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 4D811C4332F for ; Fri, 21 Oct 2022 15:18:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:CC:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=opeJTA47x0ccf3a78VXsLbUgpxZRHIEAPo0iLYPiVII=; b=zWsY/RRHdmTJ0J jTcsV0wsOw+uzs/JVvVA3JwnVPMTQGdZy0abGpaif/OBHoAglPyLelH9tcr9Xutx0NjEEwiWwbbq5 uAAq5ZqXWRT5ohAJQzdEyw8Nsb3m/vsPeiNU3f2gk0obeEz8IzEC0/Y7zk96ljirBSnp5JeqrmzcQ 2DWZ/fUmqYW0QeuVoW0OvBH9/on98YCSDHDDaZ3kh/OPax8qD6kY/3g/QChysLHfgcTnWue2Mk+fP x+TD5KZjcwgGgDp076buahcc0sPFpmH9VLSBpln3VzN1HsNEsfuuLQ5twVoDXb0tOMakzOwHulcWX irgviFjGwQ03AHECqgJw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oltmi-008f9B-9E; Fri, 21 Oct 2022 15:18:08 +0000 Received: from szxga03-in.huawei.com ([45.249.212.189]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oltme-008f7t-FC for linux-riscv@lists.infradead.org; Fri, 21 Oct 2022 15:18:06 +0000 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.56]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4Mv7Lr1JgvzJn3N; Fri, 21 Oct 2022 23:15:16 +0800 (CST) Received: from kwepemm600017.china.huawei.com (7.193.23.234) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 23:17:54 +0800 Received: from [10.174.179.234] (10.174.179.234) by kwepemm600017.china.huawei.com (7.193.23.234) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 23:17:53 +0800 Message-ID: <41608bda-3c20-060e-a9b4-afa2fe615b41@huawei.com> Date: Fri, 21 Oct 2022 23:17:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH] riscv: fix race when vmap stack overflow To: Guo Ren CC: Andrea Parri , Jisheng Zhang , Paul Walmsley , Palmer Dabbelt , Albert Ou , , References: <20221019154727.2395-1-jszhang@kernel.org> From: Tong Tiangen In-Reply-To: X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600017.china.huawei.com (7.193.23.234) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221021_081804_727476_A93F21E4 X-CRM114-Status: UNSURE ( 6.61 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org CgrlnKggMjAyMi8xMC8yMSAyMjo0MSwgR3VvIFJlbiDlhpnpgZM6Cj4gT24gRnJpLCBPY3QgMjEs IDIwMjIgYXQgOTo0NiBQTSBUb25nIFRpYW5nZW4gPHRvbmd0aWFuZ2VuQGh1YXdlaS5jb20+IHdy b3RlOgo+Pgo+Pgo+Pgo+PiDlnKggMjAyMi8xMC8yMSAyMToyMiwgQW5kcmVhIFBhcnJpIOWGmemB kzoKPj4+IEhpIFRvbmcsCj4+Pgo+Pj4+Pj4gSSB1c2UgYXRvbWljX3NldF9yZWxlYXNlIGhlcmUs IGJlY2F1c2UgSSBuZWVkIGVhcmxpZXIgbWVtb3J5Cj4+Pj4+PiBvcGVyYXRpb25zIGZpbmlzaGVk IHRvIG1ha2Ugc3VyZSB0aGUgc3AgaXMgcmVhZHkgdGhlbiBzZXQgdGhlIHNwaW4KPj4+Pj4+IGZs YWcuCj4+Pgo+Pj4+ICAgICAgIENvbnNpZGVyIHRoaXMgaW1wbGVtZW50YXRpb246KQo+Pj4+Cj4+ Pj4gICAgICAgc21wX3N0b3JlX21iKCZzcGluX3NoYWRvd19zdGFjaywgMCk7Cj4+Pgo+Pj4gc21w X3N0b3JlX21iKCkgaGFzICJXUklURV9PTkNFKCk7IHNtcF9tYigpIiBzZW1hbnRpY3M7IHNvIGl0 IGRvZXNuJ3QKPj4+IGd1YXJhbnRlZSB0aGF0IHRoZSBzdG9yZSB0byBzcGluX3NoYWRvd19zdGFj ayBpcyBvcmRlcmVkIGFmdGVyIHByb2dyYW0KPj4+IC1vcmRlciBlYXJsaWVyIG1lbW9yeSBhY2Nl c3Nlcy4KPj4+Cj4+PiAgICAgQW5kcmVhCj4+PiAuCj4+Cj4+IEhpIEFuZHJlYToKPj4KPj4gSUlV QywgdGhlIGVhcmxpZXIgbWVtb3J5IGFjY2VzcyBhbW9zd2FwLmFxcmwsIGhlcmUgLmFxcmwgZ3Vh cmFudGVlIGl0Lgo+PiBCdXQgYW55d2F5LCBjb25zaWRlciB3ZSBkb24ndCBjYXJlIGFib3V0IHBl cmZvcm1hbmNlIGhlcmUsIHVzaW5nCj4+IHNtcF9zdG9yZV9yZWxlYXNlKCkoYWRkIGJhcnJpZXIo KSkgc3VyZWx5IHJpZ2h0Lgo+IFdlIHVzZSBzbXBfc3RvcmVfcmVsZWFzZSgpIGlzIGZvcjoKPiAg