arch/i386/kernel/ptrace.c

   1 /* ptrace.c */
   2 /* By Ross Biro 1/23/92 */
   3 /*
   4  * Pentium III FXSR, SSE support
   5  *      Gareth Hughes <gareth@valinux.com>, May 2000
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/sched.h>
  10 #include <linux/mm.h>
  11 #include <linux/smp.h>
  12 #include <linux/smp_lock.h>
  13 #include <linux/errno.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/user.h>
  16 #include <linux/security.h>
  17 #include <linux/audit.h>
  18 #include <linux/seccomp.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/i387.h>
  26 #include <asm/debugreg.h>
  27 #include <asm/ldt.h>
  28 #include <asm/desc.h>
  29
  30 /*
  31  * does not yet catch signals sent when the child dies.
  32  * in exit.c or in signal.c.
  33  */
  34
  35 /* determines which flags the user has access to. */
  36 /* 1 = access 0 = no access */
  37 #define FLAG_MASK 0x00044dd5
  38
  39 /* set's the trap flag. */
  40 #define TRAP_FLAG 0x100
  41
  42 /*
  43  * Offset of eflags on child stack..
  44  */
  45 #define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs))
  46
  47 static inline struct pt_regs *get_child_regs(struct task_struct *task)
  48 {
  49         void *stack_top = (void *)task->thread.esp0;
  50         return stack_top - sizeof(struct pt_regs);
  51 }
  52
  53 /*
  54  * this routine will get a word off of the processes privileged stack.
  55  * the offset is how far from the base addr as stored in the TSS.
  56  * this routine assumes that all the privileged stacks are in our
  57  * data space.
  58  */
  59 static inline int get_stack_long(struct task_struct *task, int offset)
  60 {
  61         unsigned char *stack;
  62
  63         stack = (unsigned char *)task->thread.esp0;
  64         stack += offset;
  65         return (*((int *)stack));
  66 }
  67
  68 /*
  69  * this routine will put a word on the processes privileged stack.
  70  * the offset is how far from the base addr as stored in the TSS.
  71  * this routine assumes that all the privileged stacks are in our
  72  * data space.
  73  */
  74 static inline int put_stack_long(struct task_struct *task, int offset,
  75         unsigned long data)
  76 {
  77         unsigned char * stack;
  78
  79         stack = (unsigned char *) task->thread.esp0;
  80         stack += offset;
  81         *(unsigned long *) stack = data;
  82         return 0;
  83 }
  84
  85 static int putreg(struct task_struct *child,
  86         unsigned long regno, unsigned long value)
  87 {
  88         switch (regno >> 2) {
  89                 case FS:
  90                         if (value && (value & 3) != 3)
  91                                 return -EIO;
  92                         child->thread.fs = value;
  93                         return 0;
  94                 case GS:
  95                         if (value && (value & 3) != 3)
  96                                 return -EIO;
  97                         child->thread.gs = value;
  98                         return 0;
  99                 case DS:
 100                 case ES:
 101                         if (value && (value & 3) != 3)
 102                                 return -EIO;
 103                         value &= 0xffff;
 104                         break;
 105                 case SS:
 106                 case CS:
 107                         if ((value & 3) != 3)
 108                                 return -EIO;
 109                         value &= 0xffff;
 110                         break;
 111                 case EFL:
 112                         value &= FLAG_MASK;
 113                         value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
 114                         break;
 115         }
 116         if (regno > GS*4)
 117                 regno -= 2*4;
 118         put_stack_long(child, regno - sizeof(struct pt_regs), value);
 119         return 0;
 120 }
 121
 122 static unsigned long getreg(struct task_struct *child,
 123         unsigned long regno)
 124 {
 125         unsigned long retval = ~0UL;
 126
 127         switch (regno >> 2) {
 128                 case FS:
 129                         retval = child->thread.fs;
 130                         break;
 131                 case GS:
 132                         retval = child->thread.gs;
 133                         break;
 134                 case DS:
 135                 case ES:
 136                 case SS:
 137                 case CS:
 138                         retval = 0xffff;
 139                         /* fall through */
 140                 default:
 141                         if (regno > GS*4)
 142                                 regno -= 2*4;
 143                         regno = regno - sizeof(struct pt_regs);
 144                         retval &= get_stack_long(child, regno);
 145         }
 146         return retval;
 147 }
 148
 149 #define LDT_SEGMENT 4
 150
 151 static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_regs *regs)
 152 {
 153         unsigned long addr, seg;
 154
 155         addr = regs->eip;
 156         seg = regs->xcs & 0xffff;
 157         if (regs->eflags & VM_MASK) {
 158                 addr = (addr & 0xffff) + (seg << 4);
 159                 return addr;
 160         }
 161
 162         /*
 163          * We'll assume that the code segments in the GDT
 164          * are all zero-based. That is largely true: the
 165          * TLS segments are used for data, and the PNPBIOS
 166          * and APM bios ones we just ignore here.
