kgdb for mainline kernel: core-lite [patch 1/3]

Amit S. Kale
2004-03-08T09:44:50Z

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Hi Andrew,

Here is kgdb for mainline kernel in three patches. This is a lite
version of kgdb available from kgdb.sourceforge.net. I believe that all of us
agree on this lite kgdb.

It supports basic debugging of i386 architecture and debugging over a serial
line. Contents of these patches are as follows:

[1] core-lite.patch: architecture indepndent code
[2] i386-lite.patch: i386 architecture dependent code
[3] 8250.patch: support for generic serial driver

Thanks.
-Amit

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Index: linux-2.6.4-rc2-bk3-kgdb/Makefile
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/Makefile 2004-03-08 14:30:27.382791896 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/Makefile 2004-03-08 14:31:42.813324712 +0530
@@ -440,6 +440,8 @@

ifndef CONFIG_FRAME_POINTER
CFLAGS += -fomit-frame-pointer
+else
+CFLAGS += -fno-omit-frame-pointer
endif

ifdef CONFIG_DEBUG_INFO
Index: linux-2.6.4-rc2-bk3-kgdb/include/linux/debugger.h
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/include/linux/debugger.h 2003-01-30 15:54:37.000000000 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/include/linux/debugger.h 2004-03-08 14:31:42.814324560 +0530
@@ -0,0 +1,70 @@
+#ifndef _DEBUGGER_H_
+#define _DEBUGGER_H_
+
+/*
+ * Copyright (C) 2003-2004 Amit S. Kale
+ *
+ * Definition switchout for debuggers
+ */
+
+/*
+ * KGDB
+ */
+#ifdef CONFIG_KGDB
+
+typedef int gdb_debug_hook(int exVector, int signo, int err_code,
+ struct pt_regs *regs);
+extern gdb_debug_hook *linux_debug_hook;
+#define CHK_DEBUGGER(trapnr,signr,error_code,regs,after) \
+ { \
+ if (linux_debug_hook != (gdb_debug_hook *) NULL && !user_mode(regs)) \
+ { \
+ (*linux_debug_hook)(trapnr, signr, error_code, regs) ; \
+ after; \
+ } \
+ }
+
+void kgdb_nmihook(int cpu, void *regs);
+static inline void debugger_nmihook(int cpu, void *regs)
+{
+ kgdb_nmihook(cpu, regs);
+}
+
+void kgdb_entry(void);
+static inline void debugger_entry(void)
+{
+ kgdb_entry();
+}
+
+extern int debugger_step;
+extern atomic_t debugger_active;
+
+/*
+ * No debugger in the kernel
+ */
+#else
+
+#define CHK_DEBUGGER(trapnr,signr,error_code,regs,after) \
+{ \
+ if (0) \
+ after; \
+}
+
+static inline void debugger_nmihook(int cpu, void *regs)
+{
+ /* Do nothing */
+}
+
+static inline void debugger_entry(void)
+{
+ /* Do nothing */
+}
+
+#define debugger_step 0
+static const atomic_t debugger_active = { 0 };
+
+#define debugger_memerr_expected 0
+
+#endif
+
+#endif /* _DEBUGGER_H_ */
Index: linux-2.6.4-rc2-bk3-kgdb/include/linux/kgdb.h
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/include/linux/kgdb.h 2003-01-30 15:54:37.000000000 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/include/linux/kgdb.h 2004-03-08 14:31:42.814324560 +0530
@@ -0,0 +1,128 @@
+#ifndef _KGDB_H_
+#define _KGDB_H_
+
+/*
+ * Copyright (C) 2001-2004 Amit S. Kale
+ */
+
+#include <linux/ptrace.h>
+#include <asm/kgdb.h>
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+#include <linux/debugger.h>
+
+/*
+ * This file should not include ANY others. This makes it usable
+ * most anywhere without the fear of include order or inclusion.
+ * TODO: Make it so!
+ *
+ * This file may be included all the time. It is only active if
+ * CONFIG_KGDB is defined, otherwise it stubs out all the macros
+ * and entry points.
+ */
+
+#if defined(CONFIG_KGDB) && !defined(__ASSEMBLY__)
+/* To enter the debugger explicitly. */
+extern void breakpoint(void);
+extern void kgdb_schedule_breakpoint(void);
+extern void kgdb_process_breakpoint(void);
+extern volatile int kgdb_connected;
+
+#ifndef KGDB_MAX_NO_CPUS
+#if CONFIG_NR_CPUS > 8
+#error KGDB can handle max 8 CPUs
+#endif
+#define KGDB_MAX_NO_CPUS 8
+#endif
+
+extern atomic_t kgdb_setting_breakpoint;
+
+extern struct task_struct *kgdb_usethread, *kgdb_contthread;
+
+enum kgdb_bptype {
+ bp_breakpoint = '0',
+ bp_hardware_breakpoint,
+ bp_write_watchpoint,
+ bp_read_watchpoint,
+ bp_access_watchpoint
+};
+
+enum kgdb_bpstate {
+ bp_disabled,
+ bp_enabled
+};
+
+struct kgdb_bkpt {
+ unsigned long bpt_addr;
+ unsigned char saved_instr[BREAK_INSTR_SIZE];
+ enum kgdb_bptype type;
+ enum kgdb_bpstate state;
+};
+
+#ifndef BREAK_INSTR_SIZE
+#error BREAK_INSTR_SIZE needed by kgdb
+#endif
+
+#ifndef MAX_BREAKPOINTS
+#define MAX_BREAKPOINTS 16
+#endif
+
+#define KGDB_HW_BREAKPOINT 1
+
+/* These are functions that the arch specific code can, and in some cases
+ * must, provide. */
+extern int kgdb_arch_init(void);
+extern void regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs);
+extern void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs,
+ struct task_struct *p);
+extern void gdb_regs_to_regs(unsigned long *gdb_regs, struct pt_regs *regs);
+extern void kgdb_printexceptioninfo(int exceptionNo, int errorcode,
+ char *buffer);
+extern void kgdb_disable_hw_debug(struct pt_regs *regs);
+extern void kgdb_post_master_code(struct pt_regs *regs, int eVector,
+ int err_code);
+extern int kgdb_arch_handle_exception(int vector, int signo, int err_code,
+ char *InBuffer, char *outBuffer,
+ struct pt_regs *regs);
+extern int kgdb_arch_set_break(unsigned long addr, int type);
+extern int kgdb_arch_remove_break(unsigned long addr, int type);
+extern void kgdb_correct_hw_break(void);
+extern void kgdb_shadowinfo(struct pt_regs *regs, char *buffer,
+ unsigned threadid);
+extern struct task_struct *kgdb_get_shadow_thread(struct pt_regs *regs,
+ int threadid);
+extern struct pt_regs *kgdb_shadow_regs(struct pt_regs *regs, int threadid);
+
+struct kgdb_arch {
+ unsigned char gdb_bpt_instr[BREAK_INSTR_SIZE];
+ unsigned long flags;
+ unsigned shadowth;
+};
+
+/* Thread reference */
+typedef unsigned char threadref[8];
+
+struct kgdb_serial {
+ int (*read_char) (void);
+ void (*write_char) (int);
+ void (*flush) (void);
+ int (*hook) (void);
+};
+
+extern struct kgdb_serial *kgdb_serial;
+extern struct kgdb_arch arch_kgdb_ops;
+extern int kgdb_initialized;
+
+struct uart_port;
+
+extern void kgdb8250_add_port(int i, struct uart_port *serial_req);
+
+int kgdb_hex2long(char **ptr, long *longValue);
+char *kgdb_mem2hex(char *mem, char *buf, int count);
+char *kgdb_hex2mem(char *buf, char *mem, int count);
+int kgdb_get_mem(char *addr, unsigned char *buf, int count);
+
+#else
+#define kgdb_process_breakpoint() do {} while(0)
+#endif /* KGDB && !__ASSEMBLY__ */
+#endif /* _KGDB_H_ */
Index: linux-2.6.4-rc2-bk3-kgdb/init/main.c
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/init/main.c 2004-03-08 14:30:27.283806944 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/init/main.c 2004-03-08 14:31:42.815324408 +0530
@@ -39,6 +39,7 @@
#include <linux/writeback.h>
#include <linux/cpu.h>
#include <linux/efi.h>
+#include <linux/debugger.h>

