[AGPGART] Add missing calls to global_flush_tlb() to ali-agp
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / kprobes.c
blobd25a9ada3f8eb57c8b6ab2ac43e7123fb49ffa9f
1 /*
2 * Kernel Probes (KProbes)
3 * kernel/kprobes.c
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.
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.
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.
19 * Copyright (C) IBM Corporation, 2002, 2004
21 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
22 * Probes initial implementation (includes suggestions from
23 * Rusty Russell).
24 * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
25 * hlists and exceptions notifier as suggested by Andi Kleen.
26 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
27 * interface to access function arguments.
28 * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
29 * exceptions notifier to be first on the priority list.
30 * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
31 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
32 * <prasanna@in.ibm.com> added function-return probes.
34 #include <linux/kprobes.h>
35 #include <linux/hash.h>
36 #include <linux/init.h>
37 #include <linux/slab.h>
38 #include <linux/module.h>
39 #include <linux/moduleloader.h>
40 #include <linux/kallsyms.h>
41 #include <linux/freezer.h>
42 #include <linux/seq_file.h>
43 #include <linux/debugfs.h>
44 #include <asm-generic/sections.h>
45 #include <asm/cacheflush.h>
46 #include <asm/errno.h>
47 #include <asm/kdebug.h>
49 #define KPROBE_HASH_BITS 6
50 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
54 * Some oddball architectures like 64bit powerpc have function descriptors
55 * so this must be overridable.
57 #ifndef kprobe_lookup_name
58 #define kprobe_lookup_name(name, addr) \
59 addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
60 #endif
62 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
63 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
64 static atomic_t kprobe_count;
66 DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */
67 DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */
68 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
70 static struct notifier_block kprobe_page_fault_nb = {
71 .notifier_call = kprobe_exceptions_notify,
72 .priority = 0x7fffffff /* we need to notified first */
75 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
77 * kprobe->ainsn.insn points to the copy of the instruction to be
78 * single-stepped. x86_64, POWER4 and above have no-exec support and
79 * stepping on the instruction on a vmalloced/kmalloced/data page
80 * is a recipe for disaster
82 #define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
84 struct kprobe_insn_page {
85 struct hlist_node hlist;
86 kprobe_opcode_t *insns; /* Page of instruction slots */
87 char slot_used[INSNS_PER_PAGE];
88 int nused;
89 int ngarbage;
92 enum kprobe_slot_state {
93 SLOT_CLEAN = 0,
94 SLOT_DIRTY = 1,
95 SLOT_USED = 2,
98 static struct hlist_head kprobe_insn_pages;
99 static int kprobe_garbage_slots;
100 static int collect_garbage_slots(void);
102 static int __kprobes check_safety(void)
104 int ret = 0;
105 #if defined(CONFIG_PREEMPT) && defined(CONFIG_PM)
106 ret = freeze_processes();
107 if (ret == 0) {
108 struct task_struct *p, *q;
109 do_each_thread(p, q) {
110 if (p != current && p->state == TASK_RUNNING &&
111 p->pid != 0) {
112 printk("Check failed: %s is running\n",p->comm);
113 ret = -1;
114 goto loop_end;
116 } while_each_thread(p, q);
118 loop_end:
119 thaw_processes();
120 #else
121 synchronize_sched();
122 #endif
123 return ret;
127 * get_insn_slot() - Find a slot on an executable page for an instruction.
128 * We allocate an executable page if there's no room on existing ones.
130 kprobe_opcode_t __kprobes *get_insn_slot(void)
132 struct kprobe_insn_page *kip;
133 struct hlist_node *pos;
135 retry:
136 hlist_for_each(pos, &kprobe_insn_pages) {
137 kip = hlist_entry(pos, struct kprobe_insn_page, hlist);
138 if (kip->nused < INSNS_PER_PAGE) {
139 int i;
140 for (i = 0; i < INSNS_PER_PAGE; i++) {
141 if (kip->slot_used[i] == SLOT_CLEAN) {
142 kip->slot_used[i] = SLOT_USED;
143 kip->nused++;
144 return kip->insns + (i * MAX_INSN_SIZE);
147 /* Surprise! No unused slots. Fix kip->nused. */
148 kip->nused = INSNS_PER_PAGE;
152 /* If there are any garbage slots, collect it and try again. */
153 if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
154 goto retry;
156 /* All out of space. Need to allocate a new page. Use slot 0. */
157 kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
158 if (!kip) {
159 return NULL;
163 * Use module_alloc so this page is within +/- 2GB of where the
164 * kernel image and loaded module images reside. This is required
165 * so x86_64 can correctly handle the %rip-relative fixups.
