4d592ee9300b2739d6c82f569f0b1a02254ee09e
[linux-2.6.git] / arch / ia64 / kernel / kprobes.c
1 /*
2  *  Kernel Probes (KProbes)
3  *  arch/ia64/kernel/kprobes.c
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18  *
19  * Copyright (C) IBM Corporation, 2002, 2004
20  * Copyright (C) Intel Corporation, 2005
21  *
22  * 2005-Apr     Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
23  *              <anil.s.keshavamurthy@intel.com> adapted from i386
24  */
25
26 #include <linux/kprobes.h>
27 #include <linux/ptrace.h>
28 #include <linux/string.h>
29 #include <linux/slab.h>
30 #include <linux/preempt.h>
31 #include <linux/moduleloader.h>
32
33 #include <asm/pgtable.h>
34 #include <asm/kdebug.h>
35 #include <asm/sections.h>
36 #include <asm/uaccess.h>
37
38 extern void jprobe_inst_return(void);
39
40 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
41 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
42
43 enum instruction_type {A, I, M, F, B, L, X, u};
44 static enum instruction_type bundle_encoding[32][3] = {
45   { M, I, I },                          /* 00 */
46   { M, I, I },                          /* 01 */
47   { M, I, I },                          /* 02 */
48   { M, I, I },                          /* 03 */
49   { M, L, X },                          /* 04 */
50   { M, L, X },                          /* 05 */
51   { u, u, u },                          /* 06 */
52   { u, u, u },                          /* 07 */
53   { M, M, I },                          /* 08 */
54   { M, M, I },                          /* 09 */
55   { M, M, I },                          /* 0A */
56   { M, M, I },                          /* 0B */
57   { M, F, I },                          /* 0C */
58   { M, F, I },                          /* 0D */
59   { M, M, F },                          /* 0E */
60   { M, M, F },                          /* 0F */
61   { M, I, B },                          /* 10 */
62   { M, I, B },                          /* 11 */
63   { M, B, B },                          /* 12 */
64   { M, B, B },                          /* 13 */
65   { u, u, u },                          /* 14 */
66   { u, u, u },                          /* 15 */
67   { B, B, B },                          /* 16 */
68   { B, B, B },                          /* 17 */
69   { M, M, B },                          /* 18 */
70   { M, M, B },                          /* 19 */
71   { u, u, u },                          /* 1A */
72   { u, u, u },                          /* 1B */
73   { M, F, B },                          /* 1C */
74   { M, F, B },                          /* 1D */
75   { u, u, u },                          /* 1E */
76   { u, u, u },                          /* 1F */
77 };
78
79 /*
80  * In this function we check to see if the instruction
81  * is IP relative instruction and update the kprobe
82  * inst flag accordingly
83  */
84 static void __kprobes update_kprobe_inst_flag(uint template, uint  slot,
85                                               uint major_opcode,
86                                               unsigned long kprobe_inst,
87                                               struct kprobe *p)
88 {
89         p->ainsn.inst_flag = 0;
90         p->ainsn.target_br_reg = 0;
91
92         /* Check for Break instruction
93          * Bits 37:40 Major opcode to be zero
94          * Bits 27:32 X6 to be zero
95          * Bits 32:35 X3 to be zero
96          */
97         if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
98                 /* is a break instruction */
99                 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
100                 return;
101         }
102
103         if (bundle_encoding[template][slot] == B) {
104                 switch (major_opcode) {
105                   case INDIRECT_CALL_OPCODE:
106                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
107                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
108                         break;
109                   case IP_RELATIVE_PREDICT_OPCODE:
110                   case IP_RELATIVE_BRANCH_OPCODE:
111                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
112                         break;
113                   case IP_RELATIVE_CALL_OPCODE:
114                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
115                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
116                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
117                         break;
118                 }
119         } else if (bundle_encoding[template][slot] == X) {
120                 switch (major_opcode) {
121                   case LONG_CALL_OPCODE:
122                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
123                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
124                   break;
125                 }
126         }
127         return;
128 }
129
130 /*
131  * In this function we check to see if the instruction
132  * on which we are inserting kprobe is supported.
