uprobe/swap_uprobes.c

   1 /*
   2  *  Dynamic Binary Instrumentation Module based on KProbes
   3  *  modules/uprobe/swap_uprobes.h
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  *
  19  * Copyright (C) Samsung Electronics, 2006-2010
  20  *
  21  * 2008-2009    Alexey Gerenkov <a.gerenkov@samsung.com> User-Space
  22  *              Probes initial implementation; Support x86/ARM/MIPS for both user and kernel spaces.
  23  * 2010         Ekaterina Gorelkina <e.gorelkina@samsung.com>: redesign module for separating core and arch parts
  24  *
  25  */
  26
  27
  28 #include "swap_uprobes.h"
  29 #include <kprobe/dbi_kdebug.h>
  30
  31 #include <uprobe/arch/asm/swap_uprobes.h>
  32
  33 #include <linux/hash.h>
  34 #include <linux/mempolicy.h>
  35 #include <linux/module.h>
  36 #include <kprobe/dbi_insn_slots.h>
  37 #include <kprobe/dbi_kprobes_deps.h>
  38
  39 enum {
  40         UPROBE_HASH_BITS  = 10,
  41         UPROBE_TABLE_SIZE = (1 << UPROBE_HASH_BITS)
  42 };
  43
  44 struct hlist_head uprobe_insn_slot_table[UPROBE_TABLE_SIZE];
  45 struct hlist_head uprobe_table[UPROBE_TABLE_SIZE];
  46
  47 DEFINE_SPINLOCK(uretprobe_lock);        /* Protects uretprobe_inst_table */
  48 static struct hlist_head uretprobe_inst_table[UPROBE_TABLE_SIZE];
  49
  50 #define DEBUG_PRINT_HASH_TABLE 0
  51
  52 #if DEBUG_PRINT_HASH_TABLE
  53 void print_kprobe_hash_table(void)
  54 {
  55         int i;
  56         struct hlist_head *head;
  57         struct kprobe *p;
  58         DECLARE_NODE_PTR_FOR_HLIST(node);
  59
  60         // print uprobe table
  61         for (i = 0; i < KPROBE_TABLE_SIZE; ++i) {
  62                 head = &kprobe_table[i];
  63                 swap_hlist_for_each_entry_rcu(p, node, head, is_hlist_arm) {
  64                         printk("####### find K tgid=%u, addr=%x\n",
  65                                         p->tgid, p->addr);
  66                 }
  67         }
  68 }
  69
  70 void print_kretprobe_hash_table(void)
  71 {
  72         int i;
  73         struct hlist_head *head;
  74         struct kprobe *p;
  75         DECLARE_NODE_PTR_FOR_HLIST(node);
  76
  77         // print uprobe table
  78         for (i = 0; i < KPROBE_TABLE_SIZE; ++i) {
  79                 head = &kretprobe_inst_table[i];
  80                 swap_hlist_for_each_entry_rcu(p, node, head, is_hlist_arm) {
  81                         printk("####### find KR tgid=%u, addr=%x\n",
  82                                         p->tgid, p->addr);
  83                 }
  84         }
  85 }
  86
  87 void print_uprobe_hash_table(void)
  88 {
  89         int i;
  90         struct hlist_head *head;
  91         struct kprobe *p;
  92         DECLARE_NODE_PTR_FOR_HLIST(node);
  93
  94         // print uprobe table
  95         for (i = 0; i < UPROBE_TABLE_SIZE; ++i) {
  96                 head = &uprobe_insn_slot_table[i];
  97                 swap_hlist_for_each_entry_rcu(p, node, head, is_hlist_arm) {
  98                         printk("####### find U tgid=%u, addr=%x\n",
  99                                         p->tgid, p->addr);
 100                 }
 101         }
 102 }
 103 #endif
 104
 105 /*
 106  * Keep all fields in the uprobe consistent
 107  */
 108 static inline void copy_uprobe(struct kprobe *old_p, struct kprobe *p)
 109 {
 110         memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
 111         memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
 112         p->ss_addr = old_p->ss_addr;
