On 12.05.23 13:09, Sascha Hauer wrote:
> The i.MX HAB code on i.MX6 has to jump into ROM which happens to start
> at 0x0. To make that possible we used to map the ROM cached and jumped
> to it before the MMU is initialized. Instead, remap the ROM as needed
> in the HAB code so that we can safely jump into ROM with MMU enabled.
>
> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> ---
> arch/arm/cpu/mmu-early_32.c | 7 -------
> drivers/hab/habv4.c | 9 ++++++++-
> 2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm/cpu/mmu-early_32.c b/arch/arm/cpu/mmu-early_32.c
> index 07c5917e6a..94bde44c9b 100644
> --- a/arch/arm/cpu/mmu-early_32.c
> +++ b/arch/arm/cpu/mmu-early_32.c
> @@ -58,12 +58,5 @@ void mmu_early_enable(unsigned long membase, unsigned long memsize,
> /* maps main memory as cachable */
> map_region(membase, memsize, PMD_SECT_DEF_CACHED);
>
> - /*
> - * With HAB enabled we call into the ROM code later in imx6_hab_get_status().
> - * Map the ROM cached which has the effect that the XN bit is not set.
> - */
> - if (IS_ENABLED(CONFIG_HABV4) && IS_ENABLED(CONFIG_ARCH_IMX6))
> - map_region(0x0, SZ_1M, PMD_SECT_DEF_CACHED);
> -
> __mmu_cache_on();
> }
> diff --git a/drivers/hab/habv4.c b/drivers/hab/habv4.c
> index 252e38f655..d2494db114 100644
> --- a/drivers/hab/habv4.c
> +++ b/drivers/hab/habv4.c
> @@ -11,6 +11,9 @@
> #include <hab.h>
> #include <init.h>
> #include <types.h>
> +#include <mmu.h>
> +#include <zero_page.h>
> +#include <linux/sizes.h>
> #include <linux/arm-smccc.h>
> #include <asm/cache.h>
>
> @@ -613,12 +616,16 @@ static int init_imx6_hab_get_status(void)
> /* can happen in multi-image builds and is not an error */
> return 0;
>
> + arch_remap_range(0x0, SZ_1M, MAP_CACHED);
This affects SZ_1M bytes.
> +
> /*
> * Nobody will check the return value if there were HAB errors, but the
> * initcall will fail spectaculously with a strange error message.
> */
> imx6_hab_get_status();
>
> + zero_page_faulting();
This affects only 4K. The rest of the 1M can now be speculated into :/
> +
> return 0;
> }
>
> @@ -627,7 +634,7 @@ static int init_imx6_hab_get_status(void)
> * which will no longer be accessible when the MMU sets the zero page to
> * faulting.
> */
> -postconsole_initcall(init_imx6_hab_get_status);
> +postmmu_initcall(init_imx6_hab_get_status);
>
> int imx28_hab_get_status(void)
> {
--
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