]>
Commit | Line | Data |
---|---|---|
dc7d5527 | 1 | /* |
53197fc4 | 2 | * Kernel Debug Core |
dc7d5527 JW |
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@suse.cz> | |
10 | * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org> | |
11 | * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. | |
53197fc4 | 12 | * Copyright (C) 2005-2009 Wind River Systems, Inc. |
dc7d5527 JW |
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> | |
7c3078b6 | 31 | #include <linux/clocksource.h> |
dc7d5527 JW |
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> | |
dc7d5527 JW |
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/pid.h> | |
47 | #include <linux/smp.h> | |
48 | #include <linux/mm.h> | |
49 | ||
50 | #include <asm/cacheflush.h> | |
51 | #include <asm/byteorder.h> | |
52 | #include <asm/atomic.h> | |
53 | #include <asm/system.h> | |
54 | ||
53197fc4 | 55 | #include "debug_core.h" |
dc7d5527 | 56 | |
53197fc4 | 57 | static int kgdb_break_asap; |
62fae312 | 58 | |
53197fc4 | 59 | struct debuggerinfo_struct kgdb_info[NR_CPUS]; |
dc7d5527 JW |
60 | |
61 | /** | |
62 | * kgdb_connected - Is a host GDB connected to us? | |
63 | */ | |
64 | int kgdb_connected; | |
65 | EXPORT_SYMBOL_GPL(kgdb_connected); | |
66 | ||
67 | /* All the KGDB handlers are installed */ | |
68 | static int kgdb_io_module_registered; | |
69 | ||
70 | /* Guard for recursive entry */ | |
71 | static int exception_level; | |
72 | ||
53197fc4 | 73 | struct kgdb_io *dbg_io_ops; |
dc7d5527 JW |
74 | static DEFINE_SPINLOCK(kgdb_registration_lock); |
75 | ||
76 | /* kgdb console driver is loaded */ | |
77 | static int kgdb_con_registered; | |
78 | /* determine if kgdb console output should be used */ | |
79 | static int kgdb_use_con; | |
80 | ||
81 | static int __init opt_kgdb_con(char *str) | |
82 | { | |
83 | kgdb_use_con = 1; | |
84 | return 0; | |
85 | } | |
86 | ||
87 | early_param("kgdbcon", opt_kgdb_con); | |
88 | ||
89 | module_param(kgdb_use_con, int, 0644); | |
90 | ||
91 | /* | |
92 | * Holds information about breakpoints in a kernel. These breakpoints are | |
93 | * added and removed by gdb. | |
94 | */ | |
95 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { | |
96 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } | |
97 | }; | |
98 | ||
99 | /* | |
100 | * The CPU# of the active CPU, or -1 if none: | |
101 | */ | |
102 | atomic_t kgdb_active = ATOMIC_INIT(-1); | |
103 | ||
104 | /* | |
105 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early | |
106 | * bootup code (which might not have percpu set up yet): | |
107 | */ | |
108 | static atomic_t passive_cpu_wait[NR_CPUS]; | |
109 | static atomic_t cpu_in_kgdb[NR_CPUS]; | |
110 | atomic_t kgdb_setting_breakpoint; | |
111 | ||
112 | struct task_struct *kgdb_usethread; | |
113 | struct task_struct *kgdb_contthread; | |
114 | ||
115 | int kgdb_single_step; | |
53197fc4 | 116 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
117 | |
118 | /* to keep track of the CPU which is doing the single stepping*/ | |
119 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); | |
120 | ||
121 | /* | |
122 | * If you are debugging a problem where roundup (the collection of | |
123 | * all other CPUs) is a problem [this should be extremely rare], | |
124 | * then use the nokgdbroundup option to avoid roundup. In that case | |
125 | * the other CPUs might interfere with your debugging context, so | |
126 | * use this with care: | |
127 | */ | |
688b744d | 128 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
129 | |
130 | static int __init opt_nokgdbroundup(char *str) | |
131 | { | |
132 | kgdb_do_roundup = 0; | |
133 | ||
134 | return 0; | |
135 | } | |
136 | ||
137 | early_param("nokgdbroundup", opt_nokgdbroundup); | |
138 | ||
139 | /* | |
140 | * Finally, some KGDB code :-) | |
141 | */ | |
142 | ||
143 | /* | |
144 | * Weak aliases for breakpoint management, | |
145 | * can be overriden by architectures when needed: | |
146 | */ | |
dc7d5527 JW |
147 | int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr) |
148 | { | |
149 | int err; | |
150 | ||
151 | err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE); | |
152 | if (err) | |
153 | return err; | |
154 | ||
155 | return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr, | |
156 | BREAK_INSTR_SIZE); | |
157 | } | |
158 | ||
159 | int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle) | |
160 | { | |
161 | return probe_kernel_write((char *)addr, | |
162 | (char *)bundle, BREAK_INSTR_SIZE); | |
163 | } | |
164 | ||
a9b60bf4 JW |
165 | int __weak kgdb_validate_break_address(unsigned long addr) |
166 | { | |
167 | char tmp_variable[BREAK_INSTR_SIZE]; | |
168 | int err; | |
169 | /* Validate setting the breakpoint and then removing it. In the | |
170 | * remove fails, the kernel needs to emit a bad message because we | |
171 | * are deep trouble not being able to put things back the way we | |
172 | * found them. | |
173 | */ | |
174 | err = kgdb_arch_set_breakpoint(addr, tmp_variable); | |
175 | if (err) | |
176 | return err; | |
177 | err = kgdb_arch_remove_breakpoint(addr, tmp_variable); | |
178 | if (err) | |
179 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " | |
180 | "memory destroyed at: %lx", addr); | |
181 | return err; | |
182 | } | |
183 | ||
dc7d5527 JW |
184 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
185 | { | |
186 | return instruction_pointer(regs); | |
187 | } | |
188 | ||
189 | int __weak kgdb_arch_init(void) | |
190 | { | |
191 | return 0; | |
192 | } | |
193 | ||
b4b8ac52 JW |
194 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
195 | { | |
196 | return 0; | |
197 | } | |
198 | ||
199 | void __weak | |
200 | kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code) | |
201 | { | |
202 | return; | |
203 | } | |
204 | ||
dc7d5527 JW |
205 | /** |
206 | * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. | |
207 | * @regs: Current &struct pt_regs. | |
208 | * | |
209 | * This function will be called if the particular architecture must | |
210 | * disable hardware debugging while it is processing gdb packets or | |
211 | * handling exception. | |
212 | */ | |
213 | void __weak kgdb_disable_hw_debug(struct pt_regs *regs) | |
214 | { | |
215 | } | |
216 | ||
dc7d5527 JW |
217 | /* |
218 | * Some architectures need cache flushes when we set/clear a | |
219 | * breakpoint: | |
220 | */ | |
221 | static void kgdb_flush_swbreak_addr(unsigned long addr) | |
222 | { | |
223 | if (!CACHE_FLUSH_IS_SAFE) | |
224 | return; | |
225 | ||
737a460f | 226 | if (current->mm && current->mm->mmap_cache) { |
dc7d5527 JW |
227 | flush_cache_range(current->mm->mmap_cache, |
228 | addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 | 229 | } |
1a9a3e76 JW |
230 | /* Force flush instruction cache if it was outside the mm */ |
231 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 JW |
232 | } |
233 | ||
234 | /* | |
235 | * SW breakpoint management: | |
236 | */ | |
53197fc4 | 237 | int dbg_activate_sw_breakpoints(void) |
dc7d5527 JW |
238 | { |
239 | unsigned long addr; | |
7f8b7ed6 JW |
240 | int error; |
241 | int ret = 0; | |
dc7d5527 JW |
242 | int i; |
243 | ||
244 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
245 | if (kgdb_break[i].state != BP_SET) | |
246 | continue; | |
247 | ||
248 | addr = kgdb_break[i].bpt_addr; | |
249 | error = kgdb_arch_set_breakpoint(addr, | |
250 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
251 | if (error) { |
252 | ret = error; | |
253 | printk(KERN_INFO "KGDB: BP install failed: %lx", addr); | |
254 | continue; | |
255 | } | |
dc7d5527 JW |
256 | |
257 | kgdb_flush_swbreak_addr(addr); | |
258 | kgdb_break[i].state = BP_ACTIVE; | |
259 | } | |
7f8b7ed6 | 260 | return ret; |
dc7d5527 JW |
261 | } |
262 | ||
53197fc4 | 263 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
264 | { |
265 | int err = kgdb_validate_break_address(addr); | |
266 | int breakno = -1; | |
267 | int i; | |
268 | ||
269 | if (err) | |
270 | return err; | |
271 | ||
272 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
273 | if ((kgdb_break[i].state == BP_SET) && | |
274 | (kgdb_break[i].bpt_addr == addr)) | |
275 | return -EEXIST; | |
276 | } | |
277 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
278 | if (kgdb_break[i].state == BP_REMOVED && | |
279 | kgdb_break[i].bpt_addr == addr) { | |
280 | breakno = i; | |
281 | break; | |
282 | } | |
283 | } | |
284 | ||
285 | if (breakno == -1) { | |
286 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
287 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
288 | breakno = i; | |
289 | break; | |
290 | } | |
291 | } | |
292 | } | |
293 | ||
294 | if (breakno == -1) | |
295 | return -E2BIG; | |
296 | ||
297 | kgdb_break[breakno].state = BP_SET; | |
298 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
299 | kgdb_break[breakno].bpt_addr = addr; | |
300 | ||
301 | return 0; | |
302 | } | |
303 | ||
304 | static int kgdb_deactivate_sw_breakpoints(void) | |
305 | { | |
306 | unsigned long addr; | |
7f8b7ed6 JW |
307 | int error; |
308 | int ret = 0; | |
dc7d5527 JW |
309 | int i; |
310 | ||
311 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
312 | if (kgdb_break[i].state != BP_ACTIVE) | |
313 | continue; | |
314 | addr = kgdb_break[i].bpt_addr; | |
315 | error = kgdb_arch_remove_breakpoint(addr, | |
316 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
317 | if (error) { |
318 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr); | |
319 | ret = error; | |
320 | } | |
dc7d5527 JW |
321 | |
322 | kgdb_flush_swbreak_addr(addr); | |
323 | kgdb_break[i].state = BP_SET; | |
324 | } | |
7f8b7ed6 | 325 | return ret; |
dc7d5527 JW |
326 | } |
327 | ||
53197fc4 | 328 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
329 | { |
330 | int i; | |
331 | ||
332 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
333 | if ((kgdb_break[i].state == BP_SET) && | |
334 | (kgdb_break[i].bpt_addr == addr)) { | |
335 | kgdb_break[i].state = BP_REMOVED; | |
336 | return 0; | |
337 | } | |
338 | } | |
339 | return -ENOENT; | |
340 | } | |
341 | ||
342 | int kgdb_isremovedbreak(unsigned long addr) | |
343 | { | |
344 | int i; | |
345 | ||
346 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
347 | if ((kgdb_break[i].state == BP_REMOVED) && | |
348 | (kgdb_break[i].bpt_addr == addr)) | |
349 | return 1; | |
350 | } | |
351 | return 0; | |
352 | } | |
353 | ||
53197fc4 | 354 | int dbg_remove_all_break(void) |
dc7d5527 JW |
355 | { |
356 | unsigned long addr; | |
357 | int error; | |
358 | int i; | |
359 | ||
360 | /* Clear memory breakpoints. */ | |
361 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
362 | if (kgdb_break[i].state != BP_ACTIVE) |
363 | goto setundefined; | |
dc7d5527 JW |
364 | addr = kgdb_break[i].bpt_addr; |
365 | error = kgdb_arch_remove_breakpoint(addr, | |
366 | kgdb_break[i].saved_instr); | |
367 | if (error) | |
737a460f JW |
368 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
369 | addr); | |
370 | setundefined: | |
371 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
372 | } |
373 | ||
374 | /* Clear hardware breakpoints. */ | |
375 | if (arch_kgdb_ops.remove_all_hw_break) | |
376 | arch_kgdb_ops.remove_all_hw_break(); | |
377 | ||
378 | return 0; | |
379 | } | |
380 | ||
dc7d5527 JW |
381 | /* |
382 | * Return true if there is a valid kgdb I/O module. Also if no | |
383 | * debugger is attached a message can be printed to the console about | |
384 | * waiting for the debugger to attach. | |
385 | * | |
386 | * The print_wait argument is only to be true when called from inside | |
387 | * the core kgdb_handle_exception, because it will wait for the | |
388 | * debugger to attach. | |
389 | */ | |