 113 #ifdef CONFIG_ARM
 114         p->safe_arm = old_p->safe_arm;
 115         p->safe_thumb = old_p->safe_thumb;
 116 #endif
 117 }
 118
 119 /*
 120  * Aggregate handlers for multiple uprobes support - these handlers
 121  * take care of invoking the individual uprobe handlers on p->list
 122  */
 123 static int aggr_pre_uhandler(struct kprobe *p, struct pt_regs *regs)
 124 {
 125         struct kprobe *kp;
 126         int ret;
 127
 128         list_for_each_entry_rcu(kp, &p->list, list) {
 129                 if (kp->pre_handler) {
 130                         ret = kp->pre_handler(kp, regs);
 131                         if (ret) {
 132                                 return ret;
 133                         }
 134                 }
 135         }
 136
 137         return 0;
 138 }
 139
 140 static void aggr_post_uhandler(struct kprobe *p, struct pt_regs *regs, unsigned long flags)
 141 {
 142         struct kprobe *kp;
 143
 144         list_for_each_entry_rcu(kp, &p->list, list) {
 145                 if (kp->post_handler) {
 146                         kp->post_handler(kp, regs, flags);
 147                 }
 148         }
 149 }
 150
 151 static int aggr_fault_uhandler(struct kprobe *p, struct pt_regs *regs, int trapnr)
 152 {
 153         return 0;
 154 }
 155
 156 static int aggr_break_uhandler(struct kprobe *p, struct pt_regs *regs)
 157 {
 158         return 0;
 159 }
 160
 161 /*
 162  * Add the new probe to old_p->list. Fail if this is the
 163  * second ujprobe at the address - two ujprobes can't coexist
 164  */
 165 static int add_new_uprobe(struct kprobe *old_p, struct kprobe *p)
 166 {
 167         if (p->break_handler) {
 168                 if (old_p->break_handler) {
 169                         return -EEXIST;
 170                 }
 171
 172                 list_add_tail_rcu(&p->list, &old_p->list);
 173                 old_p->break_handler = aggr_break_uhandler;
 174         } else {
 175                 list_add_rcu (&p->list, &old_p->list);
 176         }
 177
 178         if (p->post_handler && !old_p->post_handler) {
 179                 old_p->post_handler = aggr_post_uhandler;
 180         }
 181
 182         return 0;
 183 }
 184
 185 /*
 186  * Fill in the required fields of the "manager uprobe". Replace the
 187  * earlier uprobe in the hlist with the manager uprobe
 188  */
 189 static inline void add_aggr_uprobe(struct kprobe *ap, struct kprobe *p)
 190 {
 191         copy_uprobe(p, ap);
 192
 193         ap->addr = p->addr;
 194         ap->pre_handler = aggr_pre_uhandler;
 195         ap->fault_handler = aggr_fault_uhandler;
 196
 197         if (p->post_handler) {
 198                 ap->post_handler = aggr_post_uhandler;
 199         }
 200
 201         if (p->break_handler) {
 202                 ap->break_handler = aggr_break_uhandler;
 203         }
 204
 205         INIT_LIST_HEAD(&ap->list);
 206         list_add_rcu(&p->list, &ap->list);
 207
 208         hlist_replace_rcu(&p->hlist, &ap->hlist);
 209 }
 210
 211 /*
 212  * This is the second or subsequent uprobe at the address - handle
 213  * the intricacies
 214  */
 215 static int register_aggr_uprobe(struct kprobe *old_p, struct kprobe *p)
 216 {
 217         int ret = 0;
 218         struct kprobe *ap;
 219
 220         if (old_p->pre_handler == aggr_pre_uhandler) {
 221                 copy_uprobe(old_p, p);
 222                 ret = add_new_uprobe(old_p, p);
 223         } else {
