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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kernel probes (kprobes) for SuperH
4 *
5 * Copyright (C) 2007 Chris Smith <chris.smith@st.com>
6 * Copyright (C) 2006 Lineo Solutions, Inc.
7 */
8#include <linux/kprobes.h>
9#include <linux/extable.h>
10#include <linux/ptrace.h>
11#include <linux/preempt.h>
12#include <linux/kdebug.h>
13#include <linux/slab.h>
14#include <asm/cacheflush.h>
15#include <linux/uaccess.h>
16
17DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
18DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
19
20static DEFINE_PER_CPU(struct kprobe, saved_current_opcode);
21static DEFINE_PER_CPU(struct kprobe, saved_next_opcode);
22static DEFINE_PER_CPU(struct kprobe, saved_next_opcode2);
23
24#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
25#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
26#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
27#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
28#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
29#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
30
31#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
32#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
33
34#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
35#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
36
37#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
38#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
39
40int __kprobes arch_prepare_kprobe(struct kprobe *p)
41{
42 kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
43
44 if (OPCODE_RTE(opcode))
45 return -EFAULT; /* Bad breakpoint */
46
47 p->opcode = opcode;
48
49 return 0;
50}
51
52void __kprobes arch_copy_kprobe(struct kprobe *p)
53{
54 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
55 p->opcode = *p->addr;
56}
57
58void __kprobes arch_arm_kprobe(struct kprobe *p)
59{
60 *p->addr = BREAKPOINT_INSTRUCTION;
61 flush_icache_range((unsigned long)p->addr,
62 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
63}
64
65void __kprobes arch_disarm_kprobe(struct kprobe *p)
66{
67 *p->addr = p->opcode;
68 flush_icache_range((unsigned long)p->addr,
69 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
70}
71
72int __kprobes arch_trampoline_kprobe(struct kprobe *p)
73{
74 if (*p->addr == BREAKPOINT_INSTRUCTION)
75 return 1;
76
77 return 0;
78}
79
80/**
81 * If an illegal slot instruction exception occurs for an address
82 * containing a kprobe, remove the probe.
83 *
84 * Returns 0 if the exception was handled successfully, 1 otherwise.
85 */
86int __kprobes kprobe_handle_illslot(unsigned long pc)
87{
88 struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
89
90 if (p != NULL) {
91 printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
92 (unsigned int)pc + 2);
93 unregister_kprobe(p);
94 return 0;
95 }
96
97 return 1;
98}
99
100void __kprobes arch_remove_kprobe(struct kprobe *p)
101{
102 struct kprobe *saved = this_cpu_ptr(&saved_next_opcode);
103
104 if (saved->addr) {
105 arch_disarm_kprobe(p);
106 arch_disarm_kprobe(saved);
107
108 saved->addr = NULL;
109 saved->opcode = 0;
110
111 saved = this_cpu_ptr(&saved_next_opcode2);
112 if (saved->addr) {
113 arch_disarm_kprobe(saved);
114
115 saved->addr = NULL;
116 saved->opcode = 0;
117 }
118 }
119}
120
121static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
122{
123 kcb->prev_kprobe.kp = kprobe_running();
124 kcb->prev_kprobe.status = kcb->kprobe_status;
125}
126
127static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
128{
129 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
130 kcb->kprobe_status = kcb->prev_kprobe.status;
131}
132
133static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
134 struct kprobe_ctlblk *kcb)
135{
136 __this_cpu_write(current_kprobe, p);
137}
138
139/*
140 * Singlestep is implemented by disabling the current kprobe and setting one
141 * on the next instruction, following branches. Two probes are set if the
142 * branch is conditional.
