xref: /openbmc/linux/tools/bpf/bpftool/btf_dumper.c (revision 6a143a7c)
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 	struct bpf_prog_info_linear *prog_info = NULL;
36 	const struct btf_type *func_type;
37 	const char *prog_name = NULL;
38 	struct bpf_func_info *finfo;
39 	struct btf *prog_btf = NULL;
40 	struct bpf_prog_info *info;
41 	int prog_fd, func_sig_len;
42 	char prog_str[1024];
43 
44 	/* Get the ptr's func_proto */
45 	func_sig_len = btf_dump_func(d->btf, prog_str, func_proto, NULL, 0,
46 				     sizeof(prog_str));
47 	if (func_sig_len == -1)
48 		return -1;
49 
50 	if (!prog_id)
51 		goto print;
52 
53 	/* Get the bpf_prog's name.  Obtain from func_info. */
54 	prog_fd = bpf_prog_get_fd_by_id(prog_id);
55 	if (prog_fd == -1)
56 		goto print;
57 
58 	prog_info = bpf_program__get_prog_info_linear(prog_fd,
59 						1UL << BPF_PROG_INFO_FUNC_INFO);
60 	close(prog_fd);
61 	if (IS_ERR(prog_info)) {
62 		prog_info = NULL;
63 		goto print;
64 	}
65 	info = &prog_info->info;
66 
67 	if (!info->btf_id || !info->nr_func_info ||
68 	    btf__get_from_id(info->btf_id, &prog_btf))
69 		goto print;
70 	finfo = u64_to_ptr(info->func_info);
71 	func_type = btf__type_by_id(prog_btf, finfo->type_id);
72 	if (!func_type || !btf_is_func(func_type))
73 		goto print;
74 
75 	prog_name = btf__name_by_offset(prog_btf, func_type->name_off);
76 
77 print:
78 	if (!prog_id)
79 		snprintf(&prog_str[func_sig_len],
80 			 sizeof(prog_str) - func_sig_len, " 0");
81 	else if (prog_name)
82 		snprintf(&prog_str[func_sig_len],
83 			 sizeof(prog_str) - func_sig_len,
84 			 " %s/prog_id:%u", prog_name, prog_id);
85 	else
86 		snprintf(&prog_str[func_sig_len],
87 			 sizeof(prog_str) - func_sig_len,
88 			 " <unknown_prog_name>/prog_id:%u", prog_id);
89 
90 	prog_str[sizeof(prog_str) - 1] = '\0';
91 	jsonw_string(d->jw, prog_str);
92 	btf__free(prog_btf);
93 	free(prog_info);
94 	return 0;
95 }
96 
97 static void btf_dumper_ptr(const struct btf_dumper *d,
98 			   const struct btf_type *t,
99 			   const void *data)
100 {
101 	unsigned long value = *(unsigned long *)data;
102 	const struct btf_type *ptr_type;
103 	__s32 ptr_type_id;
104 
105 	if (!d->prog_id_as_func_ptr || value > UINT32_MAX)
106 		goto print_ptr_value;
107 
108 	ptr_type_id = btf__resolve_type(d->btf, t->type);
109 	if (ptr_type_id < 0)
110 		goto print_ptr_value;
111 	ptr_type = btf__type_by_id(d->btf, ptr_type_id);
112 	if (!ptr_type || !btf_is_func_proto(ptr_type))
113 		goto print_ptr_value;
114 
115 	if (!dump_prog_id_as_func_ptr(d, ptr_type, value))
116 		return;
117 
118 print_ptr_value:
119 	if (d->is_plain_text)
120 		jsonw_printf(d->jw, "%p", (void *)value);
121 	else
122 		jsonw_printf(d->jw, "%lu", value);
123 }
124 
125 static int btf_dumper_modifier(const struct btf_dumper *d, __u32 type_id,
126 			       __u8 bit_offset, const void *data)
127 {
