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, long *offset)
 297 {
 298         char *tmp;
 299         int ret;
 300
 301         if (!offset)
 302                 return -EINVAL;
 303
 304         tmp = strpbrk(symbol, "+-");
 305         if (tmp) {
 306                 ret = kstrtol(tmp, 0, offset);
 307                 if (ret)
 308                         return ret;
 309                 *tmp = '\0';
 310         } else
 311                 *offset = 0;
 312
 313         return 0;
 314 }
 315
 316 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 317
 318 static int parse_probe_vars(char *arg, const struct fetch_type *t,
 319                             struct fetch_param *f, bool is_return,
 320                             bool is_kprobe)
 321 {
 322         int ret = 0;
 323         unsigned long param;
 324
 325         if (strcmp(arg, "retval") == 0) {
 326                 if (is_return)
 327                         f->fn = t->fetch[FETCH_MTD_retval];
 328                 else
 329                         ret = -EINVAL;
 330         } else if (strncmp(arg, "stack", 5) == 0) {
 331                 if (arg[5] == '\0') {
 332                         if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
 333                                 return -EINVAL;
 334
 335                         if (is_kprobe)
 336                                 f->fn = fetch_kernel_stack_address;
 337                         else
 338                                 f->fn = fetch_user_stack_address;
 339                 } else if (isdigit(arg[5])) {
 340                         ret = kstrtoul(arg + 5, 10, &param);
 341                         if (ret || (is_kprobe && param > PARAM_MAX_STACK))
 342                                 ret = -EINVAL;
 343                         else {
 344                                 f->fn = t->fetch[FETCH_MTD_stack];
 345                                 f->data = (void *)param;
 346                         }
 347                 } else
 348                         ret = -EINVAL;
 349         } else
 350                 ret = -EINVAL;
 351
 352         return ret;
 353 }
 354
 355 /* Recursive argument parser */
 356 static int parse_probe_arg(char *arg, const struct fetch_type *t,
 357                      struct fetch_param *f, bool is_return, bool is_kprobe,
 358                      const struct fetch_type *ftbl)
 359 {
 360         unsigned long param;
 361         long offset;
 362         char *tmp;
 363         int ret = 0;
 364
 365         switch (arg[0]) {
 366         case '$':
 367                 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
 368                 break;
 369
 370         case '%':       /* named register */
 371                 ret = regs_query_register_offset(arg + 1);
 372                 if (ret >= 0) {
 373                         f->fn = t->fetch[FETCH_MTD_reg];
 374                         f->data = (void *)(unsigned long)ret;
 375                         ret = 0;
 376                 }
 377                 break;
 378
 379         case '@':       /* memory, file-offset or symbol */
 380                 if (isdigit(arg[1])) {
 381                         ret = kstrtoul(arg + 1, 0, &param);
 382                         if (ret)
 383                                 break;
 384
 385                         f->fn = t->fetch[FETCH_MTD_memory];
 386                         f->data = (void *)param;
 387                 } else if (arg[1] == '+') {
 388                         /* kprobes don't support file offsets */
 389                         if (is_kprobe)
 390                                 return -EINVAL;
 391
 392                         ret = kstrtol(arg + 2, 0, &offset);
 393                         if (ret)
 394                                 break;
 395
 396                         f->fn = t->fetch[FETCH_MTD_file_offset];
 397                         f->data = (void *)offset;
 398                 } else {
 399                         /* uprobes don't support symbols */
 400                         if (!is_kprobe)
 401                                 return -EINVAL;
 402
 403                         ret = traceprobe_split_symbol_offset(arg + 1, &offset);
 404                         if (ret)
 405                                 break;
 406
 407                         f->data = alloc_symbol_cache(arg + 1, offset);
 408                         if (f->data)
 409                                 f->fn = t->fetch[FETCH_MTD_symbol];
 410                 }
 411                 break;
 412
 413         case '+':       /* deref memory */
 414                 arg++;  /* Skip '+', because kstrtol() rejects it. */
 415         case '-':
 416                 tmp = strchr(arg, '(');
 417                 if (!tmp)
 418                         break;
 419
 420                 *tmp = '\0';
 421                 ret = kstrtol(arg, 0, &offset);
 422
 423                 if (ret)
 424                         break;
 425
 426                 arg = tmp + 1;
 427                 tmp = strrchr(arg, ')');
 428
 429                 if (tmp) {
 430                         struct deref_fetch_param        *dprm;
 431                         const struct fetch_type         *t2;
 432
