5 files changed, 227 insertions, 138 deletions

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 1adf62b39b96..07ce18ca71e0 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -27,6 +27,9 @@
  * version 2. This program is licensed "as is" without any warranty of any
  * kind, whether express or implied.
  */
+
+#define pr_fmt(fmt) "KGDB: " fmt
+
 #include <linux/pid_namespace.h>
 #include <linux/clocksource.h>
 #include <linux/serial_core.h>
@@ -196,8 +199,8 @@ int __weak kgdb_validate_break_address(unsigned long addr)
                 return err;
         err = kgdb_arch_remove_breakpoint(&tmp);
         if (err)
-                printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
-                   "memory destroyed at: %lx", addr);
+                pr_err("Critical breakpoint error, kernel memory destroyed at: %lx\n",
+                       addr);
         return err;
 }
 
@@ -256,8 +259,8 @@ int dbg_activate_sw_breakpoints(void)
                 error = kgdb_arch_set_breakpoint(&kgdb_break[i]);
                 if (error) {
                         ret = error;
-                        printk(KERN_INFO "KGDB: BP install failed: %lx",
-                               kgdb_break[i].bpt_addr);
+                        pr_info("BP install failed: %lx\n",
+                                kgdb_break[i].bpt_addr);
                         continue;
                 }
 
@@ -319,8 +322,8 @@ int dbg_deactivate_sw_breakpoints(void)
                         continue;
                 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
                 if (error) {
-                        printk(KERN_INFO "KGDB: BP remove failed: %lx\n",
-                               kgdb_break[i].bpt_addr);
+                        pr_info("BP remove failed: %lx\n",
+                                kgdb_break[i].bpt_addr);
                         ret = error;
                 }
 
@@ -367,7 +370,7 @@ int dbg_remove_all_break(void)
                         goto setundefined;
                 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
                 if (error)
-                        printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
+                        pr_err("breakpoint remove failed: %lx\n",
                                kgdb_break[i].bpt_addr);
 setundefined:
                 kgdb_break[i].state = BP_UNDEFINED;
@@ -400,9 +403,9 @@ static int kgdb_io_ready(int print_wait)
         if (print_wait) {
 #ifdef CONFIG_KGDB_KDB
                 if (!dbg_kdb_mode)
-                        printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
+                        pr_crit("waiting... or $3#33 for KDB\n");
 #else
-                printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
+                pr_crit("Waiting for remote debugger\n");
 #endif
         }
         return 1;
@@ -430,8 +433,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
                 exception_level = 0;
                 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
                 dbg_activate_sw_breakpoints();
-                printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
-                        addr);
+                pr_crit("re-enter error: breakpoint removed %lx\n", addr);
                 WARN_ON_ONCE(1);
 
                 return 1;
@@ -444,7 +446,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
                 panic("Recursive entry to debugger");
         }
 
-        printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
+        pr_crit("re-enter exception: ALL breakpoints killed\n");
 #ifdef CONFIG_KGDB_KDB
         /* Allow kdb to debug itself one level */
         return 0;
@@ -471,6 +473,7 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
         int cpu;
         int trace_on = 0;
         int online_cpus = num_online_cpus();
+        u64 time_left;
 
         kgdb_info[ks->cpu].enter_kgdb++;
         kgdb_info[ks->cpu].exception_state |= exception_state;
@@ -595,9 +598,13 @@ return_normal:
         /*
          * Wait for the other CPUs to be notified and be waiting for us:
          */
-        while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
-                                atomic_read(&slaves_in_kgdb)) != online_cpus)
+        time_left = loops_per_jiffy * HZ;
+        while (kgdb_do_roundup && --time_left &&
+               (atomic_read(&masters_in_kgdb) + atomic_read(&slaves_in_kgdb)) !=
+                   online_cpus)
                 cpu_relax();
+        if (!time_left)
+                pr_crit("KGDB: Timed out waiting for secondary CPUs.\n");
 
