From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (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 77E8E2BCF5D for ; Wed, 3 Sep 2025 17:04:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756919076; cv=none; b=uTe4Ci1rTtrihhoqY+91Seb+cLQOwa6m8SFbnGqBtOJve5QQ+WS0Ggb66o0UjK13zHruIJCocd04PZMd4vWJlu3OWHxwm+YpCc4KViU4oMDpcSR+z3+N5F48yNkF+ugv8xZ7RXgYDLDWhjVaMj9nN39qqLMNb7IhUGMd9faD/GU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756919076; c=relaxed/simple; bh=cKJsYtkP776B04dRA/ldB6Q7492z7ZQ7YtltgZnuQCk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=UpkE3f+y3sZF7eYJY22YLnpmYcM3e5+/VpAJffvFfdCRURXSwmljYb8a/1XpsU9Zg7mVcqkyoZqw/Pa1bzasP4kLNxyTmasY/mR1Xj5O81nP9aJBJVw2p+MU8WWz41XT153cdMeGmlcqWAb3Bv1tAgUApqDlHc6kBGFj1HggQ5o= 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=t3Fu/niW; arc=none smtp.client-ip=95.215.58.172 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="t3Fu/niW" 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=1756919072; 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; bh=80u2bpOuJR39RxMiVzJKRsxTAOuRRjAlmkE6xPXkcfM=; b=t3Fu/niW36bE9KZ8BzxJ9SCozkwdta3NJvqvv9L2LdUPezoHNjtCfVqhBYnGhfgKIC5nta rhDAR2ZhVK1LjwWVJvWEXAQukK0g6JMoD0He+gyIiAx0NrPmnvgo1914AQLmhMpQ4N0FnS hrWKGtIobEnFaTrKRTVo6J1v+Uy2S7Q= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, leon.hwang@linux.dev, kernel-patches-bot@fb.com, Andrii Nakryiko Subject: [PATCH bpf-next] bpf: Generalize data copying for percpu maps Date: Thu, 4 Sep 2025 01:04:11 +0800 Message-ID: <20250903170411.69188-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT While adding support for the BPF_F_CPU and BPF_F_ALL_CPUS flags, the data copying logic of the following percpu map types needs to be updated: * percpu_array * percpu_hash * lru_percpu_hash * percpu_cgroup_storage Following Andrii’s suggestion[0], this patch refactors the data copying logic by introducing two helpers: * `bpf_percpu_copy_to_user()` * `bpf_percpu_copy_from_user()` This prepares the codebase for the upcoming CPU flag support. [0] https://lore.kernel.org/bpf/20250827164509.7401-1-leon.hwang@linux.dev/ Suggested-by: Andrii Nakryiko Signed-off-by: Leon Hwang --- include/linux/bpf.h | 29 ++++++++++++++++++++++++++++- kernel/bpf/arraymap.c | 14 ++------------ kernel/bpf/hashtab.c | 20 +++----------------- kernel/bpf/local_storage.c | 18 ++++++------------ 4 files changed, 39 insertions(+), 42 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 8f6e87f0f3a89..2dc0299a2da50 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -547,6 +547,34 @@ static inline void copy_map_value_long(struct bpf_map *map, void *dst, void *src bpf_obj_memcpy(map->record, dst, src, map->value_size, true); } +#ifdef CONFIG_BPF_SYSCALL +static inline void bpf_percpu_copy_to_user(struct bpf_map *map, void __percpu *pptr, void *value, + u32 size) +{ + int cpu, off = 0; + + 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; + } +} + +void bpf_obj_free_fields(const struct btf_record *rec, void *obj); + +static inline void bpf_percpu_copy_from_user(struct bpf_map *map, void __percpu *pptr, void *value, + u32 size) +{ + int cpu, off = 0; + + for_each_possible_cpu(cpu) { + copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off); + bpf_obj_free_fields(map->record, per_cpu_ptr(pptr, cpu)); + off += size; + } +} +#endif + static inline void bpf_obj_swap_uptrs(const struct btf_record *rec, void *dst, void *src) { unsigned long *src_uptr, *dst_uptr; @@ -2417,7 +2445,6 @@ struct btf_record *btf_record_dup(const struct btf_record *rec); bool btf_record_equal(const struct btf_record *rec_a, const struct btf_record *rec_b); void bpf_obj_free_timer(const struct btf_record *rec, void *obj); void bpf_obj_free_workqueue(const struct btf_record *rec, void *obj); -void bpf_obj_free_fields(const struct btf_record *rec, void *obj); void __bpf_obj_drop_impl(void *p, const struct btf_record *rec, bool percpu); struct bpf_map *bpf_map_get(u32 