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 struct build_id bid;
852 char sbuild_id[SBUILD_ID_SIZE] = "";
853 int ret = 0;
854 char *fpath;
855
856 if (intlist__empty(pf->lcache)) {
857 const char *comp_dir;
858
859 comp_dir = cu_get_comp_dir(&pf->cu_die);
860 if (pf->dbg->build_id) {
861 build_id__init(&bid, pf->dbg->build_id, BUILD_ID_SIZE);
862 build_id__sprintf(&bid, sbuild_id);
863 }
864 ret = find_source_path(pf->fname, sbuild_id, comp_dir, &fpath);
865 if (ret < 0) {
866 pr_warning("Failed to find source file path.\n");
867 return ret;
868 }
869
870 /* Matching lazy line pattern */
871 ret = find_lazy_match_lines(pf->lcache, fpath,
872 pf->pev->point.lazy_line);
873 free(fpath);
874 if (ret <= 0)
875 return ret;
876 }
877
878 return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
879 }
880
skip_prologue(Dwarf_Die * sp_die,struct probe_finder * pf)881 static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
882 {
883 struct perf_probe_point *pp = &pf->pev->point;
884
885 /* Not uprobe? */
886 if (!pf->pev->uprobes)
887 return;
888
889 /* Compiled with optimization? */
890 if (die_is_optimized_target(&pf->cu_die))
891 return;
892
893 /* Don't know entrypc? */
894 if (!pf->addr)
895 return;
896
897 /* Only FUNC and FUNC@SRC are eligible. */
898 if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
899 pp->offset || pp->abs_address)
900 return;
901
902 /* Not interested in func parameter? */
903 if (!perf_probe_with_var(pf->pev))
904 return;
905
906 pr_info("Target program is compiled without optimization. Skipping prologue.\n"
907 "Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
908 pf->addr);
909
910 die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
911 }
912
probe_point_inline_cb(Dwarf_Die * in_die,void * data)913 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
914 {
915 struct probe_finder *pf = data;
916 struct perf_probe_point *pp = &pf->pev->point;
917 Dwarf_Addr addr;
918 int ret;
919
920 if (pp->lazy_line)
921 ret = find_probe_point_lazy(in_die, pf);
922 else {
923 /* Get probe address */
924 if (die_entrypc(in_die, &addr) != 0) {
925 pr_warning("Failed to get entry address of %s.\n",
926 dwarf_diename(in_die));
927 return -ENOENT;
928 }
929 if (addr == 0) {
930 pr_debug("%s has no valid entry address. skipped.\n",
931 dwarf_diename(in_die));
932 return -ENOENT;
933 }
934 pf->addr = addr;
935 pf->addr += pp->offset;
936 pr_debug("found inline addr: 0x%jx\n",
937 (uintmax_t)pf->addr);
938
939 ret = call_probe_finder(in_die, pf);
940 }
941
942 return ret;
943 }
944
945 /* Callback parameter with return value for libdw */
946 struct dwarf_callback_param {
947 void *data;
948 int retval;
949 };
950
951 /* Search function from function name */
probe_point_search_cb(Dwarf_Die * sp_die,void * data)952 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
953 {
954 struct dwarf_callback_param *param = data;
955 struct probe_finder *pf = param->data;
956 struct perf_probe_point *pp = &pf->pev->point;
957 const char *fname;
958
959 /* Check tag and diename */
960 if (!die_is_func_def(sp_die) ||
961 !die_match_name(sp_die, pp->function))
962 return DWARF_CB_OK;
963
964 /* Check declared file */
965 fname = die_get_decl_file(sp_die);
966 if (!fname) {
967 pr_warning("A function DIE doesn't have decl_line. Maybe broken DWARF?\n");
968 return DWARF_CB_OK;
969 }
970 if (pp->file && fname && strtailcmp(pp->file, fname))
971 return DWARF_CB_OK;
972
973 pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
974 (unsigned long)dwarf_dieoffset(sp_die));
975 pf->fname = fname;
976 pf->abstrace_dieoffset = dwarf_dieoffset(sp_die);
977 if (pp->line) { /* Function relative line */
978 dwarf_decl_line(sp_die, &pf->lno);
979 pf->lno += pp->line;
980 param->retval = find_probe_point_by_line(pf);
981 } else if (die_is_func_instance(sp_die)) {
982 /* Instances always have the entry address */
983 die_entrypc(sp_die, &pf->addr);
984 /* But in some case the entry address is 0 */
985 if (pf->addr == 0) {
986 pr_debug("%s has no entry PC. Skipped\n",
987 dwarf_diename(sp_die));
988 param->retval = 0;
989 /* Real function */
990 } else if (pp->lazy_line)
991 param->retval = find_probe_point_lazy(sp_die, pf);
992 else {
993 skip_prologue(sp_die, pf);
994 pf->addr += pp->offset;
995 /* TODO: Check the address in this function */
996 param->retval = call_probe_finder(sp_die, pf);
997 }
998 } else if (!probe_conf.no_inlines) {
999 /* Inlined function: search instances */
1000 param->retval = die_walk_instances(sp_die,
1001 probe_point_inline_cb, (void *)pf);
1002 /* This could be a non-existed inline definition */
1003 if (param->retval == -ENOENT)
1004 param->retval = 0;
1005 }
1006
1007 /* We need to find other candidates */
1008 if (strisglob(pp->function) && param->retval >= 0) {
1009 param->retval = 0; /* We have to clear the result */
1010 return DWARF_CB_OK;
1011 }
1012
1013 return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
1014 }
1015
find_probe_point_by_func(struct probe_finder * pf)1016 static int find_probe_point_by_func(struct probe_finder *pf)
1017 {
1018 struct dwarf_callback_param _param = {.data = (void *)pf,
1019 .retval = 0};
1020 dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
1021 return _param.retval;
1022 }
1023
1024 struct pubname_callback_param {
1025 char *function;
1026 char *file;
1027 Dwarf_Die *cu_die;
1028 Dwarf_Die *sp_die;
1029 int found;
1030 };
1031
pubname_search_cb(Dwarf * dbg,Dwarf_Global * gl,void * data)1032 static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
1033 {
1034 struct pubname_callback_param *param = data;
1035 const char *fname;
1036
1037 if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
1038 if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
1039 return DWARF_CB_OK;
1040
1041 if (die_match_name(param->sp_die, param->function)) {
1042 if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
1043 return DWARF_CB_OK;
1044
1045 if (param->file) {
1046 fname = die_get_decl_file(param->sp_die);
1047 if (!fname || strtailcmp(param->file, fname))
1048 return DWARF_CB_OK;
1049 }
1050
1051 param->found = 1;
1052 return DWARF_CB_ABORT;
1053 }
1054 }
1055
1056 return DWARF_CB_OK;
1057 }
1058
debuginfo__find_probe_location(struct debuginfo * dbg,struct probe_finder * pf)1059 static int debuginfo__find_probe_location(struct debuginfo *dbg,
1060 struct probe_finder *pf)
1061 {
1062 struct perf_probe_point *pp = &pf->pev->point;
1063 Dwarf_Off off, noff;
1064 size_t cuhl;
1065 Dwarf_Die *diep;
1066 int ret = 0;
1067
1068 off = 0;
1069 pf->lcache = intlist__new(NULL);
1070 if (!pf->lcache)
1071 return -ENOMEM;
1072
1073 /* Fastpath: lookup by function name from .debug_pubnames section */
1074 if (pp->function && !strisglob(pp->function)) {
1075 struct pubname_callback_param pubname_param = {
1076 .function = pp->function,
1077 .file = pp->file,
1078 .cu_die = &pf->cu_die,
1079 .sp_die = &pf->sp_die,
1080 .found = 0,
1081 };
1082 struct dwarf_callback_param probe_param = {
1083 .data = pf,
1084 };
1085
1086 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1087 &pubname_param, 0);
1088 if (pubname_param.found) {
1089 ret = probe_point_search_cb(&pf->sp_die, &probe_param);
1090 if (ret)
1091 goto found;
1092 }
1093 }
1094
1095 /* Loop on CUs (Compilation Unit) */
1096 while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
1097 /* Get the DIE(Debugging Information Entry) of this CU */
1098 diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
1099 if (!diep) {
1100 off = noff;
1101 continue;
1102 }
1103
1104 /* Check if target file is included. */
1105 if (pp->file)
1106 pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
1107 else
1108 pf->fname = NULL;
1109
1110 if (!pp->file || pf->fname) {
1111 if (pp->function)
1112 ret = find_probe_point_by_func(pf);
1113 else if (pp->lazy_line)
1114 ret = find_probe_point_lazy(&pf->cu_die, pf);
1115 else {
1116 pf->lno = pp->line;
1117 ret = find_probe_point_by_line(pf);
1118 }
1119 if (ret < 0)
1120 break;
1121 }
1122 off = noff;
1123 }
1124
1125 found:
1126 intlist__delete(pf->lcache);
1127 pf->lcache = NULL;
1128
1129 return ret;
1130 }
1131
1132 /* Find probe points from debuginfo */
debuginfo__find_probes(struct debuginfo * dbg,struct probe_finder * pf)1133 static int debuginfo__find_probes(struct debuginfo *dbg,
1134 struct probe_finder *pf)
