arch/s390/kernel/ptrace.c

   1 /*
   2  *  arch/s390/kernel/ptrace.c
   3  *
   4  *  S390 version
   5  *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
   6  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
   7  *               Martin Schwidefsky (schwidefsky@de.ibm.com)
   8  *
   9  *  Based on PowerPC version
  10  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  11  *
  12  *  Derived from "arch/m68k/kernel/ptrace.c"
  13  *  Copyright (C) 1994 by Hamish Macdonald
  14  *  Taken from linux/kernel/ptrace.c and modified for M680x0.
  15  *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
  16  *
  17  * Modified by Cort Dougan (cort@cs.nmt.edu)
  18  *
  19  *
  20  * This file is subject to the terms and conditions of the GNU General
  21  * Public License.  See the file README.legal in the main directory of
  22  * this archive for more details.
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/sched.h>
  27 #include <linux/mm.h>
  28 #include <linux/smp.h>
  29 #include <linux/smp_lock.h>
  30 #include <linux/errno.h>
  31 #include <linux/ptrace.h>
  32 #include <linux/user.h>
  33 #include <linux/security.h>
  34 #include <linux/audit.h>
  35
  36 #include <asm/segment.h>
  37 #include <asm/page.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/pgalloc.h>
  40 #include <asm/system.h>
  41 #include <asm/uaccess.h>
  42
  43 #ifdef CONFIG_S390_SUPPORT
  44 #include "compat_ptrace.h"
  45 #endif
  46
  47 static void
  48 FixPerRegisters(struct task_struct *task)
  49 {
  50         struct pt_regs *regs;
  51         per_struct *per_info;
  52
  53         regs = __KSTK_PTREGS(task);
  54         per_info = (per_struct *) &task->thread.per_info;
  55         per_info->control_regs.bits.em_instruction_fetch =
  56                 per_info->single_step | per_info->instruction_fetch;
  57
  58         if (per_info->single_step) {
  59                 per_info->control_regs.bits.starting_addr = 0;
  60 #ifdef CONFIG_S390_SUPPORT
  61                 if (test_thread_flag(TIF_31BIT))
  62                         per_info->control_regs.bits.ending_addr = 0x7fffffffUL;
  63                 else
  64 #endif
  65                         per_info->control_regs.bits.ending_addr = PSW_ADDR_INSN;
  66         } else {
  67                 per_info->control_regs.bits.starting_addr =
  68                         per_info->starting_addr;
  69                 per_info->control_regs.bits.ending_addr =
  70                         per_info->ending_addr;
  71         }
  72         /*
  73          * if any of the control reg tracing bits are on
  74          * we switch on per in the psw
  75          */
  76         if (per_info->control_regs.words.cr[0] & PER_EM_MASK)
  77                 regs->psw.mask |= PSW_MASK_PER;
  78         else
  79                 regs->psw.mask &= ~PSW_MASK_PER;
  80
  81         if (per_info->control_regs.bits.em_storage_alteration)
  82                 per_info->control_regs.bits.storage_alt_space_ctl = 1;
  83         else
  84                 per_info->control_regs.bits.storage_alt_space_ctl = 0;
  85 }
  86
  87 void
  88 set_single_step(struct task_struct *task)
  89 {
  90         task->thread.per_info.single_step = 1;
  91         FixPerRegisters(task);
  92 }
  93
  94 void
  95 clear_single_step(struct task_struct *task)
  96 {
  97         task->thread.per_info.single_step = 0;
  98         FixPerRegisters(task);
  99 }
 100
 101 /*
 102  * Called by kernel/ptrace.c when detaching..
 103  *
 104  * Make sure single step bits etc are not set.
 105  */
 106 void
 107 ptrace_disable(struct task_struct *child)
 108 {
 109         /* make sure the single step bit is not set. */
 110         clear_single_step(child);
 111 }
 112
 113 #ifndef CONFIG_ARCH_S390X
 114 # define __ADDR_MASK 3
 115 #else
 116 # define __ADDR_MASK 7
 117 #endif
 118
 119 /*
 120  * Read the word at offset addr from the user area of a process. The
 121  * trouble here is that the information is littered over different
 122  * locations. The process registers are found on the kernel stack,
 123  * the floating point stuff and the trace settings are stored in
 124  * the task structure. In addition the different structures in
 125  * struct user contain pad bytes that should be read as zeroes.
 126  * Lovely...
 127  */
 128 static int
 129 peek_user(struct task_struct *child, addr_t addr, addr_t data)
 130 {
 131         struct user *dummy = NULL;
 132         addr_t offset, tmp;
 133
 134         /*
 135          * Stupid gdb peeks/pokes the access registers in 64 bit with
 136          * an alignment of 4. Programmers from hell...
 137          */
 138         if ((addr & 3) || addr > sizeof(struct user) - __ADDR_MASK)
 139                 return -EIO;
 140
 141         if (addr < (addr_t) &dummy->regs.acrs) {
 142                 /*
 143                  * psw and gprs are stored on the stack
 144                  */
 145                 tmp = *(addr_t *)((addr_t) &__KSTK_PTREGS(child)->psw + addr);
 146                 if (addr == (addr_t) &dummy->regs.psw.mask)
 147                         /* Remove per bit from user psw. */
 148                         tmp &= ~PSW_MASK_PER;
 149
 150         } else if (addr < (addr_t) &dummy->regs.orig_gpr2) {
 151                 /*
 152                  * access registers are stored in the thread structure
 153                  */
 154                 offset = addr - (addr_t) &dummy->regs.acrs;
 155                 tmp = *(addr_t *)((addr_t) &child->thread.acrs + offset);
 156
 157         } else if (addr == (addr_t) &dummy->regs.orig_gpr2) {
 158                 /*
 159                  * orig_gpr2 is stored on the kernel stack
 160                  */
 161                 tmp = (addr_t) __KSTK_PTREGS(child)->orig_gpr2;
 162
 163         } else if (addr < (addr_t) (&dummy->regs.fp_regs + 1)) {
 164                 /*
 165                  * floating point regs. are stored in the thread structure
 166                  */
 167                 offset = addr - (addr_t) &dummy->regs.fp_regs;
 168                 tmp = *(addr_t *)((addr_t) &child->thread.fp_regs + offset);
 169
 170         } else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
 171                 /*
 172                  * per_info is found in the thread structure
 173                  */
 174                 offset = addr - (addr_t) &dummy->regs.per_info;
 175                 tmp = *(addr_t *)((addr_t) &child->thread.per_info + offset);
 176
 177         } else
 178                 tmp = 0;
 179
 180         return put_user(tmp, (addr_t __user *) data);
 181 }
 182
 183 /*
 184  * Write a word to the user area of a process at location addr. This
 185  * operation does have an additional problem compared to peek_user.
 186  * Stores to the program status word and on the floating point
 187  * control register needs to get checked for validity.
 188  */
 189 static int
 190 poke_user(struct task_struct *child, addr_t addr, addr_t data)
 191 {
 192         struct user *dummy = NULL;
 193         addr_t offset;
 194
 195         /*
 196          * Stupid gdb peeks/pokes the access registers in 64 bit with
 197          * an alignment of 4. Programmers from hell indeed...
