[linux-2.6-block.git] / arch / x86 / kernel / dumpstack_64.c

/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
 */
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/kexec.h>
#include <linux/sysfs.h>
#include <linux/bug.h>
#include <linux/nmi.h>

#include <asm/stacktrace.h>


#define N_EXCEPTION_STACKS_END \
		(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)

static char x86_stack_ids[][8] = {
		[ DEBUG_STACK-1			]	= "#DB",
		[ NMI_STACK-1			]	= "NMI",
		[ DOUBLEFAULT_STACK-1		]	= "#DF",
		[ MCE_STACK-1			]	= "#MC",
#if DEBUG_STKSZ > EXCEPTION_STKSZ
		[ N_EXCEPTION_STACKS ...
		  N_EXCEPTION_STACKS_END	]	= "#DB[?]"
#endif
};

static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
					 unsigned *usedp, char **idp)
{
	unsigned k;

	/*
	 * Iterate over all exception stacks, and figure out whether
	 * 'stack' is in one of them:
	 */
	for (k = 0; k < N_EXCEPTION_STACKS; k++) {
		unsigned long end = per_cpu(orig_ist, cpu).ist[k];
		/*
		 * Is 'stack' above this exception frame's end?
		 * If yes then skip to the next frame.
		 */
		if (stack >= end)
			continue;
		/*
		 * Is 'stack' above this exception frame's start address?
		 * If yes then we found the right frame.
		 */
		if (stack >= end - EXCEPTION_STKSZ) {
			/*
			 * Make sure we only iterate through an exception
			 * stack once. If it comes up for the second time
			 * then there's something wrong going on - just
			 * break out and return NULL:
			 */
			if (*usedp & (1U << k))
				break;
			*usedp |= 1U << k;
			*idp = x86_stack_ids[k];
			return (unsigned long *)end;
		}
		/*
		 * If this is a debug stack, and if it has a larger size than
		 * the usual exception stacks, then 'stack' might still
		 * be within the lower portion of the debug stack:
		 */
#if DEBUG_STKSZ > EXCEPTION_STKSZ
		if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
			unsigned j = N_EXCEPTION_STACKS - 1;

			/*
			 * Black magic. A large debug stack is composed of
			 * multiple exception stack entries, which we
			 * iterate through now. Dont look:
			 */
			do {
				++j;
				end -= EXCEPTION_STKSZ;
				x86_stack_ids[j][4] = '1' +
						(j - N_EXCEPTION_STACKS);
			} while (stack < end - EXCEPTION_STKSZ);
			if (*usedp & (1U << j))
				break;
			*usedp |= 1U << j;
			*idp = x86_stack_ids[j];
			return (unsigned long *)end;
		}
#endif
	}
	return NULL;
}

static inline int
in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
	     unsigned long *irq_stack_end)
{
	return (stack >= irq_stack && stack < irq_stack_end);
}

static const unsigned long irq_stack_size =
	(IRQ_STACK_SIZE - 64) / sizeof(unsigned long);

enum stack_type {
	STACK_IS_UNKNOWN,
	STACK_IS_NORMAL,
	STACK_IS_EXCEPTION,
	STACK_IS_IRQ,
};

static enum stack_type
analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
	      unsigned long **stack_end, unsigned long *irq_stack,
	      unsigned *used, char **id)
{
	unsigned long addr;

	addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));
	if ((unsigned long)task_stack_page(task) == addr)
		return STACK_IS_NORMAL;

	*stack_end = in_exception_stack(cpu, (unsigned long)stack,
					used, id);
	if (*stack_end)
		return STACK_IS_EXCEPTION;

	if (!irq_stack)
		return STACK_IS_NORMAL;

