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 void user_enable_single_step(struct task_struct *child)
  82 {
  83         unsigned long tmp;
  84
  85         /*
  86          * Set up SPC if not set already (in which case we have no other
  87          * choice but to trust it).
  88          */
  89         if (!get_reg(child, PT_SPC)) {
  90                 /* In case we're stopped in a delay slot. */
  91                 tmp = get_reg(child, PT_ERP) & ~1;
  92                 put_reg(child, PT_SPC, tmp);
  93         }
  94         tmp = get_reg(child, PT_CCS) | SBIT_USER;
  95         put_reg(child, PT_CCS, tmp);
  96 }
  97
  98 void user_disable_single_step(struct task_struct *child)
  99 {
 100         put_reg(child, PT_SPC, 0);
 101
 102         if (!get_debugreg(child->pid, PT_BP_CTRL)) {
 103                 unsigned long tmp;
 104                 /* If no h/w bp configured, disable S bit. */
 105                 tmp = get_reg(child, PT_CCS) & ~SBIT_USER;
 106                 put_reg(child, PT_CCS, tmp);
 107         }
 108 }
 109
 110 /*
 111  * Called by kernel/ptrace.c when detaching.
 112  *
 113  * Make sure the single step bit is not set.
 114  */
 115 void
 116 ptrace_disable(struct task_struct *child)
 117 {
 118         unsigned long tmp;
 119
 120         /* Deconfigure SPC and S-bit. */
 121         user_disable_single_step(child);
 122         put_reg(child, PT_SPC, 0);
 123
 124         /* Deconfigure any watchpoints associated with the child. */
 125         deconfigure_bp(child->pid);
 126 }
 127
 128
 129 long arch_ptrace(struct task_struct *child, long request,
 130                  unsigned long addr, unsigned long data)
 131 {
 132         int ret;
 133         unsigned long __user *datap = (unsigned long __user *)data;
 134
 135         switch (request) {
 136                 /* Read word at location address. */
 137                 case PTRACE_PEEKTEXT:
 138                 case PTRACE_PEEKDATA: {
 139                         unsigned long tmp;
 140                         int copied;
 141
 142                         ret = -EIO;
 143
 144                         /* The signal trampoline page is outside the normal user-addressable
 145                          * space but still accessible. This is hack to make it possible to
 146                          * access the signal handler code in GDB.
 147                          */
 148                         if ((addr & PAGE_MASK) == cris_signal_return_page) {
 149                                 /* The trampoline page is globally mapped, no page table to traverse.*/
 150                                 tmp = *(unsigned long*)addr;
 151                         } else {
 152                                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 153
 154                                 if (copied != sizeof(tmp))
 155                                         break;
 156                         }
 157
 158                         ret = put_user(tmp,datap);
 159                         break;
 160                 }
 161
 162                 /* Read the word at location address in the USER area. */
 163                 case PTRACE_PEEKUSR: {
 164                         unsigned long tmp;
 165
 166                         ret = -EIO;
 167                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 168                                 break;
 169
 170                         tmp = get_reg(child, addr >> 2);
 171                         ret = put_user(tmp, datap);
 172                         break;
 173                 }
 174
 175                 /* Write the word at location address. */
 176                 case PTRACE_POKETEXT:
 177                 case PTRACE_POKEDATA:
 178                         ret = generic_ptrace_pokedata(child, addr, data);
 179                         break;
 180
 181                 /* Write the word at location address in the USER area. */
 182                 case PTRACE_POKEUSR:
 183                         ret = -EIO;
 184                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 185                                 break;
 186
 187                         addr >>= 2;
 188
 189                         if (addr == PT_CCS) {
 190                                 /* don't allow the tracing process to change stuff like
 191                                  * interrupt enable, kernel/user bit, dma enables etc.
