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> | |
a2531293 | 9 | * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz> |
dc7d5527 JW |
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> | |
2366e047 | 44 | #include <linux/reboot.h> |
dc7d5527 JW |
45 | #include <linux/init.h> |
46 | #include <linux/kgdb.h> | |
dcc78711 | 47 | #include <linux/kdb.h> |
dc7d5527 JW |
48 | #include <linux/pid.h> |
49 | #include <linux/smp.h> | |
50 | #include <linux/mm.h> | |
fb70b588 | 51 | #include <linux/rcupdate.h> |
dc7d5527 JW |
52 | |
53 | #include <asm/cacheflush.h> | |
54 | #include <asm/byteorder.h> | |
60063497 | 55 | #include <linux/atomic.h> |
dc7d5527 JW |
56 | #include <asm/system.h> |
57 | ||
53197fc4 | 58 | #include "debug_core.h" |
dc7d5527 | 59 | |
53197fc4 | 60 | static int kgdb_break_asap; |
62fae312 | 61 | |
53197fc4 | 62 | struct debuggerinfo_struct kgdb_info[NR_CPUS]; |
dc7d5527 JW |
63 | |
64 | /** | |
65 | * kgdb_connected - Is a host GDB connected to us? | |
66 | */ | |
67 | int kgdb_connected; | |
68 | EXPORT_SYMBOL_GPL(kgdb_connected); | |
69 | ||
70 | /* All the KGDB handlers are installed */ | |
f503b5ae | 71 | int kgdb_io_module_registered; |
dc7d5527 JW |
72 | |
73 | /* Guard for recursive entry */ | |
74 | static int exception_level; | |
75 | ||
53197fc4 | 76 | struct kgdb_io *dbg_io_ops; |
dc7d5527 JW |
77 | static DEFINE_SPINLOCK(kgdb_registration_lock); |
78 | ||
bec4d62e JW |
79 | /* Action for the reboot notifiter, a global allow kdb to change it */ |
80 | static int kgdbreboot; | |
dc7d5527 JW |
81 | /* kgdb console driver is loaded */ |
82 | static int kgdb_con_registered; | |
83 | /* determine if kgdb console output should be used */ | |
84 | static int kgdb_use_con; | |
0b4b3827 JW |
85 | /* Flag for alternate operations for early debugging */ |
86 | bool dbg_is_early = true; | |
dcc78711 JW |
87 | /* Next cpu to become the master debug core */ |
88 | int dbg_switch_cpu; | |
89 | ||
90 | /* Use kdb or gdbserver mode */ | |
a0de055c | 91 | int dbg_kdb_mode = 1; |
dc7d5527 JW |
92 | |
93 | static int __init opt_kgdb_con(char *str) | |
94 | { | |
95 | kgdb_use_con = 1; | |
96 | return 0; | |
97 | } | |
98 | ||
99 | early_param("kgdbcon", opt_kgdb_con); | |
100 | ||
101 | module_param(kgdb_use_con, int, 0644); | |
bec4d62e | 102 | module_param(kgdbreboot, int, 0644); |
dc7d5527 JW |
103 | |
104 | /* | |
105 | * Holds information about breakpoints in a kernel. These breakpoints are | |
106 | * added and removed by gdb. | |
107 | */ | |
108 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { | |
109 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } | |
110 | }; | |
111 | ||
112 | /* | |
113 | * The CPU# of the active CPU, or -1 if none: | |
114 | */ | |
115 | atomic_t kgdb_active = ATOMIC_INIT(-1); | |
dcc78711 | 116 | EXPORT_SYMBOL_GPL(kgdb_active); |
dfee3a7b JW |
117 | static DEFINE_RAW_SPINLOCK(dbg_master_lock); |
118 | static DEFINE_RAW_SPINLOCK(dbg_slave_lock); | |
dc7d5527 JW |
119 | |
120 | /* | |
121 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early | |
122 | * bootup code (which might not have percpu set up yet): | |
123 | */ | |
dfee3a7b JW |
124 | static atomic_t masters_in_kgdb; |
125 | static atomic_t slaves_in_kgdb; | |
1cee5e35 | 126 | static atomic_t kgdb_break_tasklet_var; |
dc7d5527 JW |
127 | atomic_t kgdb_setting_breakpoint; |
128 | ||
129 | struct task_struct *kgdb_usethread; | |
130 | struct task_struct *kgdb_contthread; | |
131 | ||
132 | int kgdb_single_step; | |
53197fc4 | 133 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
134 | |
135 | /* to keep track of the CPU which is doing the single stepping*/ | |
136 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); | |
137 | ||
138 | /* | |
139 | * If you are debugging a problem where roundup (the collection of | |
140 | * all other CPUs) is a problem [this should be extremely rare], | |
141 | * then use the nokgdbroundup option to avoid roundup. In that case | |
142 | * the other CPUs might interfere with your debugging context, so | |
143 | * use this with care: | |
144 | */ | |
688b744d | 145 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
146 | |
