kgdb: Read buffer overflow
[linux-2.6.git] / kernel / kgdb.c
1 /*
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>
31 #include <linux/clocksource.h>
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>
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>
55 #include <asm/unaligned.h>
56
57 static int kgdb_break_asap;
58
59 #define KGDB_MAX_THREAD_QUERY 17
60 struct kgdb_state {
61         int                     ex_vector;
62         int                     signo;
63         int                     err_code;
64         int                     cpu;
65         int                     pass_exception;
66         unsigned long           thr_query;
67         unsigned long           threadid;
68         long                    kgdb_usethreadid;
69         struct pt_regs          *linux_regs;
70 };
71
72 static 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  */
80 int                             kgdb_connected;
81 EXPORT_SYMBOL_GPL(kgdb_connected);
82
83 /* All the KGDB handlers are installed */
84 static int                      kgdb_io_module_registered;
85
86 /* Guard for recursive entry */
87 static int                      exception_level;
88
89 static struct kgdb_io           *kgdb_io_ops;
90 static DEFINE_SPINLOCK(kgdb_registration_lock);
91
92 /* kgdb console driver is loaded */
93 static int kgdb_con_registered;
94 /* determine if kgdb console output should be used */
95 static int kgdb_use_con;
96
97 static int __init opt_kgdb_con(char *str)
98 {
99         kgdb_use_con = 1;
100         return 0;
101 }
102
103 early_param("kgdbcon", opt_kgdb_con);
104
105 module_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  */
111 static 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  */
118 atomic_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  */
124 static atomic_t                 passive_cpu_wait[NR_CPUS];
125 static atomic_t                 cpu_in_kgdb[NR_CPUS];
126 atomic_t                        kgdb_setting_breakpoint;
127
128 struct task_struct              *kgdb_usethread;
129 struct task_struct              *kgdb_contthread;
130
131 int                             kgdb_single_step;
132
133 /* Our I/O buffers. */
134 static char                     remcom_in_buffer[BUFMAX];
135 static char                     remcom_out_buffer[BUFMAX];
136
137 /* Storage for the registers, in GDB format. */
138 static 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*/
143 atomic_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  */
152 static int kgdb_do_roundup = 1;
153
154 static int __init opt_nokgdbroundup(char *str)
155 {
156         kgdb_do_roundup = 0;
157
158         return 0;
159 }
160
161 early_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  */
171 int __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
183 int __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
189 int __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
208 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
209 {
210         return instruction_pointer(regs);
211 }
212
213 int __weak kgdb_arch_init(void)
214 {
215         return 0;
216 }
217
218 int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
219 {
220         return 0;
221 }
222
223 void __weak
224 kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
225 {
226         return;
227 }
228
229 /**
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  */
237 void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
238 {
239 }
240
241 /*
242  * GDB remote protocol parser:
243  */
244
245 static 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 $<data>#<checksum> */
257 static void get_packet(char *buffer)
258 {
259         unsigned char checksum;
260         unsigned char xmitcsum;
261         int count;
262         char ch;
263
264         do {
265                 /*
266                  * Spin and wait around for the start character, ignore all
267                  * other characters:
268                  */
269                 while ((ch = (kgdb_io_ops->read_char())) != '$')
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  */
311 static 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('#');
332                 kgdb_io_ops->write_char(hex_asc_hi(checksum));
333                 kgdb_io_ops->write_char(hex_asc_lo(checksum));
334                 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
362 /*
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  */
366 int 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  */
396 static 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  */
421 int 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  */
446 int kgdb_hex2long(char **ptr, unsigned long *long_val)
447 {
448         int hex_val;
449         int num = 0;
450         int negate = 0;
451
452         *long_val = 0;
453
454         if (**ptr == '-') {
455                 negate = 1;
456                 (*ptr)++;
457         }
458         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
468         if (negate)
469                 *long_val = -*long_val;
470
471         return num;
472 }
473
474 /* Write memory due to an 'M' or 'X' packet. */
475 static 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)
491                         flush_icache_range(addr, addr + length);
492                 return 0;
493         }
494
495         return -EINVAL;
496 }
497
498 static void error_packet(char *pkt, int error)
499 {
500         error = -error;
501         pkt[0] = 'E';
502         pkt[1] = hex_asc[(error / 10)];
503         pkt[2] = hex_asc[(error % 10)];
504         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
515 static 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
526 static 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;
534         put_unaligned_be32(value, scan);
535 }
536
537 static struct task_struct *getthread(struct pt_regs *regs, int tid)
538 {
539         /*
540          * Non-positive TIDs are remapped to the cpu shadow information
541          */
542         if (tid == 0 || tid == -1)
543                 tid = -atomic_read(&kgdb_active) - 2;
544         if (tid < -1 && tid > -NR_CPUS - 2) {
545                 if (kgdb_info[-tid - 2].task)
546                         return kgdb_info[-tid - 2].task;
547                 else
548                         return idle_task(-tid - 2);
549         }
550         if (tid <= 0) {
551                 printk(KERN_ERR "KGDB: Internal thread select error\n");
552                 dump_stack();
553                 return NULL;
554         }
555
556         /*
557          * find_task_by_pid_ns() does not take the tasklist lock anymore
558          * but is nicely RCU locked - hence is a pretty resilient
559          * thing to use:
560          */
561         return find_task_by_pid_ns(tid, &init_pid_ns);
562 }
563
564 /*
565  * CPU debug state control:
566  */
567
568 #ifdef CONFIG_SMP
569 static void kgdb_wait(struct pt_regs *regs)
570 {
571         unsigned long flags;
572         int cpu;
573
574         local_irq_save(flags);
575         cpu = raw_smp_processor_id();
576         kgdb_info[cpu].debuggerinfo = regs;
577         kgdb_info[cpu].task = current;
578         /*
579          * Make sure the above info reaches the primary CPU before
580          * our cpu_in_kgdb[] flag setting does:
581          */
582         smp_wmb();
583         atomic_set(&cpu_in_kgdb[cpu], 1);
584
585         /* Wait till primary CPU is done with debugging */
586         while (atomic_read(&passive_cpu_wait[cpu]))
587                 cpu_relax();
588
589         kgdb_info[cpu].debuggerinfo = NULL;
590         kgdb_info[cpu].task = NULL;
591
592         /* fix up hardware debug registers on local cpu */
593         if (arch_kgdb_ops.correct_hw_break)
594                 arch_kgdb_ops.correct_hw_break();
595
596         /* Signal the primary CPU that we are done: */
597         atomic_set(&cpu_in_kgdb[cpu], 0);
598         touch_softlockup_watchdog();
599         clocksource_touch_watchdog();
600         local_irq_restore(flags);
601 }
602 #endif
603
604 /*
605  * Some architectures need cache flushes when we set/clear a
606  * breakpoint:
607  */
608 static void kgdb_flush_swbreak_addr(unsigned long addr)
609 {
610         if (!CACHE_FLUSH_IS_SAFE)
611                 return;
612
613         if (current->mm && current->mm->mmap_cache) {
614                 flush_cache_range(current->mm->mmap_cache,
615                                   addr, addr + BREAK_INSTR_SIZE);
616         }
617         /* Force flush instruction cache if it was outside the mm */
618         flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
619 }
620
621 /*
622  * SW breakpoint management:
623  */
624 static int kgdb_activate_sw_breakpoints(void)
625 {
626         unsigned long addr;
627         int error = 0;
628         int i;
629
630         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
631                 if (kgdb_break[i].state != BP_SET)
632                         continue;
633
634                 addr = kgdb_break[i].bpt_addr;
635                 error = kgdb_arch_set_breakpoint(addr,
636                                 kgdb_break[i].saved_instr);
637                 if (error)
638                         return error;
639
640                 kgdb_flush_swbreak_addr(addr);
641                 kgdb_break[i].state = BP_ACTIVE;
642         }
643         return 0;
644 }
645
646 static int kgdb_set_sw_break(unsigned long addr)
647 {
648         int err = kgdb_validate_break_address(addr);
649         int breakno = -1;
650         int i;
651
652         if (err)
653                 return err;
654
655         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
656                 if ((kgdb_break[i].state == BP_SET) &&
657                                         (kgdb_break[i].bpt_addr == addr))
658                         return -EEXIST;
659         }
660         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
661                 if (kgdb_break[i].state == BP_REMOVED &&
662                                         kgdb_break[i].bpt_addr == addr) {
663                         breakno = i;
664                         break;
665                 }
666         }
667
668         if (breakno == -1) {
669                 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
670                         if (kgdb_break[i].state == BP_UNDEFINED) {
671                                 breakno = i;
672                                 break;
673                         }
674                 }
675         }
676
677         if (breakno == -1)
678                 return -E2BIG;
679
680         kgdb_break[breakno].state = BP_SET;
681         kgdb_break[breakno].type = BP_BREAKPOINT;
682         kgdb_break[breakno].bpt_addr = addr;
683
684         return 0;
685 }
686
687 static int kgdb_deactivate_sw_breakpoints(void)
688 {
689         unsigned long addr;
690         int error = 0;
691         int i;
692
693         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
694                 if (kgdb_break[i].state != BP_ACTIVE)
695                         continue;
696                 addr = kgdb_break[i].bpt_addr;
697                 error = kgdb_arch_remove_breakpoint(addr,
698                                         kgdb_break[i].saved_instr);
699                 if (error)
700                         return error;
701
702                 kgdb_flush_swbreak_addr(addr);
703                 kgdb_break[i].state = BP_SET;
704         }
705         return 0;
706 }
707
708 static int kgdb_remove_sw_break(unsigned long addr)
709 {
710         int i;
711
712         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
713                 if ((kgdb_break[i].state == BP_SET) &&
714                                 (kgdb_break[i].bpt_addr == addr)) {
