2 * arch/tile/kernel/kprobes.c
5 * Some portions copied from the MIPS version.
7 * Copyright (C) IBM Corporation, 2002, 2004
8 * Copyright 2006 Sony Corp.
9 * Copyright 2010 Cavium Networks
11 * Copyright 2012 Tilera Corporation. All Rights Reserved.
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation, version 2.
17 * This program is distributed in the hope that it will be useful, but
18 * WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
20 * NON INFRINGEMENT. See the GNU General Public License for
24 #include <linux/kprobes.h>
25 #include <linux/kdebug.h>
26 #include <linux/module.h>
27 #include <linux/slab.h>
28 #include <linux/uaccess.h>
29 #include <asm/cacheflush.h>
31 #include <arch/opcode.h>
33 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
34 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
36 tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
37 tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
40 * Check whether instruction is branch or jump, or if executing it
41 * has different results depending on where it is executed (e.g. lnk).
43 static int __kprobes insn_has_control(kprobe_opcode_t insn)
45 if (get_Mode(insn) != 0) { /* Y-format bundle */
46 if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 ||
47 get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1)
50 switch (get_UnaryOpcodeExtension_Y1(insn)) {
51 case JALRP_UNARY_OPCODE_Y1:
52 case JALR_UNARY_OPCODE_Y1:
53 case JRP_UNARY_OPCODE_Y1:
54 case JR_UNARY_OPCODE_Y1:
55 case LNK_UNARY_OPCODE_Y1:
62 switch (get_Opcode_X1(insn)) {
63 case BRANCH_OPCODE_X1: /* branch instructions */
64 case JUMP_OPCODE_X1: /* jump instructions: j and jal */
67 case RRR_0_OPCODE_X1: /* other jump instructions */
68 if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1)
70 switch (get_UnaryOpcodeExtension_X1(insn)) {
71 case JALRP_UNARY_OPCODE_X1:
72 case JALR_UNARY_OPCODE_X1:
73 case JRP_UNARY_OPCODE_X1:
74 case JR_UNARY_OPCODE_X1:
75 case LNK_UNARY_OPCODE_X1:
85 int __kprobes arch_prepare_kprobe(struct kprobe *p)
87 unsigned long addr = (unsigned long)p->addr;
89 if (addr & (sizeof(kprobe_opcode_t) - 1))
92 if (insn_has_control(*p->addr)) {
93 pr_notice("Kprobes for control instructions are not "
98 /* insn: must be on special executable page on tile. */
99 p->ainsn.insn = get_insn_slot();
104 * In the kprobe->ainsn.insn[] array we store the original
105 * instruction at index zero and a break trap instruction at
108 memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
109 p->ainsn.insn[1] = breakpoint2_insn;
110 p->opcode = *p->addr;
115 void __kprobes arch_arm_kprobe(struct kprobe *p)
117 unsigned long addr_wr;
119 /* Operate on writable kernel text mapping. */
120 addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
122 if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
123 sizeof(breakpoint_insn)))
124 pr_err("%s: failed to enable kprobe\n", __func__);
130 void __kprobes arch_disarm_kprobe(struct kprobe *kp)
132 unsigned long addr_wr;
134 /* Operate on writable kernel text mapping. */
135 addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
137 if (probe_kernel_write((void *)addr_wr, &kp->opcode,
139 pr_err("%s: failed to enable kprobe\n", __func__);
145 void __kprobes arch_remove_kprobe(struct kprobe *p)
148 free_insn_slot(p->ainsn.insn, 0);
149 p->ainsn.insn = NULL;
153 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
155 kcb->prev_kprobe.kp = kprobe_running();
156 kcb->prev_kprobe.status = kcb->kprobe_status;
157 kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
160 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
162 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
163 kcb->kprobe_status = kcb->prev_kprobe.status;
164 kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
167 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
168 struct kprobe_ctlblk *kcb)
170 __this_cpu_write(current_kprobe, p);
171 kcb->kprobe_saved_pc = regs->pc;
174 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
176 /* Single step inline if the instruction is a break. */
177 if (p->opcode == breakpoint_insn ||
178 p->opcode == breakpoint2_insn)
179 regs->pc = (unsigned long)p->addr;
181 regs->pc = (unsigned long)&p->ainsn.insn[0];
184 static int __kprobes kprobe_handler(struct pt_regs *regs)
188 kprobe_opcode_t *addr;
189 struct kprobe_ctlblk *kcb;
191 addr = (kprobe_opcode_t *)regs->pc;
194 * We don't want to be preempted for the entire
195 * duration of kprobe processing.
