[RFC PATCH 2/4] arm: Prepare linker scripts for memory permissions

[Jerome Forissier]

Hi Ilias,

On 1/30/25 08:20, Ilias Apalodimas wrote:
> Upcoming patches are switching the memory mappings to RW, RO, RW^X page
> permissions after the U-Boot binary and its data are relocated. Add
> annotations in the linker scripts to and mark text, data, rodata etc
> sections and align them to a page boundary
> 
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> ---
>  Makefile                       | 15 +++++++++------
>  arch/arm/cpu/armv8/u-boot.lds  | 32 +++++++++++++++++++-------------
>  include/asm-generic/sections.h |  2 ++
>  lib/efi_loader/efi_runtime.c   |  2 ++
>  4 files changed, 32 insertions(+), 19 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 33bb86343c5b..8d7c062ec830 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2176,13 +2176,16 @@ System.map:	u-boot
>  # ARM relocations should all be R_ARM_RELATIVE (32-bit) or
>  # R_AARCH64_RELATIVE (64-bit).
>  checkarmreloc: u-boot
> -	@RELOC="`$(CROSS_COMPILE)readelf -r -W $< | cut -d ' ' -f 4 | \
> +	@RELOCS="`$(CROSS_COMPILE)readelf -r -W $< | cut -d ' ' -f 4 | \
>  		grep R_A | sort -u`"; \
> -	if test "$$RELOC" != "R_ARM_RELATIVE" -a \
> -		 "$$RELOC" != "R_AARCH64_RELATIVE"; then \
> -		echo "$< contains unexpected relocations: $$RELOC"; \
> -		false; \
> -	fi
> +	for reloc in $$RELOCS; do \
> +		if [ "$$reloc" != "R_ARM_RELATIVE" -a \
> +		     "$$reloc" != "R_AARCH64_RELATIVE" -a \
> +		"$$reloc" != "R_AARCH64_NONE" ]; then \
> +			echo "$< contains unexpected relocations: $$reloc"; \
> +			false; \

s/false/exit 1/ otherwise the loop won't break and make won't get a
failure status unless the error is on the last reloc.

> +		fi; \
> +	done

This Makefile change seems unrelated to the current patch. Should it
go into a separate fixup patch?
 
>  tools/version.h: include/version.h
>  	$(Q)mkdir -p $(dir $@)
> diff --git a/arch/arm/cpu/armv8/u-boot.lds b/arch/arm/cpu/armv8/u-boot.lds
> index 857f44412e07..18e168e27135 100644
> --- a/arch/arm/cpu/armv8/u-boot.lds
> +++ b/arch/arm/cpu/armv8/u-boot.lds
> @@ -22,7 +22,7 @@ SECTIONS
>  
>  	. = ALIGN(8);
>  	__image_copy_start = ADDR(.text);
> -	.text :
> +	.text ALIGN(4096):
>  	{
>  		CPUDIR/start.o (.text*)
>  	}
> @@ -36,9 +36,12 @@ SECTIONS
>                  __efi_runtime_stop = .;
>  	}
>  
> -	.text_rest :
> +	.text_rest ALIGN(4096) :
>  	{
> +		__text_start = .;
>  		*(.text*)
> +		. = ALIGN(4096);
> +		__text_end = .;
>  	}
>  
>  #ifdef CONFIG_ARMV8_PSCI
> @@ -98,27 +101,30 @@ SECTIONS
>  	}
>  #endif
>  
> -	. = ALIGN(8);
> -	.rodata : { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }
> +	.rodata ALIGN(4096): {
> +	    __start_rodata = .;
> +	    *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*)))
> +	    . = ALIGN(4096);
> +	    __end_rodata = .;
> +	}
>  
> -	. = ALIGN(8);
> -	.data : {
> +	.data ALIGN(4096) : {
> +	    __start_data = .;
>  		*(.data*)
> +	    . = ALIGN(4096);
> +	    __end_data = .;
>  	}
>  
> -	. = ALIGN(8);
> -
> -	. = .;
> -
>  	. = ALIGN(8);
>  	__u_boot_list : {
>  		KEEP(*(SORT(__u_boot_list*)));
>  	}
>  
> -	.efi_runtime_rel : {
> +	.efi_runtime_rel ALIGN(4096) : {
>                  __efi_runtime_rel_start = .;
>  		*(.rel*.efi_runtime)
>  		*(.rel*.efi_runtime.*)
> +		. = ALIGN(4096);
>                  __efi_runtime_rel_stop = .;
>  	}
>  
> @@ -136,10 +142,10 @@ SECTIONS
>  	/*
>  	 * arch/arm/lib/crt0_64.S assumes __bss_start - __bss_end % 8 == 0
>  	 */
> -	.bss ALIGN(8) : {
> +	.bss ALIGN(4096) : {
>  		__bss_start = .;
>  		*(.bss*)
> -		. = ALIGN(8);
> +		. = ALIGN(4096);
>  		__bss_end = .;
>  	}
>  
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index b6bca53db10d..5626df796f33 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -23,6 +23,7 @@ extern char __kprobes_text_start[], __kprobes_text_end[];
>  extern char __entry_text_start[], __entry_text_end[];
>  extern char __initdata_begin[], __initdata_end[];
>  extern char __start_rodata[], __end_rodata[];
> +extern char __start_data[], __end_data[];
>  extern char __efi_helloworld_begin[];
>  extern char __efi_helloworld_end[];
>  extern char __efi_var_file_begin[];
> @@ -63,6 +64,7 @@ static inline int arch_is_kernel_data(unsigned long addr)
>  
>  /* Start of U-Boot text region */
>  extern char __text_start[];
> +extern char __text_end[];
>  
>  /* This marks the text region which must be relocated */
>  extern char __image_copy_start[], __image_copy_end[];
> diff --git a/lib/efi_loader/efi_runtime.c b/lib/efi_loader/efi_runtime.c
> index 35eb6a777665..c10a79301a92 100644
> --- a/lib/efi_loader/efi_runtime.c
> +++ b/lib/efi_loader/efi_runtime.c
> @@ -742,6 +742,8 @@ void efi_runtime_relocate(ulong offset, struct efi_mem_desc *map)
>  		      rel->info, *p, rel->offset);
>  
>  		switch (rel->info & R_MASK) {
> +		case 0:
> +			break;

It looks like this may need to go into the same fixup patch as the
Makefile changes above.

>  		case R_RELATIVE:
>  #ifdef IS_RELA
>  		newaddr = rel->addend + offset - CONFIG_TEXT_BASE;

For the linker script changes:

Acked-by: Jerome Forissier <jerome.forissier at linaro.org>