Root/
1 | /* |
2 | * Kernel Debug Core |
3 | * |
4 | * Maintainer: Jason Wessel <jason.wessel@windriver.com> |
5 | * |
6 | * Copyright (C) 2000-2001 VERITAS Software Corporation. |
7 | * Copyright (C) 2002-2004 Timesys Corporation |
8 | * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com> |
9 | * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz> |
10 | * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org> |
11 | * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. |
12 | * Copyright (C) 2005-2009 Wind River Systems, Inc. |
13 | * Copyright (C) 2007 MontaVista Software, Inc. |
14 | * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
15 | * |
16 | * Contributors at various stages not listed above: |
17 | * Jason Wessel ( jason.wessel@windriver.com ) |
18 | * George Anzinger <george@mvista.com> |
19 | * Anurekh Saxena (anurekh.saxena@timesys.com) |
20 | * Lake Stevens Instrument Division (Glenn Engel) |
21 | * Jim Kingdon, Cygnus Support. |
22 | * |
23 | * Original KGDB stub: David Grothe <dave@gcom.com>, |
24 | * Tigran Aivazian <tigran@sco.com> |
25 | * |
26 | * This file is licensed under the terms of the GNU General Public License |
27 | * version 2. This program is licensed "as is" without any warranty of any |
28 | * kind, whether express or implied. |
29 | */ |
30 | #include <linux/pid_namespace.h> |
31 | #include <linux/clocksource.h> |
32 | #include <linux/interrupt.h> |
33 | #include <linux/spinlock.h> |
34 | #include <linux/console.h> |
35 | #include <linux/threads.h> |
36 | #include <linux/uaccess.h> |
37 | #include <linux/kernel.h> |
38 | #include <linux/module.h> |
39 | #include <linux/ptrace.h> |
40 | #include <linux/string.h> |
41 | #include <linux/delay.h> |
42 | #include <linux/sched.h> |
43 | #include <linux/sysrq.h> |
44 | #include <linux/init.h> |
45 | #include <linux/kgdb.h> |
46 | #include <linux/kdb.h> |
47 | #include <linux/pid.h> |
48 | #include <linux/smp.h> |
49 | #include <linux/mm.h> |
50 | #include <linux/rcupdate.h> |
51 | |
52 | #include <asm/cacheflush.h> |
53 | #include <asm/byteorder.h> |
54 | #include <asm/atomic.h> |
55 | #include <asm/system.h> |
56 | |
57 | #include "debug_core.h" |
58 | |
59 | static int kgdb_break_asap; |
60 | |
61 | struct debuggerinfo_struct kgdb_info[NR_CPUS]; |
62 | |
63 | /** |
64 | * kgdb_connected - Is a host GDB connected to us? |
65 | */ |
66 | int kgdb_connected; |
67 | EXPORT_SYMBOL_GPL(kgdb_connected); |
68 | |
69 | /* All the KGDB handlers are installed */ |
70 | int kgdb_io_module_registered; |
71 | |
72 | /* Guard for recursive entry */ |
73 | static int exception_level; |
74 | |
75 | struct kgdb_io *dbg_io_ops; |
76 | static DEFINE_SPINLOCK(kgdb_registration_lock); |
77 | |
78 | /* kgdb console driver is loaded */ |
79 | static int kgdb_con_registered; |
80 | /* determine if kgdb console output should be used */ |
81 | static int kgdb_use_con; |
82 | /* Flag for alternate operations for early debugging */ |
83 | bool dbg_is_early = true; |
84 | /* Next cpu to become the master debug core */ |
85 | int dbg_switch_cpu; |
86 | |
87 | /* Use kdb or gdbserver mode */ |
88 | int dbg_kdb_mode = 1; |
89 | |
90 | static int __init opt_kgdb_con(char *str) |
91 | { |
92 | kgdb_use_con = 1; |
93 | return 0; |
94 | } |
95 | |
96 | early_param("kgdbcon", opt_kgdb_con); |
97 | |
98 | module_param(kgdb_use_con, int, 0644); |
99 | |
100 | /* |
101 | * Holds information about breakpoints in a kernel. These breakpoints are |
102 | * added and removed by gdb. |
103 | */ |
104 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { |
105 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } |
106 | }; |
107 | |
108 | /* |
109 | * The CPU# of the active CPU, or -1 if none: |
