aboutsummaryrefslogtreecommitdiffstats
path: root/arch/ia64/kernel/kprobes.c
blob: 5978823d5c63ce3fbc891c2108ddd6c98579e739 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
/*
 *  Kernel Probes (KProbes)
 *  arch/ia64/kernel/kprobes.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2002, 2004
 * Copyright (C) Intel Corporation, 2005
 *
 * 2005-Apr     Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
 *              <anil.s.keshavamurthy@intel.com> adapted from i386
 */

#include <linux/config.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/preempt.h>
#include <linux/moduleloader.h>

#include <asm/pgtable.h>
#include <asm/kdebug.h>

extern void jprobe_inst_return(void);

/* kprobe_status settings */
#define KPROBE_HIT_ACTIVE	0x00000001
#define KPROBE_HIT_SS		0x00000002

static struct kprobe *current_kprobe, *kprobe_prev;
static unsigned long kprobe_status, kprobe_status_prev;
static struct pt_regs jprobe_saved_regs;

enum instruction_type {A, I, M, F, B, L, X, u};
static enum instruction_type bundle_encoding[32][3] = {
  { M, I, I },				/* 00 */
  { M, I, I },				/* 01 */
  { M, I, I },				/* 02 */
  { M, I, I },				/* 03 */
  { M, L, X },				/* 04 */
  { M, L, X },				/* 05 */
  { u, u, u },  			/* 06 */
  { u, u, u },  			/* 07 */
  { M, M, I },				/* 08 */
  { M, M, I },				/* 09 */
  { M, M, I },				/* 0A */
  { M, M, I },				/* 0B */
  { M, F, I },				/* 0C */
  { M, F, I },				/* 0D */
  { M, M, F },				/* 0E */
  { M, M, F },				/* 0F */
  { M, I, B },				/* 10 */
  { M, I, B },				/* 11 */
  { M, B, B },				/* 12 */
  { M, B, B },				/* 13 */
  { u, u, u },  			/* 14 */
  { u, u, u },  			/* 15 */
  { B, B, B },				/* 16 */
  { B, B, B },				/* 17 */
  { M, M, B },				/* 18 */
  { M, M, B },				/* 19 */
  { u, u, u },  			/* 1A */
  { u, u, u },  			/* 1B */
  { M, F, B },				/* 1C */
  { M, F, B },				/* 1D */
  { u, u, u },  			/* 1E */
  { u, u, u },  			/* 1F */
};

/*
 * In this function we check to see if the instruction
 * is IP relative instruction and update the kprobe
 * inst flag accordingly
 */
static void update_kprobe_inst_flag(uint template, uint  slot, uint major_opcode,
	unsigned long kprobe_inst, struct kprobe *p)
{
	p->ainsn.inst_flag = 0;
	p->ainsn.target_br_reg = 0;

	if (bundle_encoding[template][slot] == B) {
		switch (major_opcode) {
		  case INDIRECT_CALL_OPCODE:
	 		p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 			break;
		  case IP_RELATIVE_PREDICT_OPCODE:
		  case IP_RELATIVE_BRANCH_OPCODE:
			p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 			break;
		  case IP_RELATIVE_CALL_OPCODE:
 			p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 			p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 			break;
		}
 	} else if (bundle_encoding[template][slot] == X) {
		switch (major_opcode) {
		  case LONG_CALL_OPCODE:
			p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
		  break;
		}
	}
	return;
}

/*
 * In this function we check to see if the instruction
 * on which we are inserting kprobe is supported.
 * Returns 0 if supported
 * Returns -EINVAL if unsupported
 */
static int unsupported_inst(uint template, uint  slot, uint major_opcode,
	unsigned long kprobe_inst, struct kprobe *p)
{
	unsigned long addr = (unsigned long)p->addr;

	if (bundle_encoding[template][slot] == I) {
		switch (major_opcode) {
			case 0x0: //I_UNIT_MISC_OPCODE:
			/*
			 * Check for Integer speculation instruction
			 * - Bit 33-35 to be equal to 0x1
			 */
			if (((kprobe_inst >> 33) & 0x7) == 1) {
				printk(KERN_WARNING
					"Kprobes on speculation inst at <0x%lx> not supported\n",
					addr);
				return -EINVAL;
			}

