kgdb: core
authorJason Wessel <jason.wessel@windriver.com>
Thu, 17 Apr 2008 18:05:37 +0000 (20:05 +0200)
committerIngo Molnar <mingo@elte.hu>
Thu, 17 Apr 2008 18:05:37 +0000 (20:05 +0200)
kgdb core code. Handles the protocol and the arch details.

[ mingo@elte.hu: heavily modified, simplified and cleaned up. ]
[ xemul@openvz.org: use find_task_by_pid_ns ]

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
include/linux/kgdb.h [new file with mode: 0644]
kernel/Makefile
kernel/kgdb.c [new file with mode: 0644]
lib/Kconfig.debug
lib/Kconfig.kgdb [new file with mode: 0644]

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
new file mode 100644 (file)
index 0000000..b0985b7
--- /dev/null
@@ -0,0 +1,271 @@
+/*
+ * This provides the callbacks and functions that KGDB needs to share between
+ * the core, I/O and arch-specific portions.
+ *
+ * Author: Amit Kale <amitkale@linsyssoft.com> and
+ *         Tom Rini <trini@kernel.crashing.org>
+ *
+ * 2001-2004 (c) Amit S. Kale and 2003-2005 (c) MontaVista Software, Inc.
+ * 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.
+ */
+#ifndef _KGDB_H_
+#define _KGDB_H_
+
+#include <linux/serial_8250.h>
+#include <linux/linkage.h>
+#include <linux/init.h>
+
+#include <asm/atomic.h>
+#include <asm/kgdb.h>
+
+struct pt_regs;
+
+/*
+ *     kgdb_skipexception - Bail out of KGDB when we've been triggered.
+ *     @exception: Exception vector number
+ *     @regs: Current &struct pt_regs.
+ *
+ *     On some architectures we need to skip a breakpoint exception when
+ *     it occurs after a breakpoint has been removed.
+ */
+extern int kgdb_skipexception(int exception, struct pt_regs *regs);
+
+/*
+ *     kgdb_post_primary_code - Save error vector/code numbers.
+ *     @regs: Original pt_regs.
+ *     @e_vector: Original error vector.
+ *     @err_code: Original error code.
+ *
+ *     This is needed on architectures which support SMP and KGDB.
+ *     This function is called after all the secondary cpus have been put
+ *     to a know spin state and the primary CPU has control over KGDB.
+ */
+extern void kgdb_post_primary_code(struct pt_regs *regs, int e_vector,
+                                 int err_code);
+
+/*
+ *     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.
+ */
+extern void kgdb_disable_hw_debug(struct pt_regs *regs);
+
+struct tasklet_struct;
+struct task_struct;
+struct uart_port;
+
+/* To enter the debugger explicitly. */
+void kgdb_breakpoint(void);
+
+extern int kgdb_connected;
+
+extern atomic_t                        kgdb_setting_breakpoint;
+extern atomic_t                        kgdb_cpu_doing_single_step;
+
+extern struct task_struct      *kgdb_usethread;
+extern struct task_struct      *kgdb_contthread;
+
+enum kgdb_bptype {
+       BP_BREAKPOINT = 0,
+       BP_HARDWARE_BREAKPOINT,
+       BP_WRITE_WATCHPOINT,
+       BP_READ_WATCHPOINT,
+       BP_ACCESS_WATCHPOINT
+};
+
+enum kgdb_bpstate {
+       BP_UNDEFINED = 0,
+       BP_REMOVED,
+       BP_SET,
+       BP_ACTIVE
+};
+
+struct kgdb_bkpt {
+       unsigned long           bpt_addr;
+       unsigned char           saved_instr[BREAK_INSTR_SIZE];
+       enum kgdb_bptype        type;
+       enum kgdb_bpstate       state;
+};
+
+#ifndef KGDB_MAX_BREAKPOINTS
+# define KGDB_MAX_BREAKPOINTS  1000
+#endif
+
+#define KGDB_HW_BREAKPOINT     1
+
+/*
+ * Functions each KGDB-supporting architecture must provide:
+ */
+
+/*
+ *     kgdb_arch_init - Perform any architecture specific initalization.
+ *
+ *     This function will handle the initalization of any architecture
+ *     specific callbacks.
+ */
+extern int kgdb_arch_init(void);
+
+/*
+ *     kgdb_arch_exit - Perform any architecture specific uninitalization.
+ *
+ *     This function will handle the uninitalization of any architecture
+ *     specific callbacks, for dynamic registration and unregistration.
+ */
+extern void kgdb_arch_exit(void);
+
+/*
+ *     pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
+ *     @gdb_regs: A pointer to hold the registers in the order GDB wants.
+ *     @regs: The &struct pt_regs of the current process.
+ *
+ *     Convert the pt_regs in @regs into the format for registers that
+ *     GDB expects, stored in @gdb_regs.
+ */
+extern void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs);
+
+/*
+ *     sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
+ *     @gdb_regs: A pointer to hold the registers in the order GDB wants.
+ *     @p: The &struct task_struct of the desired process.
+ *
+ *     Convert the register values of the sleeping process in @p to
+ *     the format that GDB expects.
+ *     This function is called when kgdb does not have access to the
+ *     &struct pt_regs and therefore it should fill the gdb registers
+ *     @gdb_regs with what has been saved in &struct thread_struct
+ *     thread field during switch_to.
+ */
+extern void
+sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p);
+
+/*
+ *     gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
+ *     @gdb_regs: A pointer to hold the registers we've received from GDB.
+ *     @regs: A pointer to a &struct pt_regs to hold these values in.
+ *
+ *     Convert the GDB regs in @gdb_regs into the pt_regs, and store them
+ *     in @regs.
+ */
+extern void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs);
+
+/*
+ *     kgdb_arch_handle_exception - Handle architecture specific GDB packets.
+ *     @vector: The error vector of the exception that happened.
+ *     @signo: The signal number of the exception that happened.
+ *     @err_code: The error code of the exception that happened.
+ *     @remcom_in_buffer: The buffer of the packet we have read.
+ *     @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
+ *     @regs: The &struct pt_regs of the current process.
+ *
+ *     This function MUST handle the 'c' and 's' command packets,
+ *     as well packets to set / remove a hardware breakpoint, if used.
+ *     If there are additional packets which the hardware needs to handle,
+ *     they are handled here.  The code should return -1 if it wants to
+ *     process more packets, and a %0 or %1 if it wants to exit from the
+ *     kgdb callback.
