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> | |
9 | * Copyright (C) 2004 Pavel Machek <pavel@suse.cz> | |
10 | * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org> | |
11 | * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. | |
53197fc4 | 12 | * Copyright (C) 2005-2009 Wind River Systems, Inc. |
dc7d5527 JW |
13 | * Copyright (C) 2007 MontaVista Software, Inc. |
14 | * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
15 | * | |
16 | * Contributors at various stages not listed above: | |
17 | * Jason Wessel ( jason.wessel@windriver.com ) | |
18 | * George Anzinger <george@mvista.com> | |
19 | * Anurekh Saxena (anurekh.saxena@timesys.com) | |
20 | * Lake Stevens Instrument Division (Glenn Engel) | |
21 | * Jim Kingdon, Cygnus Support. | |
22 | * | |
23 | * Original KGDB stub: David Grothe <dave@gcom.com>, | |
24 | * Tigran Aivazian <tigran@sco.com> | |
25 | * | |
26 | * This file is licensed under the terms of the GNU General Public License | |
27 | * version 2. This program is licensed "as is" without any warranty of any | |
28 | * kind, whether express or implied. | |
29 | */ | |
30 | #include <linux/pid_namespace.h> | |
7c3078b6 | 31 | #include <linux/clocksource.h> |
dc7d5527 JW |
32 | #include <linux/interrupt.h> |
33 | #include <linux/spinlock.h> | |
34 | #include <linux/console.h> | |
35 | #include <linux/threads.h> | |
36 | #include <linux/uaccess.h> | |
37 | #include <linux/kernel.h> | |
38 | #include <linux/module.h> | |
39 | #include <linux/ptrace.h> | |
dc7d5527 JW |
40 | #include <linux/string.h> |
41 | #include <linux/delay.h> | |
42 | #include <linux/sched.h> | |
43 | #include <linux/sysrq.h> | |
44 | #include <linux/init.h> | |
45 | #include <linux/kgdb.h> | |
dcc78711 | 46 | #include <linux/kdb.h> |
dc7d5527 JW |
47 | #include <linux/pid.h> |
48 | #include <linux/smp.h> | |
49 | #include <linux/mm.h> | |
50 | ||
51 | #include <asm/cacheflush.h> | |
52 | #include <asm/byteorder.h> | |
53 | #include <asm/atomic.h> | |
54 | #include <asm/system.h> | |
55 | ||
53197fc4 | 56 | #include "debug_core.h" |
dc7d5527 | 57 | |
53197fc4 | 58 | static int kgdb_break_asap; |
62fae312 | 59 | |
53197fc4 | 60 | struct debuggerinfo_struct kgdb_info[NR_CPUS]; |
dc7d5527 JW |
61 | |
62 | /** | |
63 | * kgdb_connected - Is a host GDB connected to us? | |
64 | */ | |
65 | int kgdb_connected; | |
66 | EXPORT_SYMBOL_GPL(kgdb_connected); | |
67 | ||
68 | /* All the KGDB handlers are installed */ | |
f503b5ae | 69 | int kgdb_io_module_registered; |
dc7d5527 JW |
70 | |
71 | /* Guard for recursive entry */ | |
72 | static int exception_level; | |
73 | ||
53197fc4 | 74 | struct kgdb_io *dbg_io_ops; |
dc7d5527 JW |
75 | static DEFINE_SPINLOCK(kgdb_registration_lock); |
76 | ||
77 | /* kgdb console driver is loaded */ | |
78 | static int kgdb_con_registered; | |
79 | /* determine if kgdb console output should be used */ | |
80 | static int kgdb_use_con; | |
dcc78711 JW |
81 | /* Next cpu to become the master debug core */ |
82 | int dbg_switch_cpu; | |
83 | ||
84 | /* Use kdb or gdbserver mode */ | |
a0de055c | 85 | int dbg_kdb_mode = 1; |
dc7d5527 JW |
86 | |
87 | static int __init opt_kgdb_con(char *str) | |
88 | { | |
89 | kgdb_use_con = 1; | |
90 | return 0; | |
91 | } | |
92 | ||
93 | early_param("kgdbcon", opt_kgdb_con); | |
94 | ||
95 | module_param(kgdb_use_con, int, 0644); | |
96 | ||
97 | /* | |
98 | * Holds information about breakpoints in a kernel. These breakpoints are | |
99 | * added and removed by gdb. | |
100 | */ | |
101 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { | |
102 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } | |
103 | }; | |
104 | ||
105 | /* | |
106 | * The CPU# of the active CPU, or -1 if none: | |
107 | */ | |
108 | atomic_t kgdb_active = ATOMIC_INIT(-1); | |
dcc78711 | 109 | EXPORT_SYMBOL_GPL(kgdb_active); |
