Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Kernel Probes (KProbes) | |
1da177e4 LT |
3 | * |
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 | ||
1da177e4 LT |
29 | #include <linux/kprobes.h> |
30 | #include <linux/ptrace.h> | |
1da177e4 | 31 | #include <linux/preempt.h> |
50e21f2b | 32 | #include <linux/module.h> |
1eeb66a1 | 33 | #include <linux/kdebug.h> |
5a0e3ad6 | 34 | #include <linux/slab.h> |
7e1048b1 | 35 | #include <asm/cacheflush.h> |
1da177e4 | 36 | #include <asm/sstep.h> |
50e21f2b | 37 | #include <asm/uaccess.h> |
f8279621 | 38 | |
172ae2e7 | 39 | #ifdef CONFIG_PPC_ADV_DEBUG_REGS |
f8279621 KG |
40 | #define MSR_SINGLESTEP (MSR_DE) |
41 | #else | |
42 | #define MSR_SINGLESTEP (MSR_SE) | |
43 | #endif | |
1da177e4 | 44 | |
0dc036c9 AM |
45 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
46 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 47 | |
f438d914 MH |
48 | struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}}; |
49 | ||
bb144a85 | 50 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
1da177e4 | 51 | { |
63224d1e | 52 | int ret = 0; |
1da177e4 LT |
53 | kprobe_opcode_t insn = *p->addr; |
54 | ||
63224d1e AM |
55 | if ((unsigned long)p->addr & 0x03) { |
56 | printk("Attempt to register kprobe at an unaligned address\n"); | |
57 | ret = -EINVAL; | |
82090035 KG |
58 | } else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) { |
59 | printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n"); | |
63224d1e AM |
60 | ret = -EINVAL; |
61 | } | |
9ec4b1f3 | 62 | |
f8279621 KG |
63 | /* insn must be on a special executable page on ppc64. This is |
64 | * not explicitly required on ppc32 (right now), but it doesn't hurt */ | |
9ec4b1f3 | 65 | if (!ret) { |
2d8ab6ad | 66 | p->ainsn.insn = get_insn_slot(); |
9ec4b1f3 AM |
67 | if (!p->ainsn.insn) |
68 | ret = -ENOMEM; | |
69 | } | |
1da177e4 | 70 | |
49a2a1b8 | 71 | if (!ret) { |
e6349a95 AM |
72 | memcpy(p->ainsn.insn, p->addr, |
73 | MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
49a2a1b8 | 74 | p->opcode = *p->addr; |
83db3dde AM |
75 | flush_icache_range((unsigned long)p->ainsn.insn, |
76 | (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t)); | |
49a2a1b8 AK |
77 | } |
78 | ||
e6349a95 | 79 | p->ainsn.boostable = 0; |
49a2a1b8 | 80 | return ret; |
1da177e4 LT |
81 | } |
82 | ||
bb144a85 | 83 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 84 | { |
7e1048b1 RL |
85 | *p->addr = BREAKPOINT_INSTRUCTION; |
86 | flush_icache_range((unsigned long) p->addr, | |
87 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); | |
1da177e4 LT |
88 | } |
89 | ||
bb144a85 | 90 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 LT |
91 | { |
92 | *p->addr = p->opcode; | |
7e1048b1 RL |
93 | flush_icache_range((unsigned long) p->addr, |
94 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); | |
95 | } | |
96 | ||
0498b635 | 97 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 98 | { |
12941560 MH |
99 | if (p->ainsn.insn) { |
100 | free_insn_slot(p->ainsn.insn, 0); | |
101 | p->ainsn.insn = NULL; | |
102 | } | |
1da177e4 LT |
103 | } |
104 | ||
46dbe2f4 | 105 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 106 | { |
b76e59d1 KG |
107 | /* We turn off async exceptions to ensure that the single step will |
108 | * be for the instruction we have the kprobe on, if we dont its | |
109 | * possible we'd get the single step reported for an exception handler | |
110 | * like Decrementer or External Interrupt */ | |
111 | regs->msr &= ~MSR_EE; | |
f8279621 | 112 | regs->msr |= MSR_SINGLESTEP; |
172ae2e7 | 113 | #ifdef CONFIG_PPC_ADV_DEBUG_REGS |
f8279621 KG |
114 | regs->msr &= ~MSR_CE; |
115 | mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM); | |
221c185d DK |
116 | #ifdef CONFIG_PPC_47x |
117 | isync(); | |
118 | #endif | |
f8279621 | 119 | #endif |
9ec4b1f3 | 120 | |
0ccde0a2 AM |
121 | /* |
122 | * On powerpc we should single step on the original | |
123 | * instruction even if the probed insn is a trap | |
124 | * variant as values in regs could play a part in | |
125 | * if the trap is taken or not | |
126 | */ | |
127 | regs->nip = (unsigned long)p->ainsn.insn; | |
1da177e4 LT |
128 | } |
129 | ||
46dbe2f4 | 130 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
0dc036c9 AM |
131 | { |
132 | kcb->prev_kprobe.kp = kprobe_running(); | |
133 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
134 | kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr; | |
135 | } | |
136 | ||
46dbe2f4 | 137 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
42cc2060 | 138 | { |
0dc036c9 AM |
139 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
140 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
141 | kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr; | |
42cc2060 PP |
142 | } |
143 | ||
46dbe2f4 | 144 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
0dc036c9 | 145 | struct kprobe_ctlblk *kcb) |
42cc2060 | 146 | { |
0dc036c9 AM |
147 | __get_cpu_var(current_kprobe) = p; |
148 | kcb->kprobe_saved_msr = regs->msr; | |
42cc2060 PP |
149 | } |
150 | ||
4c4308cb | 151 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
bb144a85 | 152 | struct pt_regs *regs) |
97f7943d | 153 | { |
4c4308cb CH |
154 | ri->ret_addr = (kprobe_opcode_t *)regs->link; |
155 | ||
156 | /* Replace the return addr with trampoline addr */ | |
157 | regs->link = (unsigned long)kretprobe_trampoline; | |
97f7943d RL |
158 | } |
159 | ||
46dbe2f4 | 160 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
1da177e4 LT |
161 | { |
162 | struct kprobe *p; | |
163 | int ret = 0; | |
164 | unsigned int *addr = (unsigned int *)regs->nip; | |
d217d545 AM |
165 | struct kprobe_ctlblk *kcb; |
166 | ||
167 | /* | |
168 | * We don't want to be preempted for the entire | |
169 | * duration of kprobe processing | |
170 | */ | |
171 | preempt_disable(); | |
172 | kcb = get_kprobe_ctlblk(); | |
1da177e4 LT |
173 | |
174 | /* Check we're not actually recursing */ | |
175 | if (kprobe_running()) { | |
1da177e4 LT |
176 | p = get_kprobe(addr); |
177 | if (p) { | |
deac66ae | 178 | kprobe_opcode_t insn = *p->ainsn.insn; |
0dc036c9 | 179 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 180 | is_trap(insn)) { |
f8279621 KG |
181 | /* Turn off 'trace' bits */ |
182 | regs->msr &= ~MSR_SINGLESTEP; | |
0dc036c9 | 183 | regs->msr |= kcb->kprobe_saved_msr; |
1da177e4 LT |
184 | goto no_kprobe; |
185 | } | |
42cc2060 PP |
186 | /* We have reentered the kprobe_handler(), since |
187 | * another probe was hit while within the handler. | |
188 | * We here save the original kprobes variables and | |
189 | * just single step on the instruction of the new probe | |
190 | * without calling any user handlers. | |
191 | */ | |
0dc036c9 AM |
192 | save_previous_kprobe(kcb); |
193 | set_current_kprobe(p, regs, kcb); | |
194 | kcb->kprobe_saved_msr = regs->msr; | |
bf8d5c52 | 195 | kprobes_inc_nmissed_count(p); |
42cc2060 | 196 | prepare_singlestep(p, regs); |
0dc036c9 | 197 | kcb->kprobe_status = KPROBE_REENTER; |
42cc2060 | 198 | return 1; |
1da177e4 | 199 | } else { |
eb3a7292 KA |
200 | if (*addr != BREAKPOINT_INSTRUCTION) { |
201 | /* If trap variant, then it belongs not to us */ | |