143 */
144static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
145{
146 __this_cpu_write(saved_current_opcode.addr, (kprobe_opcode_t *)regs->pc);
147
148 if (p != NULL) {
149 struct kprobe *op1, *op2;
150
151 arch_disarm_kprobe(p);
152
153 op1 = this_cpu_ptr(&saved_next_opcode);
154 op2 = this_cpu_ptr(&saved_next_opcode2);
155
156 if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
157 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
158 op1->addr = (kprobe_opcode_t *) regs->regs[reg_nr];
159 } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
160 unsigned long disp = (p->opcode & 0x0FFF);
161 op1->addr =
162 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
163
164 } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
165 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
166 op1->addr =
167 (kprobe_opcode_t *) (regs->pc + 4 +
168 regs->regs[reg_nr]);
169
170 } else if (OPCODE_RTS(p->opcode)) {
171 op1->addr = (kprobe_opcode_t *) regs->pr;
172
173 } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
174 unsigned long disp = (p->opcode & 0x00FF);
175 /* case 1 */
176 op1->addr = p->addr + 1;
177 /* case 2 */
178 op2->addr =
179 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
180 op2->opcode = *(op2->addr);
181 arch_arm_kprobe(op2);
182
183 } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
184 unsigned long disp = (p->opcode & 0x00FF);
185 /* case 1 */
186 op1->addr = p->addr + 2;
187 /* case 2 */
188 op2->addr =
189 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
190 op2->opcode = *(op2->addr);
191 arch_arm_kprobe(op2);
192
193 } else {
194 op1->addr = p->addr + 1;
195 }
196
197 op1->opcode = *(op1->addr);
198 arch_arm_kprobe(op1);
199 }
200}
201
202/* Called with kretprobe_lock held */
203void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
204 struct pt_regs *regs)
205{
206 ri->ret_addr = (kprobe_opcode_t *) regs->pr;
207
208 /* Replace the return addr with trampoline addr */
209 regs->pr = (unsigned long)kretprobe_trampoline;
210}
211
212static int __kprobes kprobe_handler(struct pt_regs *regs)
213{
214 struct kprobe *p;
215 int ret = 0;
216 kprobe_opcode_t *addr = NULL;
217 struct kprobe_ctlblk *kcb;
218
219 /*
220 * We don't want to be preempted for the entire
221 * duration of kprobe processing
222 */
223 preempt_disable();
224 kcb = get_kprobe_ctlblk();
225
226 addr = (kprobe_opcode_t *) (regs->pc);
227
228 /* Check we're not actually recursing */
229 if (kprobe_running()) {
230 p = get_kprobe(addr);
231 if (p) {
232 if (kcb->kprobe_status == KPROBE_HIT_SS &&
233 *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
234 goto no_kprobe;
235 }
236 /* We have reentered the kprobe_handler(), since
237 * another probe was hit while within the handler.
238 * We here save the original kprobes variables and
239 * just single step on the instruction of the new probe
240 * without calling any user handlers.
241 */
242 save_previous_kprobe(kcb);
243 set_current_kprobe(p, regs, kcb);
244 kprobes_inc_nmissed_count(p);
245 prepare_singlestep(p, regs);
246 kcb->kprobe_status = KPROBE_REENTER;
247 return 1;
248 }
249 goto no_kprobe;
250 }
251
252 p = get_kprobe(addr);
253 if (!p) {
254 /* Not one of ours: let kernel handle it */
255 if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) {
256 /*
257 * The breakpoint instruction was removed right
258 * after we hit it. Another cpu has removed
259 * either a probepoint or a debugger breakpoint
260 * at this address. In either case, no further
261 * handling of this interrupt is appropriate.
262 */
263 ret = 1;
264 }
265
266 goto no_kprobe;
267 }
268
269 set_current_kprobe(p, regs, kcb);
270 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
271
272 if (p->pre_handler && p->pre_handler(p, regs)) {
273 /* handler has already set things up, so skip ss setup */
274 reset_current_kprobe();
275 preempt_enable_no_resched();
276 return 1;
277 }
278
279 prepare_singlestep(p, regs);
280 kcb->kprobe_status = KPROBE_HIT_SS;
281 return 1;
282
283no_kprobe:
284 preempt_enable_no_resched();
285 return ret;
286}
287
288/*
289 * For function-return probes, init_kprobes() establishes a probepoint
290 * here. When a retprobed function returns, this probe is hit and
291 * trampoline_probe_handler() runs, calling the kretprobe's handler.
292 */
293static void __used kretprobe_trampoline_holder(void)
294{
295 asm volatile (".globl kretprobe_trampoline\n"
296 "kretprobe_trampoline:\n\t"
297 "nop\n");
298}
299
300/*
301 * Called when we hit the probe point at kretprobe_trampoline
302 */
303int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
304{
305 struct kretprobe_instance *ri = NULL;
306 struct hlist_head *head, empty_rp;
307 struct hlist_node *tmp;
308 unsigned long flags, orig_ret_address = 0;
309 unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
310
311 INIT_HLIST_HEAD(&empty_rp);
312 kretprobe_hash_lock(current, &head, &flags);
313
314 /*
315 * It is possible to have multiple instances associated with a given
316 * task either because an multiple functions in the call path
317 * have a return probe installed on them, and/or more then one return
318 * return probe was registered for a target function.
319 *
320 * We can handle this because:
321 * - instances are always inserted at the head of the list
322 * - when multiple return probes are registered for the same
323 * function, the first instance's ret_addr will point to the
324 * real return address, and all the rest will point to
325 * kretprobe_trampoline
326 */
327 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
328 if (ri->task != current)
329 /* another task is sharing our hash bucket */
330 continue;
331
332 if (ri->rp && ri->rp->handler) {
333 __this_cpu_write(current_kprobe, &ri->rp->kp);
334 ri->rp->handler(ri, regs);
335 __this_cpu_write(current_kprobe, NULL);
336 }
337
338 orig_ret_address = (unsigned long)ri->ret_addr;
339 recycle_rp_inst(ri, &empty_rp);
340
341 if (orig_ret_address != trampoline_address)
342 /*
343 * This is the real return address. Any other
344 * instances associated with this task are for
345 * other calls deeper on the call stack
346 */
347 break;
348 }
349
350 kretprobe_assert(ri, orig_ret_address, trampoline_address);
351
352 regs->pc = orig_ret_address;
353 kretprobe_hash_unlock(current, &flags);
354
355 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
356 hlist_del(&ri->hlist);
357 kfree(ri);
358 }
359
360 return orig_ret_address;
361}
362
363static int __kprobes post_kprobe_handler(struct pt_regs *regs)
364{
365 struct kprobe *cur = kprobe_running();
366 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
367 kprobe_opcode_t *addr = NULL;
368 struct kprobe *p = NULL;
369
370 if (!cur)
371 return 0;
372
373 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
374 kcb->kprobe_status = KPROBE_HIT_SSDONE;
375 cur->post_handler(cur, regs, 0);
376 }
377
378 p = this_cpu_ptr(&saved_next_opcode);
379 if (p->addr) {
380 arch_disarm_kprobe(p);
381 p->addr = NULL;
382 p->opcode = 0;
383
384 addr = __this_cpu_read(saved_current_opcode.addr);
385 __this_cpu_write(saved_current_opcode.addr, NULL);
386
387 p = get_kprobe(addr);
388 arch_arm_kprobe(p);
389
390 p = this_cpu_ptr(&saved_next_opcode2);
391 if (p->addr) {
392 arch_disarm_kprobe(p);
393 p->addr = NULL;
394 p->opcode = 0;
395 }
396 }
397
398 /* Restore back the original saved kprobes variables and continue. */
399 if (kcb->kprobe_status == KPROBE_REENTER) {
400 restore_previous_kprobe(kcb);
401 goto out;
402 }
403
404 reset_current_kprobe();
405
406out:
407 preempt_enable_no_resched();
408
409 return 1;
410}
411
412int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
413{
414 struct kprobe *cur = kprobe_running();
415 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
416 const struct exception_table_entry *entry;
417
418 switch (kcb->kprobe_status) {
419 case KPROBE_HIT_SS:
420 case KPROBE_REENTER:
421 /*
422 * We are here because the instruction being single
423 * stepped caused a page fault. We reset the current
424 * kprobe, point the pc back to the probe address
425 * and allow the page fault handler to continue as a
426 * normal page fault.