715                         kgdb_break[i].state = BP_REMOVED;
716                         return 0;
717                 }
718         }
719         return -ENOENT;
720 }
721
722 int kgdb_isremovedbreak(unsigned long addr)
723 {
724         int i;
725
726         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
727                 if ((kgdb_break[i].state == BP_REMOVED) &&
728                                         (kgdb_break[i].bpt_addr == addr))
729                         return 1;
730         }
731         return 0;
732 }
733
734 static int remove_all_break(void)
735 {
736         unsigned long addr;
737         int error;
738         int i;
739
740         /* Clear memory breakpoints. */
741         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
742                 if (kgdb_break[i].state != BP_ACTIVE)
743                         goto setundefined;
744                 addr = kgdb_break[i].bpt_addr;
745                 error = kgdb_arch_remove_breakpoint(addr,
746                                 kgdb_break[i].saved_instr);
747                 if (error)
748                         printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
749                            addr);
750 setundefined:
751                 kgdb_break[i].state = BP_UNDEFINED;
752         }
753
754         /* Clear hardware breakpoints. */
755         if (arch_kgdb_ops.remove_all_hw_break)
756                 arch_kgdb_ops.remove_all_hw_break();
757
758         return 0;
759 }
760
761 /*
762  * Remap normal tasks to their real PID,
763  * CPU shadow threads are mapped to -CPU - 2
764  */
765 static inline int shadow_pid(int realpid)
766 {
767         if (realpid)
768                 return realpid;
769
770         return -raw_smp_processor_id() - 2;
771 }
772
773 static char gdbmsgbuf[BUFMAX + 1];
774
775 static void kgdb_msg_write(const char *s, int len)
776 {
777         char *bufptr;
778         int wcount;
779         int i;
780
781         /* 'O'utput */
782         gdbmsgbuf[0] = 'O';
783
784         /* Fill and send buffers... */
785         while (len > 0) {
786                 bufptr = gdbmsgbuf + 1;
787
788                 /* Calculate how many this time */
789                 if ((len << 1) > (BUFMAX - 2))
790                         wcount = (BUFMAX - 2) >> 1;
791                 else
792                         wcount = len;
793
794                 /* Pack in hex chars */
795                 for (i = 0; i < wcount; i++)
796                         bufptr = pack_hex_byte(bufptr, s[i]);
797                 *bufptr = '\0';
798
799                 /* Move up */
800                 s += wcount;
801                 len -= wcount;
802
803                 /* Write packet */
804                 put_packet(gdbmsgbuf);
805         }
806 }
807
808 /*
809  * Return true if there is a valid kgdb I/O module.  Also if no
810  * debugger is attached a message can be printed to the console about
811  * waiting for the debugger to attach.
812  *
813  * The print_wait argument is only to be true when called from inside
814  * the core kgdb_handle_exception, because it will wait for the
815  * debugger to attach.
816  */
817 static int kgdb_io_ready(int print_wait)
818 {
819         if (!kgdb_io_ops)
820                 return 0;
821         if (kgdb_connected)
822                 return 1;
823         if (atomic_read(&kgdb_setting_breakpoint))
824                 return 1;
825         if (print_wait)
826                 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
827         return 1;
828 }
829
830 /*
831  * All the functions that start with gdb_cmd are the various
832  * operations to implement the handlers for the gdbserial protocol
833  * where KGDB is communicating with an external debugger
834  */
835
836 /* Handle the '?' status packets */
837 static void gdb_cmd_status(struct kgdb_state *ks)
838 {
839         /*
840          * We know that this packet is only sent
841          * during initial connect.  So to be safe,
842          * we clear out our breakpoints now in case
843          * GDB is reconnecting.
844          */
845         remove_all_break();
846
847         remcom_out_buffer[0] = 'S';
848         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
849 }
850
851 /* Handle the 'g' get registers request */
852 static void gdb_cmd_getregs(struct kgdb_state *ks)
853 {
854         struct task_struct *thread;
855         void *local_debuggerinfo;
856         int i;
857
858         thread = kgdb_usethread;
859         if (!thread) {
860                 thread = kgdb_info[ks->cpu].task;
861                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
862         } else {
863                 local_debuggerinfo = NULL;
864                 for_each_online_cpu(i) {
865                         /*
866                          * Try to find the task on some other
867                          * or possibly this node if we do not
868                          * find the matching task then we try
869                          * to approximate the results.
870                          */
871                         if (thread == kgdb_info[i].task)
872                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
873                 }
874         }
875
876         /*
877          * All threads that don't have debuggerinfo should be
878          * in schedule() sleeping, since all other CPUs
879          * are in kgdb_wait, and thus have debuggerinfo.
880          */
881         if (local_debuggerinfo) {
882                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
883         } else {
884                 /*
885                  * Pull stuff saved during switch_to; nothing
886                  * else is accessible (or even particularly
887                  * relevant).
888                  *
889                  * This should be enough for a stack trace.
