kprobe/arch/asm-arm/dbi_kprobes.c

   1 /*
   2  *  Dynamic Binary Instrumentation Module based on KProbes
   3  *  modules/kprobe/arch/asm-arm/dbi_kprobes.c
   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  * 2006-2007    Ekaterina Gorelkina <e.gorelkina@samsung.com>: initial implementation for ARM/MIPS
  22  * 2008-2009    Alexey Gerenkov <a.gerenkov@samsung.com> User-Space
  23  *              Probes initial implementation; Support x86.
  24  * 2010         Ekaterina Gorelkina <e.gorelkina@samsung.com>: redesign module for separating core and arch parts
  25  * 2010-2011    Alexander Shirshikov <a.shirshikov@samsung.com>: initial implementation for Thumb
  26  * 2012         Stanislav Andreev <s.andreev@samsung.com>: added time debug profiling support; BUG() message fix
  27  * 2012         Stanislav Andreev <s.andreev@samsung.com>: redesign of kprobe functionality -
  28  *              kprobe_handler() now called via undefined instruction hooks
  29  * 2012         Stanislav Andreev <s.andreev@samsung.com>: hash tables search implemented for uprobes
  30  */
  31
  32 #include <linux/module.h>
  33 #include <linux/mm.h>
  34
  35 #include "dbi_kprobes.h"
  36 #include "trampoline_arm.h"
  37 #include "../dbi_kprobes.h"
  38 #include "../../dbi_kprobes.h"
  39
  40 #include "../../dbi_kdebug.h"
  41 #include "../../dbi_insn_slots.h"
  42 #include "../../dbi_kprobes_deps.h"
  43 #include <ksyms.h>
  44
  45 #include <asm/cacheflush.h>
  46 #include <asm/traps.h>
  47 #include <asm/ptrace.h>
  48 #include <linux/list.h>
  49 #include <linux/hash.h>
  50
  51 #define SUPRESS_BUG_MESSAGES
  52
  53 extern struct kprobe * per_cpu__current_kprobe;
  54 extern struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  55
  56 static void (*__swap_register_undef_hook)(struct undef_hook *hook);
  57 static void (*__swap_unregister_undef_hook)(struct undef_hook *hook);
  58
  59 static struct kprobe trampoline_p =
  60 {
  61         .addr = (kprobe_opcode_t *)&kretprobe_trampoline,
  62         .pre_handler = trampoline_probe_handler
  63 };
  64
  65 int prep_pc_dep_insn_execbuf(kprobe_opcode_t *insns, kprobe_opcode_t insn, int uregs)
  66 {
  67         int i;
  68
  69         if (uregs & 0x10) {
  70                 int reg_mask = 0x1;
  71                 //search in reg list
  72                 for (i = 0; i < 13; i++, reg_mask <<= 1) {
  73                         if (!(insn & reg_mask))
  74                                 break;
  75                 }
  76         } else {
  77                 for (i = 0; i < 13; i++) {
  78                         if ((uregs & 0x1) && (ARM_INSN_REG_RN(insn) == i))
  79                                 continue;
  80                         if ((uregs & 0x2) && (ARM_INSN_REG_RD(insn) == i))
  81                                 continue;
  82                         if ((uregs & 0x4) && (ARM_INSN_REG_RS(insn) == i))
  83                                 continue;
  84                         if ((uregs & 0x8) && (ARM_INSN_REG_RM(insn) == i))
  85                                 continue;
  86                         break;
  87                 }
  88         }
  89
  90         if (i == 13) {
  91                 DBPRINTF ("there are no free register %x in insn %lx!", uregs, insn);
  92                 return -EINVAL;
  93         }
  94         DBPRINTF ("prep_pc_dep_insn_execbuf: using R%d, changing regs %x", i, uregs);
  95
  96         // set register to save
  97         ARM_INSN_REG_SET_RD(insns[0], i);
  98         // set register to load address to
  99         ARM_INSN_REG_SET_RD(insns[1], i);
 100         // set instruction to execute and patch it
