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; | |
89 | ||
90 | /* Use kdb or gdbserver mode */ | |
a0de055c | 91 | int dbg_kdb_mode = 1; |
dc7d5527 JW |
92 | |
93 | static int __init opt_kgdb_con(char *str) | |
94 | { | |
95 | kgdb_use_con = 1; | |
96 | return 0; | |
97 | } | |
98 | ||
99 | early_param("kgdbcon", opt_kgdb_con); | |
100 | ||
101 | module_param(kgdb_use_con, int, 0644); | |
bec4d62e | 102 | module_param(kgdbreboot, int, 0644); |
dc7d5527 JW |
103 | |
104 | /* | |
105 | * Holds information about breakpoints in a kernel. These breakpoints are | |
106 | * added and removed by gdb. | |
107 | */ | |
108 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { | |
109 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } | |
110 | }; | |
111 | ||
112 | /* | |
113 | * The CPU# of the active CPU, or -1 if none: | |
114 | */ | |
115 | atomic_t kgdb_active = ATOMIC_INIT(-1); | |
dcc78711 | 116 | EXPORT_SYMBOL_GPL(kgdb_active); |
dfee3a7b JW |
117 | static DEFINE_RAW_SPINLOCK(dbg_master_lock); |
118 | static DEFINE_RAW_SPINLOCK(dbg_slave_lock); | |
dc7d5527 JW |
119 | |
120 | /* | |
121 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early | |
122 | * bootup code (which might not have percpu set up yet): | |
123 | */ | |
dfee3a7b JW |
124 | static atomic_t masters_in_kgdb; |
125 | static atomic_t slaves_in_kgdb; | |
1cee5e35 | 126 | static atomic_t kgdb_break_tasklet_var; |
dc7d5527 JW |
127 | atomic_t kgdb_setting_breakpoint; |
128 | ||
129 | struct task_struct *kgdb_usethread; | |
130 | struct task_struct *kgdb_contthread; | |
131 | ||
132 | int kgdb_single_step; | |
53197fc4 | 133 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
134 | |
135 | /* to keep track of the CPU which is doing the single stepping*/ | |
136 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); | |
137 | ||
138 | /* | |
139 | * If you are debugging a problem where roundup (the collection of | |
140 | * all other CPUs) is a problem [this should be extremely rare], | |
141 | * then use the nokgdbroundup option to avoid roundup. In that case | |
142 | * the other CPUs might interfere with your debugging context, so | |
143 | * use this with care: | |
144 | */ | |
688b744d | 145 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
146 | |
147 | static int __init opt_nokgdbroundup(char *str) | |
148 | { | |
149 | kgdb_do_roundup = 0; | |
150 | ||
151 | return 0; | |
152 | } | |
153 | ||
154 | early_param("nokgdbroundup", opt_nokgdbroundup); | |
155 | ||
156 | /* | |
157 | * Finally, some KGDB code :-) | |
158 | */ | |
159 | ||
160 | /* | |
161 | * Weak aliases for breakpoint management, | |
162 | * can be overriden by architectures when needed: | |
163 | */ | |
98b54aa1 | 164 | int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) |
dc7d5527 JW |
165 | { |
166 | int err; | |
167 | ||
98b54aa1 JW |
168 | err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, |
169 | BREAK_INSTR_SIZE); | |
dc7d5527 JW |
170 | if (err) |
171 | return err; | |
98b54aa1 JW |
172 | err = probe_kernel_write((char *)bpt->bpt_addr, |
173 | arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); | |
174 | return err; | |
dc7d5527 JW |
175 | } |
176 | ||
98b54aa1 | 177 | int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) |
dc7d5527 | 178 | { |
98b54aa1 JW |
179 | return probe_kernel_write((char *)bpt->bpt_addr, |
180 | (char *)bpt->saved_instr, BREAK_INSTR_SIZE); | |
dc7d5527 JW |
181 | } |
182 | ||
a9b60bf4 JW |
183 | int __weak kgdb_validate_break_address(unsigned long addr) |
184 | { | |
98b54aa1 | 185 | struct kgdb_bkpt tmp; |
a9b60bf4 | 186 | int err; |
98b54aa1 | 187 | /* Validate setting the breakpoint and then removing it. If the |
a9b60bf4 JW |
188 | * remove fails, the kernel needs to emit a bad message because we |
189 | * are deep trouble not being able to put things back the way we | |
190 | * found them. | |
191 | */ | |
98b54aa1 JW |
192 | tmp.bpt_addr = addr; |
193 | err = kgdb_arch_set_breakpoint(&tmp); | |
a9b60bf4 JW |
194 | if (err) |
195 | return err; | |
98b54aa1 | 196 | err = kgdb_arch_remove_breakpoint(&tmp); |
