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>
52 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
55 { "ax", 4, offsetof(struct pt_regs, ax) },
56 { "cx", 4, offsetof(struct pt_regs, cx) },
57 { "dx", 4, offsetof(struct pt_regs, dx) },
58 { "bx", 4, offsetof(struct pt_regs, bx) },
59 { "sp", 4, offsetof(struct pt_regs, sp) },
60 { "bp", 4, offsetof(struct pt_regs, bp) },
61 { "si", 4, offsetof(struct pt_regs, si) },
62 { "di", 4, offsetof(struct pt_regs, di) },
63 { "ip", 4, offsetof(struct pt_regs, ip) },
64 { "flags", 4, offsetof(struct pt_regs, flags) },
65 { "cs", 4, offsetof(struct pt_regs, cs) },
66 { "ss", 4, offsetof(struct pt_regs, ss) },
67 { "ds", 4, offsetof(struct pt_regs, ds) },
68 { "es", 4, offsetof(struct pt_regs, es) },
70 { "ax", 8, offsetof(struct pt_regs, ax) },
71 { "bx", 8, offsetof(struct pt_regs, bx) },
72 { "cx", 8, offsetof(struct pt_regs, cx) },
73 { "dx", 8, offsetof(struct pt_regs, dx) },
74 { "si", 8, offsetof(struct pt_regs, dx) },
75 { "di", 8, offsetof(struct pt_regs, di) },
76 { "bp", 8, offsetof(struct pt_regs, bp) },
77 { "sp", 8, offsetof(struct pt_regs, sp) },
78 { "r8", 8, offsetof(struct pt_regs, r8) },
79 { "r9", 8, offsetof(struct pt_regs, r9) },
80 { "r10", 8, offsetof(struct pt_regs, r10) },
81 { "r11", 8, offsetof(struct pt_regs, r11) },
82 { "r12", 8, offsetof(struct pt_regs, r12) },
83 { "r13", 8, offsetof(struct pt_regs, r13) },
84 { "r14", 8, offsetof(struct pt_regs, r14) },
85 { "r15", 8, offsetof(struct pt_regs, r15) },
86 { "ip", 8, offsetof(struct pt_regs, ip) },
87 { "flags", 4, offsetof(struct pt_regs, flags) },
88 { "cs", 4, offsetof(struct pt_regs, cs) },
89 { "ss", 4, offsetof(struct pt_regs, ss) },
97 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
101 regno == GDB_SS || regno == GDB_FS || regno == GDB_GS ||
103 regno == GDB_SP || regno == GDB_ORIG_AX)
106 if (dbg_reg_def[regno].offset != -1)
107 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
108 dbg_reg_def[regno].size);
112 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
114 if (regno == GDB_ORIG_AX) {
115 memcpy(mem, ®s->orig_ax, sizeof(regs->orig_ax));
118 if (regno >= DBG_MAX_REG_NUM || regno < 0)
121 if (dbg_reg_def[regno].offset != -1)
122 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
123 dbg_reg_def[regno].size);
128 if (!user_mode_vm(regs))
129 *(unsigned long *)mem = __KERNEL_DS;
132 if (!user_mode_vm(regs))
133 *(unsigned long *)mem = kernel_stack_pointer(regs);
137 *(unsigned long *)mem = 0xFFFF;
141 return dbg_reg_def[regno].name;
145 * sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
146 * @gdb_regs: A pointer to hold the registers in the order GDB wants.
147 * @p: The &struct task_struct of the desired process.
149 * Convert the register values of the sleeping process in @p to
150 * the format that GDB expects.
151 * This function is called when kgdb does not have access to the
152 * &struct pt_regs and therefore it should fill the gdb registers
153 * @gdb_regs with what has been saved in &struct thread_struct
154 * thread field during switch_to.
