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 #ifdef CONFIG_64BIT
  91                 if (__is_compat_task(child)) {
  92                         int copied;
  93                         unsigned int tmp;
  94
  95                         addr &= 0xffffffffL;
  96                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
  97                         ret = -EIO;
  98                         if (copied != sizeof(tmp))
  99                                 goto out_tsk;
 100                         ret = put_user(tmp,(unsigned int *) data);
 101                         DBG("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n",
 102                                 request == PTRACE_PEEKTEXT ? "TEXT" : "DATA",
 103                                 pid, oaddr, odata, ret, tmp);
 104                 }
 105                 else
 106 #endif
 107                         ret = generic_ptrace_peekdata(child, addr, data);
 108                 goto out_tsk;
 109         }
 110
 111         /* when I and D space are separate, this will have to be fixed. */
 112         case PTRACE_POKETEXT: /* write the word at location addr. */
 113         case PTRACE_POKEDATA:
 114                 ret = 0;
 115 #ifdef CONFIG_64BIT
 116                 if (__is_compat_task(child)) {
 117                         unsigned int tmp = (unsigned int)data;
 118                         DBG("sys_ptrace(POKE%s, %d, %lx, %lx)\n",
 119                                 request == PTRACE_POKETEXT ? "TEXT" : "DATA",
 120                                 pid, oaddr, odata);
 121                         addr &= 0xffffffffL;
 122                         if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp))
 123                                 goto out_tsk;
 124                 }
 125                 else
 126 #endif
 127                 {
 128                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 129                                 goto out_tsk;
 130                 }
 131                 ret = -EIO;
 132                 goto out_tsk;
 133
 134         /* Read the word at location addr in the USER area.  For ptraced
 135            processes, the kernel saves all regs on a syscall. */
 136         case PTRACE_PEEKUSR: {
 137                 ret = -EIO;
 138 #ifdef CONFIG_64BIT
 139                 if (__is_compat_task(child)) {
 140                         unsigned int tmp;
 141
 142                         if (addr & (sizeof(int)-1))
 143                                 goto out_tsk;
 144                         if ((addr = translate_usr_offset(addr)) < 0)
 145                                 goto out_tsk;
 146
 147                         tmp = *(unsigned int *) ((char *) task_regs(child) + addr);
 148                         ret = put_user(tmp, (unsigned int *) data);
 149                         DBG("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n",
 150                                 pid, oaddr, odata, ret, addr, tmp);
 151                 }
 152                 else
 153 #endif
 154                 {
 155                         unsigned long tmp;
 156
 157                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 158                                 goto out_tsk;
 159                         tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
 160                         ret = put_user(tmp, (unsigned long *) data);
 161                 }
 162                 goto out_tsk;
 163         }
 164
 165         /* Write the word at location addr in the USER area.  This will need
 166            to change when the kernel no longer saves all regs on a syscall.
 167            FIXME.  There is a problem at the moment in that r3-r18 are only
 168            saved if the process is ptraced on syscall entry, and even then
 169            those values are overwritten by actual register values on syscall
 170            exit. */
 171         case PTRACE_POKEUSR:
 172                 ret = -EIO;
 173                 /* Some register values written here may be ignored in
 174                  * entry.S:syscall_restore_rfi; e.g. iaoq is written with
 175                  * r31/r31+4, and not with the values in pt_regs.
 176                  */
 177                  /* PT_PSW=0, so this is valid for 32 bit processes under 64
 178                  * bit kernels.
 179                  */
 180                 if (addr == PT_PSW) {
 181                         /* PT_PSW=0, so this is valid for 32 bit processes
 182                          * under 64 bit kernels.
 183                          *
 184                          * Allow writing to Nullify, Divide-step-correction,
 185                          * and carry/borrow bits.
 186                          * BEWARE, if you set N, and then single step, it won't
 187                          * stop on the nullified instruction.
 188                          */
 189                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx)\n",
 190                                 pid, oaddr, odata);
 191                         data &= USER_PSW_BITS;
 192                         task_regs(child)->gr[0] &= ~USER_PSW_BITS;
 193                         task_regs(child)->gr[0] |= data;
 194                         ret = 0;
 195                         goto out_tsk;
 196                 }
 197 #ifdef CONFIG_64BIT
 198                 if (__is_compat_task(child)) {
 199                         if (addr & (sizeof(int)-1))
 200                                 goto out_tsk;
 201                         if ((addr = translate_usr_offset(addr)) < 0)
 202                                 goto out_tsk;
 203                         DBG("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n",
 204                                 pid, oaddr, odata, addr);
 205                         if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
 206                                 /* Special case, fp regs are 64 bits anyway */
 207                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 208                                 ret = 0;
 209                         }
 210                         else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
 211                                         addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
 212                                         addr == PT_SAR+4) {
 213                                 /* Zero the top 32 bits */
 214                                 *(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0;
 215                                 *(unsigned int *) ((char *) task_regs(child) + addr) = data;
 216                                 ret = 0;
 217                         }
 218                         goto out_tsk;
 219                 }
 220                 else
 221 #endif
 222                 {
 223                         if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
 224                                 goto out_tsk;
 225                         if ((addr >= PT_GR1 && addr <= PT_GR31) ||
 226                                         addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
 227                                         (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
 228                                         addr == PT_SAR) {
 229                                 *(unsigned long *) ((char *) task_regs(child) + addr) = data;
 230                                 ret = 0;
 231                         }
 232                         goto out_tsk;
 233                 }
 234
 235         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 236         case PTRACE_CONT:
 237                 ret = -EIO;
 238                 DBG("sys_ptrace(%s)\n",
 239                         request == PTRACE_SYSCALL ? "SYSCALL" : "CONT");
 240                 if (!valid_signal(data))
 241                         goto out_tsk;
 242                 child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
 243                 if (request == PTRACE_SYSCALL) {
 244                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 245                 } else {
 246                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 247                 }
 248                 child->exit_code = data;
 249                 goto out_wake_notrap;
 250
 251         case PTRACE_KILL:
 252                 /*
 253                  * make the child exit.  Best I can do is send it a
 254                  * sigkill.  perhaps it should be put in the status
 255                  * that it wants to exit.
