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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Kernel Probes (KProbes)
4 *
5 * Copyright (C) IBM Corporation, 2002, 2004
6 *
7 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
8 * Probes initial implementation ( includes contributions from
9 * Rusty Russell).
10 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
11 * interface to access function arguments.
12 * 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
13 * for PPC64
14 */
15
16#include <linux/kprobes.h>
17#include <linux/ptrace.h>
18#include <linux/preempt.h>
19#include <linux/extable.h>
20#include <linux/kdebug.h>
21#include <linux/slab.h>
22#include <linux/moduleloader.h>
23#include <linux/set_memory.h>
24#include <asm/code-patching.h>
25#include <asm/cacheflush.h>
26#include <asm/sstep.h>
27#include <asm/sections.h>
28#include <asm/inst.h>
29#include <linux/uaccess.h>
30
31DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
32DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
33
34struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
35
36bool arch_within_kprobe_blacklist(unsigned long addr)
37{
38 return (addr >= (unsigned long)__kprobes_text_start &&
39 addr < (unsigned long)__kprobes_text_end) ||
40 (addr >= (unsigned long)_stext &&
41 addr < (unsigned long)__head_end);
42}
43
44kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
45{
46 kprobe_opcode_t *addr = NULL;
47
48#ifdef CONFIG_PPC64_ELF_ABI_V2
49 /* PPC64 ABIv2 needs local entry point */
50 addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
51 if (addr && !offset) {
52#ifdef CONFIG_KPROBES_ON_FTRACE
53 unsigned long faddr;
54 /*
55 * Per livepatch.h, ftrace location is always within the first
56 * 16 bytes of a function on powerpc with -mprofile-kernel.
57 */
58 faddr = ftrace_location_range((unsigned long)addr,
59 (unsigned long)addr + 16);
60 if (faddr)
61 addr = (kprobe_opcode_t *)faddr;
62 else
63#endif
64 addr = (kprobe_opcode_t *)ppc_function_entry(addr);
65 }
66#elif defined(CONFIG_PPC64_ELF_ABI_V1)
67 /*
68 * 64bit powerpc ABIv1 uses function descriptors:
69 * - Check for the dot variant of the symbol first.
70 * - If that fails, try looking up the symbol provided.
71 *
72 * This ensures we always get to the actual symbol and not
73 * the descriptor.
74 *
75 * Also handle <module:symbol> format.
76 */
77 char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];
78 bool dot_appended = false;
79 const char *c;
80 ssize_t ret = 0;
81 int len = 0;
82
83 if ((c = strnchr(name, MODULE_NAME_LEN, ':')) != NULL) {
84 c++;
85 len = c - name;
86 memcpy(dot_name, name, len);
87 } else
88 c = name;
89
90 if (*c != '\0' && *c != '.') {
91 dot_name[len++] = '.';
92 dot_appended = true;
93 }
94 ret = strscpy(dot_name + len, c, KSYM_NAME_LEN);
95 if (ret > 0)
96 addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name);
97
98 /* Fallback to the original non-dot symbol lookup */
99 if (!addr && dot_appended)
100 addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
101#else
102 addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
103#endif
104
105 return addr;
106}
107
108static bool arch_kprobe_on_func_entry(unsigned long offset)
109{
110#ifdef CONFIG_PPC64_ELF_ABI_V2
111#ifdef CONFIG_KPROBES_ON_FTRACE
112 return offset <= 16;
113#else
114 return offset <= 8;
115#endif
116#else
117 return !offset;
118#endif
119}
120
121/* XXX try and fold the magic of kprobe_lookup_name() in this */
122kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset,
123 bool *on_func_entry)
124{
125 *on_func_entry = arch_kprobe_on_func_entry(offset);
126 return (kprobe_opcode_t *)(addr + offset);
127}
128
129void *alloc_insn_page(void)
130{
131 void *page;
132
133 page = module_alloc(PAGE_SIZE);
134 if (!page)
135 return NULL;
136
137 if (strict_module_rwx_enabled())
138 set_memory_rox((unsigned long)page, 1);
139
140 return page;
141}
142
143int arch_prepare_kprobe(struct kprobe *p)
144{
145 int ret = 0;
146 struct kprobe *prev;
147 ppc_inst_t insn = ppc_inst_read(p->addr);
148
149 if ((unsigned long)p->addr & 0x03) {
150 printk("Attempt to register kprobe at an unaligned address\n");
151 ret = -EINVAL;
152 } else if (!can_single_step(ppc_inst_val(insn))) {
153 printk("Cannot register a kprobe on instructions that can't be single stepped\n");
154 ret = -EINVAL;
155 } else if ((unsigned long)p->addr & ~PAGE_MASK &&
156 ppc_inst_prefixed(ppc_inst_read(p->addr - 1))) {
157 printk("Cannot register a kprobe on the second word of prefixed instruction\n");
158 ret = -EINVAL;
159 }
160 prev = get_kprobe(p->addr - 1);
161
162 /*
163 * When prev is a ftrace-based kprobe, we don't have an insn, and it
164 * doesn't probe for prefixed instruction.
