aboutsummaryrefslogtreecommitdiff
path: root/arch/x86/kernel/kgdb.c
blob: 7d651adcb22273467fd54a07cc47d91bd2ca1c40 (plain)
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
/*
 * 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, 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.
 *
 */

/*
 * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com>
 * Copyright (C) 2000-2001 VERITAS Software Corporation.
 * Copyright (C) 2002 Andi Kleen, SuSE Labs
 * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
 * Copyright (C) 2007 MontaVista Software, Inc.
 * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc.
 */
/****************************************************************************
 *  Contributor:     Lake Stevens Instrument Division$
 *  Written by:      Glenn Engel $
 *  Updated by:	     Amit Kale<akale@veritas.com>
 *  Updated by:	     Tom Rini <trini@kernel.crashing.org>
 *  Updated by:	     Jason Wessel <jason.wessel@windriver.com>
 *  Modified for 386 by Jim Kingdon, Cygnus Support.
 *  Origianl kgdb, compatibility with 2.1.xx kernel by
 *  David Grothe <dave@gcom.com>
 *  Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
 *  X86_64 changes from Andi Kleen's patch merged by Jim Houston
 */
#include <linux/spinlock.h>
#include <linux/kdebug.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/kgdb.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/nmi.h>

#include <asm/apicdef.h>
#include <asm/system.h>

#ifdef CONFIG_X86_32
# include <mach_ipi.h>
#else
# include <asm/mach_apic.h>
#endif

/*
 * Put the error code here just in case the user cares:
 */
static int gdb_x86errcode;

/*
 * Likewise, the vector number here (since GDB only gets the signal
 * number through the usual means, and that's not very specific):
 */
static int gdb_x86vector = -1;

/**
 *	pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
 *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
 *	@regs: The &struct pt_regs of the current process.
 *
 *	Convert the pt_regs in @regs into the format for registers that
 *	GDB expects, stored in @gdb_regs.
 */
void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
	gdb_regs[GDB_AX]	= regs->ax;
	gdb_regs[GDB_BX]	= regs->bx;
	gdb_regs[GDB_CX]	= regs->cx;
	gdb_regs[GDB_DX]	= regs->dx;
	gdb_regs[GDB_SI]	= regs->si;
	gdb_regs[GDB_DI]	= regs->di;
	gdb_regs[GDB_BP]	= regs->bp;
	gdb_regs[GDB_PS]	= regs->flags;
	gdb_regs[GDB_PC]	= regs->ip;
#ifdef CONFIG_X86_32
	gdb_regs[GDB_DS]	= regs->ds;
	gdb_regs[GDB_ES]	= regs->es;
	gdb_regs[GDB_CS]	= regs->cs;
	gdb_regs[GDB_SS]	= __KERNEL_DS;
	gdb_regs[GDB_FS]	= 0xFFFF;
	gdb_regs[GDB_GS]	= 0xFFFF;
#else
	gdb_regs[GDB_R8]	= regs->r8;
	gdb_regs[GDB_R9]	= regs->r9;
	gdb_regs[GDB_R10]	= regs->r10;
	gdb_regs[GDB_R11]	= regs->r11;
	gdb_regs[GDB_R12]	= regs->r12;
	gdb_regs[GDB_R13]	= regs->r13;
	gdb_regs[GDB_R14]	= regs->r14;
	gdb_regs[GDB_R15]	= regs->r15;
#endif
	gdb_regs[GDB_SP]	= regs->sp;
}

/**
 *	sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
 *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
 *	@p: The &struct task_struct of the desired process.
 *
 *	Convert the register values of the sleeping process in @p to
 *	the format that GDB expects.
 *	This function is called when kgdb does not have access to the
 *	&struct pt_regs and therefore it should fill the gdb registers
 *	@gdb_regs with what has	been saved in &struct thread_struct
 *	thread field during switch_to.
 */
void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
	gdb_regs[GDB_AX]	= 0;
	gdb_regs[GDB_BX]	= 0;
	gdb_regs[GDB_CX]	= 0;
	gdb_regs[GDB_DX]	= 0;
	gdb_regs[GDB_SI]	= 0;
	gdb_regs[GDB_DI]	= 0;
	gdb_regs[GDB_BP]	= *(unsigned long *)p->thread.sp;
#ifdef CONFIG_X86_32
	gdb_regs[GDB_DS]	= __KERNEL_DS;
	gdb_regs[GDB_ES]	= __KERNEL_DS;
	gdb_regs[GDB_PS]	= 0;
	gdb_regs[GDB_CS]	= __KERNEL_CS;
	gdb_regs[GDB_PC]	= p->thread.ip;
	gdb_regs[GDB_SS]	= __KERNEL_DS;
	gdb_regs[GDB_FS]	= 0xFFFF;
	gdb_regs[GDB_GS]	= 0xFFFF;
#else
	gdb_regs[GDB_PS]	= *(unsigned long *)(p->thread.sp + 8);
	gdb_regs[GDB_PC]	= 0;
	gdb_regs[GDB_R8]	= 0;
	gdb_regs[GDB_R9]	= 0;
	gdb_regs[GDB_R10]	= 0;
	gdb_regs[GDB_R11]	= 0;
	gdb_regs[GDB_R12]	= 0;
	gdb_regs[GDB_R13]	= 0;
	gdb_regs[GDB_R14]	= 0;
	gdb_regs[GDB_R15]	= 0;
#endif
	gdb_regs[GDB_SP]	= p->thread.sp;
}

