arch/arm/kernel/ptrace.c

   1 /*
   2  *  linux/arch/arm/kernel/ptrace.c
   3  *
   4  *  By Ross Biro 1/23/92
   5  * edited by Linus Torvalds
   6  * ARM modifications Copyright (C) 2000 Russell King
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/kernel.h>
  13 #include <linux/sched.h>
  14 #include <linux/mm.h>
  15 #include <linux/smp.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/user.h>
  18 #include <linux/security.h>
  19 #include <linux/init.h>
  20 #include <linux/signal.h>
  21 #include <linux/uaccess.h>
  22
  23 #include <asm/pgtable.h>
  24 #include <asm/system.h>
  25 #include <asm/traps.h>
  26
  27 #include "ptrace.h"
  28
  29 #define REG_PC  15
  30 #define REG_PSR 16
  31 /*
  32  * does not yet catch signals sent when the child dies.
  33  * in exit.c or in signal.c.
  34  */
  35
  36 #if 0
  37 /*
  38  * Breakpoint SWI instruction: SWI &9F0001
  39  */
  40 #define BREAKINST_ARM   0xef9f0001
  41 #define BREAKINST_THUMB 0xdf00          /* fill this in later */
  42 #else
  43 /*
  44  * New breakpoints - use an undefined instruction.  The ARM architecture
  45  * reference manual guarantees that the following instruction space
  46  * will produce an undefined instruction exception on all CPUs:
  47  *
  48  *  ARM:   xxxx 0111 1111 xxxx xxxx xxxx 1111 xxxx
  49  *  Thumb: 1101 1110 xxxx xxxx
  50  */
  51 #define BREAKINST_ARM   0xe7f001f0
  52 #define BREAKINST_THUMB 0xde01
  53 #endif
  54
  55 /*
  56  * this routine will get a word off of the processes privileged stack.
  57  * the offset is how far from the base addr as stored in the THREAD.
  58  * this routine assumes that all the privileged stacks are in our
  59  * data space.
  60  */
  61 static inline long get_user_reg(struct task_struct *task, int offset)
  62 {
  63         return task_pt_regs(task)->uregs[offset];
  64 }
  65
  66 /*
  67  * this routine will put a word on the processes privileged stack.
  68  * the offset is how far from the base addr as stored in the THREAD.
  69  * this routine assumes that all the privileged stacks are in our
  70  * data space.
  71  */
  72 static inline int
  73 put_user_reg(struct task_struct *task, int offset, long data)
  74 {
  75         struct pt_regs newregs, *regs = task_pt_regs(task);
  76         int ret = -EINVAL;
  77
  78         newregs = *regs;
  79         newregs.uregs[offset] = data;
  80
  81         if (valid_user_regs(&newregs)) {
  82                 regs->uregs[offset] = data;
  83                 ret = 0;
  84         }
  85
  86         return ret;
  87 }
  88
  89 static inline int
  90 read_u32(struct task_struct *task, unsigned long addr, u32 *res)
  91 {
  92         int ret;
  93
  94         ret = access_process_vm(task, addr, res, sizeof(*res), 0);
  95
  96         return ret == sizeof(*res) ? 0 : -EIO;
  97 }
  98
  99 static inline int
 100 read_instr(struct task_struct *task, unsigned long addr, u32 *res)
 101 {
 102         int ret;
 103
 104         if (addr & 1) {
 105                 u16 val;
 106                 ret = access_process_vm(task, addr & ~1, &val, sizeof(val), 0);
 107                 ret = ret == sizeof(val) ? 0 : -EIO;
 108                 *res = val;
 109         } else {
 110                 u32 val;
 111                 ret = access_process_vm(task, addr & ~3, &val, sizeof(val), 0);
 112                 ret = ret == sizeof(val) ? 0 : -EIO;
 113                 *res = val;
 114         }
 115         return ret;
 116 }
 117
 118 /*
 119  * Get value of register `rn' (in the instruction)
 120  */
 121 static unsigned long
 122 ptrace_getrn(struct task_struct *child, unsigned long insn)
 123 {
 124         unsigned int reg = (insn >> 16) & 15;
 125         unsigned long val;
 126
 127         val = get_user_reg(child, reg);
 128         if (reg == 15)
 129                 val += 8;
 130
 131         return val;
 132 }
 133
 134 /*
 135  * Get value of operand 2 (in an ALU instruction)
 136  */
 137 static unsigned long
 138 ptrace_getaluop2(struct task_struct *child, unsigned long insn)
 139 {
 140         unsigned long val;
 141         int shift;
 142         int type;
 143
