Commit | Line | Data |
---|---|---|
dc7d5527 | 1 | /* |
53197fc4 | 2 | * Kernel Debug Core |
dc7d5527 JW |
3 | * |
4 | * Maintainer: Jason Wessel <jason.wessel@windriver.com> | |
5 | * | |
6 | * Copyright (C) 2000-2001 VERITAS Software Corporation. | |
7 | * Copyright (C) 2002-2004 Timesys Corporation | |
8 | * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com> | |
a2531293 | 9 | * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz> |
dc7d5527 JW |
10 | * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org> |
11 | * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. | |
53197fc4 | 12 | * Copyright (C) 2005-2009 Wind River Systems, Inc. |
dc7d5527 JW |
13 | * Copyright (C) 2007 MontaVista Software, Inc. |
14 | * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
15 | * | |
16 | * Contributors at various stages not listed above: | |
17 | * Jason Wessel ( jason.wessel@windriver.com ) | |
18 | * George Anzinger <george@mvista.com> | |
19 | * Anurekh Saxena (anurekh.saxena@timesys.com) | |
20 | * Lake Stevens Instrument Division (Glenn Engel) | |
21 | * Jim Kingdon, Cygnus Support. | |
22 | * | |
23 | * Original KGDB stub: David Grothe <dave@gcom.com>, | |
24 | * Tigran Aivazian <tigran@sco.com> | |
25 | * | |
26 | * This file is licensed under the terms of the GNU General Public License | |
27 | * version 2. This program is licensed "as is" without any warranty of any | |
28 | * kind, whether express or implied. | |
29 | */ | |
30 | #include <linux/pid_namespace.h> | |
7c3078b6 | 31 | #include <linux/clocksource.h> |
dc7d5527 JW |
32 | #include <linux/interrupt.h> |
33 | #include <linux/spinlock.h> | |
34 | #include <linux/console.h> | |
35 | #include <linux/threads.h> | |
36 | #include <linux/uaccess.h> | |
37 | #include <linux/kernel.h> | |
38 | #include <linux/module.h> | |
39 | #include <linux/ptrace.h> | |
dc7d5527 JW |
40 | #include <linux/string.h> |
41 | #include <linux/delay.h> | |
42 | #include <linux/sched.h> | |
43 | #include <linux/sysrq.h> | |
44 | #include <linux/init.h> | |
45 | #include <linux/kgdb.h> | |
dcc78711 | 46 | #include <linux/kdb.h> |
dc7d5527 JW |
47 | #include <linux/pid.h> |
48 | #include <linux/smp.h> | |
49 | #include <linux/mm.h> | |
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; | |
0b4b3827 JW |
81 | /* Flag for alternate operations for early debugging */ |
82 | bool dbg_is_early = true; | |
dcc78711 JW |
83 | /* Next cpu to become the master debug core */ |
84 | int dbg_switch_cpu; | |
85 | ||
86 | /* Use kdb or gdbserver mode */ | |
a0de055c | 87 | int dbg_kdb_mode = 1; |
dc7d5527 JW |
88 | |
89 | static int __init opt_kgdb_con(char *str) | |
90 | { | |
91 | kgdb_use_con = 1; | |
92 | return 0; | |
93 | } | |
94 | ||
95 | early_param("kgdbcon", opt_kgdb_con); | |
96 | ||
97 | module_param(kgdb_use_con, int, 0644); | |
98 | ||
99 | /* | |
100 | * Holds information about breakpoints in a kernel. These breakpoints are | |
101 | * added and removed by gdb. | |
102 | */ | |
103 | static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { | |
104 | [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } | |
105 | }; | |
106 | ||
107 | /* | |
108 | * The CPU# of the active CPU, or -1 if none: | |
109 | */ | |
110 | atomic_t kgdb_active = ATOMIC_INIT(-1); | |
dcc78711 | 111 | EXPORT_SYMBOL_GPL(kgdb_active); |
dc7d5527 JW |
112 | |
113 | /* | |
114 | * We use NR_CPUs not PERCPU, in case kgdb is used to debug early | |
115 | * bootup code (which might not have percpu set up yet): | |
116 | */ | |
117 | static atomic_t passive_cpu_wait[NR_CPUS]; | |
118 | static atomic_t cpu_in_kgdb[NR_CPUS]; | |
1cee5e35 | 119 | static atomic_t kgdb_break_tasklet_var; |
dc7d5527 JW |
120 | atomic_t kgdb_setting_breakpoint; |
121 | ||
122 | struct task_struct *kgdb_usethread; | |
123 | struct task_struct *kgdb_contthread; | |
124 | ||
125 | int kgdb_single_step; | |
53197fc4 | 126 | static pid_t kgdb_sstep_pid; |
dc7d5527 JW |
127 | |
128 | /* to keep track of the CPU which is doing the single stepping*/ | |
129 | atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); | |
130 | ||
131 | /* | |