1135 {
1136 int ret = 0;
1137 Elf *elf;
1138 GElf_Ehdr ehdr;
1139
1140 if (pf->cfi_eh || pf->cfi_dbg)
1141 return debuginfo__find_probe_location(dbg, pf);
1142
1143 /* Get the call frame information from this dwarf */
1144 elf = dwarf_getelf(dbg->dbg);
1145 if (elf == NULL)
1146 return -EINVAL;
1147
1148 if (gelf_getehdr(elf, &ehdr) == NULL)
1149 return -EINVAL;
1150
1151 pf->e_machine = ehdr.e_machine;
1152 pf->e_flags = ehdr.e_flags;
1153
1154 do {
1155 GElf_Shdr shdr;
1156
1157 if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
1158 shdr.sh_type == SHT_PROGBITS)
1159 pf->cfi_eh = dwarf_getcfi_elf(elf);
1160
1161 pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
1162 } while (0);
1163
1164 ret = debuginfo__find_probe_location(dbg, pf);
1165 return ret;
1166 }
1167
1168 struct local_vars_finder {
1169 struct probe_finder *pf;
1170 struct perf_probe_arg *args;
1171 bool vars;
1172 int max_args;
1173 int nargs;
1174 int ret;
1175 };
1176
1177 /* Collect available variables in this scope */
copy_variables_cb(Dwarf_Die * die_mem,void * data)1178 static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
1179 {
1180 struct local_vars_finder *vf = data;
1181 struct probe_finder *pf = vf->pf;
1182 int tag;
1183 Dwarf_Attribute attr;
1184 Dwarf_Die var_die;
1185
1186 tag = dwarf_tag(die_mem);
1187 if (tag == DW_TAG_formal_parameter ||
1188 (tag == DW_TAG_variable && vf->vars)) {
1189 if (convert_variable_location(die_mem, vf->pf->addr,
1190 vf->pf->fb_ops, &pf->sp_die,
1191 pf, /*tvar=*/NULL) == 0) {
1192 vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
1193 if (vf->args[vf->nargs].var == NULL) {
1194 vf->ret = -ENOMEM;
1195 return DIE_FIND_CB_END;
1196 }
1197 pr_debug(" %s", vf->args[vf->nargs].var);
1198 vf->nargs++;
1199 }
1200 }
1201
1202 if (dwarf_haspc(die_mem, vf->pf->addr)) {
1203 /*
1204 * when DW_AT_entry_pc contains instruction address,
1205 * also check if the DW_AT_abstract_origin of die_mem
1206 * points to correct die.
1207 */
1208 if (dwarf_attr(die_mem, DW_AT_abstract_origin, &attr)) {
1209 dwarf_formref_die(&attr, &var_die);
1210 if (pf->abstrace_dieoffset != dwarf_dieoffset(&var_die))
1211 goto out;
1212 }
1213 return DIE_FIND_CB_CONTINUE;
1214 }
1215
1216 out:
1217 return DIE_FIND_CB_SIBLING;
1218 }
1219
expand_probe_args(Dwarf_Die * sc_die,struct probe_finder * pf,struct perf_probe_arg * args)1220 static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
1221 struct perf_probe_arg *args)
1222 {
1223 Dwarf_Die die_mem;
1224 int i;
1225 int n = 0;
1226 struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
1227 .max_args = MAX_PROBE_ARGS, .ret = 0};
1228
1229 for (i = 0; i < pf->pev->nargs; i++) {
1230 /* var never be NULL */
1231 if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
1232 vf.vars = true;
1233 else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
1234 /* Copy normal argument */
1235 args[n] = pf->pev->args[i];
1236 n++;
1237 continue;
1238 }
1239 pr_debug("Expanding %s into:", pf->pev->args[i].var);
1240 vf.nargs = n;
1241 /* Special local variables */
1242 die_find_child(sc_die, copy_variables_cb, (void *)&vf,
1243 &die_mem);
1244 pr_debug(" (%d)\n", vf.nargs - n);
1245 if (vf.ret < 0)
1246 return vf.ret;
1247 n = vf.nargs;
1248 }
1249 return n;
1250 }
1251
trace_event_finder_overlap(struct trace_event_finder * tf)1252 static bool trace_event_finder_overlap(struct trace_event_finder *tf)
1253 {
1254 int i;
1255
1256 for (i = 0; i < tf->ntevs; i++) {
1257 if (tf->pf.addr == tf->tevs[i].point.address)
1258 return true;
1259 }
1260 return false;
1261 }
1262
1263 /* Add a found probe point into trace event list */
add_probe_trace_event(Dwarf_Die * sc_die,struct probe_finder * pf)1264 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
1265 {
1266 struct trace_event_finder *tf =
1267 container_of(pf, struct trace_event_finder, pf);
1268 struct perf_probe_point *pp = &pf->pev->point;
1269 struct probe_trace_event *tev;
1270 struct perf_probe_arg *args = NULL;
1271 int ret, i;
1272
1273 /*
1274 * For some reason (e.g. different column assigned to same address)
1275 * This callback can be called with the address which already passed.
