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Commit | Line | Data |
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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> | |
54 | #include <asm/atomic.h> | |
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 | * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. | |
214 | * @regs: Current &struct pt_regs. | |
215 | * | |
216 | * This function will be called if the particular architecture must | |
217 | * disable hardware debugging while it is processing gdb packets or | |
218 | * handling exception. | |
219 | */ | |
220 | void __weak kgdb_disable_hw_debug(struct pt_regs *regs) | |
221 | { | |
222 | } | |
223 | ||
dc7d5527 JW |
224 | /* |
225 | * Some architectures need cache flushes when we set/clear a | |
226 | * breakpoint: | |
227 | */ | |
228 | static void kgdb_flush_swbreak_addr(unsigned long addr) | |
229 | { | |
230 | if (!CACHE_FLUSH_IS_SAFE) | |
231 | return; | |
232 | ||
737a460f | 233 | if (current->mm && current->mm->mmap_cache) { |
dc7d5527 JW |
234 | flush_cache_range(current->mm->mmap_cache, |
235 | addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 | 236 | } |
1a9a3e76 JW |
237 | /* Force flush instruction cache if it was outside the mm */ |
238 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 JW |
239 | } |
240 | ||
241 | /* | |
242 | * SW breakpoint management: | |
243 | */ | |
53197fc4 | 244 | int dbg_activate_sw_breakpoints(void) |
dc7d5527 JW |
245 | { |
246 | unsigned long addr; | |
7f8b7ed6 JW |
247 | int error; |
248 | int ret = 0; | |
dc7d5527 JW |
249 | int i; |
250 | ||
251 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
252 | if (kgdb_break[i].state != BP_SET) | |
253 | continue; | |
254 | ||
255 | addr = kgdb_break[i].bpt_addr; | |
256 | error = kgdb_arch_set_breakpoint(addr, | |
257 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
258 | if (error) { |
259 | ret = error; | |
260 | printk(KERN_INFO "KGDB: BP install failed: %lx", addr); | |
261 | continue; | |
262 | } | |
dc7d5527 JW |
263 | |
264 | kgdb_flush_swbreak_addr(addr); | |
265 | kgdb_break[i].state = BP_ACTIVE; | |
266 | } | |
7f8b7ed6 | 267 | return ret; |
dc7d5527 JW |
268 | } |
269 | ||
53197fc4 | 270 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
271 | { |
272 | int err = kgdb_validate_break_address(addr); | |
273 | int breakno = -1; | |
274 | int i; | |
275 | ||
276 | if (err) | |
277 | return err; | |
278 | ||
279 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
280 | if ((kgdb_break[i].state == BP_SET) && | |
281 | (kgdb_break[i].bpt_addr == addr)) | |
282 | return -EEXIST; | |
283 | } | |
284 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
285 | if (kgdb_break[i].state == BP_REMOVED && | |
286 | kgdb_break[i].bpt_addr == addr) { | |
287 | breakno = i; | |
288 | break; | |
289 | } | |
290 | } | |
291 | ||
292 | if (breakno == -1) { | |
293 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
294 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
295 | breakno = i; | |
296 | break; | |
297 | } | |
298 | } | |
299 | } | |
300 | ||
301 | if (breakno == -1) | |
302 | return -E2BIG; | |
303 | ||
304 | kgdb_break[breakno].state = BP_SET; | |
305 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
306 | kgdb_break[breakno].bpt_addr = addr; | |
307 | ||
308 | return 0; | |
309 | } | |
310 | ||
dcc78711 | 311 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 JW |
312 | { |
313 | unsigned long addr; | |
7f8b7ed6 JW |
314 | int error; |
315 | int ret = 0; | |
dc7d5527 JW |
316 | int i; |
317 | ||
318 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
319 | if (kgdb_break[i].state != BP_ACTIVE) | |
320 | continue; | |
321 | addr = kgdb_break[i].bpt_addr; | |
322 | error = kgdb_arch_remove_breakpoint(addr, | |
323 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
