kdb: Prevent kernel oops with kdb_defcmd

The kdb_defcmd can only be used to display the available command aliases
while using the kernel debug shell.  If you try to define a new macro
while the kernel debugger is active it will oops.  The debug shell
macros must use pre-allocated memory set aside at the time kdb_init()
is run, and the kdb_defcmd is restricted to only working at the time
that the kdb_init sequence is being run, which only occurs if you
actually activate the kernel debugger.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index cdfc0a7e583e9351890b765f4dc44a6cdcfcfca0..496f596aa80748c401b091522b13b181079b6d96 100644 (file)
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -681,6 +681,10 @@ static int kdb_defcmd(int argc, const char **argv)
        }
        if (argc != 3)
                return KDB_ARGCOUNT;
+       if (in_dbg_master()) {
+               kdb_printf("Command only available during kdb_init()\n");
+               return KDB_NOTIMP;
+       }
        defcmd_set = kmalloc((defcmd_set_count + 1) * sizeof(*defcmd_set),
                             GFP_KDB);
        if (!defcmd_set)
@@ -2796,8 +2800,8 @@ static void __init kdb_inittab(void)
          "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, "[DRSTCZEUIMA]",
-         "Display stack all processes", 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>",