202 | kprobe_opcode_t cur_insn = *addr; | |
203 | if (is_trap(cur_insn)) | |
204 | goto no_kprobe; | |
205 | /* The breakpoint instruction was removed by | |
206 | * another cpu right after we hit, no further | |
207 | * handling of this interrupt is appropriate | |
208 | */ | |
209 | ret = 1; | |
210 | goto no_kprobe; | |
211 | } | |
0dc036c9 | 212 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
213 | if (p->break_handler && p->break_handler(p, regs)) { |
214 | goto ss_probe; | |
215 | } | |
216 | } | |
1da177e4 LT |
217 | goto no_kprobe; |
218 | } | |
219 | ||
1da177e4 LT |
220 | p = get_kprobe(addr); |
221 | if (!p) { | |
1da177e4 LT |
222 | if (*addr != BREAKPOINT_INSTRUCTION) { |
223 | /* | |
224 | * PowerPC has multiple variants of the "trap" | |
225 | * instruction. If the current instruction is a | |
226 | * trap variant, it could belong to someone else | |
227 | */ | |
228 | kprobe_opcode_t cur_insn = *addr; | |
deac66ae | 229 | if (is_trap(cur_insn)) |
1da177e4 LT |
230 | goto no_kprobe; |
231 | /* | |
232 | * The breakpoint instruction was removed right | |
233 | * after we hit it. Another cpu has removed | |
234 | * either a probepoint or a debugger breakpoint | |
235 | * at this address. In either case, no further | |
236 | * handling of this interrupt is appropriate. | |
237 | */ | |
238 | ret = 1; | |
239 | } | |
240 | /* Not one of ours: let kernel handle it */ | |
241 | goto no_kprobe; | |
242 | } | |
243 | ||
0dc036c9 AM |
244 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
245 | set_current_kprobe(p, regs, kcb); | |
1da177e4 LT |
246 | if (p->pre_handler && p->pre_handler(p, regs)) |
247 | /* handler has already set things up, so skip ss setup */ | |
248 | return 1; | |
249 | ||
250 | ss_probe: | |
e6349a95 AM |
251 | if (p->ainsn.boostable >= 0) { |
252 | unsigned int insn = *p->ainsn.insn; | |
253 | ||
254 | /* regs->nip is also adjusted if emulate_step returns 1 */ | |
255 | ret = emulate_step(regs, insn); | |
256 | if (ret > 0) { | |
257 | /* | |
258 | * Once this instruction has been boosted | |
259 | * successfully, set the boostable flag | |
260 | */ | |
261 | if (unlikely(p->ainsn.boostable == 0)) | |
262 | p->ainsn.boostable = 1; | |
263 | ||
264 | if (p->post_handler) | |
265 | p->post_handler(p, regs, 0); | |
266 | ||
267 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
268 | reset_current_kprobe(); | |
269 | preempt_enable_no_resched(); | |
270 | return 1; | |
271 | } else if (ret < 0) { | |
272 | /* | |
273 | * We don't allow kprobes on mtmsr(d)/rfi(d), etc. | |
274 | * So, we should never get here... but, its still | |
275 | * good to catch them, just in case... | |
276 | */ | |
277 | printk("Can't step on instruction %x\n", insn); | |
278 | BUG(); | |
279 | } else if (ret == 0) | |
280 | /* This instruction can't be boosted */ | |
281 | p->ainsn.boostable = -1; | |
282 | } | |
1da177e4 | 283 | prepare_singlestep(p, regs); |
0dc036c9 | 284 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
285 | return 1; |
286 | ||
287 | no_kprobe: | |
d217d545 | 288 | preempt_enable_no_resched(); |
1da177e4 LT |
289 | return ret; |
290 | } | |
291 | ||
97f7943d RL |
292 | /* |
293 | * Function return probe trampoline: | |
294 | * - init_kprobes() establishes a probepoint here | |
295 | * - When the probed function returns, this probe | |
296 | * causes the handlers to fire | |
297 | */ | |
66200ea2 | 298 | static void __used kretprobe_trampoline_holder(void) |
97f7943d RL |
299 | { |
300 | asm volatile(".global kretprobe_trampoline\n" | |
301 | "kretprobe_trampoline:\n" | |
