Merge tag 'kgdb-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux

Pull kgdb updates from Daniel Thompson:
 "Changes for kgdb/kdb this cycle are dominated by a change from Sumit
  that removes as small (256K) private heap from kdb. This is change
  I've hoped for ever since I discovered how few users of this heap
  remained in the kernel, so many thanks to Sumit for hunting these
  down.

  The other change is an incremental step towards SPDX headers"

* tag 'kgdb-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux:
  kernel: debug: Convert to SPDX identifier
  kdb: Rename members of struct kdbtab_t
  kdb: Simplify kdb_defcmd macro logic
  kdb: Get rid of redundant kdb_register_flags()
  kdb: Rename struct defcmd_set to struct kdb_macro
  kdb: Get rid of custom debug heap allocator

10 files changed, 387 insertions, 728 deletions

diff --git a/include/linux/kdb.h b/include/linux/kdb.h
index 0125a677b67f..ea0f5e580fac 100644
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -13,6 +13,8 @@
  * Copyright (C) 2009 Jason Wessel <jason.wessel@windriver.com>
  */
 
+#include <linux/list.h>
+
 /* Shifted versions of the command enable bits are be used if the command
  * has no arguments (see kdb_check_flags). This allows commands, such as
  * go, to have different permissions depending upon whether it is called
@@ -64,6 +66,17 @@ typedef enum {
 
 typedef int (*kdb_func_t)(int, const char **);
 
+/* The KDB shell command table */
+typedef struct _kdbtab {
+	char    *name;			/* Command name */
+	kdb_func_t func;		/* Function to execute command */
+	char    *usage;			/* Usage String for this command */
+	char    *help;			/* Help message for this command */
+	short    minlen;		/* Minimum legal # cmd chars required */
+	kdb_cmdflags_t flags;		/* Command behaviour flags */
+	struct list_head list_node;	/* Command list */
+} kdbtab_t;
+
 #ifdef	CONFIG_KGDB_KDB
 #include <linux/init.h>
 #include <linux/sched.h>
@@ -193,19 +206,13 @@ static inline const char *kdb_walk_kallsyms(loff_t *pos)
 #endif /* ! CONFIG_KALLSYMS */
 
 /* Dynamic kdb shell command registration */
-extern int kdb_register(char *, kdb_func_t, char *, char *, short);
-extern int kdb_register_flags(char *, kdb_func_t, char *, char *,
-			      short, kdb_cmdflags_t);
-extern int kdb_unregister(char *);
+extern int kdb_register(kdbtab_t *cmd);
+extern void kdb_unregister(kdbtab_t *cmd);
 #else /* ! CONFIG_KGDB_KDB */
 static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; }
 static inline void kdb_init(int level) {}
-static inline int kdb_register(char *cmd, kdb_func_t func, char *usage,
-			       char *help, short minlen) { return 0; }
-static inline int kdb_register_flags(char *cmd, kdb_func_t func, char *usage,
-				     char *help, short minlen,
-				     kdb_cmdflags_t flags) { return 0; }
-static inline int kdb_unregister(char *cmd) { return 0; }
+static inline int kdb_register(kdbtab_t *cmd) { return 0; }
+static inline void kdb_unregister(kdbtab_t *cmd) {}
 #endif	/* CONFIG_KGDB_KDB */
 enum {
 	KDB_NOT_INITIALIZED,
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index b4aa6bb6b2bd..da06a5553835 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Kernel Debug Core
  *
@@ -22,10 +23,6 @@
  *
  * 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.
  */
 
 #define pr_fmt(fmt) "KGDB: " fmt
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index b6f28fad4307..9d34d2364b5a 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Kernel Debug Core
  *
@@ -22,10 +23,6 @@
  *
  * 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/kernel.h>
diff --git a/kernel/debug/kdb/kdb_bp.c b/kernel/debug/kdb/kdb_bp.c
index 2168f8dacb99..372025cf1ca3 100644
--- a/kernel/debug/kdb/kdb_bp.c
+++ b/kernel/debug/kdb/kdb_bp.c
@@ -523,51 +523,51 @@ static int kdb_ss(int argc, const char **argv)
 }
 
 static kdbtab_t bptab[] = {
-	{	.cmd_name = "bp",
-		.cmd_func = kdb_bp,
-		.cmd_usage = "[<vaddr>]",
-		.cmd_help = "Set/Display breakpoints",
-		.cmd_flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
+	{	.name = "bp",
+		.func = kdb_bp,
+		.usage = "[<vaddr>]",
+		.help = "Set/Display breakpoints",
+		.flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
 	},
-	{	.cmd_name = "bl",
-		.cmd_func = kdb_bp,
-		.cmd_usage = "[<vaddr>]",
-		.cmd_help = "Display breakpoints",
-		.cmd_flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
+	{	.name = "bl",
+		.func = kdb_bp,
+		.usage = "[<vaddr>]",
+		.help = "Display breakpoints",
+		.flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
 	},
-	{	.cmd_name = "bc",
-		.cmd_func = kdb_bc,
-		.cmd_usage = "<bpnum>",
-		.cmd_help = "Clear Breakpoint",
-		.cmd_flags = KDB_ENABLE_FLOW_CTRL,
+	{	.name = "bc",
+		.func = kdb_bc,
+		.usage = "<bpnum>",
+		.help = "Clear Breakpoint",
+		.flags = KDB_ENABLE_FLOW_CTRL,
 	},
-	{	.cmd_name = "be",
-		.cmd_func = kdb_bc,
-		.cmd_usage = "<bpnum>",
-		.cmd_help = "Enable Breakpoint",
-		.cmd_flags = KDB_ENABLE_FLOW_CTRL,
+	{	.name = "be",
+		.func = kdb_bc,
+		.usage = "<bpnum>",
+		.help = "Enable Breakpoint",
+		.flags = KDB_ENABLE_FLOW_CTRL,
 	},
-	{	.cmd_name = "bd",
-		.cmd_func = kdb_bc,
-		.cmd_usage = "<bpnum>",
-		.cmd_help = "Disable Breakpoint",
-		.cmd_flags = KDB_ENABLE_FLOW_CTRL,
+	{	.name = "bd",
+		.func = kdb_bc,
+		.usage = "<bpnum>",
+		.help = "Disable Breakpoint",
+		.flags = KDB_ENABLE_FLOW_CTRL,
 	},
-	{	.cmd_name = "ss",
-		.cmd_func = kdb_ss,
-		.cmd_usage = "",
-		.cmd_help = "Single Step",
-		.cmd_minlen = 1,
-		.cmd_flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
+	{	.name = "ss",
+		.func = kdb_ss,
+		.usage = "",
+		.help = "Single Step",
+		.minlen = 1,
+		.flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
 	},
 };
 
 static kdbtab_t bphcmd = {
-	.cmd_name = "bph",
-	.cmd_func = kdb_bp,
-	.cmd_usage = "[<vaddr>]",
-	.cmd_help = "[datar [length]|dataw [length]]   Set hw brk",
-	.cmd_flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
+	.name = "bph",
+	.func = kdb_bp,
+	.usage = "[<vaddr>]",
+	.help = "[datar [length]|dataw [length]]   Set hw brk",
+	.flags = KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS,
 };
 