	*stack_end = irq_stack;
	irq_stack = irq_stack - irq_stack_size;

	if (in_irq_stack(stack, irq_stack, *stack_end))
		return STACK_IS_IRQ;

	return STACK_IS_UNKNOWN;
}

/*
 * x86-64 can have up to three kernel stacks:
 * process stack
 * interrupt stack
 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 */

void dump_trace(struct task_struct *task, struct pt_regs *regs,
		unsigned long *stack, unsigned long bp,
		const struct stacktrace_ops *ops, void *data)
{
	const unsigned cpu = get_cpu();
	unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
	unsigned long dummy;
	unsigned used = 0;
	int graph = 0;
	int done = 0;

	if (!task)
		task = current;

	if (!stack) {
		if (regs)
			stack = (unsigned long *)regs->sp;
		else if (task != current)
			stack = (unsigned long *)task->thread.sp;
		else
			stack = &dummy;
	}

	if (!bp)
		bp = stack_frame(task, regs);
	/*
	 * Print function call entries in all stacks, starting at the
	 * current stack address. If the stacks consist of nested
	 * exceptions
	 */
	while (!done) {
		unsigned long *stack_end;
		enum stack_type stype;
		char *id;

		stype = analyze_stack(cpu, task, stack, &stack_end,
				      irq_stack, &used, &id);

		/* Default finish unless specified to continue */
		done = 1;

		switch (stype) {

		/* Break out early if we are on the thread stack */
		case STACK_IS_NORMAL:
			break;

		case STACK_IS_EXCEPTION:

			if (ops->stack(data, id) < 0)
				break;

			bp = ops->walk_stack(task, stack, bp, ops,
					     data, stack_end, &graph);
			ops->stack(data, "<EOE>");
			/*
			 * We link to the next stack via the
			 * second-to-last pointer (index -2 to end) in the
			 * exception stack:
			 */
			stack = (unsigned long *) stack_end[-2];
			done = 0;
			break;

		case STACK_IS_IRQ:

			if (ops->stack(data, "IRQ") < 0)
				break;
			bp = ops->walk_stack(task, stack, bp,
				     ops, data, stack_end, &graph);
			/*
			 * We link to the next stack (which would be
			 * the process stack normally) the last
			 * pointer (index -1 to end) in the IRQ stack:
			 */
			stack = (unsigned long *) (stack_end[-1]);
			irq_stack = NULL;
			ops->stack(data, "EOI");
			done = 0;
			break;

		case STACK_IS_UNKNOWN:
			ops->stack(data, "UNK");
			break;
		}
	}

	/*
	 * This handles the process stack:
	 */
	bp = ops->walk_stack(task, stack, bp, ops, data, NULL, &graph);
	put_cpu();
}
EXPORT_SYMBOL(dump_trace);

void
show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
		   unsigned long *sp, unsigned long bp, char *log_lvl)
{
	unsigned long *irq_stack_end;
	unsigned long *irq_stack;
	unsigned long *stack;
	int cpu;
	int i;

	preempt_disable();
	cpu = smp_processor_id();

	irq_stack_end	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
	irq_stack	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);

	/*
	 * Debugging aid: "show_stack(NULL, NULL);" prints the
	 * back trace for this cpu:
	 */
	if (sp == NULL) {
		if (task)
			sp = (unsigned long *)task->thread.sp;
		else
			sp = (unsigned long *)&sp;
	}

	stack = sp;
	for (i = 0; i < kstack_depth_to_print; i++) {
		if (stack >= irq_stack && stack <= irq_stack_end) {
			if (stack == irq_stack_end) {
				stack = (unsigned long *) (irq_stack_end[-1]);
				pr_cont(" <EOI> ");
			}
		} else {
		if (kstack_end(stack))
			break;
		}
		if ((i % STACKSLOTS_PER_LINE) == 0) {
			if (i != 0)
				pr_cont("\n");
			printk("%s %016lx", log_lvl, *stack++);
		} else
			pr_cont(" %016lx", *stack++);
		touch_nmi_watchdog();
	}
	preempt_enable();

	pr_cont("\n");
	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
}

void show_regs(struct pt_regs *regs)
{
	int i;
	unsigned long sp;

	sp = regs->sp;
	show_regs_print_info(KERN_DEFAULT);
	__show_regs(regs, 1);

