xref: /openbmc/linux/tools/bpf/bpftool/btf_dumper.c (revision 2f0754f2)
1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 /* Copyright (c) 2018 Facebook */
3 
4 #include <ctype.h>
5 #include <stdio.h> /* for (FILE *) used by json_writer */
6 #include <string.h>
7 #include <unistd.h>
8 #include <asm/byteorder.h>
9 #include <linux/bitops.h>
10 #include <linux/btf.h>
11 #include <linux/err.h>
12 #include <bpf/btf.h>
13 #include <bpf/bpf.h>
14 
15 #include "json_writer.h"
16 #include "main.h"
17 
18 #define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
19 #define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
20 #define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
21 #define BITS_ROUNDUP_BYTES(bits) \
22 	(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
23 
24 static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
25 			      __u8 bit_offset, const void *data);
26 
27 static int btf_dump_func(const struct btf *btf, char *func_sig,
28 			 const struct btf_type *func_proto,
29 			 const struct btf_type *func, int pos, int size);
30 
31 static int dump_prog_id_as_func_ptr(const struct btf_dumper *d,
32 				    const struct btf_type *func_proto,
33 				    __u32 prog_id)
34 {
35 	const struct btf_type *func_type;
36 	int prog_fd = -1, func_sig_len;
37 	struct bpf_prog_info info = {};
38 	__u32 info_len = sizeof(info);
39 	const char *prog_name = NULL;
40 	struct btf *prog_btf = NULL;
41 	struct bpf_func_info finfo;
42 	__u32 finfo_rec_size;
43 	char prog_str[1024];
44 	int err;
45 
46 	/* Get the ptr's func_proto */
47 	func_sig_len = btf_dump_func(d->btf, prog_str, func_proto, NULL, 0,
48 				     sizeof(prog_str));
49 	if (func_sig_len == -1)
50 		return -1;
51 
52 	if (!prog_id)
53 		goto print;
54 
55 	/* Get the bpf_prog's name.  Obtain from func_info. */
56 	prog_fd = bpf_prog_get_fd_by_id(prog_id);
57 	if (prog_fd < 0)
58 		goto print;
59 
60 	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
61 	if (err)
62 		goto print;
63 
64 	if (!info.btf_id || !info.nr_func_info)
65 		goto print;
66 
67 	finfo_rec_size = info.func_info_rec_size;
68 	memset(&info, 0, sizeof(info));
69 	info.nr_func_info = 1;
70 	info.func_info_rec_size = finfo_rec_size;
71 	info.func_info = ptr_to_u64(&finfo);
72 
73 	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
74 	if (err)
75 		goto print;
76 
77 	prog_btf = btf__load_from_kernel_by_id(info.btf_id);
78 	if (libbpf_get_error(prog_btf))
79 		goto print;
80 	func_type = btf__type_by_id(prog_btf, finfo.type_id);
81 	if (!func_type || !btf_is_func(func_type))
82 		goto print;
83 
84 	prog_name = btf__name_by_offset(prog_btf, func_type->name_off);
85 
86 print:
87 	if (!prog_id)
88 		snprintf(&prog_str[func_sig_len],
89 			 sizeof(prog_str) - func_sig_len, " 0");
90 	else if (prog_name)
91 		snprintf(&prog_str[func_sig_len],
92 			 sizeof(prog_str) - func_sig_len,
93 			 " %s/prog_id:%u", prog_name, prog_id);
94 	else
95 		snprintf(&prog_str[func_sig_len],
96 			 sizeof(prog_str) - func_sig_len,
97 			 " <unknown_prog_name>/prog_id:%u", prog_id);
98 
99 	prog_str[sizeof(prog_str) - 1] = '\0';
100 	jsonw_string(d->jw, prog_str);
101 	btf__free(prog_btf);
102 	if (prog_fd >= 0)
103 		close(prog_fd);
104 	return 0;
105 }
106 
107 static void btf_dumper_ptr(const struct btf_dumper *d,
108 			   const struct btf_type *t,
109 			   const void *data)
110 {
111 	unsigned long value = *(unsigned long *)data;
112 	const struct btf_type *ptr_type;
113 	__s32 ptr_type_id;
114 
115 	if (!d->prog_id_as_func_ptr || value > UINT32_MAX)
116 		goto print_ptr_value;
117 
118 	ptr_type_id = btf__resolve_type(d->btf, t->type);
119 	if (ptr_type_id < 0)
120 		goto print_ptr_value;
121 	ptr_type = btf__type_by_id(d->btf, ptr_type_id);
122 	if (!ptr_type || !btf_is_func_proto(ptr_type))
123 		goto print_ptr_value;
124 
125 	if (!dump_prog_id_as_func_ptr(d, ptr_type, value))
126 		return;
127 
128 print_ptr_value:
129 	if (d->is_plain_text)
130 		jsonw_printf(d->jw, "%p", (void *)value);
131 	else
132 		jsonw_printf(d->jw, "%lu", value);
133 }
134 
135 static int btf_dumper_modifier(const struct btf_dumper *d, __u32 type_id,
136 			       __u8 bit_offset, const void *data)
137 {
138 	int actual_type_id;
139 
140 	actual_type_id = btf__resolve_type(d->btf, type_id);
141 	if (actual_type_id < 0)
142 		return actual_type_id;
143 
144 	return btf_dumper_do_type(d, actual_type_id, bit_offset, data);
145 }
146 
147 static int btf_dumper_enum(const struct btf_dumper *d,
148 			    const struct btf_type *t,
149 			    const void *data)
150 {
151 	const struct btf_enum *enums = btf_enum(t);
152 	__s64 value;
153 	__u16 i;
154 
155 	switch (t->size) {
156 	case 8:
157 		value = *(__s64 *)data;
158 		break;
159 	case 4:
160 		value = *(__s32 *)data;
161 		break;
162 	case 2:
163 		value = *(__s16 *)data;
164 		break;
165 	case 1:
166 		value = *(__s8 *)data;
167 		break;
168 	default:
169 		return -EINVAL;
170 	}
171 
172 	for (i = 0; i < btf_vlen(t); i++) {
173 		if (value == enums[i].val) {
174 			jsonw_string(d->jw,
175 				     btf__name_by_offset(d->btf,
176 							 enums[i].name_off));
177 			return 0;
178 		}
179 	}
180 
181 	jsonw_int(d->jw, value);
182 	return 0;
183 }
184 
185 static bool is_str_array(const struct btf *btf, const struct btf_array *arr,
186 			 const char *s)
187 {
188 	const struct btf_type *elem_type;
189 	const char *end_s;
190 
191 	if (!arr->nelems)
192 		return false;
193 
194 	elem_type = btf__type_by_id(btf, arr->type);
195 	/* Not skipping typedef.  typedef to char does not count as
196 	 * a string now.
197 	 */
198 	while (elem_type && btf_is_mod(elem_type))
199 		elem_type = btf__type_by_id(btf, elem_type->type);
200 
201 	if (!elem_type || !btf_is_int(elem_type) || elem_type->size != 1)
202 		return false;
203 
204 	if (btf_int_encoding(elem_type) != BTF_INT_CHAR &&
205 	    strcmp("char", btf__name_by_offset(btf, elem_type->name_off)))
206 		return false;
207 
208 	end_s = s + arr->nelems;
209 	while (s < end_s) {
210 		if (!*s)
211 			return true;
212 		if (*s <= 0x1f || *s >= 0x7f)
213 			return false;
214 		s++;
215 	}
216 
217 	/* '\0' is not found */
218 	return false;
219 }
220 
221 static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
222 			    const void *data)
223 {
224 	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
225 	struct btf_array *arr = (struct btf_array *)(t + 1);
226 	long long elem_size;
227 	int ret = 0;
228 	__u32 i;
229 
230 	if (is_str_array(d->btf, arr, data)) {
231 		jsonw_string(d->jw, data);
232 		return 0;
233 	}
234 
235 	elem_size = btf__resolve_size(d->btf, arr->type);
236 	if (elem_size < 0)
237 		return elem_size;
238 
239 	jsonw_start_array(d->jw);
240 	for (i = 0; i < arr->nelems; i++) {
241 		ret = btf_dumper_do_type(d, arr->type, 0,
242 					 data + i * elem_size);
243 		if (ret)
244 			break;
245 	}
246 
247 	jsonw_end_array(d->jw);
248 	return ret;
249 }
250 
251 static void btf_int128_print(json_writer_t *jw, const void *data,
252 			     bool is_plain_text)
253 {
254 	/* data points to a __int128 number.
255 	 * Suppose
256 	 *     int128_num = *(__int128 *)data;
257 	 * The below formulas shows what upper_num and lower_num represents:
258 	 *     upper_num = int128_num >> 64;
259 	 *     lower_num = int128_num & 0xffffffffFFFFFFFFULL;
260 	 */
261 	__u64 upper_num, lower_num;
262 
263 #ifdef __BIG_ENDIAN_BITFIELD
264 	upper_num = *(__u64 *)data;
265 	lower_num = *(__u64 *)(data + 8);
266 #else
267 	upper_num = *(__u64 *)(data + 8);
268 	lower_num = *(__u64 *)data;
269 #endif
270 
271 	if (is_plain_text) {
272 		if (upper_num == 0)
273 			jsonw_printf(jw, "0x%llx", lower_num);
274 		else
275 			jsonw_printf(jw, "0x%llx%016llx", upper_num, lower_num);
276 	} else {
277 		if (upper_num == 0)
278 			jsonw_printf(jw, "\"0x%llx\"", lower_num);
279 		else
280 			jsonw_printf(jw, "\"0x%llx%016llx\"", upper_num, lower_num);
281 	}
282 }
283 
284 static void btf_int128_shift(__u64 *print_num, __u16 left_shift_bits,
285 			     __u16 right_shift_bits)
286 {
287 	__u64 upper_num, lower_num;
288 
289 #ifdef __BIG_ENDIAN_BITFIELD
290 	upper_num = print_num[0];
291 	lower_num = print_num[1];
292 #else
293 	upper_num = print_num[1];
294 	lower_num = print_num[0];
295 #endif
296 
297 	/* shake out un-needed bits by shift/or operations */
298 	if (left_shift_bits >= 64) {
299 		upper_num = lower_num << (left_shift_bits - 64);
300 		lower_num = 0;
301 	} else {
302 		upper_num = (upper_num << left_shift_bits) |
303 			    (lower_num >> (64 - left_shift_bits));
304 		lower_num = lower_num << left_shift_bits;
305 	}
306 
307 	if (right_shift_bits >= 64) {
308 		lower_num = upper_num >> (right_shift_bits - 64);
309 		upper_num = 0;
310 	} else {
311 		lower_num = (lower_num >> right_shift_bits) |
312 			    (upper_num << (64 - right_shift_bits));
313 		upper_num = upper_num >> right_shift_bits;
314 	}
315 
316 #ifdef __BIG_ENDIAN_BITFIELD
317 	print_num[0] = upper_num;
318 	print_num[1] = lower_num;
319 #else
320 	print_num[0] = lower_num;
321 	print_num[1] = upper_num;
322 #endif
323 }
324 
325 static void btf_dumper_bitfield(__u32 nr_bits, __u8 bit_offset,
326 				const void *data, json_writer_t *jw,
327 				bool is_plain_text)
328 {
329 	int left_shift_bits, right_shift_bits;
330 	__u64 print_num[2] = {};
331 	int bytes_to_copy;
332 	int bits_to_copy;
333 
334 	bits_to_copy = bit_offset + nr_bits;
335 	bytes_to_copy = BITS_ROUNDUP_BYTES(bits_to_copy);
336 
337 	memcpy(print_num, data, bytes_to_copy);
338 #if defined(__BIG_ENDIAN_BITFIELD)
339 	left_shift_bits = bit_offset;
340 #elif defined(__LITTLE_ENDIAN_BITFIELD)
341 	left_shift_bits = 128 - bits_to_copy;
342 #else
343 #error neither big nor little endian
344 #endif
345 	right_shift_bits = 128 - nr_bits;
346 
347 	btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
348 	btf_int128_print(jw, print_num, is_plain_text);
349 }
350 
351 
352 static void btf_dumper_int_bits(__u32 int_type, __u8 bit_offset,
353 				const void *data, json_writer_t *jw,
354 				bool is_plain_text)
355 {
356 	int nr_bits = BTF_INT_BITS(int_type);
357 	int total_bits_offset;
358 
359 	/* bits_offset is at most 7.
