From patchwork Tue Jan 23 19:54:49 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Rogers X-Patchwork-Id: 13528111 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 342E3823D4 for ; Tue, 23 Jan 2024 19:54:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706039695; cv=none; b=sX+7NphsfazfnrseLVeHELiQ3tlyTkWho1u74Og0Yh+vCAC8hO2xJ3wp1hpDgVBn/vWzkeS8M+NEhXHUK+h5gDdnyCB+cLTlAsse5y/q/BerNkLa6A1EatNxDHCP+ARhRVBl9ioGSBo1KB1ht6s2EGVmI8zi9n3VltDjZjj2a/A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706039695; c=relaxed/simple; bh=HsE80BSDf3dP7dp3QIx/zCpzJs9ZWELkp2KEUKffScw=; h=Date:Message-Id:Mime-Version:Subject:From:To:Cc:Content-Type; b=f4qtfN/PCB+R3XrJz8we4IVT535Yt/TzCqLKWCmYxP5Zl+YncbYll7ui+ZBVvLwOjE/N27/HlDoQ55nSVCkSayoM8nBQ/OTVyBPbej/IjBiKGrs7s/TvUxgjxC2Ep8AKjCmlpkHna0njzqlsxuGQm9k+BP+IBXwj+tJZPjpLJ5Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=ym7vxU2D; arc=none smtp.client-ip=209.85.219.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ym7vxU2D" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-dbdb46770d7so6719769276.1 for ; Tue, 23 Jan 2024 11:54:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1706039693; x=1706644493; darn=vger.kernel.org; h=cc:to:from:subject:mime-version:message-id:date:from:to:cc:subject :date:message-id:reply-to; bh=JhpX9hlE2Pci6VpOvhAwdkAo2oTmPgpj24BygTfmpHM=; b=ym7vxU2DD1SekWj+p8oY6xNLs/mGDhMzcWceyyPljE/L5dBzR3Ozz/7uTTRAssq2Ve GtsakM9yZA2SZT7QwhCU8FRiDrS3ti6mZOslkbfqiqXPEqxWy8a9AQ5O8+O9vpLVXbPe lT1WJGi1dmDhZlwVd/coY8xEhilGwIf1w0HPE6GfuvgGXTbUW2hbba1Ar0ZfB9YLkDSl n2Dsx8E2AC1p6hmv9PhCproTCAenKW5egLVixaaGuG7Ht8F5ac9a9lhTQ9SENH/6Et7Y IBtttE7yCsRNoZad5LGerQ7nYSH/sll+Rzp0GHVDvfcH+vtCxcg+ttNK7A/zbDsbv8Y4 6O5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706039693; x=1706644493; h=cc:to:from:subject:mime-version:message-id:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=JhpX9hlE2Pci6VpOvhAwdkAo2oTmPgpj24BygTfmpHM=; b=JJOgLHWknMO4pQtyb134XuFrtpaRznjUoSyWAU2Z9T8InSjYlb/mbFXUQUvHJIwBb1 ZxAtdCP8+63wbAB1QcV19bRaE2pyJQIuMLtZ+sw/n3h7/Ea1twNp1GLAsYIR7fcF/j2d adesnJ8880ySLp0MzVqPodtZPLun3OvOQfxM3dYRpxja2eqwc8VhC/16pDl0F4pQtPuz JrtAlMN1dp7KN7ADZe+Hnu+vZN173DKPIv1r0y+/1oFokeFMUVUX8MGkZZfbD0ewHAWJ Z9fzfYeiB309w2YM7TsTC1Q+3CYSHfrjzVvoIAQS5+bJ3FxaMpS0NfDXw9x9WzNHJeV6 TICg== X-Gm-Message-State: AOJu0YwvxOxSFBm0idziU260LqmJdFdzPgOfWt0pvZ1CWkK3FzHNVfyp yyUjUVAh/v4oy3/H3WdFXvrBR1MMJNz13h85Wwwz5lYj5BBTW2dpqIoM78ZkotlXdfX4Y0oD4dy StH5ggw== X-Google-Smtp-Source: AGHT+IGAmS9Av+aJTpDnAXc+u2Z8XPgjzx85lccoKtnPOVvsWpoyTGg+NCMM7VkLAT8XQa12c5Cht0GU8BAs X-Received: from irogers.svl.corp.google.com ([2620:15c:2a3:200:b37:2438:2b2f:daae]) (user=irogers job=sendgmr) by 2002:a05:6902:1b12:b0:db5:4766:e363 with SMTP id eh18-20020a0569021b1200b00db54766e363mr2807736ybb.6.1706039693262; Tue, 23 Jan 2024 11:54:53 -0800 (PST) Date: Tue, 23 Jan 2024 11:54:49 -0800 Message-Id: <20240123195449.1303643-1-irogers@google.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Subject: [PATCH v1] libbpf: Add some details for BTF parsing failures From: Ian Rogers To: Alan Maguire , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Ian Rogers X-Patchwork-Delegate: bpf@iogearbox.net As CONFIG_DEBUG_INFO_BTF is default off the existing "failed to find valid kernel BTF" message makes diagnosing the kernel build issue some what cryptic. Add a little more detail with the hope of helping users. Before: ``` libbpf: failed to find valid kernel BTF libbpf: Error loading vmlinux BTF: -3 libbpf: failed to load object 'lock_contention_bpf' libbpf: failed to load BPF skeleton 'lock_contention_bpf': -3 ``` After no access: ``` libbpf: failed to find a kernel (typically /sys/kernel/btf/vmlinux) for BTF data libbpf: Error loading vmlinux BTF: -3 libbpf: failed to load object 'lock_contention_bpf' libbpf: failed to load BPF skeleton 'lock_contention_bpf': -3 ``` After no BTF: ``` libbpf: failed to find BTF in kernel (was CONFIG_DEBUG_INFO_BTF enabled?) libbpf: Error loading vmlinux BTF: -3 libbpf: failed to load object 'lock_contention_bpf' libbpf: failed to load BPF skeleton 'lock_contention_bpf': -3 ``` Closes: https://lore.kernel.org/bpf/CAP-5=fU+DN_+Y=Y4gtELUsJxKNDDCOvJzPHvjUVaUoeFAzNnig@mail.gmail.com/ Signed-off-by: Ian Rogers --- tools/lib/bpf/btf.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index ee95fd379d4d..505c0fb2d1ed 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -4942,6 +4942,7 @@ struct btf *btf__load_vmlinux_btf(void) struct utsname buf; struct btf *btf; int i, err; + bool found_path = false; uname(&buf); @@ -4951,6 +4952,7 @@ struct btf *btf__load_vmlinux_btf(void) if (faccessat(AT_FDCWD, path, R_OK, AT_EACCESS)) continue; + found_path = true; btf = btf__parse(path, NULL); err = libbpf_get_error(btf); pr_debug("loading kernel BTF '%s': %d\n", path, err); @@ -4960,7 +4962,11 @@ struct btf *btf__load_vmlinux_btf(void) return btf; } - pr_warn("failed to find valid kernel BTF\n"); + if (found_path) + pr_warn("failed to find BTF in kernel (was CONFIG_DEBUG_INFO_BTF enabled?)\n"); + else + pr_warn("failed to find a kernel (typically /sys/kernel/btf/vmlinux) for BTF data\n"); + return libbpf_err_ptr(-ESRCH); }