 224                 struct uprobe *uap = kzalloc(sizeof(*uap), GFP_KERNEL);
 225                 if (!uap) {
 226                         return -ENOMEM;
 227                 }
 228
 229                 uap->task = kp2up(p)->task;
 230                 ap = up2kp(uap);
 231                 add_aggr_uprobe(ap, old_p);
 232                 copy_uprobe(ap, p);
 233                 ret = add_new_uprobe(ap, p);
 234         }
 235
 236         return ret;
 237 }
 238
 239 static void arm_uprobe(struct uprobe *p)
 240 {
 241         kprobe_opcode_t insn = BREAKPOINT_INSTRUCTION;
 242         int ret = write_proc_vm_atomic(p->task, (unsigned long)p->kp.addr,
 243                                        &insn, sizeof(insn));
 244         if (!ret) {
 245                 panic("arm_uprobe: failed to write memory "
 246                       "tgid=%u addr=%p!\n", p->task->tgid, p->kp.addr);
 247         }
 248 }
 249
 250 void disarm_uprobe(struct kprobe *p, struct task_struct *task)
 251 {
 252         int ret = write_proc_vm_atomic(task, (unsigned long)p->addr,
 253                                        &p->opcode, sizeof(p->opcode));
 254         if (!ret) {
 255                 panic("disarm_uprobe: failed to write memory "
 256                       "tgid=%u, addr=%p!\n", task->tgid, p->addr);
 257         }
 258 }
 259 EXPORT_SYMBOL_GPL(disarm_uprobe);
 260
 261 static void init_uprobes_insn_slots(void)
 262 {
 263         int i;
 264         for (i = 0; i < UPROBE_TABLE_SIZE; ++i) {
 265                 INIT_HLIST_HEAD(&uprobe_insn_slot_table[i]);
 266         }
 267 }
 268
 269 static void init_uprobe_table(void)
 270 {
 271         int i;
 272         for (i = 0; i < UPROBE_TABLE_SIZE; ++i) {
 273                 INIT_HLIST_HEAD(&uprobe_table[i]);
 274         }
 275 }
 276
 277 static void init_uretprobe_inst_table(void)
 278 {
 279         int i;
 280         for (i = 0; i < UPROBE_TABLE_SIZE; ++i) {
 281                 INIT_HLIST_HEAD (&uretprobe_inst_table[i]);
 282         }
 283 }
 284
 285 struct kprobe *get_ukprobe(void *addr, pid_t tgid)
 286 {
 287         struct hlist_head *head;
 288         struct kprobe *p;
 289         DECLARE_NODE_PTR_FOR_HLIST(node);
 290
 291         head = &uprobe_table[hash_ptr(addr, UPROBE_HASH_BITS)];
 292         swap_hlist_for_each_entry_rcu(p, node, head, hlist) {
 293                 if (p->addr == addr && kp2up(p)->task->tgid == tgid) {
 294                         return p;
 295                 }
 296         }
 297
 298         return NULL;
 299 }
 300
 301 void add_uprobe_table(struct kprobe *p)
 302 {
 303         INIT_HLIST_NODE(&p->is_hlist);
 304         hlist_add_head_rcu(&p->is_hlist, &uprobe_insn_slot_table[hash_ptr(p->ainsn.insn, UPROBE_HASH_BITS)]);
 305 }
 306
 307 struct kprobe *get_ukprobe_by_insn_slot(void *addr, pid_t tgid, struct pt_regs *regs)
 308 {
 309         struct hlist_head *head;
 310         struct kprobe *p;
 311         DECLARE_NODE_PTR_FOR_HLIST(node);
 312
 313         /* TODO: test - two processes invokes instrumented function */
 314         head = &uprobe_insn_slot_table[hash_ptr(addr, UPROBE_HASH_BITS)];
 315         swap_hlist_for_each_entry_rcu(p, node, head, is_hlist) {
 316                 if (p->ainsn.insn == addr && kp2up(p)->task->tgid == tgid) {
 317                         return p;
 318                 }
 319         }
 320
 321         return NULL;
 322 }
 323
 324
 325 static void remove_uprobe(struct uprobe *up)
 326 {
 327         struct kprobe *p = up2kp(up);
 328