165 */
166 if (prev && !kprobe_ftrace(prev) &&
167 ppc_inst_prefixed(ppc_inst_read(prev->ainsn.insn))) {
168 printk("Cannot register a kprobe on the second word of prefixed instruction\n");
169 ret = -EINVAL;
170 }
171
172 /* insn must be on a special executable page on ppc64. This is
173 * not explicitly required on ppc32 (right now), but it doesn't hurt */
174 if (!ret) {
175 p->ainsn.insn = get_insn_slot();
176 if (!p->ainsn.insn)
177 ret = -ENOMEM;
178 }
179
180 if (!ret) {
181 patch_instruction(p->ainsn.insn, insn);
182 p->opcode = ppc_inst_val(insn);
183 }
184
185 p->ainsn.boostable = 0;
186 return ret;
187}
188NOKPROBE_SYMBOL(arch_prepare_kprobe);
189
190void arch_arm_kprobe(struct kprobe *p)
191{
192 WARN_ON_ONCE(patch_instruction(p->addr, ppc_inst(BREAKPOINT_INSTRUCTION)));
193}
194NOKPROBE_SYMBOL(arch_arm_kprobe);
195
196void arch_disarm_kprobe(struct kprobe *p)
197{
198 WARN_ON_ONCE(patch_instruction(p->addr, ppc_inst(p->opcode)));
199}
200NOKPROBE_SYMBOL(arch_disarm_kprobe);
201
202void arch_remove_kprobe(struct kprobe *p)
203{
204 if (p->ainsn.insn) {
205 free_insn_slot(p->ainsn.insn, 0);
206 p->ainsn.insn = NULL;
207 }
208}
209NOKPROBE_SYMBOL(arch_remove_kprobe);
210
211static nokprobe_inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
212{
213 enable_single_step(regs);
214
215 /*
216 * On powerpc we should single step on the original
217 * instruction even if the probed insn is a trap
218 * variant as values in regs could play a part in
219 * if the trap is taken or not
220 */
221 regs_set_return_ip(regs, (unsigned long)p->ainsn.insn);
222}
223
224static nokprobe_inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
225{
226 kcb->prev_kprobe.kp = kprobe_running();
227 kcb->prev_kprobe.status = kcb->kprobe_status;
228 kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;
229}
230
231static nokprobe_inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
232{
233 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
234 kcb->kprobe_status = kcb->prev_kprobe.status;
235 kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;
236}
237
238static nokprobe_inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
239 struct kprobe_ctlblk *kcb)
240{
241 __this_cpu_write(current_kprobe, p);
242 kcb->kprobe_saved_msr = regs->msr;
243}
244
245void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
246{
247 ri->ret_addr = (kprobe_opcode_t *)regs->link;
248 ri->fp = NULL;
249
250 /* Replace the return addr with trampoline addr */
251 regs->link = (unsigned long)__kretprobe_trampoline;
252}
253NOKPROBE_SYMBOL(arch_prepare_kretprobe);
254
255static int try_to_emulate(struct kprobe *p, struct pt_regs *regs)
256{
257 int ret;
258 ppc_inst_t insn = ppc_inst_read(p->ainsn.insn);
259
260 /* regs->nip is also adjusted if emulate_step returns 1 */
261 ret = emulate_step(regs, insn);
262 if (ret > 0) {
263 /*
264 * Once this instruction has been boosted
265 * successfully, set the boostable flag
266 */
267 if (unlikely(p->ainsn.boostable == 0))
268 p->ainsn.boostable = 1;
269 } else if (ret < 0) {
270 /*
271 * We don't allow kprobes on mtmsr(d)/rfi(d), etc.
272 * So, we should never get here... but, its still
273 * good to catch them, just in case...
