6882c047452d0b5a6d15e12a95a26024a40a9c9a
[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 /* Exception state values */
73 #define DCPU_WANT_MASTER 0x1 /* Waiting to become a master kgdb cpu */
74 #define DCPU_NEXT_MASTER 0x2 /* Transition from one master cpu to another */
75 #define DCPU_IS_SLAVE    0x4 /* Slave cpu enter exception */
76 #define DCPU_SSTEP       0x8 /* CPU is single stepping */
77
78 static struct debuggerinfo_struct {
79         void                    *debuggerinfo;
80         struct task_struct      *task;
81         int                     exception_state;
82 } kgdb_info[NR_CPUS];
83
84 /**
85  * kgdb_connected - Is a host GDB connected to us?
86  */
87 int                             kgdb_connected;
88 EXPORT_SYMBOL_GPL(kgdb_connected);
89
90 /* All the KGDB handlers are installed */
91 static int                      kgdb_io_module_registered;
92
93 /* Guard for recursive entry */
94 static int                      exception_level;
95
96 static struct kgdb_io           *kgdb_io_ops;
97 static DEFINE_SPINLOCK(kgdb_registration_lock);
98
99 /* kgdb console driver is loaded */
100 static int kgdb_con_registered;
101 /* determine if kgdb console output should be used */
102 static int kgdb_use_con;
103
104 static int __init opt_kgdb_con(char *str)
105 {
106         kgdb_use_con = 1;
107         return 0;
108 }
109
110 early_param("kgdbcon", opt_kgdb_con);
111
112 module_param(kgdb_use_con, int, 0644);
113
114 /*
115  * Holds information about breakpoints in a kernel. These breakpoints are
116  * added and removed by gdb.
117  */
118 static struct kgdb_bkpt         kgdb_break[KGDB_MAX_BREAKPOINTS] = {
119         [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
120 };
121
122 /*
123  * The CPU# of the active CPU, or -1 if none:
124  */
125 atomic_t                        kgdb_active = ATOMIC_INIT(-1);
126
127 /*
128  * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
129  * bootup code (which might not have percpu set up yet):
130  */
131 static atomic_t                 passive_cpu_wait[NR_CPUS];
132 static atomic_t                 cpu_in_kgdb[NR_CPUS];
133 atomic_t                        kgdb_setting_breakpoint;
134
135 struct task_struct              *kgdb_usethread;
136 struct task_struct              *kgdb_contthread;
137
138 int                             kgdb_single_step;
139 pid_t                           kgdb_sstep_pid;
140
141 /* Our I/O buffers. */
142 static char                     remcom_in_buffer[BUFMAX];
143 static char                     remcom_out_buffer[BUFMAX];
144
145 /* Storage for the registers, in GDB format. */
146 static unsigned long            gdb_regs[(NUMREGBYTES +
147                                         sizeof(unsigned long) - 1) /
148                                         sizeof(unsigned long)];
149
150 /* to keep track of the CPU which is doing the single stepping*/
151 atomic_t                        kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
152
153 /*
154  * If you are debugging a problem where roundup (the collection of
155  * all other CPUs) is a problem [this should be extremely rare],
156  * then use the nokgdbroundup option to avoid roundup. In that case
157  * the other CPUs might interfere with your debugging context, so
158  * use this with care:
159  */
160 static int kgdb_do_roundup = 1;
161
162 static int __init opt_nokgdbroundup(char *str)
163 {
164         kgdb_do_roundup = 0;
165
166         return 0;
167 }
168
169 early_param("nokgdbroundup", opt_nokgdbroundup);
170
171 /*
172  * Finally, some KGDB code :-)
173  */
174
175 /*
176  * Weak aliases for breakpoint management,
177  * can be overriden by architectures when needed:
178  */
179 int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
180 {
181         int err;
182
183         err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
184         if (err)
185                 return err;
186
187         return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
188                                   BREAK_INSTR_SIZE);
189 }
190
191 int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
192 {
193         return probe_kernel_write((char *)addr,
194                                   (char *)bundle, BREAK_INSTR_SIZE);
195 }
196
197 int __weak kgdb_validate_break_address(unsigned long addr)
198 {
199         char tmp_variable[BREAK_INSTR_SIZE];
200         int err;
201         /* Validate setting the breakpoint and then removing it.  In the
202          * remove fails, the kernel needs to emit a bad message because we
203          * are deep trouble not being able to put things back the way we
204          * found them.
205          */
206         err = kgdb_arch_set_breakpoint(addr, tmp_variable);
207         if (err)
208                 return err;
209         err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
210         if (err)
211                 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
212                    "memory destroyed at: %lx", addr);
213         return err;
214 }
215
216 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
217 {
218         return instruction_pointer(regs);
219 }
220
221 int __weak kgdb_arch_init(void)
222 {
223         return 0;
224 }
225
226 int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
227 {
228         return 0;
229 }
230
231 void __weak
232 kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
233 {
234         return;
235 }
236
237 /**
238  *      kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
239  *      @regs: Current &struct pt_regs.
240  *
241  *      This function will be called if the particular architecture must
242  *      disable hardware debugging while it is processing gdb packets or
243  *      handling exception.
244  */
245 void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
246 {
247 }
248
249 /*
250  * GDB remote protocol parser:
251  */
252
253 static int hex(char ch)
254 {
255         if ((ch >= 'a') && (ch <= 'f'))
256                 return ch - 'a' + 10;
257         if ((ch >= '0') && (ch <= '9'))
258                 return ch - '0';
259         if ((ch >= 'A') && (ch <= 'F'))
260                 return ch - 'A' + 10;
261         return -1;
262 }
263
264 /* scan for the sequence $<data>#<checksum> */
265 static void get_packet(char *buffer)
266 {
267         unsigned char checksum;
268         unsigned char xmitcsum;
269         int count;
270         char ch;
271
272         do {
273                 /*
274                  * Spin and wait around for the start character, ignore all
275                  * other characters:
276                  */
277                 while ((ch = (kgdb_io_ops->read_char())) != '$')
278                         /* nothing */;
279
280                 kgdb_connected = 1;
281                 checksum = 0;
282                 xmitcsum = -1;
283
284                 count = 0;
285
286                 /*
287                  * now, read until a # or end of buffer is found:
288                  */
289                 while (count < (BUFMAX - 1)) {
290                         ch = kgdb_io_ops->read_char();
291                         if (ch == '#')
292                                 break;
293                         checksum = checksum + ch;
294                         buffer[count] = ch;
295                         count = count + 1;
296                 }
297                 buffer[count] = 0;
298
299                 if (ch == '#') {
300                         xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
301                         xmitcsum += hex(kgdb_io_ops->read_char());
302
303                         if (checksum != xmitcsum)
304                                 /* failed checksum */
305                                 kgdb_io_ops->write_char('-');
306                         else
307                                 /* successful transfer */
308                                 kgdb_io_ops->write_char('+');
309                         if (kgdb_io_ops->flush)
310                                 kgdb_io_ops->flush();
311                 }
312         } while (checksum != xmitcsum);
313 }
314
315 /*
316  * Send the packet in buffer.
