1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * probe-finder.c : C expression to kprobe event converter
4 *
5 * Written by Masami Hiramatsu <mhiramat@redhat.com>
6 */
7
8 #include <inttypes.h>
9 #include <sys/utsname.h>
10 #include <sys/types.h>
11 #include <sys/stat.h>
12 #include <fcntl.h>
13 #include <errno.h>
14 #include <stdio.h>
15 #include <unistd.h>
16 #include <stdlib.h>
17 #include <string.h>
18 #include <stdarg.h>
19 #include <dwarf-regs.h>
20
21 #include <linux/bitops.h>
22 #include <linux/zalloc.h>
23 #include "event.h"
24 #include "dso.h"
25 #include "debug.h"
26 #include "debuginfo.h"
27 #include "intlist.h"
28 #include "strbuf.h"
29 #include "strlist.h"
30 #include "symbol.h"
31 #include "probe-finder.h"
32 #include "probe-file.h"
33 #include "string2.h"
34
35 /* Kprobe tracer basic type is up to u64 */
36 #define MAX_BASIC_TYPE_BITS 64
37
is_known_C_lang(int lang)38 bool is_known_C_lang(int lang)
39 {
40 switch (lang) {
41 case DW_LANG_C89:
42 case DW_LANG_C:
43 case DW_LANG_C99:
44 case DW_LANG_C11:
45 return true;
46 default:
47 return false;
48 }
49 }
50
51 /*
52 * Probe finder related functions
53 */
54
alloc_trace_arg_ref(long offs)55 static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
56 {
57 struct probe_trace_arg_ref *ref;
58 ref = zalloc(sizeof(struct probe_trace_arg_ref));
59 if (ref != NULL)
60 ref->offset = offs;
61 return ref;
62 }
63
64 /*
65 * Convert a location into trace_arg.
66 * If tvar == NULL, this just checks variable can be converted.
67 * If fentry == true and vr_die is a parameter, do heuristic search
68 * for the location fuzzed by function entry mcount.
69 */
convert_variable_location(Dwarf_Die * vr_die,Dwarf_Addr addr,Dwarf_Op * fb_ops,Dwarf_Die * sp_die,const struct probe_finder * pf,struct probe_trace_arg * tvar)70 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
71 Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
72 const struct probe_finder *pf,
73 struct probe_trace_arg *tvar)
74 {
75 Dwarf_Attribute attr;
76 Dwarf_Addr tmp = 0;
77 Dwarf_Op *op;
78 size_t nops;
79 unsigned int regn;
80 Dwarf_Word offs = 0;
81 bool ref = false;
82 const char *regs;
83 int ret, ret2 = 0;
84
85 if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
86 goto static_var;
87
88 /* Constant value */
89 if (dwarf_attr(vr_die, DW_AT_const_value, &attr) &&
90 immediate_value_is_supported()) {
91 Dwarf_Sword snum;
92
93 if (!tvar)
94 return 0;
95
96 dwarf_formsdata(&attr, &snum);
97 ret = asprintf(&tvar->value, "\\%ld", (long)snum);
98
99 return ret < 0 ? -ENOMEM : 0;
100 }
101
102 /* TODO: handle more than 1 exprs */
103 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
104 return -EINVAL; /* Broken DIE ? */
105 if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
106 ret = dwarf_entrypc(sp_die, &tmp);
107 if (ret)
108 return -ENOENT;
109
110 if (probe_conf.show_location_range &&
111 (dwarf_tag(vr_die) == DW_TAG_variable)) {
112 ret2 = -ERANGE;
113 } else if (addr != tmp ||
114 dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
115 return -ENOENT;
116 }
117
118 ret = dwarf_highpc(sp_die, &tmp);
119 if (ret)
120 return -ENOENT;
121 /*
122 * This is fuzzed by fentry mcount. We try to find the
123 * parameter location at the earliest address.
124 */
125 for (addr += 1; addr <= tmp; addr++) {
126 if (dwarf_getlocation_addr(&attr, addr, &op,
127 &nops, 1) > 0)
128 goto found;
129 }
130 return -ENOENT;
131 }
132 found:
133 if (nops == 0)
134 /* TODO: Support const_value */
135 return -ENOENT;
136
137 if (op->atom == DW_OP_addr) {
138 static_var:
139 if (!tvar)
140 return ret2;
141 /* Static variables on memory (not stack), make @varname */
142 ret = strlen(dwarf_diename(vr_die));
143 tvar->value = zalloc(ret + 2);
144 if (tvar->value == NULL)
145 return -ENOMEM;
146 snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
147 tvar->ref = alloc_trace_arg_ref((long)offs);
148 if (tvar->ref == NULL)
149 return -ENOMEM;
150 return ret2;
151 }
152
153 /* If this is based on frame buffer, set the offset */
154 if (op->atom == DW_OP_fbreg) {
155 if (fb_ops == NULL)
156 return -ENOTSUP;
157 ref = true;
158 offs = op->number;
159 op = &fb_ops[0];
160 }
161
162 if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
163 regn = op->atom - DW_OP_breg0;
164 offs += op->number;
165 ref = true;
166 } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
167 regn = op->atom - DW_OP_reg0;
168 } else if (op->atom == DW_OP_bregx) {
169 regn = op->number;
170 offs += op->number2;
171 ref = true;
172 } else if (op->atom == DW_OP_regx) {
173 regn = op->number;
174 } else {
175 pr_debug("DW_OP %x is not supported.\n", op->atom);
176 return -ENOTSUP;
177 }
178
179 if (!tvar)
180 return ret2;
181
182 regs = get_dwarf_regstr(regn, pf->e_machine, pf->e_flags);
183 if (!regs) {
184 /* This should be a bug in DWARF or this tool */
185 pr_warning("Mapping for the register number %u "
186 "missing on this architecture.\n", regn);
187 return -ENOTSUP;
188 }
189
190 tvar->value = strdup(regs);
191 if (tvar->value == NULL)
192 return -ENOMEM;
193
194 if (ref) {
195 tvar->ref = alloc_trace_arg_ref((long)offs);
196 if (tvar->ref == NULL)
197 return -ENOMEM;
198 }
199 return ret2;
200 }
201
convert_variable_type(Dwarf_Die * vr_die,struct probe_trace_arg * tvar,const char * cast,bool user_access)202 static int convert_variable_type(Dwarf_Die *vr_die,
203 struct probe_trace_arg *tvar,
204 const char *cast, bool user_access)
205 {
206 struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
207 Dwarf_Die type;
208 char buf[16];
209 char sbuf[STRERR_BUFSIZE];
210 int bsize, boffs, total;
211 int ret;
212 char prefix;
213
214 /* TODO: check all types */
215 if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "ustring") &&
216 strcmp(cast, "x") != 0 &&
217 strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
218 /* Non string type is OK */
219 /* and respect signedness/hexadecimal cast */
220 tvar->type = strdup(cast);
221 return (tvar->type == NULL) ? -ENOMEM : 0;
222 }
223
224 bsize = dwarf_bitsize(vr_die);
225 if (bsize > 0) {
226 /* This is a bitfield */
227 boffs = dwarf_bitoffset(vr_die);
228 total = dwarf_bytesize(vr_die);
229 if (boffs < 0 || total < 0)
230 return -ENOENT;
231 ret = snprintf(buf, 16, "b%d@%d/%d", bsize, boffs,
232 BYTES_TO_BITS(total));
233 goto formatted;
234 }
235
236 if (die_get_real_type(vr_die, &type) == NULL) {
237 pr_warning("Failed to get a type information of %s.\n",
238 dwarf_diename(vr_die));
239 return -ENOENT;
240 }
241
242 pr_debug("%s type is %s.\n",
243 dwarf_diename(vr_die), dwarf_diename(&type));
244
245 if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) {
246 /* String type */
247 ret = dwarf_tag(&type);
248 if (ret != DW_TAG_pointer_type &&
249 ret != DW_TAG_array_type) {
250 pr_warning("Failed to cast into string: "
251 "%s(%s) is not a pointer nor array.\n",
252 dwarf_diename(vr_die), dwarf_diename(&type));
253 return -EINVAL;
254 }
255 if (die_get_real_type(&type, &type) == NULL) {
256 pr_warning("Failed to get a type"
257 " information.\n");
258 return -ENOENT;
259 }
260 if (ret == DW_TAG_pointer_type) {
261 while (*ref_ptr)
262 ref_ptr = &(*ref_ptr)->next;
263 /* Add new reference with offset +0 */
264 *ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
265 if (*ref_ptr == NULL) {
266 pr_warning("Out of memory error\n");
267 return -ENOMEM;
268 }
269 (*ref_ptr)->user_access = user_access;
270 }
271 if (!die_compare_name(&type, "char") &&
272 !die_compare_name(&type, "unsigned char")) {
273 pr_warning("Failed to cast into string: "
274 "%s is not (unsigned) char *.\n",
275 dwarf_diename(vr_die));
276 return -EINVAL;
277 }
278 tvar->type = strdup(cast);
279 return (tvar->type == NULL) ? -ENOMEM : 0;
280 }
281
282 if (cast && (strcmp(cast, "u") == 0))
283 prefix = 'u';
284 else if (cast && (strcmp(cast, "s") == 0))
285 prefix = 's';
286 else if (cast && (strcmp(cast, "x") == 0) &&
287 probe_type_is_available(PROBE_TYPE_X))
288 prefix = 'x';
289 else
290 prefix = die_is_signed_type(&type) ? 's' :
291 probe_type_is_available(PROBE_TYPE_X) ? 'x' : 'u';
292
293 ret = dwarf_bytesize(&type);
294 if (ret <= 0)
295 /* No size ... try to use default type */
296 return 0;
297 ret = BYTES_TO_BITS(ret);
298
299 /* Check the bitwidth */
300 if (ret > MAX_BASIC_TYPE_BITS) {
301 pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
302 dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
303 ret = MAX_BASIC_TYPE_BITS;
304 }
305 ret = snprintf(buf, 16, "%c%d", prefix, ret);
306
307 formatted:
308 if (ret < 0 || ret >= 16) {
309 if (ret >= 16)
310 ret = -E2BIG;
311 pr_warning("Failed to convert variable type: %s\n",
312 str_error_r(-ret, sbuf, sizeof(sbuf)));
313 return ret;
314 }
315 tvar->type = strdup(buf);
316 if (tvar->type == NULL)
317 return -ENOMEM;
318 return 0;
319 }
320
convert_variable_fields(Dwarf_Die * vr_die,const char * varname,struct perf_probe_arg_field * field,struct probe_trace_arg_ref ** ref_ptr,Dwarf_Die * die_mem,bool user_access)321 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
322 struct perf_probe_arg_field *field,
323 struct probe_trace_arg_ref **ref_ptr,
324 Dwarf_Die *die_mem, bool user_access)
325 {
326 struct probe_trace_arg_ref *ref = *ref_ptr;
327 Dwarf_Die type;
328 Dwarf_Word offs;
329 int ret, tag;
330
331 pr_debug("converting %s in %s\n", field->name, varname);
332 if (die_get_real_type(vr_die, &type) == NULL) {
333 pr_warning("Failed to get the type of %s.\n", varname);
334 return -ENOENT;
335 }
336 pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type),
337 (unsigned)dwarf_dieoffset(&type));
338 tag = dwarf_tag(&type);
339
340 if (field->name[0] == '[' &&
341 (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
342 /* Save original type for next field or type */
343 memcpy(die_mem, &type, sizeof(*die_mem));
344 /* Get the type of this array */
345 if (die_get_real_type(&type, &type) == NULL) {
346 pr_warning("Failed to get the type of %s.\n", varname);
347 return -ENOENT;
348 }
349 pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type),
350 (unsigned)dwarf_dieoffset(&type));
351 if (tag == DW_TAG_pointer_type) {
352 ref = zalloc(sizeof(struct probe_trace_arg_ref));
353 if (ref == NULL)
354 return -ENOMEM;
355 if (*ref_ptr)
356 (*ref_ptr)->next = ref;
357 else
358 *ref_ptr = ref;
359 }
360 ref->offset += dwarf_bytesize(&type) * field->index;
361 ref->user_access = user_access;
362 goto next;
363 } else if (tag == DW_TAG_pointer_type) {
364 /* Check the pointer and dereference */
365 if (!field->ref) {
366 pr_err("Semantic error: %s must be referred by '->'\n",
367 field->name);
368 return -EINVAL;
369 }
370 /* Get the type pointed by this pointer */
371 if (die_get_real_type(&type, &type) == NULL) {
372 pr_warning("Failed to get the type of %s.\n", varname);
373 return -ENOENT;
374 }
375 /* Verify it is a data structure */
376 tag = dwarf_tag(&type);
377 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
378 pr_warning("%s is not a data structure nor a union.\n",
379 varname);
380 return -EINVAL;
381 }
382
383 ref = zalloc(sizeof(struct probe_trace_arg_ref));
384 if (ref == NULL)
385 return -ENOMEM;
386 if (*ref_ptr)
387 (*ref_ptr)->next = ref;
388 else
389 *ref_ptr = ref;
390 } else {
391 /* Verify it is a data structure */
392 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
393 pr_warning("%s is not a data structure nor a union.\n",
394 varname);
395 return -EINVAL;
396 }
397 if (field->name[0] == '[') {
398 pr_err("Semantic error: %s is not a pointer"
399 " nor array.\n", varname);
400 return -EINVAL;
401 }
402 /* While processing unnamed field, we don't care about this */
403 if (field->ref && dwarf_diename(vr_die)) {
404 pr_err("Semantic error: %s must be referred by '.'\n",
405 field->name);
406 return -EINVAL;
407 }
408 if (!ref) {
409 pr_warning("Structure on a register is not "
410 "supported yet.\n");
411 return -ENOTSUP;
412 }
413 }
414
415 if (die_find_member(&type, field->name, die_mem) == NULL) {
416 pr_warning("%s(type:%s) has no member %s.\n", varname,
417 dwarf_diename(&type), field->name);
418 return -EINVAL;
419 }
420
421 /* Get the offset of the field */
422 if (tag == DW_TAG_union_type) {
423 offs = 0;
424 } else {
425 ret = die_get_data_member_location(die_mem, &offs);
426 if (ret < 0) {
427 pr_warning("Failed to get the offset of %s.\n",
428 field->name);
429 return ret;
430 }
431 }
432 ref->offset += (long)offs;
433 ref->user_access = user_access;
434
435 /* If this member is unnamed, we need to reuse this field */
436 if (!dwarf_diename(die_mem))
437 return convert_variable_fields(die_mem, varname, field,
438 &ref, die_mem, user_access);
439
440 next:
441 /* Converting next field */
442 if (field->next)
443 return convert_variable_fields(die_mem, field->name,
444 field->next, &ref, die_mem, user_access);
445 else
446 return 0;
447 }
448
print_var_not_found(const char * varname)449 static void print_var_not_found(const char *varname)
450 {
451 pr_err("Failed to find the location of the '%s' variable at this address.\n"
452 " Perhaps it has been optimized out.\n"
453 " Use -V with the --range option to show '%s' location range.\n",
454 varname, varname);
455 }
456
457 /* Show a variables in kprobe event format */
convert_variable(Dwarf_Die * vr_die,struct probe_finder * pf)458 static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
459 {
460 Dwarf_Die die_mem;
461 int ret;
462
463 pr_debug("Converting variable %s into trace event.\n",
464 dwarf_diename(vr_die));
465
466 ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
467 &pf->sp_die, pf, pf->tvar);
468 if (ret == -ENOENT && pf->skip_empty_arg)
469 /* This can be found in other place. skip it */
470 return 0;
471 if (ret == -ENOENT || ret == -EINVAL) {
472 print_var_not_found(pf->pvar->var);
473 } else if (ret == -ENOTSUP)
474 pr_err("Sorry, we don't support this variable location yet.\n");
475 else if (ret == 0 && pf->pvar->field) {
476 ret = convert_variable_fields(vr_die, pf->pvar->var,
477 pf->pvar->field, &pf->tvar->ref,
478 &die_mem, pf->pvar->user_access);
479 vr_die = &die_mem;
480 }
481 if (ret == 0)
482 ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type,
483 pf->pvar->user_access);
484 /* *expr will be cached in libdw. Don't free it. */
485 return ret;
486 }
487
488 /* Find a variable in a scope DIE */
find_variable(Dwarf_Die * sc_die,struct probe_finder * pf)489 static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
490 {
491 Dwarf_Die vr_die;
492 char *buf, *ptr;
493 int ret = 0;
494
495 /* Copy raw parameters */
496 if (!is_c_varname(pf->pvar->var))
497 return copy_to_probe_trace_arg(pf->tvar, pf->pvar);
498
499 if (pf->pvar->name)
500 pf->tvar->name = strdup(pf->pvar->name);
501 else {
502 buf = synthesize_perf_probe_arg(pf->pvar);
503 if (!buf)
504 return -ENOMEM;
505 ptr = strchr(buf, ':'); /* Change type separator to _ */
506 if (ptr)
507 *ptr = '_';
508 pf->tvar->name = buf;
509 }
510 if (pf->tvar->name == NULL)
511 return -ENOMEM;
512
513 pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
514 /* Search child die for local variables and parameters. */
515 if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
516 /* Search again in global variables */
517 if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
518 0, &vr_die)) {
519 if (pf->skip_empty_arg)
520 return 0;
521 pr_warning("Failed to find '%s' in this function.\n",
522 pf->pvar->var);
523 ret = -ENOENT;
524 }
525 }
526 if (ret >= 0)
527 ret = convert_variable(&vr_die, pf);
528
529 return ret;
530 }
531
532 /* Convert subprogram DIE to trace point */
convert_to_trace_point(Dwarf_Die * sp_die,Dwfl_Module * mod,Dwarf_Addr paddr,bool retprobe,const char * function,struct probe_trace_point * tp)533 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
534 Dwarf_Addr paddr, bool retprobe,
535 const char *function,
536 struct probe_trace_point *tp)
537 {
538 Dwarf_Addr eaddr;
539 GElf_Sym sym;
540 const char *symbol;
541
542 /* Verify the address is correct */
543 if (!dwarf_haspc(sp_die, paddr)) {
544 pr_warning("Specified offset is out of %s\n",
545 dwarf_diename(sp_die));
546 return -EINVAL;
547 }
548
549 if (dwarf_entrypc(sp_die, &eaddr) == 0) {
550 /* If the DIE has entrypc, use it. */
551 symbol = dwarf_diename(sp_die);
552 } else {
553 /* Try to get actual symbol name and address from symtab */
554 symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
555 eaddr = sym.st_value;
556 }
557 if (!symbol) {
558 pr_warning("Failed to find symbol at 0x%lx\n",
559 (unsigned long)paddr);
560 return -ENOENT;
561 }
562
563 tp->offset = (unsigned long)(paddr - eaddr);
564 tp->address = paddr;
565 tp->symbol = strdup(symbol);
566 if (!tp->symbol)
567 return -ENOMEM;
568
569 /* Return probe must be on the head of a subprogram */
570 if (retprobe) {
571 if (eaddr != paddr) {
572 pr_warning("Failed to find \"%s%%return\",\n"
573 " because %s is an inlined function and"
574 " has no return point.\n", function,
575 function);
576 return -EINVAL;
577 }
578 tp->retprobe = true;
579 }
580
581 return 0;
582 }
583
584 /* Call probe_finder callback with scope DIE */
call_probe_finder(Dwarf_Die * sc_die,struct probe_finder * pf)585 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
586 {
587 Dwarf_Attribute fb_attr;
588 Dwarf_Frame *frame = NULL;
589 size_t nops;
590 int ret;
591
592 if (!sc_die) {
593 pr_err("Caller must pass a scope DIE. Program error.\n");
594 return -EINVAL;
595 }
596
597 /* If not a real subprogram, find a real one */
598 if (!die_is_func_def(sc_die)) {
599 if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
600 if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
601 pr_warning("Ignoring tail call from %s\n",
602 dwarf_diename(&pf->sp_die));
603 return 0;
604 } else {
605 pr_warning("Failed to find probe point in any "
606 "functions.\n");
607 return -ENOENT;
608 }
609 }
610 } else
611 memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));
612
613 /* Get the frame base attribute/ops from subprogram */
614 dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
615 ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
616 if (ret <= 0 || nops == 0) {
617 pf->fb_ops = NULL;
618 } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
619 (pf->cfi_eh != NULL || pf->cfi_dbg != NULL)) {
620 if ((dwarf_cfi_addrframe(pf->cfi_eh, pf->addr, &frame) != 0 &&
621 (dwarf_cfi_addrframe(pf->cfi_dbg, pf->addr, &frame) != 0)) ||
622 dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
623 pr_warning("Failed to get call frame on 0x%jx\n",
624 (uintmax_t)pf->addr);
625 free(frame);
626 return -ENOENT;
627 }
628 }
629
630 /* Call finder's callback handler */
631 ret = pf->callback(sc_die, pf);
632
633 /* Since *pf->fb_ops can be a part of frame. we should free it here. */
634 free(frame);
635 pf->fb_ops = NULL;
636
637 return ret;
638 }
639
640 struct find_scope_param {
641 const char *function;
642 const char *file;
643 int line;
644 int diff;
645 Dwarf_Die *die_mem;
646 bool found;
647 };
648
find_best_scope_cb(Dwarf_Die * fn_die,void * data)649 static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
650 {
651 struct find_scope_param *fsp = data;
652 const char *file;
653 int lno;
654
655 /* Skip if declared file name does not match */
656 if (fsp->file) {
657 file = die_get_decl_file(fn_die);
658 if (!file || strcmp(fsp->file, file) != 0)
659 return 0;
660 }
661 /* If the function name is given, that's what user expects */
662 if (fsp->function) {
663 if (die_match_name(fn_die, fsp->function)) {
664 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
665 fsp->found = true;
666 return 1;
667 }
668 } else {
669 /* With the line number, find the nearest declared DIE */
670 dwarf_decl_line(fn_die, &lno);
671 if (lno < fsp->line && fsp->diff > fsp->line - lno) {
672 /* Keep a candidate and continue */
673 fsp->diff = fsp->line - lno;
674 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
675 fsp->found = true;
676 }
677 }
678 return 0;
679 }
680
681 /* Return innermost DIE */
find_inner_scope_cb(Dwarf_Die * fn_die,void * data)682 static int find_inner_scope_cb(Dwarf_Die *fn_die, void *data)
683 {
684 struct find_scope_param *fsp = data;
685
686 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
687 fsp->found = true;
688 return 1;
689 }
690
691 /* Find an appropriate scope fits to given conditions */
find_best_scope(struct probe_finder * pf,Dwarf_Die * die_mem)692 static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
693 {
694 struct find_scope_param fsp = {
695 .function = pf->pev->point.function,
696 .file = pf->fname,
697 .line = pf->lno,
698 .diff = INT_MAX,
699 .die_mem = die_mem,
700 .found = false,
701 };
702 int ret;
703
704 ret = cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb,
705 &fsp);
706 if (!ret && !fsp.found)
707 cu_walk_functions_at(&pf->cu_die, pf->addr,
708 find_inner_scope_cb, &fsp);
709
710 return fsp.found ? die_mem : NULL;
711 }
712
verify_representive_line(struct probe_finder * pf,const char * fname,int lineno,Dwarf_Addr addr)713 static int verify_representive_line(struct probe_finder *pf, const char *fname,
714 int lineno, Dwarf_Addr addr)
715 {
716 const char *__fname, *__func = NULL;
717 Dwarf_Die die_mem;
718 int __lineno;
719
720 /* Verify line number and address by reverse search */
721 if (cu_find_lineinfo(&pf->cu_die, addr, &__fname, &__lineno) < 0)
722 return 0;
723
724 pr_debug2("Reversed line: %s:%d\n", __fname, __lineno);
725 if (strcmp(fname, __fname) || lineno == __lineno)
726 return 0;
727
728 pr_warning("This line is sharing the address with other lines.\n");
729
730 if (pf->pev->point.function) {
731 /* Find best match function name and lines */
732 pf->addr = addr;
733 if (find_best_scope(pf, &die_mem)
734 && die_match_name(&die_mem, pf->pev->point.function)
735 && dwarf_decl_line(&die_mem, &lineno) == 0) {
736 __func = dwarf_diename(&die_mem);
737 __lineno -= lineno;
738 }
739 }
740 pr_warning("Please try to probe at %s:%d instead.\n",
741 __func ? : __fname, __lineno);
742
743 return -ENOENT;
744 }
745
probe_point_line_walker(const char * fname,int lineno,Dwarf_Addr addr,void * data)746 static int probe_point_line_walker(const char *fname, int lineno,
747 Dwarf_Addr addr, void *data)
748 {
749 struct probe_finder *pf = data;
750 Dwarf_Die *sc_die, die_mem;
751 int ret;
752
753 if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)
754 return 0;
755
756 if (verify_representive_line(pf, fname, lineno, addr))
757 return -ENOENT;
758
759 pf->addr = addr;
760 sc_die = find_best_scope(pf, &die_mem);
761 if (!sc_die) {
762 pr_warning("Failed to find scope of probe point.\n");
763 return -ENOENT;
764 }
765
766 ret = call_probe_finder(sc_die, pf);
767
768 /* Continue if no error, because the line will be in inline function */
769 return ret < 0 ? ret : 0;
770 }
771
772 /* Find probe point from its line number */
find_probe_point_by_line(struct probe_finder * pf)773 static int find_probe_point_by_line(struct probe_finder *pf)
774 {
775 return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);
776 }
777
778 /* Find lines which match lazy pattern */
find_lazy_match_lines(struct intlist * list,const char * fname,const char * pat)779 static int find_lazy_match_lines(struct intlist *list,
780 const char *fname, const char *pat)
781 {
782 FILE *fp;
783 char *line = NULL;
784 size_t line_len;
785 ssize_t len;
786 int count = 0, linenum = 1;
787 char sbuf[STRERR_BUFSIZE];
788
789 fp = fopen(fname, "r");
790 if (!fp) {
791 pr_warning("Failed to open %s: %s\n", fname,
792 str_error_r(errno, sbuf, sizeof(sbuf)));
793 return -errno;
794 }
795
796 while ((len = getline(&line, &line_len, fp)) > 0) {
797
798 if (line[len - 1] == '\n')
799 line[len - 1] = '\0';
800
801 if (strlazymatch(line, pat)) {
802 intlist__add(list, linenum);
803 count++;
804 }
805 linenum++;
806 }
807
808 if (ferror(fp))
809 count = -errno;
810 free(line);
811 fclose(fp);
812
813 if (count == 0)
814 pr_debug("No matched lines found in %s.\n", fname);
815 return count;
816 }
817
probe_point_lazy_walker(const char * fname,int lineno,Dwarf_Addr addr,void * data)818 static int probe_point_lazy_walker(const char *fname, int lineno,
819 Dwarf_Addr addr, void *data)
820 {
821 struct probe_finder *pf = data;
822 Dwarf_Die *sc_die, die_mem;
823 int ret;
824
825 if (!intlist__has_entry(pf->lcache, lineno) ||
826 strtailcmp(fname, pf->fname) != 0)
827 return 0;
828
829 pr_debug("Probe line found: line:%d addr:0x%llx\n",
830 lineno, (unsigned long long)addr);
831 pf->addr = addr;
832 pf->lno = lineno;
833 sc_die = find_best_scope(pf, &die_mem);
834 if (!sc_die) {
835 pr_warning("Failed to find scope of probe point.\n");
836 return -ENOENT;
837 }
838
839 ret = call_probe_finder(sc_die, pf);
840
841 /*
842 * Continue if no error, because the lazy pattern will match
843 * to other lines
844 */
845 return ret < 0 ? ret : 0;
846 }
847
848 /* Find probe points from lazy pattern */
find_probe_point_lazy(Dwarf_Die * sp_die,struct probe_finder * pf)849 static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
850 {
851 char sbuild_id[SBUILD_ID_SIZE] = "";
852 int ret = 0;
853 char *fpath;
854
855 if (intlist__empty(pf->lcache)) {
856 const char *comp_dir;
857
858 comp_dir = cu_get_comp_dir(&pf->cu_die);
859 if (pf->dbg->build_id) {
860 struct build_id bid;
861
862 build_id__init(&bid, pf->dbg->build_id, BUILD_ID_SIZE);
863 build_id__snprintf(&bid, sbuild_id, sizeof(sbuild_id));
864 }
865 ret = find_source_path(pf->fname, sbuild_id, comp_dir, &fpath);
866 if (ret < 0) {
867 pr_warning("Failed to find source file path.\n");
868 return ret;
869 }
870
871 /* Matching lazy line pattern */
872 ret = find_lazy_match_lines(pf->lcache, fpath,
873 pf->pev->point.lazy_line);
874 free(fpath);
875 if (ret <= 0)
876 return ret;
877 }
878
879 return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
880 }
881
skip_prologue(Dwarf_Die * sp_die,struct probe_finder * pf)882 static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
883 {
884 struct perf_probe_point *pp = &pf->pev->point;
885
886 /* Not uprobe? */
887 if (!pf->pev->uprobes)
888 return;
889
890 /* Compiled with optimization? */
891 if (die_is_optimized_target(&pf->cu_die))
892 return;
893
894 /* Don't know entrypc? */
895 if (!pf->addr)
896 return;
897
898 /* Only FUNC and FUNC@SRC are eligible. */
899 if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
900 pp->offset || pp->abs_address)
901 return;
902
903 /* Not interested in func parameter? */
904 if (!perf_probe_with_var(pf->pev))
905 return;
906
907 pr_info("Target program is compiled without optimization. Skipping prologue.\n"
908 "Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
909 pf->addr);
910
911 die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
912 }
913
probe_point_inline_cb(Dwarf_Die * in_die,void * data)914 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
915 {
916 struct probe_finder *pf = data;
917 struct perf_probe_point *pp = &pf->pev->point;
918 Dwarf_Addr addr;
919 int ret;
920
921 if (pp->lazy_line)
922 ret = find_probe_point_lazy(in_die, pf);
923 else {
924 /* Get probe address */
925 if (die_entrypc(in_die, &addr) != 0) {
926 pr_warning("Failed to get entry address of %s.\n",
927 dwarf_diename(in_die));
928 return -ENOENT;
929 }
930 if (addr == 0) {
931 pr_debug("%s has no valid entry address. skipped.\n",
932 dwarf_diename(in_die));
933 return -ENOENT;
934 }
935 pf->addr = addr;
936 pf->addr += pp->offset;
937 pr_debug("found inline addr: 0x%jx\n",
938 (uintmax_t)pf->addr);
939
940 ret = call_probe_finder(in_die, pf);
941 }
942
943 return ret;
944 }
945
946 /* Callback parameter with return value for libdw */
947 struct dwarf_callback_param {
948 void *data;
949 int retval;
950 };
951
952 /* Search function from function name */
probe_point_search_cb(Dwarf_Die * sp_die,void * data)953 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
954 {
955 struct dwarf_callback_param *param = data;
956 struct probe_finder *pf = param->data;
957 struct perf_probe_point *pp = &pf->pev->point;
958 const char *fname;
959
960 /* Check tag and diename */
961 if (!die_is_func_def(sp_die) ||
962 !die_match_name(sp_die, pp->function))
963 return DWARF_CB_OK;
964
965 /* Check declared file */
966 fname = die_get_decl_file(sp_die);
967 if (!fname) {
968 pr_warning("A function DIE doesn't have decl_line. Maybe broken DWARF?\n");
969 return DWARF_CB_OK;
970 }
971 if (pp->file && fname && strtailcmp(pp->file, fname))
972 return DWARF_CB_OK;
973
974 pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
975 (unsigned long)dwarf_dieoffset(sp_die));
976 pf->fname = fname;
977 pf->abstrace_dieoffset = dwarf_dieoffset(sp_die);
978 if (pp->line) { /* Function relative line */
979 dwarf_decl_line(sp_die, &pf->lno);
980 pf->lno += pp->line;
981 param->retval = find_probe_point_by_line(pf);
982 } else if (die_is_func_instance(sp_die)) {
983 /* Instances always have the entry address */
984 die_entrypc(sp_die, &pf->addr);
985 /* But in some case the entry address is 0 */
986 if (pf->addr == 0) {
987 pr_debug("%s has no entry PC. Skipped\n",
988 dwarf_diename(sp_die));
989 param->retval = 0;
990 /* Real function */
991 } else if (pp->lazy_line)
992 param->retval = find_probe_point_lazy(sp_die, pf);
993 else {
994 skip_prologue(sp_die, pf);
995 pf->addr += pp->offset;
996 /* TODO: Check the address in this function */
997 param->retval = call_probe_finder(sp_die, pf);
998 }
999 } else if (!probe_conf.no_inlines) {
1000 /* Inlined function: search instances */
1001 param->retval = die_walk_instances(sp_die,
1002 probe_point_inline_cb, (void *)pf);
1003 /* This could be a non-existed inline definition */
1004 if (param->retval == -ENOENT)
1005 param->retval = 0;
1006 }
1007
1008 /* We need to find other candidates */
1009 if (strisglob(pp->function) && param->retval >= 0) {
1010 param->retval = 0; /* We have to clear the result */
1011 return DWARF_CB_OK;
1012 }
1013
1014 return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
1015 }
1016
find_probe_point_by_func(struct probe_finder * pf)1017 static int find_probe_point_by_func(struct probe_finder *pf)
1018 {
1019 struct dwarf_callback_param _param = {.data = (void *)pf,
1020 .retval = 0};
1021 dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
1022 return _param.retval;
1023 }
1024
1025 struct pubname_callback_param {
1026 char *function;
1027 char *file;
1028 Dwarf_Die *cu_die;
1029 Dwarf_Die *sp_die;
1030 int found;
1031 };
1032
pubname_search_cb(Dwarf * dbg,Dwarf_Global * gl,void * data)1033 static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
1034 {
1035 struct pubname_callback_param *param = data;
1036 const char *fname;
1037
1038 if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
1039 if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
1040 return DWARF_CB_OK;
1041
1042 if (die_match_name(param->sp_die, param->function)) {
1043 if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
1044 return DWARF_CB_OK;
1045
1046 if (param->file) {
1047 fname = die_get_decl_file(param->sp_die);
1048 if (!fname || strtailcmp(param->file, fname))
1049 return DWARF_CB_OK;
1050 }
1051
1052 param->found = 1;
1053 return DWARF_CB_ABORT;
1054 }
1055 }
1056
1057 return DWARF_CB_OK;
1058 }
1059
debuginfo__find_probe_location(struct debuginfo * dbg,struct probe_finder * pf)1060 static int debuginfo__find_probe_location(struct debuginfo *dbg,
1061 struct probe_finder *pf)
1062 {
1063 struct perf_probe_point *pp = &pf->pev->point;
1064 Dwarf_Off off, noff;
1065 size_t cuhl;
1066 Dwarf_Die *diep;
1067 int ret = 0;
1068
1069 off = 0;
1070 pf->lcache = intlist__new(NULL);
1071 if (!pf->lcache)
1072 return -ENOMEM;
1073
1074 /* Fastpath: lookup by function name from .debug_pubnames section */
1075 if (pp->function && !strisglob(pp->function)) {
1076 struct pubname_callback_param pubname_param = {
1077 .function = pp->function,
1078 .file = pp->file,
1079 .cu_die = &pf->cu_die,
1080 .sp_die = &pf->sp_die,
1081 .found = 0,
1082 };
1083 struct dwarf_callback_param probe_param = {
1084 .data = pf,
1085 };
1086
1087 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1088 &pubname_param, 0);
1089 if (pubname_param.found) {
1090 ret = probe_point_search_cb(&pf->sp_die, &probe_param);
1091 if (ret)
1092 goto found;
1093 }
1094 }
1095
1096 /* Loop on CUs (Compilation Unit) */
1097 while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
1098 /* Get the DIE(Debugging Information Entry) of this CU */
1099 diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
1100 if (!diep) {
1101 off = noff;
1102 continue;
1103 }
1104
1105 /* Check if target file is included. */
1106 if (pp->file)
1107 pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
1108 else
1109 pf->fname = NULL;
1110
1111 if (!pp->file || pf->fname) {
1112 if (pp->function)
1113 ret = find_probe_point_by_func(pf);
1114 else if (pp->lazy_line)
1115 ret = find_probe_point_lazy(&pf->cu_die, pf);
1116 else {
1117 pf->lno = pp->line;
1118 ret = find_probe_point_by_line(pf);
1119 }
1120 if (ret < 0)
1121 break;
1122 }
1123 off = noff;
1124 }
1125
1126 found:
1127 intlist__delete(pf->lcache);
1128 pf->lcache = NULL;
1129
1130 return ret;
1131 }
1132
1133 /* Find probe points from debuginfo */
debuginfo__find_probes(struct debuginfo * dbg,struct probe_finder * pf)1134 static int debuginfo__find_probes(struct debuginfo *dbg,
1135 struct probe_finder *pf)
1136 {
1137 int ret = 0;
1138 Elf *elf;
1139 GElf_Ehdr ehdr;
1140
1141 if (pf->cfi_eh || pf->cfi_dbg)
1142 return debuginfo__find_probe_location(dbg, pf);
1143
1144 /* Get the call frame information from this dwarf */
1145 elf = dwarf_getelf(dbg->dbg);
1146 if (elf == NULL)
1147 return -EINVAL;
1148
1149 if (gelf_getehdr(elf, &ehdr) == NULL)
1150 return -EINVAL;
1151
1152 pf->e_machine = ehdr.e_machine;
1153 pf->e_flags = ehdr.e_flags;
1154
1155 do {
1156 GElf_Shdr shdr;
1157
1158 if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
1159 shdr.sh_type == SHT_PROGBITS)
1160 pf->cfi_eh = dwarf_getcfi_elf(elf);
1161
1162 pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
1163 } while (0);
1164
1165 ret = debuginfo__find_probe_location(dbg, pf);
1166 return ret;
1167 }
1168
1169 struct local_vars_finder {
1170 struct probe_finder *pf;
1171 struct perf_probe_arg *args;
1172 bool vars;
1173 int max_args;
1174 int nargs;
1175 int ret;
1176 };
1177
1178 /* Collect available variables in this scope */
copy_variables_cb(Dwarf_Die * die_mem,void * data)1179 static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
1180 {
1181 struct local_vars_finder *vf = data;
1182 struct probe_finder *pf = vf->pf;
1183 int tag;
1184 Dwarf_Attribute attr;
1185 Dwarf_Die var_die;
1186
1187 tag = dwarf_tag(die_mem);
1188 if (tag == DW_TAG_formal_parameter ||
1189 (tag == DW_TAG_variable && vf->vars)) {
1190 if (convert_variable_location(die_mem, vf->pf->addr,
1191 vf->pf->fb_ops, &pf->sp_die,
1192 pf, /*tvar=*/NULL) == 0) {
1193 vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
1194 if (vf->args[vf->nargs].var == NULL) {
1195 vf->ret = -ENOMEM;
1196 return DIE_FIND_CB_END;
1197 }
1198 pr_debug(" %s", vf->args[vf->nargs].var);
1199 vf->nargs++;
1200 }
1201 }
1202
1203 if (dwarf_haspc(die_mem, vf->pf->addr)) {
1204 /*
1205 * when DW_AT_entry_pc contains instruction address,
1206 * also check if the DW_AT_abstract_origin of die_mem
1207 * points to correct die.