 /* Initialize the breakpoint table and register	breakpoint commands. */
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index 0220afda3200..e91fc3e4edd5 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -140,7 +140,6 @@ int kdb_stub(struct kgdb_state *ks)
 	 */
 	kdb_common_deinit_state();
 	KDB_STATE_CLEAR(PAGER);
-	kdbnearsym_cleanup();
 	if (error == KDB_CMD_KGDB) {
 		if (KDB_STATE(DOING_KGDB))
 			KDB_STATE_CLEAR(DOING_KGDB);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index d8ee5647b732..fa6deda894a1 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -33,7 +33,6 @@
 #include <linux/kallsyms.h>
 #include <linux/kgdb.h>
 #include <linux/kdb.h>
-#include <linux/list.h>
 #include <linux/notifier.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
@@ -654,16 +653,17 @@ static void kdb_cmderror(int diag)
  * Returns:
  *	zero for success, a kdb diagnostic if error
  */
-struct defcmd_set {
-	int count;
-	bool usable;
-	char *name;
-	char *usage;
-	char *help;
-	char **command;
+struct kdb_macro {
+	kdbtab_t cmd;			/* Macro command */
+	struct list_head statements;	/* Associated statement list */
 };
-static struct defcmd_set *defcmd_set;
-static int defcmd_set_count;
+
+struct kdb_macro_statement {
+	char *statement;		/* Statement text */
+	struct list_head list_node;	/* Statement list node */
+};
+
+static struct kdb_macro *kdb_macro;
 static bool defcmd_in_progress;
 
 /* Forward references */
@@ -671,53 +671,55 @@ static int kdb_exec_defcmd(int argc, const char **argv);
 
 static int kdb_defcmd2(const char *cmdstr, const char *argv0)
 {
-	struct defcmd_set *s = defcmd_set + defcmd_set_count - 1;
-	char **save_command = s->command;
+	struct kdb_macro_statement *kms;
+
+	if (!kdb_macro)
+		return KDB_NOTIMP;
+
 	if (strcmp(argv0, "endefcmd") == 0) {
 		defcmd_in_progress = false;
-		if (!s->count)
-			s->usable = false;
-		if (s->usable)
-			/* macros are always safe because when executed each
-			 * internal command re-enters kdb_parse() and is
-			 * safety checked individually.
-			 */
-			kdb_register_flags(s->name, kdb_exec_defcmd, s->usage,
-					   s->help, 0,
-					   KDB_ENABLE_ALWAYS_SAFE);
+		if (!list_empty(&kdb_macro->statements))
+			kdb_register(&kdb_macro->cmd);
 		return 0;
 	}
-	if (!s->usable)
-		return KDB_NOTIMP;
-	s->command = kcalloc(s->count + 1, sizeof(*(s->command)), GFP_KDB);
-	if (!s->command) {
-		kdb_printf("Could not allocate new kdb_defcmd table for %s\n",
+
+	kms = kmalloc(sizeof(*kms), GFP_KDB);
+	if (!kms) {
+		kdb_printf("Could not allocate new kdb macro command: %s\n",
 			   cmdstr);
-		s->usable = false;
 		return KDB_NOTIMP;
 	}
-	memcpy(s->command, save_command, s->count * sizeof(*(s->command)));
-	s->command[s->count++] = kdb_strdup(cmdstr, GFP_KDB);
-	kfree(save_command);
+
+	kms->statement = kdb_strdup(cmdstr, GFP_KDB);
+	list_add_tail(&kms->list_node, &kdb_macro->statements);
+
 	return 0;
 }
 
 static int kdb_defcmd(int argc, const char **argv)
 {
-	struct defcmd_set *save_defcmd_set = defcmd_set, *s;
+	kdbtab_t *mp;
+
 	if (defcmd_in_progress) {
 		kdb_printf("kdb: nested defcmd detected, assuming missing "
 			   "endefcmd\n");
 		kdb_defcmd2("endefcmd", "endefcmd");
 	}
 	if (argc == 0) {
-		int i;
-		for (s = defcmd_set; s < defcmd_set + defcmd_set_count; ++s) {
-			kdb_printf("defcmd %s \"%s\" \"%s\"\n", s->name,
-				   s->usage, s->help);
-			for (i = 0; i < s->count; ++i)
-				kdb_printf("%s", s->command[i]);
-			kdb_printf("endefcmd\n");
+		kdbtab_t *kp;
+		struct kdb_macro *kmp;
+		struct kdb_macro_statement *kms;
+
+		list_for_each_entry(kp, &kdb_cmds_head, list_node) {
+			if (kp->func == kdb_exec_defcmd) {
+				kdb_printf("defcmd %s \"%s\" \"%s\"\n",
+					   kp->name, kp->usage, kp->help);
+				kmp = container_of(kp, struct kdb_macro, cmd);
+				list_for_each_entry(kms, &kmp->statements,
+						    list_node)
+					kdb_printf("%s", kms->statement);
+				kdb_printf("endefcmd\n");
+			}
 		}
 		return 0;
 	}
@@ -727,45 +729,43 @@ static int kdb_defcmd(int argc, const char **argv)
 		kdb_printf("Command only available during kdb_init()\n");
 		return KDB_NOTIMP;
 	}
-	defcmd_set = kmalloc_array(defcmd_set_count + 1, sizeof(*defcmd_set),
-				   GFP_KDB);
-	if (!defcmd_set)
+	kdb_macro = kzalloc(sizeof(*kdb_macro), GFP_KDB);
+	if (!kdb_macro)
 		goto fail_defcmd;
-	memcpy(defcmd_set, save_defcmd_set,
-	       defcmd_set_count * sizeof(*defcmd_set));
-	s = defcmd_set + defcmd_set_count;
-	memset(s, 0, sizeof(*s));
-	s->usable = true;
-	s->name = kdb_strdup(argv[1], GFP_KDB);
-	if (!s->name)
+
+	mp = &kdb_macro->cmd;
+	mp->func = kdb_exec_defcmd;
+	mp->minlen = 0;
+	mp->flags = KDB_ENABLE_ALWAYS_SAFE;
+	mp->name = kdb_strdup(argv[1], GFP_KDB);
+	if (!mp->name)
 		goto fail_name;
-	s->usage = kdb_strdup(argv[2], GFP_KDB);
-	if (!s->usage)
+	mp->usage = kdb_strdup(argv[2], GFP_KDB);
+	if (!mp->usage)
 		goto fail_usage;
-	s->help = kdb_strdup(argv[3], GFP_KDB);
-	if (!s->help)
+	mp->help = kdb_strdup(argv[3], GFP_KDB);
+	if (!mp->help)
 		goto fail_help;
-	if (s->usage[0] == '"') {
-		strcpy(s->usage, argv[2]+1);
-		s->usage[strlen(s->usage)-1] = '\0';
+	if (mp->usage[0] == '"') {
+		strcpy(mp->usage, argv[2]+1);
+		mp->usage[strlen(mp->usage)-1] = '\0';
 	}
-	if (s->help[0] == '"') {
-		strcpy(s->help, argv[3]+1);
-		s->help[strlen(s->help)-1] = '\0';
+	if (mp->help[0] == '"') {
+		strcpy(mp->help, argv[3]+1);
+		mp->help[strlen(mp->help)-1] = '\0';
 	}
-	++defcmd_set_count;
+
+	INIT_LIST_HEAD(&kdb_macro->statements);
 	defcmd_in_progress = true;
-	kfree(save_defcmd_set);
 	return 0;
 fail_help:
-	kfree(s->usage);
+	kfree(mp->usage);
 fail_usage:
-	kfree(s->name);
+	kfree(mp->name);
 fail_name:
-	kfree(defcmd_set);
+	kfree(kdb_macro);
 fail_defcmd:
-	kdb_printf("Could not allocate new defcmd_set entry for %s\n", argv[1]);
-	defcmd_set = save_defcmd_set;
+	kdb_printf("Could not allocate new kdb_macro entry for %s\n", argv[1]);
 	return KDB_NOTIMP;
 }
 
