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

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

[Ahmad Fatoum]

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);
 
 	dev_dbg(&mgr->dev, "Setting APPLYCFG bit...\n");
 
diff --git a/drivers/hab/habv4.c b/drivers/hab/habv4.c
index 4945e8930acb..83ee06a6aa46 100644
--- a/drivers/hab/habv4.c
+++ b/drivers/hab/habv4.c
@@ -689,7 +689,7 @@ int imx8m_hab_print_status(void)
 
 int imx6_hab_print_status(void)
 {
-	remap_range(0x0, SZ_1M, MAP_CACHED);
+	remap_range(0x0, SZ_1M, MAP_CODE);
 
 	imx6_hab_get_status();
 
diff --git a/include/mmu.h b/include/mmu.h
index 84ec6c5efb3e..669959050194 100644
--- a/include/mmu.h
+++ b/include/mmu.h
@@ -8,6 +8,7 @@
 #define MAP_UNCACHED	0
 #define MAP_CACHED	1
 #define MAP_FAULT	2
+#define MAP_CODE	MAP_CACHED	/* until support added */
 
 /*
  * Depending on the architecture the default mapping can be
-- 
2.39.5

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

[Sascha Hauer]

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

-- 
Pengutronix e.K.                           |                             |
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Re: [PATCH] mmu: explicitly map executable non-SDRAM regions with MAP_CODE

[Sascha Hauer]

On Wed, 18 Jun 2025 14:36:42 +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.
> 
> [...]

Applied, thanks!

[1/1] mmu: explicitly map executable non-SDRAM regions with MAP_CODE
      https://git.pengutronix.de/cgit/barebox/commit/?id=225fda833a82 (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>

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

[Ahmad Fatoum]

On 20.06.25 14:45, Sascha Hauer wrote:
> 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.

fncpy calls memcpy internally though, so we should either leave the MAP_CACHED
as is and add a further MAP_CODE after the fncpy or introduce a fncpy_toio
that calls memcpy_toio internally.

What do you think?

> While at it I also added the remapping to MAP_UNCACHED.

Thanks,
Ahmad

> 
> Sascha
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |