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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Kernel Probes (KProbes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2002, 2004
19 *
20 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
21 * Probes initial implementation ( includes contributions from
22 * Rusty Russell).
23 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
24 * interface to access function arguments.
25 * 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
26 * for PPC64
27 */
28
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/kprobes.h>
30#include <linux/ptrace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/preempt.h>
Prasanna S Panchamukhi50e21f22006-03-26 01:38:24 -080032#include <linux/module.h>
Christoph Hellwig1eeb66a2007-05-08 00:27:03 -070033#include <linux/kdebug.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090034#include <linux/slab.h>
Rusty Lynch7e1048b2005-06-23 00:09:25 -070035#include <asm/cacheflush.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036#include <asm/sstep.h>
Prasanna S Panchamukhi50e21f22006-03-26 01:38:24 -080037#include <asm/uaccess.h>
Kumar Galaf8279622008-06-26 02:01:37 -050038#include <asm/system.h>
39
Dave Kleikamp172ae2e2010-02-08 11:50:57 +000040#ifdef CONFIG_PPC_ADV_DEBUG_REGS
Kumar Galaf8279622008-06-26 02:01:37 -050041#define MSR_SINGLESTEP (MSR_DE)
42#else
43#define MSR_SINGLESTEP (MSR_SE)
44#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -080046DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
47DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Masami Hiramatsuf438d912007-10-16 01:27:49 -070049struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
50
Prasanna S Panchamukhibb144a82005-09-06 15:19:29 -070051int __kprobes arch_prepare_kprobe(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -070052{
Ananth N Mavinakayanahalli63224d1e82005-06-08 15:49:41 -070053 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 kprobe_opcode_t insn = *p->addr;
55
Ananth N Mavinakayanahalli63224d1e82005-06-08 15:49:41 -070056 if ((unsigned long)p->addr & 0x03) {
57 printk("Attempt to register kprobe at an unaligned address\n");
58 ret = -EINVAL;
Kumar Gala82090032007-02-06 22:55:19 -060059 } else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) {
60 printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n");
Ananth N Mavinakayanahalli63224d1e82005-06-08 15:49:41 -070061 ret = -EINVAL;
62 }
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070063
Kumar Galaf8279622008-06-26 02:01:37 -050064 /* insn must be on a special executable page on ppc64. This is
65 * not explicitly required on ppc32 (right now), but it doesn't hurt */
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070066 if (!ret) {
Ananth N Mavinakayanahalli2d8ab6a2005-10-01 13:14:17 -040067 p->ainsn.insn = get_insn_slot();
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070068 if (!p->ainsn.insn)
69 ret = -ENOMEM;
70 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -080072 if (!ret) {
Ananth N Mavinakayanahallie6349a92007-04-18 15:57:51 +100073 memcpy(p->ainsn.insn, p->addr,
74 MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -080075 p->opcode = *p->addr;
Ananth N Mavinakayanahalli83db3dd2006-08-11 17:01:34 +053076 flush_icache_range((unsigned long)p->ainsn.insn,
77 (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -080078 }
79
Ananth N Mavinakayanahallie6349a92007-04-18 15:57:51 +100080 p->ainsn.boostable = 0;
Anil S Keshavamurthy49a2a1b2006-01-09 20:52:43 -080081 return ret;
Rusty Lynch7e1048b2005-06-23 00:09:25 -070082}
83
Prasanna S Panchamukhibb144a82005-09-06 15:19:29 -070084void __kprobes arch_arm_kprobe(struct kprobe *p)
Rusty Lynch7e1048b2005-06-23 00:09:25 -070085{
86 *p->addr = BREAKPOINT_INSTRUCTION;
87 flush_icache_range((unsigned long) p->addr,
88 (unsigned long) p->addr + sizeof(kprobe_opcode_t));
89}
90
Prasanna S Panchamukhibb144a82005-09-06 15:19:29 -070091void __kprobes arch_disarm_kprobe(struct kprobe *p)
Rusty Lynch7e1048b2005-06-23 00:09:25 -070092{
93 *p->addr = p->opcode;
94 flush_icache_range((unsigned long) p->addr,
95 (unsigned long) p->addr + sizeof(kprobe_opcode_t));
Linus Torvalds1da177e2005-04-16 15:20:36 -070096}
97
Ananth N Mavinakayanahalli0498b632006-01-09 20:52:46 -080098void __kprobes arch_remove_kprobe(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -070099{
Masami Hiramatsu12941562009-01-06 14:41:50 -0800100 if (p->ainsn.insn) {