317  * Check for gdb connection if asked for.
318  */
319 static void put_packet(char *buffer)
320 {
321         unsigned char checksum;
322         int count;
323         char ch;
324
325         /*
326          * $<packet info>#<checksum>.
327          */
328         while (1) {
329                 kgdb_io_ops->write_char('$');
330                 checksum = 0;
331                 count = 0;
332
333                 while ((ch = buffer[count])) {
334                         kgdb_io_ops->write_char(ch);
335                         checksum += ch;
336                         count++;
337                 }
338
339                 kgdb_io_ops->write_char('#');
340                 kgdb_io_ops->write_char(hex_asc_hi(checksum));
341                 kgdb_io_ops->write_char(hex_asc_lo(checksum));
342                 if (kgdb_io_ops->flush)
343                         kgdb_io_ops->flush();
344
345                 /* Now see what we get in reply. */
346                 ch = kgdb_io_ops->read_char();
347
348                 if (ch == 3)
349                         ch = kgdb_io_ops->read_char();
350
351                 /* If we get an ACK, we are done. */
352                 if (ch == '+')
353                         return;
354
355                 /*
356                  * If we get the start of another packet, this means
357                  * that GDB is attempting to reconnect.  We will NAK
358                  * the packet being sent, and stop trying to send this
359                  * packet.
360                  */
361                 if (ch == '$') {
362                         kgdb_io_ops->write_char('-');
363                         if (kgdb_io_ops->flush)
364                                 kgdb_io_ops->flush();
365                         return;
366                 }
367         }
368 }
369
370 /*
371  * Convert the memory pointed to by mem into hex, placing result in buf.
372  * Return a pointer to the last char put in buf (null). May return an error.
373  */
374 int kgdb_mem2hex(char *mem, char *buf, int count)
375 {
376         char *tmp;
377         int err;
378
379         /*
380          * We use the upper half of buf as an intermediate buffer for the
381          * raw memory copy.  Hex conversion will work against this one.
382          */
383         tmp = buf + count;
384
385         err = probe_kernel_read(tmp, mem, count);
386         if (!err) {
387                 while (count > 0) {
388                         buf = pack_hex_byte(buf, *tmp);
389                         tmp++;
390                         count--;
391                 }
392
393                 *buf = 0;
394         }
395
396         return err;
397 }
398
399 /*
400  * Copy the binary array pointed to by buf into mem.  Fix $, #, and
401  * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
402  * The input buf is overwitten with the result to write to mem.
403  */
404 static int kgdb_ebin2mem(char *buf, char *mem, int count)
405 {
406         int size = 0;
407         char *c = buf;
408
409         while (count-- > 0) {
410                 c[size] = *buf++;
411                 if (c[size] == 0x7d)
412                         c[size] = *buf++ ^ 0x20;
413                 size++;
414         }
415
416         return probe_kernel_write(mem, c, size);
417 }
418
419 /*
420  * Convert the hex array pointed to by buf into binary to be placed in mem.
421  * Return a pointer to the character AFTER the last byte written.
422  * May return an error.
423  */
424 int kgdb_hex2mem(char *buf, char *mem, int count)
425 {
426         char *tmp_raw;
427         char *tmp_hex;
428
429         /*
430          * We use the upper half of buf as an intermediate buffer for the
431          * raw memory that is converted from hex.
432          */
433         tmp_raw = buf + count * 2;
434
435         tmp_hex = tmp_raw - 1;
436         while (tmp_hex >= buf) {
437                 tmp_raw--;
438                 *tmp_raw = hex(*tmp_hex--);
439                 *tmp_raw |= hex(*tmp_hex--) << 4;
440         }
441
442         return probe_kernel_write(mem, tmp_raw, count);
443 }
444
445 /*
446  * While we find nice hex chars, build a long_val.
447  * Return number of chars processed.
448  */
449 int kgdb_hex2long(char **ptr, unsigned long *long_val)
450 {
451         int hex_val;
452         int num = 0;
453         int negate = 0;
454
455         *long_val = 0;
456
457         if (**ptr == '-') {
458                 negate = 1;
459                 (*ptr)++;
460         }
461         while (**ptr) {
462                 hex_val = hex(**ptr);
463                 if (hex_val < 0)
464                         break;
465
466                 *long_val = (*long_val << 4) | hex_val;
467                 num++;
468                 (*ptr)++;
469         }
470
471         if (negate)
472                 *long_val = -*long_val;
473
474         return num;
475 }
476
477 /* Write memory due to an 'M' or 'X' packet. */
478 static int write_mem_msg(int binary)
479 {
480         char *ptr = &remcom_in_buffer[1];
481         unsigned long addr;
482         unsigned long length;
483         int err;
484
485         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
486             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
487                 if (binary)
488                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
489                 else
490                         err = kgdb_hex2mem(ptr, (char *)addr, length);
491                 if (err)
492                         return err;
493                 if (CACHE_FLUSH_IS_SAFE)
494                         flush_icache_range(addr, addr + length);
495                 return 0;
496         }
497
498         return -EINVAL;
499 }
500
501 static void error_packet(char *pkt, int error)
502 {
503         error = -error;
504         pkt[0] = 'E';
505         pkt[1] = hex_asc[(error / 10)];
506         pkt[2] = hex_asc[(error % 10)];
507         pkt[3] = '\0';
508 }
509
510 /*
511  * Thread ID accessors. We represent a flat TID space to GDB, where
512  * the per CPU idle threads (which under Linux all have PID 0) are
513  * remapped to negative TIDs.
