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/errno.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/user.h>
  16 #include <linux/personality.h>
  17 #include <linux/security.h>
  18 #include <linux/compat.h>
  19 #include <linux/signal.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/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 CONFIG_64BIT
  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 arch_ptrace(struct task_struct *child, long request, long addr, long data)
  81 {
  82         long ret;
  83 #ifdef DEBUG_PTRACE
  84         long oaddr=addr, odata=data;
  85 #endif
  86
  87         switch (request) {
  88         case PTRACE_PEEKTEXT: /* read word at location addr. */
  89         case PTRACE_PEEKDATA: {
  90                 int copied;
  91
  92 #ifdef CONFIG_64BIT
  93                 if (__is_compat_task(child)) {
  94                         unsigned int tmp;
  95
  96                         addr &= 0xffffffffL;
  97                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
  98                         ret = -EIO;
  99                         if (copied != sizeof(tmp))
 100                                 goto out_tsk;
 101                         ret = put_user(tmp,(unsigned int *) data);
 102                         DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n",
 103                                 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA",
 104                                 pid, oaddr, odata, ret, tmp);
 105                 }
 106                 else
 107 #endif
 108                 {
 109                         unsigned long tmp;
 110
 111                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 112                         ret = -EIO;
 113                         if (copied != sizeof(tmp))
 114                                 goto out_tsk;
 115                         ret = put_user(tmp,(unsigned long *) data);
 116                 }
 117                 goto out_tsk;
 118         }
 119
 120         /* when I and D space are separate, this will have to be fixed. */
 121         case PTRACE_POKETEXT: /* write the word at location addr. */
 122         case PTRACE_POKEDATA:
 123                 ret = 0;
 124 #ifdef CONFIG_64BIT
 125                 if (__is_compat_task(child)) {
 126                         unsigned int tmp = (unsigned int)data;
 127                         DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n",
 128                                 request == PTRACE_POKETEXT ? "TEXT" : "DATA",
 129                                 pid, oaddr, odata);
 130                         addr &= 0xffffffffL;
 131                         if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp))
 132                                 goto out_tsk;
 133                 }
 134                 else
 135 #endif
 136                 {
 137                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 138                                 goto out_tsk;
 139                 }
 140                 ret = -EIO;
 141                 goto out_tsk;
 142
 143         /* Read the word at location addr in the USER area.  For ptraced
 144            processes, the kernel saves all regs on a syscall. */
 145         case PTRACE_PEEKUSR: {
 146                 ret = -EIO;
 147 #ifdef CONFIG_64BIT
 148                 if (__is_compat_task(child)) {
 149                         unsigned int tmp;
 150
 151                         if (addr & (sizeof(int)-1))
 152                                 goto out_tsk;
 153                         if ((addr = translate_usr_offset(addr)) < 0)
 154                                 goto out_tsk;
 155
 156                         tmp = *(unsigned int *) ((char *) task_regs(child) + addr);
 157                         ret = put_user(tmp, (unsigned int *) data);
 158                         DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n",
 159                                 pid, oaddr, odata, ret, addr, tmp);
 160                 }
 161                 else
 162 #endif
 163                 {
 164                         unsigned long tmp;
 165
 166                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 167                                 goto out_tsk;
 168                         tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 169                         ret = put_user(tmp, (unsigned long *) data);
 170                 }
 171                 goto out_tsk;
 172         }
 173
 174         /* Write the word at location addr in the USER area.  This will need
 175            to change when the kernel no longer saves all regs on a syscall.
 176            FIXME.  There is a problem at the moment in that r3-r18 are only
 177            saved if the process is ptraced on syscall entry, and even then
 178            those values are overwritten by actual register values on syscall
 179            exit. */
 180         case PTRACE_POKEUSR:
 181                 ret = -EIO;
 182                 /* Some register values written here may be ignored in
 183                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 184                  * r31/r31+4, and not with the values in pt_regs.
 185                  */
 186                  /* PT_PSW=0, so this is valid for 32 bit processes under 64
 187                  * bit kernels.
 188                  */
 189                 if (addr == PT_PSW) {
 190                         /* PT_PSW=0, so this is valid for 32 bit processes
 191                          * under 64 bit kernels.
 192                          *
 193                          * Allow writing to Nullify, Divide-step-correction,
 194                          * and carry/borrow bits.
 195                          * BEWARE, if you set N, and then single step, it won't
 196                          * stop on the nullified instruction.
 197                          */
 198                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n",
 199                                 pid, oaddr, odata);
 200                         data &= USER_PSW_BITS;
 201                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 202                         task_regs(child)->gr[0] |= data;
 203                         ret = 0;
 204                         goto out_tsk;
 205                 }
 206 #ifdef CONFIG_64BIT
 207                 if (__is_compat_task(child)) {
 208                         if (addr & (sizeof(int)-1))
 209                                 goto out_tsk;
 210                         if ((addr = translate_usr_offset(addr)) < 0)
 211                                 goto out_tsk;
 212                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n",
 213                                 pid, oaddr, odata, addr);
 214                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 215                                 /* Special case, fp regs are 64 bits anyway */
 216                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 217                                 ret = 0;
 218                         }
 219                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 220                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 221                                         addr == PT_SAR+4) {
 222                                 /* Zero the top 32 bits */
 223                                 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0;
 224                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 225                                 ret = 0;
 226                         }
 227                         goto out_tsk;
 228                 }
 229                 else
 230 #endif
 231                 {
 232                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 233                                 goto out_tsk;
 234                         if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 235                                         addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 236                                         (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 237                                         addr == PT_SAR) {
 238                                 *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 239                                 ret = 0;
 240                         }
 241                         goto out_tsk;
 242                 }
 243
 244         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 245         case PTRACE_CONT:
 246                 ret = -EIO;
 247                 DBG("sys_ptrace(%s)\n",
 248                         request == PTRACE_SYSCALL ? "SYSCALL" : "CONT");
 249                 if (!valid_signal(data))
 250                         goto out_tsk;
 251                 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
 252                 if (request == PTRACE_SYSCALL) {
 253                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 254                 } else {
 255                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 256                 }
 257                 child->exit_code = data;
 258                 goto out_wake_notrap;
 259
 260         case PTRACE_KILL:
 261                 /*
 262                  * make the child exit.  Best I can do is send it a
 263                  * sigkill.  perhaps it should be put in the status
 264                  * that it wants to exit.
 265                  */
 266                 ret = 0;
 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_tsk;
 348
 349         default:
 350                 ret = ptrace_request(child, request, addr, data);
 351                 goto out_tsk;
 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 }