	/*
	 * When in-kernel, we also print out the stack and code at the
	 * time of the fault..
	 */
	if (!user_mode(regs)) {
		unsigned int code_prologue = code_bytes * 43 / 64;
		unsigned int code_len = code_bytes;
		unsigned char c;
		u8 *ip;

		printk(KERN_DEFAULT "Stack:\n");
		show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
				   0, KERN_DEFAULT);

		printk(KERN_DEFAULT "Code: ");

		ip = (u8 *)regs->ip - code_prologue;
		if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
			/* try starting at IP */
			ip = (u8 *)regs->ip;
			code_len = code_len - code_prologue + 1;
		}
		for (i = 0; i < code_len; i++, ip++) {
			if (ip < (u8 *)PAGE_OFFSET ||
					probe_kernel_address(ip, c)) {
				pr_cont(" Bad RIP value.");
				break;
			}
			if (ip == (u8 *)regs->ip)
				pr_cont("<%02x> ", c);
			else
				pr_cont("%02x ", c);
		}
	}
	pr_cont("\n");
}

int is_valid_bugaddr(unsigned long ip)
{
	unsigned short ud2;

	if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
		return 0;

	return ud2 == 0x0b0f;
}
Commit	Line	Data
6fcbede3 AH	1	/*
	2	* Copyright (C) 1991, 1992 Linus Torvalds
	3	* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
	4	*/
	5	#include <linux/kallsyms.h>
	6	#include <linux/kprobes.h>
	7	#include <linux/uaccess.h>
6fcbede3 AH	8	#include <linux/hardirq.h>
	9	#include <linux/kdebug.h>
	10	#include <linux/module.h>
	11	#include <linux/ptrace.h>
	12	#include <linux/kexec.h>
b8030906	13	#include <linux/sysfs.h>
6fcbede3 AH	14	#include <linux/bug.h>
	15	#include <linux/nmi.h>
	16
	17	#include <asm/stacktrace.h>
	18
6fcbede3	19
b8030906 IM	20	#define N_EXCEPTION_STACKS_END \
b8030906 IM	21	(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
0406ca6d FW	22
0406ca6d FW	23	static char x86_stack_ids[][8] = {
b8030906 IM	24	[ DEBUG_STACK-1 ] = "#DB",
	25	[ NMI_STACK-1 ] = "NMI",
	26	[ DOUBLEFAULT_STACK-1 ] = "#DF",
b8030906	27	[ MCE_STACK-1 ] = "#MC",
6fcbede3	28	#if DEBUG_STKSZ > EXCEPTION_STKSZ
b8030906 IM	29	[ N_EXCEPTION_STACKS ...
b8030906 IM	30	N_EXCEPTION_STACKS_END ] = "#DB[?]"
6fcbede3	31	#endif
b8030906	32	};
0406ca6d	33
0406ca6d	34	static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
b8030906	35	unsigned usedp, char *idp)
0406ca6d	36	{
6fcbede3 AH	37	unsigned k;
	38
	39	/*
	40	* Iterate over all exception stacks, and figure out whether
	41	* 'stack' is in one of them:
	42	*/
	43	for (k = 0; k < N_EXCEPTION_STACKS; k++) {
	44	unsigned long end = per_cpu(orig_ist, cpu).ist[k];
	45	/*
	46	* Is 'stack' above this exception frame's end?
	47	* If yes then skip to the next frame.
	48	*/
	49	if (stack >= end)
	50	continue;
	51	/*
	52	* Is 'stack' above this exception frame's start address?
	53	* If yes then we found the right frame.
	54	*/
	55	if (stack >= end - EXCEPTION_STKSZ) {
	56	/*
	57	* Make sure we only iterate through an exception
	58	* stack once. If it comes up for the second time
