Adding new link to allow to attach program to multiple function
BTF IDs. The link is represented by struct bpf_tracing_multi_link.
To configure the link, new fields are added to bpf_attr::link_create
to pass array of BTF IDs;
struct {
__aligned_u64 ids;
__u32 cnt;
} tracing_multi;
Each BTF ID represents function (BTF_KIND_FUNC) that the link will
attach bpf program to.
We use previously added bpf_trampoline_multi_attach/detach functions
to attach/detach the link.
The linkinfo/fdinfo callbacks will be implemented in following changes.
Note this is supported only for archs (x86_64) with ftrace direct and
have single ops support.
CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS &&
CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS
Signed-off-by: Jiri Olsa <[email protected]>
---
include/linux/bpf_types.h | 1 +
include/linux/trace_events.h | 6 +++
include/uapi/linux/bpf.h | 5 ++
kernel/bpf/syscall.c | 2 +
kernel/trace/bpf_trace.c | 87 ++++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 6 +++
tools/lib/bpf/libbpf.c | 1 +
7 files changed, 108 insertions(+)
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index b13de31e163f..c1656f026790 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -155,3 +155,4 @@ BPF_LINK_TYPE(BPF_LINK_TYPE_PERF_EVENT, perf)
BPF_LINK_TYPE(BPF_LINK_TYPE_KPROBE_MULTI, kprobe_multi)
BPF_LINK_TYPE(BPF_LINK_TYPE_STRUCT_OPS, struct_ops)
BPF_LINK_TYPE(BPF_LINK_TYPE_UPROBE_MULTI, uprobe_multi)
+BPF_LINK_TYPE(BPF_LINK_TYPE_TRACING_MULTI, tracing)
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 0a2b8229b999..7a28cc824fca 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -778,6 +778,7 @@ int bpf_get_perf_event_info(const struct perf_event *event,
u32 *prog_id,
unsigned long *missed);
int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog
*prog);
int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog
*prog);
+int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr
*attr);
#else
static inline unsigned int trace_call_bpf(struct trace_event_call *call, void
*ctx)
{
@@ -830,6 +831,11 @@ bpf_uprobe_multi_link_attach(const union bpf_attr *attr,
struct bpf_prog *prog)
{
return -EOPNOTSUPP;
}
+static inline int
+bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
+{
+ return -EOPNOTSUPP;
+}
#endif
enum {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 68600972a778..7f5c51f27a36 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1180,6 +1180,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_UPROBE_MULTI = 12,
BPF_LINK_TYPE_NETKIT = 13,
BPF_LINK_TYPE_SOCKMAP = 14,
+ BPF_LINK_TYPE_TRACING_MULTI = 15,
__MAX_BPF_LINK_TYPE,
};
@@ -1863,6 +1864,10 @@ union bpf_attr {
};
__u64 expected_revision;
} cgroup;
+ struct {
+ __aligned_u64 ids;
+ __u32 cnt;
+ } tracing_multi;
};
} link_create;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index ff85a9fa080e..5892dca20b7e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5751,6 +5751,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t
uattr)
ret = bpf_iter_link_attach(attr, uattr, prog);
else if (prog->expected_attach_type == BPF_LSM_CGROUP)
ret = cgroup_bpf_link_attach(attr, prog);
+ else if (is_tracing_multi(prog->expected_attach_type))
+ ret = bpf_tracing_multi_attach(prog, attr);
else
ret = bpf_tracing_prog_attach(prog,
attr->link_create.target_fd,
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index eadaef8592a3..bfae9ec5d1b1 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -42,6 +42,7 @@
#define MAX_UPROBE_MULTI_CNT (1U << 20)
#define MAX_KPROBE_MULTI_CNT (1U << 20)