101 free_insn_slot(p->ainsn.insn, 0);
102 p->ainsn.insn = NULL;
103 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104}
105
Prasanna S Panchamukhi46dbe2f2006-04-18 22:22:01 -0700106static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107{
Kumar Galab76e59d2008-06-26 01:57:58 -0500108 /* We turn off async exceptions to ensure that the single step will
109 * be for the instruction we have the kprobe on, if we dont its
110 * possible we'd get the single step reported for an exception handler
111 * like Decrementer or External Interrupt */
112 regs->msr &= ~MSR_EE;
Kumar Galaf8279622008-06-26 02:01:37 -0500113 regs->msr |= MSR_SINGLESTEP;
Dave Kleikamp172ae2e2010-02-08 11:50:57 +0000114#ifdef CONFIG_PPC_ADV_DEBUG_REGS
Kumar Galaf8279622008-06-26 02:01:37 -0500115 regs->msr &= ~MSR_CE;
116 mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
Dave Kleikamp221c1852010-03-05 10:43:24 +0000117#ifdef CONFIG_PPC_47x
118 isync();
119#endif
Kumar Galaf8279622008-06-26 02:01:37 -0500120#endif
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -0700121
Ananth N Mavinakayanahalli0ccde0a2006-04-28 17:38:42 +0530122 /*
123 * On powerpc we should single step on the original
124 * instruction even if the probed insn is a trap
125 * variant as values in regs could play a part in
126 * if the trap is taken or not
127 */
128 regs->nip = (unsigned long)p->ainsn.insn;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129}
130
Prasanna S Panchamukhi46dbe2f2006-04-18 22:22:01 -0700131static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700132{
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800133 kcb->prev_kprobe.kp = kprobe_running();
134 kcb->prev_kprobe.status = kcb->kprobe_status;
135 kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700136}
137
Prasanna S Panchamukhi46dbe2f2006-04-18 22:22:01 -0700138static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700139{
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800140 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
141 kcb->kprobe_status = kcb->prev_kprobe.status;
142 kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;
143}
144
Prasanna S Panchamukhi46dbe2f2006-04-18 22:22:01 -0700145static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800146 struct kprobe_ctlblk *kcb)
147{
148 __get_cpu_var(current_kprobe) = p;
149 kcb->kprobe_saved_msr = regs->msr;
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700150}
151
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700152void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
Prasanna S Panchamukhibb144a82005-09-06 15:19:29 -0700153 struct pt_regs *regs)
Rusty Lynch97f79432005-06-27 15:17:15 -0700154{
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700155 ri->ret_addr = (kprobe_opcode_t *)regs->link;
Rusty Lynch97f79432005-06-27 15:17:15 -0700156
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700157 /* Replace the return addr with trampoline addr */
158 regs->link = (unsigned long)kretprobe_trampoline;
Rusty Lynch97f79432005-06-27 15:17:15 -0700159}
160
Prasanna S Panchamukhi46dbe2f2006-04-18 22:22:01 -0700161static int __kprobes kprobe_handler(struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162{
163 struct kprobe *p;
164 int ret = 0;
165 unsigned int *addr = (unsigned int *)regs->nip;
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800166 struct kprobe_ctlblk *kcb;
167
168 /*
169 * We don't want to be preempted for the entire
170 * duration of kprobe processing
171 */
172 preempt_disable();
173 kcb = get_kprobe_ctlblk();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
175 /* Check we're not actually recursing */
176 if (kprobe_running()) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 p = get_kprobe(addr);
178 if (p) {
Keshavamurthy Anil Sdeac66a2005-09-06 15:19:35 -0700179 kprobe_opcode_t insn = *p->ainsn.insn;
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800180 if (kcb->kprobe_status == KPROBE_HIT_SS &&
Keshavamurthy Anil Sdeac66a2005-09-06 15:19:35 -0700181 is_trap(insn)) {
Kumar Galaf8279622008-06-26 02:01:37 -0500182 /* Turn off 'trace' bits */
183 regs->msr &= ~MSR_SINGLESTEP;
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800184 regs->msr |= kcb->kprobe_saved_msr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 goto no_kprobe;
186 }
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700187 /* We have reentered the kprobe_handler(), since
188 * another probe was hit while within the handler.
