sysrq, intel_fb: fix sysrq g collision
[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 < 0) {
545                 if (kgdb_info[-tid - 2].task)
546                         return kgdb_info[-tid - 2].task;
547                 else
548                         return idle_task(-tid - 2);
549         }
550
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
564 static 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
580         /* 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);
593         touch_softlockup_watchdog();
594         clocksource_touch_watchdog();
595         local_irq_restore(flags);
596 }
597 #endif
598
599 /*
600  * Some architectures need cache flushes when we set/clear a
601  * breakpoint:
602  */
603 static void kgdb_flush_swbreak_addr(unsigned long addr)
604 {
605         if (!CACHE_FLUSH_IS_SAFE)
606                 return;
607
608         if (current->mm && current->mm->mmap_cache) {
609                 flush_cache_range(current->mm->mmap_cache,
610                                   addr, addr + BREAK_INSTR_SIZE);
611         }
612         /* Force flush instruction cache if it was outside the mm */
613         flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
614 }
615
616 /*
617  * SW breakpoint management:
618  */
619 static 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
641 static 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
682 static 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
703 static 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
717 int 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
729 static int remove_all_break(void)
730 {
731         unsigned long addr;
732         int error;
733         int i;
734
735         /* Clear memory breakpoints. */
736         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
737                 if (kgdb_break[i].state != BP_ACTIVE)
738                         goto setundefined;
739                 addr = kgdb_break[i].bpt_addr;
740                 error = kgdb_arch_remove_breakpoint(addr,
741                                 kgdb_break[i].saved_instr);
742                 if (error)
743                         printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
744                            addr);
745 setundefined:
746                 kgdb_break[i].state = BP_UNDEFINED;
747         }
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 /*
757  * Remap normal tasks to their real PID,
758  * CPU shadow threads are mapped to -CPU - 2
759  */
760 static inline int shadow_pid(int realpid)
761 {
762         if (realpid)
763                 return realpid;
764
765         return -raw_smp_processor_id() - 2;
766 }
767
768 static char gdbmsgbuf[BUFMAX + 1];
769
770 static 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  */
812 static 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 */
832 static 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 */
847 static 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;
859                 for_each_online_cpu(i) {
860                         /*
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 */
892 static 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 */
905 static 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 */
923 static 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 */
934 static 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 */
945 static 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 */
970 static 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 */
991 static void gdb_cmd_query(struct kgdb_state *ks)
992 {
993         struct task_struct *g;
994         struct task_struct *p;
995         unsigned char thref[8];
996         char *ptr;
997         int i;
998         int cpu;
999         int finished = 0;
1000
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
1009                 i = 0;
1010                 remcom_out_buffer[0] = 'm';
1011                 ptr = remcom_out_buffer + 1;
1012                 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);
1017                                 pack_threadid(ptr, thref);
1018                                 ptr += BUF_THREAD_ID_SIZE;
1019                                 *(ptr++) = ',';
1020                                 i++;
1021                         }
1022                 }
1023
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
1037                 *(--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                 }
1059                 if ((int)ks->threadid > 0) {
1060                         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
1066                         sprintf(tmpstr, "shadowCPU%d",
1067                                         (int)(-ks->threadid - 2));
1068                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1069                 }
1070                 break;
1071         }
1072 }
1073
1074 /* Handle the 'H' task query packets */
1075 static 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 */
1112 static 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 */
1126 static 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,
1176                         (int)length, *bpt_type - '0');
1177         else if (remcom_in_buffer[0] == 'z')
1178                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1179                         (int) length, *bpt_type - '0');
1180
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 */
1188 static 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  */
1218 static 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:
1313 default_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
1336 kgdb_exit:
1337         if (ks->pass_exception)
1338                 error = 1;
1339         return error;
1340 }
1341
1342 static 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();
1364                 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1365                         addr);
1366                 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  */
1392 int
1393 kgdb_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
1412 acquirelock:
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);
1436                 touch_softlockup_watchdog();
1437                 clocksource_touch_watchdog();
1438                 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          */
1467         if (!kgdb_single_step) {
1468                 for (i = 0; i < NR_CPUS; i++)
1469                         atomic_set(&passive_cpu_wait[i], 1);
1470         }
1471
1472         /*
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
1478 #ifdef CONFIG_SMP
1479         /* Signal the other CPUs to enter kgdb_wait() */
1480         if ((!kgdb_single_step) && kgdb_do_roundup)
1481                 kgdb_roundup_cpus(flags);
1482 #endif
1483
1484         /*
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;
1499         kgdb_contthread = current;
1500         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
1513         if (!kgdb_single_step) {
1514                 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
1526 kgdb_restore:
1527         /* Free kgdb_active */
1528         atomic_set(&kgdb_active, -1);
1529         touch_softlockup_watchdog();
1530         clocksource_touch_watchdog();
1531         local_irq_restore(flags);
1532
1533         return error;
1534 }
1535
1536 int kgdb_nmicallback(int cpu, void *regs)
1537 {
1538 #ifdef CONFIG_SMP
1539         if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1540                         atomic_read(&kgdb_active) != cpu &&
1541                         atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
1542                 kgdb_wait((struct pt_regs *)regs);
1543                 return 0;
1544         }
1545 #endif
1546         return 1;
1547 }
1548
1549 static void kgdb_console_write(struct console *co, const char *s,
1550    unsigned count)
1551 {
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
1564 static 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
1572 static 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
1584 static struct sysrq_key_op sysrq_gdb_op = {
1585         .handler        = sysrq_handle_gdb,
1586         .help_msg       = "debug(G)",
1587         .action_msg     = "DEBUG",
1588 };
1589 #endif
1590
1591 static 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
1606 static 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
1626 static 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 /**
1635  *      kgdb_register_io_module - register KGDB IO module
1636  *      @new_kgdb_io_ops: the io ops vector
1637  *
1638  *      Register it with the KGDB core.
1639  */
1640 int 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 }
1677 EXPORT_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  */
1685 void 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 }
1706 EXPORT_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  */
1716 void 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 }
1724 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1725
1726 static 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
1736 early_param("kgdbwait", opt_kgdb_wait);