324 | if (error) { |
325 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr); | |
326 | ret = error; | |
327 | } | |
dc7d5527 JW |
328 | |
329 | kgdb_flush_swbreak_addr(addr); | |
330 | kgdb_break[i].state = BP_SET; | |
331 | } | |
7f8b7ed6 | 332 | return ret; |
dc7d5527 JW |
333 | } |
334 | ||
53197fc4 | 335 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
336 | { |
337 | int i; | |
338 | ||
339 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
340 | if ((kgdb_break[i].state == BP_SET) && | |
341 | (kgdb_break[i].bpt_addr == addr)) { | |
342 | kgdb_break[i].state = BP_REMOVED; | |
343 | return 0; | |
344 | } | |
345 | } | |
346 | return -ENOENT; | |
347 | } | |
348 | ||
349 | int kgdb_isremovedbreak(unsigned long addr) | |
350 | { | |
351 | int i; | |
352 | ||
353 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
354 | if ((kgdb_break[i].state == BP_REMOVED) && | |
355 | (kgdb_break[i].bpt_addr == addr)) | |
356 | return 1; | |
357 | } | |
358 | return 0; | |
359 | } | |
360 | ||
53197fc4 | 361 | int dbg_remove_all_break(void) |
dc7d5527 JW |
362 | { |
363 | unsigned long addr; | |
364 | int error; | |
365 | int i; | |
366 | ||
367 | /* Clear memory breakpoints. */ | |
368 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
369 | if (kgdb_break[i].state != BP_ACTIVE) |
370 | goto setundefined; | |
dc7d5527 JW |
371 | addr = kgdb_break[i].bpt_addr; |
372 | error = kgdb_arch_remove_breakpoint(addr, | |
373 | kgdb_break[i].saved_instr); | |
374 | if (error) | |
737a460f JW |
375 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
376 | addr); | |
377 | setundefined: | |
378 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
379 | } |
380 | ||
381 | /* Clear hardware breakpoints. */ | |
382 | if (arch_kgdb_ops.remove_all_hw_break) | |
383 | arch_kgdb_ops.remove_all_hw_break(); | |
384 | ||
385 | return 0; | |
386 | } | |
387 | ||
dc7d5527 JW |
388 | /* |
389 | * Return true if there is a valid kgdb I/O module. Also if no | |
390 | * debugger is attached a message can be printed to the console about | |
391 | * waiting for the debugger to attach. | |
392 | * | |
393 | * The print_wait argument is only to be true when called from inside | |
394 | * the core kgdb_handle_exception, because it will wait for the | |
395 | * debugger to attach. | |
396 | */ | |
397 | static int kgdb_io_ready(int print_wait) | |
398 | { | |
53197fc4 | 399 | if (!dbg_io_ops) |
dc7d5527 JW |
400 | return 0; |
401 | if (kgdb_connected) | |
402 | return 1; | |
403 | if (atomic_read(&kgdb_setting_breakpoint)) | |
404 | return 1; | |
dcc78711 JW |
405 | if (print_wait) { |
406 | #ifdef CONFIG_KGDB_KDB | |
407 | if (!dbg_kdb_mode) | |
408 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); | |
409 | #else | |
dc7d5527 | 410 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
411 | #endif |
412 | } | |
dc7d5527 JW |
413 | return 1; |
414 | } | |
415 | ||
dc7d5527 JW |
416 | static int kgdb_reenter_check(struct kgdb_state *ks) |
417 | { | |
418 | unsigned long addr; | |
419 | ||
420 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
421 | return 0; | |
422 | ||
423 | /* Panic on recursive debugger calls: */ | |
424 | exception_level++; | |
425 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
dcc78711 | 426 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
427 | |
428 | /* | |
429 | * If the break point removed ok at the place exception | |
430 | * occurred, try to recover and print a warning to the end | |
431 | * user because the user planted a breakpoint in a place that | |
432 | * KGDB needs in order to function. | |
433 | */ | |
53197fc4 | 434 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
435 | exception_level = 0; |
436 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 437 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
