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 581CAC433FE for ; Tue, 22 Mar 2022 05:18:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236696AbiCVFTp (ORCPT ); Tue, 22 Mar 2022 01:19:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236653AbiCVFTm (ORCPT ); Tue, 22 Mar 2022 01:19:42 -0400 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 214AEDFD4; Mon, 21 Mar 2022 22:18:16 -0700 (PDT) Received: by mail-pl1-x632.google.com with SMTP id c23so3436018plo.0; Mon, 21 Mar 2022 22:18:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=zj0a8iCuZT7u7wHmcYUPl4M0YrDNUxtwZIfHRK8GPWE=; b=AHoNe3gkppcRexArdqaUq+NlCuYltTSmaKojRagWIEWtbTeNCHms80tGfjxnt9vP+r ftlR4OCKctqj1EGDA29DYEa49j6rdmR9eA4xAROYK8sl+4MmeW/294dEmp8mFPkuxMCT b4nSYDuO9Lp6l/itrvwZ28sdcTmsgN0s4WIXV+TbT80apZZrTElIX+kgGNuXYvUXaPEf aM+APpTlV3nZ0IbxFi19kZqdGbcwmYYNJvMrJfi6yX7ZXzQnQBvgkXrA/MCVhtOcIogH CaeS5TrNQ/77CaKwcNxZUrW1wlQKaKzrPI8wbYI0kxWaPZ46u93cLSXvZ9ZGQMT23K9l GpZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=zj0a8iCuZT7u7wHmcYUPl4M0YrDNUxtwZIfHRK8GPWE=; b=rW9jRAPQGAlBIwwBnDigsCCrzQV5UEvDEbedlsrfphxiGtM58vGqM+03hZcCc/vqnz 746TjR1U++KOOKFh2K9RJHkFg4Z+byBHyWTKk9zvby4jB7/p7dYmkU7DbZjPskd27umr 627fKE4sCoKZSeafmVq3LM9+7c5S57TfSsr2WLJBQ/XqCP6x6CRT2VEddkSATAJVsTGn ABkm6YAVNTKT7iYKDNFGWmV0kgnZY5Bb1Z+0jp9iifNzIy9pUcwUwcIXy34m0OdDG2Da 9CSMOpz8pKittKmQzcP4oVUbR80+x0jbfoArjQ0srMOy1JKTCKEo4Qy+MljV63wz+Bzl AaMg== X-Gm-Message-State: AOAM531mWf2XNsxlmLXgkH9IqCtNQc+wzvhwmaL5frpKc3SaJv95qLfR KIhcrT8XEiHjwawBWWZDU4U1Osy3O3UubLv6X0k= X-Google-Smtp-Source: ABdhPJwKim2p5ZiUAZaMUgUUt1wpv67R6G9MYl5FgVyyk1dmMui6uNQHCidaquxZPb1zHgGIwWINlrAzApLooc/sG2o= X-Received: by 2002:a17:90b:1a81:b0:1bc:c3e5:27b2 with SMTP id ng1-20020a17090b1a8100b001bcc3e527b2mr2941997pjb.20.1647926295541; Mon, 21 Mar 2022 22:18:15 -0700 (PDT) MIME-Version: 1.0 References: <20220321224608.55798-1-alexei.starovoitov@gmail.com> <20220322113641.763885257f741ac5c0cb2c06@kernel.org> <20220322140537.d3f3fa3600d3b80c4f226e7c@kernel.org> In-Reply-To: <20220322140537.d3f3fa3600d3b80c4f226e7c@kernel.org> From: Alexei Starovoitov Date: Mon, 21 Mar 2022 22:18:04 -0700 Message-ID: Subject: Re: pull-request: bpf-next 2022-03-21 To: Masami Hiramatsu Cc: Linus Torvalds , David Miller , Daniel Borkmann , Peter Zijlstra , Steven Rostedt , Jakub Kicinski , Andrii Nakryiko , Stephen Rothwell , Netdev , bpf , Kernel Team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Mar 21, 2022 at 10:05 PM Masami Hiramatsu wrote: > > On Mon, 21 Mar 2022 21:35:55 -0700 > Alexei Starovoitov wrote: > > > On Mon, Mar 21, 2022 at 7:36 PM Masami Hiramatsu wrote: > > > > > > Hi Linus and Alexei, > > > > > > At first, sorry about this issue. I missed to Cc'ed to arch maintainers. > > > > > > On Mon, 21 Mar 2022 17:31:28 -0700 > > > Alexei Starovoitov wrote: > > > > > > > On Mon, Mar 21, 2022 at 4:59 PM Linus Torvalds > > > > wrote: > > > > > > > > > > On Mon, Mar 21, 2022 at 4:11 PM Alexei Starovoitov > > > > > wrote: > > > > > > > > > > > > Did you look at the code? > > > > > > In particular: > > > > > > https://lore.kernel.org/bpf/164735286243.1084943.7477055110527046644.stgit@devnote2/ > > > > > > > > > > > > it's a copy paste of arch/x86/kernel/kprobes/core.c > > > > > > > > > > > > How is it "bad architecture code" ? > > > > > > > > > > It's "bad architecture code" because the architecture maintainers have > > > > > made changes to check ENDBR in the meantime. > > > > > > > > > > So it used to be perfectly fine. It's not any longer - and the > > > > > architecture maintainers were clearly never actually cc'd on the > > > > > changes, so they didn't find out until much too late. > > > > > > Let me retry porting fprobe on top of ENDBR things and confirm with > > > arch maintainers. > > > > Just look at linux-next. > > objtool warning is the only issue. > > Actually, there are conflicts with arm tree and Rust tree too. > I found I missed the objtool annotation patch on IBT series and fixed it. 4 arch patches were reverted. > > > > > > > > > > Not denying that missing cc was an issue. > > > > > > > > We can drop just arch patches: > > > > rethook: x86: Add rethook x86 implementation > > > > arm64: rethook: Add arm64 rethook implementation > > > > powerpc: Add rethook support > > > > ARM: rethook: Add rethook arm implementation > > > > > > > > or everything including Jiri's work on top of it. > > > > Which would be a massive 27 patches. > > > > > > > > We'd prefer the former, of course. > > > > Later during the merge window we can add a single > > > > 'rethook: x86' patch that takes endbr into account, > > > > so that multi-kprobe feature will work on x86. > > > > For the next merge window we can add other archs. > > > > Would that work? > > > > > > BTW, As far as I can see the ENDBR things, the major issue on fprobe > > > is that the ftrace'ed ip address will be different from the symbol > > > address (even) on x86. That must be ensured to work before merge. > > > Let me check it on Linus's tree at first. > > > > That's not an issue. Peter tweaked ftrace logic and fprobe plugs > > into that. > > The fprobe/multi-kprobe works fine in linux-next. > > Yeah, I think fprobe should work because it uses > ftrace_location_range(func-entry, func-end) for non-x86 arch. > > > > > bpf selftest for multi kprobe needs this hack: > > diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi.c > > b/tools/testing/selftests/bpf/progs/kprobe_multi.c > > index af27d2c6fce8..530a64e2996a 100644 > > --- a/tools/testing/selftests/bpf/progs/kprobe_multi.c > > +++ b/tools/testing/selftests/bpf/progs/kprobe_multi.c > > @@ -45,7 +45,7 @@ static void kprobe_multi_check(void *ctx, bool is_return) > > __u64 addr = bpf_get_func_ip(ctx); > > > > #define SET(__var, __addr, __cookie) ({ \ > > - if (((const void *) addr == __addr) && \ > > + if (((const void *) addr == __addr + 4) && \ > > (!test_cookie || (cookie == __cookie))) \ > > Hmm, this is an ugly hack... You need to use actual ftrace addr, instead of > symbol addr. With IBT series, you can use ftrace_location(symbol-addr) to > get the ftrace-addr. (e.g. addr == ftrace_location(__addr) should work) It's a temporary hack. bpf prog cannot call an arbitrary function like ftrace_location. > > > > to pass when both CONFIG_FPROBE=y and CONFIG_X86_KERNEL_IBT=y. > > The test is too strict. It didn't account for the possibility of endbr. > > > > So I'm inclined to drop only 4 arch patches instead of the whole thing. > > OK, but it is hard to understand how it works without knowing rethook itself. > I would like to send whole v13 patch series to arch maintainers. fprobe is a glorified kprobe and pretty simple code by itself. It's too late for v13. Please send 'rethook: x86' patch only with endbr annotations and get it acked. The other archs will wait until the next merge window.