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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Kernel Probes (KProbes)
4 * arch/ia64/kernel/kprobes.c
5 *
6 * Copyright (C) IBM Corporation, 2002, 2004
7 * Copyright (C) Intel Corporation, 2005
8 *
9 * 2005-Apr Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
10 * <anil.s.keshavamurthy@intel.com> adapted from i386
11 */
12
13#include <linux/kprobes.h>
14#include <linux/ptrace.h>
15#include <linux/string.h>
16#include <linux/slab.h>
17#include <linux/preempt.h>
18#include <linux/extable.h>
19#include <linux/kdebug.h>
20#include <linux/pgtable.h>
21
22#include <asm/sections.h>
23#include <asm/exception.h>
24
25DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
26DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
27
28struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
29
30enum instruction_type {A, I, M, F, B, L, X, u};
31static enum instruction_type bundle_encoding[32][3] = {
32 [0x00] = { M, I, I },
33 [0x01] = { M, I, I },
34 [0x02] = { M, I, I },
35 [0x03] = { M, I, I },
36 [0x04] = { M, L, X },
37 [0x05] = { M, L, X },
38 [0x06] = { u, u, u },
39 [0x07] = { u, u, u },
40 [0x08] = { M, M, I },
41 [0x09] = { M, M, I },
42 [0x0A] = { M, M, I },
43 [0x0B] = { M, M, I },
44 [0x0C] = { M, F, I },
45 [0x0D] = { M, F, I },
46 [0x0E] = { M, M, F },
47 [0x0F] = { M, M, F },
48 [0x10] = { M, I, B },
49 [0x11] = { M, I, B },
50 [0x12] = { M, B, B },
51 [0x13] = { M, B, B },
52 [0x14] = { u, u, u },
53 [0x15] = { u, u, u },
54 [0x16] = { B, B, B },
55 [0x17] = { B, B, B },
56 [0x18] = { M, M, B },
57 [0x19] = { M, M, B },
58 [0x1A] = { u, u, u },
59 [0x1B] = { u, u, u },
60 [0x1C] = { M, F, B },
61 [0x1D] = { M, F, B },
62 [0x1E] = { u, u, u },
63 [0x1F] = { u, u, u },
64};
65
66/* Insert a long branch code */
67static void __kprobes set_brl_inst(void *from, void *to)
68{
69 s64 rel = ((s64) to - (s64) from) >> 4;
70 bundle_t *brl;
71 brl = (bundle_t *) ((u64) from & ~0xf);
72 brl->quad0.template = 0x05; /* [MLX](stop) */
73 brl->quad0.slot0 = NOP_M_INST; /* nop.m 0x0 */
74 brl->quad0.slot1_p0 = ((rel >> 20) & 0x7fffffffff) << 2;
75 brl->quad1.slot1_p1 = (((rel >> 20) & 0x7fffffffff) << 2) >> (64 - 46);
76 /* brl.cond.sptk.many.clr rel<<4 (qp=0) */
77 brl->quad1.slot2 = BRL_INST(rel >> 59, rel & 0xfffff);
78}
79
80/*
81 * In this function we check to see if the instruction
82 * is IP relative instruction and update the kprobe
83 * inst flag accordingly
84 */
85static void __kprobes update_kprobe_inst_flag(uint template, uint slot,
86 uint major_opcode,
87 unsigned long kprobe_inst,
88 struct kprobe *p)
89{
90 p->ainsn.inst_flag = 0;
91 p->ainsn.target_br_reg = 0;
92 p->ainsn.slot = slot;
93
94 /* Check for Break instruction
95 * Bits 37:40 Major opcode to be zero
96 * Bits 27:32 X6 to be zero
97 * Bits 32:35 X3 to be zero
98 */
99 if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
100 /* is a break instruction */
101 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
102 return;
103 }
104
105 if (bundle_encoding[template][slot] == B) {
106 switch (major_opcode) {
107 case INDIRECT_CALL_OPCODE:
108 p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
109 p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
110 break;
111 case IP_RELATIVE_PREDICT_OPCODE:
112 case IP_RELATIVE_BRANCH_OPCODE:
113 p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
114 break;
115 case IP_RELATIVE_CALL_OPCODE:
116 p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
117 p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
118 p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
119 break;
120 }
121 } else if (bundle_encoding[template][slot] == X) {
122 switch (major_opcode) {
123 case LONG_CALL_OPCODE:
124 p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
125 p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
126 break;
127 }
128 }
129 return;
130}
131
132/*
133 * In this function we check to see if the instruction
134 * (qp) cmpx.crel.ctype p1,p2=r2,r3
135 * on which we are inserting kprobe is cmp instruction
136 * with ctype as unc.