110 | */ |
111 | atomic_t kgdb_active = ATOMIC_INIT(-1); |
112 | EXPORT_SYMBOL_GPL(kgdb_active); |
113 | static DEFINE_RAW_SPINLOCK(dbg_master_lock); |
114 | static DEFINE_RAW_SPINLOCK(dbg_slave_lock); |
115 | |
116 | /* |
117 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early |
118 | * bootup code (which might not have percpu set up yet): |
119 | */ |
120 | static atomic_t masters_in_kgdb; |
121 | static atomic_t slaves_in_kgdb; |
122 | static atomic_t kgdb_break_tasklet_var; |
123 | atomic_t kgdb_setting_breakpoint; |
124 | |
125 | struct task_struct *kgdb_usethread; |
126 | struct task_struct *kgdb_contthread; |
127 | |
128 | int kgdb_single_step; |
129 | static pid_t kgdb_sstep_pid; |
130 | |
131 | /* to keep track of the CPU which is doing the single stepping*/ |
132 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); |
133 | |
134 | /* |
135 | * If you are debugging a problem where roundup (the collection of |
136 | * all other CPUs) is a problem [this should be extremely rare], |
137 | * then use the nokgdbroundup option to avoid roundup. In that case |
138 | * the other CPUs might interfere with your debugging context, so |
139 | * use this with care: |
140 | */ |
141 | static int kgdb_do_roundup = 1; |
142 | |
143 | static int __init opt_nokgdbroundup(char *str) |
144 | { |
145 | kgdb_do_roundup = 0; |
146 | |
147 | return 0; |
148 | } |
149 | |
150 | early_param("nokgdbroundup", opt_nokgdbroundup); |
151 | |
152 | /* |
153 | * Finally, some KGDB code :-) |
154 | */ |
155 | |
156 | /* |
157 | * Weak aliases for breakpoint management, |
158 | * can be overriden by architectures when needed: |
159 | */ |
160 | int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr) |
161 | { |
162 | int err; |
163 | |
164 | err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE); |
165 | if (err) |
166 | return err; |
167 | |
168 | return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr, |
169 | BREAK_INSTR_SIZE); |
170 | } |
171 | |
172 | int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle) |
173 | { |
174 | return probe_kernel_write((char *)addr, |
175 | (char *)bundle, BREAK_INSTR_SIZE); |
176 | } |
177 | |
178 | int __weak kgdb_validate_break_address(unsigned long addr) |
179 | { |
180 | char tmp_variable[BREAK_INSTR_SIZE]; |
181 | int err; |
182 | /* Validate setting the breakpoint and then removing it. In the |
183 | * remove fails, the kernel needs to emit a bad message because we |
184 | * are deep trouble not being able to put things back the way we |
185 | * found them. |
186 | */ |
187 | err = kgdb_arch_set_breakpoint(addr, tmp_variable); |
188 | if (err) |
189 | return err; |
190 | err = kgdb_arch_remove_breakpoint(addr, tmp_variable); |
191 | if (err) |
192 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " |
193 | "memory destroyed at: %lx", addr); |
194 | return err; |
195 | } |
196 | |
197 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
198 | { |
199 | return instruction_pointer(regs); |
200 | } |
201 | |
202 | int __weak kgdb_arch_init(void) |
203 | { |
204 | return 0; |
205 | } |
206 | |
207 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
208 | { |
209 | return 0; |
210 | } |
211 | |
212 | /* |
213 | * Some architectures need cache flushes when we set/clear a |
214 | * breakpoint: |
215 | */ |
216 | static void kgdb_flush_swbreak_addr(unsigned long addr) |
217 | { |
218 | if (!CACHE_FLUSH_IS_SAFE) |
219 | return; |
220 | |
221 | if (current->mm && current->mm->mmap_cache) { |
222 | flush_cache_range(current->mm->mmap_cache, |
223 | addr, addr + BREAK_INSTR_SIZE); |
224 | } |
225 | /* Force flush instruction cache if it was outside the mm */ |