198 kcb = get_kprobe_ctlblk();
200 /* Check we're not actually recursing. */
201 if (kprobe_running()) {
202 p = get_kprobe(addr);
204 if (kcb->kprobe_status == KPROBE_HIT_SS &&
205 p->ainsn.insn[0] == breakpoint_insn) {
209 * We have reentered the kprobe_handler(), since
210 * another probe was hit while within the handler.
211 * We here save the original kprobes variables and
212 * just single step on the instruction of the new probe
213 * without calling any user handlers.
215 save_previous_kprobe(kcb);
216 set_current_kprobe(p, regs, kcb);
217 kprobes_inc_nmissed_count(p);
218 prepare_singlestep(p, regs);
219 kcb->kprobe_status = KPROBE_REENTER;
222 if (*addr != breakpoint_insn) {
224 * The breakpoint instruction was removed by
225 * another cpu right after we hit, no further
226 * handling of this interrupt is appropriate.
231 p = __this_cpu_read(current_kprobe);
232 if (p->break_handler && p->break_handler(p, regs))
238 p = get_kprobe(addr);
240 if (*addr != breakpoint_insn) {
242 * The breakpoint instruction was removed right
243 * after we hit it. Another cpu has removed
244 * either a probepoint or a debugger breakpoint
245 * at this address. In either case, no further
246 * handling of this interrupt is appropriate.
250 /* Not one of ours: let kernel handle it. */
254 set_current_kprobe(p, regs, kcb);
255 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
257 if (p->pre_handler && p->pre_handler(p, regs)) {
258 /* Handler has already set things up, so skip ss setup. */
263 prepare_singlestep(p, regs);
264 kcb->kprobe_status = KPROBE_HIT_SS;
268 preempt_enable_no_resched();
273 * Called after single-stepping. p->addr is the address of the
274 * instruction that has been replaced by the breakpoint. To avoid the
275 * SMP problems that can occur when we temporarily put back the
276 * original opcode to single-step, we single-stepped a copy of the
277 * instruction. The address of this copy is p->ainsn.insn.
279 * This function prepares to return from the post-single-step
282 static void __kprobes resume_execution(struct kprobe *p,
283 struct pt_regs *regs,
284 struct kprobe_ctlblk *kcb)
286 unsigned long orig_pc = kcb->kprobe_saved_pc;
287 regs->pc = orig_pc + 8;
290 static inline int post_kprobe_handler(struct pt_regs *regs)
292 struct kprobe *cur = kprobe_running();
293 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
298 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
299 kcb->kprobe_status = KPROBE_HIT_SSDONE;
300 cur->post_handler(cur, regs, 0);
303 resume_execution(cur, regs, kcb);
305 /* Restore back the original saved kprobes variables and continue. */
306 if (kcb->kprobe_status == KPROBE_REENTER) {
307 restore_previous_kprobe(kcb);
310 reset_current_kprobe();
312 preempt_enable_no_resched();
317 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
319 struct kprobe *cur = kprobe_running();
320 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
322 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
325 if (kcb->kprobe_status & KPROBE_HIT_SS) {
327 * We are here because the instruction being single
328 * stepped caused a page fault. We reset the current
329 * kprobe and the ip points back to the probe address
330 * and allow the page fault handler to continue as a
333 resume_execution(cur, regs, kcb);
334 reset_current_kprobe();
335 preempt_enable_no_resched();
341 * Wrapper routine for handling exceptions.
