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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id x34-20020a056a000be200b005106b52a823sm1636570pfu.145.2022.05.05.17.00.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 17:00:06 -0700 (PDT) Date: Thu, 5 May 2022 17:00:05 -0700 From: Kees Cook To: Ard Biesheuvel Cc: linux-arm-kernel@lists.infradead.org, will@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, maz@kernel.org, Sami Tolvanen , Fangrui Song , Nick Desaulniers , Dan Li Subject: Re: [RFC PATCH v2 3/3] arm64: implement dynamic shadow call stack for Clang Message-ID: <202205051657.A83407E@keescook> References: <20220505161011.1801596-1-ardb@kernel.org> <20220505161011.1801596-4-ardb@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220505161011.1801596-4-ardb@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220505_170007_664634_35C350E4 X-CRM114-Status: GOOD ( 13.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, May 05, 2022 at 06:10:11PM +0200, Ard Biesheuvel wrote: > [...] > + /* > + * We only enable the shadow call stack dynamically if we are running > + * on a system that does not implement PAC or BTI. PAC and SCS roughly > + * provide the same level of protection, and BTI relies on the PACIASP > + * instructions serving as landing pads, preventing us from patching > + * those instructions into something else. > + */ If BTI relies on PAC, then we only need to check for PAC, yes? I.e. there isn't going to be a device with BTI but without PAC. -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel