Commit | Line | Data |
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1da177e4 LT |
1 | /* arch/sparc64/kernel/kprobes.c |
2 | * | |
3 | * Copyright (C) 2004 David S. Miller <davem@davemloft.net> | |
4 | */ | |
5 | ||
1da177e4 LT |
6 | #include <linux/kernel.h> |
7 | #include <linux/kprobes.h> | |
b6700096 | 8 | #include <linux/module.h> |
1eeb66a1 | 9 | #include <linux/kdebug.h> |
1da177e4 | 10 | #include <asm/signal.h> |
05e14cb3 | 11 | #include <asm/cacheflush.h> |
b6700096 | 12 | #include <asm/uaccess.h> |
1da177e4 LT |
13 | |
14 | /* We do not have hardware single-stepping on sparc64. | |
15 | * So we implement software single-stepping with breakpoint | |
16 | * traps. The top-level scheme is similar to that used | |
17 | * in the x86 kprobes implementation. | |
18 | * | |
19 | * In the kprobe->ainsn.insn[] array we store the original | |
20 | * instruction at index zero and a break instruction at | |
21 | * index one. | |
22 | * | |
23 | * When we hit a kprobe we: | |
24 | * - Run the pre-handler | |
25 | * - Remember "regs->tnpc" and interrupt level stored in | |
26 | * "regs->tstate" so we can restore them later | |
27 | * - Disable PIL interrupts | |
28 | * - Set regs->tpc to point to kprobe->ainsn.insn[0] | |
29 | * - Set regs->tnpc to point to kprobe->ainsn.insn[1] | |
30 | * - Mark that we are actively in a kprobe | |
31 | * | |
32 | * At this point we wait for the second breakpoint at | |
33 | * kprobe->ainsn.insn[1] to hit. When it does we: | |
34 | * - Run the post-handler | |
35 | * - Set regs->tpc to "remembered" regs->tnpc stored above, | |
36 | * restore the PIL interrupt level in "regs->tstate" as well | |
37 | * - Make any adjustments necessary to regs->tnpc in order | |
38 | * to handle relative branches correctly. See below. | |
39 | * - Mark that we are no longer actively in a kprobe. | |
40 | */ | |
41 | ||
f215d985 AM |
42 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
43 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
44 | ||
f438d914 MH |
45 | struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}}; |
46 | ||
05e14cb3 | 47 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
1da177e4 | 48 | { |
936cf251 DM |
49 | if ((unsigned long) p->addr & 0x3UL) |
50 | return -EILSEQ; | |
51 | ||
1da177e4 | 52 | p->ainsn.insn[0] = *p->addr; |
f0882589 DM |
53 | flushi(&p->ainsn.insn[0]); |
54 | ||
1da177e4 | 55 | p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2; |
f0882589 DM |
56 | flushi(&p->ainsn.insn[1]); |
57 | ||
7e1048b1 | 58 | p->opcode = *p->addr; |
49a2a1b8 | 59 | return 0; |
7e1048b1 RL |
60 | } |
61 | ||
05e14cb3 | 62 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
7e1048b1 RL |
63 | { |
64 | *p->addr = BREAKPOINT_INSTRUCTION; | |
65 | flushi(p->addr); | |
66 | } | |
67 | ||
05e14cb3 | 68 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
7e1048b1 RL |
69 | { |
70 | *p->addr = p->opcode; | |
71 | flushi(p->addr); | |
1da177e4 LT |
72 | } |
73 | ||
07fab8da | 74 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
e539c233 | 75 | { |
f215d985 AM |
76 | kcb->prev_kprobe.kp = kprobe_running(); |
77 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
78 | kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc; | |
79 | kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil; | |
e539c233 PP |
80 | } |
81 | ||
07fab8da | 82 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
e539c233 | 83 | { |
f215d985 AM |
84 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
85 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
86 | kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc; | |
87 | kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil; | |
e539c233 PP |
88 | } |
89 | ||
07fab8da | 90 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