dc7d5527 JW |
110 | |
111 | /* | |
112 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early | |
113 | * bootup code (which might not have percpu set up yet): | |
114 | */ | |
115 | static atomic_t passive_cpu_wait[NR_CPUS]; | |
116 | static atomic_t cpu_in_kgdb[NR_CPUS]; | |
117 | atomic_t kgdb_setting_breakpoint; | |
118 | ||
119 | struct task_struct *kgdb_usethread; | |
120 | struct task_struct *kgdb_contthread; | |
121 | ||
122 | int kgdb_single_step; | |
53197fc4 | 123 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
124 | |
125 | /* to keep track of the CPU which is doing the single stepping*/ | |
126 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); | |
127 | ||
128 | /* | |
129 | * If you are debugging a problem where roundup (the collection of | |
130 | * all other CPUs) is a problem [this should be extremely rare], | |
131 | * then use the nokgdbroundup option to avoid roundup. In that case | |
132 | * the other CPUs might interfere with your debugging context, so | |
133 | * use this with care: | |
134 | */ | |
688b744d | 135 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
136 | |
137 | static int __init opt_nokgdbroundup(char *str) | |
138 | { | |
139 | kgdb_do_roundup = 0; | |
140 | ||
141 | return 0; | |
142 | } | |
143 | ||
144 | early_param("nokgdbroundup", opt_nokgdbroundup); | |
145 | ||
146 | /* | |
147 | * Finally, some KGDB code :-) | |
148 | */ | |
149 | ||
150 | /* | |
151 | * Weak aliases for breakpoint management, | |
152 | * can be overriden by architectures when needed: | |
153 | */ | |
dc7d5527 JW |
154 | int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr) |
155 | { | |
156 | int err; | |
157 | ||
158 | err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE); | |
159 | if (err) | |
160 | return err; | |
161 | ||
162 | return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr, | |
163 | BREAK_INSTR_SIZE); | |
164 | } | |
165 | ||
166 | int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle) | |
167 | { | |
168 | return probe_kernel_write((char *)addr, | |
169 | (char *)bundle, BREAK_INSTR_SIZE); | |
170 | } | |
171 | ||
a9b60bf4 JW |
172 | int __weak kgdb_validate_break_address(unsigned long addr) |
173 | { | |
174 | char tmp_variable[BREAK_INSTR_SIZE]; | |
175 | int err; | |
176 | /* Validate setting the breakpoint and then removing it. In the | |
177 | * remove fails, the kernel needs to emit a bad message because we | |
178 | * are deep trouble not being able to put things back the way we | |
179 | * found them. | |
180 | */ | |
181 | err = kgdb_arch_set_breakpoint(addr, tmp_variable); | |
182 | if (err) | |
183 | return err; | |
184 | err = kgdb_arch_remove_breakpoint(addr, tmp_variable); | |
185 | if (err) | |
186 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " | |
187 | "memory destroyed at: %lx", addr); | |
188 | return err; | |
189 | } | |
190 | ||
dc7d5527 JW |
191 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
192 | { | |
193 | return instruction_pointer(regs); | |
194 | } | |
195 | ||
196 | int __weak kgdb_arch_init(void) | |
197 | { | |
198 | return 0; | |
199 | } | |
200 | ||
b4b8ac52 JW |
201 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
202 | { | |
203 | return 0; | |
204 | } | |
205 | ||
dc7d5527 JW |
206 | /** |
207 | * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. | |
208 | * @regs: Current &struct pt_regs. | |
209 | * | |
210 | * This function will be called if the particular architecture must | |
211 | * disable hardware debugging while it is processing gdb packets or | |
212 | * handling exception. | |
213 | */ | |
214 | void __weak kgdb_disable_hw_debug(struct pt_regs *regs) | |
215 | { | |
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 JW |
239 | { |
240 | unsigned long addr; | |
7f8b7ed6 JW |
241 | int error; |
