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VT: Bump font size limitation to 64x128 pixels

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This moves 32x32 font size limitation checking down to drivers, so that
fbcon can allow large fonts.

We still keep a limitation to 64x128 pixels so as to have a simple bounded
allocation for con_font_get and in the userland kbd tool. That glyph size
will however be enough to have 128x36 characters on a "16/9 8K display".

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/20230119151935.112415738@ens-lyon.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Samuel Thibault 2023-01-19 16:19:17 +01:00 committed by Greg Kroah-Hartman
parent 24d69384bc
commit 05e2600cb0
3 changed files with 19 additions and 13 deletions
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28
drivers/tty/vt/vt.c
View file

@ -4523,17 +4523,20 @@ void reset_palette(struct vc_data *vc)
/*
* Font switching
*
* Currently we only support fonts up to 32 pixels wide, at a maximum height
* of 32 pixels. Userspace fontdata is stored with 32 bytes (shorts/ints,
* depending on width) reserved for each character which is kinda wasty, but
* this is done in order to maintain compatibility with the EGA/VGA fonts. It
* is up to the actual low-level console-driver convert data into its favorite
* format (maybe we should add a `fontoffset' field to the `display'
* structure so we won't have to convert the fontdata all the time.
* Currently we only support fonts up to 128 pixels wide, at a maximum height
* of 128 pixels. Userspace fontdata may have to be stored with 32 bytes
* (shorts/ints, depending on width) reserved for each character which is
* kinda wasty, but this is done in order to maintain compatibility with the
* EGA/VGA fonts. It is up to the actual low-level console-driver convert data
* into its favorite format (maybe we should add a `fontoffset' field to the
* `display' structure so we won't have to convert the fontdata all the time.
* /Jes
*/
#define max_font_size 65536
#define max_font_width 64
#define max_font_height 128
#define max_font_glyphs 512
#define max_font_size (max_font_glyphs*max_font_width*max_font_height)
static int con_font_get(struct vc_data *vc, struct console_font_op *op)
{
@ -4543,7 +4546,7 @@ static int con_font_get(struct vc_data *vc, struct console_font_op *op)
unsigned int vpitch = op->op == KD_FONT_OP_GET_TALL ? op->height : 32;
if (op->data) {
font.data = kmalloc(max_font_size, GFP_KERNEL);
font.data = kvmalloc(max_font_size, GFP_KERNEL);
if (!font.data)
return -ENOMEM;
} else
@ -4578,7 +4581,7 @@ static int con_font_get(struct vc_data *vc, struct console_font_op *op)
rc = -EFAULT;
out:
kfree(font.data);
kvfree(font.data);
return rc;
}
@ -4593,9 +4596,10 @@ static int con_font_set(struct vc_data *vc, struct console_font_op *op)
return -EINVAL;
if (!op->data)
return -EINVAL;
if (op->charcount > 512)
if (op->charcount > max_font_glyphs)
return -EINVAL;
if (op->width <= 0 || op->width > 32 || !op->height || op->height > 32)
if (op->width <= 0 || op->width > max_font_width || !op->height ||
op->height > max_font_height)
return -EINVAL;
if (vpitch < op->height)
return -EINVAL;

2
drivers/video/console/vgacon.c
View file

@ -1037,7 +1037,7 @@ static int vgacon_font_set(struct vc_data *c, struct console_font *font,
if (vga_video_type < VIDEO_TYPE_EGAM)
return -EINVAL;
if (font->width != VGA_FONTWIDTH || vpitch != 32 ||
if (font->width != VGA_FONTWIDTH || font->height > 32 || vpitch != 32 ||
(charcount != 256 && charcount != 512))
return -EINVAL;

2
drivers/video/fbdev/core/fbcon.c
View file

@ -2279,6 +2279,8 @@ static int fbcon_get_font(struct vc_data *vc, struct console_font *font, unsigne
font->width = vc->vc_font.width;
font->height = vc->vc_font.height;
if (font->height > vpitch)
return -ENOSPC;
font->charcount = vc->vc_hi_font_mask ? 512 : 256;
if (!font->data)
return 0;