f215d985 | 91 | struct kprobe_ctlblk *kcb) |
1da177e4 | 92 | { |
f215d985 AM |
93 | __get_cpu_var(current_kprobe) = p; |
94 | kcb->kprobe_orig_tnpc = regs->tnpc; | |
95 | kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL); | |
e539c233 PP |
96 | } |
97 | ||
07fab8da | 98 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs, |
f215d985 | 99 | struct kprobe_ctlblk *kcb) |
e539c233 | 100 | { |
1da177e4 LT |
101 | regs->tstate |= TSTATE_PIL; |
102 | ||
103 | /*single step inline, if it a breakpoint instruction*/ | |
104 | if (p->opcode == BREAKPOINT_INSTRUCTION) { | |
105 | regs->tpc = (unsigned long) p->addr; | |
f215d985 | 106 | regs->tnpc = kcb->kprobe_orig_tnpc; |
1da177e4 LT |
107 | } else { |
108 | regs->tpc = (unsigned long) &p->ainsn.insn[0]; | |
109 | regs->tnpc = (unsigned long) &p->ainsn.insn[1]; | |
110 | } | |
111 | } | |
112 | ||
05e14cb3 | 113 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
1da177e4 LT |
114 | { |
115 | struct kprobe *p; | |
116 | void *addr = (void *) regs->tpc; | |
117 | int ret = 0; | |
d217d545 AM |
118 | struct kprobe_ctlblk *kcb; |
119 | ||
120 | /* | |
121 | * We don't want to be preempted for the entire | |
122 | * duration of kprobe processing | |
123 | */ | |
124 | preempt_disable(); | |
125 | kcb = get_kprobe_ctlblk(); | |
1da177e4 | 126 | |
1da177e4 | 127 | if (kprobe_running()) { |
1da177e4 LT |
128 | p = get_kprobe(addr); |
129 | if (p) { | |
f215d985 | 130 | if (kcb->kprobe_status == KPROBE_HIT_SS) { |
1da177e4 | 131 | regs->tstate = ((regs->tstate & ~TSTATE_PIL) | |
f215d985 | 132 | kcb->kprobe_orig_tstate_pil); |
1da177e4 LT |
133 | goto no_kprobe; |
134 | } | |
e539c233 PP |
135 | /* We have reentered the kprobe_handler(), since |
136 | * another probe was hit while within the handler. | |
137 | * We here save the original kprobes variables and | |
138 | * just single step on the instruction of the new probe | |
139 | * without calling any user handlers. | |
140 | */ | |
f215d985 AM |
141 | save_previous_kprobe(kcb); |
142 | set_current_kprobe(p, regs, kcb); | |
bf8d5c52 | 143 | kprobes_inc_nmissed_count(p); |
f215d985 AM |
144 | kcb->kprobe_status = KPROBE_REENTER; |
145 | prepare_singlestep(p, regs, kcb); | |
e539c233 | 146 | return 1; |
1da177e4 | 147 | } else { |
eb3a7292 KA |
148 | if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) { |
149 | /* The breakpoint instruction was removed by | |
150 | * another cpu right after we hit, no further | |
151 | * handling of this interrupt is appropriate | |
152 | */ | |
153 | ret = 1; | |
154 | goto no_kprobe; | |
155 | } | |
f215d985 | 156 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
157 | if (p->break_handler && p->break_handler(p, regs)) |
158 | goto ss_probe; | |
159 | } | |
1da177e4 LT |
160 | goto no_kprobe; |
161 | } | |
162 | ||
1da177e4 LT |
163 | p = get_kprobe(addr); |
164 | if (!p) { | |
1da177e4 LT |
165 | if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) { |
166 | /* | |
167 | * The breakpoint instruction was removed right | |
168 | * after we hit it. Another cpu has removed | |
169 | * either a probepoint or a debugger breakpoint | |
170 | * at this address. In either case, no further | |
171 | * handling of this interrupt is appropriate. | |
172 | */ | |
173 | ret = 1; | |
174 | } | |
175 | /* Not one of ours: let kernel handle it */ | |
176 | goto no_kprobe; | |
177 | } | |
178 | ||
f215d985 AM |
179 | set_current_kprobe(p, regs, kcb); |
180 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1da177e4 LT |
181 | if (p->pre_handler && p->pre_handler(p, regs)) |
182 | return 1; | |
183 | ||
184 | ss_probe: | |
f215d985 AM |
185 | prepare_singlestep(p, regs, kcb); |
186 | kcb->kprobe_status = KPROBE_HIT_SS; | |
1da177e4 LT |