1276 * Ignore it first.
1277 */
1278 if (trace_event_finder_overlap(tf))
1279 return 0;
1280
1281 /* Check number of tevs */
1282 if (tf->ntevs == tf->max_tevs) {
1283 pr_warning("Too many( > %d) probe point found.\n",
1284 tf->max_tevs);
1285 return -ERANGE;
1286 }
1287 tev = &tf->tevs[tf->ntevs++];
1288
1289 /* Trace point should be converted from subprogram DIE */
1290 ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1291 pp->retprobe, pp->function, &tev->point);
1292 if (ret < 0)
1293 goto end;
1294
1295 tev->point.realname = strdup(dwarf_diename(sc_die));
1296 if (!tev->point.realname) {
1297 ret = -ENOMEM;
1298 goto end;
1299 }
1300
1301 tev->lang = dwarf_srclang(dwarf_diecu(sc_die, &pf->cu_die, NULL, NULL));
1302
1303 pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1304 tev->point.offset);
1305
1306 /* Expand special probe argument if exist */
1307 args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1308 if (args == NULL) {
1309 ret = -ENOMEM;
1310 goto end;
1311 }
1312
1313 ret = expand_probe_args(sc_die, pf, args);
1314 if (ret < 0)
1315 goto end;
1316
1317 tev->nargs = ret;
1318 tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1319 if (tev->args == NULL) {
1320 ret = -ENOMEM;
1321 goto end;
1322 }
1323
1324 /* Find each argument */
1325 for (i = 0; i < tev->nargs; i++) {
1326 pf->pvar = &args[i];
1327 pf->tvar = &tev->args[i];
1328 /* Variable should be found from scope DIE */
1329 ret = find_variable(sc_die, pf);
1330 if (ret != 0)
1331 break;
1332 }
1333
1334 end:
1335 if (ret) {
1336 clear_probe_trace_event(tev);
1337 tf->ntevs--;
1338 }
1339 free(args);
1340 return ret;
1341 }
1342
fill_empty_trace_arg(struct perf_probe_event * pev,struct probe_trace_event * tevs,int ntevs)1343 static int fill_empty_trace_arg(struct perf_probe_event *pev,
1344 struct probe_trace_event *tevs, int ntevs)
1345 {
1346 char **valp;
1347 char *type;
1348 int i, j, ret;
1349
1350 if (!ntevs)
1351 return -ENOENT;
1352
1353 for (i = 0; i < pev->nargs; i++) {
1354 type = NULL;
1355 for (j = 0; j < ntevs; j++) {
1356 if (tevs[j].args[i].value) {
1357 type = tevs[j].args[i].type;
1358 break;
1359 }
1360 }
1361 if (j == ntevs) {
1362 print_var_not_found(pev->args[i].var);
1363 return -ENOENT;
1364 }
1365 for (j = 0; j < ntevs; j++) {
1366 valp = &tevs[j].args[i].value;
1367 if (*valp)
1368 continue;
1369
1370 ret = asprintf(valp, "\\%lx", probe_conf.magic_num);
1371 if (ret < 0)
1372 return -ENOMEM;
1373 /* Note that type can be NULL */
1374 if (type) {
1375 tevs[j].args[i].type = strdup(type);
1376 if (!tevs[j].args[i].type)
1377 return -ENOMEM;
1378 }
1379 }
1380 }
1381 return 0;
1382 }
1383
1384 /* 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)1385 int debuginfo__find_trace_events(struct debuginfo *dbg,
1386 struct perf_probe_event *pev,
1387 struct probe_trace_event **tevs)
1388 {
1389 struct trace_event_finder tf = {
1390 .pf = {.pev = pev, .dbg = dbg, .callback = add_probe_trace_event},
1391 .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1392 int ret, i;
1393
1394 /* Allocate result tevs array */
1395 *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1396 if (*tevs == NULL)
1397 return -ENOMEM;
1398
1399 tf.tevs = *tevs;
1400 tf.ntevs = 0;
1401
1402 if (pev->nargs != 0 && immediate_value_is_supported())
1403 tf.pf.skip_empty_arg = true;
1404
1405 ret = debuginfo__find_probes(dbg, &tf.pf);
1406 if (ret >= 0 && tf.pf.skip_empty_arg)
1407 ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
1408
1409 dwarf_cfi_end(tf.pf.cfi_eh);
1410
1411 if (ret < 0 || tf.ntevs == 0) {
1412 for (i = 0; i < tf.ntevs; i++)
1413 clear_probe_trace_event(&tf.tevs[i]);
1414 zfree(tevs);
1415 return ret;
1416 }
1417
1418 return (ret < 0) ? ret : tf.ntevs;
1419 }
1420
1421 /* Collect available variables in this scope */