/**
 *	gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
 *	@gdb_regs: A pointer to hold the registers we've received from GDB.
 *	@regs: A pointer to a &struct pt_regs to hold these values in.
 *
 *	Convert the GDB regs in @gdb_regs into the pt_regs, and store them
 *	in @regs.
 */
void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
	regs->ax		= gdb_regs[GDB_AX];
	regs->bx		= gdb_regs[GDB_BX];
	regs->cx		= gdb_regs[GDB_CX];
	regs->dx		= gdb_regs[GDB_DX];
	regs->si		= gdb_regs[GDB_SI];
	regs->di		= gdb_regs[GDB_DI];
	regs->bp		= gdb_regs[GDB_BP];
	regs->flags		= gdb_regs[GDB_PS];
	regs->ip		= gdb_regs[GDB_PC];
#ifdef CONFIG_X86_32
	regs->ds		= gdb_regs[GDB_DS];
	regs->es		= gdb_regs[GDB_ES];
	regs->cs		= gdb_regs[GDB_CS];
#else
	regs->r8		= gdb_regs[GDB_R8];
	regs->r9		= gdb_regs[GDB_R9];
	regs->r10		= gdb_regs[GDB_R10];
	regs->r11		= gdb_regs[GDB_R11];
	regs->r12		= gdb_regs[GDB_R12];
	regs->r13		= gdb_regs[GDB_R13];
	regs->r14		= gdb_regs[GDB_R14];
	regs->r15		= gdb_regs[GDB_R15];
#endif
}

static struct hw_breakpoint {
	unsigned		enabled;
	unsigned		type;
	unsigned		len;
	unsigned long		addr;
} breakinfo[4];

static void kgdb_correct_hw_break(void)
{
	unsigned long dr7;
	int correctit = 0;
	int breakbit;
	int breakno;

	get_debugreg(dr7, 7);
	for (breakno = 0; breakno < 4; breakno++) {
		breakbit = 2 << (breakno << 1);
		if (!(dr7 & breakbit) && breakinfo[breakno].enabled) {
			correctit = 1;
			dr7 |= breakbit;
			dr7 &= ~(0xf0000 << (breakno << 2));
			dr7 |= ((breakinfo[breakno].len << 2) |
				 breakinfo[breakno].type) <<
			       ((breakno << 2) + 16);
			if (breakno >= 0 && breakno <= 3)
				set_debugreg(breakinfo[breakno].addr, breakno);

		} else {
			if ((dr7 & breakbit) && !breakinfo[breakno].enabled) {
				correctit = 1;
				dr7 &= ~breakbit;
				dr7 &= ~(0xf0000 << (breakno << 2));
			}
		}
	}
	if (correctit)
		set_debugreg(dr7, 7);
}

static int
kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
{
	int i;

	for (i = 0; i < 4; i++)
		if (breakinfo[i].addr == addr && breakinfo[i].enabled)
			break;
	if (i == 4)
		return -1;

	breakinfo[i].enabled = 0;

	return 0;
}

static void kgdb_remove_all_hw_break(void)
{
	int i;

	for (i = 0; i < 4; i++)
		memset(&breakinfo[i], 0, sizeof(struct hw_breakpoint));
}

static int
kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
{
	unsigned type;
	int i;

	for (i = 0; i < 4; i++)
		if (!breakinfo[i].enabled)
			break;
	if (i == 4)
		return -1;

	switch (bptype) {
	case BP_HARDWARE_BREAKPOINT:
		type = 0;
		len  = 1;
		break;
	case BP_WRITE_WATCHPOINT:
		type = 1;
		break;
	case BP_ACCESS_WATCHPOINT:
		type = 3;
		break;
	default:
		return -1;
	}