147 | static int __init opt_nokgdbroundup(char *str) | |
148 | { | |
149 | kgdb_do_roundup = 0; | |
150 | ||
151 | return 0; | |
152 | } | |
153 | ||
154 | early_param("nokgdbroundup", opt_nokgdbroundup); | |
155 | ||
156 | /* | |
157 | * Finally, some KGDB code :-) | |
158 | */ | |
159 | ||
160 | /* | |
161 | * Weak aliases for breakpoint management, | |
162 | * can be overriden by architectures when needed: | |
163 | */ | |
dc7d5527 JW |
164 | int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr) |
165 | { | |
166 | int err; | |
167 | ||
168 | err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE); | |
169 | if (err) | |
170 | return err; | |
171 | ||
172 | return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr, | |
173 | BREAK_INSTR_SIZE); | |
174 | } | |
175 | ||
176 | int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle) | |
177 | { | |
178 | return probe_kernel_write((char *)addr, | |
179 | (char *)bundle, BREAK_INSTR_SIZE); | |
180 | } | |
181 | ||
a9b60bf4 JW |
182 | int __weak kgdb_validate_break_address(unsigned long addr) |
183 | { | |
184 | char tmp_variable[BREAK_INSTR_SIZE]; | |
185 | int err; | |
186 | /* Validate setting the breakpoint and then removing it. In the | |
187 | * remove fails, the kernel needs to emit a bad message because we | |
188 | * are deep trouble not being able to put things back the way we | |
189 | * found them. | |
190 | */ | |
191 | err = kgdb_arch_set_breakpoint(addr, tmp_variable); | |
192 | if (err) | |
193 | return err; | |
194 | err = kgdb_arch_remove_breakpoint(addr, tmp_variable); | |
195 | if (err) | |
196 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " | |
197 | "memory destroyed at: %lx", addr); | |
198 | return err; | |
199 | } | |
200 | ||
dc7d5527 JW |
201 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
202 | { | |
203 | return instruction_pointer(regs); | |
204 | } | |
205 | ||
206 | int __weak kgdb_arch_init(void) | |
207 | { | |
208 | return 0; | |
209 | } | |
210 | ||
b4b8ac52 JW |
211 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
212 | { | |
213 | return 0; | |
214 | } | |
215 | ||
dc7d5527 JW |
216 | /* |
217 | * Some architectures need cache flushes when we set/clear a | |
218 | * breakpoint: | |
219 | */ | |
220 | static void kgdb_flush_swbreak_addr(unsigned long addr) | |
221 | { | |
222 | if (!CACHE_FLUSH_IS_SAFE) | |
223 | return; | |
224 | ||
737a460f | 225 | if (current->mm && current->mm->mmap_cache) { |
dc7d5527 JW |
226 | flush_cache_range(current->mm->mmap_cache, |
227 | addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 | 228 | } |
1a9a3e76 JW |
229 | /* Force flush instruction cache if it was outside the mm */ |
230 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 JW |
231 | } |
232 | ||
233 | /* | |
234 | * SW breakpoint management: | |
235 | */ | |
53197fc4 | 236 | int dbg_activate_sw_breakpoints(void) |
dc7d5527 JW |
237 | { |
238 | unsigned long addr; | |
7f8b7ed6 JW |
239 | int error; |
240 | int ret = 0; | |
dc7d5527 JW |
241 | int i; |
242 | ||
243 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
244 | if (kgdb_break[i].state != BP_SET) | |
245 | continue; | |
246 | ||
247 | addr = kgdb_break[i].bpt_addr; | |
248 | error = kgdb_arch_set_breakpoint(addr, | |
249 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
250 | if (error) { |
251 | ret = error; | |
252 | printk(KERN_INFO "KGDB: BP install failed: %lx", addr); | |
253 | continue; | |
254 | } | |
dc7d5527 JW |
255 | |
256 | kgdb_flush_swbreak_addr(addr); | |
257 | kgdb_break[i].state = BP_ACTIVE; | |
258 | } | |
7f8b7ed6 | 259 | return ret; |
dc7d5527 JW |
260 | } |
261 | ||
53197fc4 | 262 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
263 | { |
264 | int err = kgdb_validate_break_address(addr); | |
265 | int breakno = -1; | |
266 | int i; | |
267 | ||
268 | if (err) | |
269 | return err; | |
270 | ||
271 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
272 | if ((kgdb_break[i].state == BP_SET) && | |
273 | (kgdb_break[i].bpt_addr == addr)) | |
274 | return -EEXIST; | |
275 | } | |
276 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
277 | if (kgdb_break[i].state == BP_REMOVED && | |