 167          */
 168         if (seg & LDT_SEGMENT) {
 169                 u32 *desc;
 170                 unsigned long base;
 171
 172                 down(&child->mm->context.sem);
 173                 desc = child->mm->context.ldt + (seg & ~7);
 174                 base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000);
 175
 176                 /* 16-bit code segment? */
 177                 if (!((desc[1] >> 22) & 1))
 178                         addr &= 0xffff;
 179                 addr += base;
 180                 up(&child->mm->context.sem);
 181         }
 182         return addr;
 183 }
 184
 185 static inline int is_at_popf(struct task_struct *child, struct pt_regs *regs)
 186 {
 187         int i, copied;
 188         unsigned char opcode[16];
 189         unsigned long addr = convert_eip_to_linear(child, regs);
 190
 191         copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
 192         for (i = 0; i < copied; i++) {
 193                 switch (opcode[i]) {
 194                 /* popf */
 195                 case 0x9d:
 196                         return 1;
 197                 /* opcode and address size prefixes */
 198                 case 0x66: case 0x67:
 199                         continue;
 200                 /* irrelevant prefixes (segment overrides and repeats) */
 201                 case 0x26: case 0x2e:
 202                 case 0x36: case 0x3e:
 203                 case 0x64: case 0x65:
 204                 case 0xf0: case 0xf2: case 0xf3:
 205                         continue;
 206
 207                 /*
 208                  * pushf: NOTE! We should probably not let
 209                  * the user see the TF bit being set. But
 210                  * it's more pain than it's worth to avoid
 211                  * it, and a debugger could emulate this
 212                  * all in user space if it _really_ cares.
 213                  */
 214                 case 0x9c:
 215                 default:
 216                         return 0;
 217                 }
 218         }
 219         return 0;
 220 }
 221
 222 static void set_singlestep(struct task_struct *child)
 223 {
 224         struct pt_regs *regs = get_child_regs(child);
 225
 226         /*
 227          * Always set TIF_SINGLESTEP - this guarantees that
 228          * we single-step system calls etc..  This will also
 229          * cause us to set TF when returning to user mode.
 230          */
 231         set_tsk_thread_flag(child, TIF_SINGLESTEP);
 232
 233         /*
 234          * If TF was already set, don't do anything else
 235          */
 236         if (regs->eflags & TRAP_FLAG)
 237                 return;
 238
 239         /* Set TF on the kernel stack.. */
 240         regs->eflags |= TRAP_FLAG;
 241
 242         /*
 243          * ..but if TF is changed by the instruction we will trace,
 244          * don't mark it as being "us" that set it, so that we
 245          * won't clear it by hand later.
 246          */
 247         if (is_at_popf(child, regs))
 248                 return;
 249
 250         child->ptrace |= PT_DTRACE;
 251 }
 252
 253 static void clear_singlestep(struct task_struct *child)
 254 {
 255         /* Always clear TIF_SINGLESTEP... */
 256         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 257
 258         /* But touch TF only if it was set by us.. */
 259         if (child->ptrace & PT_DTRACE) {
 260                 struct pt_regs *regs = get_child_regs(child);
 261                 regs->eflags &= ~TRAP_FLAG;
 262                 child->ptrace &= ~PT_DTRACE;
 263         }
 264 }
 265
 266 /*
 267  * Called by kernel/ptrace.c when detaching..
