1 files changed, 983 insertions, 0 deletions

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
new file mode 100644
index 000000000000..8bc5eeffec8a
--- /dev/null
+++ b/kernel/debug/debug_core.c
@@ -0,0 +1,983 @@
+/*
+ * Kernel Debug Core
+ *
+ * Maintainer: Jason Wessel <jason.wessel@windriver.com>
+ *
+ * Copyright (C) 2000-2001 VERITAS Software Corporation.
+ * Copyright (C) 2002-2004 Timesys Corporation
+ * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
+ * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
+ * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
+ * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
+ * Copyright (C) 2005-2009 Wind River Systems, Inc.
+ * Copyright (C) 2007 MontaVista Software, Inc.
+ * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * Contributors at various stages not listed above:
+ *  Jason Wessel ( jason.wessel@windriver.com )
+ *  George Anzinger <george@mvista.com>
+ *  Anurekh Saxena (anurekh.saxena@timesys.com)
+ *  Lake Stevens Instrument Division (Glenn Engel)
+ *  Jim Kingdon, Cygnus Support.
+ *
+ * Original KGDB stub: David Grothe <dave@gcom.com>,
+ * Tigran Aivazian <tigran@sco.com>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+#include <linux/pid_namespace.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/console.h>
+#include <linux/threads.h>
+#include <linux/uaccess.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/ptrace.h>
+#include <linux/string.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/sysrq.h>
+#include <linux/init.h>
+#include <linux/kgdb.h>
+#include <linux/kdb.h>
+#include <linux/pid.h>
+#include <linux/smp.h>
+#include <linux/mm.h>
+
+#include <asm/cacheflush.h>
+#include <asm/byteorder.h>
+#include <asm/atomic.h>
+#include <asm/system.h>
+
+#include "debug_core.h"
+
+static int kgdb_break_asap;
+
+struct debuggerinfo_struct kgdb_info[NR_CPUS];
+
+/**
+ * kgdb_connected - Is a host GDB connected to us?
+ */
+int                             kgdb_connected;
+EXPORT_SYMBOL_GPL(kgdb_connected);
+
+/* All the KGDB handlers are installed */
+int                     kgdb_io_module_registered;
+
+/* Guard for recursive entry */
+static int                      exception_level;
+
+struct kgdb_io          *dbg_io_ops;
+static DEFINE_SPINLOCK(kgdb_registration_lock);
+
+/* kgdb console driver is loaded */
+static int kgdb_con_registered;
+/* determine if kgdb console output should be used */
+static int kgdb_use_con;
+/* Flag for alternate operations for early debugging */
+bool dbg_is_early = true;
+/* Next cpu to become the master debug core */
+int dbg_switch_cpu;
+
+/* Use kdb or gdbserver mode */
+int dbg_kdb_mode = 1;
+
+static int __init opt_kgdb_con(char *str)
+{
+        kgdb_use_con = 1;
+        return 0;
+}
+
+early_param("kgdbcon", opt_kgdb_con);
+
+module_param(kgdb_use_con, int, 0644);
+
+/*
+ * Holds information about breakpoints in a kernel. These breakpoints are
+ * added and removed by gdb.
