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> | |
44 | #include <linux/init.h> | |
45 | #include <linux/kgdb.h> | |
dcc78711 | 46 | #include <linux/kdb.h> |
dc7d5527 JW |
47 | #include <linux/pid.h> |
48 | #include <linux/smp.h> | |
49 | #include <linux/mm.h> | |
fb70b588 | 50 | #include <linux/rcupdate.h> |
dc7d5527 JW |
51 | |
52 | #include <asm/cacheflush.h> | |
53 | #include <asm/byteorder.h> | |
60063497 | 54 | #include <linux/atomic.h> |
dc7d5527 JW |
55 | #include <asm/system.h> |
56 | ||
53197fc4 | 57 | #include "debug_core.h" |
dc7d5527 | 58 | |
53197fc4 | 59 | static int kgdb_break_asap; |
62fae312 | 60 | |
53197fc4 | 61 | struct debuggerinfo_struct kgdb_info[NR_CPUS]; |
dc7d5527 JW |
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 */ | |
f503b5ae | 70 | int kgdb_io_module_registered; |
dc7d5527 JW |
71 | |
72 | /* Guard for recursive entry */ | |
73 | static int exception_level; | |
74 | ||
53197fc4 | 75 | struct kgdb_io *dbg_io_ops; |
dc7d5527 JW |
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; | |
0b4b3827 JW |
82 | /* Flag for alternate operations for early debugging */ |
83 | bool dbg_is_early = true; | |
dcc78711 JW |
84 | /* Next cpu to become the master debug core */ |
85 | int dbg_switch_cpu; | |
86 | ||
87 | /* Use kdb or gdbserver mode */ | |
a0de055c | 88 | int dbg_kdb_mode = 1; |
dc7d5527 JW |
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); | |
dcc78711 | 112 | EXPORT_SYMBOL_GPL(kgdb_active); |
dfee3a7b JW |
113 | static DEFINE_RAW_SPINLOCK(dbg_master_lock); |
114 | static DEFINE_RAW_SPINLOCK(dbg_slave_lock); | |
dc7d5527 JW |
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 | */ | |
dfee3a7b JW |
120 | static atomic_t masters_in_kgdb; |
121 | static atomic_t slaves_in_kgdb; | |
1cee5e35 | 122 | static atomic_t kgdb_break_tasklet_var; |
dc7d5527 JW |
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; | |
53197fc4 | 129 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
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 | */ | |
688b744d | 141 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
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 | */ | |
dc7d5527 JW |
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 | ||
a9b60bf4 JW |
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 | ||
dc7d5527 JW |
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 | ||
b4b8ac52 JW |
207 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
208 | { | |
209 | return 0; | |
210 | } | |
211 | ||
dc7d5527 JW |
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 | ||
737a460f | 221 | if (current->mm && current->mm->mmap_cache) { |
dc7d5527 JW |
222 | flush_cache_range(current->mm->mmap_cache, |
223 | addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 | 224 | } |
1a9a3e76 JW |
225 | /* Force flush instruction cache if it was outside the mm */ |
226 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 JW |
227 | } |
228 | ||
229 | /* | |
230 | * SW breakpoint management: | |
231 | */ | |
53197fc4 | 232 | int dbg_activate_sw_breakpoints(void) |
dc7d5527 JW |
233 | { |
234 | unsigned long addr; | |
7f8b7ed6 JW |
235 | int error; |
236 | int ret = 0; | |
dc7d5527 JW |
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); | |
7f8b7ed6 JW |
246 | if (error) { |
247 | ret = error; | |
248 | printk(KERN_INFO "KGDB: BP install failed: %lx", addr); | |
249 | continue; | |
250 | } | |
dc7d5527 JW |
251 | |
252 | kgdb_flush_swbreak_addr(addr); | |
253 | kgdb_break[i].state = BP_ACTIVE; | |
254 | } | |
7f8b7ed6 | 255 | return ret; |
dc7d5527 JW |
256 | } |
257 | ||
53197fc4 | 258 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
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 | ||
dcc78711 | 299 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 JW |
300 | { |
301 | unsigned long addr; | |
7f8b7ed6 JW |
302 | int error; |
303 | int ret = 0; | |
dc7d5527 JW |
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); | |
7f8b7ed6 JW |
312 | if (error) { |
313 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr); | |
314 | ret = error; | |
315 | } | |
dc7d5527 JW |
316 | |
317 | kgdb_flush_swbreak_addr(addr); | |
318 | kgdb_break[i].state = BP_SET; | |
319 | } | |
7f8b7ed6 | 320 | return ret; |
dc7d5527 JW |
321 | } |
322 | ||
53197fc4 | 323 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
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 | ||
53197fc4 | 349 | int dbg_remove_all_break(void) |
dc7d5527 JW |
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++) { | |
737a460f JW |
357 | if (kgdb_break[i].state != BP_ACTIVE) |
358 | goto setundefined; | |
dc7d5527 JW |
359 | addr = kgdb_break[i].bpt_addr; |
