ladmanj
Reputation: 61
linkerscript for two copies of the executable code at two different adresses in two sections of an elf file
I have a short booter program (not entire bootloader because of the available space and size of the communication stack) which expects two alternative end applications at two different memory locations. The applications can update its alternative counterpart in the runtime.
I would like to have position independent executable of the end application, but that's not possible even, because the PIE code is a little bigger and doesn't fit in the memory section.
I am able to link the application to two independent elf binaries with two independent linker scripts with different memory ranges occupied by it.
I would like, however to prepare such a linker script to pack two copies of the application relocated to the two memory areas.
Is something like that even possible? I didn't figure it out unfortunately.
In short, I need to combine these three together into single ELF file.
Booter
App A
App B
The linker-scripts used are modified versions of the STM32cubeIDE default ones. Booter:
/* Entry Point */
ENTRY(Reset_Handler)
/* Highest address of the user mode stack */
_estack = ORIGIN(RAM) + LENGTH(RAM); /* end of "RAM" Ram type memory */
_Min_Heap_Size = 0x0; /* required amount of heap */
_Min_Stack_Size = 0x70; /* required amount of stack */
/* Memories definition */
MEMORY
{
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 256
FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 2K
FLASH_APA (rx) : ORIGIN = 0x8000800, LENGTH = 30K
FLASH_APB (rx) : ORIGIN = 0x8008000, LENGTH = 30K
UFLASH (rw) : ORIGIN = 0x800f800, LENGTH = 2K
}
/* Sections */
SECTIONS
{
/* The startup code into "FLASH" Rom type memory */
.isr_vector :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
} >FLASH
/* User data goes into "FLASH" Rom type memory */
.wrflash :
{
. = ALIGN(4);
*(.wrflash) /* .wrflash sections (constants, strings, etc.) */
*(.wrflash*) /* .wrflash* sections (constants, strings, etc.) */
. = ALIGN(4);
} >UFLASH
/* User app A goes into "FLASH" Rom type memory */
.app_a :
{
. = ALIGN(4);
*(.app_a) /* .app_a sections (constants, strings, etc.) */
*(.app_a*) /* .app_a* sections (constants, strings, etc.) */
. = ALIGN(4);
} >FLASH_APA
/* User app A goes into "FLASH" Rom type memory */
.app_b :
{
. = ALIGN(4);
*(.app_b) /* .app_b sections (constants, strings, etc.) */
*(.app_b*) /* .app_b* sections (constants, strings, etc.) */
. = ALIGN(4);
} >FLASH_APB
/* The program code and other data into "FLASH" Rom type memory */
.text :
{
. = ALIGN(4);
*(.text) /* .text sections (code) */
*(.text*) /* .text* sections (code) */
*(.glue_7) /* glue arm to thumb code */
*(.glue_7t) /* glue thumb to arm code */
*(.eh_frame)
KEEP (*(.init))
KEEP (*(.fini))
. = ALIGN(4);
_etext = .; /* define a global symbols at end of code */
} >FLASH
/* Constant data into "FLASH" Rom type memory */
.rodata :
{
. = ALIGN(4);
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
. = ALIGN(4);
} >FLASH
.ARM.extab : {
. = ALIGN(4);
*(.ARM.extab* .gnu.linkonce.armextab.*)
. = ALIGN(4);
} >FLASH
.ARM : {
. = ALIGN(4);
__exidx_start = .;
*(.ARM.exidx*)
__exidx_end = .;
. = ALIGN(4);
} >FLASH
.preinit_array :
{
. = ALIGN(4);
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array*))
PROVIDE_HIDDEN (__preinit_array_end = .);
. = ALIGN(4);
} >FLASH
.init_array :
{
. = ALIGN(4);
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array*))
PROVIDE_HIDDEN (__init_array_end = .);
. = ALIGN(4);
} >FLASH
.fini_array :
{
. = ALIGN(4);
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array*))
PROVIDE_HIDDEN (__fini_array_end = .);
. = ALIGN(4);
} >FLASH
/* Used by the startup to initialize data */
_sidata = LOADADDR(.data);
/* Initialized data sections into "RAM" Ram type memory */
.data :
{
. = ALIGN(4);
_sdata = .; /* create a global symbol at data start */
*(.data) /* .data sections */
*(.data*) /* .data* sections */
*(.RamFunc) /* .RamFunc sections */
*(.RamFunc*) /* .RamFunc* sections */
. = ALIGN(4);
_edata = .; /* define a global symbol at data end */
} >RAM AT> FLASH
/* Uninitialized data section into "RAM" Ram type memory */
. = ALIGN(4);
.bss :
{
/* This is used by the startup in order to initialize the .bss section */
_sbss = .; /* define a global symbol at bss start */
__bss_start__ = _sbss;
*(.bss)
*(.bss*)
*(COMMON)
. = ALIGN(4);
_ebss = .; /* define a global symbol at bss end */
__bss_end__ = _ebss;
} >RAM
