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#include <linux/spinlock.h>
35#include <linux/kdebug.h>
36#include <linux/string.h>
37#include <linux/kernel.h>
38#include <linux/ptrace.h>
39#include <linux/sched.h>
40#include <linux/delay.h>
41#include <linux/kgdb.h>
42#include <linux/init.h>
43#include <linux/smp.h>
44#include <linux/nmi.h>
45#include <linux/hw_breakpoint.h>
46#include <linux/uaccess.h>
47#include <linux/memory.h>
48
49#include <asm/debugreg.h>
50#include <asm/apicdef.h>
51#include <asm/apic.h>
52#include <asm/nmi.h>
53
54struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
55{
56#ifdef CONFIG_X86_32
57 { "ax", 4, offsetof(struct pt_regs, ax) },
58 { "cx", 4, offsetof(struct pt_regs, cx) },
59 { "dx", 4, offsetof(struct pt_regs, dx) },
60 { "bx", 4, offsetof(struct pt_regs, bx) },
61 { "sp", 4, offsetof(struct pt_regs, sp) },
62 { "bp", 4, offsetof(struct pt_regs, bp) },
63 { "si", 4, offsetof(struct pt_regs, si) },
64 { "di", 4, offsetof(struct pt_regs, di) },
65 { "ip", 4, offsetof(struct pt_regs, ip) },
66 { "flags", 4, offsetof(struct pt_regs, flags) },
67 { "cs", 4, offsetof(struct pt_regs, cs) },
68 { "ss", 4, offsetof(struct pt_regs, ss) },
69 { "ds", 4, offsetof(struct pt_regs, ds) },
70 { "es", 4, offsetof(struct pt_regs, es) },
71#else
72 { "ax", 8, offsetof(struct pt_regs, ax) },
73 { "bx", 8, offsetof(struct pt_regs, bx) },
74 { "cx", 8, offsetof(struct pt_regs, cx) },
75 { "dx", 8, offsetof(struct pt_regs, dx) },
76 { "si", 8, offsetof(struct pt_regs, dx) },
77 { "di", 8, offsetof(struct pt_regs, di) },
78 { "bp", 8, offsetof(struct pt_regs, bp) },
79 { "sp", 8, offsetof(struct pt_regs, sp) },
80 { "r8", 8, offsetof(struct pt_regs, r8) },
81 { "r9", 8, offsetof(struct pt_regs, r9) },
82 { "r10", 8, offsetof(struct pt_regs, r10) },
83 { "r11", 8, offsetof(struct pt_regs, r11) },
84 { "r12", 8, offsetof(struct pt_regs, r12) },
85 { "r13", 8, offsetof(struct pt_regs, r13) },
86 { "r14", 8, offsetof(struct pt_regs, r14) },
87 { "r15", 8, offsetof(struct pt_regs, r15) },
88 { "ip", 8, offsetof(struct pt_regs, ip) },
89 { "flags", 4, offsetof(struct pt_regs, flags) },
90 { "cs", 4, offsetof(struct pt_regs, cs) },
91 { "ss", 4, offsetof(struct pt_regs, ss) },
92 { "ds", 4, -1 },
93 { "es", 4, -1 },
94#endif
95 { "fs", 4, -1 },
96 { "gs", 4, -1 },
97};
98
99int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
100{
101 if (
102#ifdef CONFIG_X86_32
103 regno == GDB_SS || regno == GDB_FS || regno == GDB_GS ||
104#endif
105 regno == GDB_SP || regno == GDB_ORIG_AX)
106 return 0;
107
108 if (dbg_reg_def[regno].offset != -1)
109 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
110 dbg_reg_def[regno].size);
111 return 0;
112}
113
114char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
115{
116 if (regno == GDB_ORIG_AX) {
117 memcpy(mem, ®s->orig_ax, sizeof(regs->orig_ax));
118 return "orig_ax";
119 }
120 if (regno >= DBG_MAX_REG_NUM || regno < 0)
121 return NULL;
122
123 if (dbg_reg_def[regno].offset != -1)
124 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
125 dbg_reg_def[regno].size);
126
127#ifdef CONFIG_X86_32
128 switch (regno) {
129 case GDB_SS:
130 if (!user_mode_vm(regs))
131 *(unsigned long *)mem = __KERNEL_DS;
132 break;
133 case GDB_SP:
134 if (!user_mode_vm(regs))
135 *(unsigned long *)mem = kernel_stack_pointer(regs);
136 break;
137 case GDB_GS:
138 case GDB_FS:
139 *(unsigned long *)mem = 0xFFFF;
140 break;
141 }
142#endif
