kernel/trace/trace_probe.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Common code for probe-based Dynamic events.
   4  *
   5  * This code was copied from kernel/trace/trace_kprobe.c written by
   6  * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
   7  *
   8  * Updates to make this generic:
   9  * Copyright (C) IBM Corporation, 2010-2011
  10  * Author:     Srikar Dronamraju
  11  */
  12 #define pr_fmt(fmt)     "trace_probe: " fmt
  13
  14 #include "trace_probe.h"
  15
  16 static const char *reserved_field_names[] = {
  17         "common_type",
  18         "common_flags",
  19         "common_preempt_count",
  20         "common_pid",
  21         "common_tgid",
  22         FIELD_STRING_IP,
  23         FIELD_STRING_RETIP,
  24         FIELD_STRING_FUNC,
  25 };
  26
  27 /* Printing  in basic type function template */
  28 #define DEFINE_BASIC_PRINT_TYPE_FUNC(tname, type, fmt)                  \
  29 int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, void *data, void *ent)\
  30 {                                                                       \
  31         trace_seq_printf(s, fmt, *(type *)data);                        \
  32         return !trace_seq_has_overflowed(s);                            \
  33 }                                                                       \
  34 const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;
  35
  36 DEFINE_BASIC_PRINT_TYPE_FUNC(u8,  u8,  "%u")
  37 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
  38 DEFINE_BASIC_PRINT_TYPE_FUNC(u32, u32, "%u")
  39 DEFINE_BASIC_PRINT_TYPE_FUNC(u64, u64, "%Lu")
  40 DEFINE_BASIC_PRINT_TYPE_FUNC(s8,  s8,  "%d")
  41 DEFINE_BASIC_PRINT_TYPE_FUNC(s16, s16, "%d")
  42 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, s32, "%d")
  43 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, s64, "%Ld")
  44 DEFINE_BASIC_PRINT_TYPE_FUNC(x8,  u8,  "0x%x")
  45 DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
  46 DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
  47 DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
  48
  49 int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent)
  50 {
  51         trace_seq_printf(s, "%pS", (void *)*(unsigned long *)data);
  52         return !trace_seq_has_overflowed(s);
  53 }
  54 const char PRINT_TYPE_FMT_NAME(symbol)[] = "%pS";
  55
  56 /* Print type function for string type */
  57 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
  58 {
  59         int len = *(u32 *)data >> 16;
  60
  61         if (!len)
  62                 trace_seq_puts(s, "(fault)");
  63         else
  64                 trace_seq_printf(s, "\"%s\"",
  65                                  (const char *)get_loc_data(data, ent));
  66         return !trace_seq_has_overflowed(s);
  67 }
  68
  69 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
  70
  71 /* Fetch type information table */
  72 static const struct fetch_type probe_fetch_types[] = {
  73         /* Special types */
  74         __ASSIGN_FETCH_TYPE("string", string, string, sizeof(u32), 1,
  75                             "__data_loc char[]"),
  76         /* Basic types */
  77         ASSIGN_FETCH_TYPE(u8,  u8,  0),
  78         ASSIGN_FETCH_TYPE(u16, u16, 0),
  79         ASSIGN_FETCH_TYPE(u32, u32, 0),
  80         ASSIGN_FETCH_TYPE(u64, u64, 0),
  81         ASSIGN_FETCH_TYPE(s8,  u8,  1),
  82         ASSIGN_FETCH_TYPE(s16, u16, 1),
  83         ASSIGN_FETCH_TYPE(s32, u32, 1),
  84         ASSIGN_FETCH_TYPE(s64, u64, 1),
  85         ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
  86         ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
  87         ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
  88         ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
  89         ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0),
  90
  91         ASSIGN_FETCH_TYPE_END
  92 };
  93
  94 static const struct fetch_type *find_fetch_type(const char *type)
  95 {
  96         int i;
  97
  98         if (!type)
  99                 type = DEFAULT_FETCH_TYPE_STR;
 100
 101         /* Special case: bitfield */
 102         if (*type == 'b') {
 103                 unsigned long bs;
 104
 105                 type = strchr(type, '/');
 106                 if (!type)
 107                         goto fail;
 108
 109                 type++;
 110                 if (kstrtoul(type, 0, &bs))
 111                         goto fail;
 112
 113                 switch (bs) {
 114                 case 8:
 115                         return find_fetch_type("u8");
 116                 case 16:
