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 "dbi_kprobes_arm.h"
  37 #include "dbi_kprobes_thumb.h"
  38 #include "../dbi_kprobes.h"
  39 #include "../../dbi_kprobes.h"
  40
  41 #include "../../dbi_kdebug.h"
  42 #include "../../dbi_insn_slots.h"
  43 #include "../../dbi_kprobes_deps.h"
  44 #include <ksyms.h>
  45
  46 #include <asm/cacheflush.h>
  47
  48 #ifdef TRAP_OVERHEAD_DEBUG
  49 #include <linux/pid.h>
  50 #include <linux/signal.h>
  51 #endif
  52
  53 #ifdef OVERHEAD_DEBUG
  54 #include <linux/time.h>
  55 #endif
  56
  57 #include <asm/traps.h>
  58 #include <asm/ptrace.h>
  59 #include <linux/list.h>
  60 #include <linux/hash.h>
  61
  62 #define SUPRESS_BUG_MESSAGES
  63
  64 extern struct kprobe * per_cpu__current_kprobe;
  65 extern struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  66
  67 static void (*__swap_register_undef_hook)(struct undef_hook *hook);
  68 static void (*__swap_unregister_undef_hook)(struct undef_hook *hook);
  69
  70 #ifdef OVERHEAD_DEBUG
  71 unsigned long swap_sum_time = 0;
  72 unsigned long swap_sum_hit = 0;
  73 EXPORT_SYMBOL_GPL (swap_sum_time);
  74 EXPORT_SYMBOL_GPL (swap_sum_hit);
  75 #endif
  76
  77 static unsigned int arr_traps_template[] = {
  78                 0xe1a0c00d,    // mov          ip, sp
  79                 0xe92dd800,    // stmdb        sp!, {fp, ip, lr, pc}
  80                 0xe24cb004,    // sub          fp, ip, #4      ; 0x4
  81                 0x00000000,    // b
  82                 0xe3500000,    // cmp          r0, #0  ; 0x0
  83                 0xe89da800,    // ldmia        sp, {fp, sp, pc}
  84                 0x00000000,    // nop
  85                 0xffffffff     // end
  86 };
  87
  88
  89 static struct kprobe trampoline_p =
  90 {
  91         .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
  92         .pre_handler = trampoline_probe_handler
  93 };
  94
  95 int prep_pc_dep_insn_execbuf(kprobe_opcode_t *insns, kprobe_opcode_t insn, int uregs)
  96 {
  97         int i;
  98
  99         if (uregs & 0x10)
 100         {
 101                 int reg_mask = 0x1;
 102                 //search in reg list
 103                 for (i = 0; i < 13; i++, reg_mask <<= 1)
 104                 {
 105                         if (!(insn & reg_mask))
 106                                 break;
 107                 }
 108         }
 109         else
 110         {
 111                 for (i = 0; i < 13; i++)
 112                 {
 113                         if ((uregs & 0x1) && (ARM_INSN_REG_RN (insn) == i))
 114                                 continue;
 115                         if ((uregs & 0x2) && (ARM_INSN_REG_RD (insn) == i))
 116                                 continue;
 117                         if ((uregs & 0x4) && (ARM_INSN_REG_RS (insn) == i))
 118                                 continue;
 119                         if ((uregs & 0x8) && (ARM_INSN_REG_RM (insn) == i))
 120                                 continue;
 121                         break;
 122                 }
 123         }
 124         if (i == 13)
 125         {
 126                 DBPRINTF ("there are no free register %x in insn %lx!", uregs, insn);
 127                 return -EINVAL;
 128         }
 129         DBPRINTF ("prep_pc_dep_insn_execbuf: using R%d, changing regs %x", i, uregs);
 130
 131         // set register to save
 132         ARM_INSN_REG_SET_RD (insns[0], i);
 133         // set register to load address to
 134         ARM_INSN_REG_SET_RD (insns[1], i);
 135         // set instruction to execute and patch it
 136         if (uregs & 0x10)
 137         {
 138                 ARM_INSN_REG_CLEAR_MR (insn, 15);
 139                 ARM_INSN_REG_SET_MR (insn, i);
 140         }
 141         else
 142         {
 143                 if ((uregs & 0x1) && (ARM_INSN_REG_RN (insn) == 15))
 144                         ARM_INSN_REG_SET_RN (insn, i);
 145                 if ((uregs & 0x2) && (ARM_INSN_REG_RD (insn) == 15))
 146                         ARM_INSN_REG_SET_RD (insn, i);
 147                 if ((uregs & 0x4) && (ARM_INSN_REG_RS (insn) == 15))
 148                         ARM_INSN_REG_SET_RS (insn, i);
 149                 if ((uregs & 0x8) && (ARM_INSN_REG_RM (insn) == 15))