143 return dbg_reg_def[regno].name;
144}
145
146
147
148
149
150
151
152
153
154
155
156
157
158void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
159{
160#ifndef CONFIG_X86_32
161 u32 *gdb_regs32 = (u32 *)gdb_regs;
162#endif
163 gdb_regs[GDB_AX] = 0;
164 gdb_regs[GDB_BX] = 0;
165 gdb_regs[GDB_CX] = 0;
166 gdb_regs[GDB_DX] = 0;
167 gdb_regs[GDB_SI] = 0;
168 gdb_regs[GDB_DI] = 0;
169 gdb_regs[GDB_BP] = *(unsigned long *)p->thread.sp;
170#ifdef CONFIG_X86_32
171 gdb_regs[GDB_DS] = __KERNEL_DS;
172 gdb_regs[GDB_ES] = __KERNEL_DS;
173 gdb_regs[GDB_PS] = 0;
174 gdb_regs[GDB_CS] = __KERNEL_CS;
175 gdb_regs[GDB_PC] = p->thread.ip;
176 gdb_regs[GDB_SS] = __KERNEL_DS;
177 gdb_regs[GDB_FS] = 0xFFFF;
178 gdb_regs[GDB_GS] = 0xFFFF;
179#else
180 gdb_regs32[GDB_PS] = *(unsigned long *)(p->thread.sp + 8);
181 gdb_regs32[GDB_CS] = __KERNEL_CS;
182 gdb_regs32[GDB_SS] = __KERNEL_DS;
183 gdb_regs[GDB_PC] = 0;
184 gdb_regs[GDB_R8] = 0;
185 gdb_regs[GDB_R9] = 0;
186 gdb_regs[GDB_R10] = 0;
187 gdb_regs[GDB_R11] = 0;
188 gdb_regs[GDB_R12] = 0;
189 gdb_regs[GDB_R13] = 0;
190 gdb_regs[GDB_R14] = 0;
191 gdb_regs[GDB_R15] = 0;
192#endif
193 gdb_regs[GDB_SP] = p->thread.sp;
194}
195
196static struct hw_breakpoint {
197 unsigned enabled;
198 unsigned long addr;
199 int len;
200 int type;
201 struct perf_event * __percpu *pev;
202} breakinfo[HBP_NUM];
203
204static unsigned long early_dr7;
205
206static void kgdb_correct_hw_break(void)
207{
208 int breakno;
209
210 for (breakno = 0; breakno < HBP_NUM; breakno++) {
211 struct perf_event *bp;
212 struct arch_hw_breakpoint *info;
213 int val;
214 int cpu = raw_smp_processor_id();
215 if (!breakinfo[breakno].enabled)
216 continue;
217 if (dbg_is_early) {
218 set_debugreg(breakinfo[breakno].addr, breakno);
219 early_dr7 |= encode_dr7(breakno,
220 breakinfo[breakno].len,
221 breakinfo[breakno].type);
222 set_debugreg(early_dr7, 7);
223 continue;
224 }
225 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
226 info = counter_arch_bp(bp);
227 if (bp->attr.disabled != 1)
228 continue;
229 bp->attr.bp_addr = breakinfo[breakno].addr;
230 bp->attr.bp_len = breakinfo[breakno].len;
231 bp->attr.bp_type = breakinfo[breakno].type;
232 info->address = breakinfo[breakno].addr;
233 info->len = breakinfo[breakno].len;
234 info->type = breakinfo[breakno].type;
235 val = arch_install_hw_breakpoint(bp);
236 if (!val)
237 bp->attr.disabled = 0;
238 }
239 if (!dbg_is_early)
240 hw_breakpoint_restore();
241}
242
243static int hw_break_reserve_slot(int breakno)
244{
245 int cpu;
246 int cnt = 0;
247 struct perf_event **pevent;
248
249 if (dbg_is_early)
250 return 0;
251
252 for_each_online_cpu(cpu) {
253 cnt++;
254 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
255 if (dbg_reserve_bp_slot(*pevent))
256 goto fail;
257 }
258
259 return 0;
260
261fail:
262 for_each_online_cpu(cpu) {
263 cnt--;
264 if (!cnt)
265 break;
266 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
267 dbg_release_bp_slot(*pevent);
268 }
269 return -1;
270}
271
272static int hw_break_release_slot(int breakno)
273{
274 struct perf_event **pevent;
275 int cpu;
276
277 if (dbg_is_early)
278 return 0;
279
280 for_each_online_cpu(cpu) {
281 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
282 if (dbg_release_bp_slot(*pevent))
283
284
285
286
287 return -1;
288 }
289 return 0;
290}
291
292static int
293kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
294{
295 int i;
296
297 for (i = 0; i < HBP_NUM; i++)