438 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
439 | addr); | |
dc7d5527 JW |
440 | WARN_ON_ONCE(1); |
441 | ||
442 | return 1; | |
443 | } | |
53197fc4 | 444 | dbg_remove_all_break(); |
dc7d5527 JW |
445 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
446 | ||
447 | if (exception_level > 1) { | |
448 | dump_stack(); | |
449 | panic("Recursive entry to debugger"); | |
450 | } | |
451 | ||
452 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
6d906340 JW |
453 | #ifdef CONFIG_KGDB_KDB |
454 | /* Allow kdb to debug itself one level */ | |
455 | return 0; | |
456 | #endif | |
dc7d5527 JW |
457 | dump_stack(); |
458 | panic("Recursive entry to debugger"); | |
459 | ||
460 | return 1; | |
461 | } | |
462 | ||
16cdc628 JW |
463 | static void dbg_touch_watchdogs(void) |
464 | { | |
465 | touch_softlockup_watchdog_sync(); | |
466 | clocksource_touch_watchdog(); | |
fb70b588 | 467 | rcu_cpu_stall_reset(); |
16cdc628 JW |
468 | } |
469 | ||
dfee3a7b JW |
470 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
471 | int exception_state) | |
dc7d5527 | 472 | { |
dc7d5527 | 473 | unsigned long flags; |
028e7b17 | 474 | int sstep_tries = 100; |
dcc78711 | 475 | int error; |
dfee3a7b | 476 | int cpu; |
4da75b9c | 477 | int trace_on = 0; |
dfee3a7b | 478 | int online_cpus = num_online_cpus(); |
c1bb9a9c | 479 | |
dfee3a7b JW |
480 | kgdb_info[ks->cpu].enter_kgdb++; |
481 | kgdb_info[ks->cpu].exception_state |= exception_state; | |
482 | ||
483 | if (exception_state == DCPU_WANT_MASTER) | |
484 | atomic_inc(&masters_in_kgdb); | |
485 | else | |
486 | atomic_inc(&slaves_in_kgdb); | |
c1bb9a9c DD |
487 | kgdb_disable_hw_debug(ks->linux_regs); |
488 | ||
dc7d5527 JW |
489 | acquirelock: |
490 | /* | |
491 | * Interrupts will be restored by the 'trap return' code, except when | |
492 | * single stepping. | |
493 | */ | |
494 | local_irq_save(flags); | |
495 | ||
62fae312 JW |
496 | cpu = ks->cpu; |
497 | kgdb_info[cpu].debuggerinfo = regs; | |
498 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
499 | kgdb_info[cpu].ret_state = 0; |
500 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
dc7d5527 | 501 | |
dfee3a7b JW |
502 | /* Make sure the above info reaches the primary CPU */ |
503 | smp_mb(); | |
504 | ||
505 | if (exception_level == 1) { | |
506 | if (raw_spin_trylock(&dbg_master_lock)) | |
507 | atomic_xchg(&kgdb_active, cpu); | |
6d906340 | 508 | goto cpu_master_loop; |
dfee3a7b | 509 | } |
6d906340 | 510 | |
dc7d5527 | 511 | /* |
62fae312 JW |
512 | * CPU will loop if it is a slave or request to become a kgdb |
513 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 514 | */ |
62fae312 | 515 | while (1) { |
dcc78711 JW |
516 | cpu_loop: |
517 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { | |
518 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; | |
519 | goto cpu_master_loop; | |
520 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
dfee3a7b JW |
521 | if (raw_spin_trylock(&dbg_master_lock)) { |
522 | atomic_xchg(&kgdb_active, cpu); | |
62fae312 | 523 | break; |
dfee3a7b | 524 | } |
62fae312 | 525 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
dfee3a7b | 526 | if (!raw_spin_is_locked(&dbg_slave_lock)) |
62fae312 JW |
527 | goto return_normal; |
528 | } else { | |
529 | return_normal: | |
530 | /* Return to normal operation by executing any | |
531 | * hw breakpoint fixup. | |
532 | */ | |
533 | if (arch_kgdb_ops.correct_hw_break) | |
534 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
535 | if (trace_on) |
536 | tracing_on(); | |
dfee3a7b JW |
537 | kgdb_info[cpu].exception_state &= |
538 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
539 | kgdb_info[cpu].enter_kgdb--; | |
540 | smp_mb__before_atomic_dec(); | |
541 | atomic_dec(&slaves_in_kgdb); | |
