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[2620:137:e000::1:20]) by mx.google.com with ESMTP id u9-20020a637909000000b003c16c345014si6517882pgc.854.2022.05.19.07.59.27; Thu, 19 May 2022 07:59:39 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=eL8pdHPx; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231869AbiESJCX (ORCPT + 99 others); Thu, 19 May 2022 05:02:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232291AbiESJCS (ORCPT ); Thu, 19 May 2022 05:02:18 -0400 Received: from mail-io1-xd2b.google.com (mail-io1-xd2b.google.com [IPv6:2607:f8b0:4864:20::d2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEE08A5022; Thu, 19 May 2022 02:02:16 -0700 (PDT) Received: by mail-io1-xd2b.google.com with SMTP id p74so1458811iod.8; Thu, 19 May 2022 02:02:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc:content-transfer-encoding; bh=NFytTSvpESA+gNTucGdfA0zmuvcHaBQUd/+6cBap22I=; b=eL8pdHPx4vN0d5L7qUH6EoYO1SdzoGbuSRbXHYt3rldg70paJSV7wpHk3Mzhr0mEEM OHkEXPU9Kc+QHINA29ZqAZpIvhHwSXMFhnk0hZQDa9ZIkexddhVNvYFfhyfIlp0GIiz0 spn0l590s/wnxqGjmThGAcSi7NAgRHAp02i4JjMh+6cBdxsieR5UQpoYZz6tGZC1M70p AiH6t8vzrLCnchk2o0EnO2dYn1dszZ3Gf2KS07k/ZXmtv1xzAdda8e3dr8LyZz9QeMdY lC+Agfh0KyWKhdYSixDdqKXHBe7iKvNcpLqgcJW3jhjWgPkV1Uynj5DXG/ul8fsxUDBH FsgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc:content-transfer-encoding; bh=NFytTSvpESA+gNTucGdfA0zmuvcHaBQUd/+6cBap22I=; b=H5K0Cn2JYFNgN/tyBYbsrfuUqs5oTgdiUWS16PjprA9P2+/c3v7mY0YGo7uremvw3A 9OxAMMp8g1px09zYRIYZIbMTekrA9yrrdtxXMUb6qP+bq3jBXVrvXy8zpYP4Mq3C8/Jr c8C5Q6ICPXvlcJP5CHHIGgiSiy7UA1C9FOsRZ/UufWkHiNeyoqYsTRFEA9T4d8kgt812 ey4XuSV1yOb0+0huRuMTBMmcpnh67i+jrf2jOm0oXlBg5LIGa4o8g7XbADH70pjMDCeD OY/kvDm+JbVebWvUDndFYTWuOrOOsRxA9YyPf/pEV+vh5C/uv7ZT1uJ7V8/UO2ZTlx8e cozA== X-Gm-Message-State: AOAM5333GY9zDaedM0y7TFuU82vO8twiSoGLhNHbj+NVa68+f/iSrvIU HTZSaN2DIRK224xp+Ra0jjVVor/mKoMAwO6kLLgN6/0KK2Q= X-Received: by 2002:a05:6602:1542:b0:65a:bc5d:db78 with SMTP id h2-20020a056602154200b0065abc5ddb78mr1967758iow.128.1652950936005; Thu, 19 May 2022 02:02:16 -0700 (PDT) MIME-Version: 1.0 References: <20220513202159.1550547-1-samitolvanen@google.com> In-Reply-To: Reply-To: sedat.dilek@gmail.com From: Sedat Dilek Date: Thu, 19 May 2022 11:01:40 +0200 Message-ID: Subject: Re: [RFC PATCH v2 00/21] KCFI support To: Nathan Chancellor Cc: Sami Tolvanen , linux-kernel@vger.kernel.org, Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nick Desaulniers , Joao Moreira , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 17, 2022 at 8:49 PM Nathan Chancellor wrote= : > > On Tue, May 17, 2022 at 09:33:47AM +0200, Sedat Dilek wrote: > > Is your tags/kcfi-rfc-v2 the recommended LLVM toolchain for testing kcf= i-rfc-v2? > > > > What I want to ask is if your commit well tested for x86 (and arm64) > > means build and boot on bare metal? > > I have run kCFI (v1, I haven't had time to test v2) on x86_64 hardware, > both AMD and Intel. I have only found two failures so far: the i915 > issue that I mention below and a failure in the KVM subsystem, which I > can see by