#include <asm/io.h>
#include <asm/bugs.h>
@@ -581,6 +582,7 @@

smp_init();
do_basic_setup();
+ debugger_entry();

prepare_namespace();

Index: linux-2.6.4-rc2-bk3-kgdb/kernel/Makefile
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/kernel/Makefile 2004-03-08 14:30:26.920862120 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/kernel/Makefile 2004-03-08 14:31:42.815324408 +0530
@@ -19,6 +19,7 @@
obj-$(CONFIG_COMPAT) += compat.o
obj-$(CONFIG_IKCONFIG) += configs.o
obj-$(CONFIG_IKCONFIG_PROC) += configs.o
+obj-$(CONFIG_KGDB) += kgdb.o

ifneq ($(CONFIG_IA64),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
Index: linux-2.6.4-rc2-bk3-kgdb/kernel/kgdb.c
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/kernel/kgdb.c 2003-01-30 15:54:37.000000000 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/kernel/kgdb.c 2004-03-08 14:31:42.818323952 +0530
@@ -0,0 +1,1275 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+/*
+ * Copyright (C) 2000-2001 VERITAS Software Corporation.
+ * Copyright (C) 2002-2004 Timesys Corporation
+ * Copyright (C) 2003-2004 Amit S. Kale
+ * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
+ * Copyright (C) 2004 Tom Rini <trini@kernel.crashing.org>
+ *
+ * Restructured KGDB for 2.6 kernels.
+ * thread support, support for multiple processors,support for ia-32(x86)
+ * hardware debugging, Console support, handling nmi watchdog
+ * - Amit S. Kale ( amitkale@emsyssoft.com )
+ *
+ * Several enhancements by George Anzinger <george@mvista.com>
+ * Generic KGDB Support
+ * Implemented by Anurekh Saxena (anurekh.saxena@timesys.com)
+ *
+ * Contributor: Lake Stevens Instrument Division
+ * Written by: Glenn Engel
+ *
+ * Modified for 386 by Jim Kingdon, Cygnus Support.
+ * Origianl kgdb, compatibility with 2.1.xx kernel by David Grothe <dave@gcom.com>
+ * Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
+ */
+
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+#include <linux/mm.h>
+#include <asm/system.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+#include <linux/kgdb.h>
+#include <asm/atomic.h>
+#include <linux/notifier.h>
+#include <linux/module.h>
+#include <asm/cacheflush.h>
+#ifdef CONFIG_KGDB_CONSOLE
+#include <linux/console.h>
+#endif
+#include <linux/init.h>
+
+extern int pid_max;
+
+#define BUF_THREAD_ID_SIZE 16
+
+/*
+ * kgdb_initialized indicates that kgdb is setup and is all ready to serve
+ * breakpoints and other kernel exceptions. kgdb_connected indicates that kgdb
+ * has connected to kgdb.
+ */
+int kgdb_initialized = 0;
+volatile int kgdb_connected;
+
+/* If non-zero, wait for a gdb connection when kgdb_entry is called */
+int kgdb_enter = 0;
+
+/* Set to 1 to make kgdb allow access to user addresses. Can be set from gdb
+ * also at runtime. */
+int kgdb_useraccess = 0;
+
+struct kgdb_serial *kgdb_serial;
+
+/*
+ * Holds information about breakpoints in a kernel. These breakpoints are
+ * added and removed by gdb.
+ */
+struct kgdb_bkpt kgdb_break[MAX_BREAKPOINTS];
+
+struct kgdb_arch *kgdb_ops = &arch_kgdb_ops;
+
+static const char hexchars[] = "0123456789abcdef";
+
+static spinlock_t slavecpulocks[KGDB_MAX_NO_CPUS];
+static volatile int procindebug[KGDB_MAX_NO_CPUS];
+atomic_t kgdb_setting_breakpoint;
+struct task_struct *kgdb_usethread, *kgdb_contthread;
+
+int debugger_step;
+atomic_t debugger_active;
+
+/* This will point to kgdb_handle_exception by default.
+ * The architecture code can override this in its init function
+ */
+gdb_debug_hook *linux_debug_hook;
+
+static char remcom_in_buffer[BUFMAX];
+static char remcom_out_buffer[BUFMAX];
+
+/*
+ * The following are the stub functions for code which is arch specific
+ * and can be omitted on some arches
+ * This function will handle the initalization of any architecture specific
+ * hooks. If there is a suitable early output driver, kgdb_serial
+ * can be pointed at it now.
+ */
+int __attribute__ ((weak))
+ kgdb_arch_init(void)
+{
+ return 0;
+}
+
+void __attribute__ ((weak))
+ regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+}
+
+void __attribute__ ((weak))
+ sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
+{
+}
+
+void __attribute__ ((weak))
+ gdb_regs_to_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+}
+
+void __attribute__ ((weak))
+ kgdb_printexceptioninfo(int exceptionNo, int errorcode, char *buffer)
+{
+}
+
+void __attribute__ ((weak))
+ kgdb_disable_hw_debug(struct pt_regs *regs)
+{
+}
+
+void __attribute__ ((weak))
+ kgdb_post_master_code(struct pt_regs *regs, int eVector, int err_code)
+{
+}