128 	int actual_type_id;
129 
130 	actual_type_id = btf__resolve_type(d->btf, type_id);
131 	if (actual_type_id < 0)
132 		return actual_type_id;
133 
134 	return btf_dumper_do_type(d, actual_type_id, bit_offset, data);
135 }
136 
137 static int btf_dumper_enum(const struct btf_dumper *d,
138 			    const struct btf_type *t,
139 			    const void *data)
140 {
141 	const struct btf_enum *enums = btf_enum(t);
142 	__s64 value;
143 	__u16 i;
144 
145 	switch (t->size) {
146 	case 8:
147 		value = *(__s64 *)data;
148 		break;
149 	case 4:
150 		value = *(__s32 *)data;
151 		break;
152 	case 2:
153 		value = *(__s16 *)data;
154 		break;
155 	case 1:
156 		value = *(__s8 *)data;
157 		break;
158 	default:
159 		return -EINVAL;
160 	}
161 
162 	for (i = 0; i < btf_vlen(t); i++) {
163 		if (value == enums[i].val) {
164 			jsonw_string(d->jw,
165 				     btf__name_by_offset(d->btf,
166 							 enums[i].name_off));
167 			return 0;
168 		}
169 	}
170 
171 	jsonw_int(d->jw, value);
172 	return 0;
173 }
174 
175 static bool is_str_array(const struct btf *btf, const struct btf_array *arr,
176 			 const char *s)
177 {
178 	const struct btf_type *elem_type;
179 	const char *end_s;
180 
181 	if (!arr->nelems)
182 		return false;
183 
184 	elem_type = btf__type_by_id(btf, arr->type);
185 	/* Not skipping typedef.  typedef to char does not count as
186 	 * a string now.
187 	 */
188 	while (elem_type && btf_is_mod(elem_type))
189 		elem_type = btf__type_by_id(btf, elem_type->type);
190 
191 	if (!elem_type || !btf_is_int(elem_type) || elem_type->size != 1)
192 		return false;
193 
194 	if (btf_int_encoding(elem_type) != BTF_INT_CHAR &&
195 	    strcmp("char", btf__name_by_offset(btf, elem_type->name_off)))
196 		return false;
197 
198 	end_s = s + arr->nelems;
199 	while (s < end_s) {
200 		if (!*s)
201 			return true;
202 		if (*s <= 0x1f || *s >= 0x7f)
203 			return false;
204 		s++;
205 	}
206 
207 	/* '\0' is not found */
208 	return false;
209 }
210 
211 static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
212 			    const void *data)
213 {
214 	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
215 	struct btf_array *arr = (struct btf_array *)(t + 1);
216 	long long elem_size;
217 	int ret = 0;
218 	__u32 i;
219 
220 	if (is_str_array(d->btf, arr, data)) {
221 		jsonw_string(d->jw, data);
222 		return 0;
223 	}
224 
225 	elem_size = btf__resolve_size(d->btf, arr->type);
226 	if (elem_size < 0)
227 		return elem_size;
228 
229 	jsonw_start_array(d->jw);
230 	for (i = 0; i < arr->nelems; i++) {
231 		ret = btf_dumper_do_type(d, arr->type, 0,
232 					 data + i * elem_size);
233 		if (ret)
234 			break;
235 	}
236 
237 	jsonw_end_array(d->jw);
238 	return ret;
239 }
240 
241 static void btf_int128_print(json_writer_t *jw, const void *data,
242 			     bool is_plain_text)
243 {
244 	/* data points to a __int128 number.
