kernel/trace/trace_uprobe.c

   1 /*
   2  * uprobes-based tracing 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  * Copyright (C) IBM Corporation, 2010-2012
  18  * Author:      Srikar Dronamraju <srikar@linux.vnet.ibm.com>
  19  */
  20 #define pr_fmt(fmt)     "trace_kprobe: " fmt
  21
  22 #include <linux/module.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/uprobes.h>
  25 #include <linux/namei.h>
  26 #include <linux/string.h>
  27 #include <linux/rculist.h>
  28
  29 #include "trace_probe.h"
  30
  31 #define UPROBE_EVENT_SYSTEM     "uprobes"
  32
  33 struct uprobe_trace_entry_head {
  34         struct trace_entry      ent;
  35         unsigned long           vaddr[];
  36 };
  37
  38 #define SIZEOF_TRACE_ENTRY(is_return)                   \
  39         (sizeof(struct uprobe_trace_entry_head) +       \
  40          sizeof(unsigned long) * (is_return ? 2 : 1))
  41
  42 #define DATAOF_TRACE_ENTRY(entry, is_return)            \
  43         ((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))
  44
  45 struct trace_uprobe_filter {
  46         rwlock_t                rwlock;
  47         int                     nr_systemwide;
  48         struct list_head        perf_events;
  49 };
  50
  51 /*
  52  * uprobe event core functions
  53  */
  54 struct trace_uprobe {
  55         struct list_head                list;
  56         struct trace_uprobe_filter      filter;
  57         struct uprobe_consumer          consumer;
  58         struct path                     path;
  59         struct inode                    *inode;
  60         char                            *filename;
  61         unsigned long                   offset;
  62         unsigned long                   nhit;
  63         struct trace_probe              tp;
  64 };
  65
  66 #define SIZEOF_TRACE_UPROBE(n)                          \
  67         (offsetof(struct trace_uprobe, tp.args) +       \
  68         (sizeof(struct probe_arg) * (n)))
  69
  70 static int register_uprobe_event(struct trace_uprobe *tu);
  71 static int unregister_uprobe_event(struct trace_uprobe *tu);
  72
  73 static DEFINE_MUTEX(uprobe_lock);
  74 static LIST_HEAD(uprobe_list);
  75
  76 struct uprobe_dispatch_data {
  77         struct trace_uprobe     *tu;
  78         unsigned long           bp_addr;
  79 };
  80
  81 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
  82 static int uretprobe_dispatcher(struct uprobe_consumer *con,
  83                                 unsigned long func, struct pt_regs *regs);
  84
  85 #ifdef CONFIG_STACK_GROWSUP
  86 static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
  87 {
  88         return addr - (n * sizeof(long));
  89 }
  90 #else
  91 static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
  92 {
  93         return addr + (n * sizeof(long));
  94 }
  95 #endif
  96
  97 static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
  98 {
  99         unsigned long ret;
 100         unsigned long addr = user_stack_pointer(regs);
 101
 102         addr = adjust_stack_addr(addr, n);
 103
 104         if (copy_from_user(&ret, (void __force __user *) addr, sizeof(ret)))
 105                 return 0;
 106
 107         return ret;
 108 }
 109
 110 /*
 111  * Uprobes-specific fetch functions
 112  */
 113 #define DEFINE_FETCH_stack(type)                                        \
 114 static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,          \
 115                                          void *offset, void *dest)      \
 116 {                                                                       \
 117         *(type *)dest = (type)get_user_stack_nth(regs,                  \
 118                                               ((unsigned long)offset)); \
 119 }
 120 DEFINE_BASIC_FETCH_FUNCS(stack)
 121 /* No string on the stack entry */
 122 #define fetch_stack_string      NULL
 123 #define fetch_stack_string_size NULL
 124
 125 #define DEFINE_FETCH_memory(type)                                       \
 126 static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,         \
 127                                           void *addr, void *dest)       \
 128 {                                                                       \
 129         type retval;                                                    \
 130         void __user *vaddr = (void __force __user *) addr;              \
 131                                                                         \
 132         if (copy_from_user(&retval, vaddr, sizeof(type)))               \
 133                 *(type *)dest = 0;                                      \
 134         else                                                            \
 135                 *(type *) dest = retval;                                \
 136 }
 137 DEFINE_BASIC_FETCH_FUNCS(memory)
 138 /*
 139  * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
 140  * length and relative data location.
