On Wed, Jun 07, 2023 at 10:23:45AM +0530, Kathiravan T wrote:
> During SCM probe, to identify the SCM convention, scm call is made with
> SMC_CONVENTION_ARM_64 followed by SMC_CONVENTION_ARM_32. Based on the
> result what convention to be used is decided.
>
> IPQ chipsets starting from IPQ807x, supports both 32bit and 64bit kernel
> variants, however TZ firmware runs in 64bit mode. When running on 32bit
> kernel, scm call is made with SMC_CONVENTION_ARM_64 is causing the
> system crash, due to the difference in the register sets between ARM and
> AARCH64, which is accessed by the TZ.
>
> To avoid this, use SMC_CONVENTION_ARM_64 only on ARM64 builds.
>
My memory of this is cloudy, but I feel the logic is complicated because
early 64-bit boards all used 32-bit TZ. So, I really would like Elliot's
input before picking this change.
Regards,
Bjorn
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 9a434cee773a ("firmware: qcom_scm: Dynamically support SMCCC and legacy conventions")
> Signed-off-by: Kathiravan T <quic_kathirav@xxxxxxxxxxx>
> ---
> Changes in V2:
> - Added the Fixes tag and cc'd stable mailing list
>
> drivers/firmware/qcom_scm.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index fde33acd46b7..db6754db48a0 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -171,6 +171,7 @@ static enum qcom_scm_convention __get_convention(void)
> if (likely(qcom_scm_convention != SMC_CONVENTION_UNKNOWN))
> return qcom_scm_convention;
>
> +#if IS_ENABLED(CONFIG_ARM64)
> /*
> * Device isn't required as there is only one argument - no device
> * needed to dma_map_single to secure world
> @@ -191,6 +192,7 @@ static enum qcom_scm_convention __get_convention(void)
> forced = true;
> goto found;
> }
> +#endif
>
> probed_convention = SMC_CONVENTION_ARM_32;
> ret = __scm_smc_call(NULL, &desc, probed_convention, &res, true);
> --
> 2.17.1
>
