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> | |
2366e047 | 44 | #include <linux/reboot.h> |
dc7d5527 JW |
45 | #include <linux/init.h> |
46 | #include <linux/kgdb.h> | |
dcc78711 | 47 | #include <linux/kdb.h> |
dc7d5527 JW |
48 | #include <linux/pid.h> |
49 | #include <linux/smp.h> | |
50 | #include <linux/mm.h> | |
fb70b588 | 51 | #include <linux/rcupdate.h> |
dc7d5527 JW |
52 | |
53 | #include <asm/cacheflush.h> | |
54 | #include <asm/byteorder.h> | |
60063497 | 55 | #include <linux/atomic.h> |
dc7d5527 | 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 | ||
bec4d62e JW |
78 | /* Action for the reboot notifiter, a global allow kdb to change it */ |
79 | static int kgdbreboot; | |
dc7d5527 JW |
80 | /* kgdb console driver is loaded */ |
81 | static int kgdb_con_registered; | |
82 | /* determine if kgdb console output should be used */ | |
83 | static int kgdb_use_con; | |
0b4b3827 JW |
84 | /* Flag for alternate operations for early debugging */ |
85 | bool dbg_is_early = true; | |
dcc78711 JW |
86 | /* Next cpu to become the master debug core */ |
87 | int dbg_switch_cpu; | |
88 | ||
89 | /* Use kdb or gdbserver mode */ | |
a0de055c | 90 | int dbg_kdb_mode = 1; |
dc7d5527 JW |
91 | |
92 | static int __init opt_kgdb_con(char *str) | |
93 | { | |
94 | kgdb_use_con = 1; | |
95 | return 0; | |
96 | } | |
97 | ||
98 | early_param("kgdbcon", opt_kgdb_con); | |
99 | ||
100 | module_param(kgdb_use_con, int, 0644); | |
bec4d62e | 101 | module_param(kgdbreboot, int, 0644); |
dc7d5527 JW |
102 | |
103 | /* | |
104 | * Holds information about breakpoints in a kernel. These breakpoints are | |
105 | * added and removed by gdb. | |
106 | */ | |
107 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { | |
108 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } | |
109 | }; | |
110 | ||
111 | /* | |
112 | * The CPU# of the active CPU, or -1 if none: | |
113 | */ | |
114 | atomic_t kgdb_active = ATOMIC_INIT(-1); | |
dcc78711 | 115 | EXPORT_SYMBOL_GPL(kgdb_active); |
dfee3a7b JW |
116 | static DEFINE_RAW_SPINLOCK(dbg_master_lock); |
117 | static DEFINE_RAW_SPINLOCK(dbg_slave_lock); | |
dc7d5527 JW |
118 | |
119 | /* | |
120 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early | |
121 | * bootup code (which might not have percpu set up yet): | |
122 | */ | |
dfee3a7b JW |
123 | static atomic_t masters_in_kgdb; |
124 | static atomic_t slaves_in_kgdb; | |
1cee5e35 | 125 | static atomic_t kgdb_break_tasklet_var; |
dc7d5527 JW |
126 | atomic_t kgdb_setting_breakpoint; |
127 | ||
128 | struct task_struct *kgdb_usethread; | |
129 | struct task_struct *kgdb_contthread; | |
130 | ||
131 | int kgdb_single_step; | |
53197fc4 | 132 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
133 | |
134 | /* to keep track of the CPU which is doing the single stepping*/ | |
135 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); | |
136 | ||
137 | /* | |
138 | * If you are debugging a problem where roundup (the collection of | |
139 | * all other CPUs) is a problem [this should be extremely rare], | |
140 | * then use the nokgdbroundup option to avoid roundup. In that case | |
141 | * the other CPUs might interfere with your debugging context, so | |
142 | * use this with care: | |
143 | */ | |
688b744d | 144 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
145 | |
146 | static int __init opt_nokgdbroundup(char *str) | |
147 | { | |
148 | kgdb_do_roundup = 0; | |
149 | ||
150 | return 0; | |
151 | } | |
152 | ||
153 | early_param("nokgdbroundup", opt_nokgdbroundup); | |
154 | ||
155 | /* | |
156 | * Finally, some KGDB code :-) | |
157 | */ | |
158 | ||
159 | /* | |
160 | * Weak aliases for breakpoint management, | |
161 | * can be overriden by architectures when needed: | |
162 | */ | |
98b54aa1 | 163 | int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) |
dc7d5527 JW |
164 | { |
165 | int err; | |
166 | ||
98b54aa1 JW |
167 | err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, |
168 | BREAK_INSTR_SIZE); | |
dc7d5527 JW |
169 | if (err) |
170 | return err; | |
98b54aa1 JW |
171 | err = probe_kernel_write((char *)bpt->bpt_addr, |