360 | error = kgdb_arch_remove_breakpoint(addr, | |
361 | kgdb_break[i].saved_instr); | |
362 | if (error) | |
737a460f JW |
363 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
364 | addr); | |
365 | setundefined: | |
366 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
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 | ||
dc7d5527 JW |
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 | { | |
53197fc4 | 387 | if (!dbg_io_ops) |
dc7d5527 JW |
388 | return 0; |
389 | if (kgdb_connected) | |
390 | return 1; | |
391 | if (atomic_read(&kgdb_setting_breakpoint)) | |
392 | return 1; | |
dcc78711 JW |
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 | |
dc7d5527 | 398 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
399 | #endif |
400 | } | |
dc7d5527 JW |
401 | return 1; |
402 | } | |
403 | ||
dc7d5527 JW |
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); | |
dcc78711 | 414 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
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 | */ | |
53197fc4 | 422 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
423 | exception_level = 0; |
424 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 425 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
426 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
427 | addr); | |
dc7d5527 JW |
428 | WARN_ON_ONCE(1); |
429 | ||
430 | return 1; | |
431 | } | |
53197fc4 | 432 | dbg_remove_all_break(); |
dc7d5527 JW |
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"); | |
6d906340 JW |
441 | #ifdef CONFIG_KGDB_KDB |
442 | /* Allow kdb to debug itself one level */ | |
443 | return 0; | |
444 | #endif | |
dc7d5527 JW |
445 | dump_stack(); |
446 | panic("Recursive entry to debugger"); | |
447 | ||
448 | return 1; | |
449 | } | |
450 | ||
16cdc628 JW |
451 | static void dbg_touch_watchdogs(void) |
452 | { | |
453 | touch_softlockup_watchdog_sync(); | |
454 | clocksource_touch_watchdog(); | |
fb70b588 | 455 | rcu_cpu_stall_reset(); |
16cdc628 JW |
456 | } |
457 | ||
dfee3a7b JW |
458 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
459 | int exception_state) | |
dc7d5527 | 460 | { |
dc7d5527 | 461 | unsigned long flags; |
028e7b17 | 462 | int sstep_tries = 100; |
dcc78711 | 463 | int error; |
dfee3a7b | 464 | int cpu; |
4da75b9c | 465 | int trace_on = 0; |
dfee3a7b | 466 | int online_cpus = num_online_cpus(); |
c1bb9a9c | 467 | |
dfee3a7b JW |
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); | |
d7ba979d DD |
475 | |
476 | if (arch_kgdb_ops.disable_hw_break) | |
477 | arch_kgdb_ops.disable_hw_break(regs); | |
c1bb9a9c | 478 | |
dc7d5527 JW |
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 | ||
62fae312 JW |
486 | cpu = ks->cpu; |
487 | kgdb_info[cpu].debuggerinfo = regs; | |
488 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
489 | kgdb_info[cpu].ret_state = 0; |
490 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
dc7d5527 | 491 | |
dfee3a7b JW |
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); | |
6d906340 | 498 | goto cpu_master_loop; |
dfee3a7b | 499 | } |
6d906340 | 500 | |
dc7d5527 | 501 | /* |
62fae312 JW |
502 | * CPU will loop if it is a slave or request to become a kgdb |
503 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 504 | */ |
62fae312 | 505 | while (1) { |
dcc78711 JW |
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) { | |
dfee3a7b JW |
511 | if (raw_spin_trylock(&dbg_master_lock)) { |
512 | atomic_xchg(&kgdb_active, cpu); | |
62fae312 | 513 | break; |
dfee3a7b | 514 | } |
62fae312 | 515 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
dfee3a7b | 516 | if (!raw_spin_is_locked(&dbg_slave_lock)) |
62fae312 JW |
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(); | |
4da75b9c JW |
525 | if (trace_on) |
526 | tracing_on(); | |
dfee3a7b JW |
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); | |
16cdc628 | 532 | dbg_touch_watchdogs(); |
62fae312 JW |
533 | local_irq_restore(flags); |
534 | return 0; | |
535 | } | |
dc7d5527 | 536 | cpu_relax(); |
62fae312 | 537 | } |
dc7d5527 JW |
538 | |
539 | /* | |
028e7b17 | 540 | * For single stepping, try to only enter on the processor |
25985edc | 541 | * that was single stepping. To guard against a deadlock, the |
028e7b17 JW |
542 | * kernel will only try for the value of sstep_tries before |
543 | * giving up and continuing on. | |
dc7d5527 JW |
544 | */ |
545 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
546 | (kgdb_info[cpu].task && |
547 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 548 | atomic_set(&kgdb_active, -1); |
dfee3a7b | 549 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 550 | dbg_touch_watchdogs(); |
dc7d5527 JW |
551 | local_irq_restore(flags); |
