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Jason Wesseldc7d5522008-04-17 20:05:37 +02001/*
2 * KGDB stub.
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.
12 * Copyright (C) 2005-2008 Wind River Systems, Inc.
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>
Jason Wessel7c3078b2008-02-15 14:55:54 -060031#include <linux/clocksource.h>
Jason Wesseldc7d5522008-04-17 20:05:37 +020032#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>
40#include <linux/reboot.h>
41#include <linux/string.h>
42#include <linux/delay.h>
43#include <linux/sched.h>
44#include <linux/sysrq.h>
45#include <linux/init.h>
46#include <linux/kgdb.h>
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>
Harvey Harrison827e6092008-05-28 12:49:56 -050055#include <asm/unaligned.h>
Jason Wesseldc7d5522008-04-17 20:05:37 +020056
57static int kgdb_break_asap;
58
Jason Wessel25fc9992008-08-01 08:39:35 -050059#define KGDB_MAX_THREAD_QUERY 17
Jason Wesseldc7d5522008-04-17 20:05:37 +020060struct kgdb_state {
61 int ex_vector;
62 int signo;
63 int err_code;
64 int cpu;
65 int pass_exception;
Jason Wessel25fc9992008-08-01 08:39:35 -050066 unsigned long thr_query;
Harvey Harrison688b7442008-04-24 16:57:23 -050067 unsigned long threadid;
Jason Wesseldc7d5522008-04-17 20:05:37 +020068 long kgdb_usethreadid;
69 struct pt_regs *linux_regs;
70};
71
72static struct debuggerinfo_struct {
73 void *debuggerinfo;
74 struct task_struct *task;
75} kgdb_info[NR_CPUS];
76
77/**
78 * kgdb_connected - Is a host GDB connected to us?
79 */
80int kgdb_connected;
81EXPORT_SYMBOL_GPL(kgdb_connected);
82
83/* All the KGDB handlers are installed */
84static int kgdb_io_module_registered;
85
86/* Guard for recursive entry */
87static int exception_level;
88
89static struct kgdb_io *kgdb_io_ops;
90static DEFINE_SPINLOCK(kgdb_registration_lock);
91
92/* kgdb console driver is loaded */
93static int kgdb_con_registered;
94/* determine if kgdb console output should be used */
95static int kgdb_use_con;
96
97static int __init opt_kgdb_con(char *str)
98{
99 kgdb_use_con = 1;
100 return 0;
101}
102
103early_param("kgdbcon", opt_kgdb_con);
104
105module_param(kgdb_use_con, int, 0644);
106
107/*
108 * Holds information about breakpoints in a kernel. These breakpoints are
109 * added and removed by gdb.
110 */
111static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
112 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
113};
114
115/*
116 * The CPU# of the active CPU, or -1 if none:
117 */
118atomic_t kgdb_active = ATOMIC_INIT(-1);
119
120/*
121 * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
122 * bootup code (which might not have percpu set up yet):
123 */
124static atomic_t passive_cpu_wait[NR_CPUS];
125static atomic_t cpu_in_kgdb[NR_CPUS];
126atomic_t kgdb_setting_breakpoint;
127
128struct task_struct *kgdb_usethread;
129struct task_struct *kgdb_contthread;
130
131int kgdb_single_step;
132
133/* Our I/O buffers. */
134static char remcom_in_buffer[BUFMAX];
135static char remcom_out_buffer[BUFMAX];
136
137/* Storage for the registers, in GDB format. */
138static unsigned long gdb_regs[(NUMREGBYTES +
139 sizeof(unsigned long) - 1) /
140 sizeof(unsigned long)];
141
142/* to keep track of the CPU which is doing the single stepping*/
143atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
144
145/*
146 * If you are debugging a problem where roundup (the collection of
147 * all other CPUs) is a problem [this should be extremely rare],
148 * then use the nokgdbroundup option to avoid roundup. In that case
149 * the other CPUs might interfere with your debugging context, so
150 * use this with care:
151 */
Harvey Harrison688b7442008-04-24 16:57:23 -0500152static int kgdb_do_roundup = 1;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200153
154static int __init opt_nokgdbroundup(char *str)
155{
156 kgdb_do_roundup = 0;
157
158 return 0;
159}
160
161early_param("nokgdbroundup", opt_nokgdbroundup);
162
163/*
164 * Finally, some KGDB code :-)
165 */
166
167/*
168 * Weak aliases for breakpoint management,
169 * can be overriden by architectures when needed:
170 */
Jason Wesseldc7d5522008-04-17 20:05:37 +0200171int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
172{
173 int err;
174
175 err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
176 if (err)
177 return err;
178
179 return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
180 BREAK_INSTR_SIZE);
181}
182
183int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
184{
185 return probe_kernel_write((char *)addr,
186 (char *)bundle, BREAK_INSTR_SIZE);
187}
188
Jason Wessela9b60bf2008-08-01 08:39:34 -0500189int __weak kgdb_validate_break_address(unsigned long addr)
190{
191 char tmp_variable[BREAK_INSTR_SIZE];
192 int err;
193 /* Validate setting the breakpoint and then removing it. In the
194 * remove fails, the kernel needs to emit a bad message because we
195 * are deep trouble not being able to put things back the way we
196 * found them.
197 */
198 err = kgdb_arch_set_breakpoint(addr, tmp_variable);
199 if (err)
200 return err;
201 err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
202 if (err)
203 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
204 "memory destroyed at: %lx", addr);
205 return err;
206}
207
Jason Wesseldc7d5522008-04-17 20:05:37 +0200208unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
209{
210 return instruction_pointer(regs);
211}
212
213int __weak kgdb_arch_init(void)
214{
215 return 0;
216}
217
Jason Wesselb4b8ac52008-02-20 13:33:38 -0600218int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
219{
220 return 0;
221}
222
223void __weak
224kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
225{
226 return;
227}
228
Jason Wesseldc7d5522008-04-17 20:05:37 +0200229/**
230 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
231 * @regs: Current &struct pt_regs.
232 *
233 * This function will be called if the particular architecture must
234 * disable hardware debugging while it is processing gdb packets or
235 * handling exception.