 141  */
 142 static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
 143                                             void *addr, void *dest)
 144 {
 145         long ret;
 146         u32 rloc = *(u32 *)dest;
 147         int maxlen  = get_rloc_len(rloc);
 148         u8 *dst = get_rloc_data(dest);
 149         void __user *src = (void __force __user *) addr;
 150
 151         if (!maxlen)
 152                 return;
 153
 154         ret = strncpy_from_user(dst, src, maxlen);
 155         if (ret == maxlen)
 156                 dst[--ret] = '\0';
 157
 158         if (ret < 0) {  /* Failed to fetch string */
 159                 ((u8 *)get_rloc_data(dest))[0] = '\0';
 160                 *(u32 *)dest = make_data_rloc(0, get_rloc_offs(rloc));
 161         } else {
 162                 *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(rloc));
 163         }
 164 }
 165
 166 static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
 167                                                  void *addr, void *dest)
 168 {
 169         int len;
 170         void __user *vaddr = (void __force __user *) addr;
 171
 172         len = strnlen_user(vaddr, MAX_STRING_SIZE);
 173
 174         if (len == 0 || len > MAX_STRING_SIZE)  /* Failed to check length */
 175                 *(u32 *)dest = 0;
 176         else
 177                 *(u32 *)dest = len;
 178 }
 179
 180 static unsigned long translate_user_vaddr(void *file_offset)
 181 {
 182         unsigned long base_addr;
 183         struct uprobe_dispatch_data *udd;
 184
 185         udd = (void *) current->utask->vaddr;
 186
 187         base_addr = udd->bp_addr - udd->tu->offset;
 188         return base_addr + (unsigned long)file_offset;
 189 }
 190
 191 #define DEFINE_FETCH_file_offset(type)                                  \
 192 static void FETCH_FUNC_NAME(file_offset, type)(struct pt_regs *regs,    \
 193                                                void *offset, void *dest)\
 194 {                                                                       \
 195         void *vaddr = (void *)translate_user_vaddr(offset);             \
 196                                                                         \
 197         FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest);               \
 198 }
 199 DEFINE_BASIC_FETCH_FUNCS(file_offset)
 200 DEFINE_FETCH_file_offset(string)
 201 DEFINE_FETCH_file_offset(string_size)
 202
 203 /* Fetch type information table */
 204 static const struct fetch_type uprobes_fetch_type_table[] = {
 205         /* Special types */
 206         [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
 207                                         sizeof(u32), 1, "__data_loc char[]"),
 208         [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
 209                                         string_size, sizeof(u32), 0, "u32"),
 210         /* Basic types */
 211         ASSIGN_FETCH_TYPE(u8,  u8,  0),
 212         ASSIGN_FETCH_TYPE(u16, u16, 0),
 213         ASSIGN_FETCH_TYPE(u32, u32, 0),
 214         ASSIGN_FETCH_TYPE(u64, u64, 0),
 215         ASSIGN_FETCH_TYPE(s8,  u8,  1),
 216         ASSIGN_FETCH_TYPE(s16, u16, 1),
 217         ASSIGN_FETCH_TYPE(s32, u32, 1),
 218         ASSIGN_FETCH_TYPE(s64, u64, 1),
 219         ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
 220         ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
 221         ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
 222         ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
 223
 224         ASSIGN_FETCH_TYPE_END
 225 };
 226
 227 static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
 228 {
 229         rwlock_init(&filter->rwlock);
 230         filter->nr_systemwide = 0;
 231         INIT_LIST_HEAD(&filter->perf_events);
 232 }
 233
 234 static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
 235 {
 236         return !filter->nr_systemwide && list_empty(&filter->perf_events);
 237 }
 238
 239 static inline bool is_ret_probe(struct trace_uprobe *tu)
 240 {
 241         return tu->consumer.ret_handler != NULL;
 242 }
 243
 244 /*
 245  * Allocate new trace_uprobe and initialize it (including uprobes).
 246  */
 247 static struct trace_uprobe *
 248 alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
 249 {
 250         struct trace_uprobe *tu;
 251
 252         if (!event || !is_good_name(event))
 253                 return ERR_PTR(-EINVAL);
 254
 255         if (!group || !is_good_name(group))
 256                 return ERR_PTR(-EINVAL);
 257
 258         tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
 259         if (!tu)
 260                 return ERR_PTR(-ENOMEM);
 261
 262         tu->tp.call.class = &tu->tp.class;
 263         tu->tp.call.name = kstrdup(event, GFP_KERNEL);
 264         if (!tu->tp.call.name)
 265                 goto error;
 266
 267         tu->tp.class.system = kstrdup(group, GFP_KERNEL);
 268         if (!tu->tp.class.system)
 269                 goto error;
 270
 271         INIT_LIST_HEAD(&tu->list);
 272         INIT_LIST_HEAD(&tu->tp.files);
 273         tu->consumer.handler = uprobe_dispatcher;
 274         if (is_ret)
 275                 tu->consumer.ret_handler = uretprobe_dispatcher;
 276         init_trace_uprobe_filter(&tu->filter);
 277         return tu;
 278
 279 error:
 280         kfree(tu->tp.call.name);
 281         kfree(tu);
 282
 283         return ERR_PTR(-ENOMEM);
 284 }
 285
 286 static void free_trace_uprobe(struct trace_uprobe *tu)
 287 {
 288         int i;
 289
 290         for (i = 0; i < tu->tp.nr_args; i++)
 291                 traceprobe_free_probe_arg(&tu->tp.args[i]);
 292
 293         path_put(&tu->path);
 294         kfree(tu->tp.call.class->system);
 295         kfree(tu->tp.call.name);
 296         kfree(tu->filename);
 297         kfree(tu);
 298 }
 299
 300 static struct trace_uprobe *find_probe_event(const char *event, const char *group)
 301 {
 302         struct trace_uprobe *tu;
 303
 304         list_for_each_entry(tu, &uprobe_list, list)
 305                 if (strcmp(trace_event_name(&tu->tp.call), event) == 0 &&
 306                     strcmp(tu->tp.call.class->system, group) == 0)
 307                         return tu;
 308
 309         return NULL;
 310 }
 311
 312 /* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
 313 static int unregister_trace_uprobe(struct trace_uprobe *tu)
 314 {
 315         int ret;
 316
 317         ret = unregister_uprobe_event(tu);
 318         if (ret)
 319                 return ret;
 320
 321         list_del(&tu->list);
 322         free_trace_uprobe(tu);
 323         return 0;
 324 }
 325
 326 /* Register a trace_uprobe and probe_event */
 327 static int register_trace_uprobe(struct trace_uprobe *tu)
 328 {
 329         struct trace_uprobe *old_tu;
 330         int ret;
 331
 332         mutex_lock(&uprobe_lock);
 333
 334         /* register as an event */
 335         old_tu = find_probe_event(trace_event_name(&tu->tp.call),
 336                         tu->tp.call.class->system);
 337         if (old_tu) {
 338                 /* delete old event */