a9b60bf4 JW |
197 | if (err) |
198 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " | |
199 | "memory destroyed at: %lx", addr); | |
200 | return err; | |
201 | } | |
202 | ||
dc7d5527 JW |
203 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
204 | { | |
205 | return instruction_pointer(regs); | |
206 | } | |
207 | ||
208 | int __weak kgdb_arch_init(void) | |
209 | { | |
210 | return 0; | |
211 | } | |
212 | ||
b4b8ac52 JW |
213 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
214 | { | |
215 | return 0; | |
216 | } | |
217 | ||
dc7d5527 JW |
218 | /* |
219 | * Some architectures need cache flushes when we set/clear a | |
220 | * breakpoint: | |
221 | */ | |
222 | static void kgdb_flush_swbreak_addr(unsigned long addr) | |
223 | { | |
224 | if (!CACHE_FLUSH_IS_SAFE) | |
225 | return; | |
226 | ||
737a460f | 227 | if (current->mm && current->mm->mmap_cache) { |
dc7d5527 JW |
228 | flush_cache_range(current->mm->mmap_cache, |
229 | addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 | 230 | } |
1a9a3e76 JW |
231 | /* Force flush instruction cache if it was outside the mm */ |
232 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 JW |
233 | } |
234 | ||
235 | /* | |
236 | * SW breakpoint management: | |
237 | */ | |
53197fc4 | 238 | int dbg_activate_sw_breakpoints(void) |
dc7d5527 | 239 | { |
7f8b7ed6 JW |
240 | int error; |
241 | int ret = 0; | |
dc7d5527 JW |
242 | int i; |
243 | ||
244 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
245 | if (kgdb_break[i].state != BP_SET) | |
246 | continue; | |
247 | ||
98b54aa1 | 248 | error = kgdb_arch_set_breakpoint(&kgdb_break[i]); |
7f8b7ed6 JW |
249 | if (error) { |
250 | ret = error; | |
98b54aa1 JW |
251 | printk(KERN_INFO "KGDB: BP install failed: %lx", |
252 | kgdb_break[i].bpt_addr); | |
7f8b7ed6 JW |
253 | continue; |
254 | } | |
dc7d5527 | 255 | |
98b54aa1 | 256 | kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
dc7d5527 JW |
257 | kgdb_break[i].state = BP_ACTIVE; |
258 | } | |
7f8b7ed6 | 259 | return ret; |
dc7d5527 JW |
260 | } |
261 | ||
53197fc4 | 262 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
263 | { |
264 | int err = kgdb_validate_break_address(addr); | |
265 | int breakno = -1; | |
266 | int i; | |
267 | ||
268 | if (err) | |
269 | return err; | |
270 | ||
271 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
272 | if ((kgdb_break[i].state == BP_SET) && | |
273 | (kgdb_break[i].bpt_addr == addr)) | |
274 | return -EEXIST; | |
275 | } | |
276 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
277 | if (kgdb_break[i].state == BP_REMOVED && | |
278 | kgdb_break[i].bpt_addr == addr) { | |
279 | breakno = i; | |
280 | break; | |
281 | } | |
282 | } | |
283 | ||
284 | if (breakno == -1) { | |
285 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
286 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
287 | breakno = i; | |
288 | break; | |
289 | } | |
290 | } | |
291 | } | |
292 | ||
293 | if (breakno == -1) | |
294 | return -E2BIG; | |
295 | ||
296 | kgdb_break[breakno].state = BP_SET; | |
297 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
298 | kgdb_break[breakno].bpt_addr = addr; | |
299 | ||
300 | return 0; | |
301 | } | |
302 | ||
dcc78711 | 303 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 | 304 | { |
7f8b7ed6 JW |
305 | int error; |
306 | int ret = 0; | |
dc7d5527 JW |
307 | int i; |
308 | ||
309 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
310 | if (kgdb_break[i].state != BP_ACTIVE) | |
311 | continue; | |
98b54aa1 | 312 | error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
7f8b7ed6 | 313 | if (error) { |
98b54aa1 JW |
314 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", |
315 | kgdb_break[i].bpt_addr); | |
7f8b7ed6 JW |
316 | ret = error; |
317 | } | |
dc7d5527 | 318 | |
98b54aa1 | 319 | kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
dc7d5527 JW |
320 | kgdb_break[i].state = BP_SET; |
321 | } | |
7f8b7ed6 | 322 | return ret; |
dc7d5527 JW |
323 | } |
324 | ||
53197fc4 | 325 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
