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 90246C8303C for ; Tue, 8 Jul 2025 12:17:10 +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=cLnLB/RO4UTB94beI0koaGJXjHPYatj4KwpOKVL4to4=; b=KKKZ/k2gazEagQw9KrOldMClfm Jxao3HmdX4Eo478eDvGhOAtpm4NczYhkrlEvLrA83SjzpDhct1wQumePaPPVHORatwjZd95wv/W9W xkN/9XPxLS85iMj1UzLnvyIUYi4wuZG+MtbuaKRHnOoQKV0Sie+pDmJi98NAenMbKLI/7zc8r1WQ0 4dv4bA2KqT/8iSk6K1FmSMzh/Fi4AqWQrHplkEIjGtdwq1NjO+3U9g0MnKquZxpkgZhKq/SYon9VX OWYtX+lDOrPTgGkOsMPXecXzRbnYvSGy5qhwgxLGOr9hhLvALIR+CqbuHJhTt0dh9GXHSJKqiBjSn 9nE0TY3Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uZ7Fv-00000005Gxt-1stG; Tue, 08 Jul 2025 12:17:03 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uZ7Da-00000005GfH-2Zjy for linux-arm-kernel@lists.infradead.org; Tue, 08 Jul 2025 12:14:39 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 9C0465C5DC0; Tue, 8 Jul 2025 12:14:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F884C4CEED; Tue, 8 Jul 2025 12:14:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751976876; bh=kEi/z0SApD4McCBJYfg8E/oqKRETuGz5mVH55FI4E9E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=A9gs4jnvcQMxjniKthzF3T8B3QVKkcsrdRfyYJF4BGni/JN22pFgMB8IbtBOz6n3K xNGQHd1htHQ+dG2IRx+Qie9IBQgtvcUNUOgOz/P+oXe6IpiWHMPBitQlBvTJQJIM/h JOOkfwv3qAunprvbL5qDiP4Ij81eqOPJcAVq6V1CcSjfyLPj68UCmGZ2JQBKAkk8jJ knu0fVXaBTkCOGuitbI3jvSyqG4SSSg+sScLbJFsGNatOxuu53pznGGyIGmPq40Pr3 LI0zOG87BaGPM58U4xCr/YjhUwcwwYbac3MsVj9s19Gb98s8WqnypFJ6+ICYkPcCaT yDUMJPB0CU+uQ== Date: Tue, 8 Jul 2025 13:14:31 +0100 From: Will Deacon To: Breno Leitao Cc: Mark Rutland , Catalin Marinas , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, leo.yan@arm.com, kernel-team@meta.com Subject: Re: [PATCH 1/8] arm64: Enable VMAP_STACK support Message-ID: References: <20250707-arm64_vmap-v1-0-8de98ca0f91c@debian.org> <20250707-arm64_vmap-v1-1-8de98ca0f91c@debian.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250708_051438_696152_81D51502 X-CRM114-Status: GOOD ( 19.61 ) 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 Hey Breno, Thanks for doing this. On Tue, Jul 08, 2025 at 02:39:56AM -0700, Breno Leitao wrote: > On Mon, Jul 07, 2025 at 06:23:09PM +0100, Mark Rutland wrote: > > On Mon, Jul 07, 2025 at 09:01:01AM -0700, Breno Leitao wrote: > > > Enable virtually mapped kernel stacks for ARM64. This provides better > > > stack overflow detection and improved security by mapping kernel stacks > > > in vmalloc space rather than using direct mapping. > > > > > > VMAP_STACK helps catch stack overflows early by placing guard pages > > > around kernel stacks, and also provides better isolation between > > > kernel stacks and other kernel data structures. > > > > > > All dependencies are satisfied for arm64: HAVE_ARCH_VMAP_STACK is > > > already selected above, and KASAN_VMALLOC is selected when KASAN is > > > enabled, meeting the KASAN dependency requirements. > > > > I reckon it might be better to say something like: > > > > | arm64: Mandate VMAP_STACK > > | > > | On arm64, VMAP_STACK has been enabled by default for a while now, and > > | the only reason to disable it was a historical lack of support for > > | KASAN_VMALLOC. Today there's no good reason to disable VMAP_STACK. > > | > > | Mandate VMAP_STACK, which will allow code to be simplified in > > | subsequent patches. > > > > ... to make it clear that we're not changing the default, and we are > > removing the ability to deselect VMAP_STACK. > > > > Either way, the patch itself looks good to me. > > Thanks for the suggestion. I will update and respin. No need to respin just for that; I can fold the above when I apply. Cheers, Will