278 | kgdb_break[i].bpt_addr == addr) { | |
279 | breakno = i; | |
280 | break; | |
281 | } | |
282 | } | |
283 | ||
284 | if (breakno == -1) { | |
285 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
286 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
287 | breakno = i; | |
288 | break; | |
289 | } | |
290 | } | |
291 | } | |
292 | ||
293 | if (breakno == -1) | |
294 | return -E2BIG; | |
295 | ||
296 | kgdb_break[breakno].state = BP_SET; | |
297 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
298 | kgdb_break[breakno].bpt_addr = addr; | |
299 | ||
300 | return 0; | |
301 | } | |
302 | ||
dcc78711 | 303 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 JW |
304 | { |
305 | unsigned long addr; | |
7f8b7ed6 JW |
306 | int error; |
307 | int ret = 0; | |
dc7d5527 JW |
308 | int i; |
309 | ||
310 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
311 | if (kgdb_break[i].state != BP_ACTIVE) | |
312 | continue; | |
313 | addr = kgdb_break[i].bpt_addr; | |
314 | error = kgdb_arch_remove_breakpoint(addr, | |
315 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
316 | if (error) { |
317 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr); | |
318 | ret = error; | |
319 | } | |
dc7d5527 JW |
320 | |
321 | kgdb_flush_swbreak_addr(addr); | |
322 | kgdb_break[i].state = BP_SET; | |
323 | } | |
7f8b7ed6 | 324 | return ret; |
dc7d5527 JW |
325 | } |
326 | ||
53197fc4 | 327 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
328 | { |
329 | int i; | |
330 | ||
331 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
332 | if ((kgdb_break[i].state == BP_SET) && | |
333 | (kgdb_break[i].bpt_addr == addr)) { | |
334 | kgdb_break[i].state = BP_REMOVED; | |
335 | return 0; | |
336 | } | |
337 | } | |
338 | return -ENOENT; | |
339 | } | |
340 | ||
341 | int kgdb_isremovedbreak(unsigned long addr) | |
342 | { | |
343 | int i; | |
344 | ||
345 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
346 | if ((kgdb_break[i].state == BP_REMOVED) && | |
347 | (kgdb_break[i].bpt_addr == addr)) | |
348 | return 1; | |
349 | } | |
350 | return 0; | |
351 | } | |
352 | ||
53197fc4 | 353 | int dbg_remove_all_break(void) |
dc7d5527 JW |
354 | { |
355 | unsigned long addr; | |
356 | int error; | |
357 | int i; | |
358 | ||
359 | /* Clear memory breakpoints. */ | |
360 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
361 | if (kgdb_break[i].state != BP_ACTIVE) |
362 | goto setundefined; | |
dc7d5527 JW |
363 | addr = kgdb_break[i].bpt_addr; |
364 | error = kgdb_arch_remove_breakpoint(addr, | |
365 | kgdb_break[i].saved_instr); | |
366 | if (error) | |
737a460f JW |
367 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
368 | addr); | |
369 | setundefined: | |
370 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
371 | } |
372 | ||
373 | /* Clear hardware breakpoints. */ | |
374 | if (arch_kgdb_ops.remove_all_hw_break) | |
375 | arch_kgdb_ops.remove_all_hw_break(); | |
376 | ||
377 | return 0; | |
378 | } | |
379 | ||
dc7d5527 JW |
380 | /* |
381 | * Return true if there is a valid kgdb I/O module. Also if no | |
382 | * debugger is attached a message can be printed to the console about | |
383 | * waiting for the debugger to attach. | |
384 | * | |
385 | * The print_wait argument is only to be true when called from inside | |
386 | * the core kgdb_handle_exception, because it will wait for the | |
387 | * debugger to attach. | |
388 | */ | |
389 | static int kgdb_io_ready(int print_wait) | |
390 | { | |
53197fc4 | 391 | if (!dbg_io_ops) |
dc7d5527 JW |
392 | return 0; |
393 | if (kgdb_connected) | |
394 | return 1; | |
395 | if (atomic_read(&kgdb_setting_breakpoint)) | |
396 | return 1; | |
dcc78711 JW |
397 | if (print_wait) { |
398 | #ifdef CONFIG_KGDB_KDB | |
399 | if (!dbg_kdb_mode) | |
400 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); | |
401 | #else | |
dc7d5527 | 402 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
403 | #endif |
404 | } | |
dc7d5527 JW |
405 | return 1; |
406 | } | |
407 | ||
dc7d5527 JW |
408 | static int kgdb_reenter_check(struct kgdb_state *ks) |
409 | { | |
410 | unsigned long addr; | |
411 | ||
412 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