172 | arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); | |
173 | return err; | |
dc7d5527 JW |
174 | } |
175 | ||
98b54aa1 | 176 | int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) |
dc7d5527 | 177 | { |
98b54aa1 JW |
178 | return probe_kernel_write((char *)bpt->bpt_addr, |
179 | (char *)bpt->saved_instr, BREAK_INSTR_SIZE); | |
dc7d5527 JW |
180 | } |
181 | ||
a9b60bf4 JW |
182 | int __weak kgdb_validate_break_address(unsigned long addr) |
183 | { | |
98b54aa1 | 184 | struct kgdb_bkpt tmp; |
a9b60bf4 | 185 | int err; |
98b54aa1 | 186 | /* Validate setting the breakpoint and then removing it. If the |
a9b60bf4 JW |
187 | * remove fails, the kernel needs to emit a bad message because we |
188 | * are deep trouble not being able to put things back the way we | |
189 | * found them. | |
190 | */ | |
98b54aa1 JW |
191 | tmp.bpt_addr = addr; |
192 | err = kgdb_arch_set_breakpoint(&tmp); | |
a9b60bf4 JW |
193 | if (err) |
194 | return err; | |
98b54aa1 | 195 | err = kgdb_arch_remove_breakpoint(&tmp); |
a9b60bf4 JW |
196 | if (err) |
197 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " | |
198 | "memory destroyed at: %lx", addr); | |
199 | return err; | |
200 | } | |
201 | ||
dc7d5527 JW |
202 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
203 | { | |
204 | return instruction_pointer(regs); | |
205 | } | |
206 | ||
207 | int __weak kgdb_arch_init(void) | |
208 | { | |
209 | return 0; | |
210 | } | |
211 | ||
b4b8ac52 JW |
212 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
213 | { | |
214 | return 0; | |
215 | } | |
216 | ||
dc7d5527 JW |
217 | /* |
218 | * Some architectures need cache flushes when we set/clear a | |
219 | * breakpoint: | |
220 | */ | |
221 | static void kgdb_flush_swbreak_addr(unsigned long addr) | |
222 | { | |
223 | if (!CACHE_FLUSH_IS_SAFE) | |
224 | return; | |
225 | ||
737a460f | 226 | if (current->mm && current->mm->mmap_cache) { |
dc7d5527 JW |
227 | flush_cache_range(current->mm->mmap_cache, |
228 | addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 | 229 | } |
1a9a3e76 JW |
230 | /* Force flush instruction cache if it was outside the mm */ |
231 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 JW |
232 | } |
233 | ||
234 | /* | |
235 | * SW breakpoint management: | |
236 | */ | |
53197fc4 | 237 | int dbg_activate_sw_breakpoints(void) |
dc7d5527 | 238 | { |
7f8b7ed6 JW |
239 | int error; |
240 | int ret = 0; | |
dc7d5527 JW |
241 | int i; |
242 | ||
243 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
244 | if (kgdb_break[i].state != BP_SET) | |
245 | continue; | |
246 | ||
98b54aa1 | 247 | error = kgdb_arch_set_breakpoint(&kgdb_break[i]); |
7f8b7ed6 JW |
248 | if (error) { |
249 | ret = error; | |
98b54aa1 JW |
250 | printk(KERN_INFO "KGDB: BP install failed: %lx", |
251 | kgdb_break[i].bpt_addr); | |
7f8b7ed6 JW |
252 | continue; |
253 | } | |
dc7d5527 | 254 | |
98b54aa1 | 255 | kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
dc7d5527 JW |
256 | kgdb_break[i].state = BP_ACTIVE; |
257 | } | |
7f8b7ed6 | 258 | return ret; |
dc7d5527 JW |
259 | } |
260 | ||
53197fc4 | 261 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
262 | { |
263 | int err = kgdb_validate_break_address(addr); | |
264 | int breakno = -1; | |
265 | int i; | |
266 | ||
267 | if (err) | |
268 | return err; | |
269 | ||
270 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
271 | if ((kgdb_break[i].state == BP_SET) && | |
272 | (kgdb_break[i].bpt_addr == addr)) | |
273 | return -EEXIST; | |
274 | } | |
275 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
276 | if (kgdb_break[i].state == BP_REMOVED && | |
277 | kgdb_break[i].bpt_addr == addr) { | |
278 | breakno = i; | |
279 | break; | |
280 | } | |
281 | } | |
282 | ||
283 | if (breakno == -1) { | |
284 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
285 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
286 | breakno = i; | |
287 | break; | |
288 | } | |
289 | } | |
290 | } | |
291 | ||
292 | if (breakno == -1) | |
293 | return -E2BIG; | |
294 | ||
295 | kgdb_break[breakno].state = BP_SET; | |
