kernel/linux.git/drivers/video/fbdev/core/fbcon_ud.c, branch v6.12.80

fbcon: Use correct erase colour for clearing in fbcon

2025-05-29T09:02:05+00:00

[ Upstream commit 892c788d73fe4a94337ed092cb998c49fa8ecaf4 ] The erase colour calculation for fbcon clearing should use get_color instead of attr_col_ec, like everything else. The latter is similar but is not correct. For example it's missing the depth dependent remapping and doesn't care about blanking. The problem can be reproduced by setting up the background colour to grey (vt.color=0x70) and having an fbcon console set to 2bpp (4 shades of gray). Now the background attribute should be 1 (dark gray) on the console. If the screen is scrolled when pressing enter in a shell prompt at the bottom line then the new line is cleared using colour 7 instead of 1. That's not something fillrect likes (at 2bbp it expect 0-3) so the result is interesting. This patch switches to get_color with vc_video_erase_char to determine the erase colour from attr_col_ec. That makes the latter function redundant as no other users were left. Use correct erase colour for clearing in fbcon Signed-off-by: Zsolt Kajtar Signed-off-by: Helge Deller Signed-off-by: Sasha Levin

tty: vt: remove CM_* constants

2024-01-28T02:08:54+00:00

There is no difference between CM_MOVE and CM_DRAW. Either of them enables the cursor. CM_ERASE then disables cursor. So get rid of all of them and use simple "bool enable". Note that this propagates down to the fbcon code. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" Cc: Helge Deller Cc: "James E.J. Bottomley" Cc: Daniel Vetter Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-30-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

fbdev/core: simplify cursor_state setting in fbcon_ops::cursor()

2024-01-28T02:08:54+00:00

There is a switch decicing if cursor should be drawn or not. The whole switch can be simplified to one line. Do this cleanup as a preparatory work for the next patch. There, all the CM_* constants are removed. Signed-off-by: "Jiri Slaby (SUSE)" Cc: Daniel Vetter Cc: Helge Deller Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Tested-by: Helge Deller # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-29-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

fbcon: Add option to enable legacy hardware acceleration

2022-02-02T14:16:26+00:00

Add a config option CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION to enable bitblt and fillrect hardware acceleration in the framebuffer console. If disabled, such acceleration will not be used, even if it is supported by the graphics hardware driver. If you plan to use DRM as your main graphics output system, you should disable this option since it will prevent compiling in code which isn't used later on when DRM takes over. For all other configurations, e.g. if none of your graphic cards support DRM (yet), DRM isn't available for your architecture, or you can't be sure that the graphic card in the target system will support DRM, you most likely want to enable this option. In the non-accelerated case (e.g. when DRM is used), the inlined fb_scrollmode() function is hardcoded to return SCROLL_REDRAW and as such the compiler is able to optimize much unneccesary code away. In this v3 patch version I additionally changed the GETVYRES() and GETVXRES() macros to take a pointer to the fbcon_display struct. This fixes the build when console rotation is enabled and helps the compiler again to optimize out code. Signed-off-by: Helge Deller Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Helge Deller Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220202135531.92183-4-deller@gmx.de

Revert "fbdev: Garbage collect fbdev scrolling acceleration, part 1 (from TODO list)"

2022-02-02T14:14:56+00:00

This reverts commit b3ec8cdf457e5e63d396fe1346cc788cf7c1b578. Revert the second (of 2) commits which disabled scrolling acceleration in fbcon/fbdev. It introduced a regression for fbdev-supported graphic cards because of the performance penalty by doing screen scrolling by software instead of using the existing graphic card 2D hardware acceleration. Console scrolling acceleration was disabled by dropping code which checked at runtime the driver hardware capabilities for the BINFO_HWACCEL_COPYAREA or FBINFO_HWACCEL_FILLRECT flags and if set, it enabled scrollmode SCROLL_MOVE which uses hardware acceleration to move screen contents. After dropping those checks scrollmode was hard-wired to SCROLL_REDRAW instead, which forces all graphic cards to redraw every character at the new screen position when scrolling. This change effectively disabled all hardware-based scrolling acceleration for ALL drivers, because now all kind of 2D hardware acceleration (bitblt, fillrect) in the drivers isn't used any longer. The original commit message mentions that only 3 DRM drivers (nouveau, omapdrm and gma500) used hardware acceleration in the past and thus code for checking and using scrolling acceleration is obsolete. This statement is NOT TRUE, because beside the DRM drivers there are around 35 other fbdev drivers which depend on fbdev/fbcon and still provide hardware acceleration for fbdev/fbcon. The original commit message also states that syzbot found lots of bugs in fbcon and thus it's "often the solution to just delete code and remove features". This is true, and the bugs - which actually affected all users of fbcon, including DRM - were fixed, or code was dropped like e.g. the support for software scrollback in vgacon (commit 973c096f6a85). So to further analyze which bugs were found by syzbot, I've looked through all patches in drivers/video which were tagged with syzbot or syzkaller back to year 2005. The vast majority fixed the reported issues on a higher level, e.g. when screen is to be resized, or when font size is to be changed. The few ones which touched driver code fixed a real driver bug, e.g. by adding a check. But NONE of those patches touched code of either the SCROLL_MOVE or the SCROLL_REDRAW case. That means, there was no real reason why SCROLL_MOVE had to be ripped-out and just SCROLL_REDRAW had to be used instead. The only reason I can imagine so far was that SCROLL_MOVE wasn't used by DRM and as such it was assumed that it could go away. That argument completely missed the fact that SCROLL_MOVE is still heavily used by fbdev (non-DRM) drivers. Some people mention that using memcpy() instead of the hardware acceleration is pretty much the same speed. But that's not true, at least not for older graphic cards and machines where we see speed decreases by factor 10 and more and thus this change leads to console responsiveness way worse than before. That's why the original commit is to be reverted. By reverting we reintroduce hardware-based scrolling acceleration and fix the performance regression for fbdev drivers. There isn't any impact on DRM when reverting those patches. Signed-off-by: Helge Deller Acked-by: Geert Uytterhoeven Acked-by: Sven Schnelle Cc: stable@vger.kernel.org # v5.16+ Signed-off-by: Helge Deller Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220202135531.92183-2-deller@gmx.de

