2 * probe-finder.c : C expression to kprobe event converter
4 * Written by Masami Hiramatsu <mhiramat@redhat.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
22 #include <sys/utsname.h>
23 #include <sys/types.h>
39 #include "probe-finder.h"
43 * Generic dwarf analysis helpers
46 #define X86_32_MAX_REGS 8
47 const char *x86_32_regs_table[X86_32_MAX_REGS] = {
52 "$stack", /* Stack address instead of %sp */
58 #define X86_64_MAX_REGS 16
59 const char *x86_64_regs_table[X86_64_MAX_REGS] = {
78 /* TODO: switching by dwarf address size */
80 #define ARCH_MAX_REGS X86_64_MAX_REGS
81 #define arch_regs_table x86_64_regs_table
83 #define ARCH_MAX_REGS X86_32_MAX_REGS
84 #define arch_regs_table x86_32_regs_table
87 /* Return architecture dependent register string (for kprobe-tracer) */
88 static const char *get_arch_regstr(unsigned int n)
90 return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
94 * Compare the tail of two strings.
95 * Return 0 if whole of either string is same as another's tail part.
97 static int strtailcmp(const char *s1, const char *s2)
101 while (--i1 >= 0 && --i2 >= 0) {
102 if (s1[i1] != s2[i2])
103 return s1[i1] - s2[i2];
108 /* Line number list operations */
110 /* Add a line to line number list */
111 static void line_list__add_line(struct list_head *head, unsigned int line)
113 struct line_node *ln;
116 /* Reverse search, because new line will be the last one */
117 list_for_each_entry_reverse(ln, head, list) {
118 if (ln->line < line) {
121 } else if (ln->line == line) /* Already exist */
124 /* List is empty, or the smallest entry */
127 pr_debug("line list: add a line %u\n", line);
128 ln = xzalloc(sizeof(struct line_node));
130 INIT_LIST_HEAD(&ln->list);
131 list_add(&ln->list, p);
134 /* Check if the line in line number list */
135 static int line_list__has_line(struct list_head *head, unsigned int line)
137 struct line_node *ln;
139 /* Reverse search, because new line will be the last one */
140 list_for_each_entry(ln, head, list)
141 if (ln->line == line)
147 /* Init line number list */
148 static void line_list__init(struct list_head *head)
150 INIT_LIST_HEAD(head);
153 /* Free line number list */
154 static void line_list__free(struct list_head *head)
156 struct line_node *ln;
157 while (!list_empty(head)) {
158 ln = list_first_entry(head, struct line_node, list);
166 /* Find the realpath of the target file. */
167 static const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname)
171 const char *src = NULL;
177 ret = dwarf_getsrcfiles(cu_die, &files, &nfiles);
181 for (i = 0; i < nfiles; i++) {
182 src = dwarf_filesrc(files, i, NULL, NULL);
183 if (strtailcmp(src, fname) == 0)
189 /* Compare diename and tname */
190 static bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
193 name = dwarf_diename(dw_die);
194 DIE_IF(name == NULL);
195 return strcmp(tname, name);
198 /* Get entry pc(or low pc, 1st entry of ranges) of the die */
199 static Dwarf_Addr die_get_entrypc(Dwarf_Die *dw_die)
204 ret = dwarf_entrypc(dw_die, &epc);
209 /* Return values for die_find callbacks */
211 DIE_FIND_CB_FOUND = 0, /* End of Search */
212 DIE_FIND_CB_CHILD = 1, /* Search only children */
213 DIE_FIND_CB_SIBLING = 2, /* Search only siblings */
214 DIE_FIND_CB_CONTINUE = 3, /* Search children and siblings */
217 /* Search a child die */
218 static Dwarf_Die *die_find_child(Dwarf_Die *rt_die,
219 int (*callback)(Dwarf_Die *, void *),
220 void *data, Dwarf_Die *die_mem)
225 ret = dwarf_child(rt_die, die_mem);
230 ret = callback(die_mem, data);
231 if (ret == DIE_FIND_CB_FOUND)
234 if ((ret & DIE_FIND_CB_CHILD) &&
235 die_find_child(die_mem, callback, data, &child_die)) {
236 memcpy(die_mem, &child_die, sizeof(Dwarf_Die));
239 } while ((ret & DIE_FIND_CB_SIBLING) &&
240 dwarf_siblingof(die_mem, die_mem) == 0);
245 struct __addr_die_search_param {
250 static int __die_search_func_cb(Dwarf_Die *fn_die, void *data)
252 struct __addr_die_search_param *ad = data;
254 if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
255 dwarf_haspc(fn_die, ad->addr)) {
256 memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
