Enhance bpftool to display comprehensive information about exposed
perf_event links, covering uprobe, kprobe, tracepoint, and generic perf
event. The resulting output will include the following details:
$ tools/bpf/bpftool/bpftool link show
3: perf_event prog 14
event software:cpu-clock
bpf_cookie 0
pids perf_event(19483)
4: perf_event prog 14
event hw-cache:LLC-load-misses
bpf_cookie 0
pids perf_event(19483)
5: perf_event prog 14
event hardware:cpu-cycles
bpf_cookie 0
pids perf_event(19483)
6: perf_event prog 19
tracepoint sched_switch
bpf_cookie 0
pids tracepoint(20947)
7: perf_event prog 26
uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
bpf_cookie 0
pids uprobe(21973)
8: perf_event prog 27
uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
bpf_cookie 0
pids uprobe(21973)
10: perf_event prog 43
kprobe ffffffffb70a9660 kernel_clone
bpf_cookie 0
pids kprobe(35275)
11: perf_event prog 41
kretprobe ffffffffb70a9660 kernel_clone
bpf_cookie 0
pids kprobe(35275)
$ tools/bpf/bpftool/bpftool link show -j
[{"id":3,"type":"perf_event","prog_id":14,"event_type":"software","event_config":"cpu-clock","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":4,"type":"perf_event","prog_id":14,"event_type":"hw-cache","event_config":"LLC-load-misses","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":5,"type":"perf_event","prog_id":14,"event_type":"hardware","event_config":"cpu-cycles","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":6,"type":"perf_event","prog_id":19,"tracepoint":"sched_switch","bpf_cookie":0,"pids":[{"pid":20947,"comm":"tracepoint"}]},{"id":7,"type":"perf_event","prog_id":26,"retprobe":false,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":8,"type":"perf_event","prog_id":27,"retprobe":true,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":10,"type":"perf_event","prog_id":43,"retprobe":false,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]},{"id":11,"type":"perf_event","prog_id":41,"retprobe":true,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]}]
For generic perf events, the displayed information in bpftool is limited to
the type and configuration, while other attributes such as sample_period,
sample_freq, etc., are not included.
The kernel function address won't be exposed if it is not permitted by
kptr_restrict. The result as follows when kptr_restrict is 2.
$ tools/bpf/bpftool/bpftool link show
3: perf_event prog 14
event software:cpu-clock
4: perf_event prog 14
event hw-cache:LLC-load-misses
5: perf_event prog 14
event hardware:cpu-cycles
6: perf_event prog 19
tracepoint sched_switch
7: perf_event prog 26
uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
8: perf_event prog 27
uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
10: perf_event prog 43
kprobe kernel_clone
11: perf_event prog 41
kretprobe kernel_clone
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
tools/bpf/bpftool/link.c | 247 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 246 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index ba67ea9d77fb..7c4c9fc45f63 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -17,6 +17,8 @@
#include "main.h"
#include "xlated_dumper.h"
+#define PERF_HW_CACHE_LEN 128
+
static struct hashmap *link_table;
static struct dump_data dd = {};
@@ -279,6 +281,110 @@ show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
jsonw_end_array(json_wtr);
}
+static void
+show_perf_event_kprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
+{
+ jsonw_bool_field(wtr, "retprobe", info->perf_event.type == BPF_PERF_EVENT_KRETPROBE);
+ jsonw_uint_field(wtr, "addr", info->perf_event.kprobe.addr);
+ jsonw_string_field(wtr, "func",
