lib c/cpp: Move .ctor .init_array handling from C++ to kernel

* Move ctors and init_array from the CPP library
  to the kernel library, as this is common for both C
  and C++ and it is the kernel who is running it.
* Rename the hidden kconfig option CPP_STATIC_INIT_GNU
  STATIC_INIT_GNU instead.
* If STATIC_INIT_GNU is not selected verify there is
  constructors left behind.
* Rename common-rom-cpp.ld to common-rom-init.ld
* Rename z_cpp_init_static to z_init_static,
  and have the kernel always call it.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
Signed-off-by: Keith Packard <keithp@keithp.com>

include/zephyr/arch/arc/v2/linker.ld

@@ -142,12 +142,12 @@ SECTIONS {
 #include <snippets-rodata.ld>
 #include <zephyr/linker/kobject-rom.ld>
 
-#if defined(CONFIG_CPP) && !defined(CONFIG_CPP_STATIC_INIT_GNU) && defined(__MWDT_LINKER_CMD__)
+#if defined(CONFIG_CPP) && !defined(CONFIG_STATIC_INIT_GNU) && defined(__MWDT_LINKER_CMD__)
 		. = ALIGN(4);
 		_fctors = .;
 		KEEP(*(.ctors*))
 		_ectors = .;
-#endif /* CONFIG_CPP && !CONFIG_CPP_STATIC_INIT_GNU && __MWDT_LINKER_CMD__ */
+#endif /* CONFIG_CPP && !CONFIG_STATIC_INIT_GNU && __MWDT_LINKER_CMD__ */
 
 /* This extra MPU alignment of RAMABLE_REGION is only required if we put ROMABLE_REGION and
  * RAMABLE_REGION into the same (continuous) memory - otherwise we can get beginning of the
@@ -311,11 +311,11 @@ SECTIONS {
 #endif
 
 	/DISCARD/ : {
-#if defined(CONFIG_CPP) && !defined(CONFIG_CPP_STATIC_INIT_GNU) && defined(__MWDT_LINKER_CMD__)
+#if defined(CONFIG_CPP) && !defined(CONFIG_STATIC_INIT_GNU) && defined(__MWDT_LINKER_CMD__)
 		*(.dtors*)
 		*(.fini*)
 		*(.eh_frame*)
-#endif /* CONFIG_CPP && !CONFIG_CPP_STATIC_INIT_GNU && __MWDT_LINKER_CMD__ */
+#endif /* CONFIG_CPP && !CONFIG_STATIC_INIT_GNU && __MWDT_LINKER_CMD__ */
 		*(.note.GNU-stack)
 		*(.got.plt)
 		*(.igot.plt)

include/zephyr/linker/common-rom.ld

@@ -4,7 +4,7 @@
 
 #include <zephyr/linker/common-rom/common-rom-ztest.ld>
 
-#include <zephyr/linker/common-rom/common-rom-cpp.ld>
+#include <zephyr/linker/common-rom/common-rom-init.ld>
 
 #include <zephyr/linker/common-rom/common-rom-net.ld>
 

include/zephyr/linker/common-rom/common-rom-cpp.ld → include/zephyr/linker/common-rom/common-rom-init.ld

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: Apache-2.0 */
 
-#ifdef CONFIG_CPP_STATIC_INIT_GNU
+#ifdef CONFIG_STATIC_INIT_GNU
 	SECTION_PROLOGUE(_CTOR_SECTION_NAME,,)
 	{
 		/*
@@ -59,4 +59,18 @@
 		KEEP(*(SORT_BY_NAME(".init_array*")))
 		__zephyr_init_array_end = .;
 	} GROUP_ROM_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+
+#elif defined(CONFIG_TOOLCHAIN_SUPPORTS_STATIC_INIT_GNU)
+	/*
+	 * If the code to invoke constructors is not enabled,
+	 * make sure there aren't any in the application
+	 */
+	SECTION_PROLOGUE(init_array,,)
+	{
+		KEEP(*(SORT_BY_NAME(".ctors*")))
+		KEEP(*(SORT_BY_NAME(".init_array*")))
+	} GROUP_ROM_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+
+	ASSERT (SIZEOF(init_array) == 0,
+		"GNU-style constructors required but STATIC_INIT_GNU not enabled")
 #endif

kernel/CMakeLists.txt

@@ -55,6 +55,7 @@ list(APPEND kernel_files
   errno.c
   fatal.c
   init.c
+  init_static.c
   kheap.c
   mem_slab.c
   float.c

kernel/Kconfig

@@ -983,6 +983,29 @@ config KERNEL_WHOLE_ARCHIVE
 	  This option forces every object file in the libkernel.a archive
 	  to be included, rather than searching the archive for required object files.
 