1208 */
1209 if (dwarf_attr(die_mem, DW_AT_abstract_origin, &attr)) {
1210 dwarf_formref_die(&attr, &var_die);
1211 if (pf->abstrace_dieoffset != dwarf_dieoffset(&var_die))
1212 goto out;
1213 }
1214 return DIE_FIND_CB_CONTINUE;
1215 }
1216
1217 out:
1218 return DIE_FIND_CB_SIBLING;
1219 }
1220
expand_probe_args(Dwarf_Die * sc_die,struct probe_finder * pf,struct perf_probe_arg * args)1221 static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
1222 struct perf_probe_arg *args)
1223 {
1224 Dwarf_Die die_mem;
1225 int i;
1226 int n = 0;
1227 struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
1228 .max_args = MAX_PROBE_ARGS, .ret = 0};
1229
1230 for (i = 0; i < pf->pev->nargs; i++) {
1231 /* var never be NULL */
1232 if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
1233 vf.vars = true;
1234 else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
1235 /* Copy normal argument */
1236 args[n] = pf->pev->args[i];
1237 n++;
1238 continue;
1239 }
1240 pr_debug("Expanding %s into:", pf->pev->args[i].var);
1241 vf.nargs = n;
1242 /* Special local variables */
1243 die_find_child(sc_die, copy_variables_cb, (void *)&vf,
1244 &die_mem);
1245 pr_debug(" (%d)\n", vf.nargs - n);
1246 if (vf.ret < 0)
1247 return vf.ret;
1248 n = vf.nargs;
1249 }
1250 return n;
1251 }
1252
trace_event_finder_overlap(struct trace_event_finder * tf)1253 static bool trace_event_finder_overlap(struct trace_event_finder *tf)
1254 {
1255 int i;
1256
1257 for (i = 0; i < tf->ntevs; i++) {
1258 if (tf->pf.addr == tf->tevs[i].point.address)
1259 return true;
1260 }
1261 return false;
1262 }
1263
1264 /* Add a found probe point into trace event list */
add_probe_trace_event(Dwarf_Die * sc_die,struct probe_finder * pf)1265 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
1266 {
1267 struct trace_event_finder *tf =
1268 container_of(pf, struct trace_event_finder, pf);
1269 struct perf_probe_point *pp = &pf->pev->point;
1270 struct probe_trace_event *tev;
1271 struct perf_probe_arg *args = NULL;
1272 int ret, i;
1273
1274 /*
1275 * For some reason (e.g. different column assigned to same address)
1276 * This callback can be called with the address which already passed.
1277 * Ignore it first.
1278 */
1279 if (trace_event_finder_overlap(tf))
1280 return 0;
1281
1282 /* Check number of tevs */
1283 if (tf->ntevs == tf->max_tevs) {
1284 pr_warning("Too many( > %d) probe point found.\n",
1285 tf->max_tevs);
1286 return -ERANGE;
1287 }
1288 tev = &tf->tevs[tf->ntevs++];
1289
1290 /* Trace point should be converted from subprogram DIE */
1291 ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1292 pp->retprobe, pp->function, &tev->point);
1293 if (ret < 0)
1294 goto end;
1295
1296 tev->point.realname = strdup(dwarf_diename(sc_die));
1297 if (!tev->point.realname) {
1298 ret = -ENOMEM;
1299 goto end;
1300 }
1301
1302 tev->lang = dwarf_srclang(dwarf_diecu(sc_die, &pf->cu_die, NULL, NULL));
1303
1304 pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1305 tev->point.offset);
1306
1307 /* Expand special probe argument if exist */
1308 args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1309 if (args == NULL) {
1310 ret = -ENOMEM;
1311 goto end;
1312 }
1313
1314 ret = expand_probe_args(sc_die, pf, args);
1315 if (ret < 0)
1316 goto end;
1317
1318 tev->nargs = ret;
1319 tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1320 if (tev->args == NULL) {
1321 ret = -ENOMEM;
1322 goto end;
1323 }
1324
1325 /* Find each argument */
1326 for (i = 0; i < tev->nargs; i++) {
1327 pf->pvar = &args[i];
1328 pf->tvar = &tev->args[i];
1329 /* Variable should be found from scope DIE */
1330 ret = find_variable(sc_die, pf);
1331 if (ret != 0)
1332 break;
1333 }
1334
1335 end:
1336 if (ret) {
1337 clear_probe_trace_event(tev);
1338 tf->ntevs--;
1339 }
1340 free(args);
1341 return ret;
1342 }
1343
fill_empty_trace_arg(struct perf_probe_event * pev,struct probe_trace_event * tevs,int ntevs)1344 static int fill_empty_trace_arg(struct perf_probe_event *pev,
1345 struct probe_trace_event *tevs, int ntevs)
1346 {
1347 char **valp;
1348 char *type;
1349 int i, j, ret;
1350
1351 if (!ntevs)
1352 return -ENOENT;
1353
1354 for (i = 0; i < pev->nargs; i++) {
1355 type = NULL;
1356 for (j = 0; j < ntevs; j++) {
1357 if (tevs[j].args[i].value) {
1358 type = tevs[j].args[i].type;
1359 break;
1360 }
1361 }
1362 if (j == ntevs) {
1363 print_var_not_found(pev->args[i].var);
1364 return -ENOENT;
1365 }
1366 for (j = 0; j < ntevs; j++) {
1367 valp = &tevs[j].args[i].value;
1368 if (*valp)
1369 continue;
1370
1371 ret = asprintf(valp, "\\%lx", probe_conf.magic_num);
1372 if (ret < 0)
1373 return -ENOMEM;
1374 /* Note that type can be NULL */
1375 if (type) {
1376 tevs[j].args[i].type = strdup(type);
1377 if (!tevs[j].args[i].type)
1378 return -ENOMEM;
1379 }
1380 }
1381 }
1382 return 0;
1383 }
1384
1385 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
debuginfo__find_trace_events(struct debuginfo * dbg,struct perf_probe_event * pev,struct probe_trace_event ** tevs)1386 int debuginfo__find_trace_events(struct debuginfo *dbg,
1387 struct perf_probe_event *pev,
1388 struct probe_trace_event **tevs)
1389 {
1390 struct trace_event_finder tf = {
1391 .pf = {.pev = pev, .dbg = dbg, .callback = add_probe_trace_event},
1392 .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1393 int ret, i;
1394
1395 /* Allocate result tevs array */
1396 *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1397 if (*tevs == NULL)
1398 return -ENOMEM;
1399
1400 tf.tevs = *tevs;
1401 tf.ntevs = 0;
1402
1403 if (pev->nargs != 0 && immediate_value_is_supported())
1404 tf.pf.skip_empty_arg = true;
1405
1406 ret = debuginfo__find_probes(dbg, &tf.pf);
1407 if (ret >= 0 && tf.pf.skip_empty_arg)
1408 ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
1409
1410 dwarf_cfi_end(tf.pf.cfi_eh);
1411
1412 if (ret < 0 || tf.ntevs == 0) {
1413 for (i = 0; i < tf.ntevs; i++)
1414 clear_probe_trace_event(&tf.tevs[i]);
1415 zfree(tevs);
1416 return ret;
1417 }
1418
1419 return (ret < 0) ? ret : tf.ntevs;
1420 }
1421
1422 /* Collect available variables in this scope */
collect_variables_cb(Dwarf_Die * die_mem,void * data)1423 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1424 {
1425 struct available_var_finder *af = data;
1426 struct variable_list *vl;
1427 struct strbuf buf = STRBUF_INIT;
1428 int tag, ret;
1429
1430 vl = &af->vls[af->nvls - 1];
1431
1432 tag = dwarf_tag(die_mem);
1433 if (tag == DW_TAG_formal_parameter ||
1434 tag == DW_TAG_variable) {
1435 ret = convert_variable_location(die_mem, af->pf.addr,
1436 af->pf.fb_ops, &af->pf.sp_die,
1437 &af->pf, /*tvar=*/NULL);
1438 if (ret == 0 || ret == -ERANGE) {
1439 int ret2;
1440 bool externs = !af->child;
1441
1442 if (strbuf_init(&buf, 64) < 0)
1443 goto error;
1444
1445 if (probe_conf.show_location_range) {
1446 if (!externs)
1447 ret2 = strbuf_add(&buf,
1448 ret ? "[INV]\t" : "[VAL]\t", 6);
1449 else
1450 ret2 = strbuf_add(&buf, "[EXT]\t", 6);
1451 if (ret2)
1452 goto error;
1453 }
1454
1455 ret2 = die_get_varname(die_mem, &buf);
1456
1457 if (!ret2 && probe_conf.show_location_range &&
1458 !externs) {
1459 if (strbuf_addch(&buf, '\t') < 0)
1460 goto error;
1461 ret2 = die_get_var_range(&af->pf.sp_die,
1462 die_mem, &buf);
1463 }
1464
1465 pr_debug("Add new var: %s\n", buf.buf);
1466 if (ret2 == 0) {
1467 strlist__add(vl->vars,
1468 strbuf_detach(&buf, NULL));
1469 }
1470 strbuf_release(&buf);
1471 }
1472 }
1473
1474 if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1475 return DIE_FIND_CB_CONTINUE;
1476 else
1477 return DIE_FIND_CB_SIBLING;
1478 error:
1479 strbuf_release(&buf);
1480 pr_debug("Error in strbuf\n");
1481 return DIE_FIND_CB_END;
1482 }
1483
available_var_finder_overlap(struct available_var_finder * af)1484 static bool available_var_finder_overlap(struct available_var_finder *af)
1485 {
1486 int i;
1487
1488 for (i = 0; i < af->nvls; i++) {
1489 if (af->pf.addr == af->vls[i].point.address)
1490 return true;
1491 }
1492 return false;
1493
1494 }
1495
1496 /* Add a found vars into available variables list */
add_available_vars(Dwarf_Die * sc_die,struct probe_finder * pf)1497 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1498 {
1499 struct available_var_finder *af =
1500 container_of(pf, struct available_var_finder, pf);
1501 struct perf_probe_point *pp = &pf->pev->point;
1502 struct variable_list *vl;
1503 Dwarf_Die die_mem;
1504 int ret;
1505
1506 /*
1507 * For some reason (e.g. different column assigned to same address),
1508 * this callback can be called with the address which already passed.
