Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...
[linux-2.6] / 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/smp.h>
21 #include <linux/smp_lock.h>
22 #include <linux/errno.h>
23 #include <linux/ptrace.h>
24 #include <linux/user.h>
25 #include <linux/string.h>
26 #include <linux/signal.h>
27
28 #include <asm/cacheflush.h>
29 #include <asm/io.h>
30 #include <asm/uaccess.h>
31 #include <asm/pgtable.h>
32 #include <asm/system.h>
33 #include <asm/processor.h>
34 #include <asm/mmu_context.h>
35
36 /*
37  * This routine will get a word off of the process kernel stack.
38  */
39 static inline unsigned long int
40 get_stack_long(struct task_struct *task, int offset)
41 {
42         unsigned long *stack;
43
44         stack = (unsigned long *)task_pt_regs(task);
45
46         return stack[offset];
47 }
48
49 /*
50  * This routine will put a word on the process kernel stack.
51  */
52 static inline int
53 put_stack_long(struct task_struct *task, int offset, unsigned long data)
54 {
55         unsigned long *stack;
56
57         stack = (unsigned long *)task_pt_regs(task);
58         stack[offset] = data;
59
60         return 0;
61 }
62
63 static int reg_offset[] = {
64         PT_R0, PT_R1, PT_R2, PT_R3, PT_R4, PT_R5, PT_R6, PT_R7,
65         PT_R8, PT_R9, PT_R10, PT_R11, PT_R12, PT_FP, PT_LR, PT_SPU,
66 };
67
68 /*
69  * Read the word at offset "off" into the "struct user".  We
70  * actually access the pt_regs stored on the kernel stack.
71  */
72 static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
73                             unsigned long __user *data)
74 {
75         unsigned long tmp;
76 #ifndef NO_FPU
77         struct user * dummy = NULL;
78 #endif
79
80         if ((off & 3) || (off < 0) || (off > sizeof(struct user) - 3))
81                 return -EIO;
82
83         off >>= 2;
84         switch (off) {
85         case PT_EVB:
86                 __asm__ __volatile__ (
87                         "mvfc   %0, cr5 \n\t"
88                         : "=r" (tmp)
89                 );
90                 break;
91         case PT_CBR: {
92                         unsigned long psw;
93                         psw = get_stack_long(tsk, PT_PSW);
94                         tmp = ((psw >> 8) & 1);
95                 }
96                 break;
97         case PT_PSW: {
98                         unsigned long psw, bbpsw;
99                         psw = get_stack_long(tsk, PT_PSW);
100                         bbpsw = get_stack_long(tsk, PT_BBPSW);
101                         tmp = ((psw >> 8) & 0xff) | ((bbpsw & 0xff) << 8);
102                 }
103                 break;
104         case PT_PC:
105                 tmp = get_stack_long(tsk, PT_BPC);
106                 break;
107         case PT_BPC:
108                 off = PT_BBPC;
109                 /* fall through */
110         default:
111                 if (off < (sizeof(struct pt_regs) >> 2))
112                         tmp = get_stack_long(tsk, off);
113 #ifndef NO_FPU
114                 else if (off >= (long)(&dummy->fpu >> 2) &&
115                          off < (long)(&dummy->u_fpvalid >> 2)) {
116                         if (!tsk_used_math(tsk)) {
117                                 if (off == (long)(&dummy->fpu.fpscr >> 2))
118                                         tmp = FPSCR_INIT;
119                                 else
120                                         tmp = 0;
121                         } else
122                                 tmp = ((long *)(&tsk->thread.fpu >> 2))
123                                         [off - (long)&dummy->fpu];
124                 } else if (off == (long)(&dummy->u_fpvalid >> 2))
125                         tmp = !!tsk_used_math(tsk);
126 #endif /* not NO_FPU */
127                 else
128                         tmp = 0;
129         }
130
131         return put_user(tmp, data);
132 }
133
134 static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
135                              unsigned long data)
136 {
137         int ret = -EIO;
138 #ifndef NO_FPU
139         struct user * dummy = NULL;
140 #endif
141
142         if ((off & 3) || off < 0 ||
143             off > sizeof(struct user) - 3)
144                 return -EIO;
145
146         off >>= 2;
