arch/cris/arch-v10/kernel/ptrace.c

   1 /*
   2  * Copyright (C) 2000-2003, Axis Communications AB.
   3  */
   4
   5 #include <linux/kernel.h>
   6 #include <linux/sched.h>
   7 #include <linux/mm.h>
   8 #include <linux/smp.h>
   9 #include <linux/smp_lock.h>
  10 #include <linux/errno.h>
  11 #include <linux/ptrace.h>
  12 #include <linux/user.h>
  13 #include <linux/signal.h>
  14
  15 #include <asm/uaccess.h>
  16 #include <asm/page.h>
  17 #include <asm/pgtable.h>
  18 #include <asm/system.h>
  19 #include <asm/processor.h>
  20
  21 /*
  22  * Determines which bits in DCCR the user has access to.
  23  * 1 = access, 0 = no access.
  24  */
  25 #define DCCR_MASK 0x0000001f     /* XNZVC */
  26
  27 /*
  28  * Get contents of register REGNO in task TASK.
  29  */
  30 inline long get_reg(struct task_struct *task, unsigned int regno)
  31 {
  32         /* USP is a special case, it's not in the pt_regs struct but
  33          * in the tasks thread struct
  34          */
  35
  36         if (regno == PT_USP)
  37                 return task->thread.usp;
  38         else if (regno < PT_MAX)
  39                 return ((unsigned long *)user_regs(task->thread_info))[regno];
  40         else
  41                 return 0;
  42 }
  43
  44 /*
  45  * Write contents of register REGNO in task TASK.
  46  */
  47 inline int put_reg(struct task_struct *task, unsigned int regno,
  48                           unsigned long data)
  49 {
  50         if (regno == PT_USP)
  51                 task->thread.usp = data;
  52         else if (regno < PT_MAX)
  53                 ((unsigned long *)user_regs(task->thread_info))[regno] = data;
  54         else
  55                 return -1;
  56         return 0;
  57 }
  58
  59 /*
  60  * Called by kernel/ptrace.c when detaching.
  61  *
  62  * Make sure the single step bit is not set.
  63  */
  64 void
  65 ptrace_disable(struct task_struct *child)
  66 {
  67        /* Todo - pending singlesteps? */
  68 }
  69
  70 /*
  71  * Note that this implementation of ptrace behaves differently from vanilla
  72  * ptrace.  Contrary to what the man page says, in the PTRACE_PEEKTEXT,
  73  * PTRACE_PEEKDATA, and PTRACE_PEEKUSER requests the data variable is not
  74  * ignored.  Instead, the data variable is expected to point at a location
  75  * (in user space) where the result of the ptrace call is written (instead of
  76  * being returned).
  77  */
  78 asmlinkage int
  79 sys_ptrace(long request, long pid, long addr, long data)
  80 {
  81         struct task_struct *child;
  82         int ret;
  83         unsigned long __user *datap = (unsigned long __user *)data;
  84
  85         lock_kernel();
  86         ret = -EPERM;
  87
  88         if (request == PTRACE_TRACEME) {
  89                 if (current->ptrace & PT_PTRACED)
  90                         goto out;
  91
  92                 current->ptrace |= PT_PTRACED;
  93                 ret = 0;
  94                 goto out;
  95         }
  96
  97         ret = -ESRCH;
  98         read_lock(&tasklist_lock);
  99         child = find_task_by_pid(pid);
 100
 101         if (child)
 102                 get_task_struct(child);
 103
 104         read_unlock(&tasklist_lock);
 105
 106         if (!child)
 107                 goto out;
 108
 109         ret = -EPERM;
 110
 111         if (pid == 1)           /* Leave the init process alone! */
 112                 goto out_tsk;
 113
 114         if (request == PTRACE_ATTACH) {
 115                 ret = ptrace_attach(child);
 116                 goto out_tsk;
 117         }
 118
 119         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 120         if (ret < 0)
 121                 goto out_tsk;
 122
 123         switch (request) {
 124                 /* Read word at location address. */
 125                 case PTRACE_PEEKTEXT:
 126                 case PTRACE_PEEKDATA: {
 127                         unsigned long tmp;
 128                         int copied;
 129
 130                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 131                         ret = -EIO;
 132
 133                         if (copied != sizeof(tmp))
 134                                 break;
 135
 136                         ret = put_user(tmp,datap);
 137                         break;
 138                 }
 139
 140                 /* Read the word at location address in the USER area. */
 141                 case PTRACE_PEEKUSR: {
 142                         unsigned long tmp;
 143
 144                         ret = -EIO;
 145                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 146                                 break;
 147
 148                         tmp = get_reg(child, addr >> 2);
 149                         ret = put_user(tmp, datap);
 150                         break;
 151                 }
 152
 153                 /* Write the word at location address. */
 154                 case PTRACE_POKETEXT:
 155                 case PTRACE_POKEDATA:
 156                         ret = 0;
 157
 158                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 159                                 break;
 160
 161                         ret = -EIO;
 162                         break;
 163
 164                 /* Write the word at location address in the USER area. */
 165                 case PTRACE_POKEUSR:
 166                         ret = -EIO;
 167                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 168                                 break;
 169
 170                         addr >>= 2;
 171
 172                         if (addr == PT_DCCR) {
 173                                 /* don't allow the tracing process to change stuff like
 174                                  * interrupt enable, kernel/user bit, dma enables etc.