 339                 ret = unregister_trace_uprobe(old_tu);
 340                 if (ret)
 341                         goto end;
 342         }
 343
 344         ret = register_uprobe_event(tu);
 345         if (ret) {
 346                 pr_warn("Failed to register probe event(%d)\n", ret);
 347                 goto end;
 348         }
 349
 350         list_add_tail(&tu->list, &uprobe_list);
 351
 352 end:
 353         mutex_unlock(&uprobe_lock);
 354
 355         return ret;
 356 }
 357
 358 /*
 359  * Argument syntax:
 360  *  - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS]
 361  *
 362  *  - Remove uprobe: -:[GRP/]EVENT
 363  */
 364 static int create_trace_uprobe(int argc, char **argv)
 365 {
 366         struct trace_uprobe *tu;
 367         char *arg, *event, *group, *filename;
 368         char buf[MAX_EVENT_NAME_LEN];
 369         struct path path;
 370         unsigned long offset;
 371         bool is_delete, is_return;
 372         int i, ret;
 373
 374         ret = 0;
 375         is_delete = false;
 376         is_return = false;
 377         event = NULL;
 378         group = NULL;
 379
 380         /* argc must be >= 1 */
 381         if (argv[0][0] == '-')
 382                 is_delete = true;
 383         else if (argv[0][0] == 'r')
 384                 is_return = true;
 385         else if (argv[0][0] != 'p') {
 386                 pr_info("Probe definition must be started with 'p', 'r' or '-'.\n");
 387                 return -EINVAL;
 388         }
 389
 390         if (argv[0][1] == ':') {
 391                 event = &argv[0][2];
 392                 arg = strchr(event, '/');
 393
 394                 if (arg) {
 395                         group = event;
 396                         event = arg + 1;
 397                         event[-1] = '\0';
 398
 399                         if (strlen(group) == 0) {
 400                                 pr_info("Group name is not specified\n");
 401                                 return -EINVAL;
 402                         }
 403                 }
 404                 if (strlen(event) == 0) {
 405                         pr_info("Event name is not specified\n");
 406                         return -EINVAL;
 407                 }
 408         }
 409         if (!group)
 410                 group = UPROBE_EVENT_SYSTEM;
 411
 412         if (is_delete) {
 413                 int ret;
 414
 415                 if (!event) {
 416                         pr_info("Delete command needs an event name.\n");
 417                         return -EINVAL;
 418                 }
 419                 mutex_lock(&uprobe_lock);
 420                 tu = find_probe_event(event, group);
 421
 422                 if (!tu) {
 423                         mutex_unlock(&uprobe_lock);
 424                         pr_info("Event %s/%s doesn't exist.\n", group, event);
 425                         return -ENOENT;
 426                 }
 427                 /* delete an event */
 428                 ret = unregister_trace_uprobe(tu);
 429                 mutex_unlock(&uprobe_lock);
 430                 return ret;
 431         }
 432
 433         if (argc < 2) {
 434                 pr_info("Probe point is not specified.\n");
 435                 return -EINVAL;
 436         }
 437         /* Find the last occurrence, in case the path contains ':' too. */
 438         arg = strrchr(argv[1], ':');
 439         if (!arg)
 440                 return -EINVAL;
 441
 442         *arg++ = '\0';
 443         filename = argv[1];
 444         ret = kern_path(filename, LOOKUP_FOLLOW, &path);
 445         if (ret)
 446                 return ret;
 447
 448         if (!d_is_reg(path.dentry)) {
 449                 ret = -EINVAL;
 450                 goto fail_address_parse;
 451         }
 452
 453         ret = kstrtoul(arg, 0, &offset);
 454         if (ret)
 455                 goto fail_address_parse;
 456
 457         argc -= 2;
 458         argv += 2;
 459
 460         /* setup a probe */
 461         if (!event) {
 462                 char *tail;
 463                 char *ptr;
 464
 465                 tail = kstrdup(kbasename(filename), GFP_KERNEL);
 466                 if (!tail) {
 467                         ret = -ENOMEM;
 468                         goto fail_address_parse;
 469                 }
 470
 471                 ptr = strpbrk(tail, ".-_");
 472                 if (ptr)
 473                         *ptr = '\0';
 474
 475                 snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
 476                 event = buf;
 477                 kfree(tail);
 478         }
 479
 480         tu = alloc_trace_uprobe(group, event, argc, is_return);
 481         if (IS_ERR(tu)) {
 482                 pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
 483                 ret = PTR_ERR(tu);
 484                 goto fail_address_parse;
 485         }
 486         tu->offset = offset;
 487         tu->path = path;
 488         tu->filename = kstrdup(filename, GFP_KERNEL);
 489
 490         if (!tu->filename) {
 491                 pr_info("Failed to allocate filename.\n");
 492                 ret = -ENOMEM;
 493                 goto error;
 494         }
 495
 496         /* parse arguments */
 497         ret = 0;
 498         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
 499                 struct probe_arg *parg = &tu->tp.args[i];
 500
 501                 /* Increment count for freeing args in error case */
 502                 tu->tp.nr_args++;
 503
 504                 /* Parse argument name */
 505                 arg = strchr(argv[i], '=');
 506                 if (arg) {
 507                         *arg++ = '\0';
 508                         parg->name = kstrdup(argv[i], GFP_KERNEL);
 509                 } else {
 510                         arg = argv[i];
 511                         /* If argument name is omitted, set "argN" */
 512                         snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
 513                         parg->name = kstrdup(buf, GFP_KERNEL);
 514                 }
 515
 516                 if (!parg->name) {
 517                         pr_info("Failed to allocate argument[%d] name.\n", i);
 518                         ret = -ENOMEM;
 519                         goto error;
 520                 }
 521
 522                 if (!is_good_name(parg->name)) {
 523                         pr_info("Invalid argument[%d] name: %s\n", i, parg->name);
 524                         ret = -EINVAL;
 525                         goto error;
 526                 }
 527
 528                 if (traceprobe_conflict_field_name(parg->name, tu->tp.args, i)) {
 529                         pr_info("Argument[%d] name '%s' conflicts with "
 530                                 "another field.\n", i, argv[i]);
 531                         ret = -EINVAL;
 532                         goto error;
 533                 }
 534
 535                 /* Parse fetch argument */
 536                 ret = traceprobe_parse_probe_arg(arg, &tu->tp.size, parg,