326 | { |
327 | int i; | |
328 | ||
329 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
330 | if ((kgdb_break[i].state == BP_SET) && | |
331 | (kgdb_break[i].bpt_addr == addr)) { | |
332 | kgdb_break[i].state = BP_REMOVED; | |
333 | return 0; | |
334 | } | |
335 | } | |
336 | return -ENOENT; | |
337 | } | |
338 | ||
339 | int kgdb_isremovedbreak(unsigned long addr) | |
340 | { | |
341 | int i; | |
342 | ||
343 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
344 | if ((kgdb_break[i].state == BP_REMOVED) && | |
345 | (kgdb_break[i].bpt_addr == addr)) | |
346 | return 1; | |
347 | } | |
348 | return 0; | |
349 | } | |
350 | ||
53197fc4 | 351 | int dbg_remove_all_break(void) |
dc7d5527 | 352 | { |
dc7d5527 JW |
353 | int error; |
354 | int i; | |
355 | ||
356 | /* Clear memory breakpoints. */ | |
357 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
358 | if (kgdb_break[i].state != BP_ACTIVE) |
359 | goto setundefined; | |
98b54aa1 | 360 | error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
dc7d5527 | 361 | if (error) |
737a460f | 362 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
98b54aa1 | 363 | kgdb_break[i].bpt_addr); |
737a460f JW |
364 | setundefined: |
365 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
366 | } |
367 | ||
368 | /* Clear hardware breakpoints. */ | |
369 | if (arch_kgdb_ops.remove_all_hw_break) | |
370 | arch_kgdb_ops.remove_all_hw_break(); | |
371 | ||
372 | return 0; | |
373 | } | |
374 | ||
dc7d5527 JW |
375 | /* |
376 | * Return true if there is a valid kgdb I/O module. Also if no | |
377 | * debugger is attached a message can be printed to the console about | |
378 | * waiting for the debugger to attach. | |
379 | * | |
380 | * The print_wait argument is only to be true when called from inside | |
381 | * the core kgdb_handle_exception, because it will wait for the | |
382 | * debugger to attach. | |
383 | */ | |
384 | static int kgdb_io_ready(int print_wait) | |
385 | { | |
53197fc4 | 386 | if (!dbg_io_ops) |
dc7d5527 JW |
387 | return 0; |
388 | if (kgdb_connected) | |
389 | return 1; | |
390 | if (atomic_read(&kgdb_setting_breakpoint)) | |
391 | return 1; | |
dcc78711 JW |
392 | if (print_wait) { |
393 | #ifdef CONFIG_KGDB_KDB | |
394 | if (!dbg_kdb_mode) | |
395 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); | |
396 | #else | |
dc7d5527 | 397 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
398 | #endif |
399 | } | |
dc7d5527 JW |
400 | return 1; |
401 | } | |
402 | ||
dc7d5527 JW |
403 | static int kgdb_reenter_check(struct kgdb_state *ks) |
404 | { | |
405 | unsigned long addr; | |
406 | ||
407 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
408 | return 0; | |
409 | ||
410 | /* Panic on recursive debugger calls: */ | |
411 | exception_level++; | |
412 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
dcc78711 | 413 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
414 | |
415 | /* | |
416 | * If the break point removed ok at the place exception | |
417 | * occurred, try to recover and print a warning to the end | |
418 | * user because the user planted a breakpoint in a place that | |
419 | * KGDB needs in order to function. | |
420 | */ | |
53197fc4 | 421 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
422 | exception_level = 0; |
423 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 424 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
425 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
426 | addr); | |
dc7d5527 JW |
427 | WARN_ON_ONCE(1); |
428 | ||
429 | return 1; | |
430 | } | |
53197fc4 | 431 | dbg_remove_all_break(); |
dc7d5527 JW |
432 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
433 | ||
434 | if (exception_level > 1) { | |
435 | dump_stack(); | |
436 | panic("Recursive entry to debugger"); | |
437 | } | |
438 | ||
439 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
6d906340 JW |
440 | #ifdef CONFIG_KGDB_KDB |
441 | /* Allow kdb to debug itself one level */ | |
442 | return 0; | |
443 | #endif | |
dc7d5527 JW |
444 | dump_stack(); |
445 | panic("Recursive entry to debugger"); | |
