Re: [PATCH 0/4 v4] exec: inherit HWCAPs from the parent process

On Mon, Feb 23, 2026 at 2:29 PM Kees Cook <[email protected]> wrote:
>
> On Mon, Feb 23, 2026 at 10:29:00AM -0800, Andrei Vagin wrote:
> > On Tue, Feb 17, 2026 at 10:01 AM Andrei Vagin <[email protected]> wrote:
> > >
> > > This patch series introduces a mechanism to inherit hardware capabilities
> > > (AT_HWCAP, AT_HWCAP2, etc.) from a parent process when they have been
> > > modified via prctl.
> > >
> > > To support C/R operations (snapshots, live migration) in heterogeneous
> > > clusters, we must ensure that processes utilize CPU features available
> > > on all potential target nodes. To solve this, we need to advertise a
> > > common feature set across the cluster.
> > >
> > > Initially, a cgroup-based approach was considered, but it was decided
> > > that inheriting HWCAPs from a parent process that has set its own
> > > auxiliary vector via prctl is a simpler and more flexible solution.
> > >
> > > This implementation adds a new mm flag MMF_USER_HWCAP, which is set when the
> > > auxiliary vector is modified via prctl(PR_SET_MM_AUXV). When execve() is
> > > called, if the current process has MMF_USER_HWCAP set, the HWCAP values are
> > > extracted from the current auxiliary vector and inherited by the new process.
> > >
> > > The first patch fixes AUXV size calculation for ELF_HWCAP3 and ELF_HWCAP4
> > > in binfmt_elf_fdpic and updates AT_VECTOR_SIZE_BASE.
> > >
> > > The second patch implements the core inheritance logic in execve().
> > >
> > > The third patch adds a selftest to verify that HWCAPs are correctly
> > > inherited across execve().
> > >
> > > v4: minor fixes based on feedback from the previous version.
> >
> > Kees,
> >
> > I think it is ready to be merged. Let me know if you have any other
> > comments/concerns/questions.
>
> Yeah, I think it's looking good. I'll land this in for-next/execve after
> rc2 (a week from now).

Hi Kees, just a friendly ping in case this slipped off your radar.

Thanks,
Andrei