Re: [PATCH 11/14] ARM: i.MX: tqma6ulx: fix barebox chainloading with OP-TEE enabled

[Marco Felsch <m.felsch@pengutronix.de>]

On 25-06-27, Sascha Hauer wrote:
> When barebox starts we have to guess if we have to start OP-TEE or not.
> The current detection works by checking if the first stage passed us a
> device tree pointer. This is not robust and might have security issues
> [1], so replace that with the check with imx6_can_access_tzasc(). If we
> can access the TZASC then we are the first stage and configure it and
> start OP-TEE, otherwise assume that we are chainloaded and continue
> without starting OP-TEE.
> 
> Chainloading barebox with OP-TEE enabled contained several bugs, so it
> never actually worked. This patch fixes them.
> 
> [1] https://lore.kernel.org/70b41f3b-4329-48f7-827f-1924e002ab04@pengutronix.de
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>

> ---
>  arch/arm/boards/tqma6ulx/lowlevel.c | 22 +++++++++-------------
>  arch/arm/mach-imx/Kconfig           |  1 +
>  2 files changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm/boards/tqma6ulx/lowlevel.c b/arch/arm/boards/tqma6ulx/lowlevel.c
> index 5fd997d2ec7e79c7319237a4ae52216e584ba5cd..da67e67537167096477de2b905ee5c42c653c3af 100644
> --- a/arch/arm/boards/tqma6ulx/lowlevel.c
> +++ b/arch/arm/boards/tqma6ulx/lowlevel.c
> @@ -16,6 +16,8 @@
>  #include <pbl/i2c.h>
>  #include <boards/tq/tq_eeprom.h>
>  #include <tee/optee.h>
> +#include <mach/imx/tzasc.h>
> +#include <tee/optee.h>
>  
>  #include "tqma6ulx.h"
>  
> @@ -66,7 +68,7 @@ static void *read_eeprom(void)
>  	return fdt;
>  }
>  
> -static void noinline start_mba6ulx(u32 r0)
> +static void noinline start_mba6ulx(void)
>  {
>  	void *fdt;
>  	int tee_size;
> @@ -76,21 +78,15 @@ static void noinline start_mba6ulx(u32 r0)
>  
>  	fdt = read_eeprom();
>  
> -	/* Enable normal/secure r/w for TZC380 region0 */
> -	writel(0xf0000000, 0x021D0108);
> -
>  	/*
> -	 * Chainloading barebox will pass a device tree within the RAM in r0,
> -	 * skip OP-TEE early loading in this case
> +	 * Skip loading barebox when we are chainloaded. We can detect that by detecting
> +	 * if we can access the TZASC.
>  	 */
> -	if (IS_ENABLED(CONFIG_FIRMWARE_TQMA6UL_OPTEE) &&
> -	    !(r0 > MX6_MMDC_P0_BASE_ADDR &&
> -	      r0 < MX6_MMDC_P0_BASE_ADDR + SZ_256M)) {
> -		get_builtin_firmware(mba6ul_optee_bin, &tee, &tee_size);
> +	if (IS_ENABLED(CONFIG_FIRMWARE_TQMA6UL_OPTEE) && imx6_can_access_tzasc()) {
>  
> -		memset((void *)OPTEE_OVERLAY_LOCATION, 0, 0x1000);
> +		get_builtin_firmware(mba6ul_optee_bin, &tee, &tee_size);
>  
> -		start_optee_early(NULL, tee);
> +		imx6ul_start_optee_early(NULL, tee, (void *)OPTEE_OVERLAY_LOCATION, 0x1000);
>  	}
>  
>  	imx6ul_barebox_entry(fdt);
> @@ -112,5 +108,5 @@ ENTRY_FUNCTION(start_imx6ul_mba6ulx, r0, r1, r2)
>  	setup_c();
>  	barrier();
>  
> -	start_mba6ulx(r0);
> +	start_mba6ulx();
>  }
> diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
> index 552e7227a0221fee8232dfba5dcdd60de923ff0c..1bf28b473af2b517a784c11d33f745ad74750583 100644
> --- a/arch/arm/mach-imx/Kconfig
> +++ b/arch/arm/mach-imx/Kconfig
> @@ -490,6 +490,7 @@ config MACH_TQMA6X
>  
>  config MACH_TQMA6UL
>  	bool "TQ tqma6ul on mba6ulx"
> +	select CONFIG_ARM_EXCEPTIONS_PBL if FIRMWARE_TQMA6UL_OPTEE
>  	select ARCH_IMX6UL
>  	select BOARD_TQ
>  	select I2C_IMX_EARLY
> 
> -- 
> 2.39.5
> 
> 
>