 198          */
 199         if ((addr & 3) || addr > sizeof(struct user) - __ADDR_MASK)
 200                 return -EIO;
 201
 202         if (addr < (addr_t) &dummy->regs.acrs) {
 203                 /*
 204                  * psw and gprs are stored on the stack
 205                  */
 206                 if (addr == (addr_t) &dummy->regs.psw.mask &&
 207 #ifdef CONFIG_S390_SUPPORT
 208                     data != PSW_MASK_MERGE(PSW_USER32_BITS, data) &&
 209 #endif
 210                     data != PSW_MASK_MERGE(PSW_USER_BITS, data))
 211                         /* Invalid psw mask. */
 212                         return -EINVAL;
 213 #ifndef CONFIG_ARCH_S390X
 214                 if (addr == (addr_t) &dummy->regs.psw.addr)
 215                         /* I'd like to reject addresses without the
 216                            high order bit but older gdb's rely on it */
 217                         data |= PSW_ADDR_AMODE;
 218 #endif
 219                 *(addr_t *)((addr_t) &__KSTK_PTREGS(child)->psw + addr) = data;
 220
 221         } else if (addr < (addr_t) (&dummy->regs.orig_gpr2)) {
 222                 /*
 223                  * access registers are stored in the thread structure
 224                  */
 225                 offset = addr - (addr_t) &dummy->regs.acrs;
 226                 *(addr_t *)((addr_t) &child->thread.acrs + offset) = data;
 227
 228         } else if (addr == (addr_t) &dummy->regs.orig_gpr2) {
 229                 /*
 230                  * orig_gpr2 is stored on the kernel stack
 231                  */
 232                 __KSTK_PTREGS(child)->orig_gpr2 = data;
 233
 234         } else if (addr < (addr_t) (&dummy->regs.fp_regs + 1)) {
 235                 /*
 236                  * floating point regs. are stored in the thread structure
 237                  */
 238                 if (addr == (addr_t) &dummy->regs.fp_regs.fpc &&
 239                     (data & ~FPC_VALID_MASK) != 0)
 240                         return -EINVAL;
 241                 offset = addr - (addr_t) &dummy->regs.fp_regs;
 242                 *(addr_t *)((addr_t) &child->thread.fp_regs + offset) = data;
 243
 244         } else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
 245                 /*
 246                  * per_info is found in the thread structure
 247                  */
 248                 offset = addr - (addr_t) &dummy->regs.per_info;
 249                 *(addr_t *)((addr_t) &child->thread.per_info + offset) = data;
 250
 251         }
 252
 253         FixPerRegisters(child);
 254         return 0;
 255 }
 256
 257 static int
 258 do_ptrace_normal(struct task_struct *child, long request, long addr, long data)
 259 {
 260         unsigned long tmp;
 261         ptrace_area parea;
 262         int copied, ret;
 263
 264         switch (request) {
 265         case PTRACE_PEEKTEXT:
 266         case PTRACE_PEEKDATA:
 267                 /* Remove high order bit from address (only for 31 bit). */
 268                 addr &= PSW_ADDR_INSN;
 269                 /* read word at location addr. */
 270                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 271                 if (copied != sizeof(tmp))
 272                         return -EIO;
 273                 return put_user(tmp, (unsigned long __user *) data);
 274
 275         case PTRACE_PEEKUSR:
 276                 /* read the word at location addr in the USER area. */
 277                 return peek_user(child, addr, data);
 278
 279         case PTRACE_POKETEXT:
 280         case PTRACE_POKEDATA:
 281                 /* Remove high order bit from address (only for 31 bit). */
 282                 addr &= PSW_ADDR_INSN;
 283                 /* write the word at location addr. */
 284                 copied = access_process_vm(child, addr, &data, sizeof(data),1);
 285                 if (copied != sizeof(data))
 286                         return -EIO;
 287                 return 0;
 288
 289         case PTRACE_POKEUSR:
 290                 /* write the word at location addr in the USER area */
 291                 return poke_user(child, addr, data);
 292
 293         case PTRACE_PEEKUSR_AREA:
 294         case PTRACE_POKEUSR_AREA:
 295                 if (copy_from_user(&parea, (void __user *) addr,
 296                                                         sizeof(parea)))
 297                         return -EFAULT;
 298                 addr = parea.kernel_addr;
 299                 data = parea.process_addr;
 300                 copied = 0;
 301                 while (copied < parea.len) {
 302                         if (request == PTRACE_PEEKUSR_AREA)
 303                                 ret = peek_user(child, addr, data);
 304                         else {
 305                                 addr_t tmp;
 306                                 if (get_user (tmp, (addr_t __user *) data))
 307                                         return -EFAULT;
 308                                 ret = poke_user(child, addr, tmp);
 309                         }
 310                         if (ret)
 311                                 return ret;
 312                         addr += sizeof(unsigned long);
 313                         data += sizeof(unsigned long);
 314                         copied += sizeof(unsigned long);
 315                 }
 316                 return 0;
 317         }
 318         return ptrace_request(child, request, addr, data);
 319 }
 320
 321 #ifdef CONFIG_S390_SUPPORT
 322 /*
 323  * Now the fun part starts... a 31 bit program running in the
 324  * 31 bit emulation tracing another program. PTRACE_PEEKTEXT,
 325  * PTRACE_PEEKDATA, PTRACE_POKETEXT and PTRACE_POKEDATA are easy
 326  * to handle, the difference to the 64 bit versions of the requests
 327  * is that the access is done in multiples of 4 byte instead of
 328  * 8 bytes (sizeof(unsigned long) on 31/64 bit).
