1 /* 2 * Common code for probe-based Dynamic events. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public License 14 * along with this program; if not, write to the Free Software 15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 16 * 17 * This code was copied from kernel/trace/trace_kprobe.c written by 18 * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> 19 * 20 * Updates to make this generic: 21 * Copyright (C) IBM Corporation, 2010-2011 22 * Author: Srikar Dronamraju 23 */ 24 25 #include "trace_probe.h" 26 27 const char *reserved_field_names[] = { 28 "common_type", 29 "common_flags", 30 "common_preempt_count", 31 "common_pid", 32 "common_tgid", 33 FIELD_STRING_IP, 34 FIELD_STRING_RETIP, 35 FIELD_STRING_FUNC, 36 }; 37 38 /* Printing in basic type function template */ 39 #define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt) \ 40 int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, const char *name, \ 41 void *data, void *ent) \ 42 { \ 43 trace_seq_printf(s, " %s=" fmt, name, *(type *)data); \ 44 return !trace_seq_has_overflowed(s); \ 45 } \ 46 const char PRINT_TYPE_FMT_NAME(type)[] = fmt; \ 47 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(type)); 48 49 DEFINE_BASIC_PRINT_TYPE_FUNC(u8 , "0x%x") 50 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "0x%x") 51 DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "0x%x") 52 DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "0x%Lx") 53 DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d") 54 DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d") 55 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%d") 56 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%Ld") 57 58 /* Print type function for string type */ 59 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name, 60 void *data, void *ent) 61 { 62 int len = *(u32 *)data >> 16; 63 64 if (!len) 65 trace_seq_printf(s, " %s=(fault)", name); 66 else 67 trace_seq_printf(s, " %s=\"%s\"", name, 68 (const char *)get_loc_data(data, ent)); 69 return !trace_seq_has_overflowed(s); 70 } 71 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string)); 72 73 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\""; 74 75 #define CHECK_FETCH_FUNCS(method, fn) \ 76 (((FETCH_FUNC_NAME(method, u8) == fn) || \ 77 (FETCH_FUNC_NAME(method, u16) == fn) || \ 78 (FETCH_FUNC_NAME(method, u32) == fn) || \ 79 (FETCH_FUNC_NAME(method, u64) == fn) || \ 80 (FETCH_FUNC_NAME(method, string) == fn) || \ 81 (FETCH_FUNC_NAME(method, string_size) == fn)) \ 82 && (fn != NULL)) 83 84 /* Data fetch function templates */ 85 #define DEFINE_FETCH_reg(type) \ 86 void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, void *offset, void *dest) \ 87 { \ 88 *(type *)dest = (type)regs_get_register(regs, \ 89 (unsigned int)((unsigned long)offset)); \ 90 } \ 91 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type)); 92 DEFINE_BASIC_FETCH_FUNCS(reg) 93 /* No string on the register */ 94 #define fetch_reg_string NULL 95 #define fetch_reg_string_size NULL 96 97 #define DEFINE_FETCH_retval(type) \ 98 void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs, \ 99 void *dummy, void *dest) \ 100 { \ 101 *(type *)dest = (type)regs_return_value(regs); \ 102 } \ 103 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type)); 104 DEFINE_BASIC_FETCH_FUNCS(retval) 105 /* No string on the retval */ 106 #define fetch_retval_string NULL 107 #define fetch_retval_string_size NULL 108 109 /* Dereference memory access function */ 110 struct deref_fetch_param { 111 struct fetch_param orig; 112 long offset; 113 fetch_func_t fetch; 114 fetch_func_t fetch_size; 115 }; 116 117 #define DEFINE_FETCH_deref(type) \ 118 void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs, \ 119 void *data, void *dest) \ 120 { \ 121 struct deref_fetch_param *dprm = data; \ 122 