kernel/trace/trace_probe.c

   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 <[email protected]>
  19  *
  20  * Updates to make this generic:
  21  * Copyright (C) IBM Corporation, 2010-2011
  22  * Author:     Srikar Dronamraju
  23  */
  24 #define pr_fmt(fmt)     "trace_probe: " fmt
  25
  26 #include "trace_probe.h"
  27
  28 const char *reserved_field_names[] = {
  29         "common_type",
  30         "common_flags",
  31         "common_preempt_count",
  32         "common_pid",
  33         "common_tgid",
  34         FIELD_STRING_IP,
  35         FIELD_STRING_RETIP,
  36         FIELD_STRING_FUNC,
  37 };
  38
  39 /* Printing  in basic type function template */
  40 #define DEFINE_BASIC_PRINT_TYPE_FUNC(tname, type, fmt)                  \
  41 int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, const char *name,  \
  42                                 void *data, void *ent)                  \
  43 {                                                                       \
  44         trace_seq_printf(s, " %s=" fmt, name, *(type *)data);           \
  45         return !trace_seq_has_overflowed(s);                            \
  46 }                                                                       \
  47 const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;                          \
  48 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(tname));
  49
  50 DEFINE_BASIC_PRINT_TYPE_FUNC(u8,  u8,  "%u")
  51 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
  52 DEFINE_BASIC_PRINT_TYPE_FUNC(u32, u32, "%u")
  53 DEFINE_BASIC_PRINT_TYPE_FUNC(u64, u64, "%Lu")
  54 DEFINE_BASIC_PRINT_TYPE_FUNC(s8,  s8,  "%d")
  55 DEFINE_BASIC_PRINT_TYPE_FUNC(s16, s16, "%d")
  56 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, s32, "%d")
  57 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, s64, "%Ld")
  58 DEFINE_BASIC_PRINT_TYPE_FUNC(x8,  u8,  "0x%x")
  59 DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
  60 DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
  61 DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
  62
  63 /* Print type function for string type */
  64 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name,
  65                                  void *data, void *ent)
  66 {
  67         int len = *(u32 *)data >> 16;
  68
  69         if (!len)
  70                 trace_seq_printf(s, " %s=(fault)", name);
  71         else
  72                 trace_seq_printf(s, " %s=\"%s\"", name,
  73                                  (const char *)get_loc_data(data, ent));
  74         return !trace_seq_has_overflowed(s);
  75 }
  76 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string));
  77
  78 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
  79
  80 #define CHECK_FETCH_FUNCS(method, fn)                   \
  81         (((FETCH_FUNC_NAME(method, u8) == fn) ||        \
  82           (FETCH_FUNC_NAME(method, u16) == fn) ||       \
  83           (FETCH_FUNC_NAME(method, u32) == fn) ||       \
  84           (FETCH_FUNC_NAME(method, u64) == fn) ||       \
  85           (FETCH_FUNC_NAME(method, string) == fn) ||    \
  86           (FETCH_FUNC_NAME(method, string_size) == fn)) \
  87          && (fn != NULL))
  88
  89 /* Data fetch function templates */
  90 #define DEFINE_FETCH_reg(type)                                          \
  91 void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, void *offset, void *dest) \
  92 {                                                                       \
  93         *(type *)dest = (type)regs_get_register(regs,                   \
  94                                 (unsigned int)((unsigned long)offset)); \
  95 }                                                                       \
  96 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type));
  97 DEFINE_BASIC_FETCH_FUNCS(reg)
  98 /* No string on the register */
  99 #define fetch_reg_string        NULL
 100 #define fetch_reg_string_size   NULL
 101
 102 #define DEFINE_FETCH_retval(type)                                       \
 103 void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,                \
 104                                    void *dummy, void *dest)             \
 105 {                                                                       \
 106         *(type *)dest = (type)regs_return_value(regs);                  \
 107 }                                                                       \
 108 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type));
 109 DEFINE_BASIC_FETCH_FUNCS(retval)
 110 /* No string on the retval */
 111 #define fetch_retval_string             NULL
 112 #define fetch_retval_string_size        NULL
 113
 114 /* Dereference memory access function */
 115 struct deref_fetch_param {
 116         struct fetch_param      orig;
 117         long                    offset;
