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vt: make vt_console_print() compatible with the unicode screen buffer

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When kernel messages are printed to the console, they appear blank on
the unicode screen. This is because vt_console_print() is lacking a call
to vc_uniscr_putc(). However the later function assumes vc->vc_x is
always up to date when called, which is not the case here as
vt_console_print() uses it to mark the beginning of the display update.

This patch reworks (and simplifies) vt_console_print() so that vc->vc_x
is always valid and keeps the start of display update in a local variable
instead, which finally allows for adding the missing vc_uniscr_putc()
call.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicolas Pitre 2019-01-08 22:54:59 -05:00 committed by Greg Kroah-Hartman
parent fc01d8c61c
commit 6609cff65c
1 changed files with 15 additions and 32 deletions
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47
drivers/tty/vt/vt.c
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@ -2884,8 +2884,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
unsigned char c;
static DEFINE_SPINLOCK(printing_lock);
const ushort *start;
ushort cnt = 0;
ushort myx;
ushort start_x, cnt;
int kmsg_console;
/* console busy or not yet initialized */
@ -2898,10 +2897,6 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
if (kmsg_console && vc_cons_allocated(kmsg_console - 1))
vc = vc_cons[kmsg_console - 1].d;
/* read `x' only after setting currcons properly (otherwise
the `x' macro will read the x of the foreground console). */
myx = vc->vc_x;
if (!vc_cons_allocated(fg_console)) {
/* impossible */
/* printk("vt_console_print: tty %d not allocated ??\n", currcons+1); */
@ -2916,53 +2911,41 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
hide_cursor(vc);
start = (ushort *)vc->vc_pos;
/* Contrived structure to try to emulate original need_wrap behaviour
* Problems caused when we have need_wrap set on '\n' character */
start_x = vc->vc_x;
cnt = 0;
while (count--) {
c = *b++;
if (c == 10 || c == 13 || c == 8 || vc->vc_need_wrap) {
if (cnt > 0) {
if (con_is_visible(vc))
vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, vc->vc_x);
vc->vc_x += cnt;
if (vc->vc_need_wrap)
vc->vc_x--;
cnt = 0;
}
if (cnt && con_is_visible(vc))
vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, start_x);
cnt = 0;
if (c == 8) { /* backspace */
bs(vc);
start = (ushort *)vc->vc_pos;
myx = vc->vc_x;
start_x = vc->vc_x;
continue;
}
if (c != 13)
lf(vc);
cr(vc);
start = (ushort *)vc->vc_pos;
myx = vc->vc_x;
start_x = vc->vc_x;
if (c == 10 || c == 13)
continue;
}
vc_uniscr_putc(vc, c);
scr_writew((vc->vc_attr << 8) + c, (unsigned short *)vc->vc_pos);
notify_write(vc, c);
cnt++;
if (myx == vc->vc_cols - 1) {
vc->vc_need_wrap = 1;
continue;
}
vc->vc_pos += 2;
myx++;
}
if (cnt > 0) {
if (con_is_visible(vc))
vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, vc->vc_x);
vc->vc_x += cnt;
if (vc->vc_x == vc->vc_cols) {
vc->vc_x--;
if (vc->vc_x == vc->vc_cols - 1) {
vc->vc_need_wrap = 1;
} else {
vc->vc_pos += 2;
vc->vc_x++;
}
}
if (cnt && con_is_visible(vc))
vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, start_x);
set_cursor(vc);
notify_update(vc);