From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (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 AF2A4191F92 for ; Tue, 5 Aug 2025 16:30:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754411435; cv=none; b=jn9/+LV1USvJP02Fapm6oxNwKvt4qzh9kqdLCaq5CkfZ8ng6gLo1UOO1fzXFo1veHqcmppAhl8c3+GlOFBc2lwUlgc0gVF3qwq6IQrrllPtNm1aks1KjgrkdTMArxEBWGzcPdzmxWKf0tmCH7vGSs7Zl7j7/GX7nSF7jaYcCfhE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754411435; c=relaxed/simple; bh=wlr3cjKrNPtchET8JpL1e/O4qXhy+kJA32N+2Am6NIg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HOBf1YVQgZJnGUPT5B7hgZEghlRXxNmlBF4LKTcmdnolb6nS62N7Au4HGz+kMxo6jvy5h5+fWL1G1sM7+kYOKrXGmxYxAZsrrAiWzIq7ECKNQYyFuQlLzl0OIMoqwTjUmdDeYttzXyEwecFY2AQaknQBJxx1QAjwgwT7Uk7K8Y8= 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=l3nwknZE; arc=none smtp.client-ip=91.218.175.170 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="l3nwknZE" 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=1754411431; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6j95fE/14wJW5DRhjwnMrUoRPEkY9g7X6y1JJ7dquf0=; b=l3nwknZExkHgbx1QDbpfSNgnVE1PfZHUGiR/QdXG383EhTQFzPIo3KACsXR8tAiZN0bbKW N2bz3L8CTe1FTRJVQ6OuNO2W0ElS4y+p1y14+orLe6mpGceynkXnPU49hvGVdjlNoRB3sn ilcy+uwyEzWR0wGvVAjW+tTXtYcKJlk= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, yonghong.song@linux.dev, song@kernel.org, eddyz87@gmail.com, dxu@dxuuu.xyz, deso@posteo.net, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v2 1/3] bpf: Introduce BPF_F_CPU flag for percpu_array maps Date: Wed, 6 Aug 2025 00:30:15 +0800 Message-ID: <20250805163017.17015-2-leon.hwang@linux.dev> In-Reply-To: <20250805163017.17015-1-leon.hwang@linux.dev> References: <20250805163017.17015-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Introduce support for the BPF_F_CPU flag in percpu_array maps to allow updating values for specified CPU or for all CPUs with a single value. This enhancement enables: * Efficient update of all CPUs using a single value when cpu == (u32)~0. * Targeted update or lookup for a specified CPU otherwise. The flag is passed via: * map_flags in bpf_percpu_array_update() along with embedded cpu field. * elem_flags in generic_map_update_batch() along with embedded cpu field. Signed-off-by: Leon Hwang --- include/linux/bpf.h | 3 +- include/uapi/linux/bpf.h | 6 +++ kernel/bpf/arraymap.c | 54 ++++++++++++++++++------ kernel/bpf/syscall.c | 77 +++++++++++++++++++++------------- tools/include/uapi/linux/bpf.h | 6 +++ 5 files changed, 103 insertions(+), 43 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index cc700925b802f..c17c45f797ed9 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2691,7 +2691,8 @@ int map_set_for_each_callback_args(struct bpf_verifier_env *env, struct bpf_func_state *callee); int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value); -int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value); +int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value, + u64 flags); int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value, u64 flags); int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 233de8677382e..67bc35e4d6a8d 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1372,6 +1372,12 @@ enum { BPF_NOEXIST = 1, /* create new element if it didn't exist */ BPF_EXIST = 2, /* update existing element */ BPF_F_LOCK = 4, /* spin_lock-ed map_lookup/map_update */ + BPF_F_CPU = 8, /* map_update for percpu_array */ +}; + +enum { + /* indicate updating value across all CPUs for percpu maps. */ + BPF_ALL_CPUS = (__u32)~0, }; /* flags for BPF_MAP_CREATE command */ diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 3d080916faf97..98759f0b22397 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -295,17 +295,24 @@ static void *percpu_array_map_lookup_percpu_elem(struct bpf_map *map, void *key, return per_cpu_ptr(array->pptrs[index & array->index_mask], cpu); } -int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value) +int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value, u64 flags) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; void __percpu *pptr; - int cpu, off = 0; - u32 size; + u32 size, cpu; + int