 192                                  */
 193                                 data &= CCS_MASK;
 194                                 data |= get_reg(child, PT_CCS) & ~CCS_MASK;
 195                         }
 196                         if (put_reg(child, addr, data))
 197                                 break;
 198                         ret = 0;
 199                         break;
 200
 201                 /* Get all GP registers from the child. */
 202                 case PTRACE_GETREGS: {
 203                         int i;
 204                         unsigned long tmp;
 205
 206                         for (i = 0; i <= PT_MAX; i++) {
 207                                 tmp = get_reg(child, i);
 208
 209                                 if (put_user(tmp, datap)) {
 210                                         ret = -EFAULT;
 211                                         goto out_tsk;
 212                                 }
 213
 214                                 datap++;
 215                         }
 216
 217                         ret = 0;
 218                         break;
 219                 }
 220
 221                 /* Set all GP registers in the child. */
 222                 case PTRACE_SETREGS: {
 223                         int i;
 224                         unsigned long tmp;
 225
 226                         for (i = 0; i <= PT_MAX; i++) {
 227                                 if (get_user(tmp, datap)) {
 228                                         ret = -EFAULT;
 229                                         goto out_tsk;
 230                                 }
 231
 232                                 if (i == PT_CCS) {
 233                                         tmp &= CCS_MASK;
 234                                         tmp |= get_reg(child, PT_CCS) & ~CCS_MASK;
 235                                 }
 236
 237                                 put_reg(child, i, tmp);
 238                                 datap++;
 239                         }
 240
 241                         ret = 0;
 242                         break;
 243                 }
 244
 245                 default:
 246                         ret = ptrace_request(child, request, addr, data);
 247                         break;
 248         }
 249
 250 out_tsk:
 251         return ret;
 252 }
 253
 254 void do_syscall_trace(void)
 255 {
 256         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 257                 return;
 258
 259         if (!(current->ptrace & PT_PTRACED))
 260                 return;
 261
 262         /* the 0x80 provides a way for the tracing parent to distinguish
 263            between a syscall stop and SIGTRAP delivery */
 264         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 265                                  ? 0x80 : 0));
 266
 267         /*
 268          * This isn't the same as continuing with a signal, but it will do for
 269          * normal use.
 270          */
 271         if (current->exit_code) {
 272                 send_sig(current->exit_code, current, 1);
 273                 current->exit_code = 0;
 274         }
 275 }
 276
 277 /* Returns the size of an instruction that has a delay slot. */
 278
 279 static int insn_size(struct task_struct *child, unsigned long pc)
 280 {
 281   unsigned long opcode;
 282   int copied;
 283   int opsize = 0;
 284
 285   /* Read the opcode at pc (do what PTRACE_PEEKTEXT would do). */
 286   copied = access_process_vm(child, pc, &opcode, sizeof(opcode), 0);
 287   if (copied != sizeof(opcode))
 288     return 0;
 289
 290   switch ((opcode & 0x0f00) >> 8) {
 291   case 0x0:
 292   case 0x9:
 293   case 0xb:
 294           opsize = 2;
 295           break;
 296   case 0xe:
 297   case 0xf:
 298           opsize = 6;
 299           break;
 300   case 0xd:
 301           /* Could be 4 or 6; check more bits. */
 302           if ((opcode & 0xff) == 0xff)
 303                   opsize = 4;
 304           else
 305                   opsize = 6;
 306           break;
 307   default:
 308           panic("ERROR: Couldn't find size of opcode 0x%lx at 0x%lx\n",
 309                 opcode, pc);
 310   }
 311
 312   return opsize;
 313 }
 314
 315 static unsigned long get_pseudo_pc(struct task_struct *child)
 316 {
 317         /* Default value for PC is ERP. */
 318         unsigned long pc = get_reg(child, PT_ERP);
 319
 320         if (pc & 0x1) {
 321                 unsigned long spc = get_reg(child, PT_SPC);
 322                 /* Delay slot bit set. Report as stopped on proper
 323                    instruction. */
 324                 if (spc) {
 325                         /* Rely on SPC if set. FIXME: We might want to check
 326                            that EXS indicates we stopped due to a single-step
 327                            exception. */
 328                         pc = spc;
 329                 } else {
 330                         /* Calculate the PC from the size of the instruction
 331                            that the delay slot we're in belongs to. */
 332                         pc += insn_size(child, pc & ~1) - 1;
 333                 }
