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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 46B32C2D0B1 for ; Tue, 10 Dec 2019 06:31:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C82720637 for ; Tue, 10 Dec 2019 06:31:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="tQOU0We/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727174AbfLJGbj (ORCPT ); Tue, 10 Dec 2019 01:31:39 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:37198 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726819AbfLJGbj (ORCPT ); Tue, 10 Dec 2019 01:31:39 -0500 Received: by mail-qk1-f194.google.com with SMTP id m188so15535398qkc.4; Mon, 09 Dec 2019 22:31:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=9iJIcIsuvyaKuPCjR081dtZXW++oZ7hj1JifXMC1F5Q=; b=tQOU0We/iItFc8KG52IjN8yKcohDPXKl7RkDmRCr0JGDbwrqD739SRmZx4HGmE4duI J0XY+auZyepuaZAvGnbKX4M4p+YIq7Efv67rta+b3j+CyjCd0EZT1RCxCvBb+60Gb9Ck VLYhzDBNSrWqlwtit3o2w9SpLFsUDQIwDXzOQFY8+fcGXIIx6EA1NKNgIaDameUMHFSF ybar8inmlhJw+69UVINPdq2Q/SvHrsAqgN5f/8AuSxN7phLbDq8Ew0FR+p9hZiy1Bc+T dYDqmR70lInb3Av9ACUArifbaKLjrHCfEIaJ1aPxVQlPLmvw3vD97UJBHAGiOHoxK+n+ YHuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=9iJIcIsuvyaKuPCjR081dtZXW++oZ7hj1JifXMC1F5Q=; b=fO1Xnkb3jyU7aadqxhCI//KwNLph0gqb61NoWMxzazZCsjMWOVa4VzqZ1nrlrwViw7 OdJs4TRQzFnwm1MtPewLZv/OpTx68gcKjzHJZSSpLjAgo7Y98Nypz4a1Iu7fLwXgW5fN ZCKWGXxkQ4AR8Sx+sQRqE4OWvhrmsU8cRU6WTp0nfj33mh82FsPJNZoESxg6tooJh1P6 CNvr833IkJBlAKe411gaRGGcmRS+tPUY162YZqw4SV8nS3DlJzNdy6BOhBvdiPPUuYXL xnRrSW5e1rRim9wHoMWs5BLMbd3BN0uHzHMjIA4boYh6XNI6zO+34Jz1h5PH0cdAboyK g/uQ== X-Gm-Message-State: APjAAAU4FSDS3muOsEMLIyT47NXkrwwQ/mUSOwTWBFj5vLKDNrphiB4J 2pxfmHXiiRp/jbe5PvsrwW9ZTPPutjqDSA/CFJw= X-Google-Smtp-Source: APXvYqx3F+LQFuqQ022bdlz/MnN6T1zHXpSEHoXO3K+x8qu9cpOaRxwv+CVqGdE058LR7mSeqLWqg50/WQvlj45HWMQ= X-Received: by 2002:a37:9c0f:: with SMTP id f15mr31583276qke.297.1575959497981; Mon, 09 Dec 2019 22:31:37 -0800 (PST) MIME-Version: 1.0 References: <966fe384383bf23a0ee1efe8d7291c78a3fb832b.1575916815.git.paul.chaignon@gmail.com> In-Reply-To: From: =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= Date: Tue, 10 Dec 2019 07:31:26 +0100 Message-ID: Subject: Re: [PATCH bpf 1/2] bpf, riscv: limit to 33 tail calls To: Paul Chaignon Cc: Paul Burton , Mahshid Khezri , paul.chaignon@gmail.com, bpf , Netdev , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , linux-riscv@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 9 Dec 2019 at 20:57, Bj=C3=B6rn T=C3=B6pel = wrote: > > On Mon, 9 Dec 2019 at 19:52, Paul Chaignon wro= te: > > > > All BPF JIT compilers except RISC-V's and MIPS' enforce a 33-tail calls > > limit at runtime. In addition, a test was recently added, in tailcalls= 2, > > to check this limit. > > > > This patch updates the tail call limit in RISC-V's JIT compiler to allo= w > > 33 tail calls. I tested it using the above selftest on an emulated > > RISCV64. > > > > 33! ICK! ;-) Thanks for finding this! > > Acked-by: Bj=C3=B6rn T=C3=B6pel > ...and somewhat related; One of the tailcall tests fail due to missing far-branch support in the emitter. I'll address this in the v2 of the "far branch" series.