From nobody Sat Feb 7 08:23:28 2026 Received: from mail-pf1-f194.google.com (mail-pf1-f194.google.com [209.85.210.194]) (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 863DC1B4247 for ; Sat, 18 Oct 2025 14:21:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.194 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760797312; cv=none; b=GvEiXNpqt7WYFqMKZNWi1ZOZ4TmKjU8O/7MbhcuFVnet1lMOVNIPmzgS3fiVCtuNfp59jSLYkv61g1RZIH/wYcce/YcUvelsh0jEmSSGCUSH9gjWa4LJvtgRkzOocIP/jJSkKFQ6Flcy8RhTl1Q34JOcE6FDprGBpF96Zj/uUcU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760797312; c=relaxed/simple; bh=c99jLCl4oK0lYbHL6l7ZVaK/eHqsZKgxrs6O+Xjt2Ro=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hyU4/ZS3riGmqg1QjOdaaPJuqOkwQfzYN0NT0P3xc6Oi0CugZBs3fSd2RtH841CNUldmeWt4C0WnC4cA4n+LKJ0fu+pHa8VzFCqqzqEz6kgCj0msgWg56GDjlDK+tE6/k6ebWAVS/pmnq3FIXsJqdS3Tdw3/F9kI79nBtF+e82k= 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=hhk061bR; arc=none smtp.client-ip=209.85.210.194 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="hhk061bR" Received: by mail-pf1-f194.google.com with SMTP id d2e1a72fcca58-78af743c232so2503551b3a.1 for ; Sat, 18 Oct 2025 07:21:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1760797310; x=1761402110; 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=NYwvvMkNsizkLkVR3lZyOmzWt267ljepeEAqISwgDss=; b=hhk061bR+uw2b/fjfGSSxs2NgEfBA3i/2BjMPWD4K4YGGrDtKRipuD+F2mS58iT5PO sufWTv1GBXwxjahpsL/1Ut3FsgiQ34iTfXQ3ZUaD8tbarSZ9j/wt3I18xA4VJ+OcFE3z woBY9UxLzJPQLp9vxh6oWS4YCZ4WG7eZTj93Cd/TiaaiY7BolYpBxliIXOP8shWny1yE wJwJVxxdIFV5+dSCK/YZAGZtUBTSluj89gW0u3qFTSF0goxkdrQzEctBFQ9k47zC7/E8 E4I2esZ8dLyYtq9c9H8Q3qGmkfnMeJa2fMqz2vJl8TW5ek22Y9r/taZyrWrkQFRMgaJe 4CQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760797310; x=1761402110; 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=NYwvvMkNsizkLkVR3lZyOmzWt267ljepeEAqISwgDss=; b=Pakw+6Vi0IPQ+HTnC5iDuptdEo17j5ZmUmHGu8she1/yzxVltdwE/RoOF3mEwwwKTL eOO3xqPjPIKZfW3Q8TgaJdIXYhagEPEK9tnJ1YLjKsMS4stbxY46voNWBMhWGdF1mRPg RdNWCuBvCsJulh+gFXx/y0g+LR/A5YOs3lzwzzp/7Xb1WchI3THuuGDg53SWSmstplSM fZFdI6VyDWLNDE2R45vjaHc825q2idufWfKFcGWLK4WL9EUulIIS14y0/0CUEjdMVLoS Gx7D/lsRr7caB9SQ5lbmI85mHiqahv5VfOGRK9kmLYLSFbzmMvThLy3OOf/qsd+NNCBt CknA== X-Forwarded-Encrypted: i=1; AJvYcCV9QhnvBsmyUnquHvXwmKlnNg6uGjjMfug05vluAErL5A42SV/C67Un230ccw8mUn1YP06P3eojpJEKdFc=@vger.kernel.org X-Gm-Message-State: AOJu0Yx7K32wXDVoeL+Q+xBDjp+wvHwiUzWYfBZW3N1zWvCiCYRSl9qy XrmX2GBH4nK/6m1nmtInSjcaHjOQypJbgHXkAV1ClbniX8j7tGfJkZ4w X-Gm-Gg: ASbGnct8qioS17YaDTrxPNJYceqPAUyWUUhz8VasIufQafoFn+Gu32H+2E99NWeufyK nHZqwzouaYCFErUKKV8k+vRV11XN/345Hdvg95YphG1t8eVa3bp6OWfuvcOZ2FmufSVD2kHTJ1+ hGsudMb+Y393Y+PuTyEgcNzSpRRqXyJdPP1RtdJ1dlJi2FF6fwMfQP8rucYypgPH24D8lLktVSO oFgToc98w0NjXPa4KEAQ+1gAYGlyjmyEOQqyTwNeyOvduPLIgPIOPHXGkKShYy9wIkUdSwwmHcs +tK/ZBYaOK3/jHpIxlkOCxHIyj205ces7oW+R6syQ+zBm2Isxpj5u5Ti4aNWYmpEuZb/446X65p ytv5JQDDTtlcm+KYmRR1o+qMv9ZShhSjakFAxcoClABrxNY3oH8eTClvMVduOXZyCK6WZKrtuPj NrA9vUYqqQXKk= X-Google-Smtp-Source: AGHT+IE88gDZ5ZuEI9rRpvXV/ekTZy+PSm2f/QXfC+JY64iWLG600+Hr2zdXGf21CmwOwy+JFCe24w== X-Received: by 2002:a05:6a00:2e99:b0:781:c54:4d24 with SMTP id d2e1a72fcca58-7a220ab6c7bmr7997114b3a.21.1760797309777; Sat, 18 Oct 2025 07:21:49 -0700 (PDT) Received: from 7950hx ([43.129.244.20]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7a23010d818sm2913589b3a.53.2025.10.18.07.21.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Oct 2025 07:21:49 -0700 (PDT) From: Menglong Dong X-Google-Original-From: Menglong Dong To: ast@kernel.org, jolsa@kernel.org Cc: daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, mattbobrowski@google.