arch/parisc/kernel/ptrace.c

   1 /*
   2  * Kernel support for the ptrace() and syscall tracing interfaces.
   3  *
   4  * Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc.
   5  * Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx>
   6  * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/smp.h>
  13 #include <linux/smp_lock.h>
  14 #include <linux/errno.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/user.h>
  17 #include <linux/personality.h>
  18 #include <linux/security.h>
  19 #include <linux/compat.h>
  20
  21 #include <asm/uaccess.h>
  22 #include <asm/pgtable.h>
  23 #include <asm/system.h>
  24 #include <asm/processor.h>
  25 #include <asm/offsets.h>
  26
  27 /* PSW bits we allow the debugger to modify */
  28 #define USER_PSW_BITS   (PSW_N | PSW_V | PSW_CB)
  29
  30 #undef DEBUG_PTRACE
  31
  32 #ifdef DEBUG_PTRACE
  33 #define DBG(x...)       printk(x)
  34 #else
  35 #define DBG(x...)
  36 #endif
  37
  38 #ifdef __LP64__
  39
  40 /* This function is needed to translate 32 bit pt_regs offsets in to
  41  * 64 bit pt_regs offsets.  For example, a 32 bit gdb under a 64 bit kernel
  42  * will request offset 12 if it wants gr3, but the lower 32 bits of
  43  * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
  44  * This code relies on a 32 bit pt_regs being comprised of 32 bit values
  45  * except for the fp registers which (a) are 64 bits, and (b) follow
  46  * the gr registers at the start of pt_regs.  The 32 bit pt_regs should
  47  * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
  48  * being 64 bit in both cases.
  49  */
  50
  51 static long translate_usr_offset(long offset)
  52 {
  53         if (offset < 0)
  54                 return -1;
  55         else if (offset <= 32*4)        /* gr[0..31] */
  56                 return offset * 2 + 4;
  57         else if (offset <= 32*4+32*8)   /* gr[0..31] + fr[0..31] */
  58                 return offset + 32*4;
  59         else if (offset < sizeof(struct pt_regs)/2 + 32*4)
  60                 return offset * 2 + 4 - 32*8;
  61         else
  62                 return -1;
  63 }
  64 #endif
  65
  66 /*
  67  * Called by kernel/ptrace.c when detaching..
  68  *
  69  * Make sure single step bits etc are not set.
  70  */
  71 void ptrace_disable(struct task_struct *child)
  72 {
  73         /* make sure the trap bits are not set */
  74         pa_psw(child)->r = 0;
  75         pa_psw(child)->t = 0;
  76         pa_psw(child)->h = 0;
  77         pa_psw(child)->l = 0;
  78 }
  79
  80 long sys_ptrace(long request, pid_t pid, long addr, long data)
  81 {
  82         struct task_struct *child;
  83         long ret;
  84 #ifdef DEBUG_PTRACE
  85         long oaddr=addr, odata=data;
  86 #endif
  87
  88         lock_kernel();
  89         ret = -EPERM;
  90         if (request == PTRACE_TRACEME) {
  91                 /* are we already being traced? */
  92                 if (current->ptrace & PT_PTRACED)
  93                         goto out;
  94
  95                 ret = security_ptrace(current->parent, current);
  96                 if (ret)
  97                         goto out;
  98
  99                 /* set the ptrace bit in the process flags. */
 100                 current->ptrace |= PT_PTRACED;
 101                 ret = 0;
 102                 goto out;
 103         }
 104
 105         ret = -ESRCH;
 106         read_lock(&tasklist_lock);
 107         child = find_task_by_pid(pid);
 108         if (child)
 109                 get_task_struct(child);
 110         read_unlock(&tasklist_lock);
 111         if (!child)
 112                 goto out;
 113         ret = -EPERM;
 114         if (pid == 1)           /* no messing around with init! */
 115                 goto out_tsk;
 116
 117         if (request == PTRACE_ATTACH) {
 118                 ret = ptrace_attach(child);
 119                 goto out_tsk;
 120         }
 121
 122         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 123         if (ret < 0)
 124                 goto out_tsk;
 125
 126         switch (request) {
 127         case PTRACE_PEEKTEXT: /* read word at location addr. */
 128         case PTRACE_PEEKDATA: {
 129                 int copied;
 130
 131 #ifdef __LP64__
 132                 if (is_compat_task(child)) {
 133                         unsigned int tmp;
 134
 135                         addr &= 0xffffffffL;
 136                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 137                         ret = -EIO;
 138                         if (copied != sizeof(tmp))
 139                                 goto out_tsk;
 140                         ret = put_user(tmp,(unsigned int *) data);
 141                         DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n",
 142                                 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA",
 143                                 pid, oaddr, odata, ret, tmp);
 144                 }
 145                 else
 146 #endif
 147                 {
 148                         unsigned long tmp;
 149
 150                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 151                         ret = -EIO;
 152                         if (copied != sizeof(tmp))
 153                                 goto out_tsk;
 154                         ret = put_user(tmp,(unsigned long *) data);
 155                 }
 156                 goto out_tsk;
 157         }
 158
 159         /* when I and D space are separate, this will have to be fixed. */
 160         case PTRACE_POKETEXT: /* write the word at location addr. */
 161         case PTRACE_POKEDATA:
 162                 ret = 0;
 163 #ifdef __LP64__
 164                 if (is_compat_task(child)) {
 165                         unsigned int tmp = (unsigned int)data;
 166                         DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n",
 167                                 request == PTRACE_POKETEXT ? "TEXT" : "DATA",
 168                                 pid, oaddr, odata);
 169                         addr &= 0xffffffffL;
 170                         if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp))
 171                                 goto out_tsk;
 172                 }
 173                 else
 174 #endif
 175                 {
 176                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 177                                 goto out_tsk;
 178                 }
