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/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 arch_ptrace(struct task_struct *child, long request, long addr, long data)
  82 {
  83         long ret;
  84 #ifdef DEBUG_PTRACE
  85         long oaddr=addr, odata=data;
  86 #endif
  87
  88         switch (request) {
  89         case PTRACE_PEEKTEXT: /* read word at location addr. */
  90         case PTRACE_PEEKDATA: {
  91                 int copied;
  92
  93 #ifdef __LP64__
  94                 if (is_compat_task(child)) {
  95                         unsigned int tmp;
  96
  97                         addr &= 0xffffffffL;
  98                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
  99                         ret = -EIO;
 100                         if (copied != sizeof(tmp))
 101                                 goto out_tsk;
 102                         ret = put_user(tmp,(unsigned int *) data);
 103                         DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n",
 104                                 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA",
 105                                 pid, oaddr, odata, ret, tmp);
 106                 }
 107                 else
 108 #endif
 109                 {
 110                         unsigned long tmp;
 111
 112                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 113                         ret = -EIO;
 114                         if (copied != sizeof(tmp))
 115                                 goto out_tsk;
 116                         ret = put_user(tmp,(unsigned long *) data);
 117                 }
 118                 goto out_tsk;
 119         }
 120
 121         /* when I and D space are separate, this will have to be fixed. */
 122         case PTRACE_POKETEXT: /* write the word at location addr. */
 123         case PTRACE_POKEDATA:
 124                 ret = 0;
 125 #ifdef __LP64__
 126                 if (is_compat_task(child)) {
 127                         unsigned int tmp = (unsigned int)data;
 128                         DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n",
 129                                 request == PTRACE_POKETEXT ? "TEXT" : "DATA",
 130                                 pid, oaddr, odata);
 131                         addr &= 0xffffffffL;
 132                         if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp))
 133                                 goto out_tsk;
 134                 }
 135                 else
 136 #endif
 137                 {
 138                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 139                                 goto out_tsk;
 140                 }
 141                 ret = -EIO;
 142                 goto out_tsk;
 143
 144         /* Read the word at location addr in the USER area.  For ptraced
 145            processes, the kernel saves all regs on a syscall. */
 146         case PTRACE_PEEKUSR: {
 147                 ret = -EIO;
 148 #ifdef __LP64__
 149                 if (is_compat_task(child)) {
 150                         unsigned int tmp;
 151
 152                         if (addr & (sizeof(int)-1))
 153                                 goto out_tsk;
 154                         if ((addr = translate_usr_offset(addr)) < 0)
 155                                 goto out_tsk;
 156
 157                         tmp = *(unsigned int *) ((char *) task_regs(child) + addr);
 158                         ret = put_user(tmp, (unsigned int *) data);
 159                         DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n",
 160                                 pid, oaddr, odata, ret, addr, tmp);
 161                 }
 162                 else
 163 #endif
 164                 {
 165                         unsigned long tmp;
 166
 167                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 168                                 goto out_tsk;
 169                         tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 170                         ret = put_user(tmp, (unsigned long *) data);
 171                 }
 172                 goto out_tsk;
 173         }
 174
 175         /* Write the word at location addr in the USER area.  This will need
 176            to change when the kernel no longer saves all regs on a syscall.
 177            FIXME.  There is a problem at the moment in that r3-r18 are only
 178            saved if the process is ptraced on syscall entry, and even then
 179            those values are overwritten by actual register values on syscall
 180            exit. */
 181         case PTRACE_POKEUSR:
 182                 ret = -EIO;
 183                 /* Some register values written here may be ignored in
 184                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 185                  * r31/r31+4, and not with the values in pt_regs.
 186                  */
 187                  /* PT_PSW=0, so this is valid for 32 bit processes under 64
 188                  * bit kernels.
 189                  */
 190                 if (addr == PT_PSW) {
 191                         /* PT_PSW=0, so this is valid for 32 bit processes
 192                          * under 64 bit kernels.
 193                          *
 194                          * Allow writing to Nullify, Divide-step-correction,
 195                          * and carry/borrow bits.
 196                          * BEWARE, if you set N, and then single step, it won't
 197                          * stop on the nullified instruction.
 198                          */
 199                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n",
 200                                 pid, oaddr, odata);
 201                         data &= USER_PSW_BITS;
 202                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 203                         task_regs(child)->gr[0] |= data;
 204                         ret = 0;
 205                         goto out_tsk;
 206                 }
 207 #ifdef __LP64__
 208                 if (is_compat_task(child)) {
 209                         if (addr & (sizeof(int)-1))
 210                                 goto out_tsk;
 211                         if ((addr = translate_usr_offset(addr)) < 0)
 212                                 goto out_tsk;
 213                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n",
 214                                 pid, oaddr, odata, addr);
 215                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 216                                 /* Special case, fp regs are 64 bits anyway */
 217                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 218                                 ret = 0;
 219                         }
 220                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 221                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 222                                         addr == PT_SAR+4) {
 223                                 /* Zero the top 32 bits */
 224                                 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0;
 225                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 226                                 ret = 0;
 227                         }
 228                         goto out_tsk;
 229                 }
 230                 else
 231 #endif
 232                 {
 233                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 234                                 goto out_tsk;
 235                         if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 236                                         addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 237                                         (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 238                                         addr == PT_SAR) {
 239                                 *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 240                                 ret = 0;
 241                         }
 242                         goto out_tsk;
 243                 }
 244
 245         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 246         case PTRACE_CONT:
 247                 ret = -EIO;
 248                 DBG("sys_ptrace(%s)\n",
 249                         request == PTRACE_SYSCALL ? "SYSCALL" : "CONT");
 250                 if (!valid_signal(data))
 251                         goto out_tsk;
 252                 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
 253                 if (request == PTRACE_SYSCALL) {
 254                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 255                 } else {
 256                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 257                 }
 258                 child->exit_code = data;
 259                 goto out_wake_notrap;
 260
 261         case PTRACE_KILL:
 262                 /*
 263                  * make the child exit.  Best I can do is send it a
 264                  * sigkill.  perhaps it should be put in the status
 265                  * that it wants to exit.
