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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8CA1BEB64DA for ; Fri, 21 Jul 2023 02:18:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D600828017F; Thu, 20 Jul 2023 22:18:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D104D28004C; Thu, 20 Jul 2023 22:18:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BD84B28017F; Thu, 20 Jul 2023 22:18:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id AD4B328004C for ; Thu, 20 Jul 2023 22:18:06 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 604DC120335 for ; Fri, 21 Jul 2023 02:18:06 +0000 (UTC) X-FDA: 81034008972.04.4A698D3 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf06.hostedemail.com (Postfix) with ESMTP id 5A686180005 for ; Fri, 21 Jul 2023 02:18:04 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=O0Q0sK61; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of chenhuacai@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=chenhuacai@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1689905884; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=2pwUjIqWGxpZikfBgBgd87CYfG2HI8r2bvuZKY9Dxs8=; b=tUiVLT+C+s4RnuPHQj8GVbLJ0gknEGF35//pa2eAxXfL8ZoaYPO3ueuRIkarDoVEIDq8If I79ch7VuB2LZ/MOc5+hI4K0lTRAhhpf3FrrhuN6uQBnWmCDXTK7eGiHF9cvWLIgROofM12 v2/lT7FerdOx8WwLjagB8PpqfaACmX4= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=O0Q0sK61; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of chenhuacai@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=chenhuacai@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1689905884; a=rsa-sha256; cv=none; b=lORonFC3r1jg/wAAvYKcC/fgFxgCHar5RV1s0UdDdybPpDTq0gmFBqS8/NmvUUsqSSW9F7 8UneGDZPYrfhLz/WBqHz/oBHogYaABbyqOcQDBegVXh4rAWsAq0maCG4gEuhDhn8KrilKN q/IeNr/pdShSzVkwG7FPlwkOkqwDPrw= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6175E61CCF for ; Fri, 21 Jul 2023 02:18:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C11F7C433C7 for ; Fri, 21 Jul 2023 02:18:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689905882; bh=OFb9g6ZVz3kHcyjKj3uKCp4jraM5kd5rjK5FLNo6yJ4=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=O0Q0sK61rJcCbVji3lKH374hydIH6HStbBIjK+MKTn7trgsFbTJDqvifhwZyXJ584 chhr/pJ9hOixkEe32ae8ZLvdL9LA8j2VJKZtBOqI8cwRiDoz4Gu2gnCnlQ3zbO5HWk dGQ5lH/8MKTc7TKZK+Tvk44SQeNEnP0OSx6GCW3fMBRf2Ue93ipXiF0YA3aY2IN6Wx YEXMG1aByjfar6VcjryIYuhCFfEm42BdYa1VWXqma8jXcs7145Bgh3UyJq9XnFxA/A PvSQ2N+F+wYSqF2n66CSzSeYsYu8HQkXvi1Vb98pmJHnVd4nGvx/6VeiFUgO9wF+sm 6rTcNIs2OT5mA== Received: by mail-lf1-f50.google.com with SMTP id 2adb3069b0e04-4fb7dc16ff0so2316010e87.2 for ; Thu, 20 Jul 2023 19:18:02 -0700 (PDT) X-Gm-Message-State: ABy/qLbmvvlYcat7oxX8QLOKPsimCvTKjGOBi4OKGNg5rmCt6Nzn9P2v 0DTiH7L65lrltDmhLb+k4nsme3rqZdYzQAd1ud8= X-Google-Smtp-Source: APBJJlGc1+79N7V0w84IVuUkC4WXeA0CcUQVXLLZetgREYIAGHNgmm4D7lGNmacSiRuRjfTUgM5z/XAR5H45yY9knms= X-Received: by 2002:a05:6512:2826:b0:4fb:76f7:fde9 with SMTP id cf38-20020a056512282600b004fb76f7fde9mr369862lfb.30.1689905880781; Thu, 20 Jul 2023 19:18:00 -0700 (PDT) MIME-Version: 1.0 References: <20230719082732.2189747-1-lienze@kylinos.cn> <20230719082732.2189747-3-lienze@kylinos.cn> <87tttyf2zj.fsf@kylinos.cn> In-Reply-To: <87tttyf2zj.fsf@kylinos.cn> From: Huacai Chen Date: Fri, 21 Jul 2023 10:17:48 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 2/4] LoongArch: Get stack without NMI when providing regs parameter To: Enze Li Cc: kernel@xen0n.name, loongarch@lists.linux.dev, glider@google.com, elver@google.com, akpm@linux-foundation.