95b89d4cb8f18f1595a430e0e6eaf8ac5f513487
[sfrench/cifs-2.6.git] / arch / x86 / kernel / kgdb.c
1 /*
2  * This program is free software; you can redistribute it and/or modify it
3  * under the terms of the GNU General Public License as published by the
4  * Free Software Foundation; either version 2, or (at your option) any
5  * later version.
6  *
7  * This program is distributed in the hope that it will be useful, but
8  * WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
10  * General Public License for more details.
11  *
12  */
13
14 /*
15  * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com>
16  * Copyright (C) 2000-2001 VERITAS Software Corporation.
17  * Copyright (C) 2002 Andi Kleen, SuSE Labs
18  * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
19  * Copyright (C) 2007 MontaVista Software, Inc.
20  * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc.
21  */
22 /****************************************************************************
23  *  Contributor:     Lake Stevens Instrument Division$
24  *  Written by:      Glenn Engel $
25  *  Updated by:      Amit Kale<akale@veritas.com>
26  *  Updated by:      Tom Rini <trini@kernel.crashing.org>
27  *  Updated by:      Jason Wessel <jason.wessel@windriver.com>
28  *  Modified for 386 by Jim Kingdon, Cygnus Support.
29  *  Origianl kgdb, compatibility with 2.1.xx kernel by
30  *  David Grothe <dave@gcom.com>
31  *  Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
32  *  X86_64 changes from Andi Kleen's patch merged by Jim Houston
33  */
34 #include <linux/spinlock.h>
35 #include <linux/kdebug.h>
36 #include <linux/string.h>
37 #include <linux/kernel.h>
38 #include <linux/ptrace.h>
39 #include <linux/sched.h>
40 #include <linux/delay.h>
41 #include <linux/kgdb.h>
42 #include <linux/init.h>
43 #include <linux/smp.h>
44 #include <linux/nmi.h>
45 #include <linux/hw_breakpoint.h>
46
47 #include <asm/debugreg.h>
48 #include <asm/apicdef.h>
49 #include <asm/system.h>
50 #include <asm/apic.h>
51
52 /**
53  *      pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
54  *      @gdb_regs: A pointer to hold the registers in the order GDB wants.
55  *      @regs: The &struct pt_regs of the current process.
56  *
57  *      Convert the pt_regs in @regs into the format for registers that
58  *      GDB expects, stored in @gdb_regs.
59  */
60 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
61 {
62 #ifndef CONFIG_X86_32
63         u32 *gdb_regs32 = (u32 *)gdb_regs;
64 #endif
65         gdb_regs[GDB_AX]        = regs->ax;
66         gdb_regs[GDB_BX]        = regs->bx;
67         gdb_regs[GDB_CX]        = regs->cx;
68         gdb_regs[GDB_DX]        = regs->dx;
69         gdb_regs[GDB_SI]        = regs->si;
70         gdb_regs[GDB_DI]        = regs->di;
71         gdb_regs[GDB_BP]        = regs->bp;
72         gdb_regs[GDB_PC]        = regs->ip;
73 #ifdef CONFIG_X86_32
74         gdb_regs[GDB_PS]        = regs->flags;
75         gdb_regs[GDB_DS]        = regs->ds;
76         gdb_regs[GDB_ES]        = regs->es;
77         gdb_regs[GDB_CS]        = regs->cs;
78         gdb_regs[GDB_FS]        = 0xFFFF;
79         gdb_regs[GDB_GS]        = 0xFFFF;
80         if (user_mode_vm(regs)) {
81                 gdb_regs[GDB_SS] = regs->ss;
82                 gdb_regs[GDB_SP] = regs->sp;
83         } else {
84                 gdb_regs[GDB_SS] = __KERNEL_DS;
85                 gdb_regs[GDB_SP] = kernel_stack_pointer(regs);
86         }
87 #else
88         gdb_regs[GDB_R8]        = regs->r8;
89         gdb_regs[GDB_R9]        = regs->r9;
90         gdb_regs[GDB_R10]       = regs->r10;
91         gdb_regs[GDB_R11]       = regs->r11;
92         gdb_regs[GDB_R12]       = regs->r12;
93         gdb_regs[GDB_R13]       = regs->r13;
94         gdb_regs[GDB_R14]       = regs->r14;
95         gdb_regs[GDB_R15]       = regs->r15;
96         gdb_regs32[GDB_PS]      = regs->flags;
97         gdb_regs32[GDB_CS]      = regs->cs;
98         gdb_regs32[GDB_SS]      = regs->ss;
99         gdb_regs[GDB_SP]        = kernel_stack_pointer(regs);
100 #endif
101 }
102
103 /**
104  *      sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
105  *      @gdb_regs: A pointer to hold the registers in the order GDB wants.