+
+/*
+ * Handle any additional commands. This must handle the 'c' and 's'
+ * command packets.
+ * Return -1 to loop over other commands, and 0 to exit from KGDB
+ */
+int __attribute__ ((weak))
+ kgdb_arch_handle_exception(int vector, int signo, int err_code, char *InBuffer,
+ char *outBuffer, struct pt_regs *regs)
+{
+ return 0;
+}
+
+int __attribute__ ((weak))
+ kgdb_arch_set_break(unsigned long addr, int type)
+{
+ return 0;
+}
+
+int __attribute__ ((weak))
+ kgdb_arch_remove_break(unsigned long addr, int type)
+{
+ return 0;
+}
+
+void __attribute__ ((weak))
+ kgdb_correct_hw_break(void)
+{
+}
+
+void __attribute__ ((weak))
+ kgdb_shadowinfo(struct pt_regs *regs, char *buffer, unsigned threadid)
+{
+}
+
+struct task_struct __attribute__ ((weak))
+ * kgdb_get_shadow_thread(struct pt_regs *regs, int threadid)
+{
+ return NULL;
+}
+
+struct pt_regs __attribute__ ((weak))
+ * kgdb_shadow_regs(struct pt_regs *regs, int threadid)
+{
+ return NULL;
+}
+
+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 $ #<checksum> */
+static void get_packet(char *buffer)
+{
+ unsigned char checksum;
+ unsigned char xmitcsum;
+ int i;
+ int count;
+ char ch;
+
+ do {
+ /* wait around for the start character, ignore all other
+ * characters */
+ while ((ch = (kgdb_serial->read_char() & 0x7f)) != '$')
+ ; /* Spin. */
+ 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_serial->read_char() & 0x7f;
+ if (ch == '#')
+ break;
+ checksum = checksum + ch;
+ buffer[count] = ch;
+ count = count + 1;
+ }
+ buffer[count] = 0;
+
+ if (ch == '#') {
+ xmitcsum = hex(kgdb_serial->read_char() & 0x7f) << 4;
+ xmitcsum += hex(kgdb_serial->read_char() & 0x7f);
+
+ if (checksum != xmitcsum)
+ kgdb_serial->write_char('-'); /* failed checksum */
+ else
+ kgdb_serial->write_char('+'); /* successful transfer */
+ if (kgdb_serial->flush)
+ kgdb_serial->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;
+
+ /* $<packet info>#<checksum>. */
+ while (1) {
+ kgdb_serial->write_char('$');
+ checksum = 0;
+ count = 0;
+
+ while ((ch = buffer[count])) {
+ kgdb_serial->write_char(ch);
+ checksum += ch;
+ count++;
+ }
+
+ kgdb_serial->write_char('#');
+ kgdb_serial->write_char(hexchars[checksum >> 4]);
+ kgdb_serial->write_char(hexchars[checksum % 16]);
+ if (kgdb_serial->flush)
+ kgdb_serial->flush();
+
+ /* Now see what we get in reply. */
+ ch = kgdb_serial->read_char();
+
+ if (ch == 3)
+ ch = kgdb_serial->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_serial->write_char('-');
+ if (kgdb_serial->flush)
+ kgdb_serial->flush();
+ return;
+ }
+ }
+}
+
+static int get_char(char *addr, unsigned char *data)
+{
+ mm_segment_t fs;
+ int ret = 0;
+
+ if (!kgdb_useraccess && (unsigned long)addr < TASK_SIZE) {
+ return -EINVAL;
+ }
+ wmb();
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+
+ if (get_user(*data, addr) != 0) {
+ ret = -EFAULT;
+ }
+
+ set_fs(fs);
+ return ret;
+}
+
+static int set_char(char *addr, int data)
+{
+ mm_segment_t fs;
+ int ret = 0;
+
+ if (!kgdb_useraccess && (unsigned long)addr < TASK_SIZE) {
+ return -EINVAL;
+ }
+ wmb();
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+
+ if (put_user(data, addr) != 0) {
+ ret = -EFAULT;
+ }
+
+ set_fs(fs);
+ return ret;
+}
+
+/*
+ * 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.
+ */
+char *kgdb_mem2hex(char *mem, char *buf, int count)
+{
+ int i;
+ unsigned char ch;
+ int error;
+
+ for (i = 0; i < count; i++) {
+
+ if ((error = get_char(mem++, &ch)) < 0)
+ return ERR_PTR(error);
+
+ *buf++ = hexchars[ch >> 4];
+ *buf++ = hexchars[ch % 16];
+ }
+ *buf = 0;
+ return (buf);
+}
+
+/*
+ * 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.
+ */
+char *kgdb_hex2mem(char *buf, char *mem, int count)
+{
+ int i;
+ unsigned char ch;
+ int error;
+
+ for (i = 0; i < count; i++) {
+ ch = hex(*buf++) << 4;
+ ch = ch + hex(*buf++);
+ if ((error = set_char(mem++, ch)) < 0)
+ return ERR_PTR(error);
+ }
+ return (mem);
+}
+
+/*
+ * While we find nice hex chars, build a longValue.
+ * Return number of chars processed.
+ */
+int kgdb_hex2long(char **ptr, long *longValue)
+{
+ int numChars = 0;
+ int hexValue;
+
+ *longValue = 0;
+
+ while (**ptr) {
+ hexValue = hex(**ptr);
+ if (hexValue >= 0) {
+ *longValue = (*longValue << 4) | hexValue;
+ numChars++;
+ } else
+ break;
+
+ (*ptr)++;
+ }
+
+ return (numChars);
+}
+
+static inline char *pack_hex_byte(char *pkt, int byte)
+{
+ *pkt++ = hexchars[(byte >> 4) & 0xf];
+ *pkt++ = hexchars[(byte & 0xf)];
+ return pkt;
+}
+
+static inline 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';