147         switch (off) {
148         case PT_EVB:
149         case PT_BPC:
150         case PT_SPI:
151                 /* We don't allow to modify evb. */
152                 ret = 0;
153                 break;
154         case PT_PSW:
155         case PT_CBR: {
156                         /* We allow to modify only cbr in psw */
157                         unsigned long psw;
158                         psw = get_stack_long(tsk, PT_PSW);
159                         psw = (psw & ~0x100) | ((data & 1) << 8);
160                         ret = put_stack_long(tsk, PT_PSW, psw);
161                 }
162                 break;
163         case PT_PC:
164                 off = PT_BPC;
165                 data &= ~1;
166                 /* fall through */
167         default:
168                 if (off < (sizeof(struct pt_regs) >> 2))
169                         ret = put_stack_long(tsk, off, data);
170 #ifndef NO_FPU
171                 else if (off >= (long)(&dummy->fpu >> 2) &&
172                          off < (long)(&dummy->u_fpvalid >> 2)) {
173                         set_stopped_child_used_math(tsk);
174                         ((long *)&tsk->thread.fpu)
175                                 [off - (long)&dummy->fpu] = data;
176                         ret = 0;
177                 } else if (off == (long)(&dummy->u_fpvalid >> 2)) {
178                         conditional_stopped_child_used_math(data, tsk);
179                         ret = 0;
180                 }
181 #endif /* not NO_FPU */
182                 break;
183         }
184
185         return ret;
186 }
187
188 /*
189  * Get all user integer registers.
190  */
191 static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
192 {
193         struct pt_regs *regs = task_pt_regs(tsk);
194
195         return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
196 }
197
198 /*
199  * Set all user integer registers.
200  */
201 static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
202 {
203         struct pt_regs newregs;
204         int ret;
205
206         ret = -EFAULT;
207         if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
208                 struct pt_regs *regs = task_pt_regs(tsk);
209                 *regs = newregs;
210                 ret = 0;
211         }
212
213         return ret;
214 }
215
216
217 static inline int
218 check_condition_bit(struct task_struct *child)
219 {
220         return (int)((get_stack_long(child, PT_PSW) >> 8) & 1);
221 }
222
223 static int
224 check_condition_src(unsigned long op, unsigned long regno1,
225                     unsigned long regno2, struct task_struct *child)
226 {
227         unsigned long reg1, reg2;
228
229         reg2 = get_stack_long(child, reg_offset[regno2]);
230
231         switch (op) {
232         case 0x0: /* BEQ */
233                 reg1 = get_stack_long(child, reg_offset[regno1]);
234                 return reg1 == reg2;
235         case 0x1: /* BNE */
236                 reg1 = get_stack_long(child, reg_offset[regno1]);
237                 return reg1 != reg2;
238         case 0x8: /* BEQZ */
239                 return reg2 == 0;
240         case 0x9: /* BNEZ */
241                 return reg2 != 0;
242         case 0xa: /* BLTZ */
243                 return (int)reg2 < 0;
244         case 0xb: /* BGEZ */
245                 return (int)reg2 >= 0;
246         case 0xc: /* BLEZ */
247                 return (int)reg2 <= 0;
248         case 0xd: /* BGTZ */
249                 return (int)reg2 > 0;
250         default:
251                 /* never reached */
252                 return 0;
253         }
254 }
255
256 static void
257 compute_next_pc_for_16bit_insn(unsigned long insn, unsigned long pc,
258                                unsigned long *next_pc,
259                                struct task_struct *child)
260 {
261         unsigned long op, op2, op3;
262         unsigned long disp;
263         unsigned long regno;
264         int parallel = 0;
265
266         if (insn & 0x00008000)
267                 parallel = 1;
268         if (pc & 3)
269                 insn &= 0x7fff; /* right slot */
270         else
271                 insn >>= 16;    /* left slot */
272
273         op = (insn >> 12) & 0xf;
