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1da177e4 LT |
1 | /* |
2 | * Kernel Probes (KProbes) | |
3 | * arch/i386/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 contributions from | |
23 | * Rusty Russell). | |
24 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes | |
25 | * interface to access function arguments. | |
b94cce92 HN |
26 | * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston |
27 | * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi | |
28 | * <prasanna@in.ibm.com> added function-return probes. | |
1da177e4 LT |
29 | */ |
30 | ||
31 | #include <linux/config.h> | |
32 | #include <linux/kprobes.h> | |
33 | #include <linux/ptrace.h> | |
1da177e4 | 34 | #include <linux/preempt.h> |
7e1048b1 | 35 | #include <asm/cacheflush.h> |
1da177e4 LT |
36 | #include <asm/kdebug.h> |
37 | #include <asm/desc.h> | |
38 | ||
1da177e4 LT |
39 | void jprobe_return_end(void); |
40 | ||
9a0e3a86 AM |
41 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
42 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
43 | ||
1da177e4 LT |
44 | /* |
45 | * returns non-zero if opcode modifies the interrupt flag. | |
46 | */ | |
47 | static inline int is_IF_modifier(kprobe_opcode_t opcode) | |
48 | { | |
49 | switch (opcode) { | |
50 | case 0xfa: /* cli */ | |
51 | case 0xfb: /* sti */ | |
52 | case 0xcf: /* iret/iretd */ | |
53 | case 0x9d: /* popf/popfd */ | |
54 | return 1; | |
55 | } | |
56 | return 0; | |
57 | } | |
58 | ||
3d97ae5b | 59 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
1da177e4 LT |
60 | { |
61 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
7e1048b1 | 62 | p->opcode = *p->addr; |
49a2a1b8 | 63 | return 0; |
1da177e4 LT |
64 | } |
65 | ||
3d97ae5b | 66 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 67 | { |
7e1048b1 RL |
68 | *p->addr = BREAKPOINT_INSTRUCTION; |
69 | flush_icache_range((unsigned long) p->addr, | |
70 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); | |
1da177e4 LT |
71 | } |
72 | ||
3d97ae5b | 73 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 LT |
74 | { |
75 | *p->addr = p->opcode; | |
7e1048b1 RL |
76 | flush_icache_range((unsigned long) p->addr, |
77 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); | |
78 | } | |
79 | ||
9a0e3a86 | 80 | static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb) |
417c8da6 | 81 | { |
9a0e3a86 AM |
82 | kcb->prev_kprobe.kp = kprobe_running(); |
83 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
84 | kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags; | |
85 | kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags; | |
417c8da6 PP |
86 | } |
87 | ||
9a0e3a86 | 88 | static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
417c8da6 | 89 | { |
9a0e3a86 AM |
90 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
91 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
92 | kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags; | |
93 | kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags; | |
417c8da6 PP |
94 | } |
95 | ||
9a0e3a86 AM |
96 | static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
97 | struct kprobe_ctlblk *kcb) | |
417c8da6 | 98 | { |
9a0e3a86 AM |
99 | __get_cpu_var(current_kprobe) = p; |
100 | kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags | |
417c8da6 PP |
101 | = (regs->eflags & (TF_MASK | IF_MASK)); |
102 | if (is_IF_modifier(p->opcode)) | |
9a0e3a86 | 103 | kcb->kprobe_saved_eflags &= ~IF_MASK; |
417c8da6 PP |
104 | } |
105 | ||
1da177e4 LT |
106 | static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
