* Copyright (C) 2009 Jason Wessel <jason.wessel@windriver.com>
  */
 
+/* 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
+ * with an argument.
+ */
+#define KDB_ENABLE_NO_ARGS_SHIFT 10
+
 typedef enum {
-       KDB_REPEAT_NO_ARGS      = 0x1, /* Repeat the command w/o arguments */
-       KDB_REPEAT_WITH_ARGS    = 0x2, /* Repeat the command w/ its arguments */
+       KDB_ENABLE_ALL = (1 << 0), /* Enable everything */
+       KDB_ENABLE_MEM_READ = (1 << 1),
+       KDB_ENABLE_MEM_WRITE = (1 << 2),
+       KDB_ENABLE_REG_READ = (1 << 3),
+       KDB_ENABLE_REG_WRITE = (1 << 4),
+       KDB_ENABLE_INSPECT = (1 << 5),
+       KDB_ENABLE_FLOW_CTRL = (1 << 6),
+       KDB_ENABLE_SIGNAL = (1 << 7),
+       KDB_ENABLE_REBOOT = (1 << 8),
+       /* User exposed values stop here, all remaining flags are
+        * exclusively used to describe a commands behaviour.
+        */
+
+       KDB_ENABLE_ALWAYS_SAFE = (1 << 9),
+       KDB_ENABLE_MASK = (1 << KDB_ENABLE_NO_ARGS_SHIFT) - 1,
+
+       KDB_ENABLE_ALL_NO_ARGS = KDB_ENABLE_ALL << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_MEM_READ_NO_ARGS = KDB_ENABLE_MEM_READ
+                                     << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_MEM_WRITE_NO_ARGS = KDB_ENABLE_MEM_WRITE
+                                      << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_REG_READ_NO_ARGS = KDB_ENABLE_REG_READ
+                                     << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_REG_WRITE_NO_ARGS = KDB_ENABLE_REG_WRITE
+                                      << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_INSPECT_NO_ARGS = KDB_ENABLE_INSPECT
+                                    << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_FLOW_CTRL_NO_ARGS = KDB_ENABLE_FLOW_CTRL
+                                      << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_SIGNAL_NO_ARGS = KDB_ENABLE_SIGNAL
+                                   << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_REBOOT_NO_ARGS = KDB_ENABLE_REBOOT
+                                   << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_ALWAYS_SAFE_NO_ARGS = KDB_ENABLE_ALWAYS_SAFE
+                                        << KDB_ENABLE_NO_ARGS_SHIFT,
+       KDB_ENABLE_MASK_NO_ARGS = KDB_ENABLE_MASK << KDB_ENABLE_NO_ARGS_SHIFT,
+
+       KDB_REPEAT_NO_ARGS = 0x40000000, /* Repeat the command w/o arguments */
+       KDB_REPEAT_WITH_ARGS = 0x80000000, /* Repeat the command with args */
 } kdb_cmdflags_t;
 
 typedef int (*kdb_func_t)(int, const char **);
 
        return p;
 }
 
+/*
+ * 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.
                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)
 