236 */
237void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
238{
239}
240
241/*
242 * GDB remote protocol parser:
243 */
244
Jason Wesseldc7d5522008-04-17 20:05:37 +0200245static int hex(char ch)
246{
247 if ((ch >= 'a') && (ch <= 'f'))
248 return ch - 'a' + 10;
249 if ((ch >= '0') && (ch <= '9'))
250 return ch - '0';
251 if ((ch >= 'A') && (ch <= 'F'))
252 return ch - 'A' + 10;
253 return -1;
254}
255
256/* scan for the sequence $<data>#<checksum> */
257static void get_packet(char *buffer)
258{
259 unsigned char checksum;
260 unsigned char xmitcsum;
261 int count;
262 char ch;
263
264 do {
265 /*
266 * Spin and wait around for the start character, ignore all
267 * other characters:
268 */
269 while ((ch = (kgdb_io_ops->read_char())) != '$')
270 /* nothing */;
271
272 kgdb_connected = 1;
273 checksum = 0;
274 xmitcsum = -1;
275
276 count = 0;
277
278 /*
279 * now, read until a # or end of buffer is found:
280 */
281 while (count < (BUFMAX - 1)) {
282 ch = kgdb_io_ops->read_char();
283 if (ch == '#')
284 break;
285 checksum = checksum + ch;
286 buffer[count] = ch;
287 count = count + 1;
288 }
289 buffer[count] = 0;
290
291 if (ch == '#') {
292 xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
293 xmitcsum += hex(kgdb_io_ops->read_char());
294
295 if (checksum != xmitcsum)
296 /* failed checksum */
297 kgdb_io_ops->write_char('-');
298 else
299 /* successful transfer */
300 kgdb_io_ops->write_char('+');
301 if (kgdb_io_ops->flush)
302 kgdb_io_ops->flush();
303 }
304 } while (checksum != xmitcsum);
305}
306
307/*
308 * Send the packet in buffer.
309 * Check for gdb connection if asked for.
310 */
311static void put_packet(char *buffer)
312{
313 unsigned char checksum;
314 int count;
315 char ch;
316
317 /*
318 * $<packet info>#<checksum>.
319 */
320 while (1) {
321 kgdb_io_ops->write_char('$');
322 checksum = 0;
323 count = 0;
324
325 while ((ch = buffer[count])) {
326 kgdb_io_ops->write_char(ch);
327 checksum += ch;
328 count++;
329 }
330
331 kgdb_io_ops->write_char('#');
Harvey Harrison827e6092008-05-28 12:49:56 -0500332 kgdb_io_ops->write_char(hex_asc_hi(checksum));
333 kgdb_io_ops->write_char(hex_asc_lo(checksum));
Jason Wesseldc7d5522008-04-17 20:05:37 +0200334 if (kgdb_io_ops->flush)
335 kgdb_io_ops->flush();
336
337 /* Now see what we get in reply. */
338 ch = kgdb_io_ops->read_char();
339
340 if (ch == 3)
341 ch = kgdb_io_ops->read_char();
342
343 /* If we get an ACK, we are done. */
344 if (ch == '+')
345 return;
346
347 /*
348 * If we get the start of another packet, this means
349 * that GDB is attempting to reconnect. We will NAK
350 * the packet being sent, and stop trying to send this
351 * packet.
352 */
353 if (ch == '$') {
354 kgdb_io_ops->write_char('-');
355 if (kgdb_io_ops->flush)
356 kgdb_io_ops->flush();
357 return;
358 }
359 }
360}
361
Jason Wesseldc7d5522008-04-17 20:05:37 +0200362/*
363 * Convert the memory pointed to by mem into hex, placing result in buf.
364 * Return a pointer to the last char put in buf (null). May return an error.
365 */
366int kgdb_mem2hex(char *mem, char *buf, int count)
367{
368 char *tmp;
369 int err;
370
371 /*
372 * We use the upper half of buf as an intermediate buffer for the
373 * raw memory copy. Hex conversion will work against this one.
374 */
375 tmp = buf + count;
376
377 err = probe_kernel_read(tmp, mem, count);
378 if (!err) {
379 while (count > 0) {
380 buf = pack_hex_byte(buf, *tmp);
381 tmp++;
382 count--;
383 }
384
385 *buf = 0;
386 }
387
388 return err;
389}
390
391/*
392 * Copy the binary array pointed to by buf into mem. Fix $, #, and
393 * 0x7d escaped with 0x7d. Return a pointer to the character after
394 * the last byte written.
395 */
396static int kgdb_ebin2mem(char *buf, char *mem, int count)
397{
398 int err = 0;
399 char c;
400
401 while (count-- > 0) {
402 c = *buf++;
403 if (c == 0x7d)
404 c = *buf++ ^ 0x20;
405
406 err = probe_kernel_write(mem, &c, 1);
407 if (err)
408 break;
409
410 mem++;
411 }
412
413 return err;
414}
415
416/*
417 * Convert the hex array pointed to by buf into binary to be placed in mem.
418 * Return a pointer to the character AFTER the last byte written.
419 * May return an error.
420 */
421int kgdb_hex2mem(char *buf, char *mem, int count)
422{
423 char *tmp_raw;
424 char *tmp_hex;
425
426 /*
427 * We use the upper half of buf as an intermediate buffer for the
428 * raw memory that is converted from hex.
429 */
430 tmp_raw = buf + count * 2;
431
432 tmp_hex = tmp_raw - 1;
433 while (tmp_hex >= buf) {
434 tmp_raw--;
435 *tmp_raw = hex(*tmp_hex--);
436 *tmp_raw |= hex(*tmp_hex--) << 4;
437 }
438
439 return probe_kernel_write(mem, tmp_raw, count);
440}
441
442/*
443 * While we find nice hex chars, build a long_val.
444 * Return number of chars processed.
445 */
Harvey Harrison688b7442008-04-24 16:57:23 -0500446int kgdb_hex2long(char **ptr, unsigned long *long_val)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200447{
448 int hex_val;
449 int num = 0;
Jason Wessel25fc9992008-08-01 08:39:35 -0500450 int negate = 0;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200451
452 *long_val = 0;
453
Jason Wessel25fc9992008-08-01 08:39:35 -0500454 if (**ptr == '-') {
455 negate = 1;
456 (*ptr)++;
457 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200458 while (**ptr) {
459 hex_val = hex(**ptr);
460 if (hex_val < 0)
461 break;
462
463 *long_val = (*long_val << 4) | hex_val;
464 num++;
465 (*ptr)++;
466 }
467
Jason Wessel25fc9992008-08-01 08:39:35 -0500468 if (negate)
469 *long_val = -*long_val;
470
Jason Wesseldc7d5522008-04-17 20:05:37 +0200471 return num;
472}
473
474/* Write memory due to an 'M' or 'X' packet. */
475static int write_mem_msg(int binary)
476{
477 char *ptr = &remcom_in_buffer[1];
478 unsigned long addr;
479 unsigned long length;
480 int err;
481
482 if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
483 kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
484 if (binary)
485 err = kgdb_ebin2mem(ptr, (char *)addr, length);
486 else
487 err = kgdb_hex2mem(ptr, (char *)addr, length);
488 if (err)
489 return err;
490 if (CACHE_FLUSH_IS_SAFE)
Atsuo Igarashi18d65222008-09-26 10:36:41 -0500491 flush_icache_range(addr, addr + length);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200492 return 0;
493 }
494
495 return -EINVAL;
496}
497
498static void error_packet(char *pkt, int error)
499{
500 error = -error;
501 pkt[0] = 'E';
Harvey Harrison827e6092008-05-28 12:49:56 -0500502 pkt[1] = hex_asc[(error / 10)];
503 pkt[2] = hex_asc[(error % 10)];
Jason Wesseldc7d5522008-04-17 20:05:37 +0200504 pkt[3] = '\0';
505}
506
507/*
508 * Thread ID accessors. We represent a flat TID space to GDB, where
509 * the per CPU idle threads (which under Linux all have PID 0) are
510 * remapped to negative TIDs.