274         op2 = (insn >> 8) & 0xf;
275         op3 = (insn >> 4) & 0xf;
276
277         if (op == 0x7) {
278                 switch (op2) {
279                 case 0xd: /* BNC */
280                 case 0x9: /* BNCL */
281                         if (!check_condition_bit(child)) {
282                                 disp = (long)(insn << 24) >> 22;
283                                 *next_pc = (pc & ~0x3) + disp;
284                                 return;
285                         }
286                         break;
287                 case 0x8: /* BCL */
288                 case 0xc: /* BC */
289                         if (check_condition_bit(child)) {
290                                 disp = (long)(insn << 24) >> 22;
291                                 *next_pc = (pc & ~0x3) + disp;
292                                 return;
293                         }
294                         break;
295                 case 0xe: /* BL */
296                 case 0xf: /* BRA */
297                         disp = (long)(insn << 24) >> 22;
298                         *next_pc = (pc & ~0x3) + disp;
299                         return;
300                         break;
301                 }
302         } else if (op == 0x1) {
303                 switch (op2) {
304                 case 0x0:
305                         if (op3 == 0xf) { /* TRAP */
306 #if 1
307                                 /* pass through */
308 #else
309                                 /* kernel space is not allowed as next_pc */
310                                 unsigned long evb;
311                                 unsigned long trapno;
312                                 trapno = insn & 0xf;
313                                 __asm__ __volatile__ (
314                                         "mvfc %0, cr5\n"
315                                         :"=r"(evb)
316                                         :
317                                 );
318                                 *next_pc = evb + (trapno << 2);
319                                 return;
320 #endif
321                         } else if (op3 == 0xd) { /* RTE */
322                                 *next_pc = get_stack_long(child, PT_BPC);
323                                 return;
324                         }
325                         break;
326                 case 0xc: /* JC */
327                         if (op3 == 0xc && check_condition_bit(child)) {
328                                 regno = insn & 0xf;
329                                 *next_pc = get_stack_long(child,
330                                                           reg_offset[regno]);
331                                 return;
332                         }
333                         break;
334                 case 0xd: /* JNC */
335                         if (op3 == 0xc && !check_condition_bit(child)) {
336                                 regno = insn & 0xf;
337                                 *next_pc = get_stack_long(child,
338                                                           reg_offset[regno]);
339                                 return;
340                         }
341                         break;
342                 case 0xe: /* JL */
343                 case 0xf: /* JMP */
344                         if (op3 == 0xc) { /* JMP */
345                                 regno = insn & 0xf;
346                                 *next_pc = get_stack_long(child,
347                                                           reg_offset[regno]);
348                                 return;
349                         }
350                         break;
351                 }
352         }
353         if (parallel)
354                 *next_pc = pc + 4;
355         else
356                 *next_pc = pc + 2;
357 }
358
359 static void
360 compute_next_pc_for_32bit_insn(unsigned long insn, unsigned long pc,
361                                unsigned long *next_pc,
362                                struct task_struct *child)
363 {
364         unsigned long op;
365         unsigned long op2;
366         unsigned long disp;
367         unsigned long regno1, regno2;
368
369         op = (insn >> 28) & 0xf;
370         if (op == 0xf) {        /* branch 24-bit relative */