514  */
515
516 #define BUF_THREAD_ID_SIZE      16
517
518 static char *pack_threadid(char *pkt, unsigned char *id)
519 {
520         char *limit;
521
522         limit = pkt + BUF_THREAD_ID_SIZE;
523         while (pkt < limit)
524                 pkt = pack_hex_byte(pkt, *id++);
525
526         return pkt;
527 }
528
529 static void int_to_threadref(unsigned char *id, int value)
530 {
531         unsigned char *scan;
532         int i = 4;
533
534         scan = (unsigned char *)id;
535         while (i--)
536                 *scan++ = 0;
537         put_unaligned_be32(value, scan);
538 }
539
540 static struct task_struct *getthread(struct pt_regs *regs, int tid)
541 {
542         /*
543          * Non-positive TIDs are remapped to the cpu shadow information
544          */
545         if (tid == 0 || tid == -1)
546                 tid = -atomic_read(&kgdb_active) - 2;
547         if (tid < -1 && tid > -NR_CPUS - 2) {
548                 if (kgdb_info[-tid - 2].task)
549                         return kgdb_info[-tid - 2].task;
550                 else
551                         return idle_task(-tid - 2);
552         }
553         if (tid <= 0) {
554                 printk(KERN_ERR "KGDB: Internal thread select error\n");
555                 dump_stack();
556                 return NULL;
557         }
558
559         /*
560          * find_task_by_pid_ns() does not take the tasklist lock anymore
561          * but is nicely RCU locked - hence is a pretty resilient
562          * thing to use:
563          */
564         return find_task_by_pid_ns(tid, &init_pid_ns);
565 }
566
567 /*
568  * Some architectures need cache flushes when we set/clear a
569  * breakpoint:
570  */
571 static void kgdb_flush_swbreak_addr(unsigned long addr)
572 {
573         if (!CACHE_FLUSH_IS_SAFE)
574                 return;
575
576         if (current->mm && current->mm->mmap_cache) {
577                 flush_cache_range(current->mm->mmap_cache,
578                                   addr, addr + BREAK_INSTR_SIZE);
579         }
580         /* Force flush instruction cache if it was outside the mm */
581         flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
582 }
583
584 /*
585  * SW breakpoint management:
586  */
587 static int kgdb_activate_sw_breakpoints(void)
588 {
589         unsigned long addr;
590         int error;
591         int ret = 0;
592         int i;
593
594         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
595                 if (kgdb_break[i].state != BP_SET)
596                         continue;
597
598                 addr = kgdb_break[i].bpt_addr;
599                 error = kgdb_arch_set_breakpoint(addr,
600                                 kgdb_break[i].saved_instr);
601                 if (error) {
602                         ret = error;
603                         printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
604                         continue;
605                 }
606
607                 kgdb_flush_swbreak_addr(addr);
608                 kgdb_break[i].state = BP_ACTIVE;
609         }
610         return ret;
611 }
612
613 static int kgdb_set_sw_break(unsigned long addr)
614 {
615         int err = kgdb_validate_break_address(addr);
616         int breakno = -1;
617         int i;
618
619         if (err)
620                 return err;
621
622         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
623                 if ((kgdb_break[i].state == BP_SET) &&
624                                         (kgdb_break[i].bpt_addr == addr))
625                         return -EEXIST;
626         }
627         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
628                 if (kgdb_break[i].state == BP_REMOVED &&
629                                         kgdb_break[i].bpt_addr == addr) {
630                         breakno = i;
631                         break;
632                 }
633         }
634
635         if (breakno == -1) {
636                 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
637                         if (kgdb_break[i].state == BP_UNDEFINED) {
638                                 breakno = i;
639                                 break;
640                         }
641                 }
642         }
643
644         if (breakno == -1)
645                 return -E2BIG;
646
647         kgdb_break[breakno].state = BP_SET;
648         kgdb_break[breakno].type = BP_BREAKPOINT;
649         kgdb_break[breakno].bpt_addr = addr;
650
651         return 0;
652 }
653
654 static int kgdb_deactivate_sw_breakpoints(void)
655 {
656         unsigned long addr;
657         int error;
658         int ret = 0;
659         int i;
660
661         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
662                 if (kgdb_break[i].state != BP_ACTIVE)
663                         continue;
664                 addr = kgdb_break[i].bpt_addr;
665                 error = kgdb_arch_remove_breakpoint(addr,
666                                         kgdb_break[i].saved_instr);
667                 if (error) {
668                         printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
669                         ret = error;
670                 }
671
672                 kgdb_flush_swbreak_addr(addr);
673                 kgdb_break[i].state = BP_SET;
674         }
675         return ret;
676 }
677
678 static int kgdb_remove_sw_break(unsigned long addr)
679 {
680         int i;
681
682         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
683                 if ((kgdb_break[i].state == BP_SET) &&
684                                 (kgdb_break[i].bpt_addr == addr)) {
685                         kgdb_break[i].state = BP_REMOVED;
686                         return 0;
687                 }
688         }
689         return -ENOENT;
690 }
691
692 int kgdb_isremovedbreak(unsigned long addr)
693 {
694         int i;
695
696         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
697                 if ((kgdb_break[i].state == BP_REMOVED) &&
698                                         (kgdb_break[i].bpt_addr == addr))
699                         return 1;
700         }
701         return 0;
702 }
703
704 static int remove_all_break(void)
705 {
706         unsigned long addr;
707         int error;
708         int i;
709
710         /* Clear memory breakpoints. */
711         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
712                 if (kgdb_break[i].state != BP_ACTIVE)
713                         goto setundefined;
714                 addr = kgdb_break[i].bpt_addr;
715                 error = kgdb_arch_remove_breakpoint(addr,
716                                 kgdb_break[i].saved_instr);
717                 if (error)
718                         printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
719                            addr);
720 setundefined:
721                 kgdb_break[i].state = BP_UNDEFINED;
722         }
723
724         /* Clear hardware breakpoints. */
725         if (arch_kgdb_ops.remove_all_hw_break)
726                 arch_kgdb_ops.remove_all_hw_break();
727
728         return 0;
729 }
730
731 /*
732  * Remap normal tasks to their real PID,
733  * CPU shadow threads are mapped to -CPU - 2
734  */
735 static inline int shadow_pid(int realpid)
736 {
737         if (realpid)
738                 return realpid;
739
740         return -raw_smp_processor_id() - 2;
741 }
742
743 static char gdbmsgbuf[BUFMAX + 1];
744
745 static void kgdb_msg_write(const char *s, int len)
746 {
747         char *bufptr;
748         int wcount;
749         int i;
750
751         /* 'O'utput */
752         gdbmsgbuf[0] = 'O';
753
754         /* Fill and send buffers... */
755         while (len > 0) {
756                 bufptr = gdbmsgbuf + 1;
757
758                 /* Calculate how many this time */
759                 if ((len << 1) > (BUFMAX - 2))
760                         wcount = (BUFMAX - 2) >> 1;
761                 else
762                         wcount = len;
763
764                 /* Pack in hex chars */
765                 for (i = 0; i < wcount; i++)
766                         bufptr = pack_hex_byte(bufptr, s[i]);
767                 *bufptr = '\0';
768
769                 /* Move up */
770                 s += wcount;
771                 len -= wcount;
772
773                 /* Write packet */
774                 put_packet(gdbmsgbuf);
775         }
776 }
777
778 /*
779  * Return true if there is a valid kgdb I/O module.  Also if no
780  * debugger is attached a message can be printed to the console about
781  * waiting for the debugger to attach.