 118         fetch_func_t            fetch;
 119         fetch_func_t            fetch_size;
 120 };
 121
 122 #define DEFINE_FETCH_deref(type)                                        \
 123 void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,                 \
 124                                   void *data, void *dest)               \
 125 {                                                                       \
 126         struct deref_fetch_param *dprm = data;                          \
 127         unsigned long addr;                                             \
 128         call_fetch(&dprm->orig, regs, &addr);                           \
 129         if (addr) {                                                     \
 130                 addr += dprm->offset;                                   \
 131                 dprm->fetch(regs, (void *)addr, dest);                  \
 132         } else                                                          \
 133                 *(type *)dest = 0;                                      \
 134 }                                                                       \
 135 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type));
 136 DEFINE_BASIC_FETCH_FUNCS(deref)
 137 DEFINE_FETCH_deref(string)
 138
 139 void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
 140                                          void *data, void *dest)
 141 {
 142         struct deref_fetch_param *dprm = data;
 143         unsigned long addr;
 144
 145         call_fetch(&dprm->orig, regs, &addr);
 146         if (addr && dprm->fetch_size) {
 147                 addr += dprm->offset;
 148                 dprm->fetch_size(regs, (void *)addr, dest);
 149         } else
 150                 *(string_size *)dest = 0;
 151 }
 152 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size));
 153
 154 static void update_deref_fetch_param(struct deref_fetch_param *data)
 155 {
 156         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 157                 update_deref_fetch_param(data->orig.data);
 158         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 159                 update_symbol_cache(data->orig.data);
 160 }
 161 NOKPROBE_SYMBOL(update_deref_fetch_param);
 162
 163 static void free_deref_fetch_param(struct deref_fetch_param *data)
 164 {
 165         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 166                 free_deref_fetch_param(data->orig.data);
 167         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 168                 free_symbol_cache(data->orig.data);
 169         kfree(data);
 170 }
 171 NOKPROBE_SYMBOL(free_deref_fetch_param);
 172
 173 /* Bitfield fetch function */
 174 struct bitfield_fetch_param {
 175         struct fetch_param      orig;
 176         unsigned char           hi_shift;
 177         unsigned char           low_shift;
 178 };
 179
 180 #define DEFINE_FETCH_bitfield(type)                                     \
 181 void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs,              \
 182                                      void *data, void *dest)            \
 183 {                                                                       \
 184         struct bitfield_fetch_param *bprm = data;                       \
 185         type buf = 0;                                                   \
 186         call_fetch(&bprm->orig, regs, &buf);                            \
 187         if (buf) {                                                      \
 188                 buf <<= bprm->hi_shift;                                 \
 189                 buf >>= bprm->low_shift;                                \
 190         }                                                               \
 191         *(type *)dest = buf;                                            \
 192 }                                                                       \
 193 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type));
 194 DEFINE_BASIC_FETCH_FUNCS(bitfield)
 195 #define fetch_bitfield_string           NULL
 196 #define fetch_bitfield_string_size      NULL
 197
 198 static void
 199 update_bitfield_fetch_param(struct bitfield_fetch_param *data)
 200 {
 201         /*
 202          * Don't check the bitfield itself, because this must be the
 203          * last fetch function.
 204          */
 205         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 206                 update_deref_fetch_param(data->orig.data);
 207         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 208                 update_symbol_cache(data->orig.data);
 209 }
 210
 211 static void
 212 free_bitfield_fetch_param(struct bitfield_fetch_param *data)
 213 {
 214         /*
 215          * Don't check the bitfield itself, because this must be the
 216          * last fetch function.
