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=-2.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 1244BC433E0 for ; Wed, 13 May 2020 15:09:30 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EE39520659 for ; Wed, 13 May 2020 15:08:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="gpk9V2jT"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="lLF82QDR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE39520659 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=nEyc4mYLKZEgkX5X+zb6r+UpAf709QwKCJLFpzjE2YE=; b=gpk9V2jTPAiUQ8vdtKqhay+uS o2M+UU/4VHBdZieKRZf1hxAm16mE9+6771vfhZ0hRQgo4jLeHN3QgnxYHw1xpssEmp509BE5sNZWZ LOcUu0dfs5wx0Rehc83A84g3xeSAneCaa2wg7MO3XBAaO36iRB8gMm5c2hlF76g+MPdvxPuPSflmA dpOlV2Vh0xR5y4BO36VDwQ6S4vfJhrTHs2c9VdHNBTfQugiv6nwWvy6ncUffdYlBZkF6LUX0n1LtU ez1kZyq49KzI/bqFqkqfB7S0s/DM3newX+EhFxOoYvAxvpPZk8RkYUsIXyBJdV6I4eac57P9QXCXX iQMZMV1Ww==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYszl-0006L3-5c; Wed, 13 May 2020 15:08:29 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYszi-0006KR-K6 for linux-arm-kernel@lists.infradead.org; Wed, 13 May 2020 15:08:27 +0000 Received: from localhost (fw-tnat.cambridge.arm.com [217.140.96.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 41F9820659; Wed, 13 May 2020 15:08:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589382505; bh=qYiDBXXkCe4vI5FEdyOm67jN0dl6hJoRIgo4igWvej8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lLF82QDRLrXLuo9v+UtXZXJyf8MaIWzzQyW4A/Q6iKZ2Ws5UH9aNuo2NqrLGGGcgb b7IjbBtVodL+KRJH36NUAWl1agEK/u3VlqH3iRgfc1tDPk3DZzWRrFAQnE0u2NZtfc GR2jkBVhuqeQNgu9yliw71YMk+WbK5SKnw7kf6VY= Date: Wed, 13 May 2020 16:08:22 +0100 From: Mark Brown To: Dave Martin Subject: Re: [PATCH] arm64: bti: Fix support for userspace only BTI Message-ID: <20200513150822.GK4803@sirena.org.uk> References: <20200512092155.56931-1-broonie@kernel.org> <20200512103908.GB3021@willie-the-truck> <20200512110502.GC5110@sirena.org.uk> <20200513144624.GR21779@arm.com> MIME-Version: 1.0 In-Reply-To: <20200513144624.GR21779@arm.com> X-Cookie: Long life is in store for you. 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-20200513_080826_684145_4A5E39F9 X-CRM114-Status: GOOD ( 19.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: multipart/mixed; boundary="===============2879609671519135085==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============2879609671519135085== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="kswDJesP0akhmDn8" Content-Disposition: inline --kswDJesP0akhmDn8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, May 13, 2020 at 03:46:25PM +0100, Dave Martin wrote: > On Tue, May 12, 2020 at 12:05:02PM +0100, Mark Brown wrote: > > To enable BTI for the vDSO we need the vDSO to be built with BTI > > annotations. Currently the CFLAGS are the same for the vDSO and the > > kernel, we could arrange to allow them to differ but since the most > > likely reason why the user has userspace but not kernel BTI is that > > their compiler isn't suitable it seemed like disproportionate effort > > for a most likely small audience. > The situation where the user is stuck on a binary vendor kernel built > using obsolete or wrongly configured tools doesn't sound that unlikely > to me. They'd need to be stuck on a binary vendor kernel which is sufficiently new to have BTI support but using toolchains that are sufficiently old to be unable to BTI the kernel (if their vendor went out of their way to disable BTI then that's another issue). My guess is that people will tend to update major versions of these at relatively similar times, and hopefully if people are going to the trouble of backporting BTI they'll also grab the toolchain bits since it's substantially more useful if you can compile userspace. > When the vdso was all asm, we could easily have solved this by manually > annotating it ... I guess that's the price of progress, unless anyone > has a bright idea :/ Which is the other bit - if we don't trust the toolchain to build the kernel then we probably ought to have concerns about the C bits of the vDSO as well. Even if they're fine now some future vDSO change could cause this to explode. --kswDJesP0akhmDn8 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl68DWYACgkQJNaLcl1U h9DjSAf/QBbzWjy3aoPYOF95Xw88AYwbEioRUbrRw6Z6r5pGsMkG4coCoojhQvvp sSCebYBZJS8YTslAKLGWSItyJF7mMnz90+eREBsKFfUIArEQrguj8YTlx7xywkD8 RVi15fu8ZkfYPVcdpWgJq4Q0f6j9MHFugcsa6mRHo2djwVNz7i7ZDR8CFxKBmTj/ LQa8mDHYORLqmSH+m59LVKSGKO87EYUI+T//VRHPa5LW7OsaKIceKdlHzfBCpxiM pENeAxdrPeoInbClamPHh4w5qVDrSfeowMqUgpQ/STp/NTCHxb+5mBRO0tRH6H54 s3+Wj/RhHu8rVKEVHP9Y5iMak+gcJA== =9wOd -----END PGP SIGNATURE----- --kswDJesP0akhmDn8-- --===============2879609671519135085== 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 --===============2879609671519135085==--