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 <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 #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, unsigned long *offset)
 324 {
 325         char *tmp;
 326         int ret;
 327
 328         if (!offset)
 329                 return -EINVAL;
 330
 331         tmp = strchr(symbol, '+');
 332         if (tmp) {
 333                 /* skip sign because kstrtoul doesn't accept '+' */
 334                 ret = kstrtoul(tmp + 1, 0, offset);
 335                 if (ret)
 336                         return ret;
 337
 338                 *tmp = '\0';
 339         } else
 340                 *offset = 0;
 341
 342         return 0;
 343 }
 344
 345 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 346
 347 static int parse_probe_vars(char *arg, const struct fetch_type *t,
 348                             struct fetch_param *f, bool is_return,
 349                             bool is_kprobe)
 350 {
 351         int ret = 0;
 352         unsigned long param;
 353
 354         if (strcmp(arg, "retval") == 0) {
 355                 if (is_return)
 356                         f->fn = t->fetch[FETCH_MTD_retval];
 357                 else
 358                         ret = -EINVAL;
 359         } else if (strncmp(arg, "stack", 5) == 0) {
 360                 if (arg[5] == '\0') {
 361                         if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
 362                                 return -EINVAL;
 363
 364                         if (is_kprobe)
 365                                 f->fn = fetch_kernel_stack_address;
 366                         else
 367                                 f->fn = fetch_user_stack_address;
 368                 } else if (isdigit(arg[5])) {
 369                         ret = kstrtoul(arg + 5, 10, &param);
 370                         if (ret || (is_kprobe && param > PARAM_MAX_STACK))
 371                                 ret = -EINVAL;
 372                         else {
 373                                 f->fn = t->fetch[FETCH_MTD_stack];
 374                                 f->data = (void *)param;
 375                         }
 376                 } else
 377                         ret = -EINVAL;
 378         } else if (strcmp(arg, "comm") == 0) {
 379                 if (strcmp(t->name, "string") != 0 &&
 380                     strcmp(t->name, "string_size") != 0)
 381                         return -EINVAL;
 382                 f->fn = t->fetch[FETCH_MTD_comm];
 383         } else
 384                 ret = -EINVAL;
 385
 386         return ret;
 387 }
 388
 389 /* Recursive argument parser */
 390 static int parse_probe_arg(char *arg, const struct fetch_type *t,
 391                      struct fetch_param *f, bool is_return, bool is_kprobe,
 392                      const struct fetch_type *ftbl)
 393 {
 394         unsigned long param;
 395         long offset;
 396         char *tmp;
 397         int ret = 0;
 398
 399         switch (arg[0]) {
 400         case '$':
 401                 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
 402                 break;
 403
 404         case '%':       /* named register */
 405                 ret = regs_query_register_offset(arg + 1);
 406                 if (ret >= 0) {
 407                         f->fn = t->fetch[FETCH_MTD_reg];
 408                         f->data = (void *)(unsigned long)ret;
 409                         ret = 0;
 410                 }
 411                 break;
 412
 413         case '@':       /* memory, file-offset or symbol */
 414                 if (isdigit(arg[1])) {
 415                         ret = kstrtoul(arg + 1, 0, &param);
 416                         if (ret)
 417                                 break;
 418
 419                         f->fn = t->fetch[FETCH_MTD_memory];
 420                         f->data = (void *)param;
 421                 } else if (arg[1] == '+') {
 422                         /* kprobes don't support file offsets */
 423                         if (is_kprobe)
 424                                 return -EINVAL;
 425
 426                         ret = kstrtol(arg + 2, 0, &offset);
 427                         if (ret)
 428                                 break;
 429
 430                         f->fn = t->fetch[FETCH_MTD_file_offset];
 431                         f->data = (void *)offset;
 432                 } else {
 433                         /* uprobes don't support symbols */
 434                         if (!is_kprobe)
 435                                 return -EINVAL;
 436
 437                         ret = traceprobe_split_symbol_offset(arg + 1, &offset);
