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> |
16559ae4 | 32 | #include <linux/serial_core.h> |
dc7d5527 JW |
33 | #include <linux/interrupt.h> |
34 | #include <linux/spinlock.h> | |
35 | #include <linux/console.h> | |
36 | #include <linux/threads.h> | |
37 | #include <linux/uaccess.h> | |
38 | #include <linux/kernel.h> | |
39 | #include <linux/module.h> | |
40 | #include <linux/ptrace.h> | |
dc7d5527 JW |
41 | #include <linux/string.h> |
42 | #include <linux/delay.h> | |
43 | #include <linux/sched.h> | |
44 | #include <linux/sysrq.h> | |
2366e047 | 45 | #include <linux/reboot.h> |
dc7d5527 JW |
46 | #include <linux/init.h> |
47 | #include <linux/kgdb.h> | |
dcc78711 | 48 | #include <linux/kdb.h> |
dc7d5527 JW |
49 | #include <linux/pid.h> |
50 | #include <linux/smp.h> | |
51 | #include <linux/mm.h> | |
fb70b588 | 52 | #include <linux/rcupdate.h> |
dc7d5527 JW |
53 | |
54 | #include <asm/cacheflush.h> | |
55 | #include <asm/byteorder.h> | |
60063497 | 56 | #include <linux/atomic.h> |
dc7d5527 | 57 | |
53197fc4 | 58 | #include "debug_core.h" |
dc7d5527 | 59 | |
53197fc4 | 60 | static int kgdb_break_asap; |
62fae312 | 61 | |
53197fc4 | 62 | struct debuggerinfo_struct kgdb_info[NR_CPUS]; |
dc7d5527 JW |
63 | |
64 | /** | |
65 | * kgdb_connected - Is a host GDB connected to us? | |
66 | */ | |
67 | int kgdb_connected; | |
68 | EXPORT_SYMBOL_GPL(kgdb_connected); | |
69 | ||
70 | /* All the KGDB handlers are installed */ | |
f503b5ae | 71 | int kgdb_io_module_registered; |
dc7d5527 JW |
72 | |
73 | /* Guard for recursive entry */ | |
74 | static int exception_level; | |
75 | ||
53197fc4 | 76 | struct kgdb_io *dbg_io_ops; |
dc7d5527 JW |
77 | static DEFINE_SPINLOCK(kgdb_registration_lock); |
78 | ||
bec4d62e JW |
79 | /* Action for the reboot notifiter, a global allow kdb to change it */ |
80 | static int kgdbreboot; | |
dc7d5527 JW |
81 | /* kgdb console driver is loaded */ |
82 | static int kgdb_con_registered; | |
83 | /* determine if kgdb console output should be used */ | |
84 | static int kgdb_use_con; | |
0b4b3827 JW |
85 | /* Flag for alternate operations for early debugging */ |
86 | bool dbg_is_early = true; | |
dcc78711 JW |
87 | /* Next cpu to become the master debug core */ |
88 | int dbg_switch_cpu; | |
6fa3eb70 S |
89 | /* Flag for entering kdb when a panic occurs */ |
90 | static bool break_on_panic = true; | |
91 | /* Flag for entering kdb when an exception occurs */ | |
92 | static bool break_on_exception = true; | |
dcc78711 JW |
93 | |
94 | /* Use kdb or gdbserver mode */ | |
a0de055c | 95 | int dbg_kdb_mode = 1; |
dc7d5527 JW |
96 | |
97 | static int __init opt_kgdb_con(char *str) | |
98 | { | |
99 | kgdb_use_con = 1; | |
100 | return 0; | |
101 | } | |
102 | ||
103 | early_param("kgdbcon", opt_kgdb_con); | |
104 | ||
105 | module_param(kgdb_use_con, int, 0644); | |
bec4d62e | 106 | module_param(kgdbreboot, int, 0644); |
6fa3eb70 S |
107 | module_param(break_on_panic, bool, 0644); |
108 | module_param(break_on_exception, bool, 0644); | |
dc7d5527 JW |
109 | |
110 | /* | |
111 | * Holds information about breakpoints in a kernel. These breakpoints are | |
112 | * added and removed by gdb. | |
113 | */ | |
114 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { | |
115 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } | |
116 | }; | |
117 | ||
118 | /* | |
119 | * The CPU# of the active CPU, or -1 if none: | |
120 | */ | |
121 | atomic_t kgdb_active = ATOMIC_INIT(-1); | |
dcc78711 | 122 | EXPORT_SYMBOL_GPL(kgdb_active); |
dfee3a7b JW |
123 | static DEFINE_RAW_SPINLOCK(dbg_master_lock); |