ICAgICAgICAvL2xvYWQgcGVyLWNwdSBvdmVyZmxvdyBzdGFjawo+ICAgICAgICAgIFJFR19MIHNw LCAtOChzcCkKCk9oLCBtaXNzaW5nIHRoYXQsIHlvdSdyZSByaWdodC4gVGhpcyBndWFyYW50ZWUg dGhlIHNwaW4gZmxhZyBpcyBzZXQgCmFmdGVyIHRoZSBzcCBpcyB1c2VkLgoKPiAKPiBOb3QgYW1v c3dhcC4KPiAKPiBBY3R1YWxseSwgYW1vc3dhcC5hcXJsIGd1YXJhbnRlZXMgbm90aGluZyBiZWNh dXNlIGFsbCBpbnN0cnVjdGlvbnMKPiBkZXBlbmQgb24gdGhlIHNwIHJlZ2lzdGVyLgpyaWdodC4K ClRoYW5rcywKVG9uZy4KCj4gCj4+Cj4+IFRoYW5rcywKPj4gVG9uZy4KPiAKPiAKPiAKCl9fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LXJpc2N2IG1h aWxpbmcgbGlzdApsaW51eC1yaXNjdkBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5p bmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtcmlzY3YK 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D6B6C433FE for ; Fri, 21 Oct 2022 15:18:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230263AbiJUPSD (ORCPT ); Fri, 21 Oct 2022 11:18:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230041AbiJUPSB (ORCPT ); Fri, 21 Oct 2022 11:18:01 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ED5EA23E94 for ; Fri, 21 Oct 2022 08:17:59 -0700 (PDT) Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.56]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4Mv7Lr1JgvzJn3N; Fri, 21 Oct 2022 23:15:16 +0800 (CST) Received: from kwepemm600017.china.huawei.com (7.193.23.234) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 23:17:54 +0800 Received: from [10.174.179.234] (10.174.179.234) by kwepemm600017.china.huawei.com (7.193.23.234) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 23:17:53 +0800 Message-ID: <41608bda-3c20-060e-a9b4-afa2fe615b41@huawei.com> Date: Fri, 21 Oct 2022 23:17:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH] riscv: fix race when vmap stack overflow To: Guo Ren CC: Andrea Parri , Jisheng Zhang , Paul Walmsley , Palmer Dabbelt , Albert Ou , , References: <20221019154727.2395-1-jszhang@kernel.org> From: Tong Tiangen In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600017.china.huawei.com (7.193.23.234) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/10/21 22:41, Guo Ren 写道: > On Fri, Oct 21, 2022 at 9:46 PM Tong Tiangen wrote: >> >> >> >> 在 2022/10/21 21:22, Andrea Parri 写道: >>> Hi Tong, >>> >>>>>> I use atomic_set_release here, because I need earlier memory >>>>>> operations finished to make sure the sp is ready then set the spin >>>>>> flag. >>> >>>> Consider this implementation:) >>>> >>>> smp_store_mb(&spin_shadow_stack, 0); >>> >>> smp_store_mb() has "WRITE_ONCE(); smp_mb()" semantics; so it doesn't >>> guarantee that the store to spin_shadow_stack is ordered after program >>> -order earlier memory accesses. >>> >>> Andrea >>> . >> >> Hi Andrea: >> >> IIUC, the earlier memory access amoswap.aqrl, here .aqrl guarantee it. >> But anyway, consider we don't care about performance here, using >> smp_store_release()(add barrier()) surely right. > We use smp_store_release() is for: > //load per-cpu overflow stack > REG_L sp, -8(sp) Oh, missing that, you're right. This guarantee the spin flag is set after the sp is used. > > Not amoswap. > > Actually, amoswap.aqrl guarantees nothing because all instructions > depend on the sp register. right. Thanks, Tong. > >> >> Thanks, >> Tong. > > >