arch/um/kernel/ptrace.c

   1 /*
   2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/audit.h"
   7 #include "linux/ptrace.h"
   8 #include "linux/sched.h"
   9 #include "asm/uaccess.h"
  10 #ifdef CONFIG_PROC_MM
  11 #include "proc_mm.h"
  12 #endif
  13 #include "skas_ptrace.h"
  14
  15 static inline void set_singlestepping(struct task_struct *child, int on)
  16 {
  17         if (on)
  18                 child->ptrace |= PT_DTRACE;
  19         else
  20                 child->ptrace &= ~PT_DTRACE;
  21         child->thread.singlestep_syscall = 0;
  22
  23 #ifdef SUBARCH_SET_SINGLESTEPPING
  24         SUBARCH_SET_SINGLESTEPPING(child, on);
  25 #endif
  26 }
  27
  28 /*
  29  * Called by kernel/ptrace.c when detaching..
  30  */
  31 void ptrace_disable(struct task_struct *child)
  32 {
  33         set_singlestepping(child,0);
  34 }
  35
  36 extern int peek_user(struct task_struct * child, long addr, long data);
  37 extern int poke_user(struct task_struct * child, long addr, long data);
  38
  39 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
  40 {
  41         int i, ret;
  42         unsigned long __user *p = (void __user *)(unsigned long)data;
  43
  44         switch (request) {
  45         /* read word at location addr. */
  46         case PTRACE_PEEKTEXT:
  47         case PTRACE_PEEKDATA:
  48                 ret = generic_ptrace_peekdata(child, addr, data);
  49                 break;
  50
  51         /* read the word at location addr in the USER area. */
  52         case PTRACE_PEEKUSR:
  53                 ret = peek_user(child, addr, data);
  54                 break;
  55
  56         /* write the word at location addr. */
  57         case PTRACE_POKETEXT:
  58         case PTRACE_POKEDATA:
  59                 ret = generic_ptrace_pokedata(child, addr, data);
  60                 break;
  61
  62         /* write the word at location addr in the USER area */
  63         case PTRACE_POKEUSR:
  64                 ret = poke_user(child, addr, data);
  65                 break;
  66
  67         case PTRACE_SYSEMU:
  68         case PTRACE_SYSEMU_SINGLESTEP:
  69                 ret = -EIO;
  70                 break;
  71
  72         /* continue and stop at next (return from) syscall */
  73         case PTRACE_SYSCALL:
  74         /* restart after signal. */
  75         case PTRACE_CONT: {
  76                 ret = -EIO;
  77                 if (!valid_signal(data))
  78                         break;
  79
  80                 set_singlestepping(child, 0);
  81                 if (request == PTRACE_SYSCALL)
  82                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
  83                 else clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
  84                 child->exit_code = data;
  85                 wake_up_process(child);
  86                 ret = 0;
  87                 break;
  88         }
  89
  90 /*
  91  * make the child exit.  Best I can do is send it a sigkill.
  92  * perhaps it should be put in the status that it wants to
  93  * exit.
  94  */
  95         case PTRACE_KILL: {
  96                 ret = 0;
  97                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
  98                         break;
  99
 100                 set_singlestepping(child, 0);
 101                 child->exit_code = SIGKILL;
 102                 wake_up_process(child);
 103                 break;
 104         }
 105
 106         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 107                 ret = -EIO;
 108                 if (!valid_signal(data))
 109                         break;
 110                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 111                 set_singlestepping(child, 1);
 112                 child->exit_code = data;
 113                 /* give it a chance to run. */
 114                 wake_up_process(child);
 115                 ret = 0;
 116                 break;
 117         }
 118
 119 #ifdef PTRACE_GETREGS
 120         case PTRACE_GETREGS: { /* Get all gp regs from the child. */
 121                 if (!access_ok(VERIFY_WRITE, p, MAX_REG_OFFSET)) {
 122                         ret = -EIO;
 123                         break;
 124                 }
 125                 for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
 126                         __put_user(getreg(child, i), p);
 127                         p++;
 128                 }
 129                 ret = 0;
 130                 break;
 131         }
 132 #endif
 133 #ifdef PTRACE_SETREGS
 134         case PTRACE_SETREGS: { /* Set all gp regs in the child. */
 135                 unsigned long tmp = 0;
 136                 if (!access_ok(VERIFY_READ, p, MAX_REG_OFFSET)) {
 137                         ret = -EIO;
 138                         break;
 139                 }
 140                 for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
 141                         __get_user(tmp, p);
 142                         putreg(child, i, tmp);
 143                         p++;
 144                 }
 145                 ret = 0;
 146                 break;
 147         }
 148 #endif
 149 #ifdef PTRACE_GETFPREGS
 150         case PTRACE_GETFPREGS: /* Get the child FPU state. */
 151                 ret = get_fpregs((struct user_i387_struct __user *) data,
 152                                  child);
 153                 break;
 154 #endif
 155 #ifdef PTRACE_SETFPREGS
 156         case PTRACE_SETFPREGS: /* Set the child FPU state. */
 157                 ret = set_fpregs((struct user_i387_struct __user *) data,
 158                                  child);
 159                 break;
 160 #endif
 161         case PTRACE_GET_THREAD_AREA:
 162                 ret = ptrace_get_thread_area(child, addr,
 163                                              (struct user_desc __user *) data);
 164                 break;
 165
 166         case PTRACE_SET_THREAD_AREA:
 167                 ret = ptrace_set_thread_area(child, addr,
 168                                              (struct user_desc __user *) data);
 169                 break;
 170
 171         case PTRACE_FAULTINFO: {
 172                 /*
 173                  * Take the info from thread->arch->faultinfo,
 174                  * but transfer max. sizeof(struct ptrace_faultinfo).
