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		[ STACKFAULT_STACK-1		]	= "#SS",
28		[ MCE_STACK-1			]	= "#MC",
29#if DEBUG_STKSZ > EXCEPTION_STKSZ
30		[ N_EXCEPTION_STACKS ...
31		  N_EXCEPTION_STACKS_END	]	= "#DB[?]"
32#endif
33};
34
35static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
36					 unsigned *usedp, char **idp)
37{
38	unsigned k;
39
40	/*
41	 * Iterate over all exception stacks, and figure out whether
42	 * 'stack' is in one of them:
43	 */
44	for (k = 0; k < N_EXCEPTION_STACKS; k++) {
45		unsigned long end = per_cpu(orig_ist, cpu).ist[k];
46		/*
47		 * Is 'stack' above this exception frame's end?
48		 * If yes then skip to the next frame.
49		 */
50		if (stack >= end)
51			continue;
52		/*
53		 * Is 'stack' above this exception frame's start address?
54		 * If yes then we found the right frame.
55		 */
56		if (stack >= end - EXCEPTION_STKSZ) {
57			/*
58			 * Make sure we only iterate through an exception
59			 * stack once. If it comes up for the second time
60			 * then there's something wrong going on - just
61			 * break out and return NULL:
62			 */
63			if (*usedp & (1U << k))
64				break;
65			*usedp |= 1U << k;
66			*idp = x86_stack_ids[k];
67			return (unsigned long *)end;
68		}
69		/*
70		 * If this is a debug stack, and if it has a larger size than
71		 * the usual exception stacks, then 'stack' might still
72		 * be within the lower portion of the debug stack:
73		 */
74#if DEBUG_STKSZ > EXCEPTION_STKSZ
75		if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
76			unsigned j = N_EXCEPTION_STACKS - 1;
77
78			/*
79			 * Black magic. A large debug stack is composed of
80			 * multiple exception stack entries, which we
81			 * iterate through now. Dont look:
82			 */
83			do {
84				++j;
85				end -= EXCEPTION_STKSZ;
86				x86_stack_ids[j][4] = '1' +
87						(j - N_EXCEPTION_STACKS);
88			} while (stack < end - EXCEPTION_STKSZ);
89			if (*usedp & (1U << j))
90				break;
91			*usedp |= 1U << j;
92			*idp = x86_stack_ids[j];
93			return (unsigned long *)end;
94		}
95#endif
96	}
97	return NULL;
98}
99
100static inline int
101in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
102	     unsigned long *irq_stack_end)
103{
104	return (stack >= irq_stack && stack < irq_stack_end);
105}
106
107/*
108 * x86-64 can have up to three kernel stacks:
109 * process stack
110 * interrupt stack
111 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
112 */
113
114void dump_trace(struct task_struct *task, struct pt_regs *regs,
115		unsigned long *stack, unsigned long bp,
116		const struct stacktrace_ops *ops, void *data)
117{
118	const unsigned cpu = get_cpu();
119	unsigned long *irq_stack_end =
120		(unsigned long *)per_cpu(irq_stack_ptr, cpu);
121	unsigned used = 0;
122	struct thread_info *tinfo;
123	int graph = 0;
124	unsigned long dummy;
125
126	if (!task)
127		task = current;
128
129	if (!stack) {
130		if (regs)
131			stack = (unsigned long *)regs->sp;
132		else if (task != current)
133			stack = (unsigned long *)task->thread.sp;
134		else
135			stack = &dummy;
136	}
137
138	if (!bp)
139		bp = stack_frame(task, regs);
140	/*
141	 * Print function call entries in all stacks, starting at the
142	 * current stack address. If the stacks consist of nested
143	 * exceptions
144	 */
145	tinfo = task_thread_info(task);
146	for (;;) {
147		char *id;
148		unsigned long *estack_end;
149		estack_end = in_exception_stack(cpu, (unsigned long)stack,
150						&used, &id);
151
152		if (estack_end) {
153			if (ops->stack(data, id) < 0)
154				break;
155
156			bp = ops->walk_stack(tinfo, stack, bp, ops,
157					     data, estack_end, &graph);
158			ops->stack(data, "<EOE>");
159			/*
160			 * We link to the next stack via the
161			 * second-to-last pointer (index -2 to end) in the
162			 * exception stack:
163			 */
