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> | |
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 | ||
dcc78711 JW |
463 | static void dbg_cpu_switch(int cpu, int next_cpu) |
464 | { | |
465 | /* Mark the cpu we are switching away from as a slave when it | |
466 | * holds the kgdb_active token. This must be done so that the | |
467 | * that all the cpus wait in for the debug core will not enter | |
468 | * again as the master. */ | |
469 | if (cpu == atomic_read(&kgdb_active)) { | |
470 | kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE; | |
471 | kgdb_info[cpu].exception_state &= ~DCPU_WANT_MASTER; | |
472 | } | |
473 | kgdb_info[next_cpu].exception_state |= DCPU_NEXT_MASTER; | |
474 | } | |
475 | ||
16cdc628 JW |
476 | static void dbg_touch_watchdogs(void) |
477 | { | |
478 | touch_softlockup_watchdog_sync(); | |
479 | clocksource_touch_watchdog(); | |
fb70b588 | 480 | rcu_cpu_stall_reset(); |
16cdc628 JW |
481 | } |
482 | ||
dfee3a7b JW |
483 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
484 | int exception_state) | |
dc7d5527 | 485 | { |
dc7d5527 | 486 | unsigned long flags; |
028e7b17 | 487 | int sstep_tries = 100; |
dcc78711 | 488 | int error; |
dfee3a7b | 489 | int cpu; |
4da75b9c | 490 | int trace_on = 0; |
dfee3a7b | 491 | int online_cpus = num_online_cpus(); |
c1bb9a9c | 492 | |
dfee3a7b JW |
493 | kgdb_info[ks->cpu].enter_kgdb++; |
494 | kgdb_info[ks->cpu].exception_state |= exception_state; | |
495 | ||
496 | if (exception_state == DCPU_WANT_MASTER) | |
497 | atomic_inc(&masters_in_kgdb); | |
498 | else | |
499 | atomic_inc(&slaves_in_kgdb); | |
c1bb9a9c DD |
500 | kgdb_disable_hw_debug(ks->linux_regs); |
501 | ||
dc7d5527 JW |
502 | acquirelock: |
503 | /* | |
504 | * Interrupts will be restored by the 'trap return' code, except when | |
505 | * single stepping. | |
506 | */ | |
507 | local_irq_save(flags); | |
508 | ||
62fae312 JW |
509 | cpu = ks->cpu; |
510 | kgdb_info[cpu].debuggerinfo = regs; | |
511 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
512 | kgdb_info[cpu].ret_state = 0; |
513 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
dc7d5527 | 514 | |
dfee3a7b JW |
515 | /* Make sure the above info reaches the primary CPU */ |
516 | smp_mb(); | |
517 | ||
518 | if (exception_level == 1) { | |
519 | if (raw_spin_trylock(&dbg_master_lock)) | |
520 | atomic_xchg(&kgdb_active, cpu); | |
6d906340 | 521 | goto cpu_master_loop; |
dfee3a7b | 522 | } |
6d906340 | 523 | |
dc7d5527 | 524 | /* |
62fae312 JW |
525 | * CPU will loop if it is a slave or request to become a kgdb |
526 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 527 | */ |
62fae312 | 528 | while (1) { |
dcc78711 JW |
529 | cpu_loop: |
530 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { | |
531 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; | |
532 | goto cpu_master_loop; | |
533 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
dfee3a7b JW |
534 | if (raw_spin_trylock(&dbg_master_lock)) { |
535 | atomic_xchg(&kgdb_active, cpu); | |
62fae312 | 536 | break; |
dfee3a7b | 537 | } |
62fae312 | 538 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
dfee3a7b | 539 | if (!raw_spin_is_locked(&dbg_slave_lock)) |
62fae312 JW |
540 | goto return_normal; |
541 | } else { | |
542 | return_normal: | |
543 | /* Return to normal operation by executing any | |
544 | * hw breakpoint fixup. | |
545 | */ | |
546 | if (arch_kgdb_ops.correct_hw_break) | |
547 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
548 | if (trace_on) |
549 | tracing_on(); | |
dfee3a7b JW |
550 | kgdb_info[cpu].exception_state &= |
551 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
552 | kgdb_info[cpu].enter_kgdb--; | |
553 | smp_mb__before_atomic_dec(); | |
554 | atomic_dec(&slaves_in_kgdb); | |
16cdc628 | 555 | dbg_touch_watchdogs(); |