245 	 * Suppose
246 	 *     int128_num = *(__int128 *)data;
247 	 * The below formulas shows what upper_num and lower_num represents:
248 	 *     upper_num = int128_num >> 64;
249 	 *     lower_num = int128_num & 0xffffffffFFFFFFFFULL;
250 	 */
251 	__u64 upper_num, lower_num;
252 
253 #ifdef __BIG_ENDIAN_BITFIELD
254 	upper_num = *(__u64 *)data;
255 	lower_num = *(__u64 *)(data + 8);
256 #else
257 	upper_num = *(__u64 *)(data + 8);
258 	lower_num = *(__u64 *)data;
259 #endif
260 
261 	if (is_plain_text) {
262 		if (upper_num == 0)
263 			jsonw_printf(jw, "0x%llx", lower_num);
264 		else
265 			jsonw_printf(jw, "0x%llx%016llx", upper_num, lower_num);
266 	} else {
267 		if (upper_num == 0)
268 			jsonw_printf(jw, "\"0x%llx\"", lower_num);
269 		else
270 			jsonw_printf(jw, "\"0x%llx%016llx\"", upper_num, lower_num);
271 	}
272 }
273 
274 static void btf_int128_shift(__u64 *print_num, __u16 left_shift_bits,
275 			     __u16 right_shift_bits)
276 {
277 	__u64 upper_num, lower_num;
278 
279 #ifdef __BIG_ENDIAN_BITFIELD
280 	upper_num = print_num[0];
281 	lower_num = print_num[1];
282 #else
283 	upper_num = print_num[1];
284 	lower_num = print_num[0];
285 #endif
286 
287 	/* shake out un-needed bits by shift/or operations */
288 	if (left_shift_bits >= 64) {
289 		upper_num = lower_num << (left_shift_bits - 64);
290 		lower_num = 0;
291 	} else {
292 		upper_num = (upper_num << left_shift_bits) |
293 			    (lower_num >> (64 - left_shift_bits));
294 		lower_num = lower_num << left_shift_bits;
295 	}
296 
297 	if (right_shift_bits >= 64) {
298 		lower_num = upper_num >> (right_shift_bits - 64);
299 		upper_num = 0;
300 	} else {
301 		lower_num = (lower_num >> right_shift_bits) |
302 			    (upper_num << (64 - right_shift_bits));
303 		upper_num = upper_num >> right_shift_bits;
304 	}
305 
306 #ifdef __BIG_ENDIAN_BITFIELD
307 	print_num[0] = upper_num;
308 	print_num[1] = lower_num;
309 #else
310 	print_num[0] = lower_num;
311 	print_num[1] = upper_num;
312 #endif
313 }
314 
315 static void btf_dumper_bitfield(__u32 nr_bits, __u8 bit_offset,
316 				const void *data, json_writer_t *jw,
317 				bool is_plain_text)
318 {
319 	int left_shift_bits, right_shift_bits;
320 	__u64 print_num[2] = {};
321 	int bytes_to_copy;
322 	int bits_to_copy;
323 
324 	bits_to_copy = bit_offset + nr_bits;
325 	bytes_to_copy = BITS_ROUNDUP_BYTES(bits_to_copy);
326 
327 	memcpy(print_num, data, bytes_to_copy);
328 #if defined(__BIG_ENDIAN_BITFIELD)
329 	left_shift_bits = bit_offset;
330 #elif defined(__LITTLE_ENDIAN_BITFIELD)
331 	left_shift_bits = 128 - bits_to_copy;
332 #else
333 #error neither big nor little endian
334 #endif
335 	right_shift_bits = 128 - nr_bits;
336 
337 	btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
338 	btf_int128_print(jw, print_num, is_plain_text);
339 }
340 
341 
342 static void btf_dumper_int_bits(__u32 int_type, __u8 bit_offset,
343 				const void *data, json_writer_t *jw,
344 				bool is_plain_text)
345 {
346 	int nr_bits = BTF_INT_BITS(int_type);
347 	int total_bits_offset;
348 
349 	/* bits_offset is at most 7.
350 	 * BTF_INT_OFFSET() cannot exceed 128 bits.