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, zhangqing@loongson.cn, yangtiezhu@loongson.cn, dvyukov@google.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5A686180005 X-Stat-Signature: hz3wr5sknzxdiy8shxdgn6ahtg1f1rx7 X-Rspam-User: X-HE-Tag: 1689905884-523735 X-HE-Meta: U2FsdGVkX1+AuF1lcWrXeMmNT0X6fubo1N2k+PqCjWbN6SWYzwfXYjlllc+Mu71o/44HmreIl/swS73lwdZire5Nyaw3iduxkAKVekoA1wtl1JtVzZmuWEGkjmsPA7pJnGajW/3tI3q7ct2wwNrnU3bl3EV6vJIcp5rYVplFz4t07SIYugiw8kPlBbUGSQKJXo5wBEPvSsHTVIomaPwVKFojZ0vo42v9Zg2p+Q2X0OZNdvhn8H1Tgn+CmfaUZRDQSqBaSuwUHPYQrOGn1eMFA5sBheGFfj5v3iod1/7sXt7kfjSahkXMVsuT+O29ES2s4n7vx0fKR+CiWkrZTCqADFD1Y1+mO2krv4mobEsbs3+zh3VW2TrlXRFF3tHoL2IvyrFated4MAlhiqGU7HtFEHU3J5sqpwI/l3pXYkCLt21akuP8W92EMydC1p+DpiY1CSnsZW41OfPxbtW9Hr5LENmTScFugNtlln4hpbCgBsSH3WHfxxDmbaaSR3U/CIXQX0Q6M+dAZ17P1F0wRmTlk740lvW15ZFEHhV2Nu3Z7C89rwDlpHUolrlUg9sNIhox7YSLzGIdV9zO0exHeF+k4SHYpmZi2Wsi6CR13O7xl45fhoRJ2STBhS1dtxxgHTUZV9Q+26lMmnvRcXvVZhOZNFTSDid3YGgsBt7u02+AI6Tkt4/KHsw9yxeeVUHYVIwQQO+RBGEbE1JsNtJdBXTemVnxao2mnWbyFf8cvYYoL/ah8Gko4AA+4J5Hy3EkZHApwrMT61qzb3t7xkSu2oGg/cfh4M28W80owdgaDstr+fLYFjJ78zwvRoEu4s1pLWmMS8sBUvCwlg4mXQcautPRJOPmhCoFkOPmdBmy/wOWOF8qv+33xck48ID5mQxbVBqLXHbr9KPTdI77N7wKKF29UEztbrNGXzit6/1Y4VtSHFQpRfso0XjDBpdAKwIziydhJBTqdo8SuhZzpRTIXmu YsqQ9Isq xsrL8n9tFTmqFkLMPpGChgcTNUrZ2KjJqX63SIw4eOAW7VcdvMwfkPobHZ7KQKSSHT0Cm2Yl5E5Wfz1Mv1UHKZ8h61Qzc9gOV58FBx5E5AKhwXgIXSxy99WtEVYLTYCk1P0Gljai4w2VOYbzFUhAeHI2Hla3tzJIgqedFRray96rFLovEsZGbkAdyzn5fnkErnL8glsxoXKn7xxcq/qLAbeY3V18xzNNXaa7vJkr+8RlxAO7JLkbxF6sUL3auCeNCmE6Tf9/jYc7GruHCd4KFfTTN8M/cjMOmiwuYsMEWlzibQrXNUjjAP1gLtlHC9js4KICP X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jul 21, 2023 at 9:50=E2=80=AFAM Enze Li wrote: > > Hi Huacai, > > Thanks for your review. > > On Wed, Jul 19 2023 at 11:17:14 PM +0800, Huacai Chen wrote: > > > Hi, Enze, > > > > On Wed, Jul 19, 2023 at 4:34=E2=80=AFPM Enze Li wro= te: > >> > >> Currently, executing arch_stack_walk can only get the full stack > >> information including NMI. This is because the implementation > >> of arch_stack_walk is forced to ignore the information passed by the > >> regs parameter and use the current stack information instead. > >> > >> For some detection systems like KFENCE, only partial stack information > >> is needed. In particular, the stack frame where the interrupt occurre= d. > >> > >> To support KFENCE, this patch modifies the implementation of the > >> arch_stack_walk function so that if this function is called with the > >> regs argument passed, it retains all the stack information in regs and > >> uses it to provide accurate information. > >> > >> Before the patch applied, I get, > >> [ 1.531195 ] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > >> [ 1.531442 ] BUG: KFENCE: out-of-bounds read in stack_trace_save_re= gs+0x48/0x6c > >> [ 1.531442 ] > >> [ 1.531900 ] Out-of-bounds read at 0xffff800012267fff (1B left of k= fence-#12): > >> [ 