collect_variables_cb(Dwarf_Die * die_mem,void * data)1422 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1423 {
1424 struct available_var_finder *af = data;
1425 struct variable_list *vl;
1426 struct strbuf buf = STRBUF_INIT;
1427 int tag, ret;
1428
1429 vl = &af->vls[af->nvls - 1];
1430
1431 tag = dwarf_tag(die_mem);
1432 if (tag == DW_TAG_formal_parameter ||
1433 tag == DW_TAG_variable) {
1434 ret = convert_variable_location(die_mem, af->pf.addr,
1435 af->pf.fb_ops, &af->pf.sp_die,
1436 &af->pf, /*tvar=*/NULL);
1437 if (ret == 0 || ret == -ERANGE) {
1438 int ret2;
1439 bool externs = !af->child;
1440
1441 if (strbuf_init(&buf, 64) < 0)
1442 goto error;
1443
1444 if (probe_conf.show_location_range) {
1445 if (!externs)
1446 ret2 = strbuf_add(&buf,
1447 ret ? "[INV]\t" : "[VAL]\t", 6);
1448 else
1449 ret2 = strbuf_add(&buf, "[EXT]\t", 6);
1450 if (ret2)
1451 goto error;
1452 }
1453
1454 ret2 = die_get_varname(die_mem, &buf);
1455
1456 if (!ret2 && probe_conf.show_location_range &&
1457 !externs) {
1458 if (strbuf_addch(&buf, '\t') < 0)
1459 goto error;
1460 ret2 = die_get_var_range(&af->pf.sp_die,
1461 die_mem, &buf);
1462 }
1463
1464 pr_debug("Add new var: %s\n", buf.buf);
1465 if (ret2 == 0) {
1466 strlist__add(vl->vars,
1467 strbuf_detach(&buf, NULL));
1468 }
1469 strbuf_release(&buf);
1470 }
1471 }
1472
1473 if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1474 return DIE_FIND_CB_CONTINUE;
1475 else
1476 return DIE_FIND_CB_SIBLING;
1477 error:
1478 strbuf_release(&buf);
1479 pr_debug("Error in strbuf\n");
1480 return DIE_FIND_CB_END;
1481 }
1482
available_var_finder_overlap(struct available_var_finder * af)1483 static bool available_var_finder_overlap(struct available_var_finder *af)
1484 {
1485 int i;
1486
1487 for (i = 0; i < af->nvls; i++) {
1488 if (af->pf.addr == af->vls[i].point.address)
1489 return true;
1490 }
1491 return false;
1492
1493 }
1494
1495 /* Add a found vars into available variables list */
add_available_vars(Dwarf_Die * sc_die,struct probe_finder * pf)1496 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1497 {
1498 struct available_var_finder *af =
1499 container_of(pf, struct available_var_finder, pf);
1500 struct perf_probe_point *pp = &pf->pev->point;
1501 struct variable_list *vl;
1502 Dwarf_Die die_mem;
1503 int ret;
1504
1505 /*
1506 * For some reason (e.g. different column assigned to same address),
1507 * this callback can be called with the address which already passed.
1508 * Ignore it first.
1509 */
1510 if (available_var_finder_overlap(af))
1511 return 0;
1512
1513 /* Check number of tevs */
1514 if (af->nvls == af->max_vls) {
1515 pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1516 return -ERANGE;
1517 }
1518 vl = &af->vls[af->nvls++];
1519
1520 /* Trace point should be converted from subprogram DIE */
1521 ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1522 pp->retprobe, pp->function, &vl->point);
1523 if (ret < 0)
1524 return ret;
1525
1526 pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1527 vl->point.offset);
1528
1529 /* Find local variables */
1530 vl->vars = strlist__new(NULL, NULL);
1531 if (vl->vars == NULL)
1532 return -ENOMEM;
1533 af->child = true;
1534 die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1535
1536 /* Find external variables */
1537 if (!probe_conf.show_ext_vars)
1538 goto out;
1539 /* Don't need to search child DIE for external vars. */
1540 af->child = false;
1541 die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1542
1543 out:
1544 if (strlist__empty(vl->vars)) {
1545 strlist__delete(vl->vars);
1546 vl->vars = NULL;
1547 }
1548
1549 return ret;
1550 }
1551
1552 /*
1553 * Find available variables at given probe point
1554 * Return the number of found probe points. Return 0 if there is no
1555 * matched probe point. Return <0 if an error occurs.