124 | static DEFINE_RAW_SPINLOCK(dbg_slave_lock); | |
dc7d5527 JW |
125 | |
126 | /* | |
127 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early | |
128 | * bootup code (which might not have percpu set up yet): | |
129 | */ | |
dfee3a7b JW |
130 | static atomic_t masters_in_kgdb; |
131 | static atomic_t slaves_in_kgdb; | |
1cee5e35 | 132 | static atomic_t kgdb_break_tasklet_var; |
dc7d5527 JW |
133 | atomic_t kgdb_setting_breakpoint; |
134 | ||
135 | struct task_struct *kgdb_usethread; | |
136 | struct task_struct *kgdb_contthread; | |
137 | ||
138 | int kgdb_single_step; | |
53197fc4 | 139 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
140 | |
141 | /* to keep track of the CPU which is doing the single stepping*/ | |
142 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); | |
143 | ||
144 | /* | |
145 | * If you are debugging a problem where roundup (the collection of | |
146 | * all other CPUs) is a problem [this should be extremely rare], | |
147 | * then use the nokgdbroundup option to avoid roundup. In that case | |
148 | * the other CPUs might interfere with your debugging context, so | |
149 | * use this with care: | |
150 | */ | |
688b744d | 151 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
152 | |
153 | static int __init opt_nokgdbroundup(char *str) | |
154 | { | |
155 | kgdb_do_roundup = 0; | |
156 | ||
157 | return 0; | |
158 | } | |
159 | ||
160 | early_param("nokgdbroundup", opt_nokgdbroundup); | |
161 | ||
162 | /* | |
163 | * Finally, some KGDB code :-) | |
164 | */ | |
165 | ||
166 | /* | |
167 | * Weak aliases for breakpoint management, | |
168 | * can be overriden by architectures when needed: | |
169 | */ | |
98b54aa1 | 170 | int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) |
dc7d5527 JW |
171 | { |
172 | int err; | |
173 | ||
98b54aa1 JW |
174 | err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, |
175 | BREAK_INSTR_SIZE); | |
dc7d5527 JW |
176 | if (err) |
177 | return err; | |
98b54aa1 JW |
178 | err = probe_kernel_write((char *)bpt->bpt_addr, |
179 | arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); | |
180 | return err; | |
dc7d5527 JW |
181 | } |
182 | ||
98b54aa1 | 183 | int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) |
dc7d5527 | 184 | { |
98b54aa1 JW |
185 | return probe_kernel_write((char *)bpt->bpt_addr, |
186 | (char *)bpt->saved_instr, BREAK_INSTR_SIZE); | |
dc7d5527 JW |
187 | } |
188 | ||
a9b60bf4 JW |
189 | int __weak kgdb_validate_break_address(unsigned long addr) |
190 | { | |
98b54aa1 | 191 | struct kgdb_bkpt tmp; |
a9b60bf4 | 192 | int err; |
98b54aa1 | 193 | /* Validate setting the breakpoint and then removing it. If the |
a9b60bf4 JW |
194 | * remove fails, the kernel needs to emit a bad message because we |
195 | * are deep trouble not being able to put things back the way we | |
196 | * found them. | |
197 | */ | |
98b54aa1 JW |
198 | tmp.bpt_addr = addr; |
199 | err = kgdb_arch_set_breakpoint(&tmp); | |
a9b60bf4 JW |
200 | if (err) |
201 | return err; | |
98b54aa1 | 202 | err = kgdb_arch_remove_breakpoint(&tmp); |
a9b60bf4 JW |
203 | if (err) |
204 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " | |
205 | "memory destroyed at: %lx", addr); | |
206 | return err; | |
207 | } | |
208 | ||
dc7d5527 JW |
209 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
210 | { | |
211 | return instruction_pointer(regs); | |
212 | } | |
213 | ||
214 | int __weak kgdb_arch_init(void) | |
215 | { | |
216 | return 0; | |
217 | } | |
218 | ||
b4b8ac52 JW |
219 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
220 | { | |