890                  */
891                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
892         }
893         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
894 }
895
896 /* Handle the 'G' set registers request */
897 static void gdb_cmd_setregs(struct kgdb_state *ks)
898 {
899         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
900
901         if (kgdb_usethread && kgdb_usethread != current) {
902                 error_packet(remcom_out_buffer, -EINVAL);
903         } else {
904                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
905                 strcpy(remcom_out_buffer, "OK");
906         }
907 }
908
909 /* Handle the 'm' memory read bytes */
910 static void gdb_cmd_memread(struct kgdb_state *ks)
911 {
912         char *ptr = &remcom_in_buffer[1];
913         unsigned long length;
914         unsigned long addr;
915         int err;
916
917         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
918                                         kgdb_hex2long(&ptr, &length) > 0) {
919                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
920                 if (err)
921                         error_packet(remcom_out_buffer, err);
922         } else {
923                 error_packet(remcom_out_buffer, -EINVAL);
924         }
925 }
926
927 /* Handle the 'M' memory write bytes */
928 static void gdb_cmd_memwrite(struct kgdb_state *ks)
929 {
930         int err = write_mem_msg(0);
931
932         if (err)
933                 error_packet(remcom_out_buffer, err);
934         else
935                 strcpy(remcom_out_buffer, "OK");
936 }
937
938 /* Handle the 'X' memory binary write bytes */
939 static void gdb_cmd_binwrite(struct kgdb_state *ks)
940 {
941         int err = write_mem_msg(1);
942
943         if (err)
944                 error_packet(remcom_out_buffer, err);
945         else
946                 strcpy(remcom_out_buffer, "OK");
947 }
948
949 /* Handle the 'D' or 'k', detach or kill packets */
950 static void gdb_cmd_detachkill(struct kgdb_state *ks)
951 {
952         int error;
953
954         /* The detach case */
955         if (remcom_in_buffer[0] == 'D') {
956                 error = remove_all_break();
957                 if (error < 0) {
958                         error_packet(remcom_out_buffer, error);
959                 } else {
960                         strcpy(remcom_out_buffer, "OK");
961                         kgdb_connected = 0;
962                 }
963                 put_packet(remcom_out_buffer);
964         } else {
965                 /*
966                  * Assume the kill case, with no exit code checking,
967                  * trying to force detach the debugger:
968                  */
969                 remove_all_break();
970                 kgdb_connected = 0;
971         }
972 }
973
974 /* Handle the 'R' reboot packets */
975 static int gdb_cmd_reboot(struct kgdb_state *ks)
976 {
977         /* For now, only honor R0 */
978         if (strcmp(remcom_in_buffer, "R0") == 0) {
979                 printk(KERN_CRIT "Executing emergency reboot\n");
980                 strcpy(remcom_out_buffer, "OK");
981                 put_packet(remcom_out_buffer);
982
983                 /*
984                  * Execution should not return from
985                  * machine_emergency_restart()
986                  */
987                 machine_emergency_restart();
988                 kgdb_connected = 0;
989
990                 return 1;
991         }
992         return 0;
993 }
994
995 /* Handle the 'q' query packets */
996 static void gdb_cmd_query(struct kgdb_state *ks)
997 {
998         struct task_struct *g;
999         struct task_struct *p;
1000         unsigned char thref[8];
1001         char *ptr;
1002         int i;
1003         int cpu;
1004         int finished = 0;
1005
1006         switch (remcom_in_buffer[1]) {
1007         case 's':
1008         case 'f':
1009                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
1010                         error_packet(remcom_out_buffer, -EINVAL);
1011                         break;
1012                 }
1013
1014                 i = 0;
1015                 remcom_out_buffer[0] = 'm';
1016                 ptr = remcom_out_buffer + 1;
1017                 if (remcom_in_buffer[1] == 'f') {
1018                         /* Each cpu is a shadow thread */
1019                         for_each_online_cpu(cpu) {
1020                                 ks->thr_query = 0;
1021                                 int_to_threadref(thref, -cpu - 2);
1022                                 pack_threadid(ptr, thref);
1023                                 ptr += BUF_THREAD_ID_SIZE;
1024                                 *(ptr++) = ',';
1025                                 i++;
1026                         }
1027                 }
1028
1029                 do_each_thread(g, p) {
1030                         if (i >= ks->thr_query && !finished) {
1031                                 int_to_threadref(thref, p->pid);
1032                                 pack_threadid(ptr, thref);
1033                                 ptr += BUF_THREAD_ID_SIZE;
1034                                 *(ptr++) = ',';
1035                                 ks->thr_query++;
1036                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
1037                                         finished = 1;
1038                         }
1039                         i++;
1040                 } while_each_thread(g, p);
1041
1042                 *(--ptr) = '\0';
1043                 break;
1044
1045         case 'C':
1046                 /* Current thread id */
1047                 strcpy(remcom_out_buffer, "QC");
1048                 ks->threadid = shadow_pid(current->pid);
1049                 int_to_threadref(thref, ks->threadid);
1050                 pack_threadid(remcom_out_buffer + 2, thref);
1051                 break;
1052         case 'T':
1053                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1054                         error_packet(remcom_out_buffer, -EINVAL);
1055                         break;
1056                 }
1057                 ks->threadid = 0;
1058                 ptr = remcom_in_buffer + 17;
1059                 kgdb_hex2long(&ptr, &ks->threadid);
1060                 if (!getthread(ks->linux_regs, ks->threadid)) {
1061                         error_packet(remcom_out_buffer, -EINVAL);
1062                         break;
1063                 }
1064                 if ((int)ks->threadid > 0) {
1065                         kgdb_mem2hex(getthread(ks->linux_regs,
1066                                         ks->threadid)->comm,
1067                                         remcom_out_buffer, 16);
1068                 } else {
1069                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1070
1071                         sprintf(tmpstr, "shadowCPU%d",
1072                                         (int)(-ks->threadid - 2));
1073                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1074                 }
1075                 break;
1076         }
1077 }
1078
1079 /* Handle the 'H' task query packets */
1080 static void gdb_cmd_task(struct kgdb_state *ks)
1081 {
1082         struct task_struct *thread;
1083         char *ptr;
1084
1085         switch (remcom_in_buffer[1]) {
1086         case 'g':
1087                 ptr = &remcom_in_buffer[2];
1088                 kgdb_hex2long(&ptr, &ks->threadid);
