From 97ebac58865dec1bca31140252386daefef1654f Mon Sep 17 00:00:00 2001 From: Tao Chen Date: Fri, 6 Jun 2025 23:02:58 +0800 Subject: [PATCH] bpf: Add show_fdinfo for perf_event After commit 1b715e1b0ec5 ("bpf: Support ->fill_link_info for perf_event") add perf_event info, we can also show the info with the method of cat /proc/[fd]/fdinfo. kprobe fdinfo: link_type: perf link_id: 10 prog_tag: bcf7977d3b93787c prog_id: 20 name: bpf_fentry_test1 offset: 0x0 missed: 0 addr: 0xffffffffa28a2904 event_type: kprobe cookie: 3735928559 uprobe fdinfo: link_type: perf link_id: 13 prog_tag: bcf7977d3b93787c prog_id: 21 name: /proc/self/exe offset: 0x63dce4 ref_ctr_offset: 0x33eee2a event_type: uprobe cookie: 3735928559 tracepoint fdinfo: link_type: perf link_id: 11 prog_tag: bcf7977d3b93787c prog_id: 22 tp_name: sched_switch event_type: tracepoint cookie: 3735928559 perf_event fdinfo: link_type: perf link_id: 12 prog_tag: bcf7977d3b93787c prog_id: 23 type: 1 config: 2 event_type: event cookie: 3735928559 Signed-off-by: Tao Chen Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250606150258.3385166-1-chen.dylane@linux.dev --- kernel/bpf/syscall.c | 120 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 97ad57ffc4041..0c267f37775b3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3795,6 +3795,32 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event, info->perf_event.kprobe.cookie = event->bpf_cookie; return 0; } + +static void bpf_perf_link_fdinfo_kprobe(const struct perf_event *event, + struct seq_file *seq) +{ + const char *name; + int err; + u32 prog_id, type; + u64 offset, addr; + unsigned long missed; + + err = bpf_get_perf_event_info(event, &prog_id, &type, &name, + &offset, &addr, &missed); + if (err) + return; + + seq_printf(seq, + "name:\t%s\n" + "offset:\t%#llx\n" + "missed:\t%lu\n" + "addr:\t%#llx\n" + "event_type:\t%s\n" + "cookie:\t%llu\n", + name, offset, missed, addr, + type == BPF_FD_TYPE_KRETPROBE ? "kretprobe" : "kprobe", + event->bpf_cookie); +} #endif #ifdef CONFIG_UPROBE_EVENTS @@ -3823,6 +3849,31 @@ static int bpf_perf_link_fill_uprobe(const struct perf_event *event, info->perf_event.uprobe.ref_ctr_offset = ref_ctr_offset; return 0; } + +static void bpf_perf_link_fdinfo_uprobe(const struct perf_event *event, + struct seq_file *seq) +{ + const char *name; + int err; + u32 prog_id, type; + u64 offset, ref_ctr_offset; + unsigned long missed; + + err = bpf_get_perf_event_info(event, &prog_id, &type, &name, + &offset, &ref_ctr_offset, &missed); + if (err) + return; + + seq_printf(seq, + "name:\t%s\n" + "offset:\t%#llx\n" + "ref_ctr_offset:\t%#llx\n" + "event_type:\t%s\n" + "cookie:\t%llu\n", + name, offset, ref_ctr_offset, + type == BPF_FD_TYPE_URETPROBE ? "uretprobe" : "uprobe", + event->bpf_cookie); +} #endif static int bpf_perf_link_fill_probe(const struct perf_event *event, @@ -3891,10 +3942,79 @@ static int bpf_perf_link_fill_link_info(const struct bpf_link *link, } } +static void bpf_perf_event_link_show_fdinfo(const struct perf_event *event, + struct seq_file *seq) +{ + seq_printf(seq, + "type:\t%u\n" + "config:\t%llu\n" + "event_type:\t%s\n" + "cookie:\t%llu\n", + event->attr.type, event->attr.config, + "event", event->bpf_cookie); +} + +static void bpf_tracepoint_link_show_fdinfo(const struct perf_event *event, + struct seq_file *seq) +{ + int err; + const char *name; + u32 prog_id; + + err = bpf_get_perf_event_info(event, &prog_id, NULL, &name, NULL, + NULL, NULL); + if (err) + return; + + seq_printf(seq, + "tp_name:\t%s\n" + "event_type:\t%s\n" + "cookie:\t%llu\n", + name, "tracepoint", event->bpf_cookie); +} + +static void bpf_probe_link_show_fdinfo(const struct perf_event *event, + struct seq_file *seq) +{ +#ifdef CONFIG_KPROBE_EVENTS + if (event->tp_event->flags & TRACE_EVENT_FL_KPROBE) + return bpf_perf_link_fdinfo_kprobe(event, seq); +#endif + +#ifdef CONFIG_UPROBE_EVENTS + if (event->tp_event->flags & TRACE_EVENT_FL_UPROBE) + return bpf_perf_link_fdinfo_uprobe(event, seq); +#endif +} + +static void bpf_perf_link_show_fdinfo(const struct bpf_link *link, + struct seq_file *seq) +{ + struct bpf_perf_link *perf_link; + const struct perf_event *event; + + perf_link = container_of(link, struct bpf_perf_link, link); + event = perf_get_event(perf_link->perf_file); + if (IS_ERR(event)) + return; + + switch (event->prog->type) { + case BPF_PROG_TYPE_PERF_EVENT: + return bpf_perf_event_link_show_fdinfo(event, seq); + case BPF_PROG_TYPE_TRACEPOINT: + return bpf_tracepoint_link_show_fdinfo(event, seq); + case BPF_PROG_TYPE_KPROBE: + return bpf_probe_link_show_fdinfo(event, seq); + default: + return; + } +} + static const struct bpf_link_ops bpf_perf_link_lops = { .release = bpf_perf_link_release, .dealloc = bpf_perf_link_dealloc, .fill_link_info = bpf_perf_link_fill_link_info, + .show_fdinfo = bpf_perf_link_show_fdinfo, }; static int bpf_perf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) -- 2.47.2