371                 op2 = (insn >> 24) & 0xf;
372                 switch (op2) {
373                 case 0xd:       /* BNC */
374                 case 0x9:       /* BNCL */
375                         if (!check_condition_bit(child)) {
376                                 disp = (long)(insn << 8) >> 6;
377                                 *next_pc = (pc & ~0x3) + disp;
378                                 return;
379                         }
380                         break;
381                 case 0x8:       /* BCL */
382                 case 0xc:       /* BC */
383                         if (check_condition_bit(child)) {
384                                 disp = (long)(insn << 8) >> 6;
385                                 *next_pc = (pc & ~0x3) + disp;
386                                 return;
387                         }
388                         break;
389                 case 0xe:       /* BL */
390                 case 0xf:       /* BRA */
391                         disp = (long)(insn << 8) >> 6;
392                         *next_pc = (pc & ~0x3) + disp;
393                         return;
394                 }
395         } else if (op == 0xb) { /* branch 16-bit relative */
396                 op2 = (insn >> 20) & 0xf;
397                 switch (op2) {
398                 case 0x0: /* BEQ */
399                 case 0x1: /* BNE */
400                 case 0x8: /* BEQZ */
401                 case 0x9: /* BNEZ */
402                 case 0xa: /* BLTZ */
403                 case 0xb: /* BGEZ */
404                 case 0xc: /* BLEZ */
405                 case 0xd: /* BGTZ */
406                         regno1 = ((insn >> 24) & 0xf);
407                         regno2 = ((insn >> 16) & 0xf);
408                         if (check_condition_src(op2, regno1, regno2, child)) {
409                                 disp = (long)(insn << 16) >> 14;
410                                 *next_pc = (pc & ~0x3) + disp;
411                                 return;
412                         }
413                         break;
414                 }
415         }
416         *next_pc = pc + 4;
417 }
418
419 static inline void
420 compute_next_pc(unsigned long insn, unsigned long pc,
421                 unsigned long *next_pc, struct task_struct *child)
422 {
423         if (insn & 0x80000000)
424                 compute_next_pc_for_32bit_insn(insn, pc, next_pc, child);
425         else
426                 compute_next_pc_for_16bit_insn(insn, pc, next_pc, child);
427 }
428
429 static int
430 register_debug_trap(struct task_struct *child, unsigned long next_pc,
431         unsigned long next_insn, unsigned long *code)
432 {
433         struct debug_trap *p = &child->thread.debug_trap;
434         unsigned long addr = next_pc & ~3;
435
436         if (p->nr_trap == MAX_TRAPS) {
437                 printk("kernel BUG at %s %d: p->nr_trap = %d\n",
438                                         __FILE__, __LINE__, p->nr_trap);
439                 return -1;
440         }
441         p->addr[p->nr_trap] = addr;
442         p->insn[p->nr_trap] = next_insn;
443         p->nr_trap++;
444         if (next_pc & 3) {
445                 *code = (next_insn & 0xffff0000) | 0x10f1;
446                 /* xxx --> TRAP1 */
447         } else {
448                 if ((next_insn & 0x80000000) || (next_insn & 0x8000)) {
449                         *code = 0x10f17000;
450                         /* TRAP1 --> NOP */
451                 } else {
452                         *code = (next_insn & 0xffff) | 0x10f10000;
453                         /* TRAP1 --> xxx */
454                 }
455         }
456         return 0;
457 }
458
459 static int
460 unregister_debug_trap(struct task_struct *child, unsigned long addr,
461                       unsigned long *code)
462 {
463         struct debug_trap *p = &child->thread.debug_trap;
464         int i;
465
466         /* Search debug trap entry. */
467         for (i = 0; i < p->nr_trap; i++) {
468                 if (p->addr[i] == addr)
469                         break;
470         }
471         if (i >= p->nr_trap) {
472                 /* The trap may be requested from debugger.
473                  * ptrace should do nothing in this case.
