ia64/kvm: compilation fix. export account_system_vtime.
[pv_ops_mirror.git] / arch / s390 / kernel / kprobes.c
blobed04d1372d5d0c536b4a24713bf10d041bc79458
1 /*
2 * Kernel Probes (KProbes)
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.
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.
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.
18 * Copyright (C) IBM Corporation, 2002, 2006
20 * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
23 #include <linux/kprobes.h>
24 #include <linux/ptrace.h>
25 #include <linux/preempt.h>
26 #include <linux/stop_machine.h>
27 #include <linux/kdebug.h>
28 #include <asm/cacheflush.h>
29 #include <asm/sections.h>
30 #include <asm/uaccess.h>
31 #include <linux/module.h>
33 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
34 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
36 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
38 int __kprobes arch_prepare_kprobe(struct kprobe *p)
40 /* Make sure the probe isn't going on a difficult instruction */
41 if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
42 return -EINVAL;
44 if ((unsigned long)p->addr & 0x01) {
45 printk("Attempt to register kprobe at an unaligned address\n");
46 return -EINVAL;
49 /* Use the get_insn_slot() facility for correctness */
50 if (!(p->ainsn.insn = get_insn_slot()))
51 return -ENOMEM;
53 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
55 get_instruction_type(&p->ainsn);
56 p->opcode = *p->addr;
57 return 0;
60 int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
62 switch (*(__u8 *) instruction) {
63 case 0x0c: /* bassm */
64 case 0x0b: /* bsm */
65 case 0x83: /* diag */
66 case 0x44: /* ex */
67 return -EINVAL;
69 switch (*(__u16 *) instruction) {
70 case 0x0101: /* pr */
71 case 0xb25a: /* bsa */
72 case 0xb240: /* bakr */
73 case 0xb258: /* bsg */
74 case 0xb218: /* pc */
75 case 0xb228: /* pt */
76 return -EINVAL;
78 return 0;
81 void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
83 /* default fixup method */
84 ainsn->fixup = FIXUP_PSW_NORMAL;
86 /* save r1 operand */
87 ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
89 /* save the instruction length (pop 5-5) in bytes */
90 switch (*(__u8 *) (ainsn->insn) >> 6) {
91 case 0:
92 ainsn->ilen = 2;
93 break;
94 case 1:
95 case 2:
96 ainsn->ilen = 4;
97 break;
98 case 3:
99 ainsn->ilen = 6;
100 break;
103 switch (*(__u8 *) ainsn->insn) {
104 case 0x05: /* balr */
105 case 0x0d: /* basr */
106 ainsn->fixup = FIXUP_RETURN_REGISTER;
107 /* if r2 = 0, no branch will be taken */
108 if ((*ainsn->insn & 0x0f) == 0)
109 ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
110 break;
111 case 0x06: /* bctr */
112 case 0x07: /* bcr */
113 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
114 break;
115 case 0x45: /* bal */
116 case 0x4d: /* bas */
117 ainsn->fixup = FIXUP_RETURN_REGISTER;
118 break;
119 case 0x47: /* bc */
120 case 0x46: /* bct */
121 case 0x86: /* bxh */
122 case 0x87: /* bxle */
123 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
124 break;
125 case 0x82: /* lpsw */
126 ainsn->fixup = FIXUP_NOT_REQUIRED;
127 break;
128 case 0xb2: /* lpswe */
129 if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
130 ainsn->fixup = FIXUP_NOT_REQUIRED;
132 break;
133 case 0xa7: /* bras */
134 if ((*ainsn->insn & 0x0f) == 0x05) {
135 ainsn->fixup |= FIXUP_RETURN_REGISTER;
137 break;
138 case 0xc0:
139 if ((*ainsn->insn & 0x0f) == 0x00 /* larl */
140 || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
141 ainsn->fixup |= FIXUP_RETURN_REGISTER;
142 break;
143 case 0xeb:
144 if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 || /* bxhg */
145 *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
146 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
148 break;
149 case 0xe3: /* bctg */
150 if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
151 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
153 break;
157 static int __kprobes swap_instruction(void *aref)
159 struct ins_replace_args *args = aref;
160 u32 *addr;
161 u32 instr;
162 int err = -EFAULT;
165 * Text segment is read-only, hence we use stura to bypass dynamic
166 * address translation to exchange the instruction. Since stura
167 * always operates on four bytes, but we only want to exchange two
168 * bytes do some calculations to get things right. In addition we
169 * shall not cross any page boundaries (vmalloc area!) when writing
170 * the new instruction.
