linux-kernel - Re: [PATCH v3 1/5] powerpc/interrupt: Rename and lightly change syscall_exit_prepare

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Date:   Thu, 17 Jun 2021 15:58:57 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Nicholas Piggin <npiggin@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 1/5] powerpc/interrupt: Rename and lightly change
 syscall_exit_prepare_main()



Le 17/06/2021 à 13:25, Nicholas Piggin a écrit :
> Excerpts from Christophe Leroy's message of June 15, 2021 6:33 pm:
>> Rename syscall_exit_prepare_main() into interrupt_exit_prepare_main()
>>
>> Make it static as it is not used anywhere else.
>>
>> Pass it the 'ret' so that it can 'or' it directly instead of
>> oring twice, once inside the function and once outside.
>>
>> And remove 'r3' parameter which is not used.
>>
>> Also fix a typo where CONFIG_PPC_BOOK3S should be CONFIG_PPC_BOOK3S_64.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
>> Reviewed-by: Nicholas Piggin <npiggin@...il.com>
>> ---
>> This series applies on top of Nic's series speeding up interrupt return on 64s
>>
>>   arch/powerpc/kernel/interrupt.c | 11 +++++------
>>   1 file changed, 5 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
>> index 74c995a42399..ba2d602d2da6 100644
>> --- a/arch/powerpc/kernel/interrupt.c
>> +++ b/arch/powerpc/kernel/interrupt.c
>> @@ -243,11 +243,10 @@ static notrace void booke_load_dbcr0(void)
>>   #endif
>>   }
>>   
>> -notrace unsigned long syscall_exit_prepare_main(unsigned long r3,
>> -						struct pt_regs *regs)
>> +static notrace unsigned long
>> +interrupt_exit_user_prepare_main(struct pt_regs *regs, unsigned long ret)
> 
> Hmm, I tried switching the order of the arguments thinking it would
> match caller and return registers better but didn't seem to help
> generated code. Yet I think I will make that change to your patch if
> you don't mind.

That's a static function that most likely gets inlined so the order of parameters makes no difference.
I tend to like that almost all functions dealing with interrupts take regs as first param, but I 
have no strong opinion about it so you can change it if that's better for you.

Christophe