Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-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
51 #include <asm/apic.h>
52
53 /*
54  * Put the error code here just in case the user cares:
55  */
56 static int gdb_x86errcode;
57
58 /*
59  * Likewise, the vector number here (since GDB only gets the signal
60  * number through the usual means, and that's not very specific):
61  */
62 static int gdb_x86vector = -1;
63
64 /**
65  *      pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
66  *      @gdb_regs: A pointer to hold the registers in the order GDB wants.
67  *      @regs: The &struct pt_regs of the current process.
68  *
69  *      Convert the pt_regs in @regs into the format for registers that
70  *      GDB expects, stored in @gdb_regs.
71  */
72 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
73 {
74 #ifndef CONFIG_X86_32
75         u32 *gdb_regs32 = (u32 *)gdb_regs;
76 #endif
77         gdb_regs[GDB_AX]        = regs->ax;
78         gdb_regs[GDB_BX]        = regs->bx;
79         gdb_regs[GDB_CX]        = regs->cx;
80         gdb_regs[GDB_DX]        = regs->dx;
81         gdb_regs[GDB_SI]        = regs->si;
82         gdb_regs[GDB_DI]        = regs->di;
83         gdb_regs[GDB_BP]        = regs->bp;
84         gdb_regs[GDB_PC]        = regs->ip;
85 #ifdef CONFIG_X86_32
86         gdb_regs[GDB_PS]        = regs->flags;
87         gdb_regs[GDB_DS]        = regs->ds;
88         gdb_regs[GDB_ES]        = regs->es;
89         gdb_regs[GDB_CS]        = regs->cs;
90         gdb_regs[GDB_FS]        = 0xFFFF;
91         gdb_regs[GDB_GS]        = 0xFFFF;
92         if (user_mode_vm(regs)) {
93                 gdb_regs[GDB_SS] = regs->ss;
94                 gdb_regs[GDB_SP] = regs->sp;
95         } else {
96                 gdb_regs[GDB_SS] = __KERNEL_DS;
97                 gdb_regs[GDB_SP] = kernel_stack_pointer(regs);
98         }
99 #else
100         gdb_regs[GDB_R8]        = regs->r8;
101         gdb_regs[GDB_R9]        = regs->r9;
102         gdb_regs[GDB_R10]       = regs->r10;
103         gdb_regs[GDB_R11]       = regs->r11;
104         gdb_regs[GDB_R12]       = regs->r12;
105         gdb_regs[GDB_R13]       = regs->r13;
106         gdb_regs[GDB_R14]       = regs->r14;
107         gdb_regs[GDB_R15]       = regs->r15;
108         gdb_regs32[GDB_PS]      = regs->flags;
109         gdb_regs32[GDB_CS]      = regs->cs;
110         gdb_regs32[GDB_SS]      = regs->ss;
111         gdb_regs[GDB_SP]        = kernel_stack_pointer(regs);
112 #endif
113 }
114
115 /**
116  *      sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
117  *      @gdb_regs: A pointer to hold the registers in the order GDB wants.
118  *      @p: The &struct task_struct of the desired process.
119  *
120  *      Convert the register values of the sleeping process in @p to
121  *      the format that GDB expects.
122  *      This function is called when kgdb does not have access to the
123  *      &struct pt_regs and therefore it should fill the gdb registers
124  *      @gdb_regs with what has been saved in &struct thread_struct
125  *      thread field during switch_to.
