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[IPV4]: Correct rp_filter help text.
[linux-2.6/verdex.git] / arch / arm / kernel / ptrace.c
blob6f2f46c2e406ee844632da068353b0167735886e
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
22 #include <asm/uaccess.h>
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 = pc_pointer(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 if (read_u32(child, base, &alt) == 0)
282 alt = pc_pointer(alt);
283 }
284 break;
285
286 case 0x08000000:
287 /*
288 * ldm
289 */
290 if ((insn & 0x00108000) == 0x00108000) {
291 unsigned long base;
292 unsigned int nr_regs;
293
294 if (insn & (1 << 23)) {
295 nr_regs = hweight16(insn & 65535) << 2;
296
297 if (!(insn & (1 << 24)))
298 nr_regs -= 4;
299 } else {
300 if (insn & (1 << 24))
301 nr_regs = -4;
302 else
303 nr_regs = 0;
304 }
305
306 base = ptrace_getrn(child, insn);
307
308 if (read_u32(child, base + nr_regs, &alt) == 0)
309 alt = pc_pointer(alt);
310 break;
311 }
312 break;
313
314 case 0x0a000000: {
315 /*
316 * bl or b
317 */
318 signed long displ;
319 /* It's a branch/branch link: instead of trying to
320 * figure out whether the branch will be taken or not,
321 * we'll put a breakpoint at both locations. This is
322 * simpler, more reliable, and probably not a whole lot
323 * slower than the alternative approach of emulating the
324 * branch.
325 */
326 displ = (insn & 0x00ffffff) << 8;
327 displ = (displ >> 6) + 8;
328 if (displ != 0 && displ != 4)
329 alt = pc + displ;
330 }
331 break;
332 }
333
334 return alt;
335 }
336
337 static int
338 swap_insn(struct task_struct *task, unsigned long addr,
339 void *old_insn, void *new_insn, int size)
340 {
341 int ret;
342
343 ret = access_process_vm(task, addr, old_insn, size, 0);
344 if (ret == size)
345 ret = access_process_vm(task, addr, new_insn, size, 1);
346 return ret;
347 }
348
349 static void
350 add_breakpoint(struct task_struct *task, struct debug_info *dbg, unsigned long addr)
351 {
352 int nr = dbg->nsaved;
353
354 if (nr < 2) {
355 u32 new_insn = BREAKINST_ARM;
356 int res;
357
358 res = swap_insn(task, addr, &dbg->bp[nr].insn, &new_insn, 4);
359
360 if (res == 4) {
361 dbg->bp[nr].address = addr;
362 dbg->nsaved += 1;
363 }
364 } else
365 printk(KERN_ERR "ptrace: too many breakpoints\n");
366 }
367
368 /*
369 * Clear one breakpoint in the user program. We copy what the hardware
370 * does and use bit 0 of the address to indicate whether this is a Thumb
371 * breakpoint or an ARM breakpoint.
372 */
373 static void clear_breakpoint(struct task_struct *task, struct debug_entry *bp)
374 {
375 unsigned long addr = bp->address;
376 union debug_insn old_insn;
377 int ret;
378
379 if (addr & 1) {
380 ret = swap_insn(task, addr & ~1, &old_insn.thumb,
381 &bp->insn.thumb, 2);
382
383 if (ret != 2 || old_insn.thumb != BREAKINST_THUMB)
384 printk(KERN_ERR "%s:%d: corrupted Thumb breakpoint at "
385 "0x%08lx (0x%04x)\n", task->comm, task->pid,
386 addr, old_insn.thumb);
387 } else {
388 ret = swap_insn(task, addr & ~3, &old_insn.arm,
389 &bp->insn.arm, 4);
390
391 if (ret != 4 || old_insn.arm != BREAKINST_ARM)
392 printk(KERN_ERR "%s:%d: corrupted ARM breakpoint at "
393 "0x%08lx (0x%08x)\n", task->comm, task->pid,
394 addr, old_insn.arm);
395 }
396 }
397
398 void ptrace_set_bpt(struct task_struct *child)
399 {
400 struct pt_regs *regs;
401 unsigned long pc;
402 u32 insn;
403 int res;
404
405 regs = task_pt_regs(child);
406 pc = instruction_pointer(regs);
407
408 if (thumb_mode(regs)) {
409 printk(KERN_WARNING "ptrace: can't handle thumb mode\n");
410 return;
411 }
412
413 res = read_instr(child, pc, &insn);
414 if (!res) {
415 struct debug_info *dbg = &child->thread.debug;
416 unsigned long alt;
417
418 dbg->nsaved = 0;
419
420 alt = get_branch_address(child, pc, insn);
421 if (alt)
422 add_breakpoint(child, dbg, alt);
423
424 /*
425 * Note that we ignore the result of setting the above
426 * breakpoint since it may fail. When it does, this is
427 * not so much an error, but a forewarning that we may
428 * be receiving a prefetch abort shortly.