132 | * If you are debugging a problem where roundup (the collection of | |
133 | * all other CPUs) is a problem [this should be extremely rare], | |
134 | * then use the nokgdbroundup option to avoid roundup. In that case | |
135 | * the other CPUs might interfere with your debugging context, so | |
136 | * use this with care: | |
137 | */ | |
688b744d | 138 | static int kgdb_do_roundup = 1; |
dc7d5527 JW |
139 | |
140 | static int __init opt_nokgdbroundup(char *str) | |
141 | { | |
142 | kgdb_do_roundup = 0; | |
143 | ||
144 | return 0; | |
145 | } | |
146 | ||
147 | early_param("nokgdbroundup", opt_nokgdbroundup); | |
148 | ||
149 | /* | |
150 | * Finally, some KGDB code :-) | |
151 | */ | |
152 | ||
153 | /* | |
154 | * Weak aliases for breakpoint management, | |
155 | * can be overriden by architectures when needed: | |
156 | */ | |
dc7d5527 JW |
157 | int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr) |
158 | { | |
159 | int err; | |
160 | ||
161 | err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE); | |
162 | if (err) | |
163 | return err; | |
164 | ||
165 | return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr, | |
166 | BREAK_INSTR_SIZE); | |
167 | } | |
168 | ||
169 | int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle) | |
170 | { | |
171 | return probe_kernel_write((char *)addr, | |
172 | (char *)bundle, BREAK_INSTR_SIZE); | |
173 | } | |
174 | ||
a9b60bf4 JW |
175 | int __weak kgdb_validate_break_address(unsigned long addr) |
176 | { | |
177 | char tmp_variable[BREAK_INSTR_SIZE]; | |
178 | int err; | |
179 | /* Validate setting the breakpoint and then removing it. In the | |
180 | * remove fails, the kernel needs to emit a bad message because we | |
181 | * are deep trouble not being able to put things back the way we | |
182 | * found them. | |
183 | */ | |
184 | err = kgdb_arch_set_breakpoint(addr, tmp_variable); | |
185 | if (err) | |
186 | return err; | |
187 | err = kgdb_arch_remove_breakpoint(addr, tmp_variable); | |
188 | if (err) | |
189 | printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " | |
190 | "memory destroyed at: %lx", addr); | |
191 | return err; | |
192 | } | |
193 | ||
dc7d5527 JW |
194 | unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
195 | { | |
196 | return instruction_pointer(regs); | |
197 | } | |
198 | ||
199 | int __weak kgdb_arch_init(void) | |
200 | { | |
201 | return 0; | |
202 | } | |
203 | ||
b4b8ac52 JW |
204 | int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
205 | { | |
206 | return 0; | |
207 | } | |
208 | ||
dc7d5527 JW |
209 | /** |
210 | * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. | |
211 | * @regs: Current &struct pt_regs. | |
212 | * | |
213 | * This function will be called if the particular architecture must | |
214 | * disable hardware debugging while it is processing gdb packets or | |
215 | * handling exception. | |
216 | */ | |
217 | void __weak kgdb_disable_hw_debug(struct pt_regs *regs) | |
218 | { | |
219 | } | |
220 | ||
dc7d5527 JW |
221 | /* |
222 | * Some architectures need cache flushes when we set/clear a | |
223 | * breakpoint: | |
224 | */ | |
225 | static void kgdb_flush_swbreak_addr(unsigned long addr) | |
226 | { | |
227 | if (!CACHE_FLUSH_IS_SAFE) | |
228 | return; | |
229 | ||
737a460f | 230 | if (current->mm && current->mm->mmap_cache) { |
dc7d5527 JW |
231 | flush_cache_range(current->mm->mmap_cache, |
232 | addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 | 233 | } |
1a9a3e76 JW |
234 | /* Force flush instruction cache if it was outside the mm */ |
235 | flush_icache_range(addr, addr + BREAK_INSTR_SIZE); | |
dc7d5527 JW |
236 | } |
237 | ||
238 | /* | |
239 | * SW breakpoint management: | |
240 | */ | |
53197fc4 | 241 | int dbg_activate_sw_breakpoints(void) |
dc7d5527 JW |
242 | { |
243 | unsigned long addr; | |
7f8b7ed6 JW |
244 | int error; |
245 | int ret = 0; | |
dc7d5527 JW |
246 | int i; |
247 | ||
248 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
249 | if (kgdb_break[i].state != BP_SET) | |
250 | continue; | |
251 | ||
252 | addr = kgdb_break[i].bpt_addr; | |