+ u64_to_ptr(info->perf_event.kprobe.func_name));
+ jsonw_uint_field(wtr, "offset", info->perf_event.kprobe.offset);
+}
+
+static void
+show_perf_event_uprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
+{
+ jsonw_bool_field(wtr, "retprobe", info->perf_event.type == BPF_PERF_EVENT_URETPROBE);
+ jsonw_string_field(wtr, "file",
+ u64_to_ptr(info->perf_event.uprobe.file_name));
+ jsonw_uint_field(wtr, "offset", info->perf_event.uprobe.offset);
+}
+
+static void
+show_perf_event_tracepoint_json(struct bpf_link_info *info, json_writer_t *wtr)
+{
+ jsonw_string_field(wtr, "tracepoint",
+ u64_to_ptr(info->perf_event.tracepoint.tp_name));
+}
+
+static char *perf_config_hw_cache_str(__u64 config)
+{
+ const char *hw_cache, *result, *op;
+ char *str = malloc(PERF_HW_CACHE_LEN);
+
+ if (!str) {
+ p_err("mem alloc failed");
+ return NULL;
+ }
+
+ hw_cache = perf_event_name(evsel__hw_cache, config & 0xff);
+ if (hw_cache)
+ snprintf(str, PERF_HW_CACHE_LEN, "%s-", hw_cache);
+ else
+ snprintf(str, PERF_HW_CACHE_LEN, "%lld-", config & 0xff);
+
+ op = perf_event_name(evsel__hw_cache_op, (config >> 8) & 0xff);
+ if (op)
+ snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
+ "%s-", op);
+ else
+ snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
+ "%lld-", (config >> 8) & 0xff);
+
+ result = perf_event_name(evsel__hw_cache_result, config >> 16);
+ if (result)
+ snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
+ "%s", result);
+ else
+ snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
+ "%lld", config >> 16);
+ return str;
+}
+
+static const char *perf_config_str(__u32 type, __u64 config)
+{
+ const char *perf_config;
+
+ switch (type) {
+ case PERF_TYPE_HARDWARE:
+ perf_config = perf_event_name(event_symbols_hw, config);
+ break;
+ case PERF_TYPE_SOFTWARE:
+ perf_config = perf_event_name(event_symbols_sw, config);
+ break;
+ case PERF_TYPE_HW_CACHE:
+ perf_config = perf_config_hw_cache_str(config);
+ break;
+ default:
+ perf_config = NULL;
+ break;
+ }
+ return perf_config;
+}
+
+static void
+show_perf_event_event_json(struct bpf_link_info *info, json_writer_t *wtr)
+{
+ __u64 config = info->perf_event.event.config;
+ __u32 type = info->perf_event.event.type;
+ const char *perf_type, *perf_config;
+
+ perf_type = perf_event_name(perf_type_name, type);
+ if (perf_type)
+ jsonw_string_field(wtr, "event_type", perf_type);
+ else
+ jsonw_uint_field(wtr, "event_type", type);
+
+ perf_config = perf_config_str(type, config);
+ if (perf_config)
+ jsonw_string_field(wtr, "event_config", perf_config);
+ else
+ jsonw_uint_field(wtr, "event_config", config);
+
+ if (type == PERF_TYPE_HW_CACHE && perf_config)
+ free((void *)perf_config);
+}
+
static int show_link_close_json(int fd, struct bpf_link_info *info)
{
struct bpf_prog_info prog_info;
@@ -334,6 +440,26 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
case BPF_LINK_TYPE_KPROBE_MULTI:
show_kprobe_multi_json(info, json_wtr);
break;
+ case BPF_LINK_TYPE_PERF_EVENT:
+ switch (info->perf_event.type) {
+ case BPF_PERF_EVENT_EVENT:
+ show_perf_event_event_json(info, json_wtr);
+ break;
+ case BPF_PERF_EVENT_TRACEPOINT:
+ show_perf_event_tracepoint_json(info, json_wtr);
+ break;
+ case BPF_PERF_EVENT_KPROBE:
+ case BPF_PERF_EVENT_KRETPROBE:
+ show_perf_event_kprobe_json(info, json_wtr);
+ break;
+ case BPF_PERF_EVENT_UPROBE:
+ case BPF_PERF_EVENT_URETPROBE:
+ show_perf_event_uprobe_json(info, json_wtr);
+ break;
+ default:
+ break;
+ }
+ break;
default:
break;
}
@@ -505,6 +631,75 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
}
}
+static void show_perf_event_kprobe_plain(struct bpf_link_info *info)
+{
+ const char *buf;