106  *      @p: The &struct task_struct of the desired process.
107  *
108  *      Convert the register values of the sleeping process in @p to
109  *      the format that GDB expects.
110  *      This function is called when kgdb does not have access to the
111  *      &struct pt_regs and therefore it should fill the gdb registers
112  *      @gdb_regs with what has been saved in &struct thread_struct
113  *      thread field during switch_to.
114  */
115 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
116 {
117 #ifndef CONFIG_X86_32
118         u32 *gdb_regs32 = (u32 *)gdb_regs;
119 #endif
120         gdb_regs[GDB_AX]        = 0;
121         gdb_regs[GDB_BX]        = 0;
122         gdb_regs[GDB_CX]        = 0;
123         gdb_regs[GDB_DX]        = 0;
124         gdb_regs[GDB_SI]        = 0;
125         gdb_regs[GDB_DI]        = 0;
126         gdb_regs[GDB_BP]        = *(unsigned long *)p->thread.sp;
127 #ifdef CONFIG_X86_32
128         gdb_regs[GDB_DS]        = __KERNEL_DS;
129         gdb_regs[GDB_ES]        = __KERNEL_DS;
130         gdb_regs[GDB_PS]        = 0;
131         gdb_regs[GDB_CS]        = __KERNEL_CS;
132         gdb_regs[GDB_PC]        = p->thread.ip;
133         gdb_regs[GDB_SS]        = __KERNEL_DS;
134         gdb_regs[GDB_FS]        = 0xFFFF;
135         gdb_regs[GDB_GS]        = 0xFFFF;
136 #else
137         gdb_regs32[GDB_PS]      = *(unsigned long *)(p->thread.sp + 8);
138         gdb_regs32[GDB_CS]      = __KERNEL_CS;
139         gdb_regs32[GDB_SS]      = __KERNEL_DS;
140         gdb_regs[GDB_PC]        = 0;
141         gdb_regs[GDB_R8]        = 0;
142         gdb_regs[GDB_R9]        = 0;
143         gdb_regs[GDB_R10]       = 0;
144         gdb_regs[GDB_R11]       = 0;
145         gdb_regs[GDB_R12]       = 0;
146         gdb_regs[GDB_R13]       = 0;
147         gdb_regs[GDB_R14]       = 0;
148         gdb_regs[GDB_R15]       = 0;
149 #endif
150         gdb_regs[GDB_SP]        = p->thread.sp;
151 }
152
153 /**
154  *      gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
155  *      @gdb_regs: A pointer to hold the registers we've received from GDB.
156  *      @regs: A pointer to a &struct pt_regs to hold these values in.
157  *
158  *      Convert the GDB regs in @gdb_regs into the pt_regs, and store them
159  *      in @regs.
