repair gdbstub to match the gdbserial protocol specification

commit fb82c0ff27b2c40c6f7a3d1a94cafb154591fa80 upstream.

The gdbserial protocol handler should return an empty packet instead
of an error string when ever it responds to a command it does not
implement.

The problem cases come from a debugger client sending
qTBuffer, qTStatus, qSearch, qSupported.

The incorrect response from the gdbstub leads the debugger clients to
not function correctly.  Recent versions of gdb will not detach correctly as a result of this behavior.

Backport-request-by: Frank Pan <frankpzh@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 9147a3190c9d9b947dcbb9fe9c8e5c2dbb67c483..53dae4b215af8a6be07583efe0399ec436713000 100644 (file)
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -1001,10 +1001,8 @@ static void gdb_cmd_query(struct kgdb_state *ks)
        switch (remcom_in_buffer[1]) {
        case 's':
        case 'f':
-               if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
-                       error_packet(remcom_out_buffer, -EINVAL);
+               if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
                        break;
-               }
 
                i = 0;
                remcom_out_buffer[0] = 'm';
@@ -1045,10 +1043,9 @@ static void gdb_cmd_query(struct kgdb_state *ks)
                pack_threadid(remcom_out_buffer + 2, thref);
                break;
        case 'T':
-               if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
-                       error_packet(remcom_out_buffer, -EINVAL);
+               if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
                        break;
-               }
+
                ks->threadid = 0;
                ptr = remcom_in_buffer + 17;
                kgdb_hex2long(&ptr, &ks->threadid);