Re: [PATCH RFT v3 0/5] fork: Support shadow stacks in clone3()

From: Christian Brauner <brauner@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
	"Rick P. Edgecombe" <rick.p.edgecombe@intel.com>,
	Deepak Gupta <debug@rivosinc.com>,
	"H.J. Lu" <hjl.tools@gmail.com>,
	Florian Weimer <fweimer@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	Shuah Khan <shuah@kernel.org>,
	linux-kernel@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Kees Cook <keescook@chromium.org>,
	jannh@google.com, linux-kselftest@vger.kernel.org,
	linux-api@vger.kernel.org, David Hildenbrand <david@redhat.com>,
	nd@arm.com
Subject: Re: [PATCH RFT v3 0/5] fork: Support shadow stacks in clone3()
Date: Thu, 23 Nov 2023 17:24:48 +0100	[thread overview]
Message-ID: <20231123-edelherzig-feiern-b53339f5a639@brauner> (raw)
In-Reply-To: <ZV85khoUcFyKhQ+w@finisterre.sirena.org.uk>

On Thu, Nov 23, 2023 at 11:37:54AM +0000, Mark Brown wrote:
> On Thu, Nov 23, 2023 at 11:10:24AM +0100, Christian Brauner wrote:
> > On Tue, Nov 21, 2023 at 04:09:40PM +0000, Mark Brown wrote:
> > > On Tue, Nov 21, 2023 at 12:21:37PM +0000, Szabolcs Nagy wrote:
> > > > The 11/21/2023 11:17, Christian Brauner wrote:
> 
> > I'm still not enthusiastic that we only have one implementation for this
> > in the kernel. What's the harm in waiting until the arm patches are
> > merged? This shouldn't result in chicken and egg: if the implementations
> > are sufficiently similar then we can do an appropriate clone3()
> > extension.
> 
> The main thing would be that it would mean that people doing userspace
> enablement based on the merged x86 support can't use the stack size
> control.  It's not the end of the world if that has to wait a bit, it's
> a bit of a detail thing, but it would make life easier, I guess the
> userspace people can let us know if it's starting to be a real hassle
> and we can reevaulate if that happens.
> 
> It's also currently a dependency for the arm64 code so it'd be good to
> at least get ageement that assuming nothing comes up in testing the
> patches can go in along with the arm64 series, removing the dependency

Oh yeah, I'm not fuzzed whose tree this goes through. By all means, take
it with the arm64 series.

> and then adding it as an incremental thing would be a hassle.  It's
> likely that the arm64 series will be held out of tree for a while to as
> more complete userspace support is built up and validated so things
> might be sitting for a while - we don't have hardware right now so we
> can be cautious with the testing.

Ok, that sounds good to me.