ufd); diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 3d080916faf97..6be9c54604503 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -300,7 +300,6 @@ int bpf_percpu_array_copy(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; if (unlikely(index >= array->map.max_entries)) @@ -313,11 +312,7 @@ 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; - } + bpf_percpu_copy_to_user(map, pptr, value, size); rcu_read_unlock(); return 0; } @@ -387,7 +382,6 @@ 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; if (unlikely(map_flags > BPF_EXIST)) @@ -411,11 +405,7 @@ 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); - bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu)); - off += size; - } + bpf_percpu_copy_from_user(map, pptr, value, size); rcu_read_unlock(); return 0; } diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 71f9931ac64cd..5f0f3c00dbb74 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -944,12 +944,8 @@ static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr, copy_map_value(&htab->map, this_cpu_ptr(pptr), value); } else { u32 size = round_up(htab->map.value_size, 8); - int off = 0, cpu; - for_each_possible_cpu(cpu) { - copy_map_value_long(&htab->map, per_cpu_ptr(pptr, cpu), value + off); - off += size; - } + bpf_percpu_copy_from_user(&htab->map, pptr, value, size); } } @@ -1802,15 +1798,10 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, memcpy(dst_key, l->key, key_size); if (is_percpu) { - int off = 0, cpu; void __percpu *pptr; pptr = htab_elem_get_ptr(l, map->key_size); - for_each_possible_cpu(cpu) { - copy_map_value_long(&htab->map, dst_val + off, per_cpu_ptr(pptr, cpu)); - check_and_init_map_value(&htab->map, dst_val + off); - off += size; - } + bpf_percpu_copy_to_user(&htab->map, pptr, dst_val, size); } else { value = htab_elem_value(l, key_size); if (is_fd_htab(htab)) { @@ -2370,7 +2361,6 @@ int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value) struct htab_elem *l; void __percpu *pptr; int ret = -ENOENT; - int cpu, off = 0; u32 size; /* per_cpu areas are zero-filled and bpf programs can only @@ -2386,11 +2376,7 @@ int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value) * eviction heuristics when user space does a map walk. */ pptr = htab_elem_get_ptr(l, map->key_size); - 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; - } + bpf_percpu_copy_to_user(map, pptr, value, size); ret = 0; out: rcu_read_unlock(); diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c index c93a756e035c0..02c184d20213c 100644 --- a/kernel/bpf/local_storage.c +++ b/kernel/bpf/local_storage.c @@ -184,7 +184,7 @@ int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key, { struct bpf_cgroup_storage_map *map = map_to_storage(_map); struct bpf_cgroup_storage *storage; - int cpu, off = 0; + void __percpu *pptr; u32 size; rcu_read_lock(); @@ -199,11 +199,8 @@ int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key, * will not leak any kernel data */ size = round_up(_map->value_size, 8); - for_each_possible_cpu(cpu) { - bpf_long_memcpy(value + off, - per_cpu_ptr(storage->percpu_buf, cpu), size); - off += size; - } + pptr = storage->percpu_buf; + bpf_percpu_copy_to_user(_map, pptr, value, size); rcu_read_unlock(); return 0; } @@ -213,7 +210,7 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key, { struct bpf_cgroup_storage_map *map = map_to_storage(_map); struct bpf_cgroup_storage *storage; - int cpu, off = 0; + void __percpu *pptr; u32 size; if (map_flags != BPF_ANY && map_flags != BPF_EXIST) @@ -233,11 +230,8 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key, * so no kernel data leaks possible */ size = round_up(_map->value_size, 8); - for_each_possible_cpu(cpu) { - bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu), - value + off, size); - off += size; - } + pptr = storage->percpu_buf; + bpf_percpu_copy_from_user(_map, pptr, value, size); rcu_read_unlock(); return 0; } -- 2.50.1