From patchwork Wed Jul 14 09:43:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Olsa X-Patchwork-Id: 477293 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 40ABAC11F66 for ; Wed, 14 Jul 2021 09:45:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DEBC613C5 for ; Wed, 14 Jul 2021 09:45:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238973AbhGNJry (ORCPT ); Wed, 14 Jul 2021 05:47:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46966 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238894AbhGNJry (ORCPT ); Wed, 14 Jul 2021 05:47:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626255902; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FDtmaDB4kqS4wOcww/6mdOWXrjUXzfE502+dL3peCCs=; b=Cea+fuGCc+pXw6u+5p1PMr/XMhYLmUEznsomEIdA5Ulr5Ld90fvAula9l6ENFls2ifzD2t dpuSvwUQ1D30NMz1PjSzMPYu9NdVAFkmT2yA2qqKU6Ozosqx4KjGtzOS3xqXSE1LoCJwT1 n+zQgiL8XfsNK095olNnPKOTsy7xSHk= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-125-67kW1tjlMLKJNfKbwt7Anw-1; Wed, 14 Jul 2021 05:45:01 -0400 X-MC-Unique: 67kW1tjlMLKJNfKbwt7Anw-1 Received: by mail-wr1-f72.google.com with SMTP id 32-20020adf82a30000b029013b21c75294so1203954wrc.14 for ; Wed, 14 Jul 2021 02:45:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=FDtmaDB4kqS4wOcww/6mdOWXrjUXzfE502+dL3peCCs=; b=C9qQYH06rRWpj4EG+NdhMhE/1EEVKOKCZKsIY0EuMP7pKCZ7IXFM2pjWQdtUp5zw1a Tpeq3gmXhIUV6BJeii5akKmpgGEWBPWPVXj9BQfd9OY7QhvDaY2r3Nq2R7KyT+tZ0GVl +pv3m0m+5EExR1dJmVRHiMPI2v7O6JinK8LvTPkaKthVF+e/OHQp4sVpUnI5GhgunNfP 0nr4gde1NHbwNYYIcYML5fyNpBc/3oiCYY+whVol/dH/PvtYLIH8wDsudGFXfOYD99k/ 3psoqzQmRftwQfWXCw5CwbW1H+X4URCaDIXRs0kYqHnA65tUhtwJHBkxjlr5jYCUpfbS Ekcg== X-Gm-Message-State: AOAM532FzxsuBJbC3FRQkMYeGEwO9ofVrplCauhi6BB+g+hXErZlL7bA iEG1Y3IDvD5P/h2fpnm9wHxM2mn5WKLSqcyCKOscgQeWCRxpjYloDe9Pn4noZPO9t2BS//1jBTS m89cjYVO6rg2uhsXs X-Received: by 2002:a5d:4c87:: with SMTP id z7mr11733054wrs.405.1626255900310; Wed, 14 Jul 2021 02:45:00 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxsX2PRzSqZC/fziGlaaGD8QqV4nNw/LBU9k/sV45C+e6beEAn1vHoY0xIAGZK32lnnmXF69w== X-Received: by 2002:a5d:4c87:: with SMTP id z7mr11733030wrs.405.1626255900114; Wed, 14 Jul 2021 02:45:00 -0700 (PDT) Received: from krava.redhat.com ([5.171.203.6]) by smtp.gmail.com with ESMTPSA id c12sm2108345wrr.90.2021.07.14.02.44.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jul 2021 02:44:59 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Masami Hiramatsu , Alan Maguire Subject: [PATCHv4 bpf-next 7/8] libbpf: Allow specification of "kprobe/function+offset" Date: Wed, 14 Jul 2021 11:43:59 +0200 Message-Id: <20210714094400.396467-8-jolsa@kernel.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210714094400.396467-1-jolsa@kernel.org> References: <20210714094400.396467-1-jolsa@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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); + 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; + 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,