16cdc628 | 542 | dbg_touch_watchdogs(); |
62fae312 JW |
543 | local_irq_restore(flags); |
544 | return 0; | |
545 | } | |
dc7d5527 | 546 | cpu_relax(); |
62fae312 | 547 | } |
dc7d5527 JW |
548 | |
549 | /* | |
028e7b17 JW |
550 | * For single stepping, try to only enter on the processor |
551 | * that was single stepping. To gaurd against a deadlock, the | |
552 | * kernel will only try for the value of sstep_tries before | |
553 | * giving up and continuing on. | |
dc7d5527 JW |
554 | */ |
555 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
556 | (kgdb_info[cpu].task && |
557 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 558 | atomic_set(&kgdb_active, -1); |
dfee3a7b | 559 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 560 | dbg_touch_watchdogs(); |
dc7d5527 JW |
561 | local_irq_restore(flags); |
562 | ||
563 | goto acquirelock; | |
564 | } | |
565 | ||
566 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 567 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 568 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
569 | } |
570 | ||
571 | /* | |
572 | * Don't enter if we have hit a removed breakpoint. | |
573 | */ | |
574 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
575 | goto kgdb_restore; | |
576 | ||
577 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
578 | if (dbg_io_ops->pre_exception) |
579 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 580 | |
dc7d5527 JW |
581 | /* |
582 | * Get the passive CPU lock which will hold all the non-primary | |
583 | * CPU in a spin state while the debugger is active | |
584 | */ | |
dfee3a7b JW |
585 | if (!kgdb_single_step) |
586 | raw_spin_lock(&dbg_slave_lock); | |
dc7d5527 | 587 | |
56fb7093 JW |
588 | #ifdef CONFIG_SMP |
589 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 590 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
591 | kgdb_roundup_cpus(flags); |
592 | #endif | |
593 | ||
dc7d5527 JW |
594 | /* |
595 | * Wait for the other CPUs to be notified and be waiting for us: | |
596 | */ | |
dfee3a7b JW |
597 | while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + |
598 | atomic_read(&slaves_in_kgdb)) != online_cpus) | |
599 | cpu_relax(); | |
dc7d5527 JW |
600 | |
601 | /* | |
602 | * At this point the primary processor is completely | |
603 | * in the debugger and all secondary CPUs are quiescent | |
604 | */ | |
dcc78711 | 605 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 606 | kgdb_single_step = 0; |
d7161a65 | 607 | kgdb_contthread = current; |
dc7d5527 | 608 | exception_level = 0; |
4da75b9c JW |
609 | trace_on = tracing_is_on(); |
610 | if (trace_on) | |
611 | tracing_off(); | |
dc7d5527 | 612 | |
dcc78711 JW |
613 | while (1) { |
614 | cpu_master_loop: | |
615 | if (dbg_kdb_mode) { | |
616 | kgdb_connected = 1; | |
617 | error = kdb_stub(ks); | |
3fa43aba JW |
618 | if (error == -1) |
619 | continue; | |
b0679c63 | 620 | kgdb_connected = 0; |
dcc78711 JW |
621 | } else { |
622 | error = gdb_serial_stub(ks); | |
623 | } | |
624 | ||
625 | if (error == DBG_PASS_EVENT) { | |
626 | dbg_kdb_mode = !dbg_kdb_mode; | |
dcc78711 | 627 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
495363d3 JW |
628 | kgdb_info[dbg_switch_cpu].exception_state |= |
629 | DCPU_NEXT_MASTER; | |
dcc78711 JW |
630 | goto cpu_loop; |
631 | } else { | |
632 | kgdb_info[cpu].ret_state = error; | |
633 | break; | |
634 | } | |
635 | } | |
dc7d5527 JW |
636 | |
637 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
638 | if (dbg_io_ops->post_exception) |
639 | dbg_io_ops->post_exception(); | |
dc7d5527 | 640 | |
d7161a65 | 641 | if (!kgdb_single_step) { |
dfee3a7b JW |
642 | raw_spin_unlock(&dbg_slave_lock); |
643 | /* Wait till all the CPUs have quit from the debugger. */ | |
644 | while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) | |
