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4ba069b8 MG |
1 | /* |
2 | * Kernel Probes (KProbes) | |
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 | * | |
a53c8fab | 18 | * Copyright IBM Corp. 2002, 2006 |
4ba069b8 MG |
19 | * |
20 | * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com> | |
21 | */ | |
22 | ||
4ba069b8 MG |
23 | #include <linux/kprobes.h> |
24 | #include <linux/ptrace.h> | |
25 | #include <linux/preempt.h> | |
26 | #include <linux/stop_machine.h> | |
1eeb66a1 | 27 | #include <linux/kdebug.h> |
a2b53673 | 28 | #include <linux/uaccess.h> |
4ba069b8 | 29 | #include <asm/cacheflush.h> |
4ba069b8 | 30 | #include <asm/sections.h> |
4ba069b8 | 31 | #include <linux/module.h> |
5a0e3ad6 | 32 | #include <linux/slab.h> |
adb45839 | 33 | #include <linux/hardirq.h> |
4ba069b8 | 34 | |
4a188635 | 35 | DEFINE_PER_CPU(struct kprobe *, current_kprobe); |
4ba069b8 MG |
36 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
37 | ||
4a188635 | 38 | struct kretprobe_blackpoint kretprobe_blacklist[] = { }; |
f438d914 | 39 | |
ba640a59 | 40 | static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn) |
4ba069b8 | 41 | { |
ba640a59 | 42 | switch (insn[0] >> 8) { |
4ba069b8 MG |
43 | case 0x0c: /* bassm */ |
44 | case 0x0b: /* bsm */ | |
45 | case 0x83: /* diag */ | |
46 | case 0x44: /* ex */ | |
bac9f154 HC |
47 | case 0xac: /* stnsm */ |
48 | case 0xad: /* stosm */ | |
4ba069b8 MG |
49 | return -EINVAL; |
50 | } | |
ba640a59 | 51 | switch (insn[0]) { |
4ba069b8 MG |
52 | case 0x0101: /* pr */ |
53 | case 0xb25a: /* bsa */ | |
54 | case 0xb240: /* bakr */ | |
55 | case 0xb258: /* bsg */ | |
56 | case 0xb218: /* pc */ | |
57 | case 0xb228: /* pt */ | |
bac9f154 | 58 | case 0xb98d: /* epsw */ |
4ba069b8 MG |
59 | return -EINVAL; |
60 | } | |
61 | return 0; | |
62 | } | |
63 | ||
ba640a59 | 64 | static int __kprobes get_fixup_type(kprobe_opcode_t *insn) |
4ba069b8 MG |
65 | { |
66 | /* default fixup method */ | |
ba640a59 | 67 | int fixup = FIXUP_PSW_NORMAL; |
4ba069b8 | 68 | |
ba640a59 | 69 | switch (insn[0] >> 8) { |
4ba069b8 MG |
70 | case 0x05: /* balr */ |
71 | case 0x0d: /* basr */ | |
ba640a59 | 72 | fixup = FIXUP_RETURN_REGISTER; |
4ba069b8 | 73 | /* if r2 = 0, no branch will be taken */ |
ba640a59 MS |
74 | if ((insn[0] & 0x0f) == 0) |
75 | fixup |= FIXUP_BRANCH_NOT_TAKEN; | |
4ba069b8 MG |
76 | break; |
77 | case 0x06: /* bctr */ | |
78 | case 0x07: /* bcr */ | |
ba640a59 | 79 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
4ba069b8 MG |
80 | break; |
81 | case 0x45: /* bal */ | |
82 | case 0x4d: /* bas */ | |
ba640a59 | 83 | fixup = FIXUP_RETURN_REGISTER; |
4ba069b8 MG |
84 | break; |
85 | case 0x47: /* bc */ | |
86 | case 0x46: /* bct */ | |
87 | case 0x86: /* bxh */ | |
88 | case 0x87: /* bxle */ | |
ba640a59 | 89 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
4ba069b8 MG |
90 | break; |
91 | case 0x82: /* lpsw */ | |
ba640a59 | 92 | fixup = FIXUP_NOT_REQUIRED; |
4ba069b8 MG |
93 | break; |
94 | case 0xb2: /* lpswe */ | |
ba640a59 MS |
95 | if ((insn[0] & 0xff) == 0xb2) |
96 | fixup = FIXUP_NOT_REQUIRED; | |
4ba069b8 MG |
97 | break; |
98 | case 0xa7: /* bras */ | |
ba640a59 MS |
99 | if ((insn[0] & 0x0f) == 0x05) |
100 | fixup |= FIXUP_RETURN_REGISTER; | |
4ba069b8 MG |
