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   1 /*
   2  *  Kernel Probes (KProbes)
   3  *  arch/ia64/kernel/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) IBM Corporation, 2002, 2004
  20  * Copyright (C) Intel Corporation, 2005
  21  *
  22  * 2005-Apr     Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
  23  *              <anil.s.keshavamurthy@intel.com> adapted from i386
  24  */
  25
  26 #include <linux/config.h>
  27 #include <linux/kprobes.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/string.h>
  31 #include <linux/slab.h>
  32 #include <linux/preempt.h>
  33 #include <linux/moduleloader.h>
  34
  35 #include <asm/pgtable.h>
  36 #include <asm/kdebug.h>
  37
  38 extern void jprobe_inst_return(void);
  39
  40 /* kprobe_status settings */
  41 #define KPROBE_HIT_ACTIVE       0x00000001
  42 #define KPROBE_HIT_SS           0x00000002
  43
  44 static struct kprobe *current_kprobe, *kprobe_prev;
  45 static unsigned long kprobe_status, kprobe_status_prev;
  46 static struct pt_regs jprobe_saved_regs;
  47
  48 enum instruction_type {A, I, M, F, B, L, X, u};
  49 static enum instruction_type bundle_encoding[32][3] = {
  50   { M, I, I },                          /* 00 */
  51   { M, I, I },                          /* 01 */
  52   { M, I, I },                          /* 02 */
  53   { M, I, I },                          /* 03 */
  54   { M, L, X },                          /* 04 */
  55   { M, L, X },                          /* 05 */
  56   { u, u, u },                          /* 06 */
  57   { u, u, u },                          /* 07 */
  58   { M, M, I },                          /* 08 */
  59   { M, M, I },                          /* 09 */
  60   { M, M, I },                          /* 0A */
  61   { M, M, I },                          /* 0B */
  62   { M, F, I },                          /* 0C */
  63   { M, F, I },                          /* 0D */
  64   { M, M, F },                          /* 0E */
  65   { M, M, F },                          /* 0F */
  66   { M, I, B },                          /* 10 */
  67   { M, I, B },                          /* 11 */
  68   { M, B, B },                          /* 12 */
  69   { M, B, B },                          /* 13 */
  70   { u, u, u },                          /* 14 */
  71   { u, u, u },                          /* 15 */
  72   { B, B, B },                          /* 16 */
  73   { B, B, B },                          /* 17 */
  74   { M, M, B },                          /* 18 */
  75   { M, M, B },                          /* 19 */
  76   { u, u, u },                          /* 1A */
  77   { u, u, u },                          /* 1B */
  78   { M, F, B },                          /* 1C */
  79   { M, F, B },                          /* 1D */
  80   { u, u, u },                          /* 1E */
  81   { u, u, u },                          /* 1F */
  82 };
  83
  84 /*
  85  * In this function we check to see if the instruction
  86  * is IP relative instruction and update the kprobe
  87  * inst flag accordingly
  88  */
  89 static void update_kprobe_inst_flag(uint template, uint  slot, uint major_opcode,
  90         unsigned long kprobe_inst, struct kprobe *p)
  91 {
  92         p->ainsn.inst_flag = 0;
  93         p->ainsn.target_br_reg = 0;
  94
  95         if (bundle_encoding[template][slot] == B) {
  96                 switch (major_opcode) {
  97                   case INDIRECT_CALL_OPCODE:
  98                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
  99                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 100                         break;
 101                   case IP_RELATIVE_PREDICT_OPCODE:
 102                   case IP_RELATIVE_BRANCH_OPCODE:
 103                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 104                         break;
 105                   case IP_RELATIVE_CALL_OPCODE:
 106                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 107                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 108                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 109                         break;
 110                 }
 111         } else if (bundle_encoding[template][slot] == X) {
 112                 switch (major_opcode) {
 113                   case LONG_CALL_OPCODE:
 114                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 115                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 116                   break;
 117                 }
 118         }
 119         return;
 120 }
 121
 122 /*
 123  * In this function we check to see if the instruction
 124  * on which we are inserting kprobe is supported.