446 | ||
447 | return 1; | |
448 | } | |
449 | ||
16cdc628 JW |
450 | static void dbg_touch_watchdogs(void) |
451 | { | |
452 | touch_softlockup_watchdog_sync(); | |
453 | clocksource_touch_watchdog(); | |
fb70b588 | 454 | rcu_cpu_stall_reset(); |
16cdc628 JW |
455 | } |
456 | ||
dfee3a7b JW |
457 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
458 | int exception_state) | |
dc7d5527 | 459 | { |
dc7d5527 | 460 | unsigned long flags; |
028e7b17 | 461 | int sstep_tries = 100; |
dcc78711 | 462 | int error; |
dfee3a7b | 463 | int cpu; |
4da75b9c | 464 | int trace_on = 0; |
dfee3a7b | 465 | int online_cpus = num_online_cpus(); |
c1bb9a9c | 466 | |
dfee3a7b JW |
467 | kgdb_info[ks->cpu].enter_kgdb++; |
468 | kgdb_info[ks->cpu].exception_state |= exception_state; | |
469 | ||
470 | if (exception_state == DCPU_WANT_MASTER) | |
471 | atomic_inc(&masters_in_kgdb); | |
472 | else | |
473 | atomic_inc(&slaves_in_kgdb); | |
d7ba979d DD |
474 | |
475 | if (arch_kgdb_ops.disable_hw_break) | |
476 | arch_kgdb_ops.disable_hw_break(regs); | |
c1bb9a9c | 477 | |
dc7d5527 JW |
478 | acquirelock: |
479 | /* | |
480 | * Interrupts will be restored by the 'trap return' code, except when | |
481 | * single stepping. | |
482 | */ | |
483 | local_irq_save(flags); | |
484 | ||
62fae312 JW |
485 | cpu = ks->cpu; |
486 | kgdb_info[cpu].debuggerinfo = regs; | |
487 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
488 | kgdb_info[cpu].ret_state = 0; |
489 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
dc7d5527 | 490 | |
dfee3a7b JW |
491 | /* Make sure the above info reaches the primary CPU */ |
492 | smp_mb(); | |
493 | ||
494 | if (exception_level == 1) { | |
495 | if (raw_spin_trylock(&dbg_master_lock)) | |
496 | atomic_xchg(&kgdb_active, cpu); | |
6d906340 | 497 | goto cpu_master_loop; |
dfee3a7b | 498 | } |
6d906340 | 499 | |
dc7d5527 | 500 | /* |
62fae312 JW |
501 | * CPU will loop if it is a slave or request to become a kgdb |
502 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 503 | */ |
62fae312 | 504 | while (1) { |
dcc78711 JW |
505 | cpu_loop: |
506 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { | |
507 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; | |
508 | goto cpu_master_loop; | |
509 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
dfee3a7b JW |
510 | if (raw_spin_trylock(&dbg_master_lock)) { |
511 | atomic_xchg(&kgdb_active, cpu); | |
62fae312 | 512 | break; |
dfee3a7b | 513 | } |
62fae312 | 514 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
dfee3a7b | 515 | if (!raw_spin_is_locked(&dbg_slave_lock)) |
62fae312 JW |
516 | goto return_normal; |
517 | } else { | |
518 | return_normal: | |
519 | /* Return to normal operation by executing any | |
520 | * hw breakpoint fixup. | |
521 | */ | |
522 | if (arch_kgdb_ops.correct_hw_break) | |
523 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
524 | if (trace_on) |
525 | tracing_on(); | |
dfee3a7b JW |
526 | kgdb_info[cpu].exception_state &= |
527 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
528 | kgdb_info[cpu].enter_kgdb--; | |
529 | smp_mb__before_atomic_dec(); | |
530 | atomic_dec(&slaves_in_kgdb); | |
16cdc628 | 531 | dbg_touch_watchdogs(); |
62fae312 JW |
532 | local_irq_restore(flags); |
533 | return 0; | |
534 | } | |
dc7d5527 | 535 | cpu_relax(); |
62fae312 | 536 | } |
dc7d5527 JW |
537 | |
538 | /* | |
028e7b17 | 539 | * For single stepping, try to only enter on the processor |
25985edc | 540 | * that was single stepping. To guard against a deadlock, the |
028e7b17 JW |
541 | * kernel will only try for the value of sstep_tries before |
542 | * giving up and continuing on. | |
dc7d5527 JW |
543 | */ |
544 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
545 | (kgdb_info[cpu].task && |
546 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 547 | atomic_set(&kgdb_active, -1); |
dfee3a7b | 548 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 549 | dbg_touch_watchdogs(); |
dc7d5527 JW |
550 | local_irq_restore(flags); |
551 | ||
552 | goto acquirelock; | |
553 | } | |
554 | ||
