From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f171.google.com (mail-pf1-f171.google.com [209.85.210.171]) (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 B6B4633375F for ; Tue, 4 Nov 2025 17:26:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762277220; cv=none; b=BJ9b3skkAacwe03e4KotGHmCQ2v7kHILVq8+Gx5J7A6838w/PZVpqmHnnFzaShw329mD2hZVNVPsJoty7MJvdQMiv/2IHRuV6+IXw4nLLZI9p+pobgxaVUYp3DkVAFC9p0BEx2bHZLx2pLFpcHfHld22q+3PSKUxylSaaWR/nnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762277220; c=relaxed/simple; bh=AmxjQtjAmnFN/NOgV49D01IZmIdkLn9LXZunVoDiRIg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o09mMBAnVo2uXySyxQJn8eQHHYX2mCE1NIFdLkNj5+FOirZrUhoRtBlm1rCVdEVErS6medWeB8RKx7pB80hXg9eCAn2oInk89dNwd0LRJLaVBFYbW4jvbEWGXO5Jpl8yN5NYPpwXZ2d7IfKa2buEbHZo6l08WQNK1m/+fuwfMb0= 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=h3VNgn5k; arc=none smtp.client-ip=209.85.210.171 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="h3VNgn5k" Received: by mail-pf1-f171.google.com with SMTP id d2e1a72fcca58-76e2ea933b7so46251b3a.1 for ; Tue, 04 Nov 2025 09:26:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1762277218; x=1762882018; 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=zB17NeSN53m7+EHqn57/zqq9l8oWLsYXEuHxOsehStA=; b=h3VNgn5kBb76DcyJ0W5O34Yzk10OtiGG7KopYqOHOqR3cb0w1K1p+BicKoxJt/iAD1 QsztryTM9lTU8HE4kNh8Aq/4SBBoBa6/i88aYefYmPE8+Bhy9zzdX+RK+w/rQsRGsgXg EJOabMDyMG3Ku+B2yRqHluVgRrPqtH1wJf840c0wMCOAhjiJLl8YtIYSLrbwPQ1U/3CO BcxTsgHOJSwGKPgTEVgJoK0YOVEEuNQKLAccVsAM2pux+56ZHI6czNrWx/HaTNl+8doh PLK/xebD39GqpmCm7s+A45YBkQqdrPRshUsV8iqY8bsoYvH+dSDDti3zrHM4Ce9XSiep jUWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762277218; x=1762882018; 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=zB17NeSN53m7+EHqn57/zqq9l8oWLsYXEuHxOsehStA=; b=O4KbJVL4EGBskCoVFGr9olcwM/MIN1muyEKLOXdtK3fyFPhK8MN1RDc2FqtwexyKGm 76U4+kgVaZe3KFX5MUctpIfuCsVP7eueBenEItc41RpOZat7Gy3hb5+6JBFqpXM119Sc WNuozeGQKC947SGWveoRlcw7jMFZHyzhKPvEGUuuSQxW15gO33+gHsCXPUCN20x6jU1E C7Ohso/fQecKKVcEz0PQEXEH4/8B2xl26LFq0S8r7wRZhlgsXRBjxyC1uYzaXVJLXkfk 8iXvrCtr5vuOs4nvaEjAe4pjANxachfYgX6/qCY4KUgIYADI4r1NmSNidmh4KaIk4sJ9 3EqA== X-Gm-Message-State: AOJu0YzqPo0UAHJv+SZnauR4yDPiaWryjBWXuoTV2X/kUqSxJXq/Cqoa LLdGFKcTJPU5p9cujiYVg6OBwzDE+1W0gAJlJovpDKl/8idLXYpTIVHS X-Gm-Gg: ASbGncsWzaAAwW2uXtwJ1cAXKPICb/OAIOfca9jCTZkoIyUZzoGfsAuOgfFiPVr1mOP +0ZPGahZy3iVIQ9vQlI1z7Ow5Y6t7Fds2MNumtMYfCZ5myFgQYK0Efjdras0T2ssS0UP3AhgOP9 IQoVhWdysj4VVgwPZ/ZaFs1LXp/ffZMG3H7GXBedg2u0X5F9brVLd/icvxjxg6phPkB0UqUtyI2 +05gl3De7uNzNoxq7fUgxYJ3zErrCnu5iUWkCiLFwtNutHxcr4hfCa5KBL11447aIJ49122Rwqa bHW/+YIMqRS4kaFn3XwaB/AP6BZR1isTrcL45XUgZ33okpAD1luYE6eVQDiSjoGXrc74kshQz+x xSi59RDPY8dt2gVgTtOtoCYDyVVD2liY0f/oMM4CFve+A4mPgbQ8Fw4kA8NOIo0vZHQ== X-Google-Smtp-Source: AGHT+IG7RTGi9kuw0LKIAGN8PcXtPqvP8OK1AhWGY+a4D/fwZMLwsPqZ9vFk/94OdQtgg4fHdm12Hg== X-Received: by 2002:a05:6a00:7582:b0:77d:c625:f5d3 with SMTP id d2e1a72fcca58-7acbe8fa32cmr4756338b3a.1.1762277217692; Tue, 04 Nov 2025 09:26:57 -0800 (PST) Received: from localhost ([2a03:2880:ff:3::]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7acd3d013e2sm3501677b3a.33.2025.11.04.09.26.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Nov 2025 09:26:57 -0800 (PST) From: Amery Hung To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, tj@kernel.org, martin.lau@kernel.org, ameryhung@gmail.com, kernel-team@meta.com Subject: [PATCH bpf-next v5 2/7] bpf: Support associating BPF program with struct_ops Date: Tue, 4 Nov 2025 09:26:47 -0800 Message-ID: <20251104172652.1746988-3-ameryhung@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251104172652.1746988-1-ameryhung@gmail.com> References: <20251104172652.1746988-1-ameryhung@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a