+config TOOLCHAIN_SUPPORTS_STATIC_INIT_GNU
+	# As of today only ARC MWDT toolchain doesn't support GNU-compatible
+	# initialization of static objects, new toolchains can be added
+	# here if required.
+	def_bool "$(ZEPHYR_TOOLCHAIN_VARIANT)" != "arcmwdt"
+
+config STATIC_INIT_GNU
+	bool "Support GNU-compatible initializers and constructors"
+	default y if CPP || NATIVE_BUILD || COVERAGE
+	depends on TOOLCHAIN_SUPPORTS_STATIC_INIT_GNU
+	depends on !CMAKE_LINKER_GENERATOR
+	help
+	  GNU-compatible initialization of static objects. This is required for
+	  C++ constructor support as well as for initializer functions as
+	  defined by GNU-compatible toolchains. This increases the size
+	  of Zephyr binaries by around 100 bytes. If you know your
+	  application doesn't need any initializers, you can disable this
+	  option.
+	  The ARC MWDT toolchain, does not support or use this setting,
+	  and has instead separate C++ constructor initialization code.
+	  Note the option CMAKE_LINKER_GENERATOR does not yet support this feature
+	  or CPP.
+
 endmenu
 
 rsource "Kconfig.device"

kernel/init.c

@@ -433,10 +433,8 @@ static void bg_thread_main(void *unused1, void *unused2, void *unused3)
 #endif /* CONFIG_STACK_POINTER_RANDOM */
 	boot_banner();
 
-#if defined(CONFIG_CPP)
-	void z_cpp_init_static(void);
-	z_cpp_init_static();
-#endif /* CONFIG_CPP */
+	void z_init_static(void);
+	z_init_static();
 
 	/* Final init level before app starts */
 	z_sys_init_run_level(INIT_LEVEL_APPLICATION);

kernel/init_static.c

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2012-2015 Wind River Systems, Inc.
+ * Copyright (c) 2021 Synopsys, Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+void __do_global_ctors_aux(void);
+void __do_init_array_aux(void);
+
+void z_init_static(void)
+{
+#if defined(CONFIG_STATIC_INIT_GNU)
+	__do_global_ctors_aux();
+	__do_init_array_aux();
+#elif defined(__CCAC__) /* ARC MWDT */
+	__do_global_ctors_aux();
+#endif
+}
+
+/**
+ * @section - Constructor module
+ * @brief
+ * The ctors section contains a list of function pointers that execute both the C++ constructors of
+ * static global objects, as well as either C or C++ initializer functions (declared with the
+ * attribute constructor). These must be executed before the application's main() routine.
+ *
+ * NOTE: Not all compilers put those function pointers into the ctors section;
+ * some put them into the init_array section instead.
+ */
+
+#ifdef CONFIG_STATIC_INIT_GNU
+
+/* What a constructor function pointer looks like */
+
+typedef void (*CtorFuncPtr)(void);
+
+/* Constructor function pointer list is generated by the linker script. */
+
+extern CtorFuncPtr __ZEPHYR_CTOR_LIST__[];
+extern CtorFuncPtr __ZEPHYR_CTOR_END__[];
+
+/**
+ *
+ * @brief Invoke all C++ style global object constructors
+ *
+ * This routine is invoked by the kernel prior to the execution of the
+ * application's main().
+ */
+void __do_global_ctors_aux(void)
+{
+	unsigned int nCtors;
+
+	nCtors = (unsigned long)__ZEPHYR_CTOR_LIST__[0];
+
+	while (nCtors >= 1U) {
+		__ZEPHYR_CTOR_LIST__[nCtors--]();
+	}
+}
+
+#endif
+
+/*
+ * @section
+ * @brief Execute initialization routines referenced in .init_array section
+ */
+
+#ifdef CONFIG_STATIC_INIT_GNU
+
+typedef void (*func_ptr)(void);
+
+extern func_ptr __zephyr_init_array_start[];
+extern func_ptr __zephyr_init_array_end[];
+
+/**
+ * @brief Execute initialization routines referenced in .init_array section
+ */
+void __do_init_array_aux(void)
+{
+	for (func_ptr *func = __zephyr_init_array_start;
+		func < __zephyr_init_array_end;
+		func++) {
+		(*func)();
+	}
+}
+
+#endif

lib/cpp/Kconfig

@@ -144,12 +144,12 @@ config CPP_RTTI
 endif # !MINIMAL_LIBCPP
 
 config CPP_STATIC_INIT_GNU
-	# As of today only ARC MWDT toolchain doesn't support GNU-compatible
-	# initialization of CPP static objects, new toolchains can be added
-	# here if required.
-	def_bool "$(ZEPHYR_TOOLCHAIN_VARIANT)" != "arcmwdt"
+	bool
+	select STATIC_INIT_GNU
+	select DEPRECATED
 	help
-	  GNU-compatible initialization of CPP static objects
+	  GNU-compatible initialization of CPP static objects.
+	  This option is deprecated in favour of STATIC_INIT_GNU
 