101 | break; |
102 | case 0xc0: | |
ba640a59 MS |
103 | if ((insn[0] & 0x0f) == 0x00 || /* larl */ |
104 | (insn[0] & 0x0f) == 0x05) /* brasl */ | |
105 | fixup |= FIXUP_RETURN_REGISTER; | |
4ba069b8 MG |
106 | break; |
107 | case 0xeb: | |
6b169ac9 HC |
108 | switch (insn[2] & 0xff) { |
109 | case 0x44: /* bxhg */ | |
110 | case 0x45: /* bxleg */ | |
ba640a59 | 111 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
6b169ac9 HC |
112 | break; |
113 | } | |
4ba069b8 MG |
114 | break; |
115 | case 0xe3: /* bctg */ | |
ba640a59 MS |
116 | if ((insn[2] & 0xff) == 0x46) |
117 | fixup = FIXUP_BRANCH_NOT_TAKEN; | |
4ba069b8 | 118 | break; |
6b169ac9 HC |
119 | case 0xec: |
120 | switch (insn[2] & 0xff) { | |
121 | case 0xe5: /* clgrb */ | |
122 | case 0xe6: /* cgrb */ | |
123 | case 0xf6: /* crb */ | |
124 | case 0xf7: /* clrb */ | |
125 | case 0xfc: /* cgib */ | |
126 | case 0xfd: /* cglib */ | |
127 | case 0xfe: /* cib */ | |
128 | case 0xff: /* clib */ | |
129 | fixup = FIXUP_BRANCH_NOT_TAKEN; | |
130 | break; | |
131 | } | |
132 | break; | |
4ba069b8 | 133 | } |
ba640a59 MS |
134 | return fixup; |
135 | } | |
136 | ||
137 | int __kprobes arch_prepare_kprobe(struct kprobe *p) | |
138 | { | |
139 | if ((unsigned long) p->addr & 0x01) | |
140 | return -EINVAL; | |
141 | ||
142 | /* Make sure the probe isn't going on a difficult instruction */ | |
4a188635 | 143 | if (is_prohibited_opcode(p->addr)) |
ba640a59 MS |
144 | return -EINVAL; |
145 | ||
ba640a59 MS |
146 | p->opcode = *p->addr; |
147 | memcpy(p->ainsn.insn, p->addr, ((p->opcode >> 14) + 3) & -2); | |
148 | ||
149 | return 0; | |
4ba069b8 MG |
150 | } |
151 | ||
5a8b589f MS |
152 | struct ins_replace_args { |
153 | kprobe_opcode_t *ptr; | |
154 | kprobe_opcode_t opcode; | |
155 | }; | |
156 | ||
4ba069b8 MG |
157 | static int __kprobes swap_instruction(void *aref) |
158 | { | |
acf01800 HC |
159 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
160 | unsigned long status = kcb->kprobe_status; | |
4ba069b8 | 161 | struct ins_replace_args *args = aref; |
a2b53673 | 162 | |
acf01800 | 163 | kcb->kprobe_status = KPROBE_SWAP_INST; |
5a8b589f | 164 | probe_kernel_write(args->ptr, &args->opcode, sizeof(args->opcode)); |
acf01800 | 165 | kcb->kprobe_status = status; |
5a8b589f | 166 | return 0; |
4ba069b8 MG |
167 | } |
168 | ||
169 | void __kprobes arch_arm_kprobe(struct kprobe *p) | |
170 | { | |
4ba069b8 MG |
171 | struct ins_replace_args args; |
172 | ||
173 | args.ptr = p->addr; | |
5a8b589f | 174 | args.opcode = BREAKPOINT_INSTRUCTION; |
9b1a4d38 | 175 | stop_machine(swap_instruction, &args, NULL); |
4ba069b8 MG |
176 | } |
177 | ||
178 | void __kprobes arch_disarm_kprobe(struct kprobe *p) | |
179 | { | |
4ba069b8 MG |
180 | struct ins_replace_args args; |
181 | ||
182 | args.ptr = p->addr; | |
5a8b589f | 183 | args.opcode = p->opcode; |
9b1a4d38 | 184 | stop_machine(swap_instruction, &args, NULL); |
4ba069b8 MG |
185 | } |
186 | ||
187 | void __kprobes arch_remove_kprobe(struct kprobe *p) | |
188 | { | |
4ba069b8 MG |
189 | } |
190 | ||
fc0a1fea MS |
191 | static void __kprobes enable_singlestep(struct kprobe_ctlblk *kcb, |
192 | struct pt_regs *regs, | |
193 | unsigned long ip) | |
4ba069b8 | 194 | { |
5e9a2692 | 195 | struct per_regs per_kprobe; |
4ba069b8 | 196 | |
