lkml.org 
[lkml]   [2019]   [Oct]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] Convert filldir[64]() from __put_user() to unsafe_put_user()
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

\
 
 \ /
  Last update: 2019-10-08 06:24    [W:0.110 / U:1.816 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site