274 */
275 printk("Can't step on instruction %08lx\n", ppc_inst_as_ulong(insn));
276 BUG();
277 } else {
278 /*
279 * If we haven't previously emulated this instruction, then it
280 * can't be boosted. Note it down so we don't try to do so again.
281 *
282 * If, however, we had emulated this instruction in the past,
283 * then this is just an error with the current run (for
284 * instance, exceptions due to a load/store). We return 0 so
285 * that this is now single-stepped, but continue to try
286 * emulating it in subsequent probe hits.
287 */
288 if (unlikely(p->ainsn.boostable != 1))
289 p->ainsn.boostable = -1;
290 }
291
292 return ret;
293}
294NOKPROBE_SYMBOL(try_to_emulate);
295
296int kprobe_handler(struct pt_regs *regs)
297{
298 struct kprobe *p;
299 int ret = 0;
300 unsigned int *addr = (unsigned int *)regs->nip;
301 struct kprobe_ctlblk *kcb;
302
303 if (user_mode(regs))
304 return 0;
305
306 if (!IS_ENABLED(CONFIG_BOOKE) &&
307 (!(regs->msr & MSR_IR) || !(regs->msr & MSR_DR)))
308 return 0;
309
310 /*
311 * We don't want to be preempted for the entire
312 * duration of kprobe processing
313 */
314 preempt_disable();
315 kcb = get_kprobe_ctlblk();
316
317 p = get_kprobe(addr);
318 if (!p) {
319 unsigned int instr;
320
321 if (get_kernel_nofault(instr, addr))
322 goto no_kprobe;
323
324 if (instr != BREAKPOINT_INSTRUCTION) {
325 /*
326 * PowerPC has multiple variants of the "trap"
327 * instruction. If the current instruction is a
328 * trap variant, it could belong to someone else
329 */
330 if (is_trap(instr))
331 goto no_kprobe;
332 /*
333 * The breakpoint instruction was removed right
334 * after we hit it. Another cpu has removed
335 * either a probepoint or a debugger breakpoint
336 * at this address. In either case, no further
337 * handling of this interrupt is appropriate.
338 */
339 ret = 1;
340 }
341 /* Not one of ours: let kernel handle it */
342 goto no_kprobe;
343 }
344
345 /* Check we're not actually recursing */
346 if (kprobe_running()) {
347 kprobe_opcode_t insn = *p->ainsn.insn;
348 if (kcb->kprobe_status == KPROBE_HIT_SS && is_trap(insn)) {
349 /* Turn off 'trace' bits */
350 regs_set_return_msr(regs,
351 (regs->msr & ~MSR_SINGLESTEP) |
352 kcb->kprobe_saved_msr);
353 goto no_kprobe;
354 }
355
356 /*
357 * We have reentered the kprobe_handler(), since another probe
358 * was hit while within the handler. We here save the original
359 * kprobes variables and just single step on the instruction of
360 * the new probe without calling any user handlers.
361 */
362 save_previous_kprobe(kcb);
363 set_current_kprobe(p, regs, kcb);
364 kprobes_inc_nmissed_count(p);
365 kcb->kprobe_status = KPROBE_REENTER;
366 if (p->ainsn.boostable >= 0) {
367 ret = try_to_emulate(p, regs);
368
369 if (ret > 0) {
370 restore_previous_kprobe(kcb);
371 preempt_enable();
372 return 1;
373 }
374 }
375 prepare_singlestep(p, regs);
376 return 1;
377 }
378
379 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
380 set_current_kprobe(p, regs, kcb);
381 if (p->pre_handler && p->pre_handler(p, regs)) {
382 /* handler changed execution path, so skip ss setup */
383 reset_current_kprobe();
384 preempt_enable();
385 return 1;
386 }
387
388 if (p->ainsn.boostable >= 0) {
389 ret = try_to_emulate(p, regs);
390
391 if (ret > 0) {
392 if (p->post_handler)
393 p->post_handler(p, regs, 0);
394
395 kcb->kprobe_status = KPROBE_HIT_SSDONE;
396 reset_current_kprobe();
397 preempt_enable();
398 return 1;
399 }
400 }
401 prepare_singlestep(p, regs);
402 kcb->kprobe_status = KPROBE_HIT_SS;
403 return 1;
404
405no_kprobe:
406 preempt_enable();
407 return ret;
408}
409NOKPROBE_SYMBOL(kprobe_handler);
410
411/*
412 * Function return probe trampoline:
413 * - init_kprobes() establishes a probepoint here
414 * - When the probed function returns, this probe
415 * causes the handlers to fire
416 */
417asm(".global __kretprobe_trampoline\n"
418 ".type __kretprobe_trampoline, @function\n"
419 "__kretprobe_trampoline:\n"
420 "nop\n"
421 "blr\n"
422 ".size __kretprobe_trampoline, .-__kretprobe_trampoline\n");
423
424/*
425 * Called when the probe at kretprobe trampoline is hit
426 */
427static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
428{
429 unsigned long orig_ret_address;
430
431 orig_ret_address = __kretprobe_trampoline_handler(regs, NULL);
432 /*
433 * We get here through one of two paths:
434 * 1. by taking a trap -> kprobe_handler() -> here
435 * 2. by optprobe branch -> optimized_callback() -> opt_pre_handler() -> here
436 *
437 * When going back through (1), we need regs->nip to be setup properly
438 * as it is used to determine the return address from the trap.
