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 btf_ids; /* addresses to attach */
__u32 btf_ids_cnt; /* addresses count */
} 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.
Signed-off-by: Jiri Olsa <[email protected]>
---
include/linux/trace_events.h | 6 ++
include/uapi/linux/bpf.h | 5 ++
kernel/bpf/syscall.c | 2 +
kernel/trace/bpf_trace.c | 105 +++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 5 ++
5 files changed, 123 insertions(+)
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 3690221ba3d8..6ea2f30728de 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..010785246576 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 btf_ids; /* addresses to
attach */
+ __u32 btf_ids_cnt; /* addresses
count */
+ } tracing_multi;
};
} link_create;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2f8932addf96..39217c96e1df 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5743,6 +5743,8 @@ 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 f7baeb8278ca..82e625aa04e8 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3593,3 +3593,108 @@ __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);
+
+ 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 void bpf_tracing_multi_link_show_fdinfo(const struct bpf_link *link,
+ struct seq_file *seq)
+{
+ struct bpf_tracing_multi_link *tr_link =
+ container_of(link, struct bpf_tracing_multi_link, link);
+
+ seq_printf(seq, "attach_type:\t%d\n", tr_link->attach_type);
+}
+
+static int bpf_tracing_multi_link_fill_link_info(const struct bpf_link *link,
+ struct bpf_link_info *info)
+{
+ struct bpf_tracing_multi_link *tr_link =
+ container_of(link, struct bpf_tracing_multi_link, link);
+
+ info->tracing.attach_type = tr_link->attach_type;
+ return 0;
+}
+
+static const struct bpf_link_ops bpf_tracing_multi_link_lops = {
+ .release = bpf_tracing_multi_link_release,
+ .dealloc = bpf_tracing_multi_link_dealloc,
+ .show_fdinfo = bpf_tracing_multi_link_show_fdinfo,
+ .fill_link_info = bpf_tracing_multi_link_fill_link_info,
+};
+
+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.btf_ids);
+ cnt = attr->link_create.tracing_multi.btf_ids_cnt;
+
+ if (!cnt || !uids)
+ return -EINVAL;
+
+ 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;
+ }
+
+ link->nodes_cnt = cnt;
+
+ 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;
+
+ 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..f54e830d9aae 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 btf_ids; /* addresses to
attach */
+ __u32 btf_ids_cnt; /* addresses
count */
+ } tracing_multi;
};
} link_create;
--
2.52.0