126  */
127 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
128 {
129 #ifndef CONFIG_X86_32
130         u32 *gdb_regs32 = (u32 *)gdb_regs;
131 #endif
132         gdb_regs[GDB_AX]        = 0;
133         gdb_regs[GDB_BX]        = 0;
134         gdb_regs[GDB_CX]        = 0;
135         gdb_regs[GDB_DX]        = 0;
136         gdb_regs[GDB_SI]        = 0;
137         gdb_regs[GDB_DI]        = 0;
138         gdb_regs[GDB_BP]        = *(unsigned long *)p->thread.sp;
139 #ifdef CONFIG_X86_32
140         gdb_regs[GDB_DS]        = __KERNEL_DS;
141         gdb_regs[GDB_ES]        = __KERNEL_DS;
142         gdb_regs[GDB_PS]        = 0;
143         gdb_regs[GDB_CS]        = __KERNEL_CS;
144         gdb_regs[GDB_PC]        = p->thread.ip;
145         gdb_regs[GDB_SS]        = __KERNEL_DS;
146         gdb_regs[GDB_FS]        = 0xFFFF;
147         gdb_regs[GDB_GS]        = 0xFFFF;
148 #else
149         gdb_regs32[GDB_PS]      = *(unsigned long *)(p->thread.sp + 8);
150         gdb_regs32[GDB_CS]      = __KERNEL_CS;
151         gdb_regs32[GDB_SS]      = __KERNEL_DS;
152         gdb_regs[GDB_PC]        = 0;
153         gdb_regs[GDB_R8]        = 0;
154         gdb_regs[GDB_R9]        = 0;
155         gdb_regs[GDB_R10]       = 0;
156         gdb_regs[GDB_R11]       = 0;
157         gdb_regs[GDB_R12]       = 0;
158         gdb_regs[GDB_R13]       = 0;
159         gdb_regs[GDB_R14]       = 0;
160         gdb_regs[GDB_R15]       = 0;
161 #endif
162         gdb_regs[GDB_SP]        = p->thread.sp;
163 }
164
165 /**
166  *      gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
167  *      @gdb_regs: A pointer to hold the registers we've received from GDB.
168  *      @regs: A pointer to a &struct pt_regs to hold these values in.
169  *
170  *      Convert the GDB regs in @gdb_regs into the pt_regs, and store them
171  *      in @regs.
172  */
173 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
174 {
175 #ifndef CONFIG_X86_32
176         u32 *gdb_regs32 = (u32 *)gdb_regs;
177 #endif
178         regs->ax                = gdb_regs[GDB_AX];
179         regs->bx                = gdb_regs[GDB_BX];
180         regs->cx                = gdb_regs[GDB_CX];
181         regs->dx                = gdb_regs[GDB_DX];
182         regs->si                = gdb_regs[GDB_SI];
183         regs->di                = gdb_regs[GDB_DI];
184         regs->bp                = gdb_regs[GDB_BP];
185         regs->ip                = gdb_regs[GDB_PC];
186 #ifdef CONFIG_X86_32
187         regs->flags             = gdb_regs[GDB_PS];
188         regs->ds                = gdb_regs[GDB_DS];
189         regs->es                = gdb_regs[GDB_ES];
190         regs->cs                = gdb_regs[GDB_CS];
191 #else
192         regs->r8                = gdb_regs[GDB_R8];
193         regs->r9                = gdb_regs[GDB_R9];
194         regs->r10               = gdb_regs[GDB_R10];
195         regs->r11               = gdb_regs[GDB_R11];
196         regs->r12               = gdb_regs[GDB_R12];
197         regs->r13               = gdb_regs[GDB_R13];
198         regs->r14               = gdb_regs[GDB_R14];
199         regs->r15               = gdb_regs[GDB_R15];
200         regs->flags             = gdb_regs32[GDB_PS];
201         regs->cs                = gdb_regs32[GDB_CS];
202         regs->ss                = gdb_regs32[GDB_SS];
203 #endif
204 }
205
206 static struct hw_breakpoint {
207         unsigned                enabled;
208         unsigned long           addr;
209         int                     len;
210         int                     type;
211         struct perf_event       **pev;
212 } breakinfo[4];
213
214 static void kgdb_correct_hw_break(void)
215 {
216         int breakno;
217
218         for (breakno = 0; breakno < 4; breakno++) {
219                 struct perf_event *bp;
220                 struct arch_hw_breakpoint *info;
221                 int val;
222                 int cpu = raw_smp_processor_id();
223                 if (!breakinfo[breakno].enabled)
224                         continue;
225                 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
226                 info = counter_arch_bp(bp);
227                 if (bp->attr.disabled != 1)
228                         continue;
229                 bp->attr.bp_addr = breakinfo[breakno].addr;
230                 bp->attr.bp_len = breakinfo[breakno].len;
231                 bp->attr.bp_type = breakinfo[breakno].type;
232                 info->address = breakinfo[breakno].addr;