645 | cpu_relax(); | |
dc7d5527 JW |
646 | } |
647 | ||
648 | kgdb_restore: | |
028e7b17 JW |
649 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
650 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
651 | if (kgdb_info[sstep_cpu].task) | |
652 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
653 | else | |
654 | kgdb_sstep_pid = 0; | |
655 | } | |
c1bb9a9c DD |
656 | if (arch_kgdb_ops.correct_hw_break) |
657 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
658 | if (trace_on) |
659 | tracing_on(); | |
dfee3a7b JW |
660 | |
661 | kgdb_info[cpu].exception_state &= | |
662 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
663 | kgdb_info[cpu].enter_kgdb--; | |
664 | smp_mb__before_atomic_dec(); | |
665 | atomic_dec(&masters_in_kgdb); | |
dc7d5527 JW |
666 | /* Free kgdb_active */ |
667 | atomic_set(&kgdb_active, -1); | |
dfee3a7b | 668 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 669 | dbg_touch_watchdogs(); |
dc7d5527 JW |
670 | local_irq_restore(flags); |
671 | ||
dcc78711 | 672 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
673 | } |
674 | ||
62fae312 JW |
675 | /* |
676 | * kgdb_handle_exception() - main entry point from a kernel exception | |
677 | * | |
678 | * Locking hierarchy: | |
679 | * interface locks, if any (begin_session) | |
680 | * kgdb lock (kgdb_active) | |
681 | */ | |
682 | int | |
683 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
684 | { | |
685 | struct kgdb_state kgdb_var; | |
686 | struct kgdb_state *ks = &kgdb_var; | |
62fae312 JW |
687 | |
688 | ks->cpu = raw_smp_processor_id(); | |
689 | ks->ex_vector = evector; | |
690 | ks->signo = signo; | |
62fae312 JW |
691 | ks->err_code = ecode; |
692 | ks->kgdb_usethreadid = 0; | |
693 | ks->linux_regs = regs; | |
694 | ||
695 | if (kgdb_reenter_check(ks)) | |
696 | return 0; /* Ouch, double exception ! */ | |
dfee3a7b JW |
697 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
698 | return 0; | |
699 | ||
700 | return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); | |
62fae312 JW |
701 | } |
702 | ||
dc7d5527 JW |
703 | int kgdb_nmicallback(int cpu, void *regs) |
704 | { | |
705 | #ifdef CONFIG_SMP | |
62fae312 JW |
706 | struct kgdb_state kgdb_var; |
707 | struct kgdb_state *ks = &kgdb_var; | |
708 | ||
709 | memset(ks, 0, sizeof(struct kgdb_state)); | |
710 | ks->cpu = cpu; | |
711 | ks->linux_regs = regs; | |
712 | ||
dfee3a7b JW |
713 | if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
714 | raw_spin_is_locked(&dbg_master_lock)) { | |
715 | kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); | |
dc7d5527 JW |
716 | return 0; |
717 | } | |
718 | #endif | |
719 | return 1; | |
720 | } | |
721 | ||
aabdc3b8 JW |
722 | static void kgdb_console_write(struct console *co, const char *s, |
723 | unsigned count) | |
dc7d5527 JW |
724 | { |
725 | unsigned long flags; | |
726 | ||
727 | /* If we're debugging, or KGDB has not connected, don't try | |
728 | * and print. */ | |
dcc78711 | 729 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
730 | return; |
731 | ||
732 | local_irq_save(flags); | |
53197fc4 | 733 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
734 | local_irq_restore(flags); |
735 | } | |
736 | ||
737 | static struct console kgdbcons = { | |
738 | .name = "kgdb", | |
739 | .write = kgdb_console_write, | |
740 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
741 | .index = -1, | |
742 | }; | |
743 | ||
744 | #ifdef CONFIG_MAGIC_SYSRQ | |
1495cc9d | 745 | static void sysrq_handle_dbg(int key) |
dc7d5527 | 746 | { |
53197fc4 | 747 | if (!dbg_io_ops) { |
dc7d5527 JW |
748 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
749 | return; | |
750 | } | |
dcc78711 JW |
751 | if (!kgdb_connected) { |
752 | #ifdef CONFIG_KGDB_KDB | |
753 | if (!dbg_kdb_mode) | |
754 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