			/*
			 * IP relative mov instruction
			 *  - Bit 27-35 to be equal to 0x30
			 */
			if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
				printk(KERN_WARNING
					"Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
					addr);
				return -EINVAL;

			}
		}
	}
	return 0;
}


/*
 * In this function we check to see if the instruction
 * (qp) cmpx.crel.ctype p1,p2=r2,r3
 * on which we are inserting kprobe is cmp instruction
 * with ctype as unc.
 */
static uint is_cmp_ctype_unc_inst(uint template, uint slot, uint major_opcode,
unsigned long kprobe_inst)
{
	cmp_inst_t cmp_inst;
	uint ctype_unc = 0;

	if (!((bundle_encoding[template][slot] == I) ||
		(bundle_encoding[template][slot] == M)))
		goto out;

	if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
		(major_opcode == 0xE)))
		goto out;

	cmp_inst.l = kprobe_inst;
	if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
		/* Integere compare - Register Register (A6 type)*/
		if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
				&&(cmp_inst.f.c == 1))
			ctype_unc = 1;
	} else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
		/* Integere compare - Immediate Register (A8 type)*/
		if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
			ctype_unc = 1;
	}
out:
	return ctype_unc;
}

/*
 * In this function we override the bundle with
 * the break instruction at the given slot.
 */
static void prepare_break_inst(uint template, uint  slot, uint major_opcode,
	unsigned long kprobe_inst, struct kprobe *p)
{
	unsigned long break_inst = BREAK_INST;
	bundle_t *bundle = &p->ainsn.insn.bundle;

	/*
	 * Copy the original kprobe_inst qualifying predicate(qp)
	 * to the break instruction iff !is_cmp_ctype_unc_inst
	 * because for cmp instruction with ctype equal to unc,
	 * which is a special instruction always needs to be
	 * executed regradless of qp
	 */
	if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
		break_inst |= (0x3f & kprobe_inst);

	switch (slot) {
	  case 0:
		bundle->quad0.slot0 = break_inst;
		break;
	  case 1:
		bundle->quad0.slot1_p0 = break_inst;
		bundle->quad1.slot1_p1 = break_inst >> (64-46);
		break;
	  case 2:
		bundle->quad1.slot2 = break_inst;
		break;
	}

	/*
	 * Update the instruction flag, so that we can
	 * emulate the instruction properly after we
	 * single step on original instruction
	 */
	update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
}

static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
	       	unsigned long *kprobe_inst, uint *major_opcode)
{
	unsigned long kprobe_inst_p0, kprobe_inst_p1;
	unsigned int template;

	template = bundle->quad0.template;

	switch (slot) {
	  case 0:
 		*major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 		*kprobe_inst = bundle->quad0.slot0;
		break;
	  case 1:
 		*major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
  		kprobe_inst_p0 = bundle->quad0.slot1_p0;
  		kprobe_inst_p1 = bundle->quad1.slot1_p1;
  		*kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
		break;
	  case 2:
 		*major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 		*kprobe_inst = bundle->quad1.slot2;
		break;
	}
}

static int valid_kprobe_addr(int template, int slot, unsigned long addr)
{
	if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
		printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n",
				addr);
		return -EINVAL;
	}
	return 0;
}

static inline void save_previous_kprobe(void)
{
	kprobe_prev = current_kprobe;
	kprobe_status_prev = kprobe_status;
}

static inline void restore_previous_kprobe(void)
{
	current_kprobe = kprobe_prev;
	kprobe_status = kprobe_status_prev;
}

static inline void set_current_kprobe(struct kprobe *p)
{
	current_kprobe = p;
}

int arch_prepare_kprobe(struct kprobe *p)
{
	unsigned long addr = (unsigned long) p->addr;
	unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
	unsigned long kprobe_inst=0;
	unsigned int slot = addr & 0xf, template, major_opcode = 0;
	bundle_t *bundle = &p->ainsn.insn.bundle;

	memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
	memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));

 	template = bundle->quad0.template;

	if(valid_kprobe_addr(template, slot, addr))
		return -EINVAL;

	/* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 	if (slot == 1 && bundle_encoding[template][1] == L)
  		slot++;

	/* Get kprobe_inst and major_opcode from the bundle */
	get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);

	if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
			return -EINVAL;

	prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);

	return 0;
}

void arch_arm_kprobe(struct kprobe *p)
{
	unsigned long addr = (unsigned long)p->addr;
	unsigned long arm_addr = addr & ~0xFULL;

	memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
	flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
}

void arch_disarm_kprobe(struct kprobe *p)
{
	unsigned long addr = (unsigned long)p->addr;
	unsigned long arm_addr = addr & ~0xFULL;

	/* p->opcode contains the original unaltered bundle */
	memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
	flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
}

void arch_remove_kprobe(struct kprobe *p)
{
}

/*
 * We are resuming execution after a single step fault, so the pt_regs
 * structure reflects the register state after we executed the instruction
 * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 * the ip to point back to the original stack address. To set the IP address
 * to original stack address, handle the case where we need to fixup the
 * relative IP address and/or fixup branch register.
 */
static void resume_execution(struct kprobe *p, struct pt_regs *regs)
{
  	unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
  	unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 	unsigned long template;
 	int slot = ((unsigned long)p->addr & 0xf);

	template = p->opcode.bundle.quad0.template;

 	if (slot == 1 && bundle_encoding[template][1] == L)
 		slot = 2;

	if (p->ainsn.inst_flag) {

		if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
			/* Fix relative IP address */
 			regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
		}

		if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
		/*
		 * Fix target branch register, software convention is
		 * to use either b0 or b6 or b7, so just checking
		 * only those registers
		 */
			switch (p->ainsn.target_br_reg) {
			case 0:
				if ((regs->b0 == bundle_addr) ||
					(regs->b0 == bundle_addr + 0x10)) {
					regs->b0 = (regs->b0 - bundle_addr) +
						resume_addr;
				}
				break;
			case 6:
				if ((regs->b6 == bundle_addr) ||
					(regs->b6 == bundle_addr + 0x10)) {
					regs->b6 = (regs->b6 - bundle_addr) +
						resume_addr;
				}
				break;
			case 7:
				if ((regs->b7 == bundle_addr) ||
					(regs->b7 == bundle_addr + 0x10)) {
					regs->b7 = (regs->b7 - bundle_addr) +
						resume_addr;
				}
				break;
			} /* end switch */
		}
		goto turn_ss_off;
	}

	if (slot == 2) {
 		if (regs->cr_iip == bundle_addr + 0x10) {
 			regs->cr_iip = resume_addr + 0x10;
 		}
 	} else {
 		if (regs->cr_iip == bundle_addr) {
 			regs->cr_iip = resume_addr;
 		}
	}

turn_ss_off:
  	/* Turn off Single Step bit */
  	ia64_psr(regs)->ss = 0;
}

static void prepare_ss(struct kprobe *p, struct pt_regs *regs)
{
	unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
	unsigned long slot = (unsigned long)p->addr & 0xf;

	/* Update instruction pointer (IIP) and slot number (IPSR.ri) */
	regs->cr_iip = bundle_addr & ~0xFULL;

	if (slot > 2)
		slot = 0;

	ia64_psr(regs)->ri = slot;

	/* turn on single stepping */
	ia64_psr(regs)->ss = 1;
}

static int pre_kprobes_handler(struct die_args *args)
{
	struct kprobe *p;
	int ret = 0;
	struct pt_regs *regs = args->regs;
	kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);

	preempt_disable();