296 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
297 | kgdb_break[breakno].bpt_addr = addr; | |
298 | ||
299 | return 0; | |
300 | } | |
301 | ||
dcc78711 | 302 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 | 303 | { |
7f8b7ed6 JW |
304 | int error; |
305 | int ret = 0; | |
dc7d5527 JW |
306 | int i; |
307 | ||
308 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
309 | if (kgdb_break[i].state != BP_ACTIVE) | |
310 | continue; | |
98b54aa1 | 311 | error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
7f8b7ed6 | 312 | if (error) { |
98b54aa1 JW |
313 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", |
314 | kgdb_break[i].bpt_addr); | |
7f8b7ed6 JW |
315 | ret = error; |
316 | } | |
dc7d5527 | 317 | |
98b54aa1 | 318 | kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
dc7d5527 JW |
319 | kgdb_break[i].state = BP_SET; |
320 | } | |
7f8b7ed6 | 321 | return ret; |
dc7d5527 JW |
322 | } |
323 | ||
53197fc4 | 324 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
325 | { |
326 | int i; | |
327 | ||
328 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
329 | if ((kgdb_break[i].state == BP_SET) && | |
330 | (kgdb_break[i].bpt_addr == addr)) { | |
331 | kgdb_break[i].state = BP_REMOVED; | |
332 | return 0; | |
333 | } | |
334 | } | |
335 | return -ENOENT; | |
336 | } | |
337 | ||
338 | int kgdb_isremovedbreak(unsigned long addr) | |
339 | { | |
340 | int i; | |
341 | ||
342 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
343 | if ((kgdb_break[i].state == BP_REMOVED) && | |
344 | (kgdb_break[i].bpt_addr == addr)) | |
345 | return 1; | |
346 | } | |
347 | return 0; | |
348 | } | |
349 | ||
53197fc4 | 350 | int dbg_remove_all_break(void) |
dc7d5527 | 351 | { |
dc7d5527 JW |
352 | int error; |
353 | int i; | |
354 | ||
355 | /* Clear memory breakpoints. */ | |
356 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
357 | if (kgdb_break[i].state != BP_ACTIVE) |
358 | goto setundefined; | |
98b54aa1 | 359 | error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
dc7d5527 | 360 | if (error) |
737a460f | 361 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
98b54aa1 | 362 | kgdb_break[i].bpt_addr); |
737a460f JW |
363 | setundefined: |
364 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
365 | } |
366 | ||
367 | /* Clear hardware breakpoints. */ | |
368 | if (arch_kgdb_ops.remove_all_hw_break) | |
369 | arch_kgdb_ops.remove_all_hw_break(); | |
370 | ||
371 | return 0; | |
372 | } | |
373 | ||
dc7d5527 JW |
374 | /* |
375 | * Return true if there is a valid kgdb I/O module. Also if no | |
376 | * debugger is attached a message can be printed to the console about | |
377 | * waiting for the debugger to attach. | |
378 | * | |
379 | * The print_wait argument is only to be true when called from inside | |
380 | * the core kgdb_handle_exception, because it will wait for the | |
381 | * debugger to attach. | |
382 | */ | |
383 | static int kgdb_io_ready(int print_wait) | |
384 | { | |
53197fc4 | 385 | if (!dbg_io_ops) |
dc7d5527 JW |
386 | return 0; |
387 | if (kgdb_connected) | |
388 | return 1; | |
389 | if (atomic_read(&kgdb_setting_breakpoint)) | |
390 | return 1; | |
dcc78711 JW |
391 | if (print_wait) { |
392 | #ifdef CONFIG_KGDB_KDB | |
393 | if (!dbg_kdb_mode) | |
394 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); | |
395 | #else | |
dc7d5527 | 396 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
397 | #endif |
398 | } | |
dc7d5527 JW |
399 | return 1; |
400 | } | |
401 | ||
dc7d5527 JW |
402 | static int kgdb_reenter_check(struct kgdb_state *ks) |
403 | { | |
404 | unsigned long addr; | |
405 | ||
406 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
407 | return 0; | |
408 | ||
409 | /* Panic on recursive debugger calls: */ | |
410 | exception_level++; | |
411 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
dcc78711 | 412 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
413 | |
414 | /* | |
415 | * If the break point removed ok at the place exception | |
416 | * occurred, try to recover and print a warning to the end | |
