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 <kprobe/dbi_kprobes.h>
  38
  39 #include <kprobe/dbi_kdebug.h>
  40 #include <kprobe/dbi_insn_slots.h>
  41 #include <kprobe/dbi_kprobes_deps.h>
  42 #include <ksyms/ksyms.h>
  43
  44 #include <asm/cacheflush.h>
  45 #include <asm/traps.h>
  46 #include <asm/ptrace.h>
  47 #include <linux/list.h>
  48 #include <linux/hash.h>
  49
  50 #define SUPRESS_BUG_MESSAGES
  51
  52 extern struct kprobe * per_cpu__current_kprobe;
  53 extern struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  54
  55 static void (*__swap_register_undef_hook)(struct undef_hook *hook);
  56 static void (*__swap_unregister_undef_hook)(struct undef_hook *hook);
  57
  58 int prep_pc_dep_insn_execbuf(kprobe_opcode_t *insns, kprobe_opcode_t insn, int uregs)
  59 {
  60         int i;
  61
  62         if (uregs & 0x10) {
  63                 int reg_mask = 0x1;
  64                 //search in reg list
  65                 for (i = 0; i < 13; i++, reg_mask <<= 1) {
  66                         if (!(insn & reg_mask))
  67                                 break;
  68                 }
  69         } else {
  70                 for (i = 0; i < 13; i++) {
  71                         if ((uregs & 0x1) && (ARM_INSN_REG_RN(insn) == i))
  72                                 continue;
  73                         if ((uregs & 0x2) && (ARM_INSN_REG_RD(insn) == i))
  74                                 continue;
  75                         if ((uregs & 0x4) && (ARM_INSN_REG_RS(insn) == i))
  76                                 continue;
  77                         if ((uregs & 0x8) && (ARM_INSN_REG_RM(insn) == i))
  78                                 continue;
  79                         break;
  80                 }
  81         }
  82
  83         if (i == 13) {
  84                 DBPRINTF ("there are no free register %x in insn %lx!", uregs, insn);
  85                 return -EINVAL;
  86         }
  87         DBPRINTF ("prep_pc_dep_insn_execbuf: using R%d, changing regs %x", i, uregs);
  88
  89         // set register to save
  90         ARM_INSN_REG_SET_RD(insns[0], i);
  91         // set register to load address to
  92         ARM_INSN_REG_SET_RD(insns[1], i);
  93         // set instruction to execute and patch it
  94         if (uregs & 0x10) {
  95                 ARM_INSN_REG_CLEAR_MR(insn, 15);
  96                 ARM_INSN_REG_SET_MR(insn, i);
  97         } else {
  98                 if ((uregs & 0x1) && (ARM_INSN_REG_RN(insn) == 15))
  99                         ARM_INSN_REG_SET_RN(insn, i);
 100                 if ((uregs & 0x2) && (ARM_INSN_REG_RD(insn) == 15))
 101                         ARM_INSN_REG_SET_RD(insn, i);
 102                 if ((uregs & 0x4) && (ARM_INSN_REG_RS(insn) == 15))
 103                         ARM_INSN_REG_SET_RS(insn, i);
 104                 if ((uregs & 0x8) && (ARM_INSN_REG_RM(insn) == 15))
 105                         ARM_INSN_REG_SET_RM(insn, i);
 106         }
 107
 108         insns[UPROBES_TRAMP_INSN_IDX] = insn;
 109         // set register to restore
 110         ARM_INSN_REG_SET_RD(insns[3], i);
 111
 112         return 0;
 113 }
 114 EXPORT_SYMBOL_GPL(prep_pc_dep_insn_execbuf);
 115
 116 int arch_check_insn_arm(unsigned long insn)
 117 {
 118         /* check instructions that can change PC by nature */
 119         if (
 120          /* ARM_INSN_MATCH(UNDEF, insn) || */
 121             ARM_INSN_MATCH(AUNDEF, insn) ||
 122             ARM_INSN_MATCH(SWI, insn) ||
 123             ARM_INSN_MATCH(BREAK, insn) ||
 124             ARM_INSN_MATCH(BXJ, insn)) {
 125                 goto bad_insn;
 126 #ifndef CONFIG_CPU_V7
 127         /* check instructions that can write result to PC */