413 | return 0; | |
414 | ||
415 | /* Panic on recursive debugger calls: */ | |
416 | exception_level++; | |
417 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
dcc78711 | 418 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
419 | |
420 | /* | |
421 | * If the break point removed ok at the place exception | |
422 | * occurred, try to recover and print a warning to the end | |
423 | * user because the user planted a breakpoint in a place that | |
424 | * KGDB needs in order to function. | |
425 | */ | |
53197fc4 | 426 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
427 | exception_level = 0; |
428 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 429 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
430 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
431 | addr); | |
dc7d5527 JW |
432 | WARN_ON_ONCE(1); |
433 | ||
434 | return 1; | |
435 | } | |
53197fc4 | 436 | dbg_remove_all_break(); |
dc7d5527 JW |
437 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
438 | ||
439 | if (exception_level > 1) { | |
440 | dump_stack(); | |
441 | panic("Recursive entry to debugger"); | |
442 | } | |
443 | ||
444 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
6d906340 JW |
445 | #ifdef CONFIG_KGDB_KDB |
446 | /* Allow kdb to debug itself one level */ | |
447 | return 0; | |
448 | #endif | |
dc7d5527 JW |
449 | dump_stack(); |
450 | panic("Recursive entry to debugger"); | |
451 | ||
452 | return 1; | |
453 | } | |
454 | ||
16cdc628 JW |
455 | static void dbg_touch_watchdogs(void) |
456 | { | |
457 | touch_softlockup_watchdog_sync(); | |
458 | clocksource_touch_watchdog(); | |
fb70b588 | 459 | rcu_cpu_stall_reset(); |
16cdc628 JW |
460 | } |
461 | ||
dfee3a7b JW |
462 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
463 | int exception_state) | |
dc7d5527 | 464 | { |
dc7d5527 | 465 | unsigned long flags; |
028e7b17 | 466 | int sstep_tries = 100; |
dcc78711 | 467 | int error; |
dfee3a7b | 468 | int cpu; |
4da75b9c | 469 | int trace_on = 0; |
dfee3a7b | 470 | int online_cpus = num_online_cpus(); |
c1bb9a9c | 471 | |
dfee3a7b JW |
472 | kgdb_info[ks->cpu].enter_kgdb++; |
473 | kgdb_info[ks->cpu].exception_state |= exception_state; | |
474 | ||
475 | if (exception_state == DCPU_WANT_MASTER) | |
476 | atomic_inc(&masters_in_kgdb); | |
477 | else | |
478 | atomic_inc(&slaves_in_kgdb); | |
d7ba979d DD |
479 | |
480 | if (arch_kgdb_ops.disable_hw_break) | |
481 | arch_kgdb_ops.disable_hw_break(regs); | |
c1bb9a9c | 482 | |
dc7d5527 JW |
483 | acquirelock: |
484 | /* | |
485 | * Interrupts will be restored by the 'trap return' code, except when | |
486 | * single stepping. | |
487 | */ | |
488 | local_irq_save(flags); | |
489 | ||
62fae312 JW |
490 | cpu = ks->cpu; |
491 | kgdb_info[cpu].debuggerinfo = regs; | |
492 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
493 | kgdb_info[cpu].ret_state = 0; |
494 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
dc7d5527 | 495 | |
dfee3a7b JW |
496 | /* Make sure the above info reaches the primary CPU */ |
497 | smp_mb(); | |
498 | ||
499 | if (exception_level == 1) { | |
500 | if (raw_spin_trylock(&dbg_master_lock)) | |
501 | atomic_xchg(&kgdb_active, cpu); | |
6d906340 | 502 | goto cpu_master_loop; |
dfee3a7b | 503 | } |
6d906340 | 504 | |
dc7d5527 | 505 | /* |
62fae312 JW |
506 | * CPU will loop if it is a slave or request to become a kgdb |
507 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 508 | */ |
62fae312 | 509 | while (1) { |
dcc78711 JW |
510 | cpu_loop: |
511 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { | |
512 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; | |
513 | goto cpu_master_loop; | |
514 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
dfee3a7b JW |
515 | if (raw_spin_trylock(&dbg_master_lock)) { |
516 | atomic_xchg(&kgdb_active, cpu); | |
62fae312 | 517 | break; |
dfee3a7b | 518 | } |
62fae312 | 519 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
dfee3a7b | 520 | if (!raw_spin_is_locked(&dbg_slave_lock)) |
62fae312 JW |
521 | goto return_normal; |
522 | } else { | |
523 | return_normal: | |
524 | /* Return to normal operation by executing any | |
525 | * hw breakpoint fixup. | |
