Messages in this thread | | | From | Linus Torvalds <> | Date | Sun, 13 Oct 2019 13:20:33 -0700 | Subject | Re: [PATCH] Convert filldir[64]() from __put_user() to unsafe_put_user() |
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On Sun, Oct 13, 2019 at 12:59 PM Al Viro <viro@zeniv.linux.org.uk> wrote: > > Re plotting: how strongly would you object against passing the range to > user_access_end()? Powerpc folks have a very close analogue of stac/clac, > currently buried inside their __get_user()/__put_user()/etc. - the same > places where x86 does, including futex.h and friends. > > And there it's even costlier than on x86. It would obviously be nice > to lift it at least out of unsafe_get_user()/unsafe_put_user() and > move into user_access_begin()/user_access_end(); unfortunately, in > one subarchitecture they really want it the range on the user_access_end() > side as well.
Hmm. I'm ok with that.
Do they want the actual range, or would it prefer some kind of opaque cookie that user_access_begin() returns (where 0 would mean "failure" of course)?
I'm thinking like a local_irq_save/restore thing, which might be the case on yet other architectures.
Linus
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