552 | ||
553 | goto acquirelock; | |
554 | } | |
555 | ||
556 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 557 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 558 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
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 */ | |
53197fc4 JW |
568 | if (dbg_io_ops->pre_exception) |
569 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 570 | |
dc7d5527 JW |
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 | */ | |
dfee3a7b JW |
575 | if (!kgdb_single_step) |
576 | raw_spin_lock(&dbg_slave_lock); | |
dc7d5527 | 577 | |
56fb7093 JW |
578 | #ifdef CONFIG_SMP |
579 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 580 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
581 | kgdb_roundup_cpus(flags); |
582 | #endif | |
583 | ||
dc7d5527 JW |
584 | /* |
585 | * Wait for the other CPUs to be notified and be waiting for us: | |
586 | */ | |
dfee3a7b JW |
587 | while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + |
588 | atomic_read(&slaves_in_kgdb)) != online_cpus) | |
589 | cpu_relax(); | |
dc7d5527 JW |
590 | |
591 | /* | |
592 | * At this point the primary processor is completely | |
593 | * in the debugger and all secondary CPUs are quiescent | |
594 | */ | |
dcc78711 | 595 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 596 | kgdb_single_step = 0; |
d7161a65 | 597 | kgdb_contthread = current; |
dc7d5527 | 598 | exception_level = 0; |
4da75b9c JW |
599 | trace_on = tracing_is_on(); |
600 | if (trace_on) | |
601 | tracing_off(); | |
dc7d5527 | 602 | |
dcc78711 JW |
603 | while (1) { |
604 | cpu_master_loop: | |
605 | if (dbg_kdb_mode) { | |
606 | kgdb_connected = 1; | |
607 | error = kdb_stub(ks); | |
3fa43aba JW |
608 | if (error == -1) |
609 | continue; | |
b0679c63 | 610 | kgdb_connected = 0; |
dcc78711 JW |
611 | } else { |
612 | error = gdb_serial_stub(ks); | |
613 | } | |
614 | ||
615 | if (error == DBG_PASS_EVENT) { | |
616 | dbg_kdb_mode = !dbg_kdb_mode; | |
dcc78711 | 617 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
495363d3 JW |
618 | kgdb_info[dbg_switch_cpu].exception_state |= |
619 | DCPU_NEXT_MASTER; | |
dcc78711 JW |
620 | goto cpu_loop; |
621 | } else { | |
622 | kgdb_info[cpu].ret_state = error; | |
623 | break; | |
624 | } | |
625 | } | |
dc7d5527 JW |
626 | |
627 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
628 | if (dbg_io_ops->post_exception) |
629 | dbg_io_ops->post_exception(); | |
dc7d5527 | 630 | |
d7161a65 | 631 | if (!kgdb_single_step) { |
dfee3a7b JW |
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(); | |
dc7d5527 JW |
636 | } |
637 | ||
638 | kgdb_restore: | |
028e7b17 JW |
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 | } | |
c1bb9a9c DD |
646 | if (arch_kgdb_ops.correct_hw_break) |
647 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
648 | if (trace_on) |
649 | tracing_on(); | |
dfee3a7b JW |
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); | |
dc7d5527 JW |
656 | /* Free kgdb_active */ |
657 | atomic_set(&kgdb_active, -1); | |
dfee3a7b | 658 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 659 | dbg_touch_watchdogs(); |
dc7d5527 JW |
660 | local_irq_restore(flags); |
661 | ||
dcc78711 | 662 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
663 | } |
664 | ||
62fae312 JW |
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; | |
62fae312 JW |
677 | |
678 | ks->cpu = raw_smp_processor_id(); | |
679 | ks->ex_vector = evector; | |
680 | ks->signo = signo; | |
62fae312 JW |
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 ! */ | |
dfee3a7b JW |
687 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
688 | return 0; | |
689 | ||
690 | return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); | |
62fae312 JW |
691 | } |
692 | ||
dc7d5527 JW |
693 | int kgdb_nmicallback(int cpu, void *regs) |
694 | { | |
695 | #ifdef CONFIG_SMP | |
62fae312 JW |
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 | ||
dfee3a7b JW |
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); | |
dc7d5527 JW |
706 | return 0; |
707 | } | |
708 | #endif | |
709 | return 1; | |
710 | } | |
711 | ||
aabdc3b8 JW |
712 | static void kgdb_console_write(struct console *co, const char *s, |
713 | unsigned count) | |
dc7d5527 JW |
714 | { |
715 | unsigned long flags; | |
716 | ||
717 | /* If we're debugging, or KGDB has not connected, don't try | |
718 | * and print. */ | |
dcc78711 | 719 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
720 | return; |
721 | ||
722 | local_irq_save(flags); | |
53197fc4 | 723 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
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 | |
1495cc9d | 735 | static void sysrq_handle_dbg(int key) |