+ */
+static struct kgdb_bkpt         kgdb_break[KGDB_MAX_BREAKPOINTS] = {
+        [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
+};
+
+/*
+ * The CPU# of the active CPU, or -1 if none:
+ */
+atomic_t                        kgdb_active = ATOMIC_INIT(-1);
+EXPORT_SYMBOL_GPL(kgdb_active);
+
+/*
+ * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
+ * bootup code (which might not have percpu set up yet):
+ */
+static atomic_t                 passive_cpu_wait[NR_CPUS];
+static atomic_t                 cpu_in_kgdb[NR_CPUS];
+static atomic_t                 kgdb_break_tasklet_var;
+atomic_t                        kgdb_setting_breakpoint;
+
+struct task_struct              *kgdb_usethread;
+struct task_struct              *kgdb_contthread;
+
+int                             kgdb_single_step;
+static pid_t                    kgdb_sstep_pid;
+
+/* to keep track of the CPU which is doing the single stepping*/
+atomic_t                        kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
+
+/*
+ * If you are debugging a problem where roundup (the collection of
+ * all other CPUs) is a problem [this should be extremely rare],
+ * then use the nokgdbroundup option to avoid roundup. In that case
+ * the other CPUs might interfere with your debugging context, so
+ * use this with care:
+ */
+static int kgdb_do_roundup = 1;
+
+static int __init opt_nokgdbroundup(char *str)
+{
+        kgdb_do_roundup = 0;
+
+        return 0;
+}
+
+early_param("nokgdbroundup", opt_nokgdbroundup);
+
+/*
+ * Finally, some KGDB code :-)
+ */
+
+/*
+ * Weak aliases for breakpoint management,
+ * can be overriden by architectures when needed:
+ */
+int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
+{
+        int err;
+
+        err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
+        if (err)
+                return err;
+
+        return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
+                                  BREAK_INSTR_SIZE);
+}
+
+int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
+{
+        return probe_kernel_write((char *)addr,
+                                  (char *)bundle, BREAK_INSTR_SIZE);
+}
+
+int __weak kgdb_validate_break_address(unsigned long addr)
+{
+        char tmp_variable[BREAK_INSTR_SIZE];
+        int err;
+        /* Validate setting the breakpoint and then removing it.  In the
+         * remove fails, the kernel needs to emit a bad message because we
+         * are deep trouble not being able to put things back the way we
+         * found them.
+         */
+        err = kgdb_arch_set_breakpoint(addr, tmp_variable);
+        if (err)
+                return err;
+        err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
+        if (err)
+                printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
+                   "memory destroyed at: %lx", addr);
+        return err;
+}
+
+unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
+{
+        return instruction_pointer(regs);
+}
+
+int __weak kgdb_arch_init(void)
+{
+        return 0;
+}
+
+int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
+{
+        return 0;
+}
+
+/**
+ *      kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
+ *      @regs: Current &struct pt_regs.
+ *
+ *      This function will be called if the particular architecture must
+ *      disable hardware debugging while it is processing gdb packets or
+ *      handling exception.
+ */
+void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
+{
+}
+
+/*
+ * Some architectures need cache flushes when we set/clear a
+ * breakpoint:
+ */
+static void kgdb_flush_swbreak_addr(unsigned long addr)
+{
+        if (!CACHE_FLUSH_IS_SAFE)
+                return;
+
+        if (current->mm && current->mm->mmap_cache) {
+                flush_cache_range(current->mm->mmap_cache,
+                                  addr, addr + BREAK_INSTR_SIZE);
+        }
+        /* Force flush instruction cache if it was outside the mm */
+        flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
+}
+
+/*
+ * SW breakpoint management:
+ */
+int dbg_activate_sw_breakpoints(void)
+{
+        unsigned long addr;
+        int error;
+        int ret = 0;
+        int i;
+
+        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                if (kgdb_break[i].state != BP_SET)
+                        continue;
+
+                addr = kgdb_break[i].bpt_addr;
+                error = kgdb_arch_set_breakpoint(addr,
+                                kgdb_break[i].saved_instr);
+                if (error) {
+                        ret = error;
+                        printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
+                        continue;
+                }
+
+                kgdb_flush_swbreak_addr(addr);
+                kgdb_break[i].state = BP_ACTIVE;
+        }
+        return ret;
+}
+
+int dbg_set_sw_break(unsigned long addr)
+{
+        int err = kgdb_validate_break_address(addr);
+        int breakno = -1;
+        int i;