 268  *
 269  * Make sure the single step bit is not set.
 270  */
 271 void ptrace_disable(struct task_struct *child)
 272 {
 273         clear_singlestep(child);
 274 }
 275
 276 /*
 277  * Perform get_thread_area on behalf of the traced child.
 278  */
 279 static int
 280 ptrace_get_thread_area(struct task_struct *child,
 281                        int idx, struct user_desc __user *user_desc)
 282 {
 283         struct user_desc info;
 284         struct desc_struct *desc;
 285
 286 /*
 287  * Get the current Thread-Local Storage area:
 288  */
 289
 290 #define GET_BASE(desc) ( \
 291         (((desc)->a >> 16) & 0x0000ffff) | \
 292         (((desc)->b << 16) & 0x00ff0000) | \
 293         ( (desc)->b        & 0xff000000)   )
 294
 295 #define GET_LIMIT(desc) ( \
 296         ((desc)->a & 0x0ffff) | \
 297          ((desc)->b & 0xf0000) )
 298
 299 #define GET_32BIT(desc)         (((desc)->b >> 22) & 1)
 300 #define GET_CONTENTS(desc)      (((desc)->b >> 10) & 3)
 301 #define GET_WRITABLE(desc)      (((desc)->b >>  9) & 1)
 302 #define GET_LIMIT_PAGES(desc)   (((desc)->b >> 23) & 1)
 303 #define GET_PRESENT(desc)       (((desc)->b >> 15) & 1)
 304 #define GET_USEABLE(desc)       (((desc)->b >> 20) & 1)
 305
 306         if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
 307                 return -EINVAL;
 308
 309         desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
 310
 311         info.entry_number = idx;
 312         info.base_addr = GET_BASE(desc);
 313         info.limit = GET_LIMIT(desc);
 314         info.seg_32bit = GET_32BIT(desc);
 315         info.contents = GET_CONTENTS(desc);
 316         info.read_exec_only = !GET_WRITABLE(desc);
 317         info.limit_in_pages = GET_LIMIT_PAGES(desc);
 318         info.seg_not_present = !GET_PRESENT(desc);
 319         info.useable = GET_USEABLE(desc);
 320
 321         if (copy_to_user(user_desc, &info, sizeof(info)))
 322                 return -EFAULT;
 323
 324         return 0;
 325 }
 326
 327 /*
 328  * Perform set_thread_area on behalf of the traced child.
 329  */
 330 static int
 331 ptrace_set_thread_area(struct task_struct *child,
 332                        int idx, struct user_desc __user *user_desc)
 333 {
 334         struct user_desc info;
 335         struct desc_struct *desc;
 336
 337         if (copy_from_user(&info, user_desc, sizeof(info)))
 338                 return -EFAULT;
 339
 340         if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
 341                 return -EINVAL;
 342
 343         desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
 344         if (LDT_empty(&info)) {
 345                 desc->a = 0;
 346                 desc->b = 0;
 347         } else {
 348                 desc->a = LDT_entry_a(&info);
 349                 desc->b = LDT_entry_b(&info);
 350         }
 351
 352         return 0;
 353 }
 354
 355 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
 356 {
 357         struct task_struct *child;
 358         struct user * dummy = NULL;
 359         int i, ret;
 360         unsigned long __user *datap = (unsigned long __user *)data;
 361
 362         lock_kernel();
 363         ret = -EPERM;
 364         if (request == PTRACE_TRACEME) {
 365                 /* are we already being traced? */
 366                 if (current->ptrace & PT_PTRACED)
 367                         goto out;
 368                 ret = security_ptrace(current->parent, current);
 369                 if (ret)
 370                         goto out;
 371                 /* set the ptrace bit in the process flags. */
 372                 current->ptrace |= PT_PTRACED;
 373                 ret = 0;
 374                 goto out;
 375         }
 376         ret = -ESRCH;
 377         read_lock(&tasklist_lock);
 378         child = find_task_by_pid(pid);
 379         if (child)
 380                 get_task_struct(child);
 381         read_unlock(&tasklist_lock);
 382         if (!child)
 383                 goto out;
 384
 385         ret = -EPERM;
 386         if (pid == 1)           /* you may not mess with init */
 387                 goto out_tsk;
 388
 389         if (request == PTRACE_ATTACH) {
 390                 ret = ptrace_attach(child);
