kprobes: kretprobes simplifications
[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 #include <linux/kdebug.h>
33
34 #include <asm/pgtable.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         p->ainsn.slot = slot;
92
93         /* Check for Break instruction
94          * Bits 37:40 Major opcode to be zero
95          * Bits 27:32 X6 to be zero
96          * Bits 32:35 X3 to be zero
97          */
98         if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
99                 /* is a break instruction */
100                 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
101                 return;
102         }
103
104         if (bundle_encoding[template][slot] == B) {
105                 switch (major_opcode) {
106                   case INDIRECT_CALL_OPCODE:
107                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
108                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
109                         break;
110                   case IP_RELATIVE_PREDICT_OPCODE:
111                   case IP_RELATIVE_BRANCH_OPCODE:
112                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
113                         break;
114                   case IP_RELATIVE_CALL_OPCODE:
115                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
116                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
117                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
118                         break;
119                 }
120         } else if (bundle_encoding[template][slot] == X) {
121                 switch (major_opcode) {
122                   case LONG_CALL_OPCODE:
123                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
124                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
125                   break;
126                 }
127         }
128         return;
129 }
130
131 /*
132  * In this function we check to see if the instruction
133  * (qp) cmpx.crel.ctype p1,p2=r2,r3
134  * on which we are inserting kprobe is cmp instruction
135  * with ctype as unc.
136  */
137 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
138                                             uint major_opcode,
139                                             unsigned long kprobe_inst)
140 {
141         cmp_inst_t cmp_inst;
142         uint ctype_unc = 0;
143
144         if (!((bundle_encoding[template][slot] == I) ||
145                 (bundle_encoding[template][slot] == M)))
146                 goto out;
147
148         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
149                 (major_opcode == 0xE)))
150                 goto out;
151
152         cmp_inst.l = kprobe_inst;
153         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
154                 /* Integere compare - Register Register (A6 type)*/
155                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
156                                 &&(cmp_inst.f.c == 1))
157                         ctype_unc = 1;
158         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
159                 /* Integere compare - Immediate Register (A8 type)*/
160                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
161                         ctype_unc = 1;
162         }
163 out:
164         return ctype_unc;
165 }
166
167 /*
168  * In this function we check to see if the instruction
169  * on which we are inserting kprobe is supported.
170  * Returns qp value if supported
171  * Returns -EINVAL if unsupported
172  */
173 static int __kprobes unsupported_inst(uint template, uint  slot,
174                                       uint major_opcode,
175                                       unsigned long kprobe_inst,
176                                       unsigned long addr)
177 {
178         int qp;
179
180         qp = kprobe_inst & 0x3f;
181         if (is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst)) {
182                 if (slot == 1 && qp)  {
183                         printk(KERN_WARNING "Kprobes on cmp unc"
184                                         "instruction on slot 1 at <0x%lx>"
185                                         "is not supported\n", addr);
186                         return -EINVAL;
187
188                 }
189                 qp = 0;
190         }
191         else if (bundle_encoding[template][slot] == I) {
192                 if (major_opcode == 0) {
193                         /*
194                          * Check for Integer speculation instruction
195                          * - Bit 33-35 to be equal to 0x1
196                          */
197                         if (((kprobe_inst >> 33) & 0x7) == 1) {
198                                 printk(KERN_WARNING
199                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
200                                                 addr);
201                                 return -EINVAL;
202                         }
203                         /*
204                          * IP relative mov instruction