	59	* then there's something wrong going on - just
	60	* break out and return NULL:
	61	*/
	62	if (*usedp & (1U << k))
	63	break;
	64	*usedp \|= 1U << k;
0406ca6d	65	*idp = x86_stack_ids[k];
6fcbede3 AH	66	return (unsigned long *)end;
	67	}
	68	/*
	69	* If this is a debug stack, and if it has a larger size than
	70	* the usual exception stacks, then 'stack' might still
	71	* be within the lower portion of the debug stack:
	72	*/
	73	#if DEBUG_STKSZ > EXCEPTION_STKSZ
	74	if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
	75	unsigned j = N_EXCEPTION_STACKS - 1;
	76
	77	/*
	78	* Black magic. A large debug stack is composed of
	79	* multiple exception stack entries, which we
	80	* iterate through now. Dont look:
	81	*/
	82	do {
	83	++j;
	84	end -= EXCEPTION_STKSZ;
0406ca6d FW	85	x86_stack_ids[j][4] = '1' +
0406ca6d FW	86	(j - N_EXCEPTION_STACKS);
6fcbede3 AH	87	} while (stack < end - EXCEPTION_STKSZ);
	88	if (*usedp & (1U << j))
	89	break;
	90	*usedp \|= 1U << j;
0406ca6d	91	*idp = x86_stack_ids[j];
6fcbede3 AH	92	return (unsigned long *)end;
	93	}
	94	#endif
	95	}
	96	return NULL;
	97	}
	98
af2d8289 FW	99	static inline int
	100	in_irq_stack(unsigned long stack, unsigned long irq_stack,
	101	unsigned long *irq_stack_end)
	102	{
	103	return (stack >= irq_stack && stack < irq_stack_end);
	104	}
	105
2223f6f6 SR	106	static const unsigned long irq_stack_size =
	107	(IRQ_STACK_SIZE - 64) / sizeof(unsigned long);
	108
	109	enum stack_type {
	110	STACK_IS_UNKNOWN,
	111	STACK_IS_NORMAL,
	112	STACK_IS_EXCEPTION,
	113	STACK_IS_IRQ,
	114	};
	115
	116	static enum stack_type
1aabc599	117	analyze_stack(int cpu, struct task_struct task, unsigned long stack,
63c95654 SRRH	118	unsigned long *stack_end, unsigned long irq_stack,
63c95654 SRRH	119	unsigned used, char *id)
2223f6f6	120	{
2223f6f6	121	unsigned long addr;
2223f6f6 SR	122
	123	addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));
	124	if ((unsigned long)task_stack_page(task) == addr)
	125	return STACK_IS_NORMAL;
	126
	127	*stack_end = in_exception_stack(cpu, (unsigned long)stack,
1aabc599	128	used, id);
2223f6f6 SR	129	if (*stack_end)
	130	return STACK_IS_EXCEPTION;
	131
63c95654 SRRH	132	if (!irq_stack)
63c95654 SRRH	133	return STACK_IS_NORMAL;
2223f6f6	134
63c95654 SRRH	135	*stack_end = irq_stack;
63c95654 SRRH	136	irq_stack = irq_stack - irq_stack_size;
2223f6f6 SR	137
	138	if (in_irq_stack(stack, irq_stack, *stack_end))
	139	return STACK_IS_IRQ;
	140
	141	return STACK_IS_UNKNOWN;
	142	}
	143
6fcbede3 AH	144	/*
	145	* x86-64 can have up to three kernel stacks:
	146	* process stack
	147	* interrupt stack
	148	* severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
	149	*/
	150
e8e999cf NK	151	void dump_trace(struct task_struct task, struct pt_regs regs,
e8e999cf NK	152	unsigned long *stack, unsigned long bp,
6fcbede3 AH	153	const struct stacktrace_ops ops, void data)
	154	{