 537                                                  is_return, false,
 538                                                  uprobes_fetch_type_table);
 539                 if (ret) {
 540                         pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 541                         goto error;
 542                 }
 543         }
 544
 545         ret = register_trace_uprobe(tu);
 546         if (ret)
 547                 goto error;
 548         return 0;
 549
 550 error:
 551         free_trace_uprobe(tu);
 552         return ret;
 553
 554 fail_address_parse:
 555         path_put(&path);
 556
 557         pr_info("Failed to parse address or file.\n");
 558
 559         return ret;
 560 }
 561
 562 static int cleanup_all_probes(void)
 563 {
 564         struct trace_uprobe *tu;
 565         int ret = 0;
 566
 567         mutex_lock(&uprobe_lock);
 568         while (!list_empty(&uprobe_list)) {
 569                 tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
 570                 ret = unregister_trace_uprobe(tu);
 571                 if (ret)
 572                         break;
 573         }
 574         mutex_unlock(&uprobe_lock);
 575         return ret;
 576 }
 577
 578 /* Probes listing interfaces */
 579 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
 580 {
 581         mutex_lock(&uprobe_lock);
 582         return seq_list_start(&uprobe_list, *pos);
 583 }
 584
 585 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
 586 {
 587         return seq_list_next(v, &uprobe_list, pos);
 588 }
 589
 590 static void probes_seq_stop(struct seq_file *m, void *v)
 591 {
 592         mutex_unlock(&uprobe_lock);
 593 }
 594
 595 static int probes_seq_show(struct seq_file *m, void *v)
 596 {
 597         struct trace_uprobe *tu = v;
 598         char c = is_ret_probe(tu) ? 'r' : 'p';
 599         int i;
 600
 601         seq_printf(m, "%c:%s/%s %s:0x%0*lx", c, tu->tp.call.class->system,
 602                         trace_event_name(&tu->tp.call), tu->filename,
 603                         (int)(sizeof(void *) * 2), tu->offset);
 604
 605         for (i = 0; i < tu->tp.nr_args; i++)
 606                 seq_printf(m, " %s=%s", tu->tp.args[i].name, tu->tp.args[i].comm);
 607
 608         seq_putc(m, '\n');
 609         return 0;
 610 }
 611
 612 static const struct seq_operations probes_seq_op = {
 613         .start  = probes_seq_start,
 614         .next   = probes_seq_next,
 615         .stop   = probes_seq_stop,
 616         .show   = probes_seq_show
 617 };
 618
 619 static int probes_open(struct inode *inode, struct file *file)
 620 {
 621         int ret;
 622
 623         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
 624                 ret = cleanup_all_probes();
 625                 if (ret)
 626                         return ret;
 627         }
 628
 629         return seq_open(file, &probes_seq_op);
 630 }
 631
 632 static ssize_t probes_write(struct file *file, const char __user *buffer,
 633                             size_t count, loff_t *ppos)
 634 {
 635         return trace_parse_run_command(file, buffer, count, ppos, create_trace_uprobe);
 636 }
 637
 638 static const struct file_operations uprobe_events_ops = {
 639         .owner          = THIS_MODULE,
 640         .open           = probes_open,
 641         .read           = seq_read,
 642         .llseek         = seq_lseek,
 643         .release        = seq_release,
 644         .write          = probes_write,
 645 };
 646
 647 /* Probes profiling interfaces */
 648 static int probes_profile_seq_show(struct seq_file *m, void *v)
 649 {
 650         struct trace_uprobe *tu = v;
 651
 652         seq_printf(m, "  %s %-44s %15lu\n", tu->filename,
 653                         trace_event_name(&tu->tp.call), tu->nhit);
 654         return 0;
 655 }
 656
 657 static const struct seq_operations profile_seq_op = {
 658         .start  = probes_seq_start,
 659         .next   = probes_seq_next,
 660         .stop   = probes_seq_stop,
 661         .show   = probes_profile_seq_show
 662 };
 663
 664 static int profile_open(struct inode *inode, struct file *file)
 665 {
 666         return seq_open(file, &profile_seq_op);
 667 }
 668
 669 static const struct file_operations uprobe_profile_ops = {
 670         .owner          = THIS_MODULE,
 671         .open           = profile_open,
 672         .read           = seq_read,
 673         .llseek         = seq_lseek,
 674         .release        = seq_release,
 675 };
 676
 677 struct uprobe_cpu_buffer {
 678         struct mutex mutex;
 679         void *buf;
 680 };
 681 static struct uprobe_cpu_buffer __percpu *uprobe_cpu_buffer;
 682 static int uprobe_buffer_refcnt;
 683
 684 static int uprobe_buffer_init(void)
 685 {
 686         int cpu, err_cpu;
 687
 688         uprobe_cpu_buffer = alloc_percpu(struct uprobe_cpu_buffer);
 689         if (uprobe_cpu_buffer == NULL)
 690                 return -ENOMEM;
 691
 692         for_each_possible_cpu(cpu) {
 693                 struct page *p = alloc_pages_node(cpu_to_node(cpu),
 694                                                   GFP_KERNEL, 0);
 695                 if (p == NULL) {
 696                         err_cpu = cpu;
 697                         goto err;
 698                 }
 699                 per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf = page_address(p);
 700                 mutex_init(&per_cpu_ptr(uprobe_cpu_buffer, cpu)->mutex);
 701         }
 702
 703         return 0;
 704
 705 err:
 706         for_each_possible_cpu(cpu) {
 707                 if (cpu == err_cpu)
 708                         break;
 709                 free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf);
 710         }
 711
 712         free_percpu(uprobe_cpu_buffer);
 713         return -ENOMEM;
 714 }
 715
 716 static int uprobe_buffer_enable(void)
 717 {
 718         int ret = 0;
 719
 720         BUG_ON(!mutex_is_locked(&event_mutex));
 721
 722         if (uprobe_buffer_refcnt++ == 0) {
 723                 ret = uprobe_buffer_init();
 724                 if (ret < 0)
 725                         uprobe_buffer_refcnt--;
 726         }
 727
 728         return ret;
 729 }
 730
 731 static void uprobe_buffer_disable(void)
 732 {
 733         int cpu;
 734
 735         BUG_ON(!mutex_is_locked(&event_mutex));
 736
 737         if (--uprobe_buffer_refcnt == 0) {
 738                 for_each_possible_cpu(cpu)
 739                         free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer,
 740                                                              cpu)->buf);
 741
 742                 free_percpu(uprobe_cpu_buffer);
 743                 uprobe_cpu_buffer = NULL;
 744         }
 745 }
 746
 747 static struct uprobe_cpu_buffer *uprobe_buffer_get(void)
 748 {
 749         struct uprobe_cpu_buffer *ucb;
 750         int cpu;
 751
 752         cpu = raw_smp_processor_id();
 753         ucb = per_cpu_ptr(uprobe_cpu_buffer, cpu);
 754
 755         /*
 756          * Use per-cpu buffers for fastest access, but we might migrate
 757          * so the mutex makes sure we have sole access to it.