782  *
783  * The print_wait argument is only to be true when called from inside
784  * the core kgdb_handle_exception, because it will wait for the
785  * debugger to attach.
786  */
787 static int kgdb_io_ready(int print_wait)
788 {
789         if (!kgdb_io_ops)
790                 return 0;
791         if (kgdb_connected)
792                 return 1;
793         if (atomic_read(&kgdb_setting_breakpoint))
794                 return 1;
795         if (print_wait)
796                 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
797         return 1;
798 }
799
800 /*
801  * All the functions that start with gdb_cmd are the various
802  * operations to implement the handlers for the gdbserial protocol
803  * where KGDB is communicating with an external debugger
804  */
805
806 /* Handle the '?' status packets */
807 static void gdb_cmd_status(struct kgdb_state *ks)
808 {
809         /*
810          * We know that this packet is only sent
811          * during initial connect.  So to be safe,
812          * we clear out our breakpoints now in case
813          * GDB is reconnecting.
814          */
815         remove_all_break();
816
817         remcom_out_buffer[0] = 'S';
818         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
819 }
820
821 /* Handle the 'g' get registers request */
822 static void gdb_cmd_getregs(struct kgdb_state *ks)
823 {
824         struct task_struct *thread;
825         void *local_debuggerinfo;
826         int i;
827
828         thread = kgdb_usethread;
829         if (!thread) {
830                 thread = kgdb_info[ks->cpu].task;
831                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
832         } else {
833                 local_debuggerinfo = NULL;
834                 for_each_online_cpu(i) {
835                         /*
836                          * Try to find the task on some other
837                          * or possibly this node if we do not
838                          * find the matching task then we try
839                          * to approximate the results.
840                          */
841                         if (thread == kgdb_info[i].task)
842                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
843                 }
844         }
845
846         /*
847          * All threads that don't have debuggerinfo should be
848          * in schedule() sleeping, since all other CPUs
849          * are in kgdb_wait, and thus have debuggerinfo.
850          */
851         if (local_debuggerinfo) {
852                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
853         } else {
854                 /*
855                  * Pull stuff saved during switch_to; nothing
856                  * else is accessible (or even particularly
857                  * relevant).
858                  *
859                  * This should be enough for a stack trace.
860                  */
861                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
862         }
863         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
864 }
865
866 /* Handle the 'G' set registers request */
867 static void gdb_cmd_setregs(struct kgdb_state *ks)
868 {
869         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
870
871         if (kgdb_usethread && kgdb_usethread != current) {
872                 error_packet(remcom_out_buffer, -EINVAL);
873         } else {
874                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
875                 strcpy(remcom_out_buffer, "OK");
876         }
877 }
878
879 /* Handle the 'm' memory read bytes */
880 static void gdb_cmd_memread(struct kgdb_state *ks)
881 {
882         char *ptr = &remcom_in_buffer[1];
883         unsigned long length;
884         unsigned long addr;
885         int err;
886
887         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
888                                         kgdb_hex2long(&ptr, &length) > 0) {
889                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
890                 if (err)
891                         error_packet(remcom_out_buffer, err);
892         } else {
893                 error_packet(remcom_out_buffer, -EINVAL);
894         }
895 }
896
897 /* Handle the 'M' memory write bytes */
898 static void gdb_cmd_memwrite(struct kgdb_state *ks)
899 {
900         int err = write_mem_msg(0);
901
902         if (err)
903                 error_packet(remcom_out_buffer, err);
904         else
905                 strcpy(remcom_out_buffer, "OK");
906 }
907
908 /* Handle the 'X' memory binary write bytes */
909 static void gdb_cmd_binwrite(struct kgdb_state *ks)
910 {
911         int err = write_mem_msg(1);
912
913         if (err)
914                 error_packet(remcom_out_buffer, err);
915         else
916                 strcpy(remcom_out_buffer, "OK");
917 }
918
919 /* Handle the 'D' or 'k', detach or kill packets */
920 static void gdb_cmd_detachkill(struct kgdb_state *ks)
921 {
922         int error;
923
924         /* The detach case */
925         if (remcom_in_buffer[0] == 'D') {
926                 error = remove_all_break();
927                 if (error < 0) {
928                         error_packet(remcom_out_buffer, error);
929                 } else {
930                         strcpy(remcom_out_buffer, "OK");
931                         kgdb_connected = 0;
932                 }
933                 put_packet(remcom_out_buffer);
934         } else {
935                 /*
936                  * Assume the kill case, with no exit code checking,
937                  * trying to force detach the debugger:
938                  */
939                 remove_all_break();
940                 kgdb_connected = 0;
941         }
942 }
943
944 /* Handle the 'R' reboot packets */
945 static int gdb_cmd_reboot(struct kgdb_state *ks)
946 {
947         /* For now, only honor R0 */
948         if (strcmp(remcom_in_buffer, "R0") == 0) {
949                 printk(KERN_CRIT "Executing emergency reboot\n");
950                 strcpy(remcom_out_buffer, "OK");
951                 put_packet(remcom_out_buffer);
952
953                 /*
