cmake: Add the TEXT_START location to zephyr_linker_sources()

Places linker code at or near the beginning of the text section.

Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>

cmake/extensions.cmake

@@ -873,15 +873,17 @@ endfunction(zephyr_check_compiler_flag_hardcoded)
 #    NOINIT       Inside the noinit output section.
 #    RWDATA       Inside the data output section.
 #    RODATA       Inside the rodata output section.
+#    TEXT_START   At the beginning of the text section, i.e. the beginning of
+#                 the image.
 #    RAM_SECTIONS Inside the RAMABLE_REGION GROUP.
 #    SECTIONS     Near the end of the file. Don't use this when linking into
 #                 RAMABLE_REGION, use RAM_SECTIONS instead.
 #
 # Use NOINIT, RWDATA, and RODATA unless they don't work for your use case.
 #
-# When placing into NOINIT, RWDATA, or RODATA, the contents of the files will be
-# placed inside an output section, so assume the section definition is already
-# present, e.g.:
+# When placing into NOINIT, RWDATA, RODATA, or TEXT_START the contents of the files
+# will be placed inside an output section, so assume the section definition is
+# already present, e.g.:
 #    _mysection_start = .;
 #    KEEP(*(.mysection));
 #    _mysection_end = .;
@@ -909,6 +911,7 @@ function(zephyr_linker_sources location)
   set(snippet_base      "${__build_dir}/include/generated")
   set(sections_path     "${snippet_base}/snippets-sections.ld")
   set(ram_sections_path "${snippet_base}/snippets-ram-sections.ld")
+  set(text_start_path   "${snippet_base}/snippets-text-start.ld")
   set(noinit_path       "${snippet_base}/snippets-noinit.ld")
   set(rwdata_path       "${snippet_base}/snippets-rwdata.ld")
   set(rodata_path       "${snippet_base}/snippets-rodata.ld")
@@ -918,6 +921,7 @@ function(zephyr_linker_sources location)
   if (NOT DEFINED cleared)
     file(WRITE ${sections_path} "")
     file(WRITE ${ram_sections_path} "")
+    file(WRITE ${text_start_path} "")
     file(WRITE ${noinit_path} "")
     file(WRITE ${rwdata_path} "")
     file(WRITE ${rodata_path} "")
@@ -929,6 +933,8 @@ function(zephyr_linker_sources location)
     set(snippet_path "${sections_path}")
   elseif("${location}" STREQUAL "RAM_SECTIONS")
     set(snippet_path "${ram_sections_path}")
+  elseif("${location}" STREQUAL "TEXT_START")
+    set(snippet_path "${text_start_path}")
   elseif("${location}" STREQUAL "NOINIT")
     set(snippet_path "${noinit_path}")
   elseif("${location}" STREQUAL "RWDATA")

include/arch/arc/v2/linker.ld

@@ -87,6 +87,10 @@ SECTIONS {
 		_image_rom_start = .;
 		_image_text_start = .;
 
+/* Located in generated directory. This file is populated by the
+ * zephyr_linker_sources() Cmake function.
+ */
+#include <snippets-text-start.ld>
 /* when !XIP, .text is in RAM, and vector table must be at its very start */
 
 		KEEP(*(.exc_vector_table))

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

@@ -156,6 +156,10 @@ SECTIONS
 
 	. = CONFIG_TEXT_SECTION_OFFSET;
 
+/* Located in generated directory. This file is populated by the
+ * zephyr_linker_sources() Cmake function.
+ */
+#include <snippets-text-start.ld>
 #if defined(CONFIG_SW_VECTOR_RELAY)
 	KEEP(*(.vector_relay_table))
 	KEEP(*(".vector_relay_table.*"))

include/arch/arm/cortex_r/scripts/linker.ld

@@ -153,6 +153,10 @@ SECTIONS
 
 	. = CONFIG_TEXT_SECTION_OFFSET;
 
+/* Located in generated directory. This file is populated by the
+ * zephyr_linker_sources() Cmake function.
+ */
+#include <snippets-text-start.ld>
 #if defined(CONFIG_SW_VECTOR_RELAY)
 	KEEP(*(.vector_relay_table))
 	KEEP(*(".vector_relay_table.*"))

include/arch/nios2/linker.ld

@@ -120,6 +120,12 @@ SECTIONS
         . = ALT_CPU_RESET_ADDR;
 
         _image_text_start = .;
+
+/* Located in generated directory. This file is populated by the
+ * zephyr_linker_sources() Cmake function.
+ */
+#include <snippets-text-start.ld>
+
         *(.text)
         *(".text.*")
         *(.gnu.linkonce.t.*)

include/arch/riscv/common/linker.ld

@@ -88,6 +88,12 @@ SECTIONS
 		KEEP(*(".openocd_debug.*"))
 
 		_image_text_start = .;
+
+/* Located in generated directory. This file is populated by the
+ * zephyr_linker_sources() Cmake function.
+ */
+#include <snippets-text-start.ld>
+
 		*(.text)
 		*(".text.*")
 		*(.gnu.linkonce.t.*)

include/arch/x86/ia32/linker.ld

@@ -86,6 +86,12 @@ SECTIONS
 	SECTION_PROLOGUE(_TEXT_SECTION_NAME,,)
 	{
 	. = CONFIG_TEXT_SECTION_OFFSET;
+
+/* Located in generated directory. This file is populated by the
+ * zephyr_linker_sources() Cmake function.
+ */
+#include <snippets-text-start.ld>
+
 	*(.text_start)
 	*(".text_start.*")
 	*(.text)

soc/riscv/openisa_rv32m1/linker.ld

@@ -133,6 +133,12 @@ SECTIONS
 	KEEP(*(".openocd_debug.*"))
 
 	_image_text_start = .;
+
+/* Located in generated directory. This file is populated by the
+ * zephyr_linker_sources() Cmake function.
+ */
+#include <snippets-text-start.ld>
+
 	*(.text .text.*)
 	*(.gnu.linkonce.t.*)
 	*(.eh_frame)