 128         } else if ((ARM_INSN_MATCH(DPIS, insn) ||
 129                     ARM_INSN_MATCH(DPRS, insn) ||
 130                     ARM_INSN_MATCH(DPI, insn) ||
 131                     ARM_INSN_MATCH(LIO, insn) ||
 132                     ARM_INSN_MATCH(LRO, insn)) &&
 133                    (ARM_INSN_REG_RD(insn) == 15)) {
 134                 goto bad_insn;
 135 #endif /* CONFIG_CPU_V7 */
 136         /* check special instruction loads store multiple registers */
 137         } else if ((ARM_INSN_MATCH(LM, insn) || ARM_INSN_MATCH(SM, insn)) &&
 138                         /* store PC or load to PC */
 139                    (ARM_INSN_REG_MR(insn, 15) ||
 140                          /* store/load with PC update */
 141                     ((ARM_INSN_REG_RN(insn) == 15) && (insn & 0x200000)))) {
 142                 goto bad_insn;
 143         }
 144
 145         return 0;
 146
 147 bad_insn:
 148         printk("Bad insn arch_check_insn_arm: %lx\n", insn);
 149         return -EFAULT;
 150 }
 151 EXPORT_SYMBOL_GPL(arch_check_insn_arm);
 152
 153 int arch_prepare_kprobe(struct kprobe *p, struct slot_manager *sm)
 154 {
 155         kprobe_opcode_t insns[KPROBES_TRAMP_LEN];
 156         int uregs, pc_dep, ret = 0;
 157         kprobe_opcode_t insn[MAX_INSN_SIZE];
 158         struct arch_specific_insn ainsn;
 159
 160         /* insn: must be on special executable page on i386. */
 161         p->ainsn.insn = alloc_insn_slot(sm);
 162         if (!p->ainsn.insn)
 163                 return -ENOMEM;
 164
 165         memcpy(insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
 166         ainsn.insn_arm = ainsn.insn = insn;
 167         ret = arch_check_insn_arm(insn[0]);
 168         if (!ret) {
 169                 p->opcode = *p->addr;
 170                 uregs = pc_dep = 0;
 171
 172                 // Rn, Rm ,Rd
 173                 if (ARM_INSN_MATCH(DPIS, insn[0]) || ARM_INSN_MATCH(LRO, insn[0]) ||
 174                     ARM_INSN_MATCH(SRO, insn[0])) {
 175                         uregs = 0xb;
 176                         if ((ARM_INSN_REG_RN(insn[0]) == 15) || (ARM_INSN_REG_RM(insn[0]) == 15) ||
 177                             (ARM_INSN_MATCH(SRO, insn[0]) && (ARM_INSN_REG_RD(insn[0]) == 15))) {
 178                                 DBPRINTF ("Unboostable insn %lx, DPIS/LRO/SRO\n", insn[0]);
 179                                 pc_dep = 1;
 180                         }
 181
 182                 // Rn ,Rd
 183                 } else if( ARM_INSN_MATCH(DPI, insn[0]) || ARM_INSN_MATCH(LIO, insn[0]) ||
 184                            ARM_INSN_MATCH(SIO, insn[0])) {
 185                         uregs = 0x3;
 186                         if ((ARM_INSN_REG_RN(insn[0]) == 15) || (ARM_INSN_MATCH(SIO, insn[0]) &&
 187                             (ARM_INSN_REG_RD (insn[0]) == 15))) {
 188                                 pc_dep = 1;
 189                                 DBPRINTF ("Unboostable insn %lx/%p, DPI/LIO/SIO\n", insn[0], p);
 190                         }
 191                 // Rn, Rm, Rs
 192                 } else if (ARM_INSN_MATCH(DPRS, insn[0])) {
 193                         uregs = 0xd;
 194                         if ((ARM_INSN_REG_RN(insn[0]) == 15) || (ARM_INSN_REG_RM(insn[0]) == 15) ||
 195                             (ARM_INSN_REG_RS (insn[0]) == 15)) {
 196                                 pc_dep = 1;
 197                                 DBPRINTF ("Unboostable insn %lx, DPRS\n", insn[0]);
 198                         }
 199                 // register list
 200                 } else if(ARM_INSN_MATCH(SM, insn[0])) {
 201                         uregs = 0x10;
 202                         if (ARM_INSN_REG_MR(insn[0], 15)) {