242 | int ret = 0; | |
dc7d5527 JW |
243 | int i; |
244 | ||
245 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
246 | if (kgdb_break[i].state != BP_SET) | |
247 | continue; | |
248 | ||
249 | addr = kgdb_break[i].bpt_addr; | |
250 | error = kgdb_arch_set_breakpoint(addr, | |
251 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
252 | if (error) { |
253 | ret = error; | |
254 | printk(KERN_INFO "KGDB: BP install failed: %lx", addr); | |
255 | continue; | |
256 | } | |
dc7d5527 JW |
257 | |
258 | kgdb_flush_swbreak_addr(addr); | |
259 | kgdb_break[i].state = BP_ACTIVE; | |
260 | } | |
7f8b7ed6 | 261 | return ret; |
dc7d5527 JW |
262 | } |
263 | ||
53197fc4 | 264 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
265 | { |
266 | int err = kgdb_validate_break_address(addr); | |
267 | int breakno = -1; | |
268 | int i; | |
269 | ||
270 | if (err) | |
271 | return err; | |
272 | ||
273 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
274 | if ((kgdb_break[i].state == BP_SET) && | |
275 | (kgdb_break[i].bpt_addr == addr)) | |
276 | return -EEXIST; | |
277 | } | |
278 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
279 | if (kgdb_break[i].state == BP_REMOVED && | |
280 | kgdb_break[i].bpt_addr == addr) { | |
281 | breakno = i; | |
282 | break; | |
283 | } | |
284 | } | |
285 | ||
286 | if (breakno == -1) { | |
287 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
288 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
289 | breakno = i; | |
290 | break; | |
291 | } | |
292 | } | |
293 | } | |
294 | ||
295 | if (breakno == -1) | |
296 | return -E2BIG; | |
297 | ||
298 | kgdb_break[breakno].state = BP_SET; | |
299 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
300 | kgdb_break[breakno].bpt_addr = addr; | |
301 | ||
302 | return 0; | |
303 | } | |
304 | ||
dcc78711 | 305 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 JW |
306 | { |
307 | unsigned long addr; | |
7f8b7ed6 JW |
308 | int error; |
309 | int ret = 0; | |
dc7d5527 JW |
310 | int i; |
311 | ||
312 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
313 | if (kgdb_break[i].state != BP_ACTIVE) | |
314 | continue; | |
315 | addr = kgdb_break[i].bpt_addr; | |
316 | error = kgdb_arch_remove_breakpoint(addr, | |
317 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
318 | if (error) { |
319 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr); | |
320 | ret = error; | |
321 | } | |
dc7d5527 JW |
322 | |
323 | kgdb_flush_swbreak_addr(addr); | |
324 | kgdb_break[i].state = BP_SET; | |
325 | } | |
7f8b7ed6 | 326 | return ret; |
dc7d5527 JW |
327 | } |
328 | ||
53197fc4 | 329 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
330 | { |
331 | int i; | |
332 | ||
333 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
334 | if ((kgdb_break[i].state == BP_SET) && | |
335 | (kgdb_break[i].bpt_addr == addr)) { | |
336 | kgdb_break[i].state = BP_REMOVED; | |
337 | return 0; | |
338 | } | |
339 | } | |
340 | return -ENOENT; | |
341 | } | |
342 | ||
343 | int kgdb_isremovedbreak(unsigned long addr) | |
344 | { | |
345 | int i; | |
346 | ||
347 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
348 | if ((kgdb_break[i].state == BP_REMOVED) && | |
349 | (kgdb_break[i].bpt_addr == addr)) | |
350 | return 1; | |
351 | } | |
352 | return 0; | |
353 | } | |
354 | ||
53197fc4 | 355 | int dbg_remove_all_break(void) |
dc7d5527 JW |
356 | { |
357 | unsigned long addr; | |
358 | int error; | |
359 | int i; | |
360 | ||
361 | /* Clear memory breakpoints. */ | |
362 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
363 | if (kgdb_break[i].state != BP_ACTIVE) |
364 | goto setundefined; | |
dc7d5527 JW |
365 | addr = kgdb_break[i].bpt_addr; |
366 | error = kgdb_arch_remove_breakpoint(addr, | |
367 | kgdb_break[i].saved_instr); | |
368 | if (error) | |
