x86: Constify a few items
[linux-3.10.git] / arch / x86 / kernel / dumpstack_64.c
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 }
197 EXPORT_SYMBOL(dump_trace);
198
199 void
200 show_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                                 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++);
240                 touch_nmi_watchdog();
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 }