)crt0.o
+endif

arch/xtensa/src/lx7/Toolchain.defs

@@ -223,3 +223,9 @@ CXXELFFLAGS = $(CXXFLAGS) -fvisibility=hidden -mtext-section-literals
 
 LDELFFLAGS = -r -e __start
 LDELFFLAGS += -T $(call CONVERT_PATH,$(TOPDIR)$(DELIM)libs$(DELIM)libc$(DELIM)elf$(DELIM)gnu-elf.ld)
+ifneq ($(CONFIG_BUILD_KERNEL),y)
+  # Flat build and protected elf entry point use crt0,
+  # Kernel build will use apps/import/scripts/crt0
+
+  LDELFFLAGS += $(TOPDIR)$(DELIM)arch$(DELIM)xtensa$(DELIM)src$(DELIM)crt0.o
+endif