253 | error = kgdb_arch_set_breakpoint(addr, | |
254 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
255 | if (error) { |
256 | ret = error; | |
257 | printk(KERN_INFO "KGDB: BP install failed: %lx", addr); | |
258 | continue; | |
259 | } | |
dc7d5527 JW |
260 | |
261 | kgdb_flush_swbreak_addr(addr); | |
262 | kgdb_break[i].state = BP_ACTIVE; | |
263 | } | |
7f8b7ed6 | 264 | return ret; |
dc7d5527 JW |
265 | } |
266 | ||
53197fc4 | 267 | int dbg_set_sw_break(unsigned long addr) |
dc7d5527 JW |
268 | { |
269 | int err = kgdb_validate_break_address(addr); | |
270 | int breakno = -1; | |
271 | int i; | |
272 | ||
273 | if (err) | |
274 | return err; | |
275 | ||
276 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
277 | if ((kgdb_break[i].state == BP_SET) && | |
278 | (kgdb_break[i].bpt_addr == addr)) | |
279 | return -EEXIST; | |
280 | } | |
281 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
282 | if (kgdb_break[i].state == BP_REMOVED && | |
283 | kgdb_break[i].bpt_addr == addr) { | |
284 | breakno = i; | |
285 | break; | |
286 | } | |
287 | } | |
288 | ||
289 | if (breakno == -1) { | |
290 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
291 | if (kgdb_break[i].state == BP_UNDEFINED) { | |
292 | breakno = i; | |
293 | break; | |
294 | } | |
295 | } | |
296 | } | |
297 | ||
298 | if (breakno == -1) | |
299 | return -E2BIG; | |
300 | ||
301 | kgdb_break[breakno].state = BP_SET; | |
302 | kgdb_break[breakno].type = BP_BREAKPOINT; | |
303 | kgdb_break[breakno].bpt_addr = addr; | |
304 | ||
305 | return 0; | |
306 | } | |
307 | ||
dcc78711 | 308 | int dbg_deactivate_sw_breakpoints(void) |
dc7d5527 JW |
309 | { |
310 | unsigned long addr; | |
7f8b7ed6 JW |
311 | int error; |
312 | int ret = 0; | |
dc7d5527 JW |
313 | int i; |
314 | ||
315 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
316 | if (kgdb_break[i].state != BP_ACTIVE) | |
317 | continue; | |
318 | addr = kgdb_break[i].bpt_addr; | |
319 | error = kgdb_arch_remove_breakpoint(addr, | |
320 | kgdb_break[i].saved_instr); | |
7f8b7ed6 JW |
321 | if (error) { |
322 | printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr); | |
323 | ret = error; | |
324 | } | |
dc7d5527 JW |
325 | |
326 | kgdb_flush_swbreak_addr(addr); | |
327 | kgdb_break[i].state = BP_SET; | |
328 | } | |
7f8b7ed6 | 329 | return ret; |
dc7d5527 JW |
330 | } |
331 | ||
53197fc4 | 332 | int dbg_remove_sw_break(unsigned long addr) |
dc7d5527 JW |
333 | { |
334 | int i; | |
335 | ||
336 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
337 | if ((kgdb_break[i].state == BP_SET) && | |
338 | (kgdb_break[i].bpt_addr == addr)) { | |
339 | kgdb_break[i].state = BP_REMOVED; | |
340 | return 0; | |
341 | } | |
342 | } | |
343 | return -ENOENT; | |
344 | } | |
345 | ||
346 | int kgdb_isremovedbreak(unsigned long addr) | |
347 | { | |
348 | int i; | |
349 | ||
350 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
351 | if ((kgdb_break[i].state == BP_REMOVED) && | |
352 | (kgdb_break[i].bpt_addr == addr)) | |
353 | return 1; | |
354 | } | |
355 | return 0; | |
356 | } | |
357 | ||
53197fc4 | 358 | int dbg_remove_all_break(void) |
dc7d5527 JW |
359 | { |
360 | unsigned long addr; | |
361 | int error; | |
362 | int i; | |
363 | ||
364 | /* Clear memory breakpoints. */ | |
365 | for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { | |
737a460f JW |
366 | if (kgdb_break[i].state != BP_ACTIVE) |
367 | goto setundefined; | |
dc7d5527 JW |
368 | addr = kgdb_break[i].bpt_addr; |
369 | error = kgdb_arch_remove_breakpoint(addr, | |
370 | kgdb_break[i].saved_instr); | |
371 | if (error) | |
737a460f JW |
372 | printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", |
373 | addr); | |
374 | setundefined: | |
375 | kgdb_break[i].state = BP_UNDEFINED; | |
dc7d5527 JW |
376 | } |
377 | ||
378 | /* Clear hardware breakpoints. */ | |
379 | if (arch_kgdb_ops.remove_all_hw_break) | |
380 | arch_kgdb_ops.remove_all_hw_break(); | |
381 | ||
382 | return 0; | |
383 | } | |
384 | ||
dc7d5527 JW |
385 | /* |
386 | * Return true if there is a valid kgdb I/O module. Also if no | |