 101         if (uregs & 0x10) {
 102                 ARM_INSN_REG_CLEAR_MR(insn, 15);
 103                 ARM_INSN_REG_SET_MR(insn, i);
 104         } else {
 105                 if ((uregs & 0x1) && (ARM_INSN_REG_RN(insn) == 15))
 106                         ARM_INSN_REG_SET_RN(insn, i);
 107                 if ((uregs & 0x2) && (ARM_INSN_REG_RD(insn) == 15))
 108                         ARM_INSN_REG_SET_RD(insn, i);
 109                 if ((uregs & 0x4) && (ARM_INSN_REG_RS(insn) == 15))
 110                         ARM_INSN_REG_SET_RS(insn, i);
 111                 if ((uregs & 0x8) && (ARM_INSN_REG_RM(insn) == 15))
 112                         ARM_INSN_REG_SET_RM(insn, i);
 113         }
 114
 115         insns[UPROBES_TRAMP_INSN_IDX] = insn;
 116         // set register to restore
 117         ARM_INSN_REG_SET_RD(insns[3], i);
 118
 119         return 0;
 120 }
 121 EXPORT_SYMBOL_GPL(prep_pc_dep_insn_execbuf);
 122
 123 int arch_check_insn_arm(struct arch_specific_insn *ainsn)
 124 {
 125         int ret = 0;
 126
 127         // check instructions that can change PC by nature
 128         if (
 129 //          ARM_INSN_MATCH(UNDEF, ainsn->insn_arm[0]) ||
 130             ARM_INSN_MATCH(AUNDEF, ainsn->insn_arm[0]) ||
 131             ARM_INSN_MATCH(SWI, ainsn->insn_arm[0]) ||
 132             ARM_INSN_MATCH(BREAK, ainsn->insn_arm[0]) ||
 133             ARM_INSN_MATCH(BL, ainsn->insn_arm[0]) ||
 134             ARM_INSN_MATCH(BLX1, ainsn->insn_arm[0]) ||
 135             ARM_INSN_MATCH(BLX2, ainsn->insn_arm[0]) ||
 136             ARM_INSN_MATCH(BX, ainsn->insn_arm[0]) ||
 137             ARM_INSN_MATCH(BXJ, ainsn->insn_arm[0]))    {
 138                 DBPRINTF ("Bad insn arch_check_insn_arm: %lx\n", ainsn->insn_arm[0]);
 139                 ret = -EFAULT;
 140 #ifndef CONFIG_CPU_V7
 141         // check instructions that can write result to PC
 142         } else if ((ARM_INSN_MATCH(DPIS, ainsn->insn_arm[0]) ||
 143                    ARM_INSN_MATCH(DPRS, ainsn->insn_arm[0]) ||
 144                    ARM_INSN_MATCH(DPI, ainsn->insn_arm[0]) ||
 145                    ARM_INSN_MATCH(LIO, ainsn->insn_arm[0]) ||
 146                    ARM_INSN_MATCH(LRO, ainsn->insn_arm[0])) &&
 147                    (ARM_INSN_REG_RD(ainsn->insn_arm[0]) == 15)) {
 148                 DBPRINTF ("Bad arch_check_insn_arm: %lx\n", ainsn->insn_arm[0]);
 149                 ret = -EFAULT;
 150 #endif // CONFIG_CPU_V7
 151         // check special instruction loads store multiple registers
 152         } else if ((ARM_INSN_MATCH(LM, ainsn->insn_arm[0]) || ARM_INSN_MATCH(SM, ainsn->insn_arm[0])) &&
 153                         // store pc or load to pc
 154                    (ARM_INSN_REG_MR(ainsn->insn_arm[0], 15) ||
 155                          // store/load with pc update
 156                     ((ARM_INSN_REG_RN(ainsn->insn_arm[0]) == 15) && (ainsn->insn_arm[0] & 0x200000)))) {
 157                 DBPRINTF ("Bad insn arch_check_insn_arm: %lx\n", ainsn->insn_arm[0]);
 158                 ret = -EFAULT;
 159         }
 160
 161         return ret;
 162 }
 163 EXPORT_SYMBOL_GPL(arch_check_insn_arm);
 164
 165 int arch_prepare_kprobe(struct kprobe *p, struct slot_manager *sm)
 166 {
 167         kprobe_opcode_t insns[KPROBES_TRAMP_LEN];
 168         int uregs, pc_dep, ret = 0;
 169         kprobe_opcode_t insn[MAX_INSN_SIZE];
 170         struct arch_specific_insn ainsn;
 171
 172         /* insn: must be on special executable page on i386. */
 173         p->ainsn.insn = alloc_insn_slot(sm);
 174         if (!p->ainsn.insn)
 175                 return -ENOMEM;
 176
 177         memcpy(insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