 175                                  */
 176                                 data &= DCCR_MASK;
 177                                 data |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
 178                         }
 179                         if (put_reg(child, addr, data))
 180                                 break;
 181                         ret = 0;
 182                         break;
 183
 184                 case PTRACE_SYSCALL:
 185                 case PTRACE_CONT:
 186                         ret = -EIO;
 187
 188                         if (!valid_signal(data))
 189                                 break;
 190
 191                         if (request == PTRACE_SYSCALL) {
 192                                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 193                         }
 194                         else {
 195                                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 196                         }
 197
 198                         child->exit_code = data;
 199
 200                         /* TODO: make sure any pending breakpoint is killed */
 201                         wake_up_process(child);
 202                         ret = 0;
 203
 204                         break;
 205
 206                 /* Make the child exit by sending it a sigkill. */
 207                 case PTRACE_KILL:
 208                         ret = 0;
 209
 210                         if (child->state == TASK_ZOMBIE)
 211                                 break;
 212
 213                         child->exit_code = SIGKILL;
 214
 215                         /* TODO: make sure any pending breakpoint is killed */
 216                         wake_up_process(child);
 217                         break;
 218
 219                 /* Set the trap flag. */
 220                 case PTRACE_SINGLESTEP:
 221                         ret = -EIO;
 222
 223                         if (!valid_signal(data))
 224                                 break;
 225
 226                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 227
 228                         /* TODO: set some clever breakpoint mechanism... */
 229
 230                         child->exit_code = data;
 231                         wake_up_process(child);
 232                         ret = 0;
 233                         break;
 234
 235                 case PTRACE_DETACH:
 236                         ret = ptrace_detach(child, data);
 237                         break;
 238
 239                 /* Get all GP registers from the child. */
 240                 case PTRACE_GETREGS: {
 241                         int i;
 242                         unsigned long tmp;
 243
 244                         for (i = 0; i <= PT_MAX; i++) {
 245                                 tmp = get_reg(child, i);
 246
 247                                 if (put_user(tmp, datap)) {
 248                                         ret = -EFAULT;
 249                                         goto out_tsk;
 250                                 }
 251
 252                                 data += sizeof(long);
 253                         }
 254
 255                         ret = 0;
 256                         break;
 257                 }
 258
 259                 /* Set all GP registers in the child. */
 260                 case PTRACE_SETREGS: {
 261                         int i;
 262                         unsigned long tmp;
 263
 264                         for (i = 0; i <= PT_MAX; i++) {
 265                                 if (get_user(tmp, datap)) {
 266                                         ret = -EFAULT;
 267                                         goto out_tsk;
 268                                 }
 269
 270                                 if (i == PT_DCCR) {
 271                                         tmp &= DCCR_MASK;
 272                                         tmp |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
 273                                 }
 274
 275                                 put_reg(child, i, tmp);
 276                                 data += sizeof(long);
 277                         }
 278
 279                         ret = 0;
 280                         break;
 281                 }
 282
 283                 default:
 284                         ret = ptrace_request(child, request, addr, data);
 285                         break;
 286         }
 287 out_tsk:
 288         put_task_struct(child);
 289 out:
 290         unlock_kernel();
 291         return ret;
 292 }
 293
 294 void do_syscall_trace(void)
 295 {
 296         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 297                 return;
 298
 299         if (!(current->ptrace & PT_PTRACED))
 300                 return;
 301
 302         /* the 0x80 provides a way for the tracing parent to distinguish
 303            between a syscall stop and SIGTRAP delivery */
 304         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 305                                  ? 0x80 : 0));
 306
 307         /*
 308          * This isn't the same as continuing with a signal, but it will do for
 309          * normal use.
 310          */
 311         if (current->exit_code) {
 312                 send_sig(current->exit_code, current, 1);
 313                 current->exit_code = 0;
 314         }
 315 }