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From: Mark Brown <broonie@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Oliver Upton <oliver.upton@linux.dev>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Arnd Bergmann <arnd@arndb.de>, Oleg Nesterov <oleg@redhat.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Shuah Khan <shuah@kernel.org>,
	"Rick P. Edgecombe" <rick.p.edgecombe@intel.com>,
	Deepak Gupta <debug@rivosinc.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
	Kees Cook <kees@kernel.org>, "H.J. Lu" <hjl.tools@gmail.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Florian Weimer <fweimer@redhat.com>,
	Christian Brauner <brauner@kernel.org>,
	Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
	Ross Burton <ross.burton@arm.com>,
	David Spickett <david.spickett@arm.com>,
	Yury Khrustalev <yury.khrustalev@arm.com>,
	Wilco Dijkstra <wilco.dijkstra@arm.com>,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-mm@kvack.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v13 16/40] KVM: arm64: Manage GCS access and registers for guests
Date: Thu, 3 Oct 2024 15:50:47 +0100	[thread overview]
Message-ID: <1ec14d13-7db6-4642-a14b-db8ae362e594@sirena.org.uk> (raw)
In-Reply-To: <868qv6717r.wl-maz@kernel.org>

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On Wed, Oct 02, 2024 at 08:29:28PM +0100, Marc Zyngier wrote:
> Mark Brown <broonie@kernel.org> wrote:

> > They are, though really they should UNDEF if GCS isn't there (which I
> > had thought was what you were referencing here).  Equally we only have
> > traps for a subset of GCS instructions and it's not like there aren't a
> > whole bunch of untrappable extensions anyway so it's not clear it's
> > worth the effort just for that.

> If the encodings UNDEF when GCS is not implemented (i.e. they are not
> in the NOP space), then all trapable instructions should absolutely
> UNDEF (and yes, it is worth the effort, even if it is only to
> demonstrate that the architecture is sub-par).

Yes, see DDI0487 K.a C5.9.  If you're concerned about being unable to
generate UNDEFs there's a rather large set of existing extensions where
that's not possible, most of the hwcaps in the hwcap selftest that don't
set sigill_reliable but do have a SIGILL generator for a start.

> So I expect the next version to handle traps for GCSPUSHX, GCSPOPX,
> GCSPUSHM, GCSSTR and GCSSTTR when GCS isn't enabled.

OK, I already had that change locally after your first message.

> I'm also pretty sure this is missing some form of sanitisation for
> PSTATE.EXLOCK, and looking at the pseudocode, you seem to be missing
> the handling of that bit on exception injection.

Ah, yes - I think I see the missing exception injection handling in
enter_exception64().  I'm not seeing what you're referencing with
sanitisation though, could you give me some more specific pointers
please?