257 return DWARF_CB_ABORT;
262 /* Search a real subprogram including this line, */
263 static Dwarf_Die *die_find_real_subprogram(Dwarf_Die *cu_die, Dwarf_Addr addr,
266 struct __addr_die_search_param ad;
268 ad.die_mem = die_mem;
269 /* dwarf_getscopes can't find subprogram. */
270 if (!dwarf_getfuncs(cu_die, __die_search_func_cb, &ad, 0))
276 /* die_find callback for inline function search */
277 static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data)
279 Dwarf_Addr *addr = data;
281 if (dwarf_tag(die_mem) == DW_TAG_inlined_subroutine &&
282 dwarf_haspc(die_mem, *addr))
283 return DIE_FIND_CB_FOUND;
285 return DIE_FIND_CB_CONTINUE;
288 /* Similar to dwarf_getfuncs, but returns inlined_subroutine if exists. */
289 static Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
292 return die_find_child(sp_die, __die_find_inline_cb, &addr, die_mem);
295 static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data)
297 const char *name = data;
300 tag = dwarf_tag(die_mem);
301 if ((tag == DW_TAG_formal_parameter ||
302 tag == DW_TAG_variable) &&
303 (die_compare_name(die_mem, name) == 0))
304 return DIE_FIND_CB_FOUND;
306 return DIE_FIND_CB_CONTINUE;
309 /* Find a variable called 'name' */
310 static Dwarf_Die *die_find_variable(Dwarf_Die *sp_die, const char *name,
313 return die_find_child(sp_die, __die_find_variable_cb, (void *)name,
318 * Probe finder related functions
321 /* Show a location */
322 static void show_location(Dwarf_Op *op, struct probe_finder *pf)
329 /* TODO: support CFA */
330 /* If this is based on frame buffer, set the offset */
331 if (op->atom == DW_OP_fbreg) {
332 if (pf->fb_ops == NULL)
333 die("The attribute of frame base is not supported.\n");
339 if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
340 regn = op->atom - DW_OP_breg0;
343 } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
344 regn = op->atom - DW_OP_reg0;
345 } else if (op->atom == DW_OP_bregx) {
349 } else if (op->atom == DW_OP_regx) {
352 die("DW_OP %d is not supported.", op->atom);
354 regs = get_arch_regstr(regn);
356 die("%u exceeds max register number.", regn);
359 ret = snprintf(pf->buf, pf->len, " %s=%+jd(%s)",
360 pf->var, (intmax_t)offs, regs);
362 ret = snprintf(pf->buf, pf->len, " %s=%s", pf->var, regs);
364 DIE_IF(ret >= pf->len);
367 /* Show a variables in kprobe event format */
368 static void show_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
370 Dwarf_Attribute attr;
375 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
377 /* TODO: handle more than 1 exprs */
378 ret = dwarf_getlocation_addr(&attr, pf->addr, &expr, &nexpr, 1);
379 if (ret <= 0 || nexpr == 0)
382 show_location(expr, pf);
383 /* *expr will be cached in libdw. Don't free it. */
386 /* TODO: Support const_value */
387 die("Failed to find the location of %s at this address.\n"
388 " Perhaps, it has been optimized out.", pf->var);
391 /* Find a variable in a subprogram die */
392 static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
397 /* TODO: Support struct members and arrays */
398 if (!is_c_varname(pf->var)) {
399 /* Output raw parameters */
400 ret = snprintf(pf->buf, pf->len, " %s", pf->var);
402 DIE_IF(ret >= pf->len);
406 pr_debug("Searching '%s' variable in context.\n", pf->var);
407 /* Search child die for local variables and parameters. */
408 if (!die_find_variable(sp_die, pf->var, &vr_die))
409 die("Failed to find '%s' in this function.", pf->var);
411 show_variable(&vr_die, pf);
414 /* Show a probe point to output buffer */
415 static void show_probe_point(Dwarf_Die *sp_die, struct probe_finder *pf)
417 struct probe_point *pp = pf->pp;
421 char tmp[MAX_PROBE_BUFFER];
423 Dwarf_Attribute fb_attr;
426 /* If no real subprogram, find a real one */
427 if (!sp_die || dwarf_tag(sp_die) != DW_TAG_subprogram) {
428 sp_die = die_find_real_subprogram(&pf->cu_die,
431 die("Probe point is not found in subprograms.");
434 /* Output name of probe point */
435 name = dwarf_diename(sp_die);
437 dwarf_entrypc(sp_die, &eaddr);
438 ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%lu", name,
