From nobody Mon Feb 9 19:00:12 2026 Received: from mail-yw1-f193.google.com (mail-yw1-f193.google.com [209.85.128.193]) (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 5D90828151C for ; Wed, 7 Jan 2026 06:45:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.193 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767768302; cv=none; b=glg3h+JdqYTAe6FtrWqtcetNjtIXYccKPiwwvfZ/pc8XT8v+auEGt2goq94VIQxarN+a2N1dQRaEt8VWNWIqTIeIPanOOwMChylBbOjgs9zEwPzqtNqQL6SrHT8l1agLQAsr+VbrE40TJVY0UnVtOH0QLOXuyDW88qqcGMoSYk8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767768302; c=relaxed/simple; bh=hn8W0ZkaESYLxe1GBfJWcI5Xf7fsdAugM9oC9zAf41A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GT5u/HrTw+rPK8BPfrS04+nFuNogwLzay5kBAmAhy4ah1dhaZPPYh4pQFdfoaVImQVT8N5TXT+QG/h16p3XYL/DljzZp4EMSS/dQqCuXIdXN7AlgsVIzwrmgM8eVJb53vdT4BsgGmRVPi0L6TCeOjgZ4NC7gULOyhEFCwGgPyjQ= 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=YGuPyU+d; arc=none smtp.client-ip=209.85.128.193 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="YGuPyU+d" Received: by mail-yw1-f193.google.com with SMTP id 00721157ae682-78fb7704cb4so17353277b3.3 for ; Tue, 06 Jan 2026 22:45:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1767768299; x=1768373099; 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=fhltP3LSdy4mcdJDqVz74Ak7lLpTineJXeS0W1GM7yc=; b=YGuPyU+d1or37+3jAHRiabpqdGpFenMiJUjjwmclTLTXp5ysL39fz3F9C3yZNAjGQb /G+JoPEGWPbFTzRXvgU1f+DPPvvoL5eLvXJ+9aJMl7wIZhX9JTVWXo1kC6yncpv01DDc tG0W04Tel4nllhz6BQ1pnQ9bTefbWidmC2VnNhZl7IVURxYeX10Qv8Kdj2MtuXM30/ag tHKDmZBGzP5DxylZOprheBIizw6DcglWulRXfhvFwox/PpXWY3XXTqavolCM41gRdF8b UcwGZI+wZ0Z6B+80TwOhddsgMRbOi0kgEOCXtf9UK0DG2c+Wiie+Ty4u7wq8HuIJGjOn BalA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767768299; x=1768373099; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=fhltP3LSdy4mcdJDqVz74Ak7lLpTineJXeS0W1GM7yc=; b=RSbm88UYYJkXl+PxcOX93KVfzqB3aHDgwerDNmMK6JvykCn+WhmdjcwcBNqvvWZ9qg DabqVQMASmI2fSmVwE6DKr2B1siPEimj2Vn14bnybHCje6sLbEzIuzYLGiTAlfFtWkCQ olY0fmZkc0uS641gp+7UpZKZHd3Nts8ICRvLJtSGjbcC+9Nl3kxsVJbsokV6QyP5dx69 ebtruzwgYV1TmkTGdxHuBYUx9iEYy9/D4FGeVVVOuIDSfN/JcQLAzhDrxVhUpbWC6ZFX rwAU+FVohNEVeOqfBEVzET0Jw1wTreqyEMSV6FF9rRwWNTqFKiJ87hyW8oR4fhSIixTh I6tg== X-Forwarded-Encrypted: i=1; AJvYcCXbu7hujJ44XfDbCQqi9gtDtNhd8CAHE6g/5ZInp52ogT/m8uh/jbG9okdyClWVeEe5WNQ2HZne95QQWFg=@vger.kernel.org X-Gm-Message-State: AOJu0Yw04VGMQ1RgZJD1RDlFNQEVqYJprF3q8TL03ptterPMqxc5A5s7 3ECCNZh8Dxpn/RK4TIFintx0WKS5sa75Qajy0tByDowIhkV9JzGG3zQm X-Gm-Gg: AY/fxX6wcwcKPFhrPgc/xZH2b/wYS7gR3NS+6hhixTlHqxbAPvxRCIkqYhoUqIPw2wF qJZFv5iYd86d5/qbGYPm5NNoqypzC6+MN76Uk1zQeXLdaYgYK1jHkoWh5roEA9Bee24IsYXuRPQ NYwfs9Sqluc5iNXwxfULlCW/MSJ2zxABNx/Zumjk/xmtvXMzrHg1G366ZDqxx4CqVFTlP/HT/ED w/d25AX+eT/zOeLlBs+NBk3UA7b0jQGt2ccxvdyBppvfSglpl3L4UFG4vwTQ1xrj8DqFvXYdnlw DxI+wWCJiAnJ0dZ0uLArYnA4s7uL5t2SIaqZGIhQBOU9J78Vo6GMEfqczQW6v0g0CWZ05NIwEYJ jyrvIQyzQ5tPlD546NuiQ7vujVPGGSd6KzKi89+BQYjFGfXwGVCUXcGfEhThtNZtNV4cRpqiYeu vMrK0bTlI= X-Google-Smtp-Source: AGHT+IFkIesbmcZh8GuMCFU5dkAze0Rcy8DMlKkmb+8exYD67FY3ed9jgK/Vbt8TQxR9ep1RMh55Ng== X-Received: by 2002:a05:690c:620e:b0:786:59d3:49c2 with SMTP id 00721157ae682-790b57fe13cmr12844387b3.35.1767768299328; Tue, 06 Jan 2026 22:44:59 -0800 (PST) Received: from 7940hx ([23.94.188.235]) by smtp.gmail.com with ESMTPSA id 00721157ae682-790b1be88dcsm9635047b3.47.2026.01.06.22.44.