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         return trace_seq_printf(s, " %s=" fmt, name, *(type *)data);    \
  44 }                                                                       \
  45 const char PRINT_TYPE_FMT_NAME(type)[] = fmt;                           \
  46 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(type));
  47
  48 DEFINE_BASIC_PRINT_TYPE_FUNC(u8 , "0x%x")
  49 DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "0x%x")
  50 DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "0x%x")
  51 DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "0x%Lx")
  52 DEFINE_BASIC_PRINT_TYPE_FUNC(s8,  "%d")
  53 DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d")
  54 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%d")
  55 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%Ld")
  56
  57 /* Print type function for string type */
  58 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name,
  59                                  void *data, void *ent)
  60 {
  61         int len = *(u32 *)data >> 16;
  62
  63         if (!len)
  64                 return trace_seq_printf(s, " %s=(fault)", name);
  65         else
  66                 return trace_seq_printf(s, " %s=\"%s\"", name,
  67                                         (const char *)get_loc_data(data, ent));
  68 }
  69 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string));
  70
  71 const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
  72
  73 #define CHECK_FETCH_FUNCS(method, fn)                   \
  74         (((FETCH_FUNC_NAME(method, u8) == fn) ||        \
  75           (FETCH_FUNC_NAME(method, u16) == fn) ||       \
  76           (FETCH_FUNC_NAME(method, u32) == fn) ||       \
  77           (FETCH_FUNC_NAME(method, u64) == fn) ||       \
  78           (FETCH_FUNC_NAME(method, string) == fn) ||    \
  79           (FETCH_FUNC_NAME(method, string_size) == fn)) \
  80          && (fn != NULL))
  81
  82 /* Data fetch function templates */
  83 #define DEFINE_FETCH_reg(type)                                          \
  84 void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, void *offset, void *dest) \
  85 {                                                                       \
  86         *(type *)dest = (type)regs_get_register(regs,                   \
  87                                 (unsigned int)((unsigned long)offset)); \
  88 }                                                                       \
  89 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type));
  90 DEFINE_BASIC_FETCH_FUNCS(reg)
  91 /* No string on the register */
  92 #define fetch_reg_string        NULL
  93 #define fetch_reg_string_size   NULL
  94
  95 #define DEFINE_FETCH_retval(type)                                       \
  96 void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,                \
  97                                    void *dummy, void *dest)             \
  98 {                                                                       \
  99         *(type *)dest = (type)regs_return_value(regs);                  \
 100 }                                                                       \
 101 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type));
 102 DEFINE_BASIC_FETCH_FUNCS(retval)
 103 /* No string on the retval */
 104 #define fetch_retval_string             NULL
 105 #define fetch_retval_string_size        NULL
 106
 107 /* Dereference memory access function */
 108 struct deref_fetch_param {
 109         struct fetch_param      orig;
 110         long                    offset;
 111         fetch_func_t            fetch;
 112         fetch_func_t            fetch_size;
 113 };
 114
 115 #define DEFINE_FETCH_deref(type)                                        \
 116 void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,                 \
 117                                   void *data, void *dest)               \
 118 {                                                                       \
 119         struct deref_fetch_param *dprm = data;                          \
 120         unsigned long addr;                                             \
 121         call_fetch(&dprm->orig, regs, &addr);                           \
 122         if (addr) {                                                     \
 123                 addr += dprm->offset;                                   \
 124                 dprm->fetch(regs, (void *)addr, dest);                  \
 125         } else                                                          \
 126                 *(type *)dest = 0;                                      \
 127 }                                                                       \
 128 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type));
 129 DEFINE_BASIC_FETCH_FUNCS(deref)
 130 DEFINE_FETCH_deref(string)
 131
 132 void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
 133                                          void *data, void *dest)
 134 {
 135         struct deref_fetch_param *dprm = data;