137 */
138static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
139 uint major_opcode,
140 unsigned long kprobe_inst)
141{
142 cmp_inst_t cmp_inst;
143 uint ctype_unc = 0;
144
145 if (!((bundle_encoding[template][slot] == I) ||
146 (bundle_encoding[template][slot] == M)))
147 goto out;
148
149 if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
150 (major_opcode == 0xE)))
151 goto out;
152
153 cmp_inst.l = kprobe_inst;
154 if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
155 /* Integer compare - Register Register (A6 type)*/
156 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
157 &&(cmp_inst.f.c == 1))
158 ctype_unc = 1;
159 } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
160 /* Integer compare - Immediate Register (A8 type)*/
161 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
162 ctype_unc = 1;
163 }
164out:
165 return ctype_unc;
166}
167
168/*
169 * In this function we check to see if the instruction
170 * on which we are inserting kprobe is supported.
171 * Returns qp value if supported
172 * Returns -EINVAL if unsupported
173 */
174static int __kprobes unsupported_inst(uint template, uint slot,
175 uint major_opcode,
176 unsigned long kprobe_inst,
177 unsigned long addr)
178{
179 int qp;
180
181 qp = kprobe_inst & 0x3f;
182 if (is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst)) {
183 if (slot == 1 && qp) {
184 printk(KERN_WARNING "Kprobes on cmp unc "
185 "instruction on slot 1 at <0x%lx> "
186 "is not supported\n", addr);
187 return -EINVAL;
188
189 }
190 qp = 0;
191 }
192 else if (bundle_encoding[template][slot] == I) {
193 if (major_opcode == 0) {
194 /*
195 * Check for Integer speculation instruction
196 * - Bit 33-35 to be equal to 0x1
197 */
198 if (((kprobe_inst >> 33) & 0x7) == 1) {
199 printk(KERN_WARNING
200 "Kprobes on speculation inst at <0x%lx> not supported\n",
201 addr);
202 return -EINVAL;
203 }
204 /*
205 * IP relative mov instruction
206 * - Bit 27-35 to be equal to 0x30
207 */
208 if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
209 printk(KERN_WARNING
210 "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
211 addr);
212 return -EINVAL;
213
214 }
215 }
216 else if ((major_opcode == 5) && !(kprobe_inst & (0xFUl << 33)) &&
217 (kprobe_inst & (0x1UL << 12))) {
218 /* test bit instructions, tbit,tnat,tf
219 * bit 33-36 to be equal to 0
220 * bit 12 to be equal to 1
221 */
222 if (slot == 1 && qp) {
223 printk(KERN_WARNING "Kprobes on test bit "
224 "instruction on slot at <0x%lx> "
225 "is not supported\n", addr);
226 return -EINVAL;
227 }
228 qp = 0;
229 }
230 }
231 else if (bundle_encoding[template][slot] == B) {
232 if (major_opcode == 7) {
233 /* IP-Relative Predict major code is 7 */
234 printk(KERN_WARNING "Kprobes on IP-Relative"
235 "Predict is not supported\n");
236 return -EINVAL;
237 }
238 else if (major_opcode == 2) {
239 /* Indirect Predict, major code is 2
240 * bit 27-32 to be equal to 10 or 11
241 */
242 int x6=(kprobe_inst >> 27) & 0x3F;
243 if ((x6 == 0x10) || (x6 == 0x11)) {
244 printk(KERN_WARNING "Kprobes on "
245 "Indirect Predict is not supported\n");
246 return -EINVAL;
247 }
248 }
249 }
250 /* kernel does not use float instruction, here for safety kprobe
251 * will judge whether it is fcmp/flass/float approximation instruction
252 */
