arch/m32r/kernel/ptrace.c

   1 /*
   2  * linux/arch/m32r/kernel/ptrace.c
   3  *
   4  * Copyright (C) 2002  Hirokazu Takata, Takeo Takahashi
   5  * Copyright (C) 2004  Hirokazu Takata, Kei Sakamoto
   6  *
   7  * Original x86 implementation:
   8  *      By Ross Biro 1/23/92
   9  *      edited by Linus Torvalds
  10  *
  11  * Some code taken from sh version:
  12  *   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
  13  * Some code taken from arm version:
  14  *   Copyright (C) 2000 Russell King
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/sched.h>
  19 #include <linux/mm.h>
  20 #include <linux/err.h>
  21 #include <linux/smp.h>
  22 #include <linux/smp_lock.h>
  23 #include <linux/errno.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/user.h>
  26 #include <linux/string.h>
  27 #include <linux/signal.h>
  28
  29 #include <asm/cacheflush.h>
  30 #include <asm/io.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/pgtable.h>
  33 #include <asm/system.h>
  34 #include <asm/processor.h>
  35 #include <asm/mmu_context.h>
  36
  37 /*
  38  * This routine will get a word off of the process kernel stack.
  39  */
  40 static inline unsigned long int
  41 get_stack_long(struct task_struct *task, int offset)
  42 {
  43         unsigned long *stack;
  44
  45         stack = (unsigned long *)task_pt_regs(task);
  46
  47         return stack[offset];
  48 }
  49
  50 /*
  51  * This routine will put a word on the process kernel stack.
  52  */
  53 static inline int
  54 put_stack_long(struct task_struct *task, int offset, unsigned long data)
  55 {
  56         unsigned long *stack;
  57
  58         stack = (unsigned long *)task_pt_regs(task);
  59         stack[offset] = data;
  60
  61         return 0;
  62 }
  63
  64 static int reg_offset[] = {
  65         PT_R0, PT_R1, PT_R2, PT_R3, PT_R4, PT_R5, PT_R6, PT_R7,
  66         PT_R8, PT_R9, PT_R10, PT_R11, PT_R12, PT_FP, PT_LR, PT_SPU,
  67 };
  68
  69 /*
  70  * Read the word at offset "off" into the "struct user".  We
  71  * actually access the pt_regs stored on the kernel stack.
  72  */
  73 static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
  74                             unsigned long __user *data)
  75 {
  76         unsigned long tmp;
  77 #ifndef NO_FPU
  78         struct user * dummy = NULL;
  79 #endif
  80
  81         if ((off & 3) || (off < 0) || (off > sizeof(struct user) - 3))
  82                 return -EIO;
  83
  84         off >>= 2;
  85         switch (off) {
  86         case PT_EVB:
  87                 __asm__ __volatile__ (
  88                         "mvfc   %0, cr5 \n\t"
  89                         : "=r" (tmp)
  90                 );
  91                 break;
  92         case PT_CBR: {
  93                         unsigned long psw;
  94                         psw = get_stack_long(tsk, PT_PSW);
  95                         tmp = ((psw >> 8) & 1);
  96                 }
  97                 break;
  98         case PT_PSW: {
  99                         unsigned long psw, bbpsw;
 100                         psw = get_stack_long(tsk, PT_PSW);
 101                         bbpsw = get_stack_long(tsk, PT_BBPSW);
 102                         tmp = ((psw >> 8) & 0xff) | ((bbpsw & 0xff) << 8);
 103                 }
 104                 break;
 105         case PT_PC:
 106                 tmp = get_stack_long(tsk, PT_BPC);
 107                 break;
 108         case PT_BPC:
 109                 off = PT_BBPC;
 110                 /* fall through */
 111         default:
 112                 if (off < (sizeof(struct pt_regs) >> 2))
 113                         tmp = get_stack_long(tsk, off);
 114 #ifndef NO_FPU
 115                 else if (off >= (long)(&dummy->fpu >> 2) &&
 116                          off < (long)(&dummy->u_fpvalid >> 2)) {
 117                         if (!tsk_used_math(tsk)) {
 118                                 if (off == (long)(&dummy->fpu.fpscr >> 2))
 119                                         tmp = FPSCR_INIT;
 120                                 else
 121                                         tmp = 0;
 122                         } else
 123                                 tmp = ((long *)(&tsk->thread.fpu >> 2))
 124                                         [off - (long)&dummy->fpu];
 125                 } else if (off == (long)(&dummy->u_fpvalid >> 2))
 126                         tmp = !!tsk_used_math(tsk);
 127 #endif /* not NO_FPU */
 128                 else
 129                         tmp = 0;
 130         }
 131
 132         return put_user(tmp, data);
 133 }
 134
 135 static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
 136                              unsigned long data)
 137 {
 138         int ret = -EIO;
 139 #ifndef NO_FPU
 140         struct user * dummy = NULL;
 141 #endif
 142
 143         if ((off & 3) || off < 0 ||
 144             off > sizeof(struct user) - 3)
 145                 return -EIO;
 146
 147         off >>= 2;
 148         switch (off) {
 149         case PT_EVB:
 150         case PT_BPC:
 151         case PT_SPI:
 152                 /* We don't allow to modify evb. */
 153                 ret = 0;
 154                 break;
 155         case PT_PSW:
 156         case PT_CBR: {
 157                         /* We allow to modify only cbr in psw */
 158                         unsigned long psw;
 159                         psw = get_stack_long(tsk, PT_PSW);
 160                         psw = (psw & ~0x100) | ((data & 1) << 8);
 161                         ret = put_stack_long(tsk, PT_PSW, psw);
 162                 }
 163                 break;
 164         case PT_PC:
 165                 off = PT_BPC;
 166                 data &= ~1;
 167                 /* fall through */
 168         default:
 169                 if (off < (sizeof(struct pt_regs) >> 2))
 170                         ret = put_stack_long(tsk, off, data);
 171 #ifndef NO_FPU
 172                 else if (off >= (long)(&dummy->fpu >> 2) &&
 173                          off < (long)(&dummy->u_fpvalid >> 2)) {
 174                         set_stopped_child_used_math(tsk);
 175                         ((long *)&tsk->thread.fpu)
 176                                 [off - (long)&dummy->fpu] = data;
 177                         ret = 0;
 178                 } else if (off == (long)(&dummy->u_fpvalid >> 2)) {
 179                         conditional_stopped_child_used_math(data, tsk);
 180                         ret = 0;
 181                 }
 182 #endif /* not NO_FPU */
 183                 break;
 184         }
 185
 186         return ret;
 187 }
 188
 189 /*
 190  * Get all user integer registers.
 191  */
 192 static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
 193 {
 194         struct pt_regs *regs = task_pt_regs(tsk);
 195
 196         return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
 197 }
 198
 199 /*
 200  * Set all user integer registers.
 201  */
 202 static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
 203 {
 204         struct pt_regs newregs;
 205         int ret;
 206
 207         ret = -EFAULT;
 208         if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
 209                 struct pt_regs *regs = task_pt_regs(tsk);
 210                 *regs = newregs;
 211                 ret = 0;
 212         }
 213
 214         return ret;
 215 }
 216
 217
 218 static inline int
 219 check_condition_bit(struct task_struct *child)
 220 {
 221         return (int)((get_stack_long(child, PT_PSW) >> 8) & 1);
 222 }
 223
 224 static int
 225 check_condition_src(unsigned long op, unsigned long regno1,
 226                     unsigned long regno2, struct task_struct *child)
 227 {
 228         unsigned long reg1, reg2;
 229
 230         reg2 = get_stack_long(child, reg_offset[regno2]);
 231
 232         switch (op) {
 233         case 0x0: /* BEQ */
 234                 reg1 = get_stack_long(child, reg_offset[regno1]);
 235                 return reg1 == reg2;
 236         case 0x1: /* BNE */
 237                 reg1 = get_stack_long(child, reg_offset[regno1]);
 238                 return reg1 != reg2;
 239         case 0x8: /* BEQZ */
 240                 return reg2 == 0;
 241         case 0x9: /* BNEZ */
 242                 return reg2 != 0;
 243         case 0xa: /* BLTZ */
 244                 return (int)reg2 < 0;
 245         case 0xb: /* BGEZ */
 246                 return (int)reg2 >= 0;
 247         case 0xc: /* BLEZ */
 248                 return (int)reg2 <= 0;
 249         case 0xd: /* BGTZ */
 250                 return (int)reg2 > 0;
 251         default:
 252                 /* never reached */
 253                 return 0;
 254         }
 255 }
 256
 257 static void
 258 compute_next_pc_for_16bit_insn(unsigned long insn, unsigned long pc,
 259                                unsigned long *next_pc,
 260                                struct task_struct *child)
 261 {
 262         unsigned long op, op2, op3;
 263         unsigned long disp;
 264         unsigned long regno;
 265         int parallel = 0;
 266
 267         if (insn & 0x00008000)
 268                 parallel = 1;
 269         if (pc & 3)
 270                 insn &= 0x7fff; /* right slot */
 271         else
 272                 insn >>= 16;    /* left slot */
 273
 274         op = (insn >> 12) & 0xf;
 275         op2 = (insn >> 8) & 0xf;
 276         op3 = (insn >> 4) & 0xf;
 277
 278         if (op == 0x7) {
 279                 switch (op2) {
 280                 case 0xd: /* BNC */
 281                 case 0x9: /* BNCL */
 282                         if (!check_condition_bit(child)) {
 283                                 disp = (long)(insn << 24) >> 22;
 284                                 *next_pc = (pc & ~0x3) + disp;
 285                                 return;
 286                         }
 287                         break;
 288                 case 0x8: /* BCL */
 289                 case 0xc: /* BC */
 290                         if (check_condition_bit(child)) {
 291                                 disp = (long)(insn << 24) >> 22;
 292                                 *next_pc = (pc & ~0x3) + disp;
 293                                 return;
 294                         }
 295                         break;
 296                 case 0xe: /* BL */
 297                 case 0xf: /* BRA */
 298                         disp = (long)(insn << 24) >> 22;
 299                         *next_pc = (pc & ~0x3) + disp;
 300                         return;
 301                         break;
 302                 }
 303         } else if (op == 0x1) {
 304                 switch (op2) {
 305                 case 0x0:
 306                         if (op3 == 0xf) { /* TRAP */
 307 #if 1
 308                                 /* pass through */
 309 #else
 310                                 /* kernel space is not allowed as next_pc */
 311                                 unsigned long evb;
 312                                 unsigned long trapno;
 313                                 trapno = insn & 0xf;
 314                                 __asm__ __volatile__ (
 315                                         "mvfc %0, cr5\n"
 316                                         :"=r"(evb)
 317                                         :
 318                                 );
 319                                 *next_pc = evb + (trapno << 2);
 320                                 return;
 321 #endif
 322                         } else if (op3 == 0xd) { /* RTE */
 323                                 *next_pc = get_stack_long(child, PT_BPC);
 324                                 return;
 325                         }
 326                         break;
 327                 case 0xc: /* JC */
 328                         if (op3 == 0xc && check_condition_bit(child)) {
 329                                 regno = insn & 0xf;
 330                                 *next_pc = get_stack_long(child,
 331                                                           reg_offset[regno]);
 332                                 return;
 333                         }
 334                         break;
 335                 case 0xd: /* JNC */
 336                         if (op3 == 0xc && !check_condition_bit(child)) {
 337                                 regno = insn & 0xf;
 338                                 *next_pc = get_stack_long(child,
 339                                                           reg_offset[regno]);
 340                                 return;
 341                         }
 342                         break;
 343                 case 0xe: /* JL */
 344                 case 0xf: /* JMP */
 345                         if (op3 == 0xc) { /* JMP */
 346                                 regno = insn & 0xf;
 347                                 *next_pc = get_stack_long(child,
 348                                                           reg_offset[regno]);
 349                                 return;
 350                         }
 351                         break;
 352                 }
 353         }
 354         if (parallel)
 355                 *next_pc = pc + 4;
 356         else
 357                 *next_pc = pc + 2;
 358 }
 359
 360 static void
 361 compute_next_pc_for_32bit_insn(unsigned long insn, unsigned long pc,
 362                                unsigned long *next_pc,
 363                                struct task_struct *child)
 364 {
 365         unsigned long op;
 366         unsigned long op2;
 367         unsigned long disp;
 368         unsigned long regno1, regno2;
 369
 370         op = (insn >> 28) & 0xf;
 371         if (op == 0xf) {        /* branch 24-bit relative */
 372                 op2 = (insn >> 24) & 0xf;
 373                 switch (op2) {
 374                 case 0xd:       /* BNC */
 375                 case 0x9:       /* BNCL */
 376                         if (!check_condition_bit(child)) {
 377                                 disp = (long)(insn << 8) >> 6;
 378                                 *next_pc = (pc & ~0x3) + disp;
 379                                 return;
 380                         }
 381                         break;
 382                 case 0x8:       /* BCL */
 383                 case 0xc:       /* BC */
 384                         if (check_condition_bit(child)) {
 385                                 disp = (long)(insn << 8) >> 6;
 386                                 *next_pc = (pc & ~0x3) + disp;
 387                                 return;
 388                         }
 389                         break;
 390                 case 0xe:       /* BL */
 391                 case 0xf:       /* BRA */
 392                         disp = (long)(insn << 8) >> 6;
 393                         *next_pc = (pc & ~0x3) + disp;
 394                         return;
 395                 }
 396         } else if (op == 0xb) { /* branch 16-bit relative */
 397                 op2 = (insn >> 20) & 0xf;
 398                 switch (op2) {
 399                 case 0x0: /* BEQ */
 400                 case 0x1: /* BNE */
 401                 case 0x8: /* BEQZ */
 402                 case 0x9: /* BNEZ */
 403                 case 0xa: /* BLTZ */
 404                 case 0xb: /* BGEZ */
 405                 case 0xc: /* BLEZ */
 406                 case 0xd: /* BGTZ */
 407                         regno1 = ((insn >> 24) & 0xf);
 408                         regno2 = ((insn >> 16) & 0xf);
 409                         if (check_condition_src(op2, regno1, regno2, child)) {
 410                                 disp = (long)(insn << 16) >> 14;
 411                                 *next_pc = (pc & ~0x3) + disp;
 412                                 return;
 413                         }
 414                         break;
 415                 }
 416         }
 417         *next_pc = pc + 4;
 418 }
 419
 420 static inline void
 421 compute_next_pc(unsigned long insn, unsigned long pc,
 422                 unsigned long *next_pc, struct task_struct *child)
 423 {
 424         if (insn & 0x80000000)
 425                 compute_next_pc_for_32bit_insn(insn, pc, next_pc, child);
 426         else
 427                 compute_next_pc_for_16bit_insn(insn, pc, next_pc, child);
 428 }
 429
 430 static int
 431 register_debug_trap(struct task_struct *child, unsigned long next_pc,
 432         unsigned long next_insn, unsigned long *code)
 433 {
 434         struct debug_trap *p = &child->thread.debug_trap;
 435         unsigned long addr = next_pc & ~3;
 436
 437         if (p->nr_trap == MAX_TRAPS) {
 438                 printk("kernel BUG at %s %d: p->nr_trap = %d\n",
 439                                         __FILE__, __LINE__, p->nr_trap);
 440                 return -1;
 441         }
 442         p->addr[p->nr_trap] = addr;
 443         p->insn[p->nr_trap] = next_insn;
 444         p->nr_trap++;
 445         if (next_pc & 3) {
 446                 *code = (next_insn & 0xffff0000) | 0x10f1;
 447                 /* xxx --> TRAP1 */
 448         } else {
 449                 if ((next_insn & 0x80000000) || (next_insn & 0x8000)) {
 450                         *code = 0x10f17000;
 451                         /* TRAP1 --> NOP */
 452                 } else {
 453                         *code = (next_insn & 0xffff) | 0x10f10000;
 454                         /* TRAP1 --> xxx */
 455                 }
 456         }
 457         return 0;
 458 }
 459
 460 static int
 461 unregister_debug_trap(struct task_struct *child, unsigned long addr,
 462                       unsigned long *code)
 463 {
 464         struct debug_trap *p = &child->thread.debug_trap;
 465         int i;
 466
 467         /* Search debug trap entry. */
 468         for (i = 0; i < p->nr_trap; i++) {
 469                 if (p->addr[i] == addr)
 470                         break;
 471         }
 472         if (i >= p->nr_trap) {
 473                 /* The trap may be requested from debugger.
 474                  * ptrace should do nothing in this case.