+ */
+extern int
+kgdb_arch_handle_exception(int vector, int signo, int err_code,
+                          char *remcom_in_buffer,
+                          char *remcom_out_buffer,
+                          struct pt_regs *regs);
+
+/*
+ *     kgdb_roundup_cpus - Get other CPUs into a holding pattern
+ *     @flags: Current IRQ state
+ *
+ *     On SMP systems, we need to get the attention of the other CPUs
+ *     and get them be in a known state.  This should do what is needed
+ *     to get the other CPUs to call kgdb_wait(). Note that on some arches,
+ *     the NMI approach is not used for rounding up all the CPUs. For example,
+ *     in case of MIPS, smp_call_function() is used to roundup CPUs. In
+ *     this case, we have to make sure that interrupts are enabled before
+ *     calling smp_call_function(). The argument to this function is
+ *     the flags that will be used when restoring the interrupts. There is
+ *     local_irq_save() call before kgdb_roundup_cpus().
+ *
+ *     On non-SMP systems, this is not called.
+ */
+extern void kgdb_roundup_cpus(unsigned long flags);
+
+/* Optional functions. */
+extern int kgdb_validate_break_address(unsigned long addr);
+extern int kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr);
+extern int kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle);
+
+/*
+ * struct kgdb_arch - Describe architecture specific values.
+ * @gdb_bpt_instr: The instruction to trigger a breakpoint.
+ * @flags: Flags for the breakpoint, currently just %KGDB_HW_BREAKPOINT.
+ * @set_breakpoint: Allow an architecture to specify how to set a software
+ * breakpoint.
+ * @remove_breakpoint: Allow an architecture to specify how to remove a
+ * software breakpoint.
+ * @set_hw_breakpoint: Allow an architecture to specify how to set a hardware
+ * breakpoint.
+ * @remove_hw_breakpoint: Allow an architecture to specify how to remove a
+ * hardware breakpoint.
+ * @remove_all_hw_break: Allow an architecture to specify how to remove all
+ * hardware breakpoints.
+ * @correct_hw_break: Allow an architecture to specify how to correct the
+ * hardware debug registers.
+ */
+struct kgdb_arch {
+       unsigned char           gdb_bpt_instr[BREAK_INSTR_SIZE];
+       unsigned long           flags;
+
+       int     (*set_breakpoint)(unsigned long, char *);
+       int     (*remove_breakpoint)(unsigned long, char *);
+       int     (*set_hw_breakpoint)(unsigned long, int, enum kgdb_bptype);
+       int     (*remove_hw_breakpoint)(unsigned long, int, enum kgdb_bptype);
+       void    (*remove_all_hw_break)(void);
+       void    (*correct_hw_break)(void);
+};
+
+/*
+ * struct kgdb_io - Describe the interface for an I/O driver to talk with KGDB.
+ * @name: Name of the I/O driver.
+ * @read_char: Pointer to a function that will return one char.
+ * @write_char: Pointer to a function that will write one char.
+ * @flush: Pointer to a function that will flush any pending writes.
+ * @init: Pointer to a function that will initialize the device.
+ * @pre_exception: Pointer to a function that will do any prep work for
+ * the I/O driver.
+ * @post_exception: Pointer to a function that will do any cleanup work
+ * for the I/O driver.
+ */
+struct kgdb_io {
+       const char              *name;
+       int                     (*read_char) (void);
+       void                    (*write_char) (u8);
+       void                    (*flush) (void);
+       int                     (*init) (void);
+       void                    (*pre_exception) (void);
+       void                    (*post_exception) (void);
+};
+
+extern struct kgdb_arch                arch_kgdb_ops;
+
+extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
+extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
+
+extern int kgdb_hex2long(char **ptr, long *long_val);
+extern int kgdb_mem2hex(char *mem, char *buf, int count);
+extern int kgdb_hex2mem(char *buf, char *mem, int count);
+
+extern int kgdb_isremovedbreak(unsigned long addr);
+
+extern int
+kgdb_handle_exception(int ex_vector, int signo, int err_code,
+                     struct pt_regs *regs);
+extern int kgdb_nmicallback(int cpu, void *regs);
+
+extern int                     kgdb_single_step;
+extern atomic_t                        kgdb_active;
+
+#endif /* _KGDB_H_ */
index 6c584c55a6e9e8f164fa949b8a5c5ed8054ed9f8..05c8003718eefa0b7257ccaa4b8eb21f66bccb9b 100644 (file)
@@ -53,6 +53,7 @@ obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
 obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
 obj-$(CONFIG_AUDIT_TREE) += audit_tree.o
 obj-$(CONFIG_KPROBES) += kprobes.o
+obj-$(CONFIG_KGDB) += kgdb.o
 obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o
 obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
 obj-$(CONFIG_SECCOMP) += seccomp.o
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
new file mode 100644 (file)
index 0000000..017ee78
--- /dev/null
@@ -0,0 +1,1693 @@
+/*
+ * KGDB stub.