 125  * Returns 0 if supported
 126  * Returns -EINVAL if unsupported
 127  */
 128 static int unsupported_inst(uint template, uint  slot, uint major_opcode,
 129         unsigned long kprobe_inst, struct kprobe *p)
 130 {
 131         unsigned long addr = (unsigned long)p->addr;
 132
 133         if (bundle_encoding[template][slot] == I) {
 134                 switch (major_opcode) {
 135                         case 0x0: //I_UNIT_MISC_OPCODE:
 136                         /*
 137                          * Check for Integer speculation instruction
 138                          * - Bit 33-35 to be equal to 0x1
 139                          */
 140                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 141                                 printk(KERN_WARNING
 142                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 143                                         addr);
 144                                 return -EINVAL;
 145                         }
 146
 147                         /*
 148                          * IP relative mov instruction
 149                          *  - Bit 27-35 to be equal to 0x30
 150                          */
 151                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 152                                 printk(KERN_WARNING
 153                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 154                                         addr);
 155                                 return -EINVAL;
 156
 157                         }
 158                 }
 159         }
 160         return 0;
 161 }
 162
 163
 164 /*
 165  * In this function we check to see if the instruction
 166  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 167  * on which we are inserting kprobe is cmp instruction
 168  * with ctype as unc.
 169  */
 170 static uint is_cmp_ctype_unc_inst(uint template, uint slot, uint major_opcode,
 171 unsigned long kprobe_inst)
 172 {
 173         cmp_inst_t cmp_inst;
 174         uint ctype_unc = 0;
 175
 176         if (!((bundle_encoding[template][slot] == I) ||
 177                 (bundle_encoding[template][slot] == M)))
 178                 goto out;
 179
 180         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 181                 (major_opcode == 0xE)))
 182                 goto out;
 183
 184         cmp_inst.l = kprobe_inst;
 185         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 186                 /* Integere compare - Register Register (A6 type)*/
 187                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 188                                 &&(cmp_inst.f.c == 1))
 189                         ctype_unc = 1;
 190         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 191                 /* Integere compare - Immediate Register (A8 type)*/
 192                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 193                         ctype_unc = 1;
 194         }
 195 out:
 196         return ctype_unc;
 197 }
 198
 199 /*
 200  * In this function we override the bundle with
 201  * the break instruction at the given slot.
 202  */
 203 static void prepare_break_inst(uint template, uint  slot, uint major_opcode,
 204         unsigned long kprobe_inst, struct kprobe *p)
 205 {
 206         unsigned long break_inst = BREAK_INST;
 207         bundle_t *bundle = &p->ainsn.insn.bundle;
 208
 209         /*
 210          * Copy the original kprobe_inst qualifying predicate(qp)
 211          * to the break instruction iff !is_cmp_ctype_unc_inst
 212          * because for cmp instruction with ctype equal to unc,
 213          * which is a special instruction always needs to be
 214          * executed regradless of qp
 215          */
 216         if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
 217                 break_inst |= (0x3f & kprobe_inst);
 218
 219         switch (slot) {
 220           case 0:
 221                 bundle->quad0.slot0 = break_inst;
 222                 break;
 223           case 1:
 224                 bundle->quad0.slot1_p0 = break_inst;
 225                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 226                 break;
 227           case 2:
 228                 bundle->quad1.slot2 = break_inst;
 229                 break;
 230         }
 231
 232         /*
 233          * Update the instruction flag, so that we can
 234          * emulate the instruction properly after we
 235          * single step on original instruction
 236          */
 237         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 238 }
 239
 240 static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
 241                 unsigned long *kprobe_inst, uint *major_opcode)
 242 {
 243         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 244         unsigned int template;
 245
 246         template = bundle->quad0.template;
 247
 248         switch (slot) {
 249           case 0:
 250                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 251                 *kprobe_inst = bundle->quad0.slot0;
 252                 break;
 253           case 1:
 254                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 255                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 256                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 257                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 258                 break;
 259           case 2:
 260                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 261                 *kprobe_inst = bundle->quad1.slot2;
 262                 break;
 263         }
 264 }
 265
 266 static int valid_kprobe_addr(int template, int slot, unsigned long addr)
 267 {
 268         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 269                 printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n",
 270                                 addr);
 271                 return -EINVAL;
 272         }
 273         return 0;
 274 }
 275
 276 static inline void save_previous_kprobe(void)
 277 {
 278         kprobe_prev = current_kprobe;
 279         kprobe_status_prev = kprobe_status;
 280 }
 281
 282 static inline void restore_previous_kprobe(void)
 283 {
 284         current_kprobe = kprobe_prev;
 285         kprobe_status = kprobe_status_prev;
 286 }
 287
 288 static inline void set_current_kprobe(struct kprobe *p)
 289 {
 290         current_kprobe = p;
 291 }
 292
 293 int arch_prepare_kprobe(struct kprobe *p)
 294 {
 295         unsigned long addr = (unsigned long) p->addr;