 438                         if (ret)
 439                                 break;
 440
 441                         f->data = alloc_symbol_cache(arg + 1, offset);
 442                         if (f->data)
 443                                 f->fn = t->fetch[FETCH_MTD_symbol];
 444                 }
 445                 break;
 446
 447         case '+':       /* deref memory */
 448                 arg++;  /* Skip '+', because kstrtol() rejects it. */
 449         case '-':
 450                 tmp = strchr(arg, '(');
 451                 if (!tmp)
 452                         break;
 453
 454                 *tmp = '\0';
 455                 ret = kstrtol(arg, 0, &offset);
 456
 457                 if (ret)
 458                         break;
 459
 460                 arg = tmp + 1;
 461                 tmp = strrchr(arg, ')');
 462
 463                 if (tmp) {
 464                         struct deref_fetch_param        *dprm;
 465                         const struct fetch_type         *t2;
 466
 467                         t2 = find_fetch_type(NULL, ftbl);
 468                         *tmp = '\0';
 469                         dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
 470
 471                         if (!dprm)
 472                                 return -ENOMEM;
 473
 474                         dprm->offset = offset;
 475                         dprm->fetch = t->fetch[FETCH_MTD_memory];
 476                         dprm->fetch_size = get_fetch_size_function(t,
 477                                                         dprm->fetch, ftbl);
 478                         ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
 479                                                         is_kprobe, ftbl);
 480                         if (ret)
 481                                 kfree(dprm);
 482                         else {
 483                                 f->fn = t->fetch[FETCH_MTD_deref];
 484                                 f->data = (void *)dprm;
 485                         }
 486                 }
 487                 break;
 488         }
 489         if (!ret && !f->fn) {   /* Parsed, but do not find fetch method */
 490                 pr_info("%s type has no corresponding fetch method.\n", t->name);
 491                 ret = -EINVAL;
 492         }
 493
 494         return ret;
 495 }
 496
 497 #define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))
 498
 499 /* Bitfield type needs to be parsed into a fetch function */
 500 static int __parse_bitfield_probe_arg(const char *bf,
 501                                       const struct fetch_type *t,
 502                                       struct fetch_param *f)
 503 {
 504         struct bitfield_fetch_param *bprm;
 505         unsigned long bw, bo;
 506         char *tail;
 507
 508         if (*bf != 'b')
 509                 return 0;
 510
 511         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
 512         if (!bprm)
 513                 return -ENOMEM;
 514
 515         bprm->orig = *f;
 516         f->fn = t->fetch[FETCH_MTD_bitfield];
 517         f->data = (void *)bprm;
 518         bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */
 519
 520         if (bw == 0 || *tail != '@')
 521                 return -EINVAL;
 522
 523         bf = tail + 1;
 524         bo = simple_strtoul(bf, &tail, 0);
 525
 526         if (tail == bf || *tail != '/')
 527                 return -EINVAL;
 528
 529         bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
 530         bprm->low_shift = bprm->hi_shift + bo;
 531
 532         return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
 533 }
 534
 535 /* String length checking wrapper */
 536 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 537                 struct probe_arg *parg, bool is_return, bool is_kprobe,
 538                 const struct fetch_type *ftbl)
 539 {
 540         const char *t;
 541         int ret;
 542
 543         if (strlen(arg) > MAX_ARGSTR_LEN) {
 544                 pr_info("Argument is too long.: %s\n",  arg);
 545                 return -ENOSPC;
 546         }
 547         parg->comm = kstrdup(arg, GFP_KERNEL);
 548         if (!parg->comm) {
 549                 pr_info("Failed to allocate memory for command '%s'.\n", arg);
 550                 return -ENOMEM;
 551         }
 552         t = strchr(parg->comm, ':');
 553         if (t) {
 554                 arg[t - parg->comm] = '\0';
 555                 t++;
 556         }
 557         /*
 558          * The default type of $comm should be "string", and it can't be
 559          * dereferenced.