just running QEMU: > Is there a fix around this issue? > [ 124.344654] CFI failure at kvm_mmu_notifier_invalidate_range_end+0xca/= 0x177 [kvm] (target: kvm_null_fn+0x0/0x7 [kvm]; expected type: 0x1e2c5b9c) > [ 124.344691] WARNING: CPU: 5 PID: 2767 at kvm_mmu_notifier_invalidate_r= ange_end+0xca/0x177 [kvm] > [ 124.344708] Modules linked in: ... > [ 124.344737] CPU: 5 PID: 2767 Comm: qemu-system-x86 Tainted: P = 5.18.0-rc6-debug-00033-g1d5284aff7cd #1 8c4966c7fb24f3345076747fee= bac5fb340a4797 > [ 124.344738] Hardware name: ASUS System Product Name/PRIME Z590M-PLUS, = BIOS 1203 10/27/2021 > [ 124.344738] RIP: 0010:kvm_mmu_notifier_invalidate_range_end+0xca/0x177= [kvm] > [ 124.344756] Code: 48 89 da e8 88 16 86 dd 48 85 c0 89 6c 24 0c 74 30 4= d 85 f6 74 36 48 c7 c5 19 c8 b4 c0 4c 8b 34 24 81 7d fa 9c 5b 2c 1e 74 02 <= 0f> 0b 48 89 c7 4c 89 fe 48 89 da e8 b6 16 86 dd 48 85 c0 75 e2 eb > [ 124.344757] RSP: 0018:ffffc033039d78e8 EFLAGS: 00010282 > [ 124.344758] RAX: ffffa0a141ed9450 RBX: 00007fb897e9efff RCX: ffffa0a14= 3c9d850 > [ 124.344758] RDX: 00007fb897e9efff RSI: 00007fb897e9e000 RDI: ffffc0330= 4499cf8 > [ 124.344759] RBP: ffffffffc0b4c819 R08: 0000000000000000 R09: 000000000= 0000000 > [ 124.344759] R10: 0000000000000000 R11: ffffffffc0b4c639 R12: ffffc0330= 4499000 > [ 124.344760] R13: ffffc033044a30a0 R14: ffffc033044a3120 R15: 00007fb89= 7e9e000 > [ 124.344760] FS: 00007fbca4bc3640(0000) GS:ffffa0a87f540000(0000) knlG= S:0000000000000000 > [ 124.344761] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 124.344761] CR2: 0000000000000000 CR3: 0000000119f74006 CR4: 000000000= 0772ee0 > [ 124.344762] PKRU: 55555554 > [ 124.344762] Call Trace: > [ 124.344762] > [ 124.344763] __mmu_notifier_invalidate_range_end+0xa1/0xd7 > [ 124.344764] wp_page_copy+0x592/0x920 > [ 124.344766] __handle_mm_fault+0x820/0x8f0 > [ 124.344767] handle_mm_fault+0xe0/0x227 > [ 124.344768] __get_user_pages+0x17a/0x430 > [ 124.344769] get_user_pages_unlocked+0xd9/0x327 > [ 124.344770] hva_to_pfn+0xfa/0x3f7 [kvm 950e483805e01f967a3e331506278d= 766494a4cc] > [ 124.344788] kvm_faultin_pfn+0xc3/0x2f0 [kvm 950e483805e01f967a3e33150= 6278d766494a4cc] > [ 124.344806] ? fast_page_fault+0x400/0x4c0 [kvm 950e483805e01f967a3e33= 1506278d766494a4cc] > [ 124.344823] direct_page_fault+0x130/0x350 [kvm 950e483805e01f967a3e33= 1506278d766494a4cc] > [ 124.344841] kvm_mmu_page_fault+0x176/0x2f7 [kvm 950e483805e01f967a3e3= 31506278d766494a4cc] > [ 124.344858] vmx_handle_exit+0xe/0x37 [kvm_intel 647f514f18fc365045dc5= 7db46d2bb4930b746eb] > [ 124.344863] vcpu_enter_guest+0xbff/0x1030 [kvm 950e483805e01f967a3e33= 1506278d766494a4cc] > [ 124.344881] vcpu_run+0x65/0x2f0 [kvm 950e483805e01f967a3e331506278d76= 6494a4cc] > [ 124.344898] kvm_arch_vcpu_ioctl_run+0x15f/0x3f7 [kvm 950e483805e01f96= 7a3e331506278d766494a4cc] > [ 124.344916] kvm_vcpu_ioctl+0x547/0x627 [kvm 950e483805e01f967a3e33150= 6278d766494a4cc] > [ 124.344933] ? syscall_exit_to_user_mode+0x24/0x47 > [ 124.344934] ? do_syscall_64+0x7a/0x97 > [ 