221 | return 0; | |
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 | 245 | { |
7f8b7ed6 JW |
246 | int error; |
247 | int ret = 0; | |
dc7d5527 JW |
248 | int i; |
249 | ||
250 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
251 | if (kgdb_break[i].state != BP_SET) | |
252 | continue; | |
253 | ||
98b54aa1 | 254 | error = kgdb_arch_set_breakpoint(&kgdb_break[i]); |
7f8b7ed6 JW |
255 | if (error) { |
256 | ret = error; | |
98b54aa1 JW |
257 | printk(KERN_INFO "KGDB: BP install failed: %lx", |
258 | kgdb_break[i].bpt_addr); | |
7f8b7ed6 JW |
259 | continue; |
260 | } | |
dc7d5527 | 261 | |
98b54aa1 | 262 | kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
dc7d5527 JW |
263 | kgdb_break[i].state = BP_ACTIVE; |
264 | } | |
7f8b7ed6 | 265 | return ret; |
dc7d5527 JW |
266 | } |
267 | ||
53197fc4 | 268 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
269 | { |
270 | int err = kgdb_validate_break_address(addr); | |
271 | int breakno = -1; | |
272 | int i; | |
273 | ||
274 | if (err) | |
275 | return err; | |
276 | ||
277 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
278 | if ((kgdb_break[i].state == BP_SET) && | |
279 | (kgdb_break[i].bpt_addr == addr)) | |
280 | return -EEXIST; | |
281 | } | |
282 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
283 | if (kgdb_break[i].state == BP_REMOVED && | |
284 | kgdb_break[i].bpt_addr == addr) { | |
285 | breakno = i; | |
286 | break; | |
287 | } | |
288 | } | |
289 | ||
290 | if (breakno == -1) { | |
291 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
292 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
293 | breakno = i; | |
294 | break; | |
295 | } | |
296 | } | |
297 | } | |
298 | ||
299 | if (breakno == -1) | |
300 | return -E2BIG; | |
301 | ||
302 | kgdb_break[breakno].state = BP_SET; | |
303 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
304 | kgdb_break[breakno].bpt_addr = addr; | |
305 | ||
306 | return 0; | |
307 | } | |
308 | ||
dcc78711 | 309 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 | 310 | { |
7f8b7ed6 JW |
311 | int error; |
312 | int ret = 0; | |
dc7d5527 JW |
313 | int i; |
314 | ||
315 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
316 | if (kgdb_break[i].state != BP_ACTIVE) | |
317 | continue; | |
98b54aa1 | 318 | error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
7f8b7ed6 | 319 | if (error) { |
98b54aa1 JW |
320 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", |
321 | kgdb_break[i].bpt_addr); | |
7f8b7ed6 JW |
322 | ret = error; |
323 | } | |
dc7d5527 | 324 | |
98b54aa1 | 325 | kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
dc7d5527 JW |
326 | kgdb_break[i].state = BP_SET; |
327 | } | |
7f8b7ed6 | 328 | return ret; |
dc7d5527 JW |
329 | } |
330 | ||
53197fc4 | 331 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
332 | { |
333 | int i; | |
334 | ||
335 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
336 | if ((kgdb_break[i].state == BP_SET) && | |
337 | (kgdb_break[i].bpt_addr == addr)) { | |
338 | kgdb_break[i].state = BP_REMOVED; | |
339 | return 0; | |
340 | } | |
341 | } | |
342 | return -ENOENT; | |
343 | } | |
344 | ||
345 | int kgdb_isremovedbreak(unsigned long addr) | |
346 | { | |
347 | int i; | |
348 | ||
349 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
350 | if ((kgdb_break[i].state == BP_REMOVED) && | |
351 | (kgdb_break[i].bpt_addr == addr)) | |
352 | return 1; | |
353 | } | |
354 | return 0; | |
355 | } | |
356 | ||
53197fc4 | 357 | int dbg_remove_all_break(void) |
dc7d5527 | 358 | { |
dc7d5527 JW |
359 | int error; |
360 | int i; | |
361 | ||