+ *
+ * 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) 2005-2008 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/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/reboot.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/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>
+
+static int kgdb_break_asap;
+
+struct kgdb_state {
+       int                     ex_vector;
+       int                     signo;
+       int                     err_code;
+       int                     cpu;
+       int                     pass_exception;
+       long                    threadid;
+       long                    kgdb_usethreadid;
+       struct pt_regs          *linux_regs;
+};
+
+static struct debuggerinfo_struct {
+       void                    *debuggerinfo;
+       struct task_struct      *task;
+} 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 */
+static int                     kgdb_io_module_registered;
+
+/* Guard for recursive entry */
+static int                     exception_level;
+
+static struct kgdb_io          *kgdb_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;
+
+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);
+
+/*
+ * 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];
+atomic_t                       kgdb_setting_breakpoint;
+
+struct task_struct             *kgdb_usethread;
+struct task_struct             *kgdb_contthread;
+
+int                            kgdb_single_step;
+
+/* Our I/O buffers. */
+static char                    remcom_in_buffer[BUFMAX];
+static char                    remcom_out_buffer[BUFMAX];
+
+/* Storage for the registers, in GDB format. */
+static unsigned long           gdb_regs[(NUMREGBYTES +
+                                       sizeof(unsigned long) - 1) /
+                                       sizeof(unsigned long)];
+
+/* 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:
+ */
+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_validate_break_address(unsigned long addr)
+{
+       char tmp_variable[BREAK_INSTR_SIZE];
+
+       return probe_kernel_read(tmp_variable, (char *)addr, BREAK_INSTR_SIZE);
+}
+
+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);
+}
+
+unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
+{
+       return instruction_pointer(regs);
+}
+
+int __weak kgdb_arch_init(void)
+{
+       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)
+{
+}
+
+/*
+ * GDB remote protocol parser:
+ */
+
+static const char      hexchars[] = "0123456789abcdef";
+
+static int hex(char ch)
+{
+       if ((ch >= 'a') && (ch <= 'f'))
+               return ch - 'a' + 10;
+       if ((ch >= '0') && (ch <= '9'))
+               return ch - '0';
+       if ((ch >= 'A') && (ch <= 'F'))
+               return ch - 'A' + 10;
+       return -1;
+}
+
+/* scan for the sequence $<data>#<checksum> */
+static void get_packet(char *buffer)
+{
+       unsigned char checksum;
+       unsigned char xmitcsum;
+       int count;
+       char ch;
+
+       do {
+               /*
+                * Spin and wait around for the start character, ignore all
+                * other characters:
+                */
+               while ((ch = (kgdb_io_ops->read_char())) != '$')
+                       /* nothing */;
+
+               kgdb_connected = 1;
+               checksum = 0;
+               xmitcsum = -1;
+
+               count = 0;
+
+               /*
+                * now, read until a # or end of buffer is found:
+                */
+               while (count < (BUFMAX - 1)) {
+                       ch = kgdb_io_ops->read_char();
+                       if (ch == '#')
+                               break;
+                       checksum = checksum + ch;
+                       buffer[count] = ch;
+                       count = count + 1;
+               }
+               buffer[count] = 0;
+
+               if (ch == '#') {
+                       xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
+                       xmitcsum += hex(kgdb_io_ops->read_char());
+
+                       if (checksum != xmitcsum)
+                               /* failed checksum */
+                               kgdb_io_ops->write_char('-');
+                       else
+                               /* successful transfer */
+                               kgdb_io_ops->write_char('+');
+                       if (kgdb_io_ops->flush)
+                               kgdb_io_ops->flush();
+               }
+       } while (checksum != xmitcsum);
+}
+
+/*
+ * Send the packet in buffer.
+ * Check for gdb connection if asked for.
+ */
+static void put_packet(char *buffer)
+{
+       unsigned char checksum;
+       int count;
+       char ch;
+
+       /*
+        * $<packet info>#<checksum>.
+        */
+       while (1) {
+               kgdb_io_ops->write_char('$');
+               checksum = 0;
+               count = 0;
+
+               while ((ch = buffer[count])) {
+                       kgdb_io_ops->write_char(ch);
+                       checksum += ch;
+                       count++;
+               }
+
+               kgdb_io_ops->write_char('#');
+               kgdb_io_ops->write_char(hexchars[checksum >> 4]);
+               kgdb_io_ops->write_char(hexchars[checksum & 0xf]);
+               if (kgdb_io_ops->flush)
+                       kgdb_io_ops->flush();
+
+               /* Now see what we get in reply. */
+               ch = kgdb_io_ops->read_char();
+
+               if (ch == 3)
+                       ch = kgdb_io_ops->read_char();
+
+               /* If we get an ACK, we are done. */
+               if (ch == '+')
+                       return;
+
+               /*
+                * If we get the start of another packet, this means
+                * that GDB is attempting to reconnect.  We will NAK
+                * the packet being sent, and stop trying to send this
+                * packet.
+                */
+               if (ch == '$') {
+                       kgdb_io_ops->write_char('-');
+                       if (kgdb_io_ops->flush)
+                               kgdb_io_ops->flush();
+                       return;
+               }
+       }
+}
+
+static char *pack_hex_byte(char *pkt, u8 byte)
+{
+       *pkt++ = hexchars[byte >> 4];
+       *pkt++ = hexchars[byte & 0xf];
+
+       return pkt;
+}
+
+/*
+ * Convert the memory pointed to by mem into hex, placing result in buf.
+ * Return a pointer to the last char put in buf (null). May return an error.
+ */
+int kgdb_mem2hex(char *mem, char *buf, int count)
+{
+       char *tmp;
+       int err;
+
+       /*
+        * We use the upper half of buf as an intermediate buffer for the
+        * raw memory copy.  Hex conversion will work against this one.
+        */
+       tmp = buf + count;
+
+       err = probe_kernel_read(tmp, mem, count);
+       if (!err) {
+               while (count > 0) {
+                       buf = pack_hex_byte(buf, *tmp);
+                       tmp++;
+                       count--;
+               }
+
+               *buf = 0;
+       }
+
+       return err;
+}
+
+/*
+ * Copy the binary array pointed to by buf into mem.  Fix $, #, and
+ * 0x7d escaped with 0x7d.  Return a pointer to the character after
+ * the last byte written.
+ */
+static int kgdb_ebin2mem(char *buf, char *mem, int count)
+{
+       int err = 0;
+       char c;
+
+       while (count-- > 0) {
+               c = *buf++;
+               if (c == 0x7d)
+                       c = *buf++ ^ 0x20;
+
+               err = probe_kernel_write(mem, &c, 1);
+               if (err)
+                       break;
+
+               mem++;
+       }
+
+       return err;
+}
+
+/*
+ * Convert the hex array pointed to by buf into binary to be placed in mem.
+ * Return a pointer to the character AFTER the last byte written.
+ * May return an error.
+ */
+int kgdb_hex2mem(char *buf, char *mem, int count)
+{
+       char *tmp_raw;
+       char *tmp_hex;
+
+       /*
+        * We use the upper half of buf as an intermediate buffer for the
+        * raw memory that is converted from hex.
+        */
+       tmp_raw = buf + count * 2;
+
+       tmp_hex = tmp_raw - 1;
+       while (tmp_hex >= buf) {
+               tmp_raw--;
+               *tmp_raw = hex(*tmp_hex--);
+               *tmp_raw |= hex(*tmp_hex--) << 4;
+       }
+
+       return probe_kernel_write(mem, tmp_raw, count);
+}
+
+/*
+ * While we find nice hex chars, build a long_val.
+ * Return number of chars processed.