 329  * The ugly part are PTRACE_PEEKUSR, PTRACE_PEEKUSR_AREA,
 330  * PTRACE_POKEUSR and PTRACE_POKEUSR_AREA. If the traced program
 331  * is a 31 bit program too, the content of struct user can be
 332  * emulated. A 31 bit program peeking into the struct user of
 333  * a 64 bit program is a no-no.
 334  */
 335
 336 /*
 337  * Same as peek_user but for a 31 bit program.
 338  */
 339 static int
 340 peek_user_emu31(struct task_struct *child, addr_t addr, addr_t data)
 341 {
 342         struct user32 *dummy32 = NULL;
 343         per_struct32 *dummy_per32 = NULL;
 344         addr_t offset;
 345         __u32 tmp;
 346
 347         if (!test_thread_flag(TIF_31BIT) ||
 348             (addr & 3) || addr > sizeof(struct user) - 3)
 349                 return -EIO;
 350
 351         if (addr < (addr_t) &dummy32->regs.acrs) {
 352                 /*
 353                  * psw and gprs are stored on the stack
 354                  */
 355                 if (addr == (addr_t) &dummy32->regs.psw.mask) {
 356                         /* Fake a 31 bit psw mask. */
 357                         tmp = (__u32)(__KSTK_PTREGS(child)->psw.mask >> 32);
 358                         tmp = PSW32_MASK_MERGE(PSW32_USER_BITS, tmp);
 359                 } else if (addr == (addr_t) &dummy32->regs.psw.addr) {
 360                         /* Fake a 31 bit psw address. */
 361                         tmp = (__u32) __KSTK_PTREGS(child)->psw.addr |
 362                                 PSW32_ADDR_AMODE31;
 363                 } else {
 364                         /* gpr 0-15 */
 365                         tmp = *(__u32 *)((addr_t) &__KSTK_PTREGS(child)->psw +
 366                                          addr*2 + 4);
 367                 }
 368         } else if (addr < (addr_t) (&dummy32->regs.orig_gpr2)) {
 369                 /*
 370                  * access registers are stored in the thread structure
 371                  */
 372                 offset = addr - (addr_t) &dummy32->regs.acrs;
 373                 tmp = *(__u32*)((addr_t) &child->thread.acrs + offset);
 374
 375         } else if (addr == (addr_t) (&dummy32->regs.orig_gpr2)) {
 376                 /*
 377                  * orig_gpr2 is stored on the kernel stack
 378                  */
 379                 tmp = *(__u32*)((addr_t) &__KSTK_PTREGS(child)->orig_gpr2 + 4);
 380
 381         } else if (addr < (addr_t) (&dummy32->regs.fp_regs + 1)) {
 382                 /*
 383                  * floating point regs. are stored in the thread structure
 384                  */
 385                 offset = addr - (addr_t) &dummy32->regs.fp_regs;
 386                 tmp = *(__u32 *)((addr_t) &child->thread.fp_regs + offset);
 387
 388         } else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {
 389                 /*
 390                  * per_info is found in the thread structure
 391                  */
 392                 offset = addr - (addr_t) &dummy32->regs.per_info;
 393                 /* This is magic. See per_struct and per_struct32. */
 394                 if ((offset >= (addr_t) &dummy_per32->control_regs &&
 395                      offset < (addr_t) (&dummy_per32->control_regs + 1)) ||
 396                     (offset >= (addr_t) &dummy_per32->starting_addr &&
 397                      offset <= (addr_t) &dummy_per32->ending_addr) ||
 398                     offset == (addr_t) &dummy_per32->lowcore.words.address)
 399                         offset = offset*2 + 4;
 400                 else
 401                         offset = offset*2;
 402                 tmp = *(__u32 *)((addr_t) &child->thread.per_info + offset);
 403
 404         } else
 405                 tmp = 0;
 406
 407         return put_user(tmp, (__u32 __user *) data);
 408 }
 409
 410 /*
 411  * Same as poke_user but for a 31 bit program.