427 */
428 regs->pc = (unsigned long)cur->addr;
429 if (kcb->kprobe_status == KPROBE_REENTER)
430 restore_previous_kprobe(kcb);
431 else
432 reset_current_kprobe();
433 preempt_enable_no_resched();
434 break;
435 case KPROBE_HIT_ACTIVE:
436 case KPROBE_HIT_SSDONE:
437 /*
438 * We increment the nmissed count for accounting,
439 * we can also use npre/npostfault count for accounting
440 * these specific fault cases.
441 */
442 kprobes_inc_nmissed_count(cur);
443
444 /*
445 * We come here because instructions in the pre/post
446 * handler caused the page_fault, this could happen
447 * if handler tries to access user space by
448 * copy_from_user(), get_user() etc. Let the
449 * user-specified handler try to fix it first.
450 */
451 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
452 return 1;
453
454 /*
455 * In case the user-specified fault handler returned
456 * zero, try to fix up.
457 */
458 if ((entry = search_exception_tables(regs->pc)) != NULL) {
459 regs->pc = entry->fixup;
460 return 1;
461 }
462
463 /*
464 * fixup_exception() could not handle it,
465 * Let do_page_fault() fix it.
466 */
467 break;
468 default:
469 break;
470 }
471
472 return 0;
473}
474
475/*
476 * Wrapper routine to for handling exceptions.
477 */
478int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
479 unsigned long val, void *data)
480{
481 struct kprobe *p = NULL;
482 struct die_args *args = (struct die_args *)data;
483 int ret = NOTIFY_DONE;
484 kprobe_opcode_t *addr = NULL;
485 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
486
487 addr = (kprobe_opcode_t *) (args->regs->pc);
488 if (val == DIE_TRAP &&
489 args->trapnr == (BREAKPOINT_INSTRUCTION & 0xff)) {
490 if (!kprobe_running()) {
491 if (kprobe_handler(args->regs)) {
492 ret = NOTIFY_STOP;
493 } else {
494 /* Not a kprobe trap */
495 ret = NOTIFY_DONE;
496 }
497 } else {
498 p = get_kprobe(addr);
499 if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
500 (kcb->kprobe_status == KPROBE_REENTER)) {
501 if (post_kprobe_handler(args->regs))
502 ret = NOTIFY_STOP;
503 } else {
504 if (kprobe_handler(args->regs))
505 ret = NOTIFY_STOP;
506 }
507 }
508 }
509
510 return ret;
511}
512
513static struct kprobe trampoline_p = {
514 .addr = (kprobe_opcode_t *)&kretprobe_trampoline,
515 .pre_handler = trampoline_probe_handler
516};
517
518int __init arch_init_kprobes(void)
519{
520 return register_kprobe(&trampoline_p);
521}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kernel probes (kprobes) for SuperH
4 *
5 * Copyright (C) 2007 Chris Smith <chris.smith@st.com>
6 * Copyright (C) 2006 Lineo Solutions, Inc.
