Re: [PATCH 1/1] pstore/ram: Ensure stable pmsg address with per-CPU ftrace buffers

From: Kees Cook
Date: Tue Oct 11 2022 - 18:22:40 EST


On Tue, Oct 11, 2022 at 01:44:54PM -0700, Paramjit Oberoi wrote:
> > > The only downside is it would break some code that works today because
> it
> > > ran in contexts where the pmsg address was stable (no per-cpu ftrace
> > > buffers, or power-of-two CPUs).
> >
> > I don't follow? And actually, I wonder about the original patch now --
> > nothing should care about the actual addresses. Everything should be
> > coming out of the pstore filesystem.
>
> We are running VMs with the pstore RAM mapped to a file, and using some
> tools outside the VM to read/manipulate the pstore after VM shutdown.

Ah-ha! Interesting. Well, I think it will be more stable this way even
for that. :)

--
Kees Cook