 179                 ret = -EIO;
 180                 goto out_tsk;
 181
 182         /* Read the word at location addr in the USER area.  For ptraced
 183            processes, the kernel saves all regs on a syscall. */
 184         case PTRACE_PEEKUSR: {
 185                 ret = -EIO;
 186 #ifdef __LP64__
 187                 if (is_compat_task(child)) {
 188                         unsigned int tmp;
 189
 190                         if (addr & (sizeof(int)-1))
 191                                 goto out_tsk;
 192                         if ((addr = translate_usr_offset(addr)) < 0)
 193                                 goto out_tsk;
 194
 195                         tmp = *(unsigned int *) ((char *) task_regs(child) + addr);
 196                         ret = put_user(tmp, (unsigned int *) data);
 197                         DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n",
 198                                 pid, oaddr, odata, ret, addr, tmp);
 199                 }
 200                 else
 201 #endif
 202                 {
 203                         unsigned long tmp;
 204
 205                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 206                                 goto out_tsk;
 207                         tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 208                         ret = put_user(tmp, (unsigned long *) data);
 209                 }
 210                 goto out_tsk;
 211         }
 212
 213         /* Write the word at location addr in the USER area.  This will need
 214            to change when the kernel no longer saves all regs on a syscall.
 215            FIXME.  There is a problem at the moment in that r3-r18 are only
 216            saved if the process is ptraced on syscall entry, and even then
 217            those values are overwritten by actual register values on syscall
 218            exit. */
 219         case PTRACE_POKEUSR:
 220                 ret = -EIO;
 221                 /* Some register values written here may be ignored in
 222                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 223                  * r31/r31+4, and not with the values in pt_regs.
 224                  */
 225                  /* PT_PSW=0, so this is valid for 32 bit processes under 64
 226                  * bit kernels.
 227                  */
 228                 if (addr == PT_PSW) {
 229                         /* PT_PSW=0, so this is valid for 32 bit processes
 230                          * under 64 bit kernels.
 231                          *
 232                          * Allow writing to Nullify, Divide-step-correction,
 233                          * and carry/borrow bits.
 234                          * BEWARE, if you set N, and then single step, it won't
 235                          * stop on the nullified instruction.
 236                          */
 237                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n",
 238                                 pid, oaddr, odata);
 239                         data &= USER_PSW_BITS;
 240                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 241                         task_regs(child)->gr[0] |= data;
 242                         ret = 0;
 243                         goto out_tsk;
 244                 }
 245 #ifdef __LP64__
 246                 if (is_compat_task(child)) {
 247                         if (addr & (sizeof(int)-1))
 248                                 goto out_tsk;
 249                         if ((addr = translate_usr_offset(addr)) < 0)
 250                                 goto out_tsk;
 251                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n",
 252                                 pid, oaddr, odata, addr);
 253                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 254                                 /* Special case, fp regs are 64 bits anyway */
 255                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 256                                 ret = 0;
 257                         }
 258                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 259                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 260                                         addr == PT_SAR+4) {
 261                                 /* Zero the top 32 bits */
 262                                 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0;
 263                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 264                                 ret = 0;
 265                         }
 266                         goto out_tsk;
 267                 }
 268                 else
 269 #endif
 270                 {
 271                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 272                                 goto out_tsk;
 273                         if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 274                                         addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 275                                         (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 276                                         addr == PT_SAR) {
 277                                 *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 278                                 ret = 0;
 279                         }
 280                         goto out_tsk;
 281                 }
 282
 283         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 284         case PTRACE_CONT:
 285                 ret = -EIO;
 286                 DBG("sys_ptrace(%s)\n",
 287                         request == PTRACE_SYSCALL ? "SYSCALL" : "CONT");
 288                 if ((unsigned long) data > _NSIG)
 289                         goto out_tsk;
 290                 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
 291                 if (request == PTRACE_SYSCALL) {
 292                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 293                 } else {
 294                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 295                 }
 296                 child->exit_code = data;
 297                 goto out_wake_notrap;
 298
 299         case PTRACE_KILL:
 300                 /*
 301                  * make the child exit.  Best I can do is send it a
 302                  * sigkill.  perhaps it should be put in the status
 303                  * that it wants to exit.