107 | { | |
108 | regs->eflags |= TF_MASK; | |
109 | regs->eflags &= ~IF_MASK; | |
110 | /*single step inline if the instruction is an int3*/ | |
111 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
112 | regs->eip = (unsigned long)p->addr; | |
113 | else | |
114 | regs->eip = (unsigned long)&p->ainsn.insn; | |
115 | } | |
116 | ||
991a51d8 | 117 | /* Called with kretprobe_lock held */ |
3d97ae5b PP |
118 | void __kprobes arch_prepare_kretprobe(struct kretprobe *rp, |
119 | struct pt_regs *regs) | |
b94cce92 HN |
120 | { |
121 | unsigned long *sara = (unsigned long *)®s->esp; | |
4bdbd37f RL |
122 | struct kretprobe_instance *ri; |
123 | ||
124 | if ((ri = get_free_rp_inst(rp)) != NULL) { | |
125 | ri->rp = rp; | |
126 | ri->task = current; | |
127 | ri->ret_addr = (kprobe_opcode_t *) *sara; | |
b94cce92 | 128 | |
b94cce92 HN |
129 | /* Replace the return addr with trampoline addr */ |
130 | *sara = (unsigned long) &kretprobe_trampoline; | |
b94cce92 | 131 | |
4bdbd37f RL |
132 | add_rp_inst(ri); |
133 | } else { | |
134 | rp->nmissed++; | |
135 | } | |
b94cce92 HN |
136 | } |
137 | ||
1da177e4 LT |
138 | /* |
139 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
140 | * remain disabled thorough out this function. | |
141 | */ | |
3d97ae5b | 142 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
1da177e4 LT |
143 | { |
144 | struct kprobe *p; | |
145 | int ret = 0; | |
146 | kprobe_opcode_t *addr = NULL; | |
147 | unsigned long *lp; | |
d217d545 AM |
148 | struct kprobe_ctlblk *kcb; |
149 | ||
150 | /* | |
151 | * We don't want to be preempted for the entire | |
152 | * duration of kprobe processing | |
153 | */ | |
154 | preempt_disable(); | |
155 | kcb = get_kprobe_ctlblk(); | |
1da177e4 | 156 | |
1da177e4 LT |
157 | /* Check if the application is using LDT entry for its code segment and |
158 | * calculate the address by reading the base address from the LDT entry. | |
159 | */ | |
160 | if ((regs->xcs & 4) && (current->mm)) { | |
161 | lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8) | |
162 | + (char *) current->mm->context.ldt); | |
163 | addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip - | |
164 | sizeof(kprobe_opcode_t)); | |
165 | } else { | |
166 | addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t)); | |
167 | } | |
168 | /* Check we're not actually recursing */ | |
169 | if (kprobe_running()) { | |
1da177e4 LT |
170 | p = get_kprobe(addr); |
171 | if (p) { | |
9a0e3a86 | 172 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 173 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
1da177e4 | 174 | regs->eflags &= ~TF_MASK; |
9a0e3a86 | 175 | regs->eflags |= kcb->kprobe_saved_eflags; |
1da177e4 LT |
176 | goto no_kprobe; |
177 | } | |
417c8da6 PP |
178 | /* We have reentered the kprobe_handler(), since |
179 | * another probe was hit while within the handler. | |
180 | * We here save the original kprobes variables and | |
181 | * just single step on the instruction of the new probe | |
182 | * without calling any user handlers. | |
183 | */ | |
9a0e3a86 AM |
184 | save_previous_kprobe(kcb); |
185 | set_current_kprobe(p, regs, kcb); | |
bf8d5c52 | 186 | kprobes_inc_nmissed_count(p); |
417c8da6 | 187 | prepare_singlestep(p, regs); |
9a0e3a86 | 188 | kcb->kprobe_status = KPROBE_REENTER; |
417c8da6 | 189 | return 1; |
1da177e4 | 190 | } else { |
eb3a7292 KA |
191 | if (regs->eflags & VM_MASK) { |
192 | /* We are in virtual-8086 mode. Return 0 */ | |
193 | goto no_kprobe; | |
194 | } | |
195 | if (*addr != BREAKPOINT_INSTRUCTION) { | |