+ */
+int kgdb_hex2long(char **ptr, long *long_val)
+{
+       int hex_val;
+       int num = 0;
+
+       *long_val = 0;
+
+       while (**ptr) {
+               hex_val = hex(**ptr);
+               if (hex_val < 0)
+                       break;
+
+               *long_val = (*long_val << 4) | hex_val;
+               num++;
+               (*ptr)++;
+       }
+
+       return num;
+}
+
+/* Write memory due to an 'M' or 'X' packet. */
+static int write_mem_msg(int binary)
+{
+       char *ptr = &remcom_in_buffer[1];
+       unsigned long addr;
+       unsigned long length;
+       int err;
+
+       if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
+           kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
+               if (binary)
+                       err = kgdb_ebin2mem(ptr, (char *)addr, length);
+               else
+                       err = kgdb_hex2mem(ptr, (char *)addr, length);
+               if (err)
+                       return err;
+               if (CACHE_FLUSH_IS_SAFE)
+                       flush_icache_range(addr, addr + length + 1);
+               return 0;
+       }
+
+       return -EINVAL;
+}
+
+static void error_packet(char *pkt, int error)
+{
+       error = -error;
+       pkt[0] = 'E';
+       pkt[1] = hexchars[(error / 10)];
+       pkt[2] = hexchars[(error % 10)];
+       pkt[3] = '\0';
+}
+
+/*
+ * Thread ID accessors. We represent a flat TID space to GDB, where
+ * the per CPU idle threads (which under Linux all have PID 0) are
+ * remapped to negative TIDs.
+ */
+
+#define BUF_THREAD_ID_SIZE     16
+
+static char *pack_threadid(char *pkt, unsigned char *id)
+{
+       char *limit;
+
+       limit = pkt + BUF_THREAD_ID_SIZE;
+       while (pkt < limit)
+               pkt = pack_hex_byte(pkt, *id++);
+
+       return pkt;
+}
+
+static void int_to_threadref(unsigned char *id, int value)
+{
+       unsigned char *scan;
+       int i = 4;
+
+       scan = (unsigned char *)id;
+       while (i--)
+               *scan++ = 0;
+       *scan++ = (value >> 24) & 0xff;
+       *scan++ = (value >> 16) & 0xff;
+       *scan++ = (value >> 8) & 0xff;
+       *scan++ = (value & 0xff);
+}
+
+static struct task_struct *getthread(struct pt_regs *regs, int tid)
+{
+       /*
+        * Non-positive TIDs are remapped idle tasks:
+        */
+       if (tid <= 0)
+               return idle_task(-tid);
+
+       /*
+        * find_task_by_pid_ns() does not take the tasklist lock anymore
+        * but is nicely RCU locked - hence is a pretty resilient
+        * thing to use:
+        */
+       return find_task_by_pid_ns(tid, &init_pid_ns);
+}
+
+/*
+ * CPU debug state control:
+ */
+
+#ifdef CONFIG_SMP
+static void kgdb_wait(struct pt_regs *regs)
+{
+       unsigned long flags;
+       int cpu;
+
+       local_irq_save(flags);
+       cpu = raw_smp_processor_id();
+       kgdb_info[cpu].debuggerinfo = regs;
+       kgdb_info[cpu].task = current;
+       /*
+        * Make sure the above info reaches the primary CPU before
+        * our cpu_in_kgdb[] flag setting does:
+        */
+       smp_wmb();
+       atomic_set(&cpu_in_kgdb[cpu], 1);
+
+       /*
+        * The primary CPU must be active to enter here, but this is
+        * guard in case the primary CPU had not been selected if
+        * this was an entry via nmi.
+        */
+       while (atomic_read(&kgdb_active) == -1)
+               cpu_relax();
+
+       /* Wait till primary CPU goes completely into the debugger. */
+       while (!atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)]))
+               cpu_relax();
+
+       /* Wait till primary CPU is done with debugging */
+       while (atomic_read(&passive_cpu_wait[cpu]))
+               cpu_relax();
+
+       kgdb_info[cpu].debuggerinfo = NULL;
+       kgdb_info[cpu].task = NULL;
+
+       /* fix up hardware debug registers on local cpu */
+       if (arch_kgdb_ops.correct_hw_break)
+               arch_kgdb_ops.correct_hw_break();
+
+       /* Signal the primary CPU that we are done: */
+       atomic_set(&cpu_in_kgdb[cpu], 0);
+       local_irq_restore(flags);
+}
+#endif
+
+/*
+ * 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) {
+               flush_cache_range(current->mm->mmap_cache,
+                                 addr, addr + BREAK_INSTR_SIZE);
+       } else {
+               flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
+       }
+}
+
+/*
+ * SW breakpoint management:
+ */
+static int kgdb_activate_sw_breakpoints(void)
+{
+       unsigned long addr;
+       int error = 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)
+                       return error;
+
+               kgdb_flush_swbreak_addr(addr);
+               kgdb_break[i].state = BP_ACTIVE;
+       }
+       return 0;
+}
+
+static int kgdb_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;
+}
+
+static int kgdb_deactivate_sw_breakpoints(void)
+{
+       unsigned long addr;
+       int error = 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)
+                       return error;
+
+               kgdb_flush_swbreak_addr(addr);
+               kgdb_break[i].state = BP_SET;
+       }
+       return 0;
+}
+
+static int kgdb_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 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_SET)
+                       continue;
+               addr = kgdb_break[i].bpt_addr;
+               error = kgdb_arch_remove_breakpoint(addr,
+                               kgdb_break[i].saved_instr);
+               if (error)
+                       return error;
+               kgdb_break[i].state = BP_REMOVED;
+       }
+
+       /* Clear hardware breakpoints. */
+       if (arch_kgdb_ops.remove_all_hw_break)
+               arch_kgdb_ops.remove_all_hw_break();
+
+       return 0;
+}
+
+/*
+ * Remap normal tasks to their real PID, idle tasks to -1 ... -NR_CPUs:
+ */
+static inline int shadow_pid(int realpid)
+{
+       if (realpid)
+               return realpid;
+
+       return -1-raw_smp_processor_id();
+}
+
+static char gdbmsgbuf[BUFMAX + 1];
+
+static void kgdb_msg_write(const char *s, int len)
+{
+       char *bufptr;
+       int wcount;
+       int i;
+
+       /* 'O'utput */
+       gdbmsgbuf[0] = 'O';
+
+       /* Fill and send buffers... */
+       while (len > 0) {
+               bufptr = gdbmsgbuf + 1;
+
+               /* Calculate how many this time */
+               if ((len << 1) > (BUFMAX - 2))
+                       wcount = (BUFMAX - 2) >> 1;
+               else
+                       wcount = len;
+
+               /* Pack in hex chars */
+               for (i = 0; i < wcount; i++)
+                       bufptr = pack_hex_byte(bufptr, s[i]);
+               *bufptr = '\0';
+
+               /* Move up */
+               s += wcount;
+               len -= wcount;
+
+               /* Write packet */
+               put_packet(gdbmsgbuf);
+       }
+}
+
+/*
+ * 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 (!kgdb_io_ops)
+               return 0;
+       if (kgdb_connected)
+               return 1;
+       if (atomic_read(&kgdb_setting_breakpoint))
+               return 1;
+       if (print_wait)
+               printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
+       return 1;
+}
+
+/*
+ * All the functions that start with gdb_cmd are the various
+ * operations to implement the handlers for the gdbserial protocol
+ * where KGDB is communicating with an external debugger
+ */
+
+/* Handle the '?' status packets */
+static void gdb_cmd_status(struct kgdb_state *ks)
+{
+       /*
+        * We know that this packet is only sent
+        * during initial connect.  So to be safe,
+        * we clear out our breakpoints now in case
+        * GDB is reconnecting.