new BPF command BPF_PROG_ASSOC_STRUCT_OPS to allow associating a BPF program with a struct_ops map. This command takes a file descriptor of a struct_ops map and a BPF program and set prog->aux->st_ops_assoc to the kdata of the struct_ops map. The command does not accept a struct_ops program nor a non-struct_ops map. Programs of a struct_ops map is automatically associated with the map during map update. If a program is shared between two struct_ops maps, prog->aux->st_ops_assoc will be poisoned to indicate that the associated struct_ops is ambiguous. The pointer, once poisoned, cannot be reset since we have lost track of associated struct_ops. For other program types, the associated struct_ops map, once set, cannot be changed later. This restriction may be lifted in the future if there is a use case. A kernel helper bpf_prog_get_assoc_struct_ops() can be used to retrieve the associated struct_ops pointer. The returned pointer, if not NULL, is guaranteed to be valid and point to a fully updated struct_ops struct. For struct_ops program reused in multiple struct_ops map, the return will be NULL. To make sure the returned pointer to be valid, the command increases the refcount of the map for every associated non-struct_ops programs. For struct_ops programs, the destruction of a struct_ops map already waits for its BPF programs to finish running. A later patch will further make sure the map will not be freed when an async callback schedule from struct_ops is running. struct_ops implementers should note that the struct_ops returned may or may not be attached. The struct_ops implementer will be responsible for tracking and checking the state of the associated struct_ops map if the use case requires an attached struct_ops. Signed-off-by: Amery Hung --- include/linux/bpf.h | 16 ++++++ include/uapi/linux/bpf.h | 17 +++++++ kernel/bpf/bpf_struct_ops.c | 90 ++++++++++++++++++++++++++++++++++ kernel/bpf/core.c | 3 ++ kernel/bpf/syscall.c | 46 +++++++++++++++++ tools/include/uapi/linux/bpf.h | 17 +++++++ 6 files changed, 189 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a47d67db3be5..0f71030c03e1 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1726,6 +1726,8 @@ struct bpf_prog_aux { struct rcu_head rcu; }; struct bpf_stream stream[2]; + struct mutex st_ops_assoc_mutex; + struct bpf_map *st_ops_assoc; }; struct bpf_prog { @@ -2026,6 +2028,9 @@ static inline void bpf_module_put(const void *data, struct module *owner) module_put(owner); } int bpf_struct_ops_link_create(union bpf_attr *attr); +int bpf_prog_assoc_struct_ops(struct bpf_prog *prog, struct bpf_map *map); +void bpf_prog_disassoc_struct_ops(struct bpf_prog *prog); +void *bpf_prog_get_assoc_struct_ops(const struct bpf_prog_aux *aux); u32 bpf_struct_ops_id(const void *kdata); #ifdef CONFIG_NET @@ -2073,6 +2078,17 @@ static inline int bpf_struct_ops_link_create(union bpf_attr *attr) { return -EOPNOTSUPP; } +static inline int bpf_prog_assoc_struct_ops(struct bpf_prog *prog, struct bpf_map *map) +{ + return -EOPNOTSUPP; +} +static inline void bpf_prog_disassoc_struct_ops(struct bpf_prog *prog) +{ +} +static inline void *bpf_prog_get_assoc_struct_ops(const struct bpf_prog_aux *aux) +{ + return NULL; +} static inline void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map) { } diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 1d73f165394d..a2d8cfac8555 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -918,6 +918,16 @@ union bpf_iter_link_info { * Number of bytes read from the stream on success, or -1 if an * error occurred (in which case, *errno* is set appropriately). * + * BPF_PROG_ASSOC_STRUCT_OPS + * Description + * Associate a BPF program with a