 217          */
 218         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 219                 free_deref_fetch_param(data->orig.data);
 220         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 221                 free_symbol_cache(data->orig.data);
 222
 223         kfree(data);
 224 }
 225
 226 void FETCH_FUNC_NAME(comm, string)(struct pt_regs *regs,
 227                                           void *data, void *dest)
 228 {
 229         int maxlen = get_rloc_len(*(u32 *)dest);
 230         u8 *dst = get_rloc_data(dest);
 231         long ret;
 232
 233         if (!maxlen)
 234                 return;
 235
 236         ret = strlcpy(dst, current->comm, maxlen);
 237         *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
 238 }
 239 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string));
 240
 241 void FETCH_FUNC_NAME(comm, string_size)(struct pt_regs *regs,
 242                                                void *data, void *dest)
 243 {
 244         *(u32 *)dest = strlen(current->comm) + 1;
 245 }
 246 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string_size));
 247
 248 static const struct fetch_type *find_fetch_type(const char *type,
 249                                                 const struct fetch_type *ftbl)
 250 {
 251         int i;
 252
 253         if (!type)
 254                 type = DEFAULT_FETCH_TYPE_STR;
 255
 256         /* Special case: bitfield */
 257         if (*type == 'b') {
 258                 unsigned long bs;
 259
 260                 type = strchr(type, '/');
 261                 if (!type)
 262                         goto fail;
 263
 264                 type++;
 265                 if (kstrtoul(type, 0, &bs))
 266                         goto fail;
 267
 268                 switch (bs) {
 269                 case 8:
 270                         return find_fetch_type("u8", ftbl);
 271                 case 16:
 272                         return find_fetch_type("u16", ftbl);
 273                 case 32:
 274                         return find_fetch_type("u32", ftbl);
 275                 case 64:
 276                         return find_fetch_type("u64", ftbl);
 277                 default:
 278                         goto fail;
 279                 }
 280         }
 281
 282         for (i = 0; ftbl[i].name; i++) {
 283                 if (strcmp(type, ftbl[i].name) == 0)
 284                         return &ftbl[i];
 285         }
 286
 287 fail:
 288         return NULL;
 289 }
 290
 291 /* Special function : only accept unsigned long */
 292 static void fetch_kernel_stack_address(struct pt_regs *regs, void *dummy, void *dest)
 293 {
 294         *(unsigned long *)dest = kernel_stack_pointer(regs);
 295 }
 296 NOKPROBE_SYMBOL(fetch_kernel_stack_address);
 297
 298 static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *dest)
 299 {
 300         *(unsigned long *)dest = user_stack_pointer(regs);
 301 }
 302 NOKPROBE_SYMBOL(fetch_user_stack_address);
 303
 304 static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
 305                                             fetch_func_t orig_fn,
 306                                             const struct fetch_type *ftbl)
 307 {
 308         int i;
 309
 310         if (type != &ftbl[FETCH_TYPE_STRING])
 311                 return NULL;    /* Only string type needs size function */
 312
 313         for (i = 0; i < FETCH_MTD_END; i++)
 314                 if (type->fetch[i] == orig_fn)
 315                         return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
 316
 317         WARN_ON(1);     /* This should not happen */
 318
 319         return NULL;
 320 }
 321
 322 /* Split symbol and offset. */
 323 int traceprobe_split_symbol_offset(char *symbol, long *offset)
 324 {
 325         char *tmp;
 326         int ret;
 327
 328         if (!offset)
 329                 return -EINVAL;
 330
 331         tmp = strpbrk(symbol, "+-");
 332         if (tmp) {
 333                 ret = kstrtol(tmp, 0, offset);
 334                 if (ret)
 335                         return ret;
 336                 *tmp = '\0';
 337         } else
 338                 *offset = 0;
 339
 340         return 0;
 341 }
 342
 343 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 344
 345 static int parse_probe_vars(char *arg, const struct fetch_type *t,
 346                             struct fetch_param *f, bool is_return,
 347                             bool is_kprobe)
 348 {
 349         int ret = 0;
 350         unsigned long param;
 351
 352         if (strcmp(arg, "retval") == 0) {
 353                 if (is_return)
 354                         f->fn = t->fetch[FETCH_MTD_retval];
 355                 else
 356                         ret = -EINVAL;
 357         } else if (strncmp(arg, "stack", 5) == 0) {
 358                 if (arg[5] == '\0') {
 359                         if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
 360                                 return -EINVAL;
 361
 362                         if (is_kprobe)
 363                                 f->fn = fetch_kernel_stack_address;
 364                         else
 365                                 f->fn = fetch_user_stack_address;
 366                 } else if (isdigit(arg[5])) {
 367                         ret = kstrtoul(arg + 5, 10, &param);
 368                         if (ret || (is_kprobe && param > PARAM_MAX_STACK))
 369                                 ret = -EINVAL;
 370                         else {
 371                                 f->fn = t->fetch[FETCH_MTD_stack];
 372                                 f->data = (void *)param;
 373                         }
 374                 } else
 375                         ret = -EINVAL;
 376         } else if (strcmp(arg, "comm") == 0) {
 377                 if (strcmp(t->name, "string") != 0 &&
 378                     strcmp(t->name, "string_size") != 0)
 379                         return -EINVAL;
 380                 f->fn = t->fetch[FETCH_MTD_comm];
 381         } else
 382                 ret = -EINVAL;
 383
 384         return ret;
 385 }
 386
 387 /* Recursive argument parser */
 388 static int parse_probe_arg(char *arg, const struct fetch_type *t,
 389                      struct fetch_param *f, bool is_return, bool is_kprobe,
 390                      const struct fetch_type *ftbl)
 391 {
 392         unsigned long param;