off = 0; if (unlikely(index >= array->map.max_entries)) return -ENOENT; + cpu = flags >> 32; + flags &= (u32)~0; + if (unlikely(flags > BPF_F_CPU)) + return -EINVAL; + if (unlikely((flags & BPF_F_CPU) && cpu >= num_possible_cpus())) + return -ERANGE; + /* per_cpu areas are zero-filled and bpf programs can only * access 'value_size' of them, so copying rounded areas * will not leak any kernel data @@ -313,10 +320,15 @@ int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value) size = array->elem_size; rcu_read_lock(); pptr = array->pptrs[index & array->index_mask]; - for_each_possible_cpu(cpu) { - copy_map_value_long(map, value + off, per_cpu_ptr(pptr, cpu)); - check_and_init_map_value(map, value + off); - off += size; + if (flags & BPF_F_CPU) { + copy_map_value_long(map, value, per_cpu_ptr(pptr, cpu)); + check_and_init_map_value(map, value); + } else { + for_each_possible_cpu(cpu) { + copy_map_value_long(map, value + off, per_cpu_ptr(pptr, cpu)); + check_and_init_map_value(map, value + off); + off += size; + } } rcu_read_unlock(); return 0; @@ -387,13 +399,20 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; void __percpu *pptr; - int cpu, off = 0; - u32 size; + u32 size, cpu; + int off = 0; - if (unlikely(map_flags > BPF_EXIST)) + cpu = map_flags >> 32; + map_flags &= (u32)~0; + if (unlikely(map_flags > BPF_F_CPU)) /* unknown flags */ return -EINVAL; + if (unlikely((map_flags & BPF_F_CPU) && cpu != BPF_ALL_CPUS && + cpu >= num_possible_cpus())) + /* invalid cpu */ + return -ERANGE; + if (unlikely(index >= array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ return -E2BIG; @@ -411,10 +430,19 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, size = array->elem_size; rcu_read_lock(); pptr = array->pptrs[index & array->index_mask]; - for_each_possible_cpu(cpu) { - copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off); + if ((map_flags & BPF_F_CPU) && cpu != BPF_ALL_CPUS) { + copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value); bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu)); - off += size; + } else { + for_each_possible_cpu(cpu) { + copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off); + /* same user-provided value is used if BPF_F_CPU is specified, + * otherwise value is an array of per-cpu values. + */ + if (!(map_flags & BPF_F_CPU)) + off += size; + bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu)); + } } rcu_read_unlock(); return 0; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0fbfa8532c392..43f19d02bc5ce 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -131,8 +131,11 @@ bool bpf_map_write_active(const struct bpf_map *map) return atomic64_read(&map->writecnt) != 0; } -static u32 bpf_map_value_size(const struct bpf_map *map) +static u32 bpf_map_value_size(const struct bpf_map *map, u64 flags) { + if ((flags & BPF_F_CPU) && map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) + return round_up(map->value_size, 8); + if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH || map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH || map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY || @@ -314,7 +317,7 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value, map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) { err = bpf_percpu_hash_copy(map, key, value); } else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) { - err = bpf_percpu_array_copy(map, key, value); + err = bpf_percpu_array_copy(map, key, value, flags); } else if (map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) { err = bpf_percpu_cgroup_storage_copy(map, key, value); } else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) { @@ -1669,7 +1672,10 @@ static int map_lookup_elem(union bpf_attr *attr) if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM)) return -EINVAL; - if (attr->flags & ~BPF_F_LOCK) + if ((u32)attr->flags & ~(BPF_F_LOCK | BPF_F_CPU)) + return -EINVAL; + + if (!((u32)attr->flags & BPF_F_CPU) && attr->flags >> 32) return -EINVAL; CLASS(fd, f)(attr->map_fd); @@ -1679,7 +1685,7 @@ static int map_lookup_elem(union bpf_attr *attr) if (!