 329         free_insn_slot(up->sm, p->ainsn.insn);
 330 }
 331
 332 static struct hlist_head *uretprobe_inst_table_head(void *hash_key)
 333 {
 334         return &uretprobe_inst_table[hash_ptr (hash_key, UPROBE_HASH_BITS)];
 335 }
 336
 337 /* Called with uretprobe_lock held */
 338 static void add_urp_inst(struct uretprobe_instance *ri)
 339 {
 340         /*
 341          * Remove rp inst off the free list -
 342          * Add it back when probed function returns
 343          */
 344         hlist_del(&ri->uflist);
 345
 346         /* Add rp inst onto table */
 347         INIT_HLIST_NODE(&ri->hlist);
 348         hlist_add_head(&ri->hlist, uretprobe_inst_table_head(ri->task->mm));
 349
 350         /* Also add this rp inst to the used list. */
 351         INIT_HLIST_NODE(&ri->uflist);
 352         hlist_add_head(&ri->uflist, &ri->rp->used_instances);
 353 }
 354
 355 /* Called with uretprobe_lock held */
 356 static void recycle_urp_inst(struct uretprobe_instance *ri)
 357 {
 358         if (ri->rp) {
 359                 hlist_del(&ri->hlist);
 360                 /* remove rp inst off the used list */
 361                 hlist_del(&ri->uflist);
 362                 /* put rp inst back onto the free list */
 363                 INIT_HLIST_NODE(&ri->uflist);
 364                 hlist_add_head(&ri->uflist, &ri->rp->free_instances);
 365         }
 366 }
 367
 368 /* Called with uretprobe_lock held */
 369 static struct uretprobe_instance *get_used_urp_inst(struct uretprobe *rp)
 370 {
 371         struct uretprobe_instance *ri;
 372         DECLARE_NODE_PTR_FOR_HLIST(node);
 373
 374         swap_hlist_for_each_entry(ri, node, &rp->used_instances, uflist) {
 375                 return ri;
 376         }
 377
 378         return NULL;
 379 }
 380
 381 /* Called with uretprobe_lock held */
 382 struct uretprobe_instance *get_free_urp_inst_no_alloc(struct uretprobe *rp)
 383 {
 384         struct uretprobe_instance *ri;
 385         DECLARE_NODE_PTR_FOR_HLIST(node);
 386
 387         swap_hlist_for_each_entry(ri, node, &rp->free_instances, uflist) {
 388                 return ri;
 389         }
 390
 391         return NULL;
 392 }
 393
 394 /* Called with uretprobe_lock held */
 395 static void free_urp_inst(struct uretprobe *rp)
 396 {
 397         struct uretprobe_instance *ri;
 398         while ((ri = get_free_urp_inst_no_alloc(rp)) != NULL) {
 399                 hlist_del(&ri->uflist);
 400                 kfree(ri);
 401         }
 402 }
 403
 404 #define COMMON_URP_NR 10
 405
 406 static int alloc_nodes_uretprobe(struct uretprobe *rp)
 407 {
 408         int alloc_nodes;
 409         struct uretprobe_instance *inst;
 410         int i;
 411
 412 #if 1//def CONFIG_PREEMPT
 413         rp->maxactive += max(COMMON_URP_NR, 2 * NR_CPUS);
 414 #else
 415         rp->maxacpptive += NR_CPUS;
 416 #endif
 417         alloc_nodes = COMMON_URP_NR;
 418
 419         for (i = 0; i < alloc_nodes; ++i) {
 420                 inst = kmalloc(sizeof(*inst), GFP_ATOMIC);
 421                 if (inst == NULL) {
 422                         free_urp_inst(rp);
 423                         return -ENOMEM;
 424                 }
 425                 INIT_HLIST_NODE(&inst->uflist);
 426                 hlist_add_head(&inst->uflist, &rp->free_instances);
 427         }
 428
 429         return 0;
 430 }
 431
 432 /* Called with uretprobe_lock held */
 433 static struct uretprobe_instance *get_free_urp_inst(struct uretprobe *rp)
 434 {