362 | /* Clear memory breakpoints. */ | |
363 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
364 | if (kgdb_break[i].state != BP_ACTIVE) |
365 | goto setundefined; | |
98b54aa1 | 366 | error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
dc7d5527 | 367 | if (error) |
737a460f | 368 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
98b54aa1 | 369 | kgdb_break[i].bpt_addr); |
737a460f JW |
370 | setundefined: |
371 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
372 | } |
373 | ||
374 | /* Clear hardware breakpoints. */ | |
375 | if (arch_kgdb_ops.remove_all_hw_break) | |
376 | arch_kgdb_ops.remove_all_hw_break(); | |
377 | ||
378 | return 0; | |
379 | } | |
380 | ||
dc7d5527 JW |
381 | /* |
382 | * Return true if there is a valid kgdb I/O module. Also if no | |
383 | * debugger is attached a message can be printed to the console about | |
384 | * waiting for the debugger to attach. | |
385 | * | |
386 | * The print_wait argument is only to be true when called from inside | |
387 | * the core kgdb_handle_exception, because it will wait for the | |
388 | * debugger to attach. | |
389 | */ | |
390 | static int kgdb_io_ready(int print_wait) | |
391 | { | |
53197fc4 | 392 | if (!dbg_io_ops) |
dc7d5527 JW |
393 | return 0; |
394 | if (kgdb_connected) | |
395 | return 1; | |
396 | if (atomic_read(&kgdb_setting_breakpoint)) | |
397 | return 1; | |
dcc78711 JW |
398 | if (print_wait) { |
399 | #ifdef CONFIG_KGDB_KDB | |
400 | if (!dbg_kdb_mode) | |
401 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); | |
402 | #else | |
dc7d5527 | 403 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
404 | #endif |
405 | } | |
dc7d5527 JW |
406 | return 1; |
407 | } | |
408 | ||
dc7d5527 JW |
409 | static int kgdb_reenter_check(struct kgdb_state *ks) |
410 | { | |
411 | unsigned long addr; | |
412 | ||
413 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
414 | return 0; | |
415 | ||
416 | /* Panic on recursive debugger calls: */ | |
417 | exception_level++; | |
418 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
dcc78711 | 419 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
420 | |
421 | /* | |
422 | * If the break point removed ok at the place exception | |
423 | * occurred, try to recover and print a warning to the end | |
424 | * user because the user planted a breakpoint in a place that | |
425 | * KGDB needs in order to function. | |
426 | */ | |
53197fc4 | 427 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
428 | exception_level = 0; |
429 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 430 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
431 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
432 | addr); | |
dc7d5527 JW |
433 | WARN_ON_ONCE(1); |
434 | ||
435 | return 1; | |
436 | } | |
53197fc4 | 437 | dbg_remove_all_break(); |
dc7d5527 JW |
438 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
439 | ||
440 | if (exception_level > 1) { | |
441 | dump_stack(); | |
442 | panic("Recursive entry to debugger"); | |
443 | } | |
444 | ||
445 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
6d906340 JW |
446 | #ifdef CONFIG_KGDB_KDB |
447 | /* Allow kdb to debug itself one level */ | |
448 | return 0; | |
449 | #endif | |
dc7d5527 JW |
450 | dump_stack(); |
451 | panic("Recursive entry to debugger"); | |
452 | ||
453 | return 1; | |
454 | } | |
455 | ||
16cdc628 JW |
456 | static void dbg_touch_watchdogs(void) |
457 | { | |
458 | touch_softlockup_watchdog_sync(); | |
459 | clocksource_touch_watchdog(); | |
fb70b588 | 460 | rcu_cpu_stall_reset(); |
16cdc628 JW |