+}
+
+static char *pack_threadid(char *pkt, threadref * id)
+{
+ char *limit;
+ unsigned char *altid;
+
+ altid = (unsigned char *)id;
+ limit = pkt + BUF_THREAD_ID_SIZE;
+ while (pkt < limit)
+ pkt = pack_hex_byte(pkt, *altid++);
+
+ return pkt;
+}
+
+void int_to_threadref(threadref * id, int value)
+{
+ unsigned char *scan;
+
+ scan = (unsigned char *)id;
+ {
+ int i = 4;
+ 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)
+{
+ int i;
+ struct list_head *l;
+ struct task_struct *p;
+ struct pid *pid;
+
+ if (tid >= pid_max + num_online_cpus() + kgdb_ops->shadowth) {
+ return NULL;
+ }
+ if (tid >= pid_max + num_online_cpus()) {
+ return kgdb_get_shadow_thread(regs, tid - pid_max -
+ num_online_cpus());
+ }
+ if (tid >= pid_max) {
+ i = 0;
+ for_each_task_pid(0, PIDTYPE_PID, p, l, pid) {
+ if (tid == pid_max + i) {
+ return p;
+ }
+ i++;
+ }
+ return NULL;
+ }
+ if (!tid) {
+ return NULL;
+ }
+ return find_task_by_pid(tid);
+}
+
+#ifdef CONFIG_SMP
+void kgdb_wait(struct pt_regs *regs)
+{
+ unsigned long flags;
+ int processor;
+
+ local_irq_save(flags);
+ processor = smp_processor_id();
+ procindebug[processor] = 1;
+ current->thread.debuggerinfo = regs;
+
+ /* Wait till master processor goes completely into the debugger.
+ * FIXME: this looks racy */
+ while (!procindebug[atomic_read(&debugger_active) - 1]) {
+ int i = 10; /* an arbitrary number */
+
+ while (--i)
+ asm volatile ("nop":::"memory");
+ barrier();
+ }
+
+ /* Wait till master processor is done with debugging */
+ spin_lock(slavecpulocks + processor);
+
+ /* This has been taken from x86 kgdb implementation and
+ * will be needed by architectures that have SMP support
+ */
+ kgdb_correct_hw_break();
+
+ /* Signal the master processor that we are done */
+ procindebug[processor] = 0;
+ spin_unlock(slavecpulocks + processor);
+ local_irq_restore(flags);
+}
+#endif
+
+int kgdb_get_mem(char *addr, unsigned char *buf, int count)
+{
+ int error;
+ while (count) {
+ if ((error = get_char(addr++, buf)) < 0)
+ return error;
+ buf++;
+ count--;
+ }
+ return 0;
+}
+
+static int set_mem(char *addr, unsigned char *buf, int count)
+{
+ int error;
+ while (count) {
+ if ((error = set_char(addr++, *buf++)) < 0)
+ return error;
+ count--;
+ }
+ return 0;
+}
+
+static int set_break(unsigned long addr)
+{
+ int i, breakno = -1;
+ int error;
+
+ for (i = 0; i < MAX_BREAKPOINTS; i++) {
+ if ((kgdb_break[i].state == bp_enabled) &&
+ (kgdb_break[i].bpt_addr == addr)) {
+ return -EEXIST;
+ }
+
+ if (kgdb_break[i].state == bp_disabled) {
+ if ((breakno == -1) || (kgdb_break[i].bpt_addr == addr))
+ breakno = i;
+ }
+ }
+ if (breakno == -1)
+ return -E2BIG;
+
+ if ((error = kgdb_get_mem((char *)addr, kgdb_break[breakno].saved_instr,
+ BREAK_INSTR_SIZE)) < 0)
+ return error;
+
+ if ((error = set_mem((char *)addr, kgdb_ops->gdb_bpt_instr,
+ BREAK_INSTR_SIZE)) < 0)
+ return error;
+ flush_cache_range(current->mm, addr, addr + BREAK_INSTR_SIZE);
+ flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
+
+ kgdb_break[breakno].state = bp_enabled;
+ kgdb_break[breakno].type = bp_breakpoint;
+ kgdb_break[breakno].bpt_addr = addr;
+
+ return 0;
+}
+
+static int remove_break(unsigned long addr)
+{
+ int i;
+ int error;
+
+ for (i = 0; i < MAX_BREAKPOINTS; i++) {
+ if ((kgdb_break[i].state == bp_enabled) &&
+ (kgdb_break[i].bpt_addr == addr)) {
+ if ((error =
+ set_mem((char *)addr, kgdb_break[i].saved_instr,
+ BREAK_INSTR_SIZE)) < 0)
+ return error;
+ flush_cache_range(current->mm, addr,
+ addr + BREAK_INSTR_SIZE);
+ flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
+ kgdb_break[i].state = bp_disabled;
+ return 0;
+ }
+ }
+ return -ENOENT;
+}
+
+int remove_all_break(void)
+{
+ int i;
+ int error;
+ for (i = 0; i < MAX_BREAKPOINTS; i++) {
+ if (kgdb_break[i].state == bp_enabled) {
+ unsigned long addr = kgdb_break[i].bpt_addr;
+ if ((error =
+ set_mem((char *)addr, kgdb_break[i].saved_instr,
+ BREAK_INSTR_SIZE)) < 0)
+ return error;
+ flush_cache_range(current->mm, addr,
+ addr + BREAK_INSTR_SIZE);
+ flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
+ }
+ kgdb_break[i].state = bp_disabled;
+ }
+ return 0;
+}
+
+static inline int shadow_pid(int realpid)
+{
+ if (realpid) {
+ return realpid;
+ }
+ return pid_max + smp_processor_id();
+}
+
+/*
+ * This function does all command procesing for interfacing to gdb.
+ *
+ * Locking hierarchy:
+ * interface locks, if any (begin_session)
+ * kgdb lock (debugger_active)
+ *
+ */
+int kgdb_handle_exception(int exVector, int signo, int err_code,