 435         struct uretprobe_instance *ri;
 436         DECLARE_NODE_PTR_FOR_HLIST(node);
 437
 438         swap_hlist_for_each_entry(ri, node, &rp->free_instances, uflist) {
 439                 return ri;
 440         }
 441
 442         if (!alloc_nodes_uretprobe(rp)) {
 443                 swap_hlist_for_each_entry(ri, node, &rp->free_instances, uflist) {
 444                         return ri;
 445                 }
 446         }
 447
 448         return NULL;
 449 }
 450 // ===================================================================
 451
 452 int dbi_register_uprobe(struct uprobe *up)
 453 {
 454         int ret = 0;
 455         struct kprobe *p, *old_p;
 456
 457         p = &up->kp;
 458         if (!p->addr) {
 459                 return -EINVAL;
 460         }
 461
 462         DBPRINTF("p->addr = 0x%p p = 0x%p\n", p->addr, p);
 463
 464 // thumb address = address-1;
 465 #if defined(CONFIG_ARM)
 466         // TODO: must be corrected in 'bundle'
 467         if ((unsigned long) p->addr & 0x01) {
 468                 p->addr = (kprobe_opcode_t *)((unsigned long)p->addr & 0xfffffffe);
 469         }
 470 #endif
 471
 472         p->ainsn.insn = NULL;
 473         p->mod_refcounted = 0;
 474         p->nmissed = 0;
 475         INIT_LIST_HEAD(&p->list);
 476 #ifdef KPROBES_PROFILE
 477         p->start_tm.tv_sec = p->start_tm.tv_usec = 0;
 478         p->hnd_tm_sum.tv_sec = p->hnd_tm_sum.tv_usec = 0;
 479         p->count = 0;
 480 #endif
 481
 482         // get the first item
 483         old_p = get_ukprobe(p->addr, kp2up(p)->task->tgid);
 484         if (old_p) {
 485 #ifdef CONFIG_ARM
 486                 p->safe_arm = old_p->safe_arm;
 487                 p->safe_thumb = old_p->safe_thumb;
 488 #endif
 489                 ret = register_aggr_uprobe(old_p, p);
 490                 DBPRINTF("goto out\n", ret);
 491                 goto out;
 492         }
 493
 494         ret = arch_prepare_uprobe(up);
 495         if (ret) {
 496                 DBPRINTF("goto out\n", ret);
 497                 goto out;
 498         }
 499
 500         DBPRINTF ("before out ret = 0x%x\n", ret);
 501
 502         // TODO: add uprobe (must be in function)
 503         INIT_HLIST_NODE(&p->hlist);
 504         hlist_add_head_rcu(&p->hlist, &uprobe_table[hash_ptr(p->addr, UPROBE_HASH_BITS)]);
 505         arm_uprobe(up);
 506
 507 out:
 508         DBPRINTF("out ret = 0x%x\n", ret);
 509         return ret;
 510 }
 511
 512 void __dbi_unregister_uprobe(struct uprobe *up, int disarm)
 513 {
 514         struct kprobe *p, *old_p, *list_p;
 515         int cleanup_p;
 516
 517         p = &up->kp;
 518         old_p = get_ukprobe(p->addr, kp2up(p)->task->tgid);
 519         if (unlikely(!old_p)) {
 520                 return;
 521         }
 522
 523         if (p != old_p) {
 524                 list_for_each_entry_rcu(list_p, &old_p->list, list) {
 525                         if (list_p == p) {
 526                                 /* uprobe p is a valid probe */
 527                                 goto valid_p;
 528                         }
 529                 }
 530
 531                 return;
 532         }
 533
 534 valid_p:
 535         if ((old_p == p) || ((old_p->pre_handler == aggr_pre_uhandler) &&
 536             (p->list.next == &old_p->list) && (p->list.prev == &old_p->list))) {
 537                 /* Only probe on the hash list */
 538                 if (disarm)
 539                         disarm_uprobe(&up->kp, up->task);