62fae312 JW |
556 | local_irq_restore(flags); |
557 | return 0; | |
558 | } | |
dc7d5527 | 559 | cpu_relax(); |
62fae312 | 560 | } |
dc7d5527 JW |
561 | |
562 | /* | |
028e7b17 JW |
563 | * For single stepping, try to only enter on the processor |
564 | * that was single stepping. To gaurd against a deadlock, the | |
565 | * kernel will only try for the value of sstep_tries before | |
566 | * giving up and continuing on. | |
dc7d5527 JW |
567 | */ |
568 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
569 | (kgdb_info[cpu].task && |
570 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 571 | atomic_set(&kgdb_active, -1); |
dfee3a7b | 572 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 573 | dbg_touch_watchdogs(); |
dc7d5527 JW |
574 | local_irq_restore(flags); |
575 | ||
576 | goto acquirelock; | |
577 | } | |
578 | ||
579 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 580 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 581 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
582 | } |
583 | ||
584 | /* | |
585 | * Don't enter if we have hit a removed breakpoint. | |
586 | */ | |
587 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
588 | goto kgdb_restore; | |
589 | ||
590 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
591 | if (dbg_io_ops->pre_exception) |
592 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 593 | |
dc7d5527 JW |
594 | /* |
595 | * Get the passive CPU lock which will hold all the non-primary | |
596 | * CPU in a spin state while the debugger is active | |
597 | */ | |
dfee3a7b JW |
598 | if (!kgdb_single_step) |
599 | raw_spin_lock(&dbg_slave_lock); | |
dc7d5527 | 600 | |
56fb7093 JW |
601 | #ifdef CONFIG_SMP |
602 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 603 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
604 | kgdb_roundup_cpus(flags); |
605 | #endif | |
606 | ||
dc7d5527 JW |
607 | /* |
608 | * Wait for the other CPUs to be notified and be waiting for us: | |
609 | */ | |
dfee3a7b JW |
610 | while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + |
611 | atomic_read(&slaves_in_kgdb)) != online_cpus) | |
612 | cpu_relax(); | |
dc7d5527 JW |
613 | |
614 | /* | |
615 | * At this point the primary processor is completely | |
616 | * in the debugger and all secondary CPUs are quiescent | |
617 | */ | |
dcc78711 | 618 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 619 | kgdb_single_step = 0; |
d7161a65 | 620 | kgdb_contthread = current; |
dc7d5527 | 621 | exception_level = 0; |
4da75b9c JW |
622 | trace_on = tracing_is_on(); |
623 | if (trace_on) | |
624 | tracing_off(); | |
dc7d5527 | 625 | |
dcc78711 JW |
626 | while (1) { |
627 | cpu_master_loop: | |
628 | if (dbg_kdb_mode) { | |
629 | kgdb_connected = 1; | |
630 | error = kdb_stub(ks); | |
3fa43aba JW |
631 | if (error == -1) |
632 | continue; | |
b0679c63 | 633 | kgdb_connected = 0; |
dcc78711 JW |
634 | } else { |
635 | error = gdb_serial_stub(ks); | |
636 | } | |
637 | ||
638 | if (error == DBG_PASS_EVENT) { | |
639 | dbg_kdb_mode = !dbg_kdb_mode; | |
dcc78711 JW |
640 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
641 | dbg_cpu_switch(cpu, dbg_switch_cpu); | |
642 | goto cpu_loop; | |
643 | } else { | |
644 | kgdb_info[cpu].ret_state = error; | |
645 | break; | |
646 | } | |
647 | } | |
dc7d5527 JW |
648 | |
649 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
650 | if (dbg_io_ops->post_exception) |
651 | dbg_io_ops->post_exception(); | |
dc7d5527 | 652 | |
d7161a65 | 653 | if (!kgdb_single_step) { |
dfee3a7b JW |
654 | raw_spin_unlock(&dbg_slave_lock); |
655 | /* Wait till all the CPUs have quit from the debugger. */ | |
656 | while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) | |
657 | cpu_relax(); | |
dc7d5527 JW |
658 | } |
659 | ||