167 kip->insns = module_alloc(PAGE_SIZE);
168 if (!kip->insns) {
169 kfree(kip);
170 return NULL;
172 INIT_HLIST_NODE(&kip->hlist);
173 hlist_add_head(&kip->hlist, &kprobe_insn_pages);
174 memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
175 kip->slot_used[0] = SLOT_USED;
176 kip->nused = 1;
177 kip->ngarbage = 0;
178 return kip->insns;
181 /* Return 1 if all garbages are collected, otherwise 0. */
182 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
184 kip->slot_used[idx] = SLOT_CLEAN;
185 kip->nused--;
186 if (kip->nused == 0) {
188 * Page is no longer in use. Free it unless
189 * it's the last one. We keep the last one
190 * so as not to have to set it up again the
191 * next time somebody inserts a probe.
193 hlist_del(&kip->hlist);
194 if (hlist_empty(&kprobe_insn_pages)) {
195 INIT_HLIST_NODE(&kip->hlist);
196 hlist_add_head(&kip->hlist,
197 &kprobe_insn_pages);
198 } else {
199 module_free(NULL, kip->insns);
200 kfree(kip);
202 return 1;
204 return 0;
207 static int __kprobes collect_garbage_slots(void)
209 struct kprobe_insn_page *kip;
210 struct hlist_node *pos, *next;
212 /* Ensure no-one is preepmted on the garbages */
213 if (check_safety() != 0)
214 return -EAGAIN;
216 hlist_for_each_safe(pos, next, &kprobe_insn_pages) {
217 int i;
218 kip = hlist_entry(pos, struct kprobe_insn_page, hlist);
219 if (kip->ngarbage == 0)
220 continue;
221 kip->ngarbage = 0; /* we will collect all garbages */
222 for (i = 0; i < INSNS_PER_PAGE; i++) {
223 if (kip->slot_used[i] == SLOT_DIRTY &&
224 collect_one_slot(kip, i))
225 break;
228 kprobe_garbage_slots = 0;
229 return 0;
232 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
234 struct kprobe_insn_page *kip;
235 struct hlist_node *pos;
237 hlist_for_each(pos, &kprobe_insn_pages) {
238 kip = hlist_entry(pos, struct kprobe_insn_page, hlist);
239 if (kip->insns <= slot &&
240 slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
241 int i = (slot - kip->insns) / MAX_INSN_SIZE;
242 if (dirty) {
243 kip->slot_used[i] = SLOT_DIRTY;
244 kip->ngarbage++;
245 } else {
246 collect_one_slot(kip, i);
248 break;
251 if (dirty && (++kprobe_garbage_slots > INSNS_PER_PAGE)) {
252 collect_garbage_slots();
255 #endif
257 /* We have preemption disabled.. so it is safe to use __ versions */
258 static inline void set_kprobe_instance(struct kprobe *kp)
260 __get_cpu_var(kprobe_instance) = kp;
263 static inline void reset_kprobe_instance(void)
265 __get_cpu_var(kprobe_instance) = NULL;
269 * This routine is called either:
270 * - under the kprobe_mutex - during kprobe_[un]register()
271 * OR
272 * - with preemption disabled - from arch/xxx/kernel/kprobes.c
274 struct kprobe __kprobes *get_kprobe(void *addr)
276 struct hlist_head *head;
277 struct hlist_node *node;
278 struct kprobe *p;
280 head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
281 hlist_for_each_entry_rcu(p, node, head, hlist) {
282 if (p->addr == addr)
283 return p;
285 return NULL;
289 * Aggregate handlers for multiple kprobes support - these handlers
290 * take care of invoking the individual kprobe handlers on p->list
292 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
294 struct kprobe *kp;
296 list_for_each_entry_rcu(kp, &p->list, list) {
297 if (kp->pre_handler) {
298 set_kprobe_instance(kp);
299 if (kp->pre_handler(kp, regs))
300 return 1;
302 reset_kprobe_instance();
304 return 0;
307 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
308 unsigned long flags)
310 struct kprobe *kp;
312 list_for_each_entry_rcu(kp, &p->list, list) {
313 if (kp->post_handler) {
314 set_kprobe_instance(kp);
315 kp->post_handler(kp, regs, flags);
316 reset_kprobe_instance();
319 return;
322 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
323 int trapnr)
325 struct kprobe *cur = __get_cpu_var(kprobe_instance);
328 * if we faulted "during" the execution of a user specified
