kgdb.c 14.9 KB
Newer Older
I
Ingo Molnar 已提交
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
/*
 * 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>
J
Jason Wessel 已提交
44
#include <linux/nmi.h>
I
Ingo Molnar 已提交
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

#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
}

J
Jason Wessel 已提交
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
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);
}

I
Ingo Molnar 已提交
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
/**
 *	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;
J
Jason Wessel 已提交
362
	unsigned long dr6;
I
Ingo Molnar 已提交
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
	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());
			}
		}

J
Jason Wessel 已提交
389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404
		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();

I
Ingo Molnar 已提交
405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426
		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;
}

J
Jason Wessel 已提交
427 428
static int was_in_debug_nmi[NR_CPUS];

I
Ingo Molnar 已提交
429 430 431 432 433 434 435 436 437
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);
J
Jason Wessel 已提交
438 439
			was_in_debug_nmi[raw_smp_processor_id()] = 1;
			touch_nmi_watchdog();
I
Ingo Molnar 已提交
440 441 442 443 444 445
			return NOTIFY_STOP;
		}
		return NOTIFY_DONE;

	case DIE_NMI_IPI:
		if (atomic_read(&kgdb_active) != -1) {
J
Jason Wessel 已提交
446 447 448 449 450 451 452 453 454 455
			/* 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;
I
Ingo Molnar 已提交
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
			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 },
J
Jason Wessel 已提交
562 563 564 565 566
	.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,
I
Ingo Molnar 已提交
567
};