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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;
  45 static unsigned long kprobe_status;
  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 override the bundle with
 124  * the break instruction at the given slot.
 125  */
 126 static void prepare_break_inst(uint template, uint  slot, uint major_opcode,
 127         unsigned long kprobe_inst, struct kprobe *p)
 128 {
 129         unsigned long break_inst = BREAK_INST;
 130         bundle_t *bundle = &p->ainsn.insn.bundle;
 131
 132         /*
 133          * Copy the original kprobe_inst qualifying predicate(qp)
 134          * to the break instruction
 135          */
 136         break_inst |= (0x3f & kprobe_inst);
 137
 138         switch (slot) {
 139           case 0:
 140                 bundle->quad0.slot0 = break_inst;
 141                 break;
 142           case 1:
 143                 bundle->quad0.slot1_p0 = break_inst;
 144                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 145                 break;
 146           case 2:
 147                 bundle->quad1.slot2 = break_inst;
 148                 break;
 149         }
 150
 151         /*
 152          * Update the instruction flag, so that we can
 153          * emulate the instruction properly after we
 154          * single step on original instruction
 155          */
 156         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 157 }
 158
 159 static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
 160                 unsigned long *kprobe_inst, uint *major_opcode)
 161 {
 162         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 163         unsigned int template;
 164
 165         template = bundle->quad0.template;
 166
 167         switch (slot) {
 168           case 0:
 169                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 170                 *kprobe_inst = bundle->quad0.slot0;
 171                 break;
 172           case 1:
 173                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 174                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 175                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 176                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 177                 break;
 178           case 2:
 179                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 180                 *kprobe_inst = bundle->quad1.slot2;
 181                 break;
 182         }
 183 }
 184
 185 static int valid_kprobe_addr(int template, int slot, unsigned long addr)
 186 {
 187         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 188                 printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n",
 189                                 addr);
 190                 return -EINVAL;
 191         }
 192         return 0;
 193 }
 194
 195 int arch_prepare_kprobe(struct kprobe *p)
 196 {
 197         unsigned long addr = (unsigned long) p->addr;
 198         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 199         unsigned long kprobe_inst=0;
 200         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 201         bundle_t *bundle = &p->ainsn.insn.bundle;
 202
 203         memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
 204         memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));
 205
 206         template = bundle->quad0.template;
 207
 208         if(valid_kprobe_addr(template, slot, addr))
 209                 return -EINVAL;
 210
 211         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 212         if (slot == 1 && bundle_encoding[template][1] == L)
 213                 slot++;
 214
 215         /* Get kprobe_inst and major_opcode from the bundle */
 216         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 217
 218         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
 219
 220         return 0;
 221 }
 222
 223 void arch_arm_kprobe(struct kprobe *p)
 224 {
 225         unsigned long addr = (unsigned long)p->addr;
 226         unsigned long arm_addr = addr & ~0xFULL;
 227
 228         memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
 229         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 230 }
 231
 232 void arch_disarm_kprobe(struct kprobe *p)
 233 {
 234         unsigned long addr = (unsigned long)p->addr;
 235         unsigned long arm_addr = addr & ~0xFULL;
 236
 237         /* p->opcode contains the original unaltered bundle */
 238         memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
 239         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 240 }
 241
 242 void arch_remove_kprobe(struct kprobe *p)
 243 {
 244 }
 245
 246 /*
 247  * We are resuming execution after a single step fault, so the pt_regs
 248  * structure reflects the register state after we executed the instruction
 249  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 250  * the ip to point back to the original stack address. To set the IP address
 251  * to original stack address, handle the case where we need to fixup the
 252  * relative IP address and/or fixup branch register.
 253  */
 254 static void resume_execution(struct kprobe *p, struct pt_regs *regs)
 255 {
 256         unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
 257         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 258         unsigned long template;
 259         int slot = ((unsigned long)p->addr & 0xf);
 260
 261         template = p->opcode.bundle.quad0.template;
 262
 263         if (slot == 1 && bundle_encoding[template][1] == L)
 264                 slot = 2;
 265
 266         if (p->ainsn.inst_flag) {
 267
 268                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 269                         /* Fix relative IP address */
 270                         regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
 271                 }
 272
 273                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 274                 /*
 275                  * Fix target branch register, software convention is
 276                  * to use either b0 or b6 or b7, so just checking
 277                  * only those registers
 278                  */
 279                         switch (p->ainsn.target_br_reg) {
 280                         case 0:
 281                                 if ((regs->b0 == bundle_addr) ||
 282                                         (regs->b0 == bundle_addr + 0x10)) {
 283                                         regs->b0 = (regs->b0 - bundle_addr) +
 284                                                 resume_addr;
 285                                 }
