[PATCH v3 10/13] drivers/firmware/scmi: disable ftrace for Clang Thumb2 builds

[Sudeep Holla]

On Thu, Feb 03, 2022 at 09:22:01AM +0100, Ard Biesheuvel wrote:
> The SMC calling convention designates R0-R7 as input registers in
> AArch32 mode, and this conflicts with the compiler's use of R7 as a
> frame pointer when building in Thumb2 mode. Generally, we don't enable
> the frame pointer, and GCC happily enables the -pg profiling hooks
> without them. However, Clang refuses, and errors out with the message
> below:
>
> drivers/firmware/arm_scmi/smc.c:152:2: error: write to reserved register 'R7'
>         arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
>         ^
> include/linux/arm-smccc.h:550:4: note: expanded from macro 'arm_smccc_1_1_invoke'
>                         arm_smccc_1_1_smc(__VA_ARGS__);                 \
>                         ^
> Let's just disable ftrace for the compilation unit when building this
> configuration.
>
> [...]

Applied to sudeep.holla/linux (for-next/scmi), thanks!

[10/13] drivers/firmware/scmi: disable ftrace for Clang Thumb2 builds
        https://git.kernel.org/sudeep.holla/linux/c/cdf157faaa

--
Regards,
Sudeep