133  * Returns 0 if supported
134  * Returns -EINVAL if unsupported
135  */
136 static int __kprobes unsupported_inst(uint template, uint  slot,
137                                       uint major_opcode,
138                                       unsigned long kprobe_inst,
139                                       unsigned long addr)
140 {
141         if (bundle_encoding[template][slot] == I) {
142                 switch (major_opcode) {
143                         case 0x0: //I_UNIT_MISC_OPCODE:
144                         /*
145                          * Check for Integer speculation instruction
146                          * - Bit 33-35 to be equal to 0x1
147                          */
148                         if (((kprobe_inst >> 33) & 0x7) == 1) {
149                                 printk(KERN_WARNING
150                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
151                                         addr);
152                                 return -EINVAL;
153                         }
154
155                         /*
156                          * IP relative mov instruction
157                          *  - Bit 27-35 to be equal to 0x30
158                          */
159                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
160                                 printk(KERN_WARNING
161                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
162                                         addr);
163                                 return -EINVAL;
164
165                         }
166                 }
167         }
168         return 0;
169 }
170
171
172 /*
173  * In this function we check to see if the instruction
174  * (qp) cmpx.crel.ctype p1,p2=r2,r3
175  * on which we are inserting kprobe is cmp instruction
176  * with ctype as unc.
177  */
178 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
179                                             uint major_opcode,
180                                             unsigned long kprobe_inst)
181 {
182         cmp_inst_t cmp_inst;
183         uint ctype_unc = 0;
184
185         if (!((bundle_encoding[template][slot] == I) ||
186                 (bundle_encoding[template][slot] == M)))
187                 goto out;
188
189         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
190                 (major_opcode == 0xE)))
191                 goto out;
192
193         cmp_inst.l = kprobe_inst;
194         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
195                 /* Integere compare - Register Register (A6 type)*/
196                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
197                                 &&(cmp_inst.f.c == 1))
198                         ctype_unc = 1;
199         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
200                 /* Integere compare - Immediate Register (A8 type)*/
201                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
202                         ctype_unc = 1;
203         }
204 out:
205         return ctype_unc;
206 }
207
208 /*
209  * In this function we override the bundle with
210  * the break instruction at the given slot.
211  */
212 static void __kprobes prepare_break_inst(uint template, uint  slot,
213                                          uint major_opcode,
214                                          unsigned long kprobe_inst,
215                                          struct kprobe *p)
216 {
217         unsigned long break_inst = BREAK_INST;
218         bundle_t *bundle = &p->opcode.bundle;
219
220         /*
221          * Copy the original kprobe_inst qualifying predicate(qp)
222          * to the break instruction iff !is_cmp_ctype_unc_inst
223          * because for cmp instruction with ctype equal to unc,
224          * which is a special instruction always needs to be
225          * executed regradless of qp
226          */
227         if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
228                 break_inst |= (0x3f & kprobe_inst);
229
230         switch (slot) {
231           case 0:
232                 bundle->quad0.slot0 = break_inst;
233                 break;
234           case 1:
235                 bundle->quad0.slot1_p0 = break_inst;
236                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
237                 break;
238           case 2:
239                 bundle->quad1.slot2 = break_inst;
240                 break;
241         }
242
243         /*
244          * Update the instruction flag, so that we can
245          * emulate the instruction properly after we
246          * single step on original instruction
247          */
248         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
249 }
250