511 */
512
513#define BUF_THREAD_ID_SIZE 16
514
515static char *pack_threadid(char *pkt, unsigned char *id)
516{
517 char *limit;
518
519 limit = pkt + BUF_THREAD_ID_SIZE;
520 while (pkt < limit)
521 pkt = pack_hex_byte(pkt, *id++);
522
523 return pkt;
524}
525
526static void int_to_threadref(unsigned char *id, int value)
527{
528 unsigned char *scan;
529 int i = 4;
530
531 scan = (unsigned char *)id;
532 while (i--)
533 *scan++ = 0;
Harvey Harrison827e6092008-05-28 12:49:56 -0500534 put_unaligned_be32(value, scan);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200535}
536
537static struct task_struct *getthread(struct pt_regs *regs, int tid)
538{
539 /*
Jason Wessel25fc9992008-08-01 08:39:35 -0500540 * Non-positive TIDs are remapped to the cpu shadow information
Jason Wesseldc7d5522008-04-17 20:05:37 +0200541 */
Jason Wessel25fc9992008-08-01 08:39:35 -0500542 if (tid == 0 || tid == -1)
543 tid = -atomic_read(&kgdb_active) - 2;
544 if (tid < 0) {
545 if (kgdb_info[-tid - 2].task)
546 return kgdb_info[-tid - 2].task;
547 else
548 return idle_task(-tid - 2);
549 }
Jason Wesseldc7d5522008-04-17 20:05:37 +0200550
551 /*
552 * find_task_by_pid_ns() does not take the tasklist lock anymore
553 * but is nicely RCU locked - hence is a pretty resilient
554 * thing to use:
555 */
556 return find_task_by_pid_ns(tid, &init_pid_ns);
557}
558
559/*
560 * CPU debug state control:
561 */
562
563#ifdef CONFIG_SMP
564static void kgdb_wait(struct pt_regs *regs)
565{
566 unsigned long flags;
567 int cpu;
568
569 local_irq_save(flags);
570 cpu = raw_smp_processor_id();
571 kgdb_info[cpu].debuggerinfo = regs;
572 kgdb_info[cpu].task = current;
573 /*
574 * Make sure the above info reaches the primary CPU before
575 * our cpu_in_kgdb[] flag setting does:
576 */
577 smp_wmb();
578 atomic_set(&cpu_in_kgdb[cpu], 1);
579
Jason Wesseldc7d5522008-04-17 20:05:37 +0200580 /* Wait till primary CPU is done with debugging */
581 while (atomic_read(&passive_cpu_wait[cpu]))
582 cpu_relax();
583
584 kgdb_info[cpu].debuggerinfo = NULL;
585 kgdb_info[cpu].task = NULL;
586
587 /* fix up hardware debug registers on local cpu */
588 if (arch_kgdb_ops.correct_hw_break)
589 arch_kgdb_ops.correct_hw_break();
590
591 /* Signal the primary CPU that we are done: */
592 atomic_set(&cpu_in_kgdb[cpu], 0);
Jason Wesselcc1e0f42008-10-06 13:50:59 -0500593 touch_softlockup_watchdog();
Jason Wessel7c3078b2008-02-15 14:55:54 -0600594 clocksource_touch_watchdog();
Jason Wesseldc7d5522008-04-17 20:05:37 +0200595 local_irq_restore(flags);
596}
597#endif
598
599/*
600 * Some architectures need cache flushes when we set/clear a
601 * breakpoint:
602 */
603static void kgdb_flush_swbreak_addr(unsigned long addr)
604{
605 if (!CACHE_FLUSH_IS_SAFE)
606 return;
607
Jason Wessel737a4602008-03-07 16:34:16 -0600608 if (current->mm && current->mm->mmap_cache) {
Jason Wesseldc7d5522008-04-17 20:05:37 +0200609 flush_cache_range(current->mm->mmap_cache,
610 addr, addr + BREAK_INSTR_SIZE);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200611 }
Jason Wessel1a9a3e72008-04-01 16:55:28 -0500612 /* Force flush instruction cache if it was outside the mm */
613 flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
Jason Wesseldc7d5522008-04-17 20:05:37 +0200614}
615
616/*
617 * SW breakpoint management:
618 */
619static int kgdb_activate_sw_breakpoints(void)
620{
621 unsigned long addr;
622 int error = 0;
623 int i;
624
625 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
626 if (kgdb_break[i].state != BP_SET)
627 continue;
628
629 addr = kgdb_break[i].bpt_addr;
630 error = kgdb_arch_set_breakpoint(addr,
631 kgdb_break[i].saved_instr);
632 if (error)
633 return error;
634
635 kgdb_flush_swbreak_addr(addr);
636 kgdb_break[i].state = BP_ACTIVE;
637 }
638 return 0;
639}
640
641static int kgdb_set_sw_break(unsigned long addr)
642{
643 int err = kgdb_validate_break_address(addr);
644 int breakno = -1;
645 int i;
646
647 if (err)
648 return err;
649
650 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
651 if ((kgdb_break[i].state == BP_SET) &&
652 (kgdb_break[i].bpt_addr == addr))
653 return -EEXIST;
654 }
655 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
656 if (kgdb_break[i].state == BP_REMOVED &&
657 kgdb_break[i].bpt_addr == addr) {
658 breakno = i;
659 break;
660 }
661 }
662
663 if (breakno == -1) {
664 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
665 if (kgdb_break[i].state == BP_UNDEFINED) {
666 breakno = i;
667 break;
668 }
669 }
670 }
671
672 if (breakno == -1)
673 return -E2BIG;
674
675 kgdb_break[breakno].state = BP_SET;
676 kgdb_break[breakno].type = BP_BREAKPOINT;
677 kgdb_break[breakno].bpt_addr = addr;
678
679 return 0;
680}
681
682static int kgdb_deactivate_sw_breakpoints(void)
683{
684 unsigned long addr;
685 int error = 0;
686 int i;
687
688 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
689 if (kgdb_break[i].state != BP_ACTIVE)
690 continue;
691 addr = kgdb_break[i].bpt_addr;
692 error = kgdb_arch_remove_breakpoint(addr,
693 kgdb_break[i].saved_instr);
694 if (error)
695 return error;
696
697 kgdb_flush_swbreak_addr(addr);
698 kgdb_break[i].state = BP_SET;