526 | */ | |
527 | if (arch_kgdb_ops.correct_hw_break) | |
528 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
529 | if (trace_on) |
530 | tracing_on(); | |
dfee3a7b JW |
531 | kgdb_info[cpu].exception_state &= |
532 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
533 | kgdb_info[cpu].enter_kgdb--; | |
534 | smp_mb__before_atomic_dec(); | |
535 | atomic_dec(&slaves_in_kgdb); | |
16cdc628 | 536 | dbg_touch_watchdogs(); |
62fae312 JW |
537 | local_irq_restore(flags); |
538 | return 0; | |
539 | } | |
dc7d5527 | 540 | cpu_relax(); |
62fae312 | 541 | } |
dc7d5527 JW |
542 | |
543 | /* | |
028e7b17 | 544 | * For single stepping, try to only enter on the processor |
25985edc | 545 | * that was single stepping. To guard against a deadlock, the |
028e7b17 JW |
546 | * kernel will only try for the value of sstep_tries before |
547 | * giving up and continuing on. | |
dc7d5527 JW |
548 | */ |
549 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
550 | (kgdb_info[cpu].task && |
551 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 552 | atomic_set(&kgdb_active, -1); |
dfee3a7b | 553 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 554 | dbg_touch_watchdogs(); |
dc7d5527 JW |
555 | local_irq_restore(flags); |
556 | ||
557 | goto acquirelock; | |
558 | } | |
559 | ||
560 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 561 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 562 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
563 | } |
564 | ||
565 | /* | |
566 | * Don't enter if we have hit a removed breakpoint. | |
567 | */ | |
568 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
569 | goto kgdb_restore; | |
570 | ||
571 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
572 | if (dbg_io_ops->pre_exception) |
573 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 574 | |
dc7d5527 JW |
575 | /* |
576 | * Get the passive CPU lock which will hold all the non-primary | |
577 | * CPU in a spin state while the debugger is active | |
578 | */ | |
dfee3a7b JW |
579 | if (!kgdb_single_step) |
580 | raw_spin_lock(&dbg_slave_lock); | |
dc7d5527 | 581 | |
56fb7093 JW |
582 | #ifdef CONFIG_SMP |
583 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 584 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
585 | kgdb_roundup_cpus(flags); |
586 | #endif | |
587 | ||
dc7d5527 JW |
588 | /* |
589 | * Wait for the other CPUs to be notified and be waiting for us: | |
590 | */ | |
dfee3a7b JW |
591 | while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + |
592 | atomic_read(&slaves_in_kgdb)) != online_cpus) | |
593 | cpu_relax(); | |
dc7d5527 JW |
594 | |
595 | /* | |
596 | * At this point the primary processor is completely | |
597 | * in the debugger and all secondary CPUs are quiescent | |
598 | */ | |
dcc78711 | 599 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 600 | kgdb_single_step = 0; |
d7161a65 | 601 | kgdb_contthread = current; |
dc7d5527 | 602 | exception_level = 0; |
4da75b9c JW |
603 | trace_on = tracing_is_on(); |
604 | if (trace_on) | |
605 | tracing_off(); | |
dc7d5527 | 606 | |
dcc78711 JW |
607 | while (1) { |
608 | cpu_master_loop: | |
609 | if (dbg_kdb_mode) { | |
610 | kgdb_connected = 1; | |
611 | error = kdb_stub(ks); | |
3fa43aba JW |
612 | if (error == -1) |
613 | continue; | |
b0679c63 | 614 | kgdb_connected = 0; |
dcc78711 JW |
615 | } else { |
616 | error = gdb_serial_stub(ks); | |
617 | } | |
618 | ||
619 | if (error == DBG_PASS_EVENT) { | |
620 | dbg_kdb_mode = !dbg_kdb_mode; | |
dcc78711 | 621 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
495363d3 JW |
622 | kgdb_info[dbg_switch_cpu].exception_state |= |
623 | DCPU_NEXT_MASTER; | |
dcc78711 JW |
624 | goto cpu_loop; |
625 | } else { | |
626 | kgdb_info[cpu].ret_state = error; | |
627 | break; | |
628 | } | |
629 | } | |
dc7d5527 JW |
630 | |
631 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
632 | if (dbg_io_ops->post_exception) |
633 | dbg_io_ops->post_exception(); | |
dc7d5527 | 634 | |
d7161a65 | 635 | if (!kgdb_single_step) { |
dfee3a7b JW |
636 | raw_spin_unlock(&dbg_slave_lock); |
637 | /* Wait till all the CPUs have quit from the debugger. */ | |