 117                         return find_fetch_type("u16");
 118                 case 32:
 119                         return find_fetch_type("u32");
 120                 case 64:
 121                         return find_fetch_type("u64");
 122                 default:
 123                         goto fail;
 124                 }
 125         }
 126
 127         for (i = 0; probe_fetch_types[i].name; i++) {
 128                 if (strcmp(type, probe_fetch_types[i].name) == 0)
 129                         return &probe_fetch_types[i];
 130         }
 131
 132 fail:
 133         return NULL;
 134 }
 135
 136 /* Split symbol and offset. */
 137 int traceprobe_split_symbol_offset(char *symbol, long *offset)
 138 {
 139         char *tmp;
 140         int ret;
 141
 142         if (!offset)
 143                 return -EINVAL;
 144
 145         tmp = strpbrk(symbol, "+-");
 146         if (tmp) {
 147                 ret = kstrtol(tmp, 0, offset);
 148                 if (ret)
 149                         return ret;
 150                 *tmp = '\0';
 151         } else
 152                 *offset = 0;
 153
 154         return 0;
 155 }
 156
 157 /* @buf must has MAX_EVENT_NAME_LEN size */
 158 int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 159                                 char *buf)
 160 {
 161         const char *slash, *event = *pevent;
 162         int len;
 163
 164         slash = strchr(event, '/');
 165         if (slash) {
 166                 if (slash == event) {
 167                         pr_info("Group name is not specified\n");
 168                         return -EINVAL;
 169                 }
 170                 if (slash - event + 1 > MAX_EVENT_NAME_LEN) {
 171                         pr_info("Group name is too long\n");
 172                         return -E2BIG;
 173                 }
 174                 strlcpy(buf, event, slash - event + 1);
 175                 if (!is_good_name(buf)) {
 176                         pr_info("Group name must follow the same rules as C identifiers\n");
 177                         return -EINVAL;
 178                 }
 179                 *pgroup = buf;
 180                 *pevent = slash + 1;
 181                 event = *pevent;
 182         }
 183         len = strlen(event);
 184         if (len == 0) {
 185                 pr_info("Event name is not specified\n");
 186                 return -EINVAL;
 187         } else if (len > MAX_EVENT_NAME_LEN) {
 188                 pr_info("Event name is too long\n");
 189                 return -E2BIG;
 190         }
 191         if (!is_good_name(event)) {
 192                 pr_info("Event name must follow the same rules as C identifiers\n");
 193                 return -EINVAL;
 194         }
 195         return 0;
 196 }
 197
 198 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 199
 200 static int parse_probe_vars(char *arg, const struct fetch_type *t,
 201                             struct fetch_insn *code, unsigned int flags)
 202 {
 203         unsigned long param;
 204         int ret = 0;
 205         int len;
 206
 207         if (strcmp(arg, "retval") == 0) {
 208                 if (flags & TPARG_FL_RETURN)
 209                         code->op = FETCH_OP_RETVAL;
 210                 else
 211                         ret = -EINVAL;
 212         } else if ((len = str_has_prefix(arg, "stack"))) {
 213                 if (arg[len] == '\0') {
 214                         code->op = FETCH_OP_STACKP;
 215                 } else if (isdigit(arg[len])) {
 216                         ret = kstrtoul(arg + len, 10, &param);
 217                         if (ret || ((flags & TPARG_FL_KERNEL) &&
 218                                     param > PARAM_MAX_STACK))
 219                                 ret = -EINVAL;
 220                         else {
 221                                 code->op = FETCH_OP_STACK;
 222                                 code->param = (unsigned int)param;
 223                         }
 224                 } else
 225                         ret = -EINVAL;
 226         } else if (strcmp(arg, "comm") == 0) {
 227                 code->op = FETCH_OP_COMM;
 228 #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
 229         } else if (((flags & TPARG_FL_MASK) ==
 230                     (TPARG_FL_KERNEL | TPARG_FL_FENTRY)) &&
 231                    (len = str_has_prefix(arg, "arg"))) {
 232                 if (!isdigit(arg[len]))
 233                         return -EINVAL;
 234                 ret = kstrtoul(arg + len, 10, &param);
 235                 if (ret || !param || param > PARAM_MAX_STACK)
 236                         return -EINVAL;