5e9a2692 MS |
197 | /* Set up the PER control registers %cr9-%cr11 */ |
198 | per_kprobe.control = PER_EVENT_IFETCH; | |
199 | per_kprobe.start = ip; | |
200 | per_kprobe.end = ip; | |
4ba069b8 | 201 | |
fc0a1fea MS |
202 | /* Save control regs and psw mask */ |
203 | __ctl_store(kcb->kprobe_saved_ctl, 9, 11); | |
204 | kcb->kprobe_saved_imask = regs->psw.mask & | |
205 | (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT); | |
206 | ||
207 | /* Set PER control regs, turns on single step for the given address */ | |
5e9a2692 | 208 | __ctl_load(per_kprobe, 9, 11); |
4ba069b8 | 209 | regs->psw.mask |= PSW_MASK_PER; |
adb45839 | 210 | regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT); |
fc0a1fea | 211 | regs->psw.addr = ip | PSW_ADDR_AMODE; |
4ba069b8 MG |
212 | } |
213 | ||
fc0a1fea MS |
214 | static void __kprobes disable_singlestep(struct kprobe_ctlblk *kcb, |
215 | struct pt_regs *regs, | |
216 | unsigned long ip) | |
217 | { | |
218 | /* Restore control regs and psw mask, set new psw address */ | |
219 | __ctl_load(kcb->kprobe_saved_ctl, 9, 11); | |
220 | regs->psw.mask &= ~PSW_MASK_PER; | |
221 | regs->psw.mask |= kcb->kprobe_saved_imask; | |
222 | regs->psw.addr = ip | PSW_ADDR_AMODE; | |
223 | } | |
224 | ||
b9599798 MS |
225 | /* |
226 | * Activate a kprobe by storing its pointer to current_kprobe. The | |
227 | * previous kprobe is stored in kcb->prev_kprobe. A stack of up to | |
228 | * two kprobes can be active, see KPROBE_REENTER. | |
229 | */ | |
230 | static void __kprobes push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p) | |
4ba069b8 | 231 | { |
b9599798 | 232 | kcb->prev_kprobe.kp = __get_cpu_var(current_kprobe); |
4ba069b8 | 233 | kcb->prev_kprobe.status = kcb->kprobe_status; |
b9599798 | 234 | __get_cpu_var(current_kprobe) = p; |
4ba069b8 MG |
235 | } |
236 | ||
b9599798 MS |
237 | /* |
238 | * Deactivate a kprobe by backing up to the previous state. If the | |
239 | * current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL, | |
240 | * for any other state prev_kprobe.kp will be NULL. | |
241 | */ | |
242 | static void __kprobes pop_kprobe(struct kprobe_ctlblk *kcb) | |
4ba069b8 MG |
243 | { |
244 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; | |
245 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
4ba069b8 MG |
246 | } |
247 | ||
4c4308cb | 248 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
4ba069b8 MG |
249 | struct pt_regs *regs) |
250 | { | |
4c4308cb | 251 | ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14]; |
4ba069b8 | 252 | |
4c4308cb | 253 | /* Replace the return addr with trampoline addr */ |
4a188635 | 254 | regs->gprs[14] = (unsigned long) &kretprobe_trampoline; |
4ba069b8 MG |
255 | } |
256 | ||
0e917cc3 MS |
257 | static void __kprobes kprobe_reenter_check(struct kprobe_ctlblk *kcb, |
258 | struct kprobe *p) | |
259 | { | |
260 | switch (kcb->kprobe_status) { | |
261 | case KPROBE_HIT_SSDONE: | |
262 | case KPROBE_HIT_ACTIVE: | |
263 | kprobes_inc_nmissed_count(p); | |
264 | break; | |
265 | case KPROBE_HIT_SS: | |
266 | case KPROBE_REENTER: | |
267 | default: | |
268 | /* | |
269 | * A kprobe on the code path to single step an instruction | |
270 | * is a BUG. The code path resides in the .kprobes.text | |
