Re: [PATCH 1/2] xen/arm: Simplify SMCCC handling by reusing __declare_arg_$()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/02/2026 2:14 pm, Orzel, Michal wrote:
>
> On 24/02/2026 13:45, Andrew Cooper wrote:
>> Now that the type handling is entirely uniform, it's easier to see that
>> __declare_arg_3() can use __declare_arg_2() and so on, just like the larger
>> __declare_arg_$()'s already do.
>>
>> No functional change.
> This patch won't build.
>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>> ---
>> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> CC: Julien Grall <julien@xxxxxxx>
>> CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
>> CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
>> CC: Michal Orzel <michal.orzel@xxxxxxx>
>> ---
>>  xen/arch/arm/include/asm/smccc.h | 15 +++------------
>>  1 file changed, 3 insertions(+), 12 deletions(-)
>>
>> diff --git a/xen/arch/arm/include/asm/smccc.h 
>> b/xen/arch/arm/include/asm/smccc.h
>> index 5b30dd57b69d..347c4526d12a 100644
>> --- a/xen/arch/arm/include/asm/smccc.h
>> +++ b/xen/arch/arm/include/asm/smccc.h
>> @@ -114,26 +114,17 @@ struct arm_smccc_res {
>>  
>>  #define __declare_arg_1(a0, a1, res)                        \
>>      typeof(a1) __a1 = (a1);                                 \
>> -    struct arm_smccc_res    *___res = (res);                \
>> -    register unsigned long  arg0 ASM_REG(0) = (uint32_t)(a0);\
>> +    __declare_arg_0(a0, res);                               \
>>      register typeof(a1)     arg1 ASM_REG(1) = __a1
>>  
>>  #define __declare_arg_2(a0, a1, a2, res)                    \
>>      typeof(a1) __a1 = (a1);                                 \
> You should remove this line and ...
>
>> -    typeof(a2) __a2 = (a2);                                 \
> keep this line.
>
>> -    struct arm_smccc_res    *___res = (res);                \
>> -    register unsigned long  arg0 ASM_REG(0) = (uint32_t)(a0);\
>> -    register typeof(a1)     arg1 ASM_REG(1) = __a1;         \
>> +    __declare_arg_1(a0, a1, res);                           \
>>      register typeof(a2)     arg2 ASM_REG(2) = __a2
>>  
>>  #define __declare_arg_3(a0, a1, a2, a3, res)                \
>>      typeof(a1) __a1 = (a1);                                 \
>> -    typeof(a2) __a2 = (a2);                                 \
> Same here.

Hmm - it built for me.  I'd better figure out why I missed it first.

With the second patch, these disappear, which is why _that_ builds.

>
>> -    typeof(a3) __a3 = (a3);                                 \
>> -    struct arm_smccc_res    *___res = (res);                \
>> -    register unsigned long  arg0 ASM_REG(0) = (uint32_t)(a0);\
>> -    register typeof(a1)     arg1 ASM_REG(1) = __a1;         \
>> -    register typeof(a2)     arg2 ASM_REG(2) = __a2;         \
>> +    __declare_arg_2(a0, a1, a2, res);                       \
>>      register typeof(a3)     arg3 ASM_REG(3) = __a3
>>  
>>  #define __declare_arg_4(a0, a1, a2, a3, a4, res)        \
> In principal, with the remarks addressed:
> Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>

Thanks.

~Andrew