linker: align __data_ram/rom_start/end linker symbol names

Cleanup and preparation commit for linker script generator.

Zephyr linker scripts provides start and end symbols for each section,
and sometimes even size and LMA start symbols.

Generally, start and end symbols uses the following pattern, as:
Section name:             foo
Section start symbol:     __foo_start
Section end symbol:       __foo_end

However, this pattern is not followed consistently.
To allow for linker script generation and ensure consistent naming of
symbols then the following pattern is introduced consistently to allow
for cleaner linker script generation.
Section name:             foo
Section start symbol:     __foo_start
Section end symbol:       __foo_end
Section size symbol:      __foo_size
Section LMA start symbol: __foo_load_start

This commit aligns the symbols for _data_ram/rom to other symbols and in
such a way they follow consistent pattern which allows for linker script
and scatter file generation.

The symbols are named according to the section name they describe.
Section name is `data`

A new group named data_region is introduced which instead spans all the
input and output sections that was previously covered by
__data_ram_start, __data_ram_end, and __data_rom_start.

The following symbols are aligned in this commit:
-  __data_ram_start  -> __data_region_start
-  __data_ram_end    -> __data_region_end
-  __data_rom_start  -> __data_region_load_start

The following new symbols are introduced so that the data section is
aligned with other sections:
-  __data_end
-  __data_start
       value identical to __data_region_start but describes start of
       the section.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

include/arch/arc/v2/linker.ld

@@ -178,10 +178,14 @@ SECTIONS {
 
 #include <linker/common-noinit.ld>
 
+	GROUP_START(DATA_REGION)
+
+	__data_region_start = .;
+
 	SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,) {
 
 /* when XIP, .text is in ROM, but vector table must be at start of .data */
-		__data_ram_start = .;
+		__data_start = .;
 		*(".data")
 		*(".data.*")
 		*(".kernel.*")
@@ -191,9 +195,14 @@ SECTIONS {
  */
 #include <snippets-rwdata.ld>
 
+		__data_end = .;
+
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 
-	__data_rom_start = LOADADDR(_DATA_SECTION_NAME);
+	__data_size = __data_end - __data_start;
+	__data_load_start = LOADADDR(_DATA_SECTION_NAME);
+
+	__data_region_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/common-ram.ld>
 #include <linker/kobject-data.ld>
@@ -209,7 +218,8 @@ SECTIONS {
  */
 #include <snippets-data-sections.ld>
 
-	__data_ram_end = .;
+	__data_region_end = .;
+
 	MPU_MIN_SIZE_ALIGN
 	/* Define linker symbols */
 	_image_ram_end = .;

include/arch/arm/aarch32/cortex_a_r/scripts/linker.ld

@@ -278,9 +278,11 @@ SECTIONS
 
 #include <linker/common-noinit.ld>
 
+    __data_region_start = .;
+
     SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
     {
-        __data_ram_start = .;
+        __data_start = .;
         *(.data)
         *(".data.*")
         *(".kernel.*")
@@ -293,10 +295,13 @@ SECTIONS
 #ifdef CONFIG_CODE_DATA_RELOCATION
 #include <linker_sram_data_relocate.ld>
 #endif
+        __data_end = .;
 
     } GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+    __data_size = __data_end - __data_start;
+    __data_load_start = LOADADDR(_DATA_SECTION_NAME);
 
-    __data_rom_start = LOADADDR(_DATA_SECTION_NAME);
+    __data_region_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/common-ram.ld>
 #include <linker/kobject-data.ld>
@@ -307,7 +312,7 @@ SECTIONS
  */
 #include <snippets-data-sections.ld>
 
-    __data_ram_end = .;
+    __data_region_end = .;
 
 
     /* Define linker symbols */

include/arch/arm/aarch32/cortex_m/scripts/linker.ld

@@ -292,9 +292,13 @@ SECTIONS
 
 #endif  /* CONFIG_USERSPACE */
 
+    GROUP_START(DATA_REGION)
+
+    __data_region_start = .;
+
     SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
 	{
-	__data_ram_start = .;
+	__data_start = .;
 	*(.data)
 	*(".data.*")
 	*(".kernel.*")
@@ -307,10 +311,13 @@ SECTIONS
 #ifdef CONFIG_CODE_DATA_RELOCATION
 #include <linker_sram_data_relocate.ld>
 #endif
+	__data_end = .;
 
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+    __data_size = __data_end - __data_start;
+    __data_load_start = LOADADDR(_DATA_SECTION_NAME);
 