461 | } |
462 | ||
dfee3a7b JW |
463 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
464 | int exception_state) | |
dc7d5527 | 465 | { |
dc7d5527 | 466 | unsigned long flags; |
028e7b17 | 467 | int sstep_tries = 100; |
dcc78711 | 468 | int error; |
dfee3a7b | 469 | int cpu; |
4da75b9c | 470 | int trace_on = 0; |
dfee3a7b | 471 | int online_cpus = num_online_cpus(); |
c1bb9a9c | 472 | |
6fa3eb70 S |
473 | #ifdef CONFIG_KGDB_KDB |
474 | if (force_panic) /* Force panic in previous KDB, so skip this time */ | |
475 | return NOTIFY_DONE; | |
476 | #endif | |
477 | ||
dfee3a7b JW |
478 | kgdb_info[ks->cpu].enter_kgdb++; |
479 | kgdb_info[ks->cpu].exception_state |= exception_state; | |
480 | ||
481 | if (exception_state == DCPU_WANT_MASTER) | |
482 | atomic_inc(&masters_in_kgdb); | |
483 | else | |
484 | atomic_inc(&slaves_in_kgdb); | |
d7ba979d DD |
485 | |
486 | if (arch_kgdb_ops.disable_hw_break) | |
487 | arch_kgdb_ops.disable_hw_break(regs); | |
c1bb9a9c | 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 | 550 | * For single stepping, try to only enter on the processor |
25985edc | 551 | * that was single stepping. To guard against a deadlock, the |
028e7b17 JW |
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 | ||
6fa3eb70 S |
672 | #ifdef CONFIG_KGDB_KDB |
673 | /* If no user input, force trigger kernel panic here */ | |
674 | if (force_panic) { | |
675 | printk("KDB : Force Kernal Panic ! \n"); | |
676 | do { *(volatile int *)0 = 0; } while (1); | |
677 | } | |
678 | #endif | |
679 | ||
dcc78711 | 680 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
681 | } |
682 | ||
62fae312 JW |
683 | /* |
684 | * kgdb_handle_exception() - main entry point from a kernel exception | |
685 | * | |
686 | * Locking hierarchy: | |
687 | * interface locks, if any (begin_session) | |
688 | * kgdb lock (kgdb_active) | |
689 | */ | |
690 | int | |
691 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
692 | { | |
693 | struct kgdb_state kgdb_var; | |
694 | struct kgdb_state *ks = &kgdb_var; | |
5a14fead AV |
695 | int ret = 0; |
696 | ||
697 | if (arch_kgdb_ops.enable_nmi) | |
698 | arch_kgdb_ops.enable_nmi(0); | |
62fae312 | 699 | |
6fa3eb70 S |
700 | if (unlikely(signo != SIGTRAP && !break_on_exception)) |
701 | return 1; | |
702 | ||
62fae312 JW |
703 | ks->cpu = raw_smp_processor_id(); |
704 | ks->ex_vector = evector; | |
705 | ks->signo = signo; | |
62fae312 JW |
706 | ks->err_code = ecode; |
707 | ks->kgdb_usethreadid = 0; | |
708 | ks->linux_regs = regs; | |
709 | ||
710 | if (kgdb_reenter_check(ks)) | |
5a14fead | 711 | goto out; /* Ouch, double exception ! */ |
dfee3a7b | 712 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
5a14fead | 713 | goto out; |
dfee3a7b | 714 | |
5a14fead AV |
715 | ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); |
716 | out: | |
717 | if (arch_kgdb_ops.enable_nmi) | |
718 | arch_kgdb_ops.enable_nmi(1); | |
719 | return ret; | |
62fae312 JW |
720 | } |
721 | ||
f30fed10 JW |
722 | /* |
723 | * GDB places a breakpoint at this function to know dynamically | |
724 | * loaded objects. It's not defined static so that only one instance with this | |
725 | * name exists in the kernel. | |
726 | */ | |
727 | ||
728 | static int module_event(struct notifier_block *self, unsigned long val, | |
729 | void *data) | |
730 | { | |
731 | return 0; | |
732 | } | |
733 | ||
734 | static struct notifier_block dbg_module_load_nb = { | |
735 | .notifier_call = module_event, | |
736 | }; | |
737 | ||
dc7d5527 JW |
738 | int kgdb_nmicallback(int cpu, void *regs) |
739 | { | |
