[PATCH v1 3/6] arm: Prepare linker scripts for memory permissions

[Ilias Apalodimas]

I'm just replying to myself here but I'll send a v2 when the patches
are reviewed.

I can add the linker under an ifdef, so u-boot size won't change
unless a Kconfig options is selected

/Ilias

On Wed, 5 Feb 2025 at 09:17, Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> Upcoming patches are switching the memory mappings to RW, RO, RX
> after the U-Boot binary and its data are relocated. Add
> annotations in the linker scripts to and mark text, data, rodata
> sections and align them to a page boundary.
>
> It's worth noting that efi_runtime relocations are left untouched for
> now. The efi runtime regions can be relocated by the OS when the latter
> is calling SetVirtualAddressMap. Which means we have to configure the
> pages as RX for U-Boot but convert them to RWX just before
> ExitBootServices. It also needs extra code in efi_tuntime relocation
> code since R_AARCH64_NONE are emitted as well if we page align the
> section. Keep it out for now and we can fix it in future patches.
>
> Acked-by: Jerome Forissier <jerome.forissier at linaro.org>
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> ---
>  arch/arm/cpu/armv8/u-boot.lds  | 29 +++++++++++++++++------------
>  include/asm-generic/sections.h |  2 ++
>  2 files changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm/cpu/armv8/u-boot.lds b/arch/arm/cpu/armv8/u-boot.lds
> index 857f44412e07..35afc3cbe7ec 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
> @@ -98,18 +101,20 @@ 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*)));
> @@ -136,10 +141,10 @@ 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 3fd5c772a1af..024b1adde270 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[];
> --
> 2.47.2
>