Date: Wed, 3 Jan 2018 16:40:35 -0800
From: Andi Kleen <andi@firstfloor.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        Andi Kleen <andi@firstfloor.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linux-foundation.org>,
        dwmw@amazon.co.uk, Tim Chen <tim.c.chen@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Dave Hansen <dave.hansen@intel.com>
Subject: Re: Avoid speculative indirect calls in kernel
Message-ID: <20180104004034.wouy454tjmitkm5g@two.firstfloor.org>
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> So you say, that we finally need a perl interpreter in the kernel to do
> alternative patching?

I don't think perl or objtool makes sense. That would be just incredibly
fragile because compilers can reorder and mix code. 

It could be done with a gcc change I suppose. That should be reliable.

But that would need to be developed first. We don't have it right now.

As the first step a compile time approach should be sufficient.
We can add a CONFIG option so people can chose at compile time.

Then later we can investigate run time patching.

-Andi