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>
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>
13#include <linux/sysfs.h>
14#include <linux/bug.h>
15#include <linux/nmi.h>
16
17#include <asm/stacktrace.h>
18
19
20#define N_EXCEPTION_STACKS_END \
21		(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
22
23static char x86_stack_ids[][8] = {
24		[ DEBUG_STACK-1			]	= "#DB",
25		[ NMI_STACK-1			]	= "NMI",
26		[ DOUBLEFAULT_STACK-1		]	= "#DF",
27		[ MCE_STACK-1			]	= "#MC",
28#if DEBUG_STKSZ > EXCEPTION_STKSZ
29		[ N_EXCEPTION_STACKS ...
30		  N_EXCEPTION_STACKS_END	]	= "#DB[?]"
31#endif
32};
33
34static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
35					 unsigned *usedp, char **idp)
36{
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;
65			*idp = x86_stack_ids[k];
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;
85				x86_stack_ids[j][4] = '1' +
86						(j - N_EXCEPTION_STACKS);
87			} while (stack < end - EXCEPTION_STKSZ);
88			if (*usedp & (1U << j))
89				break;
90			*usedp |= 1U << j;
91			*idp = x86_stack_ids[j];
92			return (unsigned long *)end;
93		}
94#endif
95	}
96	return NULL;
97}
98
99static inline int
100in_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
106static const unsigned long irq_stack_size =
107	(IRQ_STACK_SIZE - 64) / sizeof(unsigned long);
108
109enum stack_type {
110	STACK_IS_UNKNOWN,
111	STACK_IS_NORMAL,
112	STACK_IS_EXCEPTION,
113	STACK_IS_IRQ,
114};
115
116static enum stack_type
117analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
118	      unsigned long **stack_end, unsigned long *irq_stack,
119	      unsigned *used, char **id)
120{
121	unsigned long addr;
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,
128					used, id);
129	if (*stack_end)
130		return STACK_IS_EXCEPTION;
131
132	if (!irq_stack)
133		return STACK_IS_NORMAL;
134
135	*stack_end = irq_stack;
136	irq_stack = irq_stack - irq_stack_size;
137
138	if (in_irq_stack(stack, irq_stack, *stack_end))
139		return STACK_IS_IRQ;
140
141	return STACK_IS_UNKNOWN;
142}
143
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
151void dump_trace(struct task_struct *task, struct pt_regs *regs,
152		unsigned long *stack, unsigned long bp,
153		const struct stacktrace_ops *ops, void *data)
154{
155	const unsigned cpu = get_cpu();
156	struct thread_info *tinfo;
157	unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
158	unsigned long dummy;
159	unsigned used = 0;
160	int graph = 0;
161	int done = 0;
162
163	if (!task)
164		task = current;
165
166	if (!stack) {
167		if (regs)
168			stack = (unsigned long *)regs->sp;
169		else if (task != current)
170			stack = (unsigned long *)task->thread.sp;
171		else
172			stack = &dummy;
173	}
174
175	if (!bp)
176		bp = stack_frame(task, regs);
177	/*
178	 * Print function call entries in all stacks, starting at the
179	 * current stack address. If the stacks consist of nested
180	 * exceptions
181	 */
182	tinfo = task_thread_info(task);
183	while (!done) {
184		unsigned long *stack_end;
185		enum stack_type stype;
186		char *id;
187
188		stype = analyze_stack(cpu, task, stack, &stack_end,
189				      irq_stack, &used, &id);
190
191		/* Default finish unless specified to continue */
192		done = 1;
193
194		switch (stype) {
195
196		/* Break out early if we are on the thread stack */
197		case STACK_IS_NORMAL:
198			break;
199
200		case STACK_IS_EXCEPTION:
201
202			if (ops->stack(data, id) < 0)
203				break;
204
205			bp = ops->walk_stack(tinfo, stack, bp, ops,
206					     data, stack_end, &graph);
207			ops->stack(data, "<EOE>");
208			/*