124.344935] ? __fget_files+0xa1/0xc0 > [ 124.344936] __se_sys_ioctl+0x7c/0xc0 > [ 124.344937] do_syscall_64+0x6c/0x97 > [ 124.344938] ? do_syscall_64+0x7a/0x97 > [ 124.344939] entry_SYSCALL_64_after_hwframe+0x44/0xae > [ 124.344940] RIP: 0033:0x7fbca75f7b1f > [ 124.344940] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 0= 0 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <= 89> c2 3d 00 f0 ff ff 77 18 48 8b 44 24 18 64 48 2b 04 25 28 00 00 > [ 124.344941] RSP: 002b:00007fbca4bc2550 EFLAGS: 00000246 ORIG_RAX: 0000= 000000000010 > [ 124.344942] RAX: ffffffffffffffda RBX: 000000000000ae80 RCX: 00007fbca= 75f7b1f > [ 124.344942] RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 000000000= 000000e > [ 124.344943] RBP: 000056351ba661d0 R08: 000056351a74dc48 R09: 000000000= 0000004 > [ 124.344943] R10: 004818cf4f129e11 R11: 0000000000000246 R12: 000000000= 0000000 > [ 124.344943] R13: 0000000000000000 R14: 00007fbca814f004 R15: 000000000= 0000000 > [ 124.344944] > [ 124.344945] ---[ end trace 0000000000000000 ]--- > > I don't do any bare metal testing for the tc-build known good revision > bumps, just QEMU tests with boot-utils. > > > Just for the records: > > You definitely need a pre-LLVM-15 toolchain + KCFI sanitizer patch? > > LLVM-14? > > The feature won't land in LLVM 14, so there is little point to > backporting and testing it on LLVM 14. This is a work in progress > feature so it has to target the main branch. I have fairly good coverage > of tip of tree locally and we have solid coverage through CI so we'll > know if something major happens, it should be pretty safe to test Sami's > series. > OK, no backport. > > > > Nathan has a i915 cfi patch in His personal kernel.org Git. > > > > Is this relevant to kcfi? > > > > > > It fixes a type mismatch, so in that sense it's relevant. > > > > > > > Here the link to patch "drm/i915: Fix CFI violation with show_dynamic_i= d()": > > > > https://git.kernel.org/pub/scm/linux/kernel/git/nathan/linux.git/commit= /?h=3Dsubmitted/i915-cfi-fix&id=3D53735be6dc53453fcfbac658e847b54360e73871 > > This is now in the i915 tree so that branch is going to disappear: > > https://cgit.freedesktop.org/drm/drm-intel/commit/?id=3D18fb42db05a0b93ab= 5dd5eab5315e50eaa3ca620 > Good to know. > > You say no need to build your kernel with LTO... > > That sounds good. > > Currently, I build my kernels with Clang-14 and CONFIG_LTO_CLANG_THIN= =3Dy. > > Does something speak against using CONFIG_LTO_CLANG_THIN=3Dy with KCFI = support? > > Build-time? > > Disc-usage? > > I wouldn't expect the build time or disk usage to significantly increase > with kCFI. I ran a quick benchmark with Arch Linux's configuration with > ThinLTO then ThinLTO + kCFI on an AMD EPYC 7513: > > Benchmark 1: ThinLTO > Time (abs =E2=89=A1): 166.036 s [User: 4687.951 s,= System: 1636.767 s] > > Benchmark 2: ThinLTO + kCFI > Time (abs =E2=89=A1): 168.739 s [User: 4682.020 s,= System: 1638.109 s] > > Summary > 'ThinLTO' ran > 1.02 times faster than 'ThinLTO + kCFI' > Thanks for your feedback. -Sedat-