Re: [PATCH v2 5.4 regression fix] x86/boot: Provide memzero_explicit

[Hans de Goede]

Hi,

On 07-10-2019 20:42, Arvind Sankar wrote:
> On Mon, Oct 07, 2019 at 05:40:07PM +0200, Ingo Molnar wrote:
> > * Arvind Sankar <nivedita@xxxxxxxxxxxx> wrote:
> >
> > > With the barrier in there, is there any reason to *not* inline the
> > > function? barrier_data() is an asm statement that tells the compiler
> > > that the asm uses the memory that was set to zero, thus preventing it
> > > from removing the memset even if nothing else uses that memory later. A
> > > more detailed comment is there in compiler-gcc.h. I can't see why it
> > > wouldn't work even if it were inlined.
> > >
> > > If the function can indeed be inlined, we could just make the common
> > > implementation a macro and avoid duplicating it? As mentioned in another
> > > mail, we otherwise will likely need another duplicate implementation for
> > > arch/s390/purgatory as well.
> >
> > I suspect macro would be justified in this case. Mind sending a v3 patch
> > to demonstrate how it would all look like?
> >
> > I'll zap v2 if the macro solution looks better.
> >
> > Thanks,
> >
> > 	Ingo
>
> Patch attached to turn memzero_explicit into inline function.

Hehe, I had prepared and have just tested the exact same patch
(only the commit msg was different).

I've just booted a kernel build with that patch and that works
fine (as expected).

So your patch is:

Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>

Since this is a bit of a core change though, I think it is
best if you send it to the linux-kernel list (with my tags from above
added) as is normally done for kernel patches. Then others, who may
not be following this thread, will get a chance to give feedback on it.

Regards,

Hans