Re: [PATCH v3 6/6] RISC-V: Do not use cpumask data structure for hartid bitmap

[Andreas Schwab]

On Jan 27 2022, Geert Uytterhoeven wrote:

> Hi Atish,
>
> On Thu, Jan 27, 2022 at 9:48 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>> On Thu, Jan 27, 2022 at 2:02 AM Atish Patra <atishp@xxxxxxxxxxxxxx> wrote:
>  > Ahh yes. hmask will be incorrect if the bootcpu(cpu 0) is a higher
>> > hartid and it is trying to do a remote tlb flush/IPI
>> > to lower the hartid. We should generate the hartid array before the loop.
>> >
>> > Can you try this diff ? It seems to work for me during multiple boot
>> > cycle on the unleashed.
>> >
>> > You can find the patch here as well
>> > https://github.com/atishp04/linux/commits/v5.17-rc1
>>
>> Thanks, that fixes the issue for me.
>>
>> > --- a/arch/riscv/kernel/sbi.c
>> > +++ b/arch/riscv/kernel/sbi.c
>
>> > @@ -345,13 +368,21 @@ static int __sbi_rfence_v02(int fid, const
>> > struct cpumask *cpu_mask,
>> >       unsigned long arg4, unsigned long arg5)
>> >  {
>> >   unsigned long hartid, cpuid, hmask = 0, hbase = 0;
>> > - int result;
>> > + int result, index = 0, max_index = 0;
>> > + unsigned long hartid_arr[NR_CPUS] = {0};
>>
>> That's up to 256 bytes on the stack. And more if the maximum
>> number of cores is increased.
>
> I.e. 4 KiB with the proposed increase to 256 CPUs, as mentioned in

And those 4K need to be cleared each time the function is called, even
if there is only a small number of cpus.

-- 
Andreas Schwab, schwab@xxxxxxxxxxxxxx
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