 144         if (insn & 1 << 25) {
 145                 val = insn & 255;
 146                 shift = (insn >> 8) & 15;
 147                 type = 3;
 148         } else {
 149                 val = get_user_reg (child, insn & 15);
 150
 151                 if (insn & (1 << 4))
 152                         shift = (int)get_user_reg (child, (insn >> 8) & 15);
 153                 else
 154                         shift = (insn >> 7) & 31;
 155
 156                 type = (insn >> 5) & 3;
 157         }
 158
 159         switch (type) {
 160         case 0: val <<= shift;  break;
 161         case 1: val >>= shift;  break;
 162         case 2:
 163                 val = (((signed long)val) >> shift);
 164                 break;
 165         case 3:
 166                 val = (val >> shift) | (val << (32 - shift));
 167                 break;
 168         }
 169         return val;
 170 }
 171
 172 /*
 173  * Get value of operand 2 (in a LDR instruction)
 174  */
 175 static unsigned long
 176 ptrace_getldrop2(struct task_struct *child, unsigned long insn)
 177 {
 178         unsigned long val;
 179         int shift;
 180         int type;
 181
 182         val = get_user_reg(child, insn & 15);
 183         shift = (insn >> 7) & 31;
 184         type = (insn >> 5) & 3;
 185
 186         switch (type) {
 187         case 0: val <<= shift;  break;
 188         case 1: val >>= shift;  break;
 189         case 2:
 190                 val = (((signed long)val) >> shift);
 191                 break;
 192         case 3:
 193                 val = (val >> shift) | (val << (32 - shift));
 194                 break;
 195         }
 196         return val;
 197 }
 198
 199 #define OP_MASK 0x01e00000
 200 #define OP_AND  0x00000000
 201 #define OP_EOR  0x00200000
 202 #define OP_SUB  0x00400000
 203 #define OP_RSB  0x00600000
 204 #define OP_ADD  0x00800000
 205 #define OP_ADC  0x00a00000
 206 #define OP_SBC  0x00c00000
 207 #define OP_RSC  0x00e00000
 208 #define OP_ORR  0x01800000
 209 #define OP_MOV  0x01a00000
 210 #define OP_BIC  0x01c00000
 211 #define OP_MVN  0x01e00000
 212
 213 static unsigned long
 214 get_branch_address(struct task_struct *child, unsigned long pc, unsigned long insn)
 215 {
 216         u32 alt = 0;
 217
 218         switch (insn & 0x0e000000) {
 219         case 0x00000000:
 220         case 0x02000000: {
 221                 /*
 222                  * data processing
 223                  */
 224                 long aluop1, aluop2, ccbit;
 225
 226                 if ((insn & 0x0fffffd0) == 0x012fff10) {
 227                         /*
 228                          * bx or blx
 229                          */
 230                         alt = get_user_reg(child, insn & 15);
 231                         break;
 232                 }
 233
 234
 235                 if ((insn & 0xf000) != 0xf000)
 236                         break;
 237
 238                 aluop1 = ptrace_getrn(child, insn);
 239                 aluop2 = ptrace_getaluop2(child, insn);
 240                 ccbit  = get_user_reg(child, REG_PSR) & PSR_C_BIT ? 1 : 0;
 241
 242                 switch (insn & OP_MASK) {
 243                 case OP_AND: alt = aluop1 & aluop2;             break;
 244                 case OP_EOR: alt = aluop1 ^ aluop2;             break;
 245                 case OP_SUB: alt = aluop1 - aluop2;             break;
 246                 case OP_RSB: alt = aluop2 - aluop1;             break;
 247                 case OP_ADD: alt = aluop1 + aluop2;             break;
 248                 case OP_ADC: alt = aluop1 + aluop2 + ccbit;     break;
 249                 case OP_SBC: alt = aluop1 - aluop2 + ccbit;     break;
 250                 case OP_RSC: alt = aluop2 - aluop1 + ccbit;     break;
 251                 case OP_ORR: alt = aluop1 | aluop2;             break;
 252                 case OP_MOV: alt = aluop2;                      break;
 253                 case OP_BIC: alt = aluop1 & ~aluop2;            break;
 254                 case OP_MVN: alt = ~aluop2;                     break;
 255                 }
 256                 break;
 257         }
 258
 259         case 0x04000000:
 260         case 0x06000000:
 261                 /*
 262                  * ldr
 263                  */
 264                 if ((insn & 0x0010f000) == 0x0010f000) {
 265                         unsigned long base;
 266
 267                         base = ptrace_getrn(child, insn);
 268                         if (insn & 1 << 24) {
 269                                 long aluop2;
 270
 271                                 if (insn & 0x02000000)
 272                                         aluop2 = ptrace_getldrop2(child, insn);
 273                                 else
 274                                         aluop2 = insn & 0xfff;
 275
 276                                 if (insn & 1 << 23)
 277                                         base += aluop2;
 278                                 else
 279                                         base -= aluop2;
 280                         }
 281                         read_u32(child, base, &alt);
 282                 }
 283                 break;
 284
 285         case 0x08000000:
 286                 /*
 287                  * ldm
 288                  */
 289                 if ((insn & 0x00108000) == 0x00108000) {
 290                         unsigned long base;
 291                         unsigned int nr_regs;
 292
 293                         if (insn & (1 << 23)) {
 294                                 nr_regs = hweight16(insn & 65535) << 2;
 295
 296                                 if (!(insn & (1 << 24)))
 297                                         nr_regs -= 4;
 298                         } else {
 299                                 if (insn & (1 << 24))
 300                                         nr_regs = -4;
 301                                 else
 302                                         nr_regs = 0;
 303                         }
 304
 305                         base = ptrace_getrn(child, insn);
 306
 307                         read_u32(child, base + nr_regs, &alt);
 308                         break;
 309                 }
 310                 break;
 311
 312         case 0x0a000000: {
 313                 /*
 314                  * bl or b
 315                  */
 316                 signed long displ;
 317                 /* It's a branch/branch link: instead of trying to
 318                  * figure out whether the branch will be taken or not,
 319                  * we'll put a breakpoint at both locations.  This is
 320                  * simpler, more reliable, and probably not a whole lot
 321                  * slower than the alternative approach of emulating the
 322                  * branch.
 323                  */
 324                 displ = (insn & 0x00ffffff) << 8;
 325                 displ = (displ >> 6) + 8;
 326                 if (displ != 0 && displ != 4)
 327                         alt = pc + displ;
 328             }
 329             break;
 330         }
 331
 332         return alt;
 333 }
 334
 335 static int
 336 swap_insn(struct task_struct *task, unsigned long addr,
 337           void *old_insn, void *new_insn, int size)
 338 {
 339         int ret;
 340
 341         ret = access_process_vm(task, addr, old_insn, size, 0);
 342         if (ret == size)
 343                 ret = access_process_vm(task, addr, new_insn, size, 1);
 344         return ret;
 345 }
 346
 347 static void
 348 add_breakpoint(struct task_struct *task, struct debug_info *dbg, unsigned long addr)
 349 {
 350         int nr = dbg->nsaved;
 351
 352         if (nr < 2) {
 353                 u32 new_insn = BREAKINST_ARM;
 354                 int res;
 355
 356                 res = swap_insn(task, addr, &dbg->bp[nr].insn, &new_insn, 4);
 357
 358                 if (res == 4) {
 359                         dbg->bp[nr].address = addr;
 360                         dbg->nsaved += 1;
 361                 }
 362         } else
 363                 printk(KERN_ERR "ptrace: too many breakpoints\n");
 364 }
 365
 366 /*
 367  * Clear one breakpoint in the user program.  We copy what the hardware
 368  * does and use bit 0 of the address to indicate whether this is a Thumb
 369  * breakpoint or an ARM breakpoint.