740 | #ifdef CONFIG_SMP | |
62fae312 JW |
741 | struct kgdb_state kgdb_var; |
742 | struct kgdb_state *ks = &kgdb_var; | |
743 | ||
744 | memset(ks, 0, sizeof(struct kgdb_state)); | |
745 | ks->cpu = cpu; | |
746 | ks->linux_regs = regs; | |
747 | ||
dfee3a7b JW |
748 | if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
749 | raw_spin_is_locked(&dbg_master_lock)) { | |
750 | kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); | |
dc7d5527 JW |
751 | return 0; |
752 | } | |
753 | #endif | |
754 | return 1; | |
755 | } | |
756 | ||
aabdc3b8 JW |
757 | static void kgdb_console_write(struct console *co, const char *s, |
758 | unsigned count) | |
dc7d5527 JW |
759 | { |
760 | unsigned long flags; | |
761 | ||
762 | /* If we're debugging, or KGDB has not connected, don't try | |
763 | * and print. */ | |
dcc78711 | 764 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
765 | return; |
766 | ||
767 | local_irq_save(flags); | |
53197fc4 | 768 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
769 | local_irq_restore(flags); |
770 | } | |
771 | ||
772 | static struct console kgdbcons = { | |
773 | .name = "kgdb", | |
774 | .write = kgdb_console_write, | |
775 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
776 | .index = -1, | |
777 | }; | |
778 | ||
779 | #ifdef CONFIG_MAGIC_SYSRQ | |
1495cc9d | 780 | static void sysrq_handle_dbg(int key) |
dc7d5527 | 781 | { |
53197fc4 | 782 | if (!dbg_io_ops) { |
dc7d5527 JW |
783 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
784 | return; | |
785 | } | |
dcc78711 JW |
786 | if (!kgdb_connected) { |
787 | #ifdef CONFIG_KGDB_KDB | |
788 | if (!dbg_kdb_mode) | |
789 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
790 | #else | |
dc7d5527 | 791 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
792 | #endif |
793 | } | |
dc7d5527 JW |
794 | |
795 | kgdb_breakpoint(); | |
796 | } | |
797 | ||
53197fc4 JW |
798 | static struct sysrq_key_op sysrq_dbg_op = { |
799 | .handler = sysrq_handle_dbg, | |
f3456509 | 800 | .help_msg = "debug(g)", |
364b5b7b | 801 | .action_msg = "DEBUG", |
dc7d5527 JW |
802 | }; |
803 | #endif | |
804 | ||
4402c153 JW |
805 | static int kgdb_panic_event(struct notifier_block *self, |
806 | unsigned long val, | |
807 | void *data) | |
808 | { | |
6fa3eb70 S |
809 | #ifdef CONFIG_KGDB_KDB |
810 | if (force_panic) /* Force panic in previous KDB, so skip this time */ | |
811 | return NOTIFY_DONE; | |
812 | #endif | |
813 | ||
814 | if (!break_on_panic) | |
815 | return NOTIFY_DONE; | |
816 | ||
4402c153 JW |
817 | if (dbg_kdb_mode) |
818 | kdb_printf("PANIC: %s\n", (char *)data); | |
819 | kgdb_breakpoint(); | |
820 | return NOTIFY_DONE; | |
821 | } | |
822 | ||
823 | static struct notifier_block kgdb_panic_event_nb = { | |
824 | .notifier_call = kgdb_panic_event, | |
825 | .priority = INT_MAX, | |
826 | }; | |
827 | ||
0b4b3827 JW |
828 | void __weak kgdb_arch_late(void) |
829 | { | |
830 | } | |
831 | ||
832 | void __init dbg_late_init(void) | |
833 | { | |
834 | dbg_is_early = false; | |
835 | if (kgdb_io_module_registered) | |
836 | kgdb_arch_late(); | |
837 | kdb_init(KDB_INIT_FULL); | |
838 | } | |
839 | ||
2366e047 JW |
840 | static int |
841 | dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x) | |
842 | { | |
bec4d62e JW |
843 | /* |
844 | * Take the following action on reboot notify depending on value: | |
845 | * 1 == Enter debugger | |
846 | * 0 == [the default] detatch debug client | |
847 | * -1 == Do nothing... and use this until the board resets | |
848 | */ | |
849 | switch (kgdbreboot) { | |
850 | case 1: | |
851 | kgdb_breakpoint(); | |