660 | kgdb_restore: | |
028e7b17 JW |
661 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
662 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
663 | if (kgdb_info[sstep_cpu].task) | |
664 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
665 | else | |
666 | kgdb_sstep_pid = 0; | |
667 | } | |
c1bb9a9c DD |
668 | if (arch_kgdb_ops.correct_hw_break) |
669 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
670 | if (trace_on) |
671 | tracing_on(); | |
dfee3a7b JW |
672 | |
673 | kgdb_info[cpu].exception_state &= | |
674 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
675 | kgdb_info[cpu].enter_kgdb--; | |
676 | smp_mb__before_atomic_dec(); | |
677 | atomic_dec(&masters_in_kgdb); | |
dc7d5527 JW |
678 | /* Free kgdb_active */ |
679 | atomic_set(&kgdb_active, -1); | |
dfee3a7b | 680 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 681 | dbg_touch_watchdogs(); |
dc7d5527 JW |
682 | local_irq_restore(flags); |
683 | ||
dcc78711 | 684 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
685 | } |
686 | ||
62fae312 JW |
687 | /* |
688 | * kgdb_handle_exception() - main entry point from a kernel exception | |
689 | * | |
690 | * Locking hierarchy: | |
691 | * interface locks, if any (begin_session) | |
692 | * kgdb lock (kgdb_active) | |
693 | */ | |
694 | int | |
695 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
696 | { | |
697 | struct kgdb_state kgdb_var; | |
698 | struct kgdb_state *ks = &kgdb_var; | |
62fae312 JW |
699 | |
700 | ks->cpu = raw_smp_processor_id(); | |
701 | ks->ex_vector = evector; | |
702 | ks->signo = signo; | |
62fae312 JW |
703 | ks->err_code = ecode; |
704 | ks->kgdb_usethreadid = 0; | |
705 | ks->linux_regs = regs; | |
706 | ||
707 | if (kgdb_reenter_check(ks)) | |
708 | return 0; /* Ouch, double exception ! */ | |
dfee3a7b JW |
709 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
710 | return 0; | |
711 | ||
712 | return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); | |
62fae312 JW |
713 | } |
714 | ||
dc7d5527 JW |
715 | int kgdb_nmicallback(int cpu, void *regs) |
716 | { | |
717 | #ifdef CONFIG_SMP | |
62fae312 JW |
718 | struct kgdb_state kgdb_var; |
719 | struct kgdb_state *ks = &kgdb_var; | |
720 | ||
721 | memset(ks, 0, sizeof(struct kgdb_state)); | |
722 | ks->cpu = cpu; | |
723 | ks->linux_regs = regs; | |
724 | ||
dfee3a7b JW |
725 | if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
726 | raw_spin_is_locked(&dbg_master_lock)) { | |
727 | kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); | |
dc7d5527 JW |
728 | return 0; |
729 | } | |
730 | #endif | |
731 | return 1; | |
732 | } | |
733 | ||
aabdc3b8 JW |
734 | static void kgdb_console_write(struct console *co, const char *s, |
735 | unsigned count) | |
dc7d5527 JW |
736 | { |
737 | unsigned long flags; | |
738 | ||
739 | /* If we're debugging, or KGDB has not connected, don't try | |
740 | * and print. */ | |
dcc78711 | 741 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
742 | return; |
743 | ||
744 | local_irq_save(flags); | |
53197fc4 | 745 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
746 | local_irq_restore(flags); |
747 | } | |
748 | ||
749 | static struct console kgdbcons = { | |
750 | .name = "kgdb", | |
751 | .write = kgdb_console_write, | |
752 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
753 | .index = -1, | |
754 | }; | |
755 | ||
756 | #ifdef CONFIG_MAGIC_SYSRQ | |
1495cc9d | 757 | static void sysrq_handle_dbg(int key) |
dc7d5527 | 758 | { |
53197fc4 | 759 | if (!dbg_io_ops) { |
dc7d5527 JW |
760 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
761 | return; | |
762 | } | |
dcc78711 JW |
763 | if (!kgdb_connected) { |
764 | #ifdef CONFIG_KGDB_KDB | |
765 | if (!dbg_kdb_mode) | |
766 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
767 | #else | |
