Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 7 Oct 2019 21:24:17 -0700 | Subject | Re: [PATCH] Convert filldir[64]() from __put_user() to unsafe_put_user() |
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On Mon, Oct 7, 2019 at 9:09 PM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > Try the attached patch, and then count the number of "rorx" > instructions in the kernel. Hint: not many. On my personal config, > this triggers 15 times in the whole kernel build (not counting > modules).
.. and four of them are in perf_callchain_user(), and are due to those "__copy_from_user_nmi()" with either 4-byte or 8-byte copies.
It might as well just use __get_user() instead.
The point being that the silly code in the header files is just pointless. We shouldn't do it.
Linus
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