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Jan 2026 22:44:58 -0800 (PST) From: Menglong Dong X-Google-Original-From: Menglong Dong To: ast@kernel.org, andrii@kernel.org Cc: daniel@iogearbox.net, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, davem@davemloft.net, dsahern@kernel.org, tglx@linutronix.de, mingo@redhat.com, jiang.biao@linux.dev, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf-next v7 05/11] bpf: support fsession for bpf_session_cookie Date: Wed, 7 Jan 2026 14:43:46 +0800 Message-ID: <20260107064352.291069-6-dongml2@chinatelecom.cn> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260107064352.291069-1-dongml2@chinatelecom.cn> References: <20260107064352.291069-1-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" Implement session cookie for fsession. In order to limit the stack usage, we make 4 as the maximum of the cookie count. The offset of the current cookie is stored in the "(ctx[-1] >> BPF_TRAMP_M_COOKIE) & 0xFF". Therefore, we can get the session cookie with ctx[-offset]. The stack will look like this: return value -> 8 bytes argN -> 8 bytes ... arg1 -> 8 bytes nr_args -> 8 bytes ip (optional) -> 8 bytes cookie2 -> 8 bytes cookie1 -> 8 bytes Inline the bpf_fsession_cookie() in the verifier too. The calling to bpf_session_cookie() will be changed to bpf_fsession_cookie() in verifier for fsession. Signed-off-by: Menglong Dong --- v7: - reuse bpf_session_cookie() instead of introduce new kfunc v5: - remove "cookie_cnt" in struct bpf_trampoline v4: - limit the maximum of the cookie count to 4 - store the session cookies before nr_regs in stack --- include/linux/bpf.h | 16 ++++++++++++++++ kernel/bpf/trampoline.c | 13 +++++++++++-- kernel/bpf/verifier.c | 19 ++++++++++++++++++- kernel/trace/bpf_trace.c | 8 ++++++++ 4 files changed, 53 insertions(+), 3 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index d996dd390681..31e03886c864 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1231,6 +1231,7 @@ enum { =20 #define BPF_TRAMP_M_NR_ARGS 0 #define BPF_TRAMP_M_IS_RETURN 8 +#define BPF_TRAMP_M_COOKIE 9 =20 struct bpf_tramp_links { struct bpf_tramp_link *links[BPF_MAX_TRAMP_LINKS]; @@ -1783,6 +1784,7 @@ struct bpf_prog { enforce_expected_attach_type:1, /* Enforce expected_attach_type checki= ng at attach time */ call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */ call_get_func_ip:1, /* Do we call get_func_ip() */ + call_session_cookie:1, /* Do we call bpf_session_cookie() */ tstamp_type_access:1, /* Accessed __sk_buff->tstamp_type */ sleepable:1; /* BPF program is sleepable */ enum bpf_prog_type type; /* Type of BPF program */ @@ -2191,6 +2193,19 @@ static inline int bpf_fsession_cnt(struct bpf_tramp_= links *links) return cnt; } =20 +static inline int bpf_fsession_cookie_cnt(struct bpf_tramp_links *links) +{ + struct bpf_tramp_links fentries =3D links[BPF_TRAMP_FENTRY]; + int cnt =3D 0; + + for (int i =3D 0; i < links[BPF_TRAMP_FENTRY].nr_links; i++) { + if (fentries.links[i]->link.prog->call_session_cookie) + cnt++; + } + + return cnt; +} + int bpf_prog_ctx_arg_info_init(struct bpf_prog *prog, const struct bpf_ctx_arg_aux *info, u32 cnt); =20 @@ -3949,5 +3964,6 @@ static inline int bpf_map_check_op_flags(struct bpf_m= ap *map, u64 flags, u64 all } =20 bool bpf_fsession_is_return(void *ctx); +u64 *bpf_fsession_cookie(void *ctx); =20 #endif /* _LINUX_BPF_H */ diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 11e043049d68..29b4e00d860c 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -592,6 +592,8 @@ static int bpf_freplace_check_tgt_prog(struct bpf_prog = *tgt_prog) return 0; } =20 +#define BPF_TRAMP_MAX_COOKIES 4 + static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr, struct bpf_prog *tgt_prog) @@ -600,7 +602,7 @@ static int __bpf_trampoline_link_prog(struct bpf_tramp_= link *link, struct bpf_tramp_link *link_exiting; struct bpf_fsession_link *fslink; struct hlist_head *prog_list; - int err =3D 0; + int err =3D 0, cookie_cnt =3D 0; int cnt =3D 0, i; =20 kind =3D bpf_attach_type_to_tramp(link->link.prog); @@ -637,11 +639,18 @@ static int __bpf_trampoline_link_prog(struct bpf_tram= p_link *link, /* prog already linked */ return -EBUSY; hlist_for_each_entry(link_exiting, prog_list, tramp_hlist) { - if (link_exiting->link.prog !