251 static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
252                 unsigned long *kprobe_inst, uint *major_opcode)
253 {
254         unsigned long kprobe_inst_p0, kprobe_inst_p1;
255         unsigned int template;
256
257         template = bundle->quad0.template;
258
259         switch (slot) {
260           case 0:
261                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
262                 *kprobe_inst = bundle->quad0.slot0;
263                   break;
264           case 1:
265                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
266                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
267                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
268                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
269                 break;
270           case 2:
271                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
272                 *kprobe_inst = bundle->quad1.slot2;
273                 break;
274         }
275 }
276
277 /* Returns non-zero if the addr is in the Interrupt Vector Table */
278 static int __kprobes in_ivt_functions(unsigned long addr)
279 {
280         return (addr >= (unsigned long)__start_ivt_text
281                 && addr < (unsigned long)__end_ivt_text);
282 }
283
284 static int __kprobes valid_kprobe_addr(int template, int slot,
285                                        unsigned long addr)
286 {
287         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
288                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
289                                 "at 0x%lx\n", addr);
290                 return -EINVAL;
291         }
292
293         if (in_ivt_functions(addr)) {
294                 printk(KERN_WARNING "Kprobes can't be inserted inside "
295                                 "IVT functions at 0x%lx\n", addr);
296                 return -EINVAL;
297         }
298
299         if (slot == 1 && bundle_encoding[template][1] != L) {
300                 printk(KERN_WARNING "Inserting kprobes on slot #1 "
301                        "is not supported\n");
302                 return -EINVAL;
303         }
304
305         return 0;
306 }
307
308 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
309 {
310         kcb->prev_kprobe.kp = kprobe_running();
311         kcb->prev_kprobe.status = kcb->kprobe_status;
312 }
313
314 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
315 {
316         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
317         kcb->kprobe_status = kcb->prev_kprobe.status;
318 }
319
320 static void __kprobes set_current_kprobe(struct kprobe *p,
321                         struct kprobe_ctlblk *kcb)
322 {
323         __get_cpu_var(current_kprobe) = p;
324 }
325
326 static void kretprobe_trampoline(void)
327 {
328 }
329
330 /*
331  * At this point the target function has been tricked into
332  * returning into our trampoline.  Lookup the associated instance
333  * and then:
334  *    - call the handler function
335  *    - cleanup by marking the instance as unused
336  *    - long jump back to the original return address
337  */
338 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
339 {
340         struct kretprobe_instance *ri = NULL;
341         struct hlist_head *head, empty_rp;
342         struct hlist_node *node, *tmp;
343         unsigned long flags, orig_ret_address = 0;
344         unsigned long trampoline_address =
345                 ((struct fnptr *)kretprobe_trampoline)->ip;
346
347         INIT_HLIST_HEAD(&empty_rp);
348         spin_lock_irqsave(&kretprobe_lock, flags);
349         head = kretprobe_inst_table_head(current);
350
351         /*
352          * It is possible to have multiple instances associated with a given
353          * task either because an multiple functions in the call path
354          * have a return probe installed on them, and/or more then one return
355          * return probe was registered for a target function.
356          *
357          * We can handle this because:
358          *     - instances are always inserted at the head of the list
359          *     - when multiple return probes are registered for the same
360          *       function, the first instance's ret_addr will point to the
361          *       real return address, and all the rest will point to
362          *       kretprobe_trampoline
363          */
364         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
365                 if (ri->task != current)
366                         /* another task is sharing our hash bucket */
367                         continue;
368
369                 if (ri->rp && ri->rp->handler)
370                         ri->rp->handler(ri, regs);
371
