Re: Requirements for retpoline in Linux 4.15 (was: Re: Linux 4.15)

[David Woodhouse]

On Mon, 2018-01-29 at 12:19 +0100, Martin Steigerwald wrote:
> 
> The whole thing works:
> 
> % grep . /sys/devices/system/cpu/vulnerabilities/*ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ
> /sys/devices/system/cpu/vulnerabilities/meltdown:Mitigation: PTI
> /sys/devices/system/cpu/vulnerabilities/spectre_v1:Vulnerable
> /sys/devices/system/cpu/vulnerabilities/spectre_v2:Mitigation: Full genericÂ
> retpoline
> 
> I bet the virtualbox modules compiled by virtualbox-dkms will taint theÂ
> support, but I bet sooner or later they will support retpoline as well.Â
> (Another reason to switch to KVM one day.)

As long as those are actually compiled, it should be fine. Any C code
will be built with the correct CFLAGS.

If they have explicit asm which has indirect jumps, that would still be
a problem. We just need to port objtool into the kernel and do it at
module load time, to check for that... :)

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