387 | * debugger is attached a message can be printed to the console about | |
388 | * waiting for the debugger to attach. | |
389 | * | |
390 | * The print_wait argument is only to be true when called from inside | |
391 | * the core kgdb_handle_exception, because it will wait for the | |
392 | * debugger to attach. | |
393 | */ | |
394 | static int kgdb_io_ready(int print_wait) | |
395 | { | |
53197fc4 | 396 | if (!dbg_io_ops) |
dc7d5527 JW |
397 | return 0; |
398 | if (kgdb_connected) | |
399 | return 1; | |
400 | if (atomic_read(&kgdb_setting_breakpoint)) | |
401 | return 1; | |
dcc78711 JW |
402 | if (print_wait) { |
403 | #ifdef CONFIG_KGDB_KDB | |
404 | if (!dbg_kdb_mode) | |
405 | printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); | |
406 | #else | |
dc7d5527 | 407 | printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); |
dcc78711 JW |
408 | #endif |
409 | } | |
dc7d5527 JW |
410 | return 1; |
411 | } | |
412 | ||
dc7d5527 JW |
413 | static int kgdb_reenter_check(struct kgdb_state *ks) |
414 | { | |
415 | unsigned long addr; | |
416 | ||
417 | if (atomic_read(&kgdb_active) != raw_smp_processor_id()) | |
418 | return 0; | |
419 | ||
420 | /* Panic on recursive debugger calls: */ | |
421 | exception_level++; | |
422 | addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); | |
dcc78711 | 423 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 JW |
424 | |
425 | /* | |
426 | * If the break point removed ok at the place exception | |
427 | * occurred, try to recover and print a warning to the end | |
428 | * user because the user planted a breakpoint in a place that | |
429 | * KGDB needs in order to function. | |
430 | */ | |
53197fc4 | 431 | if (dbg_remove_sw_break(addr) == 0) { |
dc7d5527 JW |
432 | exception_level = 0; |
433 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); | |
53197fc4 | 434 | dbg_activate_sw_breakpoints(); |
67baf94c JW |
435 | printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", |
436 | addr); | |
dc7d5527 JW |
437 | WARN_ON_ONCE(1); |
438 | ||
439 | return 1; | |
440 | } | |
53197fc4 | 441 | dbg_remove_all_break(); |
dc7d5527 JW |
442 | kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
443 | ||
444 | if (exception_level > 1) { | |
445 | dump_stack(); | |
446 | panic("Recursive entry to debugger"); | |
447 | } | |
448 | ||
449 | printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); | |
6d906340 JW |
450 | #ifdef CONFIG_KGDB_KDB |
451 | /* Allow kdb to debug itself one level */ | |
452 | return 0; | |
453 | #endif | |
dc7d5527 JW |
454 | dump_stack(); |
455 | panic("Recursive entry to debugger"); | |
456 | ||
457 | return 1; | |
458 | } | |
459 | ||
dcc78711 JW |
460 | static void dbg_cpu_switch(int cpu, int next_cpu) |
461 | { | |
462 | /* Mark the cpu we are switching away from as a slave when it | |
463 | * holds the kgdb_active token. This must be done so that the | |
464 | * that all the cpus wait in for the debug core will not enter | |
465 | * again as the master. */ | |
466 | if (cpu == atomic_read(&kgdb_active)) { | |
467 | kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE; | |
468 | kgdb_info[cpu].exception_state &= ~DCPU_WANT_MASTER; | |
469 | } | |
470 | kgdb_info[next_cpu].exception_state |= DCPU_NEXT_MASTER; | |
471 | } | |
472 | ||
62fae312 | 473 | static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs) |
dc7d5527 | 474 | { |
dc7d5527 | 475 | unsigned long flags; |
028e7b17 | 476 | int sstep_tries = 100; |
dcc78711 | 477 | int error; |
dc7d5527 | 478 | int i, cpu; |
4da75b9c | 479 | int trace_on = 0; |
dc7d5527 JW |
480 | acquirelock: |
481 | /* | |
482 | * Interrupts will be restored by the 'trap return' code, except when | |
483 | * single stepping. | |
484 | */ | |
485 | local_irq_save(flags); | |
486 | ||
62fae312 JW |
487 | cpu = ks->cpu; |
488 | kgdb_info[cpu].debuggerinfo = regs; | |
489 | kgdb_info[cpu].task = current; | |
dcc78711 JW |
490 | kgdb_info[cpu].ret_state = 0; |
491 | kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; | |
62fae312 JW |
492 | /* |
493 | * Make sure the above info reaches the primary CPU before | |