+        */
+       remove_all_break();
+
+       remcom_out_buffer[0] = 'S';
+       pack_hex_byte(&remcom_out_buffer[1], ks->signo);
+}
+
+/* Handle the 'g' get registers request */
+static void gdb_cmd_getregs(struct kgdb_state *ks)
+{
+       struct task_struct *thread;
+       void *local_debuggerinfo;
+       int i;
+
+       thread = kgdb_usethread;
+       if (!thread) {
+               thread = kgdb_info[ks->cpu].task;
+               local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
+       } else {
+               local_debuggerinfo = NULL;
+               for (i = 0; i < NR_CPUS; i++) {
+                       /*
+                        * Try to find the task on some other
+                        * or possibly this node if we do not
+                        * find the matching task then we try
+                        * to approximate the results.
+                        */
+                       if (thread == kgdb_info[i].task)
+                               local_debuggerinfo = kgdb_info[i].debuggerinfo;
+               }
+       }
+
+       /*
+        * All threads that don't have debuggerinfo should be
+        * in __schedule() sleeping, since all other CPUs
+        * are in kgdb_wait, and thus have debuggerinfo.
+        */
+       if (local_debuggerinfo) {
+               pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
+       } else {
+               /*
+                * Pull stuff saved during switch_to; nothing
+                * else is accessible (or even particularly
+                * relevant).
+                *
+                * This should be enough for a stack trace.
+                */
+               sleeping_thread_to_gdb_regs(gdb_regs, thread);
+       }
+       kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
+}
+
+/* Handle the 'G' set registers request */
+static void gdb_cmd_setregs(struct kgdb_state *ks)
+{
+       kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
+
+       if (kgdb_usethread && kgdb_usethread != current) {
+               error_packet(remcom_out_buffer, -EINVAL);
+       } else {
+               gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
+               strcpy(remcom_out_buffer, "OK");
+       }
+}
+
+/* Handle the 'm' memory read bytes */
+static void gdb_cmd_memread(struct kgdb_state *ks)
+{
+       char *ptr = &remcom_in_buffer[1];
+       unsigned long length;
+       unsigned long addr;
+       int err;
+
+       if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
+                                       kgdb_hex2long(&ptr, &length) > 0) {
+               err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
+               if (err)
+                       error_packet(remcom_out_buffer, err);
+       } else {
+               error_packet(remcom_out_buffer, -EINVAL);
+       }
+}
+
+/* Handle the 'M' memory write bytes */
+static void gdb_cmd_memwrite(struct kgdb_state *ks)
+{
+       int err = write_mem_msg(0);
+
+       if (err)
+               error_packet(remcom_out_buffer, err);
+       else
+               strcpy(remcom_out_buffer, "OK");
+}
+
+/* Handle the 'X' memory binary write bytes */
+static void gdb_cmd_binwrite(struct kgdb_state *ks)
+{
+       int err = write_mem_msg(1);
+
+       if (err)
+               error_packet(remcom_out_buffer, err);
+       else
+               strcpy(remcom_out_buffer, "OK");
+}
+
+/* Handle the 'D' or 'k', detach or kill packets */
+static void gdb_cmd_detachkill(struct kgdb_state *ks)
+{
+       int error;
+
+       /* The detach case */
+       if (remcom_in_buffer[0] == 'D') {
+               error = remove_all_break();
+               if (error < 0) {
+                       error_packet(remcom_out_buffer, error);
+               } else {
+                       strcpy(remcom_out_buffer, "OK");
+                       kgdb_connected = 0;
+               }
+               put_packet(remcom_out_buffer);
+       } else {
+               /*
+                * Assume the kill case, with no exit code checking,
+                * trying to force detach the debugger:
+                */
+               remove_all_break();
+               kgdb_connected = 0;
+       }
+}
+
+/* Handle the 'R' reboot packets */
+static int gdb_cmd_reboot(struct kgdb_state *ks)
+{
+       /* For now, only honor R0 */
+       if (strcmp(remcom_in_buffer, "R0") == 0) {
+               printk(KERN_CRIT "Executing emergency reboot\n");
+               strcpy(remcom_out_buffer, "OK");
+               put_packet(remcom_out_buffer);
+
+               /*
+                * Execution should not return from
+                * machine_emergency_restart()
+                */
+               machine_emergency_restart();
+               kgdb_connected = 0;
+
+               return 1;
+       }
+       return 0;
+}
+
+/* Handle the 'q' query packets */
+static void gdb_cmd_query(struct kgdb_state *ks)
+{
+       struct task_struct *thread;
+       unsigned char thref[8];
+       char *ptr;
+       int i;
+
+       switch (remcom_in_buffer[1]) {
+       case 's':
+       case 'f':
+               if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
+                       error_packet(remcom_out_buffer, -EINVAL);
+                       break;
+               }
+
+               if (remcom_in_buffer[1] == 'f')
+                       ks->threadid = 1;
+
+               remcom_out_buffer[0] = 'm';
+               ptr = remcom_out_buffer + 1;
+
+               for (i = 0; i < 17; ks->threadid++) {
+                       thread = getthread(ks->linux_regs, ks->threadid);
+                       if (thread) {
+                               int_to_threadref(thref, ks->threadid);
+                               pack_threadid(ptr, thref);
+                               ptr += BUF_THREAD_ID_SIZE;
+                               *(ptr++) = ',';
+                               i++;
+                       }
+               }
+               *(--ptr) = '\0';
+               break;
+
+       case 'C':
+               /* Current thread id */
+               strcpy(remcom_out_buffer, "QC");
+               ks->threadid = shadow_pid(current->pid);
+               int_to_threadref(thref, ks->threadid);
+               pack_threadid(remcom_out_buffer + 2, thref);
+               break;
+       case 'T':
+               if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
+                       error_packet(remcom_out_buffer, -EINVAL);
+                       break;
+               }
+               ks->threadid = 0;
+               ptr = remcom_in_buffer + 17;
+               kgdb_hex2long(&ptr, &ks->threadid);
+               if (!getthread(ks->linux_regs, ks->threadid)) {
+                       error_packet(remcom_out_buffer, -EINVAL);
+                       break;
+               }
+               if (ks->threadid > 0) {
+                       kgdb_mem2hex(getthread(ks->linux_regs,
+                                       ks->threadid)->comm,
+                                       remcom_out_buffer, 16);
+               } else {
+                       static char tmpstr[23 + BUF_THREAD_ID_SIZE];
+
