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Message-ID: <20190426001047.851643-1-kafai@fb.com>
Date: Thu, 25 Apr 2019 17:10:47 -0700
From: Martin KaFai Lau <kafai@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>
CC: Alexei Starovoitov <ast@...com>, Andrii Nakryiko <andriin@...com>,
Daniel Borkmann <daniel@...earbox.net>,
John Fastabend <john.fastabend@...il.com>,
<kernel-team@...com>, Yonghong Song <yhs@...com>
Subject: [PATCH v2 bpf-next 3/6] bpf: Support BPF_MAP_TYPE_SK_STORAGE in bpf map probing
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@...com>
---
tools/bpf/bpftool/map.c | 1 +
tools/lib/bpf/libbpf_probes.c | 74 ++++++++++++++++++++++++++++++++++-
2 files changed, 74 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 10b6c9d3e525..693ab3da37de 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -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);
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 0f25541632e3..2e26ddb005e4 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -9,6 +9,7 @@
#include <net/if.h>
#include <sys/utsname.h>
+#include <linux/btf.h>
#include <linux/filter.h>
#include <linux/kernel.h>
@@ -130,11 +131,65 @@ 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);
@@ -160,6 +215,16 @@ 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:
@@ -205,11 +270,18 @@ 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;
}
--
2.17.1
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