699 }
700 return 0;
701}
702
703static int kgdb_remove_sw_break(unsigned long addr)
704{
705 int i;
706
707 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
708 if ((kgdb_break[i].state == BP_SET) &&
709 (kgdb_break[i].bpt_addr == addr)) {
710 kgdb_break[i].state = BP_REMOVED;
711 return 0;
712 }
713 }
714 return -ENOENT;
715}
716
717int kgdb_isremovedbreak(unsigned long addr)
718{
719 int i;
720
721 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
722 if ((kgdb_break[i].state == BP_REMOVED) &&
723 (kgdb_break[i].bpt_addr == addr))
724 return 1;
725 }
726 return 0;
727}
728
Harvey Harrison688b7442008-04-24 16:57:23 -0500729static int remove_all_break(void)
Jason Wesseldc7d5522008-04-17 20:05:37 +0200730{
731 unsigned long addr;
732 int error;
733 int i;
734
735 /* Clear memory breakpoints. */
736 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
Jason Wessel737a4602008-03-07 16:34:16 -0600737 if (kgdb_break[i].state != BP_ACTIVE)
738 goto setundefined;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200739 addr = kgdb_break[i].bpt_addr;
740 error = kgdb_arch_remove_breakpoint(addr,
741 kgdb_break[i].saved_instr);
742 if (error)
Jason Wessel737a4602008-03-07 16:34:16 -0600743 printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
744 addr);
745setundefined:
746 kgdb_break[i].state = BP_UNDEFINED;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200747 }
748
749 /* Clear hardware breakpoints. */
750 if (arch_kgdb_ops.remove_all_hw_break)
751 arch_kgdb_ops.remove_all_hw_break();
752
753 return 0;
754}
755
756/*
Jason Wessel25fc9992008-08-01 08:39:35 -0500757 * Remap normal tasks to their real PID,
758 * CPU shadow threads are mapped to -CPU - 2
Jason Wesseldc7d5522008-04-17 20:05:37 +0200759 */
760static inline int shadow_pid(int realpid)
761{
762 if (realpid)
763 return realpid;
764
Jason Wessel25fc9992008-08-01 08:39:35 -0500765 return -raw_smp_processor_id() - 2;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200766}
767
768static char gdbmsgbuf[BUFMAX + 1];
769
770static void kgdb_msg_write(const char *s, int len)
771{
772 char *bufptr;
773 int wcount;
774 int i;
775
776 /* 'O'utput */
777 gdbmsgbuf[0] = 'O';
778
779 /* Fill and send buffers... */
780 while (len > 0) {
781 bufptr = gdbmsgbuf + 1;
782
783 /* Calculate how many this time */
784 if ((len << 1) > (BUFMAX - 2))
785 wcount = (BUFMAX - 2) >> 1;
786 else
787 wcount = len;
788
789 /* Pack in hex chars */
790 for (i = 0; i < wcount; i++)
791 bufptr = pack_hex_byte(bufptr, s[i]);
792 *bufptr = '\0';
793
794 /* Move up */
795 s += wcount;
796 len -= wcount;
797
798 /* Write packet */
799 put_packet(gdbmsgbuf);
800 }
801}
802
803/*
804 * Return true if there is a valid kgdb I/O module. Also if no
805 * debugger is attached a message can be printed to the console about
806 * waiting for the debugger to attach.
807 *
808 * The print_wait argument is only to be true when called from inside
809 * the core kgdb_handle_exception, because it will wait for the
810 * debugger to attach.
811 */
812static int kgdb_io_ready(int print_wait)
813{
814 if (!kgdb_io_ops)
815 return 0;
816 if (kgdb_connected)
817 return 1;
818 if (atomic_read(&kgdb_setting_breakpoint))
819 return 1;
820 if (print_wait)
821 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
822 return 1;
823}
824
825/*
826 * All the functions that start with gdb_cmd are the various
827 * operations to implement the handlers for the gdbserial protocol
828 * where KGDB is communicating with an external debugger
829 */
830
831/* Handle the '?' status packets */
832static void gdb_cmd_status(struct kgdb_state *ks)
833{
834 /*
835 * We know that this packet is only sent
836 * during initial connect. So to be safe,
837 * we clear out our breakpoints now in case
838 * GDB is reconnecting.
839 */
840 remove_all_break();
841
842 remcom_out_buffer[0] = 'S';
843 pack_hex_byte(&remcom_out_buffer[1], ks->signo);
844}
845
846/* Handle the 'g' get registers request */
847static void gdb_cmd_getregs(struct kgdb_state *ks)
848{
849 struct task_struct *thread;
850 void *local_debuggerinfo;
851 int i;
852
853 thread = kgdb_usethread;
854 if (!thread) {
855 thread = kgdb_info[ks->cpu].task;
856 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
857 } else {
858 local_debuggerinfo = NULL;
Jason Wessel25fc9992008-08-01 08:39:35 -0500859 for_each_online_cpu(i) {
Jason Wesseldc7d5522008-04-17 20:05:37 +0200860 /*
861 * Try to find the task on some other
862 * or possibly this node if we do not
863 * find the matching task then we try
864 * to approximate the results.
865 */
866 if (thread == kgdb_info[i].task)
867 local_debuggerinfo = kgdb_info[i].debuggerinfo;
868 }
869 }
870
871 /*
872 * All threads that don't have debuggerinfo should be
873 * in __schedule() sleeping, since all other CPUs
874 * are in kgdb_wait, and thus have debuggerinfo.
875 */
876 if (local_debuggerinfo) {
877 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
878 } else {
879 /*
880 * Pull stuff saved during switch_to; nothing
881 * else is accessible (or even particularly
882 * relevant).
883 *
884 * This should be enough for a stack trace.