 150                         ARM_INSN_REG_SET_RM (insn, i);
 151         }
 152         insns[UPROBES_TRAMP_INSN_IDX] = insn;
 153         // set register to restore
 154         ARM_INSN_REG_SET_RD (insns[3], i);
 155         return 0;
 156 }
 157 EXPORT_SYMBOL_GPL(prep_pc_dep_insn_execbuf);
 158
 159 int arch_check_insn_arm(struct arch_specific_insn *ainsn)
 160 {
 161         int ret = 0;
 162
 163         // check instructions that can change PC by nature
 164         if (
 165 //              ARM_INSN_MATCH (UNDEF, ainsn->insn_arm[0]) ||
 166                 ARM_INSN_MATCH (AUNDEF, ainsn->insn_arm[0]) ||
 167                 ARM_INSN_MATCH (SWI, ainsn->insn_arm[0]) ||
 168                 ARM_INSN_MATCH (BREAK, ainsn->insn_arm[0]) ||
 169                 ARM_INSN_MATCH (BL, ainsn->insn_arm[0]) ||
 170                 ARM_INSN_MATCH (BLX1, ainsn->insn_arm[0]) ||
 171                 ARM_INSN_MATCH (BLX2, ainsn->insn_arm[0]) ||
 172                 ARM_INSN_MATCH (BX, ainsn->insn_arm[0]) ||
 173                 ARM_INSN_MATCH (BXJ, ainsn->insn_arm[0]))
 174         {
 175                 DBPRINTF ("Bad insn arch_check_insn_arm: %lx\n", ainsn->insn_arm[0]);
 176                 ret = -EFAULT;
 177         }
 178 #ifndef CONFIG_CPU_V7
 179         // check instructions that can write result to PC
 180         else if ((ARM_INSN_MATCH (DPIS, ainsn->insn_arm[0]) ||
 181                                 ARM_INSN_MATCH (DPRS, ainsn->insn_arm[0]) ||
 182                                 ARM_INSN_MATCH (DPI, ainsn->insn_arm[0]) ||
 183                                 ARM_INSN_MATCH (LIO, ainsn->insn_arm[0]) ||
 184                                 ARM_INSN_MATCH (LRO, ainsn->insn_arm[0])) &&
 185                         (ARM_INSN_REG_RD (ainsn->insn_arm[0]) == 15))
 186         {
 187                 DBPRINTF ("Bad arch_check_insn_arm: %lx\n", ainsn->insn_arm[0]);
 188                 ret = -EFAULT;
 189         }
 190 #endif // CONFIG_CPU_V7
 191         // check special instruction loads store multiple registers
 192         else if ((ARM_INSN_MATCH (LM, ainsn->insn_arm[0]) || ARM_INSN_MATCH (SM, ainsn->insn_arm[0])) &&
 193                         // store pc or load to pc
 194                         (ARM_INSN_REG_MR (ainsn->insn_arm[0], 15) ||
 195                          // store/load with pc update
 196                          ((ARM_INSN_REG_RN (ainsn->insn_arm[0]) == 15) && (ainsn->insn_arm[0] & 0x200000))))
 197         {
 198                 DBPRINTF ("Bad insn arch_check_insn_arm: %lx\n", ainsn->insn_arm[0]);
 199                 ret = -EFAULT;
 200         }
 201         return ret;
 202 }
 203 EXPORT_SYMBOL_GPL(arch_check_insn_arm);
 204
 205 int arch_prepare_kretprobe (struct kretprobe *p)
 206 {
 207         DBPRINTF("Warrning: arch_prepare_kretprobe is not implemented\n");
 208         return 0;
 209 }
 210
 211 int arch_prepare_kprobe (struct kprobe *p)
 212 {
 213         kprobe_opcode_t insns[KPROBES_TRAMP_LEN];
 214         int uregs, pc_dep, ret = 0;
 215     kprobe_opcode_t insn[MAX_INSN_SIZE];
 216     struct arch_specific_insn ainsn;
 217
 218     /* insn: must be on special executable page on i386. */
 219     p->ainsn.insn = get_insn_slot(NULL, &kprobe_insn_pages, 0);
 220     if (!p->ainsn.insn)
 221         return -ENOMEM;
 222
 223     memcpy (insn, p->addr, MAX_INSN_SIZE * sizeof (kprobe_opcode_t));
 224     ainsn.insn_arm = ainsn.insn = insn;
 225     ret = arch_check_insn_arm (&ainsn);
 226     if (!ret)
 227     {
 228         p->opcode = *p->addr;
 229         uregs = pc_dep = 0;
 230
 231         // Rn, Rm ,Rd
 232         if(ARM_INSN_MATCH (DPIS, insn[0]) || ARM_INSN_MATCH (LRO, insn[0]) ||
 233            ARM_INSN_MATCH (SRO, insn[0]))
 234         {
 235             uregs = 0xb;
 236             if( (ARM_INSN_REG_RN (insn[0]) == 15) || (ARM_INSN_REG_RM (insn[0]) == 15) ||
 237                 (ARM_INSN_MATCH (SRO, insn[0]) && (ARM_INSN_REG_RD (insn[0]) == 15)) )
 238             {
 239                 DBPRINTF ("Unboostable insn %lx, DPIS/LRO/SRO\n", insn[0]);
 240                 pc_dep = 1;
 241             }
 242         }
 243         // Rn ,Rd
 244         else if(ARM_INSN_MATCH (DPI, insn[0]) || ARM_INSN_MATCH (LIO, insn[0]) ||