205                          *  - Bit 27-35 to be equal to 0x30
206                          */
207                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
208                                 printk(KERN_WARNING
209                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
210                                                 addr);
211                                 return -EINVAL;
212
213                         }
214                 }
215                 else if ((major_opcode == 5) && !(kprobe_inst & (0xFUl << 33)) &&
216                                 (kprobe_inst & (0x1UL << 12))) {
217                         /* test bit instructions, tbit,tnat,tf
218                          * bit 33-36 to be equal to 0
219                          * bit 12 to be equal to 1
220                          */
221                         if (slot == 1 && qp) {
222                                 printk(KERN_WARNING "Kprobes on test bit"
223                                                 "instruction on slot at <0x%lx>"
224                                                 "is not supported\n", addr);
225                                 return -EINVAL;
226                         }
227                         qp = 0;
228                 }
229         }
230         else if (bundle_encoding[template][slot] == B) {
231                 if (major_opcode == 7) {
232                         /* IP-Relative Predict major code is 7 */
233                         printk(KERN_WARNING "Kprobes on IP-Relative"
234                                         "Predict is not supported\n");
235                         return -EINVAL;
236                 }
237                 else if (major_opcode == 2) {
238                         /* Indirect Predict, major code is 2
239                          * bit 27-32 to be equal to 10 or 11
240                          */
241                         int x6=(kprobe_inst >> 27) & 0x3F;
242                         if ((x6 == 0x10) || (x6 == 0x11)) {
243                                 printk(KERN_WARNING "Kprobes on"
244                                         "Indirect Predict is not supported\n");
245                                 return -EINVAL;
246                         }
247                 }
248         }
249         /* kernel does not use float instruction, here for safety kprobe
250          * will judge whether it is fcmp/flass/float approximation instruction
251          */
252         else if (unlikely(bundle_encoding[template][slot] == F)) {
253                 if ((major_opcode == 4 || major_opcode == 5) &&
254                                 (kprobe_inst  & (0x1 << 12))) {
255                         /* fcmp/fclass unc instruction */
256                         if (slot == 1 && qp) {
257                                 printk(KERN_WARNING "Kprobes on fcmp/fclass "
258                                         "instruction on slot at <0x%lx> "
259                                         "is not supported\n", addr);
260                                 return -EINVAL;
261
262                         }
263                         qp = 0;
264                 }
265                 if ((major_opcode == 0 || major_opcode == 1) &&
266                         (kprobe_inst & (0x1UL << 33))) {
267                         /* float Approximation instruction */
268                         if (slot == 1 && qp) {
269                                 printk(KERN_WARNING "Kprobes on float Approx "
270                                         "instr at <0x%lx> is not supported\n",
271                                                 addr);
272                                 return -EINVAL;
273                         }
274                         qp = 0;
275                 }
276         }
277         return qp;
278 }
279
280 /*
281  * In this function we override the bundle with
282  * the break instruction at the given slot.
283  */
284 static void __kprobes prepare_break_inst(uint template, uint  slot,
285                                          uint major_opcode,
286                                          unsigned long kprobe_inst,
287                                          struct kprobe *p,
288                                          int qp)
289 {
290         unsigned long break_inst = BREAK_INST;
291         bundle_t *bundle = &p->opcode.bundle;
292
293         /*
294          * Copy the original kprobe_inst qualifying predicate(qp)
295          * to the break instruction
296          */
297         break_inst |= qp;
298
299         switch (slot) {
300           case 0:
301                 bundle->quad0.slot0 = break_inst;
302                 break;
303           case 1:
304                 bundle->quad0.slot1_p0 = break_inst;
305                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
306                 break;
307           case 2:
308                 bundle->quad1.slot2 = break_inst;
309                 break;
310         }
311
312         /*
313          * Update the instruction flag, so that we can
