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 unsigned long early_dr7
;
204 static void kgdb_correct_hw_break(void)
208 for (breakno
= 0; breakno
< 4; breakno
++) {
209 struct perf_event
*bp
;
210 struct arch_hw_breakpoint
*info
;
212 int cpu
= raw_smp_processor_id();
213 if (!breakinfo
[breakno
].enabled
)
216 set_debugreg(breakinfo
[breakno
].addr
, breakno
);
217 early_dr7
|= encode_dr7(breakno
,
218 breakinfo
[breakno
].len
,
219 breakinfo
[breakno
].type
);
220 set_debugreg(early_dr7
, 7);
223 bp
= *per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
224 info
= counter_arch_bp(bp
);
225 if (bp
->attr
.disabled
!= 1)
227 bp
->attr
.bp_addr
= breakinfo
[breakno
].addr
;
228 bp
->attr
.bp_len
= breakinfo
[breakno
].len
;
229 bp
->attr
.bp_type
= breakinfo
[breakno
].type
;
230 info
->address
= breakinfo
[breakno
].addr
;
231 info
->len
= breakinfo
[breakno
].len
;
232 info
->type
= breakinfo
[breakno
].type
;
233 val
= arch_install_hw_breakpoint(bp
);
235 bp
->attr
.disabled
= 0;
238 hw_breakpoint_restore();
241 static int hw_break_reserve_slot(int breakno
)
245 struct perf_event
**pevent
;
250 for_each_online_cpu(cpu
) {
252 pevent
= per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
253 if (dbg_reserve_bp_slot(*pevent
))
260 for_each_online_cpu(cpu
) {
264 pevent
= per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
265 dbg_release_bp_slot(*pevent
);
270 static int hw_break_release_slot(int breakno
)
272 struct perf_event
**pevent
;
278 for_each_online_cpu(cpu
) {
279 pevent
= per_cpu_ptr(breakinfo
[breakno
].pev
, cpu
);
280 if (dbg_release_bp_slot(*pevent
))
282 * The debugger is responisble for handing the retry on
291 kgdb_remove_hw_break(unsigned long addr
, int len
, enum kgdb_bptype bptype
)
295 for (i
= 0; i
< 4; i
++)
296 if (breakinfo
[i
].addr
== addr
&& breakinfo
[i
].enabled
)
301 if (hw_break_release_slot(i
)) {
302 printk(KERN_ERR
"Cannot remove hw breakpoint at %lx\n", addr
);
305 breakinfo
[i
].enabled
= 0;
310 static void kgdb_remove_all_hw_break(void)
313 int cpu
= raw_smp_processor_id();
314 struct perf_event
*bp
;
316 for (i
= 0; i
< 4; i
++) {
317 if (!breakinfo
[i
].enabled
)
319 bp
= *per_cpu_ptr(breakinfo
[i
].pev
, cpu
);
320 if (bp
->attr
.disabled
== 1)
323 early_dr7
&= ~encode_dr7(i
, breakinfo
[i
].len
,
326 arch_uninstall_hw_breakpoint(bp
);
327 bp
->attr
.disabled
= 1;
332 kgdb_set_hw_break(unsigned long addr
, int len
, enum kgdb_bptype bptype
)
336 for (i
= 0; i
< 4; i
++)
337 if (!breakinfo
[i
].enabled
)
343 case BP_HARDWARE_BREAKPOINT
:
345 breakinfo
[i
].type
= X86_BREAKPOINT_EXECUTE
;
347 case BP_WRITE_WATCHPOINT
:
348 breakinfo
[i
].type
= X86_BREAKPOINT_WRITE
;
350 case BP_ACCESS_WATCHPOINT
:
351 breakinfo
[i
].type
= X86_BREAKPOINT_RW
;
358 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_1
;
361 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_2
;
364 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_4
;
368 breakinfo
[i
].len
= X86_BREAKPOINT_LEN_8
;
374 breakinfo
[i
].addr
= addr
;
375 if (hw_break_reserve_slot(i
)) {
376 breakinfo
[i
].addr
= 0;
379 breakinfo
[i
].enabled
= 1;
385 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
386 * @regs: Current &struct pt_regs.
388 * This function will be called if the particular architecture must
389 * disable hardware debugging while it is processing gdb packets or
390 * handling exception.