 393         long offset;
 394         char *tmp;
 395         int ret = 0;
 396
 397         switch (arg[0]) {
 398         case '$':
 399                 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
 400                 break;
 401
 402         case '%':       /* named register */
 403                 ret = regs_query_register_offset(arg + 1);
 404                 if (ret >= 0) {
 405                         f->fn = t->fetch[FETCH_MTD_reg];
 406                         f->data = (void *)(unsigned long)ret;
 407                         ret = 0;
 408                 }
 409                 break;
 410
 411         case '@':       /* memory, file-offset or symbol */
 412                 if (isdigit(arg[1])) {
 413                         ret = kstrtoul(arg + 1, 0, &param);
 414                         if (ret)
 415                                 break;
 416
 417                         f->fn = t->fetch[FETCH_MTD_memory];
 418                         f->data = (void *)param;
 419                 } else if (arg[1] == '+') {
 420                         /* kprobes don't support file offsets */
 421                         if (is_kprobe)
 422                                 return -EINVAL;
 423
 424                         ret = kstrtol(arg + 2, 0, &offset);
 425                         if (ret)
 426                                 break;
 427
 428                         f->fn = t->fetch[FETCH_MTD_file_offset];
 429                         f->data = (void *)offset;
 430                 } else {
 431                         /* uprobes don't support symbols */
 432                         if (!is_kprobe)
 433                                 return -EINVAL;
 434
 435                         ret = traceprobe_split_symbol_offset(arg + 1, &offset);
 436                         if (ret)
 437                                 break;
 438
 439                         f->data = alloc_symbol_cache(arg + 1, offset);
 440                         if (f->data)
 441                                 f->fn = t->fetch[FETCH_MTD_symbol];
 442                 }
 443                 break;
 444
 445         case '+':       /* deref memory */
 446                 arg++;  /* Skip '+', because kstrtol() rejects it. */
 447         case '-':
 448                 tmp = strchr(arg, '(');
 449                 if (!tmp)
 450                         break;
 451
 452                 *tmp = '\0';
 453                 ret = kstrtol(arg, 0, &offset);
 454
 455                 if (ret)
 456                         break;
 457
 458                 arg = tmp + 1;
 459                 tmp = strrchr(arg, ')');
 460
 461                 if (tmp) {
 462                         struct deref_fetch_param        *dprm;
 463                         const struct fetch_type         *t2;
 464
 465                         t2 = find_fetch_type(NULL, ftbl);
 466                         *tmp = '\0';
 467                         dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
 468
 469                         if (!dprm)
 470                                 return -ENOMEM;
 471
 472                         dprm->offset = offset;
 473                         dprm->fetch = t->fetch[FETCH_MTD_memory];
 474                         dprm->fetch_size = get_fetch_size_function(t,
 475                                                         dprm->fetch, ftbl);
 476                         ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
 477                                                         is_kprobe, ftbl);
 478                         if (ret)
 479                                 kfree(dprm);
 480                         else {
 481                                 f->fn = t->fetch[FETCH_MTD_deref];
 482                                 f->data = (void *)dprm;
 483                         }
 484                 }
 485                 break;
 486         }
 487         if (!ret && !f->fn) {   /* Parsed, but do not find fetch method */
 488                 pr_info("%s type has no corresponding fetch method.\n", t->name);
 489                 ret = -EINVAL;
 490         }
 491
 492         return ret;
 493 }
 494
 495 #define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))
 496
 497 /* Bitfield type needs to be parsed into a fetch function */
 498 static int __parse_bitfield_probe_arg(const char *bf,
 499                                       const struct fetch_type *t,
 500                                       struct fetch_param *f)
 501 {
 502         struct bitfield_fetch_param *bprm;
 503         unsigned long bw, bo;
 504         char *tail;
 505
 506         if (*bf != 'b')
 507                 return 0;
 508
 509         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
 510         if (!bprm)
 511                 return -ENOMEM;
 512
 513         bprm->orig = *f;
 514         f->fn = t->fetch[FETCH_MTD_bitfield];
 515         f->data = (void *)bprm;
 516         bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */
 517
 518         if (bw == 0 || *tail != '@')
 519                 return -EINVAL;
 520
 521         bf = tail + 1;
 522         bo = simple_strtoul(bf, &tail, 0);
 523
 524         if (tail == bf || *tail != '/')
 525                 return -EINVAL;
 526
 527         bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
 528         bprm->low_shift = bprm->hi_shift + bo;
 529
 530         return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
 531 }
 532
 533 /* String length checking wrapper */
 534 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 535                 struct probe_arg *parg, bool is_return, bool is_kprobe,
 536                 const struct fetch_type *ftbl)
 537 {
 538         const char *t;
 539         int ret;
 540
 541         if (strlen(arg) > MAX_ARGSTR_LEN) {
 542                 pr_info("Argument is too long.: %s\n",  arg);
 543                 return -ENOSPC;
 544         }
 545         parg->comm = kstrdup(arg, GFP_KERNEL);
 546         if (!parg->comm) {
 547                 pr_info("Failed to allocate memory for command '%s'.\n", arg);
 548                 return -ENOMEM;
 549         }
 550         t = strchr(parg->comm, ':');
 551         if (t) {
 552                 arg[t - parg->comm] = '\0';
 553                 t++;
 554         }
 555         /*
 556          * The default type of $comm should be "string", and it can't be
 557          * dereferenced.
