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
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.
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.
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
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>
47 #include <asm/debugreg.h>
48 #include <asm/apicdef.h>
49 #include <asm/system.h>
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.
57 * Convert the pt_regs in @regs into the format for registers that
58 * GDB expects, stored in @gdb_regs.
60 void pt_regs_to_gdb_regs(unsigned long *gdb_regs
, struct pt_regs
*regs
)
63 u32
*gdb_regs32
= (u32
*)gdb_regs
;
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
;
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
;
84 gdb_regs
[GDB_SS
] = __KERNEL_DS
;
85 gdb_regs
[GDB_SP
] = kernel_stack_pointer(regs
);
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
);
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.
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.
115 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs
, struct task_struct
*p
)
117 #ifndef CONFIG_X86_32
118 u32
*gdb_regs32
= (u32
*)gdb_regs
;
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
;
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;
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;
150 gdb_regs
[GDB_SP
] = p
->thread
.sp
;
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.
158 * Convert the GDB regs in @gdb_regs into the pt_regs, and store them
161 void gdb_regs_to_pt_regs(unsigned long *gdb_regs
, struct pt_regs
*regs
)
163 #ifndef CONFIG_X86_32
164 u32
*gdb_regs32
= (u32
*)gdb_regs
;
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
];
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
];
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
];
194 static struct hw_breakpoint
{
199 struct perf_event
**pev
;
202 static void kgdb_correct_hw_break(void)
206 for (breakno
= 0; breakno
< 4; breakno
++) {
207 struct perf_event
*bp
;
208 struct arch_hw_breakpoint
*info
;
210 int cpu
= raw_smp_processor_id();
211 if (!breakinfo
[breakno
].enabled
)
213 bp
= *per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
214 info
= counter_arch_bp(bp
);
215 if (bp
->attr
.disabled
!= 1)
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
);
225 bp
->attr
.disabled
= 0;
227 hw_breakpoint_restore();
230 static int hw_break_reserve_slot(int breakno
)
234 struct perf_event
**pevent
;
236 for_each_online_cpu(cpu
) {
238 pevent
= per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
239 if (dbg_reserve_bp_slot(*pevent
))
246 for_each_online_cpu(cpu
) {
250 pevent
= per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
251 dbg_release_bp_slot(*pevent
);
256 static int hw_break_release_slot(int breakno
)
258 struct perf_event
**pevent
;
261 for_each_online_cpu(cpu
) {
262 pevent
= per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
263 if (dbg_release_bp_slot(*pevent
))
265 * The debugger is responisble for handing the retry on
274 kgdb_remove_hw_break(unsigned long addr
, int len
, enum kgdb_bptype bptype
)
278 for (i
= 0; i
< 4; i
++)
279 if (breakinfo
[i
].addr
== addr
&& breakinfo
[i
].enabled
)
284 if (hw_break_release_slot(i
)) {
285 printk(KERN_ERR
"Cannot remove hw breakpoint at %lx\n", addr
);
288 breakinfo
[i
].enabled
= 0;
293 static void kgdb_remove_all_hw_break(void)
296 int cpu
= raw_smp_processor_id();
297 struct perf_event
*bp
;
299 for (i
= 0; i
< 4; i
++) {
300 if (!breakinfo
[i
].enabled
)
302 bp
= *per_cpu_ptr(breakinfo
[i
].pev
, cpu
);
303 if (bp
->attr
.disabled
== 1)
305 arch_uninstall_hw_breakpoint(bp
);
306 bp
->attr
.disabled
= 1;
311 kgdb_set_hw_break(unsigned long addr
, int len
, enum kgdb_bptype bptype
)
315 for (i
= 0; i
< 4; i
++)
316 if (!breakinfo
[i
].enabled
)
322 case BP_HARDWARE_BREAKPOINT
:
324 breakinfo
[i
].type
= X86_BREAKPOINT_EXECUTE
;
326 case BP_WRITE_WATCHPOINT
:
327 breakinfo
[i
].type
= X86_BREAKPOINT_WRITE
;
329 case BP_ACCESS_WATCHPOINT
:
330 breakinfo
[i
].type
= X86_BREAKPOINT_RW
;
337 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_1
;
340 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_2
;
343 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_4
;
347 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_8
;
353 breakinfo
[i
].addr
= addr
;
354 if (hw_break_reserve_slot(i
)) {
355 breakinfo
[i
].addr
= 0;
358 breakinfo
[i
].enabled
= 1;
364 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
365 * @regs: Current &struct pt_regs.
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.
371 void kgdb_disable_hw_debug(struct pt_regs
*regs
)
374 int cpu
= raw_smp_processor_id();
375 struct perf_event
*bp
;
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
)
382 bp
= *per_cpu_ptr(breakinfo
[i
].pev
, cpu
);
383 if (bp
->attr
.disabled
== 1)
385 arch_uninstall_hw_breakpoint(bp
);
386 bp
->attr
.disabled
= 1;
392 * kgdb_roundup_cpus - Get other CPUs into a holding pattern
393 * @flags: Current IRQ state
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().
405 * On non-SMP systems, this is not called.
407 void kgdb_roundup_cpus(unsigned long flags
)
409 apic
->send_IPI_allbutself(APIC_DM_NMI
);
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.
