Re: [PATCH v12 0/6] implement getrandom() in vDSO

Jason A. Donenfeld
2022-12-21T14:25:55Z

On Tue, Dec 20, 2022 at 08:13:14PM +0000, Eric Biggers wrote:
> On Tue, Dec 20, 2022 at 05:17:52PM +0000, Christophe Leroy wrote:
> > Hi Jason,
> >
> > Le 12/12/2022 à 19:53, Jason A. Donenfeld a écrit :
> > > Changes v11->v12:
> > > ----------------
> > > - In order to avoid mlock()ing pages, and the related rlimit and fork
> > > inheritance issues there, Introduce VM_DROPPABLE to prevent swapping
> > > while meeting the cache-like requirements of vDSO getrandom().
> > >
> > > This has some tenticles in mm/ and arch/x86/ code, so I've marked the
> > > two patches for that as still RFC, while the rest of the series is not
> > > RFC.
> > >
> > > - Mandate that opaque state blobs don't straddle page boundaries, so
> > > that VM_DROPPABLE can work on page-level granularity rather than
> > > allocation-level granularity.
> > >
> > > - Add compiler barriers to vDSO getrandom() to prevent theoretical
> > > reordering potential.
> > >
> > > - Initialize the trials loop counter in the chacha test.
> >
> > I would have liked to give it a try on powerpc, but the series
> > conflicts. I tried both on v6.1 and on linus/master from now:
> >
>
> Same here, I can't figure out how to apply this series.

Rebased v13 posted: https://lore.kernel.org/all/20221221142327.126451-1-Jason@zx2c4.com/

Jason