737a460f JW |
369 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
370 | addr); | |
371 | setundefined: | |
372 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
373 | } |
374 | ||
375 | /* Clear hardware breakpoints. */ | |
376 | if (arch_kgdb_ops.remove_all_hw_break) | |
377 | arch_kgdb_ops.remove_all_hw_break(); | |
378 | ||
379 | return 0; | |
380 | } | |
381 | ||
dc7d5527 JW |
382 | /* |
383 | * Return true if there is a valid kgdb I/O module. Also if no | |
384 | * debugger is attached a message can be printed to the console about | |
385 | * waiting for the debugger to attach. | |
386 | * | |
387 | * The print_wait argument is only to be true when called from inside | |
388 | * the core kgdb_handle_exception, because it will wait for the | |
389 | * debugger to attach. | |
390 | */ | |
391 | static int kgdb_io_ready(int print_wait) | |
392 | { | |
53197fc4 | 393 | if (!dbg_io_ops) |
dc7d5527 JW |
394 | return 0; |
395 | if (kgdb_connected) | |
396 | return 1; | |
397 | if (atomic_read(&kgdb_setting_breakpoint)) | |
398 | return 1; | |
dcc78711 JW |
399 | if (print_wait) { |
400 | #ifdef CONFIG_KGDB_KDB | |
401 | if (!dbg_kdb_mode) | |
402 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); | |
403 | #else | |
dc7d5527 | 404 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
405 | #endif |
406 | } | |
dc7d5527 JW |
407 | return 1; |
408 | } | |
409 | ||
dc7d5527 JW |
410 | static int kgdb_reenter_check(struct kgdb_state *ks) |
411 | { | |
412 | unsigned long addr; | |
413 | ||
414 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
415 | return 0; | |
416 | ||
417 | /* Panic on recursive debugger calls: */ | |
418 | exception_level++; | |
419 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
dcc78711 | 420 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
421 | |
422 | /* | |
423 | * If the break point removed ok at the place exception | |
424 | * occurred, try to recover and print a warning to the end | |
425 | * user because the user planted a breakpoint in a place that | |
426 | * KGDB needs in order to function. | |
427 | */ | |
53197fc4 | 428 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
429 | exception_level = 0; |
430 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 431 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
432 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
433 | addr); | |
dc7d5527 JW |
434 | WARN_ON_ONCE(1); |
435 | ||
436 | return 1; | |
437 | } | |
53197fc4 | 438 | dbg_remove_all_break(); |
dc7d5527 JW |
439 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
440 | ||
441 | if (exception_level > 1) { | |
442 | dump_stack(); | |
443 | panic("Recursive entry to debugger"); | |
444 | } | |
445 | ||
446 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
447 | dump_stack(); | |
448 | panic("Recursive entry to debugger"); | |
449 | ||
450 | return 1; | |
451 | } | |
452 | ||
dcc78711 JW |
453 | static void dbg_cpu_switch(int cpu, int next_cpu) |
454 | { | |
455 | /* Mark the cpu we are switching away from as a slave when it | |
456 | * holds the kgdb_active token. This must be done so that the | |
457 | * that all the cpus wait in for the debug core will not enter | |
458 | * again as the master. */ | |
459 | if (cpu == atomic_read(&kgdb_active)) { | |
460 | kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE; | |
461 | kgdb_info[cpu].exception_state &= ~DCPU_WANT_MASTER; | |
462 | } | |
463 | kgdb_info[next_cpu].exception_state |= DCPU_NEXT_MASTER; | |
464 | } | |
465 | ||
62fae312 | 466 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs) |
dc7d5527 | 467 | { |
dc7d5527 | 468 | unsigned long flags; |
028e7b17 | 469 | int sstep_tries = 100; |
dcc78711 | 470 | int error; |
dc7d5527 | 471 | int i, cpu; |
4da75b9c | 472 | int trace_on = 0; |
dc7d5527 JW |
473 | acquirelock: |
