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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 9F1EBC5CFC1 for ; Sat, 15 Aug 2026 21:54:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc: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=L1xQp6TnnctvVRvsmBO7lNUazoq7APGQJNQv5Cgr9VY=; b=Tv9gNkGHVrQoLFrVuw9jYaEfJN 0G4wI7WCauX6ciqTFrqWYi4CeyJ8mjZx5SexNoE8pXOo95f2mO4xWMtkFhPCaMRicCgpP9OoaCEI/ fbJw2QyAdpfqcktBvZeMDyX+s9+TNV2I/FYgv2EB2oAyTX+Cj8cTlh+IPpVlKzpEngcs+Zbcrnc3z DplvDa2Ehu4xpcUGURy+il5NgNeOfNqO2tXz2995ZLTlQRvZ+luSNf5uPpqyrj7rG93fuHvNKSdoB IqA+JLww2JzL6a5ruAG6wKfMowUfAKxRQiTVbF5JzKgic0qc8vQEAwrzKgtCFvWjh6w4fTESnqduj t+3nJdfA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wvMK5-00000004DgT-0GyE; Sat, 15 Aug 2026 21:53:49 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wvMK4-00000004DgN-1832 for linux-arm-kernel@lists.infradead.org; Sat, 15 Aug 2026 21:53:48 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 126FD60052; Sat, 15 Aug 2026 21:53:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 899231F000E9; Sat, 15 Aug 2026 21:53:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786830826; bh=L1xQp6TnnctvVRvsmBO7lNUazoq7APGQJNQv5Cgr9VY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=iYQysflY5z6LJOT1PECEy9L7Pyjgx1OkM93zbDsKBNftTWEYrJM1TejoFe1QcGD1j vWUFEV3hP9K2B14HKBsAvHwR4JSu2Y/WoXijAtHIurutCR+a1kKKqOmPx9mfqgB943 UNSv9khD0ANzi2gjhOLAT/2GlKhoHuDyZbHoQKasx46rMvaHfp2dLKr+dP4vOm6tvK TyjVuSfM9PkRvDs1pDyiTNi24oR7kmZsPCx4kAAxiQauaLeWIxTA64PUj+rx43NIm3 NzK9CfqJnDii5NhMtSwvxLywVHYJMGUDfUE5KvY+51aHKRdnk/P7cR0mZLUg86BRut Mk8k4bt1Vgj5A== Received: by finisterre.sirena.org.uk (Postfix, from userid 1000) id 6EE2E1AC527F; Sat, 15 Aug 2026 22:53:43 +0100 (BST) Date: Sat, 15 Aug 2026 22:53:43 +0100 From: Mark Brown To: Josh Poimboeuf Cc: Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, Song Liu , Miroslav Benes , Petr Mladek , Joe Lawrence , Mark Rutland , Nick Desaulniers , Kees Cook , Nathan Chancellor , linux-toolchains@vger.kernel.org Subject: Re: [PATCH 07/12] arm64/bti: Advertise BTI in assembly objects Message-ID: References: <5340f3df281bebc81aad3cd9a7471d95061b4b9d.1786768375.git.jpoimboe@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="hHV2ZweC5h7oUr++" Content-Disposition: inline In-Reply-To: <5340f3df281bebc81aad3cd9a7471d95061b4b9d.1786768375.git.jpoimboe@kernel.org> X-Cookie: My vaseline is RUNNING... 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --hHV2ZweC5h7oUr++ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Aug 14, 2026 at 09:45:24PM -0700, Josh Poimboeuf wrote: > On a kernel whose text exceeds the +/-128MB direct branch range, the > linker inserts veneers. With BTI enabled, the veneers' indirect branch > targets need a BTI landing pad, which not all functions have starting > with Clang 21 (and for all versions of GCC). We already have explicit note generation support in asm/assembler.h which is used in the vDSO code, it probably makes sense to replace that too. I didn't check if there's potential for the two to collide with this as is. --hHV2ZweC5h7oUr++ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmqA3+YACgkQJNaLcl1U h9A/DQf/WTnuS2TWA3jYmXlJx0LmO3Ydemf68Q8UJia96H0cXBoAVbvlCLGelBJ+ xwrW2pLUAszFkVhshCZn9wIsBxiaJHvjNEJBiV11UN27ogqwqkF8P5omVVAoUx9n Jd8YZb4KIDcof9ZXXeug2J5QFkXaZQ+TjCCAKunMT94QPA4Ku2PLSs41CVdm1aBB Hda9JTCPsvER87662JHG7mICgPmUmlDQKwHpxS9V9YE+/fx+kgARnoEGc1O32DOb JKhYD8v22nrMHu0sdcpQMwjc/6GDvB6nGzFsxtwqi9sOQ6RNDffXKaHWWnxY1+74 ZNAOYbZgbFNcnQb5BDrpiUMHGbWfjA== =y+lK -----END PGP SIGNATURE----- --hHV2ZweC5h7oUr++--