Messages in this thread | | | From | Andy Lutomirski <> | Date | Wed, 21 Nov 2018 14:38:17 -0800 | Subject | Re: [PATCH] x86: only use ERMS for user copies for larger sizes |
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On Wed, Nov 21, 2018 at 10:44 AM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Wed, Nov 21, 2018 at 10:26 AM Andy Lutomirski <luto@amacapital.net> wrote: > > > > Can we maybe use this as an excuse to ask for some reasonable instructions to access user memory? > > I did that long ago. It's why we have CLAC/STAC today. I was told that > what I actually asked for (get an instruction to access user space - I > suggested using a segment override prefix) was not viable. >
Maybe it wasn't viable *then*, but WRUSS really does write to userspace with user privilege. Surely the same mechanism with some of the weirdness removed would do what we want.
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