474 | /* | |
475 | * Interrupts will be restored by the 'trap return' code, except when | |
476 | * single stepping. | |
477 | */ | |
478 | local_irq_save(flags); | |
479 | ||
62fae312 JW |
480 | cpu = ks->cpu; |
481 | kgdb_info[cpu].debuggerinfo = regs; | |
482 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
483 | kgdb_info[cpu].ret_state = 0; |
484 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
62fae312 JW |
485 | /* |
486 | * Make sure the above info reaches the primary CPU before | |
487 | * our cpu_in_kgdb[] flag setting does: | |
488 | */ | |
ae6bf53e | 489 | atomic_inc(&cpu_in_kgdb[cpu]); |
dc7d5527 JW |
490 | |
491 | /* | |
62fae312 JW |
492 | * CPU will loop if it is a slave or request to become a kgdb |
493 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 494 | */ |
62fae312 | 495 | while (1) { |
dcc78711 JW |
496 | cpu_loop: |
497 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { | |
498 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; | |
499 | goto cpu_master_loop; | |
500 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
62fae312 JW |
501 | if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu) |
502 | break; | |
503 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { | |
504 | if (!atomic_read(&passive_cpu_wait[cpu])) | |
505 | goto return_normal; | |
506 | } else { | |
507 | return_normal: | |
508 | /* Return to normal operation by executing any | |
509 | * hw breakpoint fixup. | |
510 | */ | |
511 | if (arch_kgdb_ops.correct_hw_break) | |
512 | arch_kgdb_ops.correct_hw_break(); | |
4da75b9c JW |
513 | if (trace_on) |
514 | tracing_on(); | |
ae6bf53e | 515 | atomic_dec(&cpu_in_kgdb[cpu]); |
62fae312 JW |
516 | touch_softlockup_watchdog_sync(); |
517 | clocksource_touch_watchdog(); | |
518 | local_irq_restore(flags); | |
519 | return 0; | |
520 | } | |
dc7d5527 | 521 | cpu_relax(); |
62fae312 | 522 | } |
dc7d5527 JW |
523 | |
524 | /* | |
028e7b17 JW |
525 | * For single stepping, try to only enter on the processor |
526 | * that was single stepping. To gaurd against a deadlock, the | |
527 | * kernel will only try for the value of sstep_tries before | |
528 | * giving up and continuing on. | |
dc7d5527 JW |
529 | */ |
530 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
531 | (kgdb_info[cpu].task && |
532 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 533 | atomic_set(&kgdb_active, -1); |
d6ad3e28 | 534 | touch_softlockup_watchdog_sync(); |
7c3078b6 | 535 | clocksource_touch_watchdog(); |
dc7d5527 JW |
536 | local_irq_restore(flags); |
537 | ||
538 | goto acquirelock; | |
539 | } | |
540 | ||
541 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 542 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 543 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
544 | } |
545 | ||
546 | /* | |
547 | * Don't enter if we have hit a removed breakpoint. | |
548 | */ | |
549 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
550 | goto kgdb_restore; | |
551 | ||
552 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
553 | if (dbg_io_ops->pre_exception) |
554 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 555 | |
dc7d5527 JW |
556 | kgdb_disable_hw_debug(ks->linux_regs); |
557 | ||
558 | /* | |
559 | * Get the passive CPU lock which will hold all the non-primary | |
560 | * CPU in a spin state while the debugger is active | |
561 | */ | |
d7161a65 | 562 | if (!kgdb_single_step) { |
dc7d5527 | 563 | for (i = 0; i < NR_CPUS; i++) |
ae6bf53e | 564 | atomic_inc(&passive_cpu_wait[i]); |
dc7d5527 JW |
565 | } |
566 | ||
56fb7093 JW |
567 | #ifdef CONFIG_SMP |
568 | /* Signal the other CPUs to enter kgdb_wait() */ | |
d7161a65 | 569 | if ((!kgdb_single_step) && kgdb_do_roundup) |
56fb7093 JW |
570 | kgdb_roundup_cpus(flags); |
571 | #endif | |
572 | ||
dc7d5527 JW |
573 | /* |