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, leon.hwang@linux.dev, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH RFC bpf-next 2/5] bpf: add kfunc bpf_tracing_is_exit for TRACE_SESSION Date: Sat, 18 Oct 2025 22:21:21 +0800 Message-ID: <20251018142124.783206-3-dongml2@chinatelecom.cn> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251018142124.783206-1-dongml2@chinatelecom.cn> References: <20251018142124.783206-1-dongml2@chinatelecom.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" If TRACE_SESSION exists, we will use extra 8-bytes in the stack of the trampoline to store the flags that we needed, and the 8-bytes lie before the function argument count, which means ctx[-2]. And we will store the flag "is_exit" to the first bit of it. Introduce the kfunc bpf_tracing_is_exit(), which is used to tell if it is fexit currently. Signed-off-by: Menglong Dong Co-developed-by: Leon Hwang Signed-off-by: Leon Hwang --- kernel/bpf/verifier.c | 5 ++++- kernel/trace/bpf_trace.c | 43 +++++++++++++++++++++++++++++++++++++--- 2 files changed, 44 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 40e3274e8bc2..a1db11818d01 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12284,6 +12284,7 @@ enum special_kfunc_type { KF___bpf_trap, KF_bpf_task_work_schedule_signal, KF_bpf_task_work_schedule_resume, + KF_bpf_tracing_is_exit, }; =20 BTF_ID_LIST(special_kfunc_list) @@ -12356,6 +12357,7 @@ BTF_ID(func, bpf_res_spin_unlock_irqrestore) BTF_ID(func, __bpf_trap) BTF_ID(func, bpf_task_work_schedule_signal) BTF_ID(func, bpf_task_work_schedule_resume) +BTF_ID(func, bpf_tracing_is_exit) =20 static bool is_task_work_add_kfunc(u32 func_id) { @@ -12410,7 +12412,8 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, struct bpf_reg_state *reg =3D ®s[regno]; bool arg_mem_size =3D false; =20 - if (meta->func_id =3D=3D special_kfunc_list[KF_bpf_cast_to_kern_ctx]) + if (meta->func_id =3D=3D special_kfunc_list[KF_bpf_cast_to_kern_ctx] || + meta->func_id =3D=3D special_kfunc_list[KF_bpf_tracing_is_exit]) return KF_ARG_PTR_TO_CTX; =20 /* In this function, we verify the kfunc's BTF as per the argument type, diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4f87c16d915a..6dde48b9d27f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3356,12 +3356,49 @@ static const struct btf_kfunc_id_set bpf_kprobe_mul= ti_kfunc_set =3D { .filter =3D bpf_kprobe_multi_filter, }; =20 -static int __init bpf_kprobe_multi_kfuncs_init(void) +__bpf_kfunc_start_defs(); + +__bpf_kfunc bool bpf_tracing_is_exit(void *ctx) +{ + /* ctx[-2] is the session flags, and the last bit is is_exit */ + return ((u64 *)ctx)[-2] & 1; +} + +__bpf_kfunc_end_defs(); + +BTF_KFUNCS_START(tracing_kfunc_set_ids) +BTF_ID_FLAGS(func, bpf_tracing_is_exit) +BTF_KFUNCS_END(tracing_kfunc_set_ids) + +static int bpf_tracing_filter(const struct bpf_prog *prog, u32 kfunc_id) +{ + if (!btf_id_set8_contains(&tracing_kfunc_set_ids, kfunc_id)) + return 0; + + if (prog->type !=3D BPF_PROG_TYPE_TRACING || + prog->expected_attach_type !=3D BPF_TRACE_SESSION) + return -EINVAL; + + return 0; +} + +static const struct btf_kfunc_id_set bpf_tracing_kfunc_set =3D { + .owner =3D THIS_MODULE, + .set =3D &tracing_kfunc_set_ids, + .filter =3D bpf_tracing_filter, +}; + +static int __init bpf_trace_kfuncs_init(void) { - return register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_kprobe_multi_= kfunc_set); + int err =3D 0; + + err =3D err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_kprob= e_multi_kfunc_set); + err =3D err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_trac= ing_kfunc_set); + + return err; } =20 -late_initcall(bpf_kprobe_multi_kfuncs_init); +late_initcall(bpf_trace_kfuncs_init); =20 typedef int (*copy_fn_t)(void *dst, const void *src, u32 size, struct task= _struct *tsk); =20 --=20 2.51.0