 370  */
 371 static void clear_breakpoint(struct task_struct *task, struct debug_entry *bp)
 372 {
 373         unsigned long addr = bp->address;
 374         union debug_insn old_insn;
 375         int ret;
 376
 377         if (addr & 1) {
 378                 ret = swap_insn(task, addr & ~1, &old_insn.thumb,
 379                                 &bp->insn.thumb, 2);
 380
 381                 if (ret != 2 || old_insn.thumb != BREAKINST_THUMB)
 382                         printk(KERN_ERR "%s:%d: corrupted Thumb breakpoint at "
 383                                 "0x%08lx (0x%04x)\n", task->comm,
 384                                 task_pid_nr(task), addr, old_insn.thumb);
 385         } else {
 386                 ret = swap_insn(task, addr & ~3, &old_insn.arm,
 387                                 &bp->insn.arm, 4);
 388
 389                 if (ret != 4 || old_insn.arm != BREAKINST_ARM)
 390                         printk(KERN_ERR "%s:%d: corrupted ARM breakpoint at "
 391                                 "0x%08lx (0x%08x)\n", task->comm,
 392                                 task_pid_nr(task), addr, old_insn.arm);
 393         }
 394 }
 395
 396 void ptrace_set_bpt(struct task_struct *child)
 397 {
 398         struct pt_regs *regs;
 399         unsigned long pc;
 400         u32 insn;
 401         int res;
 402
 403         regs = task_pt_regs(child);
 404         pc = instruction_pointer(regs);
 405
 406         if (thumb_mode(regs)) {
 407                 printk(KERN_WARNING "ptrace: can't handle thumb mode\n");
 408                 return;
 409         }
 410
 411         res = read_instr(child, pc, &insn);
 412         if (!res) {
 413                 struct debug_info *dbg = &child->thread.debug;
 414                 unsigned long alt;
 415
 416                 dbg->nsaved = 0;
 417
 418                 alt = get_branch_address(child, pc, insn);
 419                 if (alt)
 420                         add_breakpoint(child, dbg, alt);
 421
 422                 /*
 423                  * Note that we ignore the result of setting the above
 424                  * breakpoint since it may fail.  When it does, this is
 425                  * not so much an error, but a forewarning that we may
 426                  * be receiving a prefetch abort shortly.
 427                  *
 428                  * If we don't set this breakpoint here, then we can
 429                  * lose control of the thread during single stepping.
 430                  */
 431                 if (!alt || predicate(insn) != PREDICATE_ALWAYS)
 432                         add_breakpoint(child, dbg, pc + 4);
 433         }
 434 }
 435
 436 /*
 437  * Ensure no single-step breakpoint is pending.  Returns non-zero
 438  * value if child was being single-stepped.
 439  */
 440 void ptrace_cancel_bpt(struct task_struct *child)
 441 {
 442         int i, nsaved = child->thread.debug.nsaved;
 443
 444         child->thread.debug.nsaved = 0;
 445
 446         if (nsaved > 2) {
 447                 printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
 448                 nsaved = 2;
 449         }
 450
 451         for (i = 0; i < nsaved; i++)
 452                 clear_breakpoint(child, &child->thread.debug.bp[i]);
 453 }
 454
 455 /*
 456  * Called by kernel/ptrace.c when detaching..
 457  */
 458 void ptrace_disable(struct task_struct *child)
 459 {
 460         single_step_disable(child);
 461 }
 462
 463 /*
 464  * Handle hitting a breakpoint.
 465  */
 466 void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
 467 {
 468         siginfo_t info;
 469
 470         ptrace_cancel_bpt(tsk);
 471
 472         info.si_signo = SIGTRAP;
 473         info.si_errno = 0;
 474         info.si_code  = TRAP_BRKPT;
 475         info.si_addr  = (void __user *)instruction_pointer(regs);
 476
 477         force_sig_info(SIGTRAP, &info, tsk);
 478 }
 479
 480 static int break_trap(struct pt_regs *regs, unsigned int instr)
 481 {
 482         ptrace_break(current, regs);
 483         return 0;
 484 }
 485
 486 static struct undef_hook arm_break_hook = {
 487         .instr_mask     = 0x0fffffff,
 488         .instr_val      = 0x07f001f0,
 489         .cpsr_mask      = PSR_T_BIT,
 490         .cpsr_val       = 0,
 491         .fn             = break_trap,
 492 };
 493
 494 static struct undef_hook thumb_break_hook = {
 495         .instr_mask     = 0xffff,
 496         .instr_val      = 0xde01,
 497         .cpsr_mask      = PSR_T_BIT,
 498         .cpsr_val       = PSR_T_BIT,
 499         .fn             = break_trap,
 500 };
 501
 502 static int __init ptrace_break_init(void)
 503 {
 504         register_undef_hook(&arm_break_hook);
 505         register_undef_hook(&thumb_break_hook);
 506         return 0;
 507 }
 508
 509 core_initcall(ptrace_break_init);
 510
 511 /*
 512  * Read the word at offset "off" into the "struct user".  We
 513  * actually access the pt_regs stored on the kernel stack.