574 | * Wait for the other CPUs to be notified and be waiting for us: | |
575 | */ | |
576 | for_each_online_cpu(i) { | |
dcc78711 | 577 | while (kgdb_do_roundup && !atomic_read(&cpu_in_kgdb[i])) |
dc7d5527 JW |
578 | cpu_relax(); |
579 | } | |
580 | ||
581 | /* | |
582 | * At this point the primary processor is completely | |
583 | * in the debugger and all secondary CPUs are quiescent | |
584 | */ | |
dcc78711 | 585 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 586 | kgdb_single_step = 0; |
d7161a65 | 587 | kgdb_contthread = current; |
dc7d5527 | 588 | exception_level = 0; |
4da75b9c JW |
589 | trace_on = tracing_is_on(); |
590 | if (trace_on) | |
591 | tracing_off(); | |
dc7d5527 | 592 | |
dcc78711 JW |
593 | while (1) { |
594 | cpu_master_loop: | |
595 | if (dbg_kdb_mode) { | |
596 | kgdb_connected = 1; | |
597 | error = kdb_stub(ks); | |
598 | } else { | |
599 | error = gdb_serial_stub(ks); | |
600 | } | |
601 | ||
602 | if (error == DBG_PASS_EVENT) { | |
603 | dbg_kdb_mode = !dbg_kdb_mode; | |
604 | kgdb_connected = 0; | |
605 | } else if (error == DBG_SWITCH_CPU_EVENT) { | |
606 | dbg_cpu_switch(cpu, dbg_switch_cpu); | |
607 | goto cpu_loop; | |
608 | } else { | |
609 | kgdb_info[cpu].ret_state = error; | |
610 | break; | |
611 | } | |
612 | } | |
dc7d5527 JW |
613 | |
614 | /* Call the I/O driver's post_exception routine */ | |
53197fc4 JW |
615 | if (dbg_io_ops->post_exception) |
616 | dbg_io_ops->post_exception(); | |
dc7d5527 | 617 | |
ae6bf53e | 618 | atomic_dec(&cpu_in_kgdb[ks->cpu]); |
dc7d5527 | 619 | |
d7161a65 | 620 | if (!kgdb_single_step) { |
dc7d5527 | 621 | for (i = NR_CPUS-1; i >= 0; i--) |
ae6bf53e | 622 | atomic_dec(&passive_cpu_wait[i]); |
dc7d5527 | 623 | /* |
dcc78711 JW |
624 | * Wait till all the CPUs have quit from the debugger, |
625 | * but allow a CPU that hit an exception and is | |
626 | * waiting to become the master to remain in the debug | |
627 | * core. | |
dc7d5527 JW |
628 | */ |
629 | for_each_online_cpu(i) { | |
dcc78711 JW |
630 | while (kgdb_do_roundup && |
631 | atomic_read(&cpu_in_kgdb[i]) && | |
632 | !(kgdb_info[i].exception_state & | |
633 | DCPU_WANT_MASTER)) | |
dc7d5527 JW |
634 | cpu_relax(); |
635 | } | |
636 | } | |
637 | ||
638 | kgdb_restore: | |
028e7b17 JW |
639 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
640 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
641 | if (kgdb_info[sstep_cpu].task) | |
642 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
643 | else | |
644 | kgdb_sstep_pid = 0; | |
645 | } | |
4da75b9c JW |
646 | if (trace_on) |
647 | tracing_on(); | |
dc7d5527 JW |
648 | /* Free kgdb_active */ |
649 | atomic_set(&kgdb_active, -1); | |
d6ad3e28 | 650 | touch_softlockup_watchdog_sync(); |
7c3078b6 | 651 | clocksource_touch_watchdog(); |
dc7d5527 JW |
652 | local_irq_restore(flags); |
653 | ||
dcc78711 | 654 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
655 | } |
656 | ||
62fae312 JW |
657 | /* |
658 | * kgdb_handle_exception() - main entry point from a kernel exception | |
659 | * | |
660 | * Locking hierarchy: | |
661 | * interface locks, if any (begin_session) | |
662 | * kgdb lock (kgdb_active) | |
663 | */ | |
664 | int | |
665 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
666 | { | |
667 | struct kgdb_state kgdb_var; | |
668 | struct kgdb_state *ks = &kgdb_var; | |
669 | int ret; | |
670 | ||
671 | ks->cpu = raw_smp_processor_id(); | |
672 | ks->ex_vector = evector; | |
673 | ks->signo = signo; | |
62fae312 JW |
674 | ks->err_code = ecode; |
675 | ks->kgdb_usethreadid = 0; | |
676 | ks->linux_regs = regs; | |
677 | ||
678 | if (kgdb_reenter_check(ks)) | |
679 | return 0; /* Ouch, double exception ! */ | |
680 | kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER; | |
681 | ret = kgdb_cpu_enter(ks, regs); | |
dcc78711 JW |