 245                 ARM_INSN_MATCH (SIO, insn[0]))
 246         {
 247             uregs = 0x3;
 248             if ((ARM_INSN_REG_RN (insn[0]) == 15) || (ARM_INSN_MATCH (SIO, insn[0]) &&
 249                         (ARM_INSN_REG_RD (insn[0]) == 15)))
 250             {
 251                 pc_dep = 1;
 252                 DBPRINTF ("Unboostable insn %lx/%p, DPI/LIO/SIO\n", insn[0], p);
 253             }
 254         }
 255         // Rn, Rm, Rs
 256         else if(ARM_INSN_MATCH (DPRS, insn[0]))
 257         {
 258             uregs = 0xd;
 259             if ((ARM_INSN_REG_RN (insn[0]) == 15) || (ARM_INSN_REG_RM (insn[0]) == 15) ||
 260                 (ARM_INSN_REG_RS (insn[0]) == 15))
 261             {
 262                 pc_dep = 1;
 263                 DBPRINTF ("Unboostable insn %lx, DPRS\n", insn[0]);
 264             }
 265         }
 266         // register list
 267         else if(ARM_INSN_MATCH (SM, insn[0]))
 268         {
 269             uregs = 0x10;
 270             if (ARM_INSN_REG_MR (insn[0], 15))
 271             {
 272                 DBPRINTF ("Unboostable insn %lx, SM\n", insn[0]);
 273                 pc_dep = 1;
 274             }
 275         }
 276         // check instructions that can write result to SP andu uses PC
 277         if (pc_dep  && (ARM_INSN_REG_RD (ainsn.insn[0]) == 13))
 278         {
 279             free_insn_slot(&kprobe_insn_pages, NULL, p->ainsn.insn);
 280             ret = -EFAULT;
 281         }
 282         else
 283         {
 284             if (uregs && pc_dep)
 285             {
 286                 memcpy (insns, pc_dep_insn_execbuf, sizeof (insns));
 287                 if (prep_pc_dep_insn_execbuf (insns, insn[0], uregs) != 0)
 288                 {
 289                     DBPRINTF ("failed to prepare exec buffer for insn %lx!", insn[0]);
 290                     free_insn_slot(&kprobe_insn_pages, NULL, p->ainsn.insn);
 291                     return -EINVAL;
 292                 }
 293                 insns[6] = (kprobe_opcode_t) (p->addr + 2);
 294             }
 295             else
 296             {
 297                 memcpy (insns, gen_insn_execbuf, sizeof (insns));
 298                 insns[KPROBES_TRAMP_INSN_IDX] = insn[0];
 299             }
 300             insns[7] = (kprobe_opcode_t) (p->addr + 1);
 301             DBPRINTF ("arch_prepare_kprobe: insn %lx", insn[0]);
 302             DBPRINTF ("arch_prepare_kprobe: to %p - %lx %lx %lx %lx %lx %lx %lx %lx %lx",
 303                     p->ainsn.insn, insns[0], insns[1], insns[2], insns[3], insns[4],
 304                     insns[5], insns[6], insns[7], insns[8]);
 305             memcpy (p->ainsn.insn, insns, sizeof(insns));
 306             flush_icache_range((long unsigned)p->ainsn.insn, (long unsigned)(p->ainsn.insn) + sizeof(insns));
 307 #ifdef BOARD_tegra
 308             flush_cache_all();
 309 #endif
 310         }
 311     }
 312     else
 313     {
 314         free_insn_slot(&kprobe_insn_pages, NULL, p->ainsn.insn);
 315         printk("arch_prepare_kprobe: instruction 0x%lx not instrumentation, addr=0x%p\n", insn[0], p->addr);
 316     }
 317
 318     return ret;
 319 }
 320
 321 static unsigned int arch_construct_brunch (unsigned int base, unsigned int addr, int link)
 322 {
 323         kprobe_opcode_t insn;
 324         unsigned int bpi = (unsigned int) base - (unsigned int) addr - 8;
 325
 326         insn = bpi >> 2;
 327         DBPRINTF ("base=%x addr=%x base-addr-8=%x\n", base, addr, bpi);
 328         if (abs (insn & 0xffffff) > 0xffffff)
 329         {
 330                 DBPRINTF ("ERROR: kprobe address out of range\n");
 331                 BUG ();
 332         }
 333         insn = insn & 0xffffff;
 334         insn = insn | ((link != 0) ? 0xeb000000 : 0xea000000);
 335         DBPRINTF ("insn=%lX\n", insn);
 336         return (unsigned int) insn;
 337 }
 338
 339 int arch_prepare_uretprobe (struct kretprobe *p, struct task_struct *task)
 340 {
 341         DBPRINTF("Warrning: arch_prepare_uretprobe is not implemented\n");
 342         return 0;
 343 }
 344 EXPORT_SYMBOL_GPL(arch_prepare_uretprobe);
 345
 346 void prepare_singlestep (struct kprobe *p, struct pt_regs *regs)