314          * emulate the instruction properly after we
315          * single step on original instruction
316          */
317         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
318 }
319
320 static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
321                 unsigned long *kprobe_inst, uint *major_opcode)
322 {
323         unsigned long kprobe_inst_p0, kprobe_inst_p1;
324         unsigned int template;
325
326         template = bundle->quad0.template;
327
328         switch (slot) {
329           case 0:
330                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
331                 *kprobe_inst = bundle->quad0.slot0;
332                   break;
333           case 1:
334                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
335                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
336                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
337                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
338                 break;
339           case 2:
340                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
341                 *kprobe_inst = bundle->quad1.slot2;
342                 break;
343         }
344 }
345
346 /* Returns non-zero if the addr is in the Interrupt Vector Table */
347 static int __kprobes in_ivt_functions(unsigned long addr)
348 {
349         return (addr >= (unsigned long)__start_ivt_text
350                 && addr < (unsigned long)__end_ivt_text);
351 }
352
353 static int __kprobes valid_kprobe_addr(int template, int slot,
354                                        unsigned long addr)
355 {
356         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
357                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
358                                 "at 0x%lx\n", addr);
359                 return -EINVAL;
360         }
361
362         if (in_ivt_functions(addr)) {
363                 printk(KERN_WARNING "Kprobes can't be inserted inside "
364                                 "IVT functions at 0x%lx\n", addr);
365                 return -EINVAL;
366         }
367
368         return 0;
369 }
370
371 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
372 {
373         kcb->prev_kprobe.kp = kprobe_running();
374         kcb->prev_kprobe.status = kcb->kprobe_status;
375 }
376
377 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
378 {
379         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
380         kcb->kprobe_status = kcb->prev_kprobe.status;
381 }
382
383 static void __kprobes set_current_kprobe(struct kprobe *p,
384                         struct kprobe_ctlblk *kcb)
385 {
386         __get_cpu_var(current_kprobe) = p;
387 }
388
389 static void kretprobe_trampoline(void)
390 {
391 }
392
393 /*
394  * At this point the target function has been tricked into
395  * returning into our trampoline.  Lookup the associated instance
396  * and then:
397  *    - call the handler function
398  *    - cleanup by marking the instance as unused
399  *    - long jump back to the original return address
400  */
401 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
402 {
403         struct kretprobe_instance *ri = NULL;
404         struct hlist_head *head, empty_rp;
405         struct hlist_node *node, *tmp;
406         unsigned long flags, orig_ret_address = 0;
407         unsigned long trampoline_address =
408                 ((struct fnptr *)kretprobe_trampoline)->ip;
409
410         INIT_HLIST_HEAD(&empty_rp);
411         spin_lock_irqsave(&kretprobe_lock, flags);
412         head = kretprobe_inst_table_head(current);
413
414         /*
415          * It is possible to have multiple instances associated with a given
416          * task either because an multiple functions in the call path
417          * have a return probe installed on them, and/or more then one return
418          * return probe was registered for a target function.
419          *
420          * We can handle this because:
421          *     - instances are always inserted at the head of the list
422          *     - when multiple return probes are registered for the same
423          *       function, the first instance's ret_addr will point to the
424          *       real return address, and all the rest will point to
425          *       kretprobe_trampoline
426          */
427         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
428                 if (ri->task != current)
429                         /* another task is sharing our hash bucket */
430                         continue;
431
432                 if (ri->rp && ri->rp->handler)
433                         ri->rp->handler(ri, regs);
434
435                 orig_ret_address = (unsigned long)ri->ret_addr;
436                 recycle_rp_inst(ri, &empty_rp);
437
438                 if (orig_ret_address != trampoline_address)
439                         /*
440                          * This is the real return address. Any other
441                          * instances associated with this task are for