1089                 thread = getthread(ks->linux_regs, ks->threadid);
1090                 if (!thread && ks->threadid > 0) {
1091                         error_packet(remcom_out_buffer, -EINVAL);
1092                         break;
1093                 }
1094                 kgdb_usethread = thread;
1095                 ks->kgdb_usethreadid = ks->threadid;
1096                 strcpy(remcom_out_buffer, "OK");
1097                 break;
1098         case 'c':
1099                 ptr = &remcom_in_buffer[2];
1100                 kgdb_hex2long(&ptr, &ks->threadid);
1101                 if (!ks->threadid) {
1102                         kgdb_contthread = NULL;
1103                 } else {
1104                         thread = getthread(ks->linux_regs, ks->threadid);
1105                         if (!thread && ks->threadid > 0) {
1106                                 error_packet(remcom_out_buffer, -EINVAL);
1107                                 break;
1108                         }
1109                         kgdb_contthread = thread;
1110                 }
1111                 strcpy(remcom_out_buffer, "OK");
1112                 break;
1113         }
1114 }
1115
1116 /* Handle the 'T' thread query packets */
1117 static void gdb_cmd_thread(struct kgdb_state *ks)
1118 {
1119         char *ptr = &remcom_in_buffer[1];
1120         struct task_struct *thread;
1121
1122         kgdb_hex2long(&ptr, &ks->threadid);
1123         thread = getthread(ks->linux_regs, ks->threadid);
1124         if (thread)
1125                 strcpy(remcom_out_buffer, "OK");
1126         else
1127                 error_packet(remcom_out_buffer, -EINVAL);
1128 }
1129
1130 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
1131 static void gdb_cmd_break(struct kgdb_state *ks)
1132 {
1133         /*
1134          * Since GDB-5.3, it's been drafted that '0' is a software
1135          * breakpoint, '1' is a hardware breakpoint, so let's do that.
1136          */
1137         char *bpt_type = &remcom_in_buffer[1];
1138         char *ptr = &remcom_in_buffer[2];
1139         unsigned long addr;
1140         unsigned long length;
1141         int error = 0;
1142
1143         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1144                 /* Unsupported */
1145                 if (*bpt_type > '4')
1146                         return;
1147         } else {
1148                 if (*bpt_type != '0' && *bpt_type != '1')
1149                         /* Unsupported. */
1150                         return;
1151         }
1152
1153         /*
1154          * Test if this is a hardware breakpoint, and
1155          * if we support it:
1156          */
1157         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1158                 /* Unsupported. */
1159                 return;
1160
1161         if (*(ptr++) != ',') {
1162                 error_packet(remcom_out_buffer, -EINVAL);
1163                 return;
1164         }
1165         if (!kgdb_hex2long(&ptr, &addr)) {
1166                 error_packet(remcom_out_buffer, -EINVAL);
1167                 return;
1168         }
1169         if (*(ptr++) != ',' ||
1170                 !kgdb_hex2long(&ptr, &length)) {
1171                 error_packet(remcom_out_buffer, -EINVAL);
1172                 return;
1173         }
1174
1175         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1176                 error = kgdb_set_sw_break(addr);
1177         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1178                 error = kgdb_remove_sw_break(addr);
1179         else if (remcom_in_buffer[0] == 'Z')
1180                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
1181                         (int)length, *bpt_type - '0');
1182         else if (remcom_in_buffer[0] == 'z')
1183                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1184                         (int) length, *bpt_type - '0');
1185
1186         if (error == 0)
1187                 strcpy(remcom_out_buffer, "OK");
1188         else
1189                 error_packet(remcom_out_buffer, error);
1190 }
1191
1192 /* Handle the 'C' signal / exception passing packets */
1193 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1194 {
1195         /* C09 == pass exception
1196          * C15 == detach kgdb, pass exception
1197          */
1198         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1199
1200                 ks->pass_exception = 1;
1201                 remcom_in_buffer[0] = 'c';
1202
1203         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1204
1205                 ks->pass_exception = 1;
1206                 remcom_in_buffer[0] = 'D';
1207                 remove_all_break();
1208                 kgdb_connected = 0;
1209                 return 1;
1210
1211         } else {
1212                 error_packet(remcom_out_buffer, -EINVAL);
1213                 return 0;
1214         }
1215
1216         /* Indicate fall through */
1217         return -1;
1218 }
1219
1220 /*
1221  * This function performs all gdbserial command procesing
1222  */
1223 static int gdb_serial_stub(struct kgdb_state *ks)
1224 {
1225         int error = 0;
1226         int tmp;
1227
1228         /* Clear the out buffer. */
1229         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1230
1231         if (kgdb_connected) {
1232                 unsigned char thref[8];
1233                 char *ptr;
1234
1235                 /* Reply to host that an exception has occurred */
1236                 ptr = remcom_out_buffer;
1237                 *ptr++ = 'T';
1238                 ptr = pack_hex_byte(ptr, ks->signo);
1239                 ptr += strlen(strcpy(ptr, "thread:"));
1240                 int_to_threadref(thref, shadow_pid(current->pid));
1241                 ptr = pack_threadid(ptr, thref);
1242                 *ptr++ = ';';
1243                 put_packet(remcom_out_buffer);
1244         }
1245
1246         kgdb_usethread = kgdb_info[ks->cpu].task;
1247         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1248         ks->pass_exception = 0;
1249
1250         while (1) {
1251                 error = 0;
1252
1253                 /* Clear the out buffer. */
1254                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1255
1256                 get_packet(remcom_in_buffer);
1257
1258                 switch (remcom_in_buffer[0]) {
1259                 case '?': /* gdbserial status */
1260                         gdb_cmd_status(ks);
1261                         break;
1262                 case 'g': /* return the value of the CPU registers */
1263                         gdb_cmd_getregs(ks);
1264                         break;
1265                 case 'G': /* set the value of the CPU registers - return OK */
1266                         gdb_cmd_setregs(ks);
1267                         break;
1268                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
1269                         gdb_cmd_memread(ks);
1270                         break;
1271                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1272                         gdb_cmd_memwrite(ks);
1273                         break;
1274                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1275                         gdb_cmd_binwrite(ks);
1276                         break;
1277                         /* kill or detach. KGDB should treat this like a
1278                          * continue.