417 | * user because the user planted a breakpoint in a place that | |
418 | * KGDB needs in order to function. | |
419 | */ | |
53197fc4 | 420 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
421 | exception_level = 0; |
422 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 423 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
424 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
425 | addr); | |
dc7d5527 JW |
426 | WARN_ON_ONCE(1); |
427 | ||
428 | return 1; | |
429 | } | |
53197fc4 | 430 | dbg_remove_all_break(); |
dc7d5527 JW |
431 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
432 | ||
433 | if (exception_level > 1) { | |
434 | dump_stack(); | |
435 | panic("Recursive entry to debugger"); | |
436 | } | |
437 | ||
438 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
6d906340 JW |
439 | #ifdef CONFIG_KGDB_KDB |
440 | /* Allow kdb to debug itself one level */ | |
441 | return 0; | |
442 | #endif | |
dc7d5527 JW |
443 | dump_stack(); |
444 | panic("Recursive entry to debugger"); | |
445 | ||
446 | return 1; | |
447 | } | |
448 | ||
16cdc628 JW |
449 | static void dbg_touch_watchdogs(void) |
450 | { | |
451 | touch_softlockup_watchdog_sync(); | |
452 | clocksource_touch_watchdog(); | |
fb70b588 | 453 | rcu_cpu_stall_reset(); |
16cdc628 JW |
454 | } |
455 | ||
dfee3a7b JW |
456 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
457 | int exception_state) | |
dc7d5527 | 458 | { |
dc7d5527 | 459 | unsigned long flags; |
028e7b17 | 460 | int sstep_tries = 100; |
dcc78711 | 461 | int error; |
dfee3a7b | 462 | int cpu; |
4da75b9c | 463 | int trace_on = 0; |
dfee3a7b | 464 | int online_cpus = num_online_cpus(); |
c1bb9a9c | 465 | |
dfee3a7b JW |
466 | kgdb_info[ks->cpu].enter_kgdb++; |
467 | kgdb_info[ks->cpu].exception_state |= exception_state; | |
468 | ||
469 | if (exception_state == DCPU_WANT_MASTER) | |
470 | atomic_inc(&masters_in_kgdb); | |
471 | else | |
472 | atomic_inc(&slaves_in_kgdb); | |
d7ba979d DD |
473 | |
474 | if (arch_kgdb_ops.disable_hw_break) | |
475 | arch_kgdb_ops.disable_hw_break(regs); | |
c1bb9a9c | 476 | |
dc7d5527 JW |
477 | acquirelock: |
478 | /* | |
479 | * Interrupts will be restored by the 'trap return' code, except when | |
480 | * single stepping. | |
481 | */ | |
482 | local_irq_save(flags); | |
483 | ||
62fae312 JW |
484 | cpu = ks->cpu; |
485 | kgdb_info[cpu].debuggerinfo = regs; | |
486 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
487 | kgdb_info[cpu].ret_state = 0; |
488 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
dc7d5527 | 489 | |
dfee3a7b JW |
490 | /* Make sure the above info reaches the primary CPU */ |
491 | smp_mb(); | |
492 | ||
493 | if (exception_level == 1) { | |
494 | if (raw_spin_trylock(&dbg_master_lock)) | |
495 | atomic_xchg(&kgdb_active, cpu); | |
6d906340 | 496 | goto cpu_master_loop; |
dfee3a7b | 497 | } |
6d906340 | 498 | |
dc7d5527 | 499 | /* |
62fae312 JW |
500 | * CPU will loop if it is a slave or request to become a kgdb |
501 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 502 | */ |
62fae312 | 503 | while (1) { |
dcc78711 JW |
504 | cpu_loop: |
505 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { | |
506 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; | |
507 | goto cpu_master_loop; | |
508 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
dfee3a7b JW |
509 | if (raw_spin_trylock(&dbg_master_lock)) { |
510 | atomic_xchg(&kgdb_active, cpu); | |
62fae312 | 511 | break; |
dfee3a7b | 512 | } |
62fae312 | 513 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
dfee3a7b | 514 | if (!raw_spin_is_locked(&dbg_slave_lock)) |
62fae312 JW |
515 | goto return_normal; |
516 | } else { | |
517 | return_normal: | |
518 | /* Return to normal operation by executing any | |
519 | * hw breakpoint fixup. | |
520 | */ | |
521 | if (arch_kgdb_ops.correct_hw_break) | |
522 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
523 | if (trace_on) |
524 | tracing_on(); | |
dfee3a7b JW |
525 | kgdb_info[cpu].exception_state &= |
526 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
527 | kgdb_info[cpu].enter_kgdb--; | |