+
+        if (err)
+                return err;
+
+        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                if ((kgdb_break[i].state == BP_SET) &&
+                                        (kgdb_break[i].bpt_addr == addr))
+                        return -EEXIST;
+        }
+        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                if (kgdb_break[i].state == BP_REMOVED &&
+                                        kgdb_break[i].bpt_addr == addr) {
+                        breakno = i;
+                        break;
+                }
+        }
+
+        if (breakno == -1) {
+                for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                        if (kgdb_break[i].state == BP_UNDEFINED) {
+                                breakno = i;
+                                break;
+                        }
+                }
+        }
+
+        if (breakno == -1)
+                return -E2BIG;
+
+        kgdb_break[breakno].state = BP_SET;
+        kgdb_break[breakno].type = BP_BREAKPOINT;
+        kgdb_break[breakno].bpt_addr = addr;
+
+        return 0;
+}
+
+int dbg_deactivate_sw_breakpoints(void)
+{
+        unsigned long addr;
+        int error;
+        int ret = 0;
+        int i;
+
+        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                if (kgdb_break[i].state != BP_ACTIVE)
+                        continue;
+                addr = kgdb_break[i].bpt_addr;
+                error = kgdb_arch_remove_breakpoint(addr,
+                                        kgdb_break[i].saved_instr);
+                if (error) {
+                        printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
+                        ret = error;
+                }
+
+                kgdb_flush_swbreak_addr(addr);
+                kgdb_break[i].state = BP_SET;
+        }
+        return ret;
+}
+
+int dbg_remove_sw_break(unsigned long addr)
+{
+        int i;
+
+        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                if ((kgdb_break[i].state == BP_SET) &&
+                                (kgdb_break[i].bpt_addr == addr)) {
+                        kgdb_break[i].state = BP_REMOVED;
+                        return 0;
+                }
+        }
+        return -ENOENT;
+}
+
+int kgdb_isremovedbreak(unsigned long addr)
+{
+        int i;
+
+        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                if ((kgdb_break[i].state == BP_REMOVED) &&
+                                        (kgdb_break[i].bpt_addr == addr))
+                        return 1;
+        }
+        return 0;
+}
+
+int dbg_remove_all_break(void)
+{
+        unsigned long addr;
+        int error;
+        int i;
+
+        /* Clear memory breakpoints. */
+        for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+                if (kgdb_break[i].state != BP_ACTIVE)
+                        goto setundefined;
+                addr = kgdb_break[i].bpt_addr;
+                error = kgdb_arch_remove_breakpoint(addr,
+                                kgdb_break[i].saved_instr);
+                if (error)
+                        printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
+                           addr);
+setundefined:
+                kgdb_break[i].state = BP_UNDEFINED;
+        }
+
+        /* Clear hardware breakpoints. */
+        if (arch_kgdb_ops.remove_all_hw_break)
+                arch_kgdb_ops.remove_all_hw_break();
+
+        return 0;
+}
+
+/*
+ * Return true if there is a valid kgdb I/O module.  Also if no
+ * debugger is attached a message can be printed to the console about
+ * waiting for the debugger to attach.
+ *
+ * The print_wait argument is only to be true when called from inside
+ * the core kgdb_handle_exception, because it will wait for the
+ * debugger to attach.
+ */
+static int kgdb_io_ready(int print_wait)
+{
+        if (!dbg_io_ops)
+                return 0;
+        if (kgdb_connected)
+                return 1;
+        if (atomic_read(&kgdb_setting_breakpoint))
+                return 1;
+        if (print_wait) {
+#ifdef CONFIG_KGDB_KDB
+                if (!dbg_kdb_mode)
+                        printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
+#else
+                printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
+#endif
+        }
+        return 1;
+}
+
+static int kgdb_reenter_check(struct kgdb_state *ks)
+{
+        unsigned long addr;
+
+        if (atomic_read(&kgdb_active) != raw_smp_processor_id())
+                return 0;
+
+        /* Panic on recursive debugger calls: */
+        exception_level++;
+        addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
+        dbg_deactivate_sw_breakpoints();
+
+        /*
+         * If the break point removed ok at the place exception
+         * occurred, try to recover and print a warning to the end
+         * user because the user planted a breakpoint in a place that
+         * KGDB needs in order to function.