 475                  */
 476                 return 0;
 477         }
 478
 479         /* Recover original instruction code. */
 480         *code = p->insn[i];
 481
 482         /* Shift debug trap entries. */
 483         while (i < p->nr_trap - 1) {
 484                 p->insn[i] = p->insn[i + 1];
 485                 p->addr[i] = p->addr[i + 1];
 486                 i++;
 487         }
 488         p->nr_trap--;
 489         return 1;
 490 }
 491
 492 static void
 493 unregister_all_debug_traps(struct task_struct *child)
 494 {
 495         struct debug_trap *p = &child->thread.debug_trap;
 496         int i;
 497
 498         for (i = 0; i < p->nr_trap; i++)
 499                 access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
 500         p->nr_trap = 0;
 501 }
 502
 503 static inline void
 504 invalidate_cache(void)
 505 {
 506 #if defined(CONFIG_CHIP_M32700) || defined(CONFIG_CHIP_OPSP)
 507
 508         _flush_cache_copyback_all();
 509
 510 #else   /* ! CONFIG_CHIP_M32700 */
 511
 512         /* Invalidate cache */
 513         __asm__ __volatile__ (
 514                 "ldi    r0, #-1                                 \n\t"
 515                 "ldi    r1, #0                                  \n\t"
 516                 "stb    r1, @r0         ; cache off             \n\t"
 517                 ";                                              \n\t"
 518                 "ldi    r0, #-2                                 \n\t"
 519                 "ldi    r1, #1                                  \n\t"
 520                 "stb    r1, @r0         ; cache invalidate      \n\t"
 521                 ".fillinsn                                      \n"
 522                 "0:                                             \n\t"
 523                 "ldb    r1, @r0         ; invalidate check      \n\t"
 524                 "bnez   r1, 0b                                  \n\t"
 525                 ";                                              \n\t"
 526                 "ldi    r0, #-1                                 \n\t"
 527                 "ldi    r1, #1                                  \n\t"
 528                 "stb    r1, @r0         ; cache on              \n\t"
 529                 : : : "r0", "r1", "memory"
 530         );
 531         /* FIXME: copying-back d-cache and invalidating i-cache are needed.
 532          */
 533 #endif  /* CONFIG_CHIP_M32700 */
 534 }
 535
 536 /* Embed a debug trap (TRAP1) code */
 537 static int
 538 embed_debug_trap(struct task_struct *child, unsigned long next_pc)
 539 {
 540         unsigned long next_insn, code;
 541         unsigned long addr = next_pc & ~3;
 542
 543         if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0)
 544             != sizeof(next_insn)) {
 545                 return -1; /* error */
 546         }
 547
 548         /* Set a trap code. */
 549         if (register_debug_trap(child, next_pc, next_insn, &code)) {
 550                 return -1; /* error */
 551         }
 552         if (access_process_vm(child, addr, &code, sizeof(code), 1)
 553             != sizeof(code)) {
 554                 return -1; /* error */
 555         }
 556         return 0; /* success */
 557 }
 558
 559 void
 560 withdraw_debug_trap(struct pt_regs *regs)
 561 {
 562         unsigned long addr;
 563         unsigned long code;
 564
 565         addr = (regs->bpc - 2) & ~3;
 566         regs->bpc -= 2;
 567         if (unregister_debug_trap(current, addr, &code)) {
 568             access_process_vm(current, addr, &code, sizeof(code), 1);
 569             invalidate_cache();
 570         }
 571 }
 572
 573 void
 574 init_debug_traps(struct task_struct *child)
 575 {
 576         struct debug_trap *p = &child->thread.debug_trap;
 577         int i;
 578         p->nr_trap = 0;
 579         for (i = 0; i < MAX_TRAPS; i++) {
 580                 p->addr[i] = 0;
 581                 p->insn[i] = 0;
 582         }
 583 }
 584
 585
 586 /*
 587  * Called by kernel/ptrace.c when detaching..
 588  *
 589  * Make sure single step bits etc are not set.
 590  */
 591 void ptrace_disable(struct task_struct *child)
 592 {
 593         /* nothing to do.. */
 594 }
 595
 596 long
 597 arch_ptrace(struct task_struct *child, long request, long addr, long data)
 598 {
 599         int ret;
 600
 601         switch (request) {
 602         /*
 603          * read word at location "addr" in the child process.