439 * For (2), since nip is not honoured with optprobes, we instead setup
440 * the link register properly so that the subsequent 'blr' in
441 * __kretprobe_trampoline jumps back to the right instruction.
442 *
443 * For nip, we should set the address to the previous instruction since
444 * we end up emulating it in kprobe_handler(), which increments the nip
445 * again.
446 */
447 regs_set_return_ip(regs, orig_ret_address - 4);
448 regs->link = orig_ret_address;
449
450 return 0;
451}
452NOKPROBE_SYMBOL(trampoline_probe_handler);
453
454/*
455 * Called after single-stepping. p->addr is the address of the
456 * instruction whose first byte has been replaced by the "breakpoint"
457 * instruction. To avoid the SMP problems that can occur when we
458 * temporarily put back the original opcode to single-step, we
459 * single-stepped a copy of the instruction. The address of this
460 * copy is p->ainsn.insn.
461 */
462int kprobe_post_handler(struct pt_regs *regs)
463{
464 int len;
465 struct kprobe *cur = kprobe_running();
466 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
467
468 if (!cur || user_mode(regs))
469 return 0;
470
471 len = ppc_inst_len(ppc_inst_read(cur->ainsn.insn));
472 /* make sure we got here for instruction we have a kprobe on */
473 if (((unsigned long)cur->ainsn.insn + len) != regs->nip)
474 return 0;
475
476 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
477 kcb->kprobe_status = KPROBE_HIT_SSDONE;
478 cur->post_handler(cur, regs, 0);
479 }
480
481 /* Adjust nip to after the single-stepped instruction */
482 regs_set_return_ip(regs, (unsigned long)cur->addr + len);
483 regs_set_return_msr(regs, regs->msr | kcb->kprobe_saved_msr);
484
485 /*Restore back the original saved kprobes variables and continue. */
486 if (kcb->kprobe_status == KPROBE_REENTER) {
487 restore_previous_kprobe(kcb);
488 goto out;
489 }
490 reset_current_kprobe();
491out:
492 preempt_enable();
493
494 /*
495 * if somebody else is singlestepping across a probe point, msr
496 * will have DE/SE set, in which case, continue the remaining processing
497 * of do_debug, as if this is not a probe hit.
498 */
499 if (regs->msr & MSR_SINGLESTEP)
500 return 0;
501
502 return 1;
503}
504NOKPROBE_SYMBOL(kprobe_post_handler);
505
506int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
507{
508 struct kprobe *cur = kprobe_running();
509 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
510 const struct exception_table_entry *entry;
511
512 switch(kcb->kprobe_status) {
513 case KPROBE_HIT_SS:
514 case KPROBE_REENTER:
515 /*
516 * We are here because the instruction being single
517 * stepped caused a page fault. We reset the current
518 * kprobe and the nip points back to the probe address
519 * and allow the page fault handler to continue as a
520 * normal page fault.
521 */
522 regs_set_return_ip(regs, (unsigned long)cur->addr);
523 /* Turn off 'trace' bits */
524 regs_set_return_msr(regs,
525 (regs->msr & ~MSR_SINGLESTEP) |
526 kcb->kprobe_saved_msr);
527 if (kcb->kprobe_status == KPROBE_REENTER)
528 restore_previous_kprobe(kcb);
529 else
530 reset_current_kprobe();
531 preempt_enable();
532 break;
533 case KPROBE_HIT_ACTIVE:
534 case KPROBE_HIT_SSDONE:
535 /*
536 * In case the user-specified fault handler returned
537 * zero, try to fix up.
