Re: [linux-next:master 8264/14724] drivers/firmware/smccc/smccc.c:141:1: error: r7 cannot be used in asm here

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Oct 07, 2026 at 02:18:08PM +0530, Aneesh Kumar K.V wrote:
> @@ -640,6 +640,39 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
>  			*___res = (typeof(*___res)){r0, r1, r2, r3};	\
>  	} while (0)
>  
> +#if defined(CONFIG_ARM) && defined(CONFIG_THUMB2_KERNEL)
> +/*
> + * GCC may reserve r7 in Thumb-2 functions. Calls with eight inputs must
> + * therefore use the assembly helpers, which save and restore r7 themselves.
> + */
> +#define __arm_smccc_1_1_out_of_line(fn, inst, a0, a1, a2, a3, a4, a5, a6, a7, res) \
> +	do {\
> +		struct arm_smccc_res __res;\
> +		struct arm_smccc_res *__res_ptr = (res);\
> +\
> +		fn((u32)(a0), a1, a2, a3, a4, a5, a6, a7,\
> +		   __res_ptr ? __res_ptr : &__res);\
> +	} while (0)
> +
> +#define __arm_smccc_1_1_inline(fn, inst, ...) \
> +	__arm_smccc_1_1(inst, __VA_ARGS__)
> +
> +#define __arm_smccc_1_1_call_2 __arm_smccc_1_1_inline
> +#define __arm_smccc_1_1_call_3 __arm_smccc_1_1_inline
> +#define __arm_smccc_1_1_call_4 __arm_smccc_1_1_inline
> +#define __arm_smccc_1_1_call_5 __arm_smccc_1_1_inline
> +#define __arm_smccc_1_1_call_6 __arm_smccc_1_1_inline
> +#define __arm_smccc_1_1_call_7 __arm_smccc_1_1_inline
> +#define __arm_smccc_1_1_call_8 __arm_smccc_1_1_inline
> +#define __arm_smccc_1_1_call_9 __arm_smccc_1_1_out_of_line
> +
> +#define __arm_smccc_1_1_call(fn, inst, ...) \
> +	CONCATENATE(__arm_smccc_1_1_call_, COUNT_ARGS(__VA_ARGS__))(fn, inst, __VA_ARGS__)
> +#else
> +#define __arm_smccc_1_1_call(fn, inst, ...) \
> +	__arm_smccc_1_1(inst, __VA_ARGS__)
> +#endif

I wonder if this could just be something simpler like

#define __arm_smccc_1_1_call(fn, inst, ...)                       \
	({                                                        \
		if (COUNT_ARGS(__VA_ARGS__) >= 7 &&               \
		    IS_ENABLED(CONFIG_THUMB2_KERNEL))             \
			__arm_smccc_1_1_call_(inst, __VA_ARGS__); \
		else                                              \
			__arm_smccc_1_1(inst, __VA_ARGS__);       \
	})

? (still needs to take care of the NULL res)

Jason