+         */
+        if (dbg_remove_sw_break(addr) == 0) {
+                exception_level = 0;
+                kgdb_skipexception(ks->ex_vector, ks->linux_regs);
+                dbg_activate_sw_breakpoints();
+                printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
+                        addr);
+                WARN_ON_ONCE(1);
+
+                return 1;
+        }
+        dbg_remove_all_break();
+        kgdb_skipexception(ks->ex_vector, ks->linux_regs);
+
+        if (exception_level > 1) {
+                dump_stack();
+                panic("Recursive entry to debugger");
+        }
+
+        printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
+#ifdef CONFIG_KGDB_KDB
+        /* Allow kdb to debug itself one level */
+        return 0;
+#endif
+        dump_stack();
+        panic("Recursive entry to debugger");
+
+        return 1;
+}
+
+static void dbg_cpu_switch(int cpu, int next_cpu)
+{
+        /* Mark the cpu we are switching away from as a slave when it
+         * holds the kgdb_active token.  This must be done so that the
+         * that all the cpus wait in for the debug core will not enter
+         * again as the master. */
+        if (cpu == atomic_read(&kgdb_active)) {
+                kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
+                kgdb_info[cpu].exception_state &= ~DCPU_WANT_MASTER;
+        }
+        kgdb_info[next_cpu].exception_state |= DCPU_NEXT_MASTER;
+}
+
+static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
+{
+        unsigned long flags;
+        int sstep_tries = 100;
+        int error;
+        int i, cpu;
+        int trace_on = 0;
+acquirelock:
+        /*
+         * Interrupts will be restored by the 'trap return' code, except when
+         * single stepping.
+         */
+        local_irq_save(flags);
+
+        cpu = ks->cpu;
+        kgdb_info[cpu].debuggerinfo = regs;
+        kgdb_info[cpu].task = current;
+        kgdb_info[cpu].ret_state = 0;
+        kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
+        /*
+         * Make sure the above info reaches the primary CPU before
+         * our cpu_in_kgdb[] flag setting does:
+         */
+        atomic_inc(&cpu_in_kgdb[cpu]);
+
+        if (exception_level == 1)
+                goto cpu_master_loop;
+
+        /*
+         * CPU will loop if it is a slave or request to become a kgdb
+         * master cpu and acquire the kgdb_active lock:
+         */
+        while (1) {
+cpu_loop:
+                if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) {
+                        kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
+                        goto cpu_master_loop;
+                } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
+                        if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu)
+                                break;
+                } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
+                        if (!atomic_read(&passive_cpu_wait[cpu]))
+                                goto return_normal;
+                } else {
+return_normal:
+                        /* Return to normal operation by executing any
+                         * hw breakpoint fixup.
+                         */
+                        if (arch_kgdb_ops.correct_hw_break)
+                                arch_kgdb_ops.correct_hw_break();
+                        if (trace_on)
+                                tracing_on();
+                        atomic_dec(&cpu_in_kgdb[cpu]);
+                        touch_softlockup_watchdog_sync();
+                        clocksource_touch_watchdog();
+                        local_irq_restore(flags);
+                        return 0;
+                }
+                cpu_relax();
+        }
+
+        /*
+         * For single stepping, try to only enter on the processor
+         * that was single stepping.  To gaurd against a deadlock, the
+         * kernel will only try for the value of sstep_tries before
+         * giving up and continuing on.
+         */
+        if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
+            (kgdb_info[cpu].task &&
+             kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
+                atomic_set(&kgdb_active, -1);
+                touch_softlockup_watchdog_sync();
+                clocksource_touch_watchdog();
+                local_irq_restore(flags);
+
+                goto acquirelock;
+        }
+
+        if (!kgdb_io_ready(1)) {
+                kgdb_info[cpu].ret_state = 1;
+                goto kgdb_restore; /* No I/O connection, resume the system */
+        }
+
+        /*
+         * Don't enter if we have hit a removed breakpoint.