164			stack = (unsigned long *) estack_end[-2];
165			continue;
166		}
167		if (irq_stack_end) {
168			unsigned long *irq_stack;
169			irq_stack = irq_stack_end -
170				(IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
171
172			if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
173				if (ops->stack(data, "IRQ") < 0)
174					break;
175				bp = ops->walk_stack(tinfo, stack, bp,
176					ops, data, irq_stack_end, &graph);
177				/*
178				 * We link to the next stack (which would be
179				 * the process stack normally) the last
180				 * pointer (index -1 to end) in the IRQ stack:
181				 */
182				stack = (unsigned long *) (irq_stack_end[-1]);
183				irq_stack_end = NULL;
184				ops->stack(data, "EOI");
185				continue;
186			}
187		}
188		break;
189	}
190
191	/*
192	 * This handles the process stack:
193	 */
194	bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
195	put_cpu();
196}
197EXPORT_SYMBOL(dump_trace);
198
199void
200show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
201		   unsigned long *sp, unsigned long bp, char *log_lvl)
202{
203	unsigned long *irq_stack_end;
204	unsigned long *irq_stack;
205	unsigned long *stack;
206	int cpu;
207	int i;
208
209	preempt_disable();
210	cpu = smp_processor_id();
211
212	irq_stack_end	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
213	irq_stack	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
214
215	/*
216	 * Debugging aid: "show_stack(NULL, NULL);" prints the
217	 * back trace for this cpu:
218	 */
219	if (sp == NULL) {
220		if (task)
221			sp = (unsigned long *)task->thread.sp;
222		else
223			sp = (unsigned long *)&sp;
224	}
225
226	stack = sp;
227	for (i = 0; i < kstack_depth_to_print; i++) {
228		if (stack >= irq_stack && stack <= irq_stack_end) {
229			if (stack == irq_stack_end) {
230				stack = (unsigned long *) (irq_stack_end[-1]);
231				printk(KERN_CONT " <EOI> ");
232			}
233		} else {
234		if (((long) stack & (THREAD_SIZE-1)) == 0)
235			break;
236		}
237		if (i && ((i % STACKSLOTS_PER_LINE) == 0))
238			printk(KERN_CONT "\n");
239		printk(KERN_CONT " %016lx", *stack++);
240		touch_nmi_watchdog();
241	}
242	preempt_enable();
243
244	printk(KERN_CONT "\n");
245	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
246}
247
248void show_registers(struct pt_regs *regs)
249{
250	int i;
251	unsigned long sp;
252	const int cpu = smp_processor_id();
253	struct task_struct *cur = current;
254
255	sp = regs->sp;
256	printk("CPU %d ", cpu);
257	print_modules();
258	__show_regs(regs, 1);
259	printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
260		cur->comm, cur->pid, task_thread_info(cur), cur);
261
262	/*
263	 * When in-kernel, we also print out the stack and code at the
264	 * time of the fault..
265	 */
266	if (!user_mode(regs)) {
267		unsigned int code_prologue = code_bytes * 43 / 64;
268		unsigned int code_len = code_bytes;
269		unsigned char c;
270		u8 *ip;
271
272		printk(KERN_DEFAULT "Stack:\n");
273		show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
274				   0, KERN_DEFAULT);
275
276		printk(KERN_DEFAULT "Code: ");
277
278		ip = (u8 *)regs->ip - code_prologue;
279		if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
280			/* try starting at IP */
281			ip = (u8 *)regs->ip;
282			code_len = code_len - code_prologue + 1;
283		}
284		for (i = 0; i < code_len; i++, ip++) {
285			if (ip < (u8 *)PAGE_OFFSET ||
286					probe_kernel_address(ip, c)) {
287				printk(KERN_CONT " Bad RIP value.");
288				break;
289			}
290			if (ip == (u8 *)regs->ip)
291				printk(KERN_CONT "<%02x> ", c);
292			else
293				printk(KERN_CONT "%02x ", c);
294		}
295	}
296	printk(KERN_CONT "\n");
297}
298
299int is_valid_bugaddr(unsigned long ip)
300{
301	unsigned short ud2;
302
303	if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
304		return 0;
305
306	return ud2 == 0x0b0f;
307}
308