mm: hugetlb: fix hugepage memory leak caused by wrong reserve count
[linux/fpc-iii.git] / arch / sparc / kernel / kprobes.c
blobcd83be527586ee0be802266d8bc5f35c1b1b1121
1 /* arch/sparc64/kernel/kprobes.c
3 * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
4 */
6 #include <linux/kernel.h>
7 #include <linux/kprobes.h>
8 #include <linux/module.h>
9 #include <linux/kdebug.h>
10 #include <linux/slab.h>
11 #include <linux/context_tracking.h>
12 #include <asm/signal.h>
13 #include <asm/cacheflush.h>
14 #include <asm/uaccess.h>
16 /* We do not have hardware single-stepping on sparc64.
17 * So we implement software single-stepping with breakpoint
18 * traps. The top-level scheme is similar to that used
19 * in the x86 kprobes implementation.
21 * In the kprobe->ainsn.insn[] array we store the original
22 * instruction at index zero and a break instruction at
23 * index one.
25 * When we hit a kprobe we:
26 * - Run the pre-handler
27 * - Remember "regs->tnpc" and interrupt level stored in
28 * "regs->tstate" so we can restore them later
29 * - Disable PIL interrupts
30 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
31 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
32 * - Mark that we are actively in a kprobe
34 * At this point we wait for the second breakpoint at
35 * kprobe->ainsn.insn[1] to hit. When it does we:
36 * - Run the post-handler
37 * - Set regs->tpc to "remembered" regs->tnpc stored above,
38 * restore the PIL interrupt level in "regs->tstate" as well
39 * - Make any adjustments necessary to regs->tnpc in order
40 * to handle relative branches correctly. See below.
41 * - Mark that we are no longer actively in a kprobe.
44 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
45 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
47 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
49 int __kprobes arch_prepare_kprobe(struct kprobe *p)
51 if ((unsigned long) p->addr & 0x3UL)
52 return -EILSEQ;
54 p->ainsn.insn[0] = *p->addr;
55 flushi(&p->ainsn.insn[0]);
57 p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
58 flushi(&p->ainsn.insn[1]);
60 p->opcode = *p->addr;
61 return 0;
64 void __kprobes arch_arm_kprobe(struct kprobe *p)
66 *p->addr = BREAKPOINT_INSTRUCTION;
67 flushi(p->addr);
70 void __kprobes arch_disarm_kprobe(struct kprobe *p)
72 *p->addr = p->opcode;
73 flushi(p->addr);
76 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
78 kcb->prev_kprobe.kp = kprobe_running();
79 kcb->prev_kprobe.status = kcb->kprobe_status;
80 kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
81 kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
84 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
86 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
87 kcb->kprobe_status = kcb->prev_kprobe.status;
88 kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
89 kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
92 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
93 struct kprobe_ctlblk *kcb)
95 __this_cpu_write(current_kprobe, p);
96 kcb->kprobe_orig_tnpc = regs->tnpc;
97 kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
100 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
101 struct kprobe_ctlblk *kcb)
103 regs->tstate |= TSTATE_PIL;
105 /*single step inline, if it a breakpoint instruction*/
106 if (p->opcode == BREAKPOINT_INSTRUCTION) {
107 regs->tpc = (unsigned long) p->addr;
108 regs->tnpc = kcb->kprobe_orig_tnpc;
109 } else {
110 regs->tpc = (unsigned long) &p->ainsn.insn[0];
111 regs->tnpc = (unsigned long) &p->ainsn.insn[1];
115 static int __kprobes kprobe_handler(struct pt_regs *regs)
117 struct kprobe *p;
118 void *addr = (void *) regs->tpc;
119 int ret = 0;
120 struct kprobe_ctlblk *kcb;
123 * We don't want to be preempted for the entire
124 * duration of kprobe processing
126 preempt_disable();
127 kcb = get_kprobe_ctlblk();
129 if (kprobe_running()) {
130 p = get_kprobe(addr);
131 if (p) {
132 if (kcb->kprobe_status == KPROBE_HIT_SS) {
133 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
134 kcb->kprobe_orig_tstate_pil);
135 goto no_kprobe;
137 /* We have reentered the kprobe_handler(), since
138 * another probe was hit while within the handler.
