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 #include <linux/security.h>
  15
  16 #include <asm/uaccess.h>
  17 #include <asm/page.h>
  18 #include <asm/pgtable.h>
  19 #include <asm/system.h>
  20 #include <asm/processor.h>
  21
  22 /*
  23  * Determines which bits in DCCR the user has access to.
  24  * 1 = access, 0 = no access.
  25  */
  26 #define DCCR_MASK 0x0000001f     /* XNZVC */
  27
  28 /*
  29  * Get contents of register REGNO in task TASK.
  30  */
  31 inline long get_reg(struct task_struct *task, unsigned int regno)
  32 {
  33         /* USP is a special case, it's not in the pt_regs struct but
  34          * in the tasks thread struct
  35          */
  36
  37         if (regno == PT_USP)
  38                 return task->thread.usp;
  39         else if (regno < PT_MAX)
  40                 return ((unsigned long *)user_regs(task->thread_info))[regno];
  41         else
  42                 return 0;
  43 }
  44
  45 /*
  46  * Write contents of register REGNO in task TASK.
  47  */
  48 inline int put_reg(struct task_struct *task, unsigned int regno,
  49                           unsigned long data)
  50 {
  51         if (regno == PT_USP)
  52                 task->thread.usp = data;
  53         else if (regno < PT_MAX)
  54                 ((unsigned long *)user_regs(task->thread_info))[regno] = data;
  55         else
  56                 return -1;
  57         return 0;
  58 }
  59
  60 /*
  61  * Called by kernel/ptrace.c when detaching.
  62  *
  63  * Make sure the single step bit is not set.
  64  */
  65 void
  66 ptrace_disable(struct task_struct *child)
  67 {
  68        /* Todo - pending singlesteps? */
  69 }
  70
  71 /*
  72  * Note that this implementation of ptrace behaves differently from vanilla
  73  * ptrace.  Contrary to what the man page says, in the PTRACE_PEEKTEXT,
  74  * PTRACE_PEEKDATA, and PTRACE_PEEKUSER requests the data variable is not
  75  * ignored.  Instead, the data variable is expected to point at a location
  76  * (in user space) where the result of the ptrace call is written (instead of
  77  * being returned).
  78  */
  79 asmlinkage int
  80 sys_ptrace(long request, long pid, long addr, long data)
  81 {
  82         struct task_struct *child;
  83         int ret;
  84         unsigned long __user *datap = (unsigned long __user *)data;
  85
  86         lock_kernel();
  87         ret = -EPERM;
  88
  89         if (request == PTRACE_TRACEME) {
  90                 /* are we already being traced? */
  91                 if (current->ptrace & PT_PTRACED)
  92                         goto out;
  93                 ret = security_ptrace(current->parent, current);
  94                 if (ret)
  95                         goto out;
  96                 /* set the ptrace bit in the process flags. */
  97                 current->ptrace |= PT_PTRACED;
  98                 ret = 0;
  99                 goto out;
 100         }
 101
 102         ret = -ESRCH;
 103         read_lock(&tasklist_lock);
 104         child = find_task_by_pid(pid);
 105
 106         if (child)
 107                 get_task_struct(child);
 108
 109         read_unlock(&tasklist_lock);
 110
 111         if (!child)
 112                 goto out;
 113
 114         ret = -EPERM;
 115
 116         if (pid == 1)           /* Leave the init process alone! */
 117                 goto out_tsk;
 118
 119         if (request == PTRACE_ATTACH) {
 120                 ret = ptrace_attach(child);
 121                 goto out_tsk;
 122         }
 123
 124         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 125         if (ret < 0)
 126                 goto out_tsk;
 127
 128         switch (request) {
 129                 /* Read word at location address. */
 130                 case PTRACE_PEEKTEXT:
 131                 case PTRACE_PEEKDATA: {
 132                         unsigned long tmp;
 133                         int copied;
 134
 135                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 136                         ret = -EIO;
 137
 138                         if (copied != sizeof(tmp))
 139                                 break;
 140
 141                         ret = put_user(tmp,datap);
 142                         break;
 143                 }
 144
 145                 /* Read the word at location address in the USER area. */
 146                 case PTRACE_PEEKUSR: {
 147                         unsigned long tmp;
 148
 149                         ret = -EIO;
 150                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 151                                 break;
 152
 153                         tmp = get_reg(child, addr >> 2);
 154                         ret = put_user(tmp, datap);
 155                         break;
 156                 }
 157
 158                 /* Write the word at location address. */
 159                 case PTRACE_POKETEXT:
 160                 case PTRACE_POKEDATA:
 161                         ret = 0;
 162
 163                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 164                                 break;
 165
 166                         ret = -EIO;
 167                         break;
 168
 169                 /* Write the word at location address in the USER area. */
 170                 case PTRACE_POKEUSR:
 171                         ret = -EIO;
 172                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
 173                                 break;
 174
 175                         addr >>= 2;
 176
 177                         if (addr == PT_DCCR) {
 178                                 /* don't allow the tracing process to change stuff like
 179                                  * interrupt enable, kernel/user bit, dma enables etc.