372                 orig_ret_address = (unsigned long)ri->ret_addr;
373                 recycle_rp_inst(ri, &empty_rp);
374
375                 if (orig_ret_address != trampoline_address)
376                         /*
377                          * This is the real return address. Any other
378                          * instances associated with this task are for
379                          * other calls deeper on the call stack
380                          */
381                         break;
382         }
383
384         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
385         regs->cr_iip = orig_ret_address;
386
387         reset_current_kprobe();
388         spin_unlock_irqrestore(&kretprobe_lock, flags);
389         preempt_enable_no_resched();
390
391         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
392                 hlist_del(&ri->hlist);
393                 kfree(ri);
394         }
395         /*
396          * By returning a non-zero value, we are telling
397          * kprobe_handler() that we don't want the post_handler
398          * to run (and have re-enabled preemption)
399          */
400         return 1;
401 }
402
403 /* Called with kretprobe_lock held */
404 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
405                                       struct pt_regs *regs)
406 {
407         struct kretprobe_instance *ri;
408
409         if ((ri = get_free_rp_inst(rp)) != NULL) {
410                 ri->rp = rp;
411                 ri->task = current;
412                 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
413
414                 /* Replace the return addr with trampoline addr */
415                 regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
416
417                 add_rp_inst(ri);
418         } else {
419                 rp->nmissed++;
420         }
421 }
422
423 int __kprobes arch_prepare_kprobe(struct kprobe *p)
424 {
425         unsigned long addr = (unsigned long) p->addr;
426         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
427         unsigned long kprobe_inst=0;
428         unsigned int slot = addr & 0xf, template, major_opcode = 0;
429         bundle_t *bundle;
430
431         bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
432         template = bundle->quad0.template;
433
434         if(valid_kprobe_addr(template, slot, addr))
435                 return -EINVAL;
436
437         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
438         if (slot == 1 && bundle_encoding[template][1] == L)
439                 slot++;
440
441         /* Get kprobe_inst and major_opcode from the bundle */
442         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
443
444         if (unsupported_inst(template, slot, major_opcode, kprobe_inst, addr))
445                         return -EINVAL;
446
447
448         p->ainsn.insn = get_insn_slot();
449         if (!p->ainsn.insn)
450                 return -ENOMEM;
451         memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
452         memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
453
454         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
455
456         return 0;
457 }
458
459 void __kprobes arch_arm_kprobe(struct kprobe *p)
460 {
461         unsigned long addr = (unsigned long)p->addr;
462         unsigned long arm_addr = addr & ~0xFULL;
463
464         flush_icache_range((unsigned long)p->ainsn.insn,
465                         (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
466         memcpy((char *)arm_addr, &p->opcode, sizeof(kprobe_opcode_t));
467         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
468 }
469
470 void __kprobes arch_disarm_kprobe(struct kprobe *p)
471 {
472         unsigned long addr = (unsigned long)p->addr;
473         unsigned long arm_addr = addr & ~0xFULL;
474
475         /* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
476         memcpy((char *) arm_addr, (char *) p->ainsn.insn,
477                                          sizeof(kprobe_opcode_t));
478         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
479 }
480
481 void __kprobes arch_remove_kprobe(struct kprobe *p)
482 {
483         mutex_lock(&kprobe_mutex);
484         free_insn_slot(p->ainsn.insn, 0);
485         mutex_unlock(&kprobe_mutex);
486 }
487 /*
488  * We are resuming execution after a single step fault, so the pt_regs
489  * structure reflects the register state after we executed the instruction
490  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
491  * the ip to point back to the original stack address. To set the IP address
492  * to original stack address, handle the case where we need to fixup the
493  * relative IP address and/or fixup branch register.