429 *
430 * If we don't set this breakpoint here, then we can
431 * lose control of the thread during single stepping.
432 */
433 if (!alt || predicate(insn) != PREDICATE_ALWAYS)
434 add_breakpoint(child, dbg, pc + 4);
435 }
436 }
437
438 /*
439 * Ensure no single-step breakpoint is pending. Returns non-zero
440 * value if child was being single-stepped.
441 */
442 void ptrace_cancel_bpt(struct task_struct *child)
443 {
444 int i, nsaved = child->thread.debug.nsaved;
445
446 child->thread.debug.nsaved = 0;
447
448 if (nsaved > 2) {
449 printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
450 nsaved = 2;
451 }
452
453 for (i = 0; i < nsaved; i++)
454 clear_breakpoint(child, &child->thread.debug.bp[i]);
455 }
456
457 /*
458 * Called by kernel/ptrace.c when detaching..
459 */
460 void ptrace_disable(struct task_struct *child)
461 {
462 single_step_disable(child);
463 }
464
465 /*
466 * Handle hitting a breakpoint.
467 */
468 void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
469 {
470 siginfo_t info;
471
472 ptrace_cancel_bpt(tsk);
473
474 info.si_signo = SIGTRAP;
475 info.si_errno = 0;
476 info.si_code = TRAP_BRKPT;
477 info.si_addr = (void __user *)instruction_pointer(regs);
478
479 force_sig_info(SIGTRAP, &info, tsk);
480 }
481
482 static int break_trap(struct pt_regs *regs, unsigned int instr)
483 {
484 ptrace_break(current, regs);
485 return 0;
486 }
487
488 static struct undef_hook arm_break_hook = {
489 .instr_mask = 0x0fffffff,
490 .instr_val = 0x07f001f0,
491 .cpsr_mask = PSR_T_BIT,
492 .cpsr_val = 0,
493 .fn = break_trap,
494 };
495
496 static struct undef_hook thumb_break_hook = {
497 .instr_mask = 0xffff,
498 .instr_val = 0xde01,
499 .cpsr_mask = PSR_T_BIT,
500 .cpsr_val = PSR_T_BIT,
501 .fn = break_trap,
502 };
503
504 static int __init ptrace_break_init(void)
505 {
506 register_undef_hook(&arm_break_hook);
507 register_undef_hook(&thumb_break_hook);
508 return 0;
509 }
510
511 core_initcall(ptrace_break_init);
512
513 /*
514 * Read the word at offset "off" into the "struct user". We
515 * actually access the pt_regs stored on the kernel stack.
516 */
517 static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
518 unsigned long __user *ret)
519 {
520 unsigned long tmp;
521
522 if (off & 3 || off >= sizeof(struct user))
523 return -EIO;
524
525 tmp = 0;
526 if (off < sizeof(struct pt_regs))
527 tmp = get_user_reg(tsk, off >> 2);
528
529 return put_user(tmp, ret);
530 }
531
532 /*
533 * Write the word at offset "off" into "struct user". We
534 * actually access the pt_regs stored on the kernel stack.
535 */
536 static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
537 unsigned long val)
538 {
539 if (off & 3 || off >= sizeof(struct user))
540 return -EIO;
541
542 if (off >= sizeof(struct pt_regs))
543 return 0;
544
545 return put_user_reg(tsk, off >> 2, val);
546 }
547
548 /*
549 * Get all user integer registers.