156 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
158 #ifndef CONFIG_X86_32
159 u32 *gdb_regs32 = (u32 *)gdb_regs;
161 gdb_regs[GDB_AX] = 0;
162 gdb_regs[GDB_BX] = 0;
163 gdb_regs[GDB_CX] = 0;
164 gdb_regs[GDB_DX] = 0;
165 gdb_regs[GDB_SI] = 0;
166 gdb_regs[GDB_DI] = 0;
167 gdb_regs[GDB_BP] = *(unsigned long *)p->thread.sp;
169 gdb_regs[GDB_DS] = __KERNEL_DS;
170 gdb_regs[GDB_ES] = __KERNEL_DS;
171 gdb_regs[GDB_PS] = 0;
172 gdb_regs[GDB_CS] = __KERNEL_CS;
173 gdb_regs[GDB_PC] = p->thread.ip;
174 gdb_regs[GDB_SS] = __KERNEL_DS;
175 gdb_regs[GDB_FS] = 0xFFFF;
176 gdb_regs[GDB_GS] = 0xFFFF;
178 gdb_regs32[GDB_PS] = *(unsigned long *)(p->thread.sp + 8);
179 gdb_regs32[GDB_CS] = __KERNEL_CS;
180 gdb_regs32[GDB_SS] = __KERNEL_DS;
181 gdb_regs[GDB_PC] = 0;
182 gdb_regs[GDB_R8] = 0;
183 gdb_regs[GDB_R9] = 0;
184 gdb_regs[GDB_R10] = 0;
185 gdb_regs[GDB_R11] = 0;
186 gdb_regs[GDB_R12] = 0;
187 gdb_regs[GDB_R13] = 0;
188 gdb_regs[GDB_R14] = 0;
189 gdb_regs[GDB_R15] = 0;
191 gdb_regs[GDB_SP] = p->thread.sp;
194 static struct hw_breakpoint {
199 struct perf_event * __percpu *pev;
200 } breakinfo[HBP_NUM];
202 static unsigned long early_dr7;
204 static void kgdb_correct_hw_break(void)
208 for (breakno = 0; breakno < HBP_NUM; 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 responsible for handing the retry on
291 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
295 for (i = 0; i < HBP_NUM; 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 < HBP_NUM; i++) {
317 if (!breakinfo[i].enabled)
319 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
320 if (!bp->attr.disabled) {
321 arch_uninstall_hw_breakpoint(bp);
322 bp->attr.disabled = 1;
326 early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
328 else if (hw_break_release_slot(i))
329 printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
331 breakinfo[i].enabled = 0;
336 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
340 for (i = 0; i < HBP_NUM; i++)
341 if (!breakinfo[i].enabled)
347 case BP_HARDWARE_BREAKPOINT:
349 breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
351 case BP_WRITE_WATCHPOINT:
352 breakinfo[i].type = X86_BREAKPOINT_WRITE;
354 case BP_ACCESS_WATCHPOINT:
355 breakinfo[i].type = X86_BREAKPOINT_RW;
362 breakinfo[i].len = X86_BREAKPOINT_LEN_1;
365 breakinfo[i].len = X86_BREAKPOINT_LEN_2;
368 breakinfo[i].len = X86_BREAKPOINT_LEN_4;
372 breakinfo[i].len = X86_BREAKPOINT_LEN_8;
378 breakinfo[i].addr = addr;
379 if (hw_break_reserve_slot(i)) {
380 breakinfo[i].addr = 0;
383 breakinfo[i].enabled = 1;
389 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
390 * @regs: Current &struct pt_regs.
392 * This function will be called if the particular architecture must
393 * disable hardware debugging while it is processing gdb packets or
394 * handling exception.
