xref: /linux/tools/bpf/bpftool/link.c (revision 07fdad3a93756b872da7b53647715c48d0f4a2d0)
1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 /* Copyright (C) 2020 Facebook */
3 
4 #include <errno.h>
5 #include <linux/err.h>
6 #include <linux/netfilter.h>
7 #include <linux/netfilter_arp.h>
8 #include <linux/perf_event.h>
9 #include <net/if.h>
10 #include <stdio.h>
11 #include <unistd.h>
12 
13 #include <bpf/bpf.h>
14 #include <bpf/hashmap.h>
15 
16 #include "json_writer.h"
17 #include "main.h"
18 #include "xlated_dumper.h"
19 
20 #define PERF_HW_CACHE_LEN 128
21 
22 static struct hashmap *link_table;
23 static struct dump_data dd;
24 
25 static const char *perf_type_name[PERF_TYPE_MAX] = {
26 	[PERF_TYPE_HARDWARE]			= "hardware",
27 	[PERF_TYPE_SOFTWARE]			= "software",
28 	[PERF_TYPE_TRACEPOINT]			= "tracepoint",
29 	[PERF_TYPE_HW_CACHE]			= "hw-cache",
30 	[PERF_TYPE_RAW]				= "raw",
31 	[PERF_TYPE_BREAKPOINT]			= "breakpoint",
32 };
33 
34 const char *event_symbols_hw[PERF_COUNT_HW_MAX] = {
35 	[PERF_COUNT_HW_CPU_CYCLES]		= "cpu-cycles",
36 	[PERF_COUNT_HW_INSTRUCTIONS]		= "instructions",
37 	[PERF_COUNT_HW_CACHE_REFERENCES]	= "cache-references",
38 	[PERF_COUNT_HW_CACHE_MISSES]		= "cache-misses",
39 	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= "branch-instructions",
40 	[PERF_COUNT_HW_BRANCH_MISSES]		= "branch-misses",
41 	[PERF_COUNT_HW_BUS_CYCLES]		= "bus-cycles",
42 	[PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= "stalled-cycles-frontend",
43 	[PERF_COUNT_HW_STALLED_CYCLES_BACKEND]	= "stalled-cycles-backend",
44 	[PERF_COUNT_HW_REF_CPU_CYCLES]		= "ref-cycles",
45 };
46 
47 const char *event_symbols_sw[PERF_COUNT_SW_MAX] = {
48 	[PERF_COUNT_SW_CPU_CLOCK]		= "cpu-clock",
49 	[PERF_COUNT_SW_TASK_CLOCK]		= "task-clock",
50 	[PERF_COUNT_SW_PAGE_FAULTS]		= "page-faults",
51 	[PERF_COUNT_SW_CONTEXT_SWITCHES]	= "context-switches",
52 	[PERF_COUNT_SW_CPU_MIGRATIONS]		= "cpu-migrations",
53 	[PERF_COUNT_SW_PAGE_FAULTS_MIN]		= "minor-faults",
54 	[PERF_COUNT_SW_PAGE_FAULTS_MAJ]		= "major-faults",
55 	[PERF_COUNT_SW_ALIGNMENT_FAULTS]	= "alignment-faults",
56 	[PERF_COUNT_SW_EMULATION_FAULTS]	= "emulation-faults",
57 	[PERF_COUNT_SW_DUMMY]			= "dummy",
58 	[PERF_COUNT_SW_BPF_OUTPUT]		= "bpf-output",
59 	[PERF_COUNT_SW_CGROUP_SWITCHES]		= "cgroup-switches",
60 };
61 
62 const char *evsel__hw_cache[PERF_COUNT_HW_CACHE_MAX] = {
63 	[PERF_COUNT_HW_CACHE_L1D]		= "L1-dcache",
64 	[PERF_COUNT_HW_CACHE_L1I]		= "L1-icache",
65 	[PERF_COUNT_HW_CACHE_LL]		= "LLC",
66 	[PERF_COUNT_HW_CACHE_DTLB]		= "dTLB",
67 	[PERF_COUNT_HW_CACHE_ITLB]		= "iTLB",
68 	[PERF_COUNT_HW_CACHE_BPU]		= "branch",
69 	[PERF_COUNT_HW_CACHE_NODE]		= "node",
70 };
71 
72 const char *evsel__hw_cache_op[PERF_COUNT_HW_CACHE_OP_MAX] = {
73 	[PERF_COUNT_HW_CACHE_OP_READ]		= "load",
74 	[PERF_COUNT_HW_CACHE_OP_WRITE]		= "store",
75 	[PERF_COUNT_HW_CACHE_OP_PREFETCH]	= "prefetch",
76 };
77 
78 const char *evsel__hw_cache_result[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
79 	[PERF_COUNT_HW_CACHE_RESULT_ACCESS]	= "refs",
80 	[PERF_COUNT_HW_CACHE_RESULT_MISS]	= "misses",
81 };
82 
83 #define perf_event_name(array, id) ({			\
84 	const char *event_str = NULL;			\
85 							\
86 	if ((id) < ARRAY_SIZE(array))			\
87 		event_str = array[id];			\
88 	event_str;					\
89 })
90 
91 static int link_parse_fd(int *argc, char ***argv)
92 {
93 	int fd;
94 
95 	if (is_prefix(**argv, "id")) {
96 		unsigned int id;
97 		char *endptr;
98 
99 		NEXT_ARGP();
100 
101 		id = strtoul(**argv, &endptr, 0);
102 		if (*endptr) {
103 			p_err("can't parse %s as ID", **argv);
104 			return -1;
105 		}
106 		NEXT_ARGP();
107 
108 		fd = bpf_link_get_fd_by_id(id);
109 		if (fd < 0)
110 			p_err("failed to get link with ID %u: %s", id, strerror(errno));
111 		return fd;
112 	} else if (is_prefix(**argv, "pinned")) {
113 		char *path;
114 
115 		NEXT_ARGP();
116 
117 		path = **argv;
118 		NEXT_ARGP();
119 
120 		return open_obj_pinned_any(path, BPF_OBJ_LINK, NULL);
121 	}
122 
123 	p_err("expected 'id' or 'pinned', got: '%s'?", **argv);
124 	return -1;
125 }
126 
127 static void
128 show_link_header_json(struct bpf_link_info *info, json_writer_t *wtr)
129 {
130 	const char *link_type_str;
131 
132 	jsonw_uint_field(wtr, "id", info->id);
133 	link_type_str = libbpf_bpf_link_type_str(info->type);
134 	if (link_type_str)
135 		jsonw_string_field(wtr, "type", link_type_str);
136 	else
137 		jsonw_uint_field(wtr, "type", info->type);
138 
139 	jsonw_uint_field(json_wtr, "prog_id", info->prog_id);
140 }
141 
142 static void show_link_attach_type_json(__u32 attach_type, json_writer_t *wtr)
143 {
144 	const char *attach_type_str;
145 
146 	attach_type_str = libbpf_bpf_attach_type_str(attach_type);
147 	if (attach_type_str)
148 		jsonw_string_field(wtr, "attach_type", attach_type_str);