302 | "nop\n"); | |
303 | } | |
304 | ||
305 | /* | |
306 | * Called when the probe at kretprobe trampoline is hit | |
307 | */ | |
66200ea2 AM |
308 | static int __kprobes trampoline_probe_handler(struct kprobe *p, |
309 | struct pt_regs *regs) | |
97f7943d | 310 | { |
62c27be0 | 311 | struct kretprobe_instance *ri = NULL; |
99219a3f | 312 | struct hlist_head *head, empty_rp; |
b67bfe0d | 313 | struct hlist_node *tmp; |
991a51d8 | 314 | unsigned long flags, orig_ret_address = 0; |
97f7943d RL |
315 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
316 | ||
99219a3f | 317 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 318 | kretprobe_hash_lock(current, &head, &flags); |
97f7943d RL |
319 | |
320 | /* | |
321 | * It is possible to have multiple instances associated with a given | |
322 | * task either because an multiple functions in the call path | |
025dfdaf | 323 | * have a return probe installed on them, and/or more than one return |
97f7943d RL |
324 | * return probe was registered for a target function. |
325 | * | |
326 | * We can handle this because: | |
327 | * - instances are always inserted at the head of the list | |
328 | * - when multiple return probes are registered for the same | |
62c27be0 | 329 | * function, the first instance's ret_addr will point to the |
97f7943d RL |
330 | * real return address, and all the rest will point to |
331 | * kretprobe_trampoline | |
332 | */ | |
b67bfe0d | 333 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
62c27be0 | 334 | if (ri->task != current) |
97f7943d | 335 | /* another task is sharing our hash bucket */ |
62c27be0 | 336 | continue; |
97f7943d RL |
337 | |
338 | if (ri->rp && ri->rp->handler) | |
339 | ri->rp->handler(ri, regs); | |
340 | ||
341 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 342 | recycle_rp_inst(ri, &empty_rp); |
97f7943d RL |
343 | |
344 | if (orig_ret_address != trampoline_address) | |
345 | /* | |
346 | * This is the real return address. Any other | |
347 | * instances associated with this task are for | |
348 | * other calls deeper on the call stack | |
349 | */ | |
350 | break; | |
351 | } | |
352 | ||
0f95b7fc | 353 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
97f7943d RL |
354 | regs->nip = orig_ret_address; |
355 | ||
0dc036c9 | 356 | reset_current_kprobe(); |
ef53d9c5 | 357 | kretprobe_hash_unlock(current, &flags); |
66ff2d06 | 358 | preempt_enable_no_resched(); |
97f7943d | 359 | |
b67bfe0d | 360 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
99219a3f | 361 | hlist_del(&ri->hlist); |
362 | kfree(ri); | |
363 | } | |
62c27be0 | 364 | /* |
365 | * By returning a non-zero value, we are telling | |
366 | * kprobe_handler() that we don't want the post_handler | |
367 | * to run (and have re-enabled preemption) | |
368 | */ | |
369 | return 1; | |
97f7943d RL |
370 | } |
371 | ||
1da177e4 LT |
372 | /* |
373 | * Called after single-stepping. p->addr is the address of the | |
374 | * instruction whose first byte has been replaced by the "breakpoint" | |
375 | * instruction. To avoid the SMP problems that can occur when we | |
376 | * temporarily put back the original opcode to single-step, we | |
377 | * single-stepped a copy of the instruction. The address of this | |
378 | * copy is p->ainsn.insn. | |
379 | */ | |
46dbe2f4 | 380 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) |
1da177e4 | 381 | { |
0dc036c9 AM |
382 | struct kprobe *cur = kprobe_running(); |
383 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
384 | ||
385 | if (!cur) | |
1da177e4 LT |
386 | return 0; |
387 | ||