233                 info->len = breakinfo[breakno].len;
234                 info->type = breakinfo[breakno].type;
235                 val = arch_install_hw_breakpoint(bp);
236                 if (!val)
237                         bp->attr.disabled = 0;
238         }
239         hw_breakpoint_restore();
240 }
241
242 static int hw_break_reserve_slot(int breakno)
243 {
244         int cpu;
245         int cnt = 0;
246         struct perf_event **pevent;
247
248         for_each_online_cpu(cpu) {
249                 cnt++;
250                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
251                 if (dbg_reserve_bp_slot(*pevent))
252                         goto fail;
253         }
254
255         return 0;
256
257 fail:
258         for_each_online_cpu(cpu) {
259                 cnt--;
260                 if (!cnt)
261                         break;
262                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
263                 dbg_release_bp_slot(*pevent);
264         }
265         return -1;
266 }
267
268 static int hw_break_release_slot(int breakno)
269 {
270         struct perf_event **pevent;
271         int cpu;
272
273         for_each_online_cpu(cpu) {
274                 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
275                 if (dbg_release_bp_slot(*pevent))
276                         /*
277                          * The debugger is responisble for handing the retry on
278                          * remove failure.
279                          */
280                         return -1;
281         }
282         return 0;
283 }
284
285 static int
286 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
287 {
288         int i;
289
290         for (i = 0; i < 4; i++)
291                 if (breakinfo[i].addr == addr && breakinfo[i].enabled)
292                         break;
293         if (i == 4)
294                 return -1;
295
296         if (hw_break_release_slot(i)) {
297                 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
298                 return -1;
299         }
300         breakinfo[i].enabled = 0;
301
302         return 0;
303 }
304
305 static void kgdb_remove_all_hw_break(void)
306 {
307         int i;
308         int cpu = raw_smp_processor_id();
309         struct perf_event *bp;
310
311         for (i = 0; i < 4; i++) {
312                 if (!breakinfo[i].enabled)
313                         continue;
314                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
315                 if (bp->attr.disabled == 1)
316                         continue;
317                 arch_uninstall_hw_breakpoint(bp);
318                 bp->attr.disabled = 1;
319         }
320 }
321
322 static int
323 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
324 {
325         int i;
326
327         for (i = 0; i < 4; i++)
328                 if (!breakinfo[i].enabled)
329                         break;
330         if (i == 4)
331                 return -1;
332
333         switch (bptype) {
334         case BP_HARDWARE_BREAKPOINT:
335                 len = 1;
336                 breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
337                 break;
338         case BP_WRITE_WATCHPOINT:
339                 breakinfo[i].type = X86_BREAKPOINT_WRITE;
340                 break;
341         case BP_ACCESS_WATCHPOINT:
342                 breakinfo[i].type = X86_BREAKPOINT_RW;
343                 break;
344         default:
345                 return -1;
346         }
347         switch (len) {
348         case 1:
349                 breakinfo[i].len = X86_BREAKPOINT_LEN_1;
350                 break;
351         case 2:
352                 breakinfo[i].len = X86_BREAKPOINT_LEN_2;
353                 break;
354         case 4:
355                 breakinfo[i].len = X86_BREAKPOINT_LEN_4;
356                 break;
357 #ifdef CONFIG_X86_64
358         case 8:
359                 breakinfo[i].len = X86_BREAKPOINT_LEN_8;
360                 break;
361 #endif
362         default:
363                 return -1;
364         }
365         breakinfo[i].addr = addr;
366         if (hw_break_reserve_slot(i)) {
367                 breakinfo[i].addr = 0;
368                 return -1;
369         }
370         breakinfo[i].enabled = 1;
371
372         return 0;
373 }
374
375 /**
376  *      kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
377  *      @regs: Current &struct pt_regs.