+                       sprintf(tmpstr, "Shadow task %d for pid 0",
+                                       (int)(-ks->threadid-1));
+                       kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
+               }
+               break;
+       }
+}
+
+/* Handle the 'H' task query packets */
+static void gdb_cmd_task(struct kgdb_state *ks)
+{
+       struct task_struct *thread;
+       char *ptr;
+
+       switch (remcom_in_buffer[1]) {
+       case 'g':
+               ptr = &remcom_in_buffer[2];
+               kgdb_hex2long(&ptr, &ks->threadid);
+               thread = getthread(ks->linux_regs, ks->threadid);
+               if (!thread && ks->threadid > 0) {
+                       error_packet(remcom_out_buffer, -EINVAL);
+                       break;
+               }
+               kgdb_usethread = thread;
+               ks->kgdb_usethreadid = ks->threadid;
+               strcpy(remcom_out_buffer, "OK");
+               break;
+       case 'c':
+               ptr = &remcom_in_buffer[2];
+               kgdb_hex2long(&ptr, &ks->threadid);
+               if (!ks->threadid) {
+                       kgdb_contthread = NULL;
+               } else {
+                       thread = getthread(ks->linux_regs, ks->threadid);
+                       if (!thread && ks->threadid > 0) {
+                               error_packet(remcom_out_buffer, -EINVAL);
+                               break;
+                       }
+                       kgdb_contthread = thread;
+               }
+               strcpy(remcom_out_buffer, "OK");
+               break;
+       }
+}
+
+/* Handle the 'T' thread query packets */
+static void gdb_cmd_thread(struct kgdb_state *ks)
+{
+       char *ptr = &remcom_in_buffer[1];
+       struct task_struct *thread;
+
+       kgdb_hex2long(&ptr, &ks->threadid);
+       thread = getthread(ks->linux_regs, ks->threadid);
+       if (thread)
+               strcpy(remcom_out_buffer, "OK");
+       else
+               error_packet(remcom_out_buffer, -EINVAL);
+}
+
+/* Handle the 'z' or 'Z' breakpoint remove or set packets */
+static void gdb_cmd_break(struct kgdb_state *ks)
+{
+       /*
+        * Since GDB-5.3, it's been drafted that '0' is a software
+        * breakpoint, '1' is a hardware breakpoint, so let's do that.
+        */
+       char *bpt_type = &remcom_in_buffer[1];
+       char *ptr = &remcom_in_buffer[2];
+       unsigned long addr;
+       unsigned long length;
+       int error = 0;
+
+       if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
+               /* Unsupported */
+               if (*bpt_type > '4')
+                       return;
+       } else {
+               if (*bpt_type != '0' && *bpt_type != '1')
+                       /* Unsupported. */
+                       return;
+       }
+
+       /*
+        * Test if this is a hardware breakpoint, and
+        * if we support it:
+        */
+       if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
+               /* Unsupported. */
+               return;
+
+       if (*(ptr++) != ',') {
+               error_packet(remcom_out_buffer, -EINVAL);
+               return;
+       }
+       if (!kgdb_hex2long(&ptr, &addr)) {
+               error_packet(remcom_out_buffer, -EINVAL);
+               return;
+       }
+       if (*(ptr++) != ',' ||
+               !kgdb_hex2long(&ptr, &length)) {
+               error_packet(remcom_out_buffer, -EINVAL);
+               return;
+       }
+
+       if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
+               error = kgdb_set_sw_break(addr);
+       else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
+               error = kgdb_remove_sw_break(addr);
+       else if (remcom_in_buffer[0] == 'Z')
+               error = arch_kgdb_ops.set_hw_breakpoint(addr,
+                       (int)length, *bpt_type);
+       else if (remcom_in_buffer[0] == 'z')
+               error = arch_kgdb_ops.remove_hw_breakpoint(addr,
+                       (int) length, *bpt_type);
+
+       if (error == 0)
+               strcpy(remcom_out_buffer, "OK");
+       else
+               error_packet(remcom_out_buffer, error);
+}
+
+/* Handle the 'C' signal / exception passing packets */
+static int gdb_cmd_exception_pass(struct kgdb_state *ks)
+{
+       /* C09 == pass exception
+        * C15 == detach kgdb, pass exception
+        */
+       if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
+
+               ks->pass_exception = 1;
+               remcom_in_buffer[0] = 'c';
+
+       } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
+
+               ks->pass_exception = 1;
+               remcom_in_buffer[0] = 'D';
+               remove_all_break();
+               kgdb_connected = 0;
+               return 1;
+
+       } else {
+               error_packet(remcom_out_buffer, -EINVAL);
+               return 0;
+       }
+
+       /* Indicate fall through */
+       return -1;
+}
+
+/*
+ * This function performs all gdbserial command procesing
+ */
+static int gdb_serial_stub(struct kgdb_state *ks)
+{
+       int error = 0;
+       int tmp;
+
+       /* Clear the out buffer. */
+       memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
+
+       if (kgdb_connected) {
+               unsigned char thref[8];
+               char *ptr;
+
+               /* Reply to host that an exception has occurred */
+               ptr = remcom_out_buffer;
+               *ptr++ = 'T';
+               ptr = pack_hex_byte(ptr, ks->signo);
+               ptr += strlen(strcpy(ptr, "thread:"));
+               int_to_threadref(thref, shadow_pid(current->pid));
+               ptr = pack_threadid(ptr, thref);
+               *ptr++ = ';';
+               put_packet(remcom_out_buffer);
+       }
+
+       kgdb_usethread = kgdb_info[ks->cpu].task;
+       ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
+       ks->pass_exception = 0;
+
+       while (1) {
+               error = 0;
+
+               /* Clear the out buffer. */
+               memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
+
+               get_packet(remcom_in_buffer);
+
+               switch (remcom_in_buffer[0]) {
+               case '?': /* gdbserial status */
+                       gdb_cmd_status(ks);
+                       break;
+               case 'g': /* return the value of the CPU registers */
+                       gdb_cmd_getregs(ks);
+                       break;
+               case 'G': /* set the value of the CPU registers - return OK */
+                       gdb_cmd_setregs(ks);
+                       break;
+               case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
+                       gdb_cmd_memread(ks);
+                       break;
+               case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
+                       gdb_cmd_memwrite(ks);
+                       break;
+               case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
+                       gdb_cmd_binwrite(ks);
+                       break;
+                       /* kill or detach. KGDB should treat this like a
+                        * continue.