 391                 goto out_tsk;
 392         }
 393
 394         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 395         if (ret < 0)
 396                 goto out_tsk;
 397
 398         switch (request) {
 399         /* when I and D space are separate, these will need to be fixed. */
 400         case PTRACE_PEEKTEXT: /* read word at location addr. */
 401         case PTRACE_PEEKDATA: {
 402                 unsigned long tmp;
 403                 int copied;
 404
 405                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 406                 ret = -EIO;
 407                 if (copied != sizeof(tmp))
 408                         break;
 409                 ret = put_user(tmp, datap);
 410                 break;
 411         }
 412
 413         /* read the word at location addr in the USER area. */
 414         case PTRACE_PEEKUSR: {
 415                 unsigned long tmp;
 416
 417                 ret = -EIO;
 418                 if ((addr & 3) || addr < 0 ||
 419                     addr > sizeof(struct user) - 3)
 420                         break;
 421
 422                 tmp = 0;  /* Default return condition */
 423                 if(addr < FRAME_SIZE*sizeof(long))
 424                         tmp = getreg(child, addr);
 425                 if(addr >= (long) &dummy->u_debugreg[0] &&
 426                    addr <= (long) &dummy->u_debugreg[7]){
 427                         addr -= (long) &dummy->u_debugreg[0];
 428                         addr = addr >> 2;
 429                         tmp = child->thread.debugreg[addr];
 430                 }
 431                 ret = put_user(tmp, datap);
 432                 break;
 433         }
 434
 435         /* when I and D space are separate, this will have to be fixed. */
 436         case PTRACE_POKETEXT: /* write the word at location addr. */
 437         case PTRACE_POKEDATA:
 438                 ret = 0;
 439                 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 440                         break;
 441                 ret = -EIO;
 442                 break;
 443
 444         case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
 445                 ret = -EIO;
 446                 if ((addr & 3) || addr < 0 ||
 447                     addr > sizeof(struct user) - 3)
 448                         break;
 449
 450                 if (addr < FRAME_SIZE*sizeof(long)) {
 451                         ret = putreg(child, addr, data);
 452                         break;
 453                 }
 454                 /* We need to be very careful here.  We implicitly
 455                    want to modify a portion of the task_struct, and we
 456                    have to be selective about what portions we allow someone
 457                    to modify. */
 458
 459                   ret = -EIO;
 460                   if(addr >= (long) &dummy->u_debugreg[0] &&
 461                      addr <= (long) &dummy->u_debugreg[7]){
 462
 463                           if(addr == (long) &dummy->u_debugreg[4]) break;
 464                           if(addr == (long) &dummy->u_debugreg[5]) break;
 465                           if(addr < (long) &dummy->u_debugreg[4] &&
 466                              ((unsigned long) data) >= TASK_SIZE-3) break;
 467
 468                           /* Sanity-check data. Take one half-byte at once with
 469                            * check = (val >> (16 + 4*i)) & 0xf. It contains the
 470                            * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
 471                            * 2 and 3 are LENi. Given a list of invalid values,
 472                            * we do mask |= 1 << invalid_value, so that
 473                            * (mask >> check) & 1 is a correct test for invalid
 474                            * values.
 475                            *
 476                            * R/Wi contains the type of the breakpoint /
 477                            * watchpoint, LENi contains the length of the watched
 478                            * data in the watchpoint case.
 479                            *
 480                            * The invalid values are:
 481                            * - LENi == 0x10 (undefined), so mask |= 0x0f00.
