From nobody Mon Sep 15 23:10:48 2025 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 404BCC5479D for ; Mon, 9 Jan 2023 09:43:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233924AbjAIJno (ORCPT ); Mon, 9 Jan 2023 04:43:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231126AbjAIJni (ORCPT ); Mon, 9 Jan 2023 04:43:38 -0500 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 459AE1166; Mon, 9 Jan 2023 01:43:37 -0800 (PST) Received: by mail-pf1-x441.google.com with SMTP id c9so5674768pfj.5; Mon, 09 Jan 2023 01:43:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=001Ob8msDHYSJ4H6+BAMlx9g50lKceUKFFGpbLEZpGo=; b=eYDyOUaHHTHcueKILaSCYIfEciTW1pbEIlEDRLZdc9Ld42Fi2TMY/zFOiUclIOYxKE G3/Vdt+ep3en4CD1mF1VzlSKuo+Wh9HxpkvfD9ZxyfG2pUc4J+5QBSTBaqsv0puA5093 Qu9WF+zTU+e/LwbJOmsbes/c0YUi3NyINImEReG2kovWz6Wvfh0NfJoHTvzal72OKPmz 61xy1Eh8diyfbUQbVjVt0GljfAvO+xDSAPx4ODJJMHsDZZYuir01obzwfCabdj6JAyF/ WE5/hm2vf1huqC9lEba3pNmbEHqaTcg3Xwj/ovuUgF8h08W+FGa52hgsIdz66aXOjA+L EozA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=001Ob8msDHYSJ4H6+BAMlx9g50lKceUKFFGpbLEZpGo=; b=4ls3ZSJ89YHmWAiBGRBfdptqdECbkarkPa3NlYFCtG2ZZoK9v4YlSR9iShIrnrNq6I bG9bbKWiwnvSk4UkwK1gVR0E3sJDbc3a/3z/mmnzSbcGyUqPeu9D1BctoCxe3f0Fwi+C mvp+KHqRC1ox2K2QArXmboobn5qLbA0Kb+zzkua4KcgS+YtW5ms75bcvi4vw+dFPotzC VnoZQ0dKmfnrdHFDBnZ2KLhnIiOvR2sKKB7rUUmmqZ28DrcKXKeNXc8cQlD4NHJ+jq4g FMNS4xPwCl8EGa/KduPloI7Ti7ycPmA7DzNmlndKQ0WS7PgnB00oDnwgZiR4iW4omC1D SnDw== X-Gm-Message-State: AFqh2kpC8eJd7vRq+/rxBhO7ARCWWJG8AEbAXcSXuta/jxGfaAljlfoY kU3EaIL0HQ7HIZ04ys6Ukrw= X-Google-Smtp-Source: AMrXdXvDm89D+EhcP8RUapv3tOByyW5gaBVPaMYRnrQQnRB++bFW5P3AFGSMG+z2cmA4N6tdKEu4fQ== X-Received: by 2002:a05:6a00:414c:b0:581:7c46:debd with SMTP id bv12-20020a056a00414c00b005817c46debdmr44941706pfb.24.1673257416708; Mon, 09 Jan 2023 01:43:36 -0800 (PST) Received: from localhost.localdomain ([203.205.141.20]) by smtp.gmail.com with ESMTPSA id z8-20020aa79e48000000b00580849b55a2sm5629527pfq.26.2023.01.09.01.43.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Jan 2023 01:43:36 -0800 (PST) From: menglong8.dong@gmail.com X-Google-Original-From: imagedong@tencent.com To: daniel@iogearbox.net Cc: ast@kernel.org, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Menglong Dong Subject: [PATCH] libbpf: resolve kernel function name optimization for kprobe Date: Mon, 9 Jan 2023 17:42:47 +0800 Message-Id: <20230109094247.1464856-1-imagedong@tencent.com> X-Mailer: git-send-email 2.39.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Menglong Dong The function name in kernel may be changed by the compiler. For example, the function 'ip_rcv_core' can be compiled to 'ip_rcv_core.isra.0'. This kind optimization can happen in any kernel function. Therefor, we should conside this case. If we failed to attach kprobe with a '-ENOENT', then we can lookup the kallsyms and check if there is a similar function end with '.xxx', and retry. Signed-off-by: Menglong Dong --- tools/lib/bpf/libbpf.c | 37 ++++++++++++++++++++++++++++++++++++- 1 file changed, 36 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a5c67a3c93c5..fdfb1ca34ced 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10375,12 +10375,30 @@ bpf_program__attach_kprobe_multi_opts(const struc= t bpf_program *prog, return libbpf_err_ptr(err); } =20 +struct kprobe_resolve { + char pattern[128]; + char name[128]; +}; + +static int kprobe_kallsyms_cb(unsigned long long sym_addr, char sym_type, + const char *sym_name, void *ctx) +{ + struct kprobe_resolve *res =3D ctx; + + if (!glob_match(sym_name, res->pattern)) + return 0; + strcpy(res->name, sym_name); + return 1; +} + static int attach_kprobe(const struct bpf_program *prog, long cookie, stru= ct bpf_link **link) { DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts); + struct kprobe_resolve res =3D {}; unsigned long offset =3D 0; const char *func_name; char *func; + int err; int n; =20 *link =3D NULL; @@ -10408,8 +10426,25 @@ static int attach_kprobe(const struct bpf_program = *prog, long cookie, struct bpf =20 opts.offset =3D offset; *link =3D bpf_program__attach_kprobe_opts(prog, func, &opts); + err =3D libbpf_get_error(*link); + + if (!err || err !=3D -ENOENT) + goto out; + + sprintf(res.pattern, "%s.*", func); + if (!libbpf_kallsyms_parse(kprobe_kallsyms_cb, &res)) + goto out; + + pr_warn("prog '%s': trying to create %s '%s+0x%zx' perf event instead\n", + prog->name, opts.retprobe ? "kretprobe" : "kprobe", + res.name, offset); + + *link =3D bpf_program__attach_kprobe_opts(prog, res.name, &opts); + err =3D libbpf_get_error(*link); + +out: free(func); - return libbpf_get_error(*link); + return err; } =20 static int attach_ksyscall(const struct bpf_program *prog, long cookie, st= ruct bpf_link **link) --=20 2.39.0