unsigned long addr; \ 123 call_fetch(&dprm->orig, regs, &addr); \ 124 if (addr) { \ 125 addr += dprm->offset; \ 126 dprm->fetch(regs, (void *)addr, dest); \ 127 } else \ 128 *(type *)dest = 0; \ 129 } \ 130 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type)); 131 DEFINE_BASIC_FETCH_FUNCS(deref) 132 DEFINE_FETCH_deref(string) 133 134 void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs, 135 void *data, void *dest) 136 { 137 struct deref_fetch_param *dprm = data; 138 unsigned long addr; 139 140 call_fetch(&dprm->orig, regs, &addr); 141 if (addr && dprm->fetch_size) { 142 addr += dprm->offset; 143 dprm->fetch_size(regs, (void *)addr, dest); 144 } else 145 *(string_size *)dest = 0; 146 } 147 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size)); 148 149 static void update_deref_fetch_param(struct deref_fetch_param *data) 150 { 151 if (CHECK_FETCH_FUNCS(deref, data->orig.fn)) 152 update_deref_fetch_param(data->orig.data); 153 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn)) 154 update_symbol_cache(data->orig.data); 155 } 156 NOKPROBE_SYMBOL(update_deref_fetch_param); 157 158 static void free_deref_fetch_param(struct deref_fetch_param *data) 159 { 160 if (CHECK_FETCH_FUNCS(deref, data->orig.fn)) 161 free_deref_fetch_param(data->orig.data); 162 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn)) 163 free_symbol_cache(data->orig.data); 164 kfree(data); 165 } 166 NOKPROBE_SYMBOL(free_deref_fetch_param); 167 168 /* Bitfield fetch function */ 169 struct bitfield_fetch_param { 170 struct fetch_param orig; 171 unsigned char hi_shift; 172 unsigned char low_shift; 173 }; 174 175 #define DEFINE_FETCH_bitfield(type) \ 176 void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs, \ 177 void *data, void *dest) \ 178 { \ 179 struct bitfield_fetch_param *bprm = data; \ 180 type buf = 0; \ 181 call_fetch(&bprm->orig, regs, &buf); \ 182 if (buf) { \ 183 buf <<= bprm->hi_shift; \ 184 buf >>= bprm->low_shift; \ 185 } \ 186 *(type *)dest = buf; \ 187 } \ 188 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type)); 189 DEFINE_BASIC_FETCH_FUNCS(bitfield) 190 #define fetch_bitfield_string NULL 191 #define fetch_bitfield_string_size NULL 192 193 static void 194 update_bitfield_fetch_param(struct bitfield_fetch_param *data) 195 { 196 /* 197 * Don't check the bitfield itself, because this must be the 198 * last fetch function. 199 */ 200 if (CHECK_FETCH_FUNCS(deref, data->orig.fn)) 201 update_deref_fetch_param(data->orig.data); 202 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn)) 203 update_symbol_cache(data->orig.data); 204 } 205 206 static void 207 free_bitfield_fetch_param(struct bitfield_fetch_param *data) 208 { 209 /* 210 * Don't check the bitfield itself, because this must be the 211 * last fetch function. 212 */ 213 if (CHECK_FETCH_FUNCS(deref, data->orig.fn)) 214 free_deref_fetch_param(data->orig.data); 215 else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn)) 216 free_symbol_cache(data->orig.data); 217 218 kfree(data); 219 } 220 221 static const struct fetch_type *find_fetch_type(const char *type, 222 const struct fetch_type *ftbl) 223 { 224 int i; 225 226 if (!type) 227 type = DEFAULT_FETCH_TYPE_STR; 228 229 /* Special case: bitfield */ 230 if (*type == 'b') { 231 unsigned long bs; 232 233 type = strchr(type, '/'); 234 if (!type) 235 goto fail; 236 237 type++; 238 if (kstrtoul(type, 0, &bs)) 239 goto fail; 240 241 switch (bs) { 242 case 8: 243 return find_fetch_type("u8", ftbl); 244 case 16: 245 return find_fetch_type("u16", ftbl); 246 case 32: 247 return find_fetch_type("u32", ftbl); 248 case 64: 249 return find_fetch_type("u64", ftbl); 250 default: 251 goto fail; 252 } 253 } 254 255 for (i = 0; ftbl[i].name; i++) { 256 if (strcmp(type, ftbl[i].name) == 0) 257 return &ftbl[i]; 258 } 259 260 fail: 261 return NULL; 262 } 263 264 /* Special function : only accept unsigned long */ 265 static void fetch_kernel_stack_address(struct pt_regs *regs, void *dummy, void *dest) 266 { 267 *(unsigned long *)dest = kernel_stack_pointer(regs); 268 } 269 NOKPROBE_SYMBOL(fetch_kernel_stack_address); 270 271 static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *dest) 272 { 273 *(unsigned long *)dest = user_stack_pointer(regs); 274 } 275 NOKPROBE_SYMBOL(fetch_user_stack_address); 276 277 static fetch_func_t get_fetch_size_function(const struct fetch_type *type, 278 fetch_func_t orig_fn, 279 const struct fetch_type *ftbl) 280 { 281 int i; 282 283 if (type != &ftbl[FETCH_TYPE_STRING]) 284 return NULL; /* Only string type needs size function */ 285 286 for (i = 0; i < FETCH_MTD_END; i++) 287 if (type->fetch[i] == orig_fn) 288 return ftbl[FETCH_TYPE_STRSIZE].fetch[i]; 289 290 WARN_ON(1); /* This should not happen */ 291 292 return NULL; 293 } 294 295 /* Split symbol and offset. */ 296 int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset) 297 { 298 char *tmp; 299 int ret; 300 301 if (!offset) 302 return -EINVAL; 303 304 tmp = strchr(symbol, '+'); 305 if (tmp) { 306 /* skip sign because kstrtoul doesn't accept '+' */ 307 ret = kstrtoul(tmp + 1, 0, offset); 308 if (ret) 309 return ret; 310 311 *tmp = '\0'; 312 } else 313 *offset = 0; 314 315 return 0; 316 } 317 318 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long)) 319 320 static int parse_probe_vars(char *arg, const struct fetch_type *t, 321 struct fetch_param *f, bool is_return, 322 bool is_kprobe) 323 { 324 int ret = 0; 325 unsigned long param; 326 327 if (strcmp(arg, "retval") == 0) { 328 if (is_return) 329 f->fn = t->fetch[FETCH_MTD_retval]; 330 else 331 ret = -EINVAL; 332 } else if (strncmp(arg, "stack", 5) == 0) { 333 if (arg[5] == '\0') { 334 if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR)) 335 return -EINVAL; 336 337 if (is_kprobe) 338 f->fn = fetch_kernel_stack_address; 339 else 340 f->fn = fetch_user_stack_address; 341 } else if (isdigit(arg[5])) { 342 ret = kstrtoul(arg + 5, 10, ¶m); 343 if (ret || (is_kprobe && param > PARAM_MAX_STACK)) 344 ret = -EINVAL; 345 else { 346 f->fn = t->fetch[FETCH_MTD_stack]; 347 f->data = (void *)param; 348 } 349 } else 350 ret = -EINVAL; 351 } else 352 ret = -EINVAL; 353 354 return ret; 355 } 356 357 /* Recursive argument parser */ 358 static int parse_probe_arg(char *arg, const struct fetch_type *t, 359 struct fetch_param *f, bool is_return, bool is_kprobe) 360 { 361 const struct fetch_type *ftbl; 362 unsigned long param; 363 long offset; 364 char *tmp; 365 int ret = 0; 366 367 ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table; 368 BUG_ON(ftbl == NULL); 369 370 switch (arg[0]) { 371 case '$': 372 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe); 373 break; 374 375 case '%': /* named register */ 376 ret = regs_query_register_offset(arg + 1); 377 if (ret >= 0) { 378 f->fn = t->fetch[FETCH_MTD_reg]; 379 f->data = (void *)(unsigned long)ret; 380 ret = 0; 381 } 382 break; 383 384 case '@': /* memory, file-offset or symbol */ 385 if (isdigit(arg[1])) { 386 ret = kstrtoul(arg + 1, 0, ¶m); 387 if (ret) 388 break; 389 390 f->fn = t->fetch[FETCH_MTD_memory]; 391 f->data = (void *)param; 392 } else if (arg[1] == '+') { 393 /* kprobes don't support file offsets */ 394 if (is_kprobe) 395 return -EINVAL; 396 397 ret = kstrtol(arg + 2, 0, &offset); 398 if (ret) 399 break; 400 401 f->fn = t->fetch[FETCH_MTD_file_offset]; 402 f->data = (void *)offset; 403 } else { 404 /* uprobes don't support symbols */ 405 if (!is_kprobe) 406 return -EINVAL; 407 408 ret = traceprobe_split_symbol_offset(arg + 1, &offset); 409 if (ret) 410 break; 411 412 f->data = alloc_symbol_cache(arg + 1, offset); 413 if (f->data) 414 f->fn = t->fetch[FETCH_MTD_symbol]; 415 } 416 break; 417 418 case '+': /* deref memory */ 419 arg++; /* Skip '+', because kstrtol() rejects it. */ 420 case '-': 421 tmp = strchr(arg, '('); 422 if (!tmp) 423 break; 424 425 *tmp = '\0'; 426 ret = kstrtol(arg, 0, &offset); 427 428 if (ret) 429 break; 430 431 arg = tmp + 1; 432 tmp = strrchr(arg, ')'); 433 434 if (tmp) { 435 struct deref_fetch_param *dprm; 436 const struct fetch_type *t2; 437 438 t2 = find_fetch_type(NULL, ftbl); 439 *tmp = '\0'; 440 dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL); 441 442 if (!dprm) 443 return -ENOMEM; 444 445 dprm->offset = offset; 446 dprm->fetch = t->fetch[FETCH_MTD_memory]; 447 dprm->fetch_size = get_fetch_size_function(t, 448 dprm->fetch, ftbl); 449 ret = parse_probe_arg(arg, t2, &dprm->orig, is_return, 450 is_kprobe); 451 if (ret) 452 kfree(dprm); 453 else { 454 f->fn = t->fetch[FETCH_MTD_deref]; 455 f->data = (void *)dprm; 456 } 457 } 458 break; 459 } 460 if (!ret && !f->fn) { /* Parsed, but do not find fetch method */ 461 pr_info("%s type has no corresponding fetch method.\n", t->name); 462 ret = -EINVAL; 463 } 464 465 return ret; 466 } 467 468 #define BYTES_TO_BITS(nb) ((BITS_PER_LONG * (nb)) / sizeof(long)) 469 470 /* Bitfield type needs to be parsed into a fetch function */ 471 static int __parse_bitfield_probe_arg(const char *bf, 472 const struct fetch_type *t, 473 struct fetch_param *f) 474 { 475 struct bitfield_fetch_param *bprm; 476 unsigned long bw, bo; 477 char *tail; 478 479 if (*bf != 'b') 480 return 0; 481 482 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 483 if (!bprm) 484 return -ENOMEM; 485 486 bprm->orig = *f; 487 f->fn = t->fetch[FETCH_MTD_bitfield]; 488 f->data = (void *)bprm; 489 bw = simple_strtoul(bf + 1, &tail, 0); /* Use simple one */ 490 491 if (bw == 0 || *tail != '@') 492 return -EINVAL; 493 494 bf = tail + 1; 495 bo = simple_strtoul(bf, &tail, 0); 496 497 if (tail == bf || *tail != '/') 498 return -EINVAL; 499 500 bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo); 501 bprm->low_shift = bprm->hi_shift + bo; 502 503 return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0; 504 } 505 506 /* String length checking wrapper */ 507 int traceprobe_parse_probe_arg(char *arg, ssize_t *size, 508 struct probe_arg *parg, bool is_return, bool is_kprobe) 509 { 510 const struct fetch_type *ftbl; 511 const char *t; 512 int ret; 513 514 ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table; 515 BUG_ON(ftbl == NULL); 516 517 if (strlen(arg) > MAX_ARGSTR_LEN) { 518 pr_info("Argument is too long.: %s\n", arg); 519 return -ENOSPC; 520 } 521 parg->comm = kstrdup(arg, GFP_KERNEL); 522 if (!parg->comm) { 523 pr_info("Failed to allocate memory for command '%s'.\n", arg); 524 return -ENOMEM; 525 } 526 t = strchr(parg->comm, ':'); 527 if (t) { 528 arg[t - parg->comm] = '\0'; 529 t++; 530 } 531 parg->type = find_fetch_type(t, ftbl); 532 if (!parg->type) { 533 pr_info("Unsupported type: %s\n", t); 534 return -EINVAL; 535 } 536 parg->offset = *size; 537 *size += parg->type->size; 538 ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe); 539 540 if (ret >= 0 && t != NULL) 541 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch); 542 543 if (ret >= 0) { 544 parg->fetch_size.fn = get_fetch_size_function(parg->type, 545 parg->fetch.fn, 546 ftbl); 547 parg->fetch_size.data = parg->fetch.data; 548 } 549 550 return ret; 551 } 552 553 /* Return 1 if name is reserved or already used by another argument */ 554 int traceprobe_conflict_field_name(const char *name, 555 struct probe_arg *args, int narg) 556 { 557 int i; 558 559 for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++) 560 if (strcmp(reserved_field_names[i], name) == 0) 561 return 1; 562 563 for (i = 0; i < narg; i++) 564 if (strcmp(args[i].name, name) == 0) 565 return 1; 566 567 return 0; 568 } 569 570 void traceprobe_update_arg(struct probe_arg *arg) 571 { 572 