390 | static int kgdb_io_ready(int print_wait) | |
391 | { | |
53197fc4 | 392 | if (!dbg_io_ops) |
dc7d5527 JW |
393 | return 0; |
394 | if (kgdb_connected) | |
395 | return 1; | |
396 | if (atomic_read(&kgdb_setting_breakpoint)) | |
397 | return 1; | |
398 | if (print_wait) | |
399 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); | |
400 | return 1; | |
401 | } | |
402 | ||
dc7d5527 JW |
403 | static int kgdb_reenter_check(struct kgdb_state *ks) |
404 | { | |
405 | unsigned long addr; | |
406 | ||
407 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
408 | return 0; | |
409 | ||
410 | /* Panic on recursive debugger calls: */ | |
411 | exception_level++; | |
412 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
413 | kgdb_deactivate_sw_breakpoints(); | |
414 | ||
415 | /* | |
416 | * If the break point removed ok at the place exception | |
417 | * occurred, try to recover and print a warning to the end | |
418 | * user because the user planted a breakpoint in a place that | |
419 | * KGDB needs in order to function. | |
420 | */ | |
53197fc4 | 421 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
422 | exception_level = 0; |
423 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 424 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
425 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
426 | addr); | |
dc7d5527 JW |
427 | WARN_ON_ONCE(1); |
428 | ||
429 | return 1; | |
430 | } | |
53197fc4 | 431 | dbg_remove_all_break(); |
dc7d5527 JW |
432 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
433 | ||
434 | if (exception_level > 1) { | |
435 | dump_stack(); | |
436 | panic("Recursive entry to debugger"); | |
437 | } | |
438 | ||
439 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
440 | dump_stack(); | |
441 | panic("Recursive entry to debugger"); | |
442 | ||
443 | return 1; | |
444 | } | |
445 | ||
62fae312 | 446 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs) |
dc7d5527 | 447 | { |
dc7d5527 | 448 | unsigned long flags; |
028e7b17 | 449 | int sstep_tries = 100; |
dc7d5527 JW |
450 | int error = 0; |
451 | int i, cpu; | |
4da75b9c | 452 | int trace_on = 0; |
dc7d5527 JW |
453 | acquirelock: |
454 | /* | |
455 | * Interrupts will be restored by the 'trap return' code, except when | |
456 | * single stepping. | |
457 | */ | |
458 | local_irq_save(flags); | |
459 | ||
62fae312 JW |
460 | cpu = ks->cpu; |
461 | kgdb_info[cpu].debuggerinfo = regs; | |
462 | kgdb_info[cpu].task = current; | |
463 | /* | |
464 | * Make sure the above info reaches the primary CPU before | |
465 | * our cpu_in_kgdb[] flag setting does: | |
466 | */ | |
ae6bf53e | 467 | atomic_inc(&cpu_in_kgdb[cpu]); |
dc7d5527 JW |
468 | |
469 | /* | |
62fae312 JW |
470 | * CPU will loop if it is a slave or request to become a kgdb |
471 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 472 | */ |
62fae312 JW |
473 | while (1) { |
474 | if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
475 | if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu) | |
476 | break; | |
477 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { | |
478 | if (!atomic_read(&passive_cpu_wait[cpu])) | |
479 | goto return_normal; | |
480 | } else { | |
481 | return_normal: | |
482 | /* Return to normal operation by executing any | |
483 | * hw breakpoint fixup. | |
484 | */ | |
485 | if (arch_kgdb_ops.correct_hw_break) | |
486 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
487 | if (trace_on) |
488 | tracing_on(); | |
ae6bf53e | 489 | atomic_dec(&cpu_in_kgdb[cpu]); |
62fae312 JW |
490 | touch_softlockup_watchdog_sync(); |
491 | clocksource_touch_watchdog(); | |
492 | local_irq_restore(flags); | |
493 | return 0; | |
494 | } | |
dc7d5527 | 495 | cpu_relax(); |
62fae312 | 496 | } |
dc7d5527 JW |
497 | |
498 | /* | |
028e7b17 JW |
499 | * For single stepping, try to only enter on the processor |
500 | * that was single stepping. To gaurd against a deadlock, the | |