149 	else
150 		jsonw_uint_field(wtr, "attach_type", attach_type);
151 }
152 
153 static void show_link_ifindex_json(__u32 ifindex, json_writer_t *wtr)
154 {
155 	char devname[IF_NAMESIZE] = "(unknown)";
156 
157 	if (ifindex)
158 		if_indextoname(ifindex, devname);
159 	else
160 		snprintf(devname, sizeof(devname), "(detached)");
161 	jsonw_string_field(wtr, "devname", devname);
162 	jsonw_uint_field(wtr, "ifindex", ifindex);
163 }
164 
165 static bool is_iter_map_target(const char *target_name)
166 {
167 	return strcmp(target_name, "bpf_map_elem") == 0 ||
168 	       strcmp(target_name, "bpf_sk_storage_map") == 0;
169 }
170 
171 static bool is_iter_cgroup_target(const char *target_name)
172 {
173 	return strcmp(target_name, "cgroup") == 0;
174 }
175 
176 static const char *cgroup_order_string(__u32 order)
177 {
178 	switch (order) {
179 	case BPF_CGROUP_ITER_ORDER_UNSPEC:
180 		return "order_unspec";
181 	case BPF_CGROUP_ITER_SELF_ONLY:
182 		return "self_only";
183 	case BPF_CGROUP_ITER_DESCENDANTS_PRE:
184 		return "descendants_pre";
185 	case BPF_CGROUP_ITER_DESCENDANTS_POST:
186 		return "descendants_post";
187 	case BPF_CGROUP_ITER_ANCESTORS_UP:
188 		return "ancestors_up";
189 	default: /* won't happen */
190 		return "unknown";
191 	}
192 }
193 
194 static bool is_iter_task_target(const char *target_name)
195 {
196 	return strcmp(target_name, "task") == 0 ||
197 		strcmp(target_name, "task_file") == 0 ||
198 		strcmp(target_name, "task_vma") == 0;
199 }
200 
201 static void show_iter_json(struct bpf_link_info *info, json_writer_t *wtr)
202 {
203 	const char *target_name = u64_to_ptr(info->iter.target_name);
204 
205 	jsonw_string_field(wtr, "target_name", target_name);
206 
207 	if (is_iter_map_target(target_name))
208 		jsonw_uint_field(wtr, "map_id", info->iter.map.map_id);
209 	else if (is_iter_task_target(target_name)) {
210 		if (info->iter.task.tid)
211 			jsonw_uint_field(wtr, "tid", info->iter.task.tid);
212 		else if (info->iter.task.pid)
213 			jsonw_uint_field(wtr, "pid", info->iter.task.pid);
214 	}
215 
216 	if (is_iter_cgroup_target(target_name)) {
217 		jsonw_lluint_field(wtr, "cgroup_id", info->iter.cgroup.cgroup_id);
218 		jsonw_string_field(wtr, "order",
219 				   cgroup_order_string(info->iter.cgroup.order));
220 	}
221 }
222 
223 void netfilter_dump_json(const struct bpf_link_info *info, json_writer_t *wtr)
224 {
225 	jsonw_uint_field(json_wtr, "pf",
226 			 info->netfilter.pf);
227 	jsonw_uint_field(json_wtr, "hook",
228 			 info->netfilter.hooknum);
229 	jsonw_int_field(json_wtr, "prio",
230 			 info->netfilter.priority);
231 	jsonw_uint_field(json_wtr, "flags",
232 			 info->netfilter.flags);
233 }
234 
235 static int get_prog_info(int prog_id, struct bpf_prog_info *info)
236 {
237 	__u32 len = sizeof(*info);
238 	int err, prog_fd;
239 
240 	prog_fd = bpf_prog_get_fd_by_id(prog_id);
241 	if (prog_fd < 0)
242 		return prog_fd;
243 
244 	memset(info, 0, sizeof(*info));
245 	err = bpf_prog_get_info_by_fd(prog_fd, info, &len);
246 	if (err)
247 		p_err("can't get prog info: %s", strerror(errno));
248 	close(prog_fd);
249 	return err;
250 }
251 
252 struct addr_cookie {
253 	__u64 addr;
254 	__u64 cookie;
255 };
256 
257 static int cmp_addr_cookie(const void *A, const void *B)
258 {
259 	const struct addr_cookie *a = A, *b = B;
260 
261 	if (a->addr == b->addr)
262 		return 0;
263 	return a->addr < b->addr ? -1 : 1;
264 }
265 
266 static struct addr_cookie *
267 get_addr_cookie_array(__u64 *addrs, __u64 *cookies, __u32 count)
268 {
269 	struct addr_cookie *data;
270 	__u32 i;
271 
272 	data = calloc(count, sizeof(data[0]));
273 	if (!data) {
274 		p_err("mem alloc failed");
275 		return NULL;
276 	}
277 	for (i = 0; i < count; i++) {
278 		data[i].addr = addrs[i];
279 		data[i].cookie = cookies[i];
280 	}
281 	qsort(data, count, sizeof(data[0]), cmp_addr_cookie);
282 	return data;
283 }
284 
285 static bool is_x86_ibt_enabled(void)
286 {
287 #if defined(__x86_64__)
288 	struct kernel_config_option options[] = {
289 		{ "CONFIG_X86_KERNEL_IBT", },
290 	};
291 	char *values[ARRAY_SIZE(options)] = { };
292 	bool ret;
293 
294 	if (read_kernel_config(options, ARRAY_SIZE(options), values, NULL))
295 		return false;
296 
297 	ret = !!values[0];
298 	free(values[0]);
299 	return ret;
300 #else
301 	return false;
302 #endif
303 }
304 
305 static bool
306 symbol_matches_target(__u64 sym_addr, __u64 target_addr, bool is_ibt_enabled)
307 {
308 	if (sym_addr == target_addr)
309 		return true;
310 
311 	/*
312 	 * On x86_64 architectures with CET (Control-flow Enforcement Technology),
313 	 * function entry points have a 4-byte 'endbr' instruction prefix.
314 	 * This causes kprobe hooks to target the address *after* 'endbr'
315 	 * (symbol address + 4), preserving the CET instruction.