1509 * Ignore it first.
1510 */
1511 if (available_var_finder_overlap(af))
1512 return 0;
1513
1514 /* Check number of tevs */
1515 if (af->nvls == af->max_vls) {
1516 pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1517 return -ERANGE;
1518 }
1519 vl = &af->vls[af->nvls++];
1520
1521 /* Trace point should be converted from subprogram DIE */
1522 ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1523 pp->retprobe, pp->function, &vl->point);
1524 if (ret < 0)
1525 return ret;
1526
1527 pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1528 vl->point.offset);
1529
1530 /* Find local variables */
1531 vl->vars = strlist__new(NULL, NULL);
1532 if (vl->vars == NULL)
1533 return -ENOMEM;
1534 af->child = true;
1535 die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1536
1537 /* Find external variables */
1538 if (!probe_conf.show_ext_vars)
1539 goto out;
1540 /* Don't need to search child DIE for external vars. */
1541 af->child = false;
1542 die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1543
1544 out:
1545 if (strlist__empty(vl->vars)) {
1546 strlist__delete(vl->vars);
1547 vl->vars = NULL;
1548 }
1549
1550 return ret;
1551 }
1552
1553 /*
1554 * Find available variables at given probe point
1555 * Return the number of found probe points. Return 0 if there is no
1556 * matched probe point. Return <0 if an error occurs.
1557 */
debuginfo__find_available_vars_at(struct debuginfo * dbg,struct perf_probe_event * pev,struct variable_list ** vls)1558 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1559 struct perf_probe_event *pev,
1560 struct variable_list **vls)
1561 {
1562 struct available_var_finder af = {
1563 .pf = {.pev = pev, .dbg = dbg, .callback = add_available_vars},
1564 .mod = dbg->mod,
1565 .max_vls = probe_conf.max_probes};
1566 int ret;
1567
1568 /* Allocate result vls array */
1569 *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1570 if (*vls == NULL)
1571 return -ENOMEM;
1572
1573 af.vls = *vls;
1574 af.nvls = 0;
1575
1576 ret = debuginfo__find_probes(dbg, &af.pf);
1577 if (ret < 0) {
1578 /* Free vlist for error */
1579 while (af.nvls--) {
1580 zfree(&af.vls[af.nvls].point.symbol);
1581 strlist__delete(af.vls[af.nvls].vars);
1582 }
1583 zfree(vls);
1584 return ret;
1585 }
1586
1587 return (ret < 0) ? ret : af.nvls;
1588 }
1589
1590 /* Reverse search */
debuginfo__find_probe_point(struct debuginfo * dbg,u64 addr,struct perf_probe_point * ppt)1591 int debuginfo__find_probe_point(struct debuginfo *dbg, u64 addr,
1592 struct perf_probe_point *ppt)
1593 {
1594 Dwarf_Die cudie, spdie, indie;
1595 Dwarf_Addr _addr = 0, baseaddr = 0;
1596 const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1597 int baseline = 0, lineno = 0, ret = 0;
1598
1599 /* We always need to relocate the address for aranges */
1600 if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
1601 addr += baseaddr;
1602 /* Find cu die */
1603 if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1604 pr_warning("Failed to find debug information for address %#" PRIx64 "\n",
1605 addr);
1606 ret = -EINVAL;
1607 goto end;
1608 }
1609
1610 /* Find a corresponding line (filename and lineno) */
1611 cu_find_lineinfo(&cudie, (Dwarf_Addr)addr, &fname, &lineno);
1612 /* Don't care whether it failed or not */
1613
1614 /* Find a corresponding function (name, baseline and baseaddr) */
1615 if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1616 /*
1617 * Get function entry information.
1618 *
1619 * As described in the document DWARF Debugging Information
1620 * Format Version 5, section 2.22 Linkage Names, "mangled names,
1621 * are used in various ways, ... to distinguish multiple
1622 * entities that have the same name".
1623 *
1624 * Firstly try to get distinct linkage name, if fail then
1625 * rollback to get associated name in DIE.
1626 */
1627 func = basefunc = die_get_linkage_name(&spdie);
1628 if (!func)
1629 func = basefunc = dwarf_diename(&spdie);
1630
1631 if (!func ||
1632 die_entrypc(&spdie, &baseaddr) != 0 ||
1633 dwarf_decl_line(&spdie, &baseline) != 0) {
1634 lineno = 0;
1635 goto post;
1636 }
1637
1638 fname = die_get_decl_file(&spdie);
1639 if (addr == baseaddr) {
1640 /* Function entry - Relative line number is 0 */
1641 lineno = baseline;
1642 goto post;
1643 }
1644
1645 /* Track down the inline functions step by step */
1646 while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1647 &indie)) {
1648 /* There is an inline function */
1649 if (die_entrypc(&indie, &_addr) == 0 &&
1650 _addr == addr) {
1651 /*
1652 * addr is at an inline function entry.
1653 * In this case, lineno should be the call-site
1654 * line number. (overwrite lineinfo)
1655 */
1656 lineno = die_get_call_lineno(&indie);
1657 fname = die_get_call_file(&indie);
1658 break;
1659 } else {
1660 /*
1661 * addr is in an inline function body.
1662 * Since lineno points one of the lines
1663 * of the inline function, baseline should
1664 * be the entry line of the inline function.
