blob: 3ea6325228dafd293b8421ac4d47ea49457b17a0 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Kernel Probes (KProbes)
3 * 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 *
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.
Hien Nguyenb94cce92005-06-23 00:09:19 -070030 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 */
34#include <linux/kprobes.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/hash.h>
36#include <linux/init.h>
Tim Schmielau4e57b682005-10-30 15:03:48 -080037#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038#include <linux/module.h>
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070039#include <linux/moduleloader.h>
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -070040#include <asm-generic/sections.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070041#include <asm/cacheflush.h>
42#include <asm/errno.h>
43#include <asm/kdebug.h>
44
45#define KPROBE_HASH_BITS 6
46#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
47
48static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
Hien Nguyenb94cce92005-06-23 00:09:19 -070049static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Ananth N Mavinakayanahalli0498b632006-01-09 20:52:46 -080051DECLARE_MUTEX(kprobe_mutex); /* Protects kprobe_table */
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -080052DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -080053static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
Anil S Keshavamurthy2d14e392006-01-09 20:52:41 -080055#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070056/*
57 * kprobe->ainsn.insn points to the copy of the instruction to be
58 * single-stepped. x86_64, POWER4 and above have no-exec support and
59 * stepping on the instruction on a vmalloced/kmalloced/data page
60 * is a recipe for disaster
61 */
62#define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
63
64struct kprobe_insn_page {
65 struct hlist_node hlist;
66 kprobe_opcode_t *insns; /* Page of instruction slots */
67 char slot_used[INSNS_PER_PAGE];
68 int nused;
69};
70
71static struct hlist_head kprobe_insn_pages;
72
73/**
74 * get_insn_slot() - Find a slot on an executable page for an instruction.
75 * We allocate an executable page if there's no room on existing ones.
76 */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -070077kprobe_opcode_t __kprobes *get_insn_slot(void)
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070078{
79 struct kprobe_insn_page *kip;
80 struct hlist_node *pos;
81
82 hlist_for_each(pos, &kprobe_insn_pages) {
83 kip = hlist_entry(pos, struct kprobe_insn_page, hlist);
84 if (kip->nused < INSNS_PER_PAGE) {
85 int i;
86 for (i = 0; i < INSNS_PER_PAGE; i++) {
87 if (!kip->slot_used[i]) {
88 kip->slot_used[i] = 1;
89 kip->nused++;
90 return kip->insns + (i * MAX_INSN_SIZE);
91 }
92 }
93 /* Surprise! No unused slots. Fix kip->nused. */
94 kip->nused = INSNS_PER_PAGE;
95 }
96 }
97
98 /* All out of space. Need to allocate a new page. Use slot 0.*/
99 kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
100 if (!kip) {
101 return NULL;
102 }
103
104 /*
105 * Use module_alloc so this page is within +/- 2GB of where the
106 * kernel image and loaded module images reside. This is required
107 * so x86_64 can correctly handle the %rip-relative fixups.
108 */
109 kip->insns = module_alloc(PAGE_SIZE);
110 if (!kip->insns) {
111 kfree(kip);
112 return NULL;
113 }
114 INIT_HLIST_NODE(&kip->hlist);
115 hlist_add_head(&kip->hlist, &kprobe_insn_pages);
116 memset(kip->slot_used, 0, INSNS_PER_PAGE);
117 kip->slot_used[0] = 1;
118 kip->nused = 1;
119 return kip->insns;
120}
121
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700122void __kprobes free_insn_slot(kprobe_opcode_t *slot)
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -0700123{
124 struct kprobe_insn_page *kip;
125 struct hlist_node *pos;
126
127 hlist_for_each(pos, &kprobe_insn_pages) {
128 kip = hlist_entry(pos, struct kprobe_insn_page, hlist);
129 if (kip->insns <= slot &&
130 slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
131 int i = (slot - kip->insns) / MAX_INSN_SIZE;
132 kip->slot_used[i] = 0;
133 kip->nused--;
134 if (kip->nused == 0) {
135 /*
136 * Page is no longer in use. Free it unless
137 * it's the last one. We keep the last one
138 * so as not to have to set it up again the
139 * next time somebody inserts a probe.