442                          * other calls deeper on the call stack
443                          */
444                         break;
445         }
446
447         kretprobe_assert(ri, orig_ret_address, trampoline_address);
448
449         regs->cr_iip = orig_ret_address;
450
451         reset_current_kprobe();
452         spin_unlock_irqrestore(&kretprobe_lock, flags);
453         preempt_enable_no_resched();
454
455         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
456                 hlist_del(&ri->hlist);
457                 kfree(ri);
458         }
459         /*
460          * By returning a non-zero value, we are telling
461          * kprobe_handler() that we don't want the post_handler
462          * to run (and have re-enabled preemption)
463          */
464         return 1;
465 }
466
467 /* Called with kretprobe_lock held */
468 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
469                                       struct pt_regs *regs)
470 {
471         ri->ret_addr = (kprobe_opcode_t *)regs->b0;
472
473         /* Replace the return addr with trampoline addr */
474         regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
475 }
476
477 int __kprobes arch_prepare_kprobe(struct kprobe *p)
478 {
479         unsigned long addr = (unsigned long) p->addr;
480         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
481         unsigned long kprobe_inst=0;
482         unsigned int slot = addr & 0xf, template, major_opcode = 0;
483         bundle_t *bundle;
484         int qp;
485
486         bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
487         template = bundle->quad0.template;
488
489         if(valid_kprobe_addr(template, slot, addr))
490                 return -EINVAL;
491
492         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
493         if (slot == 1 && bundle_encoding[template][1] == L)
494                 slot++;
495
496         /* Get kprobe_inst and major_opcode from the bundle */
497         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
498
499         qp = unsupported_inst(template, slot, major_opcode, kprobe_inst, addr);
500         if (qp < 0)
501                 return -EINVAL;
502
503         p->ainsn.insn = get_insn_slot();
504         if (!p->ainsn.insn)
505                 return -ENOMEM;
506         memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
507         memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
508
509         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p, qp);
510
511         return 0;
512 }
513
514 void __kprobes arch_arm_kprobe(struct kprobe *p)
515 {
516         unsigned long arm_addr;
517         bundle_t *src, *dest;
518
519         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
520         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
521         src = &p->opcode.bundle;
522
523         flush_icache_range((unsigned long)p->ainsn.insn,
524                         (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
525         switch (p->ainsn.slot) {
526                 case 0:
527                         dest->quad0.slot0 = src->quad0.slot0;
528                         break;
529                 case 1:
530                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
531                         break;
532                 case 2:
533                         dest->quad1.slot2 = src->quad1.slot2;
534                         break;
535         }
536         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
537 }
538
539 void __kprobes arch_disarm_kprobe(struct kprobe *p)
540 {
541         unsigned long arm_addr;
542         bundle_t *src, *dest;
543
544         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
545         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
546         /* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
547         src = &p->ainsn.insn->bundle;
548         switch (p->ainsn.slot) {
549                 case 0:
550                         dest->quad0.slot0 = src->quad0.slot0;
551                         break;
552                 case 1:
553                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
554                         break;
555                 case 2:
556                         dest->quad1.slot2 = src->quad1.slot2;
557                         break;
558         }
559         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
560 }
561
562 void __kprobes arch_remove_kprobe(struct kprobe *p)
563 {
564         mutex_lock(&kprobe_mutex);
565         free_insn_slot(p->ainsn.insn, 0);
566         mutex_unlock(&kprobe_mutex);
567 }
568 /*
569  * We are resuming execution after a single step fault, so the pt_regs
570  * structure reflects the register state after we executed the instruction
571  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
572  * the ip to point back to the original stack address. To set the IP address
573  * to original stack address, handle the case where we need to fixup the
574  * relative IP address and/or fixup branch register.