494  */
495 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
496 {
497         unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
498         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
499         unsigned long template;
500         int slot = ((unsigned long)p->addr & 0xf);
501
502         template = p->ainsn.insn->bundle.quad0.template;
503
504         if (slot == 1 && bundle_encoding[template][1] == L)
505                 slot = 2;
506
507         if (p->ainsn.inst_flag) {
508
509                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
510                         /* Fix relative IP address */
511                         regs->cr_iip = (regs->cr_iip - bundle_addr) +
512                                         resume_addr;
513                 }
514
515                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
516                 /*
517                  * Fix target branch register, software convention is
518                  * to use either b0 or b6 or b7, so just checking
519                  * only those registers
520                  */
521                         switch (p->ainsn.target_br_reg) {
522                         case 0:
523                                 if ((regs->b0 == bundle_addr) ||
524                                         (regs->b0 == bundle_addr + 0x10)) {
525                                         regs->b0 = (regs->b0 - bundle_addr) +
526                                                 resume_addr;
527                                 }
528                                 break;
529                         case 6:
530                                 if ((regs->b6 == bundle_addr) ||
531                                         (regs->b6 == bundle_addr + 0x10)) {
532                                         regs->b6 = (regs->b6 - bundle_addr) +
533                                                 resume_addr;
534                                 }
535                                 break;
536                         case 7:
537                                 if ((regs->b7 == bundle_addr) ||
538                                         (regs->b7 == bundle_addr + 0x10)) {
539                                         regs->b7 = (regs->b7 - bundle_addr) +
540                                                 resume_addr;
541                                 }
542                                 break;
543                         } /* end switch */
544                 }
545                 goto turn_ss_off;
546         }
547
548         if (slot == 2) {
549                 if (regs->cr_iip == bundle_addr + 0x10) {
550                         regs->cr_iip = resume_addr + 0x10;
551                 }
552         } else {
553                 if (regs->cr_iip == bundle_addr) {
554                         regs->cr_iip = resume_addr;
555                 }
556         }
557
558 turn_ss_off:
559         /* Turn off Single Step bit */
560         ia64_psr(regs)->ss = 0;
561 }
562
563 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
564 {
565         unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
566         unsigned long slot = (unsigned long)p->addr & 0xf;
567
568         /* single step inline if break instruction */
569         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
570                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
571         else
572                 regs->cr_iip = bundle_addr & ~0xFULL;
573
574         if (slot > 2)
575                 slot = 0;
576
577         ia64_psr(regs)->ri = slot;
578
579         /* turn on single stepping */
580         ia64_psr(regs)->ss = 1;
581 }
582
583 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
584 {
585         unsigned int slot = ia64_psr(regs)->ri;
586         unsigned int template, major_opcode;
587         unsigned long kprobe_inst;
588         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
589         bundle_t bundle;
590
591         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
592         template = bundle.quad0.template;
593
594         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
595         if (slot == 1 && bundle_encoding[template][1] == L)
596                 slot++;
597
598         /* Get Kprobe probe instruction at given slot*/
599         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
600
601         /* For break instruction,
602          * Bits 37:40 Major opcode to be zero
603          * Bits 27:32 X6 to be zero
604          * Bits 32:35 X3 to be zero
605          */
606         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
607                 /* Not a break instruction */
608                 return 0;
609         }
610
611         /* Is a break instruction */
612         return 1;
613 }
614
615 static int __kprobes pre_kprobes_handler(struct die_args *args)
616 {
617         struct kprobe *p;
618         int ret = 0;
619         struct pt_regs *regs = args->regs;
620         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
621         struct kprobe_ctlblk *kcb;
622
623         /*
624          * We don't want to be preempted for the entire
625          * duration of kprobe processing
626          */
627         preempt_disable();
628         kcb = get_kprobe_ctlblk();
629
630         /* Handle recursion cases */
631         if (kprobe_running()) {
632                 p = get_kprobe(addr);
633                 if (p) {
634                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
635                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
636                                 ia64_psr(regs)->ss = 0;
637                                 goto no_kprobe;
638                         }
639                         /* We have reentered the pre_kprobe_handler(), since
640                          * another probe was hit while within the handler.
641                          * We here save the original kprobes variables and
642                          * just single step on the instruction of the new probe
643                          * without calling any user handlers.