474                  */
475                 return 0;
476         }
477
478         /* Recover orignal instruction code. */
479         *code = p->insn[i];
480
481         /* Shift debug trap entries. */
482         while (i < p->nr_trap - 1) {
483                 p->insn[i] = p->insn[i + 1];
484                 p->addr[i] = p->addr[i + 1];
485                 i++;
486         }
487         p->nr_trap--;
488         return 1;
489 }
490
491 static void
492 unregister_all_debug_traps(struct task_struct *child)
493 {
494         struct debug_trap *p = &child->thread.debug_trap;
495         int i;
496
497         for (i = 0; i < p->nr_trap; i++)
498                 access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
499         p->nr_trap = 0;
500 }
501
502 static inline void
503 invalidate_cache(void)
504 {
505 #if defined(CONFIG_CHIP_M32700) || defined(CONFIG_CHIP_OPSP)
506
507         _flush_cache_copyback_all();
508
509 #else   /* ! CONFIG_CHIP_M32700 */
510
511         /* Invalidate cache */
512         __asm__ __volatile__ (
513                 "ldi    r0, #-1                                 \n\t"
514                 "ldi    r1, #0                                  \n\t"
515                 "stb    r1, @r0         ; cache off             \n\t"
516                 ";                                              \n\t"
517                 "ldi    r0, #-2                                 \n\t"
518                 "ldi    r1, #1                                  \n\t"
519                 "stb    r1, @r0         ; cache invalidate      \n\t"
520                 ".fillinsn                                      \n"
521                 "0:                                             \n\t"
522                 "ldb    r1, @r0         ; invalidate check      \n\t"
523                 "bnez   r1, 0b                                  \n\t"
524                 ";                                              \n\t"
525                 "ldi    r0, #-1                                 \n\t"
526                 "ldi    r1, #1                                  \n\t"
527                 "stb    r1, @r0         ; cache on              \n\t"
528                 : : : "r0", "r1", "memory"
529         );
530         /* FIXME: copying-back d-cache and invalidating i-cache are needed.
531          */
532 #endif  /* CONFIG_CHIP_M32700 */
533 }
534
535 /* Embed a debug trap (TRAP1) code */
536 static int
537 embed_debug_trap(struct task_struct *child, unsigned long next_pc)
538 {
539         unsigned long next_insn, code;
540         unsigned long addr = next_pc & ~3;
541
542         if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0)
543             != sizeof(next_insn)) {
544                 return -1; /* error */
545         }
546
547         /* Set a trap code. */
548         if (register_debug_trap(child, next_pc, next_insn, &code)) {
549                 return -1; /* error */
550         }
551         if (access_process_vm(child, addr, &code, sizeof(code), 1)
552             != sizeof(code)) {
553                 return -1; /* error */
554         }
555         return 0; /* success */
556 }
557
558 void
559 withdraw_debug_trap(struct pt_regs *regs)
560 {
561         unsigned long addr;
562         unsigned long code;
563
564         addr = (regs->bpc - 2) & ~3;
565         regs->bpc -= 2;
566         if (unregister_debug_trap(current, addr, &code)) {
567             access_process_vm(current, addr, &code, sizeof(code), 1);
568             invalidate_cache();
569         }
570 }
571
572 static void
573 init_debug_traps(struct task_struct *child)
574 {
575         struct debug_trap *p = &child->thread.debug_trap;
576         int i;
577         p->nr_trap = 0;
578         for (i = 0; i < MAX_TRAPS; i++) {
579                 p->addr[i] = 0;
580                 p->insn[i] = 0;
581         }
582 }
583
584
585 /*
586  * Called by kernel/ptrace.c when detaching..
587  *
588  * Make sure single step bits etc are not set.
589  */
590 void ptrace_disable(struct task_struct *child)
591 {
592         /* nothing to do.. */
593 }
594
595 static int
596 do_ptrace(long request, struct task_struct *child, long addr, long data)
597 {
598         unsigned long tmp;
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 = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
608                 if (ret == sizeof(tmp))
609                         ret = put_user(tmp,(unsigned long __user *) data);
610                 else
611                         ret = -EIO;
612                 break;
613
614         /*
615          * read the word at location addr in the USER area.
616          */
617         case PTRACE_PEEKUSR:
618                 ret = ptrace_read_user(child, addr,
619                                        (unsigned long __user *)data);
620                 break;
621
622         /*
623          * write the word at location addr.
624          */
625         case PTRACE_POKETEXT:
626         case PTRACE_POKEDATA:
627                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
628                 if (ret == sizeof(data)) {
629                         ret = 0;
630                         if (request == PTRACE_POKETEXT) {
631                                 invalidate_cache();
632                         }
633                 } else {
634                         ret = -EIO;
635                 }
636                 break;
637
638         /*
639          * write the word at location addr in the USER area.