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
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
)
437 switch (remcomInBuffer
[0]) {
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
;
446 newPC
= linux_regs
->ip
;
448 /* clear the trace bit */
449 linux_regs
->flags
&= ~X86_EFLAGS_TF
;
450 atomic_set(&kgdb_cpu_doing_single_step
, -1);
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());
459 kgdb_correct_hw_break();
464 /* this means that we do not want to exit from the handler: */
469 single_step_cont(struct pt_regs
*regs
, struct die_args
*args
)
472 * Single step exception from kernel space to user space so
473 * eat the exception and continue the process:
475 printk(KERN_ERR
"KGDB: trap/step from kernel to user space, "
477 kgdb_arch_handle_exception(args
->trapnr
, args
->signr
,
478 args
->err
, "c", "", regs
);
480 * Reset the BS bit in dr6 (pointed by args->err) to
481 * denote completion of processing
483 (*(unsigned long *)ERR_PTR(args
->err
)) &= ~DR_STEP
;
488 static int was_in_debug_nmi
[NR_CPUS
];
490 static int __kgdb_notify(struct die_args
*args
, unsigned long cmd
)
492 struct pt_regs
*regs
= args
->regs
;
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();
506 /* Just ignore, we will handle the roundup on DIE_NMI. */
510 if (was_in_debug_nmi
[raw_smp_processor_id()]) {
511 was_in_debug_nmi
[raw_smp_processor_id()] = 0;
516 case DIE_NMIWATCHDOG
:
517 if (atomic_read(&kgdb_active
) != -1) {
518 /* KGDB CPU roundup: */
519 kgdb_nmicallback(raw_smp_processor_id(), regs
);
522 /* Enter debugger: */
526 if (atomic_read(&kgdb_cpu_doing_single_step
) != -1) {
528 return single_step_cont(regs
, args
);
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
541 if (kgdb_handle_exception(args
->trapnr
, args
->signr
, args
->err
, regs
))
544 /* Must touch watchdog before return to normal operation */
545 touch_nmi_watchdog();
550 kgdb_notify(struct notifier_block
*self
, unsigned long cmd
, void *ptr
)
555 local_irq_save(flags
);
556 ret
= __kgdb_notify(ptr
, cmd
);
557 local_irq_restore(flags
);
562 static struct notifier_block kgdb_notifier
= {
563 .notifier_call
= kgdb_notify
,
566 * Lowest-prio notifier priority, we want to be notified last:
568 .priority
= -INT_MAX
,
572 * kgdb_arch_init - Perform any architecture specific initalization.
574 * This function will handle the initalization of any architecture
575 * specific callbacks.
577 int kgdb_arch_init(void)
581 struct perf_event_attr attr
;
582 struct perf_event
**pevent
;
584 ret
= register_die_notifier(&kgdb_notifier
);
588 * Pre-allocate the hw breakpoint structions in the non-atomic
589 * portion of kgdb because this operation requires mutexs to
592 hw_breakpoint_init(&attr
);
593 attr
.bp_addr
= (unsigned long)kgdb_arch_init
;
594 attr
.bp_len
= HW_BREAKPOINT_LEN_1
;
595 attr
.bp_type
= HW_BREAKPOINT_W
;
597 for (i
= 0; i
< 4; i
++) {
598 breakinfo
[i
].pev
= register_wide_hw_breakpoint(&attr
, NULL
);
599 if (IS_ERR(breakinfo
[i
].pev
)) {
600 printk(KERN_ERR
"kgdb: Could not allocate hw breakpoints\n");
601 breakinfo
[i
].pev
= NULL
;
605 for_each_online_cpu(cpu
) {
606 pevent
= per_cpu_ptr(breakinfo
[i
].pev
, cpu
);
607 pevent
[0]->hw
.sample_period
= 1;
608 if (pevent
[0]->destroy
!= NULL
) {
609 pevent
[0]->destroy
= NULL
;
610 release_bp_slot(*pevent
);
618 * kgdb_arch_exit - Perform any architecture specific uninitalization.
620 * This function will handle the uninitalization of any architecture
621 * specific callbacks, for dynamic registration and unregistration.
623 void kgdb_arch_exit(void)
626 for (i
= 0; i
< 4; i
++) {
627 if (breakinfo
[i
].pev
) {
628 unregister_wide_hw_breakpoint(breakinfo
[i
].pev
);
629 breakinfo
[i
].pev
= NULL
;
632 unregister_die_notifier(&kgdb_notifier
);
637 * kgdb_skipexception - Bail out of KGDB when we've been triggered.
638 * @exception: Exception vector number
639 * @regs: Current &struct pt_regs.
641 * On some architectures we need to skip a breakpoint exception when
642 * it occurs after a breakpoint has been removed.
644 * Skip an int3 exception when it occurs after a breakpoint has been
645 * removed. Backtrack eip by 1 since the int3 would have caused it to
648 int kgdb_skipexception(int exception
, struct pt_regs
*regs
)
650 if (exception
== 3 && kgdb_isremovedbreak(regs
->ip
- 1)) {
657 unsigned long kgdb_arch_pc(int exception
, struct pt_regs
*regs
)
660 return instruction_pointer(regs
) - 1;
661 return instruction_pointer(regs
);
664 void kgdb_arch_set_pc(struct pt_regs
*regs
, unsigned long ip
)
669 struct kgdb_arch arch_kgdb_ops
= {
670 /* Breakpoint instruction: */
671 .gdb_bpt_instr
= { 0xcc },
672 .flags
= KGDB_HW_BREAKPOINT
,
673 .set_hw_breakpoint
= kgdb_set_hw_break
,
674 .remove_hw_breakpoint
= kgdb_remove_hw_break
,
675 .remove_all_hw_break
= kgdb_remove_all_hw_break
,
676 .correct_hw_break
= kgdb_correct_hw_break
,