189 * We here save the original kprobes variables and
190 * just single step on the instruction of the new probe
191 * without calling any user handlers.
192 */
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800193 save_previous_kprobe(kcb);
194 set_current_kprobe(p, regs, kcb);
195 kcb->kprobe_saved_msr = regs->msr;
Keshavamurthy Anil Sbf8d5c52005-12-12 00:37:34 -0800196 kprobes_inc_nmissed_count(p);
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700197 prepare_singlestep(p, regs);
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800198 kcb->kprobe_status = KPROBE_REENTER;
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700199 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 } else {
Keshavamurthy Anil Seb3a7292006-01-11 12:17:42 -0800201 if (*addr != BREAKPOINT_INSTRUCTION) {
202 /* If trap variant, then it belongs not to us */
203 kprobe_opcode_t cur_insn = *addr;
204 if (is_trap(cur_insn))
205 goto no_kprobe;
206 /* The breakpoint instruction was removed by
207 * another cpu right after we hit, no further
208 * handling of this interrupt is appropriate
209 */
210 ret = 1;
211 goto no_kprobe;
212 }
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800213 p = __get_cpu_var(current_kprobe);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 if (p->break_handler && p->break_handler(p, regs)) {
215 goto ss_probe;
216 }
217 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 goto no_kprobe;
219 }
220
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 p = get_kprobe(addr);
222 if (!p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 if (*addr != BREAKPOINT_INSTRUCTION) {
224 /*
225 * PowerPC has multiple variants of the "trap"
226 * instruction. If the current instruction is a
227 * trap variant, it could belong to someone else
228 */
229 kprobe_opcode_t cur_insn = *addr;
Keshavamurthy Anil Sdeac66a2005-09-06 15:19:35 -0700230 if (is_trap(cur_insn))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 goto no_kprobe;
232 /*
233 * The breakpoint instruction was removed right
234 * after we hit it. Another cpu has removed
235 * either a probepoint or a debugger breakpoint
236 * at this address. In either case, no further
237 * handling of this interrupt is appropriate.
238 */
239 ret = 1;
240 }
241 /* Not one of ours: let kernel handle it */
242 goto no_kprobe;
243 }
244
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800245 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
246 set_current_kprobe(p, regs, kcb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 if (p->pre_handler && p->pre_handler(p, regs))
248 /* handler has already set things up, so skip ss setup */
249 return 1;
250
251ss_probe:
Ananth N Mavinakayanahallie6349a92007-04-18 15:57:51 +1000252 if (p->ainsn.boostable >= 0) {
253 unsigned int insn = *p->ainsn.insn;
254
255 /* regs->nip is also adjusted if emulate_step returns 1 */
256 ret = emulate_step(regs, insn);
257 if (ret > 0) {
258 /*
259 * Once this instruction has been boosted
260 * successfully, set the boostable flag
261 */
262 if (unlikely(p->ainsn.boostable == 0))
263 p->ainsn.boostable = 1;
264
265 if (p->post_handler)
266 p->post_handler(p, regs, 0);
267
268 kcb->kprobe_status = KPROBE_HIT_SSDONE;
269 reset_current_kprobe();
270 preempt_enable_no_resched();
271 return 1;
272 } else if (ret < 0) {
273 /*
274 * We don't allow kprobes on mtmsr(d)/rfi(d), etc.
275 * So, we should never get here... but, its still
276 * good to catch them, just in case...