b76e59d1 KG |
388 | /* make sure we got here for instruction we have a kprobe on */ |
389 | if (((unsigned long)cur->ainsn.insn + 4) != regs->nip) | |
390 | return 0; | |
391 | ||
0dc036c9 AM |
392 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
393 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
394 | cur->post_handler(cur, regs, 0); | |
42cc2060 | 395 | } |
1da177e4 | 396 | |
db97bc7f AM |
397 | /* Adjust nip to after the single-stepped instruction */ |
398 | regs->nip = (unsigned long)cur->addr + 4; | |
0dc036c9 | 399 | regs->msr |= kcb->kprobe_saved_msr; |
1da177e4 | 400 | |
42cc2060 | 401 | /*Restore back the original saved kprobes variables and continue. */ |
0dc036c9 AM |
402 | if (kcb->kprobe_status == KPROBE_REENTER) { |
403 | restore_previous_kprobe(kcb); | |
42cc2060 PP |
404 | goto out; |
405 | } | |
0dc036c9 | 406 | reset_current_kprobe(); |
42cc2060 | 407 | out: |
1da177e4 LT |
408 | preempt_enable_no_resched(); |
409 | ||
410 | /* | |
411 | * if somebody else is singlestepping across a probe point, msr | |
f8279621 | 412 | * will have DE/SE set, in which case, continue the remaining processing |
1da177e4 LT |
413 | * of do_debug, as if this is not a probe hit. |
414 | */ | |
f8279621 | 415 | if (regs->msr & MSR_SINGLESTEP) |
1da177e4 LT |
416 | return 0; |
417 | ||
418 | return 1; | |
419 | } | |
420 | ||
9f90b997 | 421 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 422 | { |
0dc036c9 AM |
423 | struct kprobe *cur = kprobe_running(); |
424 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
50e21f2b PP |
425 | const struct exception_table_entry *entry; |
426 | ||
427 | switch(kcb->kprobe_status) { | |
428 | case KPROBE_HIT_SS: | |
429 | case KPROBE_REENTER: | |
430 | /* | |
431 | * We are here because the instruction being single | |
432 | * stepped caused a page fault. We reset the current | |
433 | * kprobe and the nip points back to the probe address | |
434 | * and allow the page fault handler to continue as a | |
435 | * normal page fault. | |
436 | */ | |
437 | regs->nip = (unsigned long)cur->addr; | |
f8279621 | 438 | regs->msr &= ~MSR_SINGLESTEP; /* Turn off 'trace' bits */ |
0dc036c9 | 439 | regs->msr |= kcb->kprobe_saved_msr; |
50e21f2b PP |
440 | if (kcb->kprobe_status == KPROBE_REENTER) |
441 | restore_previous_kprobe(kcb); | |
442 | else | |
443 | reset_current_kprobe(); | |
1da177e4 | 444 | preempt_enable_no_resched(); |
50e21f2b PP |
445 | break; |
446 | case KPROBE_HIT_ACTIVE: | |
447 | case KPROBE_HIT_SSDONE: | |
448 | /* | |
449 | * We increment the nmissed count for accounting, | |
450 | * we can also use npre/npostfault count for accouting | |
451 | * these specific fault cases. | |
452 | */ | |
453 | kprobes_inc_nmissed_count(cur); | |
454 | ||
455 | /* | |
456 | * We come here because instructions in the pre/post | |
457 | * handler caused the page_fault, this could happen | |
458 | * if handler tries to access user space by | |
459 | * copy_from_user(), get_user() etc. Let the | |
460 | * user-specified handler try to fix it first. | |
461 | */ | |
462 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
463 | return 1; | |
464 | ||
465 | /* | |
466 | * In case the user-specified fault handler returned | |
467 | * zero, try to fix up. | |
468 | */ | |
469 | if ((entry = search_exception_tables(regs->nip)) != NULL) { | |
470 | regs->nip = entry->fixup; | |
471 | return 1; | |
472 | } | |
473 | ||
474 | /* | |
475 | * fixup_exception() could not handle it, | |
476 | * Let do_page_fault() fix it. | |
477 | */ | |
478 | break; | |
479 | default: | |
480 | break; | |