 256                  */
 257                 ret = 0;
 258                 DBG("sys_ptrace(KILL)\n");
 259                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 260                         goto out_tsk;
 261                 child->exit_code = SIGKILL;
 262                 goto out_wake_notrap;
 263
 264         case PTRACE_SINGLEBLOCK:
 265                 DBG("sys_ptrace(SINGLEBLOCK)\n");
 266                 ret = -EIO;
 267                 if (!valid_signal(data))
 268                         goto out_tsk;
 269                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 270                 child->ptrace &= ~PT_SINGLESTEP;
 271                 child->ptrace |= PT_BLOCKSTEP;
 272                 child->exit_code = data;
 273
 274                 /* Enable taken branch trap. */
 275                 pa_psw(child)->r = 0;
 276                 pa_psw(child)->t = 1;
 277                 pa_psw(child)->h = 0;
 278                 pa_psw(child)->l = 0;
 279                 goto out_wake;
 280
 281         case PTRACE_SINGLESTEP:
 282                 DBG("sys_ptrace(SINGLESTEP)\n");
 283                 ret = -EIO;
 284                 if (!valid_signal(data))
 285                         goto out_tsk;
 286
 287                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 288                 child->ptrace &= ~PT_BLOCKSTEP;
 289                 child->ptrace |= PT_SINGLESTEP;
 290                 child->exit_code = data;
 291
 292                 if (pa_psw(child)->n) {
 293                         struct siginfo si;
 294
 295                         /* Nullified, just crank over the queue. */
 296                         task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1];
 297                         task_regs(child)->iasq[0] = task_regs(child)->iasq[1];
 298                         task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4;
 299                         pa_psw(child)->n = 0;
 300                         pa_psw(child)->x = 0;
 301                         pa_psw(child)->y = 0;
 302                         pa_psw(child)->z = 0;
 303                         pa_psw(child)->b = 0;
 304                         ptrace_disable(child);
 305                         /* Don't wake up the child, but let the
 306                            parent know something happened. */
 307                         si.si_code = TRAP_TRACE;
 308                         si.si_addr = (void __user *) (task_regs(child)->iaoq[0] & ~3);
 309                         si.si_signo = SIGTRAP;
 310                         si.si_errno = 0;
 311                         force_sig_info(SIGTRAP, &si, child);
 312                         //notify_parent(child, SIGCHLD);
 313                         //ret = 0;
 314                         goto out_wake;
 315                 }
 316
 317                 /* Enable recovery counter traps.  The recovery counter
 318                  * itself will be set to zero on a task switch.  If the
 319                  * task is suspended on a syscall then the syscall return
 320                  * path will overwrite the recovery counter with a suitable
 321                  * value such that it traps once back in user space.  We
 322                  * disable interrupts in the childs PSW here also, to avoid
 323                  * interrupts while the recovery counter is decrementing.
 324                  */
 325                 pa_psw(child)->r = 1;
 326                 pa_psw(child)->t = 0;
 327                 pa_psw(child)->h = 0;
 328                 pa_psw(child)->l = 0;
 329                 /* give it a chance to run. */
 330                 goto out_wake;
 331
 332         case PTRACE_GETEVENTMSG:
 333                 ret = put_user(child->ptrace_message, (unsigned int __user *) data);
 334                 goto out_tsk;
 335
 336         default:
 337                 ret = ptrace_request(child, request, addr, data);
 338                 goto out_tsk;
 339         }
 340
 341 out_wake_notrap:
 342         ptrace_disable(child);
 343 out_wake:
 344         wake_up_process(child);
 345         ret = 0;
 346 out_tsk:
 347         DBG("arch_ptrace(%ld, %d, %lx, %lx) returning %ld\n",
 348                 request, pid, oaddr, odata, ret);
 349         return ret;
 350 }
 351
 352 void syscall_trace(void)
 353 {
 354         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 355                 return;
 356         if (!(current->ptrace & PT_PTRACED))
 357                 return;
 358         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 359                                  ? 0x80 : 0));
 360         /*
 361          * this isn't the same as continuing with a signal, but it will do
 362          * for normal use.  strace only continues with a signal if the
 363          * stopping signal is not SIGTRAP.  -brl
 364          */
 365         if (current->exit_code) {
 366                 send_sig(current->exit_code, current, 1);
 367                 current->exit_code = 0;
 368         }
 369 }