aboutsummaryrefslogtreecommitdiffstats
path: root/tools/perf/util/symbol.c
blob: 86e14375e74e3a4990f536bc8baebb913b86e75b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
#include "util.h"
#include "../perf.h"
#include "string.h"
#include "symbol.h"

#include <libelf.h>
#include <gelf.h>
#include <elf.h>

const char *sym_hist_filter;

static struct symbol *symbol__new(u64 start, u64 len,
				  const char *name, unsigned int priv_size,
				  u64 obj_start, int verbose)
{
	size_t namelen = strlen(name) + 1;
	struct symbol *self = calloc(1, priv_size + sizeof(*self) + namelen);

	if (!self)
		return NULL;

	if (verbose >= 2)
		printf("new symbol: %016Lx [%08lx]: %s, hist: %p, obj_start: %p\n",
			(u64)start, (unsigned long)len, name, self->hist, (void *)(unsigned long)obj_start);

	self->obj_start= obj_start;
	self->hist = NULL;
	self->hist_sum = 0;

	if (sym_hist_filter && !strcmp(name, sym_hist_filter))
		self->hist = calloc(sizeof(u64), len);

	if (priv_size) {
		memset(self, 0, priv_size);
		self = ((void *)self) + priv_size;
	}
	self->start = start;
	self->end   = start + len - 1;
	memcpy(self->name, name, namelen);

	return self;
}

static void symbol__delete(struct symbol *self, unsigned int priv_size)
{
	free(((void *)self) - priv_size);
}

static size_t symbol__fprintf(struct symbol *self, FILE *fp)
{
	return fprintf(fp, " %llx-%llx %s\n",
		       self->start, self->end, self->name);
}

struct dso *dso__new(const char *name, unsigned int sym_priv_size)
{
	struct dso *self = malloc(sizeof(*self) + strlen(name) + 1);

	if (self != NULL) {
		strcpy(self->name, name);
		self->syms = RB_ROOT;
		self->sym_priv_size = sym_priv_size;
		self->find_symbol = dso__find_symbol;
	}

	return self;
}

static void dso__delete_symbols(struct dso *self)
{
	struct symbol *pos;
	struct rb_node *next = rb_first(&self->syms);

	while (next) {
		pos = rb_entry(next, struct symbol, rb_node);
		next = rb_next(&pos->rb_node);
		rb_erase(&pos->rb_node, &self->syms);
		symbol__delete(pos, self->sym_priv_size);
	}
}

void dso__delete(struct dso *self)
{
	dso__delete_symbols(self);
	free(self);
}

static void dso__insert_symbol(struct dso *self, struct symbol *sym)
{
	struct rb_node **p = &self->syms.rb_node;
	struct rb_node *parent = NULL;
	const u64 ip = sym->start;
	struct symbol *s;

	while (*p != NULL) {
		parent = *p;
		s = rb_entry(parent, struct symbol, rb_node);
		if (ip < s->start)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}
	rb_link_node(&sym->rb_node, parent, p);
	rb_insert_color(&sym->rb_node, &self->syms);
}

struct symbol *dso__find_symbol(struct dso *self, u64 ip)
{
	struct rb_node *n;

	if (self == NULL)
		return NULL;

	n = self->syms.rb_node;

	while (n) {
		struct symbol *s = rb_entry(n, struct symbol, rb_node);

		if (ip < s->start)
			n = n->rb_left;
		else if (ip > s->end)
			n = n->rb_right;
		else
			return s;
	}

	return NULL;
}

size_t dso__fprintf(struct dso *self, FILE *fp)
{
	size_t ret = fprintf(fp, "dso: %s\n", self->name);

	struct rb_node *nd;
	for (nd = rb_first(&self->syms); nd; nd = rb_next(nd)) {
		struct symbol *pos = rb_entry(nd, struct symbol, rb_node);
		ret += symbol__fprintf(pos, fp);
	}

	return ret;
}

static int dso__load_kallsyms(struct dso *self, symbol_filter_t filter, int verbose)
{
	struct rb_node *nd, *prevnd;
	char *line = NULL;
	size_t n;
	FILE *file = fopen("/proc/kallsyms", "r");

	if (file == NULL)
		goto out_failure;

	while (!feof(file)) {
		u64 start;
		struct symbol *sym;
		int line_len, len;
		char symbol_type;

