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