arch/cris/arch-v32/kernel/ptrace.c

   1 /*
   2  * Copyright (C) 2000-2007, Axis Communications AB.
   3  */
   4
   5 #include <linux/kernel.h>
   6 #include <linux/sched.h>
   7 #include <linux/mm.h>
   8 #include <linux/smp.h>
   9 #include <linux/errno.h>
  10 #include <linux/ptrace.h>
  11 #include <linux/user.h>
  12 #include <linux/signal.h>
  13 #include <linux/security.h>
  14
  15 #include <asm/uaccess.h>
  16 #include <asm/page.h>
  17 #include <asm/pgtable.h>
  18 #include <asm/system.h>
  19 #include <asm/processor.h>
  20 #include <arch/hwregs/supp_reg.h>
  21
  22 /*
  23  * Determines which bits in CCS the user has access to.
  24  * 1 = access, 0 = no access.
  25  */
  26 #define CCS_MASK 0x00087c00     /* SXNZVC */
  27
  28 #define SBIT_USER (1 << (S_CCS_BITNR + CCS_SHIFT))
  29
  30 static int put_debugreg(long pid, unsigned int regno, long data);
  31 static long get_debugreg(long pid, unsigned int regno);
  32 static unsigned long get_pseudo_pc(struct task_struct *child);
  33 void deconfigure_bp(long pid);
  34
  35 extern unsigned long cris_signal_return_page;
  36
  37 /*
  38  * Get contents of register REGNO in task TASK.
  39  */
  40 long get_reg(struct task_struct *task, unsigned int regno)
  41 {
  42         /* USP is a special case, it's not in the pt_regs struct but
  43          * in the tasks thread struct
  44          */
  45         unsigned long ret;
  46
  47         if (regno <= PT_EDA)
  48                 ret = ((unsigned long *)task_pt_regs(task))[regno];
  49         else if (regno == PT_USP)
  50                 ret = task->thread.usp;
  51         else if (regno == PT_PPC)
  52                 ret = get_pseudo_pc(task);
  53         else if (regno <= PT_MAX)
  54                 ret = get_debugreg(task->pid, regno);
  55         else
  56                 ret = 0;
  57
  58         return ret;
  59 }
  60
  61 /*
  62  * Write contents of register REGNO in task TASK.
  63  */
  64 int put_reg(struct task_struct *task, unsigned int regno, unsigned long data)
  65 {
  66         if (regno <= PT_EDA)
  67                 ((unsigned long *)task_pt_regs(task))[regno] = data;
  68         else if (regno == PT_USP)
  69                 task->thread.usp = data;
  70         else if (regno == PT_PPC) {
  71                 /* Write pseudo-PC to ERP only if changed. */
  72                 if (data != get_pseudo_pc(task))
  73                         task_pt_regs(task)->erp = data;
  74         } else if (regno <= PT_MAX)
  75                 return put_debugreg(task->pid, regno, data);
  76         else
  77                 return -1;
  78         return 0;
  79 }
  80
  81 /*
  82  * Called by kernel/ptrace.c when detaching.
  83  *
  84  * Make sure the single step bit is not set.
  85  */
  86 void
  87 ptrace_disable(struct task_struct *child)
  88 {
  89         unsigned long tmp;
  90
  91         /* Deconfigure SPC and S-bit. */
  92         tmp = get_reg(child, PT_CCS) & ~SBIT_USER;
  93         put_reg(child, PT_CCS, tmp);
  94         put_reg(child, PT_SPC, 0);
  95
  96         /* Deconfigure any watchpoints associated with the child. */
  97         deconfigure_bp(child->pid);
  98 }
  99
 100
 101 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 102 {
 103         int ret;
 104         unsigned long __user *datap = (unsigned long __user *)data;
 105
 106         switch (request) {
 107                 /* Read word at location address. */
 108                 case PTRACE_PEEKTEXT:
 109                 case PTRACE_PEEKDATA: {
 110                         unsigned long tmp;
 111                         int copied;
 112
 113                         ret = -EIO;
 114
 115                         /* The signal trampoline page is outside the normal user-addressable
 116                          * space but still accessible. This is hack to make it possible to
 117                          * access the signal handler code in GDB.