528 | smp_mb__before_atomic_dec(); | |
529 | atomic_dec(&slaves_in_kgdb); | |
16cdc628 | 530 | dbg_touch_watchdogs(); |
62fae312 JW |
531 | local_irq_restore(flags); |
532 | return 0; | |
533 | } | |
dc7d5527 | 534 | cpu_relax(); |
62fae312 | 535 | } |
dc7d5527 JW |
536 | |
537 | /* | |
028e7b17 | 538 | * For single stepping, try to only enter on the processor |
25985edc | 539 | * that was single stepping. To guard against a deadlock, the |
028e7b17 JW |
540 | * kernel will only try for the value of sstep_tries before |
541 | * giving up and continuing on. | |
dc7d5527 JW |
542 | */ |
543 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
544 | (kgdb_info[cpu].task && |
545 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 546 | atomic_set(&kgdb_active, -1); |
dfee3a7b | 547 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 548 | dbg_touch_watchdogs(); |
dc7d5527 JW |
549 | local_irq_restore(flags); |
550 | ||
551 | goto acquirelock; | |
552 | } | |
553 | ||
554 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 555 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 556 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
557 | } |
558 | ||
559 | /* | |
560 | * Don't enter if we have hit a removed breakpoint. | |
561 | */ | |
562 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
563 | goto kgdb_restore; | |
564 | ||
565 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
566 | if (dbg_io_ops->pre_exception) |
567 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 568 | |
dc7d5527 JW |
569 | /* |
570 | * Get the passive CPU lock which will hold all the non-primary | |
571 | * CPU in a spin state while the debugger is active | |
572 | */ | |
dfee3a7b JW |
573 | if (!kgdb_single_step) |
574 | raw_spin_lock(&dbg_slave_lock); | |
dc7d5527 | 575 | |
56fb7093 JW |
576 | #ifdef CONFIG_SMP |
577 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 578 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
579 | kgdb_roundup_cpus(flags); |
580 | #endif | |
581 | ||
dc7d5527 JW |
582 | /* |
583 | * Wait for the other CPUs to be notified and be waiting for us: | |
584 | */ | |
dfee3a7b JW |
585 | while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + |
586 | atomic_read(&slaves_in_kgdb)) != online_cpus) | |
587 | cpu_relax(); | |
dc7d5527 JW |
588 | |
589 | /* | |
590 | * At this point the primary processor is completely | |
591 | * in the debugger and all secondary CPUs are quiescent | |
592 | */ | |
dcc78711 | 593 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 594 | kgdb_single_step = 0; |
d7161a65 | 595 | kgdb_contthread = current; |
dc7d5527 | 596 | exception_level = 0; |
4da75b9c JW |
597 | trace_on = tracing_is_on(); |
598 | if (trace_on) | |
599 | tracing_off(); | |
dc7d5527 | 600 | |
dcc78711 JW |
601 | while (1) { |
602 | cpu_master_loop: | |
603 | if (dbg_kdb_mode) { | |
604 | kgdb_connected = 1; | |
605 | error = kdb_stub(ks); | |
3fa43aba JW |
606 | if (error == -1) |
607 | continue; | |
b0679c63 | 608 | kgdb_connected = 0; |
dcc78711 JW |
609 | } else { |
610 | error = gdb_serial_stub(ks); | |
611 | } | |
612 | ||
613 | if (error == DBG_PASS_EVENT) { | |
614 | dbg_kdb_mode = !dbg_kdb_mode; | |
dcc78711 | 615 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
495363d3 JW |
616 | kgdb_info[dbg_switch_cpu].exception_state |= |
617 | DCPU_NEXT_MASTER; | |
dcc78711 JW |
618 | goto cpu_loop; |
619 | } else { | |
620 | kgdb_info[cpu].ret_state = error; | |
621 | break; | |
622 | } | |
623 | } | |
dc7d5527 JW |
624 | |
625 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
626 | if (dbg_io_ops->post_exception) |
627 | dbg_io_ops->post_exception(); | |
dc7d5527 | 628 | |
d7161a65 | 629 | if (!kgdb_single_step) { |
dfee3a7b JW |
630 | raw_spin_unlock(&dbg_slave_lock); |
631 | /* Wait till all the CPUs have quit from the debugger. */ | |
632 | while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) | |
633 | cpu_relax(); | |
dc7d5527 JW |
634 | } |
635 | ||
636 | kgdb_restore: | |
028e7b17 JW |
637 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