+#define MAX_TRACING_MULTI_CNT (1U << 20)
#ifdef CONFIG_MODULES
struct bpf_trace_module {
@@ -3592,3 +3593,89 @@ __bpf_kfunc int
bpf_copy_from_user_task_str_dynptr(struct bpf_dynptr *dptr, u64
}
__bpf_kfunc_end_defs();
+
+#if defined(CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS) &&
defined(CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS)
+
+static void bpf_tracing_multi_link_release(struct bpf_link *link)
+{
+ struct bpf_tracing_multi_link *tr_link =
+ container_of(link, struct bpf_tracing_multi_link, link);
+
+ WARN_ON_ONCE(bpf_trampoline_multi_detach(link->prog, tr_link));
+}
+
+static void bpf_tracing_multi_link_dealloc(struct bpf_link *link)
+{
+ struct bpf_tracing_multi_link *tr_link =
+ container_of(link, struct bpf_tracing_multi_link, link);
+
+ kfree(tr_link);
+}
+
+static const struct bpf_link_ops bpf_tracing_multi_link_lops = {
+ .release = bpf_tracing_multi_link_release,
+ .dealloc = bpf_tracing_multi_link_dealloc,
+};
+
+int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
+{
+ struct bpf_tracing_multi_link *link = NULL;
+ struct bpf_link_primer link_primer;
+ u32 cnt, *ids = NULL;
+ u32 __user *uids;
+ int err;
+
+ uids = u64_to_user_ptr(attr->link_create.tracing_multi.ids);
+ cnt = attr->link_create.tracing_multi.cnt;
+
+ if (!cnt || !uids)
+ return -EINVAL;
+ if (cnt > MAX_TRACING_MULTI_CNT)
+ return -E2BIG;
+
+ ids = kvmalloc_array(cnt, sizeof(*ids), GFP_KERNEL);
+ if (!ids)
+ return -ENOMEM;
+
+ if (copy_from_user(ids, uids, cnt * sizeof(*ids))) {
+ err = -EFAULT;
+ goto error;
+ }
+
+ link = kzalloc(struct_size(link, nodes, cnt), GFP_KERNEL);
+ if (!link) {
+ err = -ENOMEM;
+ goto error;
+ }
+
+ bpf_link_init(&link->link, BPF_LINK_TYPE_TRACING_MULTI,
+ &bpf_tracing_multi_link_lops, prog,
prog->expected_attach_type);
+
+ err = bpf_link_prime(&link->link, &link_primer);
+ if (err)
+ goto error;
+
+ link->nodes_cnt = cnt;
+
+ err = bpf_trampoline_multi_attach(prog, ids, link);
+ kvfree(ids);
+ if (err) {
+ bpf_link_cleanup(&link_primer);
+ return err;
+ }
+ return bpf_link_settle(&link_primer);
+
+error:
+ kvfree(ids);
+ kfree(link);
+ return err;
+}
+
+#else
+
+int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
+{
+ return -EOPNOTSUPP;
+}
+
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS) &&
CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS */
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 61f0fe5bc0aa..7f5c51f27a36 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1180,6 +1180,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_UPROBE_MULTI = 12,
BPF_LINK_TYPE_NETKIT = 13,
BPF_LINK_TYPE_SOCKMAP = 14,
+ BPF_LINK_TYPE_TRACING_MULTI = 15,
__MAX_BPF_LINK_TYPE,
};
@@ -1863,6 +1864,10 @@ union bpf_attr {
};
__u64 expected_revision;
} cgroup;
+ struct {
+ __aligned_u64 ids;
+ __u32 cnt;
+ } tracing_multi;
};
} link_create;
@@ -7236,6 +7241,7 @@ enum {
TCP_BPF_SOCK_OPS_CB_FLAGS = 1008, /* Get or Set TCP sock ops flags */
SK_BPF_CB_FLAGS = 1009, /* Get or set sock ops flags in socket
*/
SK_BPF_BYPASS_PROT_MEM = 1010, /* Get or Set sk->sk_bypass_prot_mem */
+
};
enum {
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1e19c7b861ec..74e579d7f310 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -156,6 +156,7 @@ static const char * const link_type_name[] = {
[BPF_LINK_TYPE_UPROBE_MULTI] = "uprobe_multi",
[BPF_LINK_TYPE_NETKIT] = "netkit",
[BPF_LINK_TYPE_SOCKMAP] = "sockmap",
+ [BPF_LINK_TYPE_TRACING_MULTI] = "tracing_multi",
};
static const char * const map_type_name[] = {
--
2.52.0