140 */
141 hlist_del(&kip->hlist);
142 if (hlist_empty(&kprobe_insn_pages)) {
143 INIT_HLIST_NODE(&kip->hlist);
144 hlist_add_head(&kip->hlist,
145 &kprobe_insn_pages);
146 } else {
147 module_free(NULL, kip->insns);
148 kfree(kip);
149 }
150 }
151 return;
152 }
153 }
154}
Anil S Keshavamurthy2d14e392006-01-09 20:52:41 -0800155#endif
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -0700156
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800157/* We have preemption disabled.. so it is safe to use __ versions */
158static inline void set_kprobe_instance(struct kprobe *kp)
159{
160 __get_cpu_var(kprobe_instance) = kp;
161}
162
163static inline void reset_kprobe_instance(void)
164{
165 __get_cpu_var(kprobe_instance) = NULL;
166}
167
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800168/*
169 * This routine is called either:
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800170 * - under the kprobe_mutex - during kprobe_[un]register()
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800171 * OR
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800172 * - with preemption disabled - from arch/xxx/kernel/kprobes.c
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800173 */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700174struct kprobe __kprobes *get_kprobe(void *addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175{
176 struct hlist_head *head;
177 struct hlist_node *node;
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800178 struct kprobe *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179
180 head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800181 hlist_for_each_entry_rcu(p, node, head, hlist) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 if (p->addr == addr)
183 return p;
184 }
185 return NULL;
186}
187
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700188/*
189 * Aggregate handlers for multiple kprobes support - these handlers
190 * take care of invoking the individual kprobe handlers on p->list
191 */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700192static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700193{
194 struct kprobe *kp;
195
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800196 list_for_each_entry_rcu(kp, &p->list, list) {
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700197 if (kp->pre_handler) {
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800198 set_kprobe_instance(kp);
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700199 if (kp->pre_handler(kp, regs))
200 return 1;
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700201 }
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800202 reset_kprobe_instance();
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700203 }
204 return 0;
205}
206
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700207static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
208 unsigned long flags)
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700209{
210 struct kprobe *kp;
211
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800212 list_for_each_entry_rcu(kp, &p->list, list) {
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700213 if (kp->post_handler) {
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800214 set_kprobe_instance(kp);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700215 kp->post_handler(kp, regs, flags);
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800216 reset_kprobe_instance();
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700217 }
218 }
219 return;
220}
221
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700222static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
223 int trapnr)
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700224{
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800225 struct kprobe *cur = __get_cpu_var(kprobe_instance);
226
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700227 /*
228 * if we faulted "during" the execution of a user specified
229 * probe handler, invoke just that probe's fault handler
230 */
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800231 if (cur && cur->fault_handler) {
232 if (cur->fault_handler(cur, regs, trapnr))
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700233 return 1;
234 }
235 return 0;
236}
237
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700238static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700239{
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800240 struct kprobe *cur = __get_cpu_var(kprobe_instance);
241 int ret = 0;
242
243 if (cur && cur->break_handler) {
244 if (cur->break_handler(cur, regs))
245 ret = 1;
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700246 }