 118                          */
 119                         if ((addr & PAGE_MASK) == cris_signal_return_page) {
 120                                 /* The trampoline page is globally mapped, no page table to traverse.*/
 121                                 tmp = *(unsigned long*)addr;
 122                         } else {
 123                                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 124
 125                                 if (copied != sizeof(tmp))
 126                                         break;
 127                         }
 128
 129                         ret = put_user(tmp,datap);
 130                         break;
 131                 }
 132
 133                 /* Read the word at location address in the USER area. */
 134                 case PTRACE_PEEKUSR: {
 135                         unsigned long tmp;
 136
 137                         ret = -EIO;
 138                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 139                                 break;
 140
 141                         tmp = get_reg(child, addr >> 2);
 142                         ret = put_user(tmp, datap);
 143                         break;
 144                 }
 145
 146                 /* Write the word at location address. */
 147                 case PTRACE_POKETEXT:
 148                 case PTRACE_POKEDATA:
 149                         ret = generic_ptrace_pokedata(child, addr, data);
 150                         break;
 151
 152                 /* Write the word at location address in the USER area. */
 153                 case PTRACE_POKEUSR:
 154                         ret = -EIO;
 155                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 156                                 break;
 157
 158                         addr >>= 2;
 159
 160                         if (addr == PT_CCS) {
 161                                 /* don't allow the tracing process to change stuff like
 162                                  * interrupt enable, kernel/user bit, dma enables etc.
 163                                  */
 164                                 data &= CCS_MASK;
 165                                 data |= get_reg(child, PT_CCS) & ~CCS_MASK;
 166                         }
 167                         if (put_reg(child, addr, data))
 168                                 break;
 169                         ret = 0;
 170                         break;
 171
 172                 case PTRACE_SYSCALL:
 173                 case PTRACE_CONT:
 174                         ret = -EIO;
 175
 176                         if (!valid_signal(data))
 177                                 break;
 178
 179                         /* Continue means no single-step. */
 180                         put_reg(child, PT_SPC, 0);
 181
 182                         if (!get_debugreg(child->pid, PT_BP_CTRL)) {
 183                                 unsigned long tmp;
 184                                 /* If no h/w bp configured, disable S bit. */
 185                                 tmp = get_reg(child, PT_CCS) & ~SBIT_USER;
 186                                 put_reg(child, PT_CCS, tmp);
 187                         }
 188
 189                         if (request == PTRACE_SYSCALL) {
 190                                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 191                         }
 192                         else {
 193                                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 194                         }
 195
 196                         child->exit_code = data;
 197
 198                         /* TODO: make sure any pending breakpoint is killed */
 199                         wake_up_process(child);
 200                         ret = 0;
 201
 202                         break;
 203
 204                 /* Make the child exit by sending it a sigkill. */
 205                 case PTRACE_KILL:
 206                         ret = 0;
 207
 208                         if (child->exit_state == EXIT_ZOMBIE)
 209                                 break;
 210
 211                         child->exit_code = SIGKILL;
 212
 213                         /* Deconfigure single-step and h/w bp. */
 214                         ptrace_disable(child);
 215
 216                         /* TODO: make sure any pending breakpoint is killed */
 217                         wake_up_process(child);
 218                         break;
 219
 220                 /* Set the trap flag. */
 221                 case PTRACE_SINGLESTEP: {
 222                         unsigned long tmp;
 223                         ret = -EIO;
 224
 225                         /* Set up SPC if not set already (in which case we have
 226                            no other choice but to trust it). */
 227                         if (!get_reg(child, PT_SPC)) {
 228                                 /* In case we're stopped in a delay slot. */
 229                                 tmp = get_reg(child, PT_ERP) & ~1;
 230                                 put_reg(child, PT_SPC, tmp);
 231                         }
 232                         tmp = get_reg(child, PT_CCS) | SBIT_USER;