160  */
161 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
162 {
163 #ifndef CONFIG_X86_32
164         u32 *gdb_regs32 = (u32 *)gdb_regs;
165 #endif
166         regs->ax                = gdb_regs[GDB_AX];
167         regs->bx                = gdb_regs[GDB_BX];
168         regs->cx                = gdb_regs[GDB_CX];
169         regs->dx                = gdb_regs[GDB_DX];
170         regs->si                = gdb_regs[GDB_SI];
171         regs->di                = gdb_regs[GDB_DI];
172         regs->bp                = gdb_regs[GDB_BP];
173         regs->ip                = gdb_regs[GDB_PC];
174 #ifdef CONFIG_X86_32
175         regs->flags             = gdb_regs[GDB_PS];
176         regs->ds                = gdb_regs[GDB_DS];
177         regs->es                = gdb_regs[GDB_ES];
178         regs->cs                = gdb_regs[GDB_CS];
179 #else
180         regs->r8                = gdb_regs[GDB_R8];
181         regs->r9                = gdb_regs[GDB_R9];
182         regs->r10               = gdb_regs[GDB_R10];
183         regs->r11               = gdb_regs[GDB_R11];
184         regs->r12               = gdb_regs[GDB_R12];
185         regs->r13               = gdb_regs[GDB_R13];
186         regs->r14               = gdb_regs[GDB_R14];
187         regs->r15               = gdb_regs[GDB_R15];
188         regs->flags             = gdb_regs32[GDB_PS];
189         regs->cs                = gdb_regs32[GDB_CS];
190         regs->ss                = gdb_regs32[GDB_SS];
191 #endif
192 }
193
194 static struct hw_breakpoint {
195         unsigned                enabled;
196         unsigned long           addr;
197         int                     len;
198         int                     type;
199         struct perf_event       **pev;
200 } breakinfo[4];
201
202 static void kgdb_correct_hw_break(void)
203 {
204         int breakno;
205
206         for (breakno = 0; breakno < 4; breakno++) {
207                 struct perf_event *bp;
208                 struct arch_hw_breakpoint *info;
209                 int val;
210                 int cpu = raw_smp_processor_id();
211                 if (!breakinfo[breakno].enabled)
212                         continue;
213                 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
214                 info = counter_arch_bp(bp);
215                 if (bp->attr.disabled != 1)
216                         continue;
217                 bp->attr.bp_addr = breakinfo[breakno].addr;
218                 bp->attr.bp_len = breakinfo[breakno].len;
219                 bp->attr.bp_type = breakinfo[breakno].type;
220                 info->address = breakinfo[breakno].addr;
221                 info->len = breakinfo[breakno].len;
222                 info->type = breakinfo[breakno].type;
223                 val = arch_install_hw_breakpoint(bp);
224                 if (!val)
225                         bp->attr.disabled = 0;
226         }
227         hw_breakpoint_restore();
228 }
229
230 static int hw_break_reserve_slot(int breakno)
231 {
232         int cpu;
233         int cnt = 0;
234         struct perf_event **pevent;
235
236         for_each_online_cpu(cpu) {
237                 cnt++;
238                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
239                 if (dbg_reserve_bp_slot(*pevent))
240                         goto fail;
241         }
242
243         return 0;
244
245 fail:
246         for_each_online_cpu(cpu) {
247                 cnt--;
248                 if (!cnt)
249                         break;
250                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
251                 dbg_release_bp_slot(*pevent);
252         }
253         return -1;
254 }
255
256 static int hw_break_release_slot(int breakno)
257 {
258         struct perf_event **pevent;
259         int cpu;
260
261         for_each_online_cpu(cpu) {
262                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
263                 if (dbg_release_bp_slot(*pevent))
264                         /*
265                          * The debugger is responisble for handing the retry on
266                          * remove failure.
