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dumpstack_64.c
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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 
23 static 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 
35 static 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 
100 static inline int
101 in_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 
114 void 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 }
198 
199 void
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  pr_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  pr_cont("\n");
239  pr_cont(" %016lx", *stack++);
241  }
242  preempt_enable();
243 
244  pr_cont("\n");
245  show_trace_log_lvl(task, regs, sp, bp, log_lvl);
246 }
247 
248 void show_regs(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  __show_regs(regs, 1);
258  printk(KERN_DEFAULT "Process %s (pid: %d, threadinfo %p, task %p)\n",
259  cur->comm, cur->pid, task_thread_info(cur), cur);
260 
261  /*
262  * When in-kernel, we also print out the stack and code at the
263  * time of the fault..
264  */
265  if (!user_mode(regs)) {
266  unsigned int code_prologue = code_bytes * 43 / 64;
267  unsigned int code_len = code_bytes;
268  unsigned char c;
269  u8 *ip;
270 
271  printk(KERN_DEFAULT "Stack:\n");
272  show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
273  0, KERN_DEFAULT);
274 
275  printk(KERN_DEFAULT "Code: ");
276 
277  ip = (u8 *)regs->ip - code_prologue;
278  if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
279  /* try starting at IP */
280  ip = (u8 *)regs->ip;
281  code_len = code_len - code_prologue + 1;
282  }
283  for (i = 0; i < code_len; i++, ip++) {
284  if (ip < (u8 *)PAGE_OFFSET ||
285  probe_kernel_address(ip, c)) {
286  pr_cont(" Bad RIP value.");
287  break;
288  }
289  if (ip == (u8 *)regs->ip)
290  pr_cont("<%02x> ", c);
291  else
292  pr_cont("%02x ", c);
293  }
294  }
295  pr_cont("\n");
296 }
297 
298 int is_valid_bugaddr(unsigned long ip)
299 {
300  unsigned short ud2;
301 
302  if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
303  return 0;
304 
305  return ud2 == 0x0b0f;
306 }