316 	 * Here we check if the symbol address matches the hook target address
317 	 * minus 4, indicating a CET-enabled function entry point.
318 	 */
319 	if (is_ibt_enabled && sym_addr == target_addr - 4)
320 		return true;
321 
322 	return false;
323 }
324 
325 static void
326 show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
327 {
328 	struct addr_cookie *data;
329 	__u32 i, j = 0;
330 	bool is_ibt_enabled;
331 
332 	jsonw_bool_field(json_wtr, "retprobe",
333 			 info->kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN);
334 	jsonw_uint_field(json_wtr, "func_cnt", info->kprobe_multi.count);
335 	jsonw_uint_field(json_wtr, "missed", info->kprobe_multi.missed);
336 	jsonw_name(json_wtr, "funcs");
337 	jsonw_start_array(json_wtr);
338 	data = get_addr_cookie_array(u64_to_ptr(info->kprobe_multi.addrs),
339 				     u64_to_ptr(info->kprobe_multi.cookies),
340 				     info->kprobe_multi.count);
341 	if (!data)
342 		return;
343 
344 	/* Load it once for all. */
345 	if (!dd.sym_count)
346 		kernel_syms_load(&dd);
347 	if (!dd.sym_count)
348 		goto error;
349 
350 	is_ibt_enabled = is_x86_ibt_enabled();
351 	for (i = 0; i < dd.sym_count; i++) {
352 		if (!symbol_matches_target(dd.sym_mapping[i].address,
353 					   data[j].addr, is_ibt_enabled))
354 			continue;
355 		jsonw_start_object(json_wtr);
356 		jsonw_uint_field(json_wtr, "addr", (unsigned long)data[j].addr);
357 		jsonw_string_field(json_wtr, "func", dd.sym_mapping[i].name);
358 		/* Print null if it is vmlinux */
359 		if (dd.sym_mapping[i].module[0] == '\0') {
360 			jsonw_name(json_wtr, "module");
361 			jsonw_null(json_wtr);
362 		} else {
363 			jsonw_string_field(json_wtr, "module", dd.sym_mapping[i].module);
364 		}
365 		jsonw_uint_field(json_wtr, "cookie", data[j].cookie);
366 		jsonw_end_object(json_wtr);
367 		if (j++ == info->kprobe_multi.count)
368 			break;
369 	}
370 	jsonw_end_array(json_wtr);
371 error:
372 	free(data);
373 }
374 
375 static __u64 *u64_to_arr(__u64 val)
376 {
377 	return (__u64 *) u64_to_ptr(val);
378 }
379 
380 static void
381 show_uprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
382 {
383 	__u32 i;
384 
385 	jsonw_bool_field(json_wtr, "retprobe",
386 			 info->uprobe_multi.flags & BPF_F_UPROBE_MULTI_RETURN);
387 	jsonw_string_field(json_wtr, "path", (char *) u64_to_ptr(info->uprobe_multi.path));
388 	jsonw_uint_field(json_wtr, "func_cnt", info->uprobe_multi.count);
389 	jsonw_int_field(json_wtr, "pid", (int) info->uprobe_multi.pid);
390 	jsonw_name(json_wtr, "funcs");
391 	jsonw_start_array(json_wtr);
392 
393 	for (i = 0; i < info->uprobe_multi.count; i++) {
394 		jsonw_start_object(json_wtr);
395 		jsonw_uint_field(json_wtr, "offset",
396 				 u64_to_arr(info->uprobe_multi.offsets)[i]);
397 		jsonw_uint_field(json_wtr, "ref_ctr_offset",
398 				 u64_to_arr(info->uprobe_multi.ref_ctr_offsets)[i]);
399 		jsonw_uint_field(json_wtr, "cookie",
400 				 u64_to_arr(info->uprobe_multi.cookies)[i]);
401 		jsonw_end_object(json_wtr);
402 	}
403 	jsonw_end_array(json_wtr);
404 }
405 
406 static void
407 show_perf_event_kprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
408 {
409 	jsonw_bool_field(wtr, "retprobe", info->perf_event.type == BPF_PERF_EVENT_KRETPROBE);
410 	jsonw_uint_field(wtr, "addr", info->perf_event.kprobe.addr);
411 	jsonw_string_field(wtr, "func",
412 			   u64_to_ptr(info->perf_event.kprobe.func_name));
413 	jsonw_uint_field(wtr, "offset", info->perf_event.kprobe.offset);
414 	jsonw_uint_field(wtr, "missed", info->perf_event.kprobe.missed);
415 	jsonw_uint_field(wtr, "cookie", info->perf_event.kprobe.cookie);
416 }
417 
418 static void
419 show_perf_event_uprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
420 {
421 	jsonw_bool_field(wtr, "retprobe", info->perf_event.type == BPF_PERF_EVENT_URETPROBE);
422 	jsonw_string_field(wtr, "file",
423 			   u64_to_ptr(info->perf_event.uprobe.file_name));
424 	jsonw_uint_field(wtr, "offset", info->perf_event.uprobe.offset);
425 	jsonw_uint_field(wtr, "cookie", info->perf_event.uprobe.cookie);
426 	jsonw_uint_field(wtr, "ref_ctr_offset", info->perf_event.uprobe.ref_ctr_offset);
427 }
428 
429 static void
430 show_perf_event_tracepoint_json(struct bpf_link_info *info, json_writer_t *wtr)
431 {
432 	jsonw_string_field(wtr, "tracepoint",
433 			   u64_to_ptr(info->perf_event.tracepoint.tp_name));
434 	jsonw_uint_field(wtr, "cookie", info->perf_event.tracepoint.cookie);
435 }
436 
437 static char *perf_config_hw_cache_str(__u64 config)
438 {
439 	const char *hw_cache, *result, *op;
440 	char *str = malloc(PERF_HW_CACHE_LEN);
441 
442 	if (!str) {
443 		p_err("mem alloc failed");
444 		return NULL;
445 	}
446 
447 	hw_cache = perf_event_name(evsel__hw_cache, config & 0xff);
448 	if (hw_cache)
449 		snprintf(str, PERF_HW_CACHE_LEN, "%s-", hw_cache);
450 	else
451 		snprintf(str, PERF_HW_CACHE_LEN, "%llu-", config & 0xff);
452 
453 	op = perf_event_name(evsel__hw_cache_op, (config >> 8) & 0xff);
454 	if (op)
455 		snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
