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-rw-r--r--kernel/debug/debug_core.c967
1 files changed, 967 insertions, 0 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
new file mode 100644
index 000000000000..64b5588c9638
--- /dev/null
+++ b/kernel/debug/debug_core.c
@@ -0,0 +1,967 @@
+/*
+ * 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;
+/* 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);
+ } else {
+ error = gdb_serial_stub(ks);
+ }
+
+ if (error == DBG_PASS_EVENT) {
+ dbg_kdb_mode = !dbg_kdb_mode;
+ kgdb_connected = 0;
+ } 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,
+};
+
+static void kgdb_register_callbacks(void)
+{
+ if (!kgdb_io_module_registered) {
+ kgdb_io_module_registered = 1;
+ kgdb_arch_init();
+ 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);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.