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Venkataraman" Cc: jpoimboe@redhat.com, mark.rutland@arm.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v3 2/4] arm64: Check the return PC against unreliable code sections Message-ID: <20210505164648.GC4541@sirena.org.uk> References: <65cf4dfbc439b010b50a0c46ec500432acde86d6> <20210503173615.21576-1-madvenka@linux.microsoft.com> <20210503173615.21576-3-madvenka@linux.microsoft.com> <20210504160508.GC7094@sirena.org.uk> <1bd2b177-509a-21d9-e349-9b2388db45eb@linux.microsoft.com> <0f72c4cb-25ef-ee23-49e4-986542be8673@linux.microsoft.com> MIME-Version: 1.0 In-Reply-To: <0f72c4cb-25ef-ee23-49e4-986542be8673@linux.microsoft.com> X-Cookie: Please ignore previous fortune. User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210505_094725_852314_D191B484 X-CRM114-Status: GOOD ( 12.70 ) 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: multipart/mixed; boundary="===============0098058495657783502==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============0098058495657783502== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="GPJrCs/72TxItFYR" Content-Disposition: inline --GPJrCs/72TxItFYR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 04, 2021 at 02:32:35PM -0500, Madhavan T. Venkataraman wrote: > If you prefer, I could do something like this: >=20 > check_pc: > if (!__kernel_text_address(frame->pc)) > frame->reliable =3D false; >=20 > range =3D lookup_range(frame->pc); >=20 > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > if (tsk->ret_stack && > frame->pc =3D=3D (unsigned long)return_to_handler) { > ... > frame->pc =3D ret_stack->ret; > frame->pc =3D ptrauth_strip_insn_pac(frame->pc); > goto check_pc; > } > #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ > Is that acceptable? I think that works even if it's hard to love the goto, might want some defensiveness to ensure we can't somehow end up in an infinite loop with a sufficiently badly formed stack. --GPJrCs/72TxItFYR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmCSy/cACgkQJNaLcl1U h9ABjAf/fEFuQnVM2PvVSSZ12g8EU3JD2pWnZUmAS5BwePbK0p37pAFxtY+RmvAQ DwaiqGBi0F7QP8FToXUPDsds7X9jQy8+8yHMNbt878ScDIz5SKNuR29m2ADQ/cKr OZD8Jv3poTDRDVUNequtEEqt4T+90tBlCN6ZKBlxH7wV2ArU3cUJ8Oa/vQyouyoc VPzvPAZY1zupyPtDNPzK31AkkyWhhmOZJmckQuJ1p8KC5aKZCRcEvmPA5jX9QYvq oesi89rEjZVhXphISnELRwpfcvJx/O203iRhTbuJ06nU/KxZLBXWAmj/vaXhggog jAkfptyHcleFuFCNNsKFLCY3o/TQ6A== =fJrE -----END PGP SIGNATURE----- --GPJrCs/72TxItFYR-- --===============0098058495657783502== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============0098058495657783502==--