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Jason Wesseldc7d5522008-04-17 20:05:37 +02001/*
Jason Wessel53197fc2010-04-02 11:48:03 -05002 * Kernel Debug Core
Jason Wesseldc7d5522008-04-17 20:05:37 +02003 *
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>
Pavel Macheka2531292010-07-18 14:27:13 +02009 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
Jason Wesseldc7d5522008-04-17 20:05:37 +020010 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
Jason Wessel53197fc2010-04-02 11:48:03 -050012 * Copyright (C) 2005-2009 Wind River Systems, Inc.
Jason Wesseldc7d5522008-04-17 20:05:37 +020013 * 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>
Jason Wessel7c3078b2008-02-15 14:55:54 -060031#include <linux/clocksource.h>
Greg Kroah-Hartman16559ae2013-02-04 15:35:26 -080032#include <linux/serial_core.h>
Jason Wesseldc7d5522008-04-17 20:05:37 +020033#include <linux/interrupt.h>
34#include <linux/spinlock.h>
35#include <linux/console.h>
36#include <linux/threads.h>
37#include <linux/uaccess.h>
38#include <linux/kernel.h>
39#include <linux/module.h>
40#include <linux/ptrace.h>
Jason Wesseldc7d5522008-04-17 20:05:37 +020041#include <linux/string.h>
42#include <linux/delay.h>
43#include <linux/sched.h>
44#include <linux/sysrq.h>
Jason Wessel2366e042012-03-16 14:20:41 -050045#include <linux/reboot.h>
Jason Wesseldc7d5522008-04-17 20:05:37 +020046#include <linux/init.h>
47#include <linux/kgdb.h>
Jason Wesseldcc78712010-05-20 21:04:21 -050048#include <linux/kdb.h>
Jason Wesseldc7d5522008-04-17 20:05:37 +020049#include <linux/pid.h>
50#include <linux/smp.h>
51#include <linux/mm.h>
Davidlohr Bueso615d6e82014-04-07 15:37:25 -070052#include <linux/vmacache.h>
Jason Wesselfb70b582010-08-13 12:44:04 -050053#include <linux/rcupdate.h>
Jason Wesseldc7d5522008-04-17 20:05:37 +020054
55#include <asm/cacheflush.h>
56#include <asm/byteorder.h>
Arun Sharma600634972011-07-26 16:09:06 -070057#include <linux/atomic.h>
Jason Wessel53197fc2010-04-02 11:48:03 -050058
59#include "debug_core.h"
Jason Wesseldc7d5522008-04-17 20:05:37 +020060
61static int kgdb_break_asap;
62
Jason Wessel53197fc2010-04-02 11:48:03 -050063struct debuggerinfo_struct kgdb_info[NR_CPUS];
Jason Wesseldc7d5522008-04-17 20:05:37 +020064
65/**
66 * kgdb_connected - Is a host GDB connected to us?
67 */
68int kgdb_connected;
69EXPORT_SYMBOL_GPL(kgdb_connected);
70
71/* All the KGDB handlers are installed */
Jason Wesself503b5a2010-05-20 21:04:25 -050072int kgdb_io_module_registered;
Jason Wesseldc7d5522008-04-17 20:05:37 +020073
74/* Guard for recursive entry */
75static int exception_level;
76
Jason Wessel53197fc2010-04-02 11:48:03 -050077struct kgdb_io *dbg_io_ops;
Jason Wesseldc7d5522008-04-17 20:05:37 +020078static DEFINE_SPINLOCK(kgdb_registration_lock);
79
Jason Wesselbec4d622012-03-19 19:35:55 -050080/* Action for the reboot notifiter, a global allow kdb to change it */
81static int kgdbreboot;
Jason Wesseldc7d5522008-04-17 20:05:37 +020082/* kgdb console driver is loaded */
83static int kgdb_con_registered;
84/* determine if kgdb console output should be used */
85static int kgdb_use_con;
Jason Wessel0b4b3822010-05-20 21:04:29 -050086/* Flag for alternate operations for early debugging */
87bool dbg_is_early = true;
Jason Wesseldcc78712010-05-20 21:04:21 -050088/* Next cpu to become the master debug core */
89int dbg_switch_cpu;
90
91/* Use kdb or gdbserver mode */
Jason Wessela0de0552010-05-20 21:04:24 -050092int dbg_kdb_mode = 1;
Jason Wesseldc7d5522008-04-17 20:05:37 +020093
94static int __init opt_kgdb_con(char *str)
95{
96 kgdb_use_con = 1;
97 return 0;
98}
99
100early_param("kgdbcon", opt_kgdb_con);
101
102module_param(kgdb_use_con, int, 0644);
Jason Wesselbec4d622012-03-19 19:35:55 -0500103module_param(kgdbreboot, int, 0644);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200104
105/*
106 * Holds information about breakpoints in a kernel. These breakpoints are
107 * added and removed by gdb.