187 | return 1; |
188 | ||
189 | no_kprobe: | |
d217d545 | 190 | preempt_enable_no_resched(); |
1da177e4 LT |
191 | return ret; |
192 | } | |
193 | ||
194 | /* If INSN is a relative control transfer instruction, | |
195 | * return the corrected branch destination value. | |
196 | * | |
f0882589 DM |
197 | * regs->tpc and regs->tnpc still hold the values of the |
198 | * program counters at the time of trap due to the execution | |
199 | * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1] | |
200 | * | |
1da177e4 | 201 | */ |
f0882589 DM |
202 | static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p, |
203 | struct pt_regs *regs) | |
1da177e4 | 204 | { |
f0882589 DM |
205 | unsigned long real_pc = (unsigned long) p->addr; |
206 | ||
1da177e4 | 207 | /* Branch not taken, no mods necessary. */ |
f0882589 DM |
208 | if (regs->tnpc == regs->tpc + 0x4UL) |
209 | return real_pc + 0x8UL; | |
1da177e4 LT |
210 | |
211 | /* The three cases are call, branch w/prediction, | |
212 | * and traditional branch. | |
213 | */ | |
214 | if ((insn & 0xc0000000) == 0x40000000 || | |
215 | (insn & 0xc1c00000) == 0x00400000 || | |
216 | (insn & 0xc1c00000) == 0x00800000) { | |
f0882589 DM |
217 | unsigned long ainsn_addr; |
218 | ||
219 | ainsn_addr = (unsigned long) &p->ainsn.insn[0]; | |
220 | ||
1da177e4 LT |
221 | /* The instruction did all the work for us |
222 | * already, just apply the offset to the correct | |
223 | * instruction location. | |
224 | */ | |
f0882589 | 225 | return (real_pc + (regs->tnpc - ainsn_addr)); |
1da177e4 LT |
226 | } |
227 | ||
f0882589 DM |
228 | /* It is jmpl or some other absolute PC modification instruction, |
229 | * leave NPC as-is. | |
230 | */ | |
231 | return regs->tnpc; | |
1da177e4 LT |
232 | } |
233 | ||
234 | /* If INSN is an instruction which writes it's PC location | |
235 | * into a destination register, fix that up. | |
236 | */ | |
05e14cb3 PP |
237 | static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn, |
238 | unsigned long real_pc) | |
1da177e4 LT |
239 | { |
240 | unsigned long *slot = NULL; | |
241 | ||
f0882589 | 242 | /* Simplest case is 'call', which always uses %o7 */ |
1da177e4 LT |
243 | if ((insn & 0xc0000000) == 0x40000000) { |
244 | slot = ®s->u_regs[UREG_I7]; | |
245 | } | |
246 | ||
f0882589 | 247 | /* 'jmpl' encodes the register inside of the opcode */ |
1da177e4 LT |
248 | if ((insn & 0xc1f80000) == 0x81c00000) { |
249 | unsigned long rd = ((insn >> 25) & 0x1f); | |
250 | ||
251 | if (rd <= 15) { | |
252 | slot = ®s->u_regs[rd]; | |
253 | } else { | |
254 | /* Hard case, it goes onto the stack. */ | |
255 | flushw_all(); | |
256 | ||
257 | rd -= 16; | |
258 | slot = (unsigned long *) | |
259 | (regs->u_regs[UREG_FP] + STACK_BIAS); | |
260 | slot += rd; | |
261 | } | |
262 | } | |
263 | if (slot != NULL) | |
264 | *slot = real_pc; | |
265 | } | |
266 | ||
267 | /* | |
268 | * Called after single-stepping. p->addr is the address of the | |
f0882589 | 269 | * instruction which has been replaced by the breakpoint |
1da177e4 LT |
270 | * instruction. To avoid the SMP problems that can occur when we |
271 | * temporarily put back the original opcode to single-step, we | |
272 | * single-stepped a copy of the instruction. The address of this | |
f0882589 | 273 | * copy is &p->ainsn.insn[0]. |
1da177e4 LT |
274 | * |
275 | * This function prepares to return from the post-single-step | |
276 | * breakpoint trap. | |
277 | */ | |
f215d985 AM |
278 | static void __kprobes resume_execution(struct kprobe *p, |
279 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 LT |
280 | { |
281 | u32 insn = p->ainsn.insn[0]; | |
282 | ||
f0882589 DM |
283 | regs->tnpc = relbranch_fixup(insn, p, regs); |
284 | ||
285 | /* This assignment must occur after relbranch_fixup() */ | |