 758          */
 759         mutex_lock(&ucb->mutex);
 760
 761         return ucb;
 762 }
 763
 764 static void uprobe_buffer_put(struct uprobe_cpu_buffer *ucb)
 765 {
 766         mutex_unlock(&ucb->mutex);
 767 }
 768
 769 static void __uprobe_trace_func(struct trace_uprobe *tu,
 770                                 unsigned long func, struct pt_regs *regs,
 771                                 struct uprobe_cpu_buffer *ucb, int dsize,
 772                                 struct trace_event_file *trace_file)
 773 {
 774         struct uprobe_trace_entry_head *entry;
 775         struct ring_buffer_event *event;
 776         struct ring_buffer *buffer;
 777         void *data;
 778         int size, esize;
 779         struct trace_event_call *call = &tu->tp.call;
 780
 781         WARN_ON(call != trace_file->event_call);
 782
 783         if (WARN_ON_ONCE(tu->tp.size + dsize > PAGE_SIZE))
 784                 return;
 785
 786         if (trace_trigger_soft_disabled(trace_file))
 787                 return;
 788
 789         esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
 790         size = esize + tu->tp.size + dsize;
 791         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
 792                                                 call->event.type, size, 0, 0);
 793         if (!event)
 794                 return;
 795
 796         entry = ring_buffer_event_data(event);
 797         if (is_ret_probe(tu)) {
 798                 entry->vaddr[0] = func;
 799                 entry->vaddr[1] = instruction_pointer(regs);
 800                 data = DATAOF_TRACE_ENTRY(entry, true);
 801         } else {
 802                 entry->vaddr[0] = instruction_pointer(regs);
 803                 data = DATAOF_TRACE_ENTRY(entry, false);
 804         }
 805
 806         memcpy(data, ucb->buf, tu->tp.size + dsize);
 807
 808         event_trigger_unlock_commit(trace_file, buffer, event, entry, 0, 0);
 809 }
 810
 811 /* uprobe handler */
 812 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
 813                              struct uprobe_cpu_buffer *ucb, int dsize)
 814 {
 815         struct event_file_link *link;
 816
 817         if (is_ret_probe(tu))
 818                 return 0;
 819
 820         rcu_read_lock();
 821         list_for_each_entry_rcu(link, &tu->tp.files, list)
 822                 __uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
 823         rcu_read_unlock();
 824
 825         return 0;
 826 }
 827
 828 static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
 829                                  struct pt_regs *regs,
 830                                  struct uprobe_cpu_buffer *ucb, int dsize)
 831 {
 832         struct event_file_link *link;
 833
 834         rcu_read_lock();
 835         list_for_each_entry_rcu(link, &tu->tp.files, list)
 836                 __uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
 837         rcu_read_unlock();
 838 }
 839
 840 /* Event entry printers */
 841 static enum print_line_t
 842 print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
 843 {
 844         struct uprobe_trace_entry_head *entry;
 845         struct trace_seq *s = &iter->seq;
 846         struct trace_uprobe *tu;
 847         u8 *data;
 848         int i;
 849
 850         entry = (struct uprobe_trace_entry_head *)iter->ent;
 851         tu = container_of(event, struct trace_uprobe, tp.call.event);
 852
 853         if (is_ret_probe(tu)) {
 854                 trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
 855                                  trace_event_name(&tu->tp.call),
 856                                  entry->vaddr[1], entry->vaddr[0]);
 857                 data = DATAOF_TRACE_ENTRY(entry, true);
 858         } else {
 859                 trace_seq_printf(s, "%s: (0x%lx)",
 860                                  trace_event_name(&tu->tp.call),
 861                                  entry->vaddr[0]);
 862                 data = DATAOF_TRACE_ENTRY(entry, false);
 863         }
 864
 865         for (i = 0; i < tu->tp.nr_args; i++) {
 866                 struct probe_arg *parg = &tu->tp.args[i];
 867
 868                 if (!parg->type->print(s, parg->name, data + parg->offset, entry))
 869                         goto out;
 870         }
 871
 872         trace_seq_putc(s, '\n');
 873
 874  out:
 875         return trace_handle_return(s);
 876 }
 877
 878 typedef bool (*filter_func_t)(struct uprobe_consumer *self,
 879                                 enum uprobe_filter_ctx ctx,
 880                                 struct mm_struct *mm);
 881
 882 static int
 883 probe_event_enable(struct trace_uprobe *tu, struct trace_event_file *file,
 884                    filter_func_t filter)
 885 {
 886         bool enabled = trace_probe_is_enabled(&tu->tp);
 887         struct event_file_link *link = NULL;
 888         int ret;
 889
 890         if (file) {
 891                 if (tu->tp.flags & TP_FLAG_PROFILE)
 892                         return -EINTR;
 893
 894                 link = kmalloc(sizeof(*link), GFP_KERNEL);
 895                 if (!link)
 896                         return -ENOMEM;
 897
 898                 link->file = file;
 899                 list_add_tail_rcu(&link->list, &tu->tp.files);
 900
 901                 tu->tp.flags |= TP_FLAG_TRACE;
 902         } else {