 558          */
 559         if (!t && strcmp(arg, "$comm") == 0)
 560                 t = "string";
 561         parg->type = find_fetch_type(t, ftbl);
 562         if (!parg->type) {
 563                 pr_info("Unsupported type: %s\n", t);
 564                 return -EINVAL;
 565         }
 566         parg->offset = *size;
 567         *size += parg->type->size;
 568         ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
 569                               is_kprobe, ftbl);
 570
 571         if (ret >= 0 && t != NULL)
 572                 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
 573
 574         if (ret >= 0) {
 575                 parg->fetch_size.fn = get_fetch_size_function(parg->type,
 576                                                               parg->fetch.fn,
 577                                                               ftbl);
 578                 parg->fetch_size.data = parg->fetch.data;
 579         }
 580
 581         return ret;
 582 }
 583
 584 /* Return 1 if name is reserved or already used by another argument */
 585 int traceprobe_conflict_field_name(const char *name,
 586                                struct probe_arg *args, int narg)
 587 {
 588         int i;
 589
 590         for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
 591                 if (strcmp(reserved_field_names[i], name) == 0)
 592                         return 1;
 593
 594         for (i = 0; i < narg; i++)
 595                 if (strcmp(args[i].name, name) == 0)
 596                         return 1;
 597
 598         return 0;
 599 }
 600
 601 void traceprobe_update_arg(struct probe_arg *arg)
 602 {
 603         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 604                 update_bitfield_fetch_param(arg->fetch.data);
 605         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 606                 update_deref_fetch_param(arg->fetch.data);
 607         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 608                 update_symbol_cache(arg->fetch.data);
 609 }
 610
 611 void traceprobe_free_probe_arg(struct probe_arg *arg)
 612 {
 613         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 614                 free_bitfield_fetch_param(arg->fetch.data);
 615         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 616                 free_deref_fetch_param(arg->fetch.data);
 617         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 618                 free_symbol_cache(arg->fetch.data);
 619
 620         kfree(arg->name);
 621         kfree(arg->comm);
 622 }
 623
 624 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 625                            bool is_return)
 626 {
 627         int i;
 628         int pos = 0;
 629
 630         const char *fmt, *arg;
 631
 632         if (!is_return) {
 633                 fmt = "(%lx)";
 634                 arg = "REC->" FIELD_STRING_IP;
 635         } else {
 636                 fmt = "(%lx <- %lx)";
 637                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
 638         }
 639
 640         /* When len=0, we just calculate the needed length */
 641 #define LEN_OR_ZERO (len ? len - pos : 0)
 642
 643         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
 644
 645         for (i = 0; i < tp->nr_args; i++) {
 646                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
 647                                 tp->args[i].name, tp->args[i].type->fmt);
 648         }
 649
 650         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 651
 652         for (i = 0; i < tp->nr_args; i++) {
 653                 if (strcmp(tp->args[i].type->name, "string") == 0)
 654                         pos += snprintf(buf + pos, LEN_OR_ZERO,
 655                                         ", __get_str(%s)",
 656                                         tp->args[i].name);
 657                 else
 658                         pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
 659                                         tp->args[i].name);
 660         }
 661
 662 #undef LEN_OR_ZERO
 663
 664         /* return the length of print_fmt */
 665         return pos;
 666 }
 667
 668 int set_print_fmt(struct trace_probe *tp, bool is_return)
 669 {
 670         int len;
 671         char *print_fmt;
 672
 673         /* First: called with 0 length to calculate the needed length */
 674         len = __set_print_fmt(tp, NULL, 0, is_return);
 675         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 676         if (!print_fmt)
 677                 return -ENOMEM;
 678
 679         /* Second: actually write the @print_fmt */
 680         __set_print_fmt(tp, print_fmt, len + 1, is_return);
 681         tp->call.print_fmt = print_fmt;
 682
 683         return 0;
 684 }