253 else if (unlikely(bundle_encoding[template][slot] == F)) {
254 if ((major_opcode == 4 || major_opcode == 5) &&
255 (kprobe_inst & (0x1 << 12))) {
256 /* fcmp/fclass unc instruction */
257 if (slot == 1 && qp) {
258 printk(KERN_WARNING "Kprobes on fcmp/fclass "
259 "instruction on slot at <0x%lx> "
260 "is not supported\n", addr);
261 return -EINVAL;
262
263 }
264 qp = 0;
265 }
266 if ((major_opcode == 0 || major_opcode == 1) &&
267 (kprobe_inst & (0x1UL << 33))) {
268 /* float Approximation instruction */
269 if (slot == 1 && qp) {
270 printk(KERN_WARNING "Kprobes on float Approx "
271 "instr at <0x%lx> is not supported\n",
272 addr);
273 return -EINVAL;
274 }
275 qp = 0;
276 }
277 }
278 return qp;
279}
280
281/*
282 * In this function we override the bundle with
283 * the break instruction at the given slot.
284 */
285static void __kprobes prepare_break_inst(uint template, uint slot,
286 uint major_opcode,
287 unsigned long kprobe_inst,
288 struct kprobe *p,
289 int qp)
290{
291 unsigned long break_inst = BREAK_INST;
292 bundle_t *bundle = &p->opcode.bundle;
293
294 /*
295 * Copy the original kprobe_inst qualifying predicate(qp)
296 * to the break instruction
297 */
298 break_inst |= qp;
299
300 switch (slot) {
301 case 0:
302 bundle->quad0.slot0 = break_inst;
303 break;
304 case 1:
305 bundle->quad0.slot1_p0 = break_inst;
306 bundle->quad1.slot1_p1 = break_inst >> (64-46);
307 break;
308 case 2:
309 bundle->quad1.slot2 = break_inst;
310 break;
311 }
312
313 /*
314 * Update the instruction flag, so that we can
315 * emulate the instruction properly after we
316 * single step on original instruction
317 */
318 update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
319}
320
321static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
322 unsigned long *kprobe_inst, uint *major_opcode)
323{
324 unsigned long kprobe_inst_p0, kprobe_inst_p1;
325 unsigned int template;
326
327 template = bundle->quad0.template;
328
329 switch (slot) {
330 case 0:
331 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
332 *kprobe_inst = bundle->quad0.slot0;
333 break;
334 case 1:
335 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
336 kprobe_inst_p0 = bundle->quad0.slot1_p0;
337 kprobe_inst_p1 = bundle->quad1.slot1_p1;
338 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
339 break;
340 case 2:
341 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
342 *kprobe_inst = bundle->quad1.slot2;
343 break;
344 }
345}
346
347/* Returns non-zero if the addr is in the Interrupt Vector Table */
348static int __kprobes in_ivt_functions(unsigned long addr)
349{
350 return (addr >= (unsigned long)__start_ivt_text
351 && addr < (unsigned long)__end_ivt_text);
352}
353
354static int __kprobes valid_kprobe_addr(int template, int slot,
355 unsigned long addr)
356{
357 if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
358 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
359 "at 0x%lx\n", addr);
360 return -EINVAL;
361 }
362
363 if (in_ivt_functions(addr)) {
364 printk(KERN_WARNING "Kprobes can't be inserted inside "
365 "IVT functions at 0x%lx\n", addr);
366 return -EINVAL;
367 }
368
369 return 0;
370}
371
372static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
373{
374 unsigned int i;
375 i = atomic_add_return(1, &kcb->prev_kprobe_index);
