kdb,kgdb: Implement switch and pass buffer from kdb -> gdb

When switching from kdb mode to kgdb mode packets were getting lost
depending on the size of the fifo queue of the serial chip.  When gdb
initially connects if it is in kdb mode it should entirely send any
character buffer over to the gdbstub when switching connections.

Previously kdb was zero'ing out the character buffer and this could
lead to gdb failing to connect at all, or a lengthy pause could occur
on the initial connect.

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

1 files changed, 7 insertions, 10 deletions

diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index dd0b1b7dd02..fe422d27578 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -30,6 +30,8 @@ EXPORT_SYMBOL_GPL(kdb_poll_funcs);
 int kdb_poll_idx = 1;
 EXPORT_SYMBOL_GPL(kdb_poll_idx);
 
+static struct kgdb_state *kdb_ks;
+
 int kdb_stub(struct kgdb_state *ks)
 {
         int error = 0;
@@ -39,6 +41,7 @@ int kdb_stub(struct kgdb_state *ks)
         kdb_dbtrap_t db_result = KDB_DB_NOBPT;
         int i;
 
+        kdb_ks = ks;
         if (KDB_STATE(REENTRY)) {
                 reason = KDB_REASON_SWITCH;
                 KDB_STATE_CLEAR(REENTRY);
@@ -124,16 +127,6 @@ int kdb_stub(struct kgdb_state *ks)
         kdbnearsym_cleanup();
         if (error == KDB_CMD_KGDB) {
                 if (KDB_STATE(DOING_KGDB) || KDB_STATE(DOING_KGDB2)) {
-        /*
-         * This inteface glue which allows kdb to transition in into
-         * the gdb stub.  In order to do this the '?' or '' gdb serial
-         * packet response is processed here.  And then control is
-         * passed to the gdbstub.
-         */
-                        if (KDB_STATE(DOING_KGDB))
-                                gdbstub_state(ks, "?");
-                        else
-                                gdbstub_state(ks, "");
                         KDB_STATE_CLEAR(DOING_KGDB);
                         KDB_STATE_CLEAR(DOING_KGDB2);
                 }
@@ -166,3 +159,7 @@ int kdb_stub(struct kgdb_state *ks)
         return kgdb_info[ks->cpu].ret_state;
 }
 
+void kdb_gdb_state_pass(char *buf)
+{
+        gdbstub_state(kdb_ks, buf);
+}