226 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); |
227 | } |
228 | |
229 | /* |
230 | * SW breakpoint management: |
231 | */ |
232 | int dbg_activate_sw_breakpoints(void) |
233 | { |
234 | unsigned long addr; |
235 | int error; |
236 | int ret = 0; |
237 | int i; |
238 | |
239 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
240 | if (kgdb_break[i].state != BP_SET) |
241 | continue; |
242 | |
243 | addr = kgdb_break[i].bpt_addr; |
244 | error = kgdb_arch_set_breakpoint(addr, |
245 | kgdb_break[i].saved_instr); |
246 | if (error) { |
247 | ret = error; |
248 | printk(KERN_INFO "KGDB: BP install failed: %lx", addr); |
249 | continue; |
250 | } |
251 | |
252 | kgdb_flush_swbreak_addr(addr); |
253 | kgdb_break[i].state = BP_ACTIVE; |
254 | } |
255 | return ret; |
256 | } |
257 | |
258 | int dbg_set_sw_break(unsigned long addr) |
259 | { |
260 | int err = kgdb_validate_break_address(addr); |
261 | int breakno = -1; |
262 | int i; |
263 | |
264 | if (err) |
265 | return err; |
266 | |
267 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
268 | if ((kgdb_break[i].state == BP_SET) && |
269 | (kgdb_break[i].bpt_addr == addr)) |
270 | return -EEXIST; |
271 | } |
272 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
273 | if (kgdb_break[i].state == BP_REMOVED && |
274 | kgdb_break[i].bpt_addr == addr) { |
275 | breakno = i; |
276 | break; |
277 | } |
278 | } |
279 | |
280 | if (breakno == -1) { |
281 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
282 | if (kgdb_break[i].state == BP_UNDEFINED) { |
283 | breakno = i; |
284 | break; |
285 | } |
286 | } |
287 | } |
288 | |
289 | if (breakno == -1) |
290 | return -E2BIG; |
291 | |
292 | kgdb_break[breakno].state = BP_SET; |
293 | kgdb_break[breakno].type = BP_BREAKPOINT; |
294 | kgdb_break[breakno].bpt_addr = addr; |
295 | |
296 | return 0; |
297 | } |
298 | |
299 | int dbg_deactivate_sw_breakpoints(void) |
300 | { |
301 | unsigned long addr; |
302 | int error; |
303 | int ret = 0; |
304 | int i; |
305 | |
306 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
307 | if (kgdb_break[i].state != BP_ACTIVE) |
308 | continue; |
309 | addr = kgdb_break[i].bpt_addr; |
310 | error = kgdb_arch_remove_breakpoint(addr, |
311 | kgdb_break[i].saved_instr); |
312 | if (error) { |
313 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr); |
314 | ret = error; |
315 | } |
316 | |
317 | kgdb_flush_swbreak_addr(addr); |
318 | kgdb_break[i].state = BP_SET; |
319 | } |
320 | return ret; |
321 | } |
322 | |
323 | int dbg_remove_sw_break(unsigned long addr) |
324 | { |
325 | int i; |
326 | |
327 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
328 | if ((kgdb_break[i].state == BP_SET) && |
329 | (kgdb_break[i].bpt_addr == addr)) { |
330 | kgdb_break[i].state = BP_REMOVED; |
331 | return 0; |
332 | } |
333 | } |
334 | return -ENOENT; |
335 | } |
336 | |
337 | int kgdb_isremovedbreak(unsigned long addr) |
338 | { |
339 | int i; |
340 | |
341 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
342 | if ((kgdb_break[i].state == BP_REMOVED) && |
343 | (kgdb_break[i].bpt_addr == addr)) |
344 | return 1; |
345 | } |
346 | return 0; |
347 | } |
348 | |
349 | int dbg_remove_all_break(void) |
350 | { |
351 | unsigned long addr; |
352 | int error; |
353 | int i; |
354 | |
355 | /* Clear memory breakpoints. */ |
356 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
357 | if (kgdb_break[i].state != BP_ACTIVE) |
358 | goto setundefined; |
359 | addr = kgdb_break[i].bpt_addr; |
360 | error = kgdb_arch_remove_breakpoint(addr, |
361 | kgdb_break[i].saved_instr); |
362 | if (error) |
363 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
364 | addr); |
365 | setundefined: |
366 | kgdb_break[i].state = BP_UNDEFINED; |