343 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
344 unsigned long val, void *data)
346 struct die_args *args = (struct die_args *)data;
347 int ret = NOTIFY_DONE;
351 if (kprobe_handler(args->regs))
355 if (post_kprobe_handler(args->regs))
359 /* kprobe_running() needs smp_processor_id(). */
363 && kprobe_fault_handler(args->regs, args->trapnr))
373 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
375 struct jprobe *jp = container_of(p, struct jprobe, kp);
376 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
378 kcb->jprobe_saved_regs = *regs;
379 kcb->jprobe_saved_sp = regs->sp;
381 memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
382 MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
384 regs->pc = (unsigned long)(jp->entry);
389 /* Defined in the inline asm below. */
390 void jprobe_return_end(void);
392 void __kprobes jprobe_return(void)
396 ".globl jprobe_return_end\n"
397 "jprobe_return_end:\n");
400 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
402 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
404 if (regs->pc >= (unsigned long)jprobe_return &&
405 regs->pc <= (unsigned long)jprobe_return_end) {
406 *regs = kcb->jprobe_saved_regs;
407 memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
408 MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
409 preempt_enable_no_resched();
417 * Function return probe trampoline:
418 * - init_kprobes() establishes a probepoint here
419 * - When the probed function returns, this probe causes the
422 static void __used kretprobe_trampoline_holder(void)
426 ".global kretprobe_trampoline\n"
427 "kretprobe_trampoline:\n\t"
432 void kretprobe_trampoline(void);
434 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
435 struct pt_regs *regs)
437 ri->ret_addr = (kprobe_opcode_t *) regs->lr;
439 /* Replace the return addr with trampoline addr */
440 regs->lr = (unsigned long)kretprobe_trampoline;
444 * Called when the probe at kretprobe trampoline is hit.
446 static int __kprobes trampoline_probe_handler(struct kprobe *p,
447 struct pt_regs *regs)
449 struct kretprobe_instance *ri = NULL;
450 struct hlist_head *head, empty_rp;
451 struct hlist_node *tmp;
452 unsigned long flags, orig_ret_address = 0;
453 unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;
455 INIT_HLIST_HEAD(&empty_rp);
456 kretprobe_hash_lock(current, &head, &flags);
459 * It is possible to have multiple instances associated with a given
460 * task either because multiple functions in the call path have
461 * a return probe installed on them, and/or more than one return
462 * return probe was registered for a target function.
464 * We can handle this because:
465 * - instances are always inserted at the head of the list
466 * - when multiple return probes are registered for the same
467 * function, the first instance's ret_addr will point to the
468 * real return address, and all the rest will point to
469 * kretprobe_trampoline
471 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
472 if (ri->task != current)
473 /* another task is sharing our hash bucket */
476 if (ri->rp && ri->rp->handler)
477 ri->rp->handler(ri, regs);
479 orig_ret_address = (unsigned long)ri->ret_addr;
480 recycle_rp_inst(ri, &empty_rp);
482 if (orig_ret_address != trampoline_address) {
484 * This is the real return address. Any other
485 * instances associated with this task are for
486 * other calls deeper on the call stack
492 kretprobe_assert(ri, orig_ret_address, trampoline_address);
493 instruction_pointer(regs) = orig_ret_address;
495 reset_current_kprobe();
496 kretprobe_hash_unlock(current, &flags);
497 preempt_enable_no_resched();
499 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
500 hlist_del(&ri->hlist);
504 * By returning a non-zero value, we are telling
505 * kprobe_handler() that we don't want the post_handler
506 * to run (and have re-enabled preemption)
511 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
513 if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
519 static struct kprobe trampoline_p = {
520 .addr = (kprobe_opcode_t *)kretprobe_trampoline,
521 .pre_handler = trampoline_probe_handler
524 int __init arch_init_kprobes(void)
526 register_kprobe(&trampoline_p);