 178         ainsn.insn_arm = ainsn.insn = insn;
 179         ret = arch_check_insn_arm(&ainsn);
 180         if (!ret) {
 181                 p->opcode = *p->addr;
 182                 uregs = pc_dep = 0;
 183
 184                 // Rn, Rm ,Rd
 185                 if (ARM_INSN_MATCH(DPIS, insn[0]) || ARM_INSN_MATCH(LRO, insn[0]) ||
 186                     ARM_INSN_MATCH(SRO, insn[0])) {
 187                         uregs = 0xb;
 188                         if ((ARM_INSN_REG_RN(insn[0]) == 15) || (ARM_INSN_REG_RM(insn[0]) == 15) ||
 189                             (ARM_INSN_MATCH(SRO, insn[0]) && (ARM_INSN_REG_RD(insn[0]) == 15))) {
 190                                 DBPRINTF ("Unboostable insn %lx, DPIS/LRO/SRO\n", insn[0]);
 191                                 pc_dep = 1;
 192                         }
 193
 194                 // Rn ,Rd
 195                 } else if( ARM_INSN_MATCH(DPI, insn[0]) || ARM_INSN_MATCH(LIO, insn[0]) ||
 196                            ARM_INSN_MATCH(SIO, insn[0])) {
 197                         uregs = 0x3;
 198                         if ((ARM_INSN_REG_RN(insn[0]) == 15) || (ARM_INSN_MATCH(SIO, insn[0]) &&
 199                             (ARM_INSN_REG_RD (insn[0]) == 15))) {
 200                                 pc_dep = 1;
 201                                 DBPRINTF ("Unboostable insn %lx/%p, DPI/LIO/SIO\n", insn[0], p);
 202                         }
 203                 // Rn, Rm, Rs
 204                 } else if (ARM_INSN_MATCH(DPRS, insn[0])) {
 205                         uregs = 0xd;
 206                         if ((ARM_INSN_REG_RN(insn[0]) == 15) || (ARM_INSN_REG_RM(insn[0]) == 15) ||
 207                             (ARM_INSN_REG_RS (insn[0]) == 15)) {
 208                                 pc_dep = 1;
 209                                 DBPRINTF ("Unboostable insn %lx, DPRS\n", insn[0]);
 210                         }
 211                 // register list
 212                 } else if(ARM_INSN_MATCH(SM, insn[0])) {
 213                         uregs = 0x10;
 214                         if (ARM_INSN_REG_MR(insn[0], 15)) {
 215                                 DBPRINTF ("Unboostable insn %lx, SM\n", insn[0]);
 216                                 pc_dep = 1;
 217                         }
 218                 }
 219
 220                 // check instructions that can write result to SP andu uses PC
 221                 if (pc_dep  && (ARM_INSN_REG_RD(ainsn.insn[0]) == 13)) {
 222                         free_insn_slot(sm, p->ainsn.insn);
 223                         ret = -EFAULT;
 224                 } else {
 225                         if (uregs && pc_dep) {
 226                                 memcpy(insns, pc_dep_insn_execbuf, sizeof(insns));
 227                                 if (prep_pc_dep_insn_execbuf(insns, insn[0], uregs) != 0) {
 228                                         DBPRINTF ("failed to prepare exec buffer for insn %lx!", insn[0]);
 229                                         free_insn_slot(sm, p->ainsn.insn);
 230                                         return -EINVAL;
 231                                 }
 232                                 insns[6] = (kprobe_opcode_t)(p->addr + 2);
 233                         } else {
 234                                 memcpy(insns, gen_insn_execbuf, sizeof(insns));
 235                                 insns[KPROBES_TRAMP_INSN_IDX] = insn[0];
 236                         }
 237                         insns[7] = (kprobe_opcode_t)(p->addr + 1);
 238                         DBPRINTF ("arch_prepare_kprobe: insn %lx", insn[0]);
 239                         DBPRINTF ("arch_prepare_kprobe: to %p - %lx %lx %lx %lx %lx %lx %lx %lx %lx",