108 */
109static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
110 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
111};
112
113/*
114 * The CPU# of the active CPU, or -1 if none:
115 */
116atomic_t kgdb_active = ATOMIC_INIT(-1);
Jason Wesseldcc78712010-05-20 21:04:21 -0500117EXPORT_SYMBOL_GPL(kgdb_active);
Jason Wesseldfee3a72010-05-21 08:46:00 -0500118static DEFINE_RAW_SPINLOCK(dbg_master_lock);
119static DEFINE_RAW_SPINLOCK(dbg_slave_lock);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200120
121/*
122 * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
123 * bootup code (which might not have percpu set up yet):
124 */
Jason Wesseldfee3a72010-05-21 08:46:00 -0500125static atomic_t masters_in_kgdb;
126static atomic_t slaves_in_kgdb;
Jason Wessel1cee5e32009-06-03 14:06:57 -0500127static atomic_t kgdb_break_tasklet_var;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200128atomic_t kgdb_setting_breakpoint;
129
130struct task_struct *kgdb_usethread;
131struct task_struct *kgdb_contthread;
132
133int kgdb_single_step;
Jason Wessel53197fc2010-04-02 11:48:03 -0500134static pid_t kgdb_sstep_pid;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200135
136/* to keep track of the CPU which is doing the single stepping*/
137atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
138
139/*
140 * If you are debugging a problem where roundup (the collection of
141 * all other CPUs) is a problem [this should be extremely rare],
142 * then use the nokgdbroundup option to avoid roundup. In that case
143 * the other CPUs might interfere with your debugging context, so
144 * use this with care:
145 */
Harvey Harrison688b7442008-04-24 16:57:23 -0500146static int kgdb_do_roundup = 1;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200147
148static int __init opt_nokgdbroundup(char *str)
149{
150 kgdb_do_roundup = 0;
151
152 return 0;
153}
154
155early_param("nokgdbroundup", opt_nokgdbroundup);
156
157/*
158 * Finally, some KGDB code :-)
159 */
160
161/*
162 * Weak aliases for breakpoint management,
163 * can be overriden by architectures when needed:
164 */
Jason Wessel98b54aa2012-03-21 10:17:03 -0500165int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200166{
167 int err;
168
Jason Wessel98b54aa2012-03-21 10:17:03 -0500169 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
170 BREAK_INSTR_SIZE);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200171 if (err)
172 return err;
Jason Wessel98b54aa2012-03-21 10:17:03 -0500173 err = probe_kernel_write((char *)bpt->bpt_addr,
174 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
175 return err;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200176}
177
Jason Wessel98b54aa2012-03-21 10:17:03 -0500178int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200179{
Jason Wessel98b54aa2012-03-21 10:17:03 -0500180 return probe_kernel_write((char *)bpt->bpt_addr,
181 (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200182}
183
Jason Wessela9b60bf2008-08-01 08:39:34 -0500184int __weak kgdb_validate_break_address(unsigned long addr)
185{
Jason Wessel98b54aa2012-03-21 10:17:03 -0500186 struct kgdb_bkpt tmp;
Jason Wessela9b60bf2008-08-01 08:39:34 -0500187 int err;
Jason Wessel98b54aa2012-03-21 10:17:03 -0500188 /* Validate setting the breakpoint and then removing it. If the
Jason Wessela9b60bf2008-08-01 08:39:34 -0500189 * remove fails, the kernel needs to emit a bad message because we
190 * are deep trouble not being able to put things back the way we
191 * found them.
192 */
Jason Wessel98b54aa2012-03-21 10:17:03 -0500193 tmp.bpt_addr = addr;
194 err = kgdb_arch_set_breakpoint(&tmp);
Jason Wessela9b60bf2008-08-01 08:39:34 -0500195 if (err)
196 return err;
Jason Wessel98b54aa2012-03-21 10:17:03 -0500197 err = kgdb_arch_remove_breakpoint(&tmp);
Jason Wessela9b60bf2008-08-01 08:39:34 -0500198 if (err)
199 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
200 "memory destroyed at: %lx", addr);
201 return err;
202}
203
Jason Wesseldc7d5522008-04-17 20:05:37 +0200204unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
205{
206 return instruction_pointer(regs);
207}
208
209int __weak kgdb_arch_init(void)
210{
211 return 0;
212}
213
Jason Wesselb4b8ac52008-02-20 13:33:38 -0600214int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
215{
216 return 0;
217}
218
Jason Wesseldc7d5522008-04-17 20:05:37 +0200219/*
Jason Wesseldc7d5522008-04-17 20:05:37 +0200220 * Some architectures need cache flushes when we set/clear a
221 * breakpoint:
222 */
223static void kgdb_flush_swbreak_addr(unsigned long addr)
224{
225 if (!CACHE_FLUSH_IS_SAFE)
226 return;
227
Davidlohr Bueso615d6e82014-04-07 15:37:25 -0700228 if (current->mm) {
229 int i;
230
231 for (i = 0; i < VMACACHE_SIZE; i++) {
232 if (!current->vmacache[i])
233 continue;
234 flush_cache_range(current->vmacache[i],
235 addr, addr + BREAK_INSTR_SIZE);
236 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200237 }
Davidlohr Bueso615d6e82014-04-07 15:37:25 -0700238
Jason Wessel1a9a3e72008-04-01 16:55:28 -0500239 /* Force flush instruction cache if it was outside the mm */
240 flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200241}
242
243/*
244 * SW breakpoint management:
245 */
Jason Wessel53197fc2010-04-02 11:48:03 -0500246int dbg_activate_sw_breakpoints(void)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200247{
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600248 int error;
249 int ret = 0;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200250 int i;
251
252 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
253 if (kgdb_break[i].state != BP_SET)
254 continue;
255
Jason Wessel98b54aa2012-03-21 10:17:03 -0500256 error = kgdb_arch_set_breakpoint(&kgdb_break[i]);
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600257 if (error) {
258 ret = error;
Jason Wessel98b54aa2012-03-21 10:17:03 -0500259 printk(KERN_INFO "KGDB: BP install failed: %lx",
260 kgdb_break[i].bpt_addr);