351 	 */
352 	total_bits_offset = bit_offset + BTF_INT_OFFSET(int_type);
353 	data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
354 	bit_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
355 	btf_dumper_bitfield(nr_bits, bit_offset, data, jw,
356 			    is_plain_text);
357 }
358 
359 static int btf_dumper_int(const struct btf_type *t, __u8 bit_offset,
360 			  const void *data, json_writer_t *jw,
361 			  bool is_plain_text)
362 {
363 	__u32 *int_type;
364 	__u32 nr_bits;
365 
366 	int_type = (__u32 *)(t + 1);
367 	nr_bits = BTF_INT_BITS(*int_type);
368 	/* if this is bit field */
369 	if (bit_offset || BTF_INT_OFFSET(*int_type) ||
370 	    BITS_PER_BYTE_MASKED(nr_bits)) {
371 		btf_dumper_int_bits(*int_type, bit_offset, data, jw,
372 				    is_plain_text);
373 		return 0;
374 	}
375 
376 	if (nr_bits == 128) {
377 		btf_int128_print(jw, data, is_plain_text);
378 		return 0;
379 	}
380 
381 	switch (BTF_INT_ENCODING(*int_type)) {
382 	case 0:
383 		if (BTF_INT_BITS(*int_type) == 64)
384 			jsonw_printf(jw, "%llu", *(__u64 *)data);
385 		else if (BTF_INT_BITS(*int_type) == 32)
386 			jsonw_printf(jw, "%u", *(__u32 *)data);
387 		else if (BTF_INT_BITS(*int_type) == 16)
388 			jsonw_printf(jw, "%hu", *(__u16 *)data);
389 		else if (BTF_INT_BITS(*int_type) == 8)
390 			jsonw_printf(jw, "%hhu", *(__u8 *)data);
391 		else
392 			btf_dumper_int_bits(*int_type, bit_offset, data, jw,
393 					    is_plain_text);
394 		break;
395 	case BTF_INT_SIGNED:
396 		if (BTF_INT_BITS(*int_type) == 64)
397 			jsonw_printf(jw, "%lld", *(long long *)data);
398 		else if (BTF_INT_BITS(*int_type) == 32)
399 			jsonw_printf(jw, "%d", *(int *)data);
400 		else if (BTF_INT_BITS(*int_type) == 16)
401 			jsonw_printf(jw, "%hd", *(short *)data);
402 		else if (BTF_INT_BITS(*int_type) == 8)
403 			jsonw_printf(jw, "%hhd", *(char *)data);
404 		else
405 			btf_dumper_int_bits(*int_type, bit_offset, data, jw,
406 					    is_plain_text);
407 		break;
408 	case BTF_INT_CHAR:
409 		if (isprint(*(char *)data))
410 			jsonw_printf(jw, "\"%c\"", *(char *)data);
411 		else
412 			if (is_plain_text)
413 				jsonw_printf(jw, "0x%hhx", *(char *)data);
414 			else
415 				jsonw_printf(jw, "\"\\u00%02hhx\"",
416 					     *(char *)data);
417 		break;
418 	case BTF_INT_BOOL:
419 		jsonw_bool(jw, *(int *)data);
420 		break;
421 	default:
422 		/* shouldn't happen */
423 		return -EINVAL;
424 	}
425 
426 	return 0;
427 }
428 
429 static int btf_dumper_struct(const struct btf_dumper *d, __u32 type_id,
430 			     const void *data)
431 {
432 	const struct btf_type *t;
433 	struct btf_member *m;
434 	const void *data_off;
435 	int kind_flag;
436 	int ret = 0;
437 	int i, vlen;
438 
439 	t = btf__type_by_id(d->btf, type_id);
440 	if (!t)
441 		return -EINVAL;
442 
443 	kind_flag = BTF_INFO_KFLAG(t->info);
444 	vlen = BTF_INFO_VLEN(t->info);
445 	jsonw_start_object(d->jw);
446 	m = (struct btf_member *)(t + 1);
447 
448 	for (i = 0; i < vlen; i++) {
449 		__u32 bit_offset = m[i].offset;
450 		__u32 bitfield_size = 0;
451 
452 		if (kind_flag) {
453 			bitfield_size = BTF_MEMBER_BITFIELD_SIZE(bit_offset);