550 */
551 static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
552 {
553 struct pt_regs *regs = task_pt_regs(tsk);
554
555 return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
556 }
557
558 /*
559 * Set all user integer registers.
560 */
561 static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
562 {
563 struct pt_regs newregs;
564 int ret;
565
566 ret = -EFAULT;
567 if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
568 struct pt_regs *regs = task_pt_regs(tsk);
569
570 ret = -EINVAL;
571 if (valid_user_regs(&newregs)) {
572 *regs = newregs;
573 ret = 0;
574 }
575 }
576
577 return ret;
578 }
579
580 /*
581 * Get the child FPU state.
582 */
583 static int ptrace_getfpregs(struct task_struct *tsk, void __user *ufp)
584 {
585 return copy_to_user(ufp, &task_thread_info(tsk)->fpstate,
586 sizeof(struct user_fp)) ? -EFAULT : 0;
587 }
588
589 /*
590 * Set the child FPU state.
591 */
592 static int ptrace_setfpregs(struct task_struct *tsk, void __user *ufp)
593 {
594 struct thread_info *thread = task_thread_info(tsk);
595 thread->used_cp[1] = thread->used_cp[2] = 1;
596 return copy_from_user(&thread->fpstate, ufp,
597 sizeof(struct user_fp)) ? -EFAULT : 0;
598 }
599
600 #ifdef CONFIG_IWMMXT
601
602 /*
603 * Get the child iWMMXt state.
604 */
605 static int ptrace_getwmmxregs(struct task_struct *tsk, void __user *ufp)
606 {
607 struct thread_info *thread = task_thread_info(tsk);
608
609 if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
610 return -ENODATA;
611 iwmmxt_task_disable(thread); /* force it to ram */
612 return copy_to_user(ufp, &thread->fpstate.iwmmxt, IWMMXT_SIZE)
613 ? -EFAULT : 0;
614 }
615
616 /*
617 * Set the child iWMMXt state.
618 */
619 static int ptrace_setwmmxregs(struct task_struct *tsk, void __user *ufp)
620 {
621 struct thread_info *thread = task_thread_info(tsk);
622
623 if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
624 return -EACCES;
625 iwmmxt_task_release(thread); /* force a reload */
626 return copy_from_user(&thread->fpstate.iwmmxt, ufp, IWMMXT_SIZE)
627 ? -EFAULT : 0;
628 }
629
630 #endif
631
632 #ifdef CONFIG_CRUNCH
633 /*
634 * Get the child Crunch state.
635 */
636 static int ptrace_getcrunchregs(struct task_struct *tsk, void __user *ufp)
637 {
638 struct thread_info *thread = task_thread_info(tsk);
639
640 crunch_task_disable(thread); /* force it to ram */
641 return copy_to_user(ufp, &thread->crunchstate, CRUNCH_SIZE)
642 ? -EFAULT : 0;
643 }
644
645 /*
646 * Set the child Crunch state.
647 */
648 static int ptrace_setcrunchregs(struct task_struct *tsk, void __user *ufp)
649 {
650 struct thread_info *thread = task_thread_info(tsk);
651
652 crunch_task_release(thread); /* force a reload */
653 return copy_from_user(&thread->crunchstate, ufp, CRUNCH_SIZE)
654 ? -EFAULT : 0;
655 }
656 #endif
657
658 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
659 {
660 unsigned long tmp;
661 int ret;
662
663 switch (request) {
664 /*
665 * read word at location "addr" in the child process.
666 */
667 case PTRACE_PEEKTEXT:
668 case PTRACE_PEEKDATA:
669 ret = access_process_vm(child, addr, &tmp,
670 sizeof(unsigned long), 0);
671 if (ret == sizeof(unsigned long))
672 ret = put_user(tmp, (unsigned long __user *) data);
673 else
674 ret = -EIO;
675 break;
676
677 case PTRACE_PEEKUSR:
678 ret = ptrace_read_user(child, addr, (unsigned long __user *)data);
679 break;
680
681 /*
682 * write the word at location addr.