	155	const unsigned cpu = get_cpu();
63c95654	156	unsigned long irq_stack = (unsigned long )per_cpu(irq_stack_ptr, cpu);
2e5aa682	157	unsigned long dummy;
1aabc599	158	unsigned used = 0;
2223f6f6 SR	159	int graph = 0;
2223f6f6 SR	160	int done = 0;
6fcbede3 AH	161
	162	if (!task)
	163	task = current;
	164
	165	if (!stack) {
47ce11a2 FW	166	if (regs)
47ce11a2 FW	167	stack = (unsigned long *)regs->sp;
d0caf292	168	else if (task != current)
6fcbede3	169	stack = (unsigned long *)task->thread.sp;
47ce11a2 FW	170	else
47ce11a2 FW	171	stack = &dummy;
6fcbede3 AH	172	}
6fcbede3 AH	173
e8e999cf NK	174	if (!bp)
e8e999cf NK	175	bp = stack_frame(task, regs);
6fcbede3 AH	176	/*
	177	* Print function call entries in all stacks, starting at the
	178	* current stack address. If the stacks consist of nested
	179	* exceptions
	180	*/
2223f6f6 SR	181	while (!done) {
	182	unsigned long *stack_end;
	183	enum stack_type stype;
6fcbede3	184	char *id;
6fcbede3	185
63c95654 SRRH	186	stype = analyze_stack(cpu, task, stack, &stack_end,
63c95654 SRRH	187	irq_stack, &used, &id);
2223f6f6 SR	188
	189	/* Default finish unless specified to continue */
	190	done = 1;
	191
	192	switch (stype) {
	193
	194	/* Break out early if we are on the thread stack */
	195	case STACK_IS_NORMAL:
	196	break;
	197
	198	case STACK_IS_EXCEPTION:
	199
6fcbede3 AH	200	if (ops->stack(data, id) < 0)
	201	break;
	202
da01e18a	203	bp = ops->walk_stack(task, stack, bp, ops,
2223f6f6	204	data, stack_end, &graph);
6fcbede3 AH	205	ops->stack(data, "<EOE>");
	206	/*
	207	* We link to the next stack via the
	208	* second-to-last pointer (index -2 to end) in the
	209	* exception stack:
	210	*/
2223f6f6 SR	211	stack = (unsigned long *) stack_end[-2];
	212	done = 0;
	213	break;
	214
	215	case STACK_IS_IRQ:
	216
	217	if (ops->stack(data, "IRQ") < 0)
	218	break;
da01e18a	219	bp = ops->walk_stack(task, stack, bp,
2223f6f6 SR	220	ops, data, stack_end, &graph);
	221	/*
	222	* We link to the next stack (which would be
	223	* the process stack normally) the last
	224	* pointer (index -1 to end) in the IRQ stack:
	225	*/
	226	stack = (unsigned long *) (stack_end[-1]);
63c95654	227	irq_stack = NULL;
2223f6f6 SR	228	ops->stack(data, "EOI");
	229	done = 0;
	230	break;
	231
	232	case STACK_IS_UNKNOWN:
	233	ops->stack(data, "UNK");
	234	break;
6fcbede3	235	}
6fcbede3 AH	236	}
	237
	238	/*
	239	* This handles the process stack:
	240	*/
da01e18a	241	bp = ops->walk_stack(task, stack, bp, ops, data, NULL, &graph);
6fcbede3 AH	242	put_cpu();
	243	}
	244	EXPORT_SYMBOL(dump_trace);
	245
878719e8	246	void
6fcbede3	247	show_stack_log_lvl(struct task_struct task, struct pt_regs regs,
e8e999cf	248	unsigned long sp, unsigned long bp, char log_lvl)
6fcbede3	249	{
67f2de0b IM	250	unsigned long *irq_stack_end;
67f2de0b IM	251	unsigned long *irq_stack;
6fcbede3	252	unsigned long *stack;
67f2de0b	253	int cpu;
6fcbede3	254	int i;