376 kcb->prev_kprobe[i-1].kp = kprobe_running();
377 kcb->prev_kprobe[i-1].status = kcb->kprobe_status;
378}
379
380static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
381{
382 unsigned int i;
383 i = atomic_read(&kcb->prev_kprobe_index);
384 __this_cpu_write(current_kprobe, kcb->prev_kprobe[i-1].kp);
385 kcb->kprobe_status = kcb->prev_kprobe[i-1].status;
386 atomic_sub(1, &kcb->prev_kprobe_index);
387}
388
389static void __kprobes set_current_kprobe(struct kprobe *p,
390 struct kprobe_ctlblk *kcb)
391{
392 __this_cpu_write(current_kprobe, p);
393}
394
395void __kretprobe_trampoline(void)
396{
397}
398
399int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
400{
401 regs->cr_iip = __kretprobe_trampoline_handler(regs, NULL);
402 /*
403 * By returning a non-zero value, we are telling
404 * kprobe_handler() that we don't want the post_handler
405 * to run (and have re-enabled preemption)
406 */
407 return 1;
408}
409
410void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
411 struct pt_regs *regs)
412{
413 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
414 ri->fp = NULL;
415
416 /* Replace the return addr with trampoline addr */
417 regs->b0 = (unsigned long)dereference_function_descriptor(__kretprobe_trampoline);
418}
419
420/* Check the instruction in the slot is break */
421static int __kprobes __is_ia64_break_inst(bundle_t *bundle, uint slot)
422{
423 unsigned int major_opcode;
424 unsigned int template = bundle->quad0.template;
425 unsigned long kprobe_inst;
426
427 /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
428 if (slot == 1 && bundle_encoding[template][1] == L)
429 slot++;
430
431 /* Get Kprobe probe instruction at given slot*/
432 get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
433
434 /* For break instruction,
435 * Bits 37:40 Major opcode to be zero
436 * Bits 27:32 X6 to be zero
437 * Bits 32:35 X3 to be zero
438 */
439 if (major_opcode || ((kprobe_inst >> 27) & 0x1FF)) {
440 /* Not a break instruction */
441 return 0;
442 }
443
444 /* Is a break instruction */
445 return 1;
446}
447
448/*
449 * In this function, we check whether the target bundle modifies IP or
450 * it triggers an exception. If so, it cannot be boostable.
451 */
452static int __kprobes can_boost(bundle_t *bundle, uint slot,
453 unsigned long bundle_addr)
454{
455 unsigned int template = bundle->quad0.template;
456
457 do {
458 if (search_exception_tables(bundle_addr + slot) ||
459 __is_ia64_break_inst(bundle, slot))
460 return 0; /* exception may occur in this bundle*/
461 } while ((++slot) < 3);
462 template &= 0x1e;
463 if (template >= 0x10 /* including B unit */ ||
464 template == 0x04 /* including X unit */ ||
465 template == 0x06) /* undefined */
466 return 0;
467
468 return 1;
469}
470
471/* Prepare long jump bundle and disables other boosters if need */
472static void __kprobes prepare_booster(struct kprobe *p)
473{
474 unsigned long addr = (unsigned long)p->addr & ~0xFULL;
475 unsigned int slot = (unsigned long)p->addr & 0xf;
476 struct kprobe *other_kp;
477
478 if (can_boost(&p->ainsn.insn[0].bundle, slot, addr)) {
479 set_brl_inst(&p->ainsn.insn[1].bundle, (bundle_t *)addr + 1);
480 p->ainsn.inst_flag |= INST_FLAG_BOOSTABLE;
481 }
482
483 /* disables boosters in previous slots */
484 for (; addr < (unsigned long)p->addr; addr++) {