-    __data_rom_start = LOADADDR(_DATA_SECTION_NAME);
+    __data_region_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/common-ram.ld>
 #include <linker/kobject-data.ld>
@@ -322,7 +329,7 @@ SECTIONS
  */
 #include <snippets-data-sections.ld>
 
-    __data_ram_end = .;
+    __data_region_end = .;
 
 #ifndef CONFIG_USERSPACE
    SECTION_DATA_PROLOGUE(_BSS_SECTION_NAME,(NOLOAD),)

include/arch/arm64/scripts/linker.ld

@@ -248,9 +248,11 @@ SECTIONS
 
 #include <linker/common-noinit.ld>
 
+    __data_region_start = .;
+
     SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
     {
-        __data_ram_start = .;
+	__data_start = .;
         *(.data)
         *(".data.*")
         *(".kernel.*")
@@ -260,9 +262,13 @@ SECTIONS
  */
 #include <snippets-rwdata.ld>
 
+        __data_end = .;
+
     } GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+    __data_size = __data_end - __data_start;
+    __data_load_start = LOADADDR(_DATA_SECTION_NAME);
 
-    __data_rom_start = LOADADDR(_DATA_SECTION_NAME);
+    __data_region_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/common-ram.ld>
 #include <linker/kobject-data.ld>
@@ -273,7 +279,7 @@ SECTIONS
  */
 #include <snippets-data-sections.ld>
 
-    __data_ram_end = .;
+    __data_region_end = .;
 
 
     /* Define linker symbols */

include/arch/nios2/linker.ld

@@ -97,7 +97,7 @@ SECTIONS
         }
 
     GROUP_START(ROMABLE_REGION)
-    _image_rom_start = _ROM_ADDR;
+    __rom_region_start = _ROM_ADDR;
 
     SECTION_PROLOGUE(_RESET_SECTION_NAME,,)
     {
@@ -119,21 +119,21 @@ SECTIONS
          * we are going to waste flash space? */
         . = ALT_CPU_RESET_ADDR;
 
-        _image_text_start = .;
+        __text_region_start = .;
 
         *(.text)
         *(".text.*")
         *(.gnu.linkonce.t.*)
         } GROUP_LINK_IN(ROMABLE_REGION)
 
-    _image_text_end = .;
+    __text_region_end = .;
 
 #if defined(CONFIG_GP_ALL_DATA)
         _gp = ABSOLUTE(. + 0x8000);
         PROVIDE(gp = _gp);
 #endif
 
-    _image_rodata_start = .;
+    __rodata_region_start = .;
 
 #include <linker/common-rom.ld>
 
@@ -159,7 +159,7 @@ SECTIONS
     _image_rodata_size = _image_rodata_end - _image_rodata_start;
 
     _image_rom_end = .;
-    __data_rom_start = ALIGN(4);    /* XIP imaged DATA ROM start addr */
+    __data_region_load_start = ALIGN(4);    /* XIP imaged DATA ROM start addr */
 
     GROUP_END(ROMABLE_REGION)
 
@@ -175,7 +175,7 @@ SECTIONS
     SECTION_DATA_PROLOGUE(_EXCEPTION_SECTION_NAME,,)
         {
             _image_ram_start = .;
-            __data_ram_start = .;
+            __data_region_start = .;
 
             KEEP(*(".exception.entry.*"))
             *(".exception.other.*")
@@ -191,6 +191,7 @@ SECTIONS
 
     SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
         {
+	__data_start = .;
         *(.data)
         *(".data.*")
 
@@ -223,8 +224,11 @@ SECTIONS
  * zephyr_linker_sources() Cmake function.
  */
 #include <snippets-ram-sections.ld>
+	__data_end = .;
 
         } GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+    __data_size = __data_end - __data_start;
+    __data_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/cplusplus-ram.ld>
 
@@ -233,7 +237,7 @@ SECTIONS
  */
 #include <snippets-data-sections.ld>
 
-    __data_ram_end = .;
+    __data_region_end = .;
 
 	SECTION_DATA_PROLOGUE(_BSS_SECTION_NAME,(NOLOAD),)
         {

include/arch/posix/linker.ld

@@ -53,7 +53,7 @@ SECTIONS
  */
 #include <snippets-data-sections.ld>
 
- __data_ram_end = .;
+__data_region_end = .;
 
 /* Located in generated directory. This file is populated by the
  * zephyr_linker_sources() Cmake function.

include/arch/riscv/common/linker.ld

@@ -229,11 +229,13 @@ SECTIONS
 #include <linker/common-noinit.ld>
 #include <linker/cplusplus-ram.ld>
 
+    __data_region_start = .;
+
     SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
 	{
 		 . = ALIGN(4);
 		/* _image_ram_start = .; */
-		 __data_ram_start = .;
+		 __data_start = .;
 