 286                                 break;
 287                         case 6:
 288                                 if ((regs->b6 == bundle_addr) ||
 289                                         (regs->b6 == bundle_addr + 0x10)) {
 290                                         regs->b6 = (regs->b6 - bundle_addr) +
 291                                                 resume_addr;
 292                                 }
 293                                 break;
 294                         case 7:
 295                                 if ((regs->b7 == bundle_addr) ||
 296                                         (regs->b7 == bundle_addr + 0x10)) {
 297                                         regs->b7 = (regs->b7 - bundle_addr) +
 298                                                 resume_addr;
 299                                 }
 300                                 break;
 301                         } /* end switch */
 302                 }
 303                 goto turn_ss_off;
 304         }
 305
 306         if (slot == 2) {
 307                 if (regs->cr_iip == bundle_addr + 0x10) {
 308                         regs->cr_iip = resume_addr + 0x10;
 309                 }
 310         } else {
 311                 if (regs->cr_iip == bundle_addr) {
 312                         regs->cr_iip = resume_addr;
 313                 }
 314         }
 315
 316 turn_ss_off:
 317         /* Turn off Single Step bit */
 318         ia64_psr(regs)->ss = 0;
 319 }
 320
 321 static void prepare_ss(struct kprobe *p, struct pt_regs *regs)
 322 {
 323         unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
 324         unsigned long slot = (unsigned long)p->addr & 0xf;
 325
 326         /* Update instruction pointer (IIP) and slot number (IPSR.ri) */
 327         regs->cr_iip = bundle_addr & ~0xFULL;
 328
 329         if (slot > 2)
 330                 slot = 0;
 331
 332         ia64_psr(regs)->ri = slot;
 333
 334         /* turn on single stepping */
 335         ia64_psr(regs)->ss = 1;
 336 }
 337
 338 static int pre_kprobes_handler(struct pt_regs *regs)
 339 {
 340         struct kprobe *p;
 341         int ret = 0;
 342         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 343
 344         preempt_disable();
 345
 346         /* Handle recursion cases */
 347         if (kprobe_running()) {
 348                 p = get_kprobe(addr);
 349                 if (p) {
 350                         if (kprobe_status == KPROBE_HIT_SS) {
 351                                 unlock_kprobes();
 352                                 goto no_kprobe;
 353                         }
 354                         arch_disarm_kprobe(p);
 355                         ret = 1;
 356                 } else {
 357                         /*
 358                          * jprobe instrumented function just completed
 359                          */
 360                         p = current_kprobe;
 361                         if (p->break_handler && p->break_handler(p, regs)) {
 362                                 goto ss_probe;
 363                         }
 364                 }
 365         }
 366
 367         lock_kprobes();
 368         p = get_kprobe(addr);
 369         if (!p) {
 370                 unlock_kprobes();
 371                 goto no_kprobe;
 372         }
 373
 374         kprobe_status = KPROBE_HIT_ACTIVE;
 375         current_kprobe = p;
 376
 377         if (p->pre_handler && p->pre_handler(p, regs))
 378                 /*
 379                  * Our pre-handler is specifically requesting that we just
 380                  * do a return.  This is handling the case where the
 381                  * pre-handler is really our special jprobe pre-handler.
 382                  */
 383                 return 1;
 384
 385 ss_probe:
 386         prepare_ss(p, regs);
 387         kprobe_status = KPROBE_HIT_SS;
 388         return 1;
 389
 390 no_kprobe:
 391         preempt_enable_no_resched();
 392         return ret;
 393 }
 394
 395 static int post_kprobes_handler(struct pt_regs *regs)
 396 {
 397         if (!kprobe_running())
 398                 return 0;
 399
 400         if (current_kprobe->post_handler)
 401                 current_kprobe->post_handler(current_kprobe, regs, 0);
 402
 403         resume_execution(current_kprobe, regs);
 404
 405         unlock_kprobes();
 406         preempt_enable_no_resched();
 407         return 1;
 408 }
 409
 410 static int kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 411 {
 412         if (!kprobe_running())
 413                 return 0;
 414
 415         if (current_kprobe->fault_handler &&
 416             current_kprobe->fault_handler(current_kprobe, regs, trapnr))
 417                 return 1;
 418
 419         if (kprobe_status & KPROBE_HIT_SS) {
 420                 resume_execution(current_kprobe, regs);
 421                 unlock_kprobes();
 422                 preempt_enable_no_resched();
 423         }
 424
 425         return 0;
 426 }
 427
 428 int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
 429                              void *data)
 430 {
 431         struct die_args *args = (struct die_args *)data;
 432         switch(val) {
 433         case DIE_BREAK:
 434                 if (pre_kprobes_handler(args->regs))
 435                         return NOTIFY_STOP;
 436                 break;
 437         case DIE_SS:
 438                 if (post_kprobes_handler(args->regs))
 439                         return NOTIFY_STOP;
 440                 break;
 441         case DIE_PAGE_FAULT:
 442                 if (kprobes_fault_handler(args->regs, args->trapnr))
 443                         return NOTIFY_STOP;
 444         default:
 445                 break;
 446         }
 447         return NOTIFY_DONE;
 448 }
 449
 450 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 451 {
 452         struct jprobe *jp = container_of(p, struct jprobe, kp);
 453         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 454
 455         /* save architectural state */
 456         jprobe_saved_regs = *regs;
 457
 458         /* after rfi, execute the jprobe instrumented function */
 459         regs->cr_iip = addr & ~0xFULL;
 460         ia64_psr(regs)->ri = addr & 0xf;
 461         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 462
 463         /*
 464          * fix the return address to our jprobe_inst_return() function
 465          * in the jprobes.S file
 466          */
 467         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 468
 469         return 1;
 470 }
 471
 472 int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 473 {
 474         *regs = jprobe_saved_regs;
 475         return 1;
 476 }