638 | while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) | |
639 | cpu_relax(); | |
dc7d5527 JW |
640 | } |
641 | ||
642 | kgdb_restore: | |
028e7b17 JW |
643 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
644 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
645 | if (kgdb_info[sstep_cpu].task) | |
646 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
647 | else | |
648 | kgdb_sstep_pid = 0; | |
649 | } | |
c1bb9a9c DD |
650 | if (arch_kgdb_ops.correct_hw_break) |
651 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
652 | if (trace_on) |
653 | tracing_on(); | |
dfee3a7b JW |
654 | |
655 | kgdb_info[cpu].exception_state &= | |
656 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
657 | kgdb_info[cpu].enter_kgdb--; | |
658 | smp_mb__before_atomic_dec(); | |
659 | atomic_dec(&masters_in_kgdb); | |
dc7d5527 JW |
660 | /* Free kgdb_active */ |
661 | atomic_set(&kgdb_active, -1); | |
dfee3a7b | 662 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 663 | dbg_touch_watchdogs(); |
dc7d5527 JW |
664 | local_irq_restore(flags); |
665 | ||
dcc78711 | 666 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
667 | } |
668 | ||
62fae312 JW |
669 | /* |
670 | * kgdb_handle_exception() - main entry point from a kernel exception | |
671 | * | |
672 | * Locking hierarchy: | |
673 | * interface locks, if any (begin_session) | |
674 | * kgdb lock (kgdb_active) | |
675 | */ | |
676 | int | |
677 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
678 | { | |
679 | struct kgdb_state kgdb_var; | |
680 | struct kgdb_state *ks = &kgdb_var; | |
62fae312 JW |
681 | |
682 | ks->cpu = raw_smp_processor_id(); | |
683 | ks->ex_vector = evector; | |
684 | ks->signo = signo; | |
62fae312 JW |
685 | ks->err_code = ecode; |
686 | ks->kgdb_usethreadid = 0; | |
687 | ks->linux_regs = regs; | |
688 | ||
689 | if (kgdb_reenter_check(ks)) | |
690 | return 0; /* Ouch, double exception ! */ | |
dfee3a7b JW |
691 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
692 | return 0; | |
693 | ||
694 | return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); | |
62fae312 JW |
695 | } |
696 | ||
dc7d5527 JW |
697 | int kgdb_nmicallback(int cpu, void *regs) |
698 | { | |
699 | #ifdef CONFIG_SMP | |
62fae312 JW |
700 | struct kgdb_state kgdb_var; |
701 | struct kgdb_state *ks = &kgdb_var; | |
702 | ||
703 | memset(ks, 0, sizeof(struct kgdb_state)); | |
704 | ks->cpu = cpu; | |
705 | ks->linux_regs = regs; | |
706 | ||
dfee3a7b JW |
707 | if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
708 | raw_spin_is_locked(&dbg_master_lock)) { | |
709 | kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); | |
dc7d5527 JW |
710 | return 0; |
711 | } | |
712 | #endif | |
713 | return 1; | |
714 | } | |
715 | ||
aabdc3b8 JW |
716 | static void kgdb_console_write(struct console *co, const char *s, |
717 | unsigned count) | |
dc7d5527 JW |
718 | { |
719 | unsigned long flags; | |
720 | ||
721 | /* If we're debugging, or KGDB has not connected, don't try | |
722 | * and print. */ | |
dcc78711 | 723 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
724 | return; |
725 | ||
726 | local_irq_save(flags); | |
53197fc4 | 727 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
728 | local_irq_restore(flags); |
729 | } | |
730 | ||
731 | static struct console kgdbcons = { | |
732 | .name = "kgdb", | |
733 | .write = kgdb_console_write, | |
734 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
735 | .index = -1, | |
736 | }; | |
737 | ||
738 | #ifdef CONFIG_MAGIC_SYSRQ | |
1495cc9d | 739 | static void sysrq_handle_dbg(int key) |
dc7d5527 | 740 | { |
53197fc4 | 741 | if (!dbg_io_ops) { |
dc7d5527 JW |
742 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
743 | return; | |
744 | } | |
dcc78711 JW |
745 | if (!kgdb_connected) { |
746 | #ifdef CONFIG_KGDB_KDB | |
747 | if (!dbg_kdb_mode) | |
748 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
749 | #else | |
dc7d5527 | 750 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
751 | #endif |
752 | } | |
dc7d5527 JW |
753 | |
754 | kgdb_breakpoint(); | |
755 | } | |
756 | ||
53197fc4 JW |
757 | static struct sysrq_key_op sysrq_dbg_op = { |