367 | } |
368 | |
369 | /* Clear hardware breakpoints. */ |
370 | if (arch_kgdb_ops.remove_all_hw_break) |
371 | arch_kgdb_ops.remove_all_hw_break(); |
372 | |
373 | return 0; |
374 | } |
375 | |
376 | /* |
377 | * Return true if there is a valid kgdb I/O module. Also if no |
378 | * debugger is attached a message can be printed to the console about |
379 | * waiting for the debugger to attach. |
380 | * |
381 | * The print_wait argument is only to be true when called from inside |
382 | * the core kgdb_handle_exception, because it will wait for the |
383 | * debugger to attach. |
384 | */ |
385 | static int kgdb_io_ready(int print_wait) |
386 | { |
387 | if (!dbg_io_ops) |
388 | return 0; |
389 | if (kgdb_connected) |
390 | return 1; |
391 | if (atomic_read(&kgdb_setting_breakpoint)) |
392 | return 1; |
393 | if (print_wait) { |
394 | #ifdef CONFIG_KGDB_KDB |
395 | if (!dbg_kdb_mode) |
396 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); |
397 | #else |
398 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
399 | #endif |
400 | } |
401 | return 1; |
402 | } |
403 | |
404 | static int kgdb_reenter_check(struct kgdb_state *ks) |
405 | { |
406 | unsigned long addr; |
407 | |
408 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) |
409 | return 0; |
410 | |
411 | /* Panic on recursive debugger calls: */ |
412 | exception_level++; |
413 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); |
414 | dbg_deactivate_sw_breakpoints(); |
415 | |
416 | /* |
417 | * If the break point removed ok at the place exception |
418 | * occurred, try to recover and print a warning to the end |
419 | * user because the user planted a breakpoint in a place that |
420 | * KGDB needs in order to function. |
421 | */ |
422 | if (dbg_remove_sw_break(addr) == 0) { |
423 | exception_level = 0; |
424 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
425 | dbg_activate_sw_breakpoints(); |
426 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
427 | addr); |
428 | WARN_ON_ONCE(1); |
429 | |
430 | return 1; |
431 | } |
432 | dbg_remove_all_break(); |
433 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
434 | |
435 | if (exception_level > 1) { |
436 | dump_stack(); |
437 | panic("Recursive entry to debugger"); |
438 | } |
439 | |
440 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); |
441 | #ifdef CONFIG_KGDB_KDB |
442 | /* Allow kdb to debug itself one level */ |
443 | return 0; |
444 | #endif |
445 | dump_stack(); |
446 | panic("Recursive entry to debugger"); |
447 | |
448 | return 1; |
449 | } |
450 | |
451 | static void dbg_touch_watchdogs(void) |
452 | { |
453 | touch_softlockup_watchdog_sync(); |
454 | clocksource_touch_watchdog(); |
455 | rcu_cpu_stall_reset(); |
456 | } |
457 | |
458 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
459 | int exception_state) |
460 | { |
461 | unsigned long flags; |
462 | int sstep_tries = 100; |
463 | int error; |
464 | int cpu; |
465 | int trace_on = 0; |
466 | int online_cpus = num_online_cpus(); |
467 | |
468 | kgdb_info[ks->cpu].enter_kgdb++; |
469 | kgdb_info[ks->cpu].exception_state |= exception_state; |
470 | |
471 | if (exception_state == DCPU_WANT_MASTER) |
472 | atomic_inc(&masters_in_kgdb); |
473 | else |
474 | atomic_inc(&slaves_in_kgdb); |
475 | |
476 | if (arch_kgdb_ops.disable_hw_break) |
477 | arch_kgdb_ops.disable_hw_break(regs); |
478 | |
479 | acquirelock: |
480 | /* |
481 | * Interrupts will be restored by the 'trap return' code, except when |
482 | * single stepping. |
483 | */ |
484 | local_irq_save(flags); |
485 | |
486 | cpu = ks->cpu; |
487 | kgdb_info[cpu].debuggerinfo = regs; |
488 | kgdb_info[cpu].task = current; |