298 if (breakinfo[i].addr == addr && breakinfo[i].enabled)
299 break;
300 if (i == HBP_NUM)
301 return -1;
302
303 if (hw_break_release_slot(i)) {
304 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
305 return -1;
306 }
307 breakinfo[i].enabled = 0;
308
309 return 0;
310}
311
312static void kgdb_remove_all_hw_break(void)
313{
314 int i;
315 int cpu = raw_smp_processor_id();
316 struct perf_event *bp;
317
318 for (i = 0; i < HBP_NUM; i++) {
319 if (!breakinfo[i].enabled)
320 continue;
321 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
322 if (!bp->attr.disabled) {
323 arch_uninstall_hw_breakpoint(bp);
324 bp->attr.disabled = 1;
325 continue;
326 }
327 if (dbg_is_early)
328 early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
329 breakinfo[i].type);
330 else if (hw_break_release_slot(i))
331 printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
332 breakinfo[i].addr);
333 breakinfo[i].enabled = 0;
334 }
335}
336
337static int
338kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
339{
340 int i;
341
342 for (i = 0; i < HBP_NUM; i++)
343 if (!breakinfo[i].enabled)
344 break;
345 if (i == HBP_NUM)
346 return -1;
347
348 switch (bptype) {
349 case BP_HARDWARE_BREAKPOINT:
350 len = 1;
351 breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
352 break;
353 case BP_WRITE_WATCHPOINT:
354 breakinfo[i].type = X86_BREAKPOINT_WRITE;
355 break;
356 case BP_ACCESS_WATCHPOINT:
357 breakinfo[i].type = X86_BREAKPOINT_RW;
358 break;
359 default:
360 return -1;
361 }
362 switch (len) {
363 case 1:
364 breakinfo[i].len = X86_BREAKPOINT_LEN_1;
365 break;
366 case 2:
367 breakinfo[i].len = X86_BREAKPOINT_LEN_2;
368 break;
369 case 4:
370 breakinfo[i].len = X86_BREAKPOINT_LEN_4;
371 break;
372#ifdef CONFIG_X86_64
373 case 8:
374 breakinfo[i].len = X86_BREAKPOINT_LEN_8;
375 break;
376#endif
377 default:
378 return -1;
379 }
380 breakinfo[i].addr = addr;
381 if (hw_break_reserve_slot(i)) {
382 breakinfo[i].addr = 0;
383 return -1;
384 }
385 breakinfo[i].enabled = 1;
386
387 return 0;
388}
389
390
391
392
393
394
395
396
397
398static void kgdb_disable_hw_debug(struct pt_regs *regs)
399{
400 int i;
401 int cpu = raw_smp_processor_id();
402 struct perf_event *bp;
403
404
405 set_debugreg(0UL, 7);
406 for (i = 0; i < HBP_NUM; i++) {
407 if (!breakinfo[i].enabled)
408 continue;
409 if (dbg_is_early) {
410 early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
411 breakinfo[i].type);
412 continue;
413 }
414 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
415 if (bp->attr.disabled == 1)
416 continue;
417 arch_uninstall_hw_breakpoint(bp);
418 bp->attr.disabled = 1;
419 }
420}
421
422#ifdef CONFIG_SMP
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439void kgdb_roundup_cpus(unsigned long flags)
440{
441 apic->send_IPI_allbutself(APIC_DM_NMI);
442}
443#endif
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
462 char *remcomInBuffer, char *remcomOutBuffer,
463 struct pt_regs *linux_regs)
464{
465 unsigned long addr;
466 char *ptr;
467
468 switch (remcomInBuffer[0]) {
469 case 'c':
470 case 's':
471
472 ptr = &remcomInBuffer[1];
473 if (kgdb_hex2long(&ptr, &addr))
474 linux_regs->ip = addr;
475 case 'D':
476 case 'k':
477
478 linux_regs->flags &= ~X86_EFLAGS_TF;
479 atomic_set(&kgdb_cpu_doing_single_step, -1);
480
481
482 if (remcomInBuffer[0] == 's') {
483 linux_regs->flags |= X86_EFLAGS_TF;
484 atomic_set(&kgdb_cpu_doing_single_step,
485 raw_smp_processor_id());
486 }
487
488 return 0;
489 }
490
491