+         */
+        if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
+                goto kgdb_restore;
+
+        /* Call the I/O driver's pre_exception routine */
+        if (dbg_io_ops->pre_exception)
+                dbg_io_ops->pre_exception();
+
+        kgdb_disable_hw_debug(ks->linux_regs);
+
+        /*
+         * Get the passive CPU lock which will hold all the non-primary
+         * CPU in a spin state while the debugger is active
+         */
+        if (!kgdb_single_step) {
+                for (i = 0; i < NR_CPUS; i++)
+                        atomic_inc(&passive_cpu_wait[i]);
+        }
+
+#ifdef CONFIG_SMP
+        /* Signal the other CPUs to enter kgdb_wait() */
+        if ((!kgdb_single_step) && kgdb_do_roundup)
+                kgdb_roundup_cpus(flags);
+#endif
+
+        /*
+         * Wait for the other CPUs to be notified and be waiting for us:
+         */
+        for_each_online_cpu(i) {
+                while (kgdb_do_roundup && !atomic_read(&cpu_in_kgdb[i]))
+                        cpu_relax();
+        }
+
+        /*
+         * At this point the primary processor is completely
+         * in the debugger and all secondary CPUs are quiescent
+         */
+        dbg_deactivate_sw_breakpoints();
+        kgdb_single_step = 0;
+        kgdb_contthread = current;
+        exception_level = 0;
+        trace_on = tracing_is_on();
+        if (trace_on)
+                tracing_off();
+
+        while (1) {
+cpu_master_loop:
+                if (dbg_kdb_mode) {
+                        kgdb_connected = 1;
+                        error = kdb_stub(ks);
+                        kgdb_connected = 0;
+                } else {
+                        error = gdb_serial_stub(ks);
+                }
+
+                if (error == DBG_PASS_EVENT) {
+                        dbg_kdb_mode = !dbg_kdb_mode;
+                } else if (error == DBG_SWITCH_CPU_EVENT) {
+                        dbg_cpu_switch(cpu, dbg_switch_cpu);
+                        goto cpu_loop;
+                } else {
+                        kgdb_info[cpu].ret_state = error;
+                        break;
+                }
+        }
+
+        /* Call the I/O driver's post_exception routine */
+        if (dbg_io_ops->post_exception)
+                dbg_io_ops->post_exception();
+
+        atomic_dec(&cpu_in_kgdb[ks->cpu]);
+
+        if (!kgdb_single_step) {
+                for (i = NR_CPUS-1; i >= 0; i--)
+                        atomic_dec(&passive_cpu_wait[i]);
+                /*
+                 * Wait till all the CPUs have quit from the debugger,
+                 * but allow a CPU that hit an exception and is
+                 * waiting to become the master to remain in the debug
+                 * core.
+                 */
+                for_each_online_cpu(i) {
+                        while (kgdb_do_roundup &&
+                               atomic_read(&cpu_in_kgdb[i]) &&
+                               !(kgdb_info[i].exception_state &
+                                 DCPU_WANT_MASTER))
+                                cpu_relax();
+                }
+        }
+
+kgdb_restore:
+        if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
+                int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
+                if (kgdb_info[sstep_cpu].task)
+                        kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
+                else
+                        kgdb_sstep_pid = 0;
+        }
+        if (trace_on)
+                tracing_on();
+        /* Free kgdb_active */
+        atomic_set(&kgdb_active, -1);
+        touch_softlockup_watchdog_sync();
+        clocksource_touch_watchdog();
+        local_irq_restore(flags);
+
+        return kgdb_info[cpu].ret_state;
+}
+
+/*
+ * kgdb_handle_exception() - main entry point from a kernel exception
+ *
+ * Locking hierarchy:
+ *      interface locks, if any (begin_session)
+ *      kgdb lock (kgdb_active)
+ */
+int
+kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
+{
+        struct kgdb_state kgdb_var;
+        struct kgdb_state *ks = &kgdb_var;
+        int ret;
+
+        ks->cpu                 = raw_smp_processor_id();
+        ks->ex_vector           = evector;
+        ks->signo               = signo;
+        ks->err_code            = ecode;
+        ks->kgdb_usethreadid    = 0;
+        ks->linux_regs          = regs;
+
+        if (kgdb_reenter_check(ks))
+                return 0; /* Ouch, double exception ! */
+        kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER;
