[PATCH bpf-next v3] bpf: increase supported cgroup storage value size
From: Stanislav Fomichev <hidden>
Date: 2021-07-26 23:00:38
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Linus Torvalds
Current max cgroup storage value size is 4k (PAGE_SIZE). The other local storages accept up to 64k (BPF_LOCAL_STORAGE_MAX_VALUE_SIZE). Let's align max cgroup value size with the other storages. For percpu, the max is 32k (PCPU_MIN_UNIT_SIZE) because percpu allocator is not happy about larger values. netcnt test is extended to exercise those maximum values (non-percpu max size is close to, but not real max). v3: * refine SIZEOF_BPF_LOCAL_STORAGE_ELEM comment (Yonghong Song) * anonymous struct in percpu_net_cnt & net_cnt (Yonghong Song) * reorder free (Yonghong Song) v2: * cap max_value_size instead of BUILD_BUG_ON (Martin KaFai Lau) Cc: Martin KaFai Lau <redacted> Cc: Yonghong Song <redacted> Signed-off-by: Stanislav Fomichev <redacted> --- kernel/bpf/local_storage.c | 11 +++++- tools/testing/selftests/bpf/netcnt_common.h | 38 +++++++++++++++++---- tools/testing/selftests/bpf/test_netcnt.c | 17 ++++++--- 3 files changed, 53 insertions(+), 13 deletions(-)
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 7ed2a14dc0de..035e9e3a7132 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c@@ -1,6 +1,7 @@ //SPDX-License-Identifier: GPL-2.0 #include <linux/bpf-cgroup.h> #include <linux/bpf.h> +#include <linux/bpf_local_storage.h> #include <linux/btf.h> #include <linux/bug.h> #include <linux/filter.h>
@@ -283,9 +284,17 @@ static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key, static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr) { + __u32 max_value_size = BPF_LOCAL_STORAGE_MAX_VALUE_SIZE; int numa_node = bpf_map_attr_numa_node(attr); struct bpf_cgroup_storage_map *map; + /* percpu is bound by PCPU_MIN_UNIT_SIZE, non-percu + * is the same as other local storages. + */ + if (attr->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) + max_value_size = min_t(__u32, max_value_size, + PCPU_MIN_UNIT_SIZE); + if (attr->key_size != sizeof(struct bpf_cgroup_storage_key) && attr->key_size != sizeof(__u64)) return ERR_PTR(-EINVAL);
@@ -293,7 +302,7 @@ static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr) if (attr->value_size == 0) return ERR_PTR(-EINVAL); - if (attr->value_size > PAGE_SIZE) + if (attr->value_size > max_value_size) return ERR_PTR(-E2BIG); if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK ||
diff --git a/tools/testing/selftests/bpf/netcnt_common.h b/tools/testing/selftests/bpf/netcnt_common.h
index 81084c1c2c23..87f5b97e1932 100644
--- a/tools/testing/selftests/bpf/netcnt_common.h
+++ b/tools/testing/selftests/bpf/netcnt_common.h@@ -6,19 +6,43 @@ #define MAX_PERCPU_PACKETS 32 +/* sizeof(struct bpf_local_storage_elem): + * + * It really is about 128 bytes on x86_64, but allocate more to account for + * possible layout changes, different architectures, etc. + * The kernel will wrap up to PAGE_SIZE internally anyway. + */ +#define SIZEOF_BPF_LOCAL_STORAGE_ELEM 256 + +/* Try to estimate kernel's BPF_LOCAL_STORAGE_MAX_VALUE_SIZE: */ +#define BPF_LOCAL_STORAGE_MAX_VALUE_SIZE (0xFFFF - \ + SIZEOF_BPF_LOCAL_STORAGE_ELEM) + +#define PCPU_MIN_UNIT_SIZE 32768 + struct percpu_net_cnt { - __u64 packets; - __u64 bytes; + union { + struct { + __u64 packets; + __u64 bytes; - __u64 prev_ts; + __u64 prev_ts; - __u64 prev_packets; - __u64 prev_bytes; + __u64 prev_packets; + __u64 prev_bytes; + }; + __u8 data[PCPU_MIN_UNIT_SIZE]; + }; }; struct net_cnt { - __u64 packets; - __u64 bytes; + union { + struct { + __u64 packets; + __u64 bytes; + }; + __u8 data[BPF_LOCAL_STORAGE_MAX_VALUE_SIZE]; + }; }; #endif
diff --git a/tools/testing/selftests/bpf/test_netcnt.c b/tools/testing/selftests/bpf/test_netcnt.c
index a7b9a69f4fd5..372afccf2d17 100644
--- a/tools/testing/selftests/bpf/test_netcnt.c
+++ b/tools/testing/selftests/bpf/test_netcnt.c@@ -33,11 +33,11 @@ static int bpf_find_map(const char *test, struct bpf_object *obj, int main(int argc, char **argv) { - struct percpu_net_cnt *percpu_netcnt; + struct percpu_net_cnt *percpu_netcnt = NULL; struct bpf_cgroup_storage_key key; + struct net_cnt *netcnt = NULL; int map_fd, percpu_map_fd; int error = EXIT_FAILURE; - struct net_cnt netcnt; struct bpf_object *obj; int prog_fd, cgroup_fd; unsigned long packets;
@@ -52,6 +52,12 @@ int main(int argc, char **argv) goto err; } + netcnt = malloc(sizeof(*netcnt)); + if (!netcnt) { + printf("Not enough memory for non-per-cpu area\n"); + goto err; + } + if (bpf_prog_load(BPF_PROG, BPF_PROG_TYPE_CGROUP_SKB, &obj, &prog_fd)) { printf("Failed to load bpf program\n");
@@ -96,7 +102,7 @@ int main(int argc, char **argv) goto err; } - if (bpf_map_lookup_elem(map_fd, &key, &netcnt)) { + if (bpf_map_lookup_elem(map_fd, &key, netcnt)) { printf("Failed to lookup cgroup storage\n"); goto err; }
@@ -109,8 +115,8 @@ int main(int argc, char **argv) /* Some packets can be still in per-cpu cache, but not more than * MAX_PERCPU_PACKETS. */ - packets = netcnt.packets; - bytes = netcnt.bytes; + packets = netcnt->packets; + bytes = netcnt->bytes; for (cpu = 0; cpu < nproc; cpu++) { if (percpu_netcnt[cpu].packets > MAX_PERCPU_PACKETS) { printf("Unexpected percpu value: %llu\n",
@@ -141,6 +147,7 @@ int main(int argc, char **argv) err: cleanup_cgroup_environment(); + free(netcnt); free(percpu_netcnt); out:
--
2.32.0.432.gabb21c7263-goog