 334         }
 335         return pc;
 336 }
 337
 338 static long bp_owner = 0;
 339
 340 /* Reachable from exit_thread in signal.c, so not static. */
 341 void deconfigure_bp(long pid)
 342 {
 343         int bp;
 344
 345         /* Only deconfigure if the pid is the owner. */
 346         if (bp_owner != pid)
 347                 return;
 348
 349         for (bp = 0; bp < 6; bp++) {
 350                 unsigned long tmp;
 351                 /* Deconfigure start and end address (also gets rid of ownership). */
 352                 put_debugreg(pid, PT_BP + 3 + (bp * 2), 0);
 353                 put_debugreg(pid, PT_BP + 4 + (bp * 2), 0);
 354
 355                 /* Deconfigure relevant bits in control register. */
 356                 tmp = get_debugreg(pid, PT_BP_CTRL) & ~(3 << (2 + (bp * 4)));
 357                 put_debugreg(pid, PT_BP_CTRL, tmp);
 358         }
 359         /* No owner now. */
 360         bp_owner = 0;
 361 }
 362
 363 static int put_debugreg(long pid, unsigned int regno, long data)
 364 {
 365         int ret = 0;
 366         register int old_srs;
 367
 368 #ifdef CONFIG_ETRAX_KGDB
 369         /* Ignore write, but pretend it was ok if value is 0
 370            (we don't want POKEUSR/SETREGS failing unnessecarily). */
 371         return (data == 0) ? ret : -1;
 372 #endif
 373
 374         /* Simple owner management. */
 375         if (!bp_owner)
 376                 bp_owner = pid;
 377         else if (bp_owner != pid) {
 378                 /* Ignore write, but pretend it was ok if value is 0
 379                    (we don't want POKEUSR/SETREGS failing unnessecarily). */
 380                 return (data == 0) ? ret : -1;
 381         }
 382
 383         /* Remember old SRS. */
 384         SPEC_REG_RD(SPEC_REG_SRS, old_srs);
 385         /* Switch to BP bank. */
 386         SUPP_BANK_SEL(BANK_BP);
 387
 388         switch (regno - PT_BP) {
 389         case 0:
 390                 SUPP_REG_WR(0, data); break;
 391         case 1:
 392         case 2:
 393                 if (data)
 394                         ret = -1;
 395                 break;
 396         case 3:
 397                 SUPP_REG_WR(3, data); break;
 398         case 4:
 399                 SUPP_REG_WR(4, data); break;
 400         case 5:
 401                 SUPP_REG_WR(5, data); break;
 402         case 6:
 403                 SUPP_REG_WR(6, data); break;
 404         case 7:
 405                 SUPP_REG_WR(7, data); break;
 406         case 8:
 407                 SUPP_REG_WR(8, data); break;
 408         case 9:
 409                 SUPP_REG_WR(9, data); break;
 410         case 10:
 411                 SUPP_REG_WR(10, data); break;
 412         case 11:
 413                 SUPP_REG_WR(11, data); break;
 414         case 12:
 415                 SUPP_REG_WR(12, data); break;
 416         case 13:
 417                 SUPP_REG_WR(13, data); break;
 418         case 14:
 419                 SUPP_REG_WR(14, data); break;
 420         default:
 421                 ret = -1;
 422                 break;
 423         }
 424
 425         /* Restore SRS. */
 426         SPEC_REG_WR(SPEC_REG_SRS, old_srs);
 427         /* Just for show. */
 428         NOP();
 429         NOP();
 430         NOP();
 431
 432         return ret;
 433 }
 434
 435 static long get_debugreg(long pid, unsigned int regno)
 436 {
 437         register int old_srs;
 438         register long data;
 439
 440         if (pid != bp_owner) {
 441                 return 0;
 442         }
 443
 444         /* Remember old SRS. */
 445         SPEC_REG_RD(SPEC_REG_SRS, old_srs);
 446         /* Switch to BP bank. */
 447         SUPP_BANK_SEL(BANK_BP);
 448
 449         switch (regno - PT_BP) {
 450         case 0:
 451                 SUPP_REG_RD(0, data); break;
 452         case 1:
 453         case 2:
 454                 /* error return value? */
 455                 data = 0;
 456                 break;
 457         case 3:
 458                 SUPP_REG_RD(3, data); break;
 459         case 4:
 460                 SUPP_REG_RD(4, data); break;
 461         case 5:
 462                 SUPP_REG_RD(5, data); break;
 463         case 6:
 464                 SUPP_REG_RD(6, data); break;
 465         case 7:
 466                 SUPP_REG_RD(7, data); break;
 467         case 8:
 468                 SUPP_REG_RD(8, data); break;
 469         case 9:
 470                 SUPP_REG_RD(9, data); break;
 471         case 10:
 472                 SUPP_REG_RD(10, data); break;
 473         case 11:
 474                 SUPP_REG_RD(11, data); break;
 475         case 12:
 476                 SUPP_REG_RD(12, data); break;
 477         case 13:
 478                 SUPP_REG_RD(13, data); break;
 479         case 14:
 480                 SUPP_REG_RD(14, data); break;
 481         default:
 482                 /* error return value? */
 483                 data = 0;
 484         }
 485
 486         /* Restore SRS. */
 487         SPEC_REG_WR(SPEC_REG_SRS, old_srs);
 488         /* Just for show. */
 489         NOP();
 490         NOP();
 491         NOP();
 492
 493         return data;
 494 }