Re: [Xen-devel] [RFC 3/7] arm64:armds: ARM Compiler 6.6 does not accept `rx` registers naming for AArch64

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.11.2019 10:19, Andrii Anisov wrote:
> --- a/xen/include/asm-arm/smccc.h
> +++ b/xen/include/asm-arm/smccc.h
> @@ -120,6 +120,8 @@ struct arm_smccc_res {
>  #define __constraint_read_6 __constraint_read_5, "r" (r6)
>  #define __constraint_read_7 __constraint_read_6, "r" (r7)
>  
> +#ifdef CONFIG_ARM_32
> +
>  #define __declare_arg_0(a0, res)                        \
>      struct arm_smccc_res    *___res = res;              \
>      register unsigned long  r0 asm("r0") = (uint32_t)a0;\
> @@ -174,6 +176,64 @@ struct arm_smccc_res {
>      __declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res);           \
>      register typeof(a7) r7 asm("r7") = __a7
>  
> +#else /* ARM_64 */
> +
> +#define __declare_arg_0(a0, res)                        \
> +    struct arm_smccc_res    *___res = res;              \
> +    register unsigned long  r0 asm("x0") = (uint32_t)a0;\
> +    register unsigned long  r1 asm("x1");               \
> +    register unsigned long  r2 asm("x2");               \
> +    register unsigned long  r3 asm("x3")
> +
> +#define __declare_arg_1(a0, a1, res)                    \
> +    typeof(a1) __a1 = a1;                               \
> +    struct arm_smccc_res    *___res = res;              \
> +    register unsigned long  r0 asm("x0") = (uint32_t)a0;\
> +    register unsigned long  r1 asm("x1") = __a1;        \
> +    register unsigned long  r2 asm("x2");               \
> +    register unsigned long  r3 asm("x3")
> +
> +#define __declare_arg_2(a0, a1, a2, res)                \
> +    typeof(a1) __a1 = a1;                               \
> +    typeof(a2) __a2 = a2;                               \
> +    struct arm_smccc_res    *___res = res;                              \
> +    register unsigned long  r0 asm("x0") = (uint32_t)a0;\
> +    register unsigned long  r1 asm("x1") = __a1;        \
> +    register unsigned long  r2 asm("x2") = __a2;        \
> +    register unsigned long  r3 asm("x3")
> +
> +#define __declare_arg_3(a0, a1, a2, a3, res)            \
> +    typeof(a1) __a1 = a1;                               \
> +    typeof(a2) __a2 = a2;                               \
> +    typeof(a3) __a3 = a3;                               \
> +    struct arm_smccc_res    *___res = res;              \
> +    register unsigned long  r0 asm("x0") = (uint32_t)a0;\
> +    register unsigned long  r1 asm("x1") = __a1;        \
> +    register unsigned long  r2 asm("x2") = __a2;        \
> +    register unsigned long  r3 asm("x3") = __a3
> +
> +#define __declare_arg_4(a0, a1, a2, a3, a4, res)        \
> +    typeof(a4) __a4 = a4;                               \
> +    __declare_arg_3(a0, a1, a2, a3, res);               \
> +    register unsigned long r4 asm("x4") = __a4
> +
> +#define __declare_arg_5(a0, a1, a2, a3, a4, a5, res)    \
> +    typeof(a5) __a5 = a5;                               \
> +    __declare_arg_4(a0, a1, a2, a3, a4, res);           \
> +    register typeof(a5) r5 asm("x5") = __a5
> +
> +#define __declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res)    \
> +    typeof(a6) __a6 = a6;                                   \
> +    __declare_arg_5(a0, a1, a2, a3, a4, a5, res);           \
> +    register typeof(a6) r6 asm("x6") = __a6
> +
> +#define __declare_arg_7(a0, a1, a2, a3, a4, a5, a6, a7, res)    \
> +    typeof(a7) __a7 = a7;                                       \
> +    __declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res);           \
> +    register typeof(a7) r7 asm("x7") = __a7
> +
> +#endif

I'm not an Arm maintainer, so my opinion may not mean much, but
this is way too much code duplication for my taste. Isn't all you
need an abstraction of the "r0" etc vs "x0" etc strings? Or even
better, can't use to the "x0" etc form with the other compilers
(seeing that these are their architectural names when taking the
full with registers)?

Jan

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