360 	 * BTF_INT_OFFSET() cannot exceed 128 bits.
361 	 */
362 	total_bits_offset = bit_offset + BTF_INT_OFFSET(int_type);
363 	data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
364 	bit_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
365 	btf_dumper_bitfield(nr_bits, bit_offset, data, jw,
366 			    is_plain_text);
367 }
368 
369 static int btf_dumper_int(const struct btf_type *t, __u8 bit_offset,
370 			  const void *data, json_writer_t *jw,
371 			  bool is_plain_text)
372 {
373 	__u32 *int_type;
374 	__u32 nr_bits;
375 
376 	int_type = (__u32 *)(t + 1);
377 	nr_bits = BTF_INT_BITS(*int_type);
378 	/* if this is bit field */
379 	if (bit_offset || BTF_INT_OFFSET(*int_type) ||
380 	    BITS_PER_BYTE_MASKED(nr_bits)) {
381 		btf_dumper_int_bits(*int_type, bit_offset, data, jw,
382 				    is_plain_text);
383 		return 0;
384 	}
385 
386 	if (nr_bits == 128) {
387 		btf_int128_print(jw, data, is_plain_text);
388 		return 0;
389 	}
390 
391 	switch (BTF_INT_ENCODING(*int_type)) {
392 	case 0:
393 		if (BTF_INT_BITS(*int_type) == 64)
394 			jsonw_printf(jw, "%llu", *(__u64 *)data);
395 		else if (BTF_INT_BITS(*int_type) == 32)
396 			jsonw_printf(jw, "%u", *(__u32 *)data);
397 		else if (BTF_INT_BITS(*int_type) == 16)
398 			jsonw_printf(jw, "%hu", *(__u16 *)data);
399 		else if (BTF_INT_BITS(*int_type) == 8)
400 			jsonw_printf(jw, "%hhu", *(__u8 *)data);
401 		else
402 			btf_dumper_int_bits(*int_type, bit_offset, data, jw,
403 					    is_plain_text);
404 		break;
405 	case BTF_INT_SIGNED:
406 		if (BTF_INT_BITS(*int_type) == 64)
407 			jsonw_printf(jw, "%lld", *(long long *)data);
408 		else if (BTF_INT_BITS(*int_type) == 32)
409 			jsonw_printf(jw, "%d", *(int *)data);
410 		else if (BTF_INT_BITS(*int_type) == 16)
411 			jsonw_printf(jw, "%hd", *(short *)data);
412 		else if (BTF_INT_BITS(*int_type) == 8)
413 			jsonw_printf(jw, "%hhd", *(char *)data);
414 		else
415 			btf_dumper_int_bits(*int_type, bit_offset, data, jw,
416 					    is_plain_text);
417 		break;
418 	case BTF_INT_CHAR:
419 		if (isprint(*(char *)data))
420 			jsonw_printf(jw, "\"%c\"", *(char *)data);
421 		else
422 			if (is_plain_text)
423 				jsonw_printf(jw, "0x%hhx", *(char *)data);
424 			else
425 				jsonw_printf(jw, "\"\\u00%02hhx\"",
426 					     *(char *)data);
427 		break;
428 	case BTF_INT_BOOL:
429 		jsonw_bool(jw, *(int *)data);
430 		break;
431 	default:
432 		/* shouldn't happen */
433 		return -EINVAL;
434 	}
435 
436 	return 0;
437 }
438 
439 static int btf_dumper_struct(const struct btf_dumper *d, __u32 type_id,
440 			     const void *data)
441 {
442 	const struct btf_type *t;
443 	struct btf_member *m;
444 	const void *data_off;
445 	int kind_flag;
446 	int ret = 0;
447 	int i, vlen;
448 
449 	t = btf__type_by_id(d->btf, type_id);
450 	if (!t)
451 		return -EINVAL;
452 
453 	kind_flag = BTF_INFO_KFLAG(t->info);
454 	vlen = BTF_INFO_VLEN(t->info);
455 	jsonw_start_object(d->jw);
456 	m = (struct btf_member *)(t + 1);
457 
458 	for (i = 0; i < vlen; i++) {
459 		__u32 bit_offset = m[i].offset;
460 		__u32 bitfield_size = 0;
461 
462 		if (kind_flag) {