885 */
886 sleeping_thread_to_gdb_regs(gdb_regs, thread);
887 }
888 kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
889}
890
891/* Handle the 'G' set registers request */
892static void gdb_cmd_setregs(struct kgdb_state *ks)
893{
894 kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
895
896 if (kgdb_usethread && kgdb_usethread != current) {
897 error_packet(remcom_out_buffer, -EINVAL);
898 } else {
899 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
900 strcpy(remcom_out_buffer, "OK");
901 }
902}
903
904/* Handle the 'm' memory read bytes */
905static void gdb_cmd_memread(struct kgdb_state *ks)
906{
907 char *ptr = &remcom_in_buffer[1];
908 unsigned long length;
909 unsigned long addr;
910 int err;
911
912 if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
913 kgdb_hex2long(&ptr, &length) > 0) {
914 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
915 if (err)
916 error_packet(remcom_out_buffer, err);
917 } else {
918 error_packet(remcom_out_buffer, -EINVAL);
919 }
920}
921
922/* Handle the 'M' memory write bytes */
923static void gdb_cmd_memwrite(struct kgdb_state *ks)
924{
925 int err = write_mem_msg(0);
926
927 if (err)
928 error_packet(remcom_out_buffer, err);
929 else
930 strcpy(remcom_out_buffer, "OK");
931}
932
933/* Handle the 'X' memory binary write bytes */
934static void gdb_cmd_binwrite(struct kgdb_state *ks)
935{
936 int err = write_mem_msg(1);
937
938 if (err)
939 error_packet(remcom_out_buffer, err);
940 else
941 strcpy(remcom_out_buffer, "OK");
942}
943
944/* Handle the 'D' or 'k', detach or kill packets */
945static void gdb_cmd_detachkill(struct kgdb_state *ks)
946{
947 int error;
948
949 /* The detach case */
950 if (remcom_in_buffer[0] == 'D') {
951 error = remove_all_break();
952 if (error < 0) {
953 error_packet(remcom_out_buffer, error);
954 } else {
955 strcpy(remcom_out_buffer, "OK");
956 kgdb_connected = 0;
957 }
958 put_packet(remcom_out_buffer);
959 } else {
960 /*
961 * Assume the kill case, with no exit code checking,
962 * trying to force detach the debugger:
963 */
964 remove_all_break();
965 kgdb_connected = 0;
966 }
967}
968
969/* Handle the 'R' reboot packets */
970static int gdb_cmd_reboot(struct kgdb_state *ks)
971{
972 /* For now, only honor R0 */
973 if (strcmp(remcom_in_buffer, "R0") == 0) {
974 printk(KERN_CRIT "Executing emergency reboot\n");
975 strcpy(remcom_out_buffer, "OK");
976 put_packet(remcom_out_buffer);
977
978 /*
979 * Execution should not return from
980 * machine_emergency_restart()
981 */
982 machine_emergency_restart();
983 kgdb_connected = 0;
984
985 return 1;
986 }
987 return 0;
988}
989
990/* Handle the 'q' query packets */
991static void gdb_cmd_query(struct kgdb_state *ks)
992{
Jason Wessel25fc9992008-08-01 08:39:35 -0500993 struct task_struct *g;
994 struct task_struct *p;
Jason Wesseldc7d5522008-04-17 20:05:37 +0200995 unsigned char thref[8];
996 char *ptr;
997 int i;
Jason Wessel25fc9992008-08-01 08:39:35 -0500998 int cpu;
999 int finished = 0;
Jason Wesseldc7d5522008-04-17 20:05:37 +02001000
1001 switch (remcom_in_buffer[1]) {
1002 case 's':
1003 case 'f':
1004 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
1005 error_packet(remcom_out_buffer, -EINVAL);
1006 break;
1007 }
1008
Jason Wessel25fc9992008-08-01 08:39:35 -05001009 i = 0;
Jason Wesseldc7d5522008-04-17 20:05:37 +02001010 remcom_out_buffer[0] = 'm';
1011 ptr = remcom_out_buffer + 1;
Jason Wessel25fc9992008-08-01 08:39:35 -05001012 if (remcom_in_buffer[1] == 'f') {
1013 /* Each cpu is a shadow thread */
1014 for_each_online_cpu(cpu) {
1015 ks->thr_query = 0;
1016 int_to_threadref(thref, -cpu - 2);
Jason Wesseldc7d5522008-04-17 20:05:37 +02001017 pack_threadid(ptr, thref);
1018 ptr += BUF_THREAD_ID_SIZE;
1019 *(ptr++) = ',';
1020 i++;
1021 }
1022 }
Jason Wessel25fc9992008-08-01 08:39:35 -05001023
1024 do_each_thread(g, p) {
1025 if (i >= ks->thr_query && !finished) {
1026 int_to_threadref(thref, p->pid);
1027 pack_threadid(ptr, thref);
1028 ptr += BUF_THREAD_ID_SIZE;
1029 *(ptr++) = ',';
1030 ks->thr_query++;
1031 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
1032 finished = 1;
1033 }
1034 i++;
1035 } while_each_thread(g, p);
1036
Jason Wesseldc7d5522008-04-17 20:05:37 +02001037 *(--ptr) = '\0';
1038 break;
1039
1040 case 'C':
1041 /* Current thread id */
1042 strcpy(remcom_out_buffer, "QC");
1043 ks->threadid = shadow_pid(current->pid);
1044 int_to_threadref(thref, ks->threadid);
1045 pack_threadid(remcom_out_buffer + 2, thref);
1046 break;
1047 case 'T':
1048 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1049 error_packet(remcom_out_buffer, -EINVAL);
1050 break;
1051 }
1052 ks->threadid = 0;
1053 ptr = remcom_in_buffer + 17;
1054 kgdb_hex2long(&ptr, &ks->threadid);
1055 if (!getthread(ks->linux_regs, ks->threadid)) {
1056 error_packet(remcom_out_buffer, -EINVAL);
1057 break;
1058 }
Jason Wessel25fc9992008-08-01 08:39:35 -05001059 if ((int)ks->threadid > 0) {
Jason Wesseldc7d5522008-04-17 20:05:37 +02001060 kgdb_mem2hex(getthread(ks->linux_regs,
1061 ks->threadid)->comm,
1062 remcom_out_buffer, 16);
1063 } else {
1064 static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1065
Jason Wessel25fc9992008-08-01 08:39:35 -05001066 sprintf(tmpstr, "shadowCPU%d",
1067 (int)(-ks->threadid - 2));
Jason Wesseldc7d5522008-04-17 20:05:37 +02001068 kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1069 }
1070 break;
1071 }
1072}
1073
1074/* Handle the 'H' task query packets */
1075static void gdb_cmd_task(struct kgdb_state *ks)
1076{
1077 struct task_struct *thread;
1078 char *ptr;
1079
1080 switch (remcom_in_buffer[1]) {
1081 case 'g':
1082 ptr = &remcom_in_buffer[2];
1083 kgdb_hex2long(&ptr, &ks->threadid);
1084 thread = getthread(ks->linux_regs, ks->threadid);
1085 if (!thread && ks->threadid > 0) {
1086 error_packet(remcom_out_buffer, -EINVAL);
1087 break;
1088 }
1089 kgdb_usethread = thread;
1090 ks->kgdb_usethreadid = ks->threadid;
1091 strcpy(remcom_out_buffer, "OK");
1092 break;
1093 case 'c':
1094 ptr = &remcom_in_buffer[2];
1095 kgdb_hex2long(&ptr, &ks->threadid);
1096 if (!ks->threadid) {
1097 kgdb_contthread = NULL;
1098 } else {
1099 thread = getthread(ks->linux_regs, ks->threadid);
1100 if (!thread && ks->threadid > 0) {
1101 error_packet(remcom_out_buffer, -EINVAL);
1102 break;
1103 }
1104 kgdb_contthread = thread;
1105 }
1106 strcpy(remcom_out_buffer, "OK");
1107 break;
1108 }
1109}
1110
1111/* Handle the 'T' thread query packets */
1112static void gdb_cmd_thread(struct kgdb_state *ks)
1113{
1114 char *ptr = &remcom_in_buffer[1];
1115 struct task_struct *thread;
1116
1117 kgdb_hex2long(&ptr, &ks->threadid);
1118 thread = getthread(ks->linux_regs, ks->threadid);
1119 if (thread)
1120 strcpy(remcom_out_buffer, "OK");
1121 else
1122 error_packet(remcom_out_buffer, -EINVAL);
1123}
1124
1125/* Handle the 'z' or 'Z' breakpoint remove or set packets */
1126static void gdb_cmd_break(struct kgdb_state *ks)
1127{
1128 /*
1129 * Since GDB-5.3, it's been drafted that '0' is a software
1130 * breakpoint, '1' is a hardware breakpoint, so let's do that.