7 */
8#include <linux/kprobes.h>
9#include <linux/extable.h>
10#include <linux/ptrace.h>
11#include <linux/preempt.h>
12#include <linux/kdebug.h>
13#include <linux/slab.h>
14#include <asm/cacheflush.h>
15#include <linux/uaccess.h>
16
17DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
18DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
19
20static DEFINE_PER_CPU(struct kprobe, saved_current_opcode);
21static DEFINE_PER_CPU(struct kprobe, saved_next_opcode);
22static DEFINE_PER_CPU(struct kprobe, saved_next_opcode2);
23
24#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
25#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
26#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
27#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
28#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
29#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
30
31#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
32#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
33
34#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
35#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
36
37#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
38#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
39
40int __kprobes arch_prepare_kprobe(struct kprobe *p)
41{
42 kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
43
44 if (OPCODE_RTE(opcode))
45 return -EFAULT; /* Bad breakpoint */
46
47 p->opcode = opcode;
48
49 return 0;
50}
51
52void __kprobes arch_copy_kprobe(struct kprobe *p)
53{
54 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
55 p->opcode = *p->addr;
56}
57
58void __kprobes arch_arm_kprobe(struct kprobe *p)
59{
60 *p->addr = BREAKPOINT_INSTRUCTION;
61 flush_icache_range((unsigned long)p->addr,
62 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
63}
64
65void __kprobes arch_disarm_kprobe(struct kprobe *p)
66{
67 *p->addr = p->opcode;
68 flush_icache_range((unsigned long)p->addr,
69 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
70}
71
72int __kprobes arch_trampoline_kprobe(struct kprobe *p)
73{
74 if (*p->addr == BREAKPOINT_INSTRUCTION)
75 return 1;
76
77 return 0;
78}
79
80/**
81 * If an illegal slot instruction exception occurs for an address
82 * containing a kprobe, remove the probe.
83 *
84 * Returns 0 if the exception was handled successfully, 1 otherwise.
85 */
86int __kprobes kprobe_handle_illslot(unsigned long pc)
87{
88 struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
89
90 if (p != NULL) {
91 printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
92 (unsigned int)pc + 2);
93 unregister_kprobe(p);
94 return 0;
95 }
96
97 return 1;
98}
99
100void __kprobes arch_remove_kprobe(struct kprobe *p)
101{
102 struct kprobe *saved = this_cpu_ptr(&saved_next_opcode);
103
104 if (saved->addr) {
105 arch_disarm_kprobe(p);
106 arch_disarm_kprobe(saved);
107
108 saved->addr = NULL;
109 saved->opcode = 0;
110
111 saved = this_cpu_ptr(&saved_next_opcode2);
112 if (saved->addr) {
113 arch_disarm_kprobe(saved);
114
115 saved->addr = NULL;
116 saved->opcode = 0;
117 }
118 }
119}
120
121static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
122{
123 kcb->prev_kprobe.kp = kprobe_running();
124 kcb->prev_kprobe.status = kcb->kprobe_status;
125}
126
127static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
128{
129 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
130 kcb->kprobe_status = kcb->prev_kprobe.status;
131}
132
133static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
134 struct kprobe_ctlblk *kcb)
135{
136 __this_cpu_write(current_kprobe, p);
137}
138
139/*
140 * Singlestep is implemented by disabling the current kprobe and setting one
141 * on the next instruction, following branches. Two probes are set if the
142 * branch is conditional.
143 */
144static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
145{
146 __this_cpu_write(saved_current_opcode.addr, (kprobe_opcode_t *)regs->pc);
147
148 if (p != NULL) {
149 struct kprobe *op1, *op2;
150
151 arch_disarm_kprobe(p);
152
153 op1 = this_cpu_ptr(&saved_next_opcode);