@@ -780,25 +780,31 @@ fail_defcmd:
  */
 static int kdb_exec_defcmd(int argc, const char **argv)
 {
-	int i, ret;
-	struct defcmd_set *s;
+	int ret;
+	kdbtab_t *kp;
+	struct kdb_macro *kmp;
+	struct kdb_macro_statement *kms;
+
 	if (argc != 0)
 		return KDB_ARGCOUNT;
-	for (s = defcmd_set, i = 0; i < defcmd_set_count; ++i, ++s) {
-		if (strcmp(s->name, argv[0]) == 0)
+
+	list_for_each_entry(kp, &kdb_cmds_head, list_node) {
+		if (strcmp(kp->name, argv[0]) == 0)
 			break;
 	}
-	if (i == defcmd_set_count) {
+	if (list_entry_is_head(kp, &kdb_cmds_head, list_node)) {
 		kdb_printf("kdb_exec_defcmd: could not find commands for %s\n",
 			   argv[0]);
 		return KDB_NOTIMP;
 	}
-	for (i = 0; i < s->count; ++i) {
-		/* Recursive use of kdb_parse, do not use argv after
-		 * this point */
+	kmp = container_of(kp, struct kdb_macro, cmd);
+	list_for_each_entry(kms, &kmp->statements, list_node) {
+		/*
+		 * Recursive use of kdb_parse, do not use argv after this point.
+		 */
 		argv = NULL;
-		kdb_printf("[%s]kdb> %s\n", s->name, s->command[i]);
-		ret = kdb_parse(s->command[i]);
+		kdb_printf("[%s]kdb> %s\n", kmp->cmd.name, kms->statement);
+		ret = kdb_parse(kms->statement);
 		if (ret)
 			return ret;
 	}
@@ -1009,11 +1015,11 @@ int kdb_parse(const char *cmdstr)
 		 * If this command is allowed to be abbreviated,
 		 * check to see if this is it.
 		 */
-		if (tp->cmd_minlen && (strlen(argv[0]) <= tp->cmd_minlen) &&
-		    (strncmp(argv[0], tp->cmd_name, tp->cmd_minlen) == 0))
+		if (tp->minlen && (strlen(argv[0]) <= tp->minlen) &&
+		    (strncmp(argv[0], tp->name, tp->minlen) == 0))
 			break;
 
-		if (strcmp(argv[0], tp->cmd_name) == 0)
+		if (strcmp(argv[0], tp->name) == 0)
 			break;
 	}
 
@@ -1024,8 +1030,7 @@ int kdb_parse(const char *cmdstr)
 	 */
 	if (list_entry_is_head(tp, &kdb_cmds_head, list_node)) {
 		list_for_each_entry(tp, &kdb_cmds_head, list_node) {
-			if (strncmp(argv[0], tp->cmd_name,
-				    strlen(tp->cmd_name)) == 0)
+			if (strncmp(argv[0], tp->name, strlen(tp->name)) == 0)
 				break;
 		}
 	}
@@ -1033,19 +1038,19 @@ int kdb_parse(const char *cmdstr)
 	if (!list_entry_is_head(tp, &kdb_cmds_head, list_node)) {
 		int result;
 
-		if (!kdb_check_flags(tp->cmd_flags, kdb_cmd_enabled, argc <= 1))
+		if (!kdb_check_flags(tp->flags, kdb_cmd_enabled, argc <= 1))
 			return KDB_NOPERM;
 
 		KDB_STATE_SET(CMD);
-		result = (*tp->cmd_func)(argc-1, (const char **)argv);
+		result = (*tp->func)(argc-1, (const char **)argv);
 		if (result && ignore_errors && result > KDB_CMD_GO)
 			result = 0;
 		KDB_STATE_CLEAR(CMD);
 
-		if (tp->cmd_flags & KDB_REPEAT_WITH_ARGS)
+		if (tp->flags & KDB_REPEAT_WITH_ARGS)
 			return result;
 
-		argc = tp->cmd_flags & KDB_REPEAT_NO_ARGS ? 1 : 0;
+		argc = tp->flags & KDB_REPEAT_NO_ARGS ? 1 : 0;
 		if (argv[argc])
 			*(argv[argc]) = '\0';
 		return result;
@@ -2412,12 +2417,12 @@ static int kdb_help(int argc, const char **argv)
 		char *space = "";
 		if (KDB_FLAG(CMD_INTERRUPT))
 			return 0;
-		if (!kdb_check_flags(kt->cmd_flags, kdb_cmd_enabled, true))
+		if (!kdb_check_flags(kt->flags, kdb_cmd_enabled, true))
 			continue;
-		if (strlen(kt->cmd_usage) > 20)
+		if (strlen(kt->usage) > 20)
 			space = "\n                                    ";
-		kdb_printf("%-15.15s %-20s%s%s\n", kt->cmd_name,
-			   kt->cmd_usage, space, kt->cmd_help);
+		kdb_printf("%-15.15s %-20s%s%s\n", kt->name,
+			   kt->usage, space, kt->help);
 	}
 	return 0;
 }
@@ -2613,56 +2618,32 @@ static int kdb_grep_help(int argc, const char **argv)
 	return 0;
 }
 
-/*
- * kdb_register_flags - This function is used to register a kernel
- * 	debugger command.
- * Inputs:
- *	cmd	Command name
- *	func	Function to execute the command
- *	usage	A simple usage string showing arguments
- *	help	A simple help string describing command
- *	repeat	Does the command auto repeat on enter?
- * Returns:
- *	zero for success, one if a duplicate command.
+/**
+ * kdb_register() - This function is used to register a kernel debugger
+ *                  command.
+ * @cmd: pointer to kdb command
+ *
+ * Note that it's the job of the caller to keep the memory for the cmd
+ * allocated until unregister is called.
  */
-int kdb_register_flags(char *cmd,
-		       kdb_func_t func,
-		       char *usage,
-		       char *help,
-		       short minlen,
-		       kdb_cmdflags_t flags)
+int kdb_register(kdbtab_t *cmd)
 {
 	kdbtab_t *kp;
 
 	list_for_each_entry(kp, &kdb_cmds_head, list_node) {
-		if (strcmp(kp->cmd_name, cmd) == 0) {
-			kdb_printf("Duplicate kdb command registered: "
-				"%s, func %px help %s\n", cmd, func, help);
+		if (strcmp(kp->name, cmd->name) == 0) {
+			kdb_printf("Duplicate kdb cmd: %s, func %p help %s\n",
+				   cmd->name, cmd->func, cmd->help);
 			return 1;
 		}
 	}
 