 347 {
 348         if (p->ss_addr) {
 349                 regs->ARM_pc = (unsigned long)p->ss_addr;
 350                 p->ss_addr = NULL;
 351         } else {
 352                 regs->ARM_pc = (unsigned long)p->ainsn.insn;
 353         }
 354 }
 355
 356 void save_previous_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p_run)
 357 {
 358         if (p_run == NULL) {
 359                 panic("arm_save_previous_kprobe: p_run == NULL\n");
 360         }
 361
 362         if (kcb->prev_kprobe.kp != NULL) {
 363                 DBPRINTF ("no space to save new probe[]: task = %d/%s", current->pid, current->comm);
 364         }
 365
 366         kcb->prev_kprobe.kp = p_run;
 367         kcb->prev_kprobe.status = kcb->kprobe_status;
 368 }
 369
 370 void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 371 {
 372         set_current_kprobe(kcb->prev_kprobe.kp, NULL, NULL);
 373         kcb->kprobe_status = kcb->prev_kprobe.status;
 374         kcb->prev_kprobe.kp = NULL;
 375         kcb->prev_kprobe.status = 0;
 376 }
 377
 378 void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
 379 {
 380         __get_cpu_var(current_kprobe) = p;
 381         DBPRINTF ("set_current_kprobe: p=%p addr=%p\n", p, p->addr);
 382 }
 383 EXPORT_SYMBOL_GPL(set_current_kprobe);
 384
 385 #ifdef TRAP_OVERHEAD_DEBUG
 386 static unsigned long trap_handler_counter_debug = 0;
 387 #define SAMPLING_COUNTER                               100000
 388 #endif
 389
 390 static int kprobe_handler(struct pt_regs *regs)
 391 {
 392         int err_out = 0;
 393         char *msg_out = NULL;
 394         kprobe_opcode_t *addr = (kprobe_opcode_t *) (regs->ARM_pc);
 395
 396         struct kprobe *p = NULL, *p_run = NULL;
 397         int ret = 0, retprobe = 0, reenter = 0;
 398         kprobe_opcode_t *ssaddr = NULL;
 399         struct kprobe_ctlblk *kcb;
 400
 401 #ifdef SUPRESS_BUG_MESSAGES
 402         int swap_oops_in_progress;
 403         // oops_in_progress used to avoid BUG() messages that slow down kprobe_handler() execution
 404         swap_oops_in_progress = oops_in_progress;
 405         oops_in_progress = 1;
 406 #endif
 407 #ifdef TRAP_OVERHEAD_DEBUG
 408         trap_handler_counter_debug++;
 409         if ( trap_handler_counter_debug < SAMPLING_COUNTER ) {
 410                 err_out = 0;
 411         }
 412         else {
 413                 // XXX NOTE - user must care about catching signal via signal handler to avoid hanging!
 414                 printk("Trap %ld reached - send SIGUSR1\n", trap_handler_counter_debug);
 415                 kill_pid(get_task_pid(current, PIDTYPE_PID), SIGUSR1, 1);
 416                 trap_handler_counter_debug = 0;
 417                 err_out = 0;
 418         }
 419         return err_out;
 420 #endif
 421 #ifdef OVERHEAD_DEBUG
 422         struct timeval swap_tv1;
 423         struct timeval swap_tv2;
 424 #define USEC_IN_SEC_NUM                         1000000
 425         do_gettimeofday(&swap_tv1);
 426 #endif
 427         preempt_disable();
 428
 429         p = get_kprobe(addr, 0);
 430
 431         /* We're in an interrupt, but this is clear and BUG()-safe. */
 432         kcb = get_kprobe_ctlblk ();
 433
 434         /* Check we're not actually recursing */
 435         // TODO: event is not saving in trace
 436         p_run = kprobe_running();
 437         if (p_run)
 438         {
 439                 DBPRINTF("lock???");
 440                 if (p)
 441                 {
 442                         if (addr == (kprobe_opcode_t *)kretprobe_trampoline) {
 443                                 save_previous_kprobe(kcb, p_run);
 444                                 kcb->kprobe_status = KPROBE_REENTER;
 445                                 reenter = 1;
 446                         } else {
 447                                 /* We have reentered the kprobe_handler(), since
 448                                  * another probe was hit while within the handler.
 449                                  * We here save the original kprobes variables and
 450                                  * just single step on the instruction of the new probe
 451                                  * without calling any user handlers.
