From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (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 5959624BD03 for ; Mon, 19 Jan 2026 05:59:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768802401; cv=none; b=BZcYfGFScuDFVrKpRdz1M0qm3dHJ/X3MLcnKxNgfYbxIgbXRPxupGYxq5lHCYyytEFZeZXzaFpzIIpD5AZJHpFGGHGwG2kPdrQ7fBqrlLMveWhA26BkJhLhM3icpa04Ah23KnIzKcuGwKLBhvgzIPHzMqiZESJMb2Y1YLbCL8gs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768802401; c=relaxed/simple; bh=j/vF8hNjPDjHaC/QNctJECkdd1RqKykTiJz2QSliPO4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=bt/scjNS2dEhplhMhAY0Wrxwb/9T0vJjSfPl49R5MzIl5lDBL6CEuJf7CAo00eZijBUmk+fIKWpWidiIgrhy2DKUB7dnAXMldkNSR9QK5vFwOhYmLrYwEc/E0ILPp/RYYlT5F775Y1Xvju2x7eymJ2kbAq5gfmj7G+tth9pSKq4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=jnzMs6hH; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="jnzMs6hH" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1768802397; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4XQANzAXpyoPhO9UGId1UIScWwWHg0JLuBcFpQLkopQ=; b=jnzMs6hHmh2KoZktLNdqVHUt3hnHtJPFAVljdZVM751sT4ugi1BMSn2EVri6ji+SJ7XTwF mMjBXK5CfiHfB40czCnhppVj+80shADKmM67pNx3muBuU7zwPuqsqVIk+yWZT7tJhQi8Z3 o8SrkgRmo1GtHUwnUqZ+CP5X5lJ+QNM= From: Menglong Dong To: Menglong Dong , Yonghong Song Cc: andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, mattbobrowski@google.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH bpf-next v3 1/2] bpf: support bpf_get_func_arg() for BPF_TRACE_RAW_TP Date: Mon, 19 Jan 2026 13:59:41 +0800 Message-ID: <5957968.DvuYhMxLoT@7940hx> In-Reply-To: <53c55a34-5b24-4481-91fe-290dc1b2d2e8@linux.dev> References: <20260119023732.130642-1-dongml2@chinatelecom.cn> <20260119023732.130642-2-dongml2@chinatelecom.cn> <53c55a34-5b24-4481-91fe-290dc1b2d2e8@linux.dev> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" X-Migadu-Flow: FLOW_OUT On 2026/1/19 13:11 Yonghong Song write: > > On 1/18/26 6:37 PM, Menglong Dong wrote: > > For now, bpf_get_func_arg() and bpf_get_func_arg_cnt() is not supported by > > the BPF_TRACE_RAW_TP, which is not convenient to get the argument of the > > tracepoint, especially for the case that the position of the arguments in > > a tracepoint can change. > > > > The target tracepoint BTF type id is specified during loading time, > > therefore we can get the function argument count from the function > > prototype instead of the stack. > > > > Signed-off-by: Menglong Dong > > --- > > v3: > > - remove unnecessary NULL checking for prog->aux->attach_func_proto > > > > v2: > > - for nr_args, skip first 'void *__data' argument in btf_trace_##name > > typedef > > --- > > kernel/bpf/verifier.c | 32 ++++++++++++++++++++++++++++---- > > kernel/trace/bpf_trace.c | 4 ++-- > > 2 files changed, 30 insertions(+), 6 deletions(-) > > > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > > index faa1ecc1fe9d..4f52342573f0 100644 > > --- a/kernel/bpf/verifier.c > > +++ b/kernel/bpf/verifier.c > > @@ -23316,8 +23316,20 @@ static int do_misc_fixups(struct bpf_verifier_env *env) > > /* Implement bpf_get_func_arg inline. */ > > if (prog_type == BPF_PROG_TYPE_TRACING && > > insn->imm == BPF_FUNC_get_func_arg) { > > - /* Load nr_args from ctx - 8 */ > > - insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); > > + if (eatype == BPF_TRACE_RAW_TP) { > > + int nr_args = btf_type_vlen(prog->aux->attach_func_proto); > > + > > + /* > > + * skip first 'void *__data' argument in btf_trace_##name > > + * typedef > > + */ > > + nr_args--; > > + /* Save nr_args to reg0 */ > > + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args); > > + } else { > > + /* Load nr_args from ctx - 8 */ > > + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); > > + } > > insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6); > > insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3); > > insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1); > > @@ -23369,8 +23381,20 @@ static int do_misc_fixups(struct bpf_verifier_env *env) > > /* Implement get_func_arg_cnt inline. */ > > if (prog_type == BPF_PROG_TYPE_TRACING && > > insn->imm == BPF_FUNC_get_func_arg_cnt) { > > - /* Load nr_args from ctx - 8 */ > > - insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); > > + if (eatype == BPF_TRACE_RAW_TP) { > > + int nr_args = btf_type_vlen(prog->aux->attach_func_proto); > > + > > + /* > > + * skip first 'void *__data' argument in btf_trace_##name > > + * typedef > > + */ > > + nr_args--; > > + /* Save nr_args to reg0 */ > > + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args); > > + } else { > > + /* Load nr_args from ctx - 8 */ > > + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); > > + } > > > > new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); > > if (!new_prog) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > > index 6e076485bf70..9b1b56851d26 100644 > > --- a/kernel/trace/bpf_trace.c > > +++ b/kernel/trace/bpf_trace.c > > @@ -1734,11 +1734,11 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) > > case BPF_FUNC_d_path: > > return &bpf_d_path_proto; > > case BPF_FUNC_get_func_arg: > > - return bpf_prog_has_trampoline(prog) ? &bpf_get_func_arg_proto : NULL; > > + return &bpf_get_func_arg_proto; > > BPF_TRACE_ITER is a tracing attach type. It should not support bpf_get_func_arg() or > bpf_get_func_arg_cnt(). Ah, my bad, I forgot BPF_TRACE_ITER. I'll fix it in the next version. Thanks! Menglong Dong > > > case BPF_FUNC_get_func_ret: > > return bpf_prog_has_trampoline(prog) ? &bpf_get_func_ret_proto : NULL; > > case BPF_FUNC_get_func_arg_cnt: > > - return bpf_prog_has_trampoline(prog) ? &bpf_get_func_arg_cnt_proto : NULL; > > + return &bpf_get_func_arg_cnt_proto; > > case BPF_FUNC_get_attach_cookie: > > if (prog->type == BPF_PROG_TYPE_TRACING && > > prog->expected_attach_type == BPF_TRACE_RAW_TP) > > >