f215d985 | 286 | regs->tpc = kcb->kprobe_orig_tnpc; |
f0882589 | 287 | |
1da177e4 LT |
288 | retpc_fixup(regs, insn, (unsigned long) p->addr); |
289 | ||
290 | regs->tstate = ((regs->tstate & ~TSTATE_PIL) | | |
f215d985 | 291 | kcb->kprobe_orig_tstate_pil); |
1da177e4 LT |
292 | } |
293 | ||
07fab8da | 294 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) |
1da177e4 | 295 | { |
f215d985 AM |
296 | struct kprobe *cur = kprobe_running(); |
297 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
298 | ||
299 | if (!cur) | |
1da177e4 LT |
300 | return 0; |
301 | ||
f215d985 AM |
302 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
303 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
304 | cur->post_handler(cur, regs, 0); | |
e539c233 | 305 | } |
1da177e4 | 306 | |
f215d985 | 307 | resume_execution(cur, regs, kcb); |
1da177e4 | 308 | |
e539c233 | 309 | /*Restore back the original saved kprobes variables and continue. */ |
f215d985 AM |
310 | if (kcb->kprobe_status == KPROBE_REENTER) { |
311 | restore_previous_kprobe(kcb); | |
e539c233 PP |
312 | goto out; |
313 | } | |
f215d985 | 314 | reset_current_kprobe(); |
e539c233 | 315 | out: |
1da177e4 LT |
316 | preempt_enable_no_resched(); |
317 | ||
318 | return 1; | |
319 | } | |
320 | ||
127cda1e | 321 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 322 | { |
f215d985 AM |
323 | struct kprobe *cur = kprobe_running(); |
324 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
b6700096 PP |
325 | const struct exception_table_entry *entry; |
326 | ||
327 | switch(kcb->kprobe_status) { | |
328 | case KPROBE_HIT_SS: | |
329 | case KPROBE_REENTER: | |
330 | /* | |
331 | * We are here because the instruction being single | |
332 | * stepped caused a page fault. We reset the current | |
333 | * kprobe and the tpc points back to the probe address | |
334 | * and allow the page fault handler to continue as a | |
335 | * normal page fault. | |
336 | */ | |
337 | regs->tpc = (unsigned long)cur->addr; | |
338 | regs->tnpc = kcb->kprobe_orig_tnpc; | |
339 | regs->tstate = ((regs->tstate & ~TSTATE_PIL) | | |
340 | kcb->kprobe_orig_tstate_pil); | |
341 | if (kcb->kprobe_status == KPROBE_REENTER) | |
342 | restore_previous_kprobe(kcb); | |
343 | else | |
344 | reset_current_kprobe(); | |
345 | preempt_enable_no_resched(); | |
346 | break; | |
347 | case KPROBE_HIT_ACTIVE: | |
348 | case KPROBE_HIT_SSDONE: | |
349 | /* | |
350 | * We increment the nmissed count for accounting, | |
351 | * we can also use npre/npostfault count for accouting | |
352 | * these specific fault cases. | |
353 | */ | |
354 | kprobes_inc_nmissed_count(cur); | |
355 | ||
356 | /* | |
357 | * We come here because instructions in the pre/post | |
358 | * handler caused the page_fault, this could happen | |
359 | * if handler tries to access user space by | |
360 | * copy_from_user(), get_user() etc. Let the | |
361 | * user-specified handler try to fix it first. | |
362 | */ | |
363 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
364 | return 1; | |
f215d985 | 365 | |
b6700096 PP |
366 | /* |
367 | * In case the user-specified fault handler returned | |
368 | * zero, try to fix up. | |
369 | */ | |
1da177e4 | 370 | |
b6700096 PP |
371 | entry = search_exception_tables(regs->tpc); |
372 | if (entry) { | |
373 | regs->tpc = entry->fixup; | |
374 | regs->tnpc = regs->tpc + 4; | |
375 | return 1; | |
376 | } | |
1da177e4 | 377 | |
b6700096 PP |
378 | /* |
379 | * fixup_exception() could not handle it, | |
380 | * Let do_page_fault() fix it. | |
381 | */ | |
382 | break; | |
383 | default: | |
384 | break; | |
1da177e4 | 385 | } |
b6700096 | 386 | |
1da177e4 LT |
387 | return 0; |
388 | } | |
389 | ||
390 | /* | |
391 | * Wrapper routine to for handling exceptions. | |