+        ret = kgdb_cpu_enter(ks, regs);
+        kgdb_info[ks->cpu].exception_state &= ~(DCPU_WANT_MASTER |
+                                                DCPU_IS_SLAVE);
+        return ret;
+}
+
+int kgdb_nmicallback(int cpu, void *regs)
+{
+#ifdef CONFIG_SMP
+        struct kgdb_state kgdb_var;
+        struct kgdb_state *ks = &kgdb_var;
+
+        memset(ks, 0, sizeof(struct kgdb_state));
+        ks->cpu                 = cpu;
+        ks->linux_regs          = regs;
+
+        if (!atomic_read(&cpu_in_kgdb[cpu]) &&
+            atomic_read(&kgdb_active) != -1 &&
+            atomic_read(&kgdb_active) != cpu) {
+                kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
+                kgdb_cpu_enter(ks, regs);
+                kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE;
+                return 0;
+        }
+#endif
+        return 1;
+}
+
+static void kgdb_console_write(struct console *co, const char *s,
+   unsigned count)
+{
+        unsigned long flags;
+
+        /* If we're debugging, or KGDB has not connected, don't try
+         * and print. */
+        if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode)
+                return;
+
+        local_irq_save(flags);
+        gdbstub_msg_write(s, count);
+        local_irq_restore(flags);
+}
+
+static struct console kgdbcons = {
+        .name           = "kgdb",
+        .write          = kgdb_console_write,
+        .flags          = CON_PRINTBUFFER | CON_ENABLED,
+        .index          = -1,
+};
+
+#ifdef CONFIG_MAGIC_SYSRQ
+static void sysrq_handle_dbg(int key, struct tty_struct *tty)
+{
+        if (!dbg_io_ops) {
+                printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
+                return;
+        }
+        if (!kgdb_connected) {
+#ifdef CONFIG_KGDB_KDB
+                if (!dbg_kdb_mode)
+                        printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
+#else
+                printk(KERN_CRIT "Entering KGDB\n");
+#endif
+        }
+
+        kgdb_breakpoint();
+}
+
+static struct sysrq_key_op sysrq_dbg_op = {
+        .handler        = sysrq_handle_dbg,
+        .help_msg       = "debug(G)",
+        .action_msg     = "DEBUG",
+};
+#endif
+
+static int kgdb_panic_event(struct notifier_block *self,
+                            unsigned long val,
+                            void *data)
+{
+        if (dbg_kdb_mode)
+                kdb_printf("PANIC: %s\n", (char *)data);
+        kgdb_breakpoint();
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block kgdb_panic_event_nb = {
+       .notifier_call   = kgdb_panic_event,
+       .priority        = INT_MAX,
+};
+
+void __weak kgdb_arch_late(void)
+{
+}
+
+void __init dbg_late_init(void)
+{
+        dbg_is_early = false;
+        if (kgdb_io_module_registered)
+                kgdb_arch_late();
+        kdb_init(KDB_INIT_FULL);
+}
+
+static void kgdb_register_callbacks(void)
+{
+        if (!kgdb_io_module_registered) {
+                kgdb_io_module_registered = 1;
+                kgdb_arch_init();
+                if (!dbg_is_early)
+                        kgdb_arch_late();
+                atomic_notifier_chain_register(&panic_notifier_list,
+                                               &kgdb_panic_event_nb);
+#ifdef CONFIG_MAGIC_SYSRQ
+                register_sysrq_key('g', &sysrq_dbg_op);
+#endif
+                if (kgdb_use_con && !kgdb_con_registered) {
+                        register_console(&kgdbcons);
+                        kgdb_con_registered = 1;
+                }
+        }
+}
+
+static void kgdb_unregister_callbacks(void)
+{
+        /*
+         * When this routine is called KGDB should unregister from the
+         * panic handler and clean up, making sure it is not handling any
+         * break exceptions at the time.
+         */
+        if (kgdb_io_module_registered) {
+                kgdb_io_module_registered = 0;
+                atomic_notifier_chain_unregister(&panic_notifier_list,
+                                               &kgdb_panic_event_nb);
+                kgdb_arch_exit();
+#ifdef CONFIG_MAGIC_SYSRQ
+                unregister_sysrq_key('g', &sysrq_dbg_op);
+#endif
+                if (kgdb_con_registered) {
+                        unregister_console(&kgdbcons);
+                        kgdb_con_registered = 0;
+                }
+        }
+}
+
+/*
+ * There are times a tasklet needs to be used vs a compiled in
+ * break point so as to cause an exception outside a kgdb I/O module,
+ * such as is the case with kgdboe, where calling a breakpoint in the
+ * I/O driver itself would be fatal.
