Re: [PATCH v2 3/3] arm/mpu: Provide access to the MPU region from the C code

[Luca Fancellu <Luca.Fancellu@xxxxxxx>]

Hi Ayan,

If I understand correctly Armv8-R AArch32 supports up to 255 regions, so I 
would expect ...

> /*
>  * Armv8-R supports direct access and indirect access to the MPU regions 
> through
>  * registers:
> @@ -85,6 +87,7 @@ static void __init __maybe_unused build_assertions(void)
>  */
> static void prepare_selector(uint8_t *sel)
> {
> +#ifdef CONFIG_ARM_64
>     uint8_t cur_sel = *sel;
> 
>     /*
> @@ -98,7 +101,8 @@ static void prepare_selector(uint8_t *sel)
>         WRITE_SYSREG(cur_sel, PRSELR_EL2);
>         isb();
>     }
> -    *sel &= 0xFU;
> +    *sel = *sel & 0xFU;
> +#endif

something here to check if the selector is 0-31 or not and:

- set the selector to 0 if set is 0-31
- set the selector to 32-255 if sel > 32

And ...


> }
> 
> void read_protection_region(pr_t *pr_read, uint8_t sel)
> @@ -123,6 +127,24 @@ void read_protection_region(pr_t *pr_read, uint8_t sel)
>         GENERATE_READ_PR_REG_CASE(13, pr_read);
>         GENERATE_READ_PR_REG_CASE(14, pr_read);
>         GENERATE_READ_PR_REG_CASE(15, pr_read);
> +#ifdef CONFIG_ARM_32
> +        GENERATE_READ_PR_REG_CASE(16, pr_read);
> +        GENERATE_READ_PR_REG_CASE(17, pr_read);
> +        GENERATE_READ_PR_REG_CASE(18, pr_read);
> +        GENERATE_READ_PR_REG_CASE(19, pr_read);
> +        GENERATE_READ_PR_REG_CASE(20, pr_read);
> +        GENERATE_READ_PR_REG_CASE(21, pr_read);
> +        GENERATE_READ_PR_REG_CASE(22, pr_read);
> +        GENERATE_READ_PR_REG_CASE(23, pr_read);
> +        GENERATE_READ_PR_REG_CASE(24, pr_read);
> +        GENERATE_READ_PR_REG_CASE(25, pr_read);
> +        GENERATE_READ_PR_REG_CASE(26, pr_read);
> +        GENERATE_READ_PR_REG_CASE(27, pr_read);
> +        GENERATE_READ_PR_REG_CASE(28, pr_read);
> +        GENERATE_READ_PR_REG_CASE(29, pr_read);
> +        GENERATE_READ_PR_REG_CASE(30, pr_read);
> +        GENERATE_READ_PR_REG_CASE(31, pr_read);
> +#endif
>     default:

have something here for Arm32 to access the regions 32-255


>         BUG(); /* Can't happen */
>         break;
> @@ -151,6 +173,24 @@ void write_protection_region(const pr_t *pr_write, 
> uint8_t sel)
>         GENERATE_WRITE_PR_REG_CASE(13, pr_write);
>         GENERATE_WRITE_PR_REG_CASE(14, pr_write);
>         GENERATE_WRITE_PR_REG_CASE(15, pr_write);
> +#ifdef CONFIG_ARM_32
> +        GENERATE_WRITE_PR_REG_CASE(16, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(17, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(18, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(19, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(20, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(21, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(22, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(23, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(24, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(25, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(26, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(27, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(28, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(29, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(30, pr_write);
> +        GENERATE_WRITE_PR_REG_CASE(31, pr_write);
> +#endif
>     default:

also here have something for Arm32 to access the regions 32-255

>         BUG(); /* Can't happen */
>         break;


Please let me know your thoughts.

Cheers,
Luca