 203                                 DBPRINTF ("Unboostable insn %lx, SM\n", insn[0]);
 204                                 pc_dep = 1;
 205                         }
 206                 }
 207
 208                 // check instructions that can write result to SP andu uses PC
 209                 if (pc_dep  && (ARM_INSN_REG_RD(ainsn.insn[0]) == 13)) {
 210                         free_insn_slot(sm, p->ainsn.insn);
 211                         ret = -EFAULT;
 212                 } else {
 213                         if (uregs && pc_dep) {
 214                                 memcpy(insns, pc_dep_insn_execbuf, sizeof(insns));
 215                                 if (prep_pc_dep_insn_execbuf(insns, insn[0], uregs) != 0) {
 216                                         DBPRINTF ("failed to prepare exec buffer for insn %lx!", insn[0]);
 217                                         free_insn_slot(sm, p->ainsn.insn);
 218                                         return -EINVAL;
 219                                 }
 220                                 insns[6] = (kprobe_opcode_t)(p->addr + 2);
 221                         } else {
 222                                 memcpy(insns, gen_insn_execbuf, sizeof(insns));
 223                                 insns[KPROBES_TRAMP_INSN_IDX] = insn[0];
 224                         }
 225                         insns[7] = (kprobe_opcode_t)(p->addr + 1);
 226                         DBPRINTF ("arch_prepare_kprobe: insn %lx", insn[0]);
 227                         DBPRINTF ("arch_prepare_kprobe: to %p - %lx %lx %lx %lx %lx %lx %lx %lx %lx",
 228                                   p->ainsn.insn, insns[0], insns[1], insns[2], insns[3], insns[4],
 229                                   insns[5], insns[6], insns[7], insns[8]);
 230                         memcpy(p->ainsn.insn, insns, sizeof(insns));
 231                         flush_icache_range((long unsigned)p->ainsn.insn, (long unsigned)(p->ainsn.insn) + sizeof(insns));
 232 #ifdef BOARD_tegra
 233                         flush_cache_all();
 234 #endif
 235                 }
 236         } else {
 237                 free_insn_slot(sm, p->ainsn.insn);
 238                 printk("arch_prepare_kprobe: instruction 0x%lx not instrumentation, addr=0x%p\n", insn[0], p->addr);
 239         }
 240
 241         return ret;
 242 }
 243
 244 void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 245 {
 246         if (p->ss_addr) {
 247                 regs->ARM_pc = (unsigned long)p->ss_addr;
 248                 p->ss_addr = NULL;
 249         } else {
 250                 regs->ARM_pc = (unsigned long)p->ainsn.insn;
 251         }
 252 }
 253 EXPORT_SYMBOL_GPL(prepare_singlestep);
 254
 255 void save_previous_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p_run)
 256 {
 257         kcb->prev_kprobe.kp = kprobe_running();
 258         kcb->prev_kprobe.status = kcb->kprobe_status;
 259 }
 260
 261 void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 262 {
 263         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 264         kcb->kprobe_status = kcb->prev_kprobe.status;
 265 }
 266
 267 void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
 268 {
 269         __get_cpu_var(current_kprobe) = p;
 270         DBPRINTF ("set_current_kprobe: p=%p addr=%p\n", p, p->addr);
 271 }
 272
 273 static int kprobe_handler(struct pt_regs *regs)
 274 {
 275         struct kprobe *p, *cur;
 276         struct kprobe_ctlblk *kcb;
 277
 278         kcb = get_kprobe_ctlblk();
 279         cur = kprobe_running();
 280         p = get_kprobe((void *)regs->ARM_pc);
 281
 282         if (p) {
 283                 if (cur) {
 284                         /* Kprobe is pending, so we're recursing. */