644                          */
645                         save_previous_kprobe(kcb);
646                         set_current_kprobe(p, kcb);
647                         kprobes_inc_nmissed_count(p);
648                         prepare_ss(p, regs);
649                         kcb->kprobe_status = KPROBE_REENTER;
650                         return 1;
651                 } else if (args->err == __IA64_BREAK_JPROBE) {
652                         /*
653                          * jprobe instrumented function just completed
654                          */
655                         p = __get_cpu_var(current_kprobe);
656                         if (p->break_handler && p->break_handler(p, regs)) {
657                                 goto ss_probe;
658                         }
659                 } else if (!is_ia64_break_inst(regs)) {
660                         /* The breakpoint instruction was removed by
661                          * another cpu right after we hit, no further
662                          * handling of this interrupt is appropriate
663                          */
664                         ret = 1;
665                         goto no_kprobe;
666                 } else {
667                         /* Not our break */
668                         goto no_kprobe;
669                 }
670         }
671
672         p = get_kprobe(addr);
673         if (!p) {
674                 if (!is_ia64_break_inst(regs)) {
675                         /*
676                          * The breakpoint instruction was removed right
677                          * after we hit it.  Another cpu has removed
678                          * either a probepoint or a debugger breakpoint
679                          * at this address.  In either case, no further
680                          * handling of this interrupt is appropriate.
681                          */
682                         ret = 1;
683
684                 }
685
686                 /* Not one of our break, let kernel handle it */
687                 goto no_kprobe;
688         }
689
690         set_current_kprobe(p, kcb);
691         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
692
693         if (p->pre_handler && p->pre_handler(p, regs))
694                 /*
695                  * Our pre-handler is specifically requesting that we just
696                  * do a return.  This is used for both the jprobe pre-handler
697                  * and the kretprobe trampoline
698                  */
699                 return 1;
700
701 ss_probe:
702         prepare_ss(p, regs);
703         kcb->kprobe_status = KPROBE_HIT_SS;
704         return 1;
705
706 no_kprobe:
707         preempt_enable_no_resched();
708         return ret;
709 }
710
711 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
712 {
713         struct kprobe *cur = kprobe_running();
714         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
715
716         if (!cur)
717                 return 0;
718
719         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
720                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
721                 cur->post_handler(cur, regs, 0);
722         }
723
724         resume_execution(cur, regs);
725
726         /*Restore back the original saved kprobes variables and continue. */
727         if (kcb->kprobe_status == KPROBE_REENTER) {
728                 restore_previous_kprobe(kcb);
729                 goto out;
730         }
731         reset_current_kprobe();
732
733 out:
734         preempt_enable_no_resched();
735         return 1;
736 }
737
738 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
739 {
740         struct kprobe *cur = kprobe_running();
741         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
742
743
744         switch(kcb->kprobe_status) {
745         case KPROBE_HIT_SS:
746         case KPROBE_REENTER:
747                 /*
748                  * We are here because the instruction being single
749                  * stepped caused a page fault. We reset the current
750                  * kprobe and the instruction pointer points back to
751                  * the probe address and allow the page fault handler
752                  * to continue as a normal page fault.
753                  */
754                 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
755                 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
756                 if (kcb->kprobe_status == KPROBE_REENTER)
757                         restore_previous_kprobe(kcb);
758                 else
759                         reset_current_kprobe();
760                 preempt_enable_no_resched();
761                 break;
762         case KPROBE_HIT_ACTIVE:
763         case KPROBE_HIT_SSDONE:
764                 /*
765                  * We increment the nmissed count for accounting,
766                  * we can also use npre/npostfault count for accouting
767                  * these specific fault cases.
768                  */
769                 kprobes_inc_nmissed_count(cur);
770
771                 /*
772                  * We come here because instructions in the pre/post
773                  * handler caused the page_fault, this could happen
774                  * if handler tries to access user space by
775                  * copy_from_user(), get_user() etc. Let the
776                  * user-specified handler try to fix it first.
777                  */
778                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
779                         return 1;
780                 /*
781                  * In case the user-specified fault handler returned
782                  * zero, try to fix up.
783                  */
784                 if (ia64_done_with_exception(regs))
785                         return 1;
786
787                 /*
788                  * Let ia64_do_page_fault() fix it.