463 			bitfield_size = BTF_MEMBER_BITFIELD_SIZE(bit_offset);
464 			bit_offset = BTF_MEMBER_BIT_OFFSET(bit_offset);
465 		}
466 
467 		jsonw_name(d->jw, btf__name_by_offset(d->btf, m[i].name_off));
468 		data_off = data + BITS_ROUNDDOWN_BYTES(bit_offset);
469 		if (bitfield_size) {
470 			btf_dumper_bitfield(bitfield_size,
471 					    BITS_PER_BYTE_MASKED(bit_offset),
472 					    data_off, d->jw, d->is_plain_text);
473 		} else {
474 			ret = btf_dumper_do_type(d, m[i].type,
475 						 BITS_PER_BYTE_MASKED(bit_offset),
476 						 data_off);
477 			if (ret)
478 				break;
479 		}
480 	}
481 
482 	jsonw_end_object(d->jw);
483 
484 	return ret;
485 }
486 
487 static int btf_dumper_var(const struct btf_dumper *d, __u32 type_id,
488 			  __u8 bit_offset, const void *data)
489 {
490 	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
491 	int ret;
492 
493 	jsonw_start_object(d->jw);
494 	jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
495 	ret = btf_dumper_do_type(d, t->type, bit_offset, data);
496 	jsonw_end_object(d->jw);
497 
498 	return ret;
499 }
500 
501 static int btf_dumper_datasec(const struct btf_dumper *d, __u32 type_id,
502 			      const void *data)
503 {
504 	struct btf_var_secinfo *vsi;
505 	const struct btf_type *t;
506 	int ret = 0, i, vlen;
507 
508 	t = btf__type_by_id(d->btf, type_id);
509 	if (!t)
510 		return -EINVAL;
511 
512 	vlen = BTF_INFO_VLEN(t->info);
513 	vsi = (struct btf_var_secinfo *)(t + 1);
514 
515 	jsonw_start_object(d->jw);
516 	jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
517 	jsonw_start_array(d->jw);
518 	for (i = 0; i < vlen; i++) {
519 		ret = btf_dumper_do_type(d, vsi[i].type, 0, data + vsi[i].offset);
520 		if (ret)
521 			break;
522 	}
523 	jsonw_end_array(d->jw);
524 	jsonw_end_object(d->jw);
525 
526 	return ret;
527 }
528 
529 static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
530 			      __u8 bit_offset, const void *data)
531 {
532 	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
533 
534 	switch (BTF_INFO_KIND(t->info)) {
535 	case BTF_KIND_INT:
536 		return btf_dumper_int(t, bit_offset, data, d->jw,
537 				     d->is_plain_text);
538 	case BTF_KIND_STRUCT:
539 	case BTF_KIND_UNION:
540 		return btf_dumper_struct(d, type_id, data);
541 	case BTF_KIND_ARRAY:
542 		return btf_dumper_array(d, type_id, data);
543 	case BTF_KIND_ENUM:
544 		return btf_dumper_enum(d, t, data);
545 	case BTF_KIND_PTR:
546 		btf_dumper_ptr(d, t, data);
547 		return 0;
548 	case BTF_KIND_UNKN:
549 		jsonw_printf(d->jw, "(unknown)");
550 		return 0;
551 	case BTF_KIND_FWD:
552 		/* map key or value can't be forward */
553 		jsonw_printf(d->jw, "(fwd-kind-invalid)");
554 		return -EINVAL;
555 	case BTF_KIND_TYPEDEF:
556 	case BTF_KIND_VOLATILE:
557 	case BTF_KIND_CONST:
558 	case BTF_KIND_RESTRICT:
559 		return btf_dumper_modifier(d, type_id, bit_offset, data);
560 	case BTF_KIND_VAR:
561 		return btf_dumper_var(d, type_id, bit_offset, data);
562 	case BTF_KIND_DATASEC:
563 		return btf_dumper_datasec(d, type_id, data);
564 	default:
565 		jsonw_printf(d->jw, "(unsupported-kind");
566 		return -EINVAL;