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600261 continue;
262 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200263
Jason Wessel98b54aa2012-03-21 10:17:03 -0500264 kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200265 kgdb_break[i].state = BP_ACTIVE;
266 }
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600267 return ret;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200268}
269
Jason Wessel53197fc2010-04-02 11:48:03 -0500270int dbg_set_sw_break(unsigned long addr)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200271{
272 int err = kgdb_validate_break_address(addr);
273 int breakno = -1;
274 int i;
275
276 if (err)
277 return err;
278
279 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
280 if ((kgdb_break[i].state == BP_SET) &&
281 (kgdb_break[i].bpt_addr == addr))
282 return -EEXIST;
283 }
284 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
285 if (kgdb_break[i].state == BP_REMOVED &&
286 kgdb_break[i].bpt_addr == addr) {
287 breakno = i;
288 break;
289 }
290 }
291
292 if (breakno == -1) {
293 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
294 if (kgdb_break[i].state == BP_UNDEFINED) {
295 breakno = i;
296 break;
297 }
298 }
299 }
300
301 if (breakno == -1)
302 return -E2BIG;
303
304 kgdb_break[breakno].state = BP_SET;
305 kgdb_break[breakno].type = BP_BREAKPOINT;
306 kgdb_break[breakno].bpt_addr = addr;
307
308 return 0;
309}
310
Jason Wesseldcc78712010-05-20 21:04:21 -0500311int dbg_deactivate_sw_breakpoints(void)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200312{
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600313 int error;
314 int ret = 0;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200315 int i;
316
317 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
318 if (kgdb_break[i].state != BP_ACTIVE)
319 continue;
Jason Wessel98b54aa2012-03-21 10:17:03 -0500320 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600321 if (error) {
Jason Wessel98b54aa2012-03-21 10:17:03 -0500322 printk(KERN_INFO "KGDB: BP remove failed: %lx\n",
323 kgdb_break[i].bpt_addr);
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600324 ret = error;
325 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200326
Jason Wessel98b54aa2012-03-21 10:17:03 -0500327 kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200328 kgdb_break[i].state = BP_SET;
329 }
Jason Wessel7f8b7ed62009-12-11 08:43:20 -0600330 return ret;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200331}
332
Jason Wessel53197fc2010-04-02 11:48:03 -0500333int dbg_remove_sw_break(unsigned long addr)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200334{
335 int i;
336
337 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
338 if ((kgdb_break[i].state == BP_SET) &&
339 (kgdb_break[i].bpt_addr == addr)) {
340 kgdb_break[i].state = BP_REMOVED;
341 return 0;
342 }
343 }
344 return -ENOENT;
345}
346
347int kgdb_isremovedbreak(unsigned long addr)
348{
349 int i;
350
351 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
352 if ((kgdb_break[i].state == BP_REMOVED) &&
353 (kgdb_break[i].bpt_addr == addr))
354 return 1;
355 }
356 return 0;
357}
358
Jason Wessel53197fc2010-04-02 11:48:03 -0500359int dbg_remove_all_break(void)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200360{
Jason Wesseldc7d5522008-04-17 20:05:37 +0200361 int error;
362 int i;
363
364 /* Clear memory breakpoints. */
365 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
Jason Wessel737a4602008-03-07 16:34:16 -0600366 if (kgdb_break[i].state != BP_ACTIVE)
367 goto setundefined;
Jason Wessel98b54aa2012-03-21 10:17:03 -0500368 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200369 if (error)
Jason Wessel737a4602008-03-07 16:34:16 -0600370 printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
Jason Wessel98b54aa2012-03-21 10:17:03 -0500371 kgdb_break[i].bpt_addr);
Jason Wessel737a4602008-03-07 16:34:16 -0600372setundefined:
373 kgdb_break[i].state = BP_UNDEFINED;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200374 }
375
376 /* Clear hardware breakpoints. */
377 if (arch_kgdb_ops.remove_all_hw_break)
378 arch_kgdb_ops.remove_all_hw_break();
379
380 return 0;
381}
382
383/*
Jason Wesseldc7d5522008-04-17 20:05:37 +0200384 * Return true if there is a valid kgdb I/O module. Also if no
385 * debugger is attached a message can be printed to the console about
386 * waiting for the debugger to attach.
387 *
388 * The print_wait argument is only to be true when called from inside
389 * the core kgdb_handle_exception, because it will wait for the
390 * debugger to attach.
391 */
392static int kgdb_io_ready(int print_wait)
393{
Jason Wessel53197fc2010-04-02 11:48:03 -0500394 if (!dbg_io_ops)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200395 return 0;
396 if (kgdb_connected)
397 return 1;
398 if (atomic_read(&kgdb_setting_breakpoint))
399 return 1;
Jason Wesseldcc78712010-05-20 21:04:21 -0500400 if (print_wait) {
401#ifdef CONFIG_KGDB_KDB
402 if (!dbg_kdb_mode)
403 printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
404#else
Jason Wesseldc7d5522008-04-17 20:05:37 +0200405 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
Jason Wesseldcc78712010-05-20 21:04:21 -0500406#endif
407 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200408 return 1;
409}
410
Jason Wesseldc7d5522008-04-17 20:05:37 +0200411static int kgdb_reenter_check(struct kgdb_state *ks)
412{
413 unsigned long addr;
414
415 if (atomic_read(&kgdb_active) != raw_smp_processor_id())
416 return 0;
417
418 /* Panic on recursive debugger calls: */
419 exception_level++;
420 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
Jason Wesseldcc78712010-05-20 21:04:21 -0500421 dbg_deactivate_sw_breakpoints();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200422
423 /*
424 * If the break point removed ok at the place exception
425 * occurred, try to recover and print a warning to the end
426 * user because the user planted a breakpoint in a place that
427 * KGDB needs in order to function.