1556 */
debuginfo__find_available_vars_at(struct debuginfo * dbg,struct perf_probe_event * pev,struct variable_list ** vls)1557 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1558 struct perf_probe_event *pev,
1559 struct variable_list **vls)
1560 {
1561 struct available_var_finder af = {
1562 .pf = {.pev = pev, .dbg = dbg, .callback = add_available_vars},
1563 .mod = dbg->mod,
1564 .max_vls = probe_conf.max_probes};
1565 int ret;
1566
1567 /* Allocate result vls array */
1568 *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1569 if (*vls == NULL)
1570 return -ENOMEM;
1571
1572 af.vls = *vls;
1573 af.nvls = 0;
1574
1575 ret = debuginfo__find_probes(dbg, &af.pf);
1576 if (ret < 0) {
1577 /* Free vlist for error */
1578 while (af.nvls--) {
1579 zfree(&af.vls[af.nvls].point.symbol);
1580 strlist__delete(af.vls[af.nvls].vars);
1581 }
1582 zfree(vls);
1583 return ret;
1584 }
1585
1586 return (ret < 0) ? ret : af.nvls;
1587 }
1588
1589 /* Reverse search */
debuginfo__find_probe_point(struct debuginfo * dbg,u64 addr,struct perf_probe_point * ppt)1590 int debuginfo__find_probe_point(struct debuginfo *dbg, u64 addr,
1591 struct perf_probe_point *ppt)
1592 {
1593 Dwarf_Die cudie, spdie, indie;
1594 Dwarf_Addr _addr = 0, baseaddr = 0;
1595 const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1596 int baseline = 0, lineno = 0, ret = 0;
1597
1598 /* We always need to relocate the address for aranges */
1599 if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
1600 addr += baseaddr;
1601 /* Find cu die */
1602 if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1603 pr_warning("Failed to find debug information for address %#" PRIx64 "\n",
1604 addr);
1605 ret = -EINVAL;
1606 goto end;
1607 }
1608
1609 /* Find a corresponding line (filename and lineno) */
1610 cu_find_lineinfo(&cudie, (Dwarf_Addr)addr, &fname, &lineno);
1611 /* Don't care whether it failed or not */
1612
1613 /* Find a corresponding function (name, baseline and baseaddr) */
1614 if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1615 /*
1616 * Get function entry information.
1617 *
1618 * As described in the document DWARF Debugging Information
1619 * Format Version 5, section 2.22 Linkage Names, "mangled names,
1620 * are used in various ways, ... to distinguish multiple
1621 * entities that have the same name".
1622 *
1623 * Firstly try to get distinct linkage name, if fail then
1624 * rollback to get associated name in DIE.
1625 */
1626 func = basefunc = die_get_linkage_name(&spdie);
1627 if (!func)
1628 func = basefunc = dwarf_diename(&spdie);
1629
1630 if (!func ||
1631 die_entrypc(&spdie, &baseaddr) != 0 ||
1632 dwarf_decl_line(&spdie, &baseline) != 0) {
1633 lineno = 0;
1634 goto post;
1635 }
1636
1637 fname = die_get_decl_file(&spdie);
1638 if (addr == baseaddr) {
1639 /* Function entry - Relative line number is 0 */
1640 lineno = baseline;
1641 goto post;
1642 }
1643
1644 /* Track down the inline functions step by step */
1645 while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1646 &indie)) {
1647 /* There is an inline function */
1648 if (die_entrypc(&indie, &_addr) == 0 &&
1649 _addr == addr) {
1650 /*
1651 * addr is at an inline function entry.
1652 * In this case, lineno should be the call-site
1653 * line number. (overwrite lineinfo)
1654 */
1655 lineno = die_get_call_lineno(&indie);
1656 fname = die_get_call_file(&indie);
1657 break;
1658 } else {
1659 /*
1660 * addr is in an inline function body.
1661 * Since lineno points one of the lines
1662 * of the inline function, baseline should
1663 * be the entry line of the inline function.