454 			bit_offset = BTF_MEMBER_BIT_OFFSET(bit_offset);
455 		}
456 
457 		jsonw_name(d->jw, btf__name_by_offset(d->btf, m[i].name_off));
458 		data_off = data + BITS_ROUNDDOWN_BYTES(bit_offset);
459 		if (bitfield_size) {
460 			btf_dumper_bitfield(bitfield_size,
461 					    BITS_PER_BYTE_MASKED(bit_offset),
462 					    data_off, d->jw, d->is_plain_text);
463 		} else {
464 			ret = btf_dumper_do_type(d, m[i].type,
465 						 BITS_PER_BYTE_MASKED(bit_offset),
466 						 data_off);
467 			if (ret)
468 				break;
469 		}
470 	}
471 
472 	jsonw_end_object(d->jw);
473 
474 	return ret;
475 }
476 
477 static int btf_dumper_var(const struct btf_dumper *d, __u32 type_id,
478 			  __u8 bit_offset, const void *data)
479 {
480 	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
481 	int ret;
482 
483 	jsonw_start_object(d->jw);
484 	jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
485 	ret = btf_dumper_do_type(d, t->type, bit_offset, data);
486 	jsonw_end_object(d->jw);
487 
488 	return ret;
489 }
490 
491 static int btf_dumper_datasec(const struct btf_dumper *d, __u32 type_id,
492 			      const void *data)
493 {
494 	struct btf_var_secinfo *vsi;
495 	const struct btf_type *t;
496 	int ret = 0, i, vlen;
497 
498 	t = btf__type_by_id(d->btf, type_id);
499 	if (!t)
500 		return -EINVAL;
501 
502 	vlen = BTF_INFO_VLEN(t->info);
503 	vsi = (struct btf_var_secinfo *)(t + 1);
504 
505 	jsonw_start_object(d->jw);
506 	jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
507 	jsonw_start_array(d->jw);
508 	for (i = 0; i < vlen; i++) {
509 		ret = btf_dumper_do_type(d, vsi[i].type, 0, data + vsi[i].offset);
510 		if (ret)
511 			break;
512 	}
513 	jsonw_end_array(d->jw);
514 	jsonw_end_object(d->jw);
515 
516 	return ret;
517 }
518 
519 static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
520 			      __u8 bit_offset, const void *data)
521 {
522 	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
523 
524 	switch (BTF_INFO_KIND(t->info)) {
525 	case BTF_KIND_INT:
526 		return btf_dumper_int(t, bit_offset, data, d->jw,
527 				     d->is_plain_text);
528 	case BTF_KIND_STRUCT:
529 	case BTF_KIND_UNION:
530 		return btf_dumper_struct(d, type_id, data);
531 	case BTF_KIND_ARRAY:
532 		return btf_dumper_array(d, type_id, data);
533 	case BTF_KIND_ENUM:
534 		return btf_dumper_enum(d, t, data);
535 	case BTF_KIND_PTR:
536 		btf_dumper_ptr(d, t, data);
537 		return 0;
538 	case BTF_KIND_UNKN:
539 		jsonw_printf(d->jw, "(unknown)");
540 		return 0;
541 	case BTF_KIND_FWD:
542 		/* map key or value can't be forward */
543 		jsonw_printf(d->jw, "(fwd-kind-invalid)");
544 		return -EINVAL;
545 	case BTF_KIND_TYPEDEF:
546 	case BTF_KIND_VOLATILE:
547 	case BTF_KIND_CONST:
548 	case BTF_KIND_RESTRICT:
549 		return btf_dumper_modifier(d, type_id, bit_offset, data);
550 	case BTF_KIND_VAR:
551 		return btf_dumper_var(d, type_id, bit_offset, data);
552 	case BTF_KIND_DATASEC:
553 		return btf_dumper_datasec(d, type_id, data);
554 	default:
555 		jsonw_printf(d->jw, "(unsupported-kind");
556 		return -EINVAL;
557 	}
558 }
559 