683 */
684 case PTRACE_POKETEXT:
685 case PTRACE_POKEDATA:
686 ret = access_process_vm(child, addr, &data,
687 sizeof(unsigned long), 1);
688 if (ret == sizeof(unsigned long))
689 ret = 0;
690 else
691 ret = -EIO;
692 break;
693
694 case PTRACE_POKEUSR:
695 ret = ptrace_write_user(child, addr, data);
696 break;
697
698 /*
699 * continue/restart and stop at next (return from) syscall
700 */
701 case PTRACE_SYSCALL:
702 case PTRACE_CONT:
703 ret = -EIO;
704 if (!valid_signal(data))
705 break;
706 if (request == PTRACE_SYSCALL)
707 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
708 else
709 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
710 child->exit_code = data;
711 single_step_disable(child);
712 wake_up_process(child);
713 ret = 0;
714 break;
715
716 /*
717 * make the child exit. Best I can do is send it a sigkill.
718 * perhaps it should be put in the status that it wants to
719 * exit.
720 */
721 case PTRACE_KILL:
722 single_step_disable(child);
723 if (child->exit_state != EXIT_ZOMBIE) {
724 child->exit_code = SIGKILL;
725 wake_up_process(child);
726 }
727 ret = 0;
728 break;
729
730 /*
731 * execute single instruction.
732 */
733 case PTRACE_SINGLESTEP:
734 ret = -EIO;
735 if (!valid_signal(data))
736 break;
737 single_step_enable(child);
738 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
739 child->exit_code = data;
740 /* give it a chance to run. */
741 wake_up_process(child);
742 ret = 0;
743 break;
744
745 case PTRACE_DETACH:
746 ret = ptrace_detach(child, data);
747 break;
748
749 case PTRACE_GETREGS:
750 ret = ptrace_getregs(child, (void __user *)data);
751 break;
752
753 case PTRACE_SETREGS:
754 ret = ptrace_setregs(child, (void __user *)data);
755 break;
756
757 case PTRACE_GETFPREGS:
758 ret = ptrace_getfpregs(child, (void __user *)data);
759 break;
760
761 case PTRACE_SETFPREGS:
762 ret = ptrace_setfpregs(child, (void __user *)data);
763 break;
764
765 #ifdef CONFIG_IWMMXT
766 case PTRACE_GETWMMXREGS:
767 ret = ptrace_getwmmxregs(child, (void __user *)data);
768 break;
769
770 case PTRACE_SETWMMXREGS:
771 ret = ptrace_setwmmxregs(child, (void __user *)data);
772 break;
773 #endif
774
775 case PTRACE_GET_THREAD_AREA:
776 ret = put_user(task_thread_info(child)->tp_value,
777 (unsigned long __user *) data);
778 break;
779
780 case PTRACE_SET_SYSCALL:
781 task_thread_info(child)->syscall = data;
782 ret = 0;
783 break;
784
785 #ifdef CONFIG_CRUNCH
786 case PTRACE_GETCRUNCHREGS:
787 ret = ptrace_getcrunchregs(child, (void __user *)data);
788 break;
789
790 case PTRACE_SETCRUNCHREGS:
791 ret = ptrace_setcrunchregs(child, (void __user *)data);
792 break;
793 #endif
794
795 default:
796 ret = ptrace_request(child, request, addr, data);
797 break;
798 }
799
800 return ret;
801 }
802
803 asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
804 {
805 unsigned long ip;
806
807 if (!test_thread_flag(TIF_SYSCALL_TRACE))
808 return scno;
809 if (!(current->ptrace & PT_PTRACED))
810 return scno;
811
812 /*
813 * Save IP. IP is used to denote syscall entry/exit:
814 * IP = 0 -> entry, = 1 -> exit
815 */
816 ip = regs->ARM_ip;
817 regs->ARM_ip = why;
818
819 current_thread_info()->syscall = scno;
820
821 /* the 0x80 provides a way for the tracing parent to distinguish
822 between a syscall stop and SIGTRAP delivery */
823 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
824 ? 0x80 : 0));
825 /*
826 * this isn't the same as continuing with a signal, but it will do
827 * for normal use. strace only continues with a signal if the
828 * stopping signal is not SIGTRAP. -brl
829 */
830 if (current->exit_code) {
831 send_sig(current->exit_code, current, 1);
832 current->exit_code = 0;
833 }
834 regs->ARM_ip = ip;
835
836 return current_thread_info()->syscall;
837 }
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