 285                         switch (kcb->kprobe_status) {
 286                         case KPROBE_HIT_ACTIVE:
 287                         case KPROBE_HIT_SSDONE:
 288                                 /* A pre- or post-handler probe got us here. */
 289                                 kprobes_inc_nmissed_count(p);
 290                                 save_previous_kprobe(kcb, NULL);
 291                                 set_current_kprobe(p, 0, 0);
 292                                 kcb->kprobe_status = KPROBE_REENTER;
 293                                 prepare_singlestep(p, regs);
 294                                 restore_previous_kprobe(kcb);
 295                                 break;
 296                         default:
 297                                 /* impossible cases */
 298                                 BUG();
 299                         }
 300                 } else {
 301                         set_current_kprobe(p, 0, 0);
 302                         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 303
 304                         if (!p->pre_handler || !p->pre_handler(p, regs)) {
 305                                 kcb->kprobe_status = KPROBE_HIT_SS;
 306                                 prepare_singlestep(p, regs);
 307                                 reset_current_kprobe();
 308                         }
 309                 }
 310         } else {
 311                 goto no_kprobe;
 312         }
 313
 314         return 0;
 315
 316 no_kprobe:
 317         printk("no_kprobe: Not one of ours: let kernel handle it %p\n",
 318                         (unsigned long *)regs->ARM_pc);
 319         return 1;
 320 }
 321
 322 int kprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
 323 {
 324         int ret;
 325         unsigned long flags;
 326
 327 #ifdef SUPRESS_BUG_MESSAGES
 328         int swap_oops_in_progress;
 329         /* oops_in_progress used to avoid BUG() messages
 330          * that slow down kprobe_handler() execution */
 331         swap_oops_in_progress = oops_in_progress;
 332         oops_in_progress = 1;
 333 #endif
 334
 335         local_irq_save(flags);
 336         preempt_disable();
 337         ret = kprobe_handler(regs);
 338         preempt_enable_no_resched();
 339         local_irq_restore(flags);
 340
 341 #ifdef SUPRESS_BUG_MESSAGES
 342         oops_in_progress = swap_oops_in_progress;
 343 #endif
 344
 345         return ret;
 346 }
 347
 348 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 349 {
 350         struct jprobe *jp = container_of(p, struct jprobe, kp);
 351         kprobe_pre_entry_handler_t pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
 352         entry_point_t entry = (entry_point_t)jp->entry;
 353         pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
 354
 355         if (pre_entry) {
 356                 p->ss_addr = (void *)pre_entry (jp->priv_arg, regs);
 357         }
 358
 359         if (entry) {
 360                 entry(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2,
 361                       regs->ARM_r3, regs->ARM_r4, regs->ARM_r5);
 362         } else {
 363                 dbi_jprobe_return();
 364         }
 365
 366         return 0;
 367 }
 368
 369 void dbi_jprobe_return (void)
 370 {
 371 }
 372
 373 int longjmp_break_handler (struct kprobe *p, struct pt_regs *regs)
 374 {
 375         return 0;
 376 }
 377 EXPORT_SYMBOL_GPL(longjmp_break_handler);
 378
 379 #ifdef CONFIG_STRICT_MEMORY_RWX
 380 extern void mem_text_write_kernel_word(unsigned long *addr, unsigned long word);
 381 #endif
 382
 383 void arch_arm_kprobe(struct kprobe *p)
 384 {
 385 #ifdef CONFIG_STRICT_MEMORY_RWX
 386         mem_text_write_kernel_word(p->addr, BREAKPOINT_INSTRUCTION);