        kdb_register_flags("md", kdb_md, "<vaddr>",
          "Display Memory Contents, also mdWcN, e.g. md8c1", 1,
-                           KDB_REPEAT_NO_ARGS);
+         KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS);
        kdb_register_flags("mdr", kdb_md, "<vaddr> <bytes>",
-         "Display Raw Memory", 0, KDB_REPEAT_NO_ARGS);
+         "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_REPEAT_NO_ARGS);
+         "Display Physical Memory", 0,
+         KDB_ENABLE_MEM_READ | KDB_REPEAT_NO_ARGS);
        kdb_register_flags("mds", kdb_md, "<vaddr>",
-         "Display Memory Symbolically", 0, KDB_REPEAT_NO_ARGS);
+         "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_REPEAT_NO_ARGS);
+         "Modify Memory Contents", 0,
+         KDB_ENABLE_MEM_WRITE | KDB_REPEAT_NO_ARGS);
        kdb_register_flags("go", kdb_go, "[<vaddr>]",
-         "Continue Execution", 1, 0);
+         "Continue Execution", 1,
+         KDB_ENABLE_REG_WRITE | KDB_ENABLE_ALWAYS_SAFE_NO_ARGS);
        kdb_register_flags("rd", kdb_rd, "",
-         "Display Registers", 0, 0);
+         "Display Registers", 0,
+         KDB_ENABLE_REG_READ);
        kdb_register_flags("rm", kdb_rm, "<reg> <contents>",
-         "Modify Registers", 0, 0);
+         "Modify Registers", 0,
+         KDB_ENABLE_REG_WRITE);
        kdb_register_flags("ef", kdb_ef, "<vaddr>",
-         "Display exception frame", 0, 0);
+         "Display exception frame", 0,
+         KDB_ENABLE_MEM_READ);
        kdb_register_flags("bt", kdb_bt, "[<vaddr>]",
-         "Stack traceback", 1, 0);
+         "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, 0);
+         "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, 0);
+         "Backtrace all processes matching state flag", 0,
+         KDB_ENABLE_INSPECT);
        kdb_register_flags("btc", kdb_bt, "",
-         "Backtrace current process on each cpu", 0, 0);
+         "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,
-                           0);
+         KDB_ENABLE_MEM_READ | KDB_ENABLE_INSPECT_NO_ARGS);
        kdb_register_flags("env", kdb_env, "",
-         "Show environment variables", 0, 0);
+         "Show environment variables", 0,
+         KDB_ENABLE_ALWAYS_SAFE);
        kdb_register_flags("set", kdb_set, "",
-         "Set environment variables", 0, 0);
+         "Set environment variables", 0,
+         KDB_ENABLE_ALWAYS_SAFE);
        kdb_register_flags("help", kdb_help, "",
-         "Display Help Message", 1, 0);
+         "Display Help Message", 1,
+         KDB_ENABLE_ALWAYS_SAFE);
        kdb_register_flags("?", kdb_help, "",
-         "Display Help Message", 0, 0);
+         "Display Help Message", 0,
+         KDB_ENABLE_ALWAYS_SAFE);
        kdb_register_flags("cpu", kdb_cpu, "<cpunum>",
-         "Switch to new cpu", 0, 0);
+         "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, 0);
+         "Display active task list", 0,
+         KDB_ENABLE_INSPECT);
        kdb_register_flags("pid", kdb_pid, "<pidnum>",
-         "Switch to another task", 0, 0);
+         "Switch to another task", 0,
+         KDB_ENABLE_INSPECT);
        kdb_register_flags("reboot", kdb_reboot, "",
-         "Reboot the machine immediately", 0, 0);
+         "Reboot the machine immediately", 0,
+         KDB_ENABLE_REBOOT);
 #if defined(CONFIG_MODULES)
        kdb_register_flags("lsmod", kdb_lsmod, "",
-         "List loaded kernel modules", 0, 0);
+         "List loaded kernel modules", 0,
+         KDB_ENABLE_INSPECT);
 #endif
 #if defined(CONFIG_MAGIC_SYSRQ)
        kdb_register_flags("sr", kdb_sr, "<key>",
-         "Magic SysRq key", 0, 0);
+         "Magic SysRq key", 0,
+         KDB_ENABLE_ALWAYS_SAFE);
 #endif
 #if defined(CONFIG_PRINTK)
        kdb_register_flags("dmesg", kdb_dmesg, "[lines]",
-         "Display syslog buffer", 0, 0);
+         "Display syslog buffer", 0,
+         KDB_ENABLE_ALWAYS_SAFE);
 #endif
        if (arch_kgdb_ops.enable_nmi) {
                kdb_register_flags("disable_nmi", kdb_disable_nmi, "",
-                 "Disable NMI entry to KDB", 0, 0);
+                 "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, 0);
+         "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, 0);
+         "Send a signal to a process", 0,
+         KDB_ENABLE_SIGNAL);
        kdb_register_flags("summary", kdb_summary, "",
-         "Summarize the system", 4, 0);
+         "Summarize the system", 4,
+         KDB_ENABLE_ALWAYS_SAFE);
        kdb_register_flags("per_cpu", kdb_per_cpu, "<sym> [<bytes>] [<cpu>]",
-         "Display per_cpu variables", 3, 0);
+         "Display per_cpu variables", 3,
+         KDB_ENABLE_MEM_READ);
        kdb_register_flags("grephelp", kdb_grep_help, "",
-         "Display help on | grep", 0, 0);
+         "Display help on | grep", 0,
+         KDB_ENABLE_ALWAYS_SAFE);
 }
 
 /* Execute any commands defined in kdb_cmds.  */