linux-kernel - Re: [PATCH RESEND v3 6/6] powerpc/signal: Use unsafe_copy_siginfo_to

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Date:   Mon, 13 Sep 2021 19:14:55 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, hch@...radead.org,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH RESEND v3 6/6] powerpc/signal: Use
 unsafe_copy_siginfo_to_user()



Le 13/09/2021 à 17:57, Eric W. Biederman a écrit :
> Christophe Leroy <christophe.leroy@...roup.eu> writes:
> 
>> Use unsafe_copy_siginfo_to_user() in order to do the copy
>> within the user access block.
>>
>> On an mpc 8321 (book3s/32) the improvment is about 5% on a process
>> sending a signal to itself.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
>> ---
>> v3: Don't leave compat aside, use the new unsafe_copy_siginfo_to_user32()
>> ---
>>   arch/powerpc/kernel/signal_32.c | 8 +++-----
>>   arch/powerpc/kernel/signal_64.c | 5 +----
>>   2 files changed, 4 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
>> index ff101e2b3bab..3a2db8af2d65 100644
>> --- a/arch/powerpc/kernel/signal_32.c
>> +++ b/arch/powerpc/kernel/signal_32.c
>> @@ -710,9 +710,9 @@ static long restore_tm_user_regs(struct pt_regs *regs, struct mcontext __user *s
>>   }
>>   #endif
>>   
>> -#ifdef CONFIG_PPC64
>> +#ifndef CONFIG_PPC64
>>   
>> -#define copy_siginfo_to_user	copy_siginfo_to_user32
>> +#define unsafe_copy_siginfo_to_user32	unsafe_copy_siginfo_to_user
>>   
>>   #endif /* CONFIG_PPC64 */
> 
> Any particular reason to reverse the sense of this #ifdef?

Yes I had double definition of unsafe_copy_siginfo_to_user(), I could 
have ifdefed out unsafe_copy_siginfo_to_user() in signal.h, but I 
prefered to ifdef out copy_siginfo_to_user32() in compat.h

> 
> Otherwise this change looks much cleaner.

Thanks
Christophe