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 3A6A3C433EF for ; Mon, 11 Jul 2022 14:41:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229593AbiGKOlG (ORCPT ); Mon, 11 Jul 2022 10:41:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230246AbiGKOkv (ORCPT ); Mon, 11 Jul 2022 10:40:51 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEDDF4AD78; Mon, 11 Jul 2022 07:40:49 -0700 (PDT) Received: from kwepemi500013.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4LhRM80SM9zhYnh; Mon, 11 Jul 2022 22:38:12 +0800 (CST) Received: from [10.67.111.192] (10.67.111.192) by kwepemi500013.china.huawei.com (7.221.188.120) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 11 Jul 2022 22:40:43 +0800 Message-ID: <893b2d5f-16e9-0b1d-4ae6-8199e0f4ccf8@huawei.com> Date: Mon, 11 Jul 2022 22:40:42 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH bpf-next v7 4/4] bpf, arm64: bpf trampoline for arm64 Content-Language: en-US To: Jean-Philippe Brucker CC: , , , , Will Deacon , KP Singh , Mark Rutland , Catalin Marinas , Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , Zi Shen Lim , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , "David S . Miller" , Hideaki YOSHIFUJI , David Ahern , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H . Peter Anvin" , Jakub Kicinski , Jesper Dangaard Brouer , Russell King , James Morse , Hou Tao , Jason Wang References: <20220708093032.1832755-1-xukuohai@huawei.com> <20220708093032.1832755-5-xukuohai@huawei.com> <4852eba8-9fd0-6894-934c-ab89c0c7cea9@huawei.com> From: Xu Kuohai In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.111.192] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi500013.china.huawei.com (7.221.188.120) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 7/11/2022 10:37 PM, Jean-Philippe Brucker wrote: > On Mon, Jul 11, 2022 at 10:16:00PM +0800, Xu Kuohai wrote: >>>> + if (save_ret) >>>> + emit(A64_STR64I(p->jited ? r0 : A64_R(0), A64_SP, retval_off), >>>> + ctx); >>> >>> This should be only A64_R(0), not r0. r0 happens to equal A64_R(0) when >>> jitted due to the way build_epilogue() builds the function at the moment, >>> but we shouldn't rely on that. >>> >> >> looks like I misunderstood something, will change it to: >> >> /* store return value, which is held in x0 for interpreter and in >> * bpf register r0 for JIT, > > It's simpler than that: in both cases the return value is in x0 because > the function follows the procedure call standard. You could drop the > comment to avoid confusion and only do the change to A64_R(0) > OK, will send v9 since v8 was just sent > Thanks, > Jean > >> >> >> but r0 happens to equal x0 due to the >> * way build_epilogue() builds the JIT image. >> */ >> if (save_ret) >> emit(A64_STR64I(A64_R(0), A64_SP, retval_off), ctx); >> >>> Apart from that, for the series >>> >>> Reviewed-by: Jean-Philippe Brucker >>> >>> . > .