 412  */
 413 static int
 414 poke_user_emu31(struct task_struct *child, addr_t addr, addr_t data)
 415 {
 416         struct user32 *dummy32 = NULL;
 417         per_struct32 *dummy_per32 = NULL;
 418         addr_t offset;
 419         __u32 tmp;
 420
 421         if (!test_thread_flag(TIF_31BIT) ||
 422             (addr & 3) || addr > sizeof(struct user32) - 3)
 423                 return -EIO;
 424
 425         tmp = (__u32) data;
 426
 427         if (addr < (addr_t) &dummy32->regs.acrs) {
 428                 /*
 429                  * psw, gprs, acrs and orig_gpr2 are stored on the stack
 430                  */
 431                 if (addr == (addr_t) &dummy32->regs.psw.mask) {
 432                         /* Build a 64 bit psw mask from 31 bit mask. */
 433                         if (tmp != PSW32_MASK_MERGE(PSW32_USER_BITS, tmp))
 434                                 /* Invalid psw mask. */
 435                                 return -EINVAL;
 436                         __KSTK_PTREGS(child)->psw.mask =
 437                                 PSW_MASK_MERGE(PSW_USER32_BITS, (__u64) tmp << 32);
 438                 } else if (addr == (addr_t) &dummy32->regs.psw.addr) {
 439                         /* Build a 64 bit psw address from 31 bit address. */
 440                         __KSTK_PTREGS(child)->psw.addr =
 441                                 (__u64) tmp & PSW32_ADDR_INSN;
 442                 } else {
 443                         /* gpr 0-15 */
 444                         *(__u32*)((addr_t) &__KSTK_PTREGS(child)->psw
 445                                   + addr*2 + 4) = tmp;
 446                 }
 447         } else if (addr < (addr_t) (&dummy32->regs.orig_gpr2)) {
 448                 /*
 449                  * access registers are stored in the thread structure
 450                  */
 451                 offset = addr - (addr_t) &dummy32->regs.acrs;
 452                 *(__u32*)((addr_t) &child->thread.acrs + offset) = tmp;
 453
 454         } else if (addr == (addr_t) (&dummy32->regs.orig_gpr2)) {
 455                 /*
 456                  * orig_gpr2 is stored on the kernel stack
 457                  */
 458                 *(__u32*)((addr_t) &__KSTK_PTREGS(child)->orig_gpr2 + 4) = tmp;
 459
 460         } else if (addr < (addr_t) (&dummy32->regs.fp_regs + 1)) {
 461                 /*
 462                  * floating point regs. are stored in the thread structure
 463                  */
 464                 if (addr == (addr_t) &dummy32->regs.fp_regs.fpc &&
 465                     (tmp & ~FPC_VALID_MASK) != 0)
 466                         /* Invalid floating point control. */
 467                         return -EINVAL;
 468                 offset = addr - (addr_t) &dummy32->regs.fp_regs;
 469                 *(__u32 *)((addr_t) &child->thread.fp_regs + offset) = tmp;
 470
 471         } else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {
 472                 /*
 473                  * per_info is found in the thread structure.
 474                  */
 475                 offset = addr - (addr_t) &dummy32->regs.per_info;
 476                 /*
 477                  * This is magic. See per_struct and per_struct32.
 478                  * By incident the offsets in per_struct are exactly
 479                  * twice the offsets in per_struct32 for all fields.
 480                  * The 8 byte fields need special handling though,
 481                  * because the second half (bytes 4-7) is needed and
 482                  * not the first half.