682 | kgdb_info[ks->cpu].exception_state &= ~(DCPU_WANT_MASTER | |
683 | DCPU_IS_SLAVE); | |
62fae312 JW |
684 | return ret; |
685 | } | |
686 | ||
dc7d5527 JW |
687 | int kgdb_nmicallback(int cpu, void *regs) |
688 | { | |
689 | #ifdef CONFIG_SMP | |
62fae312 JW |
690 | struct kgdb_state kgdb_var; |
691 | struct kgdb_state *ks = &kgdb_var; | |
692 | ||
693 | memset(ks, 0, sizeof(struct kgdb_state)); | |
694 | ks->cpu = cpu; | |
695 | ks->linux_regs = regs; | |
696 | ||
dc7d5527 | 697 | if (!atomic_read(&cpu_in_kgdb[cpu]) && |
62fae312 JW |
698 | atomic_read(&kgdb_active) != -1 && |
699 | atomic_read(&kgdb_active) != cpu) { | |
700 | kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE; | |
701 | kgdb_cpu_enter(ks, regs); | |
702 | kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE; | |
dc7d5527 JW |
703 | return 0; |
704 | } | |
705 | #endif | |
706 | return 1; | |
707 | } | |
708 | ||
aabdc3b8 JW |
709 | static void kgdb_console_write(struct console *co, const char *s, |
710 | unsigned count) | |
dc7d5527 JW |
711 | { |
712 | unsigned long flags; | |
713 | ||
714 | /* If we're debugging, or KGDB has not connected, don't try | |
715 | * and print. */ | |
dcc78711 | 716 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
717 | return; |
718 | ||
719 | local_irq_save(flags); | |
53197fc4 | 720 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
721 | local_irq_restore(flags); |
722 | } | |
723 | ||
724 | static struct console kgdbcons = { | |
725 | .name = "kgdb", | |
726 | .write = kgdb_console_write, | |
727 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
728 | .index = -1, | |
729 | }; | |
730 | ||
731 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 732 | static void sysrq_handle_dbg(int key, struct tty_struct *tty) |
dc7d5527 | 733 | { |
53197fc4 | 734 | if (!dbg_io_ops) { |
dc7d5527 JW |
735 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
736 | return; | |
737 | } | |
dcc78711 JW |
738 | if (!kgdb_connected) { |
739 | #ifdef CONFIG_KGDB_KDB | |
740 | if (!dbg_kdb_mode) | |
741 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
742 | #else | |
dc7d5527 | 743 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
744 | #endif |
745 | } | |
dc7d5527 JW |
746 | |
747 | kgdb_breakpoint(); | |
748 | } | |
749 | ||
53197fc4 JW |
750 | static struct sysrq_key_op sysrq_dbg_op = { |
751 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
752 | .help_msg = "debug(G)", |
753 | .action_msg = "DEBUG", | |
dc7d5527 JW |
754 | }; |
755 | #endif | |
756 | ||
757 | static void kgdb_register_callbacks(void) | |
758 | { | |
759 | if (!kgdb_io_module_registered) { | |
760 | kgdb_io_module_registered = 1; | |
761 | kgdb_arch_init(); | |
762 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 763 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
764 | #endif |
765 | if (kgdb_use_con && !kgdb_con_registered) { | |
766 | register_console(&kgdbcons); | |
767 | kgdb_con_registered = 1; | |
768 | } | |
769 | } | |
770 | } | |
771 | ||
772 | static void kgdb_unregister_callbacks(void) | |
773 | { | |
774 | /* | |
775 | * When this routine is called KGDB should unregister from the | |
776 | * panic handler and clean up, making sure it is not handling any | |
777 | * break exceptions at the time. | |
778 | */ | |
779 | if (kgdb_io_module_registered) { | |
780 | kgdb_io_module_registered = 0; | |
781 | kgdb_arch_exit(); | |
782 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 783 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
784 | #endif |
785 | if (kgdb_con_registered) { | |
786 | unregister_console(&kgdbcons); | |
787 | kgdb_con_registered = 0; | |
788 | } | |
789 | } | |
790 | } | |
791 | ||
792 | static void kgdb_initial_breakpoint(void) | |
793 | { | |
794 | kgdb_break_asap = 0; | |
795 | ||
796 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
