[PATCH] arm64: Trap WFI executed in userspace
marc.zyngier at arm.com
Thu Sep 20 15:33:20 PDT 2018
On Thu, 20 Sep 2018 23:04:30 +0100,
Pavel Machek <pavel at ucw.cz> wrote:
> On Tue 2018-08-07 10:33:26, Marc Zyngier wrote:
> > It recently came to light that userspace can execute WFI, and that
> > the arm64 kernel doesn trap this event. This sounds rather benign,
> > but the kernel should decide when it wants to wait for an interrupt,
> > and not userspace.
> > Let's trap WFI and treat it as a way to yield the CPU to another
> > process.
> I don't think that's reasonable. Userspace should not be doing that,
> and we do not want to encourage it. SIGILL would be reasonable, I'd
This ship has already sailed. Sending SIGILL changes the ABI in an
incompatible way. Immediately returning to userspace without doing
anything else (see v2 ) is the best we can do without changing the
behaviour of userspace.
Jazz is not dead, it just smell funny.
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