172 addr = (u32 *)((unsigned long)args->ptr & -4UL);
173 if ((unsigned long)args->ptr & 2)
174 instr = ((*addr) & 0xffff0000) | args->new;
175 else
176 instr = ((*addr) & 0x0000ffff) | args->new << 16;
178 asm volatile(
179 " lra %1,0(%1)\n"
180 "0: stura %2,%1\n"
181 "1: la %0,0\n"
182 "2:\n"
183 EX_TABLE(0b,2b)
184 : "+d" (err)
185 : "a" (addr), "d" (instr)
186 : "memory", "cc");
188 return err;
191 void __kprobes arch_arm_kprobe(struct kprobe *p)
193 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
194 unsigned long status = kcb->kprobe_status;
195 struct ins_replace_args args;
197 args.ptr = p->addr;
198 args.old = p->opcode;
199 args.new = BREAKPOINT_INSTRUCTION;
201 kcb->kprobe_status = KPROBE_SWAP_INST;
202 stop_machine_run(swap_instruction, &args, NR_CPUS);
203 kcb->kprobe_status = status;
206 void __kprobes arch_disarm_kprobe(struct kprobe *p)
208 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
209 unsigned long status = kcb->kprobe_status;
210 struct ins_replace_args args;
212 args.ptr = p->addr;
213 args.old = BREAKPOINT_INSTRUCTION;
214 args.new = p->opcode;
216 kcb->kprobe_status = KPROBE_SWAP_INST;
217 stop_machine_run(swap_instruction, &args, NR_CPUS);
218 kcb->kprobe_status = status;
221 void __kprobes arch_remove_kprobe(struct kprobe *p)
223 mutex_lock(&kprobe_mutex);
224 free_insn_slot(p->ainsn.insn, 0);
225 mutex_unlock(&kprobe_mutex);
228 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
230 per_cr_bits kprobe_per_regs[1];
232 memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
233 regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
235 /* Set up the per control reg info, will pass to lctl */
236 kprobe_per_regs[0].em_instruction_fetch = 1;
237 kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
238 kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
240 /* Set the PER control regs, turns on single step for this address */
241 __ctl_load(kprobe_per_regs, 9, 11);
242 regs->psw.mask |= PSW_MASK_PER;
243 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
246 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
248 kcb->prev_kprobe.kp = kprobe_running();
249 kcb->prev_kprobe.status = kcb->kprobe_status;
250 kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
251 memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
252 sizeof(kcb->kprobe_saved_ctl));
255 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
257 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
258 kcb->kprobe_status = kcb->prev_kprobe.status;
259 kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
260 memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
261 sizeof(kcb->kprobe_saved_ctl));
264 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
265 struct kprobe_ctlblk *kcb)
267 __get_cpu_var(current_kprobe) = p;
268 /* Save the interrupt and per flags */
269 kcb->kprobe_saved_imask = regs->psw.mask &
270 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
271 /* Save the control regs that govern PER */
272 __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
275 /* Called with kretprobe_lock held */
276 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
277 struct pt_regs *regs)
279 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
281 /* Replace the return addr with trampoline addr */
282 regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
285 static int __kprobes kprobe_handler(struct pt_regs *regs)
287 struct kprobe *p;
288 int ret = 0;
289 unsigned long *addr = (unsigned long *)
290 ((regs->psw.addr & PSW_ADDR_INSN) - 2);
291 struct kprobe_ctlblk *kcb;
294 * We don't want to be preempted for the entire
295 * duration of kprobe processing
297 preempt_disable();
298 kcb = get_kprobe_ctlblk();
300 /* Check we're not actually recursing */
301 if (kprobe_running()) {
302 p = get_kprobe(addr);
303 if (p) {
304 if (kcb->kprobe_status == KPROBE_HIT_SS &&
305 *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
306 regs->psw.mask &= ~PSW_MASK_PER;
307 regs->psw.mask |= kcb->kprobe_saved_imask;
308 goto no_kprobe;
310 /* We have reentered the kprobe_handler(), since
311 * another probe was hit while within the handler.
312 * We here save the original kprobes variables and
313 * just single step on the instruction of the new probe
314 * without calling any user handlers.