378  *
379  *      This function will be called if the particular architecture must
380  *      disable hardware debugging while it is processing gdb packets or
381  *      handling exception.
382  */
383 void kgdb_disable_hw_debug(struct pt_regs *regs)
384 {
385         int i;
386         int cpu = raw_smp_processor_id();
387         struct perf_event *bp;
388
389         /* Disable hardware debugging while we are in kgdb: */
390         set_debugreg(0UL, 7);
391         for (i = 0; i < 4; i++) {
392                 if (!breakinfo[i].enabled)
393                         continue;
394                 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
395                 if (bp->attr.disabled == 1)
396                         continue;
397                 arch_uninstall_hw_breakpoint(bp);
398                 bp->attr.disabled = 1;
399         }
400 }
401
402 /**
403  *      kgdb_post_primary_code - Save error vector/code numbers.
404  *      @regs: Original pt_regs.
405  *      @e_vector: Original error vector.
406  *      @err_code: Original error code.
407  *
408  *      This is needed on architectures which support SMP and KGDB.
409  *      This function is called after all the slave cpus have been put
410  *      to a know spin state and the primary CPU has control over KGDB.
411  */
412 void kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
413 {
414         /* primary processor is completely in the debugger */
415         gdb_x86vector = e_vector;
416         gdb_x86errcode = err_code;
417 }
418
419 #ifdef CONFIG_SMP
420 /**
421  *      kgdb_roundup_cpus - Get other CPUs into a holding pattern
422  *      @flags: Current IRQ state
423  *
424  *      On SMP systems, we need to get the attention of the other CPUs
425  *      and get them be in a known state.  This should do what is needed
426  *      to get the other CPUs to call kgdb_wait(). Note that on some arches,
427  *      the NMI approach is not used for rounding up all the CPUs. For example,
428  *      in case of MIPS, smp_call_function() is used to roundup CPUs. In
429  *      this case, we have to make sure that interrupts are enabled before
430  *      calling smp_call_function(). The argument to this function is
431  *      the flags that will be used when restoring the interrupts. There is
432  *      local_irq_save() call before kgdb_roundup_cpus().
433  *
434  *      On non-SMP systems, this is not called.
435  */
436 void kgdb_roundup_cpus(unsigned long flags)
437 {
438         apic->send_IPI_allbutself(APIC_DM_NMI);
439 }
440 #endif
441
442 /**
443  *      kgdb_arch_handle_exception - Handle architecture specific GDB packets.
444  *      @vector: The error vector of the exception that happened.
445  *      @signo: The signal number of the exception that happened.
446  *      @err_code: The error code of the exception that happened.
447  *      @remcom_in_buffer: The buffer of the packet we have read.
448  *      @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
449  *      @regs: The &struct pt_regs of the current process.
450  *
451  *      This function MUST handle the 'c' and 's' command packets,
452  *      as well packets to set / remove a hardware breakpoint, if used.
453  *      If there are additional packets which the hardware needs to handle,
454  *      they are handled here.  The code should return -1 if it wants to
455  *      process more packets, and a %0 or %1 if it wants to exit from the
456  *      kgdb callback.