271 | * section and is executed with interrupts disabled. | |
272 | */ | |
273 | printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr); | |
274 | dump_kprobe(p); | |
275 | BUG(); | |
276 | } | |
277 | } | |
278 | ||
4ba069b8 MG |
279 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
280 | { | |
4ba069b8 | 281 | struct kprobe_ctlblk *kcb; |
0e917cc3 | 282 | struct kprobe *p; |
4ba069b8 MG |
283 | |
284 | /* | |
0e917cc3 MS |
285 | * We want to disable preemption for the entire duration of kprobe |
286 | * processing. That includes the calls to the pre/post handlers | |
287 | * and single stepping the kprobe instruction. | |
4ba069b8 MG |
288 | */ |
289 | preempt_disable(); | |
290 | kcb = get_kprobe_ctlblk(); | |
0e917cc3 | 291 | p = get_kprobe((void *)((regs->psw.addr & PSW_ADDR_INSN) - 2)); |
4ba069b8 | 292 | |
0e917cc3 MS |
293 | if (p) { |
294 | if (kprobe_running()) { | |
b9599798 MS |
295 | /* |
296 | * We have hit a kprobe while another is still | |
297 | * active. This can happen in the pre and post | |
298 | * handler. Single step the instruction of the | |
299 | * new probe but do not call any handler function | |
300 | * of this secondary kprobe. | |
301 | * push_kprobe and pop_kprobe saves and restores | |
302 | * the currently active kprobe. | |
4ba069b8 | 303 | */ |
0e917cc3 | 304 | kprobe_reenter_check(kcb, p); |
b9599798 | 305 | push_kprobe(kcb, p); |
4ba069b8 | 306 | kcb->kprobe_status = KPROBE_REENTER; |
4ba069b8 | 307 | } else { |
0e917cc3 MS |
308 | /* |
309 | * If we have no pre-handler or it returned 0, we | |
310 | * continue with single stepping. If we have a | |
311 | * pre-handler and it returned non-zero, it prepped | |
312 | * for calling the break_handler below on re-entry | |
313 | * for jprobe processing, so get out doing nothing | |
314 | * more here. | |
315 | */ | |
316 | push_kprobe(kcb, p); | |
317 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
318 | if (p->pre_handler && p->pre_handler(p, regs)) | |
319 | return 1; | |
320 | kcb->kprobe_status = KPROBE_HIT_SS; | |
4ba069b8 | 321 | } |
0e917cc3 | 322 | enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn); |
4ba069b8 | 323 | return 1; |
0e917cc3 MS |
324 | } else if (kprobe_running()) { |
325 | p = __get_cpu_var(current_kprobe); | |
326 | if (p->break_handler && p->break_handler(p, regs)) { | |
327 | /* | |
328 | * Continuation after the jprobe completed and | |
329 | * caused the jprobe_return trap. The jprobe | |
330 | * break_handler "returns" to the original | |
331 | * function that still has the kprobe breakpoint | |
332 | * installed. We continue with single stepping. | |
333 | */ | |
334 | kcb->kprobe_status = KPROBE_HIT_SS; | |
335 | enable_singlestep(kcb, regs, | |
336 | (unsigned long) p->ainsn.insn); | |
337 | return 1; | |
338 | } /* else: | |
339 | * No kprobe at this address and the current kprobe | |
340 | * has no break handler (no jprobe!). The kernel just | |
341 | * exploded, let the standard trap handler pick up the | |
342 | * pieces. | |
343 | */ | |
344 | } /* else: | |
345 | * No kprobe at this address and no active kprobe. The trap has | |
346 | * not been caused by a kprobe breakpoint. The race of breakpoint | |
347 | * vs. kprobe remove does not exist because on s390 as we use | |
348 | * stop_machine to arm/disarm the breakpoints. | |