 482                            * - R/Wi == 0x10 (break on I/O reads or writes), so
 483                            *   mask |= 0x4444.
 484                            * - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
 485                            *   0x1110.
 486                            *
 487                            * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
 488                            *
 489                            * See the Intel Manual "System Programming Guide",
 490                            * 15.2.4
 491                            *
 492                            * Note that LENi == 0x10 is defined on x86_64 in long
 493                            * mode (i.e. even for 32-bit userspace software, but
 494                            * 64-bit kernel), so the x86_64 mask value is 0x5454.
 495                            * See the AMD manual no. 24593 (AMD64 System
 496                            * Programming)*/
 497
 498                           if(addr == (long) &dummy->u_debugreg[7]) {
 499                                   data &= ~DR_CONTROL_RESERVED;
 500                                   for(i=0; i<4; i++)
 501                                           if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
 502                                                   goto out_tsk;
 503                           }
 504
 505                           addr -= (long) &dummy->u_debugreg;
 506                           addr = addr >> 2;
 507                           child->thread.debugreg[addr] = data;
 508                           ret = 0;
 509                   }
 510                   break;
 511
 512         case PTRACE_SYSCALL:    /* continue and stop at next (return from) syscall */
 513         case PTRACE_CONT:       /* restart after signal. */
 514                 ret = -EIO;
 515                 if (!valid_signal(data))
 516                         break;
 517                 if (request == PTRACE_SYSCALL) {
 518                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 519                 }
 520                 else {
 521                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 522                 }
 523                 child->exit_code = data;
 524                 /* make sure the single step bit is not set. */
 525                 clear_singlestep(child);
 526                 wake_up_process(child);
 527                 ret = 0;
 528                 break;
 529
 530 /*
 531  * make the child exit.  Best I can do is send it a sigkill.
 532  * perhaps it should be put in the status that it wants to
 533  * exit.
 534  */
 535         case PTRACE_KILL:
 536                 ret = 0;
 537                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 538                         break;
 539                 child->exit_code = SIGKILL;
 540                 /* make sure the single step bit is not set. */
 541                 clear_singlestep(child);
 542                 wake_up_process(child);
 543                 break;
 544
 545         case PTRACE_SINGLESTEP: /* set the trap flag. */
 546                 ret = -EIO;
 547                 if (!valid_signal(data))
 548                         break;
 549                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 550                 set_singlestep(child);
 551                 child->exit_code = data;
 552                 /* give it a chance to run. */
 553                 wake_up_process(child);
 554                 ret = 0;
 555                 break;
 556
 557         case PTRACE_DETACH:
 558                 /* detach a process that was attached. */
 559                 ret = ptrace_detach(child, data);
 560                 break;
 561
 562         case PTRACE_GETREGS: { /* Get all gp regs from the child. */
 563                 if (!access_ok(VERIFY_WRITE, datap, FRAME_SIZE*sizeof(long))) {
 564                         ret = -EIO;
 565                         break;
 566                 }
 567                 for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
 568                         __put_user(getreg(child, i), datap);
 569                         datap++;
 570                 }
 571                 ret = 0;
 572                 break;
 573         }
 574
 575         case PTRACE_SETREGS: { /* Set all gp regs in the child. */
 576                 unsigned long tmp;
 577                 if (!access_ok(VERIFY_READ, datap, FRAME_SIZE*sizeof(long))) {
 578                         ret = -EIO;
 579                         break;
 580                 }
 581                 for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
 582                         __get_user(tmp, datap);
 583                         putreg(child, i, tmp);
 584                         datap++;
 585                 }
 586                 ret = 0;
 587                 break;
 588         }
 589
 590         case PTRACE_GETFPREGS: { /* Get the child FPU state. */