 endif # CPP
 

lib/cpp/abi/CMakeLists.txt

@@ -1,9 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-zephyr_sources(cpp_init.c)
-
-zephyr_sources_ifdef(CONFIG_CPP_STATIC_INIT_GNU
-  cpp_init_array.c
-  cpp_ctors.c
+zephyr_sources_ifdef(CONFIG_STATIC_INIT_GNU
   cpp_dtors.c
 )

soc/espressif/esp32/default.ld

@@ -805,7 +805,7 @@ SECTIONS
     . = ALIGN(4);
   } GROUP_DATA_LINK_IN(RODATA_REGION, ROMABLE_REGION)
 
-  #include <zephyr/linker/common-rom/common-rom-cpp.ld>
+  #include <zephyr/linker/common-rom/common-rom-init.ld>
   #include <zephyr/linker/common-rom/common-rom-kernel-devices.ld>
   #include <zephyr/linker/common-rom/common-rom-ztest.ld>
   #include <zephyr/linker/common-rom/common-rom-net.ld>

soc/espressif/esp32/default_appcpu.ld

@@ -209,7 +209,7 @@ SECTIONS
     . = ALIGN(4);
   } GROUP_DATA_LINK_IN(RODATA_REGION, ROMABLE_DATA_REGION)
 
-  #include <zephyr/linker/common-rom/common-rom-cpp.ld>
+  #include <zephyr/linker/common-rom/common-rom-init.ld>
   #include <zephyr/linker/common-rom/common-rom-kernel-devices.ld>
   #include <zephyr/linker/common-rom/common-rom-ztest.ld>
   #include <zephyr/linker/common-rom/common-rom-net.ld>

soc/espressif/esp32c3/default.ld

@@ -771,7 +771,7 @@ SECTIONS
   } GROUP_DATA_LINK_IN(RODATA_REGION, ROMABLE_REGION)
 
   #include <zephyr/linker/cplusplus-rom.ld>
-  #include <zephyr/linker/common-rom/common-rom-cpp.ld>
+  #include <zephyr/linker/common-rom/common-rom-init.ld>
   #include <zephyr/linker/common-rom/common-rom-kernel-devices.ld>
   #include <zephyr/linker/common-rom/common-rom-ztest.ld>
   #include <zephyr/linker/common-rom/common-rom-net.ld>

soc/espressif/esp32c3/mcuboot.ld

@@ -225,7 +225,7 @@ SECTIONS
     . = ALIGN(4);
   } > dram_seg
 
-  #include <zephyr/linker/common-rom/common-rom-cpp.ld>
+  #include <zephyr/linker/common-rom/common-rom-init.ld>
   #include <zephyr/linker/common-rom/common-rom-kernel-devices.ld>
   #include <zephyr/linker/common-rom/common-rom-debug.ld>
   #include <zephyr/linker/common-rom/common-rom-misc.ld>

soc/espressif/esp32c6/default.ld

@@ -771,7 +771,7 @@ SECTIONS
   } GROUP_DATA_LINK_IN(CACHED_REGION, ROMABLE_REGION)
 
   #include <zephyr/linker/cplusplus-rom.ld>
-  #include <zephyr/linker/common-rom/common-rom-cpp.ld>
+  #include <zephyr/linker/common-rom/common-rom-init.ld>
   #include <zephyr/linker/common-rom/common-rom-kernel-devices.ld>
   #include <zephyr/linker/common-rom/common-rom-ztest.ld>
   #include <zephyr/linker/common-rom/common-rom-net.ld>

soc/espressif/esp32c6/mcuboot.ld

@@ -219,7 +219,7 @@ SECTIONS
     . = ALIGN(4);
   } > dram_seg
 
-  #include <zephyr/linker/common-rom/common-rom-cpp.ld>
+  #include <zephyr/linker/common-rom/common-rom-init.ld>
   #include <zephyr/linker/common-rom/common-rom-kernel-devices.ld>
   #include <zephyr/linker/common-rom/common-rom-debug.ld>
   #include <zephyr/linker/common-rom/common-rom-misc.ld>

soc/espressif/esp32s2/default.ld

@@ -908,7 +908,7 @@ SECTIONS
   } GROUP_DATA_LINK_IN(RODATA_REGION, ROMABLE_REGION)
 
   #include <zephyr/linker/cplusplus-rom.ld>
-  #include <zephyr/linker/common-rom/common-rom-cpp.ld>
+  #include <zephyr/linker/common-rom/common-rom-init.ld>
   #include <zephyr/linker/common-rom/common-rom-kernel-devices.ld>
   #include <zephyr/linker/common-rom/common-rom-ztest.ld>
   #include <zephyr/linker/common-rom/common-rom-net.ld>