457  */
458 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
459                                char *remcomInBuffer, char *remcomOutBuffer,
460                                struct pt_regs *linux_regs)
461 {
462         unsigned long addr;
463         char *ptr;
464         int newPC;
465
466         switch (remcomInBuffer[0]) {
467         case 'c':
468         case 's':
469                 /* try to read optional parameter, pc unchanged if no parm */
470                 ptr = &remcomInBuffer[1];
471                 if (kgdb_hex2long(&ptr, &addr))
472                         linux_regs->ip = addr;
473         case 'D':
474         case 'k':
475                 newPC = linux_regs->ip;
476
477                 /* clear the trace bit */
478                 linux_regs->flags &= ~X86_EFLAGS_TF;
479                 atomic_set(&kgdb_cpu_doing_single_step, -1);
480
481                 /* set the trace bit if we're stepping */
482                 if (remcomInBuffer[0] == 's') {
483                         linux_regs->flags |= X86_EFLAGS_TF;
484                         atomic_set(&kgdb_cpu_doing_single_step,
485                                    raw_smp_processor_id());
486                 }
487
488                 kgdb_correct_hw_break();
489
490                 return 0;
491         }
492
493         /* this means that we do not want to exit from the handler: */
494         return -1;
495 }
496
497 static inline int
498 single_step_cont(struct pt_regs *regs, struct die_args *args)
499 {
500         /*
501          * Single step exception from kernel space to user space so
502          * eat the exception and continue the process:
503          */
504         printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
505                         "resuming...\n");
506         kgdb_arch_handle_exception(args->trapnr, args->signr,
507                                    args->err, "c", "", regs);
508         /*
509          * Reset the BS bit in dr6 (pointed by args->err) to
510          * denote completion of processing
511          */
512         (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
513
514         return NOTIFY_STOP;
515 }
516
517 static int was_in_debug_nmi[NR_CPUS];
518
519 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
520 {
521         struct pt_regs *regs = args->regs;
522
523         switch (cmd) {
524         case DIE_NMI:
525                 if (atomic_read(&kgdb_active) != -1) {
526                         /* KGDB CPU roundup */
527                         kgdb_nmicallback(raw_smp_processor_id(), regs);
528                         was_in_debug_nmi[raw_smp_processor_id()] = 1;
529                         touch_nmi_watchdog();
530                         return NOTIFY_STOP;
531                 }
532                 return NOTIFY_DONE;
533
534         case DIE_NMI_IPI:
535                 /* Just ignore, we will handle the roundup on DIE_NMI. */
536                 return NOTIFY_DONE;
537
538         case DIE_NMIUNKNOWN:
539                 if (was_in_debug_nmi[raw_smp_processor_id()]) {
540                         was_in_debug_nmi[raw_smp_processor_id()] = 0;
541                         return NOTIFY_STOP;
542                 }
543                 return NOTIFY_DONE;
544
545         case DIE_NMIWATCHDOG:
546                 if (atomic_read(&kgdb_active) != -1) {
547                         /* KGDB CPU roundup: */
548                         kgdb_nmicallback(raw_smp_processor_id(), regs);
549                         return NOTIFY_STOP;
550                 }
551                 /* Enter debugger: */
552                 break;
553
554         case DIE_DEBUG:
555                 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
556                         if (user_mode(regs))
557                                 return single_step_cont(regs, args);
558                         break;
559                 } else if (test_thread_flag(TIF_SINGLESTEP))
560                         /* This means a user thread is single stepping
561                          * a system call which should be ignored
562                          */
563                         return NOTIFY_DONE;
564                 /* fall through */
565         default:
566                 if (user_mode(regs))
567                         return NOTIFY_DONE;
568         }
569
570         if (kgdb_handle_exception(args->trapnr, args->signr, args->err, regs))
571                 return NOTIFY_DONE;
572
573         /* Must touch watchdog before return to normal operation */
574         touch_nmi_watchdog();
575         return NOTIFY_STOP;
576 }
577
578 static int
579 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
580 {
581         unsigned long flags;
582         int ret;
583
584         local_irq_save(flags);
585         ret = __kgdb_notify(ptr, cmd);
586         local_irq_restore(flags);
587
588         return ret;
589 }
590
591 static struct notifier_block kgdb_notifier = {
592         .notifier_call  = kgdb_notify,
593
594         /*
595          * Lowest-prio notifier priority, we want to be notified last:
596          */
597         .priority       = -INT_MAX,
598 };
599
600 /**
601  *      kgdb_arch_init - Perform any architecture specific initalization.