 903                 if (tu->tp.flags & TP_FLAG_TRACE)
 904                         return -EINTR;
 905
 906                 tu->tp.flags |= TP_FLAG_PROFILE;
 907         }
 908
 909         WARN_ON(!uprobe_filter_is_empty(&tu->filter));
 910
 911         if (enabled)
 912                 return 0;
 913
 914         ret = uprobe_buffer_enable();
 915         if (ret)
 916                 goto err_flags;
 917
 918         tu->consumer.filter = filter;
 919         tu->inode = d_real_inode(tu->path.dentry);
 920         ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
 921         if (ret)
 922                 goto err_buffer;
 923
 924         return 0;
 925
 926  err_buffer:
 927         uprobe_buffer_disable();
 928
 929  err_flags:
 930         if (file) {
 931                 list_del(&link->list);
 932                 kfree(link);
 933                 tu->tp.flags &= ~TP_FLAG_TRACE;
 934         } else {
 935                 tu->tp.flags &= ~TP_FLAG_PROFILE;
 936         }
 937         return ret;
 938 }
 939
 940 static void
 941 probe_event_disable(struct trace_uprobe *tu, struct trace_event_file *file)
 942 {
 943         if (!trace_probe_is_enabled(&tu->tp))
 944                 return;
 945
 946         if (file) {
 947                 struct event_file_link *link;
 948
 949                 link = find_event_file_link(&tu->tp, file);
 950                 if (!link)
 951                         return;
 952
 953                 list_del_rcu(&link->list);
 954                 /* synchronize with u{,ret}probe_trace_func */
 955                 synchronize_sched();
 956                 kfree(link);
 957
 958                 if (!list_empty(&tu->tp.files))
 959                         return;
 960         }
 961
 962         WARN_ON(!uprobe_filter_is_empty(&tu->filter));
 963
 964         uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
 965         tu->inode = NULL;
 966         tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
 967
 968         uprobe_buffer_disable();
 969 }
 970
 971 static int uprobe_event_define_fields(struct trace_event_call *event_call)
 972 {
 973         int ret, i, size;
 974         struct uprobe_trace_entry_head field;
 975         struct trace_uprobe *tu = event_call->data;
 976
 977         if (is_ret_probe(tu)) {
 978                 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_FUNC, 0);
 979                 DEFINE_FIELD(unsigned long, vaddr[1], FIELD_STRING_RETIP, 0);
 980                 size = SIZEOF_TRACE_ENTRY(true);
 981         } else {
 982                 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
 983                 size = SIZEOF_TRACE_ENTRY(false);
 984         }
 985         /* Set argument names as fields */
 986         for (i = 0; i < tu->tp.nr_args; i++) {
 987                 struct probe_arg *parg = &tu->tp.args[i];
 988
 989                 ret = trace_define_field(event_call, parg->type->fmttype,
 990                                          parg->name, size + parg->offset,
 991                                          parg->type->size, parg->type->is_signed,
 992                                          FILTER_OTHER);
 993
 994                 if (ret)
 995                         return ret;
 996         }
 997         return 0;
 998 }
 999
1000 #ifdef CONFIG_PERF_EVENTS
1001 static bool
1002 __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
1003 {
1004         struct perf_event *event;
1005
1006         if (filter->nr_systemwide)
1007                 return true;
1008
1009         list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
1010                 if (event->hw.target->mm == mm)
1011                         return true;
1012         }
1013
1014         return false;
1015 }
1016
1017 static inline bool
1018 uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
1019 {
1020         return __uprobe_perf_filter(&tu->filter, event->hw.target->mm);
1021 }
1022
1023 static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
1024 {
1025         bool done;
1026
1027         write_lock(&tu->filter.rwlock);
1028         if (event->hw.target) {
1029                 list_del(&event->hw.tp_list);
1030                 done = tu->filter.nr_systemwide ||
1031                         (event->hw.target->flags & PF_EXITING) ||
1032                         uprobe_filter_event(tu, event);
1033         } else {
1034                 tu->filter.nr_systemwide--;
1035                 done = tu->filter.nr_systemwide;
1036         }
1037         write_unlock(&tu->filter.rwlock);
1038
1039         if (!done)
1040                 return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
1041
1042         return 0;
1043 }
1044
1045 static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
1046 {
1047         bool done;
1048         int err;
1049
1050         write_lock(&tu->filter.rwlock);
1051         if (event->hw.target) {
1052                 /*
1053                  * event->parent != NULL means copy_process(), we can avoid
1054                  * uprobe_apply(). current->mm must be probed and we can rely
1055                  * on dup_mmap() which preserves the already installed bp's.
1056                  *
1057                  * attr.enable_on_exec means that exec/mmap will install the
1058                  * breakpoints we need.
