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@xxxxxxxxxxxx>
>> Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
>> ---
>> 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.
Thanks,
Clément
>
> - Charlie
>
>> + RISCV_HWPROBE_MISALIGNED_SCALAR_EMULATED)
>> + return false;
>> +
>> + return true;
>> +}
>> +
>> #ifdef CONFIG_RISCV_SCALAR_MISALIGNED
>>
>> static bool unaligned_ctl __read_mostly;
>> @@ -685,8 +697,6 @@ static int cpu_online_check_unaligned_access_emulated(unsigned int cpu)
>>
>> bool __init check_unaligned_access_emulated_all_cpus(void)
>> {
>> - int cpu;
>> -
>> /*
>> * We can only support PR_UNALIGN controls if all CPUs have misaligned
>> * accesses emulated since tasks requesting such control can run on any
>> @@ -694,10 +704,8 @@ bool __init check_unaligned_access_emulated_all_cpus(void)
>> */
>> on_each_cpu(check_unaligned_access_emulated, NULL, 1);
>>
>> - for_each_online_cpu(cpu)
>> - if (per_cpu(misaligned_access_speed, cpu)
>> - != RISCV_HWPROBE_MISALIGNED_SCALAR_EMULATED)
>> - return false;
>> + if (!all_cpus_unaligned_scalar_access_emulated())
>> + return false;
>>
>> unaligned_ctl = true;
>> return true;
>> --
>> 2.49.0
>>
>>
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