(map_get_sys_perms(map, f) & FMODE_CAN_READ)) return -EPERM; - if ((attr->flags & BPF_F_LOCK) && + if (((u32)attr->flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)) return -EINVAL; @@ -1687,7 +1693,7 @@ static int map_lookup_elem(union bpf_attr *attr) if (IS_ERR(key)) return PTR_ERR(key); - value_size = bpf_map_value_size(map); + value_size = bpf_map_value_size(map, attr->flags); err = -ENOMEM; value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN); @@ -1744,19 +1750,24 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr) goto err_put; } - if ((attr->flags & BPF_F_LOCK) && + if (((u32)attr->flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)) { err = -EINVAL; goto err_put; } + if (!((u32)attr->flags & BPF_F_CPU) && attr->flags >> 32) { + err = -EINVAL; + goto err_put; + } + key = ___bpf_copy_key(ukey, map->key_size); if (IS_ERR(key)) { err = PTR_ERR(key); goto err_put; } - value_size = bpf_map_value_size(map); + value_size = bpf_map_value_size(map, attr->flags); value = kvmemdup_bpfptr(uvalue, value_size); if (IS_ERR(value)) { err = PTR_ERR(value); @@ -1942,6 +1953,25 @@ int generic_map_delete_batch(struct bpf_map *map, return err; } +static int check_map_batch_elem_flags(struct bpf_map *map, u64 elem_flags) +{ + u32 flags = elem_flags; + + if (flags & ~(BPF_F_LOCK | BPF_F_CPU)) + return -EINVAL; + + if ((flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)) + return -EINVAL; + + if (!(flags & BPF_F_CPU) && elem_flags >> 32) + return -EINVAL; + + if ((flags & BPF_F_CPU) && map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY) + return -EINVAL; + + return 0; +} + int generic_map_update_batch(struct bpf_map *map, struct file *map_file, const union bpf_attr *attr, union bpf_attr __user *uattr) @@ -1952,15 +1982,11 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file, void *key, *value; int err = 0; - if (attr->batch.elem_flags & ~BPF_F_LOCK) - return -EINVAL; - - if ((attr->batch.elem_flags & BPF_F_LOCK) && - !btf_record_has_field(map->record, BPF_SPIN_LOCK)) { - return -EINVAL; - } + err = check_map_batch_elem_flags(map, attr->batch.elem_flags); + if (err) + return err; - value_size = bpf_map_value_size(map); + value_size = bpf_map_value_size(map, attr->batch.elem_flags); max_count = attr->batch.count; if (!max_count) @@ -1986,9 +2012,7 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file, copy_from_user(value, values + cp * value_size, value_size)) break; - err = bpf_map_update_value(map, map_file, key, value, - attr->batch.elem_flags); - + err = bpf_map_update_value(map, map_file, key, value, attr->batch.elem_flags); if (err) break; cond_resched(); @@ -2015,14 +2039,11 @@ int generic_map_lookup_batch(struct bpf_map *map, u32 value_size, cp, max_count; int err; - if (attr->batch.elem_flags & ~BPF_F_LOCK) - return -EINVAL; - - if ((attr->batch.elem_flags & BPF_F_LOCK) && - !btf_record_has_field(map->record, BPF_SPIN_LOCK)) - return -EINVAL; + err = check_map_batch_elem_flags(map, attr->batch.elem_flags); + if (err) + return err; - value_size = bpf_map_value_size(map); + value_size = bpf_map_value_size(map, attr->batch.elem_flags); max_count = attr->batch.count; if (!max_count) @@ -2056,9 +2077,7 @@ int generic_map_lookup_batch(struct bpf_map *map, rcu_read_unlock(); if (err) break; - err = bpf_map_copy_value(map, key, value, - attr->batch.elem_flags); - + err = bpf_map_copy_value(map, key, value, attr->batch.elem_flags); if (err == -ENOENT) goto next_key; @@ -2144,7 +2163,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr) goto err_put; } - value_size = bpf_map_value_size(map); + value_size = bpf_map_value_size(map, 0); err = -ENOMEM; value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 233de8677382e..67bc35e4d6a8d 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1372,6 +1372,12 @@ enum { BPF_NOEXIST = 1, /* create new element if it didn't exist */ BPF_EXIST = 2, /* update existing element */ BPF_F_LOCK = 4, /* spin_lock-ed map_lookup/map_update */ + BPF_F_CPU = 8, /* map_update for percpu_array */ +}; + +enum { + /* indicate updating value across all CPUs for percpu maps. */ + BPF_ALL_CPUS = (__u32)~0, }; /* flags for BPF_MAP_CREATE command */ -- 2.50.1