-	kp = kmalloc(sizeof(*kp), GFP_KDB);
-	if (!kp) {
-		kdb_printf("Could not allocate new kdb_command table\n");
-		return 1;
-	}
-
-	kp->cmd_name   = cmd;
-	kp->cmd_func   = func;
-	kp->cmd_usage  = usage;
-	kp->cmd_help   = help;
-	kp->cmd_minlen = minlen;
-	kp->cmd_flags  = flags;
-	kp->is_dynamic = true;
-
-	list_add_tail(&kp->list_node, &kdb_cmds_head);
-
+	list_add_tail(&cmd->list_node, &kdb_cmds_head);
 	return 0;
 }
-EXPORT_SYMBOL_GPL(kdb_register_flags);
+EXPORT_SYMBOL_GPL(kdb_register);
 
-/*
+/**
  * kdb_register_table() - This function is used to register a kdb command
  *                        table.
  * @kp: pointer to kdb command table
@@ -2676,266 +2657,231 @@ void kdb_register_table(kdbtab_t *kp, size_t len)
 	}
 }
 
-/*
- * kdb_register - Compatibility register function for commands that do
- *	not need to specify a repeat state.  Equivalent to
- *	kdb_register_flags with flags set to 0.
- * Inputs:
- *	cmd	Command name
- *	func	Function to execute the command
- *	usage	A simple usage string showing arguments
- *	help	A simple help string describing command
- * Returns:
- *	zero for success, one if a duplicate command.
+/**
+ * kdb_unregister() - This function is used to unregister a kernel debugger
+ *                    command. It is generally called when a module which
+ *                    implements kdb command is unloaded.
+ * @cmd: pointer to kdb command
  */
-int kdb_register(char *cmd,
-	     kdb_func_t func,
-	     char *usage,
-	     char *help,
-	     short minlen)
+void kdb_unregister(kdbtab_t *cmd)
 {
-	return kdb_register_flags(cmd, func, usage, help, minlen, 0);
-}
-EXPORT_SYMBOL_GPL(kdb_register);
-
-/*
- * kdb_unregister - This function is used to unregister a kernel
- *	debugger command.  It is generally called when a module which
- *	implements kdb commands is unloaded.
- * Inputs:
- *	cmd	Command name
- * Returns:
- *	zero for success, one command not registered.
- */
-int kdb_unregister(char *cmd)
-{
-	kdbtab_t *kp;
-
-	/*
-	 *  find the command.
-	 */
-	list_for_each_entry(kp, &kdb_cmds_head, list_node) {
-		if (strcmp(kp->cmd_name, cmd) == 0) {
-			list_del(&kp->list_node);
-			if (kp->is_dynamic)
-				kfree(kp);
-			return 0;
-		}
-	}
-
-	/* Couldn't find it.  */
-	return 1;
+	list_del(&cmd->list_node);
 }
 EXPORT_SYMBOL_GPL(kdb_unregister);
 