489 | kgdb_info[cpu].ret_state = 0; |
490 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; |
491 | |
492 | /* Make sure the above info reaches the primary CPU */ |
493 | smp_mb(); |
494 | |
495 | if (exception_level == 1) { |
496 | if (raw_spin_trylock(&dbg_master_lock)) |
497 | atomic_xchg(&kgdb_active, cpu); |
498 | goto cpu_master_loop; |
499 | } |
500 | |
501 | /* |
502 | * CPU will loop if it is a slave or request to become a kgdb |
503 | * master cpu and acquire the kgdb_active lock: |
504 | */ |
505 | while (1) { |
506 | cpu_loop: |
507 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { |
508 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; |
509 | goto cpu_master_loop; |
510 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { |
511 | if (raw_spin_trylock(&dbg_master_lock)) { |
512 | atomic_xchg(&kgdb_active, cpu); |
513 | break; |
514 | } |
515 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
516 | if (!raw_spin_is_locked(&dbg_slave_lock)) |
517 | goto return_normal; |
518 | } else { |
519 | return_normal: |
520 | /* Return to normal operation by executing any |
521 | * hw breakpoint fixup. |
522 | */ |
523 | if (arch_kgdb_ops.correct_hw_break) |
524 | arch_kgdb_ops.correct_hw_break(); |
525 | if (trace_on) |
526 | tracing_on(); |
527 | kgdb_info[cpu].exception_state &= |
528 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); |
529 | kgdb_info[cpu].enter_kgdb--; |
530 | smp_mb__before_atomic_dec(); |
531 | atomic_dec(&slaves_in_kgdb); |
532 | dbg_touch_watchdogs(); |
533 | local_irq_restore(flags); |
534 | return 0; |
535 | } |
536 | cpu_relax(); |
537 | } |
538 | |
539 | /* |
540 | * For single stepping, try to only enter on the processor |
541 | * that was single stepping. To guard against a deadlock, the |
542 | * kernel will only try for the value of sstep_tries before |
543 | * giving up and continuing on. |
544 | */ |
545 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && |
546 | (kgdb_info[cpu].task && |
547 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { |
548 | atomic_set(&kgdb_active, -1); |
549 | raw_spin_unlock(&dbg_master_lock); |
550 | dbg_touch_watchdogs(); |
551 | local_irq_restore(flags); |
552 | |
553 | goto acquirelock; |
554 | } |
555 | |
556 | if (!kgdb_io_ready(1)) { |
557 | kgdb_info[cpu].ret_state = 1; |
558 | goto kgdb_restore; /* No I/O connection, resume the system */ |
559 | } |
560 | |
561 | /* |
562 | * Don't enter if we have hit a removed breakpoint. |
563 | */ |
564 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) |
565 | goto kgdb_restore; |
566 | |
567 | /* Call the I/O driver's pre_exception routine */ |
568 | if (dbg_io_ops->pre_exception) |
569 | dbg_io_ops->pre_exception(); |
570 | |
571 | /* |
572 | * Get the passive CPU lock which will hold all the non-primary |
573 | * CPU in a spin state while the debugger is active |
574 | */ |
575 | if (!kgdb_single_step) |
576 | raw_spin_lock(&dbg_slave_lock); |
577 | |
578 | #ifdef CONFIG_SMP |
579 | /* Signal the other CPUs to enter kgdb_wait() */ |
580 | if ((!kgdb_single_step) && kgdb_do_roundup) |
581 | kgdb_roundup_cpus(flags); |
582 | #endif |
583 | |
584 | /* |
585 | * Wait for the other CPUs to be notified and be waiting for us: |
586 | */ |
587 | while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + |
588 | atomic_read(&slaves_in_kgdb)) != online_cpus) |
589 | cpu_relax(); |
590 | |
591 | /* |
592 | * At this point the primary processor is completely |
593 | * in the debugger and all secondary CPUs are quiescent |
594 | */ |
595 | dbg_deactivate_sw_breakpoints(); |
596 | kgdb_single_step = 0; |
597 | kgdb_contthread = current; |
598 | exception_level = 0; |
599 | trace_on = tracing_is_on(); |