277 */
278 printk("Can't step on instruction %x\n", insn);
279 BUG();
280 } else if (ret == 0)
281 /* This instruction can't be boosted */
282 p->ainsn.boostable = -1;
283 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 prepare_singlestep(p, regs);
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800285 kcb->kprobe_status = KPROBE_HIT_SS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 return 1;
287
288no_kprobe:
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800289 preempt_enable_no_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 return ret;
291}
292
293/*
Rusty Lynch97f79432005-06-27 15:17:15 -0700294 * Function return probe trampoline:
295 * - init_kprobes() establishes a probepoint here
296 * - When the probed function returns, this probe
297 * causes the handlers to fire
298 */
Ananth N Mavinakayanahalli66200ea2008-02-15 21:59:17 +1100299static void __used kretprobe_trampoline_holder(void)
Rusty Lynch97f79432005-06-27 15:17:15 -0700300{
301 asm volatile(".global kretprobe_trampoline\n"
302 "kretprobe_trampoline:\n"
303 "nop\n");
304}
305
306/*
307 * Called when the probe at kretprobe trampoline is hit
308 */
Ananth N Mavinakayanahalli66200ea2008-02-15 21:59:17 +1100309static int __kprobes trampoline_probe_handler(struct kprobe *p,
310 struct pt_regs *regs)
Rusty Lynch97f79432005-06-27 15:17:15 -0700311{
bibo,mao62c27be2006-10-02 02:17:33 -0700312 struct kretprobe_instance *ri = NULL;
bibo,mao99219a32006-10-02 02:17:35 -0700313 struct hlist_head *head, empty_rp;
bibo,mao62c27be2006-10-02 02:17:33 -0700314 struct hlist_node *node, *tmp;
Ananth N Mavinakayanahalli991a51d2005-11-07 01:00:14 -0800315 unsigned long flags, orig_ret_address = 0;
Rusty Lynch97f79432005-06-27 15:17:15 -0700316 unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
317
bibo,mao99219a32006-10-02 02:17:35 -0700318 INIT_HLIST_HEAD(&empty_rp);
Srinivasa D Sef53d9c2008-07-25 01:46:04 -0700319 kretprobe_hash_lock(current, &head, &flags);
Rusty Lynch97f79432005-06-27 15:17:15 -0700320
321 /*
322 * It is possible to have multiple instances associated with a given
323 * task either because an multiple functions in the call path
Frederik Schwarzer025dfda2008-10-16 19:02:37 +0200324 * have a return probe installed on them, and/or more than one return
Rusty Lynch97f79432005-06-27 15:17:15 -0700325 * return probe was registered for a target function.
326 *
327 * We can handle this because:
328 * - instances are always inserted at the head of the list
329 * - when multiple return probes are registered for the same
bibo,mao62c27be2006-10-02 02:17:33 -0700330 * function, the first instance's ret_addr will point to the
Rusty Lynch97f79432005-06-27 15:17:15 -0700331 * real return address, and all the rest will point to
332 * kretprobe_trampoline
333 */
334 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
bibo,mao62c27be2006-10-02 02:17:33 -0700335 if (ri->task != current)
Rusty Lynch97f79432005-06-27 15:17:15 -0700336 /* another task is sharing our hash bucket */
bibo,mao62c27be2006-10-02 02:17:33 -0700337 continue;
Rusty Lynch97f79432005-06-27 15:17:15 -0700338
339 if (ri->rp && ri->rp->handler)
340 ri->rp->handler(ri, regs);
341
342 orig_ret_address = (unsigned long)ri->ret_addr;
bibo,mao99219a32006-10-02 02:17:35 -0700343 recycle_rp_inst(ri, &empty_rp);
Rusty Lynch97f79432005-06-27 15:17:15 -0700344
345 if (orig_ret_address != trampoline_address)
346 /*
347 * This is the real return address. Any other
348 * instances associated with this task are for
349 * other calls deeper on the call stack
350 */
351 break;
352 }
353
Ananth N Mavinakayanahalli0f95b7f2007-05-08 00:28:27 -0700354 kretprobe_assert(ri, orig_ret_address, trampoline_address);
Rusty Lynch97f79432005-06-27 15:17:15 -0700355 regs->nip = orig_ret_address;
356
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800357 reset_current_kprobe();
Srinivasa D Sef53d9c2008-07-25 01:46:04 -0700358 kretprobe_hash_unlock(current, &flags);
Ananth N Mavinakayanahalli66ff2d02005-11-07 01:00:07 -0800359 preempt_enable_no_resched();
Rusty Lynch97f79432005-06-27 15:17:15 -0700360
bibo,mao99219a32006-10-02 02:17:35 -0700361 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
362 hlist_del(&ri->hlist);
363 kfree(ri);
364 }
bibo,mao62c27be2006-10-02 02:17:33 -0700365 /*
366 * By returning a non-zero value, we are telling
367 * kprobe_handler() that we don't want the post_handler
368 * to run (and have re-enabled preemption)
369 */
370 return 1;
Rusty Lynch97f79432005-06-27 15:17:15 -0700371}
372
373/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 * Called after single-stepping. p->addr is the address of the
375 * instruction whose first byte has been replaced by the "breakpoint"
376 * instruction. To avoid the SMP problems that can occur when we
377 * temporarily put back the original opcode to single-step, we
378 * single-stepped a copy of the instruction. The address of this
379 * copy is p->ainsn.insn.