494 | * our cpu_in_kgdb[] flag setting does: | |
495 | */ | |
ae6bf53e | 496 | atomic_inc(&cpu_in_kgdb[cpu]); |
dc7d5527 | 497 | |
6d906340 JW |
498 | if (exception_level == 1) |
499 | goto cpu_master_loop; | |
500 | ||
dc7d5527 | 501 | /* |
62fae312 JW |
502 | * CPU will loop if it is a slave or request to become a kgdb |
503 | * master cpu and acquire the kgdb_active lock: | |
dc7d5527 | 504 | */ |
62fae312 | 505 | while (1) { |
dcc78711 JW |
506 | cpu_loop: |
507 | if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { | |
508 | kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; | |
509 | goto cpu_master_loop; | |
510 | } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { | |
62fae312 JW |
511 | if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu) |
512 | break; | |
513 | } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { | |
514 | if (!atomic_read(&passive_cpu_wait[cpu])) | |
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(); | |
ae6bf53e | 525 | atomic_dec(&cpu_in_kgdb[cpu]); |
62fae312 JW |
526 | touch_softlockup_watchdog_sync(); |
527 | clocksource_touch_watchdog(); | |
528 | local_irq_restore(flags); | |
529 | return 0; | |
530 | } | |
dc7d5527 | 531 | cpu_relax(); |
62fae312 | 532 | } |
dc7d5527 JW |
533 | |
534 | /* | |
028e7b17 JW |
535 | * For single stepping, try to only enter on the processor |
536 | * that was single stepping. To gaurd against a deadlock, the | |
537 | * kernel will only try for the value of sstep_tries before | |
538 | * giving up and continuing on. | |
dc7d5527 JW |
539 | */ |
540 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && | |
028e7b17 JW |
541 | (kgdb_info[cpu].task && |
542 | kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { | |
dc7d5527 | 543 | atomic_set(&kgdb_active, -1); |
d6ad3e28 | 544 | touch_softlockup_watchdog_sync(); |
7c3078b6 | 545 | clocksource_touch_watchdog(); |
dc7d5527 JW |
546 | local_irq_restore(flags); |
547 | ||
548 | goto acquirelock; | |
549 | } | |
550 | ||
551 | if (!kgdb_io_ready(1)) { | |
dcc78711 | 552 | kgdb_info[cpu].ret_state = 1; |
53197fc4 | 553 | goto kgdb_restore; /* No I/O connection, resume the system */ |
dc7d5527 JW |
554 | } |
555 | ||
556 | /* | |
557 | * Don't enter if we have hit a removed breakpoint. | |
558 | */ | |
559 | if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) | |
560 | goto kgdb_restore; | |
561 | ||
562 | /* Call the I/O driver's pre_exception routine */ | |
53197fc4 JW |
563 | if (dbg_io_ops->pre_exception) |
564 | dbg_io_ops->pre_exception(); | |
dc7d5527 | 565 | |
dc7d5527 JW |
566 | kgdb_disable_hw_debug(ks->linux_regs); |
567 | ||
568 | /* | |
569 | * Get the passive CPU lock which will hold all the non-primary | |
570 | * CPU in a spin state while the debugger is active | |
571 | */ | |
d7161a65 | 572 | if (!kgdb_single_step) { |
dc7d5527 | 573 | for (i = 0; i < NR_CPUS; i++) |
ae6bf53e | 574 | atomic_inc(&passive_cpu_wait[i]); |
dc7d5527 JW |
575 | } |
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 | */ | |
586 | for_each_online_cpu(i) { | |
dcc78711 | 587 | while (kgdb_do_roundup && !atomic_read(&cpu_in_kgdb[i])) |
dc7d5527 JW |
588 | cpu_relax(); |
589 | } | |
590 | ||
591 | /* | |
592 | * At this point the primary processor is completely | |
593 | * in the debugger and all secondary CPUs are quiescent | |
594 | */ | |
dcc78711 | 595 | dbg_deactivate_sw_breakpoints(); |
dc7d5527 | 596 | kgdb_single_step = 0; |
d7161a65 | 597 | kgdb_contthread = current; |
dc7d5527 | 598 | exception_level = 0; |
4da75b9c JW |
599 | trace_on = tracing_is_on(); |
600 | if (trace_on) | |
601 | tracing_off(); | |
dc7d5527 | 602 | |
dcc78711 JW |
603 | while (1) { |
604 | cpu_master_loop: | |
605 | if (dbg_kdb_mode) { | |
606 | kgdb_connected = 1; | |
607 | error = kdb_stub(ks); | |
3fa43aba JW |
608 | if (error == -1) |
609 | continue; | |
b0679c63 | 610 | kgdb_connected = 0; |
dcc78711 JW |
611 | } else { |
612 | error = gdb_serial_stub(ks); | |
613 | } | |
614 | ||
615 | if (error == DBG_PASS_EVENT) { | |
616 | dbg_kdb_mode = !dbg_kdb_mode; | |
dcc78711 JW |
617 | } else if (error == DBG_SWITCH_CPU_EVENT) { |