392 void kgdb_disable_hw_debug(struct pt_regs
*regs
)
395 int cpu
= raw_smp_processor_id();
396 struct perf_event
*bp
;
398 /* Disable hardware debugging while we are in kgdb: */
399 set_debugreg(0UL, 7);
400 for (i
= 0; i
< 4; i
++) {
401 if (!breakinfo
[i
].enabled
)
404 early_dr7
&= ~encode_dr7(i
, breakinfo
[i
].len
,
408 bp
= *per_cpu_ptr(breakinfo
[i
].pev
, cpu
);
409 if (bp
->attr
.disabled
== 1)
411 arch_uninstall_hw_breakpoint(bp
);
412 bp
->attr
.disabled
= 1;
418 * kgdb_roundup_cpus - Get other CPUs into a holding pattern
419 * @flags: Current IRQ state
421 * On SMP systems, we need to get the attention of the other CPUs
422 * and get them be in a known state. This should do what is needed
423 * to get the other CPUs to call kgdb_wait(). Note that on some arches,
424 * the NMI approach is not used for rounding up all the CPUs. For example,
425 * in case of MIPS, smp_call_function() is used to roundup CPUs. In
426 * this case, we have to make sure that interrupts are enabled before
427 * calling smp_call_function(). The argument to this function is
428 * the flags that will be used when restoring the interrupts. There is
429 * local_irq_save() call before kgdb_roundup_cpus().
431 * On non-SMP systems, this is not called.
433 void kgdb_roundup_cpus(unsigned long flags
)
435 apic
->send_IPI_allbutself(APIC_DM_NMI
);
440 * kgdb_arch_handle_exception - Handle architecture specific GDB packets.
441 * @vector: The error vector of the exception that happened.
442 * @signo: The signal number of the exception that happened.
443 * @err_code: The error code of the exception that happened.
444 * @remcom_in_buffer: The buffer of the packet we have read.
445 * @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
446 * @regs: The &struct pt_regs of the current process.
448 * This function MUST handle the 'c' and 's' command packets,
449 * as well packets to set / remove a hardware breakpoint, if used.
450 * If there are additional packets which the hardware needs to handle,
451 * they are handled here. The code should return -1 if it wants to
452 * process more packets, and a %0 or %1 if it wants to exit from the
455 int kgdb_arch_handle_exception(int e_vector
, int signo
, int err_code
,
456 char *remcomInBuffer
, char *remcomOutBuffer
,
457 struct pt_regs
*linux_regs
)
463 switch (remcomInBuffer
[0]) {
466 /* try to read optional parameter, pc unchanged if no parm */
467 ptr
= &remcomInBuffer
[1];
468 if (kgdb_hex2long(&ptr
, &addr
))
469 linux_regs
->ip
= addr
;
472 newPC
= linux_regs
->ip
;
474 /* clear the trace bit */
475 linux_regs
->flags
&= ~X86_EFLAGS_TF
;
476 atomic_set(&kgdb_cpu_doing_single_step
, -1);
478 /* set the trace bit if we're stepping */
479 if (remcomInBuffer
[0] == 's') {
480 linux_regs
->flags
|= X86_EFLAGS_TF
;
481 atomic_set(&kgdb_cpu_doing_single_step
,
482 raw_smp_processor_id());
485 kgdb_correct_hw_break();
490 /* this means that we do not want to exit from the handler: */
495 single_step_cont(struct pt_regs
*regs
, struct die_args
*args
)
498 * Single step exception from kernel space to user space so
499 * eat the exception and continue the process:
501 printk(KERN_ERR
"KGDB: trap/step from kernel to user space, "
503 kgdb_arch_handle_exception(args
->trapnr
, args
->signr
,
504 args
->err
, "c", "", regs
);
506 * Reset the BS bit in dr6 (pointed by args->err) to
507 * denote completion of processing
509 (*(unsigned long *)ERR_PTR(args
->err
)) &= ~DR_STEP
;
514 static int was_in_debug_nmi
[NR_CPUS
];
516 static int __kgdb_notify(struct die_args
*args
, unsigned long cmd
)
518 struct pt_regs
*regs
= args
->regs
;
522 if (atomic_read(&kgdb_active
) != -1) {
523 /* KGDB CPU roundup */
524 kgdb_nmicallback(raw_smp_processor_id(), regs
);
525 was_in_debug_nmi
[raw_smp_processor_id()] = 1;
526 touch_nmi_watchdog();
532 /* Just ignore, we will handle the roundup on DIE_NMI. */
536 if (was_in_debug_nmi
[raw_smp_processor_id()]) {
537 was_in_debug_nmi
[raw_smp_processor_id()] = 0;
542 case DIE_NMIWATCHDOG
:
543 if (atomic_read(&kgdb_active
) != -1) {
544 /* KGDB CPU roundup: */
545 kgdb_nmicallback(raw_smp_processor_id(), regs
);
548 /* Enter debugger: */
552 if (atomic_read(&kgdb_cpu_doing_single_step
) != -1) {
554 return single_step_cont(regs
, args
);
556 } else if (test_thread_flag(TIF_SINGLESTEP
))
557 /* This means a user thread is single stepping
558 * a system call which should be ignored
567 if (kgdb_handle_exception(args
->trapnr
, args
->signr
, cmd
, regs
))
570 /* Must touch watchdog before return to normal operation */
571 touch_nmi_watchdog();
575 int kgdb_ll_trap(int cmd
, const char *str
,
576 struct pt_regs
*regs
, long err
, int trap
, int sig
)
578 struct die_args args
= {
587 if (!kgdb_io_module_registered
)
590 return __kgdb_notify(&args
, cmd
);
594 kgdb_notify(struct notifier_block
*self
, unsigned long cmd
, void *ptr
)
599 local_irq_save(flags
);
600 ret
= __kgdb_notify(ptr
, cmd
);
601 local_irq_restore(flags
);
606 static struct notifier_block kgdb_notifier
= {
607 .notifier_call
= kgdb_notify
,
610 * Lowest-prio notifier priority, we want to be notified last:
612 .priority
= -INT_MAX
,
616 * kgdb_arch_init - Perform any architecture specific initalization.
