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 #include <linux/signal.h>
  21
  22 #include <asm/uaccess.h>
  23 #include <asm/pgtable.h>
  24 #include <asm/system.h>
  25 #include <asm/processor.h>
  26 #include <asm/offsets.h>
  27
  28 /* PSW bits we allow the debugger to modify */
  29 #define USER_PSW_BITS   (PSW_N | PSW_V | PSW_CB)
  30
  31 #undef DEBUG_PTRACE
  32
  33 #ifdef DEBUG_PTRACE
  34 #define DBG(x...)       printk(x)
  35 #else
  36 #define DBG(x...)
  37 #endif
  38
  39 #ifdef __LP64__
  40
  41 /* This function is needed to translate 32 bit pt_regs offsets in to
  42  * 64 bit pt_regs offsets.  For example, a 32 bit gdb under a 64 bit kernel
  43  * will request offset 12 if it wants gr3, but the lower 32 bits of
  44  * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
  45  * This code relies on a 32 bit pt_regs being comprised of 32 bit values
  46  * except for the fp registers which (a) are 64 bits, and (b) follow
  47  * the gr registers at the start of pt_regs.  The 32 bit pt_regs should
  48  * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
  49  * being 64 bit in both cases.
  50  */
  51
  52 static long translate_usr_offset(long offset)
  53 {
  54         if (offset < 0)
  55                 return -1;
  56         else if (offset <= 32*4)        /* gr[0..31] */
  57                 return offset * 2 + 4;
  58         else if (offset <= 32*4+32*8)   /* gr[0..31] + fr[0..31] */
  59                 return offset + 32*4;
  60         else if (offset < sizeof(struct pt_regs)/2 + 32*4)
  61                 return offset * 2 + 4 - 32*8;
  62         else
  63                 return -1;
  64 }
  65 #endif
  66
  67 /*
  68  * Called by kernel/ptrace.c when detaching..
  69  *
  70  * Make sure single step bits etc are not set.
  71  */
  72 void ptrace_disable(struct task_struct *child)
  73 {
  74         /* make sure the trap bits are not set */
  75         pa_psw(child)->r = 0;
  76         pa_psw(child)->t = 0;
  77         pa_psw(child)->h = 0;
  78         pa_psw(child)->l = 0;
  79 }
  80
  81 long sys_ptrace(long request, pid_t pid, long addr, long data)
  82 {
  83         struct task_struct *child;
  84         long ret;
  85 #ifdef DEBUG_PTRACE
  86         long oaddr=addr, odata=data;
  87 #endif
  88
  89         lock_kernel();
  90         ret = -EPERM;
  91         if (request == PTRACE_TRACEME) {
  92                 /* are we already being traced? */
  93                 if (current->ptrace & PT_PTRACED)
  94                         goto out;
  95
  96                 ret = security_ptrace(current->parent, current);
  97                 if (ret)
  98                         goto out;
  99
 100                 /* set the ptrace bit in the process flags. */
 101                 current->ptrace |= PT_PTRACED;
 102                 ret = 0;
 103                 goto out;
 104         }
 105
 106         ret = -ESRCH;
 107         read_lock(&tasklist_lock);
 108         child = find_task_by_pid(pid);
 109         if (child)
 110                 get_task_struct(child);
 111         read_unlock(&tasklist_lock);
 112         if (!child)
 113                 goto out;
 114         ret = -EPERM;
 115         if (pid == 1)           /* no messing around with init! */
 116                 goto out_tsk;
 117
 118         if (request == PTRACE_ATTACH) {
 119                 ret = ptrace_attach(child);
 120                 goto out_tsk;
 121         }
 122
 123         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 124         if (ret < 0)
 125                 goto out_tsk;
 126
 127         switch (request) {
 128         case PTRACE_PEEKTEXT: /* read word at location addr. */
 129         case PTRACE_PEEKDATA: {
 130                 int copied;
 131
 132 #ifdef __LP64__
 133                 if (is_compat_task(child)) {
 134                         unsigned int tmp;
 135
 136                         addr &= 0xffffffffL;
 137                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 138                         ret = -EIO;
 139                         if (copied != sizeof(tmp))
 140                                 goto out_tsk;
 141                         ret = put_user(tmp,(unsigned int *) data);
 142                         DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n",
 143                                 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA",
 144                                 pid, oaddr, odata, ret, tmp);
 145                 }
 146                 else
 147 #endif
 148                 {
 149                         unsigned long tmp;
 150
 151                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 152                         ret = -EIO;
 153                         if (copied != sizeof(tmp))
 154                                 goto out_tsk;
 155                         ret = put_user(tmp,(unsigned long *) data);
 156                 }
 157                 goto out_tsk;
 158         }
 159
 160         /* when I and D space are separate, this will have to be fixed. */
 161         case PTRACE_POKETEXT: /* write the word at location addr. */
 162         case PTRACE_POKEDATA:
 163                 ret = 0;
 164 #ifdef __LP64__
 165                 if (is_compat_task(child)) {
 166                         unsigned int tmp = (unsigned int)data;
 167                         DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n",
 168                                 request == PTRACE_POKETEXT ? "TEXT" : "DATA",
 169                                 pid, oaddr, odata);
 170                         addr &= 0xffffffffL;
 171                         if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp))
 172                                 goto out_tsk;
 173                 }
 174                 else
 175 #endif
 176                 {
 177                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 178                                 goto out_tsk;
 179                 }
 180                 ret = -EIO;
 181                 goto out_tsk;
 182
 183         /* Read the word at location addr in the USER area.  For ptraced
 184            processes, the kernel saves all regs on a syscall. */