428 */
Jason Wessel53197fc2010-04-02 11:48:03 -0500429 if (dbg_remove_sw_break(addr) == 0) {
Jason Wesseldc7d5522008-04-17 20:05:37 +0200430 exception_level = 0;
431 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
Jason Wessel53197fc2010-04-02 11:48:03 -0500432 dbg_activate_sw_breakpoints();
Jason Wessel67baf942008-02-15 14:55:55 -0600433 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
434 addr);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200435 WARN_ON_ONCE(1);
436
437 return 1;
438 }
Jason Wessel53197fc2010-04-02 11:48:03 -0500439 dbg_remove_all_break();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200440 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
441
442 if (exception_level > 1) {
443 dump_stack();
444 panic("Recursive entry to debugger");
445 }
446
447 printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
Jason Wessel6d906342010-05-20 21:04:27 -0500448#ifdef CONFIG_KGDB_KDB
449 /* Allow kdb to debug itself one level */
450 return 0;
451#endif
Jason Wesseldc7d5522008-04-17 20:05:37 +0200452 dump_stack();
453 panic("Recursive entry to debugger");
454
455 return 1;
456}
457
Jason Wessel16cdc622010-08-06 11:47:14 -0500458static void dbg_touch_watchdogs(void)
459{
460 touch_softlockup_watchdog_sync();
461 clocksource_touch_watchdog();
Jason Wesselfb70b582010-08-13 12:44:04 -0500462 rcu_cpu_stall_reset();
Jason Wessel16cdc622010-08-06 11:47:14 -0500463}
464
Jason Wesseldfee3a72010-05-21 08:46:00 -0500465static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
466 int exception_state)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200467{
Jason Wesseldc7d5522008-04-17 20:05:37 +0200468 unsigned long flags;
Jason Wessel028e7b12009-12-11 08:43:17 -0600469 int sstep_tries = 100;
Jason Wesseldcc78712010-05-20 21:04:21 -0500470 int error;
Jason Wesseldfee3a72010-05-21 08:46:00 -0500471 int cpu;
Jason Wessel4da75b92010-04-02 11:57:18 -0500472 int trace_on = 0;
Jason Wesseldfee3a72010-05-21 08:46:00 -0500473 int online_cpus = num_online_cpus();
Dongdong Dengc1bb9a92010-09-13 06:58:00 -0500474
Jason Wesseldfee3a72010-05-21 08:46:00 -0500475 kgdb_info[ks->cpu].enter_kgdb++;
476 kgdb_info[ks->cpu].exception_state |= exception_state;
477
478 if (exception_state == DCPU_WANT_MASTER)
479 atomic_inc(&masters_in_kgdb);
480 else
481 atomic_inc(&slaves_in_kgdb);
Dongdong Dengd7ba979d2010-08-18 06:02:00 -0500482
483 if (arch_kgdb_ops.disable_hw_break)
484 arch_kgdb_ops.disable_hw_break(regs);
Dongdong Dengc1bb9a92010-09-13 06:58:00 -0500485
Jason Wesseldc7d5522008-04-17 20:05:37 +0200486acquirelock:
487 /*
488 * Interrupts will be restored by the 'trap return' code, except when
489 * single stepping.
490 */
491 local_irq_save(flags);
492
Jason Wessel62fae312010-04-02 11:47:02 -0500493 cpu = ks->cpu;
494 kgdb_info[cpu].debuggerinfo = regs;
495 kgdb_info[cpu].task = current;
Jason Wesseldcc78712010-05-20 21:04:21 -0500496 kgdb_info[cpu].ret_state = 0;
497 kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200498
Jason Wesseldfee3a72010-05-21 08:46:00 -0500499 /* Make sure the above info reaches the primary CPU */
500 smp_mb();
501
502 if (exception_level == 1) {
503 if (raw_spin_trylock(&dbg_master_lock))
504 atomic_xchg(&kgdb_active, cpu);
Jason Wessel6d906342010-05-20 21:04:27 -0500505 goto cpu_master_loop;
Jason Wesseldfee3a72010-05-21 08:46:00 -0500506 }
Jason Wessel6d906342010-05-20 21:04:27 -0500507
Jason Wesseldc7d5522008-04-17 20:05:37 +0200508 /*
Jason Wessel62fae312010-04-02 11:47:02 -0500509 * CPU will loop if it is a slave or request to become a kgdb
510 * master cpu and acquire the kgdb_active lock:
Jason Wesseldc7d5522008-04-17 20:05:37 +0200511 */
Jason Wessel62fae312010-04-02 11:47:02 -0500512 while (1) {
Jason Wesseldcc78712010-05-20 21:04:21 -0500513cpu_loop:
514 if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) {
515 kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
516 goto cpu_master_loop;
517 } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
Jason Wesseldfee3a72010-05-21 08:46:00 -0500518 if (raw_spin_trylock(&dbg_master_lock)) {
519 atomic_xchg(&kgdb_active, cpu);
Jason Wessel62fae312010-04-02 11:47:02 -0500520 break;
Jason Wesseldfee3a72010-05-21 08:46:00 -0500521 }
Jason Wessel62fae312010-04-02 11:47:02 -0500522 } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
Jason Wesseldfee3a72010-05-21 08:46:00 -0500523 if (!raw_spin_is_locked(&dbg_slave_lock))
Jason Wessel62fae312010-04-02 11:47:02 -0500524 goto return_normal;
525 } else {
526return_normal:
527 /* Return to normal operation by executing any
528 * hw breakpoint fixup.
529 */
530 if (arch_kgdb_ops.correct_hw_break)
531 arch_kgdb_ops.correct_hw_break();
Jason Wessel4da75b92010-04-02 11:57:18 -0500532 if (trace_on)
533 tracing_on();
Jason Wesseldfee3a72010-05-21 08:46:00 -0500534 kgdb_info[cpu].exception_state &=
535 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
536 kgdb_info[cpu].enter_kgdb--;
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100537 smp_mb__before_atomic();
Jason Wesseldfee3a72010-05-21 08:46:00 -0500538 atomic_dec(&slaves_in_kgdb);
Jason Wessel16cdc622010-08-06 11:47:14 -0500539 dbg_touch_watchdogs();
Jason Wessel62fae312010-04-02 11:47:02 -0500540 local_irq_restore(flags);
541 return 0;
542 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200543 cpu_relax();
Jason Wessel62fae312010-04-02 11:47:02 -0500544 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200545
546 /*
Jason Wessel028e7b12009-12-11 08:43:17 -0600547 * For single stepping, try to only enter on the processor
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300548 * that was single stepping. To guard against a deadlock, the
Jason Wessel028e7b12009-12-11 08:43:17 -0600549 * kernel will only try for the value of sstep_tries before
550 * giving up and continuing on.