600 | if (trace_on) |
601 | tracing_off(); |
602 | |
603 | while (1) { |
604 | cpu_master_loop: |
605 | if (dbg_kdb_mode) { |
606 | kgdb_connected = 1; |
607 | error = kdb_stub(ks); |
608 | if (error == -1) |
609 | continue; |
610 | kgdb_connected = 0; |
611 | } else { |
612 | error = gdb_serial_stub(ks); |
613 | } |
614 | |
615 | if (error == DBG_PASS_EVENT) { |
616 | dbg_kdb_mode = !dbg_kdb_mode; |
617 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
618 | kgdb_info[dbg_switch_cpu].exception_state |= |
619 | DCPU_NEXT_MASTER; |
620 | goto cpu_loop; |
621 | } else { |
622 | kgdb_info[cpu].ret_state = error; |
623 | break; |
624 | } |
625 | } |
626 | |
627 | /* Call the I/O driver's post_exception routine */ |
628 | if (dbg_io_ops->post_exception) |
629 | dbg_io_ops->post_exception(); |
630 | |
631 | if (!kgdb_single_step) { |
632 | raw_spin_unlock(&dbg_slave_lock); |
633 | /* Wait till all the CPUs have quit from the debugger. */ |
634 | while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) |
635 | cpu_relax(); |
636 | } |
637 | |
638 | kgdb_restore: |
639 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
640 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); |
641 | if (kgdb_info[sstep_cpu].task) |
642 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; |
643 | else |
644 | kgdb_sstep_pid = 0; |
645 | } |
646 | if (arch_kgdb_ops.correct_hw_break) |
647 | arch_kgdb_ops.correct_hw_break(); |
648 | if (trace_on) |
649 | tracing_on(); |
650 | |
651 | kgdb_info[cpu].exception_state &= |
652 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); |
653 | kgdb_info[cpu].enter_kgdb--; |
654 | smp_mb__before_atomic_dec(); |
655 | atomic_dec(&masters_in_kgdb); |
656 | /* Free kgdb_active */ |
657 | atomic_set(&kgdb_active, -1); |
658 | raw_spin_unlock(&dbg_master_lock); |
659 | dbg_touch_watchdogs(); |
660 | local_irq_restore(flags); |
661 | |
662 | return kgdb_info[cpu].ret_state; |
663 | } |
664 | |
665 | /* |
666 | * kgdb_handle_exception() - main entry point from a kernel exception |
667 | * |
668 | * Locking hierarchy: |
669 | * interface locks, if any (begin_session) |
670 | * kgdb lock (kgdb_active) |
671 | */ |
672 | int |
673 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) |
674 | { |
675 | struct kgdb_state kgdb_var; |
676 | struct kgdb_state *ks = &kgdb_var; |
677 | |
678 | ks->cpu = raw_smp_processor_id(); |
679 | ks->ex_vector = evector; |
680 | ks->signo = signo; |
681 | ks->err_code = ecode; |
682 | ks->kgdb_usethreadid = 0; |
683 | ks->linux_regs = regs; |
684 | |
685 | if (kgdb_reenter_check(ks)) |
686 | return 0; /* Ouch, double exception ! */ |
687 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
688 | return 0; |
689 | |
690 | return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); |
691 | } |
692 | |
693 | int kgdb_nmicallback(int cpu, void *regs) |
694 | { |
695 | #ifdef CONFIG_SMP |
696 | struct kgdb_state kgdb_var; |
697 | struct kgdb_state *ks = &kgdb_var; |
698 | |
699 | memset(ks, 0, sizeof(struct kgdb_state)); |
700 | ks->cpu = cpu; |
701 | ks->linux_regs = regs; |
702 | |
703 | if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
704 | raw_spin_is_locked(&dbg_master_lock)) { |
705 | kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); |
706 | return 0; |
707 | } |
708 | #endif |
709 | return 1; |
710 | } |
711 | |
712 | static void kgdb_console_write(struct console *co, const char *s, |
713 | unsigned count) |
714 | { |
715 | unsigned long flags; |
716 | |
717 | /* If we're debugging, or KGDB has not connected, don't try |
718 | * and print. */ |
719 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
720 | return; |
721 | |
722 | local_irq_save(flags); |