852 | case -1: | |
853 | goto done; | |
854 | } | |
2366e047 JW |
855 | if (!dbg_kdb_mode) |
856 | gdbstub_exit(code); | |
bec4d62e | 857 | done: |
2366e047 JW |
858 | return NOTIFY_DONE; |
859 | } | |
860 | ||
861 | static struct notifier_block dbg_reboot_notifier = { | |
862 | .notifier_call = dbg_notify_reboot, | |
863 | .next = NULL, | |
864 | .priority = INT_MAX, | |
865 | }; | |
866 | ||
dc7d5527 JW |
867 | static void kgdb_register_callbacks(void) |
868 | { | |
869 | if (!kgdb_io_module_registered) { | |
870 | kgdb_io_module_registered = 1; | |
871 | kgdb_arch_init(); | |
0b4b3827 JW |
872 | if (!dbg_is_early) |
873 | kgdb_arch_late(); | |
f30fed10 | 874 | register_module_notifier(&dbg_module_load_nb); |
2366e047 | 875 | register_reboot_notifier(&dbg_reboot_notifier); |
4402c153 JW |
876 | atomic_notifier_chain_register(&panic_notifier_list, |
877 | &kgdb_panic_event_nb); | |
dc7d5527 | 878 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 879 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
880 | #endif |
881 | if (kgdb_use_con && !kgdb_con_registered) { | |
882 | register_console(&kgdbcons); | |
883 | kgdb_con_registered = 1; | |
884 | } | |
885 | } | |
886 | } | |
887 | ||
888 | static void kgdb_unregister_callbacks(void) | |
889 | { | |
890 | /* | |
891 | * When this routine is called KGDB should unregister from the | |
892 | * panic handler and clean up, making sure it is not handling any | |
893 | * break exceptions at the time. | |
894 | */ | |
895 | if (kgdb_io_module_registered) { | |
896 | kgdb_io_module_registered = 0; | |
2366e047 | 897 | unregister_reboot_notifier(&dbg_reboot_notifier); |
f30fed10 | 898 | unregister_module_notifier(&dbg_module_load_nb); |
4402c153 JW |
899 | atomic_notifier_chain_unregister(&panic_notifier_list, |
900 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
901 | kgdb_arch_exit(); |
902 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 903 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
904 | #endif |
905 | if (kgdb_con_registered) { | |
906 | unregister_console(&kgdbcons); | |
907 | kgdb_con_registered = 0; | |
908 | } | |
909 | } | |
910 | } | |
911 | ||
1cee5e35 JW |
912 | /* |
913 | * There are times a tasklet needs to be used vs a compiled in | |
914 | * break point so as to cause an exception outside a kgdb I/O module, | |
915 | * such as is the case with kgdboe, where calling a breakpoint in the | |
916 | * I/O driver itself would be fatal. | |
917 | */ | |
918 | static void kgdb_tasklet_bpt(unsigned long ing) | |
919 | { | |
920 | kgdb_breakpoint(); | |
921 | atomic_set(&kgdb_break_tasklet_var, 0); | |
922 | } | |
923 | ||
924 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); | |
925 | ||
926 | void kgdb_schedule_breakpoint(void) | |
927 | { | |
928 | if (atomic_read(&kgdb_break_tasklet_var) || | |
929 | atomic_read(&kgdb_active) != -1 || | |
930 | atomic_read(&kgdb_setting_breakpoint)) | |
931 | return; | |
932 | atomic_inc(&kgdb_break_tasklet_var); | |
933 | tasklet_schedule(&kgdb_tasklet_breakpoint); | |
934 | } | |
935 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); | |
936 | ||
dc7d5527 JW |
937 | static void kgdb_initial_breakpoint(void) |
938 | { | |
939 | kgdb_break_asap = 0; | |
940 | ||
941 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
942 | kgdb_breakpoint(); | |
943 | } | |
944 | ||
945 | /** | |
737a460f | 946 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 947 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
948 | * |
949 | * Register it with the KGDB core. | |
950 | */ | |