 387 #else
 388         *p->addr = BREAKPOINT_INSTRUCTION;
 389         flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t));
 390 #endif
 391 }
 392
 393 void arch_disarm_kprobe(struct kprobe *p)
 394 {
 395 #ifdef CONFIG_STRICT_MEMORY_RWX
 396         mem_text_write_kernel_word(p->addr, p->opcode);
 397 #else
 398         *p->addr = p->opcode;
 399         flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t));
 400 #endif
 401 }
 402
 403 void __naked kretprobe_trampoline(void)
 404 {
 405         __asm__ __volatile__ (
 406                 "stmdb  sp!, {r0 - r11}         \n\t"
 407                 "mov    r1, sp                  \n\t"
 408                 "mov    r0, #0                  \n\t"
 409                 "bl     trampoline_probe_handler\n\t"
 410                 "mov    lr, r0                  \n\t"
 411                 "ldmia  sp!, {r0 - r11}         \n\t"
 412                 "bx     lr                      \n\t"
 413                 : : : "memory");
 414 }
 415
 416 void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
 417 {
 418         unsigned long *ptr_ret_addr;
 419
 420         /* for __switch_to probe */
 421         if ((unsigned long)ri->rp->kp.addr == sched_addr) {
 422                 struct thread_info *tinfo = (struct thread_info *)regs->ARM_r2;
 423
 424                 ptr_ret_addr = (unsigned long *)&tinfo->cpu_context.pc;
 425                 ri->sp = NULL;
 426                 ri->task = tinfo->task;
 427         } else {
 428                 ptr_ret_addr = (unsigned long *)&regs->ARM_lr;
 429                 ri->sp = (unsigned long *)regs->ARM_sp;
 430         }
 431
 432         /* Save the return address */
 433         ri->ret_addr = (unsigned long *)*ptr_ret_addr;
 434
 435         /* Replace the return addr with trampoline addr */
 436         *ptr_ret_addr = (unsigned long)&kretprobe_trampoline;
 437 }
 438
 439 void swap_register_undef_hook(struct undef_hook *hook)
 440 {
 441         __swap_register_undef_hook(hook);
 442 }
 443 EXPORT_SYMBOL_GPL(swap_register_undef_hook);
 444
 445 void swap_unregister_undef_hook(struct undef_hook *hook)
 446 {
 447         __swap_unregister_undef_hook(hook);
 448 }
 449 EXPORT_SYMBOL_GPL(swap_unregister_undef_hook);
 450
 451 // kernel probes hook
 452 static struct undef_hook undef_ho_k = {
 453         .instr_mask     = 0xffffffff,
 454         .instr_val      = BREAKPOINT_INSTRUCTION,
 455         .cpsr_mask      = MODE_MASK,
 456         .cpsr_val       = SVC_MODE,
 457         .fn             = kprobe_trap_handler
 458 };
 459
 460 int arch_init_kprobes(void)
 461 {
 462         // Register hooks (kprobe_handler)
 463         __swap_register_undef_hook = (void *)swap_ksyms("register_undef_hook");
 464         if (__swap_register_undef_hook == NULL) {
 465                 printk("no register_undef_hook symbol found!\n");
 466                 return -1;
 467         }
 468
 469         // Unregister hooks (kprobe_handler)
 470         __swap_unregister_undef_hook = (void *)swap_ksyms("unregister_undef_hook");
 471         if (__swap_unregister_undef_hook == NULL) {
 472                 printk("no unregister_undef_hook symbol found!\n");
 473                 return -1;
 474         }
 475
 476         swap_register_undef_hook(&undef_ho_k);
 477
 478         return 0;
 479 }
 480
 481 void arch_exit_kprobes(void)
 482 {
 483         swap_unregister_undef_hook(&undef_ho_k);
 484 }
 485
 486 /* export symbol for trampoline_arm.h */
 487 EXPORT_SYMBOL_GPL(gen_insn_execbuf);
 488 EXPORT_SYMBOL_GPL(pc_dep_insn_execbuf);
 489 EXPORT_SYMBOL_GPL(b_r_insn_execbuf);
 490 EXPORT_SYMBOL_GPL(b_cond_insn_execbuf);
 491 EXPORT_SYMBOL_GPL(blx_off_insn_execbuf);