Jason Wesseldc7d5522008-04-17 20:05:37 +0200551 */
552 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
Jason Wessel028e7b12009-12-11 08:43:17 -0600553 (kgdb_info[cpu].task &&
554 kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
Jason Wesseldc7d5522008-04-17 20:05:37 +0200555 atomic_set(&kgdb_active, -1);
Jason Wesseldfee3a72010-05-21 08:46:00 -0500556 raw_spin_unlock(&dbg_master_lock);
Jason Wessel16cdc622010-08-06 11:47:14 -0500557 dbg_touch_watchdogs();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200558 local_irq_restore(flags);
559
560 goto acquirelock;
561 }
562
563 if (!kgdb_io_ready(1)) {
Jason Wesseldcc78712010-05-20 21:04:21 -0500564 kgdb_info[cpu].ret_state = 1;
Jason Wessel53197fc2010-04-02 11:48:03 -0500565 goto kgdb_restore; /* No I/O connection, resume the system */
Jason Wesseldc7d5522008-04-17 20:05:37 +0200566 }
567
568 /*
569 * Don't enter if we have hit a removed breakpoint.
570 */
571 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
572 goto kgdb_restore;
573
574 /* Call the I/O driver's pre_exception routine */
Jason Wessel53197fc2010-04-02 11:48:03 -0500575 if (dbg_io_ops->pre_exception)
576 dbg_io_ops->pre_exception();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200577
Jason Wesseldc7d5522008-04-17 20:05:37 +0200578 /*
579 * Get the passive CPU lock which will hold all the non-primary
580 * CPU in a spin state while the debugger is active
581 */
Jason Wesseldfee3a72010-05-21 08:46:00 -0500582 if (!kgdb_single_step)
583 raw_spin_lock(&dbg_slave_lock);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200584
Jason Wessel56fb7092008-04-01 16:55:27 -0500585#ifdef CONFIG_SMP
Mike Travis8daaa5f2013-10-02 10:14:18 -0500586 /* If send_ready set, slaves are already waiting */
587 if (ks->send_ready)
588 atomic_set(ks->send_ready, 1);
589
Jason Wessel56fb7092008-04-01 16:55:27 -0500590 /* Signal the other CPUs to enter kgdb_wait() */
Mike Travis8daaa5f2013-10-02 10:14:18 -0500591 else if ((!kgdb_single_step) && kgdb_do_roundup)
Jason Wessel56fb7092008-04-01 16:55:27 -0500592 kgdb_roundup_cpus(flags);
593#endif
594
Jason Wesseldc7d5522008-04-17 20:05:37 +0200595 /*
596 * Wait for the other CPUs to be notified and be waiting for us:
597 */
Jason Wesseldfee3a72010-05-21 08:46:00 -0500598 while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
599 atomic_read(&slaves_in_kgdb)) != online_cpus)
600 cpu_relax();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200601
602 /*
603 * At this point the primary processor is completely
604 * in the debugger and all secondary CPUs are quiescent
605 */
Jason Wesseldcc78712010-05-20 21:04:21 -0500606 dbg_deactivate_sw_breakpoints();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200607 kgdb_single_step = 0;
Jason Wesseld7161a62008-09-26 10:36:41 -0500608 kgdb_contthread = current;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200609 exception_level = 0;
Jason Wessel4da75b92010-04-02 11:57:18 -0500610 trace_on = tracing_is_on();
611 if (trace_on)
612 tracing_off();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200613
Jason Wesseldcc78712010-05-20 21:04:21 -0500614 while (1) {
615cpu_master_loop:
616 if (dbg_kdb_mode) {
617 kgdb_connected = 1;
618 error = kdb_stub(ks);
Jason Wessel3fa43ab2010-08-05 09:22:25 -0500619 if (error == -1)
620 continue;
Jason Wesselb0679c62010-07-21 19:27:07 -0500621 kgdb_connected = 0;
Jason Wesseldcc78712010-05-20 21:04:21 -0500622 } else {
623 error = gdb_serial_stub(ks);
624 }
625
626 if (error == DBG_PASS_EVENT) {
627 dbg_kdb_mode = !dbg_kdb_mode;
Jason Wesseldcc78712010-05-20 21:04:21 -0500628 } else if (error == DBG_SWITCH_CPU_EVENT) {
Jason Wessel495363d2010-05-21 08:46:00 -0500629 kgdb_info[dbg_switch_cpu].exception_state |=
630 DCPU_NEXT_MASTER;
Jason Wesseldcc78712010-05-20 21:04:21 -0500631 goto cpu_loop;
632 } else {
633 kgdb_info[cpu].ret_state = error;
634 break;
635 }
636 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200637
638 /* Call the I/O driver's post_exception routine */
Jason Wessel53197fc2010-04-02 11:48:03 -0500639 if (dbg_io_ops->post_exception)
640 dbg_io_ops->post_exception();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200641
Jason Wesseld7161a62008-09-26 10:36:41 -0500642 if (!kgdb_single_step) {
Jason Wesseldfee3a72010-05-21 08:46:00 -0500643 raw_spin_unlock(&dbg_slave_lock);
644 /* Wait till all the CPUs have quit from the debugger. */
645 while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb))
646 cpu_relax();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200647 }
648
649kgdb_restore:
Jason Wessel028e7b12009-12-11 08:43:17 -0600650 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
651 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
652 if (kgdb_info[sstep_cpu].task)
653 kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
654 else
655 kgdb_sstep_pid = 0;
656 }
Dongdong Dengc1bb9a92010-09-13 06:58:00 -0500657 if (arch_kgdb_ops.correct_hw_break)
658 arch_kgdb_ops.correct_hw_break();