485 other_kp = get_kprobe((void *)addr);
486 if (other_kp)
487 other_kp->ainsn.inst_flag &= ~INST_FLAG_BOOSTABLE;
488 }
489}
490
491int __kprobes arch_prepare_kprobe(struct kprobe *p)
492{
493 unsigned long addr = (unsigned long) p->addr;
494 unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
495 unsigned long kprobe_inst=0;
496 unsigned int slot = addr & 0xf, template, major_opcode = 0;
497 bundle_t *bundle;
498 int qp;
499
500 bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
501 template = bundle->quad0.template;
502
503 if(valid_kprobe_addr(template, slot, addr))
504 return -EINVAL;
505
506 /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
507 if (slot == 1 && bundle_encoding[template][1] == L)
508 slot++;
509
510 /* Get kprobe_inst and major_opcode from the bundle */
511 get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
512
513 qp = unsupported_inst(template, slot, major_opcode, kprobe_inst, addr);
514 if (qp < 0)
515 return -EINVAL;
516
517 p->ainsn.insn = get_insn_slot();
518 if (!p->ainsn.insn)
519 return -ENOMEM;
520 memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
521 memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
522
523 prepare_break_inst(template, slot, major_opcode, kprobe_inst, p, qp);
524
525 prepare_booster(p);
526
527 return 0;
528}
529
530void __kprobes arch_arm_kprobe(struct kprobe *p)
531{
532 unsigned long arm_addr;
533 bundle_t *src, *dest;
534
535 arm_addr = ((unsigned long)p->addr) & ~0xFUL;
536 dest = &((kprobe_opcode_t *)arm_addr)->bundle;
537 src = &p->opcode.bundle;
538
539 flush_icache_range((unsigned long)p->ainsn.insn,
540 (unsigned long)p->ainsn.insn +
541 sizeof(kprobe_opcode_t) * MAX_INSN_SIZE);
542
543 switch (p->ainsn.slot) {
544 case 0:
545 dest->quad0.slot0 = src->quad0.slot0;
546 break;
547 case 1:
548 dest->quad1.slot1_p1 = src->quad1.slot1_p1;
549 break;
550 case 2:
551 dest->quad1.slot2 = src->quad1.slot2;
552 break;
553 }
554 flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
555}
556
557void __kprobes arch_disarm_kprobe(struct kprobe *p)
558{
559 unsigned long arm_addr;
560 bundle_t *src, *dest;
561
562 arm_addr = ((unsigned long)p->addr) & ~0xFUL;
563 dest = &((kprobe_opcode_t *)arm_addr)->bundle;
564 /* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
565 src = &p->ainsn.insn->bundle;
566 switch (p->ainsn.slot) {
567 case 0:
568 dest->quad0.slot0 = src->quad0.slot0;
569 break;
570 case 1:
571 dest->quad1.slot1_p1 = src->quad1.slot1_p1;
572 break;
573 case 2:
574 dest->quad1.slot2 = src->quad1.slot2;
575 break;
576 }
577 flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
578}
579
580void __kprobes arch_remove_kprobe(struct kprobe *p)
581{
582 if (p->ainsn.insn) {
583 free_insn_slot(p->ainsn.insn,
584 p->ainsn.inst_flag & INST_FLAG_BOOSTABLE);
585 p->ainsn.insn = NULL;
586 }
587}
588/*
589 * We are resuming execution after a single step fault, so the pt_regs
590 * structure reflects the register state after we executed the instruction
591 * located in the kprobe (p->ainsn.insn->bundle). We still need to adjust
592 * the ip to point back to the original stack address. To set the IP address
593 * to original stack address, handle the case where we need to fixup the
594 * relative IP address and/or fixup branch register.