492 return -1;
493}
494
495static inline int
496single_step_cont(struct pt_regs *regs, struct die_args *args)
497{
498
499
500
501
502 printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
503 "resuming...\n");
504 kgdb_arch_handle_exception(args->trapnr, args->signr,
505 args->err, "c", "", regs);
506
507
508
509
510 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
511
512 return NOTIFY_STOP;
513}
514
515static int was_in_debug_nmi[NR_CPUS];
516
517static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs)
518{
519 switch (cmd) {
520 case NMI_LOCAL:
521 if (atomic_read(&kgdb_active) != -1) {
522
523 kgdb_nmicallback(raw_smp_processor_id(), regs);
524 was_in_debug_nmi[raw_smp_processor_id()] = 1;
525 touch_nmi_watchdog();
526 return NMI_HANDLED;
527 }
528 break;
529
530 case NMI_UNKNOWN:
531 if (was_in_debug_nmi[raw_smp_processor_id()]) {
532 was_in_debug_nmi[raw_smp_processor_id()] = 0;
533 return NMI_HANDLED;
534 }
535 break;
536 default:
537
538 break;
539 }
540 return NMI_DONE;
541}
542
543static int __kgdb_notify(struct die_args *args, unsigned long cmd)
544{
545 struct pt_regs *regs = args->regs;
546
547 switch (cmd) {
548 case DIE_DEBUG:
549 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
550 if (user_mode(regs))
551 return single_step_cont(regs, args);
552 break;
553 } else if (test_thread_flag(TIF_SINGLESTEP))
554
555
556
557 return NOTIFY_DONE;
558
559 default:
560 if (user_mode(regs))
561 return NOTIFY_DONE;
562 }
563
564 if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
565 return NOTIFY_DONE;
566
567
568 touch_nmi_watchdog();
569 return NOTIFY_STOP;
570}
571
572int kgdb_ll_trap(int cmd, const char *str,
573 struct pt_regs *regs, long err, int trap, int sig)
574{
575 struct die_args args = {
576 .regs = regs,
577 .str = str,
578 .err = err,
579 .trapnr = trap,
580 .signr = sig,
581
582 };
583
584 if (!kgdb_io_module_registered)
585 return NOTIFY_DONE;
586
587 return __kgdb_notify(&args, cmd);
588}
589
590static int
591kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
592{
593 unsigned long flags;
594 int ret;
595
596 local_irq_save(flags);
597 ret = __kgdb_notify(ptr, cmd);
598 local_irq_restore(flags);
599
600 return ret;
601}
602
603static struct notifier_block kgdb_notifier = {
604 .notifier_call = kgdb_notify,
605};
606
607
608
609
610
611
612
613int kgdb_arch_init(void)
614{
615 int retval;
616
617 retval = register_die_notifier(&kgdb_notifier);
618 if (retval)
619 goto out;
620
621 retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler,
622 0, "kgdb");
623 if (retval)
624 goto out1;
625
626 retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler,
627 0, "kgdb");
628
629 if (retval)
630 goto out2;
631
632 return retval;
633
634out2:
635 unregister_nmi_handler(NMI_LOCAL, "kgdb");
636out1:
637 unregister_die_notifier(&kgdb_notifier);
638out:
639 return retval;
640}
641
642static void kgdb_hw_overflow_handler(struct perf_event *event,
643 struct perf_sample_data *data, struct pt_regs *regs)
644{
645 struct task_struct *tsk = current;
646 int i;
647
648 for (i = 0; i < 4; i++)
649 if (breakinfo[i].enabled)
650 tsk->thread.debugreg6 |= (DR_TRAP0 << i);
651}
652
653void kgdb_arch_late(void)
654{
655 int i, cpu;
656 struct perf_event_attr attr;
657 struct perf_event **pevent;
658
659
660
661
662
663
664 hw_breakpoint_init(&attr);
665 attr.bp_addr = (unsigned long)kgdb_arch_init;
666 attr.bp_len = HW_BREAKPOINT_LEN_1;
667 attr.bp_type = HW_BREAKPOINT_W;