618 | dbg_cpu_switch(cpu, dbg_switch_cpu); | |
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 | |
ae6bf53e | 630 | atomic_dec(&cpu_in_kgdb[ks->cpu]); |
dc7d5527 | 631 | |
d7161a65 | 632 | if (!kgdb_single_step) { |
dc7d5527 | 633 | for (i = NR_CPUS-1; i >= 0; i--) |
ae6bf53e | 634 | atomic_dec(&passive_cpu_wait[i]); |
dc7d5527 | 635 | /* |
dcc78711 JW |
636 | * Wait till all the CPUs have quit from the debugger, |
637 | * but allow a CPU that hit an exception and is | |
638 | * waiting to become the master to remain in the debug | |
639 | * core. | |
dc7d5527 JW |
640 | */ |
641 | for_each_online_cpu(i) { | |
dcc78711 JW |
642 | while (kgdb_do_roundup && |
643 | atomic_read(&cpu_in_kgdb[i]) && | |
644 | !(kgdb_info[i].exception_state & | |
645 | DCPU_WANT_MASTER)) | |
dc7d5527 JW |
646 | cpu_relax(); |
647 | } | |
648 | } | |
649 | ||
650 | kgdb_restore: | |
028e7b17 JW |
651 | if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
652 | int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); | |
653 | if (kgdb_info[sstep_cpu].task) | |
654 | kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; | |
655 | else | |
656 | kgdb_sstep_pid = 0; | |
657 | } | |
4da75b9c JW |
658 | if (trace_on) |
659 | tracing_on(); | |
dc7d5527 JW |
660 | /* Free kgdb_active */ |
661 | atomic_set(&kgdb_active, -1); | |
d6ad3e28 | 662 | touch_softlockup_watchdog_sync(); |
7c3078b6 | 663 | clocksource_touch_watchdog(); |
dc7d5527 JW |
664 | local_irq_restore(flags); |
665 | ||
dcc78711 | 666 | return kgdb_info[cpu].ret_state; |
dc7d5527 JW |
667 | } |
668 | ||
62fae312 JW |
669 | /* |
670 | * kgdb_handle_exception() - main entry point from a kernel exception | |
671 | * | |
672 | * Locking hierarchy: | |
673 | * interface locks, if any (begin_session) | |
674 | * kgdb lock (kgdb_active) | |
675 | */ | |
676 | int | |
677 | kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) | |
678 | { | |
679 | struct kgdb_state kgdb_var; | |
680 | struct kgdb_state *ks = &kgdb_var; | |
681 | int ret; | |
682 | ||
683 | ks->cpu = raw_smp_processor_id(); | |
684 | ks->ex_vector = evector; | |
685 | ks->signo = signo; | |
62fae312 JW |
686 | ks->err_code = ecode; |
687 | ks->kgdb_usethreadid = 0; | |
688 | ks->linux_regs = regs; | |
689 | ||
690 | if (kgdb_reenter_check(ks)) | |
691 | return 0; /* Ouch, double exception ! */ | |
692 | kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER; | |
693 | ret = kgdb_cpu_enter(ks, regs); | |
dcc78711 JW |
694 | kgdb_info[ks->cpu].exception_state &= ~(DCPU_WANT_MASTER | |
695 | DCPU_IS_SLAVE); | |
62fae312 JW |
696 | return ret; |
697 | } | |
698 | ||
dc7d5527 JW |
699 | int kgdb_nmicallback(int cpu, void *regs) |
700 | { | |
701 | #ifdef CONFIG_SMP | |
62fae312 JW |
702 | struct kgdb_state kgdb_var; |
703 | struct kgdb_state *ks = &kgdb_var; | |
704 | ||
705 | memset(ks, 0, sizeof(struct kgdb_state)); | |
706 | ks->cpu = cpu; | |
707 | ks->linux_regs = regs; | |
708 | ||
dc7d5527 | 709 | if (!atomic_read(&cpu_in_kgdb[cpu]) && |
62fae312 JW |
710 | atomic_read(&kgdb_active) != -1 && |
711 | atomic_read(&kgdb_active) != cpu) { | |
712 | kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE; | |
713 | kgdb_cpu_enter(ks, regs); | |
714 | kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE; | |
dc7d5527 JW |
715 | return 0; |
716 | } | |
717 | #endif | |
718 | return 1; | |
719 | } | |
720 | ||
aabdc3b8 JW |
721 | static void kgdb_console_write(struct console *co, const char *s, |
722 | unsigned count) | |
dc7d5527 JW |
723 | { |
724 | unsigned long flags; | |
725 | ||
726 | /* If we're debugging, or KGDB has not connected, don't try | |
727 | * and print. */ | |
dcc78711 | 728 | if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
dc7d5527 JW |
729 | return; |
730 | ||
731 | local_irq_save(flags); | |
53197fc4 | 732 | gdbstub_msg_write(s, count); |
dc7d5527 JW |
733 | local_irq_restore(flags); |
734 | } | |
735 | ||
736 | static struct console kgdbcons = { | |
737 | .name = "kgdb", | |
738 | .write = kgdb_console_write, | |
739 | .flags = CON_PRINTBUFFER | CON_ENABLED, | |
740 | .index = -1, | |
741 | }; | |