538 */
539 if ((entry = search_exception_tables(regs->nip)) != NULL) {
540 regs_set_return_ip(regs, extable_fixup(entry));
541 return 1;
542 }
543
544 /*
545 * fixup_exception() could not handle it,
546 * Let do_page_fault() fix it.
547 */
548 break;
549 default:
550 break;
551 }
552 return 0;
553}
554NOKPROBE_SYMBOL(kprobe_fault_handler);
555
556static struct kprobe trampoline_p = {
557 .addr = (kprobe_opcode_t *) &__kretprobe_trampoline,
558 .pre_handler = trampoline_probe_handler
559};
560
561int __init arch_init_kprobes(void)
562{
563 return register_kprobe(&trampoline_p);
564}
565
566int arch_trampoline_kprobe(struct kprobe *p)
567{
568 if (p->addr == (kprobe_opcode_t *)&__kretprobe_trampoline)
569 return 1;
570
571 return 0;
572}
573NOKPROBE_SYMBOL(arch_trampoline_kprobe);
1/*
2 * Kernel Probes (KProbes)
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2002, 2004
19 *
20 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
21 * Probes initial implementation ( includes contributions from
22 * Rusty Russell).
23 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
24 * interface to access function arguments.
25 * 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
26 * for PPC64
27 */
28
29#include <linux/kprobes.h>
30#include <linux/ptrace.h>
31#include <linux/preempt.h>
32#include <linux/module.h>
33#include <linux/kdebug.h>
34#include <linux/slab.h>
35#include <asm/cacheflush.h>
36#include <asm/sstep.h>
37#include <asm/uaccess.h>
38
39#ifdef CONFIG_PPC_ADV_DEBUG_REGS
40#define MSR_SINGLESTEP (MSR_DE)
41#else
42#define MSR_SINGLESTEP (MSR_SE)
43#endif
44
45DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
46DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
47
48struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
49
50int __kprobes arch_prepare_kprobe(struct kprobe *p)
51{
52 int ret = 0;
53 kprobe_opcode_t insn = *p->addr;
54
55 if ((unsigned long)p->addr & 0x03) {
56 printk("Attempt to register kprobe at an unaligned address\n");
57 ret = -EINVAL;
58 } else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) {
59 printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n");
60 ret = -EINVAL;
61 }
62
63 /* insn must be on a special executable page on ppc64. This is
64 * not explicitly required on ppc32 (right now), but it doesn't hurt */
65 if (!ret) {
66 p->ainsn.insn = get_insn_slot();
67 if (!p->ainsn.insn)
68 ret = -ENOMEM;
69 }
70
71 if (!ret) {
72 memcpy(p->ainsn.insn, p->addr,
73 MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
74 p->opcode = *p->addr;
75 flush_icache_range((unsigned long)p->ainsn.insn,
76 (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
77 }
78
79 p->ainsn.boostable = 0;
80 return ret;
81}
82
83void __kprobes arch_arm_kprobe(struct kprobe *p)
84{
85 *p->addr = BREAKPOINT_INSTRUCTION;
86 flush_icache_range((unsigned long) p->addr,
87 (unsigned long) p->addr + sizeof(kprobe_opcode_t));
88}
89
90void __kprobes arch_disarm_kprobe(struct kprobe *p)
91{
92 *p->addr = p->opcode;
93 flush_icache_range((unsigned long) p->addr,
94 (unsigned long) p->addr + sizeof(kprobe_opcode_t));
95}
96
97void __kprobes arch_remove_kprobe(struct kprobe *p)
98{
99 if (p->ainsn.insn) {
100 free_insn_slot(p->ainsn.insn, 0);
101 p->ainsn.insn = NULL;
102 }
103}
104
105static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
106{
107 /* We turn off async exceptions to ensure that the single step will
108 * be for the instruction we have the kprobe on, if we dont its
109 * possible we'd get the single step reported for an exception handler
110 * like Decrementer or External Interrupt */
111 regs->msr &= ~MSR_EE;
112 regs->msr |= MSR_SINGLESTEP;
113#ifdef CONFIG_PPC_ADV_DEBUG_REGS
114 regs->msr &= ~MSR_CE;
115 mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
116#ifdef CONFIG_PPC_47x
117 isync();
118#endif
119#endif
120
121 /*
122 * On powerpc we should single step on the original
123 * instruction even if the probed insn is a trap
124 * variant as values in regs could play a part in
125 * if the trap is taken or not
126 */
127 regs->nip = (unsigned long)p->ainsn.insn;
128}
129
130static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
131{