139 * We here save the original kprobes variables and
140 * just single step on the instruction of the new probe
141 * without calling any user handlers.
143 save_previous_kprobe(kcb);
144 set_current_kprobe(p, regs, kcb);
145 kprobes_inc_nmissed_count(p);
146 kcb->kprobe_status = KPROBE_REENTER;
147 prepare_singlestep(p, regs, kcb);
148 return 1;
149 } else {
150 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
151 /* The breakpoint instruction was removed by
152 * another cpu right after we hit, no further
153 * handling of this interrupt is appropriate
155 ret = 1;
156 goto no_kprobe;
158 p = __this_cpu_read(current_kprobe);
159 if (p->break_handler && p->break_handler(p, regs))
160 goto ss_probe;
162 goto no_kprobe;
165 p = get_kprobe(addr);
166 if (!p) {
167 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
169 * The breakpoint instruction was removed right
170 * after we hit it. Another cpu has removed
171 * either a probepoint or a debugger breakpoint
172 * at this address. In either case, no further
173 * handling of this interrupt is appropriate.
175 ret = 1;
177 /* Not one of ours: let kernel handle it */
178 goto no_kprobe;
181 set_current_kprobe(p, regs, kcb);
182 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
183 if (p->pre_handler && p->pre_handler(p, regs))
184 return 1;
186 ss_probe:
187 prepare_singlestep(p, regs, kcb);
188 kcb->kprobe_status = KPROBE_HIT_SS;
189 return 1;
191 no_kprobe:
192 preempt_enable_no_resched();
193 return ret;
196 /* If INSN is a relative control transfer instruction,
197 * return the corrected branch destination value.
199 * regs->tpc and regs->tnpc still hold the values of the
200 * program counters at the time of trap due to the execution
201 * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1]
204 static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p,
205 struct pt_regs *regs)
207 unsigned long real_pc = (unsigned long) p->addr;
209 /* Branch not taken, no mods necessary. */
210 if (regs->tnpc == regs->tpc + 0x4UL)
211 return real_pc + 0x8UL;
213 /* The three cases are call, branch w/prediction,
214 * and traditional branch.
216 if ((insn & 0xc0000000) == 0x40000000 ||
217 (insn & 0xc1c00000) == 0x00400000 ||
218 (insn & 0xc1c00000) == 0x00800000) {
219 unsigned long ainsn_addr;
221 ainsn_addr = (unsigned long) &p->ainsn.insn[0];
223 /* The instruction did all the work for us
224 * already, just apply the offset to the correct
225 * instruction location.
227 return (real_pc + (regs->tnpc - ainsn_addr));
230 /* It is jmpl or some other absolute PC modification instruction,
231 * leave NPC as-is.
233 return regs->tnpc;
236 /* If INSN is an instruction which writes it's PC location
237 * into a destination register, fix that up.
239 static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
240 unsigned long real_pc)
242 unsigned long *slot = NULL;
244 /* Simplest case is 'call', which always uses %o7 */
245 if ((insn & 0xc0000000) == 0x40000000) {
246 slot = &regs->u_regs[UREG_I7];
249 /* 'jmpl' encodes the register inside of the opcode */
250 if ((insn & 0xc1f80000) == 0x81c00000) {
251 unsigned long rd = ((insn >> 25) & 0x1f);
253 if (rd <= 15) {
254 slot = &regs->u_regs[rd];
255 } else {
256 /* Hard case, it goes onto the stack. */
257 flushw_all();
259 rd -= 16;
260 slot = (unsigned long *)
261 (regs->u_regs[UREG_FP] + STACK_BIAS);
262 slot += rd;
265 if (slot != NULL)
266 *slot = real_pc;
270 * Called after single-stepping. p->addr is the address of the
271 * instruction which has been replaced by the breakpoint
272 * instruction. To avoid the SMP problems that can occur when we
273 * temporarily put back the original opcode to single-step, we
274 * single-stepped a copy of the instruction. The address of this
275 * copy is &p->ainsn.insn[0].
277 * This function prepares to return from the post-single-step
278 * breakpoint trap.