595 */
596static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
597{
598 unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
599 unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
600 unsigned long template;
601 int slot = ((unsigned long)p->addr & 0xf);
602
603 template = p->ainsn.insn->bundle.quad0.template;
604
605 if (slot == 1 && bundle_encoding[template][1] == L)
606 slot = 2;
607
608 if (p->ainsn.inst_flag & ~INST_FLAG_BOOSTABLE) {
609
610 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
611 /* Fix relative IP address */
612 regs->cr_iip = (regs->cr_iip - bundle_addr) +
613 resume_addr;
614 }
615
616 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
617 /*
618 * Fix target branch register, software convention is
619 * to use either b0 or b6 or b7, so just checking
620 * only those registers
621 */
622 switch (p->ainsn.target_br_reg) {
623 case 0:
624 if ((regs->b0 == bundle_addr) ||
625 (regs->b0 == bundle_addr + 0x10)) {
626 regs->b0 = (regs->b0 - bundle_addr) +
627 resume_addr;
628 }
629 break;
630 case 6:
631 if ((regs->b6 == bundle_addr) ||
632 (regs->b6 == bundle_addr + 0x10)) {
633 regs->b6 = (regs->b6 - bundle_addr) +
634 resume_addr;
635 }
636 break;
637 case 7:
638 if ((regs->b7 == bundle_addr) ||
639 (regs->b7 == bundle_addr + 0x10)) {
640 regs->b7 = (regs->b7 - bundle_addr) +
641 resume_addr;
642 }
643 break;
644 } /* end switch */
645 }
646 goto turn_ss_off;
647 }
648
649 if (slot == 2) {
650 if (regs->cr_iip == bundle_addr + 0x10) {
651 regs->cr_iip = resume_addr + 0x10;
652 }
653 } else {
654 if (regs->cr_iip == bundle_addr) {
655 regs->cr_iip = resume_addr;
656 }
657 }
658
659turn_ss_off:
660 /* Turn off Single Step bit */
661 ia64_psr(regs)->ss = 0;
662}
663
664static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
665{
666 unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
667 unsigned long slot = (unsigned long)p->addr & 0xf;
668
669 /* single step inline if break instruction */
670 if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
671 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
672 else
673 regs->cr_iip = bundle_addr & ~0xFULL;
674
675 if (slot > 2)
676 slot = 0;
677
678 ia64_psr(regs)->ri = slot;
679
680 /* turn on single stepping */
681 ia64_psr(regs)->ss = 1;
682}
683
684static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
685{
686 unsigned int slot = ia64_psr(regs)->ri;
687 unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
688 bundle_t bundle;
689
690 memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
691
692 return __is_ia64_break_inst(&bundle, slot);
693}
694
695static int __kprobes pre_kprobes_handler(struct die_args *args)
696{
697 struct kprobe *p;
698 int ret = 0;
699 struct pt_regs *regs = args->regs;
700 kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
701 struct kprobe_ctlblk *kcb;
702
703 /*
704 * We don't want to be preempted for the entire
705 * duration of kprobe processing
706 */
707 preempt_disable();
708 kcb = get_kprobe_ctlblk();
709
710 /* Handle recursion cases */
711 if (kprobe_running()) {
712 p = get_kprobe(addr);
713 if (p) {
714 if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
715 (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
716 ia64_psr(regs)->ss = 0;
717 goto no_kprobe;
718 }
719 /* We have reentered the pre_kprobe_handler(), since
720 * another probe was hit while within the handler.
721 * We here save the original kprobes variables and
722 * just single step on the instruction of the new probe
723 * without calling any user handlers.
724 */
725 save_previous_kprobe(kcb);
726 set_current_kprobe(p, kcb);
727 kprobes_inc_nmissed_count(p);
728 prepare_ss(p, regs);
729 kcb->kprobe_status = KPROBE_REENTER;
730 return 1;
731 } else if (!is_ia64_break_inst(regs)) {
732 /* The breakpoint instruction was removed by
733 * another cpu right after we hit, no further
734 * handling of this interrupt is appropriate
735 */
736 ret = 1;
737 goto no_kprobe;
738 } else {
739 /* Not our break */
740 goto no_kprobe;
741 }
742 }
743
744 p = get_kprobe(addr);
745 if (!p) {
746 if (!is_ia64_break_inst(regs)) {
747 /*
748 * The breakpoint instruction was removed right
749 * after we hit it. Another cpu has removed
750 * either a probepoint or a debugger breakpoint
751 * at this address. In either case, no further
752 * handling of this interrupt is appropriate.