		line_len = getline(&line, &n, file);
		if (line_len < 0)
			break;

		if (!line)
			goto out_failure;

		line[--line_len] = '\0'; /* \n */

		len = hex2u64(line, &start);

		len++;
		if (len + 2 >= line_len)
			continue;

		symbol_type = toupper(line[len]);
		/*
		 * We're interested only in code ('T'ext)
		 */
		if (symbol_type != 'T' && symbol_type != 'W')
			continue;
		/*
		 * Well fix up the end later, when we have all sorted.
		 */
		sym = symbol__new(start, 0xdead, line + len + 2,
				  self->sym_priv_size, 0, verbose);

		if (sym == NULL)
			goto out_delete_line;

		if (filter && filter(self, sym))
			symbol__delete(sym, self->sym_priv_size);
		else
			dso__insert_symbol(self, sym);
	}

	/*
	 * Now that we have all sorted out, just set the ->end of all
	 * symbols
	 */
	prevnd = rb_first(&self->syms);

	if (prevnd == NULL)
		goto out_delete_line;

	for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {
		struct symbol *prev = rb_entry(prevnd, struct symbol, rb_node),
			      *curr = rb_entry(nd, struct symbol, rb_node);

		prev->end = curr->start - 1;
		prevnd = nd;
	}

	free(line);
	fclose(file);

	return 0;

out_delete_line:
	free(line);
out_failure:
	return -1;
}

static int dso__load_perf_map(struct dso *self, symbol_filter_t filter, int verbose)
{
	char *line = NULL;
	size_t n;
	FILE *file;
	int nr_syms = 0;

	file = fopen(self->name, "r");
	if (file == NULL)
		goto out_failure;

	while (!feof(file)) {
		u64 start, size;
		struct symbol *sym;
		int line_len, len;

		line_len = getline(&line, &n, file);
		if (line_len < 0)
			break;

		if (!line)
			goto out_failure;

		line[--line_len] = '\0'; /* \n */

		len = hex2u64(line, &start);

		len++;
		if (len + 2 >= line_len)
			continue;

		len += hex2u64(line + len, &size);

		len++;
		if (len + 2 >= line_len)
			continue;

		sym = symbol__new(start, size, line + len,
				  self->sym_priv_size, start, verbose);

		if (sym == NULL)
			goto out_delete_line;

		if (filter && filter(self, sym))
			symbol__delete(sym, self->sym_priv_size);
		else {
			dso__insert_symbol(self, sym);
			nr_syms++;
		}
	}

	free(line);
	fclose(file);

	return nr_syms;

out_delete_line:
	free(line);
out_failure:
	return -1;
}

/**
 * elf_symtab__for_each_symbol - iterate thru all the symbols
 *
 * @self: struct elf_symtab instance to iterate
 * @index: uint32_t index
 * @sym: GElf_Sym iterator
 */
#define elf_symtab__for_each_symbol(syms, nr_syms, index, sym) \
	for (index = 0, gelf_getsym(syms, index, &sym);\
	     index < nr_syms; \
	     index++, gelf_getsym(syms, index, &sym))

static inline uint8_t elf_sym__type(const GElf_Sym *sym)
{
	return GELF_ST_TYPE(sym->st_info);
}

static inline int elf_sym__is_function(const GElf_Sym *sym)
{
	return elf_sym__type(sym) == STT_FUNC &&
	       sym->st_name != 0 &&
	       sym->st_shndx != SHN_UNDEF &&
	       sym->st_size != 0;
}

static inline const char *elf_sym__name(const GElf_Sym *sym,
					const Elf_Data *symstrs)
{
	return symstrs->d_buf + sym->st_name;
}

static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
				    GElf_Shdr *shp, const char *name,
				    size_t *index)
{
	Elf_Scn *sec = NULL;
	size_t cnt = 1;

	while ((sec = elf_nextscn(elf, sec)) != NULL) {
		char *str;

		gelf_getshdr(sec, shp);
		str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
		if (!strcmp(name, str)) {
			if (index)
				*index = cnt;
			break;
		}
		++cnt;
	}

	return sec;
}

#define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
	for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
	     idx < nr_entries; \
	     ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))