132 kcb->prev_kprobe.kp = kprobe_running();
133 kcb->prev_kprobe.status = kcb->kprobe_status;
134 kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;
135}
136
137static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
138{
139 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
140 kcb->kprobe_status = kcb->prev_kprobe.status;
141 kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;
142}
143
144static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
145 struct kprobe_ctlblk *kcb)
146{
147 __get_cpu_var(current_kprobe) = p;
148 kcb->kprobe_saved_msr = regs->msr;
149}
150
151void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
152 struct pt_regs *regs)
153{
154 ri->ret_addr = (kprobe_opcode_t *)regs->link;
155
156 /* Replace the return addr with trampoline addr */
157 regs->link = (unsigned long)kretprobe_trampoline;
158}
159
160static int __kprobes kprobe_handler(struct pt_regs *regs)
161{
162 struct kprobe *p;
163 int ret = 0;
164 unsigned int *addr = (unsigned int *)regs->nip;
165 struct kprobe_ctlblk *kcb;
166
167 /*
168 * We don't want to be preempted for the entire
169 * duration of kprobe processing
170 */
171 preempt_disable();
172 kcb = get_kprobe_ctlblk();
173
174 /* Check we're not actually recursing */
175 if (kprobe_running()) {
176 p = get_kprobe(addr);
177 if (p) {
178 kprobe_opcode_t insn = *p->ainsn.insn;
179 if (kcb->kprobe_status == KPROBE_HIT_SS &&
180 is_trap(insn)) {
181 /* Turn off 'trace' bits */
182 regs->msr &= ~MSR_SINGLESTEP;
183 regs->msr |= kcb->kprobe_saved_msr;
184 goto no_kprobe;
185 }
186 /* We have reentered the kprobe_handler(), since
187 * another probe was hit while within the handler.
188 * We here save the original kprobes variables and
189 * just single step on the instruction of the new probe
190 * without calling any user handlers.
191 */
192 save_previous_kprobe(kcb);
193 set_current_kprobe(p, regs, kcb);
194 kcb->kprobe_saved_msr = regs->msr;
195 kprobes_inc_nmissed_count(p);
196 prepare_singlestep(p, regs);
197 kcb->kprobe_status = KPROBE_REENTER;
198 return 1;
199 } else {
200 if (*addr != BREAKPOINT_INSTRUCTION) {
201 /* If trap variant, then it belongs not to us */
202 kprobe_opcode_t cur_insn = *addr;
203 if (is_trap(cur_insn))
204 goto no_kprobe;
205 /* The breakpoint instruction was removed by
206 * another cpu right after we hit, no further
207 * handling of this interrupt is appropriate
208 */
209 ret = 1;
210 goto no_kprobe;
211 }
212 p = __get_cpu_var(current_kprobe);
213 if (p->break_handler && p->break_handler(p, regs)) {
214 goto ss_probe;
215 }
216 }
217 goto no_kprobe;
218 }
219
220 p = get_kprobe(addr);
221 if (!p) {
222 if (*addr != BREAKPOINT_INSTRUCTION) {
223 /*
224 * PowerPC has multiple variants of the "trap"
225 * instruction. If the current instruction is a
226 * trap variant, it could belong to someone else
227 */
228 kprobe_opcode_t cur_insn = *addr;
229 if (is_trap(cur_insn))
230 goto no_kprobe;
231 /*
232 * The breakpoint instruction was removed right
233 * after we hit it. Another cpu has removed
234 * either a probepoint or a debugger breakpoint
235 * at this address. In either case, no further
236 * handling of this interrupt is appropriate.
237 */
238 ret = 1;
239 }
240 /* Not one of ours: let kernel handle it */
241 goto no_kprobe;
242 }
243
244 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
245 set_current_kprobe(p, regs, kcb);
246 if (p->pre_handler && p->pre_handler(p, regs))
247 /* handler has already set things up, so skip ss setup */
248 return 1;
249
250ss_probe:
251 if (p->ainsn.boostable >= 0) {
252 unsigned int insn = *p->ainsn.insn;
253
254 /* regs->nip is also adjusted if emulate_step returns 1 */
255 ret = emulate_step(regs, insn);
256 if (ret > 0) {
257 /*
258 * Once this instruction has been boosted
259 * successfully, set the boostable flag
260 */
261 if (unlikely(p->ainsn.boostable == 0))
262 p->ainsn.boostable = 1;
263
264 if (p->post_handler)
265 p->post_handler(p, regs, 0);
266
267 kcb->kprobe_status = KPROBE_HIT_SSDONE;
268 reset_current_kprobe();
269 preempt_enable_no_resched();
270 return 1;
271 } else if (ret < 0) {
272 /*
273 * We don't allow kprobes on mtmsr(d)/rfi(d), etc.