1664 */
1665 tmp = dwarf_diename(&indie);
1666 if (!tmp ||
1667 dwarf_decl_line(&indie, &baseline) != 0)
1668 break;
1669 func = tmp;
1670 spdie = indie;
1671 }
1672 }
1673 /* Verify the lineno and baseline are in a same file */
1674 tmp = die_get_decl_file(&spdie);
1675 if (!tmp || (fname && strcmp(tmp, fname) != 0))
1676 lineno = 0;
1677 }
1678
1679 post:
1680 /* Make a relative line number or an offset */
1681 if (lineno)
1682 ppt->line = lineno - baseline;
1683 else if (basefunc) {
1684 ppt->offset = addr - baseaddr;
1685 func = basefunc;
1686 }
1687
1688 /* Duplicate strings */
1689 if (func) {
1690 ppt->function = strdup(func);
1691 if (ppt->function == NULL) {
1692 ret = -ENOMEM;
1693 goto end;
1694 }
1695 }
1696 if (fname) {
1697 ppt->file = strdup(fname);
1698 if (ppt->file == NULL) {
1699 zfree(&ppt->function);
1700 ret = -ENOMEM;
1701 goto end;
1702 }
1703 }
1704 end:
1705 if (ret == 0 && (fname || func))
1706 ret = 1; /* Found a point */
1707 return ret;
1708 }
1709
1710 /* Add a line and store the src path */
line_range_add_line(const char * src,unsigned int lineno,struct line_range * lr)1711 static int line_range_add_line(const char *src, unsigned int lineno,
1712 struct line_range *lr)
1713 {
1714 /* Copy source path */
1715 if (!lr->path) {
1716 lr->path = strdup(src);
1717 if (lr->path == NULL)
1718 return -ENOMEM;
1719 }
1720 return intlist__add(lr->line_list, lineno);
1721 }
1722
line_range_walk_cb(const char * fname,int lineno,Dwarf_Addr addr,void * data)1723 static int line_range_walk_cb(const char *fname, int lineno,
1724 Dwarf_Addr addr, void *data)
1725 {
1726 struct line_finder *lf = data;
1727 const char *__fname;
1728 int __lineno;
1729 int err;
1730
1731 if ((strtailcmp(fname, lf->fname) != 0) ||
1732 (lf->lno_s > lineno || lf->lno_e < lineno))
1733 return 0;
1734
1735 /* Make sure this line can be reversible */
1736 if (cu_find_lineinfo(&lf->cu_die, addr, &__fname, &__lineno) > 0
1737 && (lineno != __lineno || strcmp(fname, __fname)))
1738 return 0;
1739
1740 err = line_range_add_line(fname, lineno, lf->lr);
1741 if (err < 0 && err != -EEXIST)
1742 return err;
1743
1744 return 0;
1745 }
1746
1747 /* Find line range from its line number */
find_line_range_by_line(Dwarf_Die * sp_die,struct line_finder * lf)1748 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1749 {
1750 int ret;
1751
1752 ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1753
1754 /* Update status */
1755 if (ret >= 0)
1756 if (!intlist__empty(lf->lr->line_list))
1757 ret = lf->found = 1;
1758 else
1759 ret = 0; /* Lines are not found */
1760 else {
1761 zfree(&lf->lr->path);
1762 }
1763 return ret;
1764 }
1765
line_range_inline_cb(Dwarf_Die * in_die,void * data)1766 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1767 {
1768 int ret = find_line_range_by_line(in_die, data);
1769
1770 /*
1771 * We have to check all instances of inlined function, because
1772 * some execution paths can be optimized out depends on the
1773 * function argument of instances. However, if an error occurs,
1774 * it should be handled by the caller.
1775 */
1776 return ret < 0 ? ret : 0;
1777 }
1778
1779 /* Search function definition from function name */
line_range_search_cb(Dwarf_Die * sp_die,void * data)1780 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1781 {
1782 struct dwarf_callback_param *param = data;
1783 struct line_finder *lf = param->data;
1784 struct line_range *lr = lf->lr;
1785 const char *fname;
1786
1787 /* Check declared file */
1788 if (lr->file) {
1789 fname = die_get_decl_file(sp_die);
1790 if (!fname || strtailcmp(lr->file, fname))
1791 return DWARF_CB_OK;
1792 }
1793
1794 if (die_match_name(sp_die, lr->function) && die_is_func_def(sp_die)) {
1795 lf->fname = die_get_decl_file(sp_die);
1796 dwarf_decl_line(sp_die, &lr->offset);
1797 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1798 lf->lno_s = lr->offset + lr->start;
1799 if (lf->lno_s < 0) /* Overflow */
1800 lf->lno_s = INT_MAX;
1801 lf->lno_e = lr->offset + lr->end;
1802 if (lf->lno_e < 0) /* Overflow */
1803 lf->lno_e = INT_MAX;
1804 pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1805 lr->start = lf->lno_s;
1806 lr->end = lf->lno_e;
1807 if (!die_is_func_instance(sp_die))
1808 param->retval = die_walk_instances(sp_die,