555 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 556 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 557 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
558 | } |
559 | ||
560 | /* | |
561 | * Don't enter if we have hit a removed breakpoint. | |
562 | */ | |
563 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
564 | goto kgdb_restore; | |
565 | ||
566 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
567 | if (dbg_io_ops->pre_exception) |
568 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 569 | |
dc7d5527 JW |
570 | /* |
571 | * Get the passive CPU lock which will hold all the non-primary | |
572 | * CPU in a spin state while the debugger is active | |
573 | */ | |
dfee3a7b JW |
574 | if (!kgdb_single_step) |
575 | raw_spin_lock(&dbg_slave_lock); | |
dc7d5527 | 576 | |
56fb7093 JW |
577 | #ifdef CONFIG_SMP |
578 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 579 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
580 | kgdb_roundup_cpus(flags); |
581 | #endif | |
582 | ||
dc7d5527 JW |
583 | /* |
584 | * Wait for the other CPUs to be notified and be waiting for us: | |
585 | */ | |
dfee3a7b JW |
586 | while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + |
587 | atomic_read(&slaves_in_kgdb)) != online_cpus) | |
588 | cpu_relax(); | |
dc7d5527 JW |
589 | |
590 | /* | |
591 | * At this point the primary processor is completely | |
592 | * in the debugger and all secondary CPUs are quiescent | |
593 | */ | |
dcc78711 | 594 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 595 | kgdb_single_step = 0; |
d7161a65 | 596 | kgdb_contthread = current; |
dc7d5527 | 597 | exception_level = 0; |
4da75b9c JW |
598 | trace_on = tracing_is_on(); |
599 | if (trace_on) | |
600 | tracing_off(); | |
dc7d5527 | 601 | |
dcc78711 JW |
602 | while (1) { |
603 | cpu_master_loop: | |
604 | if (dbg_kdb_mode) { | |
605 | kgdb_connected = 1; | |
606 | error = kdb_stub(ks); | |
3fa43aba JW |
607 | if (error == -1) |
608 | continue; | |
b0679c63 | 609 | kgdb_connected = 0; |
dcc78711 JW |
610 | } else { |
611 | error = gdb_serial_stub(ks); | |
612 | } | |
613 | ||
614 | if (error == DBG_PASS_EVENT) { | |
615 | dbg_kdb_mode = !dbg_kdb_mode; | |
dcc78711 | 616 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
495363d3 JW |
617 | kgdb_info[dbg_switch_cpu].exception_state |= |
618 | DCPU_NEXT_MASTER; | |
dcc78711 JW |
619 | goto cpu_loop; |
620 | } else { | |
621 | kgdb_info[cpu].ret_state = error; | |
622 | break; | |
623 | } | |
624 | } | |
dc7d5527 JW |
625 | |
626 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
627 | if (dbg_io_ops->post_exception) |
628 | dbg_io_ops->post_exception(); | |
dc7d5527 | 629 | |
d7161a65 | 630 | if (!kgdb_single_step) { |
dfee3a7b JW |
631 | raw_spin_unlock(&dbg_slave_lock); |
632 | /* Wait till all the CPUs have quit from the debugger. */ | |
633 | while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) | |
634 | cpu_relax(); | |
dc7d5527 JW |
635 | } |
636 | ||
637 | kgdb_restore: | |
028e7b17 JW |
638 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
639 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
640 | if (kgdb_info[sstep_cpu].task) | |
641 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
642 | else | |
643 | kgdb_sstep_pid = 0; | |
644 | } | |
c1bb9a9c DD |
645 | if (arch_kgdb_ops.correct_hw_break) |
646 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
647 | if (trace_on) |
648 | tracing_on(); | |
dfee3a7b JW |
649 | |
650 | kgdb_info[cpu].exception_state &= | |
651 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
652 | kgdb_info[cpu].enter_kgdb--; | |
653 | smp_mb__before_atomic_dec(); | |
654 | atomic_dec(&masters_in_kgdb); | |
dc7d5527 JW |
655 | /* Free kgdb_active */ |
656 | atomic_set(&kgdb_active, -1); | |
dfee3a7b | 657 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 658 | dbg_touch_watchdogs(); |
dc7d5527 JW |
659 | local_irq_restore(flags); |
660 | ||
dcc78711 | 661 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
662 | } |
663 | ||
62fae312 JW |
664 | /* |
