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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun, 21 Jan 2018 14:27:58 -0800
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Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict
 Indirect Branch Speculation
To:     David Woodhouse <dwmw2@infradead.org>
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On Sun, Jan 21, 2018 at 2:00 PM, David Woodhouse <dwmw2@infradead.org> wrote:
>>
>> The patches do things like add the garbage MSR writes to the kernel
>> entry/exit points. That's insane. That says "we're trying to protect
>> the kernel".  We already have retpoline there, with less overhead.
>
> You're looking at IBRS usage, not IBPB. They are different things.

Ehh. Odd intel naming detail.

If you look at this series, it very much does that kernel entry/exit
stuff. It was patch 10/10, iirc. In fact, the patch I was replying to
was explicitly setting that garbage up.

And I really don't want to see these garbage patches just mindlessly
sent around.

                  Linus