Jason Wessel4da75b92010-04-02 11:57:18 -0500659 if (trace_on)
660 tracing_on();
Jason Wesseldfee3a72010-05-21 08:46:00 -0500661
662 kgdb_info[cpu].exception_state &=
663 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
664 kgdb_info[cpu].enter_kgdb--;
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100665 smp_mb__before_atomic();
Jason Wesseldfee3a72010-05-21 08:46:00 -0500666 atomic_dec(&masters_in_kgdb);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200667 /* Free kgdb_active */
668 atomic_set(&kgdb_active, -1);
Jason Wesseldfee3a72010-05-21 08:46:00 -0500669 raw_spin_unlock(&dbg_master_lock);
Jason Wessel16cdc622010-08-06 11:47:14 -0500670 dbg_touch_watchdogs();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200671 local_irq_restore(flags);
672
Jason Wesseldcc78712010-05-20 21:04:21 -0500673 return kgdb_info[cpu].ret_state;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200674}
675
Jason Wessel62fae312010-04-02 11:47:02 -0500676/*
677 * kgdb_handle_exception() - main entry point from a kernel exception
678 *
679 * Locking hierarchy:
680 * interface locks, if any (begin_session)
681 * kgdb lock (kgdb_active)
682 */
683int
684kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
685{
686 struct kgdb_state kgdb_var;
687 struct kgdb_state *ks = &kgdb_var;
Anton Vorontsov5a14fea2012-09-24 14:27:50 -0700688 int ret = 0;
689
690 if (arch_kgdb_ops.enable_nmi)
691 arch_kgdb_ops.enable_nmi(0);
Jason Wessel62fae312010-04-02 11:47:02 -0500692
Mike Travis8daaa5f2013-10-02 10:14:18 -0500693 memset(ks, 0, sizeof(struct kgdb_state));
Jason Wessel62fae312010-04-02 11:47:02 -0500694 ks->cpu = raw_smp_processor_id();
695 ks->ex_vector = evector;
696 ks->signo = signo;
Jason Wessel62fae312010-04-02 11:47:02 -0500697 ks->err_code = ecode;
Jason Wessel62fae312010-04-02 11:47:02 -0500698 ks->linux_regs = regs;
699
700 if (kgdb_reenter_check(ks))
Anton Vorontsov5a14fea2012-09-24 14:27:50 -0700701 goto out; /* Ouch, double exception ! */
Jason Wesseldfee3a72010-05-21 08:46:00 -0500702 if (kgdb_info[ks->cpu].enter_kgdb != 0)
Anton Vorontsov5a14fea2012-09-24 14:27:50 -0700703 goto out;
Jason Wesseldfee3a72010-05-21 08:46:00 -0500704
Anton Vorontsov5a14fea2012-09-24 14:27:50 -0700705 ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
706out:
707 if (arch_kgdb_ops.enable_nmi)
708 arch_kgdb_ops.enable_nmi(1);
709 return ret;
Jason Wessel62fae312010-04-02 11:47:02 -0500710}
711
Jason Wesself30fed12012-10-12 06:37:33 -0500712/*
713 * GDB places a breakpoint at this function to know dynamically
714 * loaded objects. It's not defined static so that only one instance with this
715 * name exists in the kernel.
716 */
717
718static int module_event(struct notifier_block *self, unsigned long val,
719 void *data)
720{
721 return 0;
722}
723
724static struct notifier_block dbg_module_load_nb = {
725 .notifier_call = module_event,
726};
727
Jason Wesseldc7d5522008-04-17 20:05:37 +0200728int kgdb_nmicallback(int cpu, void *regs)
729{
730#ifdef CONFIG_SMP
Jason Wessel62fae312010-04-02 11:47:02 -0500731 struct kgdb_state kgdb_var;
732 struct kgdb_state *ks = &kgdb_var;
733
734 memset(ks, 0, sizeof(struct kgdb_state));
735 ks->cpu = cpu;
736 ks->linux_regs = regs;
737
Jason Wesseldfee3a72010-05-21 08:46:00 -0500738 if (kgdb_info[ks->cpu].enter_kgdb == 0 &&
739 raw_spin_is_locked(&dbg_master_lock)) {
740 kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200741 return 0;
742 }
743#endif
744 return 1;
745}
746
Mike Travisfc8b1372014-01-14 10:25:52 -0600747int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code,
748 atomic_t *send_ready)
Mike Travis8daaa5f2013-10-02 10:14:18 -0500749{
750#ifdef CONFIG_SMP
751 if (!kgdb_io_ready(0) || !send_ready)
752 return 1;
753
754 if (kgdb_info[cpu].enter_kgdb == 0) {
755 struct kgdb_state kgdb_var;
756 struct kgdb_state *ks = &kgdb_var;
757
758 memset(ks, 0, sizeof(struct kgdb_state));
759 ks->cpu = cpu;
760 ks->ex_vector = trapnr;
761 ks->signo = SIGTRAP;
Mike Travisfc8b1372014-01-14 10:25:52 -0600762 ks->err_code = err_code;
Mike Travis8daaa5f2013-10-02 10:14:18 -0500763 ks->linux_regs = regs;
764 ks->send_ready = send_ready;
765 kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
766 return 0;
767 }
768#endif
769 return 1;
770}
771
Jason Wesselaabdc3b2008-06-24 10:52:55 -0500772static void kgdb_console_write(struct console *co, const char *s,
773 unsigned count)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200774{
775 unsigned long flags;
776
777 /* If we're debugging, or KGDB has not connected, don't try
778 * and print. */
Jason Wesseldcc78712010-05-20 21:04:21 -0500779 if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200780 return;
781
782 local_irq_save(flags);
Jason Wessel53197fc2010-04-02 11:48:03 -0500783 gdbstub_msg_write(s, count);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200784 local_irq_restore(flags);
785}
786
787static struct console kgdbcons = {
788 .name = "kgdb",
789 .write = kgdb_console_write,
