tty: vt: decrypt magic constants in vc_is_control()

0x0d00ff81 and 0x0800f501 are bitmasks of ASCII characters. Spell them
explicitly using BIT() + ASCII constants. GENMASK() is used for the
9-bit range in CTRL_ACTION.

This also modifies the 'if' checking if the masks should be applied.
>From a "random" ' ' to the actual size of the bitmasks' type.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20240202065608.14019-23-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index e35f7a31a7bd54f890394c8923ce2d531c34b47d..463be4e48dc8f7e4ef97afea9ece886696b64039 100644 (file)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2893,9 +2893,13 @@ static bool vc_is_control(struct vc_data *vc, int tc, int c)
         * as cursor movement) and should not be displayed as a glyph unless
         * the disp_ctrl mode is explicitly enabled.
         */
-       static const u32 CTRL_ACTION = 0x0d00ff81;
+       static const u32 CTRL_ACTION = BIT(ASCII_NULL) |
+               GENMASK(ASCII_SHIFTIN, ASCII_BELL) | BIT(ASCII_CANCEL) |
+               BIT(ASCII_SUBSTITUTE) | BIT(ASCII_ESCAPE);
        /* Cannot be overridden by disp_ctrl */
-       static const u32 CTRL_ALWAYS = 0x0800f501;
+       static const u32 CTRL_ALWAYS = BIT(ASCII_NULL) | BIT(ASCII_BACKSPACE) |
+               BIT(ASCII_LINEFEED) | BIT(ASCII_SHIFTIN) | BIT(ASCII_SHIFTOUT) |
+               BIT(ASCII_CAR_RET) | BIT(ASCII_FORMFEED) | BIT(ASCII_ESCAPE);
 
        if (vc->vc_state != ESnormal)
                return true;
@@ -2912,7 +2916,7 @@ static bool vc_is_control(struct vc_data *vc, int tc, int c)
         * useless without them; to display an arbitrary font position use the
         * direct-to-font zone in UTF-8 mode.
         */
-       if (c < ' ') {
+       if (c < BITS_PER_TYPE(CTRL_ALWAYS)) {
                if (vc->vc_disp_ctrl)
                        return CTRL_ALWAYS & BIT(c);
                else