954                  * Execution should not return from
955                  * machine_emergency_restart()
956                  */
957                 machine_emergency_restart();
958                 kgdb_connected = 0;
959
960                 return 1;
961         }
962         return 0;
963 }
964
965 /* Handle the 'q' query packets */
966 static void gdb_cmd_query(struct kgdb_state *ks)
967 {
968         struct task_struct *g;
969         struct task_struct *p;
970         unsigned char thref[8];
971         char *ptr;
972         int i;
973         int cpu;
974         int finished = 0;
975
976         switch (remcom_in_buffer[1]) {
977         case 's':
978         case 'f':
979                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
980                         error_packet(remcom_out_buffer, -EINVAL);
981                         break;
982                 }
983
984                 i = 0;
985                 remcom_out_buffer[0] = 'm';
986                 ptr = remcom_out_buffer + 1;
987                 if (remcom_in_buffer[1] == 'f') {
988                         /* Each cpu is a shadow thread */
989                         for_each_online_cpu(cpu) {
990                                 ks->thr_query = 0;
991                                 int_to_threadref(thref, -cpu - 2);
992                                 pack_threadid(ptr, thref);
993                                 ptr += BUF_THREAD_ID_SIZE;
994                                 *(ptr++) = ',';
995                                 i++;
996                         }
997                 }
998
999                 do_each_thread(g, p) {
1000                         if (i >= ks->thr_query && !finished) {
1001                                 int_to_threadref(thref, p->pid);
1002                                 pack_threadid(ptr, thref);
1003                                 ptr += BUF_THREAD_ID_SIZE;
1004                                 *(ptr++) = ',';
1005                                 ks->thr_query++;
1006                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
1007                                         finished = 1;
1008                         }
1009                         i++;
1010                 } while_each_thread(g, p);
1011
1012                 *(--ptr) = '\0';
1013                 break;
1014
1015         case 'C':
1016                 /* Current thread id */
1017                 strcpy(remcom_out_buffer, "QC");
1018                 ks->threadid = shadow_pid(current->pid);
1019                 int_to_threadref(thref, ks->threadid);
1020                 pack_threadid(remcom_out_buffer + 2, thref);
1021                 break;
1022         case 'T':
1023                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1024                         error_packet(remcom_out_buffer, -EINVAL);
1025                         break;
1026                 }
1027                 ks->threadid = 0;
1028                 ptr = remcom_in_buffer + 17;
1029                 kgdb_hex2long(&ptr, &ks->threadid);
1030                 if (!getthread(ks->linux_regs, ks->threadid)) {
1031                         error_packet(remcom_out_buffer, -EINVAL);
1032                         break;
1033                 }
1034                 if ((int)ks->threadid > 0) {
1035                         kgdb_mem2hex(getthread(ks->linux_regs,
1036                                         ks->threadid)->comm,
1037                                         remcom_out_buffer, 16);
1038                 } else {
1039                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1040
1041                         sprintf(tmpstr, "shadowCPU%d",
1042                                         (int)(-ks->threadid - 2));
1043                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1044                 }
1045                 break;
1046         }
1047 }
1048
1049 /* Handle the 'H' task query packets */
1050 static void gdb_cmd_task(struct kgdb_state *ks)
1051 {
1052         struct task_struct *thread;
1053         char *ptr;
1054
1055         switch (remcom_in_buffer[1]) {
1056         case 'g':
1057                 ptr = &remcom_in_buffer[2];
1058                 kgdb_hex2long(&ptr, &ks->threadid);
1059                 thread = getthread(ks->linux_regs, ks->threadid);
1060                 if (!thread && ks->threadid > 0) {
1061                         error_packet(remcom_out_buffer, -EINVAL);
1062                         break;
1063                 }
1064                 kgdb_usethread = thread;
1065                 ks->kgdb_usethreadid = ks->threadid;
1066                 strcpy(remcom_out_buffer, "OK");
1067                 break;
1068         case 'c':
1069                 ptr = &remcom_in_buffer[2];
1070                 kgdb_hex2long(&ptr, &ks->threadid);
1071                 if (!ks->threadid) {
1072                         kgdb_contthread = NULL;
1073                 } else {
1074                         thread = getthread(ks->linux_regs, ks->threadid);
1075                         if (!thread && ks->threadid > 0) {
1076                                 error_packet(remcom_out_buffer, -EINVAL);
1077                                 break;
1078                         }
1079                         kgdb_contthread = thread;
1080                 }
1081                 strcpy(remcom_out_buffer, "OK");
1082                 break;
1083         }
1084 }
1085
1086 /* Handle the 'T' thread query packets */
1087 static void gdb_cmd_thread(struct kgdb_state *ks)
1088 {
1089         char *ptr = &remcom_in_buffer[1];
1090         struct task_struct *thread;
1091
1092         kgdb_hex2long(&ptr, &ks->threadid);
1093         thread = getthread(ks->linux_regs, ks->threadid);
1094         if (thread)
1095                 strcpy(remcom_out_buffer, "OK");
1096         else
1097                 error_packet(remcom_out_buffer, -EINVAL);
1098 }
1099
1100 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
1101 static void gdb_cmd_break(struct kgdb_state *ks)
1102 {
1103         /*
1104          * Since GDB-5.3, it's been drafted that '0' is a software
1105          * breakpoint, '1' is a hardware breakpoint, so let's do that.