755 | #else | |
dc7d5527 | 756 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
757 | #endif |
758 | } | |
dc7d5527 JW |
759 | |
760 | kgdb_breakpoint(); | |
761 | } | |
762 | ||
53197fc4 JW |
763 | static struct sysrq_key_op sysrq_dbg_op = { |
764 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
765 | .help_msg = "debug(G)", |
766 | .action_msg = "DEBUG", | |
dc7d5527 JW |
767 | }; |
768 | #endif | |
769 | ||
4402c153 JW |
770 | static int kgdb_panic_event(struct notifier_block *self, |
771 | unsigned long val, | |
772 | void *data) | |
773 | { | |
774 | if (dbg_kdb_mode) | |
775 | kdb_printf("PANIC: %s\n", (char *)data); | |
776 | kgdb_breakpoint(); | |
777 | return NOTIFY_DONE; | |
778 | } | |
779 | ||
780 | static struct notifier_block kgdb_panic_event_nb = { | |
781 | .notifier_call = kgdb_panic_event, | |
782 | .priority = INT_MAX, | |
783 | }; | |
784 | ||
0b4b3827 JW |
785 | void __weak kgdb_arch_late(void) |
786 | { | |
787 | } | |
788 | ||
789 | void __init dbg_late_init(void) | |
790 | { | |
791 | dbg_is_early = false; | |
792 | if (kgdb_io_module_registered) | |
793 | kgdb_arch_late(); | |
794 | kdb_init(KDB_INIT_FULL); | |
795 | } | |
796 | ||
dc7d5527 JW |
797 | static void kgdb_register_callbacks(void) |
798 | { | |
799 | if (!kgdb_io_module_registered) { | |
800 | kgdb_io_module_registered = 1; | |
801 | kgdb_arch_init(); | |
0b4b3827 JW |
802 | if (!dbg_is_early) |
803 | kgdb_arch_late(); | |
4402c153 JW |
804 | atomic_notifier_chain_register(&panic_notifier_list, |
805 | &kgdb_panic_event_nb); | |
dc7d5527 | 806 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 807 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
808 | #endif |
809 | if (kgdb_use_con && !kgdb_con_registered) { | |
810 | register_console(&kgdbcons); | |
811 | kgdb_con_registered = 1; | |
812 | } | |
813 | } | |
814 | } | |
815 | ||
816 | static void kgdb_unregister_callbacks(void) | |
817 | { | |
818 | /* | |
819 | * When this routine is called KGDB should unregister from the | |
820 | * panic handler and clean up, making sure it is not handling any | |
821 | * break exceptions at the time. | |
822 | */ | |
823 | if (kgdb_io_module_registered) { | |
824 | kgdb_io_module_registered = 0; | |
4402c153 JW |
825 | atomic_notifier_chain_unregister(&panic_notifier_list, |
826 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
827 | kgdb_arch_exit(); |
828 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 829 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
830 | #endif |
831 | if (kgdb_con_registered) { | |
832 | unregister_console(&kgdbcons); | |
833 | kgdb_con_registered = 0; | |
834 | } | |
835 | } | |
836 | } | |
837 | ||
1cee5e35 JW |
838 | /* |
839 | * There are times a tasklet needs to be used vs a compiled in | |
840 | * break point so as to cause an exception outside a kgdb I/O module, | |
841 | * such as is the case with kgdboe, where calling a breakpoint in the | |
842 | * I/O driver itself would be fatal. | |
843 | */ | |
844 | static void kgdb_tasklet_bpt(unsigned long ing) | |
845 | { | |
846 | kgdb_breakpoint(); | |
847 | atomic_set(&kgdb_break_tasklet_var, 0); | |
848 | } | |
849 | ||
850 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); | |
851 | ||
852 | void kgdb_schedule_breakpoint(void) | |
853 | { | |
854 | if (atomic_read(&kgdb_break_tasklet_var) || | |
855 | atomic_read(&kgdb_active) != -1 || | |
856 | atomic_read(&kgdb_setting_breakpoint)) | |
857 | return; | |
858 | atomic_inc(&kgdb_break_tasklet_var); | |
859 | tasklet_schedule(&kgdb_tasklet_breakpoint); | |
860 | } | |
861 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); | |
862 | ||
dc7d5527 JW |
863 | static void kgdb_initial_breakpoint(void) |
864 | { | |
865 | kgdb_break_asap = 0; | |
866 | ||
867 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
