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Message-Id: <20210727222335.4029096-1-sdf@google.com>
Date: Tue, 27 Jul 2021 15:23:35 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
Stanislav Fomichev <sdf@...gle.com>,
Martin KaFai Lau <kafai@...com>, Yonghong Song <yhs@...com>
Subject: [PATCH bpf-next v4] bpf: increase supported cgroup storage value size
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).
v4:
* remove inner union (Andrii Nakryiko)
* keep net_cnt on the stack (Andrii Nakryiko)
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 <kafai@...com>
Cc: Yonghong Song <yhs@...com>
Cc: Andrii Nakryiko <andrii@...nel.org>
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
kernel/bpf/local_storage.c | 11 +++++-
tools/testing/selftests/bpf/netcnt_common.h | 38 ++++++++++++++-----
.../testing/selftests/bpf/progs/netcnt_prog.c | 8 ++--
tools/testing/selftests/bpf/test_netcnt.c | 4 +-
4 files changed, 45 insertions(+), 16 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..0ab1c88041cd 100644
--- a/tools/testing/selftests/bpf/netcnt_common.h
+++ b/tools/testing/selftests/bpf/netcnt_common.h
@@ -6,19 +6,39 @@
#define MAX_PERCPU_PACKETS 32
-struct percpu_net_cnt {
- __u64 packets;
- __u64 bytes;
+/* 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
- __u64 prev_ts;
+/* Try to estimate kernel's BPF_LOCAL_STORAGE_MAX_VALUE_SIZE: */
+#define BPF_LOCAL_STORAGE_MAX_VALUE_SIZE (0xFFFF - \
+ SIZEOF_BPF_LOCAL_STORAGE_ELEM)
- __u64 prev_packets;
- __u64 prev_bytes;
+#define PCPU_MIN_UNIT_SIZE 32768
+
+union percpu_net_cnt {
+ struct {
+ __u64 packets;
+ __u64 bytes;
+
+ __u64 prev_ts;
+
+ __u64 prev_packets;
+ __u64 prev_bytes;
+ };
+ __u8 data[PCPU_MIN_UNIT_SIZE];
};
-struct net_cnt {
- __u64 packets;
- __u64 bytes;
+union net_cnt {
+ struct {
+ __u64 packets;
+ __u64 bytes;
+ };
+ __u8 data[BPF_LOCAL_STORAGE_MAX_VALUE_SIZE];
};
#endif
diff --git a/tools/testing/selftests/bpf/progs/netcnt_prog.c b/tools/testing/selftests/bpf/progs/netcnt_prog.c
index d071adf178bd..43649bce4c54 100644
--- a/tools/testing/selftests/bpf/progs/netcnt_prog.c
+++ b/tools/testing/selftests/bpf/progs/netcnt_prog.c
@@ -13,21 +13,21 @@
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
__type(key, struct bpf_cgroup_storage_key);
- __type(value, struct percpu_net_cnt);
+ __type(value, union percpu_net_cnt);
} percpu_netcnt SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_CGROUP_STORAGE);
__type(key, struct bpf_cgroup_storage_key);
- __type(value, struct net_cnt);
+ __type(value, union net_cnt);
} netcnt SEC(".maps");
SEC("cgroup/skb")
int bpf_nextcnt(struct __sk_buff *skb)
{
- struct percpu_net_cnt *percpu_cnt;
+ union percpu_net_cnt *percpu_cnt;
char fmt[] = "%d %llu %llu\n";
- struct net_cnt *cnt;
+ union net_cnt *cnt;
__u64 ts, dt;
int ret;
diff --git a/tools/testing/selftests/bpf/test_netcnt.c b/tools/testing/selftests/bpf/test_netcnt.c
index a7b9a69f4fd5..4990a99e7381 100644
--- a/tools/testing/selftests/bpf/test_netcnt.c
+++ b/tools/testing/selftests/bpf/test_netcnt.c
@@ -33,14 +33,14 @@ static int bpf_find_map(const char *test, struct bpf_object *obj,
int main(int argc, char **argv)
{
- struct percpu_net_cnt *percpu_netcnt;
+ union percpu_net_cnt *percpu_netcnt;
struct bpf_cgroup_storage_key key;
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;
+ union net_cnt netcnt;
unsigned long bytes;
int cpu, nproc;
__u32 prog_cnt;
--
2.32.0.554.ge1b32706d8-goog
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