267                          */
268                         return -1;
269         }
270         return 0;
271 }
272
273 static int
274 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
275 {
276         int i;
277
278         for (i = 0; i < 4; i++)
279                 if (breakinfo[i].addr == addr && breakinfo[i].enabled)
280                         break;
281         if (i == 4)
282                 return -1;
283
284         if (hw_break_release_slot(i)) {
285                 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
286                 return -1;
287         }
288         breakinfo[i].enabled = 0;
289
290         return 0;
291 }
292
293 static void kgdb_remove_all_hw_break(void)
294 {
295         int i;
296         int cpu = raw_smp_processor_id();
297         struct perf_event *bp;
298
299         for (i = 0; i < 4; i++) {
300                 if (!breakinfo[i].enabled)
301                         continue;
302                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
303                 if (bp->attr.disabled == 1)
304                         continue;
305                 arch_uninstall_hw_breakpoint(bp);
306                 bp->attr.disabled = 1;
307         }
308 }
309
310 static int
311 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
312 {
313         int i;
314
315         for (i = 0; i < 4; i++)
316                 if (!breakinfo[i].enabled)
317                         break;
318         if (i == 4)
319                 return -1;
320
321         switch (bptype) {
322         case BP_HARDWARE_BREAKPOINT:
323                 len = 1;
324                 breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
325                 break;
326         case BP_WRITE_WATCHPOINT:
327                 breakinfo[i].type = X86_BREAKPOINT_WRITE;
328                 break;
329         case BP_ACCESS_WATCHPOINT:
330                 breakinfo[i].type = X86_BREAKPOINT_RW;
331                 break;
332         default:
333                 return -1;
334         }
335         switch (len) {
336         case 1:
337                 breakinfo[i].len = X86_BREAKPOINT_LEN_1;
338                 break;
339         case 2:
340                 breakinfo[i].len = X86_BREAKPOINT_LEN_2;
341                 break;
342         case 4:
343                 breakinfo[i].len = X86_BREAKPOINT_LEN_4;
344                 break;
345 #ifdef CONFIG_X86_64
346         case 8:
347                 breakinfo[i].len = X86_BREAKPOINT_LEN_8;
348                 break;
349 #endif
350         default:
351                 return -1;
352         }
353         breakinfo[i].addr = addr;
354         if (hw_break_reserve_slot(i)) {
355                 breakinfo[i].addr = 0;
356                 return -1;
357         }
358         breakinfo[i].enabled = 1;
359
360         return 0;
361 }
362
363 /**
364  *      kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
365  *      @regs: Current &struct pt_regs.
366  *
367  *      This function will be called if the particular architecture must
368  *      disable hardware debugging while it is processing gdb packets or
369  *      handling exception.
370  */
371 void kgdb_disable_hw_debug(struct pt_regs *regs)
372 {
373         int i;
374         int cpu = raw_smp_processor_id();
375         struct perf_event *bp;
376
377         /* Disable hardware debugging while we are in kgdb: */
378         set_debugreg(0UL, 7);
379         for (i = 0; i < 4; i++) {
380                 if (!breakinfo[i].enabled)
381                         continue;
382                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
383                 if (bp->attr.disabled == 1)
384                         continue;
385                 arch_uninstall_hw_breakpoint(bp);
386                 bp->attr.disabled = 1;
387         }
388 }
389
390 #ifdef CONFIG_SMP
391 /**
392  *      kgdb_roundup_cpus - Get other CPUs into a holding pattern
393  *      @flags: Current IRQ state
394  *
395  *      On SMP systems, we need to get the attention of the other CPUs
396  *      and get them be in a known state.  This should do what is needed
397  *      to get the other CPUs to call kgdb_wait(). Note that on some arches,
398  *      the NMI approach is not used for rounding up all the CPUs. For example,
399  *      in case of MIPS, smp_call_function() is used to roundup CPUs. In
400  *      this case, we have to make sure that interrupts are enabled before
401  *      calling smp_call_function(). The argument to this function is
402  *      the flags that will be used when restoring the interrupts. There is
403  *      local_irq_save() call before kgdb_roundup_cpus().
404  *
405  *      On non-SMP systems, this is not called.
406  */
407 void kgdb_roundup_cpus(unsigned long flags)
408 {
409         apic->send_IPI_allbutself(APIC_DM_NMI);
410 }
411 #endif
412
413 /**
414  *      kgdb_arch_handle_exception - Handle architecture specific GDB packets.
415  *      @vector: The error vector of the exception that happened.
416  *      @signo: The signal number of the exception that happened.
417  *      @err_code: The error code of the exception that happened.
418  *      @remcom_in_buffer: The buffer of the packet we have read.
419  *      @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
420  *      @regs: The &struct pt_regs of the current process.
421  *
422  *      This function MUST handle the 'c' and 's' command packets,
423  *      as well packets to set / remove a hardware breakpoint, if used.
424  *      If there are additional packets which the hardware needs to handle,
425  *      they are handled here.  The code should return -1 if it wants to
426  *      process more packets, and a %0 or %1 if it wants to exit from the
427  *      kgdb callback.