 136         unsigned long addr;
 137
 138         call_fetch(&dprm->orig, regs, &addr);
 139         if (addr && dprm->fetch_size) {
 140                 addr += dprm->offset;
 141                 dprm->fetch_size(regs, (void *)addr, dest);
 142         } else
 143                 *(string_size *)dest = 0;
 144 }
 145 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size));
 146
 147 static void update_deref_fetch_param(struct deref_fetch_param *data)
 148 {
 149         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 150                 update_deref_fetch_param(data->orig.data);
 151         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 152                 update_symbol_cache(data->orig.data);
 153 }
 154 NOKPROBE_SYMBOL(update_deref_fetch_param);
 155
 156 static void free_deref_fetch_param(struct deref_fetch_param *data)
 157 {
 158         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 159                 free_deref_fetch_param(data->orig.data);
 160         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 161                 free_symbol_cache(data->orig.data);
 162         kfree(data);
 163 }
 164 NOKPROBE_SYMBOL(free_deref_fetch_param);
 165
 166 /* Bitfield fetch function */
 167 struct bitfield_fetch_param {
 168         struct fetch_param      orig;
 169         unsigned char           hi_shift;
 170         unsigned char           low_shift;
 171 };
 172
 173 #define DEFINE_FETCH_bitfield(type)                                     \
 174 void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs,              \
 175                                      void *data, void *dest)            \
 176 {                                                                       \
 177         struct bitfield_fetch_param *bprm = data;                       \
 178         type buf = 0;                                                   \
 179         call_fetch(&bprm->orig, regs, &buf);                            \
 180         if (buf) {                                                      \
 181                 buf <<= bprm->hi_shift;                                 \
 182                 buf >>= bprm->low_shift;                                \
 183         }                                                               \
 184         *(type *)dest = buf;                                            \
 185 }                                                                       \
 186 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type));
 187 DEFINE_BASIC_FETCH_FUNCS(bitfield)
 188 #define fetch_bitfield_string           NULL
 189 #define fetch_bitfield_string_size      NULL
 190
 191 static void
 192 update_bitfield_fetch_param(struct bitfield_fetch_param *data)
 193 {
 194         /*
 195          * Don't check the bitfield itself, because this must be the
 196          * last fetch function.
 197          */
 198         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 199                 update_deref_fetch_param(data->orig.data);
 200         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 201                 update_symbol_cache(data->orig.data);
 202 }
 203
 204 static void
 205 free_bitfield_fetch_param(struct bitfield_fetch_param *data)
 206 {
 207         /*
 208          * Don't check the bitfield itself, because this must be the
 209          * last fetch function.
 210          */
 211         if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
 212                 free_deref_fetch_param(data->orig.data);
 213         else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
 214                 free_symbol_cache(data->orig.data);
 215
 216         kfree(data);
 217 }
 218
 219 static const struct fetch_type *find_fetch_type(const char *type,
 220                                                 const struct fetch_type *ftbl)
 221 {
 222         int i;
 223
 224         if (!type)
 225                 type = DEFAULT_FETCH_TYPE_STR;
 226
 227         /* Special case: bitfield */
 228         if (*type == 'b') {
 229                 unsigned long bs;
 230
 231                 type = strchr(type, '/');
 232                 if (!type)
 233                         goto fail;
 234
 235                 type++;
 236                 if (kstrtoul(type, 0, &bs))
 237                         goto fail;
 238
 239                 switch (bs) {
 240                 case 8:
 241                         return find_fetch_type("u8", ftbl);
 242                 case 16:
 243                         return find_fetch_type("u16", ftbl);
 244                 case 32:
 245                         return find_fetch_type("u32", ftbl);
 246                 case 64:
 247                         return find_fetch_type("u64", ftbl);
 248                 default:
 249                         goto fail;
 250                 }
 251         }
 252
 253         for (i = 0; ftbl[i].name; i++) {
 254                 if (strcmp(type, ftbl[i].name) == 0)
 255                         return &ftbl[i];
 256         }
 257
 258 fail:
 259         return NULL;
 260 }
 261