1106          */
1107         char *bpt_type = &remcom_in_buffer[1];
1108         char *ptr = &remcom_in_buffer[2];
1109         unsigned long addr;
1110         unsigned long length;
1111         int error = 0;
1112
1113         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1114                 /* Unsupported */
1115                 if (*bpt_type > '4')
1116                         return;
1117         } else {
1118                 if (*bpt_type != '0' && *bpt_type != '1')
1119                         /* Unsupported. */
1120                         return;
1121         }
1122
1123         /*
1124          * Test if this is a hardware breakpoint, and
1125          * if we support it:
1126          */
1127         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1128                 /* Unsupported. */
1129                 return;
1130
1131         if (*(ptr++) != ',') {
1132                 error_packet(remcom_out_buffer, -EINVAL);
1133                 return;
1134         }
1135         if (!kgdb_hex2long(&ptr, &addr)) {
1136                 error_packet(remcom_out_buffer, -EINVAL);
1137                 return;
1138         }
1139         if (*(ptr++) != ',' ||
1140                 !kgdb_hex2long(&ptr, &length)) {
1141                 error_packet(remcom_out_buffer, -EINVAL);
1142                 return;
1143         }
1144
1145         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1146                 error = kgdb_set_sw_break(addr);
1147         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1148                 error = kgdb_remove_sw_break(addr);
1149         else if (remcom_in_buffer[0] == 'Z')
1150                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
1151                         (int)length, *bpt_type - '0');
1152         else if (remcom_in_buffer[0] == 'z')
1153                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1154                         (int) length, *bpt_type - '0');
1155
1156         if (error == 0)
1157                 strcpy(remcom_out_buffer, "OK");
1158         else
1159                 error_packet(remcom_out_buffer, error);
1160 }
1161
1162 /* Handle the 'C' signal / exception passing packets */
1163 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1164 {
1165         /* C09 == pass exception
1166          * C15 == detach kgdb, pass exception
1167          */
1168         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1169
1170                 ks->pass_exception = 1;
1171                 remcom_in_buffer[0] = 'c';
1172
1173         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1174
1175                 ks->pass_exception = 1;
1176                 remcom_in_buffer[0] = 'D';
1177                 remove_all_break();
1178                 kgdb_connected = 0;
1179                 return 1;
1180
1181         } else {
1182                 kgdb_msg_write("KGDB only knows signal 9 (pass)"
1183                         " and 15 (pass and disconnect)\n"
1184                         "Executing a continue without signal passing\n", 0);
1185                 remcom_in_buffer[0] = 'c';
1186         }
1187
1188         /* Indicate fall through */
1189         return -1;
1190 }
1191
1192 /*
1193  * This function performs all gdbserial command procesing
1194  */
1195 static int gdb_serial_stub(struct kgdb_state *ks)
1196 {
1197         int error = 0;
1198         int tmp;
1199
1200         /* Clear the out buffer. */
1201         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1202
1203         if (kgdb_connected) {
1204                 unsigned char thref[8];
1205                 char *ptr;
1206
1207                 /* Reply to host that an exception has occurred */
1208                 ptr = remcom_out_buffer;
1209                 *ptr++ = 'T';
1210                 ptr = pack_hex_byte(ptr, ks->signo);
1211                 ptr += strlen(strcpy(ptr, "thread:"));
1212                 int_to_threadref(thref, shadow_pid(current->pid));
1213                 ptr = pack_threadid(ptr, thref);
1214                 *ptr++ = ';';
1215                 put_packet(remcom_out_buffer);
1216         }
1217
1218         kgdb_usethread = kgdb_info[ks->cpu].task;
1219         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1220         ks->pass_exception = 0;
1221
1222         while (1) {
1223                 error = 0;
1224
1225                 /* Clear the out buffer. */
1226                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1227
1228                 get_packet(remcom_in_buffer);
1229
1230                 switch (remcom_in_buffer[0]) {
1231                 case '?': /* gdbserial status */
1232                         gdb_cmd_status(ks);
1233                         break;
1234                 case 'g': /* return the value of the CPU registers */
1235                         gdb_cmd_getregs(ks);
1236                         break;
1237                 case 'G': /* set the value of the CPU registers - return OK */
1238                         gdb_cmd_setregs(ks);
1239                         break;
1240                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
1241                         gdb_cmd_memread(ks);
1242                         break;
1243                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1244                         gdb_cmd_memwrite(ks);
1245                         break;
1246                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1247                         gdb_cmd_binwrite(ks);
1248                         break;
1249                         /* kill or detach. KGDB should treat this like a
1250                          * continue.
1251                          */
1252                 case 'D': /* Debugger detach */
1253                 case 'k': /* Debugger detach via kill */
1254                         gdb_cmd_detachkill(ks);
1255                         goto default_handle;
1256                 case 'R': /* Reboot */
1257                         if (gdb_cmd_reboot(ks))
1258                                 goto default_handle;
1259                         break;
1260                 case 'q': /* query command */
1261                         gdb_cmd_query(ks);
1262                         break;
1263                 case 'H': /* task related */
1264                         gdb_cmd_task(ks);
1265                         break;
1266                 case 'T': /* Query thread status */
1267                         gdb_cmd_thread(ks);
1268                         break;
1269                 case 'z': /* Break point remove */
1270                 case 'Z': /* Break point set */
1271                         gdb_cmd_break(ks);
1272                         break;
1273                 case 'C': /* Exception passing */
1274                         tmp = gdb_cmd_exception_pass(ks);
1275                         if (tmp > 0)
1276                                 goto default_handle;
1277                         if (tmp == 0)
1278                                 break;
1279                         /* Fall through on tmp < 0 */
1280                 case 'c': /* Continue packet */
1281                 case 's': /* Single step packet */
1282                         if (kgdb_contthread && kgdb_contthread != current) {
1283                                 /* Can't switch threads in kgdb */
1284                                 error_packet(remcom_out_buffer, -EINVAL);
1285                                 break;
1286                         }
1287                         kgdb_activate_sw_breakpoints();
1288                         /* Fall through to default processing */
1289                 default:
1290 default_handle:
1291                         error = kgdb_arch_handle_exception(ks->ex_vector,
1292                                                 ks->signo,
1293                                                 ks->err_code,
1294                                                 remcom_in_buffer,
1295                                                 remcom_out_buffer,
1296                                                 ks->linux_regs);
1297                         /*
1298                          * Leave cmd processing on error, detach,
1299                          * kill, continue, or single step.
1300                          */
1301                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1302                             remcom_in_buffer[0] == 'k') {
1303                                 error = 0;
1304                                 goto kgdb_exit;
1305                         }
1306
1307                 }
1308
1309                 /* reply to the request */
1310                 put_packet(remcom_out_buffer);
1311         }
1312
1313 kgdb_exit:
1314         if (ks->pass_exception)
1315                 error = 1;
1316         return error;
1317 }
1318
1319 static int kgdb_reenter_check(struct kgdb_state *ks)
1320 {
1321         unsigned long addr;
1322
1323         if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1324                 return 0;
1325
1326         /* Panic on recursive debugger calls: */
1327         exception_level++;
1328         addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1329         kgdb_deactivate_sw_breakpoints();
1330
1331         /*
1332          * If the break point removed ok at the place exception
1333          * occurred, try to recover and print a warning to the end
1334          * user because the user planted a breakpoint in a place that
1335          * KGDB needs in order to function.
1336          */
1337         if (kgdb_remove_sw_break(addr) == 0) {
1338                 exception_level = 0;
1339                 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1340                 kgdb_activate_sw_breakpoints();
1341                 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1342                         addr);
1343                 WARN_ON_ONCE(1);
1344
1345                 return 1;
1346         }
1347         remove_all_break();
1348         kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1349
1350         if (exception_level > 1) {
1351                 dump_stack();
1352                 panic("Recursive entry to debugger");
1353         }
1354
1355         printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1356         dump_stack();
1357         panic("Recursive entry to debugger");
1358
1359         return 1;
1360 }
1361
1362 static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
1363 {
1364         unsigned long flags;
1365         int sstep_tries = 100;
1366         int error = 0;
1367         int i, cpu;
1368 acquirelock:
1369         /*
1370          * Interrupts will be restored by the 'trap return' code, except when
1371          * single stepping.