 452                                  */
 453                                 kprobes_inc_nmissed_count (p);
 454                                 prepare_singlestep (p, regs);
 455
 456                                 err_out = 0;
 457                                 goto out;
 458                         }
 459                 } else {
 460                         if(!p) {
 461                                 p = p_run;
 462                                 DBPRINTF ("kprobe_running !!! p = 0x%p p->break_handler = 0x%p", p, p->break_handler);
 463                                 /*if (p->break_handler && p->break_handler(p, regs)) {
 464                                   DBPRINTF("kprobe_running !!! goto ss");
 465                                   goto ss_probe;
 466                                   } */
 467                                 DBPRINTF ("unknown uprobe at %p cur at %p/%p\n", addr, p->addr, p->ainsn.insn);
 468                                 ssaddr = p->ainsn.insn + KPROBES_TRAMP_SS_BREAK_IDX;
 469                                 if (addr == ssaddr) {
 470                                         regs->ARM_pc = (unsigned long) (p->addr + 1);
 471                                         DBPRINTF ("finish step at %p cur at %p/%p, redirect to %lx\n", addr, p->addr, p->ainsn.insn, regs->ARM_pc);
 472                                         if (kcb->kprobe_status == KPROBE_REENTER) {
 473                                                 restore_previous_kprobe(kcb);
 474                                         } else {
 475                                                 reset_current_kprobe();
 476                                         }
 477                                 }
 478                                 DBPRINTF ("kprobe_running !!! goto no");
 479                                 ret = 1;
 480                                 /* If it's not ours, can't be delete race, (we hold lock). */
 481                                 DBPRINTF ("no_kprobe");
 482                                 goto no_kprobe;
 483                         }
 484                 }
 485         }
 486
 487         if (!p) {
 488                 /* Not one of ours: let kernel handle it */
 489                 DBPRINTF ("no_kprobe");
 490                 goto no_kprobe;
 491         }
 492
 493         set_current_kprobe(p, NULL, NULL);
 494         if(!reenter)
 495                 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 496         if (retprobe) {         //(einsn == UNDEF_INSTRUCTION)
 497                 ret = trampoline_probe_handler (p, regs);
 498         } else if (p->pre_handler) {
 499                 ret = p->pre_handler (p, regs);
 500                 if(p->pre_handler != trampoline_probe_handler) {
 501                         reset_current_kprobe();
 502                 }
 503         }
 504
 505         if (ret) {
 506                 /* handler has already set things up, so skip ss setup */
 507                 err_out = 0;
 508                 goto out;
 509         }
 510
 511 no_kprobe:
 512         msg_out = "no_kprobe\n";
 513         err_out = 1;            // return with death
 514         goto out;
 515
 516 out:
 517         preempt_enable_no_resched();
 518 #ifdef OVERHEAD_DEBUG
 519         do_gettimeofday(&swap_tv2);
 520         swap_sum_hit++;
 521         swap_sum_time += ((swap_tv2.tv_sec - swap_tv1.tv_sec) *  USEC_IN_SEC_NUM +
 522                 (swap_tv2.tv_usec - swap_tv1.tv_usec));
 523 #endif
 524 #ifdef SUPRESS_BUG_MESSAGES
 525         oops_in_progress = swap_oops_in_progress;
 526 #endif
 527
 528         if(msg_out) {
 529                 printk(msg_out);
 530         }
 531
 532         return err_out;
 533 }
 534
 535 int kprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
 536 {
 537         int ret;
 538         unsigned long flags;
 539         local_irq_save(flags);
 540         ret = kprobe_handler(regs);
 541         local_irq_restore(flags);
 542         return ret;
 543 }
 544
 545 int setjmp_pre_handler (struct kprobe *p, struct pt_regs *regs)
 546 {
 547         struct jprobe *jp = container_of (p, struct jprobe, kp);
 548         kprobe_pre_entry_handler_t pre_entry;
 549         entry_point_t entry;
 550
 551 # ifdef REENTER
 552 //      p = kprobe_running(regs);
 553 # endif
 554
 555         DBPRINTF ("pjp = 0x%p jp->entry = 0x%p", jp, jp->entry);
 556         entry = (entry_point_t) jp->entry;
 557         pre_entry = (kprobe_pre_entry_handler_t) jp->pre_entry;
 558         //if(!entry)
 559         //      DIE("entry NULL", regs)
 560         DBPRINTF ("entry = 0x%p jp->entry = 0x%p", entry, jp->entry);
 561
 562         //call handler for all kernel probes and user space ones which belong to current tgid
 563         if (!p->tgid || (p->tgid == current->tgid))
 564         {
 565                 if(!p->tgid && ((unsigned int)p->addr == sched_addr) && sched_rp) {
 566                         struct thread_info *tinfo = (struct thread_info *)regs->ARM_r2;
 567                         patch_suspended_task(sched_rp, tinfo->task);
 568                 }
