kernel/linux.git/lib/fonts/fonts.c, branch v7.1

lib/fonts: Provide helpers for calculating glyph pitch and size

2026-04-07T15:38:07+00:00

Implement pitch and size calculation for a single font glyph in the new helpers font_glyph_pitch() and font_glyph_size(). Replace the instances where the calculations are open-coded. Note that in the case of fbcon console rotation, the parameters for a glyph's width and height might be reversed. This is intentional. v2: - fix typos in commit message Signed-off-by: Thomas Zimmermann Signed-off-by: Helge Deller

lib/fonts: Remove internal symbols and macros from public header file

2026-03-09T14:47:21+00:00

Define access macros for font_data_t in fonts.c. Define struct font_data and declare most of the font symbols in the internal header font.h, where they can only be seen by the font code. Also move font indices into internal font.h. They appear to be unused though. There is m86k assembly code that operates on the idx field, so leave them in place for now. List all built-in fonts in a separate section in the public header file. v2: - do not add config guards around font symbols (Helge) - keep declaration of built-in fonts in public header Signed-off-by: Thomas Zimmermann Signed-off-by: Helge Deller

lib/fonts: Store font data for user space with font_data_export()

2026-03-09T14:47:21+00:00

Add font_data_export() and update consoles to use it. The helper font_data_export() is based on code in fbcon_get_font(). It extends the size of a single glyph to match the requested vpitch, which us usually 32 bytes for fonts from user space. Internal fonts have a pitch according to the glyph's height. The implementation of font_data_export() differs in several ways from the original code. The original implementation distinguished between different pitches of the font data. This is not necessary as the pitch is a parameter in the copying. There was also special handling for a font pitch of 3 bytes, which got expanded to 4 bytes (with trailing bits on each scanline). The logic originated from long before git history exists even in the historical tree. So it is not clear why this was implemented. It is not what user space expects. The setfont utitlity loads font with 3-bytes pitches and expects to read such fonts with a 3-byte pitch. For any font width, the font pitch is always the width extended to the next multiple of 8. See [1] for the user-space font-reading code. With the changes to handling the font pitches, font_data_export() replaces the original code's various special cases with a single copying logic. v3: - fix typos (Helge) Signed-off-by: Thomas Zimmermann Link: https://github.com/legionus/kbd/blob/v2.9.0/src/libkfont/kdfontop.c#L73 # [1] Signed-off-by: Helge Deller

lib/fonts: Create font_data_t from struct console_font with font_data_import()

2026-03-09T14:47:21+00:00

Add font_data_import() and update consoles to use it. The implementation of font_data_import() is based on code from fbcon, which supports overflow checks and crc32 checksums. Fbcon uses the crc32 checksum. Newport_con now implements the same overflow checks as fbcon. As before, this console does not support checksums, which are optional. Newport_con can now also handle input font data with a vertical pitch other than 32 bytes. (The vertical pitch is the offset between two glyphs in the font data.) As an internal change, remove the const qualifier from the data field if struct font_data. This allows font_data_import() to write the data without type casting. For all users of the font data via font_data_t, the stored data is still read only. v3: - fix typos Signed-off-by: Thomas Zimmermann Signed-off-by: Helge Deller

lib/fonts: Compare font data for equality with font_data_is_equal()

2026-03-09T14:47:21+00:00

Add font_data_is_equal() and update consoles to use it. Font data is equal if it has the same size and contains the same values on all bytes. Only fbcon uses a crc32 checksum. If set in both operands the checksums have to be equal. The new helper also guarantees to not compare internal fonts against fonts from user space. Internal fonts cannot be ref-counted, so making them equal to user-space fonts with the same byte sequence results in undefined behavior. The test only compares data buffers. Their interpretation is up each console. Therefore remove a width test in fbcon_set_font(). v3: - rebase onto font_data_{get,put}() Signed-off-by: Thomas Zimmermann Signed-off-by: Helge Deller

lib/fonts: Manage font-data lifetime with font_data_get/_put()