638 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
639 | if (kgdb_info[sstep_cpu].task) | |
640 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
641 | else | |
642 | kgdb_sstep_pid = 0; | |
643 | } | |
c1bb9a9c DD |
644 | if (arch_kgdb_ops.correct_hw_break) |
645 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
646 | if (trace_on) |
647 | tracing_on(); | |
dfee3a7b JW |
648 | |
649 | kgdb_info[cpu].exception_state &= | |
650 | ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); | |
651 | kgdb_info[cpu].enter_kgdb--; | |
652 | smp_mb__before_atomic_dec(); | |
653 | atomic_dec(&masters_in_kgdb); | |
dc7d5527 JW |
654 | /* Free kgdb_active */ |
655 | atomic_set(&kgdb_active, -1); | |
dfee3a7b | 656 | raw_spin_unlock(&dbg_master_lock); |
16cdc628 | 657 | dbg_touch_watchdogs(); |
dc7d5527 JW |
658 | local_irq_restore(flags); |
659 | ||
dcc78711 | 660 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
661 | } |
662 | ||
62fae312 JW |
663 | /* |
664 | * kgdb_handle_exception() - main entry point from a kernel exception | |
665 | * | |
666 | * Locking hierarchy: | |
667 | * interface locks, if any (begin_session) | |
668 | * kgdb lock (kgdb_active) | |
669 | */ | |
670 | int | |
671 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
672 | { | |
673 | struct kgdb_state kgdb_var; | |
674 | struct kgdb_state *ks = &kgdb_var; | |
62fae312 JW |
675 | |
676 | ks->cpu = raw_smp_processor_id(); | |
677 | ks->ex_vector = evector; | |
678 | ks->signo = signo; | |
62fae312 JW |
679 | ks->err_code = ecode; |
680 | ks->kgdb_usethreadid = 0; | |
681 | ks->linux_regs = regs; | |
682 | ||
683 | if (kgdb_reenter_check(ks)) | |
684 | return 0; /* Ouch, double exception ! */ | |
dfee3a7b JW |
685 | if (kgdb_info[ks->cpu].enter_kgdb != 0) |
686 | return 0; | |
687 | ||
688 | return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); | |
62fae312 JW |
689 | } |
690 | ||
dc7d5527 JW |
691 | int kgdb_nmicallback(int cpu, void *regs) |
692 | { | |
693 | #ifdef CONFIG_SMP | |
62fae312 JW |
694 | struct kgdb_state kgdb_var; |
695 | struct kgdb_state *ks = &kgdb_var; | |
696 | ||
697 | memset(ks, 0, sizeof(struct kgdb_state)); | |
698 | ks->cpu = cpu; | |
699 | ks->linux_regs = regs; | |
700 | ||
dfee3a7b JW |
701 | if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
702 | raw_spin_is_locked(&dbg_master_lock)) { | |
703 | kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); | |
dc7d5527 JW |
704 | return 0; |
705 | } | |
706 | #endif | |
707 | return 1; | |
708 | } | |
709 | ||
aabdc3b8 JW |
710 | static void kgdb_console_write(struct console *co, const char *s, |
711 | unsigned count) | |
dc7d5527 JW |
712 | { |
713 | unsigned long flags; | |
714 | ||
715 | /* If we're debugging, or KGDB has not connected, don't try | |
716 | * and print. */ | |
dcc78711 | 717 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
718 | return; |
719 | ||
720 | local_irq_save(flags); | |
53197fc4 | 721 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
722 | local_irq_restore(flags); |
723 | } | |
724 | ||
725 | static struct console kgdbcons = { | |
726 | .name = "kgdb", | |
727 | .write = kgdb_console_write, | |
728 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
729 | .index = -1, | |
730 | }; | |
731 | ||
732 | #ifdef CONFIG_MAGIC_SYSRQ | |
1495cc9d | 733 | static void sysrq_handle_dbg(int key) |
dc7d5527 | 734 | { |
53197fc4 | 735 | if (!dbg_io_ops) { |
dc7d5527 JW |
736 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
737 | return; | |
738 | } | |
dcc78711 JW |
739 | if (!kgdb_connected) { |
740 | #ifdef CONFIG_KGDB_KDB | |
741 | if (!dbg_kdb_mode) | |
742 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
743 | #else | |
dc7d5527 | 744 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
745 | #endif |
746 | } | |
dc7d5527 JW |
747 | |
748 | kgdb_breakpoint(); | |
749 | } | |
750 | ||
53197fc4 JW |
751 | static struct sysrq_key_op sysrq_dbg_op = { |
752 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
753 | .help_msg = "debug(G)", |
754 | .action_msg = "DEBUG", | |
dc7d5527 JW |
755 | }; |
756 | #endif | |
757 | ||
