Re: [PATCH] mmu: explicitly map executable non-SDRAM regions with MAP_CODE

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Jun 18, 2025 at 02:36:42PM +0200, Ahmad Fatoum wrote:
> So far we have been setting eXecute Never on MAP_UNCACHED regions and
> left it out for the default MAP_CACHED region.
> 
> We have at least three places, which depend on this to remap non-SDRAM
> regions executable, so ROM code or newly uploaded code can be run.
> 
> Switch them over to use a new MAP_CODE mapping type. For now, this is
> equivalent to MAP_CACHED, but with the addition of W^X support in
> barebox, this will be required to avoid a prefetch abort when MMU
> attributes are used.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
> ---
> Sascha, I think this should be ordered before your MMU patches to avoid
> the known regressions. Let's see what else there is. :)
> ---
>  arch/arm/mach-imx/romapi.c | 3 ++-
>  drivers/firmware/socfpga.c | 3 ++-
>  drivers/hab/habv4.c        | 2 +-
>  include/mmu.h              | 1 +
>  4 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/romapi.c b/arch/arm/mach-imx/romapi.c
> index 10af42f28a76..a4143d372ae8 100644
> --- a/arch/arm/mach-imx/romapi.c
> +++ b/arch/arm/mach-imx/romapi.c
> @@ -299,7 +299,8 @@ void imx93_bootsource(void)
>  		goto out;
>  	}
>  
> -	arch_remap_range((void *)rom.start, rom.start, resource_size(&rom), MAP_CACHED);
> +	/* TODO: restore uncached mapping once we no longer need this? */
> +	arch_remap_range((void *)rom.start, rom.start, resource_size(&rom), MAP_CODE);
>  
>  	OPTIMIZER_HIDE_VAR(rom_api);
>  
> diff --git a/drivers/firmware/socfpga.c b/drivers/firmware/socfpga.c
> index 0f7d11abb588..4b10ca009798 100644
> --- a/drivers/firmware/socfpga.c
> +++ b/drivers/firmware/socfpga.c
> @@ -353,7 +353,8 @@ static int socfpga_fpgamgr_program_finish(struct firmware_handler *fh)
>  		return status;
>  	}
>  
> -	remap_range((void *)CYCLONE5_OCRAM_ADDRESS, PAGE_SIZE, MAP_CACHED);
> +	/* TODO: restore uncached mapping once we no longer need this? */
> +	remap_range((void *)CYCLONE5_OCRAM_ADDRESS, PAGE_SIZE, MAP_CODE);

This is done before the code is copied to this page. I moved it after
the fncpy call to avoid writing to readonly memory.

While at it I also added the remapping to MAP_UNCACHED.

Sascha

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