Commit 88d61607 authored by Yafang Shao's avatar Yafang Shao Committed by Alexei Starovoitov
Browse files

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: default avatarYafang Shao <laoar.shao@gmail.com>
Reviewed-by: default avatarQuentin Monnet <quentin@isovalent.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-11-laoar.shao@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 62b57e3d

tools/bpf/bpftool/link.c

+246 −1
Original line number Diff line number Diff line
@@ -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 @@ 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 = 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);