1279                          */
1280                 case 'D': /* Debugger detach */
1281                 case 'k': /* Debugger detach via kill */
1282                         gdb_cmd_detachkill(ks);
1283                         goto default_handle;
1284                 case 'R': /* Reboot */
1285                         if (gdb_cmd_reboot(ks))
1286                                 goto default_handle;
1287                         break;
1288                 case 'q': /* query command */
1289                         gdb_cmd_query(ks);
1290                         break;
1291                 case 'H': /* task related */
1292                         gdb_cmd_task(ks);
1293                         break;
1294                 case 'T': /* Query thread status */
1295                         gdb_cmd_thread(ks);
1296                         break;
1297                 case 'z': /* Break point remove */
1298                 case 'Z': /* Break point set */
1299                         gdb_cmd_break(ks);
1300                         break;
1301                 case 'C': /* Exception passing */
1302                         tmp = gdb_cmd_exception_pass(ks);
1303                         if (tmp > 0)
1304                                 goto default_handle;
1305                         if (tmp == 0)
1306                                 break;
1307                         /* Fall through on tmp < 0 */
1308                 case 'c': /* Continue packet */
1309                 case 's': /* Single step packet */
1310                         if (kgdb_contthread && kgdb_contthread != current) {
1311                                 /* Can't switch threads in kgdb */
1312                                 error_packet(remcom_out_buffer, -EINVAL);
1313                                 break;
1314                         }
1315                         kgdb_activate_sw_breakpoints();
1316                         /* Fall through to default processing */
1317                 default:
1318 default_handle:
1319                         error = kgdb_arch_handle_exception(ks->ex_vector,
1320                                                 ks->signo,
1321                                                 ks->err_code,
1322                                                 remcom_in_buffer,
1323                                                 remcom_out_buffer,
1324                                                 ks->linux_regs);
1325                         /*
1326                          * Leave cmd processing on error, detach,
1327                          * kill, continue, or single step.
1328                          */
1329                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1330                             remcom_in_buffer[0] == 'k') {
1331                                 error = 0;
1332                                 goto kgdb_exit;
1333                         }
1334
1335                 }
1336
1337                 /* reply to the request */
1338                 put_packet(remcom_out_buffer);
1339         }
1340
1341 kgdb_exit:
1342         if (ks->pass_exception)
1343                 error = 1;
1344         return error;
1345 }
1346
1347 static int kgdb_reenter_check(struct kgdb_state *ks)
1348 {
1349         unsigned long addr;
1350
1351         if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1352                 return 0;
1353
1354         /* Panic on recursive debugger calls: */
1355         exception_level++;
1356         addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1357         kgdb_deactivate_sw_breakpoints();
1358
1359         /*
1360          * If the break point removed ok at the place exception
1361          * occurred, try to recover and print a warning to the end
1362          * user because the user planted a breakpoint in a place that
1363          * KGDB needs in order to function.
1364          */
1365         if (kgdb_remove_sw_break(addr) == 0) {
1366                 exception_level = 0;
1367                 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1368                 kgdb_activate_sw_breakpoints();
1369                 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1370                         addr);
1371                 WARN_ON_ONCE(1);
1372
1373                 return 1;
1374         }
1375         remove_all_break();
1376         kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1377
1378         if (exception_level > 1) {
1379                 dump_stack();
1380                 panic("Recursive entry to debugger");
1381         }
1382
1383         printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1384         dump_stack();
1385         panic("Recursive entry to debugger");
1386
1387         return 1;
1388 }
1389
1390 /*
1391  * kgdb_handle_exception() - main entry point from a kernel exception
1392  *
1393  * Locking hierarchy:
1394  *      interface locks, if any (begin_session)
1395  *      kgdb lock (kgdb_active)
1396  */
1397 int
1398 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1399 {
1400         struct kgdb_state kgdb_var;
1401         struct kgdb_state *ks = &kgdb_var;
1402         unsigned long flags;
1403         int error = 0;
1404         int i, cpu;
1405
1406         ks->cpu                 = raw_smp_processor_id();
1407         ks->ex_vector           = evector;
1408         ks->signo               = signo;
1409         ks->ex_vector           = evector;
1410         ks->err_code            = ecode;
1411         ks->kgdb_usethreadid    = 0;
1412         ks->linux_regs          = regs;
1413
1414         if (kgdb_reenter_check(ks))
1415                 return 0; /* Ouch, double exception ! */
1416
1417 acquirelock:
1418         /*
1419          * Interrupts will be restored by the 'trap return' code, except when
1420          * single stepping.