 540
 541                 hlist_del_rcu(&old_p->hlist);
 542                 cleanup_p = 1;
 543         } else {
 544                 list_del_rcu(&p->list);
 545                 cleanup_p = 0;
 546         }
 547
 548         if (cleanup_p) {
 549                 if (p != old_p) {
 550                         list_del_rcu(&p->list);
 551                         kfree(old_p);
 552                 }
 553
 554                 if (!in_atomic()) {
 555                         synchronize_sched();
 556                 }
 557
 558                 remove_uprobe(up);
 559         } else {
 560                 if (p->break_handler) {
 561                         old_p->break_handler = NULL;
 562                 }
 563
 564                 if (p->post_handler) {
 565                         list_for_each_entry_rcu (list_p, &old_p->list, list) {
 566                                 if (list_p->post_handler) {
 567                                         cleanup_p = 2;
 568                                         break;
 569                                 }
 570                         }
 571
 572                         if (cleanup_p == 0) {
 573                                 old_p->post_handler = NULL;
 574                         }
 575                 }
 576         }
 577 }
 578 EXPORT_SYMBOL_GPL(__dbi_unregister_uprobe);
 579
 580 void dbi_unregister_uprobe(struct uprobe *up)
 581 {
 582         __dbi_unregister_uprobe(up, 1);
 583 }
 584
 585 int dbi_register_ujprobe(struct ujprobe *jp)
 586 {
 587         int ret = 0;
 588
 589         /* Todo: Verify probepoint is a function entry point */
 590         jp->up.kp.pre_handler = setjmp_upre_handler;
 591         jp->up.kp.break_handler = longjmp_break_uhandler;
 592
 593         ret = dbi_register_uprobe(&jp->up);
 594
 595         return ret;
 596 }
 597
 598 void __dbi_unregister_ujprobe(struct ujprobe *jp, int disarm)
 599 {
 600         __dbi_unregister_uprobe(&jp->up, disarm);
 601         /*
 602          * Here is an attempt to unregister even those probes that have not been
 603          * installed (hence not added to the hlist).
 604          * So if we try to delete them from the hlist we will get NULL pointer
 605          * dereference error. That is why we check whether this node
 606          * really belongs to the hlist.
 607          */
 608         if (!(hlist_unhashed(&jp->up.kp.is_hlist))) {
 609                 hlist_del_rcu(&jp->up.kp.is_hlist);
 610         }
 611 }
 612 EXPORT_SYMBOL_GPL(__dbi_unregister_ujprobe);
 613
 614 void dbi_unregister_ujprobe(struct ujprobe *jp)
 615 {
 616         __dbi_unregister_ujprobe(jp, 1);
 617 }
 618
 619 int trampoline_uprobe_handler(struct kprobe *p, struct pt_regs *regs)
 620 {
 621         struct uretprobe_instance *ri = NULL;
 622         struct hlist_head *head;
 623         unsigned long flags, tramp_addr, orig_ret_addr = 0;
 624         struct hlist_node *tmp;
 625         DECLARE_NODE_PTR_FOR_HLIST(node);
 626
 627         tramp_addr = arch_get_trampoline_addr(p, regs);
 628         spin_lock_irqsave(&uretprobe_lock, flags);
 629
 630         head = uretprobe_inst_table_head(current->mm);
 631
 632         /*
 633          * It is possible to have multiple instances associated with a given
 634          * task either because an multiple functions in the call path
 635          * have a return probe installed on them, and/or more then one
 636          * return probe was registered for a target function.
