Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  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,
386                                 task_pid_nr(task), 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,
394                                 task_pid_nr(task), 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         int ret;
661 
662         switch (request) {
663                 /*
664                  * read word at location "addr" in the child process.
665                  */
666                 case PTRACE_PEEKTEXT:
667                 case PTRACE_PEEKDATA:
668                         ret = generic_ptrace_peekdata(child, addr, data);
669                         break;
670 
671                 case PTRACE_PEEKUSR:
672                         ret = ptrace_read_user(child, addr, (unsigned long __user *)data);
673                         break;
674 
675                 /*
676                  * write the word at location addr.
677                  */
678                 case PTRACE_POKETEXT:
679                 case PTRACE_POKEDATA:
680                         ret = generic_ptrace_pokedata(child, addr, data);
681                         break;
682 
683                 case PTRACE_POKEUSR:
684                         ret = ptrace_write_user(child, addr, data);
685                         break;
686 
687                 /*
688                  * continue/restart and stop at next (return from) syscall
689                  */
690                 case PTRACE_SYSCALL:
691                 case PTRACE_CONT:
692                         ret = -EIO;
693                         if (!valid_signal(data))
694                                 break;
695                         if (request == PTRACE_SYSCALL)
696                                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
697                         else
698                                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
699                         child->exit_code = data;
700                         single_step_disable(child);
701                         wake_up_process(child);
702                         ret = 0;
703                         break;
704 
705                 /*
706                  * make the child exit.  Best I can do is send it a sigkill.
707                  * perhaps it should be put in the status that it wants to
708                  * exit.
709                  */
710                 case PTRACE_KILL:
711                         single_step_disable(child);
712                         if (child->exit_state != EXIT_ZOMBIE) {
713                                 child->exit_code = SIGKILL;
714                                 wake_up_process(child);
715                         }
716                         ret = 0;
717                         break;
718 
719                 /*
720                  * execute single instruction.
721                  */
722                 case PTRACE_SINGLESTEP:
723                         ret = -EIO;
724                         if (!valid_signal(data))
725                                 break;
726                         single_step_enable(child);
727                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
728                         child->exit_code = data;
729                         /* give it a chance to run. */
730                         wake_up_process(child);
731                         ret = 0;
732                         break;
733 
734                 case PTRACE_GETREGS:
735                         ret = ptrace_getregs(child, (void __user *)data);
736                         break;
737 
738                 case PTRACE_SETREGS:
739                         ret = ptrace_setregs(child, (void __user *)data);
740                         break;
741 
742                 case PTRACE_GETFPREGS:
743                         ret = ptrace_getfpregs(child, (void __user *)data);
744                         break;
745                 
746                 case PTRACE_SETFPREGS:
747                         ret = ptrace_setfpregs(child, (void __user *)data);
748                         break;
749 
750 #ifdef CONFIG_IWMMXT
751                 case PTRACE_GETWMMXREGS:
752                         ret = ptrace_getwmmxregs(child, (void __user *)data);
753                         break;
754 
755                 case PTRACE_SETWMMXREGS:
756                         ret = ptrace_setwmmxregs(child, (void __user *)data);
757                         break;
758 #endif
759 
760                 case PTRACE_GET_THREAD_AREA:
761                         ret = put_user(task_thread_info(child)->tp_value,
762                                        (unsigned long __user *) data);
763                         break;
764 
765                 case PTRACE_SET_SYSCALL:
766                         task_thread_info(child)->syscall = data;
767                         ret = 0;
768                         break;
769 
770 #ifdef CONFIG_CRUNCH
771                 case PTRACE_GETCRUNCHREGS:
772                         ret = ptrace_getcrunchregs(child, (void __user *)data);
773                         break;
774 
775                 case PTRACE_SETCRUNCHREGS:
776                         ret = ptrace_setcrunchregs(child, (void __user *)data);
777                         break;
778 #endif
779 
780                 default:
781                         ret = ptrace_request(child, request, addr, data);
782                         break;
783         }
784 
785         return ret;
786 }
787 
788 asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
789 {
790         unsigned long ip;
791 
792         if (!test_thread_flag(TIF_SYSCALL_TRACE))
793                 return scno;
794         if (!(current->ptrace & PT_PTRACED))
795                 return scno;
796 
797         /*
798          * Save IP.  IP is used to denote syscall entry/exit:
799          *  IP = 0 -> entry, = 1 -> exit
800          */
801         ip = regs->ARM_ip;
802         regs->ARM_ip = why;
803 
804         current_thread_info()->syscall = scno;
805 
806         /* the 0x80 provides a way for the tracing parent to distinguish
807            between a syscall stop and SIGTRAP delivery */
808         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
809                                  ? 0x80 : 0));
810         /*
811          * this isn't the same as continuing with a signal, but it will do
812          * for normal use.  strace only continues with a signal if the
813          * stopping signal is not SIGTRAP.  -brl
814          */
815         if (current->exit_code) {
816                 send_sig(current->exit_code, current, 1);
817                 current->exit_code = 0;
818         }
819         regs->ARM_ip = ip;
820 
821         return current_thread_info()->syscall;
822 }
823 
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