 262 /* Special function : only accept unsigned long */
 263 static void fetch_kernel_stack_address(struct pt_regs *regs, void *dummy, void *dest)
 264 {
 265         *(unsigned long *)dest = kernel_stack_pointer(regs);
 266 }
 267 NOKPROBE_SYMBOL(fetch_kernel_stack_address);
 268
 269 static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *dest)
 270 {
 271         *(unsigned long *)dest = user_stack_pointer(regs);
 272 }
 273 NOKPROBE_SYMBOL(fetch_user_stack_address);
 274
 275 static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
 276                                             fetch_func_t orig_fn,
 277                                             const struct fetch_type *ftbl)
 278 {
 279         int i;
 280
 281         if (type != &ftbl[FETCH_TYPE_STRING])
 282                 return NULL;    /* Only string type needs size function */
 283
 284         for (i = 0; i < FETCH_MTD_END; i++)
 285                 if (type->fetch[i] == orig_fn)
 286                         return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
 287
 288         WARN_ON(1);     /* This should not happen */
 289
 290         return NULL;
 291 }
 292
 293 /* Split symbol and offset. */
 294 int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
 295 {
 296         char *tmp;
 297         int ret;
 298
 299         if (!offset)
 300                 return -EINVAL;
 301
 302         tmp = strchr(symbol, '+');
 303         if (tmp) {
 304                 /* skip sign because kstrtoul doesn't accept '+' */
 305                 ret = kstrtoul(tmp + 1, 0, offset);
 306                 if (ret)
 307                         return ret;
 308
 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 {
 359         const struct fetch_type *ftbl;
 360         unsigned long param;
 361         long offset;
 362         char *tmp;
 363         int ret = 0;
 364
 365         ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
 366         BUG_ON(ftbl == NULL);
 367
 368         switch (arg[0]) {
 369         case '$':
 370                 ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
 371                 break;
 372
 373         case '%':       /* named register */
 374                 ret = regs_query_register_offset(arg + 1);
 375                 if (ret >= 0) {
 376                         f->fn = t->fetch[FETCH_MTD_reg];
 377                         f->data = (void *)(unsigned long)ret;
 378                         ret = 0;
 379                 }
 380                 break;
 381
 382         case '@':       /* memory, file-offset or symbol */
 383                 if (isdigit(arg[1])) {
 384                         ret = kstrtoul(arg + 1, 0, &param);
 385                         if (ret)
 386                                 break;
 387
 388                         f->fn = t->fetch[FETCH_MTD_memory];
 389                         f->data = (void *)param;
 390                 } else if (arg[1] == '+') {
 391                         /* kprobes don't support file offsets */
 392                         if (is_kprobe)
 393                                 return -EINVAL;
 394
 395                         ret = kstrtol(arg + 2, 0, &offset);
 396                         if (ret)
 397                                 break;
 398
 399                         f->fn = t->fetch[FETCH_MTD_file_offset];
 400                         f->data = (void *)offset;
 401                 } else {
 402                         /* uprobes don't support symbols */
 403                         if (!is_kprobe)
 404                                 return -EINVAL;
 405
 406                         ret = traceprobe_split_symbol_offset(arg + 1, &offset);
 407                         if (ret)
 408                                 break;
 409
 410                         f->data = alloc_symbol_cache(arg + 1, offset);
 411                         if (f->data)
 412                                 f->fn = t->fetch[FETCH_MTD_symbol];
 413                 }
 414                 break;
 415
 416         case '+':       /* deref memory */
 417                 arg++;  /* Skip '+', because kstrtol() rejects it. */
 418         case '-':
 419                 tmp = strchr(arg, '(');
 420                 if (!tmp)
 421                         break;
 422
 423                 *tmp = '\0';
 424                 ret = kstrtol(arg, 0, &offset);
 425
 426                 if (ret)
 427                         break;
 428
 429                 arg = tmp + 1;
 430                 tmp = strrchr(arg, ')');
 431
 432                 if (tmp) {
 433                         struct deref_fetch_param        *dprm;
 434                         const struct fetch_type         *t2;
 435
 436                         t2 = find_fetch_type(NULL, ftbl);
 437                         *tmp = '\0';
 438                         dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
 439
 440                         if (!dprm)
 441                                 return -ENOMEM;
 442
 443                         dprm->offset = offset;
 444                         dprm->fetch = t->fetch[FETCH_MTD_memory];