1421          */
1422         local_irq_save(flags);
1423
1424         cpu = raw_smp_processor_id();
1425
1426         /*
1427          * Acquire the kgdb_active lock:
1428          */
1429         while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
1430                 cpu_relax();
1431
1432         /*
1433          * Do not start the debugger connection on this CPU if the last
1434          * instance of the exception handler wanted to come into the
1435          * debugger on a different CPU via a single step
1436          */
1437         if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1438             atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
1439
1440                 atomic_set(&kgdb_active, -1);
1441                 touch_softlockup_watchdog();
1442                 clocksource_touch_watchdog();
1443                 local_irq_restore(flags);
1444
1445                 goto acquirelock;
1446         }
1447
1448         if (!kgdb_io_ready(1)) {
1449                 error = 1;
1450                 goto kgdb_restore; /* No I/O connection, so resume the system */
1451         }
1452
1453         /*
1454          * Don't enter if we have hit a removed breakpoint.
1455          */
1456         if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1457                 goto kgdb_restore;
1458
1459         /* Call the I/O driver's pre_exception routine */
1460         if (kgdb_io_ops->pre_exception)
1461                 kgdb_io_ops->pre_exception();
1462
1463         kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
1464         kgdb_info[ks->cpu].task = current;
1465
1466         kgdb_disable_hw_debug(ks->linux_regs);
1467
1468         /*
1469          * Get the passive CPU lock which will hold all the non-primary
1470          * CPU in a spin state while the debugger is active
1471          */
1472         if (!kgdb_single_step) {
1473                 for (i = 0; i < NR_CPUS; i++)
1474                         atomic_set(&passive_cpu_wait[i], 1);
1475         }
1476
1477         /*
1478          * spin_lock code is good enough as a barrier so we don't
1479          * need one here:
1480          */
1481         atomic_set(&cpu_in_kgdb[ks->cpu], 1);
1482
1483 #ifdef CONFIG_SMP
1484         /* Signal the other CPUs to enter kgdb_wait() */
1485         if ((!kgdb_single_step) && kgdb_do_roundup)
1486                 kgdb_roundup_cpus(flags);
1487 #endif
1488
1489         /*
1490          * Wait for the other CPUs to be notified and be waiting for us:
1491          */
1492         for_each_online_cpu(i) {
1493                 while (!atomic_read(&cpu_in_kgdb[i]))
1494                         cpu_relax();
1495         }
1496
1497         /*
1498          * At this point the primary processor is completely
1499          * in the debugger and all secondary CPUs are quiescent
1500          */
1501         kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1502         kgdb_deactivate_sw_breakpoints();
1503         kgdb_single_step = 0;
1504         kgdb_contthread = current;
1505         exception_level = 0;
1506
1507         /* Talk to debugger with gdbserial protocol */
1508         error = gdb_serial_stub(ks);
1509
1510         /* Call the I/O driver's post_exception routine */
1511         if (kgdb_io_ops->post_exception)
1512                 kgdb_io_ops->post_exception();
1513
1514         kgdb_info[ks->cpu].debuggerinfo = NULL;
1515         kgdb_info[ks->cpu].task = NULL;
1516         atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1517
1518         if (!kgdb_single_step) {
1519                 for (i = NR_CPUS-1; i >= 0; i--)
1520                         atomic_set(&passive_cpu_wait[i], 0);
1521                 /*
1522                  * Wait till all the CPUs have quit
1523                  * from the debugger.