if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn)) 573 update_bitfield_fetch_param(arg->fetch.data); 574 else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn)) 575 update_deref_fetch_param(arg->fetch.data); 576 else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn)) 577 update_symbol_cache(arg->fetch.data); 578 } 579 580 void traceprobe_free_probe_arg(struct probe_arg *arg) 581 { 582 if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn)) 583 free_bitfield_fetch_param(arg->fetch.data); 584 else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn)) 585 free_deref_fetch_param(arg->fetch.data); 586 else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn)) 587 free_symbol_cache(arg->fetch.data); 588 589 kfree(arg->name); 590 kfree(arg->comm); 591 } 592 593 int traceprobe_command(const char *buf, int (*createfn)(int, char **)) 594 { 595 char **argv; 596 int argc, ret; 597 598 argc = 0; 599 ret = 0; 600 argv = argv_split(GFP_KERNEL, buf, &argc); 601 if (!argv) 602 return -ENOMEM; 603 604 if (argc) 605 ret = createfn(argc, argv); 606 607 argv_free(argv); 608 609 return ret; 610 } 611 612 #define WRITE_BUFSIZE 4096 613 614 ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer, 615 size_t count, loff_t *ppos, 616 int (*createfn)(int, char **)) 617 { 618 char *kbuf, *tmp; 619 int ret = 0; 620 size_t done = 0; 621 size_t size; 622 623 kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL); 624 if (!kbuf) 625 return -ENOMEM; 626 627 while (done < count) { 628 size = count - done; 629 630 if (size >= WRITE_BUFSIZE) 631 size = WRITE_BUFSIZE - 1; 632 633 if (copy_from_user(kbuf, buffer + done, size)) { 634 ret = -EFAULT; 635 goto out; 636 } 637 kbuf[size] = '\0'; 638 tmp = strchr(kbuf, '\n'); 639 640 if (tmp) { 641 *tmp = '\0'; 642 size = tmp - kbuf + 1; 643 } else if (done + size < count) { 644 pr_warning("Line length is too long: " 645 "Should be less than %d.", WRITE_BUFSIZE); 646 ret = -EINVAL; 647 goto out; 648 } 649 done += size; 650 /* Remove comments */ 651 tmp = strchr(kbuf, '#'); 652 653 if (tmp) 654 *tmp = '\0'; 655 656 ret = traceprobe_command(kbuf, createfn); 657 if (ret) 658 goto out; 659 } 660 ret = done; 661 662 out: 663 kfree(kbuf); 664 665 return ret; 666 } 667 668 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len, 669 bool is_return) 670 { 671 int i; 672 int pos = 0; 673 674 const char *fmt, *arg; 675 676 if (!is_return) { 677 fmt = "(%lx)"; 678 arg = "REC->" FIELD_STRING_IP; 679 } else { 680 fmt = "(%lx <- %lx)"; 681 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP; 682 } 683 684 /* When len=0, we just calculate the needed length */ 685 #define LEN_OR_ZERO (len ? len - pos : 0) 686 687 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt); 688 689 for (i = 0; i < tp->nr_args; i++) { 690 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s", 691 tp->args[i].name, tp->args[i].type->fmt); 692 } 693 694 pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg); 695 696 for (i = 0; i < tp->nr_args; i++) { 697 if (strcmp(tp->args[i].type->name, "string") == 0) 698 pos += snprintf(buf + pos, LEN_OR_ZERO, 699 ", __get_str(%s)", 700 tp->args[i].name); 701 else 702 pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s", 703 tp->args[i].name); 704 } 705 706 #undef LEN_OR_ZERO 707 708 /* return the length of print_fmt */ 709 return pos; 710 } 711 712 int set_print_fmt(struct trace_probe *tp, bool is_return) 713 { 714 int len; 715 char *print_fmt; 716 717 /* First: called with 0 length to calculate the needed length */ 718 len = __set_print_fmt(tp, NULL, 0, is_return); 719 print_fmt = kmalloc(len + 1, GFP_KERNEL); 720 if (!print_fmt) 721 return -ENOMEM; 722 723 /* Second: actually write the @print_fmt */ 724 __set_print_fmt(tp, print_fmt, len + 1, is_return); 725 tp->call.print_fmt = print_fmt; 726 727 return 0; 728 } 729