868 | kgdb_breakpoint(); | |
869 | } | |
870 | ||
871 | /** | |
737a460f | 872 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 873 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
874 | * |
875 | * Register it with the KGDB core. | |
876 | */ | |
53197fc4 | 877 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
878 | { |
879 | int err; | |
880 | ||
881 | spin_lock(&kgdb_registration_lock); | |
882 | ||
53197fc4 | 883 | if (dbg_io_ops) { |
dc7d5527 JW |
884 | spin_unlock(&kgdb_registration_lock); |
885 | ||
886 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
887 | "registered with KGDB.\n"); | |
888 | return -EBUSY; | |
889 | } | |
890 | ||
53197fc4 JW |
891 | if (new_dbg_io_ops->init) { |
892 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
893 | if (err) { |
894 | spin_unlock(&kgdb_registration_lock); | |
895 | return err; | |
896 | } | |
897 | } | |
898 | ||
53197fc4 | 899 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
900 | |
901 | spin_unlock(&kgdb_registration_lock); | |
902 | ||
903 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 904 | new_dbg_io_ops->name); |
dc7d5527 JW |
905 | |
906 | /* Arm KGDB now. */ | |
907 | kgdb_register_callbacks(); | |
908 | ||
909 | if (kgdb_break_asap) | |
910 | kgdb_initial_breakpoint(); | |
911 | ||
912 | return 0; | |
913 | } | |
914 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
915 | ||
916 | /** | |
917 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 918 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
919 | * |
920 | * Unregister it with the KGDB core. | |
921 | */ | |
53197fc4 | 922 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
923 | { |
924 | BUG_ON(kgdb_connected); | |
925 | ||
926 | /* | |
927 | * KGDB is no longer able to communicate out, so | |
928 | * unregister our callbacks and reset state. | |
929 | */ | |
930 | kgdb_unregister_callbacks(); | |
931 | ||
932 | spin_lock(&kgdb_registration_lock); | |
933 | ||
53197fc4 JW |
934 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
935 | dbg_io_ops = NULL; | |
dc7d5527 JW |
936 | |
937 | spin_unlock(&kgdb_registration_lock); | |
938 | ||
939 | printk(KERN_INFO | |
940 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 941 | old_dbg_io_ops->name); |
dc7d5527 JW |
942 | } |
943 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
944 | ||
dcc78711 JW |
945 | int dbg_io_get_char(void) |
946 | { | |
947 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
948 | if (ret == NO_POLL_CHAR) |
949 | return -1; | |
dcc78711 JW |
950 | if (!dbg_kdb_mode) |
951 | return ret; | |
952 | if (ret == 127) | |
953 | return 8; | |
954 | return ret; | |
955 | } | |
956 | ||
dc7d5527 JW |
957 | /** |
958 | * kgdb_breakpoint - generate breakpoint exception | |
959 | * | |
960 | * This function will generate a breakpoint exception. It is used at the | |
961 | * beginning of a program to sync up with a debugger and can be used | |
962 | * otherwise as a quick means to stop program execution and "break" into | |
963 | * the debugger. | |
964 | */ | |
965 | void kgdb_breakpoint(void) | |
966 | { | |
ae6bf53e | 967 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
968 | wmb(); /* Sync point before breakpoint */ |
969 | arch_kgdb_breakpoint(); | |
970 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 971 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
972 | } |
973 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
974 | ||
975 | static int __init opt_kgdb_wait(char *str) | |
976 | { | |
977 | kgdb_break_asap = 1; | |
978 | ||
dcc78711 | 979 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
980 | if (kgdb_io_module_registered) |
981 | kgdb_initial_breakpoint(); | |
982 | ||
983 | return 0; | |
984 | } | |
985 | ||
986 | early_param("kgdbwait", opt_kgdb_wait); |