1.532046 ] stack_trace_save_regs+0x48/0x6c > >> [ 1.532169 ] kfence_report_error+0xa4/0x528 > >> [ 1.532276 ] kfence_handle_page_fault+0x124/0x270 > >> [ 1.532388 ] no_context+0x50/0x94 > >> [ 1.532453 ] do_page_fault+0x1a8/0x36c > >> [ 1.532524 ] tlb_do_page_fault_0+0x118/0x1b4 > >> [ 1.532623 ] test_out_of_bounds_read+0xa0/0x1d8 > >> [ 1.532745 ] kunit_generic_run_threadfn_adapter+0x1c/0x28 > >> [ 1.532854 ] kthread+0x124/0x130 > >> [ 1.532922 ] ret_from_kernel_thread+0xc/0xa4 > >> > >> > >> With this patch applied, I get the correct stack information. > >> [ 1.320220 ] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > >> [ 1.320401 ] BUG: KFENCE: out-of-bounds read in test_out_of_bounds_= read+0xa8/0x1d8 > >> [ 1.320401 ] > >> [ 1.320898 ] Out-of-bounds read at 0xffff800012257fff (1B left of k= fence-#10): > >> [ 1.321134 ] test_out_of_bounds_read+0xa8/0x1d8 > >> [ 1.321264 ] kunit_generic_run_threadfn_adapter+0x1c/0x28 > >> [ 1.321392 ] kthread+0x124/0x130 > >> [ 1.321459 ] ret_from_kernel_thread+0xc/0xa4 > >> > >> > >> Signed-off-by: Enze Li > >> --- > >> arch/loongarch/kernel/stacktrace.c | 16 ++++++++++------ > >> 1 file changed, 10 insertions(+), 6 deletions(-) > >> > >> diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kerne= l/stacktrace.c > >> index 2463d2fea21f..21f60811e26f 100644 > >> --- a/arch/loongarch/kernel/stacktrace.c > >> +++ b/arch/loongarch/kernel/stacktrace.c > >> @@ -18,16 +18,20 @@ void arch_stack_walk(stack_trace_consume_fn consum= e_entry, void *cookie, > >> struct pt_regs dummyregs; > >> struct unwind_state state; > >> > >> - regs =3D &dummyregs; > >> - > >> if (task =3D=3D current) { > >> - regs->regs[3] =3D (unsigned long)__builtin_frame_addre= ss(0); > >> - regs->csr_era =3D (unsigned long)__builtin_return_addr= ess(0); > >> + if (regs) > >> + memcpy(&dummyregs, regs, sizeof(*regs)); > >> + else { > >> + dummyregs.regs[3] =3D (unsigned long)__builtin= _frame_address(0); > >> + dummyregs.csr_era =3D (unsigned long)__builtin= _return_address(0); > >> + } > >> } else { > > When "task !=3D current", we don't need to handle the "regs !=3D NULL" = case? > > > > Huacai > > > > So far, I have not encountered this situation. I'm not sure what > problems would arise from extending the modifications with "task !=3D > current". > > However, these modifications now are sufficient for the KFENCE > system. I would suggest that we don't modify other parts until we > encounter problems. This way, we can forge ahead steadily. I don't think so. In my opinion, "partial stack information" is a clear requirement, whether the task is current or not. So, if the input regs is not NULL, we should always memcpy(&dummyregs, regs, sizeof(*regs)); Or we may listen to Tiezhu's idea? Huacai > > Best Regards, > Enze > > >> - regs->regs[3] =3D thread_saved_fp(task); > >> - regs->csr_era =3D thread_saved_ra(task); > >> + dummyregs.regs[3] =3D thread_saved_fp(task); > >> + dummyregs.csr_era =3D thread_saved_ra(task); > >> } > >> > >> + regs =3D &dummyregs; > >> + > >> regs->regs[1] =3D 0; > >> for (unwind_start(&state, task, regs); > >> !unwind_done(&state) && !unwind_error(&state); unwind_nex= t_frame(&state)) { > >> -- > >> 2.34.1 > >> > >>