618 * This function will handle the initalization of any architecture
619 * specific callbacks.
621 int kgdb_arch_init(void)
623 return register_die_notifier(&kgdb_notifier
);
626 static void kgdb_hw_overflow_handler(struct perf_event
*event
, int nmi
,
627 struct perf_sample_data
*data
, struct pt_regs
*regs
)
629 kgdb_ll_trap(DIE_DEBUG
, "debug", regs
, 0, 0, SIGTRAP
);
632 void kgdb_arch_late(void)
635 struct perf_event_attr attr
;
636 struct perf_event
**pevent
;
639 * Pre-allocate the hw breakpoint structions in the non-atomic
640 * portion of kgdb because this operation requires mutexs to
643 hw_breakpoint_init(&attr
);
644 attr
.bp_addr
= (unsigned long)kgdb_arch_init
;
645 attr
.bp_len
= HW_BREAKPOINT_LEN_1
;
646 attr
.bp_type
= HW_BREAKPOINT_W
;
648 for (i
= 0; i
< 4; i
++) {
649 if (breakinfo
[i
].pev
)
651 breakinfo
[i
].pev
= register_wide_hw_breakpoint(&attr
, NULL
);
652 if (IS_ERR(breakinfo
[i
].pev
)) {
653 printk(KERN_ERR
"kgdb: Could not allocate hw"
654 "breakpoints\nDisabling the kernel debugger\n");
655 breakinfo
[i
].pev
= NULL
;
659 for_each_online_cpu(cpu
) {
660 pevent
= per_cpu_ptr(breakinfo
[i
].pev
, cpu
);
661 pevent
[0]->hw
.sample_period
= 1;
662 pevent
[0]->overflow_handler
= kgdb_hw_overflow_handler
;
663 if (pevent
[0]->destroy
!= NULL
) {
664 pevent
[0]->destroy
= NULL
;
665 release_bp_slot(*pevent
);
672 * kgdb_arch_exit - Perform any architecture specific uninitalization.
674 * This function will handle the uninitalization of any architecture
675 * specific callbacks, for dynamic registration and unregistration.
677 void kgdb_arch_exit(void)
680 for (i
= 0; i
< 4; i
++) {
681 if (breakinfo
[i
].pev
) {
682 unregister_wide_hw_breakpoint(breakinfo
[i
].pev
);
683 breakinfo
[i
].pev
= NULL
;
686 unregister_die_notifier(&kgdb_notifier
);
691 * kgdb_skipexception - Bail out of KGDB when we've been triggered.
692 * @exception: Exception vector number
693 * @regs: Current &struct pt_regs.
695 * On some architectures we need to skip a breakpoint exception when
696 * it occurs after a breakpoint has been removed.
698 * Skip an int3 exception when it occurs after a breakpoint has been
699 * removed. Backtrack eip by 1 since the int3 would have caused it to
702 int kgdb_skipexception(int exception
, struct pt_regs
*regs
)
704 if (exception
== 3 && kgdb_isremovedbreak(regs
->ip
- 1)) {
711 unsigned long kgdb_arch_pc(int exception
, struct pt_regs
*regs
)
714 return instruction_pointer(regs
) - 1;
715 return instruction_pointer(regs
);
718 void kgdb_arch_set_pc(struct pt_regs
*regs
, unsigned long ip
)
723 struct kgdb_arch arch_kgdb_ops
= {
724 /* Breakpoint instruction: */
725 .gdb_bpt_instr
= { 0xcc },
726 .flags
= KGDB_HW_BREAKPOINT
,
727 .set_hw_breakpoint
= kgdb_set_hw_break
,
728 .remove_hw_breakpoint
= kgdb_remove_hw_break
,
729 .remove_all_hw_break
= kgdb_remove_all_hw_break
,
730 .correct_hw_break
= kgdb_correct_hw_break
,