790 .flags = CON_PRINTBUFFER | CON_ENABLED,
791 .index = -1,
792};
793
794#ifdef CONFIG_MAGIC_SYSRQ
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700795static void sysrq_handle_dbg(int key)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200796{
Jason Wessel53197fc2010-04-02 11:48:03 -0500797 if (!dbg_io_ops) {
Jason Wesseldc7d5522008-04-17 20:05:37 +0200798 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
799 return;
800 }
Jason Wesseldcc78712010-05-20 21:04:21 -0500801 if (!kgdb_connected) {
802#ifdef CONFIG_KGDB_KDB
803 if (!dbg_kdb_mode)
804 printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
805#else
Jason Wesseldc7d5522008-04-17 20:05:37 +0200806 printk(KERN_CRIT "Entering KGDB\n");
Jason Wesseldcc78712010-05-20 21:04:21 -0500807#endif
808 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200809
810 kgdb_breakpoint();
811}
812
Jason Wessel53197fc2010-04-02 11:48:03 -0500813static struct sysrq_key_op sysrq_dbg_op = {
814 .handler = sysrq_handle_dbg,
zhangwei(Jovi)f3456502013-04-30 15:28:51 -0700815 .help_msg = "debug(g)",
Jason Wessel364b5b72009-05-13 21:56:59 -0500816 .action_msg = "DEBUG",
Jason Wesseldc7d5522008-04-17 20:05:37 +0200817};
818#endif
819
Jason Wessel4402c152010-05-20 21:04:28 -0500820static int kgdb_panic_event(struct notifier_block *self,
821 unsigned long val,
822 void *data)
823{
824 if (dbg_kdb_mode)
825 kdb_printf("PANIC: %s\n", (char *)data);
826 kgdb_breakpoint();
827 return NOTIFY_DONE;
828}
829
830static struct notifier_block kgdb_panic_event_nb = {
831 .notifier_call = kgdb_panic_event,
832 .priority = INT_MAX,
833};
834
Jason Wessel0b4b3822010-05-20 21:04:29 -0500835void __weak kgdb_arch_late(void)
836{
837}
838
839void __init dbg_late_init(void)
840{
841 dbg_is_early = false;
842 if (kgdb_io_module_registered)
843 kgdb_arch_late();
844 kdb_init(KDB_INIT_FULL);
845}
846
Jason Wessel2366e042012-03-16 14:20:41 -0500847static int
848dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x)
849{
Jason Wesselbec4d622012-03-19 19:35:55 -0500850 /*
851 * Take the following action on reboot notify depending on value:
852 * 1 == Enter debugger
853 * 0 == [the default] detatch debug client
854 * -1 == Do nothing... and use this until the board resets
855 */
856 switch (kgdbreboot) {
857 case 1:
858 kgdb_breakpoint();
859 case -1:
860 goto done;
861 }
Jason Wessel2366e042012-03-16 14:20:41 -0500862 if (!dbg_kdb_mode)
863 gdbstub_exit(code);
Jason Wesselbec4d622012-03-19 19:35:55 -0500864done:
Jason Wessel2366e042012-03-16 14:20:41 -0500865 return NOTIFY_DONE;
866}
867
868static struct notifier_block dbg_reboot_notifier = {
869 .notifier_call = dbg_notify_reboot,
870 .next = NULL,
871 .priority = INT_MAX,
872};
873
Jason Wesseldc7d5522008-04-17 20:05:37 +0200874static void kgdb_register_callbacks(void)
875{
876 if (!kgdb_io_module_registered) {
877 kgdb_io_module_registered = 1;
878 kgdb_arch_init();
Jason Wessel0b4b3822010-05-20 21:04:29 -0500879 if (!dbg_is_early)
880 kgdb_arch_late();
Jason Wesself30fed12012-10-12 06:37:33 -0500881 register_module_notifier(&dbg_module_load_nb);
Jason Wessel2366e042012-03-16 14:20:41 -0500882 register_reboot_notifier(&dbg_reboot_notifier);
Jason Wessel4402c152010-05-20 21:04:28 -0500883 atomic_notifier_chain_register(&panic_notifier_list,
884 &kgdb_panic_event_nb);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200885#ifdef CONFIG_MAGIC_SYSRQ
Jason Wessel53197fc2010-04-02 11:48:03 -0500886 register_sysrq_key('g', &sysrq_dbg_op);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200887#endif
888 if (kgdb_use_con && !kgdb_con_registered) {
889 register_console(&kgdbcons);
890 kgdb_con_registered = 1;
891 }
892 }
893}
894
895static void kgdb_unregister_callbacks(void)
896{
897 /*
898 * When this routine is called KGDB should unregister from the
899 * panic handler and clean up, making sure it is not handling any
900 * break exceptions at the time.
901 */
902 if (kgdb_io_module_registered) {
903 kgdb_io_module_registered = 0;
Jason Wessel2366e042012-03-16 14:20:41 -0500904 unregister_reboot_notifier(&dbg_reboot_notifier);
Jason Wesself30fed12012-10-12 06:37:33 -0500905 unregister_module_notifier(&dbg_module_load_nb);
Jason Wessel4402c152010-05-20 21:04:28 -0500906 atomic_notifier_chain_unregister(&panic_notifier_list,
907 &kgdb_panic_event_nb);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200908 kgdb_arch_exit();
909#ifdef CONFIG_MAGIC_SYSRQ
Jason Wessel53197fc2010-04-02 11:48:03 -0500910 unregister_sysrq_key('g', &sysrq_dbg_op);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200911#endif
912 if (kgdb_con_registered) {
913 unregister_console(&kgdbcons);
914 kgdb_con_registered = 0;
915 }
916 }
917}
918
Jason Wessel1cee5e32009-06-03 14:06:57 -0500919/*
920 * There are times a tasklet needs to be used vs a compiled in
921 * break point so as to cause an exception outside a kgdb I/O module,
922 * such as is the case with kgdboe, where calling a breakpoint in the
923 * I/O driver itself would be fatal.