456 			 "%s-", op);
457 	else
458 		snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
459 			 "%llu-", (config >> 8) & 0xff);
460 
461 	result = perf_event_name(evsel__hw_cache_result, config >> 16);
462 	if (result)
463 		snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
464 			 "%s", result);
465 	else
466 		snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
467 			 "%llu", config >> 16);
468 	return str;
469 }
470 
471 static const char *perf_config_str(__u32 type, __u64 config)
472 {
473 	const char *perf_config;
474 
475 	switch (type) {
476 	case PERF_TYPE_HARDWARE:
477 		perf_config = perf_event_name(event_symbols_hw, config);
478 		break;
479 	case PERF_TYPE_SOFTWARE:
480 		perf_config = perf_event_name(event_symbols_sw, config);
481 		break;
482 	case PERF_TYPE_HW_CACHE:
483 		perf_config = perf_config_hw_cache_str(config);
484 		break;
485 	default:
486 		perf_config = NULL;
487 		break;
488 	}
489 	return perf_config;
490 }
491 
492 static void
493 show_perf_event_event_json(struct bpf_link_info *info, json_writer_t *wtr)
494 {
495 	__u64 config = info->perf_event.event.config;
496 	__u32 type = info->perf_event.event.type;
497 	const char *perf_type, *perf_config;
498 
499 	perf_type = perf_event_name(perf_type_name, type);
500 	if (perf_type)
501 		jsonw_string_field(wtr, "event_type", perf_type);
502 	else
503 		jsonw_uint_field(wtr, "event_type", type);
504 
505 	perf_config = perf_config_str(type, config);
506 	if (perf_config)
507 		jsonw_string_field(wtr, "event_config", perf_config);
508 	else
509 		jsonw_uint_field(wtr, "event_config", config);
510 
511 	jsonw_uint_field(wtr, "cookie", info->perf_event.event.cookie);
512 
513 	if (type == PERF_TYPE_HW_CACHE && perf_config)
514 		free((void *)perf_config);
515 }
516 
517 static int show_link_close_json(int fd, struct bpf_link_info *info)
518 {
519 	struct bpf_prog_info prog_info;
520 	const char *prog_type_str;
521 	int err;
522 
523 	jsonw_start_object(json_wtr);
524 
525 	show_link_header_json(info, json_wtr);
526 
527 	switch (info->type) {
528 	case BPF_LINK_TYPE_RAW_TRACEPOINT:
529 		jsonw_string_field(json_wtr, "tp_name",
530 				   u64_to_ptr(info->raw_tracepoint.tp_name));
531 		jsonw_uint_field(json_wtr, "cookie", info->raw_tracepoint.cookie);
532 		break;
533 	case BPF_LINK_TYPE_TRACING:
534 		err = get_prog_info(info->prog_id, &prog_info);
535 		if (err)
536 			return err;
537 
538 		prog_type_str = libbpf_bpf_prog_type_str(prog_info.type);
539 		/* libbpf will return NULL for variants unknown to it. */
540 		if (prog_type_str)
541 			jsonw_string_field(json_wtr, "prog_type", prog_type_str);
542 		else
543 			jsonw_uint_field(json_wtr, "prog_type", prog_info.type);
544 
545 		show_link_attach_type_json(info->tracing.attach_type,
546 					   json_wtr);
547 		jsonw_uint_field(json_wtr, "target_obj_id", info->tracing.target_obj_id);
548 		jsonw_uint_field(json_wtr, "target_btf_id", info->tracing.target_btf_id);
549 		jsonw_uint_field(json_wtr, "cookie", info->tracing.cookie);
550 		break;
551 	case BPF_LINK_TYPE_CGROUP:
552 		jsonw_lluint_field(json_wtr, "cgroup_id",
553 				   info->cgroup.cgroup_id);
554 		show_link_attach_type_json(info->cgroup.attach_type, json_wtr);
555 		break;
556 	case BPF_LINK_TYPE_ITER:
557 		show_iter_json(info, json_wtr);
558 		break;
559 	case BPF_LINK_TYPE_NETNS:
560 		jsonw_uint_field(json_wtr, "netns_ino",
561 				 info->netns.netns_ino);
562 		show_link_attach_type_json(info->netns.attach_type, json_wtr);
563 		break;
564 	case BPF_LINK_TYPE_NETFILTER:
565 		netfilter_dump_json(info, json_wtr);
566 		break;
567 	case BPF_LINK_TYPE_TCX:
568 		show_link_ifindex_json(info->tcx.ifindex, json_wtr);
569 		show_link_attach_type_json(info->tcx.attach_type, json_wtr);
570 		break;
571 	case BPF_LINK_TYPE_NETKIT:
572 		show_link_ifindex_json(info->netkit.ifindex, json_wtr);
573 		show_link_attach_type_json(info->netkit.attach_type, json_wtr);
574 		break;
575 	case BPF_LINK_TYPE_SOCKMAP:
576 		jsonw_uint_field(json_wtr, "map_id", info->sockmap.map_id);
577 		show_link_attach_type_json(info->sockmap.attach_type, json_wtr);
578 		break;
579 	case BPF_LINK_TYPE_XDP:
580 		show_link_ifindex_json(info->xdp.ifindex, json_wtr);
581 		break;
582 	case BPF_LINK_TYPE_STRUCT_OPS:
583 		jsonw_uint_field(json_wtr, "map_id",
584 				 info->struct_ops.map_id);
585 		break;
586 	case BPF_LINK_TYPE_KPROBE_MULTI:
587 		show_kprobe_multi_json(info, json_wtr);
588 		break;
589 	case BPF_LINK_TYPE_UPROBE_MULTI:
590 		show_uprobe_multi_json(info, json_wtr);
591 		break;
592 	case BPF_LINK_TYPE_PERF_EVENT:
593 		switch (info->perf_event.type) {
594 		case BPF_PERF_EVENT_EVENT:
595 			show_perf_event_event_json(info, json_wtr);
596 			break;
597 		case BPF_PERF_EVENT_TRACEPOINT:
598 			show_perf_event_tracepoint_json(info, json_wtr);
599 			break;
600 		case BPF_PERF_EVENT_KPROBE:
601 		case BPF_PERF_EVENT_KRETPROBE:
602 			show_perf_event_kprobe_json(info, json_wtr);
603 			break;
