[PATCH v7 09/14] riscv: misaligned: move emulated access uniformity check in a function

[Clément Léger]

On 20/05/2025 19:08, Charlie Jenkins wrote:
> On Tue, May 20, 2025 at 10:19:47AM +0200, Clément Léger wrote:
>>
>>
>> On 20/05/2025 01:32, Charlie Jenkins wrote:
>>> On Thu, May 15, 2025 at 10:22:10AM +0200, Clément Léger wrote:
>>>> Split the code that check for the uniformity of misaligned accesses
>>>> performance on all cpus from check_unaligned_access_emulated_all_cpus()
>>>> to its own function which will be used for delegation check. No
>>>> functional changes intended.
>>>>
>>>> Signed-off-by: Clément Léger <cleger at rivosinc.com>
>>>> Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
>>>> ---
>>>>  arch/riscv/kernel/traps_misaligned.c | 20 ++++++++++++++------
>>>>  1 file changed, 14 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c
>>>> index e551ba17f557..287ec37021c8 100644
>>>> --- a/arch/riscv/kernel/traps_misaligned.c
>>>> +++ b/arch/riscv/kernel/traps_misaligned.c
>>>> @@ -647,6 +647,18 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void)
>>>>  }
>>>>  #endif
>>>>  
>>>> +static bool all_cpus_unaligned_scalar_access_emulated(void)
>>>> +{
>>>> +	int cpu;
>>>> +
>>>> +	for_each_online_cpu(cpu)
>>>> +		if (per_cpu(misaligned_access_speed, cpu) !=
>>>
>>> misaligned_access_speed is only defined when
>>> CONFIG_RISCV_SCALAR_MISALIGNED. This function should return false when
>>> !CONFIG_RISCV_SCALAR_MISALIGNED and only use this logic otherwise.
>>
>> Hi Charlie,
>>
>> misaligned_access_speed is defined in unaligned_access_speed.c which is
>> compiled based on CONFIG_RISCV_MISALIGNED (ditto for trap_misaligned.c)
>>
>> obj-$(CONFIG_RISCV_MISALIGNED)	+= unaligned_access_speed.o
>>
>> However, the declaration for it in the header cpu-feature.h however is
>> under a CONFIG_RISCV_SCALAR_MISALIGNED ifdef. So either the declaration
>> or the definition is wrong but the ifdefery soup makes it quite
>> difficult to understand what's going on.
>>
>> I would suggest to move the DECLARE_PER_CPU under
>> CONFIG_RISCV_MISALIGNED so that it reduces ifdef in traps_misaligned as
>> well.
> 
> Here is the patch I am using locally for testing purposes, but if there
> is a way to reduce the number of ifdefs that is probably the better way to go:
> 

Hi Charlie,

I have another way to do so which indeed reduces the number of
ifdef/duplicated functions. I'll submit that.

Thanks,

Clément

> From 18f9a056d3b597934c931abdf72fb6e775ccb714 Mon Sep 17 00:00:00 2001
> From: Charlie Jenkins <charlie at rivosinc.com>
> Date: Mon, 19 May 2025 16:35:51 -0700
> Subject: [PATCH] fixup! riscv: misaligned: move emulated access uniformity
>  check in a function
> 
> ---
>  arch/riscv/kernel/traps_misaligned.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c
> index f3ab84bc4632..1449c6a4ac21 100644
> --- a/arch/riscv/kernel/traps_misaligned.c
> +++ b/arch/riscv/kernel/traps_misaligned.c
> @@ -647,6 +647,10 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void)
>  }
>  #endif
>  
> +#ifdef CONFIG_RISCV_SCALAR_MISALIGNED
> +
> +static bool unaligned_ctl __read_mostly;
> +
>  static bool all_cpus_unaligned_scalar_access_emulated(void)
>  {
>  	int cpu;
> @@ -659,10 +663,6 @@ static bool all_cpus_unaligned_scalar_access_emulated(void)
>  	return true;
>  }
>  
> -#ifdef CONFIG_RISCV_SCALAR_MISALIGNED
> -
> -static bool unaligned_ctl __read_mostly;
> -
>  static void check_unaligned_access_emulated(void *arg __always_unused)
>  {
>  	int cpu = smp_processor_id();
> @@ -716,6 +716,10 @@ bool unaligned_ctl_available(void)
>  	return unaligned_ctl;
>  }
>  #else
> +static bool all_cpus_unaligned_scalar_access_emulated(void)
> +{
> +	return false;
> +}
>  bool __init check_unaligned_access_emulated_all_cpus(void)
>  {
>  	return false;