560 int btf_dumper_type(const struct btf_dumper *d, __u32 type_id,
561 		    const void *data)
562 {
563 	return btf_dumper_do_type(d, type_id, 0, data);
564 }
565 
566 #define BTF_PRINT_ARG(...)						\
567 	do {								\
568 		pos += snprintf(func_sig + pos, size - pos,		\
569 				__VA_ARGS__);				\
570 		if (pos >= size)					\
571 			return -1;					\
572 	} while (0)
573 #define BTF_PRINT_TYPE(type)					\
574 	do {								\
575 		pos = __btf_dumper_type_only(btf, type, func_sig,	\
576 					     pos, size);		\
577 		if (pos == -1)						\
578 			return -1;					\
579 	} while (0)
580 
581 static int __btf_dumper_type_only(const struct btf *btf, __u32 type_id,
582 				  char *func_sig, int pos, int size)
583 {
584 	const struct btf_type *proto_type;
585 	const struct btf_array *array;
586 	const struct btf_var *var;
587 	const struct btf_type *t;
588 
589 	if (!type_id) {
590 		BTF_PRINT_ARG("void ");
591 		return pos;
592 	}
593 
594 	t = btf__type_by_id(btf, type_id);
595 
596 	switch (BTF_INFO_KIND(t->info)) {
597 	case BTF_KIND_INT:
598 	case BTF_KIND_TYPEDEF:
599 	case BTF_KIND_FLOAT:
600 		BTF_PRINT_ARG("%s ", btf__name_by_offset(btf, t->name_off));
601 		break;
602 	case BTF_KIND_STRUCT:
603 		BTF_PRINT_ARG("struct %s ",
604 			      btf__name_by_offset(btf, t->name_off));
605 		break;
606 	case BTF_KIND_UNION:
607 		BTF_PRINT_ARG("union %s ",
608 			      btf__name_by_offset(btf, t->name_off));
609 		break;
610 	case BTF_KIND_ENUM:
611 		BTF_PRINT_ARG("enum %s ",
612 			      btf__name_by_offset(btf, t->name_off));
613 		break;
614 	case BTF_KIND_ARRAY:
615 		array = (struct btf_array *)(t + 1);
616 		BTF_PRINT_TYPE(array->type);
617 		BTF_PRINT_ARG("[%d]", array->nelems);
618 		break;
619 	case BTF_KIND_PTR:
620 		BTF_PRINT_TYPE(t->type);
621 		BTF_PRINT_ARG("* ");
622 		break;
623 	case BTF_KIND_FWD:
624 		BTF_PRINT_ARG("%s %s ",
625 			      BTF_INFO_KFLAG(t->info) ? "union" : "struct",
626 			      btf__name_by_offset(btf, t->name_off));
627 		break;
628 	case BTF_KIND_VOLATILE:
629 		BTF_PRINT_ARG("volatile ");
630 		BTF_PRINT_TYPE(t->type);
631 		break;
632 	case BTF_KIND_CONST:
633 		BTF_PRINT_ARG("const ");
634 		BTF_PRINT_TYPE(t->type);
635 		break;
636 	case BTF_KIND_RESTRICT:
637 		BTF_PRINT_ARG("restrict ");
638 		BTF_PRINT_TYPE(t->type);
639 		break;
640 	case BTF_KIND_FUNC_PROTO:
641 		pos = btf_dump_func(btf, func_sig, t, NULL, pos, size);
642 		if (pos == -1)
643 			return -1;
644 		break;
645 	case BTF_KIND_FUNC:
646 		proto_type = btf__type_by_id(btf, t->type);
647 		pos = btf_dump_func(btf, func_sig, proto_type, t, pos, size);
648 		if (pos == -1)
649 			return -1;
650 		break;
651 	case BTF_KIND_VAR:
652 		var = (struct btf_var *)(t + 1);
653 		if (var->linkage == BTF_VAR_STATIC)
654 			BTF_PRINT_ARG("static ");
655 		BTF_PRINT_TYPE(t->type);
656 		BTF_PRINT_ARG(" %s",
657 			      btf__name_by_offset(btf, t->name_off));
658 		break;
659 	case BTF_KIND_DATASEC:
660 		BTF_PRINT_ARG("section (\"%s\") ",
661 			      btf__name_by_offset(btf, t->name_off));
662 		break;
663 	case BTF_KIND_UNKN:
664 	default:
665 		return -1;