dc7d5527 | 768 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
769 | #endif |
770 | } | |
dc7d5527 JW |
771 | |
772 | kgdb_breakpoint(); | |
773 | } | |
774 | ||
53197fc4 JW |
775 | static struct sysrq_key_op sysrq_dbg_op = { |
776 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
777 | .help_msg = "debug(G)", |
778 | .action_msg = "DEBUG", | |
dc7d5527 JW |
779 | }; |
780 | #endif | |
781 | ||
4402c153 JW |
782 | static int kgdb_panic_event(struct notifier_block *self, |
783 | unsigned long val, | |
784 | void *data) | |
785 | { | |
786 | if (dbg_kdb_mode) | |
787 | kdb_printf("PANIC: %s\n", (char *)data); | |
788 | kgdb_breakpoint(); | |
789 | return NOTIFY_DONE; | |
790 | } | |
791 | ||
792 | static struct notifier_block kgdb_panic_event_nb = { | |
793 | .notifier_call = kgdb_panic_event, | |
794 | .priority = INT_MAX, | |
795 | }; | |
796 | ||
0b4b3827 JW |
797 | void __weak kgdb_arch_late(void) |
798 | { | |
799 | } | |
800 | ||
801 | void __init dbg_late_init(void) | |
802 | { | |
803 | dbg_is_early = false; | |
804 | if (kgdb_io_module_registered) | |
805 | kgdb_arch_late(); | |
806 | kdb_init(KDB_INIT_FULL); | |
807 | } | |
808 | ||
dc7d5527 JW |
809 | static void kgdb_register_callbacks(void) |
810 | { | |
811 | if (!kgdb_io_module_registered) { | |
812 | kgdb_io_module_registered = 1; | |
813 | kgdb_arch_init(); | |
0b4b3827 JW |
814 | if (!dbg_is_early) |
815 | kgdb_arch_late(); | |
4402c153 JW |
816 | atomic_notifier_chain_register(&panic_notifier_list, |
817 | &kgdb_panic_event_nb); | |
dc7d5527 | 818 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 819 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
820 | #endif |
821 | if (kgdb_use_con && !kgdb_con_registered) { | |
822 | register_console(&kgdbcons); | |
823 | kgdb_con_registered = 1; | |
824 | } | |
825 | } | |
826 | } | |
827 | ||
828 | static void kgdb_unregister_callbacks(void) | |
829 | { | |
830 | /* | |
831 | * When this routine is called KGDB should unregister from the | |
832 | * panic handler and clean up, making sure it is not handling any | |
833 | * break exceptions at the time. | |
834 | */ | |
835 | if (kgdb_io_module_registered) { | |
836 | kgdb_io_module_registered = 0; | |
4402c153 JW |
837 | atomic_notifier_chain_unregister(&panic_notifier_list, |
838 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
839 | kgdb_arch_exit(); |
840 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 841 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
842 | #endif |
843 | if (kgdb_con_registered) { | |
844 | unregister_console(&kgdbcons); | |
845 | kgdb_con_registered = 0; | |
846 | } | |
847 | } | |
848 | } | |
849 | ||
1cee5e35 JW |
850 | /* |
851 | * There are times a tasklet needs to be used vs a compiled in | |
852 | * break point so as to cause an exception outside a kgdb I/O module, | |
853 | * such as is the case with kgdboe, where calling a breakpoint in the | |
854 | * I/O driver itself would be fatal. | |
855 | */ | |
856 | static void kgdb_tasklet_bpt(unsigned long ing) | |
857 | { | |
858 | kgdb_breakpoint(); | |
859 | atomic_set(&kgdb_break_tasklet_var, 0); | |
860 | } | |
861 | ||
862 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); | |
863 | ||
864 | void kgdb_schedule_breakpoint(void) | |
865 | { | |
866 | if (atomic_read(&kgdb_break_tasklet_var) || | |
867 | atomic_read(&kgdb_active) != -1 || | |
868 | atomic_read(&kgdb_setting_breakpoint)) | |
869 | return; | |
870 | atomic_inc(&kgdb_break_tasklet_var); | |
871 | tasklet_schedule(&kgdb_tasklet_breakpoint); | |
872 | } | |
873 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); | |
874 | ||
dc7d5527 JW |
875 | static void kgdb_initial_breakpoint(void) |
876 | { | |
877 | kgdb_break_asap = 0; | |
878 | ||
879 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