196 | /* The breakpoint instruction was removed by | |
197 | * another cpu right after we hit, no further | |
198 | * handling of this interrupt is appropriate | |
199 | */ | |
200 | regs->eip -= sizeof(kprobe_opcode_t); | |
201 | ret = 1; | |
202 | goto no_kprobe; | |
203 | } | |
9a0e3a86 | 204 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
205 | if (p->break_handler && p->break_handler(p, regs)) { |
206 | goto ss_probe; | |
207 | } | |
208 | } | |
1da177e4 LT |
209 | goto no_kprobe; |
210 | } | |
211 | ||
1da177e4 LT |
212 | p = get_kprobe(addr); |
213 | if (!p) { | |
1da177e4 LT |
214 | if (regs->eflags & VM_MASK) { |
215 | /* We are in virtual-8086 mode. Return 0 */ | |
216 | goto no_kprobe; | |
217 | } | |
218 | ||
219 | if (*addr != BREAKPOINT_INSTRUCTION) { | |
220 | /* | |
221 | * The breakpoint instruction was removed right | |
222 | * after we hit it. Another cpu has removed | |
223 | * either a probepoint or a debugger breakpoint | |
224 | * at this address. In either case, no further | |
225 | * handling of this interrupt is appropriate. | |
bce06494 JK |
226 | * Back up over the (now missing) int3 and run |
227 | * the original instruction. | |
1da177e4 | 228 | */ |
bce06494 | 229 | regs->eip -= sizeof(kprobe_opcode_t); |
1da177e4 LT |
230 | ret = 1; |
231 | } | |
232 | /* Not one of ours: let kernel handle it */ | |
233 | goto no_kprobe; | |
234 | } | |
235 | ||
9a0e3a86 AM |
236 | set_current_kprobe(p, regs, kcb); |
237 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1da177e4 LT |
238 | |
239 | if (p->pre_handler && p->pre_handler(p, regs)) | |
240 | /* handler has already set things up, so skip ss setup */ | |
241 | return 1; | |
242 | ||
243 | ss_probe: | |
244 | prepare_singlestep(p, regs); | |
9a0e3a86 | 245 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
246 | return 1; |
247 | ||
248 | no_kprobe: | |
d217d545 | 249 | preempt_enable_no_resched(); |
1da177e4 LT |
250 | return ret; |
251 | } | |
252 | ||
b94cce92 HN |
253 | /* |
254 | * For function-return probes, init_kprobes() establishes a probepoint | |
255 | * here. When a retprobed function returns, this probe is hit and | |
256 | * trampoline_probe_handler() runs, calling the kretprobe's handler. | |
257 | */ | |
258 | void kretprobe_trampoline_holder(void) | |
259 | { | |
260 | asm volatile ( ".global kretprobe_trampoline\n" | |
261 | "kretprobe_trampoline: \n" | |
262 | "nop\n"); | |
263 | } | |
264 | ||
265 | /* | |
266 | * Called when we hit the probe point at kretprobe_trampoline | |
267 | */ | |
3d97ae5b | 268 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) |
b94cce92 | 269 | { |
4bdbd37f RL |
270 | struct kretprobe_instance *ri = NULL; |
271 | struct hlist_head *head; | |
272 | struct hlist_node *node, *tmp; | |
991a51d8 | 273 | unsigned long flags, orig_ret_address = 0; |
4bdbd37f | 274 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
b94cce92 | 275 | |
991a51d8 | 276 | spin_lock_irqsave(&kretprobe_lock, flags); |
4bdbd37f | 277 | head = kretprobe_inst_table_head(current); |
b94cce92 | 278 | |
4bdbd37f RL |
279 | /* |
280 | * It is possible to have multiple instances associated with a given | |
281 | * task either because an multiple functions in the call path | |
282 | * have a return probe installed on them, and/or more then one return | |
283 | * return probe was registered for a target function. | |
284 | * | |
285 | * We can handle this because: | |
286 | * - instances are always inserted at the head of the list | |
287 | * - when multiple return probes are registered for the same | |
