Messages in this thread | | | Subject | Re: [PATCH 2/5] powerpc/mm: split store_updates_sp() in two parts in do_page_fault() | From | Christophe LEROY <> | Date | Fri, 2 Jun 2017 14:31:47 +0200 |
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Le 02/06/2017 à 14:11, Benjamin Herrenschmidt a écrit : > On Fri, 2017-06-02 at 11:39 +0200, Christophe LEROY wrote: >> The difference between get_user() and __get_user() is that get_user() >> performs an access_ok() in addition. >> >> Doesn't access_ok() only checks whether addr is below TASK_SIZE to >> ensure it is a valid user address ? > > Do you have a measurable improvement by skipping that check ? I agree > with your reasoning but I'm also paranoid and so I wouldn't change it > unless it's really worth it. >
No I don't have. Taking into account the patch following this serie which limits even more the calls to get_user(), it is probably not worth it anymore (see https://patchwork.ozlabs.org/patch/757564/)
I will then have to resubmit the entire serie (including that additional one), but there is no get_user_inatomic() so will have to either: - do the access_ok() verification inside the function - get back to v2 (https://patchwork.ozlabs.org/patch/756234/) - implement an get_user_inatomic() function
What would be the best ?
Christophe
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