501 | * kernel will only try for the value of sstep_tries before | |
502 | * giving up and continuing on. | |
dc7d5527 JW |
503 | */ |
504 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
505 | (kgdb_info[cpu].task && |
506 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 507 | atomic_set(&kgdb_active, -1); |
d6ad3e28 | 508 | touch_softlockup_watchdog_sync(); |
7c3078b6 | 509 | clocksource_touch_watchdog(); |
dc7d5527 JW |
510 | local_irq_restore(flags); |
511 | ||
512 | goto acquirelock; | |
513 | } | |
514 | ||
515 | if (!kgdb_io_ready(1)) { | |
516 | error = 1; | |
53197fc4 | 517 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
518 | } |
519 | ||
520 | /* | |
521 | * Don't enter if we have hit a removed breakpoint. | |
522 | */ | |
523 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
524 | goto kgdb_restore; | |
525 | ||
526 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
527 | if (dbg_io_ops->pre_exception) |
528 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 529 | |
dc7d5527 JW |
530 | kgdb_disable_hw_debug(ks->linux_regs); |
531 | ||
532 | /* | |
533 | * Get the passive CPU lock which will hold all the non-primary | |
534 | * CPU in a spin state while the debugger is active | |
535 | */ | |
d7161a65 | 536 | if (!kgdb_single_step) { |
dc7d5527 | 537 | for (i = 0; i < NR_CPUS; i++) |
ae6bf53e | 538 | atomic_inc(&passive_cpu_wait[i]); |
dc7d5527 JW |
539 | } |
540 | ||
56fb7093 JW |
541 | #ifdef CONFIG_SMP |
542 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 543 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
544 | kgdb_roundup_cpus(flags); |
545 | #endif | |
546 | ||
dc7d5527 JW |
547 | /* |
548 | * Wait for the other CPUs to be notified and be waiting for us: | |
549 | */ | |
550 | for_each_online_cpu(i) { | |
551 | while (!atomic_read(&cpu_in_kgdb[i])) | |
552 | cpu_relax(); | |
553 | } | |
554 | ||
555 | /* | |
556 | * At this point the primary processor is completely | |
557 | * in the debugger and all secondary CPUs are quiescent | |
558 | */ | |
559 | kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code); | |
560 | kgdb_deactivate_sw_breakpoints(); | |
561 | kgdb_single_step = 0; | |
d7161a65 | 562 | kgdb_contthread = current; |
dc7d5527 | 563 | exception_level = 0; |
4da75b9c JW |
564 | trace_on = tracing_is_on(); |
565 | if (trace_on) | |
566 | tracing_off(); | |
dc7d5527 JW |
567 | |
568 | /* Talk to debugger with gdbserial protocol */ | |
569 | error = gdb_serial_stub(ks); | |
570 | ||
571 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
572 | if (dbg_io_ops->post_exception) |
573 | dbg_io_ops->post_exception(); | |
dc7d5527 | 574 | |
ae6bf53e | 575 | atomic_dec(&cpu_in_kgdb[ks->cpu]); |
dc7d5527 | 576 | |
d7161a65 | 577 | if (!kgdb_single_step) { |
dc7d5527 | 578 | for (i = NR_CPUS-1; i >= 0; i--) |
ae6bf53e | 579 | atomic_dec(&passive_cpu_wait[i]); |
dc7d5527 JW |
580 | /* |
581 | * Wait till all the CPUs have quit | |
582 | * from the debugger. | |
583 | */ | |
584 | for_each_online_cpu(i) { | |
585 | while (atomic_read(&cpu_in_kgdb[i])) | |
586 | cpu_relax(); | |
587 | } | |
588 | } | |
589 | ||
590 | kgdb_restore: | |
028e7b17 JW |
591 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
592 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
593 | if (kgdb_info[sstep_cpu].task) | |
594 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
595 | else | |
596 | kgdb_sstep_pid = 0; | |
597 | } | |
4da75b9c JW |
598 | if (trace_on) |
599 | tracing_on(); | |
dc7d5527 JW |
600 | /* Free kgdb_active */ |
601 | atomic_set(&kgdb_active, -1); | |
d6ad3e28 | 602 | touch_softlockup_watchdog_sync(); |
7c3078b6 | 603 | clocksource_touch_watchdog(); |
dc7d5527 JW |
604 | local_irq_restore(flags); |
605 | ||
606 | return error; | |
607 | } | |
608 | ||
62fae312 JW |
609 | /* |
610 | * kgdb_handle_exception() - main entry point from a kernel exception | |
