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b=a3e5etiaCTIf6mj5LJfPayGGRPCkqpzgVIw1FeLdsLBfQNoMAL/qYtEtGJibhp3oU XvqjYzMm14iBcabQH9ixoP1adKlIOXGttkEhHZ12Rn+NE7gvkO0FpJV0Zyj8nQwHej MjS2muDzwVxCuK7DRdg1nW1guor/t1KJ5KFDRVtVQGCSbEzRP9ZExfSI7/m4gQY7lu IH2ENW1K8nf3rbsVt1oRT1ORFvOCs/E01MBBu4hQdhIY6WX6HFJELx88n+Vg8H2giH DQ7AfczuUA1Y5ZtqJLYSw5zzQXVd8T4Ihv2M8i5skO8VC6v+6w6nuxJvbPeOJJ9KVr TwOSG7d+bkkgA== Date: Thu, 22 Feb 2024 13:33:10 +0000 From: Mark Brown To: Deepak Gupta Cc: rick.p.edgecombe@intel.com, Szabolcs.Nagy@arm.com, kito.cheng@sifive.com, keescook@chromium.org, ajones@ventanamicro.com, paul.walmsley@sifive.com, palmer@dabbelt.com, conor.dooley@microchip.com, cleger@rivosinc.com, atishp@atishpatra.org, alex@ghiti.fr, bjorn@rivosinc.com, alexghiti@rivosinc.com, corbet@lwn.net, aou@eecs.berkeley.edu, oleg@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, ebiederm@xmission.com, shuah@kernel.org, brauner@kernel.org, guoren@kernel.org, samitolvanen@google.com, evan@rivosinc.com, xiao.w.wang@intel.com, apatel@ventanamicro.com, mchitale@ventanamicro.com, waylingii@gmail.com, greentime.hu@sifive.com, heiko@sntech.de, jszhang@kernel.org, shikemeng@huaweicloud.com, david@redhat.com, charlie@rivosinc.com, panqinglin2020@iscas.ac.cn, willy@infradead.org, vincent.chen@sifive.com, andy.chiu@sifive.com, gerg@kernel.org, jeeheng.sia@starfivetech.com, mason.huo@starfivetech.com, ancientmodern4@gmail.com, mathis.salmen@matsal.de, cuiyunhui@bytedance.com, bhe@redhat.com, chenjiahao16@huawei.com, ruscur@russell.cc, bgray@linux.ibm.com, alx@kernel.org, baruch@tkos.co.il, zhangqing@loongson.cn, catalin.marinas@arm.com, revest@chromium.org, josh@joshtriplett.org, joey.gouly@arm.com, shr@devkernel.io, omosnace@redhat.com, ojeda@kernel.org, jhubbard@nvidia.com, linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH v1 15/28] riscv/mm: Implement map_shadow_stack() syscall Message-ID: <6ad3e87a-25ab-4938-8d81-c5c609619586@sirena.org.uk> References: <20240125062739.1339782-1-debug@rivosinc.com> <20240125062739.1339782-16-debug@rivosinc.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="LxmbY0AjUg4WDPUw" Content-Disposition: inline In-Reply-To: X-Cookie: I have accepted Provolone into my life! X-Rspamd-Queue-Id: C736210000A X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 871wjgnp9wkuui9sf4ibamqu7wfmo1tk X-HE-Tag: 1708608811-670796 X-HE-Meta: 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 M8oUH8We 7IgCzHmtSILiJQG1iQtYojDch0OiaBMBR46Pr379yhQP5JYf6+dasAncmDIRqKfTs2GxKWoqX6uf+eI4O4agtWpUkwKP6i96bWAH0PVM7QYno/KfRzdPXfNbZBGAEQpEXkCz8nIw39+fcGepcCQ0oS7BO/HPCObyvrlccHddZDif8N0GCj2hp+aErJwVeS3SLVsF56rLBZ6vBb1z2mpOf4wLPXr1NKS2LuizbnAaZkWNmSuDV9h9nuOaK6f6oGGPPkZgkaiDkiWHQoWsm7thQ/6arnQrphgi5eqWnDLiOQYqiEfs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --LxmbY0AjUg4WDPUw Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Feb 21, 2024 at 04:47:11PM -0800, Deepak Gupta wrote: > On Tue, Feb 06, 2024 at 04:01:28PM +0000, Mark Brown wrote: > > > +#define SHADOW_STACK_SET_TOKEN (1ULL << 0) /* Set up a restore token in the shadow stack */ > > For arm64 I also added a SHADOW_STACK_SET_MARKER for adding a top of > > stack marker, did you have any thoughts on that for RISC-V? I think x86 > > were considering adding it too, it'd be good if we could get things > > consistent. > Please correct me on this. A token at the top which can't be consumed to restore > but *just* purely as marker, right? Yes, for arm64 we just leave a zero word (which can't be a valid token) above the stack switch token, that does mean you can't exactly tell that the top of stack marker is there unless there's also a stack switch token below it. > It's a good design basic with not a lot of cost. > I think risc-v should be able to converge on that. Great. --LxmbY0AjUg4WDPUw Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmXXTRUACgkQJNaLcl1U h9ChLQf/TR/+XFN8k0dkmk90JLlGHu3WaTQM0wqbCtUC2FExSxw4JGFIeRSKnUum 10loLkMwAaklC1on36bhQcqVQ+qMOoVN0k9k+YJpi4iXFDo6LH95Z4Qwq37xUQOg EI+FqbA6BiCGk1OVOHibZO51nBBmQuwO4c/MYT24AYyoR2/uk6OPE+G1Mm7K4/M6 zukeMbRS4LPn++luduEqROdMpJNdEBjeSELUQL8AjyUFemzG6ZlpojuJAvVNbVsN COBlGD75skhCaSfor7bhAv3iKrr+htaWDZ3zwkPMjlufoZjwYBUb+h3A7eE2G2YF wLkwHJN21WNLbqxqHXvjCFibtxling== =mXRS -----END PGP SIGNATURE----- --LxmbY0AjUg4WDPUw--