1372          */
1373         local_irq_save(flags);
1374
1375         cpu = ks->cpu;
1376         kgdb_info[cpu].debuggerinfo = regs;
1377         kgdb_info[cpu].task = current;
1378         /*
1379          * Make sure the above info reaches the primary CPU before
1380          * our cpu_in_kgdb[] flag setting does:
1381          */
1382         smp_wmb();
1383         atomic_set(&cpu_in_kgdb[cpu], 1);
1384
1385         /*
1386          * CPU will loop if it is a slave or request to become a kgdb
1387          * master cpu and acquire the kgdb_active lock:
1388          */
1389         while (1) {
1390                 if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
1391                         if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu)
1392                                 break;
1393                 } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
1394                         if (!atomic_read(&passive_cpu_wait[cpu]))
1395                                 goto return_normal;
1396                 } else {
1397 return_normal:
1398                         /* Return to normal operation by executing any
1399                          * hw breakpoint fixup.
1400                          */
1401                         if (arch_kgdb_ops.correct_hw_break)
1402                                 arch_kgdb_ops.correct_hw_break();
1403                         atomic_set(&cpu_in_kgdb[cpu], 0);
1404                         touch_softlockup_watchdog_sync();
1405                         clocksource_touch_watchdog();
1406                         local_irq_restore(flags);
1407                         return 0;
1408                 }
1409                 cpu_relax();
1410         }
1411
1412         /*
1413          * For single stepping, try to only enter on the processor
1414          * that was single stepping.  To gaurd against a deadlock, the
1415          * kernel will only try for the value of sstep_tries before
1416          * giving up and continuing on.
1417          */
1418         if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1419             (kgdb_info[cpu].task &&
1420              kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
1421                 atomic_set(&kgdb_active, -1);
1422                 touch_softlockup_watchdog_sync();
1423                 clocksource_touch_watchdog();
1424                 local_irq_restore(flags);
1425
1426                 goto acquirelock;
1427         }
1428
1429         if (!kgdb_io_ready(1)) {
1430                 error = 1;
1431                 goto kgdb_restore; /* No I/O connection, so resume the system */
1432         }
1433
1434         /*
1435          * Don't enter if we have hit a removed breakpoint.
1436          */
1437         if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1438                 goto kgdb_restore;
1439
1440         /* Call the I/O driver's pre_exception routine */
1441         if (kgdb_io_ops->pre_exception)
1442                 kgdb_io_ops->pre_exception();
1443
1444         kgdb_disable_hw_debug(ks->linux_regs);
1445
1446         /*
1447          * Get the passive CPU lock which will hold all the non-primary
1448          * CPU in a spin state while the debugger is active
1449          */
1450         if (!kgdb_single_step) {
1451                 for (i = 0; i < NR_CPUS; i++)
1452                         atomic_set(&passive_cpu_wait[i], 1);
1453         }
1454
1455 #ifdef CONFIG_SMP
1456         /* Signal the other CPUs to enter kgdb_wait() */
1457         if ((!kgdb_single_step) && kgdb_do_roundup)
1458                 kgdb_roundup_cpus(flags);
1459 #endif
1460
1461         /*
1462          * Wait for the other CPUs to be notified and be waiting for us:
1463          */
1464         for_each_online_cpu(i) {
1465                 while (!atomic_read(&cpu_in_kgdb[i]))
1466                         cpu_relax();
1467         }
1468
1469         /*
1470          * At this point the primary processor is completely
1471          * in the debugger and all secondary CPUs are quiescent
1472          */
1473         kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1474         kgdb_deactivate_sw_breakpoints();
1475         kgdb_single_step = 0;
1476         kgdb_contthread = current;
1477         exception_level = 0;
1478
1479         /* Talk to debugger with gdbserial protocol */
1480         error = gdb_serial_stub(ks);
1481
1482         /* Call the I/O driver's post_exception routine */
1483         if (kgdb_io_ops->post_exception)
1484                 kgdb_io_ops->post_exception();
1485
1486         atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1487
1488         if (!kgdb_single_step) {
1489                 for (i = NR_CPUS-1; i >= 0; i--)
1490                         atomic_set(&passive_cpu_wait[i], 0);
1491                 /*
1492                  * Wait till all the CPUs have quit
1493                  * from the debugger.