758 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
759 | .help_msg = "debug(G)", |
760 | .action_msg = "DEBUG", | |
dc7d5527 JW |
761 | }; |
762 | #endif | |
763 | ||
4402c153 JW |
764 | static int kgdb_panic_event(struct notifier_block *self, |
765 | unsigned long val, | |
766 | void *data) | |
767 | { | |
768 | if (dbg_kdb_mode) | |
769 | kdb_printf("PANIC: %s\n", (char *)data); | |
770 | kgdb_breakpoint(); | |
771 | return NOTIFY_DONE; | |
772 | } | |
773 | ||
774 | static struct notifier_block kgdb_panic_event_nb = { | |
775 | .notifier_call = kgdb_panic_event, | |
776 | .priority = INT_MAX, | |
777 | }; | |
778 | ||
0b4b3827 JW |
779 | void __weak kgdb_arch_late(void) |
780 | { | |
781 | } | |
782 | ||
783 | void __init dbg_late_init(void) | |
784 | { | |
785 | dbg_is_early = false; | |
786 | if (kgdb_io_module_registered) | |
787 | kgdb_arch_late(); | |
788 | kdb_init(KDB_INIT_FULL); | |
789 | } | |
790 | ||
2366e047 JW |
791 | static int |
792 | dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x) | |
793 | { | |
bec4d62e JW |
794 | /* |
795 | * Take the following action on reboot notify depending on value: | |
796 | * 1 == Enter debugger | |
797 | * 0 == [the default] detatch debug client | |
798 | * -1 == Do nothing... and use this until the board resets | |
799 | */ | |
800 | switch (kgdbreboot) { | |
801 | case 1: | |
802 | kgdb_breakpoint(); | |
803 | case -1: | |
804 | goto done; | |
805 | } | |
2366e047 JW |
806 | if (!dbg_kdb_mode) |
807 | gdbstub_exit(code); | |
bec4d62e | 808 | done: |
2366e047 JW |
809 | return NOTIFY_DONE; |
810 | } | |
811 | ||
812 | static struct notifier_block dbg_reboot_notifier = { | |
813 | .notifier_call = dbg_notify_reboot, | |
814 | .next = NULL, | |
815 | .priority = INT_MAX, | |
816 | }; | |
817 | ||
dc7d5527 JW |
818 | static void kgdb_register_callbacks(void) |
819 | { | |
820 | if (!kgdb_io_module_registered) { | |
821 | kgdb_io_module_registered = 1; | |
822 | kgdb_arch_init(); | |
0b4b3827 JW |
823 | if (!dbg_is_early) |
824 | kgdb_arch_late(); | |
2366e047 | 825 | register_reboot_notifier(&dbg_reboot_notifier); |
4402c153 JW |
826 | atomic_notifier_chain_register(&panic_notifier_list, |
827 | &kgdb_panic_event_nb); | |
dc7d5527 | 828 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 829 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
830 | #endif |
831 | if (kgdb_use_con && !kgdb_con_registered) { | |
832 | register_console(&kgdbcons); | |
833 | kgdb_con_registered = 1; | |
834 | } | |
835 | } | |
836 | } | |
837 | ||
838 | static void kgdb_unregister_callbacks(void) | |
839 | { | |
840 | /* | |
841 | * When this routine is called KGDB should unregister from the | |
842 | * panic handler and clean up, making sure it is not handling any | |
843 | * break exceptions at the time. | |
844 | */ | |
845 | if (kgdb_io_module_registered) { | |
846 | kgdb_io_module_registered = 0; | |
2366e047 | 847 | unregister_reboot_notifier(&dbg_reboot_notifier); |
4402c153 JW |
848 | atomic_notifier_chain_unregister(&panic_notifier_list, |
849 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
850 | kgdb_arch_exit(); |
851 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 852 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
853 | #endif |
854 | if (kgdb_con_registered) { | |
855 | unregister_console(&kgdbcons); | |
856 | kgdb_con_registered = 0; | |
857 | } | |
858 | } | |
859 | } | |
860 | ||
1cee5e35 JW |
861 | /* |
862 | * There are times a tasklet needs to be used vs a compiled in | |
863 | * break point so as to cause an exception outside a kgdb I/O module, | |
864 | * such as is the case with kgdboe, where calling a breakpoint in the | |
865 | * I/O driver itself would be fatal. | |
866 | */ | |
867 | static void kgdb_tasklet_bpt(unsigned long ing) | |
868 | { | |
869 | kgdb_breakpoint(); | |
870 | atomic_set(&kgdb_break_tasklet_var, 0); | |
871 | } | |
872 | ||
873 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); | |
874 | ||
875 | void kgdb_schedule_breakpoint(void) | |
876 | { | |
877 | if (atomic_read(&kgdb_break_tasklet_var) || | |
878 | atomic_read(&kgdb_active) != -1 || | |
879 | atomic_read(&kgdb_setting_breakpoint)) | |
