From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F3A04B5AD for ; Wed, 20 Dec 2023 23:31:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=meta.com Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3BKLtkLA020761 for ; Wed, 20 Dec 2023 15:31:41 -0800 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3v47dfgye4-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 20 Dec 2023 15:31:40 -0800 Received: from twshared10507.42.prn1.facebook.com (2620:10d:c0a8:1b::30) by mail.thefacebook.com (2620:10d:c0a8:82::b) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Wed, 20 Dec 2023 15:31:37 -0800 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 29C613D865022; Wed, 20 Dec 2023 15:31:29 -0800 (PST) From: Andrii Nakryiko To: , , , CC: , Subject: [PATCH bpf-next 0/8] Libbpf-side __arg_ctx fallback support Date: Wed, 20 Dec 2023 15:31:19 -0800 Message-ID: <20231220233127.1990417-1-andrii@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: 3RwqMlmkKZhxGtMeh8ccSwoAhNuRDebb X-Proofpoint-GUID: 3RwqMlmkKZhxGtMeh8ccSwoAhNuRDebb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-20_13,2023-12-20_01,2023-05-22_02 Support __arg_ctx global function argument tag semantics even on older ke= rnels that don't natively support it through btf_decl_tag("arg:ctx"). Patches #2-#6 are preparatory work to allow to postpone BTF loading into = the kernel until after all the BPF program relocations (including global func appending to main programs) are done. Patch #4 is perhaps the most import= ant and establishes pre-created stable placeholder FDs, so that relocations c= an embed valid map FDs into ldimm64 instructions. Once BTF is done after relocation, what's left is to adjust BTF informati= on to have each main program's copy of each used global subprog to point to its= own adjusted FUNC -> FUNC_PROTO type chain (if they use __arg_ctx) in such a = way as to satisfy type expectations of BPF verifier regarding the PTR_TO_CTX argument definition. See patch #7 for details. Patch #8 adds few more __arg_ctx use cases (edge cases like multiple argu= ments having __arg_ctx, etc) to test_global_func_ctx_args.c, to make it simple = to validate that this logic indeed works on old kernels. It does. Andrii Nakryiko (8): libbpf: make uniform use of btf__fd() accessor inside libbpf libbpf: use explicit map reuse flag to skip map creation steps libbpf: don't rely on map->fd as an indicator of map being created libbpf: use stable map placeholder FDs libbpf: move exception callbacks assignment logic into relocation step libbpf: move BTF loading step after relocation step libbpf: implement __arg_ctx fallback logic selftests/bpf: add arg:ctx cases to test_global_funcs tests tools/lib/bpf/libbpf.c | 548 +++++++++++++----- tools/lib/bpf/libbpf_internal.h | 24 + .../bpf/progs/test_global_func_ctx_args.c | 49 ++ 3 files changed, 474 insertions(+), 147 deletions(-) --=20 2.34.1