From patchwork Thu Jan 23 17:05:54 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tao Chen X-Patchwork-Id: 13948491 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pl1-f170.google.com (mail-pl1-f170.google.com [209.85.214.170]) (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 6D71A2153E0; Thu, 23 Jan 2025 17:06:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737651965; cv=none; b=H7Qt7sVvyoDyPf+sMFpnnOvf3dosIQLWMfyhTF5bSnTCnjiQXMCl1sQfpYYB0LqyvpoIDpaGOEdx0ZBIOtoTI5693cRXvpElmNi6oIQd7QUnac55jCJX90TZUBjkTNYUm59tJiyrCI5/SmhmzN2DKOwo59splbT1qiSKcZcBK/k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737651965; c=relaxed/simple; bh=wph3aDXUne9+3+05ABeaMobAhUCM/4X3pkH2X8Tzq9E=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=QuoFxPPknQ3wSTat7Y/s9ZNdhV2w4L+3ivUFXx74jJ7RiHrzqPSvvGuO2xMs9hzQHBydMGClI2ASjVuWsv1pkmb2A66HvPQZgbJOPk77WQWcHLAQkFUArUAF65kcPUAtd6gEfmE/kxcmAXdius43lwLplo1Jg67yre4c+RCyj7k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=M+GLwRyl; arc=none smtp.client-ip=209.85.214.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="M+GLwRyl" Received: by mail-pl1-f170.google.com with SMTP id d9443c01a7336-21675fd60feso26055925ad.2; Thu, 23 Jan 2025 09:06:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1737651962; x=1738256762; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=X9xy2ERYdfTbZqCRKsReSP/A3tr47zfn3k7WTpKW7mM=; b=M+GLwRylqgtQrK8TO4lJihjTDiqKS8KY6DM04iR7UVASdH9KxqZZGmdCFaQB4gtJPh VGuvfGFPwt0EEbLlMquwMQMj7QGwXCLIzAkC4PN8wNdbVYgEGRICAZYO/G++IU62eysZ AneztBoL4dNF/f9toiKn8IrW3uopbVAYi6SaGcsKaRtHxnwxDPhcL0a8etwUWc84vQD+ qvUiBFh8e94VPqmFa29tz+X0zOHd+67YV7UwlTEVCE5f6wDGgRHhmOEOxjJJshb+zBOF My2kyyNYwxHC9YgxLXoFD+8zgdPbJ4Ie786tnA8RfYrz8f0pxw9TTPGIggOPmkYZjxIC Eciw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1737651962; x=1738256762; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=X9xy2ERYdfTbZqCRKsReSP/A3tr47zfn3k7WTpKW7mM=; b=vO4d6o+ueOARqM6bDhvm6jHkNZ74CDEwBYZOK471gtyXfsiDoAEU6mq2RDwb8e63wX OQHx7eQe97ueb4deKcRJ/mMSTd9+S5pXJxE7eBhrKLnd5Z8AlADQnYzAC9Q+QJWySIBR TiGLUJUzGRWXqfq5rc60a7g5h8mRLYuFsgzQPGb6kwkVV1G0LJPN/f1oL8SQOiz09hlU FGIRRGmMpVL9VPs/8SN2hRWEy7kSiWt9G3Pqu7ku3juXz0ZYPS7FQvwTEv0cZriYYiJt m+2A/GN1CFADzD3+LdYEUoS3WTNxPHPKE7I99cMWy7VJ7jo1j9a/2sD/AOIiwhG0ZOA8 sewA== X-Forwarded-Encrypted: i=1; AJvYcCW9on0/gYDR5rUPEknDRRJrj8ikeQf7vMAVu6Ji7U4kY/OAIXBpo+bu+/Rv6FvPf/+4C3eFz5wEJ3ytHNA=@vger.kernel.org X-Gm-Message-State: AOJu0Yx9VMNRqjDFu7qy5HzcQASLA/XDHugyfDSct6k+Vb2nkm9R+88D urj8jaLOH+1/GMszClwGWLOMqdM3gfb52T3fbVE9NAjrV1tfoYfg X-Gm-Gg: ASbGncvAOEj0Jx6/dFQIa8FeGgB10gsdc13lepHlH5TwuPS/bbDt3yyONXngP9kGTyl CIPkb5RPySP9qMIWCMO1nhyzKX5kGb7zaYBDO686HDGNpGemtY9UWqUb2+Et46UN+eMRnijBykO +5mJ0QZxxXu4+QockShwXzSxZvrrXViaHPMcbka5wm7MXutlU0DENVTgQ7kM1L+JWTk/9dl67xS +JvX93FdorJ0u/lT3IAj8BLMrSWDvQV9joHkXLWq7868b1xEHrI/57MfW43S8t43yQtQlxPI23g zH4hP23wtkrx3A== X-Google-Smtp-Source: AGHT+IEdTw4pnjL41rwQIN6p0/20IzSP1hHSlb0opeNUELRCWRnZlwyiSmNPo6aZxsk7m25+BnhpEg== X-Received: by 2002:a05:6a20:3d8e:b0:1ea:ddd1:2fb6 with SMTP id adf61e73a8af0-1eb2158170dmr49995045637.30.1737651962489; Thu, 23 Jan 2025 09:06:02 -0800 (PST) Received: from localhost ([117.147.90.29]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-ac49745c0b9sm89438a12.78.2025.01.23.09.06.