753 */
754 ret = 1;
755
756 }
757
758 /* Not one of our break, let kernel handle it */
759 goto no_kprobe;
760 }
761
762 set_current_kprobe(p, kcb);
763 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
764
765 if (p->pre_handler && p->pre_handler(p, regs)) {
766 reset_current_kprobe();
767 preempt_enable_no_resched();
768 return 1;
769 }
770
771#if !defined(CONFIG_PREEMPTION)
772 if (p->ainsn.inst_flag == INST_FLAG_BOOSTABLE && !p->post_handler) {
773 /* Boost up -- we can execute copied instructions directly */
774 ia64_psr(regs)->ri = p->ainsn.slot;
775 regs->cr_iip = (unsigned long)&p->ainsn.insn->bundle & ~0xFULL;
776 /* turn single stepping off */
777 ia64_psr(regs)->ss = 0;
778
779 reset_current_kprobe();
780 preempt_enable_no_resched();
781 return 1;
782 }
783#endif
784 prepare_ss(p, regs);
785 kcb->kprobe_status = KPROBE_HIT_SS;
786 return 1;
787
788no_kprobe:
789 preempt_enable_no_resched();
790 return ret;
791}
792
793static int __kprobes post_kprobes_handler(struct pt_regs *regs)
794{
795 struct kprobe *cur = kprobe_running();
796 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
797
798 if (!cur)
799 return 0;
800
801 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
802 kcb->kprobe_status = KPROBE_HIT_SSDONE;
803 cur->post_handler(cur, regs, 0);
804 }
805
806 resume_execution(cur, regs);
807
808 /*Restore back the original saved kprobes variables and continue. */
809 if (kcb->kprobe_status == KPROBE_REENTER) {
810 restore_previous_kprobe(kcb);
811 goto out;
812 }
813 reset_current_kprobe();
814
815out:
816 preempt_enable_no_resched();
817 return 1;
818}
819
820int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
821{
822 struct kprobe *cur = kprobe_running();
823 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
824
825
826 switch(kcb->kprobe_status) {
827 case KPROBE_HIT_SS:
828 case KPROBE_REENTER:
829 /*
830 * We are here because the instruction being single
831 * stepped caused a page fault. We reset the current
832 * kprobe and the instruction pointer points back to
833 * the probe address and allow the page fault handler
834 * to continue as a normal page fault.
835 */
836 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
837 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
838 if (kcb->kprobe_status == KPROBE_REENTER)
839 restore_previous_kprobe(kcb);
840 else
841 reset_current_kprobe();
842 preempt_enable_no_resched();
843 break;
844 case KPROBE_HIT_ACTIVE:
845 case KPROBE_HIT_SSDONE:
846 /*
847 * In case the user-specified fault handler returned
848 * zero, try to fix up.
849 */
850 if (ia64_done_with_exception(regs))
851 return 1;
852
853 /*
854 * Let ia64_do_page_fault() fix it.
855 */
856 break;
857 default:
858 break;
859 }
860
861 return 0;
862}
863
864int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
865 unsigned long val, void *data)
866{
867 struct die_args *args = (struct die_args *)data;
868 int ret = NOTIFY_DONE;
869
870 if (args->regs && user_mode(args->regs))
871 return ret;
872
873 switch(val) {
874 case DIE_BREAK:
875 /* err is break number from ia64_bad_break() */
876 if ((args->err >> 12) == (__IA64_BREAK_KPROBE >> 12)
877 || args->err == 0)
878 if (pre_kprobes_handler(args))
879 ret = NOTIFY_STOP;
880 break;
881 case DIE_FAULT:
882 /* err is vector number from ia64_fault() */
883 if (args->err == 36)
884 if (post_kprobes_handler(args->regs))
885 ret = NOTIFY_STOP;
886 break;
887 default:
888 break;
889 }
890 return ret;
891}
892
893static struct kprobe trampoline_p = {
894 .pre_handler = trampoline_probe_handler
895};
896
897int __init arch_init_kprobes(void)
898{
899 trampoline_p.addr =
900 dereference_function_descriptor(__kretprobe_trampoline);
901 return register_kprobe(&trampoline_p);
902}
903
904int __kprobes arch_trampoline_kprobe(struct kprobe *p)
905{
906 if (p->addr ==
907 dereference_function_descriptor(__kretprobe_trampoline))
908 return 1;
909
910 return 0;
911}