 185         case PTRACE_PEEKUSR: {
 186                 ret = -EIO;
 187 #ifdef __LP64__
 188                 if (is_compat_task(child)) {
 189                         unsigned int tmp;
 190
 191                         if (addr & (sizeof(int)-1))
 192                                 goto out_tsk;
 193                         if ((addr = translate_usr_offset(addr)) < 0)
 194                                 goto out_tsk;
 195
 196                         tmp = *(unsigned int *) ((char *) task_regs(child) + addr);
 197                         ret = put_user(tmp, (unsigned int *) data);
 198                         DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n",
 199                                 pid, oaddr, odata, ret, addr, tmp);
 200                 }
 201                 else
 202 #endif
 203                 {
 204                         unsigned long tmp;
 205
 206                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 207                                 goto out_tsk;
 208                         tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 209                         ret = put_user(tmp, (unsigned long *) data);
 210                 }
 211                 goto out_tsk;
 212         }
 213
 214         /* Write the word at location addr in the USER area.  This will need
 215            to change when the kernel no longer saves all regs on a syscall.
 216            FIXME.  There is a problem at the moment in that r3-r18 are only
 217            saved if the process is ptraced on syscall entry, and even then
 218            those values are overwritten by actual register values on syscall
 219            exit. */
 220         case PTRACE_POKEUSR:
 221                 ret = -EIO;
 222                 /* Some register values written here may be ignored in
 223                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 224                  * r31/r31+4, and not with the values in pt_regs.
 225                  */
 226                  /* PT_PSW=0, so this is valid for 32 bit processes under 64
 227                  * bit kernels.
 228                  */
 229                 if (addr == PT_PSW) {
 230                         /* PT_PSW=0, so this is valid for 32 bit processes
 231                          * under 64 bit kernels.
 232                          *
 233                          * Allow writing to Nullify, Divide-step-correction,
 234                          * and carry/borrow bits.
 235                          * BEWARE, if you set N, and then single step, it won't
 236                          * stop on the nullified instruction.
 237                          */
 238                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n",
 239                                 pid, oaddr, odata);
 240                         data &= USER_PSW_BITS;
 241                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 242                         task_regs(child)->gr[0] |= data;
 243                         ret = 0;
 244                         goto out_tsk;
 245                 }
 246 #ifdef __LP64__
 247                 if (is_compat_task(child)) {
 248                         if (addr & (sizeof(int)-1))
 249                                 goto out_tsk;
 250                         if ((addr = translate_usr_offset(addr)) < 0)
 251                                 goto out_tsk;
 252                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n",
 253                                 pid, oaddr, odata, addr);
 254                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 255                                 /* Special case, fp regs are 64 bits anyway */
 256                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 257                                 ret = 0;
 258                         }
 259                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 260                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 261                                         addr == PT_SAR+4) {
 262                                 /* Zero the top 32 bits */
 263                                 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0;
 264                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 265                                 ret = 0;
 266                         }
 267                         goto out_tsk;
 268                 }
 269                 else
 270 #endif
 271                 {
 272                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 273                                 goto out_tsk;
 274                         if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 275                                         addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 276                                         (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 277                                         addr == PT_SAR) {
 278                                 *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 279                                 ret = 0;
 280                         }
 281                         goto out_tsk;
 282                 }
 283
 284         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 285         case PTRACE_CONT:
 286                 ret = -EIO;
 287                 DBG("sys_ptrace(%s)\n",
 288                         request == PTRACE_SYSCALL ? "SYSCALL" : "CONT");
 289                 if (!valid_signal(data))
 290                         goto out_tsk;
 291                 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
 292                 if (request == PTRACE_SYSCALL) {
 293                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 294                 } else {
 295                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 296                 }
 297                 child->exit_code = data;
 298                 goto out_wake_notrap;
 299
 300         case PTRACE_KILL:
 301                 /*
 302                  * make the child exit.  Best I can do is send it a
 303                  * sigkill.  perhaps it should be put in the status
 304                  * that it wants to exit.
