From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
hch@infradead.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH RESEND v3 6/6] powerpc/signal: Use unsafe_copy_siginfo_to_user()
Date: Mon, 13 Sep 2021 19:19:26 +0200 [thread overview]
Message-ID: <96d06ad9-5a9b-b8c3-3c1d-ed8837091a60@csgroup.eu> (raw)
In-Reply-To: <87y280o38q.fsf@disp2133>
Le 13/09/2021 à 18:21, Eric W. Biederman a écrit :
> ebiederm@xmission.com (Eric W. Biederman) writes:
>
>> Christophe Leroy <christophe.leroy@csgroup.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.
>
> If you can't make function calls from an unsafe macro there is another
> way to handle this that doesn't require everything to be inline.
>
> From a safety perspective it is probably even a better approach.
Yes but that's exactly what I wanted to avoid for the native ppc32 case:
this double hop means useless pressure on the cache. The siginfo_t
structure is 128 bytes large, that means 8 lines of cache on powerpc 8xx.
But maybe it is acceptable to do that only for the compat case. Let me
think about it, it might be quite easy.
Christophe
next prev parent reply other threads:[~2021-09-13 17:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 15:19 [PATCH RESEND v3 1/6] powerpc/signal64: Access function descriptor with user access block Christophe Leroy
2021-09-13 15:19 ` [PATCH RESEND v3 2/6] powerpc/signal: Include the new stack frame inside the " Christophe Leroy
2021-09-13 15:19 ` [PATCH RESEND v3 3/6] signal: Add unsafe_copy_siginfo_to_user() Christophe Leroy
2021-09-13 15:19 ` [PATCH RESEND v3 4/6] signal: Add unsafe_copy_siginfo_to_user32() Christophe Leroy
2021-09-13 15:54 ` Eric W. Biederman
2021-09-13 17:01 ` Christophe Leroy
2021-09-13 15:19 ` [PATCH RESEND v3 5/6] powerpc/uaccess: Add unsafe_clear_user() Christophe Leroy
2021-09-13 15:19 ` [PATCH RESEND v3 6/6] powerpc/signal: Use unsafe_copy_siginfo_to_user() Christophe Leroy
2021-09-13 15:57 ` Eric W. Biederman
2021-09-13 16:21 ` Eric W. Biederman
2021-09-13 17:19 ` Christophe Leroy [this message]
2021-09-13 19:11 ` Eric W. Biederman
2021-09-14 14:00 ` Christophe Leroy
2021-09-13 17:14 ` Christophe Leroy
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