#define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
	for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
	     idx < nr_entries; \
	     ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))

static int dso__synthesize_plt_symbols(struct  dso *self, Elf *elf,
				       GElf_Ehdr *ehdr, Elf_Scn *scn_dynsym,
				       GElf_Shdr *shdr_dynsym,
				       size_t dynsym_idx, int verbose)
{
	uint32_t nr_rel_entries, idx;
	GElf_Sym sym;
	u64 plt_offset;
	GElf_Shdr shdr_plt;
	struct symbol *f;
	GElf_Shdr shdr_rel_plt;
	Elf_Data *reldata, *syms, *symstrs;
	Elf_Scn *scn_plt_rel, *scn_symstrs;
	char sympltname[1024];
	int nr = 0, symidx;

	scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
					  ".rela.plt", NULL);
	if (scn_plt_rel == NULL) {
		scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
						  ".rel.plt", NULL);
		if (scn_plt_rel == NULL)
			return 0;
	}

	if (shdr_rel_plt.sh_link != dynsym_idx)
		return 0;

	if (elf_section_by_name(elf, ehdr, &shdr_plt, ".plt", NULL) == NULL)
		return 0;

	/*
	 * Fetch the relocation section to find the indexes to the GOT
	 * and the symbols in the .dynsym they refer to.
	 */
	reldata = elf_getdata(scn_plt_rel, NULL);
	if (reldata == NULL)
		return -1;

	syms = elf_getdata(scn_dynsym, NULL);
	if (syms == NULL)
		return -1;

	scn_symstrs = elf_getscn(elf, shdr_dynsym->sh_link);
	if (scn_symstrs == NULL)
		return -1;

	symstrs = elf_getdata(scn_symstrs, NULL);
	if (symstrs == NULL)
		return -1;

	nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
	plt_offset = shdr_plt.sh_offset;

	if (shdr_rel_plt.sh_type == SHT_RELA) {
		GElf_Rela pos_mem, *pos;

		elf_section__for_each_rela(reldata, pos, pos_mem, idx,
					   nr_rel_entries) {
			symidx = GELF_R_SYM(pos->r_info);
			plt_offset += shdr_plt.sh_entsize;
			gelf_getsym(syms, symidx, &sym);
			snprintf(sympltname, sizeof(sympltname),
				 "%s@plt", elf_sym__name(&sym, symstrs));

			f = symbol__new(plt_offset, shdr_plt.sh_entsize,
					sympltname, self->sym_priv_size, 0, verbose);
			if (!f)
				return -1;

			dso__insert_symbol(self, f);
			++nr;
		}
	} else if (shdr_rel_plt.sh_type == SHT_REL) {
		GElf_Rel pos_mem, *pos;
		elf_section__for_each_rel(reldata, pos, pos_mem, idx,
					  nr_rel_entries) {
			symidx = GELF_R_SYM(pos->r_info);
			plt_offset += shdr_plt.sh_entsize;
			gelf_getsym(syms, symidx, &sym);
			snprintf(sympltname, sizeof(sympltname),
				 "%s@plt", elf_sym__name(&sym, symstrs));

			f = symbol__new(plt_offset, shdr_plt.sh_entsize,
					sympltname, self->sym_priv_size, 0, verbose);
			if (!f)
				return -1;

			dso__insert_symbol(self, f);
			++nr;
		}
	} else {
		/*
		 * TODO: There are still one more shdr_rel_plt.sh_type
		 * I have to investigate, but probably should be ignored.
		 */
	}

	return nr;
}

static int dso__load_sym(struct dso *self, int fd, const char *name,
			 symbol_filter_t filter, int verbose)
{
	Elf_Data *symstrs;
	uint32_t nr_syms;
	int err = -1;
	uint32_t index;
	GElf_Ehdr ehdr;
	GElf_Shdr shdr;
	Elf_Data *syms;
	GElf_Sym sym;
	Elf_Scn *sec, *sec_dynsym;
	Elf *elf;
	size_t dynsym_idx;
	int nr = 0;

	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
	if (elf == NULL) {
		if (verbose)
			fprintf(stderr, "%s: cannot read %s ELF file.\n",
				__func__, name);
		goto out_close;
	}

	if (gelf_getehdr(elf, &ehdr) == NULL) {
		if (verbose)
			fprintf(stderr, "%s: cannot get elf header.\n", __func__);
		goto out_elf_end;
	}