742 | ||
743 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 744 | static void sysrq_handle_dbg(int key, struct tty_struct *tty) |
dc7d5527 | 745 | { |
53197fc4 | 746 | if (!dbg_io_ops) { |
dc7d5527 JW |
747 | printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); |
748 | return; | |
749 | } | |
dcc78711 JW |
750 | if (!kgdb_connected) { |
751 | #ifdef CONFIG_KGDB_KDB | |
752 | if (!dbg_kdb_mode) | |
753 | printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); | |
754 | #else | |
dc7d5527 | 755 | printk(KERN_CRIT "Entering KGDB\n"); |
dcc78711 JW |
756 | #endif |
757 | } | |
dc7d5527 JW |
758 | |
759 | kgdb_breakpoint(); | |
760 | } | |
761 | ||
53197fc4 JW |
762 | static struct sysrq_key_op sysrq_dbg_op = { |
763 | .handler = sysrq_handle_dbg, | |
364b5b7b JW |
764 | .help_msg = "debug(G)", |
765 | .action_msg = "DEBUG", | |
dc7d5527 JW |
766 | }; |
767 | #endif | |
768 | ||
4402c153 JW |
769 | static int kgdb_panic_event(struct notifier_block *self, |
770 | unsigned long val, | |
771 | void *data) | |
772 | { | |
773 | if (dbg_kdb_mode) | |
774 | kdb_printf("PANIC: %s\n", (char *)data); | |
775 | kgdb_breakpoint(); | |
776 | return NOTIFY_DONE; | |
777 | } | |
778 | ||
779 | static struct notifier_block kgdb_panic_event_nb = { | |
780 | .notifier_call = kgdb_panic_event, | |
781 | .priority = INT_MAX, | |
782 | }; | |
783 | ||
0b4b3827 JW |
784 | void __weak kgdb_arch_late(void) |
785 | { | |
786 | } | |
787 | ||
788 | void __init dbg_late_init(void) | |
789 | { | |
790 | dbg_is_early = false; | |
791 | if (kgdb_io_module_registered) | |
792 | kgdb_arch_late(); | |
793 | kdb_init(KDB_INIT_FULL); | |
794 | } | |
795 | ||
dc7d5527 JW |
796 | static void kgdb_register_callbacks(void) |
797 | { | |
798 | if (!kgdb_io_module_registered) { | |
799 | kgdb_io_module_registered = 1; | |
800 | kgdb_arch_init(); | |
0b4b3827 JW |
801 | if (!dbg_is_early) |
802 | kgdb_arch_late(); | |
4402c153 JW |
803 | atomic_notifier_chain_register(&panic_notifier_list, |
804 | &kgdb_panic_event_nb); | |
dc7d5527 | 805 | #ifdef CONFIG_MAGIC_SYSRQ |
53197fc4 | 806 | register_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
807 | #endif |
808 | if (kgdb_use_con && !kgdb_con_registered) { | |
809 | register_console(&kgdbcons); | |
810 | kgdb_con_registered = 1; | |
811 | } | |
812 | } | |
813 | } | |
814 | ||
815 | static void kgdb_unregister_callbacks(void) | |
816 | { | |
817 | /* | |
818 | * When this routine is called KGDB should unregister from the | |
819 | * panic handler and clean up, making sure it is not handling any | |
820 | * break exceptions at the time. | |
821 | */ | |
822 | if (kgdb_io_module_registered) { | |
823 | kgdb_io_module_registered = 0; | |
4402c153 JW |
824 | atomic_notifier_chain_unregister(&panic_notifier_list, |
825 | &kgdb_panic_event_nb); | |
dc7d5527 JW |
826 | kgdb_arch_exit(); |
827 | #ifdef CONFIG_MAGIC_SYSRQ | |
53197fc4 | 828 | unregister_sysrq_key('g', &sysrq_dbg_op); |
dc7d5527 JW |
829 | #endif |
830 | if (kgdb_con_registered) { | |
831 | unregister_console(&kgdbcons); | |
832 | kgdb_con_registered = 0; | |
833 | } | |
834 | } | |
835 | } | |
836 | ||
1cee5e35 JW |
837 | /* |
838 | * There are times a tasklet needs to be used vs a compiled in | |
839 | * break point so as to cause an exception outside a kgdb I/O module, | |
840 | * such as is the case with kgdboe, where calling a breakpoint in the | |
841 | * I/O driver itself would be fatal. | |
842 | */ | |
843 | static void kgdb_tasklet_bpt(unsigned long ing) | |
844 | { | |
845 | kgdb_breakpoint(); | |
846 | atomic_set(&kgdb_break_tasklet_var, 0); | |
847 | } | |
848 | ||
849 | static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); | |
850 | ||
851 | void kgdb_schedule_breakpoint(void) | |
852 | { | |
853 | if (atomic_read(&kgdb_break_tasklet_var) || | |
854 | atomic_read(&kgdb_active) != -1 || | |
855 | atomic_read(&kgdb_setting_breakpoint)) | |
856 | return; | |
857 | atomic_inc(&kgdb_break_tasklet_var); | |
858 | tasklet_schedule(&kgdb_tasklet_breakpoint); | |
859 | } | |
860 | EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); | |