288 | * function, the first instance's ret_addr will point to the | |
289 | * real return address, and all the rest will point to | |
290 | * kretprobe_trampoline | |
291 | */ | |
292 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
293 | if (ri->task != current) | |
294 | /* another task is sharing our hash bucket */ | |
295 | continue; | |
296 | ||
297 | if (ri->rp && ri->rp->handler) | |
298 | ri->rp->handler(ri, regs); | |
299 | ||
300 | orig_ret_address = (unsigned long)ri->ret_addr; | |
b94cce92 | 301 | recycle_rp_inst(ri); |
4bdbd37f RL |
302 | |
303 | if (orig_ret_address != trampoline_address) | |
304 | /* | |
305 | * This is the real return address. Any other | |
306 | * instances associated with this task are for | |
307 | * other calls deeper on the call stack | |
308 | */ | |
309 | break; | |
b94cce92 | 310 | } |
4bdbd37f RL |
311 | |
312 | BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); | |
313 | regs->eip = orig_ret_address; | |
314 | ||
9a0e3a86 | 315 | reset_current_kprobe(); |
991a51d8 | 316 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
4bdbd37f RL |
317 | preempt_enable_no_resched(); |
318 | ||
66ff2d06 AM |
319 | /* |
320 | * By returning a non-zero value, we are telling | |
d217d545 AM |
321 | * kprobe_handler() that we don't want the post_handler |
322 | * to run (and have re-enabled preemption) | |
66ff2d06 | 323 | */ |
4bdbd37f | 324 | return 1; |
b94cce92 HN |
325 | } |
326 | ||
1da177e4 LT |
327 | /* |
328 | * Called after single-stepping. p->addr is the address of the | |
329 | * instruction whose first byte has been replaced by the "int 3" | |
330 | * instruction. To avoid the SMP problems that can occur when we | |
331 | * temporarily put back the original opcode to single-step, we | |
332 | * single-stepped a copy of the instruction. The address of this | |
333 | * copy is p->ainsn.insn. | |
334 | * | |
335 | * This function prepares to return from the post-single-step | |
336 | * interrupt. We have to fix up the stack as follows: | |
337 | * | |
338 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
339 | * the new eip is relative to the copied instruction. We need to make | |
340 | * it relative to the original instruction. | |
341 | * | |
342 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
343 | * flags are set in the just-pushed eflags, and may need to be cleared. | |
344 | * | |
345 | * 2) If the single-stepped instruction was a call, the return address | |
346 | * that is atop the stack is the address following the copied instruction. | |
347 | * We need to make it the address following the original instruction. | |
348 | */ | |
9a0e3a86 AM |
349 | static void __kprobes resume_execution(struct kprobe *p, |
350 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 LT |
351 | { |
352 | unsigned long *tos = (unsigned long *)®s->esp; | |
353 | unsigned long next_eip = 0; | |
354 | unsigned long copy_eip = (unsigned long)&p->ainsn.insn; | |
355 | unsigned long orig_eip = (unsigned long)p->addr; | |
356 | ||
357 | switch (p->ainsn.insn[0]) { | |
358 | case 0x9c: /* pushfl */ | |
359 | *tos &= ~(TF_MASK | IF_MASK); | |
9a0e3a86 | 360 | *tos |= kcb->kprobe_old_eflags; |
1da177e4 | 361 | break; |
0b9e2cac PP |
362 | case 0xc3: /* ret/lret */ |
363 | case 0xcb: | |
364 | case 0xc2: | |
365 | case 0xca: | |
366 | regs->eflags &= ~TF_MASK; | |
367 | /* eip is already adjusted, no more changes required*/ | |
368 | return; | |
1da177e4 LT |
369 | case 0xe8: /* call relative - Fix return addr */ |
370 | *tos = orig_eip + (*tos - copy_eip); | |