 569                 if (pre_entry)
 570                         p->ss_addr = (void *)pre_entry (jp->priv_arg, regs);
 571                 if (entry){
 572                         entry (regs->ARM_r0, regs->ARM_r1, regs->ARM_r2, regs->ARM_r3, regs->ARM_r4, regs->ARM_r5);
 573                 }
 574                 else {
 575                         if (p->tgid)
 576                                 dbi_arch_uprobe_return ();
 577                         else
 578                                 dbi_jprobe_return ();
 579                 }
 580         }
 581         else if (p->tgid)
 582                 dbi_arch_uprobe_return ();
 583
 584         prepare_singlestep (p, regs);
 585
 586         return 1;
 587 }
 588 EXPORT_SYMBOL_GPL(setjmp_pre_handler);
 589
 590 void dbi_jprobe_return (void)
 591 {
 592 }
 593
 594 void dbi_arch_uprobe_return (void)
 595 {
 596 }
 597 EXPORT_SYMBOL_GPL(dbi_arch_uprobe_return);
 598
 599 int longjmp_break_handler (struct kprobe *p, struct pt_regs *regs)
 600 {
 601 # ifndef REENTER
 602         //kprobe_opcode_t insn = BREAKPOINT_INSTRUCTION;
 603         kprobe_opcode_t insns[2];
 604
 605         if (p->pid)
 606         {
 607                 insns[0] = BREAKPOINT_INSTRUCTION;
 608                 insns[1] = p->opcode;
 609                 //p->opcode = *p->addr;
 610                 if (read_proc_vm_atomic (current, (unsigned long) (p->addr), &(p->opcode), sizeof (p->opcode)) < sizeof (p->opcode))
 611                 {
 612                         printk ("ERROR[%lu]: failed to read vm of proc %s/%u addr %p.", nCount, current->comm, current->pid, p->addr);
 613                         return -1;
 614                 }
 615                 //*p->addr = BREAKPOINT_INSTRUCTION;
 616                 //*(p->addr+1) = p->opcode;
 617                 if (write_proc_vm_atomic (current, (unsigned long) (p->addr), insns, sizeof (insns)) < sizeof (insns))
 618                 {
 619                         printk ("ERROR[%lu]: failed to write vm of proc %s/%u addr %p.", nCount, current->comm, current->pid, p->addr);
 620                         return -1;
 621                 }
 622         }
 623         else
 624         {
 625                 DBPRINTF ("p->opcode = 0x%lx *p->addr = 0x%lx p->addr = 0x%p\n", p->opcode, *p->addr, p->addr);
 626                 *(p->addr + 1) = p->opcode;
 627                 p->opcode = *p->addr;
 628                 *p->addr = BREAKPOINT_INSTRUCTION;
 629
 630                 flush_icache_range ((unsigned int) p->addr, (unsigned int) (((unsigned int) p->addr) + (sizeof (kprobe_opcode_t) * 2)));
 631         }
 632
 633         reset_current_kprobe();
 634
 635 #endif //REENTER
 636
 637         return 0;
 638 }
 639 EXPORT_SYMBOL_GPL(longjmp_break_handler);
 640
 641 void arch_arm_kprobe (struct kprobe *p)
 642 {
 643         *p->addr = BREAKPOINT_INSTRUCTION;
 644         flush_icache_range ((unsigned long) p->addr, (unsigned long) p->addr + sizeof (kprobe_opcode_t));
 645 }
 646
 647 void arch_disarm_kprobe (struct kprobe *p)
 648 {
 649         *p->addr = p->opcode;
 650         flush_icache_range ((unsigned long) p->addr, (unsigned long) p->addr + sizeof (kprobe_opcode_t));
 651 }
 652
 653
 654 int trampoline_probe_handler (struct kprobe *p, struct pt_regs *regs)
 655 {
 656         struct kretprobe_instance *ri = NULL;
 657         struct hlist_head *head;
 658         struct hlist_node *node, *tmp;
 659         unsigned long flags, orig_ret_address = 0;
 660         unsigned long trampoline_address = (unsigned long) &kretprobe_trampoline;
 661
 662         struct kretprobe *crp = NULL;
 663         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk ();
 664
 665         DBPRINTF ("start");
 666
 667         if (p && p->tgid){
 668                 // in case of user space retprobe trampoline is at the Nth instruction of US tramp
 669                 if (!thumb_mode( regs ))
 670                         trampoline_address = (unsigned long)(p->ainsn.insn + UPROBES_TRAMP_RET_BREAK_IDX);
 671                 else
 672                         trampoline_address = (unsigned long)(p->ainsn.insn) + 0x1b;
 673         }
 674
 675         spin_lock_irqsave (&kretprobe_lock, flags);
 676
 677         /*
 678          * We are using different hash keys (current and mm) for finding kernel
 679          * space and user space probes.  Kernel space probes can change mm field in
 680          * task_struct.  User space probes can be shared between threads of one
 681          * process so they have different current but same mm.
 682          */
 683         if (p && p->tgid) {
 684                 head = kretprobe_inst_table_head(current->mm);
 685         } else {
 686                 head = kretprobe_inst_table_head(current);
 687         }
 688
 689         /*
 690          * It is possible to have multiple instances associated with a given
 691          * task either because an multiple functions in the call path
 692          * have a return probe installed on them, and/or more then one
 693          * return probe was registered for a target function.
