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 7D96EC433EF for ; Sat, 12 Feb 2022 02:40:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229806AbiBLCkj (ORCPT ); Fri, 11 Feb 2022 21:40:39 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:50348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229541AbiBLCkj (ORCPT ); Fri, 11 Feb 2022 21:40:39 -0500 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 68E522DABD; Fri, 11 Feb 2022 18:40:34 -0800 (PST) Received: from [10.130.0.135] (unknown [113.200.148.30]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9CxDuEaHgdi9rwAAA--.3561S3; Sat, 12 Feb 2022 10:40:27 +0800 (CST) Subject: Re: [PATCH bpf-next 2/2] bpf: Make BPF_JIT_DEFAULT_ON selectable in Kconfig To: Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh References: <1644569851-20859-1-git-send-email-yangtiezhu@loongson.cn> <1644569851-20859-3-git-send-email-yangtiezhu@loongson.cn> Cc: Xuefeng Li , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org From: Tiezhu Yang Message-ID: <65323db1-5fcb-21b3-2197-9bd6935bd96c@loongson.cn> Date: Sat, 12 Feb 2022 10:40:26 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID: AQAAf9CxDuEaHgdi9rwAAA--.3561S3 X-Coremail-Antispam: 1UD129KBjvJXoW7ury3Wr1fAF4xZr43KrWkCrg_yoW8GFyUpw 4Yq34Syrs7Krs3KFs7u3W7JF48Ww48Wr1UXFs8GrWUZas7CF92kr18K3Wqqa47Z34kX3Wj yFZ5ZFyDXa1Uu37anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUB014x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r1j6r1xM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVCY1x0267AKxVW8Jr 0_Cr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj 6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr 0_Gr1lF7xvr2IY64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8cxa n2IY04v7Mxk0xIA0c2IEe2xFo4CEbIxvr21lc2xSY4AK67AK6r4UMxAIw28IcxkI7VAKI4 8JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xv wVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjx v20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20E Y4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I 0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUO_MaUUUUU X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 02/11/2022 06:23 PM, Daniel Borkmann wrote: > On 2/11/22 9:57 AM, Tiezhu Yang wrote: >> Currently, it is not possible to set bpf_jit_enable to 1 by default >> and the users can change it to 0 or 2, it seems bad for some users, >> make BPF_JIT_DEFAULT_ON selectable to give them a chance. > > I'm not fully sure I follow the above, so you are saying that a kconfig of > !BPF_JIT_ALWAYS_ON and ARCH_WANT_DEFAULT_BPF_JIT, enables > BPF_JIT_DEFAULT_ON > however in such setting you are not able to reset bpf_jit_enable back to > 0 at > runtime? Oh, no. Sorry for the unclear description. currently, only x86, arm64 and s390 select ARCH_WANT_DEFAULT_BPF_JIT, the other archs do not select ARCH_WANT_DEFAULT_BPF_JIT. On the archs without ARCH_WANT_DEFAULT_BPF_JIT, if we want to set bpf_jit_enable to 1 by default, the only way is to enable CONFIG_BPF_JIT_ALWAYS_ON, then the users can not change it to 0 or 2, it seems bad for some users, we can select ARCH_WANT_DEFAULT_BPF_JIT for those archs if it is proper, but at least for now, make BPF_JIT_DEFAULT_ON selectable can give them a chance. Additionaly, with this patch, under !BPF_JIT_ALWAYS_ON, we can disable BPF_JIT_DEFAULT_ON on the archs with ARCH_WANT_DEFAULT_BPF_JIT when make menuconfig, it seems flexible for some developers. If you are OK, I will update the commit message and then send v2. Thanks, Tiezhu > > Thanks, > Daniel