1059                  */
1060                 done = tu->filter.nr_systemwide ||
1061                         event->parent || event->attr.enable_on_exec ||
1062                         uprobe_filter_event(tu, event);
1063                 list_add(&event->hw.tp_list, &tu->filter.perf_events);
1064         } else {
1065                 done = tu->filter.nr_systemwide;
1066                 tu->filter.nr_systemwide++;
1067         }
1068         write_unlock(&tu->filter.rwlock);
1069
1070         err = 0;
1071         if (!done) {
1072                 err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
1073                 if (err)
1074                         uprobe_perf_close(tu, event);
1075         }
1076         return err;
1077 }
1078
1079 static bool uprobe_perf_filter(struct uprobe_consumer *uc,
1080                                 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
1081 {
1082         struct trace_uprobe *tu;
1083         int ret;
1084
1085         tu = container_of(uc, struct trace_uprobe, consumer);
1086         read_lock(&tu->filter.rwlock);
1087         ret = __uprobe_perf_filter(&tu->filter, mm);
1088         read_unlock(&tu->filter.rwlock);
1089
1090         return ret;
1091 }
1092
1093 static void __uprobe_perf_func(struct trace_uprobe *tu,
1094                                unsigned long func, struct pt_regs *regs,
1095                                struct uprobe_cpu_buffer *ucb, int dsize)
1096 {
1097         struct trace_event_call *call = &tu->tp.call;
1098         struct uprobe_trace_entry_head *entry;
1099         struct hlist_head *head;
1100         void *data;
1101         int size, esize;
1102         int rctx;
1103
1104         if (bpf_prog_array_valid(call) && !trace_call_bpf(call, regs))
1105                 return;
1106
1107         esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1108
1109         size = esize + tu->tp.size + dsize;
1110         size = ALIGN(size + sizeof(u32), sizeof(u64)) - sizeof(u32);
1111         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
1112                 return;
1113
1114         preempt_disable();
1115         head = this_cpu_ptr(call->perf_events);
1116         if (hlist_empty(head))
1117                 goto out;
1118
1119         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1120         if (!entry)
1121                 goto out;
1122
1123         if (is_ret_probe(tu)) {
1124                 entry->vaddr[0] = func;
1125                 entry->vaddr[1] = instruction_pointer(regs);
1126                 data = DATAOF_TRACE_ENTRY(entry, true);
1127         } else {
1128                 entry->vaddr[0] = instruction_pointer(regs);
1129                 data = DATAOF_TRACE_ENTRY(entry, false);
1130         }
1131
1132         memcpy(data, ucb->buf, tu->tp.size + dsize);
1133
1134         if (size - esize > tu->tp.size + dsize) {
1135                 int len = tu->tp.size + dsize;
1136
1137                 memset(data + len, 0, size - esize - len);
1138         }
1139
1140         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1141                               head, NULL);
1142  out:
1143         preempt_enable();
1144 }
1145
1146 /* uprobe profile handler */
1147 static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs,
1148                             struct uprobe_cpu_buffer *ucb, int dsize)
1149 {
1150         if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
1151                 return UPROBE_HANDLER_REMOVE;
1152
1153         if (!is_ret_probe(tu))
1154                 __uprobe_perf_func(tu, 0, regs, ucb, dsize);
1155         return 0;
1156 }
1157
1158 static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
1159                                 struct pt_regs *regs,
1160                                 struct uprobe_cpu_buffer *ucb, int dsize)
1161 {
1162         __uprobe_perf_func(tu, func, regs, ucb, dsize);
1163 }
1164
1165 int bpf_get_uprobe_info(const struct perf_event *event, u32 *fd_type,
1166                         const char **filename, u64 *probe_offset,
1167                         bool perf_type_tracepoint)
1168 {
1169         const char *pevent = trace_event_name(event->tp_event);
1170         const char *group = event->tp_event->class->system;
1171         struct trace_uprobe *tu;
1172
1173         if (perf_type_tracepoint)
1174                 tu = find_probe_event(pevent, group);
1175         else
1176                 tu = event->tp_event->data;
1177         if (!tu)
1178                 return -EINVAL;
1179
1180         *fd_type = is_ret_probe(tu) ? BPF_FD_TYPE_URETPROBE
1181                                     : BPF_FD_TYPE_UPROBE;
1182         *filename = tu->filename;
1183         *probe_offset = tu->offset;
1184         return 0;
1185 }
1186 #endif  /* CONFIG_PERF_EVENTS */
1187
1188 static int
1189 trace_uprobe_register(struct trace_event_call *event, enum trace_reg type,
1190                       void *data)
1191 {
1192         struct trace_uprobe *tu = event->data;
1193         struct trace_event_file *file = data;
1194
1195         switch (type) {
1196         case TRACE_REG_REGISTER:
1197                 return probe_event_enable(tu, file, NULL);
1198
1199         case TRACE_REG_UNREGISTER:
1200                 probe_event_disable(tu, file);
1201                 return 0;
1202
1203 #ifdef CONFIG_PERF_EVENTS
1204         case TRACE_REG_PERF_REGISTER:
1205                 return probe_event_enable(tu, NULL, uprobe_perf_filter);
1206
1207         case TRACE_REG_PERF_UNREGISTER:
1208                 probe_event_disable(tu, NULL);
1209                 return 0;
1210
1211         case TRACE_REG_PERF_OPEN:
1212                 return uprobe_perf_open(tu, data);
1213
1214         case TRACE_REG_PERF_CLOSE:
1215                 return uprobe_perf_close(tu, data);
1216
1217 #endif
1218         default:
1219                 return 0;
1220         }
1221         return 0;
1222 }
1223
1224 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
1225 {
1226         struct trace_uprobe *tu;
1227         struct uprobe_dispatch_data udd;
1228         struct uprobe_cpu_buffer *ucb;
1229         int dsize, esize;
1230         int ret = 0;
1231
1232
1233         tu = container_of(con, struct trace_uprobe, consumer);
1234         tu->nhit++;
1235
1236         udd.tu = tu;
1237         udd.bp_addr = instruction_pointer(regs);
1238
1239         current->utask->vaddr = (unsigned long) &udd;