+
+ buf = (const char *)u64_to_ptr(info->perf_event.kprobe.func_name);
+ if (buf[0] == '\0' && !info->perf_event.kprobe.addr)
+ return;
+
+ if (info->perf_event.type == BPF_PERF_EVENT_KRETPROBE)
+ printf("\n\tkretprobe ");
+ else
+ printf("\n\tkprobe ");
+ if (info->perf_event.kprobe.addr)
+ printf("%llx ", info->perf_event.kprobe.addr);
+ printf("%s", buf);
+ if (info->perf_event.kprobe.offset)
+ printf("+%#x", info->perf_event.kprobe.offset);
+ printf(" ");
+}
+
+static void show_perf_event_uprobe_plain(struct bpf_link_info *info)
+{
+ const char *buf;
+
+ buf = (const char *)u64_to_ptr(info->perf_event.uprobe.file_name);
+ if (buf[0] == '\0')
+ return;
+
+ if (info->perf_event.type == BPF_PERF_EVENT_URETPROBE)
+ printf("\n\turetprobe ");
+ else
+ printf("\n\tuprobe ");
+ printf("%s+%#x ", buf, info->perf_event.uprobe.offset);
+}
+
+static void show_perf_event_tracepoint_plain(struct bpf_link_info *info)
+{
+ const char *buf;
+
+ buf = (const char *)u64_to_ptr(info->perf_event.tracepoint.tp_name);
+ if (buf[0] == '\0')
+ return;
+
+ printf("\n\ttracepoint %s ", buf);
+}
+
+static void show_perf_event_event_plain(struct bpf_link_info *info)
+{
+ __u64 config = info->perf_event.event.config;
+ __u32 type = info->perf_event.event.type;
+ const char *perf_type, *perf_config;
+
+ printf("\n\tevent ");
+ perf_type = perf_event_name(perf_type_name, type);
+ if (perf_type)
+ printf("%s:", perf_type);
+ else
+ printf("%u :", type);
+
+ perf_config = perf_config_str(type, config);
+ if (perf_config)
+ printf("%s ", perf_config);
+ else
+ printf("%llu ", config);
+
+ if (type == PERF_TYPE_HW_CACHE && perf_config)
+ free((void *)perf_config);
+}
+
static int show_link_close_plain(int fd, struct bpf_link_info *info)
{
struct bpf_prog_info prog_info;
@@ -553,6 +748,26 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
case BPF_LINK_TYPE_KPROBE_MULTI:
show_kprobe_multi_plain(info);
break;
+ case BPF_LINK_TYPE_PERF_EVENT:
+ switch (info->perf_event.type) {
+ case BPF_PERF_EVENT_EVENT:
+ show_perf_event_event_plain(info);
+ break;
+ case BPF_PERF_EVENT_TRACEPOINT:
+ show_perf_event_tracepoint_plain(info);
+ break;
+ case BPF_PERF_EVENT_KPROBE:
+ case BPF_PERF_EVENT_KRETPROBE:
+ show_perf_event_kprobe_plain(info);
+ break;
+ case BPF_PERF_EVENT_UPROBE:
+ case BPF_PERF_EVENT_URETPROBE:
+ show_perf_event_uprobe_plain(info);
+ break;
+ default:
+ break;
+ }
+ break;
default:
break;
}
@@ -575,11 +790,12 @@ static int do_show_link(int fd)
struct bpf_link_info info;
__u32 len = sizeof(info);
__u64 *addrs = NULL;
- char buf[256];
+ char buf[PATH_MAX];
int count;
int err;
memset(&info, 0, sizeof(info));
+ buf[0] = '\0';
again:
err = bpf_link_get_info_by_fd(fd, &info, &len);
if (err) {
@@ -614,6 +830,35 @@ static int do_show_link(int fd)
goto again;
}
}
+ if (info.type == BPF_LINK_TYPE_PERF_EVENT) {
+ switch (info.perf_event.type) {
+ case BPF_PERF_EVENT_TRACEPOINT:
+ if (!info.perf_event.tracepoint.tp_name) {
+ info.perf_event.tracepoint.tp_name = (unsigned long)&buf;
+ info.perf_event.tracepoint.name_len = sizeof(buf);
+ goto again;
+ }
+ break;
+ case BPF_PERF_EVENT_KPROBE:
+ case BPF_PERF_EVENT_KRETPROBE:
+ if (!info.perf_event.kprobe.func_name) {
+ info.perf_event.kprobe.func_name = (unsigned long)&buf;
+ info.perf_event.kprobe.name_len = sizeof(buf);
+ goto again;
+ }
+ break;
+ case BPF_PERF_EVENT_UPROBE:
+ case BPF_PERF_EVENT_URETPROBE:
+ if (!info.perf_event.uprobe.file_name) {
+ info.perf_event.uprobe.file_name = (unsigned long)&buf;
+ info.perf_event.uprobe.name_len = sizeof(buf);
+ goto again;
+ }
+ break;
+ default:
+ break;
+ }
+ }
if (json_output)
show_link_close_json(fd, &info);
--
2.39.3