1809 line_range_inline_cb, lf);
1810 else
1811 param->retval = find_line_range_by_line(sp_die, lf);
1812 return DWARF_CB_ABORT;
1813 }
1814 return DWARF_CB_OK;
1815 }
1816
find_line_range_by_func(struct line_finder * lf)1817 static int find_line_range_by_func(struct line_finder *lf)
1818 {
1819 struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1820 dwarf_getfuncs(&lf->cu_die, line_range_search_cb, ¶m, 0);
1821 return param.retval;
1822 }
1823
debuginfo__find_line_range(struct debuginfo * dbg,struct line_range * lr)1824 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1825 {
1826 struct line_finder lf = {.lr = lr, .found = 0};
1827 int ret = 0;
1828 Dwarf_Off off = 0, noff;
1829 size_t cuhl;
1830 Dwarf_Die *diep;
1831 const char *comp_dir;
1832
1833 /* Fastpath: lookup by function name from .debug_pubnames section */
1834 if (lr->function) {
1835 struct pubname_callback_param pubname_param = {
1836 .function = lr->function, .file = lr->file,
1837 .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1838 struct dwarf_callback_param line_range_param = {
1839 .data = (void *)&lf, .retval = 0};
1840
1841 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1842 &pubname_param, 0);
1843 if (pubname_param.found) {
1844 line_range_search_cb(&lf.sp_die, &line_range_param);
1845 if (lf.found)
1846 goto found;
1847 }
1848 }
1849
1850 /* Loop on CUs (Compilation Unit) */
1851 while (!lf.found && ret >= 0) {
1852 if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1853 NULL, NULL, NULL) != 0)
1854 break;
1855
1856 /* Get the DIE(Debugging Information Entry) of this CU */
1857 diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1858 if (!diep) {
1859 off = noff;
1860 continue;
1861 }
1862
1863 /* Check if target file is included. */
1864 if (lr->file)
1865 lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1866 else
1867 lf.fname = 0;
1868
1869 if (!lr->file || lf.fname) {
1870 if (lr->function)
1871 ret = find_line_range_by_func(&lf);
1872 else {
1873 lf.lno_s = lr->start;
1874 lf.lno_e = lr->end;
1875 ret = find_line_range_by_line(NULL, &lf);
1876 }
1877 }
1878 off = noff;
1879 }
1880
1881 found:
1882 /* Store comp_dir */
1883 if (lf.found) {
1884 comp_dir = cu_get_comp_dir(&lf.cu_die);
1885 if (comp_dir) {
1886 lr->comp_dir = strdup(comp_dir);
1887 if (!lr->comp_dir)
1888 ret = -ENOMEM;
1889 }
1890 }
1891
1892 pr_debug("path: %s\n", lr->path);
1893 return (ret < 0) ? ret : lf.found;
1894 }
1895
1896 /*
1897 * Find a src file from a DWARF tag path. Prepend optional source path prefix
1898 * and chop off leading directories that do not exist. Result is passed back as
1899 * a newly allocated path on success.
1900 * Return 0 if file was found and readable, -errno otherwise.
1901 */
find_source_path(const char * raw_path,const char * sbuild_id,const char * comp_dir,char ** new_path)1902 int find_source_path(const char *raw_path, const char *sbuild_id,
1903 const char *comp_dir, char **new_path)
1904 {
1905 const char *prefix = symbol_conf.source_prefix;
1906
1907 if (sbuild_id && !prefix) {
1908 char prefixed_raw_path[PATH_MAX];
1909
1910 path__join(prefixed_raw_path, sizeof(prefixed_raw_path), comp_dir, raw_path);
1911
1912 if (!get_source_from_debuginfod(prefixed_raw_path, sbuild_id, new_path))
1913 return 0;
1914 }
1915
1916 if (!prefix) {
1917 if (raw_path[0] != '/' && comp_dir)
1918 /* If not an absolute path, try to use comp_dir */
1919 prefix = comp_dir;
1920 else {
1921 if (access(raw_path, R_OK) == 0) {
1922 *new_path = strdup(raw_path);
1923 return *new_path ? 0 : -ENOMEM;
1924 } else
1925 return -errno;
1926 }
1927 }
1928
1929 *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
1930 if (!*new_path)
1931 return -ENOMEM;
1932
1933 for (;;) {
1934 sprintf(*new_path, "%s/%s", prefix, raw_path);
1935
1936 if (access(*new_path, R_OK) == 0)
1937 return 0;
1938
1939 if (!symbol_conf.source_prefix) {
1940 /* In case of searching comp_dir, don't retry */
1941 zfree(new_path);
1942 return -errno;
1943 }
1944
1945 switch (errno) {
1946 case ENAMETOOLONG:
1947 case ENOENT:
1948 case EROFS:
1949 case EFAULT:
1950 raw_path = strchr(++raw_path, '/');
1951 if (!raw_path) {
1952 zfree(new_path);
1953 return -ENOENT;
1954 }
1955 continue;
1956
1957 default:
1958 zfree(new_path);
1959 return -errno;
1960 }
1961 }
1962 }
1963