604 		case BPF_PERF_EVENT_UPROBE:
605 		case BPF_PERF_EVENT_URETPROBE:
606 			show_perf_event_uprobe_json(info, json_wtr);
607 			break;
608 		default:
609 			break;
610 		}
611 		break;
612 	default:
613 		break;
614 	}
615 
616 	if (!hashmap__empty(link_table)) {
617 		struct hashmap_entry *entry;
618 
619 		jsonw_name(json_wtr, "pinned");
620 		jsonw_start_array(json_wtr);
621 		hashmap__for_each_key_entry(link_table, entry, info->id)
622 			jsonw_string(json_wtr, entry->pvalue);
623 		jsonw_end_array(json_wtr);
624 	}
625 
626 	emit_obj_refs_json(refs_table, info->id, json_wtr);
627 
628 	jsonw_end_object(json_wtr);
629 
630 	return 0;
631 }
632 
633 static void show_link_header_plain(struct bpf_link_info *info)
634 {
635 	const char *link_type_str;
636 
637 	printf("%u: ", info->id);
638 	link_type_str = libbpf_bpf_link_type_str(info->type);
639 	if (link_type_str)
640 		printf("%s  ", link_type_str);
641 	else
642 		printf("type %u  ", info->type);
643 
644 	if (info->type == BPF_LINK_TYPE_STRUCT_OPS)
645 		printf("map %u  ", info->struct_ops.map_id);
646 	else
647 		printf("prog %u  ", info->prog_id);
648 }
649 
650 static void show_link_attach_type_plain(__u32 attach_type)
651 {
652 	const char *attach_type_str;
653 
654 	attach_type_str = libbpf_bpf_attach_type_str(attach_type);
655 	if (attach_type_str)
656 		printf("attach_type %s  ", attach_type_str);
657 	else
658 		printf("attach_type %u  ", attach_type);
659 }
660 
661 static void show_link_ifindex_plain(__u32 ifindex)
662 {
663 	char devname[IF_NAMESIZE * 2] = "(unknown)";
664 	char tmpname[IF_NAMESIZE];
665 	char *ret = NULL;
666 
667 	if (ifindex)
668 		ret = if_indextoname(ifindex, tmpname);
669 	else
670 		snprintf(devname, sizeof(devname), "(detached)");
671 	if (ret)
672 		snprintf(devname, sizeof(devname), "%s(%u)",
673 			 tmpname, ifindex);
674 	printf("ifindex %s  ", devname);
675 }
676 
677 static void show_iter_plain(struct bpf_link_info *info)
678 {
679 	const char *target_name = u64_to_ptr(info->iter.target_name);
680 
681 	printf("target_name %s  ", target_name);
682 
683 	if (is_iter_map_target(target_name))
684 		printf("map_id %u  ", info->iter.map.map_id);
685 	else if (is_iter_task_target(target_name)) {
686 		if (info->iter.task.tid)
687 			printf("tid %u ", info->iter.task.tid);
688 		else if (info->iter.task.pid)
689 			printf("pid %u ", info->iter.task.pid);
690 	}
691 
692 	if (is_iter_cgroup_target(target_name)) {
693 		printf("cgroup_id %llu  ", info->iter.cgroup.cgroup_id);
694 		printf("order %s  ",
695 		       cgroup_order_string(info->iter.cgroup.order));
696 	}
697 }
698 
699 static const char * const pf2name[] = {
700 	[NFPROTO_INET] = "inet",
701 	[NFPROTO_IPV4] = "ip",
702 	[NFPROTO_ARP] = "arp",
703 	[NFPROTO_NETDEV] = "netdev",
704 	[NFPROTO_BRIDGE] = "bridge",
705 	[NFPROTO_IPV6] = "ip6",
706 };
707 
708 static const char * const inethook2name[] = {
709 	[NF_INET_PRE_ROUTING] = "prerouting",
710 	[NF_INET_LOCAL_IN] = "input",
711 	[NF_INET_FORWARD] = "forward",
712 	[NF_INET_LOCAL_OUT] = "output",
713 	[NF_INET_POST_ROUTING] = "postrouting",
714 };
715 
716 static const char * const arphook2name[] = {
717 	[NF_ARP_IN] = "input",
718 	[NF_ARP_OUT] = "output",
719 };
720 
721 void netfilter_dump_plain(const struct bpf_link_info *info)
722 {
723 	const char *hookname = NULL, *pfname = NULL;
724 	unsigned int hook = info->netfilter.hooknum;
725 	unsigned int pf = info->netfilter.pf;
726 
727 	if (pf < ARRAY_SIZE(pf2name))
728 		pfname = pf2name[pf];
729 
730 	switch (pf) {
731 	case NFPROTO_BRIDGE: /* bridge shares numbers with enum nf_inet_hooks */
732 	case NFPROTO_IPV4:
733 	case NFPROTO_IPV6:
734 	case NFPROTO_INET:
735 		if (hook < ARRAY_SIZE(inethook2name))
736 			hookname = inethook2name[hook];
737 		break;
738 	case NFPROTO_ARP:
739 		if (hook < ARRAY_SIZE(arphook2name))
740 			hookname = arphook2name[hook];
741 	default:
742 		break;
743 	}
744 
745 	if (pfname)
746 		printf("\n\t%s", pfname);
747 	else
748 		printf("\n\tpf: %u", pf);
749 
750 	if (hookname)
751 		printf(" %s", hookname);
752 	else
753 		printf(", hook %u,", hook);
754 
755 	printf(" prio %d", info->netfilter.priority);
756 
757 	if (info->netfilter.flags)
758 		printf(" flags 0x%x", info->netfilter.flags);
759 }
760 
761 static void show_kprobe_multi_plain(struct bpf_link_info *info)
762 {
763 	struct addr_cookie *data;
764 	__u32 i, j = 0;
765 	bool is_ibt_enabled;
766 
767 	if (!info->kprobe_multi.count)
768 		return;
769 
770 	if (info->kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN)
771 		printf("\n\tkretprobe.multi  ");
772 	else
773 		printf("\n\tkprobe.multi  ");
774 	printf("func_cnt %u  ", info->kprobe_multi.count);
775 	if (info->kprobe_multi.missed)
776 		printf("missed %llu  ", info->kprobe_multi.missed);
777 	data = get_addr_cookie_array(u64_to_ptr(info->kprobe_multi.addrs),
778 				     u64_to_ptr(info->kprobe_multi.cookies),
779 				     info->kprobe_multi.count);
780 	if (!data)
781 		return;
782 