611 | * | |
612 | * Locking hierarchy: | |
613 | * interface locks, if any (begin_session) | |
614 | * kgdb lock (kgdb_active) | |
615 | */ | |
616 | int | |
617 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
618 | { | |
619 | struct kgdb_state kgdb_var; | |
620 | struct kgdb_state *ks = &kgdb_var; | |
621 | int ret; | |
622 | ||
623 | ks->cpu = raw_smp_processor_id(); | |
624 | ks->ex_vector = evector; | |
625 | ks->signo = signo; | |
626 | ks->ex_vector = evector; | |
627 | ks->err_code = ecode; | |
628 | ks->kgdb_usethreadid = 0; | |
629 | ks->linux_regs = regs; | |
630 | ||
631 | if (kgdb_reenter_check(ks)) | |
632 | return 0; /* Ouch, double exception ! */ | |
633 | kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER; | |
634 | ret = kgdb_cpu_enter(ks, regs); | |
635 | kgdb_info[ks->cpu].exception_state &= ~DCPU_WANT_MASTER; | |
636 | return ret; | |
637 | } | |
638 | ||
dc7d5527 JW |
639 | int kgdb_nmicallback(int cpu, void *regs) |
640 | { | |
641 | #ifdef CONFIG_SMP | |
62fae312 JW |
642 | struct kgdb_state kgdb_var; |
643 | struct kgdb_state *ks = &kgdb_var; | |
644 | ||
645 | memset(ks, 0, sizeof(struct kgdb_state)); | |
646 | ks->cpu = cpu; | |
647 | ks->linux_regs = regs; | |
648 | ||
dc7d5527 | 649 | if (!atomic_read(&cpu_in_kgdb[cpu]) && |
62fae312 JW |
650 | atomic_read(&kgdb_active) != -1 && |
651 | atomic_read(&kgdb_active) != cpu) { | |
652 | kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE; | |
653 | kgdb_cpu_enter(ks, regs); | |
654 | kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE; | |
dc7d5527 JW |
655 | return 0; |
656 | } | |
657 | #endif | |
658 | return 1; | |
659 | } | |
660 | ||
aabdc3b8 JW |
661 | static void kgdb_console_write(struct console *co, const char *s, |
662 | unsigned count) | |
dc7d5527 JW |
663 | { |
664 | unsigned long flags; | |
665 | ||
666 | /* If we're debugging, or KGDB has not connected, don't try | |
667 | * and print. */ | |
668 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1) | |
669 | return; | |
670 | ||
671 | local_irq_save(flags); | |
53197fc4 | 672 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
673 | local_irq_restore(flags); |
674 | } | |
675 | ||
676 | static struct console kgdbcons = { | |
677 | .name = "kgdb", | |
678 | .write = kgdb_console_write, | |
679 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
680 | .index = -1, | |
681 | }; | |
682 | ||
683 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 684 | static void sysrq_handle_dbg(int key, struct tty_struct *tty) |
dc7d5527 | 685 | { |
53197fc4 | 686 | if (!dbg_io_ops) { |
dc7d5527 JW |
687 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
688 | return; | |
689 | } | |
690 | if (!kgdb_connected) | |
691 | printk(KERN_CRIT "Entering KGDB\n"); | |
692 | ||
693 | kgdb_breakpoint(); | |
694 | } | |
695 | ||
53197fc4 JW |
696 | static struct sysrq_key_op sysrq_dbg_op = { |
697 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
698 | .help_msg = "debug(G)", |
699 | .action_msg = "DEBUG", | |
dc7d5527 JW |
700 | }; |
701 | #endif | |
702 | ||
703 | static void kgdb_register_callbacks(void) | |
704 | { | |
705 | if (!kgdb_io_module_registered) { | |
706 | kgdb_io_module_registered = 1; | |
707 | kgdb_arch_init(); | |
708 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 709 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
710 | #endif |
711 | if (kgdb_use_con && !kgdb_con_registered) { | |
712 | register_console(&kgdbcons); | |
713 | kgdb_con_registered = 1; | |
714 | } | |
715 | } | |
716 | } | |
717 | ||
718 | static void kgdb_unregister_callbacks(void) | |
719 | { | |
720 | /* | |
721 | * When this routine is called KGDB should unregister from the | |
722 | * panic handler and clean up, making sure it is not handling any | |
723 | * break exceptions at the time. | |
724 | */ | |
725 | if (kgdb_io_module_registered) { | |