428  */
429 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
430                                char *remcomInBuffer, char *remcomOutBuffer,
431                                struct pt_regs *linux_regs)
432 {
433         unsigned long addr;
434         char *ptr;
435         int newPC;
436
437         switch (remcomInBuffer[0]) {
438         case 'c':
439         case 's':
440                 /* try to read optional parameter, pc unchanged if no parm */
441                 ptr = &remcomInBuffer[1];
442                 if (kgdb_hex2long(&ptr, &addr))
443                         linux_regs->ip = addr;
444         case 'D':
445         case 'k':
446                 newPC = linux_regs->ip;
447
448                 /* clear the trace bit */
449                 linux_regs->flags &= ~X86_EFLAGS_TF;
450                 atomic_set(&kgdb_cpu_doing_single_step, -1);
451
452                 /* set the trace bit if we're stepping */
453                 if (remcomInBuffer[0] == 's') {
454                         linux_regs->flags |= X86_EFLAGS_TF;
455                         atomic_set(&kgdb_cpu_doing_single_step,
456                                    raw_smp_processor_id());
457                 }
458
459                 kgdb_correct_hw_break();
460
461                 return 0;
462         }
463
464         /* this means that we do not want to exit from the handler: */
465         return -1;
466 }
467
468 static inline int
469 single_step_cont(struct pt_regs *regs, struct die_args *args)
470 {
471         /*
472          * Single step exception from kernel space to user space so
473          * eat the exception and continue the process:
474          */
475         printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
476                         "resuming...\n");
477         kgdb_arch_handle_exception(args->trapnr, args->signr,
478                                    args->err, "c", "", regs);
479         /*
480          * Reset the BS bit in dr6 (pointed by args->err) to
481          * denote completion of processing
482          */
483         (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
484
485         return NOTIFY_STOP;
486 }
487
488 static int was_in_debug_nmi[NR_CPUS];
489
490 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
491 {
492         struct pt_regs *regs = args->regs;
493
494         switch (cmd) {
495         case DIE_NMI:
496                 if (atomic_read(&kgdb_active) != -1) {
497                         /* KGDB CPU roundup */
498                         kgdb_nmicallback(raw_smp_processor_id(), regs);
499                         was_in_debug_nmi[raw_smp_processor_id()] = 1;
500                         touch_nmi_watchdog();
501                         return NOTIFY_STOP;
502                 }
503                 return NOTIFY_DONE;
504
505         case DIE_NMI_IPI:
506                 /* Just ignore, we will handle the roundup on DIE_NMI. */
507                 return NOTIFY_DONE;
508
509         case DIE_NMIUNKNOWN:
510                 if (was_in_debug_nmi[raw_smp_processor_id()]) {
511                         was_in_debug_nmi[raw_smp_processor_id()] = 0;
512                         return NOTIFY_STOP;
513                 }
514                 return NOTIFY_DONE;
515
516         case DIE_NMIWATCHDOG:
517                 if (atomic_read(&kgdb_active) != -1) {
518                         /* KGDB CPU roundup: */
519                         kgdb_nmicallback(raw_smp_processor_id(), regs);
520                         return NOTIFY_STOP;
521                 }
522                 /* Enter debugger: */
523                 break;
524
525         case DIE_DEBUG:
526                 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
527                         if (user_mode(regs))
528                                 return single_step_cont(regs, args);
529                         break;
530                 } else if (test_thread_flag(TIF_SINGLESTEP))
531                         /* This means a user thread is single stepping
532                          * a system call which should be ignored
533                          */
534                         return NOTIFY_DONE;
535                 /* fall through */
536         default:
537                 if (user_mode(regs))
538                         return NOTIFY_DONE;
539         }
540
541         if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
542                 return NOTIFY_DONE;
543
544         /* Must touch watchdog before return to normal operation */
545         touch_nmi_watchdog();
546         return NOTIFY_STOP;
547 }
548
549 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
550 int kgdb_ll_trap(int cmd, const char *str,
551                  struct pt_regs *regs, long err, int trap, int sig)
552 {
553         struct die_args args = {
554                 .regs   = regs,
555                 .str    = str,
556                 .err    = err,
557                 .trapnr = trap,
558                 .signr  = sig,
559
560         };
561
562         if (!kgdb_io_module_registered)
563                 return NOTIFY_DONE;
564
565         return __kgdb_notify(&args, cmd);
566 }
567 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
568
569 static int
570 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
571 {
572         unsigned long flags;
573         int ret;
574
575         local_irq_save(flags);
576         ret = __kgdb_notify(ptr, cmd);
577         local_irq_restore(flags);
578
579         return ret;
580 }
581
582 static struct notifier_block kgdb_notifier = {
583         .notifier_call  = kgdb_notify,
584
585         /*
586          * Lowest-prio notifier priority, we want to be notified last:
587          */
588         .priority       = -INT_MAX,
589 };
590
591 /**
592  *      kgdb_arch_init - Perform any architecture specific initalization.
