From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-185.mta0.migadu.com (out-185.mta0.migadu.com [91.218.175.185]) (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 D473CC2EA for ; Mon, 19 Jan 2026 05:11:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.185 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768799500; cv=none; b=stQ4NZxhpeZQe6GgFxQAo4R69vj9mLrH+DX7sKBETO26tpHTE3NfPC5uw1IYmTiSla7LLLQjKMtyDtzok6vrScMM8ejTvyq6US5Hp90xFagogoUZAulxmRYsULhwRPfT5LRHwiT/Rq443iL0tiHAYeqe6Ah7qrB1vZ/SyBYxvyQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768799500; c=relaxed/simple; bh=IKsaF+oqxshhLleQKy7iWm7X2uMoyrTOvJDIORdXmRQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=G3N9tgPqd544dGibg9U3pi3xAOXIROSgRW6wOmM/YV6yQ/aqCzkPDU+dgTK8GOmyhqwEIViuY7A+zqkgZAoHCNpPQyGT6wzFGqtjEErSJILkBJySpckcTKU3t9gCj4Da6Vk8JgxtdLa7z9rS+Nqy8Pivfns08DAETtwJlgBIsoE= 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=MiIm/Ikm; arc=none smtp.client-ip=91.218.175.185 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="MiIm/Ikm" Message-ID: <53c55a34-5b24-4481-91fe-290dc1b2d2e8@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1768799495; 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=TnLKFFVvSi7ptmeanmjm5bs33Tvk+u8kjAwYWyr7ccI=; b=MiIm/Ikmqw+UxpmfyiSmMmct25eTPWQudi4ygEp89H0djgKVTNLR0nckjAEtJ9DP3Ao3B0 4e7RNz0eGBh6fFgnZl2UMnEGOJEXg3H2bOdC3YSKBCwdhfm6/15+kFavWivmNvW1dLLnEP N3IcJRuqG01jj6kijF4uMReNAVJ4BtE= Date: Sun, 18 Jan 2026 21:11:28 -0800 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v3 1/2] bpf: support bpf_get_func_arg() for BPF_TRACE_RAW_TP Content-Language: en-GB To: Menglong Dong , andrii@kernel.org, ast@kernel.org Cc: 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 References: <20260119023732.130642-1-dongml2@chinatelecom.cn> <20260119023732.130642-2-dongml2@chinatelecom.cn> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <20260119023732.130642-2-dongml2@chinatelecom.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT 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(). > 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)