380 */
Prasanna S Panchamukhi46dbe2f2006-04-18 22:22:01 -0700381static int __kprobes post_kprobe_handler(struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382{
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800383 struct kprobe *cur = kprobe_running();
384 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
385
386 if (!cur)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 return 0;
388
Kumar Galab76e59d2008-06-26 01:57:58 -0500389 /* make sure we got here for instruction we have a kprobe on */
390 if (((unsigned long)cur->ainsn.insn + 4) != regs->nip)
391 return 0;
392
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800393 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
394 kcb->kprobe_status = KPROBE_HIT_SSDONE;
395 cur->post_handler(cur, regs, 0);
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700396 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397
Ananth N Mavinakayanahallidb97bc72010-05-27 19:19:20 +0000398 /* Adjust nip to after the single-stepped instruction */
399 regs->nip = (unsigned long)cur->addr + 4;
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800400 regs->msr |= kcb->kprobe_saved_msr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700402 /*Restore back the original saved kprobes variables and continue. */
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800403 if (kcb->kprobe_status == KPROBE_REENTER) {
404 restore_previous_kprobe(kcb);
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700405 goto out;
406 }
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800407 reset_current_kprobe();
Prasanna S Panchamukhi42cc2062005-06-23 00:09:38 -0700408out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 preempt_enable_no_resched();
410
411 /*
412 * if somebody else is singlestepping across a probe point, msr
Kumar Galaf8279622008-06-26 02:01:37 -0500413 * will have DE/SE set, in which case, continue the remaining processing
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 * of do_debug, as if this is not a probe hit.
415 */
Kumar Galaf8279622008-06-26 02:01:37 -0500416 if (regs->msr & MSR_SINGLESTEP)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 return 0;
418
419 return 1;
420}
421
Christoph Hellwig9f90b992007-04-30 11:56:46 +0100422int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423{
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800424 struct kprobe *cur = kprobe_running();
425 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
Prasanna S Panchamukhi50e21f22006-03-26 01:38:24 -0800426 const struct exception_table_entry *entry;
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800427
Prasanna S Panchamukhi50e21f22006-03-26 01:38:24 -0800428 switch(kcb->kprobe_status) {
429 case KPROBE_HIT_SS:
430 case KPROBE_REENTER:
431 /*
432 * We are here because the instruction being single
433 * stepped caused a page fault. We reset the current
434 * kprobe and the nip points back to the probe address
435 * and allow the page fault handler to continue as a
436 * normal page fault.
437 */
438 regs->nip = (unsigned long)cur->addr;
Kumar Galaf8279622008-06-26 02:01:37 -0500439 regs->msr &= ~MSR_SINGLESTEP; /* Turn off 'trace' bits */
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800440 regs->msr |= kcb->kprobe_saved_msr;
Prasanna S Panchamukhi50e21f22006-03-26 01:38:24 -0800441 if (kcb->kprobe_status == KPROBE_REENTER)
442 restore_previous_kprobe(kcb);
443 else
444 reset_current_kprobe();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 preempt_enable_no_resched();
Prasanna S Panchamukhi50e21f22006-03-26 01:38:24 -0800446 break;
447 case KPROBE_HIT_ACTIVE:
448 case KPROBE_HIT_SSDONE:
449 /*
450 * We increment the nmissed count for accounting,
451 * we can also use npre/npostfault count for accouting
452 * these specific fault cases.