 514  */
 515 static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
 516                             unsigned long __user *ret)
 517 {
 518         unsigned long tmp;
 519
 520         if (off & 3 || off >= sizeof(struct user))
 521                 return -EIO;
 522
 523         tmp = 0;
 524         if (off < sizeof(struct pt_regs))
 525                 tmp = get_user_reg(tsk, off >> 2);
 526
 527         return put_user(tmp, ret);
 528 }
 529
 530 /*
 531  * Write the word at offset "off" into "struct user".  We
 532  * actually access the pt_regs stored on the kernel stack.
 533  */
 534 static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
 535                              unsigned long val)
 536 {
 537         if (off & 3 || off >= sizeof(struct user))
 538                 return -EIO;
 539
 540         if (off >= sizeof(struct pt_regs))
 541                 return 0;
 542
 543         return put_user_reg(tsk, off >> 2, val);
 544 }
 545
 546 /*
 547  * Get all user integer registers.
 548  */
 549 static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
 550 {
 551         struct pt_regs *regs = task_pt_regs(tsk);
 552
 553         return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
 554 }
 555
 556 /*
 557  * Set all user integer registers.
 558  */
 559 static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
 560 {
 561         struct pt_regs newregs;
 562         int ret;
 563
 564         ret = -EFAULT;
 565         if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
 566                 struct pt_regs *regs = task_pt_regs(tsk);
 567
 568                 ret = -EINVAL;
 569                 if (valid_user_regs(&newregs)) {
 570                         *regs = newregs;
 571                         ret = 0;
 572                 }
 573         }
 574
 575         return ret;
 576 }
 577
 578 /*
 579  * Get the child FPU state.
 580  */
 581 static int ptrace_getfpregs(struct task_struct *tsk, void __user *ufp)
 582 {
 583         return copy_to_user(ufp, &task_thread_info(tsk)->fpstate,
 584                             sizeof(struct user_fp)) ? -EFAULT : 0;
 585 }
 586
 587 /*
 588  * Set the child FPU state.
 589  */
 590 static int ptrace_setfpregs(struct task_struct *tsk, void __user *ufp)
 591 {
 592         struct thread_info *thread = task_thread_info(tsk);
 593         thread->used_cp[1] = thread->used_cp[2] = 1;
 594         return copy_from_user(&thread->fpstate, ufp,
 595                               sizeof(struct user_fp)) ? -EFAULT : 0;
 596 }
 597
 598 #ifdef CONFIG_IWMMXT
 599
 600 /*
 601  * Get the child iWMMXt state.
 602  */
 603 static int ptrace_getwmmxregs(struct task_struct *tsk, void __user *ufp)
 604 {
 605         struct thread_info *thread = task_thread_info(tsk);
 606
 607         if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
 608                 return -ENODATA;
 609         iwmmxt_task_disable(thread);  /* force it to ram */
 610         return copy_to_user(ufp, &thread->fpstate.iwmmxt, IWMMXT_SIZE)
 611                 ? -EFAULT : 0;
 612 }
 613
 614 /*
 615  * Set the child iWMMXt state.
 616  */
 617 static int ptrace_setwmmxregs(struct task_struct *tsk, void __user *ufp)
 618 {
 619         struct thread_info *thread = task_thread_info(tsk);
 620
 621         if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
 622                 return -EACCES;
 623         iwmmxt_task_release(thread);  /* force a reload */
 624         return copy_from_user(&thread->fpstate.iwmmxt, ufp, IWMMXT_SIZE)
 625                 ? -EFAULT : 0;
 626 }
 627
 628 #endif
 629
 630 #ifdef CONFIG_CRUNCH
 631 /*
 632  * Get the child Crunch state.