723 | gdbstub_msg_write(s, count); |
724 | local_irq_restore(flags); |
725 | } |
726 | |
727 | static struct console kgdbcons = { |
728 | .name = "kgdb", |
729 | .write = kgdb_console_write, |
730 | .flags = CON_PRINTBUFFER | CON_ENABLED, |
731 | .index = -1, |
732 | }; |
733 | |
734 | #ifdef CONFIG_MAGIC_SYSRQ |
735 | static void sysrq_handle_dbg(int key) |
736 | { |
737 | if (!dbg_io_ops) { |
738 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
739 | return; |
740 | } |
741 | if (!kgdb_connected) { |
742 | #ifdef CONFIG_KGDB_KDB |
743 | if (!dbg_kdb_mode) |
744 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); |
745 | #else |
746 | printk(KERN_CRIT "Entering KGDB\n"); |
747 | #endif |
748 | } |
749 | |
750 | kgdb_breakpoint(); |
751 | } |
752 | |
753 | static struct sysrq_key_op sysrq_dbg_op = { |
754 | .handler = sysrq_handle_dbg, |
755 | .help_msg = "debug(G)", |
756 | .action_msg = "DEBUG", |
757 | }; |
758 | #endif |
759 | |
760 | static int kgdb_panic_event(struct notifier_block *self, |
761 | unsigned long val, |
762 | void *data) |
763 | { |
764 | if (dbg_kdb_mode) |
765 | kdb_printf("PANIC: %s\n", (char *)data); |
766 | kgdb_breakpoint(); |
767 | return NOTIFY_DONE; |
768 | } |
769 | |
770 | static struct notifier_block kgdb_panic_event_nb = { |
771 | .notifier_call = kgdb_panic_event, |
772 | .priority = INT_MAX, |
773 | }; |
774 | |
775 | void __weak kgdb_arch_late(void) |
776 | { |
777 | } |
778 | |
779 | void __init dbg_late_init(void) |
780 | { |
781 | dbg_is_early = false; |
782 | if (kgdb_io_module_registered) |
783 | kgdb_arch_late(); |
784 | kdb_init(KDB_INIT_FULL); |
785 | } |
786 | |
787 | static void kgdb_register_callbacks(void) |
788 | { |
789 | if (!kgdb_io_module_registered) { |
790 | kgdb_io_module_registered = 1; |
791 | kgdb_arch_init(); |
792 | if (!dbg_is_early) |
793 | kgdb_arch_late(); |
794 | atomic_notifier_chain_register(&panic_notifier_list, |
795 | &kgdb_panic_event_nb); |
796 | #ifdef CONFIG_MAGIC_SYSRQ |
797 | register_sysrq_key('g', &sysrq_dbg_op); |
798 | #endif |
799 | if (kgdb_use_con && !kgdb_con_registered) { |
800 | register_console(&kgdbcons); |
801 | kgdb_con_registered = 1; |
802 | } |
803 | } |
804 | } |
805 | |
806 | static void kgdb_unregister_callbacks(void) |
807 | { |
808 | /* |
809 | * When this routine is called KGDB should unregister from the |
810 | * panic handler and clean up, making sure it is not handling any |
811 | * break exceptions at the time. |
812 | */ |
813 | if (kgdb_io_module_registered) { |
814 | kgdb_io_module_registered = 0; |
815 | atomic_notifier_chain_unregister(&panic_notifier_list, |
816 | &kgdb_panic_event_nb); |
817 | kgdb_arch_exit(); |
818 | #ifdef CONFIG_MAGIC_SYSRQ |
819 | unregister_sysrq_key('g', &sysrq_dbg_op); |
820 | #endif |
821 | if (kgdb_con_registered) { |
822 | unregister_console(&kgdbcons); |
823 | kgdb_con_registered = 0; |
824 | } |
825 | } |
826 | } |
827 | |
828 | /* |
829 | * There are times a tasklet needs to be used vs a compiled in |
830 | * break point so as to cause an exception outside a kgdb I/O module, |
831 | * such as is the case with kgdboe, where calling a breakpoint in the |
832 | * I/O driver itself would be fatal. |
833 | */ |
834 | static void kgdb_tasklet_bpt(unsigned long ing) |
835 | { |
836 | kgdb_breakpoint(); |
837 | atomic_set(&kgdb_break_tasklet_var, 0); |
838 | } |
839 | |
840 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); |
841 | |
842 | void kgdb_schedule_breakpoint(void) |
843 | { |
844 | if (atomic_read(&kgdb_break_tasklet_var) || |
845 | atomic_read(&kgdb_active) != -1 || |
846 | atomic_read(&kgdb_setting_breakpoint)) |
847 | return; |
848 | atomic_inc(&kgdb_break_tasklet_var); |