861 | ||
dc7d5527 JW |
862 | static void kgdb_initial_breakpoint(void) |
863 | { | |
864 | kgdb_break_asap = 0; | |
865 | ||
866 | printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); | |
867 | kgdb_breakpoint(); | |
868 | } | |
869 | ||
870 | /** | |
737a460f | 871 | * kgdb_register_io_module - register KGDB IO module |
53197fc4 | 872 | * @new_dbg_io_ops: the io ops vector |
dc7d5527 JW |
873 | * |
874 | * Register it with the KGDB core. | |
875 | */ | |
53197fc4 | 876 | int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
dc7d5527 JW |
877 | { |
878 | int err; | |
879 | ||
880 | spin_lock(&kgdb_registration_lock); | |
881 | ||
53197fc4 | 882 | if (dbg_io_ops) { |
dc7d5527 JW |
883 | spin_unlock(&kgdb_registration_lock); |
884 | ||
885 | printk(KERN_ERR "kgdb: Another I/O driver is already " | |
886 | "registered with KGDB.\n"); | |
887 | return -EBUSY; | |
888 | } | |
889 | ||
53197fc4 JW |
890 | if (new_dbg_io_ops->init) { |
891 | err = new_dbg_io_ops->init(); | |
dc7d5527 JW |
892 | if (err) { |
893 | spin_unlock(&kgdb_registration_lock); | |
894 | return err; | |
895 | } | |
896 | } | |
897 | ||
53197fc4 | 898 | dbg_io_ops = new_dbg_io_ops; |
dc7d5527 JW |
899 | |
900 | spin_unlock(&kgdb_registration_lock); | |
901 | ||
902 | printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", | |
53197fc4 | 903 | new_dbg_io_ops->name); |
dc7d5527 JW |
904 | |
905 | /* Arm KGDB now. */ | |
906 | kgdb_register_callbacks(); | |
907 | ||
908 | if (kgdb_break_asap) | |
909 | kgdb_initial_breakpoint(); | |
910 | ||
911 | return 0; | |
912 | } | |
913 | EXPORT_SYMBOL_GPL(kgdb_register_io_module); | |
914 | ||
915 | /** | |
916 | * kkgdb_unregister_io_module - unregister KGDB IO module | |
53197fc4 | 917 | * @old_dbg_io_ops: the io ops vector |
dc7d5527 JW |
918 | * |
919 | * Unregister it with the KGDB core. | |
920 | */ | |
53197fc4 | 921 | void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
dc7d5527 JW |
922 | { |
923 | BUG_ON(kgdb_connected); | |
924 | ||
925 | /* | |
926 | * KGDB is no longer able to communicate out, so | |
927 | * unregister our callbacks and reset state. | |
928 | */ | |
929 | kgdb_unregister_callbacks(); | |
930 | ||
931 | spin_lock(&kgdb_registration_lock); | |
932 | ||
53197fc4 JW |
933 | WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
934 | dbg_io_ops = NULL; | |
dc7d5527 JW |
935 | |
936 | spin_unlock(&kgdb_registration_lock); | |
937 | ||
938 | printk(KERN_INFO | |
939 | "kgdb: Unregistered I/O driver %s, debugger disabled.\n", | |
53197fc4 | 940 | old_dbg_io_ops->name); |
dc7d5527 JW |
941 | } |
942 | EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); | |
943 | ||
dcc78711 JW |
944 | int dbg_io_get_char(void) |
945 | { | |
946 | int ret = dbg_io_ops->read_char(); | |
f5316b4a JW |
947 | if (ret == NO_POLL_CHAR) |
948 | return -1; | |
dcc78711 JW |
949 | if (!dbg_kdb_mode) |
950 | return ret; | |
951 | if (ret == 127) | |
952 | return 8; | |
953 | return ret; | |
954 | } | |
955 | ||
dc7d5527 JW |
956 | /** |
957 | * kgdb_breakpoint - generate breakpoint exception | |
958 | * | |
959 | * This function will generate a breakpoint exception. It is used at the | |
960 | * beginning of a program to sync up with a debugger and can be used | |
961 | * otherwise as a quick means to stop program execution and "break" into | |
962 | * the debugger. | |
963 | */ | |
964 | void kgdb_breakpoint(void) | |
965 | { | |
ae6bf53e | 966 | atomic_inc(&kgdb_setting_breakpoint); |
dc7d5527 JW |
967 | wmb(); /* Sync point before breakpoint */ |
968 | arch_kgdb_breakpoint(); | |
969 | wmb(); /* Sync point after breakpoint */ | |
ae6bf53e | 970 | atomic_dec(&kgdb_setting_breakpoint); |
dc7d5527 JW |
971 | } |
972 | EXPORT_SYMBOL_GPL(kgdb_breakpoint); | |
973 | ||
974 | static int __init opt_kgdb_wait(char *str) | |
975 | { | |
976 | kgdb_break_asap = 1; | |
977 | ||
dcc78711 | 978 | kdb_init(KDB_INIT_EARLY); |
dc7d5527 JW |
979 | if (kgdb_io_module_registered) |
980 | kgdb_initial_breakpoint(); | |
981 | ||
982 | return 0; | |
983 | } | |
984 | ||
985 | early_param("kgdbwait", opt_kgdb_wait); |