 233                         put_reg(child, PT_CCS, tmp);
 234
 235                         if (!valid_signal(data))
 236                                 break;
 237
 238                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 239
 240                         /* TODO: set some clever breakpoint mechanism... */
 241
 242                         child->exit_code = data;
 243                         wake_up_process(child);
 244                         ret = 0;
 245                         break;
 246
 247                 }
 248
 249                 /* Get all GP registers from the child. */
 250                 case PTRACE_GETREGS: {
 251                         int i;
 252                         unsigned long tmp;
 253
 254                         for (i = 0; i <= PT_MAX; i++) {
 255                                 tmp = get_reg(child, i);
 256
 257                                 if (put_user(tmp, datap)) {
 258                                         ret = -EFAULT;
 259                                         goto out_tsk;
 260                                 }
 261
 262                                 datap++;
 263                         }
 264
 265                         ret = 0;
 266                         break;
 267                 }
 268
 269                 /* Set all GP registers in the child. */
 270                 case PTRACE_SETREGS: {
 271                         int i;
 272                         unsigned long tmp;
 273
 274                         for (i = 0; i <= PT_MAX; i++) {
 275                                 if (get_user(tmp, datap)) {
 276                                         ret = -EFAULT;
 277                                         goto out_tsk;
 278                                 }
 279
 280                                 if (i == PT_CCS) {
 281                                         tmp &= CCS_MASK;
 282                                         tmp |= get_reg(child, PT_CCS) & ~CCS_MASK;
 283                                 }
 284
 285                                 put_reg(child, i, tmp);
 286                                 datap++;
 287                         }
 288
 289                         ret = 0;
 290                         break;
 291                 }
 292
 293                 default:
 294                         ret = ptrace_request(child, request, addr, data);
 295                         break;
 296         }
 297
 298 out_tsk:
 299         return ret;
 300 }
 301
 302 void do_syscall_trace(void)
 303 {
 304         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 305                 return;
 306
 307         if (!(current->ptrace & PT_PTRACED))
 308                 return;
 309
 310         /* the 0x80 provides a way for the tracing parent to distinguish
 311            between a syscall stop and SIGTRAP delivery */
 312         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 313                                  ? 0x80 : 0));
 314
 315         /*
 316          * This isn't the same as continuing with a signal, but it will do for
 317          * normal use.
 318          */
 319         if (current->exit_code) {
 320                 send_sig(current->exit_code, current, 1);
 321                 current->exit_code = 0;
 322         }
 323 }
 324
 325 /* Returns the size of an instruction that has a delay slot. */
 326
 327 static int insn_size(struct task_struct *child, unsigned long pc)
 328 {
 329   unsigned long opcode;
 330   int copied;
 331   int opsize = 0;
 332
 333   /* Read the opcode at pc (do what PTRACE_PEEKTEXT would do). */
 334   copied = access_process_vm(child, pc, &opcode, sizeof(opcode), 0);
 335   if (copied != sizeof(opcode))
 336     return 0;
 337
 338   switch ((opcode & 0x0f00) >> 8) {
 339   case 0x0:
 340   case 0x9:
 341   case 0xb:
 342           opsize = 2;
 343           break;
 344   case 0xe:
 345   case 0xf:
 346           opsize = 6;
 347           break;
 348   case 0xd:
 349           /* Could be 4 or 6; check more bits. */
 350           if ((opcode & 0xff) == 0xff)
 351                   opsize = 4;
 352           else
 353                   opsize = 6;
 354           break;
 355   default:
 356           panic("ERROR: Couldn't find size of opcode 0x%lx at 0x%lx\n",
 357                 opcode, pc);
 358   }
 359
 360   return opsize;
 361 }
 362
 363 static unsigned long get_pseudo_pc(struct task_struct *child)
 364 {
 365         /* Default value for PC is ERP. */
 366         unsigned long pc = get_reg(child, PT_ERP);
 367
 368         if (pc & 0x1) {
 369                 unsigned long spc = get_reg(child, PT_SPC);
 370                 /* Delay slot bit set. Report as stopped on proper
 371                    instruction. */
 372                 if (spc) {
 373                         /* Rely on SPC if set. FIXME: We might want to check
 374                            that EXS indicates we stopped due to a single-step
 375                            exception. */
 376                         pc = spc;
 377                 } else {
 378                         /* Calculate the PC from the size of the instruction
 379                            that the delay slot we're in belongs to. */