924 */
925static void kgdb_tasklet_bpt(unsigned long ing)
926{
927 kgdb_breakpoint();
928 atomic_set(&kgdb_break_tasklet_var, 0);
929}
930
931static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0);
932
933void kgdb_schedule_breakpoint(void)
934{
935 if (atomic_read(&kgdb_break_tasklet_var) ||
936 atomic_read(&kgdb_active) != -1 ||
937 atomic_read(&kgdb_setting_breakpoint))
938 return;
939 atomic_inc(&kgdb_break_tasklet_var);
940 tasklet_schedule(&kgdb_tasklet_breakpoint);
941}
942EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint);
943
Jason Wesseldc7d5522008-04-17 20:05:37 +0200944static void kgdb_initial_breakpoint(void)
945{
946 kgdb_break_asap = 0;
947
948 printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
949 kgdb_breakpoint();
950}
951
952/**
Jason Wessel737a4602008-03-07 16:34:16 -0600953 * kgdb_register_io_module - register KGDB IO module
Jason Wessel53197fc2010-04-02 11:48:03 -0500954 * @new_dbg_io_ops: the io ops vector
Jason Wesseldc7d5522008-04-17 20:05:37 +0200955 *
956 * Register it with the KGDB core.
957 */
Jason Wessel53197fc2010-04-02 11:48:03 -0500958int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200959{
960 int err;
961
962 spin_lock(&kgdb_registration_lock);
963
Jason Wessel53197fc2010-04-02 11:48:03 -0500964 if (dbg_io_ops) {
Jason Wesseldc7d5522008-04-17 20:05:37 +0200965 spin_unlock(&kgdb_registration_lock);
966
967 printk(KERN_ERR "kgdb: Another I/O driver is already "
968 "registered with KGDB.\n");
969 return -EBUSY;
970 }
971
Jason Wessel53197fc2010-04-02 11:48:03 -0500972 if (new_dbg_io_ops->init) {
973 err = new_dbg_io_ops->init();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200974 if (err) {
975 spin_unlock(&kgdb_registration_lock);
976 return err;
977 }
978 }
979
Jason Wessel53197fc2010-04-02 11:48:03 -0500980 dbg_io_ops = new_dbg_io_ops;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200981
982 spin_unlock(&kgdb_registration_lock);
983
984 printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
Jason Wessel53197fc2010-04-02 11:48:03 -0500985 new_dbg_io_ops->name);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200986
987 /* Arm KGDB now. */
988 kgdb_register_callbacks();
989
990 if (kgdb_break_asap)
991 kgdb_initial_breakpoint();
992
993 return 0;
994}
995EXPORT_SYMBOL_GPL(kgdb_register_io_module);
996
997/**
998 * kkgdb_unregister_io_module - unregister KGDB IO module
Jason Wessel53197fc2010-04-02 11:48:03 -0500999 * @old_dbg_io_ops: the io ops vector
Jason Wesseldc7d5522008-04-17 20:05:37 +02001000 *
1001 * Unregister it with the KGDB core.
1002 */
Jason Wessel53197fc2010-04-02 11:48:03 -05001003void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
Jason Wesseldc7d5522008-04-17 20:05:37 +02001004{
1005 BUG_ON(kgdb_connected);
1006
1007 /*
1008 * KGDB is no longer able to communicate out, so
1009 * unregister our callbacks and reset state.
1010 */
1011 kgdb_unregister_callbacks();
1012
1013 spin_lock(&kgdb_registration_lock);
1014
Jason Wessel53197fc2010-04-02 11:48:03 -05001015 WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops);
1016 dbg_io_ops = NULL;
Jason Wesseldc7d5522008-04-17 20:05:37 +02001017
1018 spin_unlock(&kgdb_registration_lock);
1019
1020 printk(KERN_INFO
1021 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
Jason Wessel53197fc2010-04-02 11:48:03 -05001022 old_dbg_io_ops->name);
Jason Wesseldc7d5522008-04-17 20:05:37 +02001023}
1024EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1025
Jason Wesseldcc78712010-05-20 21:04:21 -05001026int dbg_io_get_char(void)
1027{
1028 int ret = dbg_io_ops->read_char();
Jason Wesself5316b42010-05-20 21:04:22 -05001029 if (ret == NO_POLL_CHAR)
1030 return -1;
Jason Wesseldcc78712010-05-20 21:04:21 -05001031 if (!dbg_kdb_mode)
1032 return ret;
1033 if (ret == 127)
1034 return 8;
1035 return ret;
1036}
1037
Jason Wesseldc7d5522008-04-17 20:05:37 +02001038/**
1039 * kgdb_breakpoint - generate breakpoint exception
1040 *
1041 * This function will generate a breakpoint exception. It is used at the
1042 * beginning of a program to sync up with a debugger and can be used
1043 * otherwise as a quick means to stop program execution and "break" into
1044 * the debugger.
1045 */
Vijaya Kumar Kd498d4b2014-01-28 16:50:20 +05301046noinline void kgdb_breakpoint(void)
Jason Wesseldc7d5522008-04-17 20:05:37 +02001047{
Jason Wesselae6bf532010-04-02 14:58:18 -05001048 atomic_inc(&kgdb_setting_breakpoint);
Jason Wesseldc7d5522008-04-17 20:05:37 +02001049 wmb(); /* Sync point before breakpoint */
1050 arch_kgdb_breakpoint();
1051 wmb(); /* Sync point after breakpoint */
Jason Wesselae6bf532010-04-02 14:58:18 -05001052 atomic_dec(&kgdb_setting_breakpoint);
Jason Wesseldc7d5522008-04-17 20:05:37 +02001053}
1054EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1055
1056static int __init opt_kgdb_wait(char *str)
1057{
1058 kgdb_break_asap = 1;
1059
Jason Wesseldcc78712010-05-20 21:04:21 -05001060 kdb_init(KDB_INIT_EARLY);
Jason Wesseldc7d5522008-04-17 20:05:37 +02001061 if (kgdb_io_module_registered)
1062 kgdb_initial_breakpoint();
1063
1064 return 0;
1065}
1066
1067early_param("kgdbwait", opt_kgdb_wait);