 560          */
 561         if (!t && strcmp(arg, "$comm") == 0)
 562                 t = "string";
 563         parg->type = find_fetch_type(t, ftbl);
 564         if (!parg->type) {
 565                 pr_info("Unsupported type: %s\n", t);
 566                 return -EINVAL;
 567         }
 568         parg->offset = *size;
 569         *size += parg->type->size;
 570         ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
 571                               is_kprobe, ftbl);
 572
 573         if (ret >= 0 && t != NULL)
 574                 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
 575
 576         if (ret >= 0) {
 577                 parg->fetch_size.fn = get_fetch_size_function(parg->type,
 578                                                               parg->fetch.fn,
 579                                                               ftbl);
 580                 parg->fetch_size.data = parg->fetch.data;
 581         }
 582
 583         return ret;
 584 }
 585
 586 /* Return 1 if name is reserved or already used by another argument */
 587 int traceprobe_conflict_field_name(const char *name,
 588                                struct probe_arg *args, int narg)
 589 {
 590         int i;
 591
 592         for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
 593                 if (strcmp(reserved_field_names[i], name) == 0)
 594                         return 1;
 595
 596         for (i = 0; i < narg; i++)
 597                 if (strcmp(args[i].name, name) == 0)
 598                         return 1;
 599
 600         return 0;
 601 }
 602
 603 void traceprobe_update_arg(struct probe_arg *arg)
 604 {
 605         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 606                 update_bitfield_fetch_param(arg->fetch.data);
 607         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 608                 update_deref_fetch_param(arg->fetch.data);
 609         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 610                 update_symbol_cache(arg->fetch.data);
 611 }
 612
 613 void traceprobe_free_probe_arg(struct probe_arg *arg)
 614 {
 615         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 616                 free_bitfield_fetch_param(arg->fetch.data);
 617         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 618                 free_deref_fetch_param(arg->fetch.data);
 619         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 620                 free_symbol_cache(arg->fetch.data);
 621
 622         kfree(arg->name);
 623         kfree(arg->comm);
 624 }
 625
 626 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 627                            bool is_return)
 628 {
 629         int i;
 630         int pos = 0;
 631
 632         const char *fmt, *arg;
 633
 634         if (!is_return) {
 635                 fmt = "(%lx)";
 636                 arg = "REC->" FIELD_STRING_IP;
 637         } else {
 638                 fmt = "(%lx <- %lx)";
 639                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
 640         }
 641
 642         /* When len=0, we just calculate the needed length */
 643 #define LEN_OR_ZERO (len ? len - pos : 0)
 644
 645         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
 646
 647         for (i = 0; i < tp->nr_args; i++) {
 648                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
 649                                 tp->args[i].name, tp->args[i].type->fmt);
 650         }
 651
 652         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 653
 654         for (i = 0; i < tp->nr_args; i++) {
 655                 if (strcmp(tp->args[i].type->name, "string") == 0)
 656                         pos += snprintf(buf + pos, LEN_OR_ZERO,
 657                                         ", __get_str(%s)",
 658                                         tp->args[i].name);
 659                 else
 660                         pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
 661                                         tp->args[i].name);
 662         }
 663
 664 #undef LEN_OR_ZERO
 665
 666         /* return the length of print_fmt */
 667         return pos;
 668 }
 669
 670 int set_print_fmt(struct trace_probe *tp, bool is_return)
 671 {
 672         int len;
 673         char *print_fmt;
 674
 675         /* First: called with 0 length to calculate the needed length */
 676         len = __set_print_fmt(tp, NULL, 0, is_return);
 677         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 678         if (!print_fmt)
 679                 return -ENOMEM;
 680
 681         /* Second: actually write the @print_fmt */
 682         __set_print_fmt(tp, print_fmt, len + 1, is_return);
 683         tp->call.print_fmt = print_fmt;
 684
 685         return 0;
 686 }