 637          *
 638          * We can handle this because:
 639          *     - instances are always inserted at the head of the list
 640          *     - when multiple return probes are registered for the same
 641          *       function, the first instance's ret_addr will point to the
 642          *       real return address, and all the rest will point to
 643          *       uretprobe_trampoline
 644          */
 645         swap_hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 646                 if (ri->task != current) {
 647                         /* another task is sharing our hash bucket */
 648                         continue;
 649                 }
 650
 651                 if (ri->rp && ri->rp->handler) {
 652                         ri->rp->handler(ri, regs);
 653                 }
 654
 655                 orig_ret_addr = (unsigned long)ri->ret_addr;
 656                 recycle_urp_inst(ri);
 657
 658                 if (orig_ret_addr != tramp_addr) {
 659                         /*
 660                          * This is the real return address. Any other
 661                          * instances associated with this task are for
 662                          * other calls deeper on the call stack
 663                          */
 664                         break;
 665                 }
 666         }
 667
 668         spin_unlock_irqrestore(&uretprobe_lock, flags);
 669         arch_set_orig_ret_addr(orig_ret_addr, regs);
 670
 671         return 1;
 672 }
 673
 674 static int pre_handler_uretprobe(struct kprobe *p, struct pt_regs *regs)
 675 {
 676         struct uprobe *up = container_of(p, struct uprobe, kp);
 677         struct uretprobe *rp = container_of(up, struct uretprobe, up);
 678 #ifdef CONFIG_ARM
 679         int noret = thumb_mode(regs) ? rp->thumb_noret : rp->arm_noret;
 680 #endif
 681         struct uretprobe_instance *ri;
 682         unsigned long flags;
 683
 684 #ifdef CONFIG_ARM
 685         if (noret)
 686                 return 0;
 687 #endif
 688
 689         /* TODO: consider to only swap the RA after the last pre_handler fired */
 690         spin_lock_irqsave(&uretprobe_lock, flags);
 691
 692         /* TODO: test - remove retprobe after func entry but before its exit */
 693         if ((ri = get_free_urp_inst(rp)) != NULL) {
 694                 ri->rp = rp;
 695                 ri->task = current;
 696
 697                 if (rp->entry_handler)
 698                         rp->entry_handler(ri, regs);
 699
 700                 arch_prepare_uretprobe(ri, regs);
 701
 702                 add_urp_inst(ri);
 703         } else {
 704                 ++rp->nmissed;
 705         }
 706
 707         spin_unlock_irqrestore(&uretprobe_lock, flags);
 708
 709         return 0;
 710 }
 711
 712 int dbi_register_uretprobe(struct uretprobe *rp)
 713 {
 714         int i, ret = 0;
 715         struct uretprobe_instance *inst;
 716
 717         DBPRINTF ("START\n");
 718
 719         rp->up.kp.pre_handler = pre_handler_uretprobe;
 720         rp->up.kp.post_handler = NULL;
 721         rp->up.kp.fault_handler = NULL;
 722         rp->up.kp.break_handler = NULL;
 723
 724         /* Pre-allocate memory for max kretprobe instances */
 725         if (rp->maxactive <= 0) {
 726 #if 1//def CONFIG_PREEMPT
 727                 rp->maxactive = max(10, 2 * NR_CPUS);
 728 #else
 729                 rp->maxactive = NR_CPUS;
 730 #endif
 731         }
 732
 733         INIT_HLIST_HEAD(&rp->used_instances);
 734         INIT_HLIST_HEAD(&rp->free_instances);
 735
 736         for (i = 0; i < rp->maxactive; i++) {
 737                 inst = kmalloc(sizeof(*inst), GFP_ATOMIC);
 738                 if (inst == NULL) {
 739                         free_urp_inst(rp);
 740                         return -ENOMEM;
 741                 }
 742
 743                 INIT_HLIST_NODE(&inst->uflist);
 744                 hlist_add_head(&inst->uflist, &rp->free_instances);
 745         }
 746
 747         rp->nmissed = 0;
 748
 749         /* Establish function entry probe point */