 433                         t2 = find_fetch_type(NULL, ftbl);
 434                         *tmp = '\0';
 435                         dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
 436
 437                         if (!dprm)
 438                                 return -ENOMEM;
 439
 440                         dprm->offset = offset;
 441                         dprm->fetch = t->fetch[FETCH_MTD_memory];
 442                         dprm->fetch_size = get_fetch_size_function(t,
 443                                                         dprm->fetch, ftbl);
 444                         ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
 445                                                         is_kprobe, ftbl);
 446                         if (ret)
 447                                 kfree(dprm);
 448                         else {
 449                                 f->fn = t->fetch[FETCH_MTD_deref];
 450                                 f->data = (void *)dprm;
 451                         }
 452                 }
 453                 break;
 454         }
 455         if (!ret && !f->fn) {   /* Parsed, but do not find fetch method */
 456                 pr_info("%s type has no corresponding fetch method.\n", t->name);
 457                 ret = -EINVAL;
 458         }
 459
 460         return ret;
 461 }
 462
 463 #define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))
 464
 465 /* Bitfield type needs to be parsed into a fetch function */
 466 static int __parse_bitfield_probe_arg(const char *bf,
 467                                       const struct fetch_type *t,
 468                                       struct fetch_param *f)
 469 {
 470         struct bitfield_fetch_param *bprm;
 471         unsigned long bw, bo;
 472         char *tail;
 473
 474         if (*bf != 'b')
 475                 return 0;
 476
 477         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
 478         if (!bprm)
 479                 return -ENOMEM;
 480
 481         bprm->orig = *f;
 482         f->fn = t->fetch[FETCH_MTD_bitfield];
 483         f->data = (void *)bprm;
 484         bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */
 485
 486         if (bw == 0 || *tail != '@')
 487                 return -EINVAL;
 488
 489         bf = tail + 1;
 490         bo = simple_strtoul(bf, &tail, 0);
 491
 492         if (tail == bf || *tail != '/')
 493                 return -EINVAL;
 494
 495         bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
 496         bprm->low_shift = bprm->hi_shift + bo;
 497
 498         return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
 499 }
 500
 501 /* String length checking wrapper */
 502 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 503                 struct probe_arg *parg, bool is_return, bool is_kprobe,
 504                 const struct fetch_type *ftbl)
 505 {
 506         const char *t;
 507         int ret;
 508
 509         if (strlen(arg) > MAX_ARGSTR_LEN) {
 510                 pr_info("Argument is too long.: %s\n",  arg);
 511                 return -ENOSPC;
 512         }
 513         parg->comm = kstrdup(arg, GFP_KERNEL);
 514         if (!parg->comm) {
 515                 pr_info("Failed to allocate memory for command '%s'.\n", arg);
 516                 return -ENOMEM;
 517         }
 518         t = strchr(parg->comm, ':');
 519         if (t) {
 520                 arg[t - parg->comm] = '\0';
 521                 t++;
 522         }
 523         parg->type = find_fetch_type(t, ftbl);
 524         if (!parg->type) {
 525                 pr_info("Unsupported type: %s\n", t);
 526                 return -EINVAL;
 527         }
 528         parg->offset = *size;
 529         *size += parg->type->size;
 530         ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
 531                               is_kprobe, ftbl);
 532
 533         if (ret >= 0 && t != NULL)
 534                 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
 535
 536         if (ret >= 0) {
 537                 parg->fetch_size.fn = get_fetch_size_function(parg->type,
 538                                                               parg->fetch.fn,
 539                                                               ftbl);
 540                 parg->fetch_size.data = parg->fetch.data;
 541         }
 542
 543         return ret;
 544 }
 545
 546 /* Return 1 if name is reserved or already used by another argument */
 547 int traceprobe_conflict_field_name(const char *name,
 548                                struct probe_arg *args, int narg)
 549 {
 550         int i;
 551
 552         for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
 553                 if (strcmp(reserved_field_names[i], name) == 0)
 554                         return 1;
 555
 556         for (i = 0; i < narg; i++)
 557                 if (strcmp(args[i].name, name) == 0)
 558                         return 1;
 559
 560         return 0;
 561 }
 562
 563 void traceprobe_update_arg(struct probe_arg *arg)
 564 {
 565         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 566                 update_bitfield_fetch_param(arg->fetch.data);