Ananth N Mavinakayanahallie6584522005-11-07 01:00:07 -0800247 reset_kprobe_instance();
248 return ret;
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700249}
250
Keshavamurthy Anil Sbf8d5c52005-12-12 00:37:34 -0800251/* Walks the list and increments nmissed count for multiprobe case */
252void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
253{
254 struct kprobe *kp;
255 if (p->pre_handler != aggr_pre_handler) {
256 p->nmissed++;
257 } else {
258 list_for_each_entry_rcu(kp, &p->list, list)
259 kp->nmissed++;
260 }
261 return;
262}
263
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800264/* Called with kretprobe_lock held */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700265struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700266{
267 struct hlist_node *node;
268 struct kretprobe_instance *ri;
269 hlist_for_each_entry(ri, node, &rp->free_instances, uflist)
270 return ri;
271 return NULL;
272}
273
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800274/* Called with kretprobe_lock held */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700275static struct kretprobe_instance __kprobes *get_used_rp_inst(struct kretprobe
276 *rp)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700277{
278 struct hlist_node *node;
279 struct kretprobe_instance *ri;
280 hlist_for_each_entry(ri, node, &rp->used_instances, uflist)
281 return ri;
282 return NULL;
283}
284
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800285/* Called with kretprobe_lock held */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700286void __kprobes add_rp_inst(struct kretprobe_instance *ri)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700287{
Hien Nguyenb94cce92005-06-23 00:09:19 -0700288 /*
289 * Remove rp inst off the free list -
290 * Add it back when probed function returns
291 */
292 hlist_del(&ri->uflist);
Rusty Lynch802eae72005-06-27 15:17:08 -0700293
Hien Nguyenb94cce92005-06-23 00:09:19 -0700294 /* Add rp inst onto table */
295 INIT_HLIST_NODE(&ri->hlist);
296 hlist_add_head(&ri->hlist,
Rusty Lynch802eae72005-06-27 15:17:08 -0700297 &kretprobe_inst_table[hash_ptr(ri->task, KPROBE_HASH_BITS)]);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700298
299 /* Also add this rp inst to the used list. */
300 INIT_HLIST_NODE(&ri->uflist);
301 hlist_add_head(&ri->uflist, &ri->rp->used_instances);
302}
303
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800304/* Called with kretprobe_lock held */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700305void __kprobes recycle_rp_inst(struct kretprobe_instance *ri)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700306{
307 /* remove rp inst off the rprobe_inst_table */
308 hlist_del(&ri->hlist);
309 if (ri->rp) {
310 /* remove rp inst off the used list */
311 hlist_del(&ri->uflist);
312 /* put rp inst back onto the free list */
313 INIT_HLIST_NODE(&ri->uflist);
314 hlist_add_head(&ri->uflist, &ri->rp->free_instances);
315 } else
316 /* Unregistering */
317 kfree(ri);
318}
319
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700320struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700321{
322 return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
323}
324
Hien Nguyenb94cce92005-06-23 00:09:19 -0700325/*
Rusty Lynch802eae72005-06-27 15:17:08 -0700326 * This function is called from exit_thread or flush_thread when task tk's
327 * stack is being recycled so that we can recycle any function-return probe
328 * instances associated with this task. These left over instances represent
329 * probed functions that have been called but will never return.
Hien Nguyenb94cce92005-06-23 00:09:19 -0700330 */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700331void __kprobes kprobe_flush_task(struct task_struct *tk)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700332{
Rusty Lynch802eae72005-06-27 15:17:08 -0700333 struct kretprobe_instance *ri;
334 struct hlist_head *head;
335 struct hlist_node *node, *tmp;
Hien Nguyen0aa55e42005-06-23 00:09:26 -0700336 unsigned long flags = 0;
Rusty Lynch802eae72005-06-27 15:17:08 -0700337
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800338 spin_lock_irqsave(&kretprobe_lock, flags);
Rusty Lynch802eae72005-06-27 15:17:08 -0700339 head = kretprobe_inst_table_head(current);
340 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
341 if (ri->task == tk)
342 recycle_rp_inst(ri);
343 }
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800344 spin_unlock_irqrestore(&kretprobe_lock, flags);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700345}
346
347/*
348 * This kprobe pre_handler is registered with every kretprobe. When probe
349 * hits it will set up the return probe.