 591                 if (!access_ok(VERIFY_WRITE, datap,
 592                                sizeof(struct user_i387_struct))) {
 593                         ret = -EIO;
 594                         break;
 595                 }
 596                 ret = 0;
 597                 if (!tsk_used_math(child))
 598                         init_fpu(child);
 599                 get_fpregs((struct user_i387_struct __user *)data, child);
 600                 break;
 601         }
 602
 603         case PTRACE_SETFPREGS: { /* Set the child FPU state. */
 604                 if (!access_ok(VERIFY_READ, datap,
 605                                sizeof(struct user_i387_struct))) {
 606                         ret = -EIO;
 607                         break;
 608                 }
 609                 set_stopped_child_used_math(child);
 610                 set_fpregs(child, (struct user_i387_struct __user *)data);
 611                 ret = 0;
 612                 break;
 613         }
 614
 615         case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */
 616                 if (!access_ok(VERIFY_WRITE, datap,
 617                                sizeof(struct user_fxsr_struct))) {
 618                         ret = -EIO;
 619                         break;
 620                 }
 621                 if (!tsk_used_math(child))
 622                         init_fpu(child);
 623                 ret = get_fpxregs((struct user_fxsr_struct __user *)data, child);
 624                 break;
 625         }
 626
 627         case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */
 628                 if (!access_ok(VERIFY_READ, datap,
 629                                sizeof(struct user_fxsr_struct))) {
 630                         ret = -EIO;
 631                         break;
 632                 }
 633                 set_stopped_child_used_math(child);
 634                 ret = set_fpxregs(child, (struct user_fxsr_struct __user *)data);
 635                 break;
 636         }
 637
 638         case PTRACE_GET_THREAD_AREA:
 639                 ret = ptrace_get_thread_area(child, addr,
 640                                         (struct user_desc __user *) data);
 641                 break;
 642
 643         case PTRACE_SET_THREAD_AREA:
 644                 ret = ptrace_set_thread_area(child, addr,
 645                                         (struct user_desc __user *) data);
 646                 break;
 647
 648         default:
 649                 ret = ptrace_request(child, request, addr, data);
 650                 break;
 651         }
 652 out_tsk:
 653         put_task_struct(child);
 654 out:
 655         unlock_kernel();
 656         return ret;
 657 }
 658
 659 void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
 660 {
 661         struct siginfo info;
 662
 663         tsk->thread.trap_no = 1;
 664         tsk->thread.error_code = error_code;
 665
 666         memset(&info, 0, sizeof(info));
 667         info.si_signo = SIGTRAP;
 668         info.si_code = TRAP_BRKPT;
 669
 670         /* User-mode eip? */
 671         info.si_addr = user_mode(regs) ? (void __user *) regs->eip : NULL;
 672
 673         /* Send us the fakey SIGTRAP */
 674         force_sig_info(SIGTRAP, &info, tsk);
 675 }
 676
 677 /* notification of system call entry/exit
 678  * - triggered by current->work.syscall_trace
 679  */
 680 __attribute__((regparm(3)))
 681 void do_syscall_trace(struct pt_regs *regs, int entryexit)
 682 {
 683         /* do the secure computing check first */
 684         secure_computing(regs->orig_eax);
 685
 686         if (unlikely(current->audit_context) && entryexit)
 687                 audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
 688
 689         if (!(current->ptrace & PT_PTRACED))
 690                 goto out;
 691
 692         /* Fake a debug trap */
 693         if (test_thread_flag(TIF_SINGLESTEP))
 694                 send_sigtrap(current, regs, 0);
 695
 696         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 697                 goto out;
 698
 699         /* the 0x80 provides a way for the tracing parent to distinguish
 700            between a syscall stop and SIGTRAP delivery */
 701         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
 702
 703         /*
 704          * this isn't the same as continuing with a signal, but it will do
 705          * for normal use.  strace only continues with a signal if the
 706          * stopping signal is not SIGTRAP.  -brl
 707          */
 708         if (current->exit_code) {
 709                 send_sig(current->exit_code, current, 1);
 710                 current->exit_code = 0;
 711         }
 712  out:
 713         if (unlikely(current->audit_context) && !entryexit)
 714                 audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax,
 715                                     regs->ebx, regs->ecx, regs->edx, regs->esi);
 716
 717 }