kernel/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
  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, &param);
 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                      const struct fetch_type *ftbl)
 361 {
 362         unsigned long param;
 363         long offset;
 364         char *tmp;
 365         int ret = 0;
 366
 367         switch (arg[0]) {
 368         case '$':
 369                 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
 370                 break;
 371
 372         case '%':       /* named register */
 373                 ret = regs_query_register_offset(arg + 1);
 374                 if (ret >= 0) {
 375                         f->fn = t->fetch[FETCH_MTD_reg];
 376                         f->data = (void *)(unsigned long)ret;
 377                         ret = 0;
 378                 }
 379                 break;
 380
 381         case '@':       /* memory, file-offset or symbol */
 382                 if (isdigit(arg[1])) {
 383                         ret = kstrtoul(arg + 1, 0, &param);
 384                         if (ret)
 385                                 break;
 386
 387                         f->fn = t->fetch[FETCH_MTD_memory];
 388                         f->data = (void *)param;
 389                 } else if (arg[1] == '+') {
 390                         /* kprobes don't support file offsets */
 391                         if (is_kprobe)
 392                                 return -EINVAL;
 393
 394                         ret = kstrtol(arg + 2, 0, &offset);
 395                         if (ret)
 396                                 break;
 397
 398                         f->fn = t->fetch[FETCH_MTD_file_offset];
 399                         f->data = (void *)offset;
 400                 } else {
 401                         /* uprobes don't support symbols */
 402                         if (!is_kprobe)
 403                                 return -EINVAL;
 404
 405                         ret = traceprobe_split_symbol_offset(arg + 1, &offset);
 406                         if (ret)
 407                                 break;
 408
 409                         f->data = alloc_symbol_cache(arg + 1, offset);
 410                         if (f->data)
 411                                 f->fn = t->fetch[FETCH_MTD_symbol];
 412                 }
 413                 break;
 414
 415         case '+':       /* deref memory */
 416                 arg++;  /* Skip '+', because kstrtol() rejects it. */
 417         case '-':
 418                 tmp = strchr(arg, '(');
 419                 if (!tmp)
 420                         break;
 421
 422                 *tmp = '\0';
 423                 ret = kstrtol(arg, 0, &offset);
 424
 425                 if (ret)
 426                         break;
 427
 428                 arg = tmp + 1;
 429                 tmp = strrchr(arg, ')');
 430
 431                 if (tmp) {
 432                         struct deref_fetch_param        *dprm;
 433                         const struct fetch_type         *t2;
 434
 435                         t2 = find_fetch_type(NULL, ftbl);
 436                         *tmp = '\0';
 437                         dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
 438
 439                         if (!dprm)
 440                                 return -ENOMEM;
 441
 442                         dprm->offset = offset;
 443                         dprm->fetch = t->fetch[FETCH_MTD_memory];
 444                         dprm->fetch_size = get_fetch_size_function(t,
 445                                                         dprm->fetch, ftbl);
 446                         ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
 447                                                         is_kprobe, ftbl);
 448                         if (ret)
 449                                 kfree(dprm);
 450                         else {
 451                                 f->fn = t->fetch[FETCH_MTD_deref];
 452                                 f->data = (void *)dprm;
 453                         }
 454                 }
 455                 break;
 456         }
 457         if (!ret && !f->fn) {   /* Parsed, but do not find fetch method */
 458                 pr_info("%s type has no corresponding fetch method.\n", t->name);
 459                 ret = -EINVAL;
 460         }
 461
 462         return ret;
 463 }
 464
 465 #define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))
 466
 467 /* Bitfield type needs to be parsed into a fetch function */
 468 static int __parse_bitfield_probe_arg(const char *bf,
 469                                       const struct fetch_type *t,
 470                                       struct fetch_param *f)
 471 {
 472         struct bitfield_fetch_param *bprm;
 473         unsigned long bw, bo;
 474         char *tail;
 475
 476         if (*bf != 'b')
 477                 return 0;
 478
 479         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
 480         if (!bprm)
 481                 return -ENOMEM;
 482
 483         bprm->orig = *f;
 484         f->fn = t->fetch[FETCH_MTD_bitfield];
 485         f->data = (void *)bprm;
 486         bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */
 487
 488         if (bw == 0 || *tail != '@')
 489                 return -EINVAL;
 490
 491         bf = tail + 1;
 492         bo = simple_strtoul(bf, &tail, 0);
 493
 494         if (tail == bf || *tail != '/')
 495                 return -EINVAL;
 496
 497         bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
 498         bprm->low_shift = bprm->hi_shift + bo;
 499
 500         return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
 501 }
 502
 503 /* String length checking wrapper */
 504 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 505                 struct probe_arg *parg, bool is_return, bool is_kprobe,
 506                 const struct fetch_type *ftbl)
 507 {
 508         const char *t;
 509         int ret;
 510
 511         if (strlen(arg) > MAX_ARGSTR_LEN) {
 512                 pr_info("Argument is too long.: %s\n",  arg);
 513                 return -ENOSPC;
 514         }
 515         parg->comm = kstrdup(arg, GFP_KERNEL);
 516         if (!parg->comm) {
 517                 pr_info("Failed to allocate memory for command '%s'.\n", arg);
 518                 return -ENOMEM;
 519         }
 520         t = strchr(parg->comm, ':');
 521         if (t) {
 522                 arg[t - parg->comm] = '\0';