316 save_previous_kprobe(kcb);
317 set_current_kprobe(p, regs, kcb);
318 kprobes_inc_nmissed_count(p);
319 prepare_singlestep(p, regs);
320 kcb->kprobe_status = KPROBE_REENTER;
321 return 1;
322 } else {
323 p = __get_cpu_var(current_kprobe);
324 if (p->break_handler && p->break_handler(p, regs)) {
325 goto ss_probe;
328 goto no_kprobe;
331 p = get_kprobe(addr);
332 if (!p)
334 * No kprobe at this address. The fault has not been
335 * caused by a kprobe breakpoint. The race of breakpoint
336 * vs. kprobe remove does not exist because on s390 we
337 * use stop_machine_run to arm/disarm the breakpoints.
339 goto no_kprobe;
341 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
342 set_current_kprobe(p, regs, kcb);
343 if (p->pre_handler && p->pre_handler(p, regs))
344 /* handler has already set things up, so skip ss setup */
345 return 1;
347 ss_probe:
348 prepare_singlestep(p, regs);
349 kcb->kprobe_status = KPROBE_HIT_SS;
350 return 1;
352 no_kprobe:
353 preempt_enable_no_resched();
354 return ret;
358 * Function return probe trampoline:
359 * - init_kprobes() establishes a probepoint here
360 * - When the probed function returns, this probe
361 * causes the handlers to fire
363 static void __used kretprobe_trampoline_holder(void)
365 asm volatile(".global kretprobe_trampoline\n"
366 "kretprobe_trampoline: bcr 0,0\n");
370 * Called when the probe at kretprobe trampoline is hit
372 static int __kprobes trampoline_probe_handler(struct kprobe *p,
373 struct pt_regs *regs)
375 struct kretprobe_instance *ri = NULL;
376 struct hlist_head *head, empty_rp;
377 struct hlist_node *node, *tmp;
378 unsigned long flags, orig_ret_address = 0;
379 unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
381 INIT_HLIST_HEAD(&empty_rp);
382 spin_lock_irqsave(&kretprobe_lock, flags);
383 head = kretprobe_inst_table_head(current);
386 * It is possible to have multiple instances associated with a given
387 * task either because an multiple functions in the call path
388 * have a return probe installed on them, and/or more then one return
389 * return probe was registered for a target function.
391 * We can handle this because:
392 * - instances are always inserted at the head of the list
393 * - when multiple return probes are registered for the same
394 * function, the first instance's ret_addr will point to the
395 * real return address, and all the rest will point to
396 * kretprobe_trampoline
398 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
399 if (ri->task != current)
400 /* another task is sharing our hash bucket */
401 continue;
403 if (ri->rp && ri->rp->handler)
404 ri->rp->handler(ri, regs);
406 orig_ret_address = (unsigned long)ri->ret_addr;
407 recycle_rp_inst(ri, &empty_rp);
409 if (orig_ret_address != trampoline_address) {
411 * This is the real return address. Any other
412 * instances associated with this task are for
413 * other calls deeper on the call stack
415 break;
418 kretprobe_assert(ri, orig_ret_address, trampoline_address);
419 regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
421 reset_current_kprobe();
422 spin_unlock_irqrestore(&kretprobe_lock, flags);
423 preempt_enable_no_resched();
425 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
426 hlist_del(&ri->hlist);
427 kfree(ri);
430 * By returning a non-zero value, we are telling
431 * kprobe_handler() that we don't want the post_handler
432 * to run (and have re-enabled preemption)
434 return 1;
438 * Called after single-stepping. p->addr is the address of the
439 * instruction whose first byte has been replaced by the "breakpoint"
440 * instruction. To avoid the SMP problems that can occur when we
441 * temporarily put back the original opcode to single-step, we
442 * single-stepped a copy of the instruction. The address of this
443 * copy is p->ainsn.insn.
445 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
447 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
449 regs->psw.addr &= PSW_ADDR_INSN;
451 if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
452 regs->psw.addr = (unsigned long)p->addr +
453 ((unsigned long)regs->psw.addr -
454 (unsigned long)p->ainsn.insn);
456 if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
457 if ((unsigned long)regs->psw.addr -
458 (unsigned long)p->ainsn.insn == p->ainsn.ilen)
459 regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
461 if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
462 regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
463 (regs->gprs[p->ainsn.reg] -
464 (unsigned long)p->ainsn.insn))
465 | PSW_ADDR_AMODE;
467 regs->psw.addr |= PSW_ADDR_AMODE;
468 /* turn off PER mode */
469 regs->psw.mask &= ~PSW_MASK_PER;
470 /* Restore the original per control regs */
471 __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
472 regs->psw.mask |= kcb->kprobe_saved_imask;
475 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
477 struct kprobe *cur = kprobe_running();
478 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
480 if (!cur)
481 return 0;
483 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
484 kcb->kprobe_status = KPROBE_HIT_SSDONE;
485 cur->post_handler(cur, regs, 0);
488 resume_execution(cur, regs);
490 /*Restore back the original saved kprobes variables and continue. */
491 if (kcb->kprobe_status == KPROBE_REENTER) {
492 restore_previous_kprobe(kcb);
493 goto out;
495 reset_current_kprobe();
496 out:
497 preempt_enable_no_resched();
500 * if somebody else is singlestepping across a probe point, psw mask
501 * will have PER set, in which case, continue the remaining processing
502 * of do_single_step, as if this is not a probe hit.