53197fc4 | 951 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
952 | { |
953 | int err; | |
954 | ||
955 | spin_lock(&kgdb_registration_lock); | |
956 | ||
53197fc4 | 957 | if (dbg_io_ops) { |
dc7d5527 JW |
958 | spin_unlock(&kgdb_registration_lock); |
959 | ||
960 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
961 | "registered with KGDB.\n"); | |
962 | return -EBUSY; | |
963 | } | |
964 | ||
53197fc4 JW |
965 | if (new_dbg_io_ops->init) { |
966 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
967 | if (err) { |
968 | spin_unlock(&kgdb_registration_lock); | |
969 | return err; | |
970 | } | |
971 | } | |
972 | ||
53197fc4 | 973 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
974 | |
975 | spin_unlock(&kgdb_registration_lock); | |
976 | ||
977 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 978 | new_dbg_io_ops->name); |
dc7d5527 JW |
979 | |
980 | /* Arm KGDB now. */ | |
981 | kgdb_register_callbacks(); | |
982 | ||
983 | if (kgdb_break_asap) | |
984 | kgdb_initial_breakpoint(); | |
985 | ||
986 | return 0; | |
987 | } | |
988 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
989 | ||
990 | /** | |
991 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 992 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
993 | * |
994 | * Unregister it with the KGDB core. | |
995 | */ | |
53197fc4 | 996 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
997 | { |
998 | BUG_ON(kgdb_connected); | |
999 | ||
1000 | /* | |
1001 | * KGDB is no longer able to communicate out, so | |
1002 | * unregister our callbacks and reset state. | |
1003 | */ | |
1004 | kgdb_unregister_callbacks(); | |
1005 | ||
1006 | spin_lock(&kgdb_registration_lock); | |
1007 | ||
53197fc4 JW |
1008 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
1009 | dbg_io_ops = NULL; | |
dc7d5527 JW |
1010 | |
1011 | spin_unlock(&kgdb_registration_lock); | |
1012 | ||
1013 | printk(KERN_INFO | |
1014 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 1015 | old_dbg_io_ops->name); |
dc7d5527 JW |
1016 | } |
1017 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
1018 | ||
dcc78711 JW |
1019 | int dbg_io_get_char(void) |
1020 | { | |
1021 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
1022 | if (ret == NO_POLL_CHAR) |
1023 | return -1; | |
dcc78711 JW |
1024 | if (!dbg_kdb_mode) |
1025 | return ret; | |
1026 | if (ret == 127) | |
1027 | return 8; | |
1028 | return ret; | |
1029 | } | |
1030 | ||
dc7d5527 JW |
1031 | /** |
1032 | * kgdb_breakpoint - generate breakpoint exception | |
1033 | * | |
1034 | * This function will generate a breakpoint exception. It is used at the | |
1035 | * beginning of a program to sync up with a debugger and can be used | |
1036 | * otherwise as a quick means to stop program execution and "break" into | |
1037 | * the debugger. | |
1038 | */ | |
1039 | void kgdb_breakpoint(void) | |
1040 | { | |
ae6bf53e | 1041 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
1042 | wmb(); /* Sync point before breakpoint */ |
1043 | arch_kgdb_breakpoint(); | |
1044 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 1045 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
1046 | } |
1047 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
1048 | ||
1049 | static int __init opt_kgdb_wait(char *str) | |
1050 | { | |
1051 | kgdb_break_asap = 1; | |
1052 | ||
dcc78711 | 1053 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
1054 | if (kgdb_io_module_registered) |
1055 | kgdb_initial_breakpoint(); | |
1056 | ||
1057 | return 0; | |
1058 | } | |
1059 | ||
1060 | early_param("kgdbwait", opt_kgdb_wait); |