392 | */ | |
05e14cb3 PP |
393 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
394 | unsigned long val, void *data) | |
1da177e4 LT |
395 | { |
396 | struct die_args *args = (struct die_args *)data; | |
66ff2d06 AM |
397 | int ret = NOTIFY_DONE; |
398 | ||
2326c770 | 399 | if (args->regs && user_mode(args->regs)) |
400 | return ret; | |
401 | ||
1da177e4 LT |
402 | switch (val) { |
403 | case DIE_DEBUG: | |
404 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 405 | ret = NOTIFY_STOP; |
1da177e4 LT |
406 | break; |
407 | case DIE_DEBUG_2: | |
408 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 409 | ret = NOTIFY_STOP; |
1da177e4 | 410 | break; |
1da177e4 LT |
411 | default: |
412 | break; | |
413 | } | |
66ff2d06 | 414 | return ret; |
1da177e4 LT |
415 | } |
416 | ||
05e14cb3 PP |
417 | asmlinkage void __kprobes kprobe_trap(unsigned long trap_level, |
418 | struct pt_regs *regs) | |
1da177e4 LT |
419 | { |
420 | BUG_ON(trap_level != 0x170 && trap_level != 0x171); | |
421 | ||
422 | if (user_mode(regs)) { | |
423 | local_irq_enable(); | |
424 | bad_trap(regs, trap_level); | |
425 | return; | |
426 | } | |
427 | ||
428 | /* trap_level == 0x170 --> ta 0x70 | |
429 | * trap_level == 0x171 --> ta 0x71 | |
430 | */ | |
431 | if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2, | |
432 | (trap_level == 0x170) ? "debug" : "debug_2", | |
433 | regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP) | |
434 | bad_trap(regs, trap_level); | |
435 | } | |
436 | ||
437 | /* Jprobes support. */ | |
05e14cb3 | 438 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
439 | { |
440 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
f215d985 | 441 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 442 | |
f215d985 | 443 | memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs)); |
1da177e4 | 444 | |
1da177e4 LT |
445 | regs->tpc = (unsigned long) jp->entry; |
446 | regs->tnpc = ((unsigned long) jp->entry) + 0x4UL; | |
447 | regs->tstate |= TSTATE_PIL; | |
448 | ||
449 | return 1; | |
450 | } | |
451 | ||
05e14cb3 | 452 | void __kprobes jprobe_return(void) |
1da177e4 | 453 | { |
f0882589 DM |
454 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
455 | register unsigned long orig_fp asm("g1"); | |
456 | ||
457 | orig_fp = kcb->jprobe_saved_regs.u_regs[UREG_FP]; | |
458 | __asm__ __volatile__("\n" | |
459 | "1: cmp %%sp, %0\n\t" | |
460 | "blu,a,pt %%xcc, 1b\n\t" | |
461 | " restore\n\t" | |
462 | ".globl jprobe_return_trap_instruction\n" | |
1da177e4 | 463 | "jprobe_return_trap_instruction:\n\t" |
f0882589 DM |
464 | "ta 0x70" |
465 | : /* no outputs */ | |
466 | : "r" (orig_fp)); | |
1da177e4 LT |
467 | } |
468 | ||
469 | extern void jprobe_return_trap_instruction(void); | |
470 | ||
05e14cb3 | 471 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
472 | { |
473 | u32 *addr = (u32 *) regs->tpc; | |
f215d985 | 474 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 LT |
475 | |
476 | if (addr == (u32 *) jprobe_return_trap_instruction) { | |
f215d985 | 477 | memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs)); |
d217d545 | 478 | preempt_enable_no_resched(); |
1da177e4 LT |
479 | return 1; |
480 | } | |
481 | return 0; | |
482 | } | |
e539c233 | 483 | |
ef53d9c5 S |
484 | /* The value stored in the return address register is actually 2 |
485 | * instructions before where the callee will return to. | |
486 | * Sequences usually look something like this | |
d38f1220 DM |
487 | * |
488 | * call some_function <--- return register points here | |
489 | * nop <--- call delay slot | |
490 | * whatever <--- where callee returns to | |
491 | * | |
492 | * To keep trampoline_probe_handler logic simpler, we normalize the | |
493 | * value kept in ri->ret_addr so we don't need to keep adjusting it | |