 523                 t++;
 524         }
 525         parg->type = find_fetch_type(t, ftbl);
 526         if (!parg->type) {
 527                 pr_info("Unsupported type: %s\n", t);
 528                 return -EINVAL;
 529         }
 530         parg->offset = *size;
 531         *size += parg->type->size;
 532         ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
 533                               is_kprobe, ftbl);
 534
 535         if (ret >= 0 && t != NULL)
 536                 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
 537
 538         if (ret >= 0) {
 539                 parg->fetch_size.fn = get_fetch_size_function(parg->type,
 540                                                               parg->fetch.fn,
 541                                                               ftbl);
 542                 parg->fetch_size.data = parg->fetch.data;
 543         }
 544
 545         return ret;
 546 }
 547
 548 /* Return 1 if name is reserved or already used by another argument */
 549 int traceprobe_conflict_field_name(const char *name,
 550                                struct probe_arg *args, int narg)
 551 {
 552         int i;
 553
 554         for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
 555                 if (strcmp(reserved_field_names[i], name) == 0)
 556                         return 1;
 557
 558         for (i = 0; i < narg; i++)
 559                 if (strcmp(args[i].name, name) == 0)
 560                         return 1;
 561
 562         return 0;
 563 }
 564
 565 void traceprobe_update_arg(struct probe_arg *arg)
 566 {
 567         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 568                 update_bitfield_fetch_param(arg->fetch.data);
 569         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 570                 update_deref_fetch_param(arg->fetch.data);
 571         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 572                 update_symbol_cache(arg->fetch.data);
 573 }
 574
 575 void traceprobe_free_probe_arg(struct probe_arg *arg)
 576 {
 577         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 578                 free_bitfield_fetch_param(arg->fetch.data);
 579         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 580                 free_deref_fetch_param(arg->fetch.data);
 581         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 582                 free_symbol_cache(arg->fetch.data);
 583
 584         kfree(arg->name);
 585         kfree(arg->comm);
 586 }
 587
 588 int traceprobe_command(const char *buf, int (*createfn)(int, char **))
 589 {
 590         char **argv;
 591         int argc, ret;
 592
 593         argc = 0;
 594         ret = 0;
 595         argv = argv_split(GFP_KERNEL, buf, &argc);
 596         if (!argv)
 597                 return -ENOMEM;
 598
 599         if (argc)
 600                 ret = createfn(argc, argv);
 601
 602         argv_free(argv);
 603
 604         return ret;
 605 }
 606
 607 #define WRITE_BUFSIZE  4096
 608
 609 ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
 610                                 size_t count, loff_t *ppos,
 611                                 int (*createfn)(int, char **))
 612 {
 613         char *kbuf, *tmp;
 614         int ret = 0;
 615         size_t done = 0;
 616         size_t size;
 617
 618         kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
 619         if (!kbuf)
 620                 return -ENOMEM;
 621
 622         while (done < count) {
 623                 size = count - done;
 624
 625                 if (size >= WRITE_BUFSIZE)
 626                         size = WRITE_BUFSIZE - 1;
 627
 628                 if (copy_from_user(kbuf, buffer + done, size)) {
 629                         ret = -EFAULT;
 630                         goto out;
 631                 }
 632                 kbuf[size] = '\0';
 633                 tmp = strchr(kbuf, '\n');
 634
 635                 if (tmp) {
 636                         *tmp = '\0';
 637                         size = tmp - kbuf + 1;
 638                 } else if (done + size < count) {
 639                         pr_warning("Line length is too long: "
 640                                    "Should be less than %d.", WRITE_BUFSIZE);
 641                         ret = -EINVAL;
 642                         goto out;
 643                 }
 644                 done += size;
 645                 /* Remove comments */
 646                 tmp = strchr(kbuf, '#');
 647
 648                 if (tmp)
 649                         *tmp = '\0';
 650
 651                 ret = traceprobe_command(kbuf, createfn);
 652                 if (ret)
 653                         goto out;
 654         }
 655         ret = done;
 656
 657 out:
 658         kfree(kbuf);
 659
 660         return ret;
 661 }
 662
 663 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 664                            bool is_return)
 665 {
 666         int i;
 667         int pos = 0;
 668
 669         const char *fmt, *arg;
 670
 671         if (!is_return) {
 672                 fmt = "(%lx)";
 673                 arg = "REC->" FIELD_STRING_IP;
 674         } else {
 675                 fmt = "(%lx <- %lx)";
 676                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
 677         }
 678
 679         /* When len=0, we just calculate the needed length */
 680 #define LEN_OR_ZERO (len ? len - pos : 0)
 681
 682         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
 683
 684         for (i = 0; i < tp->nr_args; i++) {
 685                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
 686                                 tp->args[i].name, tp->args[i].type->fmt);
 687         }
 688
 689         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 690
 691         for (i = 0; i < tp->nr_args; i++) {
 692                 if (strcmp(tp->args[i].type->name, "string") == 0)
 693                         pos += snprintf(buf + pos, LEN_OR_ZERO,
 694                                         ", __get_str(%s)",
 695                                         tp->args[i].name);
 696                 else
 697                         pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
 698                                         tp->args[i].name);
 699         }
 700
 701 #undef LEN_OR_ZERO
 702
 703         /* return the length of print_fmt */
 704         return pos;
 705 }
 706
 707 int 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 }