396 static void kgdb_disable_hw_debug(struct pt_regs *regs)
399 int cpu = raw_smp_processor_id();
400 struct perf_event *bp;
402 /* Disable hardware debugging while we are in kgdb: */
403 set_debugreg(0UL, 7);
404 for (i = 0; i < HBP_NUM; i++) {
405 if (!breakinfo[i].enabled)
408 early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
412 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
413 if (bp->attr.disabled == 1)
415 arch_uninstall_hw_breakpoint(bp);
416 bp->attr.disabled = 1;
422 * kgdb_roundup_cpus - Get other CPUs into a holding pattern
423 * @flags: Current IRQ state
425 * On SMP systems, we need to get the attention of the other CPUs
426 * and get them be in a known state. This should do what is needed
427 * to get the other CPUs to call kgdb_wait(). Note that on some arches,
428 * the NMI approach is not used for rounding up all the CPUs. For example,
429 * in case of MIPS, smp_call_function() is used to roundup CPUs. In
430 * this case, we have to make sure that interrupts are enabled before
431 * calling smp_call_function(). The argument to this function is
432 * the flags that will be used when restoring the interrupts. There is
433 * local_irq_save() call before kgdb_roundup_cpus().
435 * On non-SMP systems, this is not called.
437 void kgdb_roundup_cpus(unsigned long flags)
439 apic->send_IPI_allbutself(APIC_DM_NMI);
444 * kgdb_arch_handle_exception - Handle architecture specific GDB packets.
445 * @vector: The error vector of the exception that happened.
446 * @signo: The signal number of the exception that happened.
447 * @err_code: The error code of the exception that happened.
448 * @remcom_in_buffer: The buffer of the packet we have read.
449 * @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
450 * @regs: The &struct pt_regs of the current process.
452 * This function MUST handle the 'c' and 's' command packets,
453 * as well packets to set / remove a hardware breakpoint, if used.
454 * If there are additional packets which the hardware needs to handle,
455 * they are handled here. The code should return -1 if it wants to
456 * process more packets, and a %0 or %1 if it wants to exit from the
459 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
460 char *remcomInBuffer, char *remcomOutBuffer,
461 struct pt_regs *linux_regs)
466 switch (remcomInBuffer[0]) {
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;
475 /* clear the trace bit */
476 linux_regs->flags &= ~X86_EFLAGS_TF;
477 atomic_set(&kgdb_cpu_doing_single_step, -1);
479 /* set the trace bit if we're stepping */
480 if (remcomInBuffer[0] == 's') {
481 linux_regs->flags |= X86_EFLAGS_TF;
482 atomic_set(&kgdb_cpu_doing_single_step,
483 raw_smp_processor_id());
489 /* this means that we do not want to exit from the handler: */
494 single_step_cont(struct pt_regs *regs, struct die_args *args)
497 * Single step exception from kernel space to user space so
498 * eat the exception and continue the process:
500 printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
502 kgdb_arch_handle_exception(args->trapnr, args->signr,
503 args->err, "c", "", regs);
505 * Reset the BS bit in dr6 (pointed by args->err) to
506 * denote completion of processing
508 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
513 static int was_in_debug_nmi[NR_CPUS];
515 static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs)
519 if (atomic_read(&kgdb_active) != -1) {
520 /* KGDB CPU roundup */
521 kgdb_nmicallback(raw_smp_processor_id(), regs);
522 was_in_debug_nmi[raw_smp_processor_id()] = 1;
523 touch_nmi_watchdog();
529 if (was_in_debug_nmi[raw_smp_processor_id()]) {
530 was_in_debug_nmi[raw_smp_processor_id()] = 0;
541 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
543 struct pt_regs *regs = args->regs;
547 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
549 return single_step_cont(regs, args);
551 } else if (test_thread_flag(TIF_SINGLESTEP))
552 /* This means a user thread is single stepping
553 * a system call which should be ignored
562 if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
565 /* Must touch watchdog before return to normal operation */
566 touch_nmi_watchdog();
570 int kgdb_ll_trap(int cmd, const char *str,
571 struct pt_regs *regs, long err, int trap, int sig)
573 struct die_args args = {
582 if (!kgdb_io_module_registered)
585 return __kgdb_notify(&args, cmd);
589 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
594 local_irq_save(flags);
595 ret = __kgdb_notify(ptr, cmd);
596 local_irq_restore(flags);
601 static struct notifier_block kgdb_notifier = {
602 .notifier_call = kgdb_notify,
606 * kgdb_arch_init - Perform any architecture specific initalization.