 240                                   p->ainsn.insn, insns[0], insns[1], insns[2], insns[3], insns[4],
 241                                   insns[5], insns[6], insns[7], insns[8]);
 242                         memcpy(p->ainsn.insn, insns, sizeof(insns));
 243                         flush_icache_range((long unsigned)p->ainsn.insn, (long unsigned)(p->ainsn.insn) + sizeof(insns));
 244 #ifdef BOARD_tegra
 245                         flush_cache_all();
 246 #endif
 247                 }
 248         } else {
 249                 free_insn_slot(sm, p->ainsn.insn);
 250                 printk("arch_prepare_kprobe: instruction 0x%lx not instrumentation, addr=0x%p\n", insn[0], p->addr);
 251         }
 252
 253         return ret;
 254 }
 255
 256 void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 257 {
 258         if (p->ss_addr) {
 259                 regs->ARM_pc = (unsigned long)p->ss_addr;
 260                 p->ss_addr = NULL;
 261         } else {
 262                 regs->ARM_pc = (unsigned long)p->ainsn.insn;
 263         }
 264 }
 265 EXPORT_SYMBOL_GPL(prepare_singlestep);
 266
 267 void save_previous_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p_run)
 268 {
 269         kcb->prev_kprobe.kp = kprobe_running();
 270         kcb->prev_kprobe.status = kcb->kprobe_status;
 271 }
 272
 273 void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 274 {
 275         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 276         kcb->kprobe_status = kcb->prev_kprobe.status;
 277 }
 278
 279 void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
 280 {
 281         __get_cpu_var(current_kprobe) = p;
 282         DBPRINTF ("set_current_kprobe: p=%p addr=%p\n", p, p->addr);
 283 }
 284
 285 static int kprobe_handler(struct pt_regs *regs)
 286 {
 287         struct kprobe *p, *cur;
 288         struct kprobe_ctlblk *kcb;
 289
 290         kcb = get_kprobe_ctlblk();
 291         cur = kprobe_running();
 292         p = get_kprobe((void *)regs->ARM_pc);
 293
 294         if (p) {
 295                 if (cur) {
 296                         /* Kprobe is pending, so we're recursing. */
 297                         switch (kcb->kprobe_status) {
 298                         case KPROBE_HIT_ACTIVE:
 299                         case KPROBE_HIT_SSDONE:
 300                                 /* A pre- or post-handler probe got us here. */
 301                                 kprobes_inc_nmissed_count(p);
 302                                 save_previous_kprobe(kcb, NULL);
 303                                 set_current_kprobe(p, 0, 0);
 304                                 kcb->kprobe_status = KPROBE_REENTER;
 305                                 prepare_singlestep(p, regs);
 306                                 restore_previous_kprobe(kcb);
 307                                 break;
 308                         default:
 309                                 /* impossible cases */
 310                                 BUG();
 311                         }
 312                 } else {
 313                         set_current_kprobe(p, 0, 0);
 314                         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 315
 316                         if (!p->pre_handler || !p->pre_handler(p, regs)) {
 317                                 kcb->kprobe_status = KPROBE_HIT_SS;
 318                                 prepare_singlestep(p, regs);
 319                                 reset_current_kprobe();
 320                         }
 321                 }
 322         } else {
 323                 goto no_kprobe;
 324         }
 325
 326         return 0;
 327
 328 no_kprobe:
 329         printk("no_kprobe\n");
 330         return 1;
 331 }
 332
 333 int kprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
 334 {
 335         int ret;
 336         unsigned long flags;
 337
 338 #ifdef SUPRESS_BUG_MESSAGES
 339         int swap_oops_in_progress;
 340         /* oops_in_progress used to avoid BUG() messages
 341          * that slow down kprobe_handler() execution */
 342         swap_oops_in_progress = oops_in_progress;
 343         oops_in_progress = 1;
 344 #endif
 345
 346         local_irq_save(flags);
 347         preempt_disable();
 348         ret = kprobe_handler(regs);
 349         preempt_enable_no_resched();
 350         local_irq_restore(flags);
 351
 352 #ifdef SUPRESS_BUG_MESSAGES
 353         oops_in_progress = swap_oops_in_progress;
 354 #endif
 355
 356         return ret;
 357 }
 358
 359 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 360 {
 361         struct jprobe *jp = container_of(p, struct jprobe, kp);
 362         kprobe_pre_entry_handler_t pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
 363         entry_point_t entry = (entry_point_t)jp->entry;
 364         pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
 365
 366         if (((unsigned long)p->addr == sched_addr) && sched_rp) {
 367                 struct thread_info *tinfo = (struct thread_info *)regs->ARM_r2;
 368                 patch_suspended_task(sched_rp, tinfo->task);
 369         }
 370
 371         if (pre_entry) {
 372                 p->ss_addr = (void *)pre_entry (jp->priv_arg, regs);
 373         }
 374
 375         if (entry) {
 376                 entry(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2,
 377                       regs->ARM_r3, regs->ARM_r4, regs->ARM_r5);
 378         } else {
 379                 dbi_jprobe_return();
 380         }
 381
 382         return 0;
 383 }
 384
 385 void dbi_jprobe_return (void)
 386 {
 387 }
 388
 389 int longjmp_break_handler (struct kprobe *p, struct pt_regs *regs)
 390 {
 391         return 0;
 392 }
 393 EXPORT_SYMBOL_GPL(longjmp_break_handler);
 394
 395 void arch_arm_kprobe(struct kprobe *p)
 396 {
 397         *p->addr = BREAKPOINT_INSTRUCTION;
 398         flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t));
 399 }
 400
 401 void arch_disarm_kprobe(struct kprobe *p)
 402 {
 403         *p->addr = p->opcode;
 404         flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t));
 405 }
 406
 407 int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 408 {
 409         struct kretprobe_instance *ri = NULL;
 410         struct hlist_head *head;
 411         struct hlist_node *node, *tmp;
 412         unsigned long flags, orig_ret_address = 0;
 413         unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
 414
 415         struct kretprobe *crp = NULL;
 416         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 417
 418         spin_lock_irqsave(&kretprobe_lock, flags);
 419
 420         /*
 421          * We are using different hash keys (current and mm) for finding kernel
 422          * space and user space probes.  Kernel space probes can change mm field in
 423          * task_struct.  User space probes can be shared between threads of one
 424          * process so they have different current but same mm.
 425          */
 426         head = kretprobe_inst_table_head(current);
 427
 428         /*
 429          * It is possible to have multiple instances associated with a given
 430          * task either because an multiple functions in the call path
 431          * have a return probe installed on them, and/or more then one
 432          * return probe was registered for a target function.
