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