 445                         dprm->fetch_size = get_fetch_size_function(t,
 446                                                         dprm->fetch, ftbl);
 447                         ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
 448                                                         is_kprobe);
 449                         if (ret)
 450                                 kfree(dprm);
 451                         else {
 452                                 f->fn = t->fetch[FETCH_MTD_deref];
 453                                 f->data = (void *)dprm;
 454                         }
 455                 }
 456                 break;
 457         }
 458         if (!ret && !f->fn) {   /* Parsed, but do not find fetch method */
 459                 pr_info("%s type has no corresponding fetch method.\n", t->name);
 460                 ret = -EINVAL;
 461         }
 462
 463         return ret;
 464 }
 465
 466 #define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))
 467
 468 /* Bitfield type needs to be parsed into a fetch function */
 469 static int __parse_bitfield_probe_arg(const char *bf,
 470                                       const struct fetch_type *t,
 471                                       struct fetch_param *f)
 472 {
 473         struct bitfield_fetch_param *bprm;
 474         unsigned long bw, bo;
 475         char *tail;
 476
 477         if (*bf != 'b')
 478                 return 0;
 479
 480         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
 481         if (!bprm)
 482                 return -ENOMEM;
 483
 484         bprm->orig = *f;
 485         f->fn = t->fetch[FETCH_MTD_bitfield];
 486         f->data = (void *)bprm;
 487         bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */
 488
 489         if (bw == 0 || *tail != '@')
 490                 return -EINVAL;
 491
 492         bf = tail + 1;
 493         bo = simple_strtoul(bf, &tail, 0);
 494
 495         if (tail == bf || *tail != '/')
 496                 return -EINVAL;
 497
 498         bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
 499         bprm->low_shift = bprm->hi_shift + bo;
 500
 501         return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
 502 }
 503
 504 /* String length checking wrapper */
 505 int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
 506                 struct probe_arg *parg, bool is_return, bool is_kprobe)
 507 {
 508         const struct fetch_type *ftbl;
 509         const char *t;
 510         int ret;
 511
 512         ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
 513         BUG_ON(ftbl == NULL);
 514
 515         if (strlen(arg) > MAX_ARGSTR_LEN) {
 516                 pr_info("Argument is too long.: %s\n",  arg);
 517                 return -ENOSPC;
 518         }
 519         parg->comm = kstrdup(arg, GFP_KERNEL);
 520         if (!parg->comm) {
 521                 pr_info("Failed to allocate memory for command '%s'.\n", arg);
 522                 return -ENOMEM;
 523         }
 524         t = strchr(parg->comm, ':');
 525         if (t) {
 526                 arg[t - parg->comm] = '\0';
 527                 t++;
 528         }
 529         parg->type = find_fetch_type(t, ftbl);
 530         if (!parg->type) {
 531                 pr_info("Unsupported type: %s\n", t);
 532                 return -EINVAL;
 533         }
 534         parg->offset = *size;
 535         *size += parg->type->size;
 536         ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe);
 537
 538         if (ret >= 0 && t != NULL)
 539                 ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
 540
 541         if (ret >= 0) {
 542                 parg->fetch_size.fn = get_fetch_size_function(parg->type,
 543                                                               parg->fetch.fn,
 544                                                               ftbl);
 545                 parg->fetch_size.data = parg->fetch.data;
 546         }
 547
 548         return ret;
 549 }
 550
 551 /* Return 1 if name is reserved or already used by another argument */
 552 int traceprobe_conflict_field_name(const char *name,
 553                                struct probe_arg *args, int narg)
 554 {
 555         int i;
 556
 557         for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
 558                 if (strcmp(reserved_field_names[i], name) == 0)
 559                         return 1;
 560
 561         for (i = 0; i < narg; i++)
 562                 if (strcmp(args[i].name, name) == 0)
 563                         return 1;
 564
 565         return 0;
 566 }
 567
 568 void traceprobe_update_arg(struct probe_arg *arg)
 569 {
 570         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 571                 update_bitfield_fetch_param(arg->fetch.data);
 572         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 573                 update_deref_fetch_param(arg->fetch.data);
 574         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 575                 update_symbol_cache(arg->fetch.data);