371 | break; | |
372 | case 0xff: | |
373 | if ((p->ainsn.insn[1] & 0x30) == 0x10) { | |
374 | /* call absolute, indirect */ | |
375 | /* Fix return addr; eip is correct. */ | |
376 | next_eip = regs->eip; | |
377 | *tos = orig_eip + (*tos - copy_eip); | |
378 | } else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ | |
379 | ((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ | |
380 | /* eip is correct. */ | |
381 | next_eip = regs->eip; | |
382 | } | |
383 | break; | |
384 | case 0xea: /* jmp absolute -- eip is correct */ | |
385 | next_eip = regs->eip; | |
386 | break; | |
387 | default: | |
388 | break; | |
389 | } | |
390 | ||
391 | regs->eflags &= ~TF_MASK; | |
392 | if (next_eip) { | |
393 | regs->eip = next_eip; | |
394 | } else { | |
395 | regs->eip = orig_eip + (regs->eip - copy_eip); | |
396 | } | |
397 | } | |
398 | ||
399 | /* | |
400 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
991a51d8 | 401 | * remain disabled thoroughout this function. |
1da177e4 LT |
402 | */ |
403 | static inline int post_kprobe_handler(struct pt_regs *regs) | |
404 | { | |
9a0e3a86 AM |
405 | struct kprobe *cur = kprobe_running(); |
406 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
407 | ||
408 | if (!cur) | |
1da177e4 LT |
409 | return 0; |
410 | ||
9a0e3a86 AM |
411 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
412 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
413 | cur->post_handler(cur, regs, 0); | |
417c8da6 | 414 | } |
1da177e4 | 415 | |
9a0e3a86 AM |
416 | resume_execution(cur, regs, kcb); |
417 | regs->eflags |= kcb->kprobe_saved_eflags; | |
1da177e4 | 418 | |
417c8da6 | 419 | /*Restore back the original saved kprobes variables and continue. */ |
9a0e3a86 AM |
420 | if (kcb->kprobe_status == KPROBE_REENTER) { |
421 | restore_previous_kprobe(kcb); | |
417c8da6 PP |
422 | goto out; |
423 | } | |
9a0e3a86 | 424 | reset_current_kprobe(); |
417c8da6 | 425 | out: |
1da177e4 LT |
426 | preempt_enable_no_resched(); |
427 | ||
428 | /* | |
429 | * if somebody else is singlestepping across a probe point, eflags | |
430 | * will have TF set, in which case, continue the remaining processing | |
431 | * of do_debug, as if this is not a probe hit. | |
432 | */ | |
433 | if (regs->eflags & TF_MASK) | |
434 | return 0; | |
435 | ||
436 | return 1; | |
437 | } | |
438 | ||
1da177e4 LT |
439 | static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
440 | { | |
9a0e3a86 AM |
441 | struct kprobe *cur = kprobe_running(); |
442 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
443 | ||
444 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
1da177e4 LT |
445 | return 1; |
446 | ||
9a0e3a86 AM |
447 | if (kcb->kprobe_status & KPROBE_HIT_SS) { |
448 | resume_execution(cur, regs, kcb); | |
449 | regs->eflags |= kcb->kprobe_old_eflags; | |
1da177e4 | 450 | |
9a0e3a86 | 451 | reset_current_kprobe(); |
1da177e4 LT |
452 | preempt_enable_no_resched(); |
453 | } | |
454 | return 0; | |
455 | } | |
456 | ||
457 | /* | |
458 | * Wrapper routine to for handling exceptions. | |
459 | */ | |
3d97ae5b PP |
460 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
461 | unsigned long val, void *data) | |
1da177e4 LT |
462 | { |
463 | struct die_args *args = (struct die_args *)data; | |
66ff2d06 AM |
464 | int ret = NOTIFY_DONE; |
465 | ||
1da177e4 LT |
466 | switch (val) { |
467 | case DIE_INT3: | |
468 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 469 | ret = NOTIFY_STOP; |
1da177e4 LT |
470 | break; |
471 | case DIE_DEBUG: | |
