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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 D865EC433E0 for ; Tue, 16 Feb 2021 11:26:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87C4964DF0 for ; Tue, 16 Feb 2021 11:26:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230038AbhBPL0Z (ORCPT ); Tue, 16 Feb 2021 06:26:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229703AbhBPL0W (ORCPT ); Tue, 16 Feb 2021 06:26:22 -0500 Received: from mail-qt1-x833.google.com (mail-qt1-x833.google.com [IPv6:2607:f8b0:4864:20::833]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FA45C061574 for ; Tue, 16 Feb 2021 03:25:41 -0800 (PST) Received: by mail-qt1-x833.google.com with SMTP id e11so6810242qtg.6 for ; Tue, 16 Feb 2021 03:25:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OpdMgD15nVOmxBqHmgQp5QV05JlNNLMOu1zTK5wectk=; b=BJlVkeg+KiYKigJv0dLocm82YBRds4Ze0jh0m/e1C4EWOqEFjdkvw84Sy7UTocnkSP 7JOD+hiV/AhOYlEahswG+drBrVpdQtpxC1+dlJNJxM4GLAWIVkzcn4FNpO6gfLpicS/C ltsSOxMyOOjQtylvk7nP1UVZyj/sTEh6vHZUpkYFV37aYfCTkpt+vy/gJS5dxcxuvqTt KB/tTD0d72xBCF68FnY8LslS+Vnlxl3OnQTVrVwDPMHJp1uxmg63+gfuHup/+mc2gQdi +tWjbjdhol1lp+S5UW5I+3ruWIP+E3U5gNtjhiqwYauzIl0h8Og4Gh+PKIJ8pEm25uOy 9Tog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OpdMgD15nVOmxBqHmgQp5QV05JlNNLMOu1zTK5wectk=; b=PYZosPLFEEuCya/btfofI1D9dimW1PebVSZohBtdmMsd3Z/MjygHZKnr562fenFd8Y +qXz5C9LFF3Cu5LK7bvh/gb9TTSHu2dbo/W5GqElB9zq3SU7I7zxBG4RzMInT0ZMrDbS I+56RyDilehCZy5dpdpw5q8xfLUjzy7x7Fwl8keVFLl6f7kZ4OfLUW0WoTNQyXgKG6VW urgi+pj+woxnosh8TKbuuCpJsIlBT/uKqoOxN/O+OPg7Bf0sgx+yYRLw7lBVDyv8tT7B cVqyTQY91FC+OUMt4ehjT40Fps2/9vadgMibkZ6XeB6e8vnx1jDqEKOoV2V1NR4opYBf Odmw== X-Gm-Message-State: AOAM53148oZ8uLPQMKtN64gFm+6ozy9pf4ak9zpyNkpOok1N6Rxhw7n/ kX7H851eY+HuHq9olDGXWnSywMrSit+eWxHC34g3JA== X-Google-Smtp-Source: ABdhPJwpW1GE+h0hCdOCxpmjTvpVz2L9jJNy9DdTONweY3+hgOg8KMJs8pE5xCd0rshQ3wiZ9zidYh4Xdpp/YWRYGQg= X-Received: by 2002:aed:3647:: with SMTP id e65mr9003272qtb.43.1613474740157; Tue, 16 Feb 2021 03:25:40 -0800 (PST) MIME-Version: 1.0 References: <20210118145310.crnqnh6kax5jqicj@distanz.ch> <6e9ee3a1-0e16-b1fc-a690-f1ca8e9823a5@ghiti.fr> In-Reply-To: From: Dmitry Vyukov Date: Tue, 16 Feb 2021 12:25:28 +0100 Message-ID: Subject: Re: riscv+KASAN does not boot To: Alex Ghiti Cc: Tobias Klauser , Albert Ou , Bjorn Topel , Palmer Dabbelt , LKML , nylon7@andestech.com, syzkaller , Andreas Schwab , Paul Walmsley , linux-riscv Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 16, 2021 at 12:17 PM Dmitry Vyukov wrote: > > On Fri, Jan 29, 2021 at 9:11 AM Dmitry Vyukov wrote: > > > I was fixing KASAN support for my sv48 patchset so I took a look at your > > > issue: I built a kernel on top of the branch riscv/fixes using > > > https://github.com/google/syzkaller/blob/269d24e857a757d09a898086a2fa6fa5d827c3e1/dashboard/config/linux/upstream-riscv64-kasan.config > > > and Buildroot 2020.11. I have the warnings regarding the use of > > > __virt_to_phys on wrong addresses (but that's normal since this function > > > is used in virt_addr_valid) but not the segfaults you describe. > > > > Hi Alex, > > > > Let me try to rebuild buildroot image. Maybe there was something wrong > > with my build, though, I did 'make clean' before doing. But at the > > same time it worked back in June... > > > > Re WARNINGs, they indicate kernel bugs. I am working on setting up a > > syzbot instance on riscv. If there a WARNING during boot then the > > kernel will be marked as broken. No further testing will happen. > > Is it a mis-use of WARN_ON? If so, could anybody please remove it or > > replace it with pr_err. > > > Hi, > > I've localized one issue with riscv/KASAN: > KASAN breaks VDSO and that's I think the root cause of weird faults I > saw earlier. The following patch fixes it. > Could somebody please upstream this fix? I don't know how to add/run > tests for this. > Thanks > > diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile > index 0cfd6da784f84..cf3a383c1799d 100644 > --- a/arch/riscv/kernel/vdso/Makefile > +++ b/arch/riscv/kernel/vdso/Makefile > @@ -35,6 +35,7 @@ CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os > # Disable gcov profiling for VDSO code > GCOV_PROFILE := n > KCOV_INSTRUMENT := n > +KASAN_SANITIZE := n > > # Force dependency > $(obj)/vdso.o: $(obj)/vdso.so Second issue I am seeing seems to be related to text segment size. I check out v5.11 and use this config: https://gist.github.com/dvyukov/6af25474d455437577a84213b0cc9178 Then trying to boot it using: QEMU emulator version 5.2.0 (Debian 1:5.2+dfsg-3) $ qemu-system-riscv64 -machine virt -smp 2 -m 4G ... It shows no output from the kernel whatsoever, even though I have earlycon and output shows very early with other configs. Kernel boots fine with defconfig and other smaller configs. If I enable KASAN_OUTLINE and CC_OPTIMIZE_FOR_SIZE, then this config also boots fine. Both of these options significantly reduce kernel size. However, I can also boot the kernel without these 2 configs, if I disable a whole lot of subsystem configs. This makes me think that there is an issue related to kernel size somewhere in qemu/bootloader/kernel bootstrap code. Does it make sense to you? Can somebody reproduce what I am seeing? Thanks