280 static void __kprobes resume_execution(struct kprobe *p,
281 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
283 u32 insn = p->ainsn.insn[0];
285 regs->tnpc = relbranch_fixup(insn, p, regs);
287 /* This assignment must occur after relbranch_fixup() */
288 regs->tpc = kcb->kprobe_orig_tnpc;
290 retpc_fixup(regs, insn, (unsigned long) p->addr);
292 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
293 kcb->kprobe_orig_tstate_pil);
296 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
298 struct kprobe *cur = kprobe_running();
299 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
301 if (!cur)
302 return 0;
304 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
305 kcb->kprobe_status = KPROBE_HIT_SSDONE;
306 cur->post_handler(cur, regs, 0);
309 resume_execution(cur, regs, kcb);
311 /*Restore back the original saved kprobes variables and continue. */
312 if (kcb->kprobe_status == KPROBE_REENTER) {
313 restore_previous_kprobe(kcb);
314 goto out;
316 reset_current_kprobe();
317 out:
318 preempt_enable_no_resched();
320 return 1;
323 int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
325 struct kprobe *cur = kprobe_running();
326 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
327 const struct exception_table_entry *entry;
329 switch(kcb->kprobe_status) {
330 case KPROBE_HIT_SS:
331 case KPROBE_REENTER:
333 * We are here because the instruction being single
334 * stepped caused a page fault. We reset the current
335 * kprobe and the tpc points back to the probe address
336 * and allow the page fault handler to continue as a
337 * normal page fault.
339 regs->tpc = (unsigned long)cur->addr;
340 regs->tnpc = kcb->kprobe_orig_tnpc;
341 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
342 kcb->kprobe_orig_tstate_pil);
343 if (kcb->kprobe_status == KPROBE_REENTER)
344 restore_previous_kprobe(kcb);
345 else
346 reset_current_kprobe();
347 preempt_enable_no_resched();
348 break;
349 case KPROBE_HIT_ACTIVE:
350 case KPROBE_HIT_SSDONE:
352 * We increment the nmissed count for accounting,
353 * we can also use npre/npostfault count for accounting
354 * these specific fault cases.
356 kprobes_inc_nmissed_count(cur);
359 * We come here because instructions in the pre/post
360 * handler caused the page_fault, this could happen
361 * if handler tries to access user space by
362 * copy_from_user(), get_user() etc. Let the
363 * user-specified handler try to fix it first.
365 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
366 return 1;
369 * In case the user-specified fault handler returned
370 * zero, try to fix up.
373 entry = search_exception_tables(regs->tpc);
374 if (entry) {
375 regs->tpc = entry->fixup;
376 regs->tnpc = regs->tpc + 4;
377 return 1;
381 * fixup_exception() could not handle it,
382 * Let do_page_fault() fix it.
384 break;
385 default:
386 break;
389 return 0;
393 * Wrapper routine to for handling exceptions.
395 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
396 unsigned long val, void *data)
398 struct die_args *args = (struct die_args *)data;
399 int ret = NOTIFY_DONE;
401 if (args->regs && user_mode(args->regs))
402 return ret;
404 switch (val) {
405 case DIE_DEBUG:
406 if (kprobe_handler(args->regs))
407 ret = NOTIFY_STOP;
408 break;
409 case DIE_DEBUG_2:
410 if (post_kprobe_handler(args->regs))
411 ret = NOTIFY_STOP;
412 break;
413 default:
414 break;
416 return ret;
419 asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
420 struct pt_regs *regs)
422 enum ctx_state prev_state = exception_enter();
424 BUG_ON(trap_level != 0x170 && trap_level != 0x171);
426 if (user_mode(regs)) {
427 local_irq_enable();
428 bad_trap(regs, trap_level);
429 goto out;
432 /* trap_level == 0x170 --> ta 0x70
433 * trap_level == 0x171 --> ta 0x71
435 if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
436 (trap_level == 0x170) ? "debug" : "debug_2",
437 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
438 bad_trap(regs, trap_level);
439 out:
440 exception_exit(prev_state);
443 /* Jprobes support. */
444 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
446 struct jprobe *jp = container_of(p, struct jprobe, kp);
447 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
449 memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
451 regs->tpc = (unsigned long) jp->entry;
452 regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
453 regs->tstate |= TSTATE_PIL;
455 return 1;
458 void __kprobes jprobe_return(void)
460 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
461 register unsigned long orig_fp asm("g1");
463 orig_fp = kcb->jprobe_saved_regs.u_regs[UREG_FP];
464 __asm__ __volatile__("\n"
465 "1: cmp %%sp, %0\n\t"
466 "blu,a,pt %%xcc, 1b\n\t"
467 " restore\n\t"
468 ".globl jprobe_return_trap_instruction\n"
469 "jprobe_return_trap_instruction:\n\t"
470 "ta 0x70"
471 : /* no outputs */
472 : "r" (orig_fp));
475 extern void jprobe_return_trap_instruction(void);
477 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
479 u32 *addr = (u32 *) regs->tpc;
480 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
482 if (addr == (u32 *) jprobe_return_trap_instruction) {
483 memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
484 preempt_enable_no_resched();
485 return 1;
487 return 0;
490 /* The value stored in the return address register is actually 2
491 * instructions before where the callee will return to.