 237                 code->op = FETCH_OP_ARG;
 238                 code->param = (unsigned int)param - 1;
 239 #endif
 240         } else
 241                 ret = -EINVAL;
 242
 243         return ret;
 244 }
 245
 246 /* Recursive argument parser */
 247 static int
 248 parse_probe_arg(char *arg, const struct fetch_type *type,
 249                 struct fetch_insn **pcode, struct fetch_insn *end,
 250                 unsigned int flags)
 251 {
 252         struct fetch_insn *code = *pcode;
 253         unsigned long param;
 254         long offset = 0;
 255         char *tmp;
 256         int ret = 0;
 257
 258         switch (arg[0]) {
 259         case '$':
 260                 ret = parse_probe_vars(arg + 1, type, code, flags);
 261                 break;
 262
 263         case '%':       /* named register */
 264                 ret = regs_query_register_offset(arg + 1);
 265                 if (ret >= 0) {
 266                         code->op = FETCH_OP_REG;
 267                         code->param = (unsigned int)ret;
 268                         ret = 0;
 269                 }
 270                 break;
 271
 272         case '@':       /* memory, file-offset or symbol */
 273                 if (isdigit(arg[1])) {
 274                         ret = kstrtoul(arg + 1, 0, &param);
 275                         if (ret)
 276                                 break;
 277                         /* load address */
 278                         code->op = FETCH_OP_IMM;
 279                         code->immediate = param;
 280                 } else if (arg[1] == '+') {
 281                         /* kprobes don't support file offsets */
 282                         if (flags & TPARG_FL_KERNEL)
 283                                 return -EINVAL;
 284
 285                         ret = kstrtol(arg + 2, 0, &offset);
 286                         if (ret)
 287                                 break;
 288
 289                         code->op = FETCH_OP_FOFFS;
 290                         code->immediate = (unsigned long)offset;  // imm64?
 291                 } else {
 292                         /* uprobes don't support symbols */
 293                         if (!(flags & TPARG_FL_KERNEL))
 294                                 return -EINVAL;
 295
 296                         /* Preserve symbol for updating */
 297                         code->op = FETCH_NOP_SYMBOL;
 298                         code->data = kstrdup(arg + 1, GFP_KERNEL);
 299                         if (!code->data)
 300                                 return -ENOMEM;
 301                         if (++code == end)
 302                                 return -E2BIG;
 303
 304                         code->op = FETCH_OP_IMM;
 305                         code->immediate = 0;
 306                 }
 307                 /* These are fetching from memory */
 308                 if (++code == end)
 309                         return -E2BIG;
 310                 *pcode = code;
 311                 code->op = FETCH_OP_DEREF;
 312                 code->offset = offset;
 313                 break;
 314
 315         case '+':       /* deref memory */
 316                 arg++;  /* Skip '+', because kstrtol() rejects it. */
 317                 /* fall through */
 318         case '-':
 319                 tmp = strchr(arg, '(');
 320                 if (!tmp)
 321                         return -EINVAL;
 322
 323                 *tmp = '\0';
 324                 ret = kstrtol(arg, 0, &offset);
 325                 if (ret)
 326                         break;
 327
 328                 arg = tmp + 1;
 329                 tmp = strrchr(arg, ')');
 330
 331                 if (tmp) {
 332                         const struct fetch_type *t2 = find_fetch_type(NULL);
 333
 334                         *tmp = '\0';
 335                         ret = parse_probe_arg(arg, t2, &code, end, flags);
 336                         if (ret)
 337                                 break;
 338                         if (code->op == FETCH_OP_COMM)
 339                                 return -EINVAL;
 340                         if (++code == end)
 341                                 return -E2BIG;
 342                         *pcode = code;
 343
 344                         code->op = FETCH_OP_DEREF;
 345                         code->offset = offset;
 346                 }
 347                 break;
 348         }
 349         if (!ret && code->op == FETCH_OP_NOP) {
 350                 /* Parsed, but do not find fetch method */
 351                 ret = -EINVAL;
 352         }
 353         return ret;