4402c153 JW |
758 | static int kgdb_panic_event(struct notifier_block *self, |
759 | unsigned long val, | |
760 | void *data) | |
761 | { | |
762 | if (dbg_kdb_mode) | |
763 | kdb_printf("PANIC: %s\n", (char *)data); | |
764 | kgdb_breakpoint(); | |
765 | return NOTIFY_DONE; | |
766 | } | |
767 | ||
768 | static struct notifier_block kgdb_panic_event_nb = { | |
769 | .notifier_call = kgdb_panic_event, | |
770 | .priority = INT_MAX, | |
771 | }; | |
772 | ||
0b4b3827 JW |
773 | void __weak kgdb_arch_late(void) |
774 | { | |
775 | } | |
776 | ||
777 | void __init dbg_late_init(void) | |
778 | { | |
779 | dbg_is_early = false; | |
780 | if (kgdb_io_module_registered) | |
781 | kgdb_arch_late(); | |
782 | kdb_init(KDB_INIT_FULL); | |
783 | } | |
784 | ||
2366e047 JW |
785 | static int |
786 | dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x) | |
787 | { | |
bec4d62e JW |
788 | /* |
789 | * Take the following action on reboot notify depending on value: | |
790 | * 1 == Enter debugger | |
791 | * 0 == [the default] detatch debug client | |
792 | * -1 == Do nothing... and use this until the board resets | |
793 | */ | |
794 | switch (kgdbreboot) { | |
795 | case 1: | |
796 | kgdb_breakpoint(); | |
797 | case -1: | |
798 | goto done; | |
799 | } | |
2366e047 JW |
800 | if (!dbg_kdb_mode) |
801 | gdbstub_exit(code); | |
bec4d62e | 802 | done: |
2366e047 JW |
803 | return NOTIFY_DONE; |
804 | } | |
805 | ||
806 | static struct notifier_block dbg_reboot_notifier = { | |
807 | .notifier_call = dbg_notify_reboot, | |
808 | .next = NULL, | |
809 | .priority = INT_MAX, | |
810 | }; | |
811 | ||
dc7d5527 JW |
812 | static void kgdb_register_callbacks(void) |
813 | { | |
814 | if (!kgdb_io_module_registered) { | |
815 | kgdb_io_module_registered = 1; | |
816 | kgdb_arch_init(); | |
0b4b3827 JW |
817 | if (!dbg_is_early) |
818 | kgdb_arch_late(); | |
2366e047 | 819 | register_reboot_notifier(&dbg_reboot_notifier); |
4402c153 JW |
820 | atomic_notifier_chain_register(&panic_notifier_list, |
821 | &kgdb_panic_event_nb); | |
dc7d5527 | 822 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 823 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
824 | #endif |
825 | if (kgdb_use_con && !kgdb_con_registered) { | |
826 | register_console(&kgdbcons); | |
827 | kgdb_con_registered = 1; | |
828 | } | |
829 | } | |
830 | } | |
831 | ||
832 | static void kgdb_unregister_callbacks(void) | |
833 | { | |
834 | /* | |
835 | * When this routine is called KGDB should unregister from the | |
836 | * panic handler and clean up, making sure it is not handling any | |
837 | * break exceptions at the time. | |
838 | */ | |
839 | if (kgdb_io_module_registered) { | |
840 | kgdb_io_module_registered = 0; | |
2366e047 | 841 | unregister_reboot_notifier(&dbg_reboot_notifier); |
4402c153 JW |
842 | atomic_notifier_chain_unregister(&panic_notifier_list, |
843 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
844 | kgdb_arch_exit(); |
845 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 846 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
847 | #endif |
848 | if (kgdb_con_registered) { | |
849 | unregister_console(&kgdbcons); | |
850 | kgdb_con_registered = 0; | |
851 | } | |
852 | } | |
853 | } | |
854 | ||
1cee5e35 JW |
855 | /* |
856 | * There are times a tasklet needs to be used vs a compiled in | |
857 | * break point so as to cause an exception outside a kgdb I/O module, | |
858 | * such as is the case with kgdboe, where calling a breakpoint in the | |
859 | * I/O driver itself would be fatal. | |
860 | */ | |
861 | static void kgdb_tasklet_bpt(unsigned long ing) | |
862 | { | |
863 | kgdb_breakpoint(); | |
864 | atomic_set(&kgdb_break_tasklet_var, 0); | |
865 | } | |
866 | ||
867 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); | |
868 | ||
869 | void kgdb_schedule_breakpoint(void) | |
870 | { | |
871 | if (atomic_read(&kgdb_break_tasklet_var) || | |
872 | atomic_read(&kgdb_active) != -1 || | |
873 | atomic_read(&kgdb_setting_breakpoint)) | |
874 | return; | |
875 | atomic_inc(&kgdb_break_tasklet_var); | |