492 * Sequences usually look something like this
494 * call some_function <--- return register points here
495 * nop <--- call delay slot
496 * whatever <--- where callee returns to
498 * To keep trampoline_probe_handler logic simpler, we normalize the
499 * value kept in ri->ret_addr so we don't need to keep adjusting it
500 * back and forth.
502 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
503 struct pt_regs *regs)
505 ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8);
507 /* Replace the return addr with trampoline addr */
508 regs->u_regs[UREG_RETPC] =
509 ((unsigned long)kretprobe_trampoline) - 8;
513 * Called when the probe at kretprobe trampoline is hit
515 static int __kprobes trampoline_probe_handler(struct kprobe *p,
516 struct pt_regs *regs)
518 struct kretprobe_instance *ri = NULL;
519 struct hlist_head *head, empty_rp;
520 struct hlist_node *tmp;
521 unsigned long flags, orig_ret_address = 0;
522 unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
524 INIT_HLIST_HEAD(&empty_rp);
525 kretprobe_hash_lock(current, &head, &flags);
528 * It is possible to have multiple instances associated with a given
529 * task either because an multiple functions in the call path
530 * have a return probe installed on them, and/or more than one return
531 * return probe was registered for a target function.
533 * We can handle this because:
534 * - instances are always inserted at the head of the list
535 * - when multiple return probes are registered for the same
536 * function, the first instance's ret_addr will point to the
537 * real return address, and all the rest will point to
538 * kretprobe_trampoline
540 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
541 if (ri->task != current)
542 /* another task is sharing our hash bucket */
543 continue;
545 if (ri->rp && ri->rp->handler)
546 ri->rp->handler(ri, regs);
548 orig_ret_address = (unsigned long)ri->ret_addr;
549 recycle_rp_inst(ri, &empty_rp);
551 if (orig_ret_address != trampoline_address)
553 * This is the real return address. Any other
554 * instances associated with this task are for
555 * other calls deeper on the call stack
557 break;
560 kretprobe_assert(ri, orig_ret_address, trampoline_address);
561 regs->tpc = orig_ret_address;
562 regs->tnpc = orig_ret_address + 4;
564 reset_current_kprobe();
565 kretprobe_hash_unlock(current, &flags);
566 preempt_enable_no_resched();
568 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
569 hlist_del(&ri->hlist);
570 kfree(ri);
573 * By returning a non-zero value, we are telling
574 * kprobe_handler() that we don't want the post_handler
575 * to run (and have re-enabled preemption)
577 return 1;
580 static void __used kretprobe_trampoline_holder(void)
582 asm volatile(".global kretprobe_trampoline\n"
583 "kretprobe_trampoline:\n"
584 "\tnop\n"
585 "\tnop\n");
587 static struct kprobe trampoline_p = {
588 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
589 .pre_handler = trampoline_probe_handler
592 int __init arch_init_kprobes(void)
594 return register_kprobe(&trampoline_p);
597 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
599 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
600 return 1;
602 return 0;