209			 * We link to the next stack via the
210			 * second-to-last pointer (index -2 to end) in the
211			 * exception stack:
212			 */
213			stack = (unsigned long *) stack_end[-2];
214			done = 0;
215			break;
216
217		case STACK_IS_IRQ:
218
219			if (ops->stack(data, "IRQ") < 0)
220				break;
221			bp = ops->walk_stack(tinfo, stack, bp,
222				     ops, data, stack_end, &graph);
223			/*
224			 * We link to the next stack (which would be
225			 * the process stack normally) the last
226			 * pointer (index -1 to end) in the IRQ stack:
227			 */
228			stack = (unsigned long *) (stack_end[-1]);
229			irq_stack = NULL;
230			ops->stack(data, "EOI");
231			done = 0;
232			break;
233
234		case STACK_IS_UNKNOWN:
235			ops->stack(data, "UNK");
236			break;
237		}
238	}
239
240	/*
241	 * This handles the process stack:
242	 */
243	bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
244	put_cpu();
245}
246EXPORT_SYMBOL(dump_trace);
247
248void
249show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
250		   unsigned long *sp, unsigned long bp, char *log_lvl)
251{
252	unsigned long *irq_stack_end;
253	unsigned long *irq_stack;
254	unsigned long *stack;
255	int cpu;
256	int i;
257
258	preempt_disable();
259	cpu = smp_processor_id();
260
261	irq_stack_end	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
262	irq_stack	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
263
264	/*
265	 * Debugging aid: "show_stack(NULL, NULL);" prints the
266	 * back trace for this cpu:
267	 */
268	if (sp == NULL) {
269		if (task)
270			sp = (unsigned long *)task->thread.sp;
271		else
272			sp = (unsigned long *)&sp;
273	}
274
275	stack = sp;
276	for (i = 0; i < kstack_depth_to_print; i++) {
277		if (stack >= irq_stack && stack <= irq_stack_end) {
278			if (stack == irq_stack_end) {
279				stack = (unsigned long *) (irq_stack_end[-1]);
280				pr_cont(" <EOI> ");
281			}
282		} else {
283		if (kstack_end(stack))
284			break;
285		}
286		if ((i % STACKSLOTS_PER_LINE) == 0) {
287			if (i != 0)
288				pr_cont("\n");
289			printk("%s %016lx", log_lvl, *stack++);
290		} else
291			pr_cont(" %016lx", *stack++);
292		touch_nmi_watchdog();
293	}
294	preempt_enable();
295
296	pr_cont("\n");
297	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
298}
299
300void show_regs(struct pt_regs *regs)
301{
302	int i;
303	unsigned long sp;
304
305	sp = regs->sp;
306	show_regs_print_info(KERN_DEFAULT);
307	__show_regs(regs, 1);
308
309	/*
310	 * When in-kernel, we also print out the stack and code at the
311	 * time of the fault..
312	 */
313	if (!user_mode(regs)) {
314		unsigned int code_prologue = code_bytes * 43 / 64;
315		unsigned int code_len = code_bytes;
316		unsigned char c;
317		u8 *ip;
318
319		printk(KERN_DEFAULT "Stack:\n");
320		show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
321				   0, KERN_DEFAULT);
322
323		printk(KERN_DEFAULT "Code: ");
324
325		ip = (u8 *)regs->ip - code_prologue;
326		if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
327			/* try starting at IP */
328			ip = (u8 *)regs->ip;
329			code_len = code_len - code_prologue + 1;
330		}
331		for (i = 0; i < code_len; i++, ip++) {
332			if (ip < (u8 *)PAGE_OFFSET ||
333					probe_kernel_address(ip, c)) {
334				pr_cont(" Bad RIP value.");
335				break;
336			}
337			if (ip == (u8 *)regs->ip)
338				pr_cont("<%02x> ", c);
339			else
340				pr_cont("%02x ", c);
341		}
342	}
343	pr_cont("\n");
344}
345
346int is_valid_bugaddr(unsigned long ip)
347{
348	unsigned short ud2;
349
350	if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
351		return 0;
352
353	return ud2 == 0x0b0f;
354}
355