 354 }
 355
 356 #define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))
 357
 358 /* Bitfield type needs to be parsed into a fetch function */
 359 static int __parse_bitfield_probe_arg(const char *bf,
 360                                       const struct fetch_type *t,
 361                                       struct fetch_insn **pcode)
 362 {
 363         struct fetch_insn *code = *pcode;
 364         unsigned long bw, bo;
 365         char *tail;
 366
 367         if (*bf != 'b')
 368                 return 0;
 369
 370         bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */
 371
 372         if (bw == 0 || *tail != '@')
 373                 return -EINVAL;
 374
 375         bf = tail + 1;
 376         bo = simple_strtoul(bf, &tail, 0);
 377
 378         if (tail == bf || *tail != '/')
 379                 return -EINVAL;
 380         code++;
 381         if (code->op != FETCH_OP_NOP)
 382                 return -E2BIG;
 383         *pcode = code;
 384
 385         code->op = FETCH_OP_MOD_BF;
 386         code->lshift = BYTES_TO_BITS(t->size) - (bw + bo);
 387         code->rshift = BYTES_TO_BITS(t->size) - bw;
 388         code->basesize = t->size;
 389
 390         return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
 391 }
 392
 393 /* String length checking wrapper */
 394 static int traceprobe_parse_probe_arg_body(char *arg, ssize_t *size,
 395                 struct probe_arg *parg, unsigned int flags)
 396 {
 397         struct fetch_insn *code, *scode, *tmp = NULL;
 398         char *t, *t2;
 399         int ret, len;
 400
 401         if (strlen(arg) > MAX_ARGSTR_LEN) {
 402                 pr_info("Argument is too long.: %s\n",  arg);
 403                 return -ENOSPC;
 404         }
 405         parg->comm = kstrdup(arg, GFP_KERNEL);
 406         if (!parg->comm) {
 407                 pr_info("Failed to allocate memory for command '%s'.\n", arg);
 408                 return -ENOMEM;
 409         }
 410         t = strchr(arg, ':');
 411         if (t) {
 412                 *t = '\0';
 413                 t2 = strchr(++t, '[');
 414                 if (t2) {
 415                         *t2 = '\0';
 416                         parg->count = simple_strtoul(t2 + 1, &t2, 0);
 417                         if (strcmp(t2, "]") || parg->count == 0)
 418                                 return -EINVAL;
 419                         if (parg->count > MAX_ARRAY_LEN)
 420                                 return -E2BIG;
 421                 }
 422         }
 423         /*
 424          * The default type of $comm should be "string", and it can't be
 425          * dereferenced.
 426          */
 427         if (!t && strcmp(arg, "$comm") == 0)
 428                 parg->type = find_fetch_type("string");
 429         else
 430                 parg->type = find_fetch_type(t);
 431         if (!parg->type) {
 432                 pr_info("Unsupported type: %s\n", t);
 433                 return -EINVAL;
 434         }
 435         parg->offset = *size;
 436         *size += parg->type->size * (parg->count ?: 1);
 437
 438         if (parg->count) {
 439                 len = strlen(parg->type->fmttype) + 6;
 440                 parg->fmt = kmalloc(len, GFP_KERNEL);
 441                 if (!parg->fmt)
 442                         return -ENOMEM;
 443                 snprintf(parg->fmt, len, "%s[%d]", parg->type->fmttype,
 444                          parg->count);
 445         }
 446
 447         code = tmp = kzalloc(sizeof(*code) * FETCH_INSN_MAX, GFP_KERNEL);
 448         if (!code)
 449                 return -ENOMEM;
 450         code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;
 451
 452         ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
 453                               flags);
 454         if (ret)
 455                 goto fail;
 456
 457         /* Store operation */
 458         if (!strcmp(parg->type->name, "string")) {
 459                 if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_IMM &&
 460                     code->op != FETCH_OP_COMM) {
 461                         pr_info("string only accepts memory or address.\n");
 462                         ret = -EINVAL;
 463                         goto fail;
 464                 }
 465                 if (code->op != FETCH_OP_DEREF || parg->count) {
 466                         /*
 467                          * IMM and COMM is pointing actual address, those must
 468                          * be kept, and if parg->count != 0, this is an array
 469                          * of string pointers instead of string address itself.