726 | kgdb_io_module_registered = 0; | |
727 | kgdb_arch_exit(); | |
728 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 729 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
730 | #endif |
731 | if (kgdb_con_registered) { | |
732 | unregister_console(&kgdbcons); | |
733 | kgdb_con_registered = 0; | |
734 | } | |
735 | } | |
736 | } | |
737 | ||
738 | static void kgdb_initial_breakpoint(void) | |
739 | { | |
740 | kgdb_break_asap = 0; | |
741 | ||
742 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
743 | kgdb_breakpoint(); | |
744 | } | |
745 | ||
746 | /** | |
737a460f | 747 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 748 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
749 | * |
750 | * Register it with the KGDB core. | |
751 | */ | |
53197fc4 | 752 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
753 | { |
754 | int err; | |
755 | ||
756 | spin_lock(&kgdb_registration_lock); | |
757 | ||
53197fc4 | 758 | if (dbg_io_ops) { |
dc7d5527 JW |
759 | spin_unlock(&kgdb_registration_lock); |
760 | ||
761 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
762 | "registered with KGDB.\n"); | |
763 | return -EBUSY; | |
764 | } | |
765 | ||
53197fc4 JW |
766 | if (new_dbg_io_ops->init) { |
767 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
768 | if (err) { |
769 | spin_unlock(&kgdb_registration_lock); | |
770 | return err; | |
771 | } | |
772 | } | |
773 | ||
53197fc4 | 774 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
775 | |
776 | spin_unlock(&kgdb_registration_lock); | |
777 | ||
778 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 779 | new_dbg_io_ops->name); |
dc7d5527 JW |
780 | |
781 | /* Arm KGDB now. */ | |
782 | kgdb_register_callbacks(); | |
783 | ||
784 | if (kgdb_break_asap) | |
785 | kgdb_initial_breakpoint(); | |
786 | ||
787 | return 0; | |
788 | } | |
789 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
790 | ||
791 | /** | |
792 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 793 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
794 | * |
795 | * Unregister it with the KGDB core. | |
796 | */ | |
53197fc4 | 797 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
798 | { |
799 | BUG_ON(kgdb_connected); | |
800 | ||
801 | /* | |
802 | * KGDB is no longer able to communicate out, so | |
803 | * unregister our callbacks and reset state. | |
804 | */ | |
805 | kgdb_unregister_callbacks(); | |
806 | ||
807 | spin_lock(&kgdb_registration_lock); | |
808 | ||
53197fc4 JW |
809 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
810 | dbg_io_ops = NULL; | |
dc7d5527 JW |
811 | |
812 | spin_unlock(&kgdb_registration_lock); | |
813 | ||
814 | printk(KERN_INFO | |
815 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 816 | old_dbg_io_ops->name); |
dc7d5527 JW |
817 | } |
818 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
819 | ||
820 | /** | |
821 | * kgdb_breakpoint - generate breakpoint exception | |
822 | * | |
823 | * This function will generate a breakpoint exception. It is used at the | |
824 | * beginning of a program to sync up with a debugger and can be used | |
825 | * otherwise as a quick means to stop program execution and "break" into | |
826 | * the debugger. | |
827 | */ | |
828 | void kgdb_breakpoint(void) | |
829 | { | |
ae6bf53e | 830 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
831 | wmb(); /* Sync point before breakpoint */ |
832 | arch_kgdb_breakpoint(); | |
833 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 834 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
835 | } |
836 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
837 | ||
838 | static int __init opt_kgdb_wait(char *str) | |
839 | { | |
840 | kgdb_break_asap = 1; | |
841 | ||
842 | if (kgdb_io_module_registered) | |
843 | kgdb_initial_breakpoint(); | |
844 | ||
845 | return 0; | |
846 | } | |
847 | ||
848 | early_param("kgdbwait", opt_kgdb_wait); |