 750         ret = dbi_register_uprobe(&rp->up);
 751         if (ret)
 752                 return ret;
 753
 754         arch_opcode_analysis_uretprobe(rp);
 755
 756         return 0;
 757 }
 758
 759 /* Called with uretprobe_lock held */
 760 int dbi_disarm_urp_inst_for_task(struct task_struct *parent, struct task_struct *task)
 761 {
 762         struct uretprobe_instance *ri;
 763         struct hlist_head *head = uretprobe_inst_table_head(parent->mm);
 764         struct hlist_node *tmp;
 765         DECLARE_NODE_PTR_FOR_HLIST(node);
 766
 767         swap_hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 768                 if (parent == ri->task) {
 769                         arch_disarm_urp_inst(ri, task);
 770                 }
 771         }
 772
 773         return 0;
 774 }
 775 EXPORT_SYMBOL_GPL(dbi_disarm_urp_inst_for_task);
 776
 777 void __dbi_unregister_uretprobe(struct uretprobe *rp, int disarm)
 778 {
 779         unsigned long flags;
 780         struct uretprobe_instance *ri;
 781
 782         __dbi_unregister_uprobe(&rp->up, disarm);
 783         spin_lock_irqsave (&uretprobe_lock, flags);
 784
 785         while ((ri = get_used_urp_inst(rp)) != NULL) {
 786                 if (arch_disarm_urp_inst(ri, ri->task) != 0)
 787                         printk("%s (%d/%d): cannot disarm urp instance (%08lx)\n",
 788                                         ri->task->comm, ri->task->tgid, ri->task->pid,
 789                                         (unsigned long)rp->up.kp.addr);
 790                 recycle_urp_inst(ri);
 791         }
 792
 793         if (hlist_empty(&rp->used_instances)) {
 794                 struct kprobe *p = &rp->up.kp;
 795
 796                 if (!(hlist_unhashed(&p->is_hlist))) {
 797                         hlist_del_rcu(&p->is_hlist);
 798                 }
 799         }
 800
 801         while ((ri = get_used_urp_inst(rp)) != NULL) {
 802                 ri->rp = NULL;
 803                 hlist_del(&ri->uflist);
 804         }
 805
 806         spin_unlock_irqrestore(&uretprobe_lock, flags);
 807         free_urp_inst(rp);
 808 }
 809 EXPORT_SYMBOL_GPL(__dbi_unregister_uretprobe);
 810
 811 void dbi_unregister_uretprobe(struct uretprobe *rp)
 812 {
 813         __dbi_unregister_uretprobe(rp, 1);
 814 }
 815
 816 void dbi_unregister_all_uprobes(struct task_struct *task)
 817 {
 818         struct hlist_head *head;
 819         struct kprobe *p;
 820         int i;
 821         struct hlist_node *tnode;
 822         DECLARE_NODE_PTR_FOR_HLIST(node);
 823
 824         for (i = 0; i < UPROBE_TABLE_SIZE; ++i) {
 825                 head = &uprobe_table[i];
 826                 swap_hlist_for_each_entry_safe(p, node, tnode, head, hlist) {
 827                         if (kp2up(p)->task->tgid == task->tgid) {
 828                                 struct uprobe *up = container_of(p, struct uprobe, kp);
 829                                 printk("dbi_unregister_all_uprobes: delete uprobe at %p[%lx] for %s/%d\n",
 830                                                 p->addr, (unsigned long)p->opcode, task->comm, task->pid);
 831                                 dbi_unregister_uprobe(up);
 832                         }
 833                 }
 834         }
 835 }
 836
 837 void swap_ujprobe_return(void)
 838 {
 839         arch_ujprobe_return();
 840 }
 841 EXPORT_SYMBOL_GPL(swap_ujprobe_return);
 842
 843 static int __init init_uprobes(void)
 844 {
 845         init_uprobe_table();
 846         init_uprobes_insn_slots();
 847         init_uretprobe_inst_table();
 848
 849         return swap_arch_init_uprobes();
 850 }
 851
 852 static void __exit exit_uprobes(void)
 853 {
 854         swap_arch_exit_uprobes();
 855 }
 856
 857 EXPORT_SYMBOL_GPL(dbi_register_ujprobe);
 858 EXPORT_SYMBOL_GPL(dbi_unregister_ujprobe);
 859 EXPORT_SYMBOL_GPL(dbi_register_uretprobe);
 860 EXPORT_SYMBOL_GPL(dbi_unregister_uretprobe);
 861 EXPORT_SYMBOL_GPL(dbi_unregister_all_uprobes);
 862
 863 module_init(init_uprobes);
 864 module_exit(exit_uprobes);
 865
 866 MODULE_LICENSE ("GPL");