593  *
594  *      This function will handle the initalization of any architecture
595  *      specific callbacks.
596  */
597 int kgdb_arch_init(void)
598 {
599         int i, cpu;
600         int ret;
601         struct perf_event_attr attr;
602         struct perf_event **pevent;
603
604         ret = register_die_notifier(&kgdb_notifier);
605         if (ret != 0)
606                 return ret;
607         /*
608          * Pre-allocate the hw breakpoint structions in the non-atomic
609          * portion of kgdb because this operation requires mutexs to
610          * complete.
611          */
612         hw_breakpoint_init(&attr);
613         attr.bp_addr = (unsigned long)kgdb_arch_init;
614         attr.bp_len = HW_BREAKPOINT_LEN_1;
615         attr.bp_type = HW_BREAKPOINT_W;
616         attr.disabled = 1;
617         for (i = 0; i < 4; i++) {
618                 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
619                 if (IS_ERR(breakinfo[i].pev)) {
620                         printk(KERN_ERR "kgdb: Could not allocate hw breakpoints\n");
621                         breakinfo[i].pev = NULL;
622                         kgdb_arch_exit();
623                         return -1;
624                 }
625                 for_each_online_cpu(cpu) {
626                         pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
627                         pevent[0]->hw.sample_period = 1;
628                         if (pevent[0]->destroy != NULL) {
629                                 pevent[0]->destroy = NULL;
630                                 release_bp_slot(*pevent);
631                         }
632                 }
633         }
634         return ret;
635 }
636
637 /**
638  *      kgdb_arch_exit - Perform any architecture specific uninitalization.
639  *
640  *      This function will handle the uninitalization of any architecture
641  *      specific callbacks, for dynamic registration and unregistration.
642  */
643 void kgdb_arch_exit(void)
644 {
645         int i;
646         for (i = 0; i < 4; i++) {
647                 if (breakinfo[i].pev) {
648                         unregister_wide_hw_breakpoint(breakinfo[i].pev);
649                         breakinfo[i].pev = NULL;
650                 }
651         }
652         unregister_die_notifier(&kgdb_notifier);
653 }
654
655 /**
656  *
657  *      kgdb_skipexception - Bail out of KGDB when we've been triggered.
658  *      @exception: Exception vector number
659  *      @regs: Current &struct pt_regs.
660  *
661  *      On some architectures we need to skip a breakpoint exception when
662  *      it occurs after a breakpoint has been removed.
663  *
664  * Skip an int3 exception when it occurs after a breakpoint has been
665  * removed. Backtrack eip by 1 since the int3 would have caused it to
666  * increment by 1.
667  */
668 int kgdb_skipexception(int exception, struct pt_regs *regs)
669 {
670         if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
671                 regs->ip -= 1;
672                 return 1;
673         }
674         return 0;
675 }
676
677 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
678 {
679         if (exception == 3)
680                 return instruction_pointer(regs) - 1;
681         return instruction_pointer(regs);
682 }
683
684 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
685 {
686         regs->ip = ip;
687 }
688
689 struct kgdb_arch arch_kgdb_ops = {
690         /* Breakpoint instruction: */
691         .gdb_bpt_instr          = { 0xcc },
692         .flags                  = KGDB_HW_BREAKPOINT,
693         .set_hw_breakpoint      = kgdb_set_hw_break,
694         .remove_hw_breakpoint   = kgdb_remove_hw_break,
695         .remove_all_hw_break    = kgdb_remove_all_hw_break,
696         .correct_hw_break       = kgdb_correct_hw_break,
697 };