1131 */
1132 char *bpt_type = &remcom_in_buffer[1];
1133 char *ptr = &remcom_in_buffer[2];
1134 unsigned long addr;
1135 unsigned long length;
1136 int error = 0;
1137
1138 if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1139 /* Unsupported */
1140 if (*bpt_type > '4')
1141 return;
1142 } else {
1143 if (*bpt_type != '0' && *bpt_type != '1')
1144 /* Unsupported. */
1145 return;
1146 }
1147
1148 /*
1149 * Test if this is a hardware breakpoint, and
1150 * if we support it:
1151 */
1152 if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1153 /* Unsupported. */
1154 return;
1155
1156 if (*(ptr++) != ',') {
1157 error_packet(remcom_out_buffer, -EINVAL);
1158 return;
1159 }
1160 if (!kgdb_hex2long(&ptr, &addr)) {
1161 error_packet(remcom_out_buffer, -EINVAL);
1162 return;
1163 }
1164 if (*(ptr++) != ',' ||
1165 !kgdb_hex2long(&ptr, &length)) {
1166 error_packet(remcom_out_buffer, -EINVAL);
1167 return;
1168 }
1169
1170 if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1171 error = kgdb_set_sw_break(addr);
1172 else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1173 error = kgdb_remove_sw_break(addr);
1174 else if (remcom_in_buffer[0] == 'Z')
1175 error = arch_kgdb_ops.set_hw_breakpoint(addr,
Jason Wessel64e9ee32008-02-15 14:55:56 -06001176 (int)length, *bpt_type - '0');
Jason Wesseldc7d5522008-04-17 20:05:37 +02001177 else if (remcom_in_buffer[0] == 'z')
1178 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
Jason Wessel64e9ee32008-02-15 14:55:56 -06001179 (int) length, *bpt_type - '0');
Jason Wesseldc7d5522008-04-17 20:05:37 +02001180
1181 if (error == 0)
1182 strcpy(remcom_out_buffer, "OK");
1183 else
1184 error_packet(remcom_out_buffer, error);
1185}
1186
1187/* Handle the 'C' signal / exception passing packets */
1188static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1189{
1190 /* C09 == pass exception
1191 * C15 == detach kgdb, pass exception
1192 */
1193 if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1194
1195 ks->pass_exception = 1;
1196 remcom_in_buffer[0] = 'c';
1197
1198 } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1199
1200 ks->pass_exception = 1;
1201 remcom_in_buffer[0] = 'D';
1202 remove_all_break();
1203 kgdb_connected = 0;
1204 return 1;
1205
1206 } else {
1207 error_packet(remcom_out_buffer, -EINVAL);
1208 return 0;
1209 }
1210
1211 /* Indicate fall through */
1212 return -1;
1213}
1214
1215/*
1216 * This function performs all gdbserial command procesing
1217 */
1218static int gdb_serial_stub(struct kgdb_state *ks)
1219{
1220 int error = 0;
1221 int tmp;
1222
1223 /* Clear the out buffer. */
1224 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1225
1226 if (kgdb_connected) {
1227 unsigned char thref[8];
1228 char *ptr;
1229
1230 /* Reply to host that an exception has occurred */
1231 ptr = remcom_out_buffer;
1232 *ptr++ = 'T';
1233 ptr = pack_hex_byte(ptr, ks->signo);
1234 ptr += strlen(strcpy(ptr, "thread:"));
1235 int_to_threadref(thref, shadow_pid(current->pid));
1236 ptr = pack_threadid(ptr, thref);
1237 *ptr++ = ';';
1238 put_packet(remcom_out_buffer);
1239 }
1240
1241 kgdb_usethread = kgdb_info[ks->cpu].task;
1242 ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1243 ks->pass_exception = 0;
1244
1245 while (1) {
1246 error = 0;
1247
1248 /* Clear the out buffer. */
1249 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1250
1251 get_packet(remcom_in_buffer);
1252
1253 switch (remcom_in_buffer[0]) {
1254 case '?': /* gdbserial status */
1255 gdb_cmd_status(ks);
1256 break;
1257 case 'g': /* return the value of the CPU registers */
1258 gdb_cmd_getregs(ks);
1259 break;
1260 case 'G': /* set the value of the CPU registers - return OK */
1261 gdb_cmd_setregs(ks);
1262 break;
1263 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
1264 gdb_cmd_memread(ks);
1265 break;
1266 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1267 gdb_cmd_memwrite(ks);
1268 break;
1269 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1270 gdb_cmd_binwrite(ks);
1271 break;
1272 /* kill or detach. KGDB should treat this like a
1273 * continue.
1274 */
1275 case 'D': /* Debugger detach */
1276 case 'k': /* Debugger detach via kill */
1277 gdb_cmd_detachkill(ks);
1278 goto default_handle;
1279 case 'R': /* Reboot */
1280 if (gdb_cmd_reboot(ks))
1281 goto default_handle;
1282 break;
1283 case 'q': /* query command */
1284 gdb_cmd_query(ks);
1285 break;
1286 case 'H': /* task related */
1287 gdb_cmd_task(ks);
1288 break;
1289 case 'T': /* Query thread status */
1290 gdb_cmd_thread(ks);
1291 break;
1292 case 'z': /* Break point remove */
1293 case 'Z': /* Break point set */
1294 gdb_cmd_break(ks);
1295 break;
1296 case 'C': /* Exception passing */
1297 tmp = gdb_cmd_exception_pass(ks);
1298 if (tmp > 0)
1299 goto default_handle;
1300 if (tmp == 0)
1301 break;
1302 /* Fall through on tmp < 0 */
1303 case 'c': /* Continue packet */
1304 case 's': /* Single step packet */
1305 if (kgdb_contthread && kgdb_contthread != current) {
1306 /* Can't switch threads in kgdb */
1307 error_packet(remcom_out_buffer, -EINVAL);
1308 break;
1309 }
1310 kgdb_activate_sw_breakpoints();
1311 /* Fall through to default processing */
1312 default:
1313default_handle:
1314 error = kgdb_arch_handle_exception(ks->ex_vector,
1315 ks->signo,
1316 ks->err_code,
1317 remcom_in_buffer,
1318 remcom_out_buffer,
1319 ks->linux_regs);
1320 /*
1321 * Leave cmd processing on error, detach,
1322 * kill, continue, or single step.
