Messages in this thread | | | From | Linus Torvalds <> | Date | Thu, 22 Nov 2018 08:55:50 -0800 | Subject | Re: [PATCH] x86: only use ERMS for user copies for larger sizes |
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On Thu, Nov 22, 2018 at 2:32 AM Ingo Molnar <mingo@kernel.org> wrote: > * Linus Torvalds <torvalds@linux-foundation.org> wrote: > > > > Random patch (with my "asm goto" hack included) attached, in case > > people want to play with it. > > Doesn't even look all that hacky to me. Any hack in it that I didn't > notice? :-)
The code to use asm goto sadly doesn't have any fallback at all for the "no asm goto available".
I guess we're getting close to "we require asm goto support", but I don't think we're there yet.
Also, while "unsafe_put_user()" has been converted to use asm goto (and yes, it really does generate much nicer code), the same is not true of "unsafe_get_user()". Because sadly, gcc does not support asm goto with output values.
So, realistically, my patch is not _technically_ hacky, but it's simply not viable as things stand, and it's more of a tech demonstration than anything else.
Linus
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