	if (len == 1 || len == 2 || len == 4)
		breakinfo[i].len  = len - 1;
	else
		return -1;

	breakinfo[i].enabled = 1;
	breakinfo[i].addr = addr;
	breakinfo[i].type = type;

	return 0;
}

/**
 *	kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
 *	@regs: Current &struct pt_regs.
 *
 *	This function will be called if the particular architecture must
 *	disable hardware debugging while it is processing gdb packets or
 *	handling exception.
 */
void kgdb_disable_hw_debug(struct pt_regs *regs)
{
	/* Disable hardware debugging while we are in kgdb: */
	set_debugreg(0UL, 7);
}

/**
 *	kgdb_post_primary_code - Save error vector/code numbers.
 *	@regs: Original pt_regs.
 *	@e_vector: Original error vector.
 *	@err_code: Original error code.
 *
 *	This is needed on architectures which support SMP and KGDB.
 *	This function is called after all the slave cpus have been put
 *	to a know spin state and the primary CPU has control over KGDB.
 */
void kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
{
	/* primary processor is completely in the debugger */
	gdb_x86vector = e_vector;
	gdb_x86errcode = err_code;
}

#ifdef CONFIG_SMP
/**
 *	kgdb_roundup_cpus - Get other CPUs into a holding pattern
 *	@flags: Current IRQ state
 *
 *	On SMP systems, we need to get the attention of the other CPUs
 *	and get them be in a known state.  This should do what is needed
 *	to get the other CPUs to call kgdb_wait(). Note that on some arches,
 *	the NMI approach is not used for rounding up all the CPUs. For example,
 *	in case of MIPS, smp_call_function() is used to roundup CPUs. In
 *	this case, we have to make sure that interrupts are enabled before
 *	calling smp_call_function(). The argument to this function is
 *	the flags that will be used when restoring the interrupts. There is
 *	local_irq_save() call before kgdb_roundup_cpus().
 *
 *	On non-SMP systems, this is not called.
 */
void kgdb_roundup_cpus(unsigned long flags)
{
	send_IPI_allbutself(APIC_DM_NMI);
}
#endif

/**
 *	kgdb_arch_handle_exception - Handle architecture specific GDB packets.
 *	@vector: The error vector of the exception that happened.
 *	@signo: The signal number of the exception that happened.
 *	@err_code: The error code of the exception that happened.
 *	@remcom_in_buffer: The buffer of the packet we have read.
 *	@remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
 *	@regs: The &struct pt_regs of the current process.
 *
 *	This function MUST handle the 'c' and 's' command packets,
 *	as well packets to set / remove a hardware breakpoint, if used.
 *	If there are additional packets which the hardware needs to handle,
 *	they are handled here.  The code should return -1 if it wants to
 *	process more packets, and a %0 or %1 if it wants to exit from the
 *	kgdb callback.
 */
int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
			       char *remcomInBuffer, char *remcomOutBuffer,
			       struct pt_regs *linux_regs)
{
	unsigned long addr;
	unsigned long dr6;
	char *ptr;
	int newPC;

	switch (remcomInBuffer[0]) {
	case 'c':
	case 's':
		/* try to read optional parameter, pc unchanged if no parm */
		ptr = &remcomInBuffer[1];
		if (kgdb_hex2long(&ptr, &addr))
			linux_regs->ip = addr;
		newPC = linux_regs->ip;

		/* clear the trace bit */
		linux_regs->flags &= ~TF_MASK;
		atomic_set(&kgdb_cpu_doing_single_step, -1);

		/* set the trace bit if we're stepping */
		if (remcomInBuffer[0] == 's') {
			linux_regs->flags |= TF_MASK;
			kgdb_single_step = 1;
			if (kgdb_contthread) {
				atomic_set(&kgdb_cpu_doing_single_step,
					   raw_smp_processor_id());
			}
		}

		get_debugreg(dr6, 6);
		if (!(dr6 & 0x4000)) {
			int breakno;

			for (breakno = 0; breakno < 4; breakno++) {
				if (dr6 & (1 << breakno) &&
				    breakinfo[breakno].type == 0) {
					/* Set restore flag: */
					linux_regs->flags |= X86_EFLAGS_RF;
					break;
				}
			}
		}
		set_debugreg(0UL, 6);
		kgdb_correct_hw_break();

