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bpf: Support BPF_MAP_TYPE_SK_STORAGE in bpf map probing

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This patch supports probing for the new BPF_MAP_TYPE_SK_STORAGE.
BPF_MAP_TYPE_SK_STORAGE enforces BTF usage, so the new probe
requires to create and load a BTF also.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Martin KaFai Lau 2019-04-26 16:39:44 -07:00 committed by Alexei Starovoitov
parent 948d930e3d
commit a19f89f366
2 changed files with 74 additions and 1 deletions
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1
tools/bpf/bpftool/map.c
View file

@ -46,6 +46,7 @@ const char * const map_type_name[] = {
[BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE] = "percpu_cgroup_storage",
[BPF_MAP_TYPE_QUEUE] = "queue",
[BPF_MAP_TYPE_STACK] = "stack",
[BPF_MAP_TYPE_SK_STORAGE] = "sk_storage",
};
const size_t map_type_name_size = ARRAY_SIZE(map_type_name);

74
tools/lib/bpf/libbpf_probes.c
View file

@ -9,6 +9,7 @@
#include <net/if.h>
#include <sys/utsname.h>
#include <linux/btf.h>
#include <linux/filter.h>
#include <linux/kernel.h>
@ -131,11 +132,65 @@ bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
return errno != EINVAL && errno != EOPNOTSUPP;
}
static int load_btf(void)
{
#define BTF_INFO_ENC(kind, kind_flag, vlen) \
((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
#define BTF_TYPE_ENC(name, info, size_or_type) \
(name), (info), (size_or_type)
#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
BTF_INT_ENC(encoding, bits_offset, bits)
#define BTF_MEMBER_ENC(name, type, bits_offset) \
(name), (type), (bits_offset)
const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l";
/* struct bpf_spin_lock {
* int val;
* };
* struct val {
* int cnt;
* struct bpf_spin_lock l;
* };
*/
__u32 btf_raw_types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* struct bpf_spin_lock */ /* [2] */
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
BTF_MEMBER_ENC(15, 1, 0), /* int val; */
/* struct val */ /* [3] */
BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
};
struct btf_header btf_hdr = {
.magic = BTF_MAGIC,
.version = BTF_VERSION,
.hdr_len = sizeof(struct btf_header),
.type_len = sizeof(btf_raw_types),
.str_off = sizeof(btf_raw_types),
.str_len = sizeof(btf_str_sec),
};
__u8 raw_btf[sizeof(struct btf_header) + sizeof(btf_raw_types) +
sizeof(btf_str_sec)];
memcpy(raw_btf, &btf_hdr, sizeof(btf_hdr));
memcpy(raw_btf + sizeof(btf_hdr), btf_raw_types, sizeof(btf_raw_types));
memcpy(raw_btf + sizeof(btf_hdr) + sizeof(btf_raw_types),
btf_str_sec, sizeof(btf_str_sec));
return bpf_load_btf(raw_btf, sizeof(raw_btf), 0, 0, 0);
}
bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
{
int key_size, value_size, max_entries, map_flags;
__u32 btf_key_type_id = 0, btf_value_type_id = 0;
struct bpf_create_map_attr attr = {};
int fd = -1, fd_inner;
int fd = -1, btf_fd = -1, fd_inner;
key_size = sizeof(__u32);
value_size = sizeof(__u32);
@ -161,6 +216,16 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
case BPF_MAP_TYPE_STACK:
key_size = 0;
break;
case BPF_MAP_TYPE_SK_STORAGE:
btf_key_type_id = 1;
btf_value_type_id = 3;
value_size = 8;
max_entries = 0;
map_flags = BPF_F_NO_PREALLOC;
btf_fd = load_btf();
if (btf_fd < 0)
return false;
break;
case BPF_MAP_TYPE_UNSPEC:
case BPF_MAP_TYPE_HASH:
case BPF_MAP_TYPE_ARRAY:
@ -206,11 +271,18 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
attr.max_entries = max_entries;
attr.map_flags = map_flags;
attr.map_ifindex = ifindex;
if (btf_fd >= 0) {
attr.btf_fd = btf_fd;
attr.btf_key_type_id = btf_key_type_id;
attr.btf_value_type_id = btf_value_type_id;
}
fd = bpf_create_map_xattr(&attr);
}
if (fd >= 0)
close(fd);
if (btf_fd >= 0)
close(btf_fd);
return fd >= 0;
}