Re: [PATCH v3 18/23] riscv: linker script: create separate PT_LOAD segments for text, rodata, and data

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 1/8/26 4:50 PM, Sascha Hauer wrote:
> Fix the linker script to generate three distinct PT_LOAD segments with
> correct permissions instead of combining .rodata with .data.
> 
> Before this fix, the linker auto-generated only two PT_LOAD segments:
> 1. Text segment (PF_R|PF_X)
> 2. Data segment (PF_R|PF_W) - containing .rodata, .data, .bss, etc.
> 
> This caused .rodata to be mapped with write permissions when
> riscv_mmu_setup_from_elf() or riscv_pmp_setup_from_elf() set up memory
> permissions based on ELF segments, defeating the W^X protection.

There is no riscv_pmp_setup_from_elf in this series.

> 
> With explicit PHDRS directives, we now generate three segments:
> 1. text segment (PF_R|PF_X): .text and related code sections
> 2. rodata segment (PF_R): .rodata and related read-only sections
> 3. data segment (PF_R|PF_W): .data, .bss, and related sections
> 
> This ensures riscv_mmu_setup_from_elf() and riscv_pmp_setup_from_elf()
> correctly map .rodata as read-only instead of read-write.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  arch/riscv/lib/barebox.lds.S | 38 +++++++++++++++++++++++++-------------
>  1 file changed, 25 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/riscv/lib/barebox.lds.S b/arch/riscv/lib/barebox.lds.S
> index 03b3a967193cfee1c67b96632cf972a553e8bec4..77f854e73e2013ca332a0a94fd1deaa2b9978a1d 100644
> --- a/arch/riscv/lib/barebox.lds.S
> +++ b/arch/riscv/lib/barebox.lds.S
> @@ -16,14 +16,23 @@
>  OUTPUT_ARCH(BAREBOX_OUTPUT_ARCH)
>  ENTRY(start)
>  OUTPUT_FORMAT(BAREBOX_OUTPUT_FORMAT)
> +
> +PHDRS
> +{
> +	text PT_LOAD FLAGS(5);     /* PF_R | PF_X */
> +	rodata PT_LOAD FLAGS(4);   /* PF_R */
> +	data PT_LOAD FLAGS(6);     /* PF_R | PF_W */
> +	dynamic PT_DYNAMIC FLAGS(4); /* PF_R */

Move before data.

> +	.dynamic : { *(.dynamic) } :data :dynamic

Move to rodata and replace :data with :rodata.

Cheers,
Ahmad

>  
>  	_edata = .;
>  
> -	.image_end : { *(.__image_end) }
> +	.image_end : { *(.__image_end) } :data
>  
>  	. = ALIGN(4);
> -	.__bss_start :  { *(.__bss_start) }
> -	.bss : { *(.bss*) }
> -	.__bss_stop :  { *(.__bss_stop) }
> +	.__bss_start :  { *(.__bss_start) } :data
> +	.bss : { *(.bss*) } :data
> +	.__bss_stop :  { *(.__bss_stop) } :data
>  	_end = .;
>  	_barebox_image_size = __bss_start;
>  }
> 

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