[U-Boot] [PATCH v5 2/7] efi_loader: AArch64: Run EFI payloads in EL2 if U-Boot runs in EL3

[york sun]

On 10/15/2016 03:03 AM, Alexander Graf wrote:
> Some boards decided not to run ATF or other secure firmware in EL3, so
> they instead run U-Boot there. The uEFI spec doesn't know what EL3 is
> though - it only knows about EL2 and EL1. So if we see that we're running
> in EL3, let's get into EL2 to make payloads happy.
>
> Signed-off-by: Alexander Graf <agraf at suse.de>
>
> ---
>
> v4 -> v5:
>
>   - Remove manual ttbr / tcr copy
>   - Regenerate page tables in EL2, getting us non-secured page tables
> ---
>  cmd/bootefi.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
> index 8714666..32148d7 100644
> --- a/cmd/bootefi.c
> +++ b/cmd/bootefi.c
> @@ -224,6 +224,17 @@ static unsigned long do_bootefi_exec(void *efi, void *fdt)
>  		return status == EFI_SUCCESS ? 0 : -EINVAL;
>  	}
>
> +#ifdef CONFIG_ARM64
> +	/* On AArch64 we need to make sure we call our payload in < EL3 */
> +	if (current_el() == 3) {
> +		smp_kick_all_cpus();
> +		dcache_disable();	/* flush cache before switch to EL2 */
> +		armv8_switch_to_el2();
> +		/* Enable caches again */
> +		dcache_enable();
> +	}
> +#endif
> +
>  	return entry(&loaded_image_info, &systab);
>  }
>
>

Reviewed-by: York Sun <york.sun at nxp.com>