1240
1241         if (WARN_ON_ONCE(!uprobe_cpu_buffer))
1242                 return 0;
1243
1244         dsize = __get_data_size(&tu->tp, regs);
1245         esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1246
1247         ucb = uprobe_buffer_get();
1248         store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
1249
1250         if (tu->tp.flags & TP_FLAG_TRACE)
1251                 ret |= uprobe_trace_func(tu, regs, ucb, dsize);
1252
1253 #ifdef CONFIG_PERF_EVENTS
1254         if (tu->tp.flags & TP_FLAG_PROFILE)
1255                 ret |= uprobe_perf_func(tu, regs, ucb, dsize);
1256 #endif
1257         uprobe_buffer_put(ucb);
1258         return ret;
1259 }
1260
1261 static int uretprobe_dispatcher(struct uprobe_consumer *con,
1262                                 unsigned long func, struct pt_regs *regs)
1263 {
1264         struct trace_uprobe *tu;
1265         struct uprobe_dispatch_data udd;
1266         struct uprobe_cpu_buffer *ucb;
1267         int dsize, esize;
1268
1269         tu = container_of(con, struct trace_uprobe, consumer);
1270
1271         udd.tu = tu;
1272         udd.bp_addr = func;
1273
1274         current->utask->vaddr = (unsigned long) &udd;
1275
1276         if (WARN_ON_ONCE(!uprobe_cpu_buffer))
1277                 return 0;
1278
1279         dsize = __get_data_size(&tu->tp, regs);
1280         esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1281
1282         ucb = uprobe_buffer_get();
1283         store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
1284
1285         if (tu->tp.flags & TP_FLAG_TRACE)
1286                 uretprobe_trace_func(tu, func, regs, ucb, dsize);
1287
1288 #ifdef CONFIG_PERF_EVENTS
1289         if (tu->tp.flags & TP_FLAG_PROFILE)
1290                 uretprobe_perf_func(tu, func, regs, ucb, dsize);
1291 #endif
1292         uprobe_buffer_put(ucb);
1293         return 0;
1294 }
1295
1296 static struct trace_event_functions uprobe_funcs = {
1297         .trace          = print_uprobe_event
1298 };
1299
1300 static inline void init_trace_event_call(struct trace_uprobe *tu,
1301                                          struct trace_event_call *call)
1302 {
1303         INIT_LIST_HEAD(&call->class->fields);
1304         call->event.funcs = &uprobe_funcs;
1305         call->class->define_fields = uprobe_event_define_fields;
1306
1307         call->flags = TRACE_EVENT_FL_UPROBE;
1308         call->class->reg = trace_uprobe_register;
1309         call->data = tu;
1310 }
1311
1312 static int register_uprobe_event(struct trace_uprobe *tu)
1313 {
1314         struct trace_event_call *call = &tu->tp.call;
1315         int ret = 0;
1316
1317         init_trace_event_call(tu, call);
1318
1319         if (set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0)
1320                 return -ENOMEM;
1321
1322         ret = register_trace_event(&call->event);
1323         if (!ret) {
1324                 kfree(call->print_fmt);
1325                 return -ENODEV;
1326         }
1327
1328         ret = trace_add_event_call(call);
1329
1330         if (ret) {
1331                 pr_info("Failed to register uprobe event: %s\n",
1332                         trace_event_name(call));
1333                 kfree(call->print_fmt);
1334                 unregister_trace_event(&call->event);
1335         }
1336
1337         return ret;
1338 }
1339
1340 static int unregister_uprobe_event(struct trace_uprobe *tu)
1341 {
1342         int ret;
1343
1344         /* tu->event is unregistered in trace_remove_event_call() */
1345         ret = trace_remove_event_call(&tu->tp.call);
1346         if (ret)
1347                 return ret;
1348         kfree(tu->tp.call.print_fmt);
1349         tu->tp.call.print_fmt = NULL;
1350         return 0;
1351 }
1352
1353 #ifdef CONFIG_PERF_EVENTS
1354 struct trace_event_call *
1355 create_local_trace_uprobe(char *name, unsigned long offs, bool is_return)
1356 {
1357         struct trace_uprobe *tu;
1358         struct path path;
1359         int ret;
1360
1361         ret = kern_path(name, LOOKUP_FOLLOW, &path);
1362         if (ret)
1363                 return ERR_PTR(ret);
1364
1365         if (!d_is_reg(path.dentry)) {
1366                 path_put(&path);
1367                 return ERR_PTR(-EINVAL);
1368         }
1369
1370         /*
1371          * local trace_kprobes are not added to probe_list, so they are never
1372          * searched in find_trace_kprobe(). Therefore, there is no concern of
1373          * duplicated name "DUMMY_EVENT" here.
1374          */
1375         tu = alloc_trace_uprobe(UPROBE_EVENT_SYSTEM, "DUMMY_EVENT", 0,
1376                                 is_return);
1377
1378         if (IS_ERR(tu)) {
1379                 pr_info("Failed to allocate trace_uprobe.(%d)\n",
1380                         (int)PTR_ERR(tu));
1381                 path_put(&path);
1382                 return ERR_CAST(tu);
1383         }
1384
1385         tu->offset = offs;
1386         tu->path = path;
1387         tu->filename = kstrdup(name, GFP_KERNEL);
1388         init_trace_event_call(tu, &tu->tp.call);
1389
1390         if (set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0) {
1391                 ret = -ENOMEM;
1392                 goto error;
1393         }
1394
1395         return &tu->tp.call;
1396 error:
1397         free_trace_uprobe(tu);
1398         return ERR_PTR(ret);
1399 }
1400
1401 void destroy_local_trace_uprobe(struct trace_event_call *event_call)
1402 {
1403         struct trace_uprobe *tu;
1404
1405         tu = container_of(event_call, struct trace_uprobe, tp.call);
1406
1407         kfree(tu->tp.call.print_fmt);
1408         tu->tp.call.print_fmt = NULL;
1409
1410         free_trace_uprobe(tu);
1411 }
1412 #endif /* CONFIG_PERF_EVENTS */
1413
1414 /* Make a trace interface for controling probe points */
1415 static __init int init_uprobe_trace(void)
1416 {
1417         struct dentry *d_tracer;
1418
1419         d_tracer = tracing_init_dentry();
1420         if (IS_ERR(d_tracer))
1421                 return 0;
1422
1423         trace_create_file("uprobe_events", 0644, d_tracer,
1424                                     NULL, &uprobe_events_ops);
1425         /* Profile interface */
1426         trace_create_file("uprobe_profile", 0444, d_tracer,
1427                                     NULL, &uprobe_profile_ops);
1428         return 0;
1429 }
1430
1431 fs_initcall(init_uprobe_trace);