+                        */
+               case 'D': /* Debugger detach */
+               case 'k': /* Debugger detach via kill */
+                       gdb_cmd_detachkill(ks);
+                       goto default_handle;
+               case 'R': /* Reboot */
+                       if (gdb_cmd_reboot(ks))
+                               goto default_handle;
+                       break;
+               case 'q': /* query command */
+                       gdb_cmd_query(ks);
+                       break;
+               case 'H': /* task related */
+                       gdb_cmd_task(ks);
+                       break;
+               case 'T': /* Query thread status */
+                       gdb_cmd_thread(ks);
+                       break;
+               case 'z': /* Break point remove */
+               case 'Z': /* Break point set */
+                       gdb_cmd_break(ks);
+                       break;
+               case 'C': /* Exception passing */
+                       tmp = gdb_cmd_exception_pass(ks);
+                       if (tmp > 0)
+                               goto default_handle;
+                       if (tmp == 0)
+                               break;
+                       /* Fall through on tmp < 0 */
+               case 'c': /* Continue packet */
+               case 's': /* Single step packet */
+                       if (kgdb_contthread && kgdb_contthread != current) {
+                               /* Can't switch threads in kgdb */
+                               error_packet(remcom_out_buffer, -EINVAL);
+                               break;
+                       }
+                       kgdb_activate_sw_breakpoints();
+                       /* Fall through to default processing */
+               default:
+default_handle:
+                       error = kgdb_arch_handle_exception(ks->ex_vector,
+                                               ks->signo,
+                                               ks->err_code,
+                                               remcom_in_buffer,
+                                               remcom_out_buffer,
+                                               ks->linux_regs);
+                       /*
+                        * Leave cmd processing on error, detach,
+                        * kill, continue, or single step.
+                        */
+                       if (error >= 0 || remcom_in_buffer[0] == 'D' ||
+                           remcom_in_buffer[0] == 'k') {
+                               error = 0;
+                               goto kgdb_exit;
+                       }
+
+               }
+
+               /* reply to the request */
+               put_packet(remcom_out_buffer);
+       }
+
+kgdb_exit:
+       if (ks->pass_exception)
+               error = 1;
+       return error;
+}
+
+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);
+       kgdb_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 (kgdb_remove_sw_break(addr) == 0) {
+               exception_level = 0;
+               kgdb_skipexception(ks->ex_vector, ks->linux_regs);
+               kgdb_activate_sw_breakpoints();
+               printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed\n");
+               WARN_ON_ONCE(1);
+
+               return 1;
+       }
+       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");
+       dump_stack();
+       panic("Recursive entry to debugger");
+
+       return 1;
+}
+
+/*
+ * 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;
+       unsigned long flags;
+       int error = 0;
+       int i, cpu;
+
+       ks->cpu                 = raw_smp_processor_id();
+       ks->ex_vector           = evector;
+       ks->signo               = signo;
+       ks->ex_vector           = evector;
+       ks->err_code            = ecode;
+       ks->kgdb_usethreadid    = 0;
+       ks->linux_regs          = regs;
+
+       if (kgdb_reenter_check(ks))
+               return 0; /* Ouch, double exception ! */
+
+acquirelock:
+       /*
+        * Interrupts will be restored by the 'trap return' code, except when
+        * single stepping.
+        */
+       local_irq_save(flags);
+
+       cpu = raw_smp_processor_id();
+
+       /*
+        * Acquire the kgdb_active lock:
+        */
+       while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
+               cpu_relax();
+
+       /*
+        * Do not start the debugger connection on this CPU if the last
+        * instance of the exception handler wanted to come into the
+        * debugger on a different CPU via a single step
+        */
+       if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
+           atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
+
+               atomic_set(&kgdb_active, -1);
+               local_irq_restore(flags);
+
+               goto acquirelock;
+       }
+
+       if (!kgdb_io_ready(1)) {
+               error = 1;
+               goto kgdb_restore; /* No I/O connection, so 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 (kgdb_io_ops->pre_exception)
+               kgdb_io_ops->pre_exception();
+
+       kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
+       kgdb_info[ks->cpu].task = current;
+
+       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 || !kgdb_contthread) {
+               for (i = 0; i < NR_CPUS; i++)
+                       atomic_set(&passive_cpu_wait[i], 1);
+       }
+
+#ifdef CONFIG_SMP
+       /* Signal the other CPUs to enter kgdb_wait() */
+       if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup)
+               kgdb_roundup_cpus(flags);
+#endif
+
+       /*
+        * spin_lock code is good enough as a barrier so we don't
+        * need one here:
+        */
+       atomic_set(&cpu_in_kgdb[ks->cpu], 1);
+
+       /*
+        * Wait for the other CPUs to be notified and be waiting for us:
+        */
+       for_each_online_cpu(i) {
+               while (!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
+        */
+       kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
+       kgdb_deactivate_sw_breakpoints();
+       kgdb_single_step = 0;
+       kgdb_contthread = NULL;
+       exception_level = 0;
+
+       /* Talk to debugger with gdbserial protocol */
+       error = gdb_serial_stub(ks);
+
+       /* Call the I/O driver's post_exception routine */
+       if (kgdb_io_ops->post_exception)
+               kgdb_io_ops->post_exception();
+
+       kgdb_info[ks->cpu].debuggerinfo = NULL;
+       kgdb_info[ks->cpu].task = NULL;
+       atomic_set(&cpu_in_kgdb[ks->cpu], 0);
+
+       if (!kgdb_single_step || !kgdb_contthread) {
+               for (i = NR_CPUS-1; i >= 0; i--)
+                       atomic_set(&passive_cpu_wait[i], 0);
+               /*
+                * Wait till all the CPUs have quit
+                * from the debugger.