575  */
576 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
577 {
578         unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
579         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
580         unsigned long template;
581         int slot = ((unsigned long)p->addr & 0xf);
582
583         template = p->ainsn.insn->bundle.quad0.template;
584
585         if (slot == 1 && bundle_encoding[template][1] == L)
586                 slot = 2;
587
588         if (p->ainsn.inst_flag) {
589
590                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
591                         /* Fix relative IP address */
592                         regs->cr_iip = (regs->cr_iip - bundle_addr) +
593                                         resume_addr;
594                 }
595
596                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
597                 /*
598                  * Fix target branch register, software convention is
599                  * to use either b0 or b6 or b7, so just checking
600                  * only those registers
601                  */
602                         switch (p->ainsn.target_br_reg) {
603                         case 0:
604                                 if ((regs->b0 == bundle_addr) ||
605                                         (regs->b0 == bundle_addr + 0x10)) {
606                                         regs->b0 = (regs->b0 - bundle_addr) +
607                                                 resume_addr;
608                                 }
609                                 break;
610                         case 6:
611                                 if ((regs->b6 == bundle_addr) ||
612                                         (regs->b6 == bundle_addr + 0x10)) {
613                                         regs->b6 = (regs->b6 - bundle_addr) +
614                                                 resume_addr;
615                                 }
616                                 break;
617                         case 7:
618                                 if ((regs->b7 == bundle_addr) ||
619                                         (regs->b7 == bundle_addr + 0x10)) {
620                                         regs->b7 = (regs->b7 - bundle_addr) +
621                                                 resume_addr;
622                                 }
623                                 break;
624                         } /* end switch */
625                 }
626                 goto turn_ss_off;
627         }
628
629         if (slot == 2) {
630                 if (regs->cr_iip == bundle_addr + 0x10) {
631                         regs->cr_iip = resume_addr + 0x10;
632                 }
633         } else {
634                 if (regs->cr_iip == bundle_addr) {
635                         regs->cr_iip = resume_addr;
636                 }
637         }
638
639 turn_ss_off:
640         /* Turn off Single Step bit */
641         ia64_psr(regs)->ss = 0;
642 }
643
644 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
645 {
646         unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
647         unsigned long slot = (unsigned long)p->addr & 0xf;
648
649         /* single step inline if break instruction */
650         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
651                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
652         else
653                 regs->cr_iip = bundle_addr & ~0xFULL;
654
655         if (slot > 2)
656                 slot = 0;
657
658         ia64_psr(regs)->ri = slot;
659
660         /* turn on single stepping */
661         ia64_psr(regs)->ss = 1;
662 }
663
664 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
665 {
666         unsigned int slot = ia64_psr(regs)->ri;
667         unsigned int template, major_opcode;
668         unsigned long kprobe_inst;
669         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
670         bundle_t bundle;
671
672         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
673         template = bundle.quad0.template;
674
675         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
676         if (slot == 1 && bundle_encoding[template][1] == L)
677                 slot++;
678
679         /* Get Kprobe probe instruction at given slot*/
680         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
681
682         /* For break instruction,
683          * Bits 37:40 Major opcode to be zero
684          * Bits 27:32 X6 to be zero
685          * Bits 32:35 X3 to be zero
686          */
687         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
688                 /* Not a break instruction */
689                 return 0;
690         }
691
692         /* Is a break instruction */
693         return 1;
694 }
695
696 static int __kprobes pre_kprobes_handler(struct die_args *args)
697 {
698         struct kprobe *p;
699         int ret = 0;
700         struct pt_regs *regs = args->regs;
701         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
702         struct kprobe_ctlblk *kcb;
703
704         /*
705          * We don't want to be preempted for the entire
706          * duration of kprobe processing
707          */
708         preempt_disable();
709         kcb = get_kprobe_ctlblk();
710
711         /* Handle recursion cases */
712         if (kprobe_running()) {
713                 p = get_kprobe(addr);
714                 if (p) {
715                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
716                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
717                                 ia64_psr(regs)->ss = 0;
718                                 goto no_kprobe;
719                         }
720                         /* We have reentered the pre_kprobe_handler(), since
721                          * another probe was hit while within the handler.
722                          * We here save the original kprobes variables and
723                          * just single step on the instruction of the new probe
724                          * without calling any user handlers.
725                          */
726                         save_previous_kprobe(kcb);
727                         set_current_kprobe(p, kcb);
728                         kprobes_inc_nmissed_count(p);
729                         prepare_ss(p, regs);
730                         kcb->kprobe_status = KPROBE_REENTER;
731                         return 1;
732                 } else if (args->err == __IA64_BREAK_JPROBE) {
733                         /*
734                          * jprobe instrumented function just completed
735                          */
736                         p = __get_cpu_var(current_kprobe);
737                         if (p->break_handler && p->break_handler(p, regs)) {
738                                 goto ss_probe;
739                         }
740                 } else if (!is_ia64_break_inst(regs)) {
741                         /* The breakpoint instruction was removed by
742                          * another cpu right after we hit, no further
743                          * handling of this interrupt is appropriate
744                          */
745                         ret = 1;
746                         goto no_kprobe;
747                 } else {
748                         /* Not our break */
749                         goto no_kprobe;
750                 }
751         }
752
753         p = get_kprobe(addr);
754         if (!p) {
755                 if (!is_ia64_break_inst(regs)) {
756                         /*
757                          * The breakpoint instruction was removed right
758                          * after we hit it.  Another cpu has removed
759                          * either a probepoint or a debugger breakpoint
760                          * at this address.  In either case, no further
761                          * handling of this interrupt is appropriate.