665 | * kgdb_handle_exception() - main entry point from a kernel exception | |
666 | * | |
667 | * Locking hierarchy: | |
668 | * interface locks, if any (begin_session) | |
669 | * kgdb lock (kgdb_active) | |
670 | */ | |
671 | int | |
672 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
673 | { | |
674 | struct kgdb_state kgdb_var; | |
675 | struct kgdb_state *ks = &kgdb_var; | |
5a14fead AV |
676 | int ret = 0; |
677 | ||
678 | if (arch_kgdb_ops.enable_nmi) | |
679 | arch_kgdb_ops.enable_nmi(0); | |
62fae312 JW |
680 | |
681 | ks->cpu = raw_smp_processor_id(); | |
682 | ks->ex_vector = evector; | |
683 | ks->signo = signo; | |
62fae312 JW |
684 | ks->err_code = ecode; |
685 | ks->kgdb_usethreadid = 0; | |
686 | ks->linux_regs = regs; | |
687 | ||
688 | if (kgdb_reenter_check(ks)) | |
5a14fead | 689 | goto out; /* Ouch, double exception ! */ |
dfee3a7b | 690 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
5a14fead | 691 | goto out; |
dfee3a7b | 692 | |
5a14fead AV |
693 | ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); |
694 | out: | |
695 | if (arch_kgdb_ops.enable_nmi) | |
696 | arch_kgdb_ops.enable_nmi(1); | |
697 | return ret; | |
62fae312 JW |
698 | } |
699 | ||
f30fed10 JW |
700 | /* |
701 | * GDB places a breakpoint at this function to know dynamically | |
702 | * loaded objects. It's not defined static so that only one instance with this | |
703 | * name exists in the kernel. | |
704 | */ | |
705 | ||
706 | static int module_event(struct notifier_block *self, unsigned long val, | |
707 | void *data) | |
708 | { | |
709 | return 0; | |
710 | } | |
711 | ||
712 | static struct notifier_block dbg_module_load_nb = { | |
713 | .notifier_call = module_event, | |
714 | }; | |
715 | ||
dc7d5527 JW |
716 | int kgdb_nmicallback(int cpu, void *regs) |
717 | { | |
718 | #ifdef CONFIG_SMP | |
62fae312 JW |
719 | struct kgdb_state kgdb_var; |
720 | struct kgdb_state *ks = &kgdb_var; | |
721 | ||
722 | memset(ks, 0, sizeof(struct kgdb_state)); | |
723 | ks->cpu = cpu; | |
724 | ks->linux_regs = regs; | |
725 | ||
dfee3a7b JW |
726 | if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
727 | raw_spin_is_locked(&dbg_master_lock)) { | |
728 | kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); | |
dc7d5527 JW |
729 | return 0; |
730 | } | |
731 | #endif | |
732 | return 1; | |
733 | } | |
734 | ||
aabdc3b8 JW |
735 | static void kgdb_console_write(struct console *co, const char *s, |
736 | unsigned count) | |
dc7d5527 JW |
737 | { |
738 | unsigned long flags; | |
739 | ||
740 | /* If we're debugging, or KGDB has not connected, don't try | |
741 | * and print. */ | |
dcc78711 | 742 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
743 | return; |
744 | ||
745 | local_irq_save(flags); | |
53197fc4 | 746 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
747 | local_irq_restore(flags); |
748 | } | |
749 | ||
750 | static struct console kgdbcons = { | |
751 | .name = "kgdb", | |
752 | .write = kgdb_console_write, | |
753 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
754 | .index = -1, | |
755 | }; | |
756 | ||
757 | #ifdef CONFIG_MAGIC_SYSRQ | |
1495cc9d | 758 | static void sysrq_handle_dbg(int key) |
dc7d5527 | 759 | { |
53197fc4 | 760 | if (!dbg_io_ops) { |
dc7d5527 JW |
761 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
762 | return; | |
763 | } | |
dcc78711 JW |
764 | if (!kgdb_connected) { |
765 | #ifdef CONFIG_KGDB_KDB | |
766 | if (!dbg_kdb_mode) | |
767 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
768 | #else | |
dc7d5527 | 769 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
770 | #endif |
771 | } | |
dc7d5527 JW |
772 | |
773 | kgdb_breakpoint(); | |
774 | } | |
775 | ||
53197fc4 JW |
776 | static struct sysrq_key_op sysrq_dbg_op = { |
777 | .handler = sysrq_handle_dbg, | |
f3456509 | 778 | .help_msg = "debug(g)", |
364b5b7b | 779 | .action_msg = "DEBUG", |
dc7d5527 JW |
780 | }; |
781 | #endif | |
782 | ||
4402c153 JW |
783 | static int kgdb_panic_event(struct notifier_block *self, |
784 | unsigned long val, | |
785 | void *data) | |
786 | { | |
787 | if (dbg_kdb_mode) | |