876 | tasklet_schedule(&kgdb_tasklet_breakpoint); | |
877 | } | |
878 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); | |
879 | ||
dc7d5527 JW |
880 | static void kgdb_initial_breakpoint(void) |
881 | { | |
882 | kgdb_break_asap = 0; | |
883 | ||
884 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
885 | kgdb_breakpoint(); | |
886 | } | |
887 | ||
888 | /** | |
737a460f | 889 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 890 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
891 | * |
892 | * Register it with the KGDB core. | |
893 | */ | |
53197fc4 | 894 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
895 | { |
896 | int err; | |
897 | ||
898 | spin_lock(&kgdb_registration_lock); | |
899 | ||
53197fc4 | 900 | if (dbg_io_ops) { |
dc7d5527 JW |
901 | spin_unlock(&kgdb_registration_lock); |
902 | ||
903 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
904 | "registered with KGDB.\n"); | |
905 | return -EBUSY; | |
906 | } | |
907 | ||
53197fc4 JW |
908 | if (new_dbg_io_ops->init) { |
909 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
910 | if (err) { |
911 | spin_unlock(&kgdb_registration_lock); | |
912 | return err; | |
913 | } | |
914 | } | |
915 | ||
53197fc4 | 916 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
917 | |
918 | spin_unlock(&kgdb_registration_lock); | |
919 | ||
920 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 921 | new_dbg_io_ops->name); |
dc7d5527 JW |
922 | |
923 | /* Arm KGDB now. */ | |
924 | kgdb_register_callbacks(); | |
925 | ||
926 | if (kgdb_break_asap) | |
927 | kgdb_initial_breakpoint(); | |
928 | ||
929 | return 0; | |
930 | } | |
931 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
932 | ||
933 | /** | |
934 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 935 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
936 | * |
937 | * Unregister it with the KGDB core. | |
938 | */ | |
53197fc4 | 939 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
940 | { |
941 | BUG_ON(kgdb_connected); | |
942 | ||
943 | /* | |
944 | * KGDB is no longer able to communicate out, so | |
945 | * unregister our callbacks and reset state. | |
946 | */ | |
947 | kgdb_unregister_callbacks(); | |
948 | ||
949 | spin_lock(&kgdb_registration_lock); | |
950 | ||
53197fc4 JW |
951 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
952 | dbg_io_ops = NULL; | |
dc7d5527 JW |
953 | |
954 | spin_unlock(&kgdb_registration_lock); | |
955 | ||
956 | printk(KERN_INFO | |
957 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 958 | old_dbg_io_ops->name); |
dc7d5527 JW |
959 | } |
960 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
961 | ||
dcc78711 JW |
962 | int dbg_io_get_char(void) |
963 | { | |
964 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
965 | if (ret == NO_POLL_CHAR) |
966 | return -1; | |
dcc78711 JW |
967 | if (!dbg_kdb_mode) |
968 | return ret; | |
969 | if (ret == 127) | |
970 | return 8; | |
971 | return ret; | |
972 | } | |
973 | ||
dc7d5527 JW |
974 | /** |
975 | * kgdb_breakpoint - generate breakpoint exception | |
976 | * | |
977 | * This function will generate a breakpoint exception. It is used at the | |
978 | * beginning of a program to sync up with a debugger and can be used | |
979 | * otherwise as a quick means to stop program execution and "break" into | |
980 | * the debugger. | |
981 | */ | |
982 | void kgdb_breakpoint(void) | |
983 | { | |
ae6bf53e | 984 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
985 | wmb(); /* Sync point before breakpoint */ |
986 | arch_kgdb_breakpoint(); | |
987 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 988 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
989 | } |
990 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
991 | ||
992 | static int __init opt_kgdb_wait(char *str) | |
993 | { | |
994 | kgdb_break_asap = 1; | |
995 | ||
dcc78711 | 996 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
997 | if (kgdb_io_module_registered) |
998 | kgdb_initial_breakpoint(); | |
999 | ||
1000 | return 0; | |
1001 | } | |
1002 | ||
1003 | early_param("kgdbwait", opt_kgdb_wait); |