 380                         pc += insn_size(child, pc & ~1) - 1;
 381                 }
 382         }
 383         return pc;
 384 }
 385
 386 static long bp_owner = 0;
 387
 388 /* Reachable from exit_thread in signal.c, so not static. */
 389 void deconfigure_bp(long pid)
 390 {
 391         int bp;
 392
 393         /* Only deconfigure if the pid is the owner. */
 394         if (bp_owner != pid)
 395                 return;
 396
 397         for (bp = 0; bp < 6; bp++) {
 398                 unsigned long tmp;
 399                 /* Deconfigure start and end address (also gets rid of ownership). */
 400                 put_debugreg(pid, PT_BP + 3 + (bp * 2), 0);
 401                 put_debugreg(pid, PT_BP + 4 + (bp * 2), 0);
 402
 403                 /* Deconfigure relevant bits in control register. */
 404                 tmp = get_debugreg(pid, PT_BP_CTRL) & ~(3 << (2 + (bp * 4)));
 405                 put_debugreg(pid, PT_BP_CTRL, tmp);
 406         }
 407         /* No owner now. */
 408         bp_owner = 0;
 409 }
 410
 411 static int put_debugreg(long pid, unsigned int regno, long data)
 412 {
 413         int ret = 0;
 414         register int old_srs;
 415
 416 #ifdef CONFIG_ETRAX_KGDB
 417         /* Ignore write, but pretend it was ok if value is 0
 418            (we don't want POKEUSR/SETREGS failing unnessecarily). */
 419         return (data == 0) ? ret : -1;
 420 #endif
 421
 422         /* Simple owner management. */
 423         if (!bp_owner)
 424                 bp_owner = pid;
 425         else if (bp_owner != pid) {
 426                 /* Ignore write, but pretend it was ok if value is 0
 427                    (we don't want POKEUSR/SETREGS failing unnessecarily). */
 428                 return (data == 0) ? ret : -1;
 429         }
 430
 431         /* Remember old SRS. */
 432         SPEC_REG_RD(SPEC_REG_SRS, old_srs);
 433         /* Switch to BP bank. */
 434         SUPP_BANK_SEL(BANK_BP);
 435
 436         switch (regno - PT_BP) {
 437         case 0:
 438                 SUPP_REG_WR(0, data); break;
 439         case 1:
 440         case 2:
 441                 if (data)
 442                         ret = -1;
 443                 break;
 444         case 3:
 445                 SUPP_REG_WR(3, data); break;
 446         case 4:
 447                 SUPP_REG_WR(4, data); break;
 448         case 5:
 449                 SUPP_REG_WR(5, data); break;
 450         case 6:
 451                 SUPP_REG_WR(6, data); break;
 452         case 7:
 453                 SUPP_REG_WR(7, data); break;
 454         case 8:
 455                 SUPP_REG_WR(8, data); break;
 456         case 9:
 457                 SUPP_REG_WR(9, data); break;
 458         case 10:
 459                 SUPP_REG_WR(10, data); break;
 460         case 11:
 461                 SUPP_REG_WR(11, data); break;
 462         case 12:
 463                 SUPP_REG_WR(12, data); break;
 464         case 13:
 465                 SUPP_REG_WR(13, data); break;
 466         case 14:
 467                 SUPP_REG_WR(14, data); break;
 468         default:
 469                 ret = -1;
 470                 break;
 471         }
 472
 473         /* Restore SRS. */
 474         SPEC_REG_WR(SPEC_REG_SRS, old_srs);
 475         /* Just for show. */
 476         NOP();
 477         NOP();
 478         NOP();
 479
 480         return ret;
 481 }
 482
 483 static long get_debugreg(long pid, unsigned int regno)
 484 {
 485         register int old_srs;
 486         register long data;
 487
 488         if (pid != bp_owner) {
 489                 return 0;
 490         }
 491
 492         /* Remember old SRS. */
 493         SPEC_REG_RD(SPEC_REG_SRS, old_srs);
 494         /* Switch to BP bank. */
 495         SUPP_BANK_SEL(BANK_BP);
 496
 497         switch (regno - PT_BP) {
 498         case 0:
 499                 SUPP_REG_RD(0, data); break;
 500         case 1:
 501         case 2:
 502                 /* error return value? */
 503                 data = 0;
 504                 break;
 505         case 3:
 506                 SUPP_REG_RD(3, data); break;
 507         case 4:
 508                 SUPP_REG_RD(4, data); break;
 509         case 5:
 510                 SUPP_REG_RD(5, data); break;
 511         case 6:
 512                 SUPP_REG_RD(6, data); break;
 513         case 7:
 514                 SUPP_REG_RD(7, data); break;
 515         case 8:
 516                 SUPP_REG_RD(8, data); break;
 517         case 9:
 518                 SUPP_REG_RD(9, data); break;
 519         case 10:
 520                 SUPP_REG_RD(10, data); break;
 521         case 11:
 522                 SUPP_REG_RD(11, data); break;
 523         case 12:
 524                 SUPP_REG_RD(12, data); break;
 525         case 13:
 526                 SUPP_REG_RD(13, data); break;
 527         case 14:
 528                 SUPP_REG_RD(14, data); break;
 529         default:
 530                 /* error return value? */
 531                 data = 0;
 532         }
 533
 534         /* Restore SRS. */
 535         SPEC_REG_WR(SPEC_REG_SRS, old_srs);
 536         /* Just for show. */
 537         NOP();
 538         NOP();
 539         NOP();
 540
 541         return data;
 542 }