349 | */ | |
4ba069b8 | 350 | preempt_enable_no_resched(); |
0e917cc3 | 351 | return 0; |
4ba069b8 MG |
352 | } |
353 | ||
354 | /* | |
355 | * Function return probe trampoline: | |
356 | * - init_kprobes() establishes a probepoint here | |
357 | * - When the probed function returns, this probe | |
358 | * causes the handlers to fire | |
359 | */ | |
a806170e | 360 | static void __used kretprobe_trampoline_holder(void) |
4ba069b8 MG |
361 | { |
362 | asm volatile(".global kretprobe_trampoline\n" | |
363 | "kretprobe_trampoline: bcr 0,0\n"); | |
364 | } | |
365 | ||
366 | /* | |
367 | * Called when the probe at kretprobe trampoline is hit | |
368 | */ | |
2b67fc46 HC |
369 | static int __kprobes trampoline_probe_handler(struct kprobe *p, |
370 | struct pt_regs *regs) | |
4ba069b8 | 371 | { |
4a188635 | 372 | struct kretprobe_instance *ri; |
99219a3f | 373 | struct hlist_head *head, empty_rp; |
b67bfe0d | 374 | struct hlist_node *tmp; |
4a188635 MS |
375 | unsigned long flags, orig_ret_address; |
376 | unsigned long trampoline_address; | |
377 | kprobe_opcode_t *correct_ret_addr; | |
4ba069b8 | 378 | |
99219a3f | 379 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 380 | kretprobe_hash_lock(current, &head, &flags); |
4ba069b8 MG |
381 | |
382 | /* | |
383 | * It is possible to have multiple instances associated with a given | |
384 | * task either because an multiple functions in the call path | |
025dfdaf | 385 | * have a return probe installed on them, and/or more than one return |
4ba069b8 MG |
386 | * return probe was registered for a target function. |
387 | * | |
388 | * We can handle this because: | |
389 | * - instances are always inserted at the head of the list | |
390 | * - when multiple return probes are registered for the same | |
391 | * function, the first instance's ret_addr will point to the | |
392 | * real return address, and all the rest will point to | |
393 | * kretprobe_trampoline | |
394 | */ | |
4a188635 MS |
395 | ri = NULL; |
396 | orig_ret_address = 0; | |
397 | correct_ret_addr = NULL; | |
398 | trampoline_address = (unsigned long) &kretprobe_trampoline; | |
b67bfe0d | 399 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
4ba069b8 MG |
400 | if (ri->task != current) |
401 | /* another task is sharing our hash bucket */ | |
402 | continue; | |
403 | ||
4a188635 | 404 | orig_ret_address = (unsigned long) ri->ret_addr; |
89480801 MS |
405 | |
406 | if (orig_ret_address != trampoline_address) | |
407 | /* | |
408 | * This is the real return address. Any other | |
409 | * instances associated with this task are for | |
410 | * other calls deeper on the call stack | |
411 | */ | |
412 | break; | |
413 | } | |
414 | ||
415 | kretprobe_assert(ri, orig_ret_address, trampoline_address); | |
416 | ||
417 | correct_ret_addr = ri->ret_addr; | |
b67bfe0d | 418 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
89480801 MS |
419 | if (ri->task != current) |
420 | /* another task is sharing our hash bucket */ | |
421 | continue; | |
4ba069b8 | 422 | |
4a188635 | 423 | orig_ret_address = (unsigned long) ri->ret_addr; |
89480801 MS |
424 | |
425 | if (ri->rp && ri->rp->handler) { | |
426 | ri->ret_addr = correct_ret_addr; | |
427 | ri->rp->handler(ri, regs); | |
428 | } | |