783 	/* Load it once for all. */
784 	if (!dd.sym_count)
785 		kernel_syms_load(&dd);
786 	if (!dd.sym_count)
787 		goto error;
788 
789 	is_ibt_enabled = is_x86_ibt_enabled();
790 	printf("\n\t%-16s %-16s %s", "addr", "cookie", "func [module]");
791 	for (i = 0; i < dd.sym_count; i++) {
792 		if (!symbol_matches_target(dd.sym_mapping[i].address,
793 					   data[j].addr, is_ibt_enabled))
794 			continue;
795 		printf("\n\t%016lx %-16llx %s",
796 		       (unsigned long)data[j].addr, data[j].cookie, dd.sym_mapping[i].name);
797 		if (dd.sym_mapping[i].module[0] != '\0')
798 			printf(" [%s]  ", dd.sym_mapping[i].module);
799 		else
800 			printf("  ");
801 
802 		if (j++ == info->kprobe_multi.count)
803 			break;
804 	}
805 error:
806 	free(data);
807 }
808 
809 static void show_uprobe_multi_plain(struct bpf_link_info *info)
810 {
811 	__u32 i;
812 
813 	if (!info->uprobe_multi.count)
814 		return;
815 
816 	if (info->uprobe_multi.flags & BPF_F_UPROBE_MULTI_RETURN)
817 		printf("\n\turetprobe.multi  ");
818 	else
819 		printf("\n\tuprobe.multi  ");
820 
821 	printf("path %s  ", (char *) u64_to_ptr(info->uprobe_multi.path));
822 	printf("func_cnt %u  ", info->uprobe_multi.count);
823 
824 	if (info->uprobe_multi.pid)
825 		printf("pid %u  ", info->uprobe_multi.pid);
826 
827 	printf("\n\t%-16s   %-16s   %-16s", "offset", "ref_ctr_offset", "cookies");
828 	for (i = 0; i < info->uprobe_multi.count; i++) {
829 		printf("\n\t0x%-16llx 0x%-16llx 0x%-16llx",
830 			u64_to_arr(info->uprobe_multi.offsets)[i],
831 			u64_to_arr(info->uprobe_multi.ref_ctr_offsets)[i],
832 			u64_to_arr(info->uprobe_multi.cookies)[i]);
833 	}
834 }
835 
836 static void show_perf_event_kprobe_plain(struct bpf_link_info *info)
837 {
838 	const char *buf;
839 
840 	buf = u64_to_ptr(info->perf_event.kprobe.func_name);
841 	if (buf[0] == '\0' && !info->perf_event.kprobe.addr)
842 		return;
843 
844 	if (info->perf_event.type == BPF_PERF_EVENT_KRETPROBE)
845 		printf("\n\tkretprobe ");
846 	else
847 		printf("\n\tkprobe ");
848 	if (info->perf_event.kprobe.addr)
849 		printf("%llx ", info->perf_event.kprobe.addr);
850 	printf("%s", buf);
851 	if (info->perf_event.kprobe.offset)
852 		printf("+%#x", info->perf_event.kprobe.offset);
853 	if (info->perf_event.kprobe.missed)
854 		printf("  missed %llu", info->perf_event.kprobe.missed);
855 	if (info->perf_event.kprobe.cookie)
856 		printf("  cookie %llu", info->perf_event.kprobe.cookie);
857 	printf("  ");
858 }
859 
860 static void show_perf_event_uprobe_plain(struct bpf_link_info *info)
861 {
862 	const char *buf;
863 
864 	buf = u64_to_ptr(info->perf_event.uprobe.file_name);
865 	if (buf[0] == '\0')
866 		return;
867 
868 	if (info->perf_event.type == BPF_PERF_EVENT_URETPROBE)
869 		printf("\n\turetprobe ");
870 	else
871 		printf("\n\tuprobe ");
872 	printf("%s+%#x  ", buf, info->perf_event.uprobe.offset);
873 	if (info->perf_event.uprobe.cookie)
874 		printf("cookie %llu  ", info->perf_event.uprobe.cookie);
875 	if (info->perf_event.uprobe.ref_ctr_offset)
876 		printf("ref_ctr_offset 0x%llx  ", info->perf_event.uprobe.ref_ctr_offset);
877 }
878 
879 static void show_perf_event_tracepoint_plain(struct bpf_link_info *info)
880 {
881 	const char *buf;
882 
883 	buf = u64_to_ptr(info->perf_event.tracepoint.tp_name);
884 	if (buf[0] == '\0')
885 		return;
886 
887 	printf("\n\ttracepoint %s  ", buf);
888 	if (info->perf_event.tracepoint.cookie)
889 		printf("cookie %llu  ", info->perf_event.tracepoint.cookie);
890 }
891 
892 static void show_perf_event_event_plain(struct bpf_link_info *info)
893 {
894 	__u64 config = info->perf_event.event.config;
895 	__u32 type = info->perf_event.event.type;
896 	const char *perf_type, *perf_config;
897 
898 	printf("\n\tevent ");
899 	perf_type = perf_event_name(perf_type_name, type);
900 	if (perf_type)
901 		printf("%s:", perf_type);
902 	else
903 		printf("%u :", type);
904 
905 	perf_config = perf_config_str(type, config);
906 	if (perf_config)
907 		printf("%s  ", perf_config);
908 	else
909 		printf("%llu  ", config);
910 
911 	if (info->perf_event.event.cookie)
912 		printf("cookie %llu  ", info->perf_event.event.cookie);
913 
914 	if (type == PERF_TYPE_HW_CACHE && perf_config)
915 		free((void *)perf_config);
916 }
917 
918 static int show_link_close_plain(int fd, struct bpf_link_info *info)
919 {
920 	struct bpf_prog_info prog_info;
921 	const char *prog_type_str;
922 	int err;
923 
924 	show_link_header_plain(info);
925 
926 	switch (info->type) {
927 	case BPF_LINK_TYPE_RAW_TRACEPOINT:
928 		printf("\n\ttp '%s'  ",
929 		       (const char *)u64_to_ptr(info->raw_tracepoint.tp_name));
930 		if (info->raw_tracepoint.cookie)
931 			printf("cookie %llu  ", info->raw_tracepoint.cookie);
932 		break;
933 	case BPF_LINK_TYPE_TRACING:
934 		err = get_prog_info(info->prog_id, &prog_info);
935 		if (err)
936 			return err;
937 
938 		prog_type_str = libbpf_bpf_prog_type_str(prog_info.type);
939 		/* libbpf will return NULL for variants unknown to it. */