 633  */
 634 static int ptrace_getcrunchregs(struct task_struct *tsk, void __user *ufp)
 635 {
 636         struct thread_info *thread = task_thread_info(tsk);
 637
 638         crunch_task_disable(thread);  /* force it to ram */
 639         return copy_to_user(ufp, &thread->crunchstate, CRUNCH_SIZE)
 640                 ? -EFAULT : 0;
 641 }
 642
 643 /*
 644  * Set the child Crunch state.
 645  */
 646 static int ptrace_setcrunchregs(struct task_struct *tsk, void __user *ufp)
 647 {
 648         struct thread_info *thread = task_thread_info(tsk);
 649
 650         crunch_task_release(thread);  /* force a reload */
 651         return copy_from_user(&thread->crunchstate, ufp, CRUNCH_SIZE)
 652                 ? -EFAULT : 0;
 653 }
 654 #endif
 655
 656 #ifdef CONFIG_VFP
 657 /*
 658  * Get the child VFP state.
 659  */
 660 static int ptrace_getvfpregs(struct task_struct *tsk, void __user *data)
 661 {
 662         struct thread_info *thread = task_thread_info(tsk);
 663         union vfp_state *vfp = &thread->vfpstate;
 664         struct user_vfp __user *ufp = data;
 665
 666         vfp_sync_state(thread);
 667
 668         /* copy the floating point registers */
 669         if (copy_to_user(&ufp->fpregs, &vfp->hard.fpregs,
 670                          sizeof(vfp->hard.fpregs)))
 671                 return -EFAULT;
 672
 673         /* copy the status and control register */
 674         if (put_user(vfp->hard.fpscr, &ufp->fpscr))
 675                 return -EFAULT;
 676
 677         return 0;
 678 }
 679
 680 /*
 681  * Set the child VFP state.
 682  */
 683 static int ptrace_setvfpregs(struct task_struct *tsk, void __user *data)
 684 {
 685         struct thread_info *thread = task_thread_info(tsk);
 686         union vfp_state *vfp = &thread->vfpstate;
 687         struct user_vfp __user *ufp = data;
 688
 689         vfp_sync_state(thread);
 690
 691         /* copy the floating point registers */
 692         if (copy_from_user(&vfp->hard.fpregs, &ufp->fpregs,
 693                            sizeof(vfp->hard.fpregs)))
 694                 return -EFAULT;
 695
 696         /* copy the status and control register */
 697         if (get_user(vfp->hard.fpscr, &ufp->fpscr))
 698                 return -EFAULT;
 699
 700         return 0;
 701 }
 702 #endif
 703
 704 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 705 {
 706         int ret;
 707
 708         switch (request) {
 709                 /*
 710                  * read word at location "addr" in the child process.
 711                  */
 712                 case PTRACE_PEEKTEXT:
 713                 case PTRACE_PEEKDATA:
 714                         ret = generic_ptrace_peekdata(child, addr, data);
 715                         break;
 716
 717                 case PTRACE_PEEKUSR:
 718                         ret = ptrace_read_user(child, addr, (unsigned long __user *)data);
 719                         break;
 720
 721                 /*
 722                  * write the word at location addr.
 723                  */
 724                 case PTRACE_POKETEXT:
 725                 case PTRACE_POKEDATA:
 726                         ret = generic_ptrace_pokedata(child, addr, data);
 727                         break;
 728
 729                 case PTRACE_POKEUSR:
 730                         ret = ptrace_write_user(child, addr, data);
 731                         break;
 732
 733                 /*
 734                  * continue/restart and stop at next (return from) syscall
 735                  */
 736                 case PTRACE_SYSCALL:
 737                 case PTRACE_CONT:
 738                         ret = -EIO;
 739                         if (!valid_signal(data))
 740                                 break;
 741                         if (request == PTRACE_SYSCALL)
 742                                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 743                         else
 744                                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 745                         child->exit_code = data;
 746                         single_step_disable(child);
 747                         wake_up_process(child);
 748                         ret = 0;
 749                         break;
 750
 751                 /*
 752                  * make the child exit.  Best I can do is send it a sigkill.
