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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 122E8C11F64 for ; Mon, 28 Jun 2021 23:20:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ED50061CFC for ; Mon, 28 Jun 2021 23:20:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237102AbhF1XXE (ORCPT ); Mon, 28 Jun 2021 19:23:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234600AbhF1XWx (ORCPT ); Mon, 28 Jun 2021 19:22:53 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6257C061574 for ; Mon, 28 Jun 2021 16:20:27 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id z4so525391plg.8 for ; Mon, 28 Jun 2021 16:20:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=mRUbf3KJA2d64vKTZ/FyrTly1jL2s60EVp6ODRb0q9Q=; b=uXOWQ+eB18empgtJVMYzzMwdBwxLEMq2W32P0eBwWcEwSQUzia+V/S8UP6EgC3kBJ1 xxY9Mu0kbipBr7023piq8gZS7lglwBz6MHTSf8NQepDqOgQJUuKVFOEOFFz5k3aEVvR6 fS2z13O8CYBnqa5ci3RlGU9XLg18OXDHkCSYPrcTBTTaJ68T89J+5KTaxLJbeq6QM8M5 2lqzzHj9pUqDuJA3Yvkg9y9NVyXc0emYOOftoXBM86l0xJnmqWg6S4JtCKpl6LrTsIBa CjrQxMi4nA9a4zHjfMNq7CpYcwLuCOFfSzRlOjWF3SvVbw/ty0IReHyA1kWprbVUdWbj FU8g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=mRUbf3KJA2d64vKTZ/FyrTly1jL2s60EVp6ODRb0q9Q=; b=NTzdnNNX1vSqC+08fagzFXaveWHgrgJanu5HgMgNFpE3XfoEv1J7vMyoZ6RoBnSQtV VglyVLQl5O5io34Pl51bY9xNC/teuuPGnZ71HFRYw6ES4oaYvTPNHIVQ3HzrPP+iYWTx jwnpT9QrgfrrWT0pc9CnAPGW7X9yLpttswNNI4aaXimYDe0xaJMZNlorHaf+EQcrV8PU 3ALUjJHeKPN+ifZTsIXocf4BVCROkIq3CWStcjGYkHECldwejappAtOmMS+vcU01IIRg pDUN5yJSBAKh1rT8wurVepSrJy9SmSZwouTcC22yVPy8X+kyVxt4kdLQyI9e7/Bhm/Cm 7AFw== X-Gm-Message-State: AOAM530f57MNRC8DPMyJrvzBlxaWOCUoju0vySpuTyVVqsI+28kMMKUW xwWeD7ePPSjDKp0zipJuwU0= X-Google-Smtp-Source: ABdhPJysNaqjkYn1H0Iwdtijp2+qlaPNrYNNPvI5VF7m7NFdeCk2r71nY6ITTL1zQwSyEQPKlBHEzg== X-Received: by 2002:a17:90a:a29:: with SMTP id o38mr27617803pjo.228.1624922427442; Mon, 28 Jun 2021 16:20:27 -0700 (PDT) Received: from mail.google.com ([141.164.41.4]) by smtp.gmail.com with ESMTPSA id i27sm15304030pgl.78.2021.06.28.16.20.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Jun 2021 16:20:26 -0700 (PDT) Date: Tue, 29 Jun 2021 07:20:23 +0800 From: Changbin Du To: Jisheng Zhang Cc: Changbin Du , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] riscv: stacktrace: fix dump_backtrace/walk_stackframe with NULL task Message-ID: <20210628232023.l6o7k5eetvvz2ysm@mail.google.com> References: <20210627092659.46193-1-changbin.du@gmail.com> <20210628134404.4c470112@xhacker.debian> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210628134404.4c470112@xhacker.debian> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 28, 2021 at 01:44:04PM +0800, Jisheng Zhang wrote: > On Sun, 27 Jun 2021 17:26:59 +0800 > Changbin Du wrote: > > > > > > > > Some places try to show backtrace with NULL task, and expect the task is > > 'current'. For example, dump_stack()->show_stack(NULL,...). So the > > stacktrace code should take care of this case. > > I fixed this issue one week ago: > > http://lists.infradead.org/pipermail/linux-riscv/2021-June/007258.html > Good to know. Thanks! > > > > Here is an oops caused by this issue when accessing the NULL task. > > > > [ 15.180813] Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance. > > [ 15.182382] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc7-00111-g625acffd7ae2-dirty #18 > > [ 15.183431] Hardware name: riscv-virtio,qemu (DT) > > [ 15.184253] Call Trace: > > [ 15.223617] Unable to handle kernel paging request at virtual address 0000000000001590 > > [ 15.267378] Oops [#1] > > [ 15.268215] Modules linked in: > > [ 15.272027] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc7-00111-g625acffd7ae2-dirty #18 > > [ 15.273997] Hardware name: riscv-virtio,qemu (DT) > > [ 15.275134] epc : walk_stackframe+0xc4/0xdc > > [ 15.280146] ra : dump_backtrace+0x30/0x38 > > [ 15.280799] epc : ffffffff8000597e ra : ffffffff800059c6 sp : ffffffe002383d60 > > [ 15.281622] gp : ffffffff8179ad18 tp : ffffffe002378000 t0 : ffffffff81bc1a3f > > [ 15.282574] t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffffe002383dc0 > > [ 15.283782] s1 : ffffffff812b7d18 a0 : 0000000000001000 a1 : 0000000000000000 > > [ 15.285115] a2 : ffffffff807ec668 a3 : ffffffff812b7d18 a4 : c76c00cabf08b500 > > [ 15.286213] a5 : 0000000000001000 a6 : 000000001a9ef260 a7 : 0000000000000000 > > [ 15.287317] s2 : 0000000000000000 s3 : 0000000000000000 s4 : 0000000000000000 > > [ 15.288323] s5 : ffffffff807ec668 s6 : ffffffff812b7d18 s7 : 0000000000000000 > > [ 15.289530] s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000 > > [ 15.290995] s11: 0000000000000000 t3 : 0000000000000001 t4 : 0000000000000000 > > [ 15.292465] t5 : 206f74206e6f6974 t6 : ffffffe002383b28 > > [ 15.293859] status: 0000000000000100 badaddr: 0000000000001590 cause: 000000000000000d > > [ 15.296035] [] walk_stackframe+0xc4/0xdc > > [ 15.297342] [] dump_backtrace+0x30/0x38 > > [ 15.298333] [] show_stack+0x40/0x4c > > [ 15.299765] [] dump_stack+0x7c/0x96 > > [ 15.300553] [] panic+0x118/0x300 > > [ 15.301147] [] kernel_init+0x12c/0x138 > > [ 15.302056] [] ret_from_exception+0x0/0xc > > [ 15.338628] ---[ end trace 0a3fa0cc7f3393cd ]--- > > [ 15.339919] note: swapper/0[1] exited with preempt_count 1 > > [ 15.341995] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > > [ 15.343889] SMP: stopping secondary CPUs > > [ 16.802836] SMP: failed to stop secondary CPUs 0-3 > > [ 16.806264] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--- > > > > This patch fixes it by setting the task to current if it's NULL before > > accessing it. > > > > Signed-off-by: Changbin Du > > Fixes: 5d8544e2d0 ("RISC-V: Generic library routines and assembly") > > Hmm, this fixes tag should be > Fixes: eac2f3059e02 ("riscv: stacktrace: fix the riscv stacktrace when CONFIG_FRAME_POINTER enabled" > > > > --- > > arch/riscv/kernel/stacktrace.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c > > index bde85fc53357..788b65eba965 100644 > > --- a/arch/riscv/kernel/stacktrace.c > > +++ b/arch/riscv/kernel/stacktrace.c > > @@ -23,6 +23,9 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, > > { > > unsigned long fp, sp, pc; > > > > + if (!task) > > + task = current; > > + > > if (regs) { > > fp = frame_pointer(regs); > > sp = user_stack_pointer(regs); > > @@ -73,6 +76,9 @@ void notrace walk_stackframe(struct task_struct *task, > > unsigned long sp, pc; > > unsigned long *ksp; > > > > + if (!task) > > + task = current; > > + > > if (regs) { > > sp = user_stack_pointer(regs); > > pc = instruction_pointer(regs); > > -- > > 2.30.2 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > -- Cheers, Changbin Du