/* User_heap_stack section, used to check that there is enough "RAM" Ram type memory left */
._user_heap_stack :
{
. = ALIGN(8);
PROVIDE ( end = . );
PROVIDE ( _end = . );
. = . + _Min_Heap_Size;
. = . + _Min_Stack_Size;
. = ALIGN(8);
} >RAM
/* Remove information from the compiler libraries */
/DISCARD/ :
{
libc.a ( * )
libm.a ( * )
libgcc.a ( * )
}
.ARM.attributes 0 : { *(.ARM.attributes) }
}
App A:
/* Entry Point */
ENTRY(Reset_Handler)
/* Highest address of the user mode stack */
_estack = ORIGIN(RAM) + LENGTH(RAM); /* end of "RAM" Ram type memory */
_Min_Heap_Size = 0x200; /* required amount of heap */
_Min_Stack_Size = 0x400; /* required amount of stack */
/* Memories definition */
MEMORY
{
RAM (xrw) : ORIGIN = 0x20000100, LENGTH = 7936
FLASH (rx) : ORIGIN = 0x8000800, LENGTH = 30K
UFLASH (rw) : ORIGIN = 0x800f800, LENGTH = 2K
}
/* Sections */
SECTIONS
{
/* The startup code into "FLASH" Rom type memory */
.isr_vector :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
} >FLASH
/* User data goes into "FLASH" Rom type memory */
.wrflash :
{
. = ALIGN(4);
*(.wrflash) /* .wrflash sections (constants, strings, etc.) */
*(.wrflash*) /* .wrflash* sections (constants, strings, etc.) */
. = ALIGN(4);
} >UFLASH
/* The program code and other data into "FLASH" Rom type memory */
.text :
{
. = ALIGN(4);
*(.text) /* .text sections (code) */
*(.text*) /* .text* sections (code) */
*(.glue_7) /* glue arm to thumb code */
*(.glue_7t) /* glue thumb to arm code */
*(.eh_frame)
KEEP (*(.init))
KEEP (*(.fini))
. = ALIGN(4);
_etext = .; /* define a global symbols at end of code */
} >FLASH
/* Constant data into "FLASH" Rom type memory */
.rodata :
{
. = ALIGN(4);
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
. = ALIGN(4);
} >FLASH
.ARM.extab : {
. = ALIGN(4);
*(.ARM.extab* .gnu.linkonce.armextab.*)
. = ALIGN(4);
} >FLASH
.ARM : {
. = ALIGN(4);
__exidx_start = .;
*(.ARM.exidx*)
__exidx_end = .;
. = ALIGN(4);
} >FLASH
.preinit_array :
{
. = ALIGN(4);
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array*))
PROVIDE_HIDDEN (__preinit_array_end = .);
. = ALIGN(4);
} >FLASH
.init_array :
{
. = ALIGN(4);
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array*))
PROVIDE_HIDDEN (__init_array_end = .);
. = ALIGN(4);
} >FLASH
.fini_array :
{
. = ALIGN(4);
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array*))
PROVIDE_HIDDEN (__fini_array_end = .);
. = ALIGN(4);
} >FLASH
/* Used by the startup to initialize data */
_sidata = LOADADDR(.data);
/* Initialized data sections into "RAM" Ram type memory */
.data :
{
. = ALIGN(4);
_sdata = .; /* create a global symbol at data start */
*(.data) /* .data sections */
*(.data*) /* .data* sections */
*(.RamFunc) /* .RamFunc sections */
*(.RamFunc*) /* .RamFunc* sections */
. = ALIGN(4);
_edata = .; /* define a global symbol at data end */
} >RAM AT> FLASH
/* Uninitialized data section into "RAM" Ram type memory */
. = ALIGN(4);
.bss :
{
/* This is used by the startup in order to initialize the .bss section */
_sbss = .; /* define a global symbol at bss start */
__bss_start__ = _sbss;
*(.bss)
*(.bss*)
*(COMMON)
. = ALIGN(4);
_ebss = .; /* define a global symbol at bss end */
__bss_end__ = _ebss;
} >RAM
/* User_heap_stack section, used to check that there is enough "RAM" Ram type memory left */
._user_heap_stack :
{
. = ALIGN(8);
PROVIDE ( end = . );
PROVIDE ( _end = . );
. = . + _Min_Heap_Size;
. = . + _Min_Stack_Size;
. = ALIGN(8);
} >RAM
/* Remove information from the compiler libraries */
/DISCARD/ :
{
libc.a ( * )
libm.a ( * )
libgcc.a ( * )
}
.ARM.attributes 0 : { *(.ARM.attributes) }
}
I will not spam you with the App B one, because it looks the same except the memory region used.
I have tried to stuff both A and B into one linker-script, but that did nothing. Not tried anything to put the booter code in, because no idea how to do it.
I know the code runs properly because i can at least combine the files with this bash script:
#!/bin/bash
rm ./app*.bin
rm ./app*.elf
arm-none-eabi-objcopy -S --remove-section .wrflash -O binary Release\ FLASH\ A/app_a.elf appa.bin
arm-none-eabi-objcopy -S --remove-section .wrflash -O binary Release\ FLASH\ B/app_b.elf appb.bin
arm-none-eabi-objcopy --update-section .app_a=appa.bin --update-section .app_b=appb.bin ../mblboot-0.1/Debug/mblboot-0.1.elf mblboot-0.1.upd.elf
It will be much better to link the whole file by the linker instead.
Upvotes: 0
Views: 40
Answers (0)
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