 304                  */
 305                 DBG("sys_ptrace(KILL)\n");
 306                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 307                         goto out_tsk;
 308                 child->exit_code = SIGKILL;
 309                 goto out_wake_notrap;
 310
 311         case PTRACE_SINGLEBLOCK:
 312                 DBG("sys_ptrace(SINGLEBLOCK)\n");
 313                 ret = -EIO;
 314                 if ((unsigned long) data > _NSIG)
 315                         goto out_tsk;
 316                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 317                 child->ptrace &= ~PT_SINGLESTEP;
 318                 child->ptrace |= PT_BLOCKSTEP;
 319                 child->exit_code = data;
 320
 321                 /* Enable taken branch trap. */
 322                 pa_psw(child)->r = 0;
 323                 pa_psw(child)->t = 1;
 324                 pa_psw(child)->h = 0;
 325                 pa_psw(child)->l = 0;
 326                 goto out_wake;
 327
 328         case PTRACE_SINGLESTEP:
 329                 DBG("sys_ptrace(SINGLESTEP)\n");
 330                 ret = -EIO;
 331                 if ((unsigned long) data > _NSIG)
 332                         goto out_tsk;
 333
 334                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 335                 child->ptrace &= ~PT_BLOCKSTEP;
 336                 child->ptrace |= PT_SINGLESTEP;
 337                 child->exit_code = data;
 338
 339                 if (pa_psw(child)->n) {
 340                         struct siginfo si;
 341
 342                         /* Nullified, just crank over the queue. */
 343                         task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1];
 344                         task_regs(child)->iasq[0] = task_regs(child)->iasq[1];
 345                         task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4;
 346                         pa_psw(child)->n = 0;
 347                         pa_psw(child)->x = 0;
 348                         pa_psw(child)->y = 0;
 349                         pa_psw(child)->z = 0;
 350                         pa_psw(child)->b = 0;
 351                         ptrace_disable(child);
 352                         /* Don't wake up the child, but let the
 353                            parent know something happened. */
 354                         si.si_code = TRAP_TRACE;
 355                         si.si_addr = (void __user *) (task_regs(child)->iaoq[0] & ~3);
 356                         si.si_signo = SIGTRAP;
 357                         si.si_errno = 0;
 358                         force_sig_info(SIGTRAP, &si, child);
 359                         //notify_parent(child, SIGCHLD);
 360                         //ret = 0;
 361                         goto out_wake;
 362                 }
 363
 364                 /* Enable recovery counter traps.  The recovery counter
 365                  * itself will be set to zero on a task switch.  If the
 366                  * task is suspended on a syscall then the syscall return
 367                  * path will overwrite the recovery counter with a suitable
 368                  * value such that it traps once back in user space.  We
 369                  * disable interrupts in the childs PSW here also, to avoid
 370                  * interrupts while the recovery counter is decrementing.
 371                  */
 372                 pa_psw(child)->r = 1;
 373                 pa_psw(child)->t = 0;
 374                 pa_psw(child)->h = 0;
 375                 pa_psw(child)->l = 0;
 376                 /* give it a chance to run. */
 377                 goto out_wake;
 378
 379         case PTRACE_DETACH:
 380                 ret = ptrace_detach(child, data);
 381                 goto out_tsk;
 382
 383         case PTRACE_GETEVENTMSG:
 384                 ret = put_user(child->ptrace_message, (unsigned int __user *) data);
 385                 goto out_tsk;
 386
 387         default:
 388                 ret = ptrace_request(child, request, addr, data);
 389                 goto out_tsk;
 390         }
 391
 392 out_wake_notrap:
 393         ptrace_disable(child);
 394 out_wake:
 395         wake_up_process(child);
 396         ret = 0;
 397 out_tsk:
 398         put_task_struct(child);
 399 out:
 400         unlock_kernel();
 401         DBG("sys_ptrace(%ld, %d, %lx, %lx) returning %ld\n",
 402                 request, pid, oaddr, odata, ret);
 403         return ret;
 404 }
 405
 406 void syscall_trace(void)
 407 {
 408         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 409                 return;
 410         if (!(current->ptrace & PT_PTRACED))
 411                 return;
 412         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 413                                  ? 0x80 : 0));
 414         /*
 415          * this isn't the same as continuing with a signal, but it will do
 416          * for normal use.  strace only continues with a signal if the
 417          * stopping signal is not SIGTRAP.  -brl
 418          */
 419         if (current->exit_code) {
 420                 send_sig(current->exit_code, current, 1);
 421                 current->exit_code = 0;
 422         }
 423 }