firmware: arm_scmi: Disable ftrace for Clang Thumb2 builds

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.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Nick Desaulniers <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>

0 files changed, 0 insertions, 0 deletions