 567         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 568                 update_deref_fetch_param(arg->fetch.data);
 569         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 570                 update_symbol_cache(arg->fetch.data);
 571 }
 572
 573 void traceprobe_free_probe_arg(struct probe_arg *arg)
 574 {
 575         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 576                 free_bitfield_fetch_param(arg->fetch.data);
 577         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 578                 free_deref_fetch_param(arg->fetch.data);
 579         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 580                 free_symbol_cache(arg->fetch.data);
 581
 582         kfree(arg->name);
 583         kfree(arg->comm);
 584 }
 585
 586 int traceprobe_command(const char *buf, int (*createfn)(int, char **))
 587 {
 588         char **argv;
 589         int argc, ret;
 590
 591         argc = 0;
 592         ret = 0;
 593         argv = argv_split(GFP_KERNEL, buf, &argc);
 594         if (!argv)
 595                 return -ENOMEM;
 596
 597         if (argc)
 598                 ret = createfn(argc, argv);
 599
 600         argv_free(argv);
 601
 602         return ret;
 603 }
 604
 605 #define WRITE_BUFSIZE  4096
 606
 607 ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
 608                                 size_t count, loff_t *ppos,
 609                                 int (*createfn)(int, char **))
 610 {
 611         char *kbuf, *tmp;
 612         int ret = 0;
 613         size_t done = 0;
 614         size_t size;
 615
 616         kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
 617         if (!kbuf)
 618                 return -ENOMEM;
 619
 620         while (done < count) {
 621                 size = count - done;
 622
 623                 if (size >= WRITE_BUFSIZE)
 624                         size = WRITE_BUFSIZE - 1;
 625
 626                 if (copy_from_user(kbuf, buffer + done, size)) {
 627                         ret = -EFAULT;
 628                         goto out;
 629                 }
 630                 kbuf[size] = '\0';
 631                 tmp = strchr(kbuf, '\n');
 632
 633                 if (tmp) {
 634                         *tmp = '\0';
 635                         size = tmp - kbuf + 1;
 636                 } else if (done + size < count) {
 637                         pr_warning("Line length is too long: "
 638                                    "Should be less than %d.", WRITE_BUFSIZE);
 639                         ret = -EINVAL;
 640                         goto out;
 641                 }
 642                 done += size;
 643                 /* Remove comments */
 644                 tmp = strchr(kbuf, '#');
 645
 646                 if (tmp)
 647                         *tmp = '\0';
 648
 649                 ret = traceprobe_command(kbuf, createfn);
 650                 if (ret)
 651                         goto out;
 652         }
 653         ret = done;
 654
 655 out:
 656         kfree(kbuf);
 657
 658         return ret;
 659 }
 660
 661 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 662                            bool is_return)
 663 {
 664         int i;
 665         int pos = 0;
 666
 667         const char *fmt, *arg;
 668
 669         if (!is_return) {
 670                 fmt = "(%lx)";
 671                 arg = "REC->" FIELD_STRING_IP;
 672         } else {
 673                 fmt = "(%lx <- %lx)";
 674                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
 675         }
 676
 677         /* When len=0, we just calculate the needed length */
 678 #define LEN_OR_ZERO (len ? len - pos : 0)
 679
 680         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
 681
 682         for (i = 0; i < tp->nr_args; i++) {
 683                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
 684                                 tp->args[i].name, tp->args[i].type->fmt);
 685         }
 686
 687         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 688
 689         for (i = 0; i < tp->nr_args; i++) {
 690                 if (strcmp(tp->args[i].type->name, "string") == 0)
 691                         pos += snprintf(buf + pos, LEN_OR_ZERO,
 692                                         ", __get_str(%s)",
 693                                         tp->args[i].name);
 694                 else
 695                         pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
 696                                         tp->args[i].name);
 697         }
 698
 699 #undef LEN_OR_ZERO
 700
 701         /* return the length of print_fmt */
 702         return pos;
 703 }
 704
 705 int set_print_fmt(struct trace_probe *tp, bool is_return)
 706 {
 707         int len;
 708         char *print_fmt;
 709
 710         /* First: called with 0 length to calculate the needed length */
 711         len = __set_print_fmt(tp, NULL, 0, is_return);
 712         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 713         if (!print_fmt)
 714                 return -ENOMEM;
 715
 716         /* Second: actually write the @print_fmt */
 717         __set_print_fmt(tp, print_fmt, len + 1, is_return);
 718         tp->call.print_fmt = print_fmt;
 719
 720         return 0;
 721 }