On Fri, Nov 26, 2021 at 11:10 AM Ard Biesheuvel [off-list ref] wrote:

Enable the use of the TLS register to hold the 'current' pointer for all
configurations that can support it, including non-SMP ones that target
v6k or later CPUs, and multi-platform SMP ones that also support v6
based UP systems.

The remaining configurations are all strictly UP, which means we can
switch to a global variable to hold the current pointer. By doing this,
we can enable THREAD_INFO_IN_TASK, which moves thread info off the
stack, protecting it from overflows. It also permits us to enable IRQ
stacks and vmap'ed stacks for UP configurations as well.

I really like what I see here!

I glanced over it but sadly do not have sufficient time to read every
detail of it, but I certainly trust to to get things right and iron out any
rough corners so FWIW:
Acked-by: Linus Walleij <redacted>
on this patch set.

Supporting v6 cores without SMP extensions in SMP configurations (e.g.,
omap2plus_defconfig or imx_v6_v7_defconfig) makes this a bit tricky, and
this is a feature we may consider dropping entirely in the future. But
for the time being, we can support this mode as well.

Hmmm yes these will look odd and I can see it really makes the
patch hairy too. I think people might be using them though :/

Yours,
Linus Walleij

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