602  *
603  *      This function will handle the initalization of any architecture
604  *      specific callbacks.
605  */
606 int kgdb_arch_init(void)
607 {
608         int i, cpu;
609         int ret;
610         struct perf_event_attr attr;
611         struct perf_event **pevent;
612
613         ret = register_die_notifier(&kgdb_notifier);
614         if (ret != 0)
615                 return ret;
616         /*
617          * Pre-allocate the hw breakpoint structions in the non-atomic
618          * portion of kgdb because this operation requires mutexs to
619          * complete.
620          */
621         hw_breakpoint_init(&attr);
622         attr.bp_addr = (unsigned long)kgdb_arch_init;
623         attr.bp_len = HW_BREAKPOINT_LEN_1;
624         attr.bp_type = HW_BREAKPOINT_W;
625         attr.disabled = 1;
626         for (i = 0; i < 4; i++) {
627                 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
628                 if (IS_ERR(breakinfo[i].pev)) {
629                         printk(KERN_ERR "kgdb: Could not allocate hw breakpoints\n");
630                         breakinfo[i].pev = NULL;
631                         kgdb_arch_exit();
632                         return -1;
633                 }
634                 for_each_online_cpu(cpu) {
635                         pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
636                         pevent[0]->hw.sample_period = 1;
637                         if (pevent[0]->destroy != NULL) {
638                                 pevent[0]->destroy = NULL;
639                                 release_bp_slot(*pevent);
640                         }
641                 }
642         }
643         return ret;
644 }
645
646 /**
647  *      kgdb_arch_exit - Perform any architecture specific uninitalization.
648  *
649  *      This function will handle the uninitalization of any architecture
650  *      specific callbacks, for dynamic registration and unregistration.
651  */
652 void kgdb_arch_exit(void)
653 {
654         int i;
655         for (i = 0; i < 4; i++) {
656                 if (breakinfo[i].pev) {
657                         unregister_wide_hw_breakpoint(breakinfo[i].pev);
658                         breakinfo[i].pev = NULL;
659                 }
660         }
661         unregister_die_notifier(&kgdb_notifier);
662 }
663
664 /**
665  *
666  *      kgdb_skipexception - Bail out of KGDB when we've been triggered.
667  *      @exception: Exception vector number
668  *      @regs: Current &struct pt_regs.
669  *
670  *      On some architectures we need to skip a breakpoint exception when
671  *      it occurs after a breakpoint has been removed.
672  *
673  * Skip an int3 exception when it occurs after a breakpoint has been
674  * removed. Backtrack eip by 1 since the int3 would have caused it to
675  * increment by 1.
676  */
677 int kgdb_skipexception(int exception, struct pt_regs *regs)
678 {
679         if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
680                 regs->ip -= 1;
681                 return 1;
682         }
683         return 0;
684 }
685
686 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
687 {
688         if (exception == 3)
689                 return instruction_pointer(regs) - 1;
690         return instruction_pointer(regs);
691 }
692
693 struct kgdb_arch arch_kgdb_ops = {
694         /* Breakpoint instruction: */
695         .gdb_bpt_instr          = { 0xcc },
696         .flags                  = KGDB_HW_BREAKPOINT,
697         .set_hw_breakpoint      = kgdb_set_hw_break,
698         .remove_hw_breakpoint   = kgdb_remove_hw_break,
699         .remove_all_hw_break    = kgdb_remove_all_hw_break,
700         .correct_hw_break       = kgdb_correct_hw_break,
701 };