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jan 2025 09:06:02 -0800 (PST) From: Tao Chen To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, haoluo@google.com, jolsa@kernel.org, qmo@kernel.org Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Tao Chen Subject: [PATCH bpf-next v2 1/2] libbpf: Add libbpf_probe_bpf_kfunc API Date: Fri, 24 Jan 2025 01:05:54 +0800 Message-Id: <20250123170555.291896-2-chen.dylane@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250123170555.291896-1-chen.dylane@gmail.com> References: <20250123170555.291896-1-chen.dylane@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Similarly to libbpf_probe_bpf_helper, the libbpf_probe_bpf_kfunc used to test the availability of the different eBPF kfuncs on the current system. Signed-off-by: Tao Chen --- tools/lib/bpf/libbpf.h | 17 ++++++++++++- tools/lib/bpf/libbpf.map | 1 + tools/lib/bpf/libbpf_probes.c | 47 +++++++++++++++++++++++++++++++++++ 3 files changed, 64 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 3020ee45303a..ac0b46d8d8f9 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -1680,7 +1680,22 @@ LIBBPF_API int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void */ LIBBPF_API int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id, const void *opts); - +/** + * @brief **libbpf_probe_bpf_kfunc()** detects if host kernel supports the + * use of a given BPF kfunc from specified BPF program type. + * @param prog_type BPF program type used to check the support of BPF kfunc + * @param kfunc_id The btf ID of BPF kfunc to check support for + * @param off The module BTF FD, 0 for vmlinux + * @param opts reserved for future extensibility, should be NULL + * @return 1, if given combination of program type and kfunc is supported; 0, + * if the combination is not supported; negative error code if feature + * detection for provided input arguments failed or can't be performed + * + * Make sure the process has required set of CAP_* permissions (or runs as + * root) when performing feature checking. + */ +LIBBPF_API int libbpf_probe_bpf_kfunc(enum bpf_prog_type prog_type, + int kfunc_id, __s16 off, const void *opts); /** * @brief **libbpf_num_possible_cpus()** is a helper function to get the * number of possible CPUs that the host kernel supports and expects. diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index a8b2936a1646..e93fae101efd 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -436,4 +436,5 @@ LIBBPF_1.6.0 { bpf_linker__add_buf; bpf_linker__add_fd; bpf_linker__new_fd; + libbpf_probe_bpf_kfunc; } LIBBPF_1.5.0; diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index 9dfbe7750f56..641b1b008eeb 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -413,6 +413,53 @@ int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts) return libbpf_err(ret); } +int libbpf_probe_bpf_kfunc(enum bpf_prog_type prog_type, int kfunc_id, + __s16 off, const void *opts) +{ + struct bpf_insn insns[] = { + BPF_EXIT_INSN(), + BPF_EXIT_INSN(), + }; + const size_t insn_cnt = ARRAY_SIZE(insns); + int err; + char buf[4096]; + + if (opts) + return libbpf_err(-EINVAL); + + /* Same logic as probe_bpf_helper check */ + switch (prog_type) { + case BPF_PROG_TYPE_TRACING: + case BPF_PROG_TYPE_EXT: + case BPF_PROG_TYPE_LSM: + case BPF_PROG_TYPE_STRUCT_OPS: + return -EOPNOTSUPP; + default: + break; + } + + insns[0].code = BPF_JMP | BPF_CALL; + insns[0].src_reg = BPF_PSEUDO_KFUNC_CALL; + insns[0].imm = kfunc_id; + insns[0].off = off; + + buf[0] = '\0'; + err = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf)); + if (err < 0) + return libbpf_err(err); + + /* If BPF verifier recognizes BPF kfunc but it's not supported for + * given BPF program type, it will emit "calling kernel function + * bpf_cpumask_create is not allowed", if the kfunc id is invalid, + * it will emit "kernel btf_id 4294967295 is not a function" + */ + if (err == 0 && (strstr(buf, "not allowed") || strstr(buf, "not a function"))) + return 0; + + return 1; /* assume supported */ +} + int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id, const void *opts) { -- 2.43.0