1524                  */
1525                 for_each_online_cpu(i) {
1526                         while (atomic_read(&cpu_in_kgdb[i]))
1527                                 cpu_relax();
1528                 }
1529         }
1530
1531 kgdb_restore:
1532         /* Free kgdb_active */
1533         atomic_set(&kgdb_active, -1);
1534         touch_softlockup_watchdog();
1535         clocksource_touch_watchdog();
1536         local_irq_restore(flags);
1537
1538         return error;
1539 }
1540
1541 int kgdb_nmicallback(int cpu, void *regs)
1542 {
1543 #ifdef CONFIG_SMP
1544         if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1545                         atomic_read(&kgdb_active) != cpu &&
1546                         atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
1547                 kgdb_wait((struct pt_regs *)regs);
1548                 return 0;
1549         }
1550 #endif
1551         return 1;
1552 }
1553
1554 static void kgdb_console_write(struct console *co, const char *s,
1555    unsigned count)
1556 {
1557         unsigned long flags;
1558
1559         /* If we're debugging, or KGDB has not connected, don't try
1560          * and print. */
1561         if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
1562                 return;
1563
1564         local_irq_save(flags);
1565         kgdb_msg_write(s, count);
1566         local_irq_restore(flags);
1567 }
1568
1569 static struct console kgdbcons = {
1570         .name           = "kgdb",
1571         .write          = kgdb_console_write,
1572         .flags          = CON_PRINTBUFFER | CON_ENABLED,
1573         .index          = -1,
1574 };
1575
1576 #ifdef CONFIG_MAGIC_SYSRQ
1577 static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1578 {
1579         if (!kgdb_io_ops) {
1580                 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1581                 return;
1582         }
1583         if (!kgdb_connected)
1584                 printk(KERN_CRIT "Entering KGDB\n");
1585
1586         kgdb_breakpoint();
1587 }
1588
1589 static struct sysrq_key_op sysrq_gdb_op = {
1590         .handler        = sysrq_handle_gdb,
1591         .help_msg       = "debug(G)",
1592         .action_msg     = "DEBUG",
1593 };
1594 #endif
1595
1596 static void kgdb_register_callbacks(void)
1597 {
1598         if (!kgdb_io_module_registered) {
1599                 kgdb_io_module_registered = 1;
1600                 kgdb_arch_init();
1601 #ifdef CONFIG_MAGIC_SYSRQ
1602                 register_sysrq_key('g', &sysrq_gdb_op);
1603 #endif
1604                 if (kgdb_use_con && !kgdb_con_registered) {
1605                         register_console(&kgdbcons);
1606                         kgdb_con_registered = 1;
1607                 }
1608         }
1609 }
1610
1611 static void kgdb_unregister_callbacks(void)
1612 {
1613         /*
1614          * When this routine is called KGDB should unregister from the
1615          * panic handler and clean up, making sure it is not handling any
1616          * break exceptions at the time.
1617          */
1618         if (kgdb_io_module_registered) {
1619                 kgdb_io_module_registered = 0;
1620                 kgdb_arch_exit();
1621 #ifdef CONFIG_MAGIC_SYSRQ
1622                 unregister_sysrq_key('g', &sysrq_gdb_op);
1623 #endif
1624                 if (kgdb_con_registered) {
1625                         unregister_console(&kgdbcons);
1626                         kgdb_con_registered = 0;
1627                 }
1628         }
1629 }
1630
1631 static void kgdb_initial_breakpoint(void)
1632 {
1633         kgdb_break_asap = 0;
1634
1635         printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1636         kgdb_breakpoint();
1637 }
1638
1639 /**
1640  *      kgdb_register_io_module - register KGDB IO module
1641  *      @new_kgdb_io_ops: the io ops vector
1642  *
1643  *      Register it with the KGDB core.
1644  */
1645 int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1646 {
1647         int err;
1648
1649         spin_lock(&kgdb_registration_lock);
1650
1651         if (kgdb_io_ops) {
1652                 spin_unlock(&kgdb_registration_lock);
1653
1654                 printk(KERN_ERR "kgdb: Another I/O driver is already "
1655                                 "registered with KGDB.\n");
1656                 return -EBUSY;
1657         }
1658
1659         if (new_kgdb_io_ops->init) {
1660                 err = new_kgdb_io_ops->init();
1661                 if (err) {
1662                         spin_unlock(&kgdb_registration_lock);
1663                         return err;
1664                 }
1665         }
1666
1667         kgdb_io_ops = new_kgdb_io_ops;
1668
1669         spin_unlock(&kgdb_registration_lock);
1670
1671         printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1672                new_kgdb_io_ops->name);
1673
1674         /* Arm KGDB now. */
1675         kgdb_register_callbacks();
1676
1677         if (kgdb_break_asap)
1678                 kgdb_initial_breakpoint();
1679
1680         return 0;
1681 }
1682 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1683
1684 /**
1685  *      kkgdb_unregister_io_module - unregister KGDB IO module
1686  *      @old_kgdb_io_ops: the io ops vector
1687  *
1688  *      Unregister it with the KGDB core.
1689  */
1690 void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1691 {
1692         BUG_ON(kgdb_connected);
1693
1694         /*
1695          * KGDB is no longer able to communicate out, so
1696          * unregister our callbacks and reset state.
1697          */
1698         kgdb_unregister_callbacks();
1699
1700         spin_lock(&kgdb_registration_lock);
1701
1702         WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1703         kgdb_io_ops = NULL;
1704
1705         spin_unlock(&kgdb_registration_lock);
1706
1707         printk(KERN_INFO
1708                 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1709                 old_kgdb_io_ops->name);
1710 }
1711 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1712
1713 /**
1714  * kgdb_breakpoint - generate breakpoint exception
1715  *
1716  * This function will generate a breakpoint exception.  It is used at the
1717  * beginning of a program to sync up with a debugger and can be used
1718  * otherwise as a quick means to stop program execution and "break" into
1719  * the debugger.
1720  */
1721 void kgdb_breakpoint(void)
1722 {
1723         atomic_set(&kgdb_setting_breakpoint, 1);
1724         wmb(); /* Sync point before breakpoint */
1725         arch_kgdb_breakpoint();
1726         wmb(); /* Sync point after breakpoint */
1727         atomic_set(&kgdb_setting_breakpoint, 0);
1728 }
1729 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1730
1731 static int __init opt_kgdb_wait(char *str)
1732 {
1733         kgdb_break_asap = 1;
1734
1735         if (kgdb_io_module_registered)
1736                 kgdb_initial_breakpoint();
1737
1738         return 0;
1739 }
1740
1741 early_param("kgdbwait", opt_kgdb_wait);