762                          */
763                         ret = 1;
764
765                 }
766
767                 /* Not one of our break, let kernel handle it */
768                 goto no_kprobe;
769         }
770
771         set_current_kprobe(p, kcb);
772         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
773
774         if (p->pre_handler && p->pre_handler(p, regs))
775                 /*
776                  * Our pre-handler is specifically requesting that we just
777                  * do a return.  This is used for both the jprobe pre-handler
778                  * and the kretprobe trampoline
779                  */
780                 return 1;
781
782 ss_probe:
783         prepare_ss(p, regs);
784         kcb->kprobe_status = KPROBE_HIT_SS;
785         return 1;
786
787 no_kprobe:
788         preempt_enable_no_resched();
789         return ret;
790 }
791
792 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
793 {
794         struct kprobe *cur = kprobe_running();
795         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
796
797         if (!cur)
798                 return 0;
799
800         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
801                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
802                 cur->post_handler(cur, regs, 0);
803         }
804
805         resume_execution(cur, regs);
806
807         /*Restore back the original saved kprobes variables and continue. */
808         if (kcb->kprobe_status == KPROBE_REENTER) {
809                 restore_previous_kprobe(kcb);
810                 goto out;
811         }
812         reset_current_kprobe();
813
814 out:
815         preempt_enable_no_resched();
816         return 1;
817 }
818
819 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
820 {
821         struct kprobe *cur = kprobe_running();
822         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
823
824
825         switch(kcb->kprobe_status) {
826         case KPROBE_HIT_SS:
827         case KPROBE_REENTER:
828                 /*
829                  * We are here because the instruction being single
830                  * stepped caused a page fault. We reset the current
831                  * kprobe and the instruction pointer points back to
832                  * the probe address and allow the page fault handler
833                  * to continue as a normal page fault.
834                  */
835                 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
836                 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
837                 if (kcb->kprobe_status == KPROBE_REENTER)
838                         restore_previous_kprobe(kcb);
839                 else
840                         reset_current_kprobe();
841                 preempt_enable_no_resched();
842                 break;
843         case KPROBE_HIT_ACTIVE:
844         case KPROBE_HIT_SSDONE:
845                 /*
846                  * We increment the nmissed count for accounting,
847                  * we can also use npre/npostfault count for accouting
848                  * these specific fault cases.
849                  */
850                 kprobes_inc_nmissed_count(cur);
851
852                 /*
853                  * We come here because instructions in the pre/post
854                  * handler caused the page_fault, this could happen
855                  * if handler tries to access user space by
856                  * copy_from_user(), get_user() etc. Let the
857                  * user-specified handler try to fix it first.
858                  */
859                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
860                         return 1;
861                 /*
862                  * In case the user-specified fault handler returned
863                  * zero, try to fix up.
864                  */
865                 if (ia64_done_with_exception(regs))
866                         return 1;
867
868                 /*
869                  * Let ia64_do_page_fault() fix it.