 470                          */
 471                         code++;
 472                         if (code->op != FETCH_OP_NOP) {
 473                                 ret = -E2BIG;
 474                                 goto fail;
 475                         }
 476                 }
 477                 code->op = FETCH_OP_ST_STRING;  /* In DEREF case, replace it */
 478                 code->size = parg->type->size;
 479                 parg->dynamic = true;
 480         } else if (code->op == FETCH_OP_DEREF) {
 481                 code->op = FETCH_OP_ST_MEM;
 482                 code->size = parg->type->size;
 483         } else {
 484                 code++;
 485                 if (code->op != FETCH_OP_NOP) {
 486                         ret = -E2BIG;
 487                         goto fail;
 488                 }
 489                 code->op = FETCH_OP_ST_RAW;
 490                 code->size = parg->type->size;
 491         }
 492         scode = code;
 493         /* Modify operation */
 494         if (t != NULL) {
 495                 ret = __parse_bitfield_probe_arg(t, parg->type, &code);
 496                 if (ret)
 497                         goto fail;
 498         }
 499         /* Loop(Array) operation */
 500         if (parg->count) {
 501                 if (scode->op != FETCH_OP_ST_MEM &&
 502                     scode->op != FETCH_OP_ST_STRING) {
 503                         pr_info("array only accepts memory or address\n");
 504                         ret = -EINVAL;
 505                         goto fail;
 506                 }
 507                 code++;
 508                 if (code->op != FETCH_OP_NOP) {
 509                         ret = -E2BIG;
 510                         goto fail;
 511                 }
 512                 code->op = FETCH_OP_LP_ARRAY;
 513                 code->param = parg->count;
 514         }
 515         code++;
 516         code->op = FETCH_OP_END;
 517
 518         /* Shrink down the code buffer */
 519         parg->code = kzalloc(sizeof(*code) * (code - tmp + 1), GFP_KERNEL);
 520         if (!parg->code)
 521                 ret = -ENOMEM;
 522         else
 523                 memcpy(parg->code, tmp, sizeof(*code) * (code - tmp + 1));
 524
 525 fail:
 526         if (ret) {
 527                 for (code = tmp; code < tmp + FETCH_INSN_MAX; code++)
 528                         if (code->op == FETCH_NOP_SYMBOL)
 529                                 kfree(code->data);
 530         }
 531         kfree(tmp);
 532
 533         return ret;
 534 }
 535
 536 /* Return 1 if name is reserved or already used by another argument */
 537 static int traceprobe_conflict_field_name(const char *name,
 538                                           struct probe_arg *args, int narg)
 539 {
 540         int i;
 541
 542         for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
 543                 if (strcmp(reserved_field_names[i], name) == 0)
 544                         return 1;
 545
 546         for (i = 0; i < narg; i++)
 547                 if (strcmp(args[i].name, name) == 0)
 548                         return 1;
 549
 550         return 0;
 551 }
 552
 553 int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, char *arg,
 554                                 unsigned int flags)
 555 {
 556         struct probe_arg *parg = &tp->args[i];
 557         char *body;
 558         int ret;
 559
 560         /* Increment count for freeing args in error case */
 561         tp->nr_args++;
 562
 563         body = strchr(arg, '=');
 564         if (body) {
 565                 if (body - arg > MAX_ARG_NAME_LEN || body == arg)
 566                         return -EINVAL;
 567                 parg->name = kmemdup_nul(arg, body - arg, GFP_KERNEL);
 568                 body++;
 569         } else {
 570                 /* If argument name is omitted, set "argN" */
 571                 parg->name = kasprintf(GFP_KERNEL, "arg%d", i + 1);
 572                 body = arg;
 573         }
 574         if (!parg->name)
 575                 return -ENOMEM;
 576
 577         if (!is_good_name(parg->name)) {
 578                 pr_info("Invalid argument[%d] name: %s\n",
 579                         i, parg->name);
 580                 return -EINVAL;
 581         }
 582
 583         if (traceprobe_conflict_field_name(parg->name, tp->args, i)) {
 584                 pr_info("Argument[%d]: '%s' conflicts with another field.\n",
 585                         i, parg->name);
 586                 return -EINVAL;
 587         }
 588
 589         /* Parse fetch argument */
 590         ret = traceprobe_parse_probe_arg_body(body, &tp->size, parg, flags);
 591         if (ret)
 592                 pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 593         return ret;
 594 }
 595
 596 void traceprobe_free_probe_arg(struct probe_arg *arg)
 597 {
 598         struct fetch_insn *code = arg->code;
 599
 600         while (code && code->op != FETCH_OP_END) {
 601                 if (code->op == FETCH_NOP_SYMBOL)
 602                         kfree(code->data);
 603                 code++;
 604         }
 605         kfree(arg->code);
 606         kfree(arg->name);
 607         kfree(arg->comm);
 608         kfree(arg->fmt);
 609 }
 610
 611 int traceprobe_update_arg(struct probe_arg *arg)
 612 {
 613         struct fetch_insn *code = arg->code;
 614         long offset;
 615         char *tmp;
 616         char c;
 617         int ret = 0;
 618