1665 */
1666 tmp = dwarf_diename(&indie);
1667 if (!tmp ||
1668 dwarf_decl_line(&indie, &baseline) != 0)
1669 break;
1670 func = tmp;
1671 spdie = indie;
1672 }
1673 }
1674 /* Verify the lineno and baseline are in a same file */
1675 tmp = die_get_decl_file(&spdie);
1676 if (!tmp || (fname && strcmp(tmp, fname) != 0))
1677 lineno = 0;
1678 }
1679
1680 post:
1681 /* Make a relative line number or an offset */
1682 if (lineno)
1683 ppt->line = lineno - baseline;
1684 else if (basefunc) {
1685 ppt->offset = addr - baseaddr;
1686 func = basefunc;
1687 }
1688
1689 /* Duplicate strings */
1690 if (func) {
1691 ppt->function = strdup(func);
1692 if (ppt->function == NULL) {
1693 ret = -ENOMEM;
1694 goto end;
1695 }
1696 }
1697 if (fname) {
1698 ppt->file = strdup(fname);
1699 if (ppt->file == NULL) {
1700 zfree(&ppt->function);
1701 ret = -ENOMEM;
1702 goto end;
1703 }
1704 }
1705 end:
1706 if (ret == 0 && (fname || func))
1707 ret = 1; /* Found a point */
1708 return ret;
1709 }
1710
1711 /* Add a line and store the src path */
line_range_add_line(const char * src,unsigned int lineno,struct line_range * lr)1712 static int line_range_add_line(const char *src, unsigned int lineno,
1713 struct line_range *lr)
1714 {
1715 /* Copy source path */
1716 if (!lr->path) {
1717 lr->path = strdup(src);
1718 if (lr->path == NULL)
1719 return -ENOMEM;
1720 }
1721 return intlist__add(lr->line_list, lineno);
1722 }
1723
line_range_walk_cb(const char * fname,int lineno,Dwarf_Addr addr,void * data)1724 static int line_range_walk_cb(const char *fname, int lineno,
1725 Dwarf_Addr addr, void *data)
1726 {
1727 struct line_finder *lf = data;
1728 const char *__fname;
1729 int __lineno;
1730 int err;
1731
1732 if ((strtailcmp(fname, lf->fname) != 0) ||
1733 (lf->lno_s > lineno || lf->lno_e < lineno))
1734 return 0;
1735
1736 /* Make sure this line can be reversible */
1737 if (cu_find_lineinfo(&lf->cu_die, addr, &__fname, &__lineno) > 0
1738 && (lineno != __lineno || strcmp(fname, __fname)))
1739 return 0;
1740
1741 err = line_range_add_line(fname, lineno, lf->lr);
1742 if (err < 0 && err != -EEXIST)
1743 return err;
1744
1745 return 0;
1746 }
1747
1748 /* Find line range from its line number */
find_line_range_by_line(Dwarf_Die * sp_die,struct line_finder * lf)1749 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1750 {
1751 int ret;
1752
1753 ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1754
1755 /* Update status */
1756 if (ret >= 0)
1757 if (!intlist__empty(lf->lr->line_list))
1758 ret = lf->found = 1;
1759 else
1760 ret = 0; /* Lines are not found */
1761 else {
1762 zfree(&lf->lr->path);
1763 }
1764 return ret;
1765 }
1766
line_range_inline_cb(Dwarf_Die * in_die,void * data)1767 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1768 {
1769 int ret = find_line_range_by_line(in_die, data);
1770
1771 /*
1772 * We have to check all instances of inlined function, because
1773 * some execution paths can be optimized out depends on the
1774 * function argument of instances. However, if an error occurs,
1775 * it should be handled by the caller.
1776 */
1777 return ret < 0 ? ret : 0;
1778 }
1779
1780 /* Search function definition from function name */
line_range_search_cb(Dwarf_Die * sp_die,void * data)1781 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1782 {
1783 struct dwarf_callback_param *param = data;
1784 struct line_finder *lf = param->data;
1785 struct line_range *lr = lf->lr;
1786 const char *fname;
1787
1788 /* Check declared file */
1789 if (lr->file) {
1790 fname = die_get_decl_file(sp_die);
1791 if (!fname || strtailcmp(lr->file, fname))
1792 return DWARF_CB_OK;
1793 }
1794
1795 if (die_match_name(sp_die, lr->function) && die_is_func_def(sp_die)) {
1796 lf->fname = die_get_decl_file(sp_die);
1797 dwarf_decl_line(sp_die, &lr->offset);
1798 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1799 lf->lno_s = lr->offset + lr->start;
1800 if (lf->lno_s < 0) /* Overflow */
1801 lf->lno_s = INT_MAX;
1802 lf->lno_e = lr->offset + lr->end;
1803 if (lf->lno_e < 0) /* Overflow */
1804 lf->lno_e = INT_MAX;
1805 pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1806 lr->start = lf->lno_s;
1807 lr->end = lf->lno_e;
1808 if (!die_is_func_instance(sp_die))
1809 param->retval = die_walk_instances(sp_die,
1810 line_range_inline_cb, lf);
1811 else
1812 param->retval = find_line_range_by_line(sp_die, lf);
1813 return DWARF_CB_ABORT;
1814 }
1815 return DWARF_CB_OK;
1816 }
1817
find_line_range_by_func(struct line_finder * lf)1818 static int find_line_range_by_func(struct line_finder *lf)
1819 {
1820 struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1821 dwarf_getfuncs(&lf->cu_die, line_range_search_cb, ¶m, 0);
1822 return param.retval;
1823 }
1824
debuginfo__find_line_range(struct debuginfo * dbg,struct line_range * lr)1825 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1826 {
1827 struct line_finder lf = {.lr = lr, .found = 0};
1828 int ret = 0;
1829 Dwarf_Off off = 0, noff;
1830 size_t cuhl;
1831 Dwarf_Die *diep;
1832 const char *comp_dir;
1833
1834 /* Fastpath: lookup by function name from .debug_pubnames section */
1835 if (lr->function) {
1836 struct pubname_callback_param pubname_param = {
1837 .function = lr->function, .file = lr->file,
1838 .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1839 struct dwarf_callback_param line_range_param = {
1840 .data = (void *)&lf, .retval = 0};
1841
1842 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1843 &pubname_param, 0);
1844 if (pubname_param.found) {
1845 line_range_search_cb(&lf.sp_die, &line_range_param);
1846 if (lf.found)
1847 goto found;
1848 }
1849 }
1850
1851 /* Loop on CUs (Compilation Unit) */
1852 while (!lf.found && ret >= 0) {
1853 if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1854 NULL, NULL, NULL) != 0)
1855 break;
1856
1857 /* Get the DIE(Debugging Information Entry) of this CU */
1858 diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1859 if (!diep) {
1860 off = noff;
1861 continue;
1862 }
1863
1864 /* Check if target file is included. */
1865 if (lr->file)
1866 lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1867 else
1868 lf.fname = 0;
1869
1870 if (!lr->file || lf.fname) {
1871 if (lr->function)
1872 ret = find_line_range_by_func(&lf);
1873 else {
1874 lf.lno_s = lr->start;
1875 lf.lno_e = lr->end;
1876 ret = find_line_range_by_line(NULL, &lf);
1877 }
1878 }
1879 off = noff;
1880 }
1881
1882 found:
1883 /* Store comp_dir */
1884 if (lf.found) {
1885 comp_dir = cu_get_comp_dir(&lf.cu_die);
1886 if (comp_dir) {
1887 lr->comp_dir = strdup(comp_dir);
1888 if (!lr->comp_dir)
1889 ret = -ENOMEM;
1890 }
1891 }
1892
1893 pr_debug("path: %s\n", lr->path);
1894 return (ret < 0) ? ret : lf.found;
1895 }
1896
1897 /*
1898 * Find a src file from a DWARF tag path. Prepend optional source path prefix
1899 * and chop off leading directories that do not exist. Result is passed back as
1900 * a newly allocated path on success.
1901 * Return 0 if file was found and readable, -errno otherwise.
1902 */
find_source_path(const char * raw_path,const char * sbuild_id,const char * comp_dir,char ** new_path)1903 int find_source_path(const char *raw_path, const char *sbuild_id,
1904 const char *comp_dir, char **new_path)
1905 {
1906 const char *prefix = symbol_conf.source_prefix;
1907
1908 if (sbuild_id && !prefix) {
1909 char prefixed_raw_path[PATH_MAX];
1910
1911 path__join(prefixed_raw_path, sizeof(prefixed_raw_path), comp_dir, raw_path);
1912
1913 if (!get_source_from_debuginfod(prefixed_raw_path, sbuild_id, new_path))
1914 return 0;
1915 }
1916
1917 if (!prefix) {
1918 if (raw_path[0] != '/' && comp_dir)
1919 /* If not an absolute path, try to use comp_dir */
1920 prefix = comp_dir;
1921 else {
1922 if (access(raw_path, R_OK) == 0) {
1923 *new_path = strdup(raw_path);
1924 return *new_path ? 0 : -ENOMEM;
1925 } else
1926 return -errno;
1927 }
1928 }
1929
1930 *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
1931 if (!*new_path)
1932 return -ENOMEM;
1933
1934 for (;;) {
1935 sprintf(*new_path, "%s/%s", prefix, raw_path);
1936
1937 if (access(*new_path, R_OK) == 0)
1938 return 0;
1939
1940 if (!symbol_conf.source_prefix) {
1941 /* In case of searching comp_dir, don't retry */
1942 zfree(new_path);
1943 return -errno;
1944 }
1945
1946 switch (errno) {
1947 case ENAMETOOLONG:
1948 case ENOENT:
1949 case EROFS:
1950 case EFAULT:
1951 raw_path = strchr(++raw_path, '/');
1952 if (!raw_path) {
1953 zfree(new_path);
1954 return -ENOENT;
1955 }
1956 continue;
1957
1958 default:
1959 zfree(new_path);
1960 return -errno;
1961 }
1962 }
1963 }
1964