870                  */
871                 break;
872         default:
873                 break;
874         }
875
876         return 0;
877 }
878
879 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
880                                        unsigned long val, void *data)
881 {
882         struct die_args *args = (struct die_args *)data;
883         int ret = NOTIFY_DONE;
884
885         if (args->regs && user_mode(args->regs))
886                 return ret;
887
888         switch(val) {
889         case DIE_BREAK:
890                 /* err is break number from ia64_bad_break() */
891                 if ((args->err >> 12) == (__IA64_BREAK_KPROBE >> 12)
892                         || args->err == __IA64_BREAK_JPROBE
893                         || args->err == 0)
894                         if (pre_kprobes_handler(args))
895                                 ret = NOTIFY_STOP;
896                 break;
897         case DIE_FAULT:
898                 /* err is vector number from ia64_fault() */
899                 if (args->err == 36)
900                         if (post_kprobes_handler(args->regs))
901                                 ret = NOTIFY_STOP;
902                 break;
903         case DIE_PAGE_FAULT:
904                 /* kprobe_running() needs smp_processor_id() */
905                 preempt_disable();
906                 if (kprobe_running() &&
907                         kprobes_fault_handler(args->regs, args->trapnr))
908                         ret = NOTIFY_STOP;
909                 preempt_enable();
910         default:
911                 break;
912         }
913         return ret;
914 }
915
916 struct param_bsp_cfm {
917         unsigned long ip;
918         unsigned long *bsp;
919         unsigned long cfm;
920 };
921
922 static void ia64_get_bsp_cfm(struct unw_frame_info *info, void *arg)
923 {
924         unsigned long ip;
925         struct param_bsp_cfm *lp = arg;
926
927         do {
928                 unw_get_ip(info, &ip);
929                 if (ip == 0)
930                         break;
931                 if (ip == lp->ip) {
932                         unw_get_bsp(info, (unsigned long*)&lp->bsp);
933                         unw_get_cfm(info, (unsigned long*)&lp->cfm);
934                         return;
935                 }
936         } while (unw_unwind(info) >= 0);
937         lp->bsp = NULL;
938         lp->cfm = 0;
939         return;
940 }
941
942 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
943 {
944         struct jprobe *jp = container_of(p, struct jprobe, kp);
945         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
946         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
947         struct param_bsp_cfm pa;
948         int bytes;
949
950         /*
951          * Callee owns the argument space and could overwrite it, eg
952          * tail call optimization. So to be absolutely safe
953          * we save the argument space before transfering the control
954          * to instrumented jprobe function which runs in
955          * the process context
956          */
957         pa.ip = regs->cr_iip;
958         unw_init_running(ia64_get_bsp_cfm, &pa);
959         bytes = (char *)ia64_rse_skip_regs(pa.bsp, pa.cfm & 0x3f)
960                                 - (char *)pa.bsp;
961         memcpy( kcb->jprobes_saved_stacked_regs,
962                 pa.bsp,
963                 bytes );
964         kcb->bsp = pa.bsp;
965         kcb->cfm = pa.cfm;
966
967         /* save architectural state */
968         kcb->jprobe_saved_regs = *regs;
969
970         /* after rfi, execute the jprobe instrumented function */
971         regs->cr_iip = addr & ~0xFULL;
972         ia64_psr(regs)->ri = addr & 0xf;
973         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
974
975         /*
976          * fix the return address to our jprobe_inst_return() function
977          * in the jprobes.S file
978          */
979         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
980
981         return 1;
982 }
983
984 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
985 {
986         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
987         int bytes;
988
989         /* restoring architectural state */
990         *regs = kcb->jprobe_saved_regs;
991
992         /* restoring the original argument space */
993         flush_register_stack();
994         bytes = (char *)ia64_rse_skip_regs(kcb->bsp, kcb->cfm & 0x3f)
995                                 - (char *)kcb->bsp;
996         memcpy( kcb->bsp,
997                 kcb->jprobes_saved_stacked_regs,
998                 bytes );
999         invalidate_stacked_regs();
1000
1001         preempt_enable_no_resched();
1002         return 1;
1003 }
1004
1005 static struct kprobe trampoline_p = {
1006         .pre_handler = trampoline_probe_handler
1007 };
1008
1009 int __init arch_init_kprobes(void)
1010 {
1011         trampoline_p.addr =
1012                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
1013         return register_kprobe(&trampoline_p);
1014 }