 		 *(.data)
 		 *(".data.*")
@@ -260,10 +262,13 @@ SECTIONS
  * zephyr_linker_sources() Cmake function.
  */
 #include <snippets-rwdata.ld>
+		 __data_end = .;
 
 	}  GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+	__data_size = __data_end - __data_start;
+	__data_load_start = LOADADDR(_DATA_SECTION_NAME);
 
-	__data_rom_start = LOADADDR(_DATA_SECTION_NAME);
+	__data_region_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/common-ram.ld>
 #include <linker/kobject-data.ld>
@@ -278,7 +283,7 @@ SECTIONS
  */
 #include <snippets-data-sections.ld>
 
-    __data_ram_end = .;
+    __data_region_end = .;
 
     MPU_MIN_SIZE_ALIGN
 

include/arch/sparc/linker.ld

@@ -67,7 +67,8 @@ SECTIONS
 
     _image_rom_end = .;
 
-    __data_rom_start = .;
+    __data_region_load_start = .;
+    __data_region_start = .;
 
 
     SECTION_PROLOGUE(.plt,,)
@@ -84,7 +85,7 @@ SECTIONS
 	{
 		 . = ALIGN(8);
 		 _image_ram_start = .;
-		 __data_ram_start = .;
+		 __data_start = .;
 
 		 *(.data)
 		 *(.data.*)
@@ -96,7 +97,11 @@ SECTIONS
  */
 #include <snippets-rwdata.ld>
 
+		 __data_end = .;
+
 	}  GROUP_DATA_LINK_IN(REGION_DATA_VMA, REGION_DATA_LMA)
+    __data_size = __data_end - __data_start;
+    __data_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/common-ram.ld>
 
@@ -110,7 +115,7 @@ SECTIONS
  */
 #include <snippets-data-sections.ld>
 
-    __data_ram_end = .;
+    __data_region_end = .;
 
     SECTION_DATA_PROLOGUE(_BSS_SECTION_NAME,(NOLOAD),)
 	{

include/arch/x86/ia32/linker.ld

@@ -437,10 +437,12 @@ SECTIONS
 
 	MMU_PAGE_ALIGN_PERM
 
+
 	SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
 	{
 
-	__data_ram_start = .;
+	__data_region_start = .;
+	__data_start = .;
 
 	*(.data)
 	*(".data.*")
@@ -462,9 +464,13 @@ SECTIONS
 #endif /* !CONFIG_LINKER_USE_PINNED_SECTION */
 
 	. = ALIGN(4);
+	__data_end = .;
+
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+	__data_size = __data_end - __data_start;
+	__data_load_start = LOADADDR(_DATA_SECTION_NAME);
 
-	__data_rom_start = LOADADDR(_DATA_SECTION_NAME);
+	__data_region_load_start = LOADADDR(_DATA_SECTION_NAME);
 
 #include <linker/cplusplus-ram.ld>
 
@@ -482,7 +488,7 @@ SECTIONS
 #include <snippets-data-sections.ld>
 
 	MMU_PAGE_ALIGN
-	__data_ram_end = .;
+	__data_region_end = .;
 
 	/* All unused memory also owned by the kernel for heaps */
 	__kernel_ram_end = KERNEL_BASE_ADDR + KERNEL_RAM_SIZE;
@@ -536,6 +542,6 @@ SECTIONS
  * to 3 extra bytes copied in next section (BSS). At run time, the XIP copy
  * is done first followed by clearing the BSS section.
  */
-__data_size = (__data_ram_end - __data_ram_start);
+__data_size = (__data_region_end - __data_region_start);
 __data_num_words = (__data_size + 3) >> 2;
 #endif

include/linker/linker-defs.h

@@ -172,9 +172,9 @@
 GDATA(__bss_start)
 GDATA(__bss_num_words)
 #ifdef CONFIG_XIP
-GDATA(__data_rom_start)
-GDATA(__data_ram_start)
-GDATA(__data_num_words)
+GDATA(__data_region_load_start)
+GDATA(__data_region_start)
+GDATA(__data_region_num_words)
 #endif
 
 #else /* ! _ASMLANGUAGE */
@@ -224,9 +224,9 @@ extern char __bss_end[];
 
 /* Used by z_data_copy() or arch-specific implementation */
 #ifdef CONFIG_XIP
-extern char __data_rom_start[];
-extern char __data_ram_start[];
-extern char __data_ram_end[];
+extern char __data_region_load_start[];
+extern char __data_region_start[];
+extern char __data_region_end[];
 #endif /* CONFIG_XIP */
 
 #ifdef CONFIG_MMU