668 attr.disabled = 1;
669 for (i = 0; i < HBP_NUM; i++) {
670 if (breakinfo[i].pev)
671 continue;
672 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL);
673 if (IS_ERR((void * __force)breakinfo[i].pev)) {
674 printk(KERN_ERR "kgdb: Could not allocate hw"
675 "breakpoints\nDisabling the kernel debugger\n");
676 breakinfo[i].pev = NULL;
677 kgdb_arch_exit();
678 return;
679 }
680 for_each_online_cpu(cpu) {
681 pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
682 pevent[0]->hw.sample_period = 1;
683 pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
684 if (pevent[0]->destroy != NULL) {
685 pevent[0]->destroy = NULL;
686 release_bp_slot(*pevent);
687 }
688 }
689 }
690}
691
692
693
694
695
696
697
698void kgdb_arch_exit(void)
699{
700 int i;
701 for (i = 0; i < 4; i++) {
702 if (breakinfo[i].pev) {
703 unregister_wide_hw_breakpoint(breakinfo[i].pev);
704 breakinfo[i].pev = NULL;
705 }
706 }
707 unregister_nmi_handler(NMI_UNKNOWN, "kgdb");
708 unregister_nmi_handler(NMI_LOCAL, "kgdb");
709 unregister_die_notifier(&kgdb_notifier);
710}
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725int kgdb_skipexception(int exception, struct pt_regs *regs)
726{
727 if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
728 regs->ip -= 1;
729 return 1;
730 }
731 return 0;
732}
733
734unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
735{
736 if (exception == 3)
737 return instruction_pointer(regs) - 1;
738 return instruction_pointer(regs);
739}
740
741void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
742{
743 regs->ip = ip;
744}
745
746int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
747{
748 int err;
749#ifdef CONFIG_DEBUG_RODATA
750 char opc[BREAK_INSTR_SIZE];
751#endif
752
753 bpt->type = BP_BREAKPOINT;
754 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
755 BREAK_INSTR_SIZE);
756 if (err)
757 return err;
758 err = probe_kernel_write((char *)bpt->bpt_addr,
759 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
760#ifdef CONFIG_DEBUG_RODATA
761 if (!err)
762 return err;
763
764
765
766
767 if (mutex_is_locked(&text_mutex))
768 return -EBUSY;
769 text_poke((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
770 BREAK_INSTR_SIZE);
771 err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
772 if (err)
773 return err;
774 if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
775 return -EINVAL;
776 bpt->type = BP_POKE_BREAKPOINT;
777#endif
778 return err;
779}
780
781int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
782{
783#ifdef CONFIG_DEBUG_RODATA
784 int err;
785 char opc[BREAK_INSTR_SIZE];
786
787 if (bpt->type != BP_POKE_BREAKPOINT)
788 goto knl_write;
789
790
791
792
793 if (mutex_is_locked(&text_mutex))
794 goto knl_write;
795 text_poke((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE);
796 err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
797 if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
798 goto knl_write;
799 return err;
800knl_write:
801#endif
802 return probe_kernel_write((char *)bpt->bpt_addr,
803 (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
804}
805
806struct kgdb_arch arch_kgdb_ops = {
807
808 .gdb_bpt_instr = { 0xcc },
809 .flags = KGDB_HW_BREAKPOINT,
810 .set_hw_breakpoint = kgdb_set_hw_break,
811 .remove_hw_breakpoint = kgdb_remove_hw_break,
812 .disable_hw_break = kgdb_disable_hw_debug,
813 .remove_all_hw_break = kgdb_remove_all_hw_break,
814 .correct_hw_break = kgdb_correct_hw_break,
815};
816