67f2de0b IM	255
	256	preempt_disable();
	257	cpu = smp_processor_id();
	258
	259	irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
	260	irq_stack = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
6fcbede3 AH	261
6fcbede3 AH	262	/*
67f2de0b IM	263	* Debugging aid: "show_stack(NULL, NULL);" prints the
67f2de0b IM	264	* back trace for this cpu:
6fcbede3	265	*/
6fcbede3 AH	266	if (sp == NULL) {
	267	if (task)
	268	sp = (unsigned long *)task->thread.sp;
	269	else
	270	sp = (unsigned long *)&sp;
	271	}
	272
	273	stack = sp;
	274	for (i = 0; i < kstack_depth_to_print; i++) {
26f80bd6 BG	275	if (stack >= irq_stack && stack <= irq_stack_end) {
	276	if (stack == irq_stack_end) {
	277	stack = (unsigned long *) (irq_stack_end[-1]);
c767a54b	278	pr_cont(" <EOI> ");
6fcbede3 AH	279	}
6fcbede3 AH	280	} else {
04769ae3	281	if (kstack_end(stack))
6fcbede3 AH	282	break;
6fcbede3 AH	283	}
1fc7f61c AS	284	if ((i % STACKSLOTS_PER_LINE) == 0) {
	285	if (i != 0)
	286	pr_cont("\n");
	287	printk("%s %016lx", log_lvl, *stack++);
	288	} else
	289	pr_cont(" %016lx", *stack++);
6fcbede3 AH	290	touch_nmi_watchdog();
6fcbede3 AH	291	}
67f2de0b IM	292	preempt_enable();
67f2de0b IM	293
c767a54b	294	pr_cont("\n");
e8e999cf	295	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
6fcbede3 AH	296	}
6fcbede3 AH	297
57da8b96	298	void show_regs(struct pt_regs *regs)
6fcbede3 AH	299	{
	300	int i;
	301	unsigned long sp;
6fcbede3 AH	302
6fcbede3 AH	303	sp = regs->sp;
a43cb95d	304	show_regs_print_info(KERN_DEFAULT);
6fcbede3	305	__show_regs(regs, 1);
6fcbede3 AH	306
	307	/*
	308	* When in-kernel, we also print out the stack and code at the
	309	* time of the fault..
	310	*/
	311	if (!user_mode(regs)) {
	312	unsigned int code_prologue = code_bytes * 43 / 64;
	313	unsigned int code_len = code_bytes;
	314	unsigned char c;
	315	u8 *ip;
	316
b0f4c4b3	317	printk(KERN_DEFAULT "Stack:\n");
6fcbede3	318	show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
b0f4c4b3	319	0, KERN_DEFAULT);
6fcbede3	320
b0f4c4b3	321	printk(KERN_DEFAULT "Code: ");
6fcbede3 AH	322
	323	ip = (u8 *)regs->ip - code_prologue;
	324	if (ip < (u8 *)PAGE_OFFSET \|\| probe_kernel_address(ip, c)) {
8a541665	325	/* try starting at IP */
6fcbede3 AH	326	ip = (u8 *)regs->ip;
	327	code_len = code_len - code_prologue + 1;
	328	}
	329	for (i = 0; i < code_len; i++, ip++) {
	330	if (ip < (u8 *)PAGE_OFFSET \|\|
	331	probe_kernel_address(ip, c)) {
c767a54b	332	pr_cont(" Bad RIP value.");
6fcbede3 AH	333	break;
	334	}
	335	if (ip == (u8 *)regs->ip)
c767a54b	336	pr_cont("<%02x> ", c);
6fcbede3	337	else
c767a54b	338	pr_cont("%02x ", c);
6fcbede3 AH	339	}
6fcbede3 AH	340	}
c767a54b	341	pr_cont("\n");
6fcbede3 AH	342	}
	343
	344	int is_valid_bugaddr(unsigned long ip)
	345	{
	346	unsigned short ud2;
	347
	348	if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
	349	return 0;
	350
	351	return ud2 == 0x0b0f;
	352	}