940 		if (prog_type_str)
941 			printf("\n\tprog_type %s  ", prog_type_str);
942 		else
943 			printf("\n\tprog_type %u  ", prog_info.type);
944 
945 		show_link_attach_type_plain(info->tracing.attach_type);
946 		if (info->tracing.target_obj_id || info->tracing.target_btf_id)
947 			printf("\n\ttarget_obj_id %u  target_btf_id %u  ",
948 			       info->tracing.target_obj_id,
949 			       info->tracing.target_btf_id);
950 		if (info->tracing.cookie)
951 			printf("\n\tcookie %llu  ", info->tracing.cookie);
952 		break;
953 	case BPF_LINK_TYPE_CGROUP:
954 		printf("\n\tcgroup_id %zu  ", (size_t)info->cgroup.cgroup_id);
955 		show_link_attach_type_plain(info->cgroup.attach_type);
956 		break;
957 	case BPF_LINK_TYPE_ITER:
958 		show_iter_plain(info);
959 		break;
960 	case BPF_LINK_TYPE_NETNS:
961 		printf("\n\tnetns_ino %u  ", info->netns.netns_ino);
962 		show_link_attach_type_plain(info->netns.attach_type);
963 		break;
964 	case BPF_LINK_TYPE_NETFILTER:
965 		netfilter_dump_plain(info);
966 		break;
967 	case BPF_LINK_TYPE_TCX:
968 		printf("\n\t");
969 		show_link_ifindex_plain(info->tcx.ifindex);
970 		show_link_attach_type_plain(info->tcx.attach_type);
971 		break;
972 	case BPF_LINK_TYPE_NETKIT:
973 		printf("\n\t");
974 		show_link_ifindex_plain(info->netkit.ifindex);
975 		show_link_attach_type_plain(info->netkit.attach_type);
976 		break;
977 	case BPF_LINK_TYPE_SOCKMAP:
978 		printf("\n\t");
979 		printf("map_id %u  ", info->sockmap.map_id);
980 		show_link_attach_type_plain(info->sockmap.attach_type);
981 		break;
982 	case BPF_LINK_TYPE_XDP:
983 		printf("\n\t");
984 		show_link_ifindex_plain(info->xdp.ifindex);
985 		break;
986 	case BPF_LINK_TYPE_KPROBE_MULTI:
987 		show_kprobe_multi_plain(info);
988 		break;
989 	case BPF_LINK_TYPE_UPROBE_MULTI:
990 		show_uprobe_multi_plain(info);
991 		break;
992 	case BPF_LINK_TYPE_PERF_EVENT:
993 		switch (info->perf_event.type) {
994 		case BPF_PERF_EVENT_EVENT:
995 			show_perf_event_event_plain(info);
996 			break;
997 		case BPF_PERF_EVENT_TRACEPOINT:
998 			show_perf_event_tracepoint_plain(info);
999 			break;
1000 		case BPF_PERF_EVENT_KPROBE:
1001 		case BPF_PERF_EVENT_KRETPROBE:
1002 			show_perf_event_kprobe_plain(info);
1003 			break;
1004 		case BPF_PERF_EVENT_UPROBE:
1005 		case BPF_PERF_EVENT_URETPROBE:
1006 			show_perf_event_uprobe_plain(info);
1007 			break;
1008 		default:
1009 			break;
1010 		}
1011 		break;
1012 	default:
1013 		break;
1014 	}
1015 
1016 	if (!hashmap__empty(link_table)) {
1017 		struct hashmap_entry *entry;
1018 
1019 		hashmap__for_each_key_entry(link_table, entry, info->id)
1020 			printf("\n\tpinned %s", (char *)entry->pvalue);
1021 	}
1022 	emit_obj_refs_plain(refs_table, info->id, "\n\tpids ");
1023 
1024 	printf("\n");
1025 
1026 	return 0;
1027 }
1028 
1029 static int do_show_link(int fd)
1030 {
1031 	__u64 *ref_ctr_offsets = NULL, *offsets = NULL, *cookies = NULL;
1032 	struct bpf_link_info info;
1033 	__u32 len = sizeof(info);
1034 	char path_buf[PATH_MAX];
1035 	__u64 *addrs = NULL;
1036 	char buf[PATH_MAX];
1037 	int count;
1038 	int err;
1039 
1040 	memset(&info, 0, sizeof(info));
1041 	buf[0] = '\0';
1042 again:
1043 	err = bpf_link_get_info_by_fd(fd, &info, &len);
1044 	if (err) {
1045 		p_err("can't get link info: %s",
1046 		      strerror(errno));
1047 		close(fd);
1048 		return err;
1049 	}
1050 	if (info.type == BPF_LINK_TYPE_RAW_TRACEPOINT &&
1051 	    !info.raw_tracepoint.tp_name) {
1052 		info.raw_tracepoint.tp_name = ptr_to_u64(&buf);
1053 		info.raw_tracepoint.tp_name_len = sizeof(buf);
1054 		goto again;
1055 	}
1056 	if (info.type == BPF_LINK_TYPE_ITER &&
1057 	    !info.iter.target_name) {
1058 		info.iter.target_name = ptr_to_u64(&buf);
1059 		info.iter.target_name_len = sizeof(buf);
1060 		goto again;
1061 	}
1062 	if (info.type == BPF_LINK_TYPE_KPROBE_MULTI &&
1063 	    !info.kprobe_multi.addrs) {
1064 		count = info.kprobe_multi.count;
1065 		if (count) {
1066 			addrs = calloc(count, sizeof(__u64));
1067 			if (!addrs) {
1068 				p_err("mem alloc failed");
1069 				close(fd);
1070 				return -ENOMEM;
1071 			}
1072 			info.kprobe_multi.addrs = ptr_to_u64(addrs);
1073 			cookies = calloc(count, sizeof(__u64));
1074 			if (!cookies) {
1075 				p_err("mem alloc failed");
1076 				free(addrs);
1077 				close(fd);
1078 				return -ENOMEM;
1079 			}
1080 			info.kprobe_multi.cookies = ptr_to_u64(cookies);
1081 			goto again;
1082 		}
1083 	}
1084 	if (info.type == BPF_LINK_TYPE_UPROBE_MULTI &&
1085 	    !info.uprobe_multi.offsets) {
1086 		count = info.uprobe_multi.count;
1087 		if (count) {
1088 			offsets = calloc(count, sizeof(__u64));
1089 			if (!offsets) {
1090 				p_err("mem alloc failed");
1091 				close(fd);
1092 				return -ENOMEM;
1093 			}
1094 			info.uprobe_multi.offsets = ptr_to_u64(offsets);
1095 			ref_ctr_offsets = calloc(count, sizeof(__u64));
1096 			if (!ref_ctr_offsets) {
1097 				p_err("mem alloc failed");
1098 				free(offsets);
1099 				close(fd);
1100 				return -ENOMEM;