 604          */
 605         case PTRACE_PEEKTEXT:
 606         case PTRACE_PEEKDATA:
 607                 ret = generic_ptrace_peekdata(child, addr, data);
 608                 break;
 609
 610         /*
 611          * read the word at location addr in the USER area.
 612          */
 613         case PTRACE_PEEKUSR:
 614                 ret = ptrace_read_user(child, addr,
 615                                        (unsigned long __user *)data);
 616                 break;
 617
 618         /*
 619          * write the word at location addr.
 620          */
 621         case PTRACE_POKETEXT:
 622         case PTRACE_POKEDATA:
 623                 ret = generic_ptrace_pokedata(child, addr, data);
 624                 if (ret == 0 && request == PTRACE_POKETEXT)
 625                         invalidate_cache();
 626                 break;
 627
 628         /*
 629          * write the word at location addr in the USER area.
 630          */
 631         case PTRACE_POKEUSR:
 632                 ret = ptrace_write_user(child, addr, data);
 633                 break;
 634
 635         /*
 636          * continue/restart and stop at next (return from) syscall
 637          */
 638         case PTRACE_SYSCALL:
 639         case PTRACE_CONT:
 640                 ret = -EIO;
 641                 if (!valid_signal(data))
 642                         break;
 643                 if (request == PTRACE_SYSCALL)
 644                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 645                 else
 646                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 647                 child->exit_code = data;
 648                 wake_up_process(child);
 649                 ret = 0;
 650                 break;
 651
 652         /*
 653          * make the child exit.  Best I can do is send it a sigkill.
 654          * perhaps it should be put in the status that it wants to
 655          * exit.
 656          */
 657         case PTRACE_KILL: {
 658                 ret = 0;
 659                 unregister_all_debug_traps(child);
 660                 invalidate_cache();
 661                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 662                         break;
 663                 child->exit_code = SIGKILL;
 664                 wake_up_process(child);
 665                 break;
 666         }
 667
 668         /*
 669          * execute single instruction.
 670          */
 671         case PTRACE_SINGLESTEP: {
 672                 unsigned long next_pc;
 673                 unsigned long pc, insn;
 674
 675                 ret = -EIO;
 676                 if (!valid_signal(data))
 677                         break;
 678                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 679
 680                 /* Compute next pc.  */
 681                 pc = get_stack_long(child, PT_BPC);
 682
 683                 if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
 684                     != sizeof(insn))
 685                         break;
 686
 687                 compute_next_pc(insn, pc, &next_pc, child);
 688                 if (next_pc & 0x80000000)
 689                         break;
 690
 691                 if (embed_debug_trap(child, next_pc))
 692                         break;
 693
 694                 invalidate_cache();
 695                 child->exit_code = data;
 696
 697                 /* give it a chance to run. */
 698                 wake_up_process(child);
 699                 ret = 0;
 700                 break;
 701         }
 702
 703         case PTRACE_GETREGS:
 704                 ret = ptrace_getregs(child, (void __user *)data);
 705                 break;
 706
 707         case PTRACE_SETREGS:
 708                 ret = ptrace_setregs(child, (void __user *)data);
 709                 break;
 710
 711         default:
 712                 ret = ptrace_request(child, request, addr, data);
 713                 break;
 714         }
 715
 716         return ret;
 717 }
 718
 719 /* notification of system call entry/exit
 720  * - triggered by current->work.syscall_trace
 721  */
 722 void do_syscall_trace(void)
 723 {
 724         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 725                 return;
 726         if (!(current->ptrace & PT_PTRACED))
 727                 return;
 728         /* the 0x80 provides a way for the tracing parent to distinguish
 729            between a syscall stop and SIGTRAP delivery */
 730         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 731                                  ? 0x80 : 0));
 732
 733         /*
 734          * this isn't the same as continuing with a signal, but it will do
 735          * for normal use.  strace only continues with a signal if the
 736          * stopping signal is not SIGTRAP.  -brl
 737          */
 738         if (current->exit_code) {
 739                 send_sig(current->exit_code, current, 1);
 740                 current->exit_code = 0;
 741         }
 742 }