The patch titled
vt: fix console corruption on driver hand-over
has been added to the -mm tree. Its filename is
vt-fix-console-corruption-on-driver-hand-over.patch
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------------------------------------------------------
Subject: vt: fix console corruption on driver hand-over
From: Francisco Jerez <currojerez@xxxxxxxxxx>
After 02f0777a0d6560 ("drivers/char/vt.c: fix vc->vc_origin on
take_over_console()"), vc_origin is no longer reset to the screen buffer
before calling the con_init() hook of the new console driver.
If the old driver wasn't using a fixed scanout buffer (e.g. the case of
vgacon) "vc_origin" may be a pointer to a VRAM location, and its contents
aren't guaranteed to be preserved after calling con_deinit() on the old
driver and con_init() on the new driver, i.e. the subsequent console
resize may fill the framebuffer with garbage.
It can be reproduced in the transition from vgacon to the nouveau
framebuffer driver: in that case the legacy VGA aperture "vc_origin"
points to becomes unreadable after fbcon_init().
This patch reverts the mentioned commit. To avoid the problem it intended
to fix, stop using "vc_scr_end" in vc_do_resize() to calculate how many
rows we have to copy (actually the code looks simpler this way without the
help of "vc_scr_end").
Signed-off-by: Francisco Jerez <currojerez@xxxxxxxxxx>
Tested-by: qiaochong <qiaochong@xxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/char/vt.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)
diff -puN drivers/char/vt.c~vt-fix-console-corruption-on-driver-hand-over drivers/char/vt.c
--- a/drivers/char/vt.c~vt-fix-console-corruption-on-driver-hand-over
+++ a/drivers/char/vt.c
@@ -906,22 +906,16 @@ static int vc_do_resize(struct tty_struc
* bottom of buffer
*/
old_origin += (old_rows - new_rows) * old_row_size;
- end = vc->vc_scr_end;
} else {
/*
* Cursor is in no man's land, copy 1/2 screenful
* from the top and bottom of cursor position
*/
old_origin += (vc->vc_y - new_rows/2) * old_row_size;
- end = old_origin + (old_row_size * new_rows);
}
- } else
- /*
- * Cursor near the top, copy contents from the top of buffer
- */
- end = (old_rows > new_rows) ? old_origin +
- (old_row_size * new_rows) :
- vc->vc_scr_end;
+ }
+
+ end = old_origin + old_row_size * min(old_rows, new_rows);
update_attr(vc);
@@ -3075,8 +3069,7 @@ static int bind_con_driver(const struct
old_was_color = vc->vc_can_do_color;
vc->vc_sw->con_deinit(vc);
- if (!vc->vc_origin)
- vc->vc_origin = (unsigned long)vc->vc_screenbuf;
+ vc->vc_origin = (unsigned long)vc->vc_screenbuf;
visual_init(vc, i, 0);
set_origin(vc);
update_attr(vc);
_
Patches currently in -mm which might be from currojerez@xxxxxxxxxx are
vt-fix-console-corruption-on-driver-hand-over.patch
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