 433          *
 434          * We can handle this because:
 435          *     - instances are always inserted at the head of the list
 436          *     - when multiple return probes are registered for the same
 437          *       function, the first instance's ret_addr will point to the
 438          *       real return address, and all the rest will point to
 439          *       kretprobe_trampoline
 440          */
 441         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 442                 if (ri->task != current)
 443                         /* another task is sharing our hash bucket */
 444                         continue;
 445                 if (ri->rp && ri->rp->handler) {
 446                         ri->rp->handler(ri, regs, ri->rp->priv_arg);
 447                 }
 448
 449                 orig_ret_address = (unsigned long)ri->ret_addr;
 450                 recycle_rp_inst(ri);
 451                 if (orig_ret_address != trampoline_address)
 452                         /*
 453                          * This is the real return address. Any other
 454                          * instances associated with this task are for
 455                          * other calls deeper on the call stack
 456                          */
 457                         break;
 458         }
 459         kretprobe_assert(ri, orig_ret_address, trampoline_address);
 460
 461         regs->ARM_lr = orig_ret_address;
 462         regs->ARM_pc = orig_ret_address;
 463
 464         if (kcb->kprobe_status == KPROBE_REENTER) {
 465                 restore_previous_kprobe(kcb);
 466         } else {
 467                 reset_current_kprobe();
 468         }
 469
 470         spin_unlock_irqrestore(&kretprobe_lock, flags);
 471
 472         /*
 473          * By returning a non-zero value, we are telling
 474          * kprobe_handler() that we don't want the post_handler
 475          * to run (and have re-enabled preemption)
 476          */
 477
 478         return 1;
 479 }
 480 EXPORT_SYMBOL_GPL(trampoline_probe_handler);
 481
 482 void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs)
 483 {
 484         struct kretprobe_instance *ri;
 485
 486         DBPRINTF ("start\n");
 487         //TODO: test - remove retprobe after func entry but before its exit
 488         if ((ri = get_free_rp_inst(rp)) != NULL) {
 489                 ri->rp = rp;
 490                 ri->task = current;
 491                 ri->ret_addr = (kprobe_opcode_t *)regs->uregs[14];
 492                 ri->sp = (kprobe_opcode_t *)regs->ARM_sp; //uregs[13];
 493
 494                 /* Set flag of current mode */
 495                 ri->sp = (kprobe_opcode_t *)((long)ri->sp | !!thumb_mode(regs));
 496
 497                 /* Replace the return addr with trampoline addr */
 498                 regs->uregs[14] = (unsigned long)&kretprobe_trampoline;
 499
 500 //              DBPRINTF ("ret addr set to %p->%lx\n", ri->ret_addr, regs->uregs[14]);
 501                 add_rp_inst(ri);
 502         } else {
 503                 DBPRINTF ("WARNING: missed retprobe %p\n", rp->kp.addr);
 504                 rp->nmissed++;
 505         }
 506 }
 507
 508 void swap_register_undef_hook(struct undef_hook *hook)
 509 {
 510         __swap_register_undef_hook(hook);
 511 }
 512 EXPORT_SYMBOL_GPL(swap_register_undef_hook);
 513
 514 void swap_unregister_undef_hook(struct undef_hook *hook)
 515 {
 516         __swap_unregister_undef_hook(hook);
 517 }
 518 EXPORT_SYMBOL_GPL(swap_unregister_undef_hook);
 519
 520 // kernel probes hook
 521 static struct undef_hook undef_ho_k = {
 522         .instr_mask     = 0xffffffff,
 523         .instr_val      = BREAKPOINT_INSTRUCTION,
 524         .cpsr_mask      = MODE_MASK,
 525         .cpsr_val       = SVC_MODE,
 526         .fn             = kprobe_trap_handler
 527 };
 528
 529 int arch_init_kprobes(void)
 530 {
 531         int ret = 0;
 532
 533         // Register hooks (kprobe_handler)
 534         __swap_register_undef_hook = swap_ksyms("register_undef_hook");
 535         if (__swap_register_undef_hook == NULL) {
 536                 printk("no register_undef_hook symbol found!\n");
 537                 return -1;
 538         }
 539
 540         // Unregister hooks (kprobe_handler)
 541         __swap_unregister_undef_hook = swap_ksyms("unregister_undef_hook");
 542         if (__swap_unregister_undef_hook == NULL) {
 543                 printk("no unregister_undef_hook symbol found!\n");
 544                 return -1;
 545         }
 546
 547         swap_register_undef_hook(&undef_ho_k);
 548         if ((ret = dbi_register_kprobe (&trampoline_p)) != 0) {
 549                 //dbi_unregister_jprobe(&do_exit_p, 0);
 550                 return ret;
 551         }
 552
 553         return ret;
 554 }
 555
 556 void arch_exit_kprobes(void)
 557 {
 558         dbi_unregister_kprobe(&trampoline_p, NULL);
 559         swap_unregister_undef_hook(&undef_ho_k);
 560 }
 561
 562 /* export symbol for trampoline_arm.h */
 563 EXPORT_SYMBOL_GPL(gen_insn_execbuf);
 564 EXPORT_SYMBOL_GPL(pc_dep_insn_execbuf);