dc7d5527 | 736 | { |
53197fc4 | 737 | if (!dbg_io_ops) { |
dc7d5527 JW |
738 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
739 | return; | |
740 | } | |
dcc78711 JW |
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 | |
dc7d5527 | 746 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
747 | #endif |
748 | } | |
dc7d5527 JW |
749 | |
750 | kgdb_breakpoint(); | |
751 | } | |
752 | ||
53197fc4 JW |
753 | static struct sysrq_key_op sysrq_dbg_op = { |
754 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
755 | .help_msg = "debug(G)", |
756 | .action_msg = "DEBUG", | |
dc7d5527 JW |
757 | }; |
758 | #endif | |
759 | ||
4402c153 JW |
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 | ||
0b4b3827 JW |
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 | ||
dc7d5527 JW |
787 | static void kgdb_register_callbacks(void) |
788 | { | |
789 | if (!kgdb_io_module_registered) { | |
790 | kgdb_io_module_registered = 1; | |
791 | kgdb_arch_init(); | |
0b4b3827 JW |
792 | if (!dbg_is_early) |
793 | kgdb_arch_late(); | |
4402c153 JW |
794 | atomic_notifier_chain_register(&panic_notifier_list, |
795 | &kgdb_panic_event_nb); | |
dc7d5527 | 796 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 797 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
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; | |
4402c153 JW |
815 | atomic_notifier_chain_unregister(&panic_notifier_list, |
816 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
817 | kgdb_arch_exit(); |
818 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 819 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
820 | #endif |
821 | if (kgdb_con_registered) { | |
822 | unregister_console(&kgdbcons); | |
823 | kgdb_con_registered = 0; | |
824 | } | |
825 | } | |
826 | } | |
827 | ||
1cee5e35 JW |
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 | ||
dc7d5527 JW |
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 | /** | |
737a460f | 862 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 863 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
864 | * |
865 | * Register it with the KGDB core. | |
866 | */ | |
53197fc4 | 867 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
868 | { |
869 | int err; | |
870 | ||
871 | spin_lock(&kgdb_registration_lock); | |
872 | ||
53197fc4 | 873 | if (dbg_io_ops) { |
dc7d5527 JW |
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 | ||
53197fc4 JW |
881 | if (new_dbg_io_ops->init) { |
882 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
883 | if (err) { |
884 | spin_unlock(&kgdb_registration_lock); | |
885 | return err; | |
886 | } | |
887 | } | |
888 | ||
53197fc4 | 889 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
890 | |
891 | spin_unlock(&kgdb_registration_lock); | |
892 | ||
893 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 894 | new_dbg_io_ops->name); |
dc7d5527 JW |
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 | |
53197fc4 | 908 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
909 | * |
910 | * Unregister it with the KGDB core. | |
911 | */ | |
53197fc4 | 912 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
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 | ||
53197fc4 JW |
924 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
925 | dbg_io_ops = NULL; | |
dc7d5527 JW |
926 | |
927 | spin_unlock(&kgdb_registration_lock); | |
928 | ||
929 | printk(KERN_INFO | |
930 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 931 | old_dbg_io_ops->name); |
dc7d5527 JW |
932 | } |
933 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
934 | ||
dcc78711 JW |
935 | int dbg_io_get_char(void) |
936 | { | |
937 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
938 | if (ret == NO_POLL_CHAR) |
939 | return -1; | |
dcc78711 JW |
940 | if (!dbg_kdb_mode) |
941 | return ret; | |
942 | if (ret == 127) | |
943 | return 8; | |
944 | return ret; | |
945 | } | |
946 | ||
dc7d5527 JW |
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 | { | |
ae6bf53e | 957 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
958 | wmb(); /* Sync point before breakpoint */ |
959 | arch_kgdb_breakpoint(); | |
960 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 961 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
962 | } |
963 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
964 | ||
965 | static int __init opt_kgdb_wait(char *str) | |
966 | { | |
967 | kgdb_break_asap = 1; | |
968 | ||
dcc78711 | 969 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
970 | if (kgdb_io_module_registered) |
971 | kgdb_initial_breakpoint(); | |
972 | ||
973 | return 0; | |
974 | } | |
975 | ||
976 | early_param("kgdbwait", opt_kgdb_wait); |