         /*
          * At this point the primary processor is completely
@@ -795,15 +802,15 @@ static struct console kgdbcons = {
 static void sysrq_handle_dbg(int key)
 {
         if (!dbg_io_ops) {
-                printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
+                pr_crit("ERROR: No KGDB I/O module available\n");
                 return;
         }
         if (!kgdb_connected) {
 #ifdef CONFIG_KGDB_KDB
                 if (!dbg_kdb_mode)
-                        printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
+                        pr_crit("KGDB or $3#33 for KDB\n");
 #else
-                printk(KERN_CRIT "Entering KGDB\n");
+                pr_crit("Entering KGDB\n");
 #endif
         }
 
@@ -945,7 +952,7 @@ static void kgdb_initial_breakpoint(void)
 {
         kgdb_break_asap = 0;
 
-        printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
+        pr_crit("Waiting for connection from remote gdb...\n");
         kgdb_breakpoint();
 }
 
@@ -964,8 +971,7 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
         if (dbg_io_ops) {
                 spin_unlock(&kgdb_registration_lock);
 
-                printk(KERN_ERR "kgdb: Another I/O driver is already "
-                                "registered with KGDB.\n");
+                pr_err("Another I/O driver is already registered with KGDB\n");
                 return -EBUSY;
         }
 
@@ -981,8 +987,7 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
 
         spin_unlock(&kgdb_registration_lock);
 
-        printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
-               new_dbg_io_ops->name);
+        pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name);
 
         /* Arm KGDB now. */
         kgdb_register_callbacks();
@@ -1017,8 +1022,7 @@ void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
 
         spin_unlock(&kgdb_registration_lock);
 
-        printk(KERN_INFO
-                "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
+        pr_info("Unregistered I/O driver %s, debugger disabled\n",
                 old_dbg_io_ops->name);
 }
 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
diff --git a/kernel/debug/kdb/kdb_bp.c b/kernel/debug/kdb/kdb_bp.c
index b20d544f20c2..e1dbf4a2c69e 100644
--- a/kernel/debug/kdb/kdb_bp.c
+++ b/kernel/debug/kdb/kdb_bp.c
@@ -531,22 +531,29 @@ void __init kdb_initbptab(void)
         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++)
                 bp->bp_free = 1;
 
-        kdb_register_repeat("bp", kdb_bp, "[<vaddr>]",
-                "Set/Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
-        kdb_register_repeat("bl", kdb_bp, "[<vaddr>]",
-                "Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("bp", kdb_bp, "[<vaddr>]",
+                "Set/Display breakpoints", 0,
+                KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("bl", kdb_bp, "[<vaddr>]",
+                "Display breakpoints", 0,
+                KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
         if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)
-                kdb_register_repeat("bph", kdb_bp, "[<vaddr>]",
-                "[datar [length]|dataw [length]]   Set hw brk", 0, KDB_REPEAT_NO_ARGS);
-        kdb_register_repeat("bc", kdb_bc, "<bpnum>",
-                "Clear Breakpoint", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("be", kdb_bc, "<bpnum>",
-                "Enable Breakpoint", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("bd", kdb_bc, "<bpnum>",
-                "Disable Breakpoint", 0, KDB_REPEAT_NONE);
-
-        kdb_register_repeat("ss", kdb_ss, "",
-                "Single Step", 1, KDB_REPEAT_NO_ARGS);
+                kdb_register_flags("bph", kdb_bp, "[<vaddr>]",
+                "[datar [length]|dataw [length]]   Set hw brk", 0,
+                KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("bc", kdb_bc, "<bpnum>",
+                "Clear Breakpoint", 0,
+                KDB_ENABLE_FLOW_CTRL);
+        kdb_register_flags("be", kdb_bc, "<bpnum>",
+                "Enable Breakpoint", 0,
+                KDB_ENABLE_FLOW_CTRL);
+        kdb_register_flags("bd", kdb_bc, "<bpnum>",
+                "Disable Breakpoint", 0,
+                KDB_ENABLE_FLOW_CTRL);
+
+        kdb_register_flags("ss", kdb_ss, "",
+                "Single Step", 1,
+                KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
         /*
          * Architecture dependent initialization.
          */
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index 8859ca34dcfe..15e1a7af5dd0 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -129,6 +129,10 @@ int kdb_stub(struct kgdb_state *ks)
                 ks->pass_exception = 1;
                 KDB_FLAG_SET(CATASTROPHIC);
         }
+        /* set CATASTROPHIC if the system contains unresponsive processors */
+        for_each_online_cpu(i)
+                if (!kgdb_info[i].enter_kgdb)
+                        KDB_FLAG_SET(CATASTROPHIC);
         if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
                 KDB_STATE_CLEAR(SSBPT);
                 KDB_STATE_CLEAR(DOING_SS);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 379650b984f8..7b40c5f07dce 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -12,6 +12,7 @@
  */
 
 #include <linux/ctype.h>
+#include <linux/types.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/kmsg_dump.h>
@@ -23,6 +24,7 @@
 #include <linux/vmalloc.h>
 #include <linux/atomic.h>
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/kallsyms.h>
@@ -42,6 +44,12 @@
 #include <linux/slab.h>
 #include "kdb_private.h"
 
+#undef  MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX "kdb."
+
+static int kdb_cmd_enabled = CONFIG_KDB_DEFAULT_ENABLE;
+module_param_named(cmd_enable, kdb_cmd_enabled, int, 0600);
+
 #define GREP_LEN 256
 char kdb_grep_string[GREP_LEN];
 int kdb_grepping_flag;
@@ -121,6 +129,7 @@ static kdbmsg_t kdbmsgs[] = {
         KDBMSG(BADLENGTH, "Invalid length field"),
         KDBMSG(NOBP, "No Breakpoint exists"),
         KDBMSG(BADADDR, "Invalid address"),
+        KDBMSG(NOPERM, "Permission denied"),
 };
 #undef KDBMSG
 
@@ -188,6 +197,26 @@ struct task_struct *kdb_curr_task(int cpu)
 }
 
 /*
+ * Check whether the flags of the current command and the permissions
+ * of the kdb console has allow a command to be run.
+ */
+static inline bool kdb_check_flags(kdb_cmdflags_t flags, int permissions,
+                                   bool no_args)
+{
+        /* permissions comes from userspace so needs massaging slightly */
+        permissions &= KDB_ENABLE_MASK;
+        permissions |= KDB_ENABLE_ALWAYS_SAFE;
+
+        /* some commands change group when launched with no arguments */
+        if (no_args)
+                permissions |= permissions << KDB_ENABLE_NO_ARGS_SHIFT;
+
+        flags |= KDB_ENABLE_ALL;
+
+        return permissions & flags;
+}
+
+/*
  * kdbgetenv - This function will return the character string value of
  *      an environment variable.
  * Parameters:
@@ -476,6 +505,15 @@ int kdbgetaddrarg(int argc, const char **argv, int *nextarg,
         kdb_symtab_t symtab;
 
         /*
+         * If the enable flags prohibit both arbitrary memory access
+         * and flow control then there are no reasonable grounds to
+         * provide symbol lookup.
+         */
+        if (!kdb_check_flags(KDB_ENABLE_MEM_READ | KDB_ENABLE_FLOW_CTRL,
+                             kdb_cmd_enabled, false))
+                return KDB_NOPERM;
+
+        /*
          * Process arguments which follow the following syntax:
          *
          *  symbol | numeric-address [+/- numeric-offset]
@@ -641,8 +679,13 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
                 if (!s->count)
                         s->usable = 0;
                 if (s->usable)
-                        kdb_register(s->name, kdb_exec_defcmd,
-                                     s->usage, s->help, 0);
+                        /* 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);
                 return 0;
         }
         if (!s->usable)
@@ -1003,25 +1046,22 @@ int kdb_parse(const char *cmdstr)
 
         if (i < kdb_max_commands) {
                 int result;
+
+                if (!kdb_check_flags(tp->cmd_flags, kdb_cmd_enabled, argc <= 1))
+                        return KDB_NOPERM;
+
                 KDB_STATE_SET(CMD);
                 result = (*tp->cmd_func)(argc-1, (const char **)argv);
                 if (result && ignore_errors && result > KDB_CMD_GO)
                         result = 0;
                 KDB_STATE_CLEAR(CMD);
-                switch (tp->cmd_repeat) {
-                case KDB_REPEAT_NONE:
-                        argc = 0;
-                        if (argv[0])
-                                *(argv[0]) = '\0';
-                        break;
-                case KDB_REPEAT_NO_ARGS:
-                        argc = 1;
-                        if (argv[1])
-                                *(argv[1]) = '\0';
-                        break;
-                case KDB_REPEAT_WITH_ARGS:
-                        break;
-                }
+
+                if (tp->cmd_flags & KDB_REPEAT_WITH_ARGS)
+                        return result;
+
+                argc = tp->cmd_flags & KDB_REPEAT_NO_ARGS ? 1 : 0;
+                if (argv[argc])
+                        *(argv[argc]) = '\0';
                 return result;
         }
 
@@ -1921,10 +1961,14 @@ static int kdb_rm(int argc, const char **argv)
  */
 static int kdb_sr(int argc, const char **argv)
 {
+        bool check_mask =
+            !kdb_check_flags(KDB_ENABLE_ALL, kdb_cmd_enabled, false);
+
         if (argc != 1)
                 return KDB_ARGCOUNT;
+
         kdb_trap_printk++;
-        __handle_sysrq(*argv[1], false);
+        __handle_sysrq(*argv[1], check_mask);
         kdb_trap_printk--;
 
         return 0;
@@ -1979,7 +2023,7 @@ static int kdb_lsmod(int argc, const char **argv)
                 kdb_printf("%-20s%8u  0x%p ", mod->name,
                            mod->core_size, (void *)mod);
 #ifdef CONFIG_MODULE_UNLOAD
-                kdb_printf("%4ld ", module_refcount(mod));
+                kdb_printf("%4d ", module_refcount(mod));
 #endif
                 if (mod->state == MODULE_STATE_GOING)
                         kdb_printf(" (Unloading)");
@@ -2157,6 +2201,8 @@ static void kdb_cpu_status(void)
         for (start_cpu = -1, i = 0; i < NR_CPUS; i++) {
                 if (!cpu_online(i)) {
                         state = 'F';    /* cpu is offline */
+                } else if (!kgdb_info[i].enter_kgdb) {
+                        state = 'D';    /* cpu is online but unresponsive */
                 } else {
                         state = ' ';    /* cpu is responding to kdb */
                         if (kdb_task_state_char(KDB_TSK(i)) == 'I')
@@ -2210,7 +2256,7 @@ static int kdb_cpu(int argc, const char **argv)
         /*
          * Validate cpunum
          */
-        if ((cpunum > NR_CPUS) || !cpu_online(cpunum))
+        if ((cpunum > NR_CPUS) || !kgdb_info[cpunum].enter_kgdb)
                 return KDB_BADCPUNUM;
 
         dbg_switch_cpu = cpunum;
@@ -2375,6 +2421,8 @@ static int kdb_help(int argc, const char **argv)
                         return 0;
                 if (!kt->cmd_name)
                         continue;
+                if (!kdb_check_flags(kt->cmd_flags, kdb_cmd_enabled, true))
+                        continue;
                 if (strlen(kt->cmd_usage) > 20)
                         space = "\n                                    ";
                 kdb_printf("%-15.15s %-20s%s%s\n", kt->cmd_name,
@@ -2629,7 +2677,7 @@ static int kdb_grep_help(int argc, const char **argv)
 }
 
 /*
- * kdb_register_repeat - This function is used to register a kernel
+ * kdb_register_flags - This function is used to register a kernel
  *      debugger command.
  * Inputs:
  *      cmd     Command name
@@ -2641,12 +2689,12 @@ static int kdb_grep_help(int argc, const char **argv)
  *      zero for success, one if a duplicate command.
  */
 #define kdb_command_extend 50   /* arbitrary */
-int kdb_register_repeat(char *cmd,
-                        kdb_func_t func,
-                        char *usage,
-                        char *help,
-                        short minlen,
-                        kdb_repeat_t repeat)
+int kdb_register_flags(char *cmd,
+                       kdb_func_t func,
+                       char *usage,
+                       char *help,
+                       short minlen,
+                       kdb_cmdflags_t flags)
 {
         int i;
         kdbtab_t *kp;
@@ -2694,19 +2742,18 @@ int kdb_register_repeat(char *cmd,
         kp->cmd_func   = func;
         kp->cmd_usage  = usage;
         kp->cmd_help   = help;
-        kp->cmd_flags  = 0;
         kp->cmd_minlen = minlen;
-        kp->cmd_repeat = repeat;
+        kp->cmd_flags  = flags;
 
         return 0;
 }
-EXPORT_SYMBOL_GPL(kdb_register_repeat);
+EXPORT_SYMBOL_GPL(kdb_register_flags);
 
 
 /*
  * kdb_register - Compatibility register function for commands that do
  *      not need to specify a repeat state.  Equivalent to
- *      kdb_register_repeat with KDB_REPEAT_NONE.
+ *      kdb_register_flags with flags set to 0.
  * Inputs:
  *      cmd     Command name
  *      func    Function to execute the command
@@ -2721,8 +2768,7 @@ int kdb_register(char *cmd,
              char *help,
              short minlen)
 {
-        return kdb_register_repeat(cmd, func, usage, help, minlen,
-                                   KDB_REPEAT_NONE);
+        return kdb_register_flags(cmd, func, usage, help, minlen, 0);
 }
 EXPORT_SYMBOL_GPL(kdb_register);
 
@@ -2764,80 +2810,109 @@ static void __init kdb_inittab(void)
         for_each_kdbcmd(kp, i)
                 kp->cmd_name = NULL;
 
-        kdb_register_repeat("md", kdb_md, "<vaddr>",
+        kdb_register_flags("md", kdb_md, "<vaddr>",
           "Display Memory Contents, also mdWcN, e.g. md8c1", 1,
-                            KDB_REPEAT_NO_ARGS);
-        kdb_register_repeat("mdr", kdb_md, "<vaddr> <bytes>",
-          "Display Raw Memory", 0, KDB_REPEAT_NO_ARGS);
-        kdb_register_repeat("mdp", kdb_md, "<paddr> <bytes>",
-          "Display Physical Memory", 0, KDB_REPEAT_NO_ARGS);
-        kdb_register_repeat("mds", kdb_md, "<vaddr>",
-          "Display Memory Symbolically", 0, KDB_REPEAT_NO_ARGS);
-        kdb_register_repeat("mm", kdb_mm, "<vaddr> <contents>",
-          "Modify Memory Contents", 0, KDB_REPEAT_NO_ARGS);
-        kdb_register_repeat("go", kdb_go, "[<vaddr>]",
-          "Continue Execution", 1, KDB_REPEAT_NONE);
-        kdb_register_repeat("rd", kdb_rd, "",
-          "Display Registers", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("rm", kdb_rm, "<reg> <contents>",
-          "Modify Registers", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("ef", kdb_ef, "<vaddr>",
-          "Display exception frame", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("bt", kdb_bt, "[<vaddr>]",
-          "Stack traceback", 1, KDB_REPEAT_NONE);
-        kdb_register_repeat("btp", kdb_bt, "<pid>",
-          "Display stack for process <pid>", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("bta", kdb_bt, "[D|R|S|T|C|Z|E|U|I|M|A]",
-          "Backtrace all processes matching state flag", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("btc", kdb_bt, "",
-          "Backtrace current process on each cpu", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("btt", kdb_bt, "<vaddr>",
+          KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("mdr", kdb_md, "<vaddr> <bytes>",
+          "Display Raw Memory", 0,
+          KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("mdp", kdb_md, "<paddr> <bytes>",
+          "Display Physical Memory", 0,
+          KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("mds", kdb_md, "<vaddr>",
+          "Display Memory Symbolically", 0,
+          KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("mm", kdb_mm, "<vaddr> <contents>",
+          "Modify Memory Contents", 0,
+          KDB_ENABLE_MEM_WRITE | KDB_REPEAT_NO_ARGS);
+        kdb_register_flags("go", kdb_go, "[<vaddr>]",
+          "Continue Execution", 1,
+          KDB_ENABLE_REG_WRITE | KDB_ENABLE_ALWAYS_SAFE_NO_ARGS);
+        kdb_register_flags("rd", kdb_rd, "",
+          "Display Registers", 0,
+          KDB_ENABLE_REG_READ);
+        kdb_register_flags("rm", kdb_rm, "<reg> <contents>",
+          "Modify Registers", 0,
+          KDB_ENABLE_REG_WRITE);
+        kdb_register_flags("ef", kdb_ef, "<vaddr>",
+          "Display exception frame", 0,
+          KDB_ENABLE_MEM_READ);
+        kdb_register_flags("bt", kdb_bt, "[<vaddr>]",
+          "Stack traceback", 1,
+          KDB_ENABLE_MEM_READ | KDB_ENABLE_INSPECT_NO_ARGS);
+        kdb_register_flags("btp", kdb_bt, "<pid>",
+          "Display stack for process <pid>", 0,
+          KDB_ENABLE_INSPECT);
+        kdb_register_flags("bta", kdb_bt, "[D|R|S|T|C|Z|E|U|I|M|A]",
+          "Backtrace all processes matching state flag", 0,
+          KDB_ENABLE_INSPECT);
+        kdb_register_flags("btc", kdb_bt, "",
+          "Backtrace current process on each cpu", 0,
+          KDB_ENABLE_INSPECT);
+        kdb_register_flags("btt", kdb_bt, "<vaddr>",
           "Backtrace process given its struct task address", 0,
-                            KDB_REPEAT_NONE);
-        kdb_register_repeat("env", kdb_env, "",
-          "Show environment variables", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("set", kdb_set, "",
-          "Set environment variables", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("help", kdb_help, "",
-          "Display Help Message", 1, KDB_REPEAT_NONE);
-        kdb_register_repeat("?", kdb_help, "",
-          "Display Help Message", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("cpu", kdb_cpu, "<cpunum>",
-          "Switch to new cpu", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("kgdb", kdb_kgdb, "",
-          "Enter kgdb mode", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("ps", kdb_ps, "[<flags>|A]",
-          "Display active task list", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("pid", kdb_pid, "<pidnum>",
-          "Switch to another task", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("reboot", kdb_reboot, "",
-          "Reboot the machine immediately", 0, KDB_REPEAT_NONE);
+          KDB_ENABLE_MEM_READ | KDB_ENABLE_INSPECT_NO_ARGS);
+        kdb_register_flags("env", kdb_env, "",
+          "Show environment variables", 0,
+          KDB_ENABLE_ALWAYS_SAFE);
+        kdb_register_flags("set", kdb_set, "",
+          "Set environment variables", 0,
+          KDB_ENABLE_ALWAYS_SAFE);
+        kdb_register_flags("help", kdb_help, "",
+          "Display Help Message", 1,
+          KDB_ENABLE_ALWAYS_SAFE);
+        kdb_register_flags("?", kdb_help, "",
+          "Display Help Message", 0,
+          KDB_ENABLE_ALWAYS_SAFE);
+        kdb_register_flags("cpu", kdb_cpu, "<cpunum>",
+          "Switch to new cpu", 0,
+          KDB_ENABLE_ALWAYS_SAFE_NO_ARGS);
+        kdb_register_flags("kgdb", kdb_kgdb, "",
+          "Enter kgdb mode", 0, 0);
+        kdb_register_flags("ps", kdb_ps, "[<flags>|A]",
+          "Display active task list", 0,
+          KDB_ENABLE_INSPECT);
+        kdb_register_flags("pid", kdb_pid, "<pidnum>",
+          "Switch to another task", 0,
+          KDB_ENABLE_INSPECT);
+        kdb_register_flags("reboot", kdb_reboot, "",
+          "Reboot the machine immediately", 0,
+          KDB_ENABLE_REBOOT);
 #if defined(CONFIG_MODULES)
-        kdb_register_repeat("lsmod", kdb_lsmod, "",
-          "List loaded kernel modules", 0, KDB_REPEAT_NONE);
+        kdb_register_flags("lsmod", kdb_lsmod, "",
+          "List loaded kernel modules", 0,
+          KDB_ENABLE_INSPECT);
 #endif
 #if defined(CONFIG_MAGIC_SYSRQ)
-        kdb_register_repeat("sr", kdb_sr, "<key>",
-          "Magic SysRq key", 0, KDB_REPEAT_NONE);
+        kdb_register_flags("sr", kdb_sr, "<key>",
+          "Magic SysRq key", 0,
+          KDB_ENABLE_ALWAYS_SAFE);
 #endif
 #if defined(CONFIG_PRINTK)
-        kdb_register_repeat("dmesg", kdb_dmesg, "[lines]",
-          "Display syslog buffer", 0, KDB_REPEAT_NONE);
+        kdb_register_flags("dmesg", kdb_dmesg, "[lines]",
+          "Display syslog buffer", 0,
+          KDB_ENABLE_ALWAYS_SAFE);
 #endif
         if (arch_kgdb_ops.enable_nmi) {
-                kdb_register_repeat("disable_nmi", kdb_disable_nmi, "",
-                  "Disable NMI entry to KDB", 0, KDB_REPEAT_NONE);
-        }
-        kdb_register_repeat("defcmd", kdb_defcmd, "name \"usage\" \"help\"",
-          "Define a set of commands, down to endefcmd", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("kill", kdb_kill, "<-signal> <pid>",
-          "Send a signal to a process", 0, KDB_REPEAT_NONE);
-        kdb_register_repeat("summary", kdb_summary, "",
-          "Summarize the system", 4, KDB_REPEAT_NONE);
-        kdb_register_repeat("per_cpu", kdb_per_cpu, "<sym> [<bytes>] [<cpu>]",
-          "Display per_cpu variables", 3, KDB_REPEAT_NONE);
-        kdb_register_repeat("grephelp", kdb_grep_help, "",
-          "Display help on | grep", 0, KDB_REPEAT_NONE);
+                kdb_register_flags("disable_nmi", kdb_disable_nmi, "",
+                  "Disable NMI entry to KDB", 0,
+                  KDB_ENABLE_ALWAYS_SAFE);
+        }
+        kdb_register_flags("defcmd", kdb_defcmd, "name \"usage\" \"help\"",
+          "Define a set of commands, down to endefcmd", 0,
+          KDB_ENABLE_ALWAYS_SAFE);
+        kdb_register_flags("kill", kdb_kill, "<-signal> <pid>",
+          "Send a signal to a process", 0,
+          KDB_ENABLE_SIGNAL);
+        kdb_register_flags("summary", kdb_summary, "",
+          "Summarize the system", 4,
+          KDB_ENABLE_ALWAYS_SAFE);
+        kdb_register_flags("per_cpu", kdb_per_cpu, "<sym> [<bytes>] [<cpu>]",
+          "Display per_cpu variables", 3,
+          KDB_ENABLE_MEM_READ);
+        kdb_register_flags("grephelp", kdb_grep_help, "",
+          "Display help on | grep", 0,
+          KDB_ENABLE_ALWAYS_SAFE);
 }
 
 /* Execute any commands defined in kdb_cmds.  */
diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index 7afd3c8c41d5..eaacd1693954 100644
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -172,10 +172,9 @@ typedef struct _kdbtab {
         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_flags;             /* Parsing flags */
         short    cmd_minlen;            /* Minimum legal # command
                                          * chars required */
-        kdb_repeat_t cmd_repeat;        /* Does command auto repeat on enter? */
+        kdb_cmdflags_t cmd_flags;       /* Command behaviour flags */
 } kdbtab_t;
 
 extern int kdb_bt(int, const char **);  /* KDB display back trace */