1da177e4 LT |
481 | } |
482 | return 0; | |
483 | } | |
484 | ||
485 | /* | |
486 | * Wrapper routine to for handling exceptions. | |
487 | */ | |
bb144a85 PP |
488 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
489 | unsigned long val, void *data) | |
1da177e4 LT |
490 | { |
491 | struct die_args *args = (struct die_args *)data; | |
492 | int ret = NOTIFY_DONE; | |
493 | ||
2326c770 | 494 | if (args->regs && user_mode(args->regs)) |
495 | return ret; | |
496 | ||
1da177e4 | 497 | switch (val) { |
1da177e4 LT |
498 | case DIE_BPT: |
499 | if (kprobe_handler(args->regs)) | |
500 | ret = NOTIFY_STOP; | |
501 | break; | |
502 | case DIE_SSTEP: | |
503 | if (post_kprobe_handler(args->regs)) | |
504 | ret = NOTIFY_STOP; | |
505 | break; | |
1da177e4 LT |
506 | default: |
507 | break; | |
508 | } | |
1da177e4 LT |
509 | return ret; |
510 | } | |
511 | ||
3d7e3382 ME |
512 | #ifdef CONFIG_PPC64 |
513 | unsigned long arch_deref_entry_point(void *entry) | |
514 | { | |
80d267f9 | 515 | return ((func_descr_t *)entry)->entry; |
3d7e3382 ME |
516 | } |
517 | #endif | |
518 | ||
bb144a85 | 519 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
520 | { |
521 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
0dc036c9 | 522 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 523 | |
0dc036c9 | 524 | memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); |
1da177e4 LT |
525 | |
526 | /* setup return addr to the jprobe handler routine */ | |
3d7e3382 | 527 | regs->nip = arch_deref_entry_point(jp->entry); |
82090035 | 528 | #ifdef CONFIG_PPC64 |
1da177e4 | 529 | regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc); |
82090035 | 530 | #endif |
1da177e4 | 531 | |
790d869b NR |
532 | /* |
533 | * jprobes use jprobe_return() which skips the normal return | |
534 | * path of the function, and this messes up the accounting of the | |
535 | * function graph tracer. | |
536 | * | |
537 | * Pause function graph tracing while performing the jprobe function. | |
538 | */ | |
539 | pause_graph_tracing(); | |
540 | ||
1da177e4 LT |
541 | return 1; |
542 | } | |
543 | ||
66200ea2 | 544 | void __used __kprobes jprobe_return(void) |
1da177e4 LT |
545 | { |
546 | asm volatile("trap" ::: "memory"); | |
547 | } | |
548 | ||
66200ea2 | 549 | static void __used __kprobes jprobe_return_end(void) |
1da177e4 LT |
550 | { |
551 | }; | |
552 | ||
bb144a85 | 553 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 554 | { |
0dc036c9 AM |
555 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
556 | ||
1da177e4 LT |
557 | /* |
558 | * FIXME - we should ideally be validating that we got here 'cos | |
559 | * of the "trap" in jprobe_return() above, before restoring the | |
560 | * saved regs... | |
561 | */ | |
0dc036c9 | 562 | memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); |
790d869b NR |
563 | /* It's OK to start function graph tracing again */ |
564 | unpause_graph_tracing(); | |
d217d545 | 565 | preempt_enable_no_resched(); |
1da177e4 LT |
566 | return 1; |
567 | } | |
97f7943d RL |
568 | |
569 | static struct kprobe trampoline_p = { | |
570 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, | |
571 | .pre_handler = trampoline_probe_handler | |
572 | }; | |
573 | ||
6772926b | 574 | int __init arch_init_kprobes(void) |
97f7943d RL |
575 | { |
576 | return register_kprobe(&trampoline_p); | |
577 | } | |
bf8f6e5b AM |
578 | |
579 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
580 | { | |
581 | if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) | |
582 | return 1; | |
583 | ||
584 | return 0; | |
585 | } |