154 op2 = this_cpu_ptr(&saved_next_opcode2);
155
156 if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
157 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
158 op1->addr = (kprobe_opcode_t *) regs->regs[reg_nr];
159 } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
160 unsigned long disp = (p->opcode & 0x0FFF);
161 op1->addr =
162 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
163
164 } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
165 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
166 op1->addr =
167 (kprobe_opcode_t *) (regs->pc + 4 +
168 regs->regs[reg_nr]);
169
170 } else if (OPCODE_RTS(p->opcode)) {
171 op1->addr = (kprobe_opcode_t *) regs->pr;
172
173 } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
174 unsigned long disp = (p->opcode & 0x00FF);
175 /* case 1 */
176 op1->addr = p->addr + 1;
177 /* case 2 */
178 op2->addr =
179 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
180 op2->opcode = *(op2->addr);
181 arch_arm_kprobe(op2);
182
183 } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
184 unsigned long disp = (p->opcode & 0x00FF);
185 /* case 1 */
186 op1->addr = p->addr + 2;
187 /* case 2 */
188 op2->addr =
189 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
190 op2->opcode = *(op2->addr);
191 arch_arm_kprobe(op2);
192
193 } else {
194 op1->addr = p->addr + 1;
195 }
196
197 op1->opcode = *(op1->addr);
198 arch_arm_kprobe(op1);
199 }
200}
201
202/* Called with kretprobe_lock held */
203void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
204 struct pt_regs *regs)
205{
206 ri->ret_addr = (kprobe_opcode_t *) regs->pr;
207 ri->fp = NULL;
208
209 /* Replace the return addr with trampoline addr */
210 regs->pr = (unsigned long)__kretprobe_trampoline;
211}
212
213static int __kprobes kprobe_handler(struct pt_regs *regs)
214{
215 struct kprobe *p;
216 int ret = 0;
217 kprobe_opcode_t *addr = NULL;
218 struct kprobe_ctlblk *kcb;
219
220 /*
221 * We don't want to be preempted for the entire
222 * duration of kprobe processing
223 */
224 preempt_disable();
225 kcb = get_kprobe_ctlblk();
226
227 addr = (kprobe_opcode_t *) (regs->pc);
228
229 /* Check we're not actually recursing */
230 if (kprobe_running()) {
231 p = get_kprobe(addr);
232 if (p) {
233 if (kcb->kprobe_status == KPROBE_HIT_SS &&
234 *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
235 goto no_kprobe;
236 }
237 /* We have reentered the kprobe_handler(), since
238 * another probe was hit while within the handler.
239 * We here save the original kprobes variables and
240 * just single step on the instruction of the new probe
241 * without calling any user handlers.
242 */
243 save_previous_kprobe(kcb);
244 set_current_kprobe(p, regs, kcb);
245 kprobes_inc_nmissed_count(p);
246 prepare_singlestep(p, regs);
247 kcb->kprobe_status = KPROBE_REENTER;
248 return 1;
249 }
250 goto no_kprobe;
251 }
252
253 p = get_kprobe(addr);
254 if (!p) {
255 /* Not one of ours: let kernel handle it */
256 if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) {
257 /*
258 * The breakpoint instruction was removed right
259 * after we hit it. Another cpu has removed
260 * either a probepoint or a debugger breakpoint
261 * at this address. In either case, no further
262 * handling of this interrupt is appropriate.
263 */
264 ret = 1;
265 }
266
267 goto no_kprobe;
268 }
269
270 set_current_kprobe(p, regs, kcb);
271 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
272
273 if (p->pre_handler && p->pre_handler(p, regs)) {
274 /* handler has already set things up, so skip ss setup */
275 reset_current_kprobe();
276 preempt_enable_no_resched();
277 return 1;
278 }
279
280 prepare_singlestep(p, regs);
281 kcb->kprobe_status = KPROBE_HIT_SS;
282 return 1;
283
284no_kprobe:
285 preempt_enable_no_resched();
286 return ret;
287}
288
289/*
290 * For function-return probes, init_kprobes() establishes a probepoint
291 * here. When a retprobed function returns, this probe is hit and
292 * trampoline_probe_handler() runs, calling the kretprobe's handler.