494 | * back and forth. | |
495 | */ | |
496 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, | |
497 | struct pt_regs *regs) | |
498 | { | |
499 | ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8); | |
500 | ||
501 | /* Replace the return addr with trampoline addr */ | |
502 | regs->u_regs[UREG_RETPC] = | |
503 | ((unsigned long)kretprobe_trampoline) - 8; | |
504 | } | |
505 | ||
506 | /* | |
507 | * Called when the probe at kretprobe trampoline is hit | |
508 | */ | |
509 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) | |
510 | { | |
511 | struct kretprobe_instance *ri = NULL; | |
512 | struct hlist_head *head, empty_rp; | |
513 | struct hlist_node *node, *tmp; | |
514 | unsigned long flags, orig_ret_address = 0; | |
515 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; | |
516 | ||
517 | INIT_HLIST_HEAD(&empty_rp); | |
ef53d9c5 | 518 | kretprobe_hash_lock(current, &head, &flags); |
d38f1220 DM |
519 | |
520 | /* | |
521 | * It is possible to have multiple instances associated with a given | |
522 | * task either because an multiple functions in the call path | |
025dfdaf | 523 | * have a return probe installed on them, and/or more than one return |
d38f1220 DM |
524 | * return probe was registered for a target function. |
525 | * | |
526 | * We can handle this because: | |
527 | * - instances are always inserted at the head of the list | |
528 | * - when multiple return probes are registered for the same | |
529 | * function, the first instance's ret_addr will point to the | |
530 | * real return address, and all the rest will point to | |
531 | * kretprobe_trampoline | |
532 | */ | |
533 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
534 | if (ri->task != current) | |
535 | /* another task is sharing our hash bucket */ | |
536 | continue; | |
537 | ||
538 | if (ri->rp && ri->rp->handler) | |
539 | ri->rp->handler(ri, regs); | |
540 | ||
541 | orig_ret_address = (unsigned long)ri->ret_addr; | |
542 | recycle_rp_inst(ri, &empty_rp); | |
543 | ||
544 | if (orig_ret_address != trampoline_address) | |
545 | /* | |
546 | * This is the real return address. Any other | |
547 | * instances associated with this task are for | |
548 | * other calls deeper on the call stack | |
549 | */ | |
550 | break; | |
551 | } | |
552 | ||
553 | kretprobe_assert(ri, orig_ret_address, trampoline_address); | |
554 | regs->tpc = orig_ret_address; | |
555 | regs->tnpc = orig_ret_address + 4; | |
556 | ||
557 | reset_current_kprobe(); | |
ef53d9c5 | 558 | kretprobe_hash_unlock(current, &flags); |
d38f1220 DM |
559 | preempt_enable_no_resched(); |
560 | ||
561 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { | |
562 | hlist_del(&ri->hlist); | |
563 | kfree(ri); | |
564 | } | |
565 | /* | |
566 | * By returning a non-zero value, we are telling | |
567 | * kprobe_handler() that we don't want the post_handler | |
568 | * to run (and have re-enabled preemption) | |
569 | */ | |
570 | return 1; | |
571 | } | |
572 | ||
573 | void kretprobe_trampoline_holder(void) | |
574 | { | |
575 | asm volatile(".global kretprobe_trampoline\n" | |
576 | "kretprobe_trampoline:\n" | |
577 | "\tnop\n" | |
578 | "\tnop\n"); | |
579 | } | |
580 | static struct kprobe trampoline_p = { | |
581 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, | |
582 | .pre_handler = trampoline_probe_handler | |
583 | }; | |
584 | ||
585 | int __init arch_init_kprobes(void) | |
6772926b | 586 | { |
d38f1220 DM |
587 | return register_kprobe(&trampoline_p); |
588 | } | |
589 | ||
590 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
591 | { | |
592 | if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) | |
593 | return 1; | |
594 | ||
6772926b RL |
595 | return 0; |
596 | } |