kdb: Fix console handling when editing and tab-completing commands

commit db2f9c7dc29114f531df4a425d0867d01e1f1e28 upstream.

Currently, if the cursor position is not at the end of the command buffer
and the user uses the Tab-complete functions, then the console does not
leave the cursor in the correct position.

For example consider the following buffer with the cursor positioned
at the ^:

md kdb_pro 10
          ^

Pressing tab should result in:

md kdb_prompt_str 10
                 ^

However this does not happen. Instead the cursor is placed at the end
(after then 10) and further cursor movement redraws incorrectly. The
same problem exists when we double-Tab but in a different part of the
code.

Fix this by sending a carriage return and then redisplaying the text to
the left of the cursor.

Cc: stable@vger.kernel.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-3-f236dbe9828d@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 0f4b288185beb9c1e018d99a19ee074568123596..217124076c6c2bebc57ce8ae103b42178fa22e48 100644 (file)
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -370,6 +370,8 @@ poll_again:
                        kdb_printf("\n");
                        kdb_printf(kdb_prompt_str);
                        kdb_printf("%s", buffer);
+                       if (cp != lastchar)
+                               kdb_position_cursor(kdb_prompt_str, buffer, cp);
                } else if (tab != 2 && count > 0) {
                        /* How many new characters do we want from tmpbuffer? */
                        len_tmp = strlen(p_tmp) - len;
@@ -383,6 +385,9 @@ poll_again:
                                kdb_printf("%s", cp);
                                cp += len_tmp;
                                lastchar += len_tmp;
+                               if (cp != lastchar)
+                                       kdb_position_cursor(kdb_prompt_str,
+                                                           buffer, cp);
                        }
                }
                kdb_nextline = 1; /* reset output line number */