 576 }
 577
 578 void traceprobe_free_probe_arg(struct probe_arg *arg)
 579 {
 580         if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
 581                 free_bitfield_fetch_param(arg->fetch.data);
 582         else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
 583                 free_deref_fetch_param(arg->fetch.data);
 584         else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
 585                 free_symbol_cache(arg->fetch.data);
 586
 587         kfree(arg->name);
 588         kfree(arg->comm);
 589 }
 590
 591 int traceprobe_command(const char *buf, int (*createfn)(int, char **))
 592 {
 593         char **argv;
 594         int argc, ret;
 595
 596         argc = 0;
 597         ret = 0;
 598         argv = argv_split(GFP_KERNEL, buf, &argc);
 599         if (!argv)
 600                 return -ENOMEM;
 601
 602         if (argc)
 603                 ret = createfn(argc, argv);
 604
 605         argv_free(argv);
 606
 607         return ret;
 608 }
 609
 610 #define WRITE_BUFSIZE  4096
 611
 612 ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
 613                                 size_t count, loff_t *ppos,
 614                                 int (*createfn)(int, char **))
 615 {
 616         char *kbuf, *tmp;
 617         int ret = 0;
 618         size_t done = 0;
 619         size_t size;
 620
 621         kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
 622         if (!kbuf)
 623                 return -ENOMEM;
 624
 625         while (done < count) {
 626                 size = count - done;
 627
 628                 if (size >= WRITE_BUFSIZE)
 629                         size = WRITE_BUFSIZE - 1;
 630
 631                 if (copy_from_user(kbuf, buffer + done, size)) {
 632                         ret = -EFAULT;
 633                         goto out;
 634                 }
 635                 kbuf[size] = '\0';
 636                 tmp = strchr(kbuf, '\n');
 637
 638                 if (tmp) {
 639                         *tmp = '\0';
 640                         size = tmp - kbuf + 1;
 641                 } else if (done + size < count) {
 642                         pr_warning("Line length is too long: "
 643                                    "Should be less than %d.", WRITE_BUFSIZE);
 644                         ret = -EINVAL;
 645                         goto out;
 646                 }
 647                 done += size;
 648                 /* Remove comments */
 649                 tmp = strchr(kbuf, '#');
 650
 651                 if (tmp)
 652                         *tmp = '\0';
 653
 654                 ret = traceprobe_command(kbuf, createfn);
 655                 if (ret)
 656                         goto out;
 657         }
 658         ret = done;
 659
 660 out:
 661         kfree(kbuf);
 662
 663         return ret;
 664 }
 665
 666 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 667                            bool is_return)
 668 {
 669         int i;
 670         int pos = 0;
 671
 672         const char *fmt, *arg;
 673
 674         if (!is_return) {
 675                 fmt = "(%lx)";
 676                 arg = "REC->" FIELD_STRING_IP;
 677         } else {
 678                 fmt = "(%lx <- %lx)";
 679                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
 680         }
 681
 682         /* When len=0, we just calculate the needed length */
 683 #define LEN_OR_ZERO (len ? len - pos : 0)
 684
 685         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
 686
 687         for (i = 0; i < tp->nr_args; i++) {
 688                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
 689                                 tp->args[i].name, tp->args[i].type->fmt);
 690         }
 691
 692         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 693
 694         for (i = 0; i < tp->nr_args; i++) {
 695                 if (strcmp(tp->args[i].type->name, "string") == 0)
 696                         pos += snprintf(buf + pos, LEN_OR_ZERO,
 697                                         ", __get_str(%s)",
 698                                         tp->args[i].name);
 699                 else
 700                         pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
 701                                         tp->args[i].name);
 702         }
 703
 704 #undef LEN_OR_ZERO
 705
 706         /* return the length of print_fmt */
 707         return pos;
 708 }
 709
 710 int set_print_fmt(struct trace_probe *tp, bool is_return)
 711 {
 712         int len;
 713         char *print_fmt;
 714
 715         /* First: called with 0 length to calculate the needed length */
 716         len = __set_print_fmt(tp, NULL, 0, is_return);
 717         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 718         if (!print_fmt)
 719                 return -ENOMEM;
 720
 721         /* Second: actually write the @print_fmt */
 722         __set_print_fmt(tp, print_fmt, len + 1, is_return);
 723         tp->call.print_fmt = print_fmt;
 724
 725         return 0;
 726 }