 static kdbtab_t maintab[] = {
-	{	.cmd_name = "md",
-		.cmd_func = kdb_md,
-		.cmd_usage = "<vaddr>",
-		.cmd_help = "Display Memory Contents, also mdWcN, e.g. md8c1",
-		.cmd_minlen = 1,
-		.cmd_flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
+	{	.name = "md",
+		.func = kdb_md,
+		.usage = "<vaddr>",
+		.help = "Display Memory Contents, also mdWcN, e.g. md8c1",
+		.minlen = 1,
+		.flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
 	},
-	{	.cmd_name = "mdr",
-		.cmd_func = kdb_md,
-		.cmd_usage = "<vaddr> <bytes>",
-		.cmd_help = "Display Raw Memory",
-		.cmd_flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
+	{	.name = "mdr",
+		.func = kdb_md,
+		.usage = "<vaddr> <bytes>",
+		.help = "Display Raw Memory",
+		.flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
 	},
-	{	.cmd_name = "mdp",
-		.cmd_func = kdb_md,
-		.cmd_usage = "<paddr> <bytes>",
-		.cmd_help = "Display Physical Memory",
-		.cmd_flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
+	{	.name = "mdp",
+		.func = kdb_md,
+		.usage = "<paddr> <bytes>",
+		.help = "Display Physical Memory",
+		.flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
 	},
-	{	.cmd_name = "mds",
-		.cmd_func = kdb_md,
-		.cmd_usage = "<vaddr>",
-		.cmd_help = "Display Memory Symbolically",
-		.cmd_flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
+	{	.name = "mds",
+		.func = kdb_md,
+		.usage = "<vaddr>",
+		.help = "Display Memory Symbolically",
+		.flags = KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS,
 	},
-	{	.cmd_name = "mm",
-		.cmd_func = kdb_mm,
-		.cmd_usage = "<vaddr> <contents>",
-		.cmd_help = "Modify Memory Contents",
-		.cmd_flags = KDB_ENABLE_MEM_WRITE | KDB_REPEAT_NO_ARGS,
+	{	.name = "mm",
+		.func = kdb_mm,
+		.usage = "<vaddr> <contents>",
+		.help = "Modify Memory Contents",
+		.flags = KDB_ENABLE_MEM_WRITE | KDB_REPEAT_NO_ARGS,
 	},
-	{	.cmd_name = "go",
-		.cmd_func = kdb_go,
-		.cmd_usage = "[<vaddr>]",
-		.cmd_help = "Continue Execution",
-		.cmd_minlen = 1,
-		.cmd_flags = KDB_ENABLE_REG_WRITE |
+	{	.name = "go",
+		.func = kdb_go,
+		.usage = "[<vaddr>]",
+		.help = "Continue Execution",
+		.minlen = 1,
+		.flags = KDB_ENABLE_REG_WRITE |
 			     KDB_ENABLE_ALWAYS_SAFE_NO_ARGS,
 	},
-	{	.cmd_name = "rd",
-		.cmd_func = kdb_rd,
-		.cmd_usage = "",
-		.cmd_help = "Display Registers",
-		.cmd_flags = KDB_ENABLE_REG_READ,
+	{	.name = "rd",
+		.func = kdb_rd,
+		.usage = "",
+		.help = "Display Registers",
+		.flags = KDB_ENABLE_REG_READ,
 	},
-	{	.cmd_name = "rm",
-		.cmd_func = kdb_rm,
-		.cmd_usage = "<reg> <contents>",
-		.cmd_help = "Modify Registers",
-		.cmd_flags = KDB_ENABLE_REG_WRITE,
+	{	.name = "rm",
+		.func = kdb_rm,
+		.usage = "<reg> <contents>",
+		.help = "Modify Registers",
+		.flags = KDB_ENABLE_REG_WRITE,
 	},
-	{	.cmd_name = "ef",
-		.cmd_func = kdb_ef,
-		.cmd_usage = "<vaddr>",
-		.cmd_help = "Display exception frame",
-		.cmd_flags = KDB_ENABLE_MEM_READ,
+	{	.name = "ef",
+		.func = kdb_ef,
+		.usage = "<vaddr>",
+		.help = "Display exception frame",
+		.flags = KDB_ENABLE_MEM_READ,
 	},
-	{	.cmd_name = "bt",
-		.cmd_func = kdb_bt,
-		.cmd_usage = "[<vaddr>]",
-		.cmd_help = "Stack traceback",
-		.cmd_minlen = 1,
-		.cmd_flags = KDB_ENABLE_MEM_READ | KDB_ENABLE_INSPECT_NO_ARGS,
+	{	.name = "bt",
+		.func = kdb_bt,
+		.usage = "[<vaddr>]",
+		.help = "Stack traceback",
+		.minlen = 1,
+		.flags = KDB_ENABLE_MEM_READ | KDB_ENABLE_INSPECT_NO_ARGS,
 	},
-	{	.cmd_name = "btp",
-		.cmd_func = kdb_bt,
-		.cmd_usage = "<pid>",
-		.cmd_help = "Display stack for process <pid>",
-		.cmd_flags = KDB_ENABLE_INSPECT,
+	{	.name = "btp",
+		.func = kdb_bt,
+		.usage = "<pid>",
+		.help = "Display stack for process <pid>",
+		.flags = KDB_ENABLE_INSPECT,
 	},
-	{	.cmd_name = "bta",
-		.cmd_func = kdb_bt,
-		.cmd_usage = "[D|R|S|T|C|Z|E|U|I|M|A]",
-		.cmd_help = "Backtrace all processes matching state flag",
-		.cmd_flags = KDB_ENABLE_INSPECT,
+	{	.name = "bta",
+		.func = kdb_bt,
+		.usage = "[D|R|S|T|C|Z|E|U|I|M|A]",
+		.help = "Backtrace all processes matching state flag",
+		.flags = KDB_ENABLE_INSPECT,
 	},
-	{	.cmd_name = "btc",
-		.cmd_func = kdb_bt,
-		.cmd_usage = "",
-		.cmd_help = "Backtrace current process on each cpu",
-		.cmd_flags = KDB_ENABLE_INSPECT,
+	{	.name = "btc",
+		.func = kdb_bt,
+		.usage = "",
+		.help = "Backtrace current process on each cpu",
+		.flags = KDB_ENABLE_INSPECT,
 	},
-	{	.cmd_name = "btt",
-		.cmd_func = kdb_bt,
-		.cmd_usage = "<vaddr>",
-		.cmd_help = "Backtrace process given its struct task address",
-		.cmd_flags = KDB_ENABLE_MEM_READ | KDB_ENABLE_INSPECT_NO_ARGS,
+	{	.name = "btt",
+		.func = kdb_bt,
+		.usage = "<vaddr>",
+		.help = "Backtrace process given its struct task address",
+		.flags = KDB_ENABLE_MEM_READ | KDB_ENABLE_INSPECT_NO_ARGS,
 	},
-	{	.cmd_name = "env",
-		.cmd_func = kdb_env,
-		.cmd_usage = "",
-		.cmd_help = "Show environment variables",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "env",
+		.func = kdb_env,
+		.usage = "",
+		.help = "Show environment variables",
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
-	{	.cmd_name = "set",
-		.cmd_func = kdb_set,
-		.cmd_usage = "",
-		.cmd_help = "Set environment variables",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "set",
+		.func = kdb_set,
+		.usage = "",
+		.help = "Set environment variables",
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
-	{	.cmd_name = "help",
-		.cmd_func = kdb_help,
-		.cmd_usage = "",
-		.cmd_help = "Display Help Message",
-		.cmd_minlen = 1,
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "help",
+		.func = kdb_help,
+		.usage = "",
+		.help = "Display Help Message",
+		.minlen = 1,
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
-	{	.cmd_name = "?",
-		.cmd_func = kdb_help,
-		.cmd_usage = "",
-		.cmd_help = "Display Help Message",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "?",
+		.func = kdb_help,
+		.usage = "",
+		.help = "Display Help Message",
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
-	{	.cmd_name = "cpu",
-		.cmd_func = kdb_cpu,
-		.cmd_usage = "<cpunum>",
-		.cmd_help = "Switch to new cpu",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE_NO_ARGS,
+	{	.name = "cpu",
+		.func = kdb_cpu,
+		.usage = "<cpunum>",
+		.help = "Switch to new cpu",
+		.flags = KDB_ENABLE_ALWAYS_SAFE_NO_ARGS,
 	},
-	{	.cmd_name = "kgdb",
-		.cmd_func = kdb_kgdb,
-		.cmd_usage = "",
-		.cmd_help = "Enter kgdb mode",
-		.cmd_flags = 0,
+	{	.name = "kgdb",
+		.func = kdb_kgdb,
+		.usage = "",
+		.help = "Enter kgdb mode",
+		.flags = 0,
 	},
-	{	.cmd_name = "ps",
-		.cmd_func = kdb_ps,
-		.cmd_usage = "[<flags>|A]",
-		.cmd_help = "Display active task list",
-		.cmd_flags = KDB_ENABLE_INSPECT,
+	{	.name = "ps",
+		.func = kdb_ps,
+		.usage = "[<flags>|A]",
+		.help = "Display active task list",
+		.flags = KDB_ENABLE_INSPECT,
 	},
-	{	.cmd_name = "pid",
-		.cmd_func = kdb_pid,
-		.cmd_usage = "<pidnum>",
-		.cmd_help = "Switch to another task",
-		.cmd_flags = KDB_ENABLE_INSPECT,
+	{	.name = "pid",
+		.func = kdb_pid,
+		.usage = "<pidnum>",
+		.help = "Switch to another task",
+		.flags = KDB_ENABLE_INSPECT,
 	},
-	{	.cmd_name = "reboot",
-		.cmd_func = kdb_reboot,
-		.cmd_usage = "",
-		.cmd_help = "Reboot the machine immediately",
-		.cmd_flags = KDB_ENABLE_REBOOT,
+	{	.name = "reboot",
+		.func = kdb_reboot,
+		.usage = "",
+		.help = "Reboot the machine immediately",
+		.flags = KDB_ENABLE_REBOOT,
 	},
 #if defined(CONFIG_MODULES)
-	{	.cmd_name = "lsmod",
-		.cmd_func = kdb_lsmod,
-		.cmd_usage = "",
-		.cmd_help = "List loaded kernel modules",
-		.cmd_flags = KDB_ENABLE_INSPECT,
+	{	.name = "lsmod",
+		.func = kdb_lsmod,
+		.usage = "",
+		.help = "List loaded kernel modules",
+		.flags = KDB_ENABLE_INSPECT,
 	},
 #endif
 #if defined(CONFIG_MAGIC_SYSRQ)
-	{	.cmd_name = "sr",
-		.cmd_func = kdb_sr,
-		.cmd_usage = "<key>",
-		.cmd_help = "Magic SysRq key",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "sr",
+		.func = kdb_sr,
+		.usage = "<key>",
+		.help = "Magic SysRq key",
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
 #endif
 #if defined(CONFIG_PRINTK)
-	{	.cmd_name = "dmesg",
-		.cmd_func = kdb_dmesg,
-		.cmd_usage = "[lines]",
-		.cmd_help = "Display syslog buffer",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "dmesg",
+		.func = kdb_dmesg,
+		.usage = "[lines]",
+		.help = "Display syslog buffer",
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
 #endif
-	{	.cmd_name = "defcmd",
-		.cmd_func = kdb_defcmd,
-		.cmd_usage = "name \"usage\" \"help\"",
-		.cmd_help = "Define a set of commands, down to endefcmd",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "defcmd",
+		.func = kdb_defcmd,
+		.usage = "name \"usage\" \"help\"",
+		.help = "Define a set of commands, down to endefcmd",
+		/*
+		 * Macros are always safe because when executed each
+		 * internal command re-enters kdb_parse() and is safety
+		 * checked individually.
+		 */
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
-	{	.cmd_name = "kill",
-		.cmd_func = kdb_kill,
-		.cmd_usage = "<-signal> <pid>",
-		.cmd_help = "Send a signal to a process",
-		.cmd_flags = KDB_ENABLE_SIGNAL,
+	{	.name = "kill",
+		.func = kdb_kill,
+		.usage = "<-signal> <pid>",
+		.help = "Send a signal to a process",
+		.flags = KDB_ENABLE_SIGNAL,
 	},
-	{	.cmd_name = "summary",
-		.cmd_func = kdb_summary,
-		.cmd_usage = "",
-		.cmd_help = "Summarize the system",
-		.cmd_minlen = 4,
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "summary",
+		.func = kdb_summary,
+		.usage = "",
+		.help = "Summarize the system",
+		.minlen = 4,
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
-	{	.cmd_name = "per_cpu",
-		.cmd_func = kdb_per_cpu,
-		.cmd_usage = "<sym> [<bytes>] [<cpu>]",
-		.cmd_help = "Display per_cpu variables",
-		.cmd_minlen = 3,
-		.cmd_flags = KDB_ENABLE_MEM_READ,
+	{	.name = "per_cpu",
+		.func = kdb_per_cpu,
+		.usage = "<sym> [<bytes>] [<cpu>]",
+		.help = "Display per_cpu variables",
+		.minlen = 3,
+		.flags = KDB_ENABLE_MEM_READ,
 	},
-	{	.cmd_name = "grephelp",
-		.cmd_func = kdb_grep_help,
-		.cmd_usage = "",
-		.cmd_help = "Display help on | grep",
-		.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	{	.name = "grephelp",
+		.func = kdb_grep_help,
+		.usage = "",
+		.help = "Display help on | grep",
+		.flags = KDB_ENABLE_ALWAYS_SAFE,
 	},
 };
 
 static kdbtab_t nmicmd = {
-	.cmd_name = "disable_nmi",
-	.cmd_func = kdb_disable_nmi,
-	.cmd_usage = "",
-	.cmd_help = "Disable NMI entry to KDB",
-	.cmd_flags = KDB_ENABLE_ALWAYS_SAFE,
+	.name = "disable_nmi",
+	.func = kdb_disable_nmi,
+	.usage = "",
+	.help = "Disable NMI entry to KDB",
+	.flags = KDB_ENABLE_ALWAYS_SAFE,
 };
 
 /* Initialize the kdb command table. */
diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index 170c69aedebb..629590084a0d 100644
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -109,7 +109,6 @@ extern int kdbgetaddrarg(int, const char **, int*, unsigned long *,
 			 long *, char **);
 extern int kdbgetsymval(const char *, kdb_symtab_t *);
 extern int kdbnearsym(unsigned long, kdb_symtab_t *);
-extern void kdbnearsym_cleanup(void);
 extern char *kdb_strdup(const char *str, gfp_t type);
 extern void kdb_symbol_print(unsigned long, const kdb_symtab_t *, unsigned int);
 
@@ -165,19 +164,6 @@ typedef struct _kdb_bp {
 #ifdef CONFIG_KGDB_KDB
 extern kdb_bp_t kdb_breakpoints[/* KDB_MAXBPT */];
 
-/* The KDB shell command table */
-typedef struct _kdbtab {
-	char    *cmd_name;		/* Command name */
-	kdb_func_t cmd_func;		/* Function to execute command */
-	char    *cmd_usage;		/* Usage String for this command */
-	char    *cmd_help;		/* Help message for this command */
-	short    cmd_minlen;		/* Minimum legal # command
-					 * chars required */
-	kdb_cmdflags_t cmd_flags;	/* Command behaviour flags */
-	struct list_head list_node;	/* Command list */
-	bool    is_dynamic;		/* Command table allocation type */
-} kdbtab_t;
-
 extern void kdb_register_table(kdbtab_t *kp, size_t len);
 extern int kdb_bt(int, const char **);	/* KDB display back trace */
 
@@ -233,10 +219,6 @@ extern struct task_struct *kdb_curr_task(int);
 
 #define GFP_KDB (in_dbg_master() ? GFP_ATOMIC : GFP_KERNEL)
 
-extern void *debug_kmalloc(size_t size, gfp_t flags);
-extern void debug_kfree(void *);
-extern void debug_kusage(void);
-
 extern struct task_struct *kdb_current_task;
 extern struct pt_regs *kdb_current_regs;
 
diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c
index 4f9950678e7b..7507d9a8dc6a 100644
--- a/kernel/debug/kdb/kdb_support.c
+++ b/kernel/debug/kdb/kdb_support.c
@@ -51,48 +51,48 @@ int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
 }
 EXPORT_SYMBOL(kdbgetsymval);
 
-static char *kdb_name_table[100];	/* arbitrary size */
-
-/*
- * kdbnearsym -	Return the name of the symbol with the nearest address
- *	less than 'addr'.
+/**
+ * kdbnearsym() - Return the name of the symbol with the nearest address
+ *                less than @addr.
+ * @addr: Address to check for near symbol
+ * @symtab: Structure to receive results
  *
- * Parameters:
- *	addr	Address to check for symbol near
- *	symtab  Structure to receive results
- * Returns:
- *	0	No sections contain this address, symtab zero filled
- *	1	Address mapped to module/symbol/section, data in symtab
- * Remarks:
- *	2.6 kallsyms has a "feature" where it unpacks the name into a
- *	string.  If that string is reused before the caller expects it
- *	then the caller sees its string change without warning.  To
- *	avoid cluttering up the main kdb code with lots of kdb_strdup,
- *	tests and kfree calls, kdbnearsym maintains an LRU list of the
- *	last few unique strings.  The list is sized large enough to
- *	hold active strings, no kdb caller of kdbnearsym makes more
- *	than ~20 later calls before using a saved value.
+ * WARNING: This function may return a pointer to a single statically
+ * allocated buffer (namebuf). kdb's unusual calling context (single
+ * threaded, all other CPUs halted) provides us sufficient locking for
+ * this to be safe. The only constraint imposed by the static buffer is
+ * that the caller must consume any previous reply prior to another call
+ * to lookup a new symbol.
+ *
+ * Note that, strictly speaking, some architectures may re-enter the kdb
+ * trap if the system turns out to be very badly damaged and this breaks
+ * the single-threaded assumption above. In these circumstances successful
+ * continuation and exit from the inner trap is unlikely to work and any
+ * user attempting this receives a prominent warning before being allowed
+ * to progress. In these circumstances we remain memory safe because
+ * namebuf[KSYM_NAME_LEN-1] will never change from '\0' although we do
+ * tolerate the possibility of garbled symbol display from the outer kdb
+ * trap.
+ *
+ * Return:
+ * * 0 - No sections contain this address, symtab zero filled
+ * * 1 - Address mapped to module/symbol/section, data in symtab
  */
 int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
 {
 	int ret = 0;
 	unsigned long symbolsize = 0;
 	unsigned long offset = 0;
-#define knt1_size 128		/* must be >= kallsyms table size */
-	char *knt1 = NULL;
+	static char namebuf[KSYM_NAME_LEN];
 
 	kdb_dbg_printf(AR, "addr=0x%lx, symtab=%px\n", addr, symtab);
 	memset(symtab, 0, sizeof(*symtab));
 
 	if (addr < 4096)
 		goto out;
-	knt1 = debug_kmalloc(knt1_size, GFP_ATOMIC);
-	if (!knt1) {
-		kdb_func_printf("addr=0x%lx cannot kmalloc knt1\n", addr);
-		goto out;
-	}
+
 	symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
-				(char **)(&symtab->mod_name), knt1);
+				(char **)(&symtab->mod_name), namebuf);
 	if (offset > 8*1024*1024) {
 		symtab->sym_name = NULL;
 		addr = offset = symbolsize = 0;
@@ -101,63 +101,14 @@ int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
 	symtab->sym_end = symtab->sym_start + symbolsize;
 	ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
 
-	if (ret) {
-		int i;
-		/* Another 2.6 kallsyms "feature".  Sometimes the sym_name is
-		 * set but the buffer passed into kallsyms_lookup is not used,
-		 * so it contains garbage.  The caller has to work out which
-		 * buffer needs to be saved.
-		 *
-		 * What was Rusty smoking when he wrote that code?
-		 */
-		if (symtab->sym_name != knt1) {
-			strncpy(knt1, symtab->sym_name, knt1_size);
-			knt1[knt1_size-1] = '\0';
-		}
-		for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
-			if (kdb_name_table[i] &&
-			    strcmp(kdb_name_table[i], knt1) == 0)
-				break;
-		}
-		if (i >= ARRAY_SIZE(kdb_name_table)) {
-			debug_kfree(kdb_name_table[0]);
-			memmove(kdb_name_table, kdb_name_table+1,
-			       sizeof(kdb_name_table[0]) *
-			       (ARRAY_SIZE(kdb_name_table)-1));
-		} else {
-			debug_kfree(knt1);
-			knt1 = kdb_name_table[i];
-			memmove(kdb_name_table+i, kdb_name_table+i+1,
-			       sizeof(kdb_name_table[0]) *
-			       (ARRAY_SIZE(kdb_name_table)-i-1));
-		}
-		i = ARRAY_SIZE(kdb_name_table) - 1;
-		kdb_name_table[i] = knt1;
-		symtab->sym_name = kdb_name_table[i];
-		knt1 = NULL;
-	}
-
 	if (symtab->mod_name == NULL)
 		symtab->mod_name = "kernel";
 	kdb_dbg_printf(AR, "returns %d symtab->sym_start=0x%lx, symtab->mod_name=%px, symtab->sym_name=%px (%s)\n",
 		       ret, symtab->sym_start, symtab->mod_name, symtab->sym_name, symtab->sym_name);
-
 out:
-	debug_kfree(knt1);
 	return ret;
 }
 
-void kdbnearsym_cleanup(void)
-{
-	int i;
-	for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
-		if (kdb_name_table[i]) {
-			debug_kfree(kdb_name_table[i]);
-			kdb_name_table[i] = NULL;
-		}
-	}
-}
-
 static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
 
 /*
@@ -655,230 +606,6 @@ unsigned long kdb_task_state(const struct task_struct *p, unsigned long mask)
 	return (mask & kdb_task_state_string(state)) != 0;
 }
 
-/* Last ditch allocator for debugging, so we can still debug even when
- * the GFP_ATOMIC pool has been exhausted.  The algorithms are tuned
- * for space usage, not for speed.  One smallish memory pool, the free
- * chain is always in ascending address order to allow coalescing,
- * allocations are done in brute force best fit.
- */
-
-struct debug_alloc_header {
-	u32 next;	/* offset of next header from start of pool */
-	u32 size;
-	void *caller;
-};
-
-/* The memory returned by this allocator must be aligned, which means
- * so must the header size.  Do not assume that sizeof(struct
- * debug_alloc_header) is a multiple of the alignment, explicitly
- * calculate the overhead of this header, including the alignment.
- * The rest of this code must not use sizeof() on any header or
- * pointer to a header.
- */
-#define dah_align 8
-#define dah_overhead ALIGN(sizeof(struct debug_alloc_header), dah_align)
-
-static u64 debug_alloc_pool_aligned[256*1024/dah_align];	/* 256K pool */
-static char *debug_alloc_pool = (char *)debug_alloc_pool_aligned;
-static u32 dah_first, dah_first_call = 1, dah_used, dah_used_max;
-
-/* Locking is awkward.  The debug code is called from all contexts,
- * including non maskable interrupts.  A normal spinlock is not safe
- * in NMI context.  Try to get the debug allocator lock, if it cannot
- * be obtained after a second then give up.  If the lock could not be
- * previously obtained on this cpu then only try once.
- *
- * sparse has no annotation for "this function _sometimes_ acquires a
- * lock", so fudge the acquire/release notation.
- */
-static DEFINE_SPINLOCK(dap_lock);
-static int get_dap_lock(void)
-	__acquires(dap_lock)
-{
-	static int dap_locked = -1;
-	int count;
-	if (dap_locked == smp_processor_id())
-		count = 1;
-	else
-		count = 1000;
-	while (1) {
-		if (spin_trylock(&dap_lock)) {
-			dap_locked = -1;
-			return 1;
-		}
-		if (!count--)
-			break;
-		udelay(1000);
-	}
-	dap_locked = smp_processor_id();
-	__acquire(dap_lock);
-	return 0;
-}
-
-void *debug_kmalloc(size_t size, gfp_t flags)
-{
-	unsigned int rem, h_offset;
-	struct debug_alloc_header *best, *bestprev, *prev, *h;
-	void *p = NULL;
-	if (!get_dap_lock()) {
-		__release(dap_lock);	/* we never actually got it */
-		return NULL;
-	}
-	h = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
-	if (dah_first_call) {
-		h->size = sizeof(debug_alloc_pool_aligned) - dah_overhead;
-		dah_first_call = 0;
-	}
-	size = ALIGN(size, dah_align);
-	prev = best = bestprev = NULL;
-	while (1) {
-		if (h->size >= size && (!best || h->size < best->size)) {
-			best = h;
-			bestprev = prev;
-			if (h->size == size)
-				break;
-		}
-		if (!h->next)
-			break;
-		prev = h;
-		h = (struct debug_alloc_header *)(debug_alloc_pool + h->next);
-	}
-	if (!best)
-		goto out;
-	rem = best->size - size;
-	/* The pool must always contain at least one header */
-	if (best->next == 0 && bestprev == NULL && rem < dah_overhead)
-		goto out;
-	if (rem >= dah_overhead) {
-		best->size = size;
-		h_offset = ((char *)best - debug_alloc_pool) +
-			   dah_overhead + best->size;
-		h = (struct debug_alloc_header *)(debug_alloc_pool + h_offset);
-		h->size = rem - dah_overhead;
-		h->next = best->next;
-	} else
-		h_offset = best->next;
-	best->caller = __builtin_return_address(0);
-	dah_used += best->size;
-	dah_used_max = max(dah_used, dah_used_max);
-	if (bestprev)
-		bestprev->next = h_offset;
-	else
-		dah_first = h_offset;
-	p = (char *)best + dah_overhead;
-	memset(p, POISON_INUSE, best->size - 1);
-	*((char *)p + best->size - 1) = POISON_END;
-out:
-	spin_unlock(&dap_lock);
-	return p;
-}
-
-void debug_kfree(void *p)
-{
-	struct debug_alloc_header *h;
-	unsigned int h_offset;
-	if (!p)
-		return;
-	if ((char *)p < debug_alloc_pool ||
-	    (char *)p >= debug_alloc_pool + sizeof(debug_alloc_pool_aligned)) {
-		kfree(p);
-		return;
-	}
-	if (!get_dap_lock()) {
-		__release(dap_lock);	/* we never actually got it */
-		return;		/* memory leak, cannot be helped */
-	}
-	h = (struct debug_alloc_header *)((char *)p - dah_overhead);
-	memset(p, POISON_FREE, h->size - 1);
-	*((char *)p + h->size - 1) = POISON_END;
-	h->caller = NULL;
-	dah_used -= h->size;
-	h_offset = (char *)h - debug_alloc_pool;
-	if (h_offset < dah_first) {
-		h->next = dah_first;
-		dah_first = h_offset;
-	} else {
-		struct debug_alloc_header *prev;
-		unsigned int prev_offset;
-		prev = (struct debug_alloc_header *)(debug_alloc_pool +
-						     dah_first);
-		while (1) {
-			if (!prev->next || prev->next > h_offset)
-				break;
-			prev = (struct debug_alloc_header *)
-				(debug_alloc_pool + prev->next);
-		}
-		prev_offset = (char *)prev - debug_alloc_pool;
-		if (prev_offset + dah_overhead + prev->size == h_offset) {
-			prev->size += dah_overhead + h->size;
-			memset(h, POISON_FREE, dah_overhead - 1);
-			*((char *)h + dah_overhead - 1) = POISON_END;
-			h = prev;
-			h_offset = prev_offset;
-		} else {
-			h->next = prev->next;
-			prev->next = h_offset;
-		}
-	}
-	if (h_offset + dah_overhead + h->size == h->next) {
-		struct debug_alloc_header *next;
-		next = (struct debug_alloc_header *)
-			(debug_alloc_pool + h->next);
-		h->size += dah_overhead + next->size;
-		h->next = next->next;
-		memset(next, POISON_FREE, dah_overhead - 1);
-		*((char *)next + dah_overhead - 1) = POISON_END;
-	}
-	spin_unlock(&dap_lock);
-}
-
-void debug_kusage(void)
-{
-	struct debug_alloc_header *h_free, *h_used;
-#ifdef	CONFIG_IA64
-	/* FIXME: using dah for ia64 unwind always results in a memory leak.
-	 * Fix that memory leak first, then set debug_kusage_one_time = 1 for
-	 * all architectures.
-	 */
-	static int debug_kusage_one_time;
-#else
-	static int debug_kusage_one_time = 1;
-#endif
-	if (!get_dap_lock()) {
-		__release(dap_lock);	/* we never actually got it */
-		return;
-	}
-	h_free = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
-	if (dah_first == 0 &&
-	    (h_free->size == sizeof(debug_alloc_pool_aligned) - dah_overhead ||
-	     dah_first_call))
-		goto out;
-	if (!debug_kusage_one_time)
-		goto out;
-	debug_kusage_one_time = 0;
-	kdb_func_printf("debug_kmalloc memory leak dah_first %d\n", dah_first);
-	if (dah_first) {
-		h_used = (struct debug_alloc_header *)debug_alloc_pool;
-		kdb_func_printf("h_used %px size %d\n", h_used, h_used->size);
-	}
-	do {
-		h_used = (struct debug_alloc_header *)
-			  ((char *)h_free + dah_overhead + h_free->size);
-		kdb_func_printf("h_used %px size %d caller %px\n",
-				h_used, h_used->size, h_used->caller);
-		h_free = (struct debug_alloc_header *)
-			  (debug_alloc_pool + h_free->next);
-	} while (h_free->next);
-	h_used = (struct debug_alloc_header *)
-		  ((char *)h_free + dah_overhead + h_free->size);
-	if ((char *)h_used - debug_alloc_pool !=
-	    sizeof(debug_alloc_pool_aligned))
-		kdb_func_printf("h_used %px size %d caller %px\n",
-				h_used, h_used->size, h_used->caller);
-out:
-	spin_unlock(&dap_lock);
-}
-
 /* Maintain a small stack of kdb_flags to allow recursion without disturbing
  * the global kdb state.
  */
diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
index 9da76104f7a2..59857a1ee44c 100644
--- a/kernel/trace/trace_kdb.c
+++ b/kernel/trace/trace_kdb.c
@@ -147,11 +147,17 @@ static int kdb_ftdump(int argc, const char **argv)
 	return 0;
 }
 
+static kdbtab_t ftdump_cmd = {
+	.name = "ftdump",
+	.func = kdb_ftdump,
+	.usage = "[skip_#entries] [cpu]",
+	.help = "Dump ftrace log; -skip dumps last #entries",
+	.flags = KDB_ENABLE_ALWAYS_SAFE,
+};
+
 static __init int kdb_ftrace_register(void)
 {
-	kdb_register_flags("ftdump", kdb_ftdump, "[skip_#entries] [cpu]",
-			    "Dump ftrace log; -skip dumps last #entries", 0,
-			    KDB_ENABLE_ALWAYS_SAFE);
+	kdb_register(&ftdump_cmd);
 	return 0;
 }
 
diff --git a/samples/kdb/kdb_hello.c b/samples/kdb/kdb_hello.c
index c1c2fa0f62c2..82736e5a5e32 100644
--- a/samples/kdb/kdb_hello.c
+++ b/samples/kdb/kdb_hello.c
@@ -28,28 +28,26 @@ static int kdb_hello_cmd(int argc, const char **argv)
 	return 0;
 }
 
+static kdbtab_t hello_cmd = {
+	.name = "hello",
+	.func = kdb_hello_cmd,
+	.usage = "[string]",
+	.help = "Say Hello World or Hello [string]",
+};
 
 static int __init kdb_hello_cmd_init(void)
 {
 	/*
 	 * Registration of a dynamically added kdb command is done with
-	 * kdb_register() with the arguments being:
-	 *   1: The name of the shell command
-	 *   2: The function that processes the command
-	 *   3: Description of the usage of any arguments
-	 *   4: Descriptive text when you run help
-	 *   5: Number of characters to complete the command
-	 *      0 == type the whole command
-	 *      1 == match both "g" and "go" for example
+	 * kdb_register().
 	 */
-	kdb_register("hello", kdb_hello_cmd, "[string]",
-		     "Say Hello World or Hello [string]", 0);
+	kdb_register(&hello_cmd);
 	return 0;
 }
 
 static void __exit kdb_hello_cmd_exit(void)
 {
-	kdb_unregister("hello");
+	kdb_unregister(&hello_cmd);
 }
 
 module_init(kdb_hello_cmd_init);