 483                  */
 484                 if ((offset >= (addr_t) &dummy_per32->control_regs &&
 485                      offset < (addr_t) (&dummy_per32->control_regs + 1)) ||
 486                     (offset >= (addr_t) &dummy_per32->starting_addr &&
 487                      offset <= (addr_t) &dummy_per32->ending_addr) ||
 488                     offset == (addr_t) &dummy_per32->lowcore.words.address)
 489                         offset = offset*2 + 4;
 490                 else
 491                         offset = offset*2;
 492                 *(__u32 *)((addr_t) &child->thread.per_info + offset) = tmp;
 493
 494         }
 495
 496         FixPerRegisters(child);
 497         return 0;
 498 }
 499
 500 static int
 501 do_ptrace_emu31(struct task_struct *child, long request, long addr, long data)
 502 {
 503         unsigned int tmp;  /* 4 bytes !! */
 504         ptrace_area_emu31 parea;
 505         int copied, ret;
 506
 507         switch (request) {
 508         case PTRACE_PEEKTEXT:
 509         case PTRACE_PEEKDATA:
 510                 /* read word at location addr. */
 511                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 512                 if (copied != sizeof(tmp))
 513                         return -EIO;
 514                 return put_user(tmp, (unsigned int __user *) data);
 515
 516         case PTRACE_PEEKUSR:
 517                 /* read the word at location addr in the USER area. */
 518                 return peek_user_emu31(child, addr, data);
 519
 520         case PTRACE_POKETEXT:
 521         case PTRACE_POKEDATA:
 522                 /* write the word at location addr. */
 523                 tmp = data;
 524                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 1);
 525                 if (copied != sizeof(tmp))
 526                         return -EIO;
 527                 return 0;
 528
 529         case PTRACE_POKEUSR:
 530                 /* write the word at location addr in the USER area */
 531                 return poke_user_emu31(child, addr, data);
 532
 533         case PTRACE_PEEKUSR_AREA:
 534         case PTRACE_POKEUSR_AREA:
 535                 if (copy_from_user(&parea, (void __user *) addr,
 536                                                         sizeof(parea)))
 537                         return -EFAULT;
 538                 addr = parea.kernel_addr;
 539                 data = parea.process_addr;
 540                 copied = 0;
 541                 while (copied < parea.len) {
 542                         if (request == PTRACE_PEEKUSR_AREA)
 543                                 ret = peek_user_emu31(child, addr, data);
 544                         else {
 545                                 __u32 tmp;
 546                                 if (get_user (tmp, (__u32 __user *) data))
 547                                         return -EFAULT;
 548                                 ret = poke_user_emu31(child, addr, tmp);
 549                         }
 550                         if (ret)
 551                                 return ret;
 552                         addr += sizeof(unsigned int);
 553                         data += sizeof(unsigned int);
 554                         copied += sizeof(unsigned int);
 555                 }
 556                 return 0;
 557         case PTRACE_GETEVENTMSG:
 558                 return put_user((__u32) child->ptrace_message,
 559                                 (unsigned int __user *) data);
 560         case PTRACE_GETSIGINFO:
 561                 if (child->last_siginfo == NULL)
 562                         return -EINVAL;
 563                 return copy_siginfo_to_user32((compat_siginfo_t __user *) data,
 564                                               child->last_siginfo);
 565         case PTRACE_SETSIGINFO:
 566                 if (child->last_siginfo == NULL)
 567                         return -EINVAL;
 568                 return copy_siginfo_from_user32(child->last_siginfo,
 569                                                 (compat_siginfo_t __user *) data);
 570         }
 571         return ptrace_request(child, request, addr, data);
 572 }
 573 #endif
 574
 575 #define PT32_IEEE_IP 0x13c
 576
 577 static int
 578 do_ptrace(struct task_struct *child, long request, long addr, long data)
 579 {
 580         int ret;
 581
 582         if (request == PTRACE_ATTACH)
 583                 return ptrace_attach(child);
 584
 585         /*
 586          * Special cases to get/store the ieee instructions pointer.
 587          */
 588         if (child == current) {
 589                 if (request == PTRACE_PEEKUSR && addr == PT_IEEE_IP)
 590                         return peek_user(child, addr, data);
 591                 if (request == PTRACE_POKEUSR && addr == PT_IEEE_IP)
 592                         return poke_user(child, addr, data);
 593 #ifdef CONFIG_S390_SUPPORT
 594                 if (request == PTRACE_PEEKUSR &&
 595                     addr == PT32_IEEE_IP && test_thread_flag(TIF_31BIT))
 596                         return peek_user_emu31(child, addr, data);
 597                 if (request == PTRACE_POKEUSR &&
 598                     addr == PT32_IEEE_IP && test_thread_flag(TIF_31BIT))
 599                         return poke_user_emu31(child, addr, data);
 600 #endif
 601         }
 602
 603         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 604         if (ret < 0)
 605                 return ret;
 606
 607         switch (request) {
 608         case PTRACE_SYSCALL:
 609                 /* continue and stop at next (return from) syscall */
 610         case PTRACE_CONT:
 611                 /* restart after signal. */
 612                 if ((unsigned long) data >= _NSIG)
 613                         return -EIO;
 614                 if (request == PTRACE_SYSCALL)
 615                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 616                 else
 617                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 618                 child->exit_code = data;
 619                 /* make sure the single step bit is not set. */
 620                 clear_single_step(child);
 621                 wake_up_process(child);
 622                 return 0;
 623
 624         case PTRACE_KILL:
 625                 /*
 626                  * make the child exit.  Best I can do is send it a sigkill.