293 */
294static void __used kretprobe_trampoline_holder(void)
295{
296 asm volatile (".globl __kretprobe_trampoline\n"
297 "__kretprobe_trampoline:\n\t"
298 "nop\n");
299}
300
301/*
302 * Called when we hit the probe point at __kretprobe_trampoline
303 */
304int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
305{
306 regs->pc = __kretprobe_trampoline_handler(regs, NULL);
307
308 return 1;
309}
310
311static int __kprobes post_kprobe_handler(struct pt_regs *regs)
312{
313 struct kprobe *cur = kprobe_running();
314 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
315 kprobe_opcode_t *addr = NULL;
316 struct kprobe *p = NULL;
317
318 if (!cur)
319 return 0;
320
321 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
322 kcb->kprobe_status = KPROBE_HIT_SSDONE;
323 cur->post_handler(cur, regs, 0);
324 }
325
326 p = this_cpu_ptr(&saved_next_opcode);
327 if (p->addr) {
328 arch_disarm_kprobe(p);
329 p->addr = NULL;
330 p->opcode = 0;
331
332 addr = __this_cpu_read(saved_current_opcode.addr);
333 __this_cpu_write(saved_current_opcode.addr, NULL);
334
335 p = get_kprobe(addr);
336 arch_arm_kprobe(p);
337
338 p = this_cpu_ptr(&saved_next_opcode2);
339 if (p->addr) {
340 arch_disarm_kprobe(p);
341 p->addr = NULL;
342 p->opcode = 0;
343 }
344 }
345
346 /* Restore back the original saved kprobes variables and continue. */
347 if (kcb->kprobe_status == KPROBE_REENTER) {
348 restore_previous_kprobe(kcb);
349 goto out;
350 }
351
352 reset_current_kprobe();
353
354out:
355 preempt_enable_no_resched();
356
357 return 1;
358}
359
360int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
361{
362 struct kprobe *cur = kprobe_running();
363 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
364 const struct exception_table_entry *entry;
365
366 switch (kcb->kprobe_status) {
367 case KPROBE_HIT_SS:
368 case KPROBE_REENTER:
369 /*
370 * We are here because the instruction being single
371 * stepped caused a page fault. We reset the current
372 * kprobe, point the pc back to the probe address
373 * and allow the page fault handler to continue as a
374 * normal page fault.
375 */
376 regs->pc = (unsigned long)cur->addr;
377 if (kcb->kprobe_status == KPROBE_REENTER)
378 restore_previous_kprobe(kcb);
379 else
380 reset_current_kprobe();
381 preempt_enable_no_resched();
382 break;
383 case KPROBE_HIT_ACTIVE:
384 case KPROBE_HIT_SSDONE:
385 /*
386 * In case the user-specified fault handler returned
387 * zero, try to fix up.
388 */
389 if ((entry = search_exception_tables(regs->pc)) != NULL) {
390 regs->pc = entry->fixup;
391 return 1;
392 }
393
394 /*
395 * fixup_exception() could not handle it,
396 * Let do_page_fault() fix it.
397 */
398 break;
399 default:
400 break;
401 }
402
403 return 0;
404}
405
406/*
407 * Wrapper routine to for handling exceptions.
408 */
409int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
410 unsigned long val, void *data)
411{
412 struct kprobe *p = NULL;
413 struct die_args *args = (struct die_args *)data;
414 int ret = NOTIFY_DONE;
415 kprobe_opcode_t *addr = NULL;
416 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
417
418 addr = (kprobe_opcode_t *) (args->regs->pc);
419 if (val == DIE_TRAP &&
420 args->trapnr == (BREAKPOINT_INSTRUCTION & 0xff)) {
421 if (!kprobe_running()) {
422 if (kprobe_handler(args->regs)) {
423 ret = NOTIFY_STOP;
424 } else {
425 /* Not a kprobe trap */
426 ret = NOTIFY_DONE;
427 }
428 } else {
429 p = get_kprobe(addr);
430 if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
431 (kcb->kprobe_status == KPROBE_REENTER)) {
432 if (post_kprobe_handler(args->regs))
433 ret = NOTIFY_STOP;
434 } else {
435 if (kprobe_handler(args->regs))
436 ret = NOTIFY_STOP;
437 }
438 }
439 }
440
441 return ret;
442}
443
444static struct kprobe trampoline_p = {
445 .addr = (kprobe_opcode_t *)&__kretprobe_trampoline,
446 .pre_handler = trampoline_probe_handler
447};
448
449int __init arch_init_kprobes(void)
450{
451 return register_kprobe(&trampoline_p);
452}