=3D link->link.prog) + if (link_exiting->link.prog !=3D link->link.prog) { + if (kind =3D=3D BPF_TRAMP_FSESSION && + link_exiting->link.prog->call_session_cookie) + cookie_cnt++; continue; + } /* prog already linked */ return -EBUSY; } + if (link->link.prog->call_session_cookie && + cookie_cnt >=3D BPF_TRAMP_MAX_COOKIES) + return -E2BIG; =20 hlist_add_head(&link->tramp_hlist, prog_list); if (kind =3D=3D BPF_TRAMP_FSESSION) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d3709edd0e51..210af94e3957 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12508,7 +12508,8 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, bool arg_mem_size =3D false; =20 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_session_is_return]) + meta->func_id =3D=3D special_kfunc_list[KF_bpf_session_is_return] || + meta->func_id =3D=3D special_kfunc_list[KF_bpf_session_cookie]) return KF_ARG_PTR_TO_CTX; =20 if (argno + 1 < nargs && @@ -14294,6 +14295,9 @@ static int check_kfunc_call(struct bpf_verifier_env= *env, struct bpf_insn *insn, return err; } =20 + if (meta.func_id =3D=3D special_kfunc_list[KF_bpf_session_cookie]) + env->prog->call_session_cookie =3D true; + return 0; } =20 @@ -22446,6 +22450,9 @@ static int specialize_kfunc(struct bpf_verifier_env= *env, struct bpf_kfunc_desc } else if (func_id =3D=3D special_kfunc_list[KF_bpf_session_is_return]) { if (prog->expected_attach_type =3D=3D BPF_TRACE_FSESSION) addr =3D (unsigned long)bpf_fsession_is_return; + } else if (func_id =3D=3D special_kfunc_list[KF_bpf_session_cookie]) { + if (prog->expected_attach_type =3D=3D BPF_TRACE_FSESSION) + addr =3D (unsigned long)bpf_fsession_cookie; } desc->addr =3D addr; return 0; @@ -22571,6 +22578,16 @@ static int fixup_kfunc_call(struct bpf_verifier_en= v *env, struct bpf_insn *insn, insn_buf[1] =3D BPF_ALU64_IMM(BPF_RSH, BPF_REG_0, BPF_TRAMP_M_IS_RETURN); insn_buf[2] =3D BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 1); *cnt =3D 3; + } else if (desc->func_id =3D=3D special_kfunc_list[KF_bpf_session_cookie]= && + env->prog->expected_attach_type =3D=3D BPF_TRACE_FSESSION) { + /* Load nr_args from ctx - 8 */ + insn_buf[0] =3D BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + insn_buf[1] =3D BPF_ALU64_IMM(BPF_RSH, BPF_REG_0, BPF_TRAMP_M_COOKIE); + insn_buf[2] =3D BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xFF); + insn_buf[3] =3D BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3); + insn_buf[4] =3D BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1); + insn_buf[5] =3D BPF_ALU64_IMM(BPF_NEG, BPF_REG_0, 0); + *cnt =3D 6; } =20 if (env->insn_aux_data[insn_idx].arg_prog) { diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 9d3bf3bbe8f6..4960bb69cb30 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3320,6 +3320,14 @@ bool bpf_fsession_is_return(void *ctx) return !!(((u64 *)ctx)[-1] & (1 << BPF_TRAMP_M_IS_RETURN)); } =20 +u64 *bpf_fsession_cookie(void *ctx) +{ + /* This helper call is inlined by verifier. */ + u64 off =3D (((u64 *)ctx)[-1] >> BPF_TRAMP_M_COOKIE) & 0xFF; + + return &((u64 *)ctx)[-off]; +} + __bpf_kfunc_start_defs(); =20 __bpf_kfunc bool bpf_session_is_return(void *ctx) --=20 2.52.0