+ struct pt_regs *linux_regs)
+{
+ unsigned long length, addr;
+ char *ptr;
+ unsigned long flags;
+ unsigned long gdb_regs[NUMREGBYTES / sizeof(unsigned long)];
+ int i;
+ long threadid;
+ threadref thref;
+ struct task_struct *thread = NULL;
+ unsigned procid;
+ static char tmpstr[256];
+ int numshadowth = num_online_cpus() + kgdb_ops->shadowth;
+ long kgdb_usethreadid = 0;
+ int error = 0;
+ struct pt_regs *shadowregs;
+
+ /* Panic on recursive debugger calls. */
+ if (atomic_read(&debugger_active) == smp_processor_id() + 1) {
+ return 0;
+ }
+
+ /*
+ * Interrupts will be restored by the 'trap return' code, except when
+ * single stepping.
+ */
+ local_irq_save(flags);
+
+ /* Hold debugger_active */
+ procid = smp_processor_id();
+ while (cmpxchg(&atomic_read(&debugger_active), 0, (procid + 1)) != 0) {
+ int i = 25; /* an arbitrary number */
+
+ while (--i)
+ asm volatile ("nop":::"memory");
+ }
+
+ debugger_step = 0;
+
+ current->thread.debuggerinfo = linux_regs;
+
+ kgdb_disable_hw_debug(linux_regs);
+
+ for (i = 0; i < num_online_cpus(); i++) {
+ spin_lock(&slavecpulocks[i]);
+ }
+
+ /* spin_lock code is good enough as a barrier so we don't
+ * need one here */
+ procindebug[smp_processor_id()] = 1;
+
+ /* Clear the out buffer. */
+ memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
+
+ /* Master processor is completely in the debugger */
+ kgdb_post_master_code(linux_regs, exVector, err_code);
+
+ if (kgdb_connected) {
+ /* reply to host that an exception has occurred */
+ ptr = remcom_out_buffer;
+ *ptr++ = 'T';
+ *ptr++ = hexchars[(signo >> 4) % 16];
+ *ptr++ = hexchars[signo % 16];
+ 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 = current;
+ kgdb_usethreadid = shadow_pid(current->pid);
+
+ while (1) {
+ int bpt_type = 0;
+ 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 '?':
+ /* We know that this packet is only sent
+ * during initial connect. So to be safe,
+ * we clear out our breakpoints now incase
+ * GDB is reconnecting. */
+ remove_all_break();
+ remcom_out_buffer[0] = 'S';
+ remcom_out_buffer[1] = hexchars[signo >> 4];
+ remcom_out_buffer[2] = hexchars[signo % 16];
+ break;
+
+ case 'g': /* return the value of the CPU registers */
+ thread = kgdb_usethread;
+
+ if (!thread)
+ thread = current;
+
+ /* 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 (kgdb_usethreadid >= pid_max + num_online_cpus()) {
+ shadowregs = kgdb_shadow_regs(linux_regs,
+ kgdb_usethreadid -
+ pid_max -
+ num_online_cpus
+ ());
+ if (!shadowregs) {
+ error_packet(remcom_out_buffer,
+ -EINVAL);
+ break;
+ }
+ regs_to_gdb_regs(gdb_regs, shadowregs);
+ } else if (thread->thread.debuggerinfo) {
+ if ((error =
+ get_char(thread->thread.debuggerinfo,
+ (unsigned char *)gdb_regs)) < 0) {
+ error_packet(remcom_out_buffer, error);
+ break;
+ }
+ regs_to_gdb_regs(gdb_regs, (struct pt_regs *)
+ thread->thread.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);
+ break;
+
+ case 'G': /* set the value of the CPU registers - return OK */
+ 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_regs(gdb_regs, (struct pt_regs *)
+ current->thread.debuggerinfo);
+ strcpy(remcom_out_buffer, "OK");
+ }
+
+ break;
+
+ /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
+ case 'm':
+ ptr = &remcom_in_buffer[1];
+ if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
+ kgdb_hex2long(&ptr, &length) > 0) {
+ if (IS_ERR(ptr = kgdb_mem2hex((char *)addr,
+ remcom_out_buffer,
+ length)))
+ error_packet(remcom_out_buffer,
+ PTR_ERR(ptr));
+ } else
+ error_packet(remcom_out_buffer, -EINVAL);
+ break;
+
+ /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
+ case 'M':
+ ptr = &remcom_in_buffer[1];
+ if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ','
+ && kgdb_hex2long(&ptr, &length) > 0 &&
+ *(ptr++) == ':') {
+ if (IS_ERR(ptr = kgdb_hex2mem(ptr, (char *)addr,
+ length)))
+ error_packet(remcom_out_buffer,
+ PTR_ERR(ptr));
+ } else
+ error_packet(remcom_out_buffer, -EINVAL);
+ break;
+
+ /* kill or detach. KGDB should treat this like a
+ * continue.
+ */
+ case 'D':
+ if ((error = remove_all_break()) < 0) {
+ error_packet(remcom_out_buffer, error);
+ } else {
+ strcpy(remcom_out_buffer, "OK");
+ kgdb_connected = 0;
+ }
+ put_packet(remcom_out_buffer);
+ goto default_handle;
+
+ case 'k':
+ /* Don't care about error from remove_all_break */
+ remove_all_break();
+ kgdb_connected = 0;
+ goto default_handle;
+
+ /* query */
+ case 'q':
+ 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') {
+ threadid = 1;
+ }
+ remcom_out_buffer[0] = 'm';