429 | ||
99219a3f | 430 | recycle_rp_inst(ri, &empty_rp); |
4ba069b8 | 431 | |
4a188635 | 432 | if (orig_ret_address != trampoline_address) |
4ba069b8 MG |
433 | /* |
434 | * This is the real return address. Any other | |
435 | * instances associated with this task are for | |
436 | * other calls deeper on the call stack | |
437 | */ | |
438 | break; | |
4ba069b8 | 439 | } |
89480801 | 440 | |
4ba069b8 MG |
441 | regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE; |
442 | ||
b9599798 | 443 | pop_kprobe(get_kprobe_ctlblk()); |
ef53d9c5 | 444 | kretprobe_hash_unlock(current, &flags); |
4ba069b8 MG |
445 | preempt_enable_no_resched(); |
446 | ||
b67bfe0d | 447 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
99219a3f | 448 | hlist_del(&ri->hlist); |
449 | kfree(ri); | |
450 | } | |
4ba069b8 MG |
451 | /* |
452 | * By returning a non-zero value, we are telling | |
453 | * kprobe_handler() that we don't want the post_handler | |
454 | * to run (and have re-enabled preemption) | |
455 | */ | |
456 | return 1; | |
457 | } | |
458 | ||
459 | /* | |
460 | * Called after single-stepping. p->addr is the address of the | |
461 | * instruction whose first byte has been replaced by the "breakpoint" | |
462 | * instruction. To avoid the SMP problems that can occur when we | |
463 | * temporarily put back the original opcode to single-step, we | |
464 | * single-stepped a copy of the instruction. The address of this | |
465 | * copy is p->ainsn.insn. | |
466 | */ | |
467 | static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) | |
468 | { | |
469 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
fc0a1fea | 470 | unsigned long ip = regs->psw.addr & PSW_ADDR_INSN; |
ba640a59 | 471 | int fixup = get_fixup_type(p->ainsn.insn); |
4ba069b8 | 472 | |
ba640a59 | 473 | if (fixup & FIXUP_PSW_NORMAL) |
fc0a1fea | 474 | ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn; |
4ba069b8 | 475 | |
ba640a59 MS |
476 | if (fixup & FIXUP_BRANCH_NOT_TAKEN) { |
477 | int ilen = ((p->ainsn.insn[0] >> 14) + 3) & -2; | |
478 | if (ip - (unsigned long) p->ainsn.insn == ilen) | |
479 | ip = (unsigned long) p->addr + ilen; | |
480 | } | |
4ba069b8 | 481 | |
ba640a59 MS |
482 | if (fixup & FIXUP_RETURN_REGISTER) { |
483 | int reg = (p->ainsn.insn[0] & 0xf0) >> 4; | |
484 | regs->gprs[reg] += (unsigned long) p->addr - | |
485 | (unsigned long) p->ainsn.insn; | |
486 | } | |
4ba069b8 | 487 | |
fc0a1fea | 488 | disable_singlestep(kcb, regs, ip); |
4ba069b8 MG |
489 | } |
490 | ||
491 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
492 | { | |
4ba069b8 | 493 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
4a188635 | 494 | struct kprobe *p = kprobe_running(); |
4ba069b8 | 495 | |
4a188635 | 496 | if (!p) |
4ba069b8 MG |
497 | return 0; |
498 | ||
4a188635 | 499 | if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) { |
4ba069b8 | 500 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
4a188635 | 501 | p->post_handler(p, regs, 0); |
4ba069b8 MG |
502 | } |
503 | ||
4a188635 | 504 | resume_execution(p, regs); |
b9599798 | 505 | pop_kprobe(kcb); |
4ba069b8 MG |
506 | preempt_enable_no_resched(); |
507 | ||
508 | /* | |
509 | * if somebody else is singlestepping across a probe point, psw mask | |