567 	}
568 }
569 
570 int btf_dumper_type(const struct btf_dumper *d, __u32 type_id,
571 		    const void *data)
572 {
573 	return btf_dumper_do_type(d, type_id, 0, data);
574 }
575 
576 #define BTF_PRINT_ARG(...)						\
577 	do {								\
578 		pos += snprintf(func_sig + pos, size - pos,		\
579 				__VA_ARGS__);				\
580 		if (pos >= size)					\
581 			return -1;					\
582 	} while (0)
583 #define BTF_PRINT_TYPE(type)					\
584 	do {								\
585 		pos = __btf_dumper_type_only(btf, type, func_sig,	\
586 					     pos, size);		\
587 		if (pos == -1)						\
588 			return -1;					\
589 	} while (0)
590 
591 static int __btf_dumper_type_only(const struct btf *btf, __u32 type_id,
592 				  char *func_sig, int pos, int size)
593 {
594 	const struct btf_type *proto_type;
595 	const struct btf_array *array;
596 	const struct btf_var *var;
597 	const struct btf_type *t;
598 
599 	if (!type_id) {
600 		BTF_PRINT_ARG("void ");
601 		return pos;
602 	}
603 
604 	t = btf__type_by_id(btf, type_id);
605 
606 	switch (BTF_INFO_KIND(t->info)) {
607 	case BTF_KIND_INT:
608 	case BTF_KIND_TYPEDEF:
609 	case BTF_KIND_FLOAT:
610 		BTF_PRINT_ARG("%s ", btf__name_by_offset(btf, t->name_off));
611 		break;
612 	case BTF_KIND_STRUCT:
613 		BTF_PRINT_ARG("struct %s ",
614 			      btf__name_by_offset(btf, t->name_off));
615 		break;
616 	case BTF_KIND_UNION:
617 		BTF_PRINT_ARG("union %s ",
618 			      btf__name_by_offset(btf, t->name_off));
619 		break;
620 	case BTF_KIND_ENUM:
621 		BTF_PRINT_ARG("enum %s ",
622 			      btf__name_by_offset(btf, t->name_off));
623 		break;
624 	case BTF_KIND_ARRAY:
625 		array = (struct btf_array *)(t + 1);
626 		BTF_PRINT_TYPE(array->type);
627 		BTF_PRINT_ARG("[%d]", array->nelems);
628 		break;
629 	case BTF_KIND_PTR:
630 		BTF_PRINT_TYPE(t->type);
631 		BTF_PRINT_ARG("* ");
632 		break;
633 	case BTF_KIND_FWD:
634 		BTF_PRINT_ARG("%s %s ",
635 			      BTF_INFO_KFLAG(t->info) ? "union" : "struct",
636 			      btf__name_by_offset(btf, t->name_off));
637 		break;
638 	case BTF_KIND_VOLATILE:
639 		BTF_PRINT_ARG("volatile ");
640 		BTF_PRINT_TYPE(t->type);
641 		break;
642 	case BTF_KIND_CONST:
643 		BTF_PRINT_ARG("const ");
644 		BTF_PRINT_TYPE(t->type);
645 		break;
646 	case BTF_KIND_RESTRICT:
647 		BTF_PRINT_ARG("restrict ");
648 		BTF_PRINT_TYPE(t->type);
649 		break;
650 	case BTF_KIND_FUNC_PROTO:
651 		pos = btf_dump_func(btf, func_sig, t, NULL, pos, size);
652 		if (pos == -1)
653 			return -1;
654 		break;
655 	case BTF_KIND_FUNC:
656 		proto_type = btf__type_by_id(btf, t->type);
657 		pos = btf_dump_func(btf, func_sig, proto_type, t, pos, size);
658 		if (pos == -1)
659 			return -1;
660 		break;
661 	case BTF_KIND_VAR:
662 		var = (struct btf_var *)(t + 1);
663 		if (var->linkage == BTF_VAR_STATIC)
664 			BTF_PRINT_ARG("static ");
665 		BTF_PRINT_TYPE(t->type);
666 		BTF_PRINT_ARG(" %s",
667 			      btf__name_by_offset(btf, t->name_off));
668 		break;
669 	case BTF_KIND_DATASEC:
670 		BTF_PRINT_ARG("section (\"%s\") ",
671 			      btf__name_by_offset(btf, t->name_off));
672 		break;
673 	case BTF_KIND_UNKN:
674 	default:
675 		return -1;
676 	}
677 
678 	return pos;
679 }
680 
681 static int btf_dump_func(const struct btf *btf, char *func_sig,
682 			 const struct btf_type *func_proto,
683 			 const struct btf_type *func, int pos, int size)
684 {
685 	int i, vlen;
686 
687 	BTF_PRINT_TYPE(func_proto->type);
688 	if (func)
689 		BTF_PRINT_ARG("%s(", btf__name_by_offset(btf, func->name_off));
690 	else
691 		BTF_PRINT_ARG("(");
692 	vlen = BTF_INFO_VLEN(func_proto->info);
693 	for (i = 0; i < vlen; i++) {
694 		struct btf_param *arg = &((struct btf_param *)(func_proto + 1))[i];
695 
696 		if (i)
697 			BTF_PRINT_ARG(", ");
698 		if (arg->type) {
699 			BTF_PRINT_TYPE(arg->type);
700 			if (arg->name_off)
701 				BTF_PRINT_ARG("%s",
702 					      btf__name_by_offset(btf, arg->name_off));
703 			else if (pos && func_sig[pos - 1] == ' ')
704 				/* Remove unnecessary space for
705 				 * FUNC_PROTO that does not have
706 				 * arg->name_off
707 				 */
708 				func_sig[--pos] = '\0';
709 		} else {
710 			BTF_PRINT_ARG("...");
711 		}
712 	}
713 	BTF_PRINT_ARG(")");
714 
715 	return pos;
716 }
717 
718 void btf_dumper_type_only(const struct btf *btf, __u32 type_id, char *func_sig,
719 			  int size)
720 {
721 	int err;
722 
723 	func_sig[0] = '\0';
724 	if (!btf)
725 		return;
726 
727 	err = __btf_dumper_type_only(btf, type_id, func_sig, 0, size);
728 	if (err < 0)
729 		func_sig[0] = '\0';
730 }
731 
732 static const char *ltrim(const char *s)
733 {
734 	while (isspace(*s))
735 		s++;
736 
737 	return s;
738 }
739 
740 void btf_dump_linfo_plain(const struct btf *btf,
741 			  const struct bpf_line_info *linfo,
742 			  const char *prefix, bool linum)
743 {
744 	const char *line = btf__name_by_offset(btf, linfo->line_off);
745 
746 	if (!line)
747 		return;
748 	line = ltrim(line);
749 
750 	if (!prefix)
751 		prefix = "";
752 
753 	if (linum) {
754 		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
755 
756 		/* More forgiving on file because linum option is
757 		 * expected to provide more info than the already
758 		 * available src line.
759 		 */
760 		if (!file)
761 			file = "";
762 
763 		printf("%s%s [file:%s line_num:%u line_col:%u]\n",
764 		       prefix, line, file,
765 		       BPF_LINE_INFO_LINE_NUM(linfo->line_col),
766 		       BPF_LINE_INFO_LINE_COL(linfo->line_col));
767 	} else {
768 		printf("%s%s\n", prefix, line);
769 	}
770 }
771 
772 void btf_dump_linfo_json(const struct btf *btf,
773 			 const struct bpf_line_info *linfo, bool linum)
774 {
775 	const char *line = btf__name_by_offset(btf, linfo->line_off);
776 
777 	if (line)
778 		jsonw_string_field(json_wtr, "src", ltrim(line));
779 
780 	if (linum) {
781 		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
782 
783 		if (file)
784 			jsonw_string_field(json_wtr, "file", file);
785 
786 		if (BPF_LINE_INFO_LINE_NUM(linfo->line_col))
787 			jsonw_int_field(json_wtr, "line_num",
788 					BPF_LINE_INFO_LINE_NUM(linfo->line_col));
789 
790 		if (BPF_LINE_INFO_LINE_COL(linfo->line_col))
791 			jsonw_int_field(json_wtr, "line_col",
792 					BPF_LINE_INFO_LINE_COL(linfo->line_col));
793 	}
794 }
795