+ */
+static void kgdb_tasklet_bpt(unsigned long ing)
+{
+        kgdb_breakpoint();
+        atomic_set(&kgdb_break_tasklet_var, 0);
+}
+
+static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0);
+
+void kgdb_schedule_breakpoint(void)
+{
+        if (atomic_read(&kgdb_break_tasklet_var) ||
+                atomic_read(&kgdb_active) != -1 ||
+                atomic_read(&kgdb_setting_breakpoint))
+                return;
+        atomic_inc(&kgdb_break_tasklet_var);
+        tasklet_schedule(&kgdb_tasklet_breakpoint);
+}
+EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint);
+
+static void kgdb_initial_breakpoint(void)
+{
+        kgdb_break_asap = 0;
+
+        printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
+        kgdb_breakpoint();
+}
+
+/**
+ *      kgdb_register_io_module - register KGDB IO module
+ *      @new_dbg_io_ops: the io ops vector
+ *
+ *      Register it with the KGDB core.
+ */
+int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
+{
+        int err;
+
+        spin_lock(&kgdb_registration_lock);
+
+        if (dbg_io_ops) {
+                spin_unlock(&kgdb_registration_lock);
+
+                printk(KERN_ERR "kgdb: Another I/O driver is already "
+                                "registered with KGDB.\n");
+                return -EBUSY;
+        }
+
+        if (new_dbg_io_ops->init) {
+                err = new_dbg_io_ops->init();
+                if (err) {
+                        spin_unlock(&kgdb_registration_lock);
+                        return err;
+                }
+        }
+
+        dbg_io_ops = new_dbg_io_ops;
+
+        spin_unlock(&kgdb_registration_lock);
+
+        printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
+               new_dbg_io_ops->name);
+
+        /* Arm KGDB now. */
+        kgdb_register_callbacks();
+
+        if (kgdb_break_asap)
+                kgdb_initial_breakpoint();
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(kgdb_register_io_module);
+
+/**
+ *      kkgdb_unregister_io_module - unregister KGDB IO module
+ *      @old_dbg_io_ops: the io ops vector
+ *
+ *      Unregister it with the KGDB core.
+ */
+void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
+{
+        BUG_ON(kgdb_connected);
+
+        /*
+         * KGDB is no longer able to communicate out, so
+         * unregister our callbacks and reset state.
+         */
+        kgdb_unregister_callbacks();
+
+        spin_lock(&kgdb_registration_lock);
+
+        WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops);
+        dbg_io_ops = NULL;
+
+        spin_unlock(&kgdb_registration_lock);
+
+        printk(KERN_INFO
+                "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
+                old_dbg_io_ops->name);
+}
+EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
+
+int dbg_io_get_char(void)
+{
+        int ret = dbg_io_ops->read_char();
+        if (ret == NO_POLL_CHAR)
+                return -1;
+        if (!dbg_kdb_mode)
+                return ret;
+        if (ret == 127)
+                return 8;
+        return ret;
+}
+
+/**
+ * kgdb_breakpoint - generate breakpoint exception
+ *
+ * This function will generate a breakpoint exception.  It is used at the
+ * beginning of a program to sync up with a debugger and can be used
+ * otherwise as a quick means to stop program execution and "break" into
+ * the debugger.
+ */
+void kgdb_breakpoint(void)
+{
+        atomic_inc(&kgdb_setting_breakpoint);
+        wmb(); /* Sync point before breakpoint */
+        arch_kgdb_breakpoint();
+        wmb(); /* Sync point after breakpoint */
+        atomic_dec(&kgdb_setting_breakpoint);
+}
+EXPORT_SYMBOL_GPL(kgdb_breakpoint);
+
+static int __init opt_kgdb_wait(char *str)
+{
+        kgdb_break_asap = 1;
+
+        kdb_init(KDB_INIT_EARLY);
+        if (kgdb_io_module_registered)
+                kgdb_initial_breakpoint();
+
+        return 0;
+}
+
+early_param("kgdbwait", opt_kgdb_wait);