789                  */
790                 break;
791         default:
792                 break;
793         }
794
795         return 0;
796 }
797
798 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
799                                        unsigned long val, void *data)
800 {
801         struct die_args *args = (struct die_args *)data;
802         int ret = NOTIFY_DONE;
803
804         if (args->regs && user_mode(args->regs))
805                 return ret;
806
807         switch(val) {
808         case DIE_BREAK:
809                 /* err is break number from ia64_bad_break() */
810                 if (args->err == 0x80200 || args->err == 0x80300 || args->err == 0)
811                         if (pre_kprobes_handler(args))
812                                 ret = NOTIFY_STOP;
813                 break;
814         case DIE_FAULT:
815                 /* err is vector number from ia64_fault() */
816                 if (args->err == 36)
817                         if (post_kprobes_handler(args->regs))
818                                 ret = NOTIFY_STOP;
819                 break;
820         case DIE_PAGE_FAULT:
821                 /* kprobe_running() needs smp_processor_id() */
822                 preempt_disable();
823                 if (kprobe_running() &&
824                         kprobes_fault_handler(args->regs, args->trapnr))
825                         ret = NOTIFY_STOP;
826                 preempt_enable();
827         default:
828                 break;
829         }
830         return ret;
831 }
832
833 struct param_bsp_cfm {
834         unsigned long ip;
835         unsigned long *bsp;
836         unsigned long cfm;
837 };
838
839 static void ia64_get_bsp_cfm(struct unw_frame_info *info, void *arg)
840 {
841         unsigned long ip;
842         struct param_bsp_cfm *lp = arg;
843
844         do {
845                 unw_get_ip(info, &ip);
846                 if (ip == 0)
847                         break;
848                 if (ip == lp->ip) {
849                         unw_get_bsp(info, (unsigned long*)&lp->bsp);
850                         unw_get_cfm(info, (unsigned long*)&lp->cfm);
851                         return;
852                 }
853         } while (unw_unwind(info) >= 0);
854         lp->bsp = 0;
855         lp->cfm = 0;
856         return;
857 }
858
859 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
860 {
861         struct jprobe *jp = container_of(p, struct jprobe, kp);
862         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
863         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
864         struct param_bsp_cfm pa;
865         int bytes;
866
867         /*
868          * Callee owns the argument space and could overwrite it, eg
869          * tail call optimization. So to be absolutely safe
870          * we save the argument space before transfering the control
871          * to instrumented jprobe function which runs in
872          * the process context
873          */
874         pa.ip = regs->cr_iip;
875         unw_init_running(ia64_get_bsp_cfm, &pa);
876         bytes = (char *)ia64_rse_skip_regs(pa.bsp, pa.cfm & 0x3f)
877                                 - (char *)pa.bsp;
878         memcpy( kcb->jprobes_saved_stacked_regs,
879                 pa.bsp,
880                 bytes );
881         kcb->bsp = pa.bsp;
882         kcb->cfm = pa.cfm;
883
884         /* save architectural state */
885         kcb->jprobe_saved_regs = *regs;
886
887         /* after rfi, execute the jprobe instrumented function */
888         regs->cr_iip = addr & ~0xFULL;
889         ia64_psr(regs)->ri = addr & 0xf;
890         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
891
892         /*
893          * fix the return address to our jprobe_inst_return() function
894          * in the jprobes.S file
895          */
896         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
897
898         return 1;
899 }
900
901 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
902 {
903         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
904         int bytes;
905
906         /* restoring architectural state */
907         *regs = kcb->jprobe_saved_regs;
908
909         /* restoring the original argument space */
910         flush_register_stack();
911         bytes = (char *)ia64_rse_skip_regs(kcb->bsp, kcb->cfm & 0x3f)
912                                 - (char *)kcb->bsp;
913         memcpy( kcb->bsp,
914                 kcb->jprobes_saved_stacked_regs,
915                 bytes );
916         invalidate_stacked_regs();
917
918         preempt_enable_no_resched();
919         return 1;
920 }
921
922 static struct kprobe trampoline_p = {
923         .pre_handler = trampoline_probe_handler
924 };
925
926 int __init arch_init_kprobes(void)
927 {
928         trampoline_p.addr =
929                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
930         return register_kprobe(&trampoline_p);
931 }