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authorFrancisco Jerez <currojerez@riseup.net>2010-08-22 17:37:24 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-09-03 17:29:03 -0700
commit9fc2b2d0cf743008d8f6be6293278f4ef61f09f3 (patch)
treedf7c30660be493aa9844da45f02c06097936f5b9
parent2bfc96a127bc1cc94d26bfaa40159966064f9c8c (diff)
vt: Fix console corruption on driver hand-over.
After 02f0777a0d6560eb995aade34a1b82f95c0452da "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@riseup.net> Cc: qiaochong <qiaochong@loongson.cn> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/char/vt.c15
1 files changed, 4 insertions, 11 deletions
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 50590c7f2c01..281aada7b4a1 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -906,22 +906,16 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
* 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 consw *csw, int first, int last,
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);