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, cmd, regs))
544 /* Must touch watchdog before return to normal operation */
545 touch_nmi_watchdog();
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)
553 struct die_args args = {
562 if (!kgdb_io_module_registered)
565 return __kgdb_notify(&args, cmd);
567 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
570 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
575 local_irq_save(flags);
576 ret = __kgdb_notify(ptr, cmd);
577 local_irq_restore(flags);
582 static struct notifier_block kgdb_notifier = {
583 .notifier_call = kgdb_notify,
586 * Lowest-prio notifier priority, we want to be notified last:
588 .priority = -INT_MAX,
592 * kgdb_arch_init - Perform any architecture specific initalization.
594 * This function will handle the initalization of any architecture
595 * specific callbacks.
597 int kgdb_arch_init(void)
599 return register_die_notifier(&kgdb_notifier);
602 void kgdb_arch_late(void)
605 struct perf_event_attr attr;
606 struct perf_event **pevent;
609 * Pre-allocate the hw breakpoint structions in the non-atomic
610 * portion of kgdb because this operation requires mutexs to
613 hw_breakpoint_init(&attr);
614 attr.bp_addr = (unsigned long)kgdb_arch_init;
615 attr.bp_len = HW_BREAKPOINT_LEN_1;
616 attr.bp_type = HW_BREAKPOINT_W;
618 for (i = 0; i < 4; i++) {
619 if (breakinfo[i].pev)
621 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
622 if (IS_ERR(breakinfo[i].pev)) {
623 printk(KERN_ERR "kgdb: Could not allocate hw"
624 "breakpoints\nDisabling the kernel debugger\n");
625 breakinfo[i].pev = NULL;
629 for_each_online_cpu(cpu) {
630 pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
631 pevent[0]->hw.sample_period = 1;
632 if (pevent[0]->destroy != NULL) {
633 pevent[0]->destroy = NULL;
634 release_bp_slot(*pevent);
641 * kgdb_arch_exit - Perform any architecture specific uninitalization.
643 * This function will handle the uninitalization of any architecture
644 * specific callbacks, for dynamic registration and unregistration.
646 void kgdb_arch_exit(void)
649 for (i = 0; i < 4; i++) {
650 if (breakinfo[i].pev) {
651 unregister_wide_hw_breakpoint(breakinfo[i].pev);
652 breakinfo[i].pev = NULL;
655 unregister_die_notifier(&kgdb_notifier);
660 * kgdb_skipexception - Bail out of KGDB when we've been triggered.
661 * @exception: Exception vector number
662 * @regs: Current &struct pt_regs.
664 * On some architectures we need to skip a breakpoint exception when
665 * it occurs after a breakpoint has been removed.
667 * Skip an int3 exception when it occurs after a breakpoint has been
668 * removed. Backtrack eip by 1 since the int3 would have caused it to
671 int kgdb_skipexception(int exception, struct pt_regs *regs)
673 if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
680 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
683 return instruction_pointer(regs) - 1;
684 return instruction_pointer(regs);
687 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
692 struct kgdb_arch arch_kgdb_ops = {
693 /* Breakpoint instruction: */
694 .gdb_bpt_instr = { 0xcc },
695 .flags = KGDB_HW_BREAKPOINT,
696 .set_hw_breakpoint = kgdb_set_hw_break,
697 .remove_hw_breakpoint = kgdb_remove_hw_break,
698 .remove_all_hw_break = kgdb_remove_all_hw_break,
699 .correct_hw_break = kgdb_correct_hw_break,