1323 */
1324 if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1325 remcom_in_buffer[0] == 'k') {
1326 error = 0;
1327 goto kgdb_exit;
1328 }
1329
1330 }
1331
1332 /* reply to the request */
1333 put_packet(remcom_out_buffer);
1334 }
1335
1336kgdb_exit:
1337 if (ks->pass_exception)
1338 error = 1;
1339 return error;
1340}
1341
1342static int kgdb_reenter_check(struct kgdb_state *ks)
1343{
1344 unsigned long addr;
1345
1346 if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1347 return 0;
1348
1349 /* Panic on recursive debugger calls: */
1350 exception_level++;
1351 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1352 kgdb_deactivate_sw_breakpoints();
1353
1354 /*
1355 * If the break point removed ok at the place exception
1356 * occurred, try to recover and print a warning to the end
1357 * user because the user planted a breakpoint in a place that
1358 * KGDB needs in order to function.
1359 */
1360 if (kgdb_remove_sw_break(addr) == 0) {
1361 exception_level = 0;
1362 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1363 kgdb_activate_sw_breakpoints();
Jason Wessel67baf942008-02-15 14:55:55 -06001364 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1365 addr);
Jason Wesseldc7d5522008-04-17 20:05:37 +02001366 WARN_ON_ONCE(1);
1367
1368 return 1;
1369 }
1370 remove_all_break();
1371 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1372
1373 if (exception_level > 1) {
1374 dump_stack();
1375 panic("Recursive entry to debugger");
1376 }
1377
1378 printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1379 dump_stack();
1380 panic("Recursive entry to debugger");
1381
1382 return 1;
1383}
1384
1385/*
1386 * kgdb_handle_exception() - main entry point from a kernel exception
1387 *
1388 * Locking hierarchy:
1389 * interface locks, if any (begin_session)
1390 * kgdb lock (kgdb_active)
1391 */
1392int
1393kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1394{
1395 struct kgdb_state kgdb_var;
1396 struct kgdb_state *ks = &kgdb_var;
1397 unsigned long flags;
1398 int error = 0;
1399 int i, cpu;
1400
1401 ks->cpu = raw_smp_processor_id();
1402 ks->ex_vector = evector;
1403 ks->signo = signo;
1404 ks->ex_vector = evector;
1405 ks->err_code = ecode;
1406 ks->kgdb_usethreadid = 0;
1407 ks->linux_regs = regs;
1408
1409 if (kgdb_reenter_check(ks))
1410 return 0; /* Ouch, double exception ! */
1411
1412acquirelock:
1413 /*
1414 * Interrupts will be restored by the 'trap return' code, except when
1415 * single stepping.
1416 */
1417 local_irq_save(flags);
1418
1419 cpu = raw_smp_processor_id();
1420
1421 /*
1422 * Acquire the kgdb_active lock:
1423 */
1424 while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
1425 cpu_relax();
1426
1427 /*
1428 * Do not start the debugger connection on this CPU if the last
1429 * instance of the exception handler wanted to come into the
1430 * debugger on a different CPU via a single step
1431 */
1432 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1433 atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
1434
1435 atomic_set(&kgdb_active, -1);
Jason Wesselcc1e0f42008-10-06 13:50:59 -05001436 touch_softlockup_watchdog();
Jason Wessel7c3078b2008-02-15 14:55:54 -06001437 clocksource_touch_watchdog();
Jason Wesseldc7d5522008-04-17 20:05:37 +02001438 local_irq_restore(flags);
1439
1440 goto acquirelock;
1441 }
1442
1443 if (!kgdb_io_ready(1)) {
1444 error = 1;
1445 goto kgdb_restore; /* No I/O connection, so resume the system */
1446 }
1447
1448 /*
1449 * Don't enter if we have hit a removed breakpoint.
1450 */
1451 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1452 goto kgdb_restore;
1453
1454 /* Call the I/O driver's pre_exception routine */
1455 if (kgdb_io_ops->pre_exception)
1456 kgdb_io_ops->pre_exception();
1457
1458 kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
1459 kgdb_info[ks->cpu].task = current;
1460
1461 kgdb_disable_hw_debug(ks->linux_regs);
1462
1463 /*
1464 * Get the passive CPU lock which will hold all the non-primary
1465 * CPU in a spin state while the debugger is active
1466 */
Jason Wesseld7161a62008-09-26 10:36:41 -05001467 if (!kgdb_single_step) {
Jason Wesseldc7d5522008-04-17 20:05:37 +02001468 for (i = 0; i < NR_CPUS; i++)
1469 atomic_set(&passive_cpu_wait[i], 1);
1470 }
1471
Jason Wesseldc7d5522008-04-17 20:05:37 +02001472 /*
1473 * spin_lock code is good enough as a barrier so we don't
1474 * need one here:
1475 */
1476 atomic_set(&cpu_in_kgdb[ks->cpu], 1);
1477
Jason Wessel56fb7092008-04-01 16:55:27 -05001478#ifdef CONFIG_SMP
1479 /* Signal the other CPUs to enter kgdb_wait() */
Jason Wesseld7161a62008-09-26 10:36:41 -05001480 if ((!kgdb_single_step) && kgdb_do_roundup)
Jason Wessel56fb7092008-04-01 16:55:27 -05001481 kgdb_roundup_cpus(flags);
1482#endif
1483
Jason Wesseldc7d5522008-04-17 20:05:37 +02001484 /*
1485 * Wait for the other CPUs to be notified and be waiting for us:
1486 */
1487 for_each_online_cpu(i) {
1488 while (!atomic_read(&cpu_in_kgdb[i]))
1489 cpu_relax();
1490 }
1491
1492 /*
1493 * At this point the primary processor is completely
1494 * in the debugger and all secondary CPUs are quiescent
1495 */
1496 kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1497 kgdb_deactivate_sw_breakpoints();
1498 kgdb_single_step = 0;
Jason Wesseld7161a62008-09-26 10:36:41 -05001499 kgdb_contthread = current;
Jason Wesseldc7d5522008-04-17 20:05:37 +02001500 exception_level = 0;
1501
1502 /* Talk to debugger with gdbserial protocol */
1503 error = gdb_serial_stub(ks);
1504
1505 /* Call the I/O driver's post_exception routine */
1506 if (kgdb_io_ops->post_exception)
1507 kgdb_io_ops->post_exception();
1508
1509 kgdb_info[ks->cpu].debuggerinfo = NULL;
1510 kgdb_info[ks->cpu].task = NULL;
1511 atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1512
Jason Wesseld7161a62008-09-26 10:36:41 -05001513 if (!kgdb_single_step) {
Jason Wesseldc7d5522008-04-17 20:05:37 +02001514 for (i = NR_CPUS-1; i >= 0; i--)
1515 atomic_set(&passive_cpu_wait[i], 0);
1516 /*
1517 * Wait till all the CPUs have quit
1518 * from the debugger.