		return 0;
	}

	/* this means that we do not want to exit from the handler: */
	return -1;
}

static inline int
single_step_cont(struct pt_regs *regs, struct die_args *args)
{
	/*
	 * Single step exception from kernel space to user space so
	 * eat the exception and continue the process:
	 */
	printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
			"resuming...\n");
	kgdb_arch_handle_exception(args->trapnr, args->signr,
				   args->err, "c", "", regs);

	return NOTIFY_STOP;
}

static int was_in_debug_nmi[NR_CPUS];

static int __kgdb_notify(struct die_args *args, unsigned long cmd)
{
	struct pt_regs *regs = args->regs;

	switch (cmd) {
	case DIE_NMI:
		if (atomic_read(&kgdb_active) != -1) {
			/* KGDB CPU roundup */
			kgdb_nmicallback(raw_smp_processor_id(), regs);
			was_in_debug_nmi[raw_smp_processor_id()] = 1;
			touch_nmi_watchdog();
			return NOTIFY_STOP;
		}
		return NOTIFY_DONE;

	case DIE_NMI_IPI:
		if (atomic_read(&kgdb_active) != -1) {
			/* KGDB CPU roundup */
			kgdb_nmicallback(raw_smp_processor_id(), regs);
			was_in_debug_nmi[raw_smp_processor_id()] = 1;
			touch_nmi_watchdog();
		}
		return NOTIFY_DONE;

	case DIE_NMIUNKNOWN:
		if (was_in_debug_nmi[raw_smp_processor_id()]) {
			was_in_debug_nmi[raw_smp_processor_id()] = 0;
			return NOTIFY_STOP;
		}
		return NOTIFY_DONE;

	case DIE_NMIWATCHDOG:
		if (atomic_read(&kgdb_active) != -1) {
			/* KGDB CPU roundup: */
			kgdb_nmicallback(raw_smp_processor_id(), regs);
			return NOTIFY_STOP;
		}
		/* Enter debugger: */
		break;

	case DIE_DEBUG:
		if (atomic_read(&kgdb_cpu_doing_single_step) ==
			raw_smp_processor_id() &&
			user_mode(regs))
			return single_step_cont(regs, args);
		/* fall through */
	default:
		if (user_mode(regs))
			return NOTIFY_DONE;
	}

	if (kgdb_handle_exception(args->trapnr, args->signr, args->err, regs))
		return NOTIFY_DONE;

	return NOTIFY_STOP;
}

static int
kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
{
	unsigned long flags;
	int ret;

	local_irq_save(flags);
	ret = __kgdb_notify(ptr, cmd);
	local_irq_restore(flags);

	return ret;
}

static struct notifier_block kgdb_notifier = {
	.notifier_call	= kgdb_notify,

	/*
	 * Lowest-prio notifier priority, we want to be notified last:
	 */
	.priority	= -INT_MAX,
};

/**
 *	kgdb_arch_init - Perform any architecture specific initalization.
 *
 *	This function will handle the initalization of any architecture
 *	specific callbacks.
 */
int kgdb_arch_init(void)
{
	return register_die_notifier(&kgdb_notifier);
}

/**
 *	kgdb_arch_exit - Perform any architecture specific uninitalization.
 *
 *	This function will handle the uninitalization of any architecture
 *	specific callbacks, for dynamic registration and unregistration.
 */
void kgdb_arch_exit(void)
{
	unregister_die_notifier(&kgdb_notifier);
}

/**
 *
 *	kgdb_skipexception - Bail out of KGDB when we've been triggered.
 *	@exception: Exception vector number
 *	@regs: Current &struct pt_regs.
 *
 *	On some architectures we need to skip a breakpoint exception when
 *	it occurs after a breakpoint has been removed.
 *
 * Skip an int3 exception when it occurs after a breakpoint has been
 * removed. Backtrack eip by 1 since the int3 would have caused it to
 * increment by 1.
 */
int kgdb_skipexception(int exception, struct pt_regs *regs)
{
	if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
		regs->ip -= 1;
		return 1;
	}
	return 0;
}

unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
{
	if (exception == 3)
		return instruction_pointer(regs) - 1;
	return instruction_pointer(regs);
}

struct kgdb_arch arch_kgdb_ops = {
	/* Breakpoint instruction: */
	.gdb_bpt_instr		= { 0xcc },
	.flags			= KGDB_HW_BREAKPOINT,
	.set_hw_breakpoint	= kgdb_set_hw_break,
	.remove_hw_breakpoint	= kgdb_remove_hw_break,
	.remove_all_hw_break	= kgdb_remove_all_hw_break,
	.correct_hw_break	= kgdb_correct_hw_break,
};