439 (unsigned long)(pf->addr - eaddr));
440 /* Copy the function name if possible */
442 pp->function = xstrdup(name);
443 pp->offset = (size_t)(pf->addr - eaddr);
446 /* This function has no name. */
447 ret = snprintf(tmp, MAX_PROBE_BUFFER, "0x%jx",
448 (uintmax_t)pf->addr);
450 /* TODO: Use _stext */
451 pp->function = xstrdup("");
452 pp->offset = (size_t)pf->addr;
456 DIE_IF(ret >= MAX_PROBE_BUFFER);
458 pr_debug("Probe point found: %s\n", tmp);
460 /* Get the frame base attribute/ops */
461 dwarf_attr(sp_die, DW_AT_frame_base, &fb_attr);
462 ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
463 if (ret <= 0 || nops == 0)
466 /* Find each argument */
467 /* TODO: use dwarf_cfi_addrframe */
468 for (i = 0; i < pp->nr_args; i++) {
469 pf->var = pp->args[i];
471 pf->len = MAX_PROBE_BUFFER - len;
472 find_variable(sp_die, pf);
473 len += strlen(pf->buf);
476 /* *pf->fb_ops will be cached in libdw. Don't free it. */
479 if (pp->found == MAX_PROBES)
480 die("Too many( > %d) probe point found.\n", MAX_PROBES);
482 pp->probes[pp->found] = xstrdup(tmp);
486 /* Find probe point from its line number */
487 static void find_probe_point_by_line(struct probe_finder *pf)
496 ret = dwarf_getsrclines(&pf->cu_die, &lines, &nlines);
499 for (i = 0; i < nlines; i++) {
500 line = dwarf_onesrcline(lines, i);
501 dwarf_lineno(line, &lineno);
502 if (lineno != pf->lno)
505 /* TODO: Get fileno from line, but how? */
506 if (strtailcmp(dwarf_linesrc(line, NULL, NULL), pf->fname) != 0)
509 ret = dwarf_lineaddr(line, &addr);
511 pr_debug("Probe line found: line[%d]:%d addr:0x%jx\n",
512 (int)i, lineno, (uintmax_t)addr);
515 show_probe_point(NULL, pf);
516 /* Continuing, because target line might be inlined. */
520 /* Find lines which match lazy pattern */
521 static int find_lazy_match_lines(struct list_head *head,
522 const char *fname, const char *pat)
524 char *fbuf, *p1, *p2;
525 int fd, line, nlines = 0;
528 fd = open(fname, O_RDONLY);
530 die("failed to open %s", fname);
531 DIE_IF(fstat(fd, &st) < 0);
532 fbuf = xmalloc(st.st_size + 2);
533 DIE_IF(read(fd, fbuf, st.st_size) < 0);
535 fbuf[st.st_size] = '\n'; /* Dummy line */
536 fbuf[st.st_size + 1] = '\0';
539 while ((p2 = strchr(p1, '\n')) != NULL) {
541 if (strlazymatch(p1, pat)) {
542 line_list__add_line(head, line);
552 /* Find probe points from lazy pattern */
553 static void find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
563 if (list_empty(&pf->lcache)) {
564 /* Matching lazy line pattern */
565 ret = find_lazy_match_lines(&pf->lcache, pf->fname,
568 die("No matched lines found in %s.", pf->fname);
571 ret = dwarf_getsrclines(&pf->cu_die, &lines, &nlines);
573 for (i = 0; i < nlines; i++) {
574 line = dwarf_onesrcline(lines, i);
576 dwarf_lineno(line, &lineno);
577 if (!line_list__has_line(&pf->lcache, lineno))
580 /* TODO: Get fileno from line, but how? */
581 if (strtailcmp(dwarf_linesrc(line, NULL, NULL), pf->fname) != 0)
584 ret = dwarf_lineaddr(line, &addr);
587 /* Address filtering 1: does sp_die include addr? */
588 if (!dwarf_haspc(sp_die, addr))
590 /* Address filtering 2: No child include addr? */
591 if (die_find_inlinefunc(sp_die, addr, &die_mem))
595 pr_debug("Probe line found: line[%d]:%d addr:0x%llx\n",
596 (int)i, lineno, (unsigned long long)addr);
599 show_probe_point(sp_die, pf);
600 /* Continuing, because target line might be inlined. */
602 /* TODO: deallocate lines, but how? */
605 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
607 struct probe_finder *pf = (struct probe_finder *)data;
608 struct probe_point *pp = pf->pp;
611 find_probe_point_lazy(in_die, pf);
613 /* Get probe address */
614 pf->addr = die_get_entrypc(in_die);
615 pf->addr += pp->offset;
616 pr_debug("found inline addr: 0x%jx\n",
617 (uintmax_t)pf->addr);
619 show_probe_point(in_die, pf);
625 /* Search function from function name */
626 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
628 struct probe_finder *pf = (struct probe_finder *)data;
629 struct probe_point *pp = pf->pp;
631 /* Check tag and diename */
632 if (dwarf_tag(sp_die) != DW_TAG_subprogram ||