 180                                  */
 181                                 data &= DCCR_MASK;
 182                                 data |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
 183                         }
 184                         if (put_reg(child, addr, data))
 185                                 break;
 186                         ret = 0;
 187                         break;
 188
 189                 case PTRACE_SYSCALL:
 190                 case PTRACE_CONT:
 191                         ret = -EIO;
 192
 193                         if (!valid_signal(data))
 194                                 break;
 195
 196                         if (request == PTRACE_SYSCALL) {
 197                                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 198                         }
 199                         else {
 200                                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 201                         }
 202
 203                         child->exit_code = data;
 204
 205                         /* TODO: make sure any pending breakpoint is killed */
 206                         wake_up_process(child);
 207                         ret = 0;
 208
 209                         break;
 210
 211                 /* Make the child exit by sending it a sigkill. */
 212                 case PTRACE_KILL:
 213                         ret = 0;
 214
 215                         if (child->exit_state == EXIT_ZOMBIE)
 216                                 break;
 217
 218                         child->exit_code = SIGKILL;
 219
 220                         /* TODO: make sure any pending breakpoint is killed */
 221                         wake_up_process(child);
 222                         break;
 223
 224                 /* Set the trap flag. */
 225                 case PTRACE_SINGLESTEP:
 226                         ret = -EIO;
 227
 228                         if (!valid_signal(data))
 229                                 break;
 230
 231                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 232
 233                         /* TODO: set some clever breakpoint mechanism... */
 234
 235                         child->exit_code = data;
 236                         wake_up_process(child);
 237                         ret = 0;
 238                         break;
 239
 240                 case PTRACE_DETACH:
 241                         ret = ptrace_detach(child, data);
 242                         break;
 243
 244                 /* Get all GP registers from the child. */
 245                 case PTRACE_GETREGS: {
 246                         int i;
 247                         unsigned long tmp;
 248
 249                         for (i = 0; i <= PT_MAX; i++) {
 250                                 tmp = get_reg(child, i);
 251
 252                                 if (put_user(tmp, datap)) {
 253                                         ret = -EFAULT;
 254                                         goto out_tsk;
 255                                 }
 256
 257                                 data += sizeof(long);
 258                         }
 259
 260                         ret = 0;
 261                         break;
 262                 }
 263
 264                 /* Set all GP registers in the child. */
 265                 case PTRACE_SETREGS: {
 266                         int i;
 267                         unsigned long tmp;
 268
 269                         for (i = 0; i <= PT_MAX; i++) {
 270                                 if (get_user(tmp, datap)) {
 271                                         ret = -EFAULT;
 272                                         goto out_tsk;
 273                                 }
 274
 275                                 if (i == PT_DCCR) {
 276                                         tmp &= DCCR_MASK;
 277                                         tmp |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
 278                                 }
 279
 280                                 put_reg(child, i, tmp);
 281                                 data += sizeof(long);
 282                         }
 283
 284                         ret = 0;
 285                         break;
 286                 }
 287
 288                 default:
 289                         ret = ptrace_request(child, request, addr, data);
 290                         break;
 291         }
 292 out_tsk:
 293         put_task_struct(child);
 294 out:
 295         unlock_kernel();
 296         return ret;
 297 }
 298
 299 void do_syscall_trace(void)
 300 {
 301         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 302                 return;
 303
 304         if (!(current->ptrace & PT_PTRACED))
 305                 return;
 306
 307         /* the 0x80 provides a way for the tracing parent to distinguish
 308            between a syscall stop and SIGTRAP delivery */
 309         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 310                                  ? 0x80 : 0));
 311
 312         /*
 313          * This isn't the same as continuing with a signal, but it will do for
 314          * normal use.
 315          */
 316         if (current->exit_code) {
 317                 send_sig(current->exit_code, current, 1);
 318                 current->exit_code = 0;
 319         }
 320 }