	/*
	 * We need to check if we have a .dynsym, so that we can handle the
	 * .plt, synthesizing its symbols, that aren't on the symtabs (be it
	 * .dynsym or .symtab)
	 */
	sec_dynsym = elf_section_by_name(elf, &ehdr, &shdr,
					 ".dynsym", &dynsym_idx);
	if (sec_dynsym != NULL) {
		nr = dso__synthesize_plt_symbols(self, elf, &ehdr,
						 sec_dynsym, &shdr,
						 dynsym_idx, verbose);
		if (nr < 0)
			goto out_elf_end;
	}

	/*
	 * But if we have a full .symtab (that is a superset of .dynsym) we
	 * should add the symbols not in the .dynsyn
	 */
	sec = elf_section_by_name(elf, &ehdr, &shdr, ".symtab", NULL);
	if (sec == NULL) {
		if (sec_dynsym == NULL)
			goto out_elf_end;

		sec = sec_dynsym;
		gelf_getshdr(sec, &shdr);
	}

	syms = elf_getdata(sec, NULL);
	if (syms == NULL)
		goto out_elf_end;

	sec = elf_getscn(elf, shdr.sh_link);
	if (sec == NULL)
		goto out_elf_end;

	symstrs = elf_getdata(sec, NULL);
	if (symstrs == NULL)
		goto out_elf_end;

	nr_syms = shdr.sh_size / shdr.sh_entsize;

	memset(&sym, 0, sizeof(sym));

	elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
		struct symbol *f;
		u64 obj_start;

		if (!elf_sym__is_function(&sym))
			continue;

		sec = elf_getscn(elf, sym.st_shndx);
		if (!sec)
			goto out_elf_end;

		gelf_getshdr(sec, &shdr);
		obj_start = sym.st_value;

		sym.st_value -= shdr.sh_addr - shdr.sh_offset;

		f = symbol__new(sym.st_value, sym.st_size,
				elf_sym__name(&sym, symstrs),
				self->sym_priv_size, obj_start, verbose);
		if (!f)
			goto out_elf_end;

		if (filter && filter(self, f))
			symbol__delete(f, self->sym_priv_size);
		else {
			dso__insert_symbol(self, f);
			nr++;
		}
	}

	err = nr;
out_elf_end:
	elf_end(elf);
out_close:
	return err;
}

int dso__load(struct dso *self, symbol_filter_t filter, int verbose)
{
	int size = strlen(self->name) + sizeof("/usr/lib/debug%s.debug");
	char *name = malloc(size);
	int variant = 0;
	int ret = -1;
	int fd;

	if (!name)
		return -1;

	if (strncmp(self->name, "/tmp/perf-", 10) == 0)
		return dso__load_perf_map(self, filter, verbose);

more:
	do {
		switch (variant) {
		case 0: /* Fedora */
			snprintf(name, size, "/usr/lib/debug%s.debug", self->name);
			break;
		case 1: /* Ubuntu */
			snprintf(name, size, "/usr/lib/debug%s", self->name);
			break;
		case 2: /* Sane people */
			snprintf(name, size, "%s", self->name);
			break;

		default:
			goto out;
		}
		variant++;

		fd = open(name, O_RDONLY);
	} while (fd < 0);

	ret = dso__load_sym(self, fd, name, filter, verbose);
	close(fd);

	/*
	 * Some people seem to have debuginfo files _WITHOUT_ debug info!?!?
	 */
	if (!ret)
		goto more;

out:
	free(name);
	return ret;
}

static int dso__load_vmlinux(struct dso *self, const char *vmlinux,
			     symbol_filter_t filter, int verbose)
{
	int err, fd = open(vmlinux, O_RDONLY);

	if (fd < 0)
		return -1;

	err = dso__load_sym(self, fd, vmlinux, filter, verbose);
	close(fd);

	return err;
}

int dso__load_kernel(struct dso *self, const char *vmlinux,
		     symbol_filter_t filter, int verbose)
{
	int err = -1;

	if (vmlinux)
		err = dso__load_vmlinux(self, vmlinux, filter, verbose);

	if (err)
		err = dso__load_kallsyms(self, filter, verbose);

	return err;
}

void symbol__init(void)
{
	elf_version(EV_CURRENT);
}