640          */
641         case PTRACE_POKEUSR:
642                 ret = ptrace_write_user(child, addr, data);
643                 break;
644
645         /*
646          * continue/restart and stop at next (return from) syscall
647          */
648         case PTRACE_SYSCALL:
649         case PTRACE_CONT:
650                 ret = -EIO;
651                 if (!valid_signal(data))
652                         break;
653                 if (request == PTRACE_SYSCALL)
654                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
655                 else
656                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
657                 child->exit_code = data;
658                 wake_up_process(child);
659                 ret = 0;
660                 break;
661
662         /*
663          * make the child exit.  Best I can do is send it a sigkill.
664          * perhaps it should be put in the status that it wants to
665          * exit.
666          */
667         case PTRACE_KILL: {
668                 ret = 0;
669                 unregister_all_debug_traps(child);
670                 invalidate_cache();
671                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
672                         break;
673                 child->exit_code = SIGKILL;
674                 wake_up_process(child);
675                 break;
676         }
677
678         /*
679          * execute single instruction.
680          */
681         case PTRACE_SINGLESTEP: {
682                 unsigned long next_pc;
683                 unsigned long pc, insn;
684
685                 ret = -EIO;
686                 if (!valid_signal(data))
687                         break;
688                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
689                 if ((child->ptrace & PT_DTRACE) == 0) {
690                         /* Spurious delayed TF traps may occur */
691                         child->ptrace |= PT_DTRACE;
692                 }
693
694                 /* Compute next pc.  */
695                 pc = get_stack_long(child, PT_BPC);
696
697                 if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
698                     != sizeof(insn))
699                         break;
700
701                 compute_next_pc(insn, pc, &next_pc, child);
702                 if (next_pc & 0x80000000)
703                         break;
704
705                 if (embed_debug_trap(child, next_pc))
706                         break;
707
708                 invalidate_cache();
709                 child->exit_code = data;
710
711                 /* give it a chance to run. */
712                 wake_up_process(child);
713                 ret = 0;
714                 break;
715         }
716
717         /*
718          * detach a process that was attached.
719          */
720         case PTRACE_DETACH:
721                 ret = 0;
722                 ret = ptrace_detach(child, data);
723                 break;
724
725         case PTRACE_GETREGS:
726                 ret = ptrace_getregs(child, (void __user *)data);
727                 break;
728
729         case PTRACE_SETREGS:
730                 ret = ptrace_setregs(child, (void __user *)data);
731                 break;
732
733         default:
734                 ret = ptrace_request(child, request, addr, data);
735                 break;
736         }
737
738         return ret;
739 }
740
741 asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
742 {
743         struct task_struct *child;
744         int ret;
745
746         lock_kernel();
747         if (request == PTRACE_TRACEME) {
748                 ret = ptrace_traceme();
749                 goto out;
750         }
751
752         child = ptrace_get_task_struct(pid);
753         if (IS_ERR(child)) {
754                 ret = PTR_ERR(child);
755                 goto out;
756         }
757
758         if (request == PTRACE_ATTACH) {
759                 ret = ptrace_attach(child);
760                 if (ret == 0)
761                         init_debug_traps(child);
762                 goto out_tsk;
763         }
764
765         ret = ptrace_check_attach(child, request == PTRACE_KILL);
766         if (ret == 0)
767                 ret = do_ptrace(request, child, addr, data);
768
769 out_tsk:
770         put_task_struct(child);
771 out:
772         unlock_kernel();
773
774         return ret;
775 }
776
777 /* notification of system call entry/exit
778  * - triggered by current->work.syscall_trace
779  */
780 void do_syscall_trace(void)
781 {
782         if (!test_thread_flag(TIF_SYSCALL_TRACE))
783                 return;
784         if (!(current->ptrace & PT_PTRACED))
785                 return;
786         /* the 0x80 provides a way for the tracing parent to distinguish
787            between a syscall stop and SIGTRAP delivery */
788         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
789                                  ? 0x80 : 0));
790
791         /*
792          * this isn't the same as continuing with a signal, but it will do
793          * for normal use.  strace only continues with a signal if the
794          * stopping signal is not SIGTRAP.  -brl
795          */
796         if (current->exit_code) {
797                 send_sig(current->exit_code, current, 1);
798                 current->exit_code = 0;
799         }
800 }