504 if (regs->psw.mask & PSW_MASK_PER) {
505 return 0;
508 return 1;
511 int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
513 struct kprobe *cur = kprobe_running();
514 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
515 const struct exception_table_entry *entry;
517 switch(kcb->kprobe_status) {
518 case KPROBE_SWAP_INST:
519 /* We are here because the instruction replacement failed */
520 return 0;
521 case KPROBE_HIT_SS:
522 case KPROBE_REENTER:
524 * We are here because the instruction being single
525 * stepped caused a page fault. We reset the current
526 * kprobe and the nip points back to the probe address
527 * and allow the page fault handler to continue as a
528 * normal page fault.
530 regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
531 regs->psw.mask &= ~PSW_MASK_PER;
532 regs->psw.mask |= kcb->kprobe_saved_imask;
533 if (kcb->kprobe_status == KPROBE_REENTER)
534 restore_previous_kprobe(kcb);
535 else
536 reset_current_kprobe();
537 preempt_enable_no_resched();
538 break;
539 case KPROBE_HIT_ACTIVE:
540 case KPROBE_HIT_SSDONE:
542 * We increment the nmissed count for accounting,
543 * we can also use npre/npostfault count for accouting
544 * these specific fault cases.
546 kprobes_inc_nmissed_count(cur);
549 * We come here because instructions in the pre/post
550 * handler caused the page_fault, this could happen
551 * if handler tries to access user space by
552 * copy_from_user(), get_user() etc. Let the
553 * user-specified handler try to fix it first.
555 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
556 return 1;
559 * In case the user-specified fault handler returned
560 * zero, try to fix up.
562 entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
563 if (entry) {
564 regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
565 return 1;
569 * fixup_exception() could not handle it,
570 * Let do_page_fault() fix it.
572 break;
573 default:
574 break;
576 return 0;
580 * Wrapper routine to for handling exceptions.
582 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
583 unsigned long val, void *data)
585 struct die_args *args = (struct die_args *)data;
586 int ret = NOTIFY_DONE;
588 switch (val) {
589 case DIE_BPT:
590 if (kprobe_handler(args->regs))
591 ret = NOTIFY_STOP;
592 break;
593 case DIE_SSTEP:
594 if (post_kprobe_handler(args->regs))
595 ret = NOTIFY_STOP;
596 break;
597 case DIE_TRAP:
598 /* kprobe_running() needs smp_processor_id() */
599 preempt_disable();
600 if (kprobe_running() &&
601 kprobe_fault_handler(args->regs, args->trapnr))
602 ret = NOTIFY_STOP;
603 preempt_enable();
604 break;
605 default:
606 break;
608 return ret;
611 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
613 struct jprobe *jp = container_of(p, struct jprobe, kp);
614 unsigned long addr;
615 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
617 memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
619 /* setup return addr to the jprobe handler routine */
620 regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
622 /* r14 is the function return address */
623 kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];
624 /* r15 is the stack pointer */
625 kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];
626 addr = (unsigned long)kcb->jprobe_saved_r15;
628 memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
629 MIN_STACK_SIZE(addr));
630 return 1;
633 void __kprobes jprobe_return(void)
635 asm volatile(".word 0x0002");
638 void __kprobes jprobe_return_end(void)
640 asm volatile("bcr 0,0");
643 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
645 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
646 unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);
648 /* Put the regs back */
649 memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
650 /* put the stack back */
651 memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
652 MIN_STACK_SIZE(stack_addr));
653 preempt_enable_no_resched();
654 return 1;
657 static struct kprobe trampoline_p = {
658 .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
659 .pre_handler = trampoline_probe_handler
662 int __init arch_init_kprobes(void)
664 return register_kprobe(&trampoline_p);
667 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
669 if (p->addr == (kprobe_opcode_t *) & kretprobe_trampoline)
670 return 1;
671 return 0;