608 * This function will handle the initalization of any architecture
609 * specific callbacks.
611 int kgdb_arch_init(void)
615 retval = register_die_notifier(&kgdb_notifier);
619 retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler,
624 retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler,
633 unregister_nmi_handler(NMI_LOCAL, "kgdb");
635 unregister_die_notifier(&kgdb_notifier);
640 static void kgdb_hw_overflow_handler(struct perf_event *event,
641 struct perf_sample_data *data, struct pt_regs *regs)
643 struct task_struct *tsk = current;
646 for (i = 0; i < 4; i++)
647 if (breakinfo[i].enabled)
648 tsk->thread.debugreg6 |= (DR_TRAP0 << i);
651 void kgdb_arch_late(void)
654 struct perf_event_attr attr;
655 struct perf_event **pevent;
658 * Pre-allocate the hw breakpoint structions in the non-atomic
659 * portion of kgdb because this operation requires mutexs to
662 hw_breakpoint_init(&attr);
663 attr.bp_addr = (unsigned long)kgdb_arch_init;
664 attr.bp_len = HW_BREAKPOINT_LEN_1;
665 attr.bp_type = HW_BREAKPOINT_W;
667 for (i = 0; i < HBP_NUM; i++) {
668 if (breakinfo[i].pev)
670 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL);
671 if (IS_ERR((void * __force)breakinfo[i].pev)) {
672 printk(KERN_ERR "kgdb: Could not allocate hw"
673 "breakpoints\nDisabling the kernel debugger\n");
674 breakinfo[i].pev = NULL;
678 for_each_online_cpu(cpu) {
679 pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
680 pevent[0]->hw.sample_period = 1;
681 pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
682 if (pevent[0]->destroy != NULL) {
683 pevent[0]->destroy = NULL;
684 release_bp_slot(*pevent);
691 * kgdb_arch_exit - Perform any architecture specific uninitalization.
693 * This function will handle the uninitalization of any architecture
694 * specific callbacks, for dynamic registration and unregistration.
696 void kgdb_arch_exit(void)
699 for (i = 0; i < 4; i++) {
700 if (breakinfo[i].pev) {
701 unregister_wide_hw_breakpoint(breakinfo[i].pev);
702 breakinfo[i].pev = NULL;
705 unregister_nmi_handler(NMI_UNKNOWN, "kgdb");
706 unregister_nmi_handler(NMI_LOCAL, "kgdb");
707 unregister_die_notifier(&kgdb_notifier);
712 * kgdb_skipexception - Bail out of KGDB when we've been triggered.
713 * @exception: Exception vector number
714 * @regs: Current &struct pt_regs.
716 * On some architectures we need to skip a breakpoint exception when
717 * it occurs after a breakpoint has been removed.
719 * Skip an int3 exception when it occurs after a breakpoint has been
720 * removed. Backtrack eip by 1 since the int3 would have caused it to
723 int kgdb_skipexception(int exception, struct pt_regs *regs)
725 if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
732 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
735 return instruction_pointer(regs) - 1;
736 return instruction_pointer(regs);
739 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
744 struct kgdb_arch arch_kgdb_ops = {
745 /* Breakpoint instruction: */
746 .gdb_bpt_instr = { 0xcc },
747 .flags = KGDB_HW_BREAKPOINT,
748 .set_hw_breakpoint = kgdb_set_hw_break,
749 .remove_hw_breakpoint = kgdb_remove_hw_break,
750 .disable_hw_break = kgdb_disable_hw_debug,
751 .remove_all_hw_break = kgdb_remove_all_hw_break,
752 .correct_hw_break = kgdb_correct_hw_break,