 753                  * perhaps it should be put in the status that it wants to
 754                  * exit.
 755                  */
 756                 case PTRACE_KILL:
 757                         single_step_disable(child);
 758                         if (child->exit_state != EXIT_ZOMBIE) {
 759                                 child->exit_code = SIGKILL;
 760                                 wake_up_process(child);
 761                         }
 762                         ret = 0;
 763                         break;
 764
 765                 /*
 766                  * execute single instruction.
 767                  */
 768                 case PTRACE_SINGLESTEP:
 769                         ret = -EIO;
 770                         if (!valid_signal(data))
 771                                 break;
 772                         single_step_enable(child);
 773                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 774                         child->exit_code = data;
 775                         /* give it a chance to run. */
 776                         wake_up_process(child);
 777                         ret = 0;
 778                         break;
 779
 780                 case PTRACE_GETREGS:
 781                         ret = ptrace_getregs(child, (void __user *)data);
 782                         break;
 783
 784                 case PTRACE_SETREGS:
 785                         ret = ptrace_setregs(child, (void __user *)data);
 786                         break;
 787
 788                 case PTRACE_GETFPREGS:
 789                         ret = ptrace_getfpregs(child, (void __user *)data);
 790                         break;
 791
 792                 case PTRACE_SETFPREGS:
 793                         ret = ptrace_setfpregs(child, (void __user *)data);
 794                         break;
 795
 796 #ifdef CONFIG_IWMMXT
 797                 case PTRACE_GETWMMXREGS:
 798                         ret = ptrace_getwmmxregs(child, (void __user *)data);
 799                         break;
 800
 801                 case PTRACE_SETWMMXREGS:
 802                         ret = ptrace_setwmmxregs(child, (void __user *)data);
 803                         break;
 804 #endif
 805
 806                 case PTRACE_GET_THREAD_AREA:
 807                         ret = put_user(task_thread_info(child)->tp_value,
 808                                        (unsigned long __user *) data);
 809                         break;
 810
 811                 case PTRACE_SET_SYSCALL:
 812                         task_thread_info(child)->syscall = data;
 813                         ret = 0;
 814                         break;
 815
 816 #ifdef CONFIG_CRUNCH
 817                 case PTRACE_GETCRUNCHREGS:
 818                         ret = ptrace_getcrunchregs(child, (void __user *)data);
 819                         break;
 820
 821                 case PTRACE_SETCRUNCHREGS:
 822                         ret = ptrace_setcrunchregs(child, (void __user *)data);
 823                         break;
 824 #endif
 825
 826 #ifdef CONFIG_VFP
 827                 case PTRACE_GETVFPREGS:
 828                         ret = ptrace_getvfpregs(child, (void __user *)data);
 829                         break;
 830
 831                 case PTRACE_SETVFPREGS:
 832                         ret = ptrace_setvfpregs(child, (void __user *)data);
 833                         break;
 834 #endif
 835
 836                 default:
 837                         ret = ptrace_request(child, request, addr, data);
 838                         break;
 839         }
 840
 841         return ret;
 842 }
 843
 844 asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 845 {
 846         unsigned long ip;
 847
 848         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 849                 return scno;
 850         if (!(current->ptrace & PT_PTRACED))
 851                 return scno;
 852
 853         /*
 854          * Save IP.  IP is used to denote syscall entry/exit:
 855          *  IP = 0 -> entry, = 1 -> exit
 856          */
 857         ip = regs->ARM_ip;
 858         regs->ARM_ip = why;
 859
 860         current_thread_info()->syscall = scno;
 861
 862         /* the 0x80 provides a way for the tracing parent to distinguish
 863            between a syscall stop and SIGTRAP delivery */
 864         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 865                                  ? 0x80 : 0));
 866         /*
 867          * this isn't the same as continuing with a signal, but it will do
 868          * for normal use.  strace only continues with a signal if the
 869          * stopping signal is not SIGTRAP.  -brl
 870          */
 871         if (current->exit_code) {
 872                 send_sig(current->exit_code, current, 1);
 873                 current->exit_code = 0;
 874         }
 875         regs->ARM_ip = ip;
 876
 877         return current_thread_info()->syscall;
 878 }