struct_ops map. The struct_ops + * map is identified by *map_fd* and the BPF program is + * identified by *prog_fd*. + * + * Return + * 0 on success or -1 if an error occurred (in which case, + * *errno* is set appropriately). + * * NOTES * eBPF objects (maps and programs) can be shared between processes. * @@ -974,6 +984,7 @@ enum bpf_cmd { BPF_PROG_BIND_MAP, BPF_TOKEN_CREATE, BPF_PROG_STREAM_READ_BY_FD, + BPF_PROG_ASSOC_STRUCT_OPS, __MAX_BPF_CMD, }; @@ -1893,6 +1904,12 @@ union bpf_attr { __u32 prog_fd; } prog_stream_read; + struct { + __u32 map_fd; + __u32 prog_fd; + __u32 flags; + } prog_assoc_struct_ops; + } __attribute__((aligned(8))); /* The description below is an attempt at providing documentation to eBPF diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index a41e6730edcf..0a19842da7a2 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -533,6 +533,17 @@ static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map) } } +static void bpf_struct_ops_map_dissoc_progs(struct bpf_struct_ops_map *st_map) +{ + u32 i; + + for (i = 0; i < st_map->funcs_cnt; i++) { + if (!st_map->links[i]) + break; + bpf_prog_disassoc_struct_ops(st_map->links[i]->prog); + } +} + static void bpf_struct_ops_map_free_image(struct bpf_struct_ops_map *st_map) { int i; @@ -801,6 +812,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, goto reset_unlock; } + err = bpf_prog_assoc_struct_ops(prog, &st_map->map); + if (err) { + bpf_prog_put(prog); + goto reset_unlock; + } + link = kzalloc(sizeof(*link), GFP_USER); if (!link) { bpf_prog_put(prog); @@ -980,6 +997,8 @@ static void bpf_struct_ops_map_free(struct bpf_map *map) if (btf_is_module(st_map->btf)) module_put(st_map->st_ops_desc->st_ops->owner); + bpf_struct_ops_map_dissoc_progs(st_map); + bpf_struct_ops_map_del_ksyms(st_map); /* The struct_ops's function may switch to another struct_ops. @@ -1394,6 +1413,77 @@ int bpf_struct_ops_link_create(union bpf_attr *attr) return err; } +int bpf_prog_assoc_struct_ops(struct bpf_prog *prog, struct bpf_map *map) +{ + struct bpf_map *st_ops_assoc; + + guard(mutex)(&prog->aux->st_ops_assoc_mutex); + + st_ops_assoc = prog->aux->st_ops_assoc; + + if (st_ops_assoc && st_ops_assoc == map) + return 0; + + if (st_ops_assoc) { + if (prog->type != BPF_PROG_TYPE_STRUCT_OPS) + return -EBUSY; + + WRITE_ONCE(prog->aux->st_ops_assoc, BPF_PTR_POISON); + } else { + if (prog->type != BPF_PROG_TYPE_STRUCT_OPS) + bpf_map_inc(map); + + WRITE_ONCE(prog->aux->st_ops_assoc, map); + } + + return 0; +} + +void bpf_prog_disassoc_struct_ops(struct bpf_prog *prog) +{ + struct bpf_map *st_ops_assoc; + + guard(mutex)(&prog->aux->st_ops_assoc_mutex); + + st_ops_assoc = prog->aux->st_ops_assoc; + + if (!st_ops_assoc || st_ops_assoc == BPF_PTR_POISON) + return; + + if (prog->type != BPF_PROG_TYPE_STRUCT_OPS) + bpf_map_put(st_ops_assoc); + + WRITE_ONCE(prog->aux->st_ops_assoc, NULL); +} + +/* + * Get a reference to the struct_ops struct (i.e., kdata) associated with a + * program. + * + * If the returned pointer is not NULL, it must points to a valid and + * initialized struct_ops. The struct_ops may or may not be attached. + * Kernel struct_ops implementers are responsible for tracking and checking + * the state of the struct_ops if the use case requires an attached struct_ops. + */ +void *bpf_prog_get_assoc_struct_ops(const struct bpf_prog_aux *aux) +{ + struct bpf_map *st_ops_assoc = READ_ONCE(aux->st_ops_assoc); + struct bpf_struct_ops_map *st_map; + + if (!st_ops_assoc || st_ops_assoc == BPF_PTR_POISON) + return NULL; + + st_map = (struct bpf_struct_ops_map *)st_ops_assoc; + + if (smp_load_acquire(&st_map->kvalue.common.state) == BPF_STRUCT_OPS_STATE_INIT) { + bpf_map_put(st_ops_assoc); + return