510 | * will have PER set, in which case, continue the remaining processing | |
511 | * of do_single_step, as if this is not a probe hit. | |
512 | */ | |
4a188635 | 513 | if (regs->psw.mask & PSW_MASK_PER) |
4ba069b8 | 514 | return 0; |
4ba069b8 MG |
515 | |
516 | return 1; | |
517 | } | |
518 | ||
adb45839 | 519 | static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr) |
4ba069b8 | 520 | { |
4ba069b8 | 521 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
4a188635 | 522 | struct kprobe *p = kprobe_running(); |
4ba069b8 MG |
523 | const struct exception_table_entry *entry; |
524 | ||
525 | switch(kcb->kprobe_status) { | |
526 | case KPROBE_SWAP_INST: | |
527 | /* We are here because the instruction replacement failed */ | |
528 | return 0; | |
529 | case KPROBE_HIT_SS: | |
530 | case KPROBE_REENTER: | |
531 | /* | |
532 | * We are here because the instruction being single | |
533 | * stepped caused a page fault. We reset the current | |
534 | * kprobe and the nip points back to the probe address | |
535 | * and allow the page fault handler to continue as a | |
536 | * normal page fault. | |
537 | */ | |
4a188635 | 538 | disable_singlestep(kcb, regs, (unsigned long) p->addr); |
b9599798 | 539 | pop_kprobe(kcb); |
4ba069b8 MG |
540 | preempt_enable_no_resched(); |
541 | break; | |
542 | case KPROBE_HIT_ACTIVE: | |
543 | case KPROBE_HIT_SSDONE: | |
544 | /* | |
545 | * We increment the nmissed count for accounting, | |
23d6d3db | 546 | * we can also use npre/npostfault count for accounting |
4ba069b8 MG |
547 | * these specific fault cases. |
548 | */ | |
4a188635 | 549 | kprobes_inc_nmissed_count(p); |
4ba069b8 MG |
550 | |
551 | /* | |
552 | * We come here because instructions in the pre/post | |
553 | * handler caused the page_fault, this could happen | |
554 | * if handler tries to access user space by | |
555 | * copy_from_user(), get_user() etc. Let the | |
556 | * user-specified handler try to fix it first. | |
557 | */ | |
4a188635 | 558 | if (p->fault_handler && p->fault_handler(p, regs, trapnr)) |
4ba069b8 MG |
559 | return 1; |
560 | ||
561 | /* | |
562 | * In case the user-specified fault handler returned | |
563 | * zero, try to fix up. | |
564 | */ | |
565 | entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN); | |
566 | if (entry) { | |
eb608fb3 | 567 | regs->psw.addr = extable_fixup(entry) | PSW_ADDR_AMODE; |
4ba069b8 MG |
568 | return 1; |
569 | } | |
570 | ||
571 | /* | |
572 | * fixup_exception() could not handle it, | |
573 | * Let do_page_fault() fix it. | |
574 | */ | |
575 | break; | |
576 | default: | |
577 | break; | |
578 | } | |
579 | return 0; | |
580 | } | |
581 | ||
adb45839 MS |
582 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
583 | { | |
584 | int ret; | |
585 | ||
586 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) | |
587 | local_irq_disable(); | |
588 | ret = kprobe_trap_handler(regs, trapnr); | |
589 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) | |
590 | local_irq_restore(regs->psw.mask & ~PSW_MASK_PER); | |
591 | return ret; | |
592 | } | |
593 | ||
4ba069b8 MG |
594 | /* |
595 | * Wrapper routine to for handling exceptions. | |
596 | */ | |
597 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, | |
598 | unsigned long val, void *data) | |
599 | { | |