fbdev: Garbage collect fbdev scrolling acceleration, part 1 (from TODO list)

2021-10-13T13:29:23+00:00

Scroll acceleration is disabled in fbcon by hard-wiring p->scrollmode = SCROLL_REDRAW. Remove the obsolete code in fbcon.c and fbdev/core/ Signed-off-by: Claudio Suarez Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/YVXTYqszZix9TxjJ@gineta.localdomain

fbcon: Drop EXPORT_SYMBOL

2020-11-17T10:00:43+00:00

Every since commit 6104c37094e729f3d4ce65797002112735d49cd1 Author: Daniel Vetter Date: Tue Aug 1 17:32:07 2017 +0200 fbcon: Make fbcon a built-time depency for fbdev these are no longer distinct loadable modules, so exporting symbols is kinda pointless. Acked-by: Thomas Zimmermann Signed-off-by: Daniel Vetter Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: Daniel Vetter Cc: Tetsuo Handa Cc: Helge Deller Cc: Peilin Ye Link: https://patchwork.freedesktop.org/patch/msgid/20201029101428.4058311-2-daniel.vetter@ffwll.ch

fbcon: remove now unusued 'softback_lines' cursor() argument

2020-09-14T17:06:15+00:00

Since the softscroll code got removed, this argument is always zero and makes no sense any more. Tested-by: Yuan Ming Tested-by: Willy Tarreau Reviewed-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds

Merge 5.8-rc7 into tty-next

2020-07-27T10:40:56+00:00

we need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman

fbdev: Detect integer underflow at "struct fbcon_ops"->clear_margins.

2020-07-23T14:22:25+00:00

syzbot is reporting general protection fault in bitfill_aligned() [1] caused by integer underflow in bit_clear_margins(). The cause of this problem is when and how do_vc_resize() updates vc->vc_{cols,rows}. If vc_do_resize() fails (e.g. kzalloc() fails) when var.xres or var.yres is going to shrink, vc->vc_{cols,rows} will not be updated. This allows bit_clear_margins() to see info->var.xres < (vc->vc_cols * cw) or info->var.yres < (vc->vc_rows * ch). Unexpectedly large rw or bh will try to overrun the __iomem region and causes general protection fault. Also, vc_resize(vc, 0, 0) does not set vc->vc_{cols,rows} = 0 due to new_cols = (cols ? cols : vc->vc_cols); new_rows = (lines ? lines : vc->vc_rows); exception. Since cols and lines are calculated as cols = FBCON_SWAP(ops->rotate, info->var.xres, info->var.yres); rows = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres); cols /= vc->vc_font.width; rows /= vc->vc_font.height; vc_resize(vc, cols, rows); in fbcon_modechanged(), var.xres < vc->vc_font.width makes cols = 0 and var.yres < vc->vc_font.height makes rows = 0. This means that const int fd = open("/dev/fb0", O_ACCMODE); struct fb_var_screeninfo var = { }; ioctl(fd, FBIOGET_VSCREENINFO, &var); var.xres = var.yres = 1; ioctl(fd, FBIOPUT_VSCREENINFO, &var); easily reproduces integer underflow bug explained above. Of course, callers of vc_resize() are not handling vc_do_resize() failure is bad. But we can't avoid vc_resize(vc, 0, 0) which returns 0. Therefore, as a band-aid workaround, this patch checks integer underflow in "struct fbcon_ops"->clear_margins call, assuming that vc->vc_cols * vc->vc_font.width and vc->vc_rows * vc->vc_font.heigh do not cause integer overflow. [1] https://syzkaller.appspot.com/bug?id=a565882df74fa76f10d3a6fec4be31098dbb37c6 Reported-and-tested-by: syzbot Signed-off-by: Tetsuo Handa Acked-by: Daniel Vetter Cc: stable Link: https://lore.kernel.org/r/20200715015102.3814-1-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Greg Kroah-Hartman