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Message-ID: <20250627082252.431209-1-chen.dylane@linux.dev>
Date: Fri, 27 Jun 2025 16:22:50 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: ast@...nel.org,
daniel@...earbox.net,
john.fastabend@...il.com,
andrii@...nel.org,
martin.lau@...ux.dev,
eddyz87@...il.com,
song@...nel.org,
yonghong.song@...ux.dev,
kpsingh@...nel.org,
sdf@...ichev.me,
haoluo@...gle.com,
jolsa@...nel.org,
mattbobrowski@...gle.com,
rostedt@...dmis.org,
mhiramat@...nel.org,
mathieu.desnoyers@...icios.com
Cc: bpf@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org,
Tao Chen <chen.dylane@...ux.dev>
Subject: [PATCH bpf-next v6 1/3] 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
As Andrii suggested attach_type can be recorded in bpf_link, there is
still a 6 byte hole in bpf_link, we can fill the hole with attach_type
soon.
Co-authored-by: Jiri Olsa <jolsa@...nel.org>
Signed-off-by: Tao Chen <chen.dylane@...ux.dev>
---
include/linux/bpf.h | 1 +
kernel/bpf/syscall.c | 9 ++++++++-
kernel/trace/bpf_trace.c | 10 ++++------
3 files changed, 13 insertions(+), 7 deletions(-)
Change list:
v5 -> v6:
- Move flags into bpf_link to get retprobe info
directly.(Alexei, Jiri)
v5:
https://lore.kernel.org/bpf/20250623134342.227347-1-chen.dylane@linux.dev
v4 -> v5:
- Add patch1 to show precise link_type for
{uprobe,kprobe}_multi.(Alexei)
- patch2,3 just remove type field, which will be showed in
link_type
v4:
https://lore.kernel.org/bpf/20250619034257.70520-1-chen.dylane@linux.dev
v3 -> v4:
- use %pS to print func info.(Alexei)
v3:
https://lore.kernel.org/bpf/20250616130233.451439-1-chen.dylane@linux.dev
v2 -> v3:
- show info in one line for multi events.(Jiri)
v2:
https://lore.kernel.org/bpf/20250615150514.418581-1-chen.dylane@linux.dev
v1 -> v2:
- replace 'func_cnt' with 'uprobe_cnt'.(Andrii)
- print func name is more readable and security for kprobe_multi.(Alexei)
v1:
https://lore.kernel.org/bpf/20250612115556.295103-1-chen.dylane@linux.dev
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5b25d278409..3d8fecc9b17 100644
--- 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 :8;
/* 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 51ba1a7aa43..e6eea594f1c 100644
--- 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 24b94870b50..85f07f662fe 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2469,7 +2469,6 @@ struct bpf_kprobe_multi_link {
u32 cnt;
u32 mods_cnt;
struct module **mods;
- u32 flags;
};
struct bpf_kprobe_multi_run_ctx {
@@ -2589,7 +2588,7 @@ 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)
@@ -2979,7 +2978,7 @@ 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) {
/*
@@ -3048,7 +3047,6 @@ struct bpf_uprobe_multi_link {
struct path path;
struct bpf_link link;
u32 cnt;
- u32 flags;
struct bpf_uprobe *uprobes;
struct task_struct *task;
};
@@ -3112,7 +3110,7 @@ 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;
@@ -3372,7 +3370,7 @@ 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);
--
2.48.1
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