350 */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700351static int __kprobes pre_handler_kretprobe(struct kprobe *p,
352 struct pt_regs *regs)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700353{
354 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800355 unsigned long flags = 0;
Hien Nguyenb94cce92005-06-23 00:09:19 -0700356
357 /*TODO: consider to only swap the RA after the last pre_handler fired */
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800358 spin_lock_irqsave(&kretprobe_lock, flags);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700359 arch_prepare_kretprobe(rp, regs);
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800360 spin_unlock_irqrestore(&kretprobe_lock, flags);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700361 return 0;
362}
363
364static inline void free_rp_inst(struct kretprobe *rp)
365{
366 struct kretprobe_instance *ri;
367 while ((ri = get_free_rp_inst(rp)) != NULL) {
368 hlist_del(&ri->uflist);
369 kfree(ri);
370 }
371}
372
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700373/*
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700374 * Keep all fields in the kprobe consistent
375 */
376static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
377{
378 memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
379 memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
380}
381
382/*
383* Add the new probe to old_p->list. Fail if this is the
384* second jprobe at the address - two jprobes can't coexist
385*/
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700386static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p)
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700387{
388 struct kprobe *kp;
389
390 if (p->break_handler) {
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800391 list_for_each_entry_rcu(kp, &old_p->list, list) {
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700392 if (kp->break_handler)
393 return -EEXIST;
394 }
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800395 list_add_tail_rcu(&p->list, &old_p->list);
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700396 } else
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800397 list_add_rcu(&p->list, &old_p->list);
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700398 return 0;
399}
400
401/*
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700402 * Fill in the required fields of the "manager kprobe". Replace the
403 * earlier kprobe in the hlist with the manager kprobe
404 */
405static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
406{
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700407 copy_kprobe(p, ap);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700408 ap->addr = p->addr;
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700409 ap->pre_handler = aggr_pre_handler;
410 ap->post_handler = aggr_post_handler;
411 ap->fault_handler = aggr_fault_handler;
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700412 ap->break_handler = aggr_break_handler;
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700413
414 INIT_LIST_HEAD(&ap->list);
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800415 list_add_rcu(&p->list, &ap->list);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700416
Keshavamurthy Anil Sadad0f32005-12-12 00:37:12 -0800417 hlist_replace_rcu(&p->hlist, &ap->hlist);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700418}
419
420/*
421 * This is the second or subsequent kprobe at the address - handle
422 * the intricacies
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700423 */
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700424static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
425 struct kprobe *p)
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700426{
427 int ret = 0;
428 struct kprobe *ap;
429
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700430 if (old_p->pre_handler == aggr_pre_handler) {
431 copy_kprobe(old_p, p);
432 ret = add_new_kprobe(old_p, p);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700433 } else {
Keshavamurthy Anil Sa0d50062006-01-09 20:52:46 -0800434 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700435 if (!ap)
436 return -ENOMEM;
437 add_aggr_kprobe(ap, old_p);
Prasanna S Panchamukhi8b0914e2005-06-23 00:09:41 -0700438 copy_kprobe(ap, p);
439 ret = add_new_kprobe(ap, p);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700440 }
441 return ret;
442}
443
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700444static int __kprobes in_kprobes_functions(unsigned long addr)
445{
446 if (addr >= (unsigned long)__kprobes_text_start
447 && addr < (unsigned long)__kprobes_text_end)
448 return -EINVAL;
449 return 0;
450}
451
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800452static int __kprobes __register_kprobe(struct kprobe *p,
453 unsigned long called_from)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454{
455 int ret = 0;
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700456 struct kprobe *old_p;
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800457 struct module *probed_mod;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458
Mao, Bibob3e55c72005-12-12 00:37:00 -0800459 if ((!kernel_text_address((unsigned long) p->addr)) ||
460 in_kprobes_functions((unsigned long) p->addr))
461 return -EINVAL;
462
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800463 p->mod_refcounted = 0;
464 /* Check are we probing a module */
465 if ((probed_mod = module_text_address((unsigned long) p->addr))) {
466 struct module *calling_mod = module_text_address(called_from);
467 /* We must allow modules to probe themself and
468 * in this case avoid incrementing the module refcount,
469 * so as to allow unloading of self probing modules.
