Re: [PATCH 3/3] [v4] lib/vsprintf: no_hash_pointers prints all addresses as unhashed

Andy Shevchenko
2021-03-02T19:46:02Z

On Tue, Mar 02, 2021 at 03:28:09PM +0100, Geert Uytterhoeven wrote:
> On Tue, Mar 2, 2021 at 3:08 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> > On Tue, 2 Mar 2021 14:49:42 +0100
> > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > > So this is basically a kernel tinyfication issue, right? Is that still pursued
> > > > today? Are there better config options suitable for this than CONFIG_DEBUG_KERNEL?
> > >
> > > As long as I hear about products running Linux on SoCs with 10 MiB of
> > > SRAM, I think the answer is yes.
> > > I'm not immediately aware of a better config option. There are no more
> > > TINY options left, and EXPERT selects DEBUG_KERNEL.
> >
> > Since the trace_printk() uses the same type of notice, I wonder if we could
> > make this into a helper function and just pass in the top part.
> >
> > + pr_warn("**********************************************************\n");
> > + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
> > + pr_warn("** **\n");
> >
> >
> > + pr_warn("** This system shows unhashed kernel memory addresses **\n");
> > + pr_warn("** via the console, logs, and other interfaces. This **\n");
> > + pr_warn("** might reduce the security of your system. **\n");
> >
> > Only the above section is really unique. The rest can be a boiler plate.
>
> Good idea. drivers/iommu/iommu-debugfs.c has a third copy.

+1. Let's keep it in some helper that can be added if we have a corresponding
functionality.

> > + pr_warn("** **\n");
> > + pr_warn("** If you see this message and you are not debugging **\n");
> > + pr_warn("** the kernel, report this immediately to your system **\n");
> > + pr_warn("** administrator! **\n");
> > + pr_warn("** **\n");
> > + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
> > + pr_warn("**********************************************************\n");
>
> Fortunately gcc is already smart enough to deduplicate identical strings,
> but only in the same source file.

--
With Best Regards,
Andy Shevchenko