4a188635 | 600 | struct die_args *args = (struct die_args *) data; |
adb45839 | 601 | struct pt_regs *regs = args->regs; |
4ba069b8 MG |
602 | int ret = NOTIFY_DONE; |
603 | ||
adb45839 MS |
604 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) |
605 | local_irq_disable(); | |
606 | ||
4ba069b8 MG |
607 | switch (val) { |
608 | case DIE_BPT: | |
4a188635 | 609 | if (kprobe_handler(regs)) |
4ba069b8 MG |
610 | ret = NOTIFY_STOP; |
611 | break; | |
612 | case DIE_SSTEP: | |
4a188635 | 613 | if (post_kprobe_handler(regs)) |
4ba069b8 MG |
614 | ret = NOTIFY_STOP; |
615 | break; | |
616 | case DIE_TRAP: | |
adb45839 | 617 | if (!preemptible() && kprobe_running() && |
4a188635 | 618 | kprobe_trap_handler(regs, args->trapnr)) |
4ba069b8 | 619 | ret = NOTIFY_STOP; |
4ba069b8 MG |
620 | break; |
621 | default: | |
622 | break; | |
623 | } | |
adb45839 MS |
624 | |
625 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) | |
626 | local_irq_restore(regs->psw.mask & ~PSW_MASK_PER); | |
627 | ||
4ba069b8 MG |
628 | return ret; |
629 | } | |
630 | ||
631 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) | |
632 | { | |
633 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
4ba069b8 | 634 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
92b8cbf1 | 635 | unsigned long stack; |
4ba069b8 MG |
636 | |
637 | memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); | |
638 | ||
639 | /* setup return addr to the jprobe handler routine */ | |
4a188635 | 640 | regs->psw.addr = (unsigned long) jp->entry | PSW_ADDR_AMODE; |
adb45839 | 641 | regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT); |
4ba069b8 | 642 | |
4ba069b8 | 643 | /* r15 is the stack pointer */ |
92b8cbf1 | 644 | stack = (unsigned long) regs->gprs[15]; |
4ba069b8 | 645 | |
92b8cbf1 | 646 | memcpy(kcb->jprobes_stack, (void *) stack, MIN_STACK_SIZE(stack)); |
4ba069b8 MG |
647 | return 1; |
648 | } | |
649 | ||
650 | void __kprobes jprobe_return(void) | |
651 | { | |
652 | asm volatile(".word 0x0002"); | |
653 | } | |
654 | ||
c4736d96 | 655 | static void __used __kprobes jprobe_return_end(void) |
4ba069b8 MG |
656 | { |
657 | asm volatile("bcr 0,0"); | |
658 | } | |
659 | ||
660 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) | |
661 | { | |
662 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
92b8cbf1 MS |
663 | unsigned long stack; |
664 | ||
665 | stack = (unsigned long) kcb->jprobe_saved_regs.gprs[15]; | |
4ba069b8 MG |
666 | |
667 | /* Put the regs back */ | |
668 | memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); | |
669 | /* put the stack back */ | |
92b8cbf1 | 670 | memcpy((void *) stack, kcb->jprobes_stack, MIN_STACK_SIZE(stack)); |
4ba069b8 MG |
671 | preempt_enable_no_resched(); |
672 | return 1; | |
673 | } | |
674 | ||
4a188635 MS |
675 | static struct kprobe trampoline = { |
676 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, | |
4ba069b8 MG |
677 | .pre_handler = trampoline_probe_handler |
678 | }; | |
679 | ||
680 | int __init arch_init_kprobes(void) | |
681 | { | |
4a188635 | 682 | return register_kprobe(&trampoline); |
4ba069b8 | 683 | } |
bf8f6e5b AM |
684 | |
685 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
686 | { | |
4a188635 | 687 | return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline; |
bf8f6e5b | 688 | } |