453 */
454 kprobes_inc_nmissed_count(cur);
455
456 /*
457 * We come here because instructions in the pre/post
458 * handler caused the page_fault, this could happen
459 * if handler tries to access user space by
460 * copy_from_user(), get_user() etc. Let the
461 * user-specified handler try to fix it first.
462 */
463 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
464 return 1;
465
466 /*
467 * In case the user-specified fault handler returned
468 * zero, try to fix up.
469 */
470 if ((entry = search_exception_tables(regs->nip)) != NULL) {
471 regs->nip = entry->fixup;
472 return 1;
473 }
474
475 /*
476 * fixup_exception() could not handle it,
477 * Let do_page_fault() fix it.
478 */
479 break;
480 default:
481 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 }
483 return 0;
484}
485
486/*
487 * Wrapper routine to for handling exceptions.
488 */
Prasanna S Panchamukhibb144a82005-09-06 15:19:29 -0700489int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
490 unsigned long val, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491{
492 struct die_args *args = (struct die_args *)data;
493 int ret = NOTIFY_DONE;
494
bibo,mao2326c772006-03-26 01:38:21 -0800495 if (args->regs && user_mode(args->regs))
496 return ret;
497
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 switch (val) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 case DIE_BPT:
500 if (kprobe_handler(args->regs))
501 ret = NOTIFY_STOP;
502 break;
503 case DIE_SSTEP:
504 if (post_kprobe_handler(args->regs))
505 ret = NOTIFY_STOP;
506 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 default:
508 break;
509 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 return ret;
511}
512
Michael Ellerman3d7e3382007-07-19 01:48:11 -0700513#ifdef CONFIG_PPC64
514unsigned long arch_deref_entry_point(void *entry)
515{
Michael Ellerman80d267f2008-05-23 14:22:21 +1000516 return ((func_descr_t *)entry)->entry;
Michael Ellerman3d7e3382007-07-19 01:48:11 -0700517}
518#endif
519
Prasanna S Panchamukhibb144a82005-09-06 15:19:29 -0700520int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521{
522 struct jprobe *jp = container_of(p, struct jprobe, kp);
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800523 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800525 memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526
527 /* setup return addr to the jprobe handler routine */
Michael Ellerman3d7e3382007-07-19 01:48:11 -0700528 regs->nip = arch_deref_entry_point(jp->entry);
Kumar Gala82090032007-02-06 22:55:19 -0600529#ifdef CONFIG_PPC64
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
Kumar Gala82090032007-02-06 22:55:19 -0600531#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532
533 return 1;
534}
535
Ananth N Mavinakayanahalli66200ea2008-02-15 21:59:17 +1100536void __used __kprobes jprobe_return(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537{
538 asm volatile("trap" ::: "memory");
539}
540
Ananth N Mavinakayanahalli66200ea2008-02-15 21:59:17 +1100541static void __used __kprobes jprobe_return_end(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542{
543};
544
Prasanna S Panchamukhibb144a82005-09-06 15:19:29 -0700545int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546{
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800547 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
548
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 /*
550 * FIXME - we should ideally be validating that we got here 'cos
551 * of the "trap" in jprobe_return() above, before restoring the
552 * saved regs...
553 */
Ananth N Mavinakayanahalli0dc036c2005-11-07 01:00:10 -0800554 memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800555 preempt_enable_no_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 return 1;
557}
Rusty Lynch97f79432005-06-27 15:17:15 -0700558
559static struct kprobe trampoline_p = {
560 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
561 .pre_handler = trampoline_probe_handler
562};
563
Rusty Lynch67729262005-07-05 18:54:50 -0700564int __init arch_init_kprobes(void)
Rusty Lynch97f79432005-06-27 15:17:15 -0700565{
566 return register_kprobe(&trampoline_p);
567}
Ananth N Mavinakayanahallibf8f6e5b2007-05-08 00:34:16 -0700568
569int __kprobes arch_trampoline_kprobe(struct kprobe *p)
570{
571 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
572 return 1;
573
574 return 0;
575}