880 | kgdb_breakpoint(); | |
881 | } | |
882 | ||
883 | /** | |
737a460f | 884 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 885 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
886 | * |
887 | * Register it with the KGDB core. | |
888 | */ | |
53197fc4 | 889 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
890 | { |
891 | int err; | |
892 | ||
893 | spin_lock(&kgdb_registration_lock); | |
894 | ||
53197fc4 | 895 | if (dbg_io_ops) { |
dc7d5527 JW |
896 | spin_unlock(&kgdb_registration_lock); |
897 | ||
898 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
899 | "registered with KGDB.\n"); | |
900 | return -EBUSY; | |
901 | } | |
902 | ||
53197fc4 JW |
903 | if (new_dbg_io_ops->init) { |
904 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
905 | if (err) { |
906 | spin_unlock(&kgdb_registration_lock); | |
907 | return err; | |
908 | } | |
909 | } | |
910 | ||
53197fc4 | 911 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
912 | |
913 | spin_unlock(&kgdb_registration_lock); | |
914 | ||
915 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 916 | new_dbg_io_ops->name); |
dc7d5527 JW |
917 | |
918 | /* Arm KGDB now. */ | |
919 | kgdb_register_callbacks(); | |
920 | ||
921 | if (kgdb_break_asap) | |
922 | kgdb_initial_breakpoint(); | |
923 | ||
924 | return 0; | |
925 | } | |
926 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
927 | ||
928 | /** | |
929 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 930 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
931 | * |
932 | * Unregister it with the KGDB core. | |
933 | */ | |
53197fc4 | 934 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
935 | { |
936 | BUG_ON(kgdb_connected); | |
937 | ||
938 | /* | |
939 | * KGDB is no longer able to communicate out, so | |
940 | * unregister our callbacks and reset state. | |
941 | */ | |
942 | kgdb_unregister_callbacks(); | |
943 | ||
944 | spin_lock(&kgdb_registration_lock); | |
945 | ||
53197fc4 JW |
946 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
947 | dbg_io_ops = NULL; | |
dc7d5527 JW |
948 | |
949 | spin_unlock(&kgdb_registration_lock); | |
950 | ||
951 | printk(KERN_INFO | |
952 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 953 | old_dbg_io_ops->name); |
dc7d5527 JW |
954 | } |
955 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
956 | ||
dcc78711 JW |
957 | int dbg_io_get_char(void) |
958 | { | |
959 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
960 | if (ret == NO_POLL_CHAR) |
961 | return -1; | |
dcc78711 JW |
962 | if (!dbg_kdb_mode) |
963 | return ret; | |
964 | if (ret == 127) | |
965 | return 8; | |
966 | return ret; | |
967 | } | |
968 | ||
dc7d5527 JW |
969 | /** |
970 | * kgdb_breakpoint - generate breakpoint exception | |
971 | * | |
972 | * This function will generate a breakpoint exception. It is used at the | |
973 | * beginning of a program to sync up with a debugger and can be used | |
974 | * otherwise as a quick means to stop program execution and "break" into | |
975 | * the debugger. | |
976 | */ | |
977 | void kgdb_breakpoint(void) | |
978 | { | |
ae6bf53e | 979 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
980 | wmb(); /* Sync point before breakpoint */ |
981 | arch_kgdb_breakpoint(); | |
982 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 983 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
984 | } |
985 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
986 | ||
987 | static int __init opt_kgdb_wait(char *str) | |
988 | { | |
989 | kgdb_break_asap = 1; | |
990 | ||
dcc78711 | 991 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
992 | if (kgdb_io_module_registered) |
993 | kgdb_initial_breakpoint(); | |
994 | ||
995 | return 0; | |
996 | } | |
997 | ||
998 | early_param("kgdbwait", opt_kgdb_wait); |