From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E2FEC43460 for ; Thu, 8 Apr 2021 16:58:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 21B38610A2 for ; Thu, 8 Apr 2021 16:58:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232428AbhDHQ64 (ORCPT ); Thu, 8 Apr 2021 12:58:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:43868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231566AbhDHQ6z (ORCPT ); Thu, 8 Apr 2021 12:58:55 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 32675610CB; Thu, 8 Apr 2021 16:58:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617901123; bh=PZNfTKA5x4FKKMhvyT5cCCUAlEeo8PRtWyGGv8cGvvo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=t61RSwV1ntvkbNH52ixOuqu9drh9ySIlZ/f5pq5wqtlgstkz/MWkNd1guMnGwXlZo O0AnUrJPDni8kfEheiGDsTDdVthmgTDVrrSh0d8aeY9yo23/ITcE8rvA988zp2IW6L vExr3mwpgkwaBXe1NtNroyDPUCQn0GKUz74GZt89FZDlMzy6dm/dius/VtwsqL/Q72 sDFxiioJJQD+2k909GMSh6HZ4Vcgdcwo6HAElAYSs5qxbh9QEg/NoQstH+2E66ng8T aGSKUQikK8iXgGb5iMdbBe3+J4jt4q7Dd8jAU62Lq8HL1GCYbmePZBpt1+byF17ngs hT5PlHSlgnrQg== Date: Thu, 8 Apr 2021 17:58:25 +0100 From: Mark Brown To: madvenka@linux.microsoft.com, mark.rutland@arm.com Cc: jpoimboe@redhat.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 3/4] arm64: Detect FTRACE cases that make the stack trace unreliable Message-ID: <20210408165825.GP4516@sirena.org.uk> References: <705993ccb34a611c75cdae0a8cb1b40f9b218ebd> <20210405204313.21346-1-madvenka@linux.microsoft.com> <20210405204313.21346-4-madvenka@linux.microsoft.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="LfQcPIWFRhGivmDw" Content-Disposition: inline In-Reply-To: <20210405204313.21346-4-madvenka@linux.microsoft.com> X-Cookie: Editing is a rewording activity. User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --LfQcPIWFRhGivmDw Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 05, 2021 at 03:43:12PM -0500, madvenka@linux.microsoft.com wrot= e: > From: "Madhavan T. Venkataraman" >=20 > When CONFIG_DYNAMIC_FTRACE_WITH_REGS is enabled and tracing is activated > for a function, the ftrace infrastructure is called for the function at > the very beginning. Ftrace creates two frames: This looks good to me however I'd really like someone who has a firmer understanding of what ftrace is doing to double check as it is entirely likely that I am missing cases here, it seems likely that if I am missing stuff it's extra stuff that needs to be added and we're not actually making use of the reliability information yet. --LfQcPIWFRhGivmDw Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmBvNjEACgkQJNaLcl1U h9DvhAgAgAJBXnn2mXE3bqxCAxxZ0ON7WKXWJ4AqHOgUJMlSbwacx8qcSZk15YJG yR02M4hQMPpKRHHSCfNvn1EoC2DHR/HbnibDN0hTe1RkYsPKUv85X+nwHLb1uW49 Yg/tpZ4OSFmMCQYQopW0bffgNK05i0cypnANyGM45qooTdOyMQOUf7Nw7FbUWjSK aDHHHeWMCs/CZy6as3c1m5PDrgKncByRVcKT6o1eack0p6Ok6zPmSUe9uePVzLoB NJ+QPh+s0SCltRZ0MG5cC/+NNC0d/Z9CMwzrcSMg+n9VzQIjX3C+cB+6wVxMdAv8 3KA3kaFHl1DWgtYLfdxdE0q/hkrBzg== =xE1N -----END PGP SIGNATURE----- --LfQcPIWFRhGivmDw--