+ ptr = remcom_out_buffer + 1;
+ for (i = 0; i < 32 && threadid < pid_max +
+ numshadowth; threadid++) {
+ thread = getthread(linux_regs,
+ threadid);
+ if (thread) {
+ int_to_threadref(&thref,
+ threadid);
+ pack_threadid(ptr, &thref);
+ ptr += 16;
+ *(ptr++) = ',';
+ i++;
+ }
+ }
+ *(--ptr) = '\0';
+ break;
+
+ case 'C':
+ /* Current thread id */
+ strcpy(remcom_out_buffer, "QC");
+
+ threadid = shadow_pid(current->pid);
+
+ int_to_threadref(&thref, threadid);
+ pack_threadid(remcom_out_buffer + 2, &thref);
+ break;
+
+ case 'E':
+ /* Print exception info */
+ kgdb_printexceptioninfo(exVector, err_code,
+ remcom_out_buffer);
+ break;
+ case 'T':
+ if (memcmp(remcom_in_buffer + 1,
+ "ThreadExtraInfo,", 16)) {
+ error_packet(remcom_out_buffer,
+ -EINVAL);
+ break;
+ }
+ threadid = 0;
+ ptr = remcom_in_buffer + 17;
+ kgdb_hex2long(&ptr, &threadid);
+ if (!getthread(linux_regs, threadid)) {
+ error_packet(remcom_out_buffer,
+ -EINVAL);
+ break;
+ }
+ if (threadid < pid_max) {
+ kgdb_mem2hex(getthread(linux_regs,
+ threadid)->comm,
+ remcom_out_buffer, 16);
+ } else if (threadid >= pid_max +
+ num_online_cpus()) {
+ kgdb_shadowinfo(linux_regs,
+ remcom_out_buffer,
+ threadid - pid_max -
+ num_online_cpus());
+ } else {
+ sprintf(tmpstr, "Shadow task %d"
+ " for pid 0",
+ (int)(threadid - pid_max));
+ kgdb_mem2hex(tmpstr, remcom_out_buffer,
+ strlen(tmpstr));
+ }
+ break;
+ }
+ break;
+
+ /* task related */
+ case 'H':
+ switch (remcom_in_buffer[1]) {
+ case 'g':
+ ptr = &remcom_in_buffer[2];
+ kgdb_hex2long(&ptr, &threadid);
+ thread = getthread(linux_regs, threadid);
+ if (!thread && threadid > 0) {
+ error_packet(remcom_out_buffer,
+ -EINVAL);
+ break;
+ }
+ kgdb_usethread = thread;
+ kgdb_usethreadid = threadid;
+ strcpy(remcom_out_buffer, "OK");
+ break;
+
+ case 'c':
+ ptr = &remcom_in_buffer[2];
+ kgdb_hex2long(&ptr, &threadid);
+ if (!threadid) {
+ kgdb_contthread = 0;
+ } else {
+ thread =
+ getthread(linux_regs, threadid);
+ if (!thread && threadid > 0) {
+ error_packet(remcom_out_buffer,
+ -EINVAL);
+ break;
+ }
+ kgdb_contthread = thread;
+ }
+ strcpy(remcom_out_buffer, "OK");
+ break;
+ }
+ break;
+
+ /* Query thread status */
+ case 'T':
+ ptr = &remcom_in_buffer[1];
+ kgdb_hex2long(&ptr, &threadid);
+ thread = getthread(linux_regs, threadid);
+ if (thread)
+ strcpy(remcom_out_buffer, "OK");
+ else
+ error_packet(remcom_out_buffer, -EINVAL);
+ break;
+ case 'z':
+ case 'Z':
+ ptr = &remcom_in_buffer[2];
+ if (*(ptr++) != ',') {
+ error_packet(remcom_out_buffer, -EINVAL);
+ break;
+ }
+ kgdb_hex2long(&ptr, &addr);
+
+ bpt_type = remcom_in_buffer[1];
+ if (bpt_type != bp_breakpoint) {
+ if (bpt_type == bp_hardware_breakpoint &&
+ !(kgdb_ops->flags & KGDB_HW_BREAKPOINT))
+ break;
+
+ /* if set_break is not defined, then
+ * remove_break does not matter
+ */
+ if (!(kgdb_ops->flags & KGDB_HW_BREAKPOINT))
+ break;
+ }
+
+ if (remcom_in_buffer[0] == 'Z') {
+ if (bpt_type == bp_breakpoint)
+ error = set_break(addr);
+ else
+ error = kgdb_arch_set_break(addr,
+ bpt_type);
+ } else {
+ if (bpt_type == bp_breakpoint)
+ error = remove_break(addr);
+ else
+ error = kgdb_arch_remove_break(addr,
+ bpt_type);
+ }
+
+ if (error == 0)
+ strcpy(remcom_out_buffer, "OK");
+ else
+ error_packet(remcom_out_buffer, error);
+
+ break;
+
+ default:
+ default_handle:
+ error = kgdb_arch_handle_exception(exVector, signo,
+ err_code,
+ remcom_in_buffer,
+ remcom_out_buffer,
+ linux_regs);
+
+ if (error >= 0 || remcom_in_buffer[0] == 'D' ||
+ remcom_in_buffer[0] == 'k')
+ goto kgdb_exit;
+
+ } /* switch */
+
+ /* reply to the request */
+ put_packet(remcom_out_buffer);
+ }
+
+ kgdb_exit:
+ procindebug[smp_processor_id()] = 0;
+
+ for (i = 0; i < num_online_cpus(); i++) {
+ spin_unlock(&slavecpulocks[i]);
+ }
+ /* Wait till all the processors have quit
+ * from the debugger
+ */
+ for (i = 0; i < num_online_cpus(); i++) {
+ while (procindebug[i]) {
+ int j = 10; /* an arbitrary number */
+
+ while (--j) {
+ asm volatile ("nop":::"memory");
+ }
+ barrier();
+ }
+ }
+
+ /* Free debugger_active */
+ atomic_set(&debugger_active, 0);
+ local_irq_restore(flags);
+
+ return error;
+}
+
+/*
+ * GDB places a breakpoint at this function to know dynamically
+ * loaded objects. It's not defined static so that only one instance with this
+ * name exists in the kernel.
+ */
+
+int module_event(struct notifier_block *self, unsigned long val, void *data)
+{
+ return 0;
+}
+
+static struct notifier_block kgdb_module_load_nb = {
+ .notifier_call = module_event,
+};
+
+/* 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 breakpoint(void)
+{
+ if (!kgdb_initialized) {
+ kgdb_enter = 1;
+ kgdb_entry();
+ if (!kgdb_initialized) {
+ printk("kgdb not enabled. Cannot do breakpoint\n");
+ return;
+ }
+ }
+
+ atomic_set(&kgdb_setting_breakpoint, 1);
+ wmb();
+ BREAKPOINT();
+ wmb();
+ atomic_set(&kgdb_setting_breakpoint, 0);
+}
+
+void kgdb_nmihook(int cpu, void *regs)
+{
+#ifdef CONFIG_SMP
+ if (!procindebug[cpu] && atomic_read(&debugger_active) != (cpu + 1)) {
+ kgdb_wait((struct pt_regs *)regs);
+ }
+#endif
+}
+
+void kgdb_entry(void)
+{
+ int i;
+
+ if (kgdb_initialized) {
+ /* KGDB was initialized */
+ return;
+ }
+
+ for (i = 0; i < KGDB_MAX_NO_CPUS; i++)
+ spin_lock_init(&slavecpulocks[i]);
+
+ /* Free debugger_active */
+ atomic_set(&debugger_active, 0);
+
+ for (i = 0; i < MAX_BREAKPOINTS; i++)
+ kgdb_break[i].state = bp_disabled;
+
+ linux_debug_hook = kgdb_handle_exception;
+
+ /* Let the arch do any initalization it needs to, including
+ * pointing to a suitable early output device. */
+ kgdb_arch_init();
+
+ /* We can't do much if this fails */
+ register_module_notifier(&kgdb_module_load_nb);
+
+ atomic_set(&kgdb_setting_breakpoint, 0);
+
+ if (!kgdb_serial || kgdb_serial->hook() < 0) {
+ /* KGDB interface isn't ready yet */
+ return;
+ }
+ kgdb_initialized = 1;
+ if (!kgdb_enter) {
+ return;
+ }
+ /*
+ * Call the breakpoint() routine in GDB to start the debugging
+ * session
+ */
+ printk(KERN_CRIT "Waiting for connection from remote gdb... ");
+ breakpoint();
+ printk("Connected.\n");
+}
+
+/*
+ * Sometimes we need to schedule a breakpoint because we can't break
+ * right where we are.
+ */
+static int kgdb_need_breakpoint[NR_CPUS];
+
+void kgdb_schedule_breakpoint(void)
+{
+ kgdb_need_breakpoint[smp_processor_id()] = 1;
+}
+
+void kgdb_process_breakpoint(void)
+{
+ /*
+ * Handle a breakpoint queued from inside network driver code
+ * to avoid reentrancy issues
+ */
+ if (kgdb_need_breakpoint[smp_processor_id()]) {
+ kgdb_need_breakpoint[smp_processor_id()] = 0;
+ breakpoint();
+ }
+}
+
+#ifdef CONFIG_KGDB_CONSOLE
+char kgdbconbuf[BUFMAX];
+
+void kgdb_console_write(struct console *co, const char *s, unsigned count)
+{
+ int i;
+ int wcount;
+ char *bufptr;
+ unsigned long flags;
+
+ if (!kgdb_connected) {
+ return;
+ }
+ local_irq_save(flags);
+
+ kgdbconbuf[0] = 'O';
+ bufptr = kgdbconbuf + 1;
+ while (count > 0) {
+ if ((count << 1) > (BUFMAX - 2)) {
+ wcount = (BUFMAX - 2) >> 1;
+ } else {
+ wcount = count;
+ }
+ count -= wcount;
+ for (i = 0; i < wcount; i++) {
+ bufptr = pack_hex_byte(bufptr, s[i]);
+ }
+ *bufptr = '\0';
+ s += wcount;
+
+ put_packet(kgdbconbuf);
+
+ }
+ local_irq_restore(flags);
+}
+
+/* Always fail so that kgdb console doesn't become the default console */
+static int __init kgdb_console_setup(struct console *co, char *options)
+{
+ return -1;
+}
+
+static struct console kgdbcons = {
+ .name = "kgdb",
+ .write = kgdb_console_write,
+ .setup = kgdb_console_setup,
+ .flags = CON_PRINTBUFFER | CON_ENABLED,
+ .index = -1,
+};
+
+static int __init kgdb_console_init(void)
+{
+ register_console(&kgdbcons);
+ return 0;
+}
+
+console_initcall(kgdb_console_init);
+#endif
+
+EXPORT_SYMBOL(breakpoint);
+#ifdef CONFIG_KGDB_THREAD
+EXPORT_SYMBOL(kern_schedule);
+#endif
+
+static int __init opt_kgdb_enter(char *str)
+{
+ kgdb_enter = 1;
+ return 1;
+}
+
+static int __init opt_gdb(char *str)
+{
+ kgdb_enter = 1;
+ return 1;
+}
+
+/*
+ * These options have been deprecated and are present only to maintain
+ * compatibility with kgdb for 2.4 and earlier kernels.
+ */
+#ifdef CONFIG_KGDB_8250
+extern int kgdb8250_baud;
+extern int kgdb8250_ttyS;
+static int __init opt_gdbttyS(char *str)
+{
+ kgdb8250_ttyS = simple_strtoul(str, NULL, 10);
+ return 1;
+}
+static int __init opt_gdbbaud(char *str)
+{
+ kgdb8250_baud = simple_strtoul(str, NULL, 10);
+ return 1;
+}
+#endif
+
+/*
+ *
+ * Sequence of following lines has to be maintained because gdb option is a
+ * prefix of the other two options
+ */
+
+#ifdef CONFIG_KGDB_8250
+__setup("gdbttyS=", opt_gdbttyS);
+__setup("gdbbaud=", opt_gdbbaud);
+#endif
+__setup("gdb", opt_gdb);
+__setup("kgdbwait", opt_kgdb_enter);
Index: linux-2.6.4-rc2-bk3-kgdb/kernel/sched.c
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/kernel/sched.c 2004-03-08 14:30:26.958856344 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/kernel/sched.c 2004-03-08 14:31:42.819323800 +0530
@@ -37,6 +37,7 @@
#include <linux/rcupdate.h>
#include <linux/cpu.h>
#include <linux/percpu.h>
+#include <linux/debugger.h>

#ifdef CONFIG_NUMA
#define cpu_to_node_mask(cpu) node_to_cpumask(cpu_to_node(cpu))
@@ -2961,6 +2962,8 @@
#if defined(in_atomic)
static unsigned long prev_jiffy; /* ratelimiting */

+ if (atomic_read(&debugger_active))
+ return;
if ((in_atomic() || irqs_disabled()) && system_running) {
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;
Index: linux-2.6.4-rc2-bk3-kgdb/kernel/Kconfig.kgdb
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/kernel/Kconfig.kgdb 2003-01-30 15:54:37.000000000 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/kernel/Kconfig.kgdb 2004-03-08 14:31:42.820323648 +0530
@@ -0,0 +1,13 @@
+config KGDB
+ bool "KGDB: kernel debugging with remote gdb"
+ depends on DEBUG_KERNEL
+ select DEBUG_INFO
+ select FRAME_POINTER
+ help
+ If you say Y here, it will be possible to remotely debug the
+ kernel using gdb. This enlarges your kernel image disk size by
+ several megabytes and requires a machine with more than 128 MB
+ RAM to avoid excessive linking time.
+ Documentation of kernel debugger available at
+ http://kgdb.sourceforge.net
+ This is only useful for kernel hackers. If unsure, say N.
Index: linux-2.6.4-rc2-bk3-kgdb/Documentation/kgdb.txt
===================================================================
--- linux-2.6.4-rc2-bk3-kgdb.orig/Documentation/kgdb.txt 2003-01-30 15:54:37.000000000 +0530
+++ linux-2.6.4-rc2-bk3-kgdb/Documentation/kgdb.txt 2004-03-08 14:31:42.820323648 +0530
@@ -0,0 +1,49 @@
+KGDB Linux kernel source level debugger
+
+Amit S. Kale <amitkale@emsyssoft.com>
+Last updated March 2004.
+
+Introduction:
+kgdb is a source level debugger for linux kernel. It is used along with gdb to
+debug a linux kernel. Kernel developers can debug a kernel similar to
+application programs with the use of kgdb. It makes it possible to place
+breakpoints in kernel code, step through the code and observe variables.
+
+Two machines are required for using kgdb. One of these machines is a
+development machine and the other is a test machine. The machines are
+connected through a serial line, a null-modem cable which connects their
+serial ports. The kernel to be debugged runs on the test machine. gdb runs on
+the development machine. The serial line is used by gdb to communicate to the
+kernel being debugged.
+
+This version of kgdb is a lite version. It is available on i386 platform uses
+a serial line for communicating to gdb. Full kgdb containing more features and
+supporting more architecture is available along with plenty of documentation
+at http://kgdb.sourceforge.net/
+
+Compiling a kernel:
+Enable Kernel hacking -> Kernel Debugging -> KGDB: kernel debugging with
+remote gdb
+
+Only generic serial port (8250) is supported in the lite version. Configure
+8250 options.
+
+Booting the kernel:
+Kernel command line option "kgdbwait" makes kgdb wait for gdb connection
+during booting of a kernel. If you have configured simple serial port, the
+port number and speed can be overriden on command line by using option
+"kgdb8250=portnumber,speed", where port numbers are 0-3 for COM1 to COM4
+respectively and supported speeds are 9600, 19200, 38400, 57600, 115200.
+Example: kgdbwait kgdb8250=0,115200
+
+Connecting gdb:
+If you have used "kgdbwait", kgdb prints a message "Waiting for connection
+from remote gdb..." on the console and waits for connection from gdb. At this
+point you connect gdb to kgdb.
+Example:
+ % gdb ./vmlinux
+ (gdb) set remotebaud 115200
+ (gdb) target remote /dev/ttyS0
+
+Once connected, you can debug a kernel the way you would debug an application
+program.