666 	}
667 
668 	return pos;
669 }
670 
671 static int btf_dump_func(const struct btf *btf, char *func_sig,
672 			 const struct btf_type *func_proto,
673 			 const struct btf_type *func, int pos, int size)
674 {
675 	int i, vlen;
676 
677 	BTF_PRINT_TYPE(func_proto->type);
678 	if (func)
679 		BTF_PRINT_ARG("%s(", btf__name_by_offset(btf, func->name_off));
680 	else
681 		BTF_PRINT_ARG("(");
682 	vlen = BTF_INFO_VLEN(func_proto->info);
683 	for (i = 0; i < vlen; i++) {
684 		struct btf_param *arg = &((struct btf_param *)(func_proto + 1))[i];
685 
686 		if (i)
687 			BTF_PRINT_ARG(", ");
688 		if (arg->type) {
689 			BTF_PRINT_TYPE(arg->type);
690 			if (arg->name_off)
691 				BTF_PRINT_ARG("%s",
692 					      btf__name_by_offset(btf, arg->name_off));
693 			else if (pos && func_sig[pos - 1] == ' ')
694 				/* Remove unnecessary space for
695 				 * FUNC_PROTO that does not have
696 				 * arg->name_off
697 				 */
698 				func_sig[--pos] = '\0';
699 		} else {
700 			BTF_PRINT_ARG("...");
701 		}
702 	}
703 	BTF_PRINT_ARG(")");
704 
705 	return pos;
706 }
707 
708 void btf_dumper_type_only(const struct btf *btf, __u32 type_id, char *func_sig,
709 			  int size)
710 {
711 	int err;
712 
713 	func_sig[0] = '\0';
714 	if (!btf)
715 		return;
716 
717 	err = __btf_dumper_type_only(btf, type_id, func_sig, 0, size);
718 	if (err < 0)
719 		func_sig[0] = '\0';
720 }
721 
722 static const char *ltrim(const char *s)
723 {
724 	while (isspace(*s))
725 		s++;
726 
727 	return s;
728 }
729 
730 void btf_dump_linfo_plain(const struct btf *btf,
731 			  const struct bpf_line_info *linfo,
732 			  const char *prefix, bool linum)
733 {
734 	const char *line = btf__name_by_offset(btf, linfo->line_off);
735 
736 	if (!line)
737 		return;
738 	line = ltrim(line);
739 
740 	if (!prefix)
741 		prefix = "";
742 
743 	if (linum) {
744 		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
745 
746 		/* More forgiving on file because linum option is
747 		 * expected to provide more info than the already
748 		 * available src line.
749 		 */
750 		if (!file)
751 			file = "";
752 
753 		printf("%s%s [file:%s line_num:%u line_col:%u]\n",
754 		       prefix, line, file,
755 		       BPF_LINE_INFO_LINE_NUM(linfo->line_col),
756 		       BPF_LINE_INFO_LINE_COL(linfo->line_col));
757 	} else {
758 		printf("%s%s\n", prefix, line);
759 	}
760 }
761 
762 void btf_dump_linfo_json(const struct btf *btf,
763 			 const struct bpf_line_info *linfo, bool linum)
764 {
765 	const char *line = btf__name_by_offset(btf, linfo->line_off);
766 
767 	if (line)
768 		jsonw_string_field(json_wtr, "src", ltrim(line));
769 
770 	if (linum) {
771 		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
772 
773 		if (file)
774 			jsonw_string_field(json_wtr, "file", file);
775 
776 		if (BPF_LINE_INFO_LINE_NUM(linfo->line_col))
777 			jsonw_int_field(json_wtr, "line_num",
778 					BPF_LINE_INFO_LINE_NUM(linfo->line_col));
779 
780 		if (BPF_LINE_INFO_LINE_COL(linfo->line_col))
781 			jsonw_int_field(json_wtr, "line_col",
782 					BPF_LINE_INFO_LINE_COL(linfo->line_col));
783 	}
784 }
785