788 | kdb_printf("PANIC: %s\n", (char *)data); | |
789 | kgdb_breakpoint(); | |
790 | return NOTIFY_DONE; | |
791 | } | |
792 | ||
793 | static struct notifier_block kgdb_panic_event_nb = { | |
794 | .notifier_call = kgdb_panic_event, | |
795 | .priority = INT_MAX, | |
796 | }; | |
797 | ||
0b4b3827 JW |
798 | void __weak kgdb_arch_late(void) |
799 | { | |
800 | } | |
801 | ||
802 | void __init dbg_late_init(void) | |
803 | { | |
804 | dbg_is_early = false; | |
805 | if (kgdb_io_module_registered) | |
806 | kgdb_arch_late(); | |
807 | kdb_init(KDB_INIT_FULL); | |
808 | } | |
809 | ||
2366e047 JW |
810 | static int |
811 | dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x) | |
812 | { | |
bec4d62e JW |
813 | /* |
814 | * Take the following action on reboot notify depending on value: | |
815 | * 1 == Enter debugger | |
816 | * 0 == [the default] detatch debug client | |
817 | * -1 == Do nothing... and use this until the board resets | |
818 | */ | |
819 | switch (kgdbreboot) { | |
820 | case 1: | |
821 | kgdb_breakpoint(); | |
822 | case -1: | |
823 | goto done; | |
824 | } | |
2366e047 JW |
825 | if (!dbg_kdb_mode) |
826 | gdbstub_exit(code); | |
bec4d62e | 827 | done: |
2366e047 JW |
828 | return NOTIFY_DONE; |
829 | } | |
830 | ||
831 | static struct notifier_block dbg_reboot_notifier = { | |
832 | .notifier_call = dbg_notify_reboot, | |
833 | .next = NULL, | |
834 | .priority = INT_MAX, | |
835 | }; | |
836 | ||
dc7d5527 JW |
837 | static void kgdb_register_callbacks(void) |
838 | { | |
839 | if (!kgdb_io_module_registered) { | |
840 | kgdb_io_module_registered = 1; | |
841 | kgdb_arch_init(); | |
0b4b3827 JW |
842 | if (!dbg_is_early) |
843 | kgdb_arch_late(); | |
f30fed10 | 844 | register_module_notifier(&dbg_module_load_nb); |
2366e047 | 845 | register_reboot_notifier(&dbg_reboot_notifier); |
4402c153 JW |
846 | atomic_notifier_chain_register(&panic_notifier_list, |
847 | &kgdb_panic_event_nb); | |
dc7d5527 | 848 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 849 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
850 | #endif |
851 | if (kgdb_use_con && !kgdb_con_registered) { | |
852 | register_console(&kgdbcons); | |
853 | kgdb_con_registered = 1; | |
854 | } | |
855 | } | |
856 | } | |
857 | ||
858 | static void kgdb_unregister_callbacks(void) | |
859 | { | |
860 | /* | |
861 | * When this routine is called KGDB should unregister from the | |
862 | * panic handler and clean up, making sure it is not handling any | |
863 | * break exceptions at the time. | |
864 | */ | |
865 | if (kgdb_io_module_registered) { | |
866 | kgdb_io_module_registered = 0; | |
2366e047 | 867 | unregister_reboot_notifier(&dbg_reboot_notifier); |
f30fed10 | 868 | unregister_module_notifier(&dbg_module_load_nb); |
4402c153 JW |
869 | atomic_notifier_chain_unregister(&panic_notifier_list, |
870 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
871 | kgdb_arch_exit(); |
872 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 873 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
874 | #endif |
875 | if (kgdb_con_registered) { | |
876 | unregister_console(&kgdbcons); | |
877 | kgdb_con_registered = 0; | |
878 | } | |
879 | } | |
880 | } | |
881 | ||
1cee5e35 JW |
882 | /* |
883 | * There are times a tasklet needs to be used vs a compiled in | |
884 | * break point so as to cause an exception outside a kgdb I/O module, | |
885 | * such as is the case with kgdboe, where calling a breakpoint in the | |
886 | * I/O driver itself would be fatal. | |
887 | */ | |
888 | static void kgdb_tasklet_bpt(unsigned long ing) | |
889 | { | |
890 | kgdb_breakpoint(); | |
891 | atomic_set(&kgdb_break_tasklet_var, 0); | |
892 | } | |
893 | ||
894 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); | |
895 | ||
896 | void kgdb_schedule_breakpoint(void) | |
897 | { | |
898 | if (atomic_read(&kgdb_break_tasklet_var) || | |
899 | atomic_read(&kgdb_active) != -1 || | |
900 | atomic_read(&kgdb_setting_breakpoint)) | |
901 | return; | |
902 | atomic_inc(&kgdb_break_tasklet_var); | |
903 | tasklet_schedule(&kgdb_tasklet_breakpoint); | |