 175                  * On i386, ptrace_faultinfo is smaller!
 176                  */
 177                 ret = copy_to_user(p, &child->thread.arch.faultinfo,
 178                                    sizeof(struct ptrace_faultinfo));
 179                 break;
 180         }
 181
 182 #ifdef PTRACE_LDT
 183         case PTRACE_LDT: {
 184                 struct ptrace_ldt ldt;
 185
 186                 if (copy_from_user(&ldt, p, sizeof(ldt))) {
 187                         ret = -EIO;
 188                         break;
 189                 }
 190
 191                 /*
 192                  * This one is confusing, so just punt and return -EIO for
 193                  * now
 194                  */
 195                 ret = -EIO;
 196                 break;
 197         }
 198 #endif
 199 #ifdef CONFIG_PROC_MM
 200         case PTRACE_SWITCH_MM: {
 201                 struct mm_struct *old = child->mm;
 202                 struct mm_struct *new = proc_mm_get_mm(data);
 203
 204                 if (IS_ERR(new)) {
 205                         ret = PTR_ERR(new);
 206                         break;
 207                 }
 208
 209                 atomic_inc(&new->mm_users);
 210                 child->mm = new;
 211                 child->active_mm = new;
 212                 mmput(old);
 213                 ret = 0;
 214                 break;
 215         }
 216 #endif
 217 #ifdef PTRACE_ARCH_PRCTL
 218         case PTRACE_ARCH_PRCTL:
 219                 /* XXX Calls ptrace on the host - needs some SMP thinking */
 220                 ret = arch_prctl(child, data, (void *) addr);
 221                 break;
 222 #endif
 223         default:
 224                 ret = ptrace_request(child, request, addr, data);
 225                 if (ret == -EIO)
 226                         ret = subarch_ptrace(child, request, addr, data);
 227                 break;
 228         }
 229
 230         return ret;
 231 }
 232
 233 static void send_sigtrap(struct task_struct *tsk, struct uml_pt_regs *regs,
 234                   int error_code)
 235 {
 236         struct siginfo info;
 237
 238         memset(&info, 0, sizeof(info));
 239         info.si_signo = SIGTRAP;
 240         info.si_code = TRAP_BRKPT;
 241
 242         /* User-mode eip? */
 243         info.si_addr = UPT_IS_USER(regs) ? (void __user *) UPT_IP(regs) : NULL;
 244
 245         /* Send us the fake SIGTRAP */
 246         force_sig_info(SIGTRAP, &info, tsk);
 247 }
 248
 249 /*
 250  * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
 251  * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
 252  */
 253 void syscall_trace(struct uml_pt_regs *regs, int entryexit)
 254 {
 255         int is_singlestep = (current->ptrace & PT_DTRACE) && entryexit;
 256         int tracesysgood;
 257
 258         if (unlikely(current->audit_context)) {
 259                 if (!entryexit)
 260                         audit_syscall_entry(HOST_AUDIT_ARCH,
 261                                             UPT_SYSCALL_NR(regs),
 262                                             UPT_SYSCALL_ARG1(regs),
 263                                             UPT_SYSCALL_ARG2(regs),
 264                                             UPT_SYSCALL_ARG3(regs),
 265                                             UPT_SYSCALL_ARG4(regs));
 266                 else audit_syscall_exit(AUDITSC_RESULT(UPT_SYSCALL_RET(regs)),
 267                                         UPT_SYSCALL_RET(regs));
 268         }
 269
 270         /* Fake a debug trap */
 271         if (is_singlestep)
 272                 send_sigtrap(current, regs, 0);
 273
 274         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 275                 return;
 276
 277         if (!(current->ptrace & PT_PTRACED))
 278                 return;
 279
 280         /*
 281          * the 0x80 provides a way for the tracing parent to distinguish
 282          * between a syscall stop and SIGTRAP delivery
 283          */
 284         tracesysgood = (current->ptrace & PT_TRACESYSGOOD);
 285         ptrace_notify(SIGTRAP | (tracesysgood ? 0x80 : 0));
 286
 287         if (entryexit) /* force do_signal() --> is_syscall() */
 288                 set_thread_flag(TIF_SIGPENDING);
 289
 290         /*
 291          * this isn't the same as continuing with a signal, but it will do
 292          * for normal use.  strace only continues with a signal if the
 293          * stopping signal is not SIGTRAP.  -brl
 294          */
 295         if (current->exit_code) {
 296                 send_sig(current->exit_code, current, 1);
 297                 current->exit_code = 0;
 298         }
 299 }