bpftool: Show perf link info

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@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-11-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index 8e4d9176a6e8568dab6438ce908637837a4da819..65a168df63bc134f4cf17c2b83600fd6fd2dff51 100644 (file)
--- 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 = 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 = 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 = 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 @@ again:
                        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 = ptr_to_u64(&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 = ptr_to_u64(&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 = ptr_to_u64(&buf);
+                               info.perf_event.uprobe.name_len = sizeof(buf);
+                               goto again;
+                       }
+                       break;
+               default:
+                       break;
+               }
+       }
 
        if (json_output)
                show_link_close_json(fd, &info);