849 | tasklet_schedule(&kgdb_tasklet_breakpoint); |
850 | } |
851 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); |
852 | |
853 | static void kgdb_initial_breakpoint(void) |
854 | { |
855 | kgdb_break_asap = 0; |
856 | |
857 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); |
858 | kgdb_breakpoint(); |
859 | } |
860 | |
861 | /** |
862 | * kgdb_register_io_module - register KGDB IO module |
863 | * @new_dbg_io_ops: the io ops vector |
864 | * |
865 | * Register it with the KGDB core. |
866 | */ |
867 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
868 | { |
869 | int err; |
870 | |
871 | spin_lock(&kgdb_registration_lock); |
872 | |
873 | if (dbg_io_ops) { |
874 | spin_unlock(&kgdb_registration_lock); |
875 | |
876 | printk(KERN_ERR "kgdb: Another I/O driver is already " |
877 | "registered with KGDB.\n"); |
878 | return -EBUSY; |
879 | } |
880 | |
881 | if (new_dbg_io_ops->init) { |
882 | err = new_dbg_io_ops->init(); |
883 | if (err) { |
884 | spin_unlock(&kgdb_registration_lock); |
885 | return err; |
886 | } |
887 | } |
888 | |
889 | dbg_io_ops = new_dbg_io_ops; |
890 | |
891 | spin_unlock(&kgdb_registration_lock); |
892 | |
893 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", |
894 | new_dbg_io_ops->name); |
895 | |
896 | /* Arm KGDB now. */ |
897 | kgdb_register_callbacks(); |
898 | |
899 | if (kgdb_break_asap) |
900 | kgdb_initial_breakpoint(); |
901 | |
902 | return 0; |
903 | } |
904 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); |
905 | |
906 | /** |
907 | * kkgdb_unregister_io_module - unregister KGDB IO module |
908 | * @old_dbg_io_ops: the io ops vector |
909 | * |
910 | * Unregister it with the KGDB core. |
911 | */ |
912 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
913 | { |
914 | BUG_ON(kgdb_connected); |
915 | |
916 | /* |
917 | * KGDB is no longer able to communicate out, so |
918 | * unregister our callbacks and reset state. |
919 | */ |
920 | kgdb_unregister_callbacks(); |
921 | |
922 | spin_lock(&kgdb_registration_lock); |
923 | |
924 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
925 | dbg_io_ops = NULL; |
926 | |
927 | spin_unlock(&kgdb_registration_lock); |
928 | |
929 | printk(KERN_INFO |
930 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", |
931 | old_dbg_io_ops->name); |
932 | } |
933 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); |
934 | |
935 | int dbg_io_get_char(void) |
936 | { |
937 | int ret = dbg_io_ops->read_char(); |
938 | if (ret == NO_POLL_CHAR) |
939 | return -1; |
940 | if (!dbg_kdb_mode) |
941 | return ret; |
942 | if (ret == 127) |
943 | return 8; |
944 | return ret; |
945 | } |
946 | |
947 | /** |
948 | * kgdb_breakpoint - generate breakpoint exception |
949 | * |
950 | * This function will generate a breakpoint exception. It is used at the |
951 | * beginning of a program to sync up with a debugger and can be used |
952 | * otherwise as a quick means to stop program execution and "break" into |
953 | * the debugger. |
954 | */ |
955 | void kgdb_breakpoint(void) |
956 | { |
957 | atomic_inc(&kgdb_setting_breakpoint); |
958 | wmb(); /* Sync point before breakpoint */ |
959 | arch_kgdb_breakpoint(); |
960 | wmb(); /* Sync point after breakpoint */ |
961 | atomic_dec(&kgdb_setting_breakpoint); |
962 | } |
963 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); |
964 | |
965 | static int __init opt_kgdb_wait(char *str) |
966 | { |
967 | kgdb_break_asap = 1; |
968 | |
969 | kdb_init(KDB_INIT_EARLY); |
970 | if (kgdb_io_module_registered) |
971 | kgdb_initial_breakpoint(); |
972 | |
973 | return 0; |
974 | } |
975 | |
976 | early_param("kgdbwait", opt_kgdb_wait); |
977 |
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