 694          *
 695          * We can handle this because:
 696          *     - instances are always inserted at the head of the list
 697          *     - when multiple return probes are registered for the same
 698          *       function, the first instance's ret_addr will point to the
 699          *       real return address, and all the rest will point to
 700          *       kretprobe_trampoline
 701          */
 702         hlist_for_each_entry_safe (ri, node, tmp, head, hlist)
 703         {
 704                 if (ri->task != current)
 705                         /* another task is sharing our hash bucket */
 706                         continue;
 707                 if (ri->rp && ri->rp->handler){
 708                         ri->rp->handler (ri, regs, ri->rp->priv_arg);
 709                 }
 710
 711                 orig_ret_address = (unsigned long) ri->ret_addr;
 712                 recycle_rp_inst (ri);
 713                 if (orig_ret_address != trampoline_address)
 714                         /*
 715                          * This is the real return address. Any other
 716                          * instances associated with this task are for
 717                          * other calls deeper on the call stack
 718                          */
 719                         break;
 720         }
 721         kretprobe_assert (ri, orig_ret_address, trampoline_address);
 722         //BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 723         //E.G. Check this code in case of __switch_to function instrumentation -- currently this code generates dump in this case
 724         //if (trampoline_address != (unsigned long) &kretprobe_trampoline){
 725         //if (ri->rp2) BUG_ON (ri->rp2->kp.tgid == 0);
 726         //if (ri->rp) BUG_ON (ri->rp->kp.tgid == 0);
 727         //else if (ri->rp2) BUG_ON (ri->rp2->kp.tgid == 0);
 728         //}
 729         if ((ri->rp && ri->rp->kp.tgid) || (ri->rp2 && ri->rp2->kp.tgid))
 730                 BUG_ON (trampoline_address == (unsigned long) &kretprobe_trampoline);
 731
 732         regs->uregs[14] = orig_ret_address;
 733         DBPRINTF ("regs->uregs[14] = 0x%lx\n", regs->uregs[14]);
 734         DBPRINTF ("regs->uregs[15] = 0x%lx\n", regs->uregs[15]);
 735
 736         if (trampoline_address != (unsigned long) &kretprobe_trampoline)
 737         {
 738                 regs->uregs[15] = orig_ret_address;
 739         }else{
 740                 if (!thumb_mode( regs )) regs->uregs[15] += 4;
 741                 else regs->uregs[15] += 2;
 742         }
 743
 744         DBPRINTF ("regs->uregs[15] = 0x%lx\n", regs->uregs[15]);
 745
 746         if(p){ // ARM, MIPS, X86 user space
 747                 if (thumb_mode( regs ) && !(regs->uregs[14] & 0x01))
 748                 {
 749                         regs->ARM_cpsr &= 0xFFFFFFDF;
 750                 }else{
 751                         if (user_mode( regs ) && (regs->uregs[14] & 0x01))
 752                         {
 753                                 regs->ARM_cpsr |= 0x20;
 754                         }
 755                 }
 756
 757                 //TODO: test - enter function, delete us retprobe, exit function
 758                 // for user space retprobes only - deferred deletion
 759
 760                 if (trampoline_address != (unsigned long) &kretprobe_trampoline)
 761                 {
 762                         // if we are not at the end of the list and current retprobe should be disarmed
 763                         if (node && ri->rp2)
 764                         {
 765                                 struct hlist_node *current_node = node;
 766                                 crp = ri->rp2;
 767                                 /*sprintf(die_msg, "deferred disarm p->addr = %p [%lx %lx %lx]\n",
 768                                   crp->kp.addr, *kaddrs[0], *kaddrs[1], *kaddrs[2]);
 769                                   DIE(die_msg, regs); */
 770                                 // look for other instances for the same retprobe
 771                                 hlist_for_each_entry_safe (ri, node, tmp, head, hlist)
 772                                 {
 773                                         /*
 774                                          * Trying to find another retprobe instance associated with
 775                                          * the same retprobe.
 776                                          */
 777                                         if (ri->rp2 == crp && node != current_node)
 778                                                 break;
 779                                 }
 780
 781                                 if (!node)
 782                                 {
 783                                         // if there are no more instances for this retprobe
 784                                         // delete retprobe
 785                                         struct kprobe *is_p = &crp->kp;
 786                                         DBPRINTF ("defered retprobe deletion p->addr = %p", crp->kp.addr);
 787                                         /*
 788                                           If there is no any retprobe instances of this retprobe
 789                                           we can free the resources related to the probe.