 619         while (code && code->op != FETCH_OP_END) {
 620                 if (code->op == FETCH_NOP_SYMBOL) {
 621                         if (code[1].op != FETCH_OP_IMM)
 622                                 return -EINVAL;
 623
 624                         tmp = strpbrk(code->data, "+-");
 625                         if (tmp)
 626                                 c = *tmp;
 627                         ret = traceprobe_split_symbol_offset(code->data,
 628                                                              &offset);
 629                         if (ret)
 630                                 return ret;
 631
 632                         code[1].immediate =
 633                                 (unsigned long)kallsyms_lookup_name(code->data);
 634                         if (tmp)
 635                                 *tmp = c;
 636                         if (!code[1].immediate)
 637                                 return -ENOENT;
 638                         code[1].immediate += offset;
 639                 }
 640                 code++;
 641         }
 642         return 0;
 643 }
 644
 645 /* When len=0, we just calculate the needed length */
 646 #define LEN_OR_ZERO (len ? len - pos : 0)
 647 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 648                            bool is_return)
 649 {
 650         struct probe_arg *parg;
 651         int i, j;
 652         int pos = 0;
 653         const char *fmt, *arg;
 654
 655         if (!is_return) {
 656                 fmt = "(%lx)";
 657                 arg = "REC->" FIELD_STRING_IP;
 658         } else {
 659                 fmt = "(%lx <- %lx)";
 660                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
 661         }
 662
 663         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
 664
 665         for (i = 0; i < tp->nr_args; i++) {
 666                 parg = tp->args + i;
 667                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=", parg->name);
 668                 if (parg->count) {
 669                         pos += snprintf(buf + pos, LEN_OR_ZERO, "{%s",
 670                                         parg->type->fmt);
 671                         for (j = 1; j < parg->count; j++)
 672                                 pos += snprintf(buf + pos, LEN_OR_ZERO, ",%s",
 673                                                 parg->type->fmt);
 674                         pos += snprintf(buf + pos, LEN_OR_ZERO, "}");
 675                 } else
 676                         pos += snprintf(buf + pos, LEN_OR_ZERO, "%s",
 677                                         parg->type->fmt);
 678         }
 679
 680         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 681
 682         for (i = 0; i < tp->nr_args; i++) {
 683                 parg = tp->args + i;
 684                 if (parg->count) {
 685                         if (strcmp(parg->type->name, "string") == 0)
 686                                 fmt = ", __get_str(%s[%d])";
 687                         else
 688                                 fmt = ", REC->%s[%d]";
 689                         for (j = 0; j < parg->count; j++)
 690                                 pos += snprintf(buf + pos, LEN_OR_ZERO,
 691                                                 fmt, parg->name, j);
 692                 } else {
 693                         if (strcmp(parg->type->name, "string") == 0)
 694                                 fmt = ", __get_str(%s)";
 695                         else
 696                                 fmt = ", REC->%s";
 697                         pos += snprintf(buf + pos, LEN_OR_ZERO,
 698                                         fmt, parg->name);
 699                 }
 700         }
 701
 702         /* return the length of print_fmt */
 703         return pos;
 704 }
 705 #undef LEN_OR_ZERO
 706
 707 int traceprobe_set_print_fmt(struct trace_probe *tp, bool is_return)
 708 {
 709         int len;
 710         char *print_fmt;
 711
 712         /* First: called with 0 length to calculate the needed length */
 713         len = __set_print_fmt(tp, NULL, 0, is_return);
 714         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 715         if (!print_fmt)
 716                 return -ENOMEM;
 717
 718         /* Second: actually write the @print_fmt */
 719         __set_print_fmt(tp, print_fmt, len + 1, is_return);
 720         tp->call.print_fmt = print_fmt;
 721
 722         return 0;
 723 }
 724
 725 int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 726                                  size_t offset, struct trace_probe *tp)
 727 {
 728         int ret, i;
 729
 730         /* Set argument names as fields */
 731         for (i = 0; i < tp->nr_args; i++) {
 732                 struct probe_arg *parg = &tp->args[i];
 733                 const char *fmt = parg->type->fmttype;
 734                 int size = parg->type->size;
 735
 736                 if (parg->fmt)
 737                         fmt = parg->fmt;
 738                 if (parg->count)
 739                         size *= parg->count;
 740                 ret = trace_define_field(event_call, fmt, parg->name,
 741                                          offset + parg->offset, size,
 742                                          parg->type->is_signed,
 743                                          FILTER_OTHER);
 744                 if (ret)
 745                         return ret;
 746         }
 747         return 0;
 748 }