274 * So, we should never get here... but, its still
275 * good to catch them, just in case...
276 */
277 printk("Can't step on instruction %x\n", insn);
278 BUG();
279 } else if (ret == 0)
280 /* This instruction can't be boosted */
281 p->ainsn.boostable = -1;
282 }
283 prepare_singlestep(p, regs);
284 kcb->kprobe_status = KPROBE_HIT_SS;
285 return 1;
286
287no_kprobe:
288 preempt_enable_no_resched();
289 return ret;
290}
291
292/*
293 * Function return probe trampoline:
294 * - init_kprobes() establishes a probepoint here
295 * - When the probed function returns, this probe
296 * causes the handlers to fire
297 */
298static void __used kretprobe_trampoline_holder(void)
299{
300 asm volatile(".global kretprobe_trampoline\n"
301 "kretprobe_trampoline:\n"
302 "nop\n");
303}
304
305/*
306 * Called when the probe at kretprobe trampoline is hit
307 */
308static int __kprobes trampoline_probe_handler(struct kprobe *p,
309 struct pt_regs *regs)
310{
311 struct kretprobe_instance *ri = NULL;
312 struct hlist_head *head, empty_rp;
313 struct hlist_node *node, *tmp;
314 unsigned long flags, orig_ret_address = 0;
315 unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
316
317 INIT_HLIST_HEAD(&empty_rp);
318 kretprobe_hash_lock(current, &head, &flags);
319
320 /*
321 * It is possible to have multiple instances associated with a given
322 * task either because an multiple functions in the call path
323 * have a return probe installed on them, and/or more than one return
324 * return probe was registered for a target function.
325 *
326 * We can handle this because:
327 * - instances are always inserted at the head of the list
328 * - when multiple return probes are registered for the same
329 * function, the first instance's ret_addr will point to the
330 * real return address, and all the rest will point to
331 * kretprobe_trampoline
332 */
333 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
334 if (ri->task != current)
335 /* another task is sharing our hash bucket */
336 continue;
337
338 if (ri->rp && ri->rp->handler)
339 ri->rp->handler(ri, regs);
340
341 orig_ret_address = (unsigned long)ri->ret_addr;
342 recycle_rp_inst(ri, &empty_rp);
343
344 if (orig_ret_address != trampoline_address)
345 /*
346 * This is the real return address. Any other
347 * instances associated with this task are for
348 * other calls deeper on the call stack
349 */
350 break;
351 }
352
353 kretprobe_assert(ri, orig_ret_address, trampoline_address);
354 regs->nip = orig_ret_address;
355
356 reset_current_kprobe();
357 kretprobe_hash_unlock(current, &flags);
358 preempt_enable_no_resched();
359
360 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
361 hlist_del(&ri->hlist);
362 kfree(ri);
363 }
364 /*
365 * By returning a non-zero value, we are telling
366 * kprobe_handler() that we don't want the post_handler
367 * to run (and have re-enabled preemption)
368 */
369 return 1;
370}
371
372/*
373 * Called after single-stepping. p->addr is the address of the
374 * instruction whose first byte has been replaced by the "breakpoint"
375 * instruction. To avoid the SMP problems that can occur when we
376 * temporarily put back the original opcode to single-step, we
377 * single-stepped a copy of the instruction. The address of this
378 * copy is p->ainsn.insn.
379 */
380static int __kprobes post_kprobe_handler(struct pt_regs *regs)
381{
382 struct kprobe *cur = kprobe_running();
383 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
384
385 if (!cur)
386 return 0;
387
388 /* make sure we got here for instruction we have a kprobe on */
389 if (((unsigned long)cur->ainsn.insn + 4) != regs->nip)
390 return 0;
391
392 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
393 kcb->kprobe_status = KPROBE_HIT_SSDONE;
394 cur->post_handler(cur, regs, 0);
395 }
396
397 /* Adjust nip to after the single-stepped instruction */
398 regs->nip = (unsigned long)cur->addr + 4;
399 regs->msr |= kcb->kprobe_saved_msr;
400
401 /*Restore back the original saved kprobes variables and continue. */
402 if (kcb->kprobe_status == KPROBE_REENTER) {
403 restore_previous_kprobe(kcb);
404 goto out;
405 }
406 reset_current_kprobe();
407out:
408 preempt_enable_no_resched();
409
410 /*
411 * if somebody else is singlestepping across a probe point, msr
412 * will have DE/SE set, in which case, continue the remaining processing
413 * of do_debug, as if this is not a probe hit.