1519 */
1520 for_each_online_cpu(i) {
1521 while (atomic_read(&cpu_in_kgdb[i]))
1522 cpu_relax();
1523 }
1524 }
1525
1526kgdb_restore:
1527 /* Free kgdb_active */
1528 atomic_set(&kgdb_active, -1);
Jason Wesselcc1e0f42008-10-06 13:50:59 -05001529 touch_softlockup_watchdog();
Jason Wessel7c3078b2008-02-15 14:55:54 -06001530 clocksource_touch_watchdog();
Jason Wesseldc7d5522008-04-17 20:05:37 +02001531 local_irq_restore(flags);
1532
1533 return error;
1534}
1535
1536int kgdb_nmicallback(int cpu, void *regs)
1537{
1538#ifdef CONFIG_SMP
1539 if (!atomic_read(&cpu_in_kgdb[cpu]) &&
Jason Wessel56fb7092008-04-01 16:55:27 -05001540 atomic_read(&kgdb_active) != cpu &&
1541 atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
Jason Wesseldc7d5522008-04-17 20:05:37 +02001542 kgdb_wait((struct pt_regs *)regs);
1543 return 0;
1544 }
1545#endif
1546 return 1;
1547}
1548
Jason Wesselaabdc3b2008-06-24 10:52:55 -05001549static void kgdb_console_write(struct console *co, const char *s,
1550 unsigned count)
Jason Wesseldc7d5522008-04-17 20:05:37 +02001551{
1552 unsigned long flags;
1553
1554 /* If we're debugging, or KGDB has not connected, don't try
1555 * and print. */
1556 if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
1557 return;
1558
1559 local_irq_save(flags);
1560 kgdb_msg_write(s, count);
1561 local_irq_restore(flags);
1562}
1563
1564static struct console kgdbcons = {
1565 .name = "kgdb",
1566 .write = kgdb_console_write,
1567 .flags = CON_PRINTBUFFER | CON_ENABLED,
1568 .index = -1,
1569};
1570
1571#ifdef CONFIG_MAGIC_SYSRQ
1572static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1573{
1574 if (!kgdb_io_ops) {
1575 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1576 return;
1577 }
1578 if (!kgdb_connected)
1579 printk(KERN_CRIT "Entering KGDB\n");
1580
1581 kgdb_breakpoint();
1582}
1583
1584static struct sysrq_key_op sysrq_gdb_op = {
1585 .handler = sysrq_handle_gdb,
1586 .help_msg = "Gdb",
1587 .action_msg = "GDB",
1588};
1589#endif
1590
1591static void kgdb_register_callbacks(void)
1592{
1593 if (!kgdb_io_module_registered) {
1594 kgdb_io_module_registered = 1;
1595 kgdb_arch_init();
1596#ifdef CONFIG_MAGIC_SYSRQ
1597 register_sysrq_key('g', &sysrq_gdb_op);
1598#endif
1599 if (kgdb_use_con && !kgdb_con_registered) {
1600 register_console(&kgdbcons);
1601 kgdb_con_registered = 1;
1602 }
1603 }
1604}
1605
1606static void kgdb_unregister_callbacks(void)
1607{
1608 /*
1609 * When this routine is called KGDB should unregister from the
1610 * panic handler and clean up, making sure it is not handling any
1611 * break exceptions at the time.
1612 */
1613 if (kgdb_io_module_registered) {
1614 kgdb_io_module_registered = 0;
1615 kgdb_arch_exit();
1616#ifdef CONFIG_MAGIC_SYSRQ
1617 unregister_sysrq_key('g', &sysrq_gdb_op);
1618#endif
1619 if (kgdb_con_registered) {
1620 unregister_console(&kgdbcons);
1621 kgdb_con_registered = 0;
1622 }
1623 }
1624}
1625
1626static void kgdb_initial_breakpoint(void)
1627{
1628 kgdb_break_asap = 0;
1629
1630 printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1631 kgdb_breakpoint();
1632}
1633
1634/**
Jason Wessel737a4602008-03-07 16:34:16 -06001635 * kgdb_register_io_module - register KGDB IO module
Jason Wesseldc7d5522008-04-17 20:05:37 +02001636 * @new_kgdb_io_ops: the io ops vector
1637 *
1638 * Register it with the KGDB core.
1639 */
1640int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1641{
1642 int err;
1643
1644 spin_lock(&kgdb_registration_lock);
1645
1646 if (kgdb_io_ops) {
1647 spin_unlock(&kgdb_registration_lock);
1648
1649 printk(KERN_ERR "kgdb: Another I/O driver is already "
1650 "registered with KGDB.\n");
1651 return -EBUSY;
1652 }
1653
1654 if (new_kgdb_io_ops->init) {
1655 err = new_kgdb_io_ops->init();
1656 if (err) {
1657 spin_unlock(&kgdb_registration_lock);
1658 return err;
1659 }
1660 }
1661
1662 kgdb_io_ops = new_kgdb_io_ops;
1663
1664 spin_unlock(&kgdb_registration_lock);
1665
1666 printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1667 new_kgdb_io_ops->name);
1668
1669 /* Arm KGDB now. */
1670 kgdb_register_callbacks();
1671
1672 if (kgdb_break_asap)
1673 kgdb_initial_breakpoint();
1674
1675 return 0;
1676}
1677EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1678
1679/**
1680 * kkgdb_unregister_io_module - unregister KGDB IO module
1681 * @old_kgdb_io_ops: the io ops vector
1682 *
1683 * Unregister it with the KGDB core.
1684 */
1685void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1686{
1687 BUG_ON(kgdb_connected);
1688
1689 /*
1690 * KGDB is no longer able to communicate out, so
1691 * unregister our callbacks and reset state.
1692 */
1693 kgdb_unregister_callbacks();
1694
1695 spin_lock(&kgdb_registration_lock);
1696
1697 WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1698 kgdb_io_ops = NULL;
1699
1700 spin_unlock(&kgdb_registration_lock);
1701
1702 printk(KERN_INFO
1703 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1704 old_kgdb_io_ops->name);
1705}
1706EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1707
1708/**
1709 * kgdb_breakpoint - generate breakpoint exception
1710 *
1711 * This function will generate a breakpoint exception. It is used at the
1712 * beginning of a program to sync up with a debugger and can be used
1713 * otherwise as a quick means to stop program execution and "break" into
1714 * the debugger.
1715 */
1716void kgdb_breakpoint(void)
1717{
1718 atomic_set(&kgdb_setting_breakpoint, 1);
1719 wmb(); /* Sync point before breakpoint */
1720 arch_kgdb_breakpoint();
1721 wmb(); /* Sync point after breakpoint */
1722 atomic_set(&kgdb_setting_breakpoint, 0);
1723}
1724EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1725
1726static int __init opt_kgdb_wait(char *str)
1727{
1728 kgdb_break_asap = 1;
1729
1730 if (kgdb_io_module_registered)
1731 kgdb_initial_breakpoint();
1732
1733 return 0;
1734}
1735
1736early_param("kgdbwait", opt_kgdb_wait);