 790                                          */
 791                                         if (!(hlist_unhashed(&is_p->is_hlist_arm))) {
 792                                                 hlist_del_rcu(&is_p->is_hlist_arm);
 793                                         }
 794                                         if (!(hlist_unhashed(&is_p->is_hlist_thumb))) {
 795                                                 hlist_del_rcu(&is_p->is_hlist_thumb);
 796                                         }
 797
 798                                         dbi_unregister_kprobe(&crp->kp, current);
 799                                         kfree (crp);
 800                                 }
 801                                 hlist_del(current_node);
 802                         }
 803                 }
 804
 805                 if (kcb->kprobe_status == KPROBE_REENTER) {
 806                         restore_previous_kprobe(kcb);
 807                 } else {
 808                         reset_current_kprobe();
 809                 }
 810         }
 811
 812         spin_unlock_irqrestore (&kretprobe_lock, flags);
 813
 814         /*
 815          * By returning a non-zero value, we are telling
 816          * kprobe_handler() that we don't want the post_handler
 817          * to run (and have re-enabled preemption)
 818          */
 819
 820         return 1;
 821 }
 822 EXPORT_SYMBOL_GPL(trampoline_probe_handler);
 823
 824 void  __arch_prepare_kretprobe (struct kretprobe *rp, struct pt_regs *regs)
 825 {
 826         struct kretprobe_instance *ri;
 827
 828         DBPRINTF ("start\n");
 829         //TODO: test - remove retprobe after func entry but before its exit
 830         if ((ri = get_free_rp_inst (rp)) != NULL)
 831         {
 832                 ri->rp = rp;
 833                 ri->rp2 = NULL;
 834                 ri->task = current;
 835                 ri->ret_addr = (kprobe_opcode_t *) regs->uregs[14];
 836                 ri->sp = (kprobe_opcode_t *)regs->ARM_sp; //uregs[13];
 837
 838                 if (rp->kp.tgid)
 839                         if (!thumb_mode( regs ))
 840                                 regs->uregs[14] = (unsigned long) (rp->kp.ainsn.insn + UPROBES_TRAMP_RET_BREAK_IDX);
 841                         else
 842                                 regs->uregs[14] = (unsigned long) (rp->kp.ainsn.insn) + 0x1b;
 843
 844                 else    /* Replace the return addr with trampoline addr */
 845                         regs->uregs[14] = (unsigned long) &kretprobe_trampoline;
 846
 847 //              DBPRINTF ("ret addr set to %p->%lx\n", ri->ret_addr, regs->uregs[14]);
 848                 add_rp_inst (ri);
 849         }
 850         else {
 851                 DBPRINTF ("WARNING: missed retprobe %p\n", rp->kp.addr);
 852                 rp->nmissed++;
 853         }
 854 }
 855
 856
 857 int asm_init_module_dependencies(void)
 858 {
 859         //No module dependencies
 860         return 0;
 861 }
 862
 863 void swap_register_undef_hook(struct undef_hook *hook)
 864 {
 865         __swap_register_undef_hook(hook);
 866 }
 867 EXPORT_SYMBOL_GPL(swap_register_undef_hook);
 868
 869 void swap_unregister_undef_hook(struct undef_hook *hook)
 870 {
 871         __swap_unregister_undef_hook(hook);
 872 }
 873 EXPORT_SYMBOL_GPL(swap_unregister_undef_hook);
 874
 875 // kernel probes hook
 876 static struct undef_hook undef_ho_k = {
 877     .instr_mask = 0xffffffff,
 878     .instr_val  = BREAKPOINT_INSTRUCTION,
 879     .cpsr_mask  = MODE_MASK,
 880     .cpsr_val   = SVC_MODE,
 881     .fn         = kprobe_trap_handler
 882 };
 883
 884 int __init arch_init_kprobes (void)
 885 {
 886         unsigned int do_bp_handler = 0;
 887         int ret = 0;
 888
 889         if (arch_init_module_dependencies())
 890         {
 891                 DBPRINTF ("Unable to init module dependencies\n");
 892                 return -1;
 893         }
 894
 895         do_bp_handler = swap_ksyms("do_undefinstr");
 896         if (do_bp_handler == 0) {
 897                 DBPRINTF("no do_undefinstr symbol found!");
 898                 return -1;
 899         }
 900         arr_traps_template[NOTIFIER_CALL_CHAIN_INDEX] = arch_construct_brunch ((unsigned int)kprobe_handler, do_bp_handler + NOTIFIER_CALL_CHAIN_INDEX * 4, 1);
 901         // Register hooks (kprobe_handler)
 902         __swap_register_undef_hook = swap_ksyms("register_undef_hook");
 903         if (__swap_register_undef_hook == NULL) {
 904                 printk("no register_undef_hook symbol found!\n");
 905                 return -1;
 906         }
 907
 908         // Unregister hooks (kprobe_handler)
 909         __swap_unregister_undef_hook = swap_ksyms("unregister_undef_hook");
 910         if (__swap_unregister_undef_hook == NULL) {
 911                 printk("no unregister_undef_hook symbol found!\n");
 912                 return -1;
 913         }
 914
 915         swap_register_undef_hook(&undef_ho_k);
 916         if ((ret = dbi_register_kprobe (&trampoline_p)) != 0) {
 917                 //dbi_unregister_jprobe(&do_exit_p, 0);
 918                 return ret;
 919         }
 920         return ret;
 921 }
 922
 923 void __exit dbi_arch_exit_kprobes (void)
 924 {
 925         swap_unregister_undef_hook(&undef_ho_k);
 926 }
 927
 928 //EXPORT_SYMBOL_GPL (dbi_arch_uprobe_return);
 929 //EXPORT_SYMBOL_GPL (dbi_arch_exit_kprobes);