880 | return; | |
881 | atomic_inc(&kgdb_break_tasklet_var); | |
882 | tasklet_schedule(&kgdb_tasklet_breakpoint); | |
883 | } | |
884 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); | |
885 | ||
dc7d5527 JW |
886 | static void kgdb_initial_breakpoint(void) |
887 | { | |
888 | kgdb_break_asap = 0; | |
889 | ||
890 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
891 | kgdb_breakpoint(); | |
892 | } | |
893 | ||
894 | /** | |
737a460f | 895 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 896 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
897 | * |
898 | * Register it with the KGDB core. | |
899 | */ | |
53197fc4 | 900 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
901 | { |
902 | int err; | |
903 | ||
904 | spin_lock(&kgdb_registration_lock); | |
905 | ||
53197fc4 | 906 | if (dbg_io_ops) { |
dc7d5527 JW |
907 | spin_unlock(&kgdb_registration_lock); |
908 | ||
909 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
910 | "registered with KGDB.\n"); | |
911 | return -EBUSY; | |
912 | } | |
913 | ||
53197fc4 JW |
914 | if (new_dbg_io_ops->init) { |
915 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
916 | if (err) { |
917 | spin_unlock(&kgdb_registration_lock); | |
918 | return err; | |
919 | } | |
920 | } | |
921 | ||
53197fc4 | 922 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
923 | |
924 | spin_unlock(&kgdb_registration_lock); | |
925 | ||
926 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 927 | new_dbg_io_ops->name); |
dc7d5527 JW |
928 | |
929 | /* Arm KGDB now. */ | |
930 | kgdb_register_callbacks(); | |
931 | ||
932 | if (kgdb_break_asap) | |
933 | kgdb_initial_breakpoint(); | |
934 | ||
935 | return 0; | |
936 | } | |
937 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
938 | ||
939 | /** | |
940 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 941 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
942 | * |
943 | * Unregister it with the KGDB core. | |
944 | */ | |
53197fc4 | 945 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
946 | { |
947 | BUG_ON(kgdb_connected); | |
948 | ||
949 | /* | |
950 | * KGDB is no longer able to communicate out, so | |
951 | * unregister our callbacks and reset state. | |
952 | */ | |
953 | kgdb_unregister_callbacks(); | |
954 | ||
955 | spin_lock(&kgdb_registration_lock); | |
956 | ||
53197fc4 JW |
957 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
958 | dbg_io_ops = NULL; | |
dc7d5527 JW |
959 | |
960 | spin_unlock(&kgdb_registration_lock); | |
961 | ||
962 | printk(KERN_INFO | |
963 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 964 | old_dbg_io_ops->name); |
dc7d5527 JW |
965 | } |
966 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
967 | ||
dcc78711 JW |
968 | int dbg_io_get_char(void) |
969 | { | |
970 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
971 | if (ret == NO_POLL_CHAR) |
972 | return -1; | |
dcc78711 JW |
973 | if (!dbg_kdb_mode) |
974 | return ret; | |
975 | if (ret == 127) | |
976 | return 8; | |
977 | return ret; | |
978 | } | |
979 | ||
dc7d5527 JW |
980 | /** |
981 | * kgdb_breakpoint - generate breakpoint exception | |
982 | * | |
983 | * This function will generate a breakpoint exception. It is used at the | |
984 | * beginning of a program to sync up with a debugger and can be used | |
985 | * otherwise as a quick means to stop program execution and "break" into | |
986 | * the debugger. | |
987 | */ | |
988 | void kgdb_breakpoint(void) | |
989 | { | |
ae6bf53e | 990 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
991 | wmb(); /* Sync point before breakpoint */ |
992 | arch_kgdb_breakpoint(); | |
993 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 994 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
995 | } |
996 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
997 | ||
998 | static int __init opt_kgdb_wait(char *str) | |
999 | { | |
1000 | kgdb_break_asap = 1; | |
1001 | ||
dcc78711 | 1002 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
1003 | if (kgdb_io_module_registered) |
1004 | kgdb_initial_breakpoint(); | |
1005 | ||
1006 | return 0; | |
1007 | } | |
1008 | ||
1009 | early_param("kgdbwait", opt_kgdb_wait); |