 296         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 297         unsigned long kprobe_inst=0;
 298         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 299         bundle_t *bundle = &p->ainsn.insn.bundle;
 300
 301         memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
 302         memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));
 303
 304         template = bundle->quad0.template;
 305
 306         if(valid_kprobe_addr(template, slot, addr))
 307                 return -EINVAL;
 308
 309         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 310         if (slot == 1 && bundle_encoding[template][1] == L)
 311                 slot++;
 312
 313         /* Get kprobe_inst and major_opcode from the bundle */
 314         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 315
 316         if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
 317                         return -EINVAL;
 318
 319         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
 320
 321         return 0;
 322 }
 323
 324 void arch_arm_kprobe(struct kprobe *p)
 325 {
 326         unsigned long addr = (unsigned long)p->addr;
 327         unsigned long arm_addr = addr & ~0xFULL;
 328
 329         memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
 330         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 331 }
 332
 333 void arch_disarm_kprobe(struct kprobe *p)
 334 {
 335         unsigned long addr = (unsigned long)p->addr;
 336         unsigned long arm_addr = addr & ~0xFULL;
 337
 338         /* p->opcode contains the original unaltered bundle */
 339         memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
 340         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 341 }
 342
 343 void arch_remove_kprobe(struct kprobe *p)
 344 {
 345 }
 346
 347 /*
 348  * We are resuming execution after a single step fault, so the pt_regs
 349  * structure reflects the register state after we executed the instruction
 350  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 351  * the ip to point back to the original stack address. To set the IP address
 352  * to original stack address, handle the case where we need to fixup the
 353  * relative IP address and/or fixup branch register.
 354  */
 355 static void resume_execution(struct kprobe *p, struct pt_regs *regs)
 356 {
 357         unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
 358         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 359         unsigned long template;
 360         int slot = ((unsigned long)p->addr & 0xf);
 361
 362         template = p->opcode.bundle.quad0.template;
 363
 364         if (slot == 1 && bundle_encoding[template][1] == L)
 365                 slot = 2;
 366
 367         if (p->ainsn.inst_flag) {
 368
 369                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 370                         /* Fix relative IP address */
 371                         regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
 372                 }
 373
 374                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 375                 /*
 376                  * Fix target branch register, software convention is
 377                  * to use either b0 or b6 or b7, so just checking
 378                  * only those registers
 379                  */
 380                         switch (p->ainsn.target_br_reg) {
 381                         case 0:
 382                                 if ((regs->b0 == bundle_addr) ||
 383                                         (regs->b0 == bundle_addr + 0x10)) {
 384                                         regs->b0 = (regs->b0 - bundle_addr) +
 385                                                 resume_addr;
 386                                 }
 387                                 break;
 388                         case 6:
 389                                 if ((regs->b6 == bundle_addr) ||
 390                                         (regs->b6 == bundle_addr + 0x10)) {
 391                                         regs->b6 = (regs->b6 - bundle_addr) +
 392                                                 resume_addr;
 393                                 }
 394                                 break;
 395                         case 7:
 396                                 if ((regs->b7 == bundle_addr) ||
 397                                         (regs->b7 == bundle_addr + 0x10)) {
 398                                         regs->b7 = (regs->b7 - bundle_addr) +
 399                                                 resume_addr;
 400                                 }
 401                                 break;
 402                         } /* end switch */
 403                 }
 404                 goto turn_ss_off;
 405         }
 406
 407         if (slot == 2) {
 408                 if (regs->cr_iip == bundle_addr + 0x10) {
 409                         regs->cr_iip = resume_addr + 0x10;
 410                 }
 411         } else {
 412                 if (regs->cr_iip == bundle_addr) {
 413                         regs->cr_iip = resume_addr;
 414                 }
 415         }
 416
 417 turn_ss_off:
 418         /* Turn off Single Step bit */
 419         ia64_psr(regs)->ss = 0;
 420 }
 421
 422 static void prepare_ss(struct kprobe *p, struct pt_regs *regs)
 423 {
 424         unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
 425         unsigned long slot = (unsigned long)p->addr & 0xf;
 426
 427         /* Update instruction pointer (IIP) and slot number (IPSR.ri) */
 428         regs->cr_iip = bundle_addr & ~0xFULL;
 429
 430         if (slot > 2)
 431                 slot = 0;
 432
 433         ia64_psr(regs)->ri = slot;
 434
 435         /* turn on single stepping */
 436         ia64_psr(regs)->ss = 1;
 437 }
 438
 439 static int pre_kprobes_handler(struct die_args *args)
 440 {
 441         struct kprobe *p;
 442         int ret = 0;
 443         struct pt_regs *regs = args->regs;
 444         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 445
 446         preempt_disable();
 447
 448         /* Handle recursion cases */
 449         if (kprobe_running()) {
 450                 p = get_kprobe(addr);
 451                 if (p) {
 452                         if (kprobe_status == KPROBE_HIT_SS) {
 453                                 unlock_kprobes();
 454                                 goto no_kprobe;
 455                         }
 456                         /* We have reentered the pre_kprobe_handler(), since
 457                          * another probe was hit while within the handler.