1101 			}
1102 			info.uprobe_multi.ref_ctr_offsets = ptr_to_u64(ref_ctr_offsets);
1103 			cookies = calloc(count, sizeof(__u64));
1104 			if (!cookies) {
1105 				p_err("mem alloc failed");
1106 				free(ref_ctr_offsets);
1107 				free(offsets);
1108 				close(fd);
1109 				return -ENOMEM;
1110 			}
1111 			info.uprobe_multi.cookies = ptr_to_u64(cookies);
1112 			info.uprobe_multi.path = ptr_to_u64(path_buf);
1113 			info.uprobe_multi.path_size = sizeof(path_buf);
1114 			goto again;
1115 		}
1116 	}
1117 	if (info.type == BPF_LINK_TYPE_PERF_EVENT) {
1118 		switch (info.perf_event.type) {
1119 		case BPF_PERF_EVENT_TRACEPOINT:
1120 			if (!info.perf_event.tracepoint.tp_name) {
1121 				info.perf_event.tracepoint.tp_name = ptr_to_u64(&buf);
1122 				info.perf_event.tracepoint.name_len = sizeof(buf);
1123 				goto again;
1124 			}
1125 			break;
1126 		case BPF_PERF_EVENT_KPROBE:
1127 		case BPF_PERF_EVENT_KRETPROBE:
1128 			if (!info.perf_event.kprobe.func_name) {
1129 				info.perf_event.kprobe.func_name = ptr_to_u64(&buf);
1130 				info.perf_event.kprobe.name_len = sizeof(buf);
1131 				goto again;
1132 			}
1133 			break;
1134 		case BPF_PERF_EVENT_UPROBE:
1135 		case BPF_PERF_EVENT_URETPROBE:
1136 			if (!info.perf_event.uprobe.file_name) {
1137 				info.perf_event.uprobe.file_name = ptr_to_u64(&buf);
1138 				info.perf_event.uprobe.name_len = sizeof(buf);
1139 				goto again;
1140 			}
1141 			break;
1142 		default:
1143 			break;
1144 		}
1145 	}
1146 
1147 	if (json_output)
1148 		show_link_close_json(fd, &info);
1149 	else
1150 		show_link_close_plain(fd, &info);
1151 
1152 	free(ref_ctr_offsets);
1153 	free(cookies);
1154 	free(offsets);
1155 	free(addrs);
1156 	close(fd);
1157 	return 0;
1158 }
1159 
1160 static int do_show(int argc, char **argv)
1161 {
1162 	__u32 id = 0;
1163 	int err, fd;
1164 
1165 	if (show_pinned) {
1166 		link_table = hashmap__new(hash_fn_for_key_as_id,
1167 					  equal_fn_for_key_as_id, NULL);
1168 		if (IS_ERR(link_table)) {
1169 			p_err("failed to create hashmap for pinned paths");
1170 			return -1;
1171 		}
1172 		build_pinned_obj_table(link_table, BPF_OBJ_LINK);
1173 	}
1174 	build_obj_refs_table(&refs_table, BPF_OBJ_LINK);
1175 
1176 	if (argc == 2) {
1177 		fd = link_parse_fd(&argc, &argv);
1178 		if (fd < 0)
1179 			return fd;
1180 		do_show_link(fd);
1181 		goto out;
1182 	}
1183 
1184 	if (argc)
1185 		return BAD_ARG();
1186 
1187 	if (json_output)
1188 		jsonw_start_array(json_wtr);
1189 	while (true) {
1190 		err = bpf_link_get_next_id(id, &id);
1191 		if (err) {
1192 			if (errno == ENOENT)
1193 				break;
1194 			p_err("can't get next link: %s%s", strerror(errno),
1195 			      errno == EINVAL ? " -- kernel too old?" : "");
1196 			break;
1197 		}
1198 
1199 		fd = bpf_link_get_fd_by_id(id);
1200 		if (fd < 0) {
1201 			if (errno == ENOENT)
1202 				continue;
1203 			p_err("can't get link by id (%u): %s",
1204 			      id, strerror(errno));
1205 			break;
1206 		}
1207 
1208 		err = do_show_link(fd);
1209 		if (err)
1210 			break;
1211 	}
1212 	if (json_output)
1213 		jsonw_end_array(json_wtr);
1214 
1215 	delete_obj_refs_table(refs_table);
1216 
1217 	if (show_pinned)
1218 		delete_pinned_obj_table(link_table);
1219 
1220 out:
1221 	if (dd.sym_count)
1222 		kernel_syms_destroy(&dd);
1223 	return errno == ENOENT ? 0 : -1;
1224 }
1225 
1226 static int do_pin(int argc, char **argv)
1227 {
1228 	int err;
1229 
1230 	err = do_pin_any(argc, argv, link_parse_fd);
1231 	if (!err && json_output)
1232 		jsonw_null(json_wtr);
1233 	return err;
1234 }
1235 
1236 static int do_detach(int argc, char **argv)
1237 {
1238 	int err, fd;
1239 
1240 	if (argc != 2) {
1241 		p_err("link specifier is invalid or missing\n");
1242 		return 1;
1243 	}
1244 
1245 	fd = link_parse_fd(&argc, &argv);
1246 	if (fd < 0)
1247 		return 1;
1248 
1249 	err = bpf_link_detach(fd);
1250 	if (err)
1251 		err = -errno;
1252 	close(fd);
1253 	if (err) {
1254 		p_err("failed link detach: %s", strerror(-err));
1255 		return 1;
1256 	}
1257 
1258 	if (json_output)
1259 		jsonw_null(json_wtr);
1260 
1261 	return 0;
1262 }
1263 
1264 static int do_help(int argc, char **argv)
1265 {
1266 	if (json_output) {
1267 		jsonw_null(json_wtr);
1268 		return 0;
1269 	}
1270 
1271 	fprintf(stderr,
1272 		"Usage: %1$s %2$s { show | list }   [LINK]\n"
1273 		"       %1$s %2$s pin        LINK  FILE\n"
1274 		"       %1$s %2$s detach     LINK\n"
1275 		"       %1$s %2$s help\n"
1276 		"\n"
1277 		"       " HELP_SPEC_LINK "\n"
1278 		"       " HELP_SPEC_OPTIONS " |\n"
1279 		"                    {-f|--bpffs} | {-n|--nomount} }\n"
1280 		"",
1281 		bin_name, argv[-2]);
1282 
1283 	return 0;
1284 }
1285 
1286 static const struct cmd cmds[] = {
1287 	{ "show",	do_show },
1288 	{ "list",	do_show },
1289 	{ "help",	do_help },
1290 	{ "pin",	do_pin },
1291 	{ "detach",	do_detach },
1292 	{ 0 }
1293 };
1294 
1295 int do_link(int argc, char **argv)
1296 {
1297 	return cmd_select(cmds, argc, argv, do_help);
1298 }
1299