797 | kgdb_breakpoint(); | |
798 | } | |
799 | ||
800 | /** | |
737a460f | 801 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 802 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
803 | * |
804 | * Register it with the KGDB core. | |
805 | */ | |
53197fc4 | 806 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
807 | { |
808 | int err; | |
809 | ||
810 | spin_lock(&kgdb_registration_lock); | |
811 | ||
53197fc4 | 812 | if (dbg_io_ops) { |
dc7d5527 JW |
813 | spin_unlock(&kgdb_registration_lock); |
814 | ||
815 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
816 | "registered with KGDB.\n"); | |
817 | return -EBUSY; | |
818 | } | |
819 | ||
53197fc4 JW |
820 | if (new_dbg_io_ops->init) { |
821 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
822 | if (err) { |
823 | spin_unlock(&kgdb_registration_lock); | |
824 | return err; | |
825 | } | |
826 | } | |
827 | ||
53197fc4 | 828 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
829 | |
830 | spin_unlock(&kgdb_registration_lock); | |
831 | ||
832 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 833 | new_dbg_io_ops->name); |
dc7d5527 JW |
834 | |
835 | /* Arm KGDB now. */ | |
836 | kgdb_register_callbacks(); | |
837 | ||
838 | if (kgdb_break_asap) | |
839 | kgdb_initial_breakpoint(); | |
840 | ||
841 | return 0; | |
842 | } | |
843 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
844 | ||
845 | /** | |
846 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 847 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
848 | * |
849 | * Unregister it with the KGDB core. | |
850 | */ | |
53197fc4 | 851 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
852 | { |
853 | BUG_ON(kgdb_connected); | |
854 | ||
855 | /* | |
856 | * KGDB is no longer able to communicate out, so | |
857 | * unregister our callbacks and reset state. | |
858 | */ | |
859 | kgdb_unregister_callbacks(); | |
860 | ||
861 | spin_lock(&kgdb_registration_lock); | |
862 | ||
53197fc4 JW |
863 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
864 | dbg_io_ops = NULL; | |
dc7d5527 JW |
865 | |
866 | spin_unlock(&kgdb_registration_lock); | |
867 | ||
868 | printk(KERN_INFO | |
869 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 870 | old_dbg_io_ops->name); |
dc7d5527 JW |
871 | } |
872 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
873 | ||
dcc78711 JW |
874 | int dbg_io_get_char(void) |
875 | { | |
876 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
877 | if (ret == NO_POLL_CHAR) |
878 | return -1; | |
dcc78711 JW |
879 | if (!dbg_kdb_mode) |
880 | return ret; | |
881 | if (ret == 127) | |
882 | return 8; | |
883 | return ret; | |
884 | } | |
885 | ||
dc7d5527 JW |
886 | /** |
887 | * kgdb_breakpoint - generate breakpoint exception | |
888 | * | |
889 | * This function will generate a breakpoint exception. It is used at the | |
890 | * beginning of a program to sync up with a debugger and can be used | |
891 | * otherwise as a quick means to stop program execution and "break" into | |
892 | * the debugger. | |
893 | */ | |
894 | void kgdb_breakpoint(void) | |
895 | { | |
ae6bf53e | 896 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
897 | wmb(); /* Sync point before breakpoint */ |
898 | arch_kgdb_breakpoint(); | |
899 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 900 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
901 | } |
902 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
903 | ||
904 | static int __init opt_kgdb_wait(char *str) | |
905 | { | |
906 | kgdb_break_asap = 1; | |
907 | ||
dcc78711 | 908 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
909 | if (kgdb_io_module_registered) |
910 | kgdb_initial_breakpoint(); | |
911 | ||
912 | return 0; | |
913 | } | |
914 | ||
915 | early_param("kgdbwait", opt_kgdb_wait); |