 458                          * We here save the original kprobes variables and
 459                          * just single step on the instruction of the new probe
 460                          * without calling any user handlers.
 461                          */
 462                         save_previous_kprobe();
 463                         set_current_kprobe(p);
 464                         p->nmissed++;
 465                         prepare_ss(p, regs);
 466                         kprobe_status = KPROBE_REENTER;
 467                         return 1;
 468                 } else if (args->err == __IA64_BREAK_JPROBE) {
 469                         /*
 470                          * jprobe instrumented function just completed
 471                          */
 472                         p = current_kprobe;
 473                         if (p->break_handler && p->break_handler(p, regs)) {
 474                                 goto ss_probe;
 475                         }
 476                 } else {
 477                         /* Not our break */
 478                         goto no_kprobe;
 479                 }
 480         }
 481
 482         lock_kprobes();
 483         p = get_kprobe(addr);
 484         if (!p) {
 485                 unlock_kprobes();
 486                 goto no_kprobe;
 487         }
 488
 489         kprobe_status = KPROBE_HIT_ACTIVE;
 490         set_current_kprobe(p);
 491
 492         if (p->pre_handler && p->pre_handler(p, regs))
 493                 /*
 494                  * Our pre-handler is specifically requesting that we just
 495                  * do a return.  This is handling the case where the
 496                  * pre-handler is really our special jprobe pre-handler.
 497                  */
 498                 return 1;
 499
 500 ss_probe:
 501         prepare_ss(p, regs);
 502         kprobe_status = KPROBE_HIT_SS;
 503         return 1;
 504
 505 no_kprobe:
 506         preempt_enable_no_resched();
 507         return ret;
 508 }
 509
 510 static int post_kprobes_handler(struct pt_regs *regs)
 511 {
 512         if (!kprobe_running())
 513                 return 0;
 514
 515         if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
 516                 kprobe_status = KPROBE_HIT_SSDONE;
 517                 current_kprobe->post_handler(current_kprobe, regs, 0);
 518         }
 519
 520         resume_execution(current_kprobe, regs);
 521
 522         /*Restore back the original saved kprobes variables and continue. */
 523         if (kprobe_status == KPROBE_REENTER) {
 524                 restore_previous_kprobe();
 525                 goto out;
 526         }
 527
 528         unlock_kprobes();
 529
 530 out:
 531         preempt_enable_no_resched();
 532         return 1;
 533 }
 534
 535 static int kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 536 {
 537         if (!kprobe_running())
 538                 return 0;
 539
 540         if (current_kprobe->fault_handler &&
 541             current_kprobe->fault_handler(current_kprobe, regs, trapnr))
 542                 return 1;
 543
 544         if (kprobe_status & KPROBE_HIT_SS) {
 545                 resume_execution(current_kprobe, regs);
 546                 unlock_kprobes();
 547                 preempt_enable_no_resched();
 548         }
 549
 550         return 0;
 551 }
 552
 553 int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
 554                              void *data)
 555 {
 556         struct die_args *args = (struct die_args *)data;
 557         switch(val) {
 558         case DIE_BREAK:
 559                 if (pre_kprobes_handler(args))
 560                         return NOTIFY_STOP;
 561                 break;
 562         case DIE_SS:
 563                 if (post_kprobes_handler(args->regs))
 564                         return NOTIFY_STOP;
 565                 break;
 566         case DIE_PAGE_FAULT:
 567                 if (kprobes_fault_handler(args->regs, args->trapnr))
 568                         return NOTIFY_STOP;
 569         default:
 570                 break;
 571         }
 572         return NOTIFY_DONE;
 573 }
 574
 575 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 576 {
 577         struct jprobe *jp = container_of(p, struct jprobe, kp);
 578         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 579
 580         /* save architectural state */
 581         jprobe_saved_regs = *regs;
 582
 583         /* after rfi, execute the jprobe instrumented function */
 584         regs->cr_iip = addr & ~0xFULL;
 585         ia64_psr(regs)->ri = addr & 0xf;
 586         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 587
 588         /*
 589          * fix the return address to our jprobe_inst_return() function
 590          * in the jprobes.S file
 591          */
 592         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 593
 594         return 1;
 595 }
 596
 597 int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 598 {
 599         *regs = jprobe_saved_regs;
 600         return 1;
 601 }