build: x86: add some flexibility in custom linker scripts

If a particular project needs to add additional data to the
binary image, in most cases the entire linker script needs to
forked into the project space, causing maintenance issues if
the main linker script is changed.

Now we add some Kconfig options to allow a project to specify
some additional linker scripts which get included by the main
one in a few key areas:

1) In the definition to the 'rodata' section, which can allow
additional data to be included in this ROM section.

2) In the definition to the 'datas' section, which allows
additional data to be included in this RAM section.

3) Arbitrary additional sections to be included at the end of
the binary.

For 1 and 2, this is useful to include data generated outside of
the normal C compilation, such as data structures that are created
by special build tools.

3 is useful for including arbitrary binary blobs inside the final
image, such as for peripheral or co-processor firmware.

Change-Id: I5738d3d6da25f5bc96cda8ae806bf1a3fb34bd5d
Signed-off-by: Andrew Boie <[email protected]>

Makefile

@@ -843,6 +843,7 @@ $(KERNEL_NAME).lnk: $(zephyr-deps)
 linker.cmd: $(zephyr-deps)
 	$(Q)$(CC) -x assembler-with-cpp -nostdinc -undef -E -P \
 	$(LDFLAG_LINKERCMD) $(LD_TOOLCHAIN) -I$(srctree)/include \
+	-I$(SOURCE_DIR) \
 	-I$(objtree)/include/generated $(EXTRA_LINKER_CMD_OPT) $(KBUILD_LDS) -o $@
 
 PREBUILT_KERNEL = $(KERNEL_NAME)_prebuilt.elf

include/arch/arc/v2/linker.ld

@@ -117,6 +117,12 @@ SECTIONS {
 		*(.rodata)
 		*(".rodata.*")
 		*(.gnu.linkonce.r.*)
+
+#ifdef CONFIG_CUSTOM_RODATA_LD
+/* Located in project source directory */
+#include <custom-rodata.ld>
+#endif
+
 	} GROUP_LINK_IN(ROMABLE_REGION)
 
 	_image_rom_end = .;
@@ -135,6 +141,11 @@ SECTIONS {
 		*(.data)
 		*(".data.*")
 
+#ifdef CONFIG_CUSTOM_RWDATA_LD
+/* Located in project source directory */
+#include <custom-rwdata.ld>
+#endif
+
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 
 #include <linker/common-ram.ld>
@@ -184,4 +195,9 @@ SECTIONS {
 	}
 	ASSERT(SIZEOF(initlevel_error) == 0, "Undefined initialization levels used.")
 
+#ifdef CONFIG_CUSTOM_SECTIONS_LD
+/* Located in project source directory */
+#include <custom-sections.ld>
+#endif
+
 	}

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

@@ -139,6 +139,11 @@ SECTIONS
 	*(.rodata)
 	*(".rodata.*")
 	*(.gnu.linkonce.r.*)
+
+#ifdef CONFIG_CUSTOM_RODATA_LD
+/* Located in project source directory */
+#include <custom-rodata.ld>
+#endif
 	/*
 	 * For XIP images, in order to avoid the situation when __data_rom_start
 	 * is 32-bit aligned, but the actual data is placed right after rodata
@@ -167,6 +172,12 @@ SECTIONS
 	*(.top_of_image_ram.*)
 	*(.data)
 	*(".data.*")
+
+#ifdef CONFIG_CUSTOM_RWDATA_LD
+/* Located in project source directory */
+#include <custom-rwdata.ld>
+#endif
+
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 
 #include <linker/common-ram.ld>
@@ -236,4 +247,9 @@ SECTIONS
 	 } GROUP_LINK_IN(SYSTEM_CONTROL_SPACE)
     GROUP_END(SYSTEM_CONTROL_SPACE)
 
+#ifdef CONFIG_CUSTOM_SECTIONS_LD
+/* Located in project source directory */
+#include <custom-sections.ld>
+#endif
+
     }

include/arch/nios2/linker.ld

@@ -127,6 +127,12 @@ SECTIONS
         *(.rodata)
         *(".rodata.*")
         *(.gnu.linkonce.r.*)
+
+#ifdef CONFIG_CUSTOM_RODATA_LD
+/* Located in project source directory */
+#include <custom-rodata.ld>
+#endif
+
         } GROUP_LINK_IN(ROMABLE_REGION)
 
     _image_rom_end = .;
@@ -177,6 +183,11 @@ SECTIONS
         *(.data)
         *(".data.*")
 
+#ifdef CONFIG_CUSTOM_RWDATA_LD
+/* Located in project source directory */
+#include <custom-rwdata.ld>
+#endif
+
         /* the Nios2 architecture only has 16-bit signed immediate offsets in
          * the instructions, so accessing a general address requires typically
          * three instructions – basically, two for the two halves of the 32-bit
@@ -237,5 +248,10 @@ SECTIONS
 
     GROUP_END(RAMABLE_REGION)
 
+#ifdef CONFIG_CUSTOM_SECTIONS_LD
+/* Located in project source directory */
+#include <custom-sections.ld>
+#endif
+
     }
 

include/arch/x86/linker.ld

@@ -109,6 +109,11 @@ SECTIONS
 	KEEP(*(irq_int_vector_map))
 #endif
 
+#ifdef CONFIG_CUSTOM_RODATA_LD
+/* Located in project source directory */
+#include <custom-rodata.ld>
+#endif
+
 	KEXEC_PGALIGN_PAD(MMU_PAGE_SIZE)
 	} GROUP_LINK_IN(ROMABLE_REGION)
 
@@ -129,6 +134,12 @@ SECTIONS
 	*(.top_of_image_ram.*)
 	*(.data)
 	*(".data.*")
+
+#ifdef CONFIG_CUSTOM_RWDATA_LD
+/* Located in project source directory */
+#include <custom-rwdata.ld>
+#endif
+
 	. = ALIGN(4);
 	} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 
@@ -180,6 +191,7 @@ SECTIONS
 	*(.bottom_of_image_ram.*)
 	} GROUP_LINK_IN(RAMABLE_REGION)
 
+
 	/* Define linker symbols */
 	_image_ram_end = .;
 	_end = .; /* end of image */
@@ -201,6 +213,12 @@ SECTIONS
 	KEEP(*(.gnu.linkonce.intList.*))
 	__INT_LIST_END__ = .;
 	} > IDT_LIST
+
+#ifdef CONFIG_CUSTOM_SECTIONS_LD
+/* Located in project source directory */
+#include <custom-sections.ld>
+#endif
+
 	}
 
 #ifdef CONFIG_XIP

misc/Kconfig

@@ -53,6 +53,27 @@ config CUSTOM_LINKER_SCRIPT
 	linker script and avoid having to change the script provided by
 	Zephyr.
 
+config CUSTOM_RODATA_LD
+	bool "Include custom-rodata.ld"
+	default n
+	help
+	Include a customized linker script fragment for inserting additional
+	data and linker directives into the rodata section.
+
+config CUSTOM_RWDATA_LD
+	bool "Include custom-rwdata.ld"
+	default n
+	help
+	Include a customized linker script fragment for inserting additional
+	data and linker directives into the data section.
+
+config CUSTOM_SECTIONS_LD
+	bool "Include custom-sections.ld"
+	default n
+	help
+	Include a customized linker script fragment for inserting additional
+	arbitrary sections.
+
 config CROSS_COMPILE
 	string "Cross-compiler tool prefix"
 	help