	/* Handle recursion cases */
	if (kprobe_running()) {
		p = get_kprobe(addr);
		if (p) {
			if (kprobe_status == KPROBE_HIT_SS) {
				unlock_kprobes();
				goto no_kprobe;
			}
			/* We have reentered the pre_kprobe_handler(), since
			 * another probe was hit while within the handler.
			 * We here save the original kprobes variables and
			 * just single step on the instruction of the new probe
			 * without calling any user handlers.
			 */
			save_previous_kprobe();
			set_current_kprobe(p);
			p->nmissed++;
			prepare_ss(p, regs);
			kprobe_status = KPROBE_REENTER;
			return 1;
		} else if (args->err == __IA64_BREAK_JPROBE) {
			/*
			 * jprobe instrumented function just completed
			 */
			p = current_kprobe;
			if (p->break_handler && p->break_handler(p, regs)) {
				goto ss_probe;
			}
		} else {
			/* Not our break */
			goto no_kprobe;
		}
	}

	lock_kprobes();
	p = get_kprobe(addr);
	if (!p) {
		unlock_kprobes();
		goto no_kprobe;
	}

	kprobe_status = KPROBE_HIT_ACTIVE;
	set_current_kprobe(p);

	if (p->pre_handler && p->pre_handler(p, regs))
		/*
		 * Our pre-handler is specifically requesting that we just
		 * do a return.  This is handling the case where the
		 * pre-handler is really our special jprobe pre-handler.
		 */
		return 1;

ss_probe:
	prepare_ss(p, regs);
	kprobe_status = KPROBE_HIT_SS;
	return 1;

no_kprobe:
	preempt_enable_no_resched();
	return ret;
}

static int post_kprobes_handler(struct pt_regs *regs)
{
	if (!kprobe_running())
		return 0;

	if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
		kprobe_status = KPROBE_HIT_SSDONE;
		current_kprobe->post_handler(current_kprobe, regs, 0);
	}

	resume_execution(current_kprobe, regs);

	/*Restore back the original saved kprobes variables and continue. */
	if (kprobe_status == KPROBE_REENTER) {
		restore_previous_kprobe();
		goto out;
	}

	unlock_kprobes();

out:
	preempt_enable_no_resched();
	return 1;
}

static int kprobes_fault_handler(struct pt_regs *regs, int trapnr)
{
	if (!kprobe_running())
		return 0;

	if (current_kprobe->fault_handler &&
	    current_kprobe->fault_handler(current_kprobe, regs, trapnr))
		return 1;

	if (kprobe_status & KPROBE_HIT_SS) {
		resume_execution(current_kprobe, regs);
		unlock_kprobes();
		preempt_enable_no_resched();
	}

	return 0;
}

int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
			     void *data)
{
	struct die_args *args = (struct die_args *)data;
	switch(val) {
	case DIE_BREAK:
		if (pre_kprobes_handler(args))
			return NOTIFY_STOP;
		break;
	case DIE_SS:
		if (post_kprobes_handler(args->regs))
			return NOTIFY_STOP;
		break;
	case DIE_PAGE_FAULT:
		if (kprobes_fault_handler(args->regs, args->trapnr))
			return NOTIFY_STOP;
	default:
		break;
	}
	return NOTIFY_DONE;
}

int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct jprobe *jp = container_of(p, struct jprobe, kp);
	unsigned long addr = ((struct fnptr *)(jp->entry))->ip;

	/* save architectural state */
	jprobe_saved_regs = *regs;

	/* after rfi, execute the jprobe instrumented function */
	regs->cr_iip = addr & ~0xFULL;
	ia64_psr(regs)->ri = addr & 0xf;
	regs->r1 = ((struct fnptr *)(jp->entry))->gp;

	/*
	 * fix the return address to our jprobe_inst_return() function
	 * in the jprobes.S file
	 */
 	regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;

	return 1;
}

int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
	*regs = jprobe_saved_regs;
	return 1;
}