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  reply	other threads:[~2024-10-03 14:51 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-01 22:58 [PATCH v13 00/40] arm64/gcs: Provide support for GCS in userspace Mark Brown
2024-10-01 22:58 ` [PATCH v13 01/40] mm: Introduce ARCH_HAS_USER_SHADOW_STACK Mark Brown
2024-10-01 22:58 ` [PATCH v13 02/40] mm: Define VM_HIGH_ARCH_6 Mark Brown
2024-10-01 22:58 ` [PATCH v13 03/40] arm64/mm: Restructure arch_validate_flags() for extensibility Mark Brown
2024-10-01 22:58 ` [PATCH v13 04/40] prctl: arch-agnostic prctl for shadow stack Mark Brown
2024-10-01 23:13   ` Deepak Gupta
2024-10-01 22:58 ` [PATCH v13 05/40] mman: Add map_shadow_stack() flags Mark Brown
2024-10-01 22:58 ` [PATCH v13 06/40] arm64: Document boot requirements for Guarded Control Stacks Mark Brown
2024-10-01 22:58 ` [PATCH v13 07/40] arm64/gcs: Document the ABI " Mark Brown
2024-10-01 22:58 ` [PATCH v13 08/40] arm64/sysreg: Add definitions for architected GCS caps Mark Brown
2024-10-01 22:58 ` [PATCH v13 09/40] arm64/gcs: Add manual encodings of GCS instructions Mark Brown
2024-10-01 22:58 ` [PATCH v13 10/40] arm64/gcs: Provide put_user_gcs() Mark Brown
2024-10-01 22:58 ` [PATCH v13 11/40] arm64/gcs: Provide basic EL2 setup to allow GCS usage at EL0 and EL1 Mark Brown
2024-10-09 20:49   ` Nathan Chancellor
2024-10-10 15:18     ` Marc Zyngier
2024-10-10 17:16       ` Catalin Marinas
2024-10-11 12:55         ` Marc Zyngier
2024-10-14 16:31           ` Catalin Marinas
2024-10-15 13:05       ` Catalin Marinas
2024-10-01 22:58 ` [PATCH v13 12/40] arm64/cpufeature: Runtime detection of Guarded Control Stack (GCS) Mark Brown
2024-10-01 22:58 ` [PATCH v13 13/40] arm64/mm: Allocate PIE slots for EL0 guarded control stack Mark Brown
2024-10-01 22:58 ` [PATCH v13 14/40] mm: Define VM_SHADOW_STACK for arm64 when we support GCS Mark Brown
2024-10-01 22:58 ` [PATCH v13 15/40] arm64/mm: Map pages for guarded control stack Mark Brown
2024-10-01 22:58 ` [PATCH v13 16/40] KVM: arm64: Manage GCS access and registers for guests Mark Brown
2024-10-02  0:24   ` Marc Zyngier
2024-10-02 15:55     ` Marc Zyngier
2024-10-02 18:24       ` Mark Brown
2024-10-02 19:29         ` Marc Zyngier
2024-10-03 14:50           ` Mark Brown [this message]
2024-10-01 22:58 ` [PATCH v13 17/40] arm64/idreg: Add overrride for GCS Mark Brown
2024-10-01 22:58 ` [PATCH v13 18/40] arm64/hwcap: Add hwcap " Mark Brown
2024-10-03 16:25   ` Yury Khrustalev
2024-10-01 22:58 ` [PATCH v13 19/40] arm64/traps: Handle GCS exceptions Mark Brown
2024-10-01 22:58 ` [PATCH v13 20/40] arm64/mm: Handle GCS data aborts Mark Brown
2024-10-01 22:59 ` [PATCH v13 21/40] arm64/gcs: Context switch GCS state for EL0 Mark Brown
2024-10-01 22:59 ` [PATCH v13 22/40] arm64/gcs: Ensure that new threads have a GCS Mark Brown
2024-10-04 11:18   ` Catalin Marinas
2024-10-04 11:50     ` Mark Brown
2024-10-01 22:59 ` [PATCH v13 23/40] arm64/gcs: Implement shadow stack prctl() interface Mark Brown
2024-10-01 22:59 ` [PATCH v13 24/40] arm64/mm: Implement map_shadow_stack() Mark Brown
2024-10-01 22:59 ` [PATCH v13 25/40] arm64/signal: Set up and restore the GCS context for signal handlers Mark Brown
2024-10-01 22:59 ` [PATCH v13 26/40] arm64/signal: Expose GCS state in signal frames Mark Brown
2024-10-01 22:59 ` [PATCH v13 27/40] arm64/ptrace: Expose GCS via ptrace and core files Mark Brown
2024-10-01 22:59 ` [PATCH v13 28/40] arm64: Add Kconfig for Guarded Control Stack (GCS) Mark Brown
2024-10-01 22:59 ` [PATCH v13 29/40] kselftest/arm64: Verify the GCS hwcap Mark Brown
2024-10-01 22:59 ` [PATCH v13 30/40] kselftest/arm64: Add GCS as a detected feature in the signal tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 31/40] kselftest/arm64: Add framework support for GCS to signal handling tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 32/40] kselftest/arm64: Allow signals tests to specify an expected si_code Mark Brown
2024-10-01 22:59 ` [PATCH v13 33/40] kselftest/arm64: Always run signals tests with GCS enabled Mark Brown
2024-10-01 22:59 ` [PATCH v13 34/40] kselftest/arm64: Add very basic GCS test program Mark Brown
2024-10-01 22:59 ` [PATCH v13 35/40] kselftest/arm64: Add a GCS test program built with the system libc Mark Brown
2024-10-01 22:59 ` [PATCH v13 36/40] kselftest/arm64: Add test coverage for GCS mode locking Mark Brown
2024-10-01 22:59 ` [PATCH v13 37/40] kselftest/arm64: Add GCS signal tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 38/40] kselftest/arm64: Add a GCS stress test Mark Brown
2024-10-01 22:59 ` [PATCH v13 39/40] kselftest/arm64: Enable GCS for the FP stress tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 40/40] KVM: selftests: arm64: Add GCS registers to get-reg-list Mark Brown
2024-10-04 13:52 ` (subset) [PATCH v13 00/40] arm64/gcs: Provide support for GCS in userspace Catalin Marinas

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