472 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 473 | ret = NOTIFY_STOP; |
1da177e4 LT |
474 | break; |
475 | case DIE_GPF: | |
1da177e4 | 476 | case DIE_PAGE_FAULT: |
d217d545 AM |
477 | /* kprobe_running() needs smp_processor_id() */ |
478 | preempt_disable(); | |
1da177e4 LT |
479 | if (kprobe_running() && |
480 | kprobe_fault_handler(args->regs, args->trapnr)) | |
66ff2d06 | 481 | ret = NOTIFY_STOP; |
d217d545 | 482 | preempt_enable(); |
1da177e4 LT |
483 | break; |
484 | default: | |
485 | break; | |
486 | } | |
66ff2d06 | 487 | return ret; |
1da177e4 LT |
488 | } |
489 | ||
3d97ae5b | 490 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
491 | { |
492 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
493 | unsigned long addr; | |
9a0e3a86 | 494 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 495 | |
9a0e3a86 AM |
496 | kcb->jprobe_saved_regs = *regs; |
497 | kcb->jprobe_saved_esp = ®s->esp; | |
498 | addr = (unsigned long)(kcb->jprobe_saved_esp); | |
1da177e4 LT |
499 | |
500 | /* | |
501 | * TBD: As Linus pointed out, gcc assumes that the callee | |
502 | * owns the argument space and could overwrite it, e.g. | |
503 | * tailcall optimization. So, to be absolutely safe | |
504 | * we also save and restore enough stack bytes to cover | |
505 | * the argument area. | |
506 | */ | |
9a0e3a86 AM |
507 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
508 | MIN_STACK_SIZE(addr)); | |
1da177e4 LT |
509 | regs->eflags &= ~IF_MASK; |
510 | regs->eip = (unsigned long)(jp->entry); | |
511 | return 1; | |
512 | } | |
513 | ||
3d97ae5b | 514 | void __kprobes jprobe_return(void) |
1da177e4 | 515 | { |
9a0e3a86 AM |
516 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
517 | ||
1da177e4 LT |
518 | asm volatile (" xchgl %%ebx,%%esp \n" |
519 | " int3 \n" | |
520 | " .globl jprobe_return_end \n" | |
521 | " jprobe_return_end: \n" | |
522 | " nop \n"::"b" | |
9a0e3a86 | 523 | (kcb->jprobe_saved_esp):"memory"); |
1da177e4 LT |
524 | } |
525 | ||
3d97ae5b | 526 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 527 | { |
9a0e3a86 | 528 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 529 | u8 *addr = (u8 *) (regs->eip - 1); |
9a0e3a86 | 530 | unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp); |
1da177e4 LT |
531 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
532 | ||
533 | if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { | |
9a0e3a86 | 534 | if (®s->esp != kcb->jprobe_saved_esp) { |
1da177e4 | 535 | struct pt_regs *saved_regs = |
9a0e3a86 AM |
536 | container_of(kcb->jprobe_saved_esp, |
537 | struct pt_regs, esp); | |
1da177e4 | 538 | printk("current esp %p does not match saved esp %p\n", |
9a0e3a86 | 539 | ®s->esp, kcb->jprobe_saved_esp); |
1da177e4 LT |
540 | printk("Saved registers for jprobe %p\n", jp); |
541 | show_registers(saved_regs); | |
542 | printk("Current registers\n"); | |
543 | show_registers(regs); | |
544 | BUG(); | |
545 | } | |
9a0e3a86 AM |
546 | *regs = kcb->jprobe_saved_regs; |
547 | memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, | |
1da177e4 | 548 | MIN_STACK_SIZE(stack_addr)); |
d217d545 | 549 | preempt_enable_no_resched(); |
1da177e4 LT |
550 | return 1; |
551 | } | |
552 | return 0; | |
553 | } | |
4bdbd37f RL |
554 | |
555 | static struct kprobe trampoline_p = { | |
556 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, | |
557 | .pre_handler = trampoline_probe_handler | |
558 | }; | |
559 | ||
6772926b | 560 | int __init arch_init_kprobes(void) |
4bdbd37f RL |
561 | { |
562 | return register_kprobe(&trampoline_p); | |
563 | } |