1494                  */
1495                 for_each_online_cpu(i) {
1496                         while (atomic_read(&cpu_in_kgdb[i]))
1497                                 cpu_relax();
1498                 }
1499         }
1500
1501 kgdb_restore:
1502         if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
1503                 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
1504                 if (kgdb_info[sstep_cpu].task)
1505                         kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
1506                 else
1507                         kgdb_sstep_pid = 0;
1508         }
1509         /* Free kgdb_active */
1510         atomic_set(&kgdb_active, -1);
1511         touch_softlockup_watchdog_sync();
1512         clocksource_touch_watchdog();
1513         local_irq_restore(flags);
1514
1515         return error;
1516 }
1517
1518 /*
1519  * kgdb_handle_exception() - main entry point from a kernel exception
1520  *
1521  * Locking hierarchy:
1522  *      interface locks, if any (begin_session)
1523  *      kgdb lock (kgdb_active)
1524  */
1525 int
1526 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1527 {
1528         struct kgdb_state kgdb_var;
1529         struct kgdb_state *ks = &kgdb_var;
1530         int ret;
1531
1532         ks->cpu                 = raw_smp_processor_id();
1533         ks->ex_vector           = evector;
1534         ks->signo               = signo;
1535         ks->ex_vector           = evector;
1536         ks->err_code            = ecode;
1537         ks->kgdb_usethreadid    = 0;
1538         ks->linux_regs          = regs;
1539
1540         if (kgdb_reenter_check(ks))
1541                 return 0; /* Ouch, double exception ! */
1542         kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER;
1543         ret = kgdb_cpu_enter(ks, regs);
1544         kgdb_info[ks->cpu].exception_state &= ~DCPU_WANT_MASTER;
1545         return ret;
1546 }
1547
1548 int kgdb_nmicallback(int cpu, void *regs)
1549 {
1550 #ifdef CONFIG_SMP
1551         struct kgdb_state kgdb_var;
1552         struct kgdb_state *ks = &kgdb_var;
1553
1554         memset(ks, 0, sizeof(struct kgdb_state));
1555         ks->cpu                 = cpu;
1556         ks->linux_regs          = regs;
1557
1558         if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1559             atomic_read(&kgdb_active) != -1 &&
1560             atomic_read(&kgdb_active) != cpu) {
1561                 kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
1562                 kgdb_cpu_enter(ks, regs);
1563                 kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE;
1564                 return 0;
1565         }
1566 #endif
1567         return 1;
1568 }
1569
1570 static void kgdb_console_write(struct console *co, const char *s,
1571    unsigned count)
1572 {
1573         unsigned long flags;
1574
1575         /* If we're debugging, or KGDB has not connected, don't try
1576          * and print. */
1577         if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
1578                 return;
1579
1580         local_irq_save(flags);
1581         kgdb_msg_write(s, count);
1582         local_irq_restore(flags);
1583 }
1584
1585 static struct console kgdbcons = {
1586         .name           = "kgdb",
1587         .write          = kgdb_console_write,
1588         .flags          = CON_PRINTBUFFER | CON_ENABLED,
1589         .index          = -1,
1590 };
1591
1592 #ifdef CONFIG_MAGIC_SYSRQ
1593 static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1594 {
1595         if (!kgdb_io_ops) {
1596                 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1597                 return;
1598         }
1599         if (!kgdb_connected)
1600                 printk(KERN_CRIT "Entering KGDB\n");
1601
1602         kgdb_breakpoint();
1603 }
1604
1605 static struct sysrq_key_op sysrq_gdb_op = {
1606         .handler        = sysrq_handle_gdb,
1607         .help_msg       = "debug(G)",
1608         .action_msg     = "DEBUG",
1609 };
1610 #endif
1611
1612 static void kgdb_register_callbacks(void)
1613 {
1614         if (!kgdb_io_module_registered) {
1615                 kgdb_io_module_registered = 1;
1616                 kgdb_arch_init();
1617 #ifdef CONFIG_MAGIC_SYSRQ
1618                 register_sysrq_key('g', &sysrq_gdb_op);
1619 #endif
1620                 if (kgdb_use_con && !kgdb_con_registered) {
1621                         register_console(&kgdbcons);
1622                         kgdb_con_registered = 1;
1623                 }
1624         }
1625 }
1626
1627 static void kgdb_unregister_callbacks(void)
1628 {
1629         /*
1630          * When this routine is called KGDB should unregister from the
1631          * panic handler and clean up, making sure it is not handling any
1632          * break exceptions at the time.
1633          */
1634         if (kgdb_io_module_registered) {
1635                 kgdb_io_module_registered = 0;
1636                 kgdb_arch_exit();
1637 #ifdef CONFIG_MAGIC_SYSRQ
1638                 unregister_sysrq_key('g', &sysrq_gdb_op);
1639 #endif
1640                 if (kgdb_con_registered) {
1641                         unregister_console(&kgdbcons);
1642                         kgdb_con_registered = 0;
1643                 }
1644         }
1645 }
1646
1647 static void kgdb_initial_breakpoint(void)
1648 {
1649         kgdb_break_asap = 0;
1650
1651         printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1652         kgdb_breakpoint();
1653 }
1654
1655 /**
1656  *      kgdb_register_io_module - register KGDB IO module
1657  *      @new_kgdb_io_ops: the io ops vector
1658  *
1659  *      Register it with the KGDB core.
1660  */
1661 int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1662 {
1663         int err;
1664
1665         spin_lock(&kgdb_registration_lock);
1666
1667         if (kgdb_io_ops) {
1668                 spin_unlock(&kgdb_registration_lock);
1669
1670                 printk(KERN_ERR "kgdb: Another I/O driver is already "
1671                                 "registered with KGDB.\n");
1672                 return -EBUSY;
1673         }
1674
1675         if (new_kgdb_io_ops->init) {
1676                 err = new_kgdb_io_ops->init();
1677                 if (err) {
1678                         spin_unlock(&kgdb_registration_lock);
1679                         return err;
1680                 }
1681         }
1682
1683         kgdb_io_ops = new_kgdb_io_ops;
1684
1685         spin_unlock(&kgdb_registration_lock);
1686
1687         printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1688                new_kgdb_io_ops->name);
1689
1690         /* Arm KGDB now. */
1691         kgdb_register_callbacks();
1692
1693         if (kgdb_break_asap)
1694                 kgdb_initial_breakpoint();
1695
1696         return 0;
1697 }
1698 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1699
1700 /**
1701  *      kkgdb_unregister_io_module - unregister KGDB IO module
1702  *      @old_kgdb_io_ops: the io ops vector
1703  *
1704  *      Unregister it with the KGDB core.
1705  */
1706 void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1707 {
1708         BUG_ON(kgdb_connected);
1709
1710         /*
1711          * KGDB is no longer able to communicate out, so
1712          * unregister our callbacks and reset state.
1713          */
1714         kgdb_unregister_callbacks();
1715
1716         spin_lock(&kgdb_registration_lock);
1717
1718         WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1719         kgdb_io_ops = NULL;
1720
1721         spin_unlock(&kgdb_registration_lock);
1722
1723         printk(KERN_INFO
1724                 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1725                 old_kgdb_io_ops->name);
1726 }
1727 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1728
1729 /**
1730  * kgdb_breakpoint - generate breakpoint exception
1731  *
1732  * This function will generate a breakpoint exception.  It is used at the
1733  * beginning of a program to sync up with a debugger and can be used
1734  * otherwise as a quick means to stop program execution and "break" into
1735  * the debugger.
1736  */
1737 void kgdb_breakpoint(void)
1738 {
1739         atomic_set(&kgdb_setting_breakpoint, 1);
1740         wmb(); /* Sync point before breakpoint */
1741         arch_kgdb_breakpoint();
1742         wmb(); /* Sync point after breakpoint */
1743         atomic_set(&kgdb_setting_breakpoint, 0);
1744 }
1745 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1746
1747 static int __init opt_kgdb_wait(char *str)
1748 {
1749         kgdb_break_asap = 1;
1750
1751         if (kgdb_io_module_registered)
1752                 kgdb_initial_breakpoint();
1753
1754         return 0;
1755 }
1756
1757 early_param("kgdbwait", opt_kgdb_wait);