2026-03-09T14:47:21+00:00

Add font_data_get() and font_data_put(). Update consoles to use them over REFCOUNT() and plain kfree(). Newly allocated font data starts with a reference count of 1. Loading the font puts the previously loaded font. If the reference count reaches zero, font_data_put() frees the font data. The kernel stores a refcount of zero for internal font data. Invoking font_data_get() and font_data_put() tests this internally and returns success without further operation. From the caller's perspective, getting and putting works the same for all font data. Fbcon used the userfont flag distinguish between internal fonts and fonts loaded by user space. Only the latter where refcounted. With the new helper's automatic handling of internal font data, remove the userfont flag from fbcon. Newport_con uses a default font, FONT_DATA, until user space loads custom font data. Remove all special cases for FONT_DATA, as the get and put calls' read-only handling also covers this case. v3: - fix module linker error wrt font symbols (Nathan, Arnd) - fix typos Signed-off-by: Thomas Zimmermann Signed-off-by: Helge Deller

lib/fonts: Read font size with font_data_size()

2026-03-09T14:47:20+00:00

Add font_data_size() and update consoles to use it. Signed-off-by: Thomas Zimmermann Signed-off-by: Helge Deller

lib/fonts: Add Terminus 10x18 console font

2025-12-02T18:57:01+00:00

Add a compile-in option for Terminus 10x18 bitmap console font to improve readability on modern laptop displays. On modern 13-16 inch laptop displays with high pixel density, common scaled resolutions like 1280x800 and 1440x900 are widely used. At these resolutions, VGA 8x16 is too small and difficult to read for extended periods, while Terminus 16x32 is too large, providing only 25-28 rows. The existing 10x18 font has poor readability. Terminus 10x18 provides improved readability with its clean, fixed-width design while maintaining practical row counts (44-50 rows). A comfortable and readable built-in font for early boot messages, kernel panics or whenever userspace is unavailable. The font was converted from standard Terminus ter-i18b.psf using psftools and formatted to match kernel font conventions. This patch is non-intrusive, no options are enabled by default so most users won't notice a thing. Signed-off-by: Neilay Kharwadkar Signed-off-by: Helge Deller

fbcon: Increase maximum font width x height to 64 x 128

2024-03-16T07:29:48+00:00

By using bitmaps we actually support whatever size we would want, but the console currently limits fonts to 64x128 (which gives 60x16 text on 4k screens), so we don't need more for now, and we can easily increase later. Signed-off-by: Samuel Thibault Signed-off-by: Helge Deller

lib/fonts: fix undefined behavior in bit shift for get_default_font

2022-11-18T21:55:09+00:00

Shifting signed 32-bit value by 31 bits is undefined, so changing significant bit to unsigned. The UBSAN warning calltrace like below: UBSAN: shift-out-of-bounds in lib/fonts/fonts.c:139:20 left shift of 1 by 31 places cannot be represented in type 'int' dump_stack_lvl+0x7d/0xa5 dump_stack+0x15/0x1b ubsan_epilogue+0xe/0x4e __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c get_default_font+0x1c7/0x1f0 fbcon_startup+0x347/0x3a0 do_take_over_console+0xce/0x270 do_fbcon_takeover+0xa1/0x170 do_fb_registered+0x2a8/0x340 fbcon_fb_registered+0x47/0xe0 register_framebuffer+0x294/0x4a0 __drm_fb_helper_initial_config_and_unlock+0x43c/0x880 [drm_kms_helper] drm_fb_helper_initial_config+0x52/0x80 [drm_kms_helper] drm_fbdev_client_hotplug+0x156/0x1b0 [drm_kms_helper] drm_fbdev_generic_setup+0xfc/0x290 [drm_kms_helper] bochs_pci_probe+0x6ca/0x772 [bochs] local_pci_probe+0x4d/0xb0 pci_device_probe+0x119/0x320 really_probe+0x181/0x550 __driