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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 9F5CBC636CA for ; Sat, 17 Jul 2021 01:42:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FB3E613EB for ; Sat, 17 Jul 2021 01:42:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238385AbhGQBpN (ORCPT ); Fri, 16 Jul 2021 21:45:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232010AbhGQBpM (ORCPT ); Fri, 16 Jul 2021 21:45:12 -0400 Received: from mail-yb1-xb33.google.com (mail-yb1-xb33.google.com [IPv6:2607:f8b0:4864:20::b33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB878C06175F; Fri, 16 Jul 2021 18:42:16 -0700 (PDT) Received: by mail-yb1-xb33.google.com with SMTP id r132so17816173yba.5; Fri, 16 Jul 2021 18:42:16 -0700 (PDT) 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; bh=XaI4Sevy4rmeomslDz9L3SbX88X7A1/njpOmXYRxXTc=; b=jyyAYR4I23gQbT9eNARXvU6NOhBWz/Z08wl1a0VkMB3sO/NHC6cxo0EWrVKQ351MGh um2j++Ml29AF41l+GreBSrSmJHqAlLPW+Z++R+LGdlgPLhly0d0gKqsrACdI0B5eXH5g Hg8PUaA4Z+lm3A0UmrQCeYoz432BF6krh58VEvmHbxopULXFLjHG3gXOv5oXCNB6OJyp ztlpgF2YdVIXJpV+LNe6LKxf5YS1KSCL1n168+x73VZC2njnXNgKikGlZd451waREvUo vPu+aX2LS+caQbTd8mzqMMmXYjqpWiB4uXQt51NanRHPYyezASCFPyXL1R7AvZt8xbp7 Y55A== 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; bh=XaI4Sevy4rmeomslDz9L3SbX88X7A1/njpOmXYRxXTc=; b=Yk7enSLOkAGk71EyDO+7HWWunnZzHJM85s/hYcAN5yXDdgwC/XU11gY4B4IfFAlvfe wEDM/CIKBnH0GZ1fm/JhTPDnwbR/NMTPslwr/YjVaf8T7skzX2JXe09p7RbW5h946pAB JcrmlmOtOFYmFdYnMRoAiayO2SlndC6lNZoPQyTsvvkT34Qmo3UnstIcgIuR8uOQ8ymo Yt7pgEfUzLO5pBvpBk8fdfSno8pBADg+/NBSDvwP/vK6SnbNTkg5d2PGeIH7YM8jE4fc rLgpm32f18xeI9W3IREFKqLyh3ONqyRtHK6zNI+3bQFxd+G4LPujkCkccYe8IKlalOpN NbKg== X-Gm-Message-State: AOAM531zEFnCu0PcBRdU4yvDozuX+4+T1QbxMBBleoMo32bZI1zUvJHy SE6/WvfomMfgj77ZoCv38tvVg/ITwCBAXYYDoiE= X-Google-Smtp-Source: ABdhPJxx2xJ5WMG214Nr6e1aeM0d5Af+dOrLYUU0iM17J5ilqI0VDPoZrUy8sw1XdEqYKP2AZoQ2nA7kxvOIRx69wWo= X-Received: by 2002:a25:3787:: with SMTP id e129mr15981599yba.459.1626486136165; Fri, 16 Jul 2021 18:42:16 -0700 (PDT) MIME-Version: 1.0 References: <20210714094400.396467-1-jolsa@kernel.org> <20210714094400.396467-8-jolsa@kernel.org> In-Reply-To: <20210714094400.396467-8-jolsa@kernel.org> From: Andrii Nakryiko Date: Fri, 16 Jul 2021 18:42:05 -0700 Message-ID: Subject: Re: [PATCHv4 bpf-next 7/8] libbpf: Allow specification of "kprobe/function+offset" To: Jiri Olsa Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Networking , bpf , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Masami Hiramatsu , Alan Maguire Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Jul 14, 2021 at 2:45 AM Jiri Olsa wrote: > > From: Alan Maguire > > kprobes can be placed on most instructions in a function, not > just entry, and ftrace and bpftrace support the function+offset > notification for probe placement. Adding parsing of func_name > into func+offset to bpf_program__attach_kprobe() allows the > user to specify > > SEC("kprobe/bpf_fentry_test5+0x6") > > ...for example, and the offset can be passed to perf_event_open_probe() > to support kprobe attachment. > > [jolsa: changed original code to use bpf_program__attach_kprobe_opts > and use dynamic allocation in sscanf] > > Signed-off-by: Alan Maguire > Signed-off-by: Jiri Olsa > --- > tools/lib/bpf/libbpf.c | 24 ++++++++++++++++++++++-- > 1 file changed, 22 insertions(+), 2 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index d93a6f9408d1..abe6d4842bb0 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -10348,6 +10348,7 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name, > > struct bpf_program_attach_kprobe_opts { > bool retprobe; > + unsigned long offset; > }; > > static struct bpf_link* > @@ -10360,7 +10361,7 @@ bpf_program__attach_kprobe_opts(struct bpf_program *prog, > int pfd, err; > > pfd = perf_event_open_probe(false /* uprobe */, opts->retprobe, func_name, > - 0 /* offset */, -1 /* pid */); > + opts->offset, -1 /* pid */); > if (pfd < 0) { > pr_warn("prog '%s': failed to create %s '%s' perf event: %s\n", > prog->name, opts->retprobe ? "kretprobe" : "kprobe", func_name, > @@ -10394,12 +10395,31 @@ static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec, > struct bpf_program *prog) > { > struct bpf_program_attach_kprobe_opts opts; > + unsigned long offset = 0; > + struct bpf_link *link; > const char *func_name; > + char *func; > + int n, err; > > func_name = prog->sec_name + sec->len; > opts.retprobe = strcmp(sec->sec, "kretprobe/") == 0; > > - return bpf_program__attach_kprobe_opts(prog, func_name, &opts); > + n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%lx", &func, &offset); could have used %li here to support both +0xabc and +123 forms > + if (n < 1) { > + err = -EINVAL; > + pr_warn("kprobe name is invalid: %s\n", func_name); > + return libbpf_err_ptr(err); > + } > + if (opts.retprobe && offset != 0) { > + err = -EINVAL; leaking func here > + pr_warn("kretprobes do not support offset specification\n"); > + return libbpf_err_ptr(err); > + } > + > + opts.offset = offset; > + link = bpf_program__attach_kprobe_opts(prog, func, &opts); > + free(func); > + return link; > } > > struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog, > -- > 2.31.1 >