414 */
415 if (regs->msr & MSR_SINGLESTEP)
416 return 0;
417
418 return 1;
419}
420
421int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
422{
423 struct kprobe *cur = kprobe_running();
424 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
425 const struct exception_table_entry *entry;
426
427 switch(kcb->kprobe_status) {
428 case KPROBE_HIT_SS:
429 case KPROBE_REENTER:
430 /*
431 * We are here because the instruction being single
432 * stepped caused a page fault. We reset the current
433 * kprobe and the nip points back to the probe address
434 * and allow the page fault handler to continue as a
435 * normal page fault.
436 */
437 regs->nip = (unsigned long)cur->addr;
438 regs->msr &= ~MSR_SINGLESTEP; /* Turn off 'trace' bits */
439 regs->msr |= kcb->kprobe_saved_msr;
440 if (kcb->kprobe_status == KPROBE_REENTER)
441 restore_previous_kprobe(kcb);
442 else
443 reset_current_kprobe();
444 preempt_enable_no_resched();
445 break;
446 case KPROBE_HIT_ACTIVE:
447 case KPROBE_HIT_SSDONE:
448 /*
449 * We increment the nmissed count for accounting,
450 * we can also use npre/npostfault count for accouting
451 * these specific fault cases.
452 */
453 kprobes_inc_nmissed_count(cur);
454
455 /*
456 * We come here because instructions in the pre/post
457 * handler caused the page_fault, this could happen
458 * if handler tries to access user space by
459 * copy_from_user(), get_user() etc. Let the
460 * user-specified handler try to fix it first.
461 */
462 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
463 return 1;
464
465 /*
466 * In case the user-specified fault handler returned
467 * zero, try to fix up.
468 */
469 if ((entry = search_exception_tables(regs->nip)) != NULL) {
470 regs->nip = entry->fixup;
471 return 1;
472 }
473
474 /*
475 * fixup_exception() could not handle it,
476 * Let do_page_fault() fix it.
477 */
478 break;
479 default:
480 break;
481 }
482 return 0;
483}
484
485/*
486 * Wrapper routine to for handling exceptions.
487 */
488int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
489 unsigned long val, void *data)
490{
491 struct die_args *args = (struct die_args *)data;
492 int ret = NOTIFY_DONE;
493
494 if (args->regs && user_mode(args->regs))
495 return ret;
496
497 switch (val) {
498 case DIE_BPT:
499 if (kprobe_handler(args->regs))
500 ret = NOTIFY_STOP;
501 break;
502 case DIE_SSTEP:
503 if (post_kprobe_handler(args->regs))
504 ret = NOTIFY_STOP;
505 break;
506 default:
507 break;
508 }
509 return ret;
510}
511
512#ifdef CONFIG_PPC64
513unsigned long arch_deref_entry_point(void *entry)
514{
515 return ((func_descr_t *)entry)->entry;
516}
517#endif
518
519int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
520{
521 struct jprobe *jp = container_of(p, struct jprobe, kp);
522 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
523
524 memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
525
526 /* setup return addr to the jprobe handler routine */
527 regs->nip = arch_deref_entry_point(jp->entry);
528#ifdef CONFIG_PPC64
529 regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
530#endif
531
532 return 1;
533}
534
535void __used __kprobes jprobe_return(void)
536{
537 asm volatile("trap" ::: "memory");
538}
539
540static void __used __kprobes jprobe_return_end(void)
541{
542};
543
544int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
545{
546 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
547
548 /*
549 * FIXME - we should ideally be validating that we got here 'cos
550 * of the "trap" in jprobe_return() above, before restoring the
551 * saved regs...
552 */
553 memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
554 preempt_enable_no_resched();
555 return 1;
556}
557
558static struct kprobe trampoline_p = {
559 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
560 .pre_handler = trampoline_probe_handler
561};
562
563int __init arch_init_kprobes(void)
564{
565 return register_kprobe(&trampoline_p);
566}
567
568int __kprobes arch_trampoline_kprobe(struct kprobe *p)
569{
570 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
571 return 1;
572
573 return 0;
574}