904 | } | |
905 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); | |
906 | ||
dc7d5527 JW |
907 | static void kgdb_initial_breakpoint(void) |
908 | { | |
909 | kgdb_break_asap = 0; | |
910 | ||
911 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
912 | kgdb_breakpoint(); | |
913 | } | |
914 | ||
915 | /** | |
737a460f | 916 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 917 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
918 | * |
919 | * Register it with the KGDB core. | |
920 | */ | |
53197fc4 | 921 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
922 | { |
923 | int err; | |
924 | ||
925 | spin_lock(&kgdb_registration_lock); | |
926 | ||
53197fc4 | 927 | if (dbg_io_ops) { |
dc7d5527 JW |
928 | spin_unlock(&kgdb_registration_lock); |
929 | ||
930 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
931 | "registered with KGDB.\n"); | |
932 | return -EBUSY; | |
933 | } | |
934 | ||
53197fc4 JW |
935 | if (new_dbg_io_ops->init) { |
936 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
937 | if (err) { |
938 | spin_unlock(&kgdb_registration_lock); | |
939 | return err; | |
940 | } | |
941 | } | |
942 | ||
53197fc4 | 943 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
944 | |
945 | spin_unlock(&kgdb_registration_lock); | |
946 | ||
947 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 948 | new_dbg_io_ops->name); |
dc7d5527 JW |
949 | |
950 | /* Arm KGDB now. */ | |
951 | kgdb_register_callbacks(); | |
952 | ||
953 | if (kgdb_break_asap) | |
954 | kgdb_initial_breakpoint(); | |
955 | ||
956 | return 0; | |
957 | } | |
958 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
959 | ||
960 | /** | |
961 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 962 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
963 | * |
964 | * Unregister it with the KGDB core. | |
965 | */ | |
53197fc4 | 966 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
967 | { |
968 | BUG_ON(kgdb_connected); | |
969 | ||
970 | /* | |
971 | * KGDB is no longer able to communicate out, so | |
972 | * unregister our callbacks and reset state. | |
973 | */ | |
974 | kgdb_unregister_callbacks(); | |
975 | ||
976 | spin_lock(&kgdb_registration_lock); | |
977 | ||
53197fc4 JW |
978 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
979 | dbg_io_ops = NULL; | |
dc7d5527 JW |
980 | |
981 | spin_unlock(&kgdb_registration_lock); | |
982 | ||
983 | printk(KERN_INFO | |
984 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 985 | old_dbg_io_ops->name); |
dc7d5527 JW |
986 | } |
987 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
988 | ||
dcc78711 JW |
989 | int dbg_io_get_char(void) |
990 | { | |
991 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
992 | if (ret == NO_POLL_CHAR) |
993 | return -1; | |
dcc78711 JW |
994 | if (!dbg_kdb_mode) |
995 | return ret; | |
996 | if (ret == 127) | |
997 | return 8; | |
998 | return ret; | |
999 | } | |
1000 | ||
dc7d5527 JW |
1001 | /** |
1002 | * kgdb_breakpoint - generate breakpoint exception | |
1003 | * | |
1004 | * This function will generate a breakpoint exception. It is used at the | |
1005 | * beginning of a program to sync up with a debugger and can be used | |
1006 | * otherwise as a quick means to stop program execution and "break" into | |
1007 | * the debugger. | |
1008 | */ | |
1009 | void kgdb_breakpoint(void) | |
1010 | { | |
ae6bf53e | 1011 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
1012 | wmb(); /* Sync point before breakpoint */ |
1013 | arch_kgdb_breakpoint(); | |
1014 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 1015 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
1016 | } |
1017 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
1018 | ||
1019 | static int __init opt_kgdb_wait(char *str) | |
1020 | { | |
1021 | kgdb_break_asap = 1; | |
1022 | ||
dcc78711 | 1023 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
1024 | if (kgdb_io_module_registered) |
1025 | kgdb_initial_breakpoint(); | |
1026 | ||
1027 | return 0; | |
1028 | } | |
1029 | ||
1030 | early_param("kgdbwait", opt_kgdb_wait); |