 627                  * perhaps it should be put in the status that it wants to
 628                  * exit.
 629                  */
 630                 if (child->exit_state == EXIT_ZOMBIE) /* already dead */
 631                         return 0;
 632                 child->exit_code = SIGKILL;
 633                 /* make sure the single step bit is not set. */
 634                 clear_single_step(child);
 635                 wake_up_process(child);
 636                 return 0;
 637
 638         case PTRACE_SINGLESTEP:
 639                 /* set the trap flag. */
 640                 if ((unsigned long) data >= _NSIG)
 641                         return -EIO;
 642                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 643                 child->exit_code = data;
 644                 if (data)
 645                         set_tsk_thread_flag(child, TIF_SINGLE_STEP);
 646                 else
 647                         set_single_step(child);
 648                 /* give it a chance to run. */
 649                 wake_up_process(child);
 650                 return 0;
 651
 652         case PTRACE_DETACH:
 653                 /* detach a process that was attached. */
 654                 return ptrace_detach(child, data);
 655
 656
 657         /* Do requests that differ for 31/64 bit */
 658         default:
 659 #ifdef CONFIG_S390_SUPPORT
 660                 if (test_thread_flag(TIF_31BIT))
 661                         return do_ptrace_emu31(child, request, addr, data);
 662 #endif
 663                 return do_ptrace_normal(child, request, addr, data);
 664         }
 665         /* Not reached.  */
 666         return -EIO;
 667 }
 668
 669 asmlinkage long
 670 sys_ptrace(long request, long pid, long addr, long data)
 671 {
 672         struct task_struct *child;
 673         int ret;
 674
 675         lock_kernel();
 676
 677         if (request == PTRACE_TRACEME) {
 678                 /* are we already being traced? */
 679                 ret = -EPERM;
 680                 if (current->ptrace & PT_PTRACED)
 681                         goto out;
 682                 ret = security_ptrace(current->parent, current);
 683                 if (ret)
 684                         goto out;
 685                 /* set the ptrace bit in the process flags. */
 686                 current->ptrace |= PT_PTRACED;
 687                 goto out;
 688         }
 689
 690         ret = -EPERM;
 691         if (pid == 1)           /* you may not mess with init */
 692                 goto out;
 693
 694         ret = -ESRCH;
 695         read_lock(&tasklist_lock);
 696         child = find_task_by_pid(pid);
 697         if (child)
 698                 get_task_struct(child);
 699         read_unlock(&tasklist_lock);
 700         if (!child)
 701                 goto out;
 702
 703         ret = do_ptrace(child, request, addr, data);
 704
 705         put_task_struct(child);
 706 out:
 707         unlock_kernel();
 708         return ret;
 709 }
 710
 711 asmlinkage void
 712 syscall_trace(struct pt_regs *regs, int entryexit)
 713 {
 714         if (unlikely(current->audit_context)) {
 715                 if (!entryexit)
 716                         audit_syscall_entry(current, regs->gprs[2],
 717                                             regs->orig_gpr2, regs->gprs[3],
 718                                             regs->gprs[4], regs->gprs[5]);
 719                 else
 720                         audit_syscall_exit(current, regs->gprs[2]);
 721         }
 722         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 723                 return;
 724         if (!(current->ptrace & PT_PTRACED))
 725                 return;
 726         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 727                                  ? 0x80 : 0));
 728
 729         /*
 730          * this isn't the same as continuing with a signal, but it will do
 731          * for normal use.  strace only continues with a signal if the
 732          * stopping signal is not SIGTRAP.  -brl
 733          */
 734         if (current->exit_code) {
 735                 send_sig(current->exit_code, current, 1);
 736                 current->exit_code = 0;
 737         }
 738 }