 305                  */
 306                 DBG("sys_ptrace(KILL)\n");
 307                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 308                         goto out_tsk;
 309                 child->exit_code = SIGKILL;
 310                 goto out_wake_notrap;
 311
 312         case PTRACE_SINGLEBLOCK:
 313                 DBG("sys_ptrace(SINGLEBLOCK)\n");
 314                 ret = -EIO;
 315                 if (!valid_signal(data))
 316                         goto out_tsk;
 317                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 318                 child->ptrace &= ~PT_SINGLESTEP;
 319                 child->ptrace |= PT_BLOCKSTEP;
 320                 child->exit_code = data;
 321
 322                 /* Enable taken branch trap. */
 323                 pa_psw(child)->r = 0;
 324                 pa_psw(child)->t = 1;
 325                 pa_psw(child)->h = 0;
 326                 pa_psw(child)->l = 0;
 327                 goto out_wake;
 328
 329         case PTRACE_SINGLESTEP:
 330                 DBG("sys_ptrace(SINGLESTEP)\n");
 331                 ret = -EIO;
 332                 if (!valid_signal(data))
 333                         goto out_tsk;
 334
 335                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 336                 child->ptrace &= ~PT_BLOCKSTEP;
 337                 child->ptrace |= PT_SINGLESTEP;
 338                 child->exit_code = data;
 339
 340                 if (pa_psw(child)->n) {
 341                         struct siginfo si;
 342
 343                         /* Nullified, just crank over the queue. */
 344                         task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1];
 345                         task_regs(child)->iasq[0] = task_regs(child)->iasq[1];
 346                         task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4;
 347                         pa_psw(child)->n = 0;
 348                         pa_psw(child)->x = 0;
 349                         pa_psw(child)->y = 0;
 350                         pa_psw(child)->z = 0;
 351                         pa_psw(child)->b = 0;
 352                         ptrace_disable(child);
 353                         /* Don't wake up the child, but let the
 354                            parent know something happened. */
 355                         si.si_code = TRAP_TRACE;
 356                         si.si_addr = (void __user *) (task_regs(child)->iaoq[0] & ~3);
 357                         si.si_signo = SIGTRAP;
 358                         si.si_errno = 0;
 359                         force_sig_info(SIGTRAP, &si, child);
 360                         //notify_parent(child, SIGCHLD);
 361                         //ret = 0;
 362                         goto out_wake;
 363                 }
 364
 365                 /* Enable recovery counter traps.  The recovery counter
 366                  * itself will be set to zero on a task switch.  If the
 367                  * task is suspended on a syscall then the syscall return
 368                  * path will overwrite the recovery counter with a suitable
 369                  * value such that it traps once back in user space.  We
 370                  * disable interrupts in the childs PSW here also, to avoid
 371                  * interrupts while the recovery counter is decrementing.
 372                  */
 373                 pa_psw(child)->r = 1;
 374                 pa_psw(child)->t = 0;
 375                 pa_psw(child)->h = 0;
 376                 pa_psw(child)->l = 0;
 377                 /* give it a chance to run. */
 378                 goto out_wake;
 379
 380         case PTRACE_DETACH:
 381                 ret = ptrace_detach(child, data);
 382                 goto out_tsk;
 383
 384         case PTRACE_GETEVENTMSG:
 385                 ret = put_user(child->ptrace_message, (unsigned int __user *) data);
 386                 goto out_tsk;
 387
 388         default:
 389                 ret = ptrace_request(child, request, addr, data);
 390                 goto out_tsk;
 391         }
 392
 393 out_wake_notrap:
 394         ptrace_disable(child);
 395 out_wake:
 396         wake_up_process(child);
 397         ret = 0;
 398 out_tsk:
 399         put_task_struct(child);
 400 out:
 401         unlock_kernel();
 402         DBG("sys_ptrace(%ld, %d, %lx, %lx) returning %ld\n",
 403                 request, pid, oaddr, odata, ret);
 404         return ret;
 405 }
 406
 407 void syscall_trace(void)
 408 {
 409         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 410                 return;
 411         if (!(current->ptrace & PT_PTRACED))
 412                 return;
 413         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 414                                  ? 0x80 : 0));
 415         /*
 416          * this isn't the same as continuing with a signal, but it will do
 417          * for normal use.  strace only continues with a signal if the
 418          * stopping signal is not SIGTRAP.  -brl
 419          */
 420         if (current->exit_code) {
 421                 send_sig(current->exit_code, current, 1);
 422                 current->exit_code = 0;
 423         }
 424 }