linux-kernel - [PATCH] kdb: fix ctrl+e/a/f/b/d/p/n broken in keyboard mode

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Message-ID: <20241108221116.GA123748@lichtman.org>
Date: Fri, 8 Nov 2024 22:11:16 +0000
From: Nir Lichtman <nir@...htman.org>
To: jason.wessel@...driver.com, daniel.thompson@...aro.org,
	dianders@...omium.org, linux-kernel@...r.kernel.org
Subject: [PATCH] kdb: fix ctrl+e/a/f/b/d/p/n broken in keyboard mode

Problem: When using KDB via keyboard it does not react to control
characters which are supported in serial mode.

Example: Chords such as CTRL+A/E/D/P do not work in keyboard mode

Solution: Before disregarding a non-printable key character, check if it
is one of the supported control characters, I have took the control
characters from the switch case upwards in this function that translates
scan codes of arrow keys/backspace/home/.. to the control characters.
I have took them all besides the TAB control character translation (I am
not sure what that maps to on the keyboard)

---
 kernel/debug/kdb/kdb_keyboard.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/debug/kdb/kdb_keyboard.c b/kernel/debug/kdb/kdb_keyboard.c
index 3c2987f46f6e..2c004abd5375 100644
--- a/kernel/debug/kdb/kdb_keyboard.c
+++ b/kernel/debug/kdb/kdb_keyboard.c
@@ -172,6 +172,9 @@ int kdb_get_kbd_char(void)
 	switch (KTYP(keychar)) {
 	case KT_LETTER:
 	case KT_LATIN:
+		if (keychar == 4 || keychar == 1 || keychar == 5 || keychar == 2 ||
+		    keychar == 16 || keychar == 14 || keychar == 6)
+			return keychar;		/* non-printable supported control characters (e.g. CTRL+A) */
 		if (isprint(keychar))
 			break;		/* printable characters */
 		fallthrough;
-- 
2.39.2