NULL; + } + + return &st_map->kvalue.data; +} +EXPORT_SYMBOL_GPL(bpf_prog_get_assoc_struct_ops); + void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map) { struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map; diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index d595fe512498..441bfeece377 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -136,6 +136,7 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag mutex_init(&fp->aux->used_maps_mutex); mutex_init(&fp->aux->ext_mutex); mutex_init(&fp->aux->dst_mutex); + mutex_init(&fp->aux->st_ops_assoc_mutex); #ifdef CONFIG_BPF_SYSCALL bpf_prog_stream_init(fp); @@ -286,6 +287,7 @@ void __bpf_prog_free(struct bpf_prog *fp) if (fp->aux) { mutex_destroy(&fp->aux->used_maps_mutex); mutex_destroy(&fp->aux->dst_mutex); + mutex_destroy(&fp->aux->st_ops_assoc_mutex); kfree(fp->aux->poke_tab); kfree(fp->aux); } @@ -2875,6 +2877,7 @@ static void bpf_prog_free_deferred(struct work_struct *work) #endif bpf_free_used_maps(aux); bpf_free_used_btfs(aux); + bpf_prog_disassoc_struct_ops(aux->prog); if (bpf_prog_is_dev_bound(aux)) bpf_prog_dev_bound_destroy(aux->prog); #ifdef CONFIG_PERF_EVENTS diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 8a129746bd6c..dddbe89e9718 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -6107,6 +6107,49 @@ static int prog_stream_read(union bpf_attr *attr) return ret; } +#define BPF_PROG_ASSOC_STRUCT_OPS_LAST_FIELD prog_assoc_struct_ops.prog_fd + +static int prog_assoc_struct_ops(union bpf_attr *attr) +{ + struct bpf_prog *prog; + struct bpf_map *map; + int ret; + + if (CHECK_ATTR(BPF_PROG_ASSOC_STRUCT_OPS)) + return -EINVAL; + + if (attr->prog_assoc_struct_ops.flags) + return -EINVAL; + + prog = bpf_prog_get(attr->prog_assoc_struct_ops.prog_fd); + if (IS_ERR(prog)) + return PTR_ERR(prog); + + if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) { + ret = -EINVAL; + goto put_prog; + } + + map = bpf_map_get(attr->prog_assoc_struct_ops.map_fd); + if (IS_ERR(map)) { + ret = PTR_ERR(map); + goto put_prog; + } + + if (map->map_type != BPF_MAP_TYPE_STRUCT_OPS) { + ret = -EINVAL; + goto put_map; + } + + ret = bpf_prog_assoc_struct_ops(prog, map); + +put_map: + bpf_map_put(map); +put_prog: + bpf_prog_put(prog); + return ret; +} + static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size) { union bpf_attr attr; @@ -6246,6 +6289,9 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size) case BPF_PROG_STREAM_READ_BY_FD: err = prog_stream_read(&attr); break; + case BPF_PROG_ASSOC_STRUCT_OPS: + err = prog_assoc_struct_ops(&attr); + break; default: err = -EINVAL; break; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 1d73f165394d..a2d8cfac8555 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -918,6 +918,16 @@ union bpf_iter_link_info { * Number of bytes read from the stream on success, or -1 if an * error occurred (in which case, *errno* is set appropriately). * + * BPF_PROG_ASSOC_STRUCT_OPS + * Description + * Associate a BPF program with a struct_ops map. The struct_ops + * map is identified by *map_fd* and the BPF program is + * identified by *prog_fd*. + * + * Return + * 0 on success or -1 if an error occurred (in which case, + * *errno* is set appropriately). + * * NOTES * eBPF objects (maps and programs) can be shared between processes. * @@ -974,6 +984,7 @@ enum bpf_cmd { BPF_PROG_BIND_MAP, BPF_TOKEN_CREATE, BPF_PROG_STREAM_READ_BY_FD, + BPF_PROG_ASSOC_STRUCT_OPS, __MAX_BPF_CMD, }; @@ -1893,6 +1904,12 @@ union bpf_attr { __u32 prog_fd; } prog_stream_read; + struct { + __u32 map_fd; + __u32 prog_fd; + __u32 flags; + } prog_assoc_struct_ops; + } __attribute__((aligned(8))); /* The description below is an attempt at providing documentation to eBPF -- 2.47.3