 266                  */
 267                 DBG("sys_ptrace(KILL)\n");
 268                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 269                         goto out_tsk;
 270                 child->exit_code = SIGKILL;
 271                 goto out_wake_notrap;
 272
 273         case PTRACE_SINGLEBLOCK:
 274                 DBG("sys_ptrace(SINGLEBLOCK)\n");
 275                 ret = -EIO;
 276                 if (!valid_signal(data))
 277                         goto out_tsk;
 278                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 279                 child->ptrace &= ~PT_SINGLESTEP;
 280                 child->ptrace |= PT_BLOCKSTEP;
 281                 child->exit_code = data;
 282
 283                 /* Enable taken branch trap. */
 284                 pa_psw(child)->r = 0;
 285                 pa_psw(child)->t = 1;
 286                 pa_psw(child)->h = 0;
 287                 pa_psw(child)->l = 0;
 288                 goto out_wake;
 289
 290         case PTRACE_SINGLESTEP:
 291                 DBG("sys_ptrace(SINGLESTEP)\n");
 292                 ret = -EIO;
 293                 if (!valid_signal(data))
 294                         goto out_tsk;
 295
 296                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 297                 child->ptrace &= ~PT_BLOCKSTEP;
 298                 child->ptrace |= PT_SINGLESTEP;
 299                 child->exit_code = data;
 300
 301                 if (pa_psw(child)->n) {
 302                         struct siginfo si;
 303
 304                         /* Nullified, just crank over the queue. */
 305                         task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1];
 306                         task_regs(child)->iasq[0] = task_regs(child)->iasq[1];
 307                         task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4;
 308                         pa_psw(child)->n = 0;
 309                         pa_psw(child)->x = 0;
 310                         pa_psw(child)->y = 0;
 311                         pa_psw(child)->z = 0;
 312                         pa_psw(child)->b = 0;
 313                         ptrace_disable(child);
 314                         /* Don't wake up the child, but let the
 315                            parent know something happened. */
 316                         si.si_code = TRAP_TRACE;
 317                         si.si_addr = (void __user *) (task_regs(child)->iaoq[0] & ~3);
 318                         si.si_signo = SIGTRAP;
 319                         si.si_errno = 0;
 320                         force_sig_info(SIGTRAP, &si, child);
 321                         //notify_parent(child, SIGCHLD);
 322                         //ret = 0;
 323                         goto out_wake;
 324                 }
 325
 326                 /* Enable recovery counter traps.  The recovery counter
 327                  * itself will be set to zero on a task switch.  If the
 328                  * task is suspended on a syscall then the syscall return
 329                  * path will overwrite the recovery counter with a suitable
 330                  * value such that it traps once back in user space.  We
 331                  * disable interrupts in the childs PSW here also, to avoid
 332                  * interrupts while the recovery counter is decrementing.
 333                  */
 334                 pa_psw(child)->r = 1;
 335                 pa_psw(child)->t = 0;
 336                 pa_psw(child)->h = 0;
 337                 pa_psw(child)->l = 0;
 338                 /* give it a chance to run. */
 339                 goto out_wake;
 340
 341         case PTRACE_DETACH:
 342                 ret = ptrace_detach(child, data);
 343                 goto out_tsk;
 344
 345         case PTRACE_GETEVENTMSG:
 346                 ret = put_user(child->ptrace_message, (unsigned int __user *) data);
 347                 goto out;
 348
 349         default:
 350                 ret = ptrace_request(child, request, addr, data);
 351                 goto out;
 352         }
 353
 354 out_wake_notrap:
 355         ptrace_disable(child);
 356 out_wake:
 357         wake_up_process(child);
 358         ret = 0;
 359 out_tsk:
 360         DBG("arch_ptrace(%ld, %d, %lx, %lx) returning %ld\n",
 361                 request, pid, oaddr, odata, ret);
 362         return ret;
 363 }
 364
 365 void syscall_trace(void)
 366 {
 367         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 368                 return;
 369         if (!(current->ptrace & PT_PTRACED))
 370                 return;
 371         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 372                                  ? 0x80 : 0));
 373         /*
 374          * this isn't the same as continuing with a signal, but it will do
 375          * for normal use.  strace only continues with a signal if the
 376          * stopping signal is not SIGTRAP.  -brl
 377          */
 378         if (current->exit_code) {
 379                 send_sig(current->exit_code, current, 1);
 380                 current->exit_code = 0;
 381         }
 382 }