633 die_compare_name(sp_die, pp->function) != 0)
636 pf->fname = dwarf_decl_file(sp_die);
637 if (pp->line) { /* Function relative line */
638 dwarf_decl_line(sp_die, &pf->lno);
640 find_probe_point_by_line(pf);
641 } else if (!dwarf_func_inline(sp_die)) {
644 find_probe_point_lazy(sp_die, pf);
646 pf->addr = die_get_entrypc(sp_die);
647 pf->addr += pp->offset;
648 /* TODO: Check the address in this function */
649 show_probe_point(sp_die, pf);
652 /* Inlined function: search instances */
653 dwarf_func_inline_instances(sp_die, probe_point_inline_cb, pf);
655 return 1; /* Exit; no same symbol in this CU. */
658 static void find_probe_point_by_func(struct probe_finder *pf)
660 dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, pf, 0);
663 /* Find a probe point */
664 int find_probe_point(int fd, struct probe_point *pp)
666 struct probe_finder pf = {.pp = pp};
672 dbg = dwarf_begin(fd, DWARF_C_READ);
678 line_list__init(&pf.lcache);
679 /* Loop on CUs (Compilation Unit) */
680 while (!dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
681 /* Get the DIE(Debugging Information Entry) of this CU */
682 diep = dwarf_offdie(dbg, off + cuhl, &pf.cu_die);
686 /* Check if target file is included. */
688 pf.fname = cu_find_realpath(&pf.cu_die, pp->file);
692 if (!pp->file || pf.fname) {
694 find_probe_point_by_func(&pf);
695 else if (pp->lazy_line)
696 find_probe_point_lazy(NULL, &pf);
699 find_probe_point_by_line(&pf);
704 line_list__free(&pf.lcache);
710 /* Find line range from its line number */
711 static void find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
722 line_list__init(&lf->lr->line_list);
723 ret = dwarf_getsrclines(&lf->cu_die, &lines, &nlines);
726 for (i = 0; i < nlines; i++) {
727 line = dwarf_onesrcline(lines, i);
728 ret = dwarf_lineno(line, &lineno);
730 if (lf->lno_s > lineno || lf->lno_e < lineno)
734 /* Address filtering 1: does sp_die include addr? */
735 ret = dwarf_lineaddr(line, &addr);
737 if (!dwarf_haspc(sp_die, addr))
740 /* Address filtering 2: No child include addr? */
741 if (die_find_inlinefunc(sp_die, addr, &die_mem))
745 /* TODO: Get fileno from line, but how? */
746 src = dwarf_linesrc(line, NULL, NULL);
747 if (strtailcmp(src, lf->fname) != 0)
752 lf->lr->path = xstrdup(src);
753 line_list__add_line(&lf->lr->line_list, (unsigned int)lineno);
756 if (!list_empty(&lf->lr->line_list))
764 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
766 find_line_range_by_line(in_die, (struct line_finder *)data);
767 return DWARF_CB_ABORT; /* No need to find other instances */
770 /* Search function from function name */
771 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
773 struct line_finder *lf = (struct line_finder *)data;
774 struct line_range *lr = lf->lr;
776 if (dwarf_tag(sp_die) == DW_TAG_subprogram &&
777 die_compare_name(sp_die, lr->function) == 0) {
778 lf->fname = dwarf_decl_file(sp_die);
779 dwarf_decl_line(sp_die, &lr->offset);
780 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
781 lf->lno_s = lr->offset + lr->start;
785 lf->lno_e = lr->offset + lr->end;
786 lr->start = lf->lno_s;
788 if (dwarf_func_inline(sp_die))
789 dwarf_func_inline_instances(sp_die,
790 line_range_inline_cb, lf);
792 find_line_range_by_line(sp_die, lf);
798 static void find_line_range_by_func(struct line_finder *lf)
800 dwarf_getfuncs(&lf->cu_die, line_range_search_cb, lf, 0);
803 int find_line_range(int fd, struct line_range *lr)
805 struct line_finder lf = {.lr = lr, .found = 0};
807 Dwarf_Off off = 0, noff;
812 dbg = dwarf_begin(fd, DWARF_C_READ);
816 /* Loop on CUs (Compilation Unit) */
818 ret = dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL);
822 /* Get the DIE(Debugging Information Entry) of this CU */
823 diep = dwarf_offdie(dbg, off + cuhl, &lf.cu_die);
827 /* Check if target file is included. */
829 lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
833 if (!lr->file || lf.fname) {
835 find_line_range_by_func(&lf);
837 lf.lno_s = lr->start;
842 find_line_range_by_line(NULL, &lf);
847 pr_debug("path: %lx\n", (unsigned long)lr->path);