329 * probe handler, invoke just that probe's fault handler
331 if (cur && cur->fault_handler) {
332 if (cur->fault_handler(cur, regs, trapnr))
333 return 1;
335 return 0;
338 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
340 struct kprobe *cur = __get_cpu_var(kprobe_instance);
341 int ret = 0;
343 if (cur && cur->break_handler) {
344 if (cur->break_handler(cur, regs))
345 ret = 1;
347 reset_kprobe_instance();
348 return ret;
351 /* Walks the list and increments nmissed count for multiprobe case */
352 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
354 struct kprobe *kp;
355 if (p->pre_handler != aggr_pre_handler) {
356 p->nmissed++;
357 } else {
358 list_for_each_entry_rcu(kp, &p->list, list)
359 kp->nmissed++;
361 return;
364 /* Called with kretprobe_lock held */
365 struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp)
367 struct hlist_node *node;
368 struct kretprobe_instance *ri;
369 hlist_for_each_entry(ri, node, &rp->free_instances, uflist)
370 return ri;
371 return NULL;
374 /* Called with kretprobe_lock held */
375 static struct kretprobe_instance __kprobes *get_used_rp_inst(struct kretprobe
376 *rp)
378 struct hlist_node *node;
379 struct kretprobe_instance *ri;
380 hlist_for_each_entry(ri, node, &rp->used_instances, uflist)
381 return ri;
382 return NULL;
385 /* Called with kretprobe_lock held */
386 void __kprobes add_rp_inst(struct kretprobe_instance *ri)
389 * Remove rp inst off the free list -
390 * Add it back when probed function returns
392 hlist_del(&ri->uflist);
394 /* Add rp inst onto table */
395 INIT_HLIST_NODE(&ri->hlist);
396 hlist_add_head(&ri->hlist,
397 &kretprobe_inst_table[hash_ptr(ri->task, KPROBE_HASH_BITS)]);
399 /* Also add this rp inst to the used list. */
400 INIT_HLIST_NODE(&ri->uflist);
401 hlist_add_head(&ri->uflist, &ri->rp->used_instances);
404 /* Called with kretprobe_lock held */
405 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
406 struct hlist_head *head)
408 /* remove rp inst off the rprobe_inst_table */
409 hlist_del(&ri->hlist);
410 if (ri->rp) {
411 /* remove rp inst off the used list */
412 hlist_del(&ri->uflist);
413 /* put rp inst back onto the free list */
414 INIT_HLIST_NODE(&ri->uflist);
415 hlist_add_head(&ri->uflist, &ri->rp->free_instances);
416 } else
417 /* Unregistering */
418 hlist_add_head(&ri->hlist, head);
421 struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk)
423 return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
427 * This function is called from finish_task_switch when task tk becomes dead,
428 * so that we can recycle any function-return probe instances associated
429 * with this task. These left over instances represent probed functions
430 * that have been called but will never return.
432 void __kprobes kprobe_flush_task(struct task_struct *tk)
434 struct kretprobe_instance *ri;
435 struct hlist_head *head, empty_rp;
436 struct hlist_node *node, *tmp;
437 unsigned long flags = 0;
439 INIT_HLIST_HEAD(&empty_rp);
440 spin_lock_irqsave(&kretprobe_lock, flags);
441 head = kretprobe_inst_table_head(tk);
442 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
443 if (ri->task == tk)
444 recycle_rp_inst(ri, &empty_rp);
446 spin_unlock_irqrestore(&kretprobe_lock, flags);
448 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
449 hlist_del(&ri->hlist);
450 kfree(ri);
454 static inline void free_rp_inst(struct kretprobe *rp)
456 struct kretprobe_instance *ri;
457 while ((ri = get_free_rp_inst(rp)) != NULL) {
458 hlist_del(&ri->uflist);
459 kfree(ri);
464 * Keep all fields in the kprobe consistent
466 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
468 memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
469 memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
473 * Add the new probe to old_p->list. Fail if this is the
474 * second jprobe at the address - two jprobes can't coexist
476 static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p)
478 if (p->break_handler) {
479 if (old_p->break_handler)
480 return -EEXIST;
481 list_add_tail_rcu(&p->list, &old_p->list);
482 old_p->break_handler = aggr_break_handler;
483 } else
484 list_add_rcu(&p->list, &old_p->list);
485 if (p->post_handler && !old_p->post_handler)
486 old_p->post_handler = aggr_post_handler;
487 return 0;
491 * Fill in the required fields of the "manager kprobe". Replace the
492 * earlier kprobe in the hlist with the manager kprobe
494 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
496 copy_kprobe(p, ap);
497 flush_insn_slot(ap);
498 ap->addr = p->addr;
499 ap->pre_handler = aggr_pre_handler;
500 ap->fault_handler = aggr_fault_handler;
501 if (p->post_handler)
502 ap->post_handler = aggr_post_handler;
503 if (p->break_handler)
504 ap->break_handler = aggr_break_handler;
506 INIT_LIST_HEAD(&ap->list);
507 list_add_rcu(&p->list, &ap->list);
509 hlist_replace_rcu(&p->hlist, &ap->hlist);
513 * This is the second or subsequent kprobe at the address - handle
514 * the intricacies
516 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
517 struct kprobe *p)
519 int ret = 0;
520 struct kprobe *ap;
522 if (old_p->pre_handler == aggr_pre_handler) {
523 copy_kprobe(old_p, p);
524 ret = add_new_kprobe(old_p, p);
525 } else {
526 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
527 if (!ap)
528 return -ENOMEM;
529 add_aggr_kprobe(ap, old_p);
530 copy_kprobe(ap, p);
531 ret = add_new_kprobe(ap, p);
533 return ret;
536 static int __kprobes in_kprobes_functions(unsigned long addr)
538 if (addr >= (unsigned long)__kprobes_text_start
539 && addr < (unsigned long)__kprobes_text_end)
540 return -EINVAL;
541 return 0;
544 static int __kprobes __register_kprobe(struct kprobe *p,
545 unsigned long called_from)
547 int ret = 0;
548 struct kprobe *old_p;
549 struct module *probed_mod;
552 * If we have a symbol_name argument look it up,
553 * and add it to the address. That way the addr
554 * field can either be global or relative to a symbol.
556 if (p->symbol_name) {
557 if (p->addr)
558 return -EINVAL;
559 kprobe_lookup_name(p->symbol_name, p->addr);
562 if (!p->addr)
563 return -EINVAL;
564 p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset);
566 if ((!kernel_text_address((unsigned long) p->addr)) ||
567 in_kprobes_functions((unsigned long) p->addr))
568 return -EINVAL;
570 p->mod_refcounted = 0;
571 /* Check are we probing a module */
572 if ((probed_mod = module_text_address((unsigned long) p->addr))) {
573 struct module *calling_mod = module_text_address(called_from);
574 /* We must allow modules to probe themself and
575 * in this case avoid incrementing the module refcount,
576 * so as to allow unloading of self probing modules.
578 if (calling_mod && (calling_mod != probed_mod)) {
579 if (unlikely(!try_module_get(probed_mod)))
580 return -EINVAL;
581 p->mod_refcounted = 1;
582 } else
583 probed_mod = NULL;
586 p->nmissed = 0;
587 mutex_lock(&kprobe_mutex);
588 old_p = get_kprobe(p->addr);
589 if (old_p) {
590 ret = register_aggr_kprobe(old_p, p);
591 if (!ret)
592 atomic_inc(&kprobe_count);
593 goto out;
596 if ((ret = arch_prepare_kprobe(p)) != 0)
597 goto out;
599 INIT_HLIST_NODE(&p->hlist);
600 hlist_add_head_rcu(&p->hlist,
601 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
603 if (atomic_add_return(1, &kprobe_count) == \
604 (ARCH_INACTIVE_KPROBE_COUNT + 1))
605 register_page_fault_notifier(&kprobe_page_fault_nb);
607 arch_arm_kprobe(p);
609 out:
610 mutex_unlock(&kprobe_mutex);
612 if (ret && probed_mod)
613 module_put(probed_mod);
614 return ret;
617 int __kprobes register_kprobe(struct kprobe *p)
619 return __register_kprobe(p,
620 (unsigned long)__builtin_return_address(0));
623 void __kprobes unregister_kprobe(struct kprobe *p)
625 struct module *mod;
626 struct kprobe *old_p, *list_p;
627 int cleanup_p;
629 mutex_lock(&kprobe_mutex);
630 old_p = get_kprobe(p->addr);
631 if (unlikely(!old_p)) {
632 mutex_unlock(&kprobe_mutex);
633 return;
635 if (p != old_p) {
636 list_for_each_entry_rcu(list_p, &old_p->list, list)
637 if (list_p == p)
638 /* kprobe p is a valid probe */
639 goto valid_p;
640 mutex_unlock(&kprobe_mutex);
641 return;
643 valid_p:
644 if ((old_p == p) || ((old_p->pre_handler == aggr_pre_handler) &&
645 (p->list.next == &old_p->list) &&
646 (p->list.prev == &old_p->list))) {
647 /* Only probe on the hash list */
648 arch_disarm_kprobe(p);
649 hlist_del_rcu(&old_p->hlist);
650 cleanup_p = 1;
651 } else {
652 list_del_rcu(&p->list);
653 cleanup_p = 0;
656 mutex_unlock(&kprobe_mutex);
658 synchronize_sched();
659 if (p->mod_refcounted &&
660 (mod = module_text_address((unsigned long)p->addr)))
661 module_put(mod);
663 if (cleanup_p) {
664 if (p != old_p) {
665 list_del_rcu(&p->list);
666 kfree(old_p);
668 arch_remove_kprobe(p);
669 } else {
670 mutex_lock(&kprobe_mutex);
671 if (p->break_handler)
672 old_p->break_handler = NULL;
673 if (p->post_handler){
674 list_for_each_entry_rcu(list_p, &old_p->list, list){
675 if (list_p->post_handler){
676 cleanup_p = 2;
677 break;
680 if (cleanup_p == 0)
681 old_p->post_handler = NULL;
683 mutex_unlock(&kprobe_mutex);
686 /* Call unregister_page_fault_notifier()
687 * if no probes are active
689 mutex_lock(&kprobe_mutex);
690 if (atomic_add_return(-1, &kprobe_count) == \
691 ARCH_INACTIVE_KPROBE_COUNT)
692 unregister_page_fault_notifier(&kprobe_page_fault_nb);
693 mutex_unlock(&kprobe_mutex);
694 return;
697 static struct notifier_block kprobe_exceptions_nb = {
698 .notifier_call = kprobe_exceptions_notify,
699 .priority = 0x7fffffff /* we need to be notified first */
703 int __kprobes register_jprobe(struct jprobe *jp)
705 /* Todo: Verify probepoint is a function entry point */
706 jp->kp.pre_handler = setjmp_pre_handler;
707 jp->kp.break_handler = longjmp_break_handler;
709 return __register_kprobe(&jp->kp,
710 (unsigned long)__builtin_return_address(0));
713 void __kprobes unregister_jprobe(struct jprobe *jp)
715 unregister_kprobe(&jp->kp);
718 #ifdef ARCH_SUPPORTS_KRETPROBES
721 * This kprobe pre_handler is registered with every kretprobe. When probe
722 * hits it will set up the return probe.
724 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
725 struct pt_regs *regs)
727 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
728 unsigned long flags = 0;
730 /*TODO: consider to only swap the RA after the last pre_handler fired */
731 spin_lock_irqsave(&kretprobe_lock, flags);
732 arch_prepare_kretprobe(rp, regs);
733 spin_unlock_irqrestore(&kretprobe_lock, flags);
734 return 0;
737 int __kprobes register_kretprobe(struct kretprobe *rp)
739 int ret = 0;
740 struct kretprobe_instance *inst;
741 int i;
743 rp->kp.pre_handler = pre_handler_kretprobe;
744 rp->kp.post_handler = NULL;
745 rp->kp.fault_handler = NULL;
746 rp->kp.break_handler = NULL;
748 /* Pre-allocate memory for max kretprobe instances */
749 if (rp->maxactive <= 0) {
750 #ifdef CONFIG_PREEMPT
751 rp->maxactive = max(10, 2 * NR_CPUS);
752 #else
753 rp->maxactive = NR_CPUS;
754 #endif
756 INIT_HLIST_HEAD(&rp->used_instances);
757 INIT_HLIST_HEAD(&rp->free_instances);
758 for (i = 0; i < rp->maxactive; i++) {
759 inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL);
760 if (inst == NULL) {
761 free_rp_inst(rp);
762 return -ENOMEM;
764 INIT_HLIST_NODE(&inst->uflist);
765 hlist_add_head(&inst->uflist, &rp->free_instances);
768 rp->nmissed = 0;
769 /* Establish function entry probe point */
770 if ((ret = __register_kprobe(&rp->kp,
771 (unsigned long)__builtin_return_address(0))) != 0)
772 free_rp_inst(rp);
773 return ret;
776 #else /* ARCH_SUPPORTS_KRETPROBES */
778 int __kprobes register_kretprobe(struct kretprobe *rp)
780 return -ENOSYS;
783 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
784 struct pt_regs *regs)
786 return 0;
789 #endif /* ARCH_SUPPORTS_KRETPROBES */
791 void __kprobes unregister_kretprobe(struct kretprobe *rp)
793 unsigned long flags;
794 struct kretprobe_instance *ri;
796 unregister_kprobe(&rp->kp);
797 /* No race here */
798 spin_lock_irqsave(&kretprobe_lock, flags);
799 while ((ri = get_used_rp_inst(rp)) != NULL) {
800 ri->rp = NULL;
801 hlist_del(&ri->uflist);
803 spin_unlock_irqrestore(&kretprobe_lock, flags);
804 free_rp_inst(rp);
807 static int __init init_kprobes(void)
809 int i, err = 0;
811 /* FIXME allocate the probe table, currently defined statically */
812 /* initialize all list heads */
813 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
814 INIT_HLIST_HEAD(&kprobe_table[i]);
815 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
817 atomic_set(&kprobe_count, 0);
819 err = arch_init_kprobes();
820 if (!err)
821 err = register_die_notifier(&kprobe_exceptions_nb);
823 return err;
826 #ifdef CONFIG_DEBUG_FS
827 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
828 const char *sym, int offset,char *modname)
830 char *kprobe_type;
832 if (p->pre_handler == pre_handler_kretprobe)
833 kprobe_type = "r";
834 else if (p->pre_handler == setjmp_pre_handler)
835 kprobe_type = "j";
836 else
837 kprobe_type = "k";
838 if (sym)
839 seq_printf(pi, "%p %s %s+0x%x %s\n", p->addr, kprobe_type,
840 sym, offset, (modname ? modname : " "));
841 else
842 seq_printf(pi, "%p %s %p\n", p->addr, kprobe_type, p->addr);
845 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
847 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
850 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
852 (*pos)++;
853 if (*pos >= KPROBE_TABLE_SIZE)
854 return NULL;
855 return pos;
858 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
860 /* Nothing to do */
863 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
865 struct hlist_head *head;
866 struct hlist_node *node;
867 struct kprobe *p, *kp;
868 const char *sym = NULL;
869 unsigned int i = *(loff_t *) v;
870 unsigned long size, offset = 0;
871 char *modname, namebuf[128];
873 head = &kprobe_table[i];
874 preempt_disable();
875 hlist_for_each_entry_rcu(p, node, head, hlist) {
876 sym = kallsyms_lookup((unsigned long)p->addr, &size,
877 &offset, &modname, namebuf);
878 if (p->pre_handler == aggr_pre_handler) {
879 list_for_each_entry_rcu(kp, &p->list, list)
880 report_probe(pi, kp, sym, offset, modname);
881 } else
882 report_probe(pi, p, sym, offset, modname);
884 preempt_enable();
885 return 0;
888 static struct seq_operations kprobes_seq_ops = {
889 .start = kprobe_seq_start,
890 .next = kprobe_seq_next,
891 .stop = kprobe_seq_stop,
892 .show = show_kprobe_addr
895 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
897 return seq_open(filp, &kprobes_seq_ops);
900 static struct file_operations debugfs_kprobes_operations = {
901 .open = kprobes_open,
902 .read = seq_read,
903 .llseek = seq_lseek,
904 .release = seq_release,
907 static int __kprobes debugfs_kprobe_init(void)
909 struct dentry *dir, *file;
911 dir = debugfs_create_dir("kprobes", NULL);
912 if (!dir)
913 return -ENOMEM;
915 file = debugfs_create_file("list", 0444, dir , 0 ,
916 &debugfs_kprobes_operations);
917 if (!file) {
918 debugfs_remove(dir);
919 return -ENOMEM;
922 return 0;
925 late_initcall(debugfs_kprobe_init);
926 #endif /* CONFIG_DEBUG_FS */
928 module_init(init_kprobes);
930 EXPORT_SYMBOL_GPL(register_kprobe);
931 EXPORT_SYMBOL_GPL(unregister_kprobe);
932 EXPORT_SYMBOL_GPL(register_jprobe);
933 EXPORT_SYMBOL_GPL(unregister_jprobe);
934 EXPORT_SYMBOL_GPL(jprobe_return);
935 EXPORT_SYMBOL_GPL(register_kretprobe);
936 EXPORT_SYMBOL_GPL(unregister_kretprobe);