470 */
471 if (calling_mod && (calling_mod != probed_mod)) {
472 if (unlikely(!try_module_get(probed_mod)))
473 return -EINVAL;
474 p->mod_refcounted = 1;
475 } else
476 probed_mod = NULL;
477 }
Mao, Bibob3e55c72005-12-12 00:37:00 -0800478
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800479 p->nmissed = 0;
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800480 down(&kprobe_mutex);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700481 old_p = get_kprobe(p->addr);
482 if (old_p) {
483 ret = register_aggr_kprobe(old_p, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 goto out;
485 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800487 if ((ret = arch_prepare_kprobe(p)) != 0)
488 goto out;
489
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700490 INIT_HLIST_NODE(&p->hlist);
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800491 hlist_add_head_rcu(&p->hlist,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
493
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700494 arch_arm_kprobe(p);
495
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496out:
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800497 up(&kprobe_mutex);
498
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800499 if (ret && probed_mod)
500 module_put(probed_mod);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 return ret;
502}
503
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800504int __kprobes register_kprobe(struct kprobe *p)
505{
506 return __register_kprobe(p,
507 (unsigned long)__builtin_return_address(0));
508}
509
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700510void __kprobes unregister_kprobe(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511{
Mao, Bibob3e55c72005-12-12 00:37:00 -0800512 struct module *mod;
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800513 struct kprobe *old_p, *list_p;
514 int cleanup_p;
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700515
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800516 down(&kprobe_mutex);
Ananth N Mavinakayanahalli64f562c2005-05-05 16:15:42 -0700517 old_p = get_kprobe(p->addr);
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800518 if (unlikely(!old_p)) {
519 up(&kprobe_mutex);
520 return;
521 }
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800522 if (p != old_p) {
523 list_for_each_entry_rcu(list_p, &old_p->list, list)
524 if (list_p == p)
525 /* kprobe p is a valid probe */
526 goto valid_p;
527 up(&kprobe_mutex);
528 return;
529 }
530valid_p:
531 if ((old_p == p) || ((old_p->pre_handler == aggr_pre_handler) &&
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800532 (p->list.next == &old_p->list) &&
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800533 (p->list.prev == &old_p->list))) {
534 /* Only probe on the hash list */
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800535 arch_disarm_kprobe(p);
536 hlist_del_rcu(&old_p->hlist);
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800537 cleanup_p = 1;
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800538 } else {
539 list_del_rcu(&p->list);
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800540 cleanup_p = 0;
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800541 }
Mao, Bibob3e55c72005-12-12 00:37:00 -0800542
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800543 up(&kprobe_mutex);
Mao, Bibob3e55c72005-12-12 00:37:00 -0800544
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800545 synchronize_sched();
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800546 if (p->mod_refcounted &&
547 (mod = module_text_address((unsigned long)p->addr)))
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800548 module_put(mod);
549
550 if (cleanup_p) {
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800551 if (p != old_p) {
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800552 list_del_rcu(&p->list);
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800553 kfree(old_p);
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800554 }
Ananth N Mavinakayanahalli0498b632006-01-09 20:52:46 -0800555 arch_remove_kprobe(p);
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -0800556 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557}
558
559static struct notifier_block kprobe_exceptions_nb = {