+                */
+               for_each_online_cpu(i) {
+                       while (atomic_read(&cpu_in_kgdb[i]))
+                               cpu_relax();
+               }
+       }
+
+kgdb_restore:
+       /* Free kgdb_active */
+       atomic_set(&kgdb_active, -1);
+       local_irq_restore(flags);
+
+       return error;
+}
+
+int kgdb_nmicallback(int cpu, void *regs)
+{
+#ifdef CONFIG_SMP
+       if (!atomic_read(&cpu_in_kgdb[cpu]) &&
+                       atomic_read(&kgdb_active) != cpu) {
+               kgdb_wait((struct pt_regs *)regs);
+               return 0;
+       }
+#endif
+       return 1;
+}
+
+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)
+               return;
+
+       local_irq_save(flags);
+       kgdb_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_gdb(int key, struct tty_struct *tty)
+{
+       if (!kgdb_io_ops) {
+               printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
+               return;
+       }
+       if (!kgdb_connected)
+               printk(KERN_CRIT "Entering KGDB\n");
+
+       kgdb_breakpoint();
+}
+
+static struct sysrq_key_op sysrq_gdb_op = {
+       .handler        = sysrq_handle_gdb,
+       .help_msg       = "Gdb",
+       .action_msg     = "GDB",
+};
+#endif
+
+static void kgdb_register_callbacks(void)
+{
+       if (!kgdb_io_module_registered) {
+               kgdb_io_module_registered = 1;
+               kgdb_arch_init();
+#ifdef CONFIG_MAGIC_SYSRQ
+               register_sysrq_key('g', &sysrq_gdb_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;
+               kgdb_arch_exit();
+#ifdef CONFIG_MAGIC_SYSRQ
+               unregister_sysrq_key('g', &sysrq_gdb_op);
+#endif
+               if (kgdb_con_registered) {
+                       unregister_console(&kgdbcons);
+                       kgdb_con_registered = 0;
+               }
+       }
+}
+
+static void kgdb_initial_breakpoint(void)
+{
+       kgdb_break_asap = 0;
+
+       printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
+       kgdb_breakpoint();
+}
+
+/**
+ *     kkgdb_register_io_module - register KGDB IO module
+ *     @new_kgdb_io_ops: the io ops vector
+ *
+ *     Register it with the KGDB core.
+ */
+int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
+{
+       int err;
+
+       spin_lock(&kgdb_registration_lock);
+
+       if (kgdb_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_kgdb_io_ops->init) {
+               err = new_kgdb_io_ops->init();
+               if (err) {
+                       spin_unlock(&kgdb_registration_lock);
+                       return err;
+               }
+       }
+
+       kgdb_io_ops = new_kgdb_io_ops;
+
+       spin_unlock(&kgdb_registration_lock);
+
+       printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
+              new_kgdb_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_kgdb_io_ops: the io ops vector
+ *
+ *     Unregister it with the KGDB core.
+ */
+void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_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(kgdb_io_ops != old_kgdb_io_ops);
+       kgdb_io_ops = NULL;
+
+       spin_unlock(&kgdb_registration_lock);
+
+       printk(KERN_INFO
+               "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
+               old_kgdb_io_ops->name);
+}
+EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
+
+/**
+ * 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_set(&kgdb_setting_breakpoint, 1);
+       wmb(); /* Sync point before breakpoint */
+       arch_kgdb_breakpoint();
+       wmb(); /* Sync point after breakpoint */
+       atomic_set(&kgdb_setting_breakpoint, 0);
+}
+EXPORT_SYMBOL_GPL(kgdb_breakpoint);
+
+static int __init opt_kgdb_wait(char *str)
+{
+       kgdb_break_asap = 1;
+
+       if (kgdb_io_module_registered)
+               kgdb_initial_breakpoint();
+
+       return 0;
+}
+
+early_param("kgdbwait", opt_kgdb_wait);
index 0796c1a090c029db5d038020ae52684ee423c2e3..e601d0e7ac5d16d549dcfde9be7d18613d864517 100644 (file)
@@ -622,3 +622,5 @@ config PROVIDE_OHCI1394_DMA_INIT
          See Documentation/debugging-via-ohci1394.txt for more information.
 
 source "samples/Kconfig"
+
+source "lib/Kconfig.kgdb"
diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
new file mode 100644 (file)
index 0000000..9631ba3
--- /dev/null
@@ -0,0 +1,27 @@
+
+menuconfig KGDB
+       bool "KGDB: kernel debugging with remote gdb"
+       select FRAME_POINTER
+       depends on HAVE_ARCH_KGDB
+       depends on DEBUG_KERNEL && EXPERIMENTAL
+       help
+         If you say Y here, it will be possible to remotely debug the
+         kernel using gdb.  Documentation of kernel debugger is available
+         at http://kgdb.sourceforge.net as well as in DocBook form
+         in Documentation/DocBook/.  If unsure, say N.
+
+config HAVE_ARCH_KGDB_SHADOW_INFO
+       bool
+
+config HAVE_ARCH_KGDB
+       bool
+
+config KGDB_SERIAL_CONSOLE
+       tristate "KGDB: use kgdb over the serial console"
+       depends on KGDB
+       select CONSOLE_POLL
+       select MAGIC_SYSRQ
+       default y
+       help
+         Share a serial console with kgdb. Sysrq-g must be used
+         to break in initially.