bpf: Show precise link_type for {uprobe,kprobe}_multi fdinfo

Alexei suggested, 'link_type' can be more precise and differentiate
for human in fdinfo. In fact BPF_LINK_TYPE_KPROBE_MULTI includes
kretprobe_multi type, the same as BPF_LINK_TYPE_UPROBE_MULTI, so we
can show it more concretely.

link_type:	kprobe_multi
link_id:	1
prog_tag:	d2b307e915f0dd37
...
link_type:	kretprobe_multi
link_id:	2
prog_tag:	ab9ea0545870781d
...
link_type:	uprobe_multi
link_id:	9
prog_tag:	e729f789e34a8eca
...
link_type:	uretprobe_multi
link_id:	10
prog_tag:	7db356c03e61a4d4

Co-developed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Link: https://lore.kernel.org/r/20250702153958.639852-1-chen.dylane@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5dd556e89cceb68235560741ee12878fc14d47c2..287c956cdbd28a14092109237cced0f1f578d634 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1702,6 +1702,7 @@ struct bpf_link {
         * link's semantics is determined by target attach hook
         */
        bool sleepable;
+       u32 flags;
        /* rcu is used before freeing, work can be used to schedule that
         * RCU-based freeing before that, so they never overlap
         */

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 56500381c28aa74a5c3e53ddca650c8d0ccd4b17..f1d9ee9717a1523df971457a3dd671daa2959366 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3228,7 +3228,14 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp)
        char prog_tag[sizeof(prog->tag) * 2 + 1] = { };
 
        if (type < ARRAY_SIZE(bpf_link_type_strs) && bpf_link_type_strs[type]) {
-               seq_printf(m, "link_type:\t%s\n", bpf_link_type_strs[type]);
+               if (link->type == BPF_LINK_TYPE_KPROBE_MULTI)
+                       seq_printf(m, "link_type:\t%s\n", link->flags == BPF_F_KPROBE_MULTI_RETURN ?
+                                  "kretprobe_multi" : "kprobe_multi");
+               else if (link->type == BPF_LINK_TYPE_UPROBE_MULTI)
+                       seq_printf(m, "link_type:\t%s\n", link->flags == BPF_F_UPROBE_MULTI_RETURN ?
+                                  "uretprobe_multi" : "uprobe_multi");
+               else
+                       seq_printf(m, "link_type:\t%s\n", bpf_link_type_strs[type]);
        } else {
                WARN_ONCE(1, "missing BPF_LINK_TYPE(...) for link type %u\n", type);
                seq_printf(m, "link_type:\t<%u>\n", type);

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0a06ea6638fe620676ccd1b8bb8274ed5c57ba54..81d7a4e5ae1540efd41c6d71b01d578b4e2c416f 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2466,7 +2466,6 @@ struct bpf_kprobe_multi_link {
        u32 cnt;
        u32 mods_cnt;
        struct module **mods;
-       u32 flags;
 };
 
 struct bpf_kprobe_multi_run_ctx {
@@ -2586,7 +2585,7 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 
        kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
        info->kprobe_multi.count = kmulti_link->cnt;
-       info->kprobe_multi.flags = kmulti_link->flags;
+       info->kprobe_multi.flags = kmulti_link->link.flags;
        info->kprobe_multi.missed = kmulti_link->fp.nmissed;
 
        if (!uaddrs)
@@ -2976,7 +2975,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
        link->addrs = addrs;
        link->cookies = cookies;
        link->cnt = cnt;
-       link->flags = flags;
+       link->link.flags = flags;
 
        if (cookies) {
                /*
@@ -3045,7 +3044,6 @@ struct bpf_uprobe_multi_link {
        struct path path;
        struct bpf_link link;
        u32 cnt;
-       u32 flags;
        struct bpf_uprobe *uprobes;
        struct task_struct *task;
 };
@@ -3109,7 +3107,7 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link,
 
        umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
        info->uprobe_multi.count = umulti_link->cnt;
-       info->uprobe_multi.flags = umulti_link->flags;
+       info->uprobe_multi.flags = umulti_link->link.flags;
        info->uprobe_multi.pid = umulti_link->task ?
                                 task_pid_nr_ns(umulti_link->task, task_active_pid_ns(current)) : 0;
 
@@ -3369,7 +3367,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
        link->uprobes = uprobes;
        link->path = path;
        link->task = task;
-       link->flags = flags;
+       link->link.flags = flags;
 
        bpf_link_init(&link->link, BPF_LINK_TYPE_UPROBE_MULTI,
                      &bpf_uprobe_multi_link_lops, prog);