560 .notifier_call = kprobe_exceptions_notify,
561 .priority = 0x7fffffff /* we need to notified first */
562};
563
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700564int __kprobes register_jprobe(struct jprobe *jp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565{
566 /* Todo: Verify probepoint is a function entry point */
567 jp->kp.pre_handler = setjmp_pre_handler;
568 jp->kp.break_handler = longjmp_break_handler;
569
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800570 return __register_kprobe(&jp->kp,
571 (unsigned long)__builtin_return_address(0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572}
573
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700574void __kprobes unregister_jprobe(struct jprobe *jp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575{
576 unregister_kprobe(&jp->kp);
577}
578
Hien Nguyenb94cce92005-06-23 00:09:19 -0700579#ifdef ARCH_SUPPORTS_KRETPROBES
580
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700581int __kprobes register_kretprobe(struct kretprobe *rp)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700582{
583 int ret = 0;
584 struct kretprobe_instance *inst;
585 int i;
586
587 rp->kp.pre_handler = pre_handler_kretprobe;
588
589 /* Pre-allocate memory for max kretprobe instances */
590 if (rp->maxactive <= 0) {
591#ifdef CONFIG_PREEMPT
592 rp->maxactive = max(10, 2 * NR_CPUS);
593#else
594 rp->maxactive = NR_CPUS;
595#endif
596 }
597 INIT_HLIST_HEAD(&rp->used_instances);
598 INIT_HLIST_HEAD(&rp->free_instances);
599 for (i = 0; i < rp->maxactive; i++) {
600 inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL);
601 if (inst == NULL) {
602 free_rp_inst(rp);
603 return -ENOMEM;
604 }
605 INIT_HLIST_NODE(&inst->uflist);
606 hlist_add_head(&inst->uflist, &rp->free_instances);
607 }
608
609 rp->nmissed = 0;
610 /* Establish function entry probe point */
Keshavamurthy Anil Sdf019b12006-01-11 12:17:41 -0800611 if ((ret = __register_kprobe(&rp->kp,
612 (unsigned long)__builtin_return_address(0))) != 0)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700613 free_rp_inst(rp);
614 return ret;
615}
616
617#else /* ARCH_SUPPORTS_KRETPROBES */
618
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700619int __kprobes register_kretprobe(struct kretprobe *rp)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700620{
621 return -ENOSYS;
622}
623
624#endif /* ARCH_SUPPORTS_KRETPROBES */
625
Prasanna S Panchamukhid0aaff92005-09-06 15:19:26 -0700626void __kprobes unregister_kretprobe(struct kretprobe *rp)
Hien Nguyenb94cce92005-06-23 00:09:19 -0700627{
628 unsigned long flags;
629 struct kretprobe_instance *ri;
630
631 unregister_kprobe(&rp->kp);
632 /* No race here */
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800633 spin_lock_irqsave(&kretprobe_lock, flags);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700634 free_rp_inst(rp);
635 while ((ri = get_used_rp_inst(rp)) != NULL) {
636 ri->rp = NULL;
637 hlist_del(&ri->uflist);
638 }
Ananth N Mavinakayanahalli3516a462005-11-07 01:00:13 -0800639 spin_unlock_irqrestore(&kretprobe_lock, flags);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700640}
641
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642static int __init init_kprobes(void)
643{
644 int i, err = 0;
645
646 /* FIXME allocate the probe table, currently defined statically */
647 /* initialize all list heads */
Hien Nguyenb94cce92005-06-23 00:09:19 -0700648 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649 INIT_HLIST_HEAD(&kprobe_table[i]);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700650 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
651 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652
Rusty Lynch67729262005-07-05 18:54:50 -0700653 err = arch_init_kprobes();
Rusty Lynch802eae72005-06-27 15:17:08 -0700654 if (!err)
655 err = register_die_notifier(&kprobe_exceptions_nb);
656
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 return err;
658}
659
660__initcall(init_kprobes);
661
662EXPORT_SYMBOL_GPL(register_kprobe);
663EXPORT_SYMBOL_GPL(unregister_kprobe);
664EXPORT_SYMBOL_GPL(register_jprobe);
665EXPORT_SYMBOL_GPL(unregister_jprobe);
666EXPORT_SYMBOL_GPL(jprobe_return);
Hien Nguyenb94cce92005-06-23 00:09:19 -0700667EXPORT_SYMBOL_GPL(register_kretprobe);
668EXPORT_SYMBOL_GPL(unregister_kretprobe);
669