Messages in this thread | | | Subject | Re: [PATCH RESEND v3 6/6] powerpc/signal: Use unsafe_copy_siginfo_to_user() | From | Christophe Leroy <> | Date | Mon, 13 Sep 2021 19:19:26 +0200 |
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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
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