linux-kernel - PTI build regression with nvidia drivers

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Message-ID: <CAGXu5jLM6NXoP9dCAiYDKUaGzSGp7WAY3PpUq-2osL4WLQg2Dg@mail.gmail.com>
Date:   Thu, 4 Jan 2018 10:17:23 -0800
From:   Kees Cook <keescook@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: PTI build regression with nvidia drivers

Hi,

This was pointed out in a few places, but not forwarded to lkml yet that I saw:

https://devtalk.nvidia.com/default/topic/1028222/linux/lts-kernel-patch-for-intel-cpu-vulnerability-breaks-nvidia-driver/post/5230546

Before and after PTI, cpu_tlbstate is a GPL export:

$ git show v4.14:arch/x86/mm/init.c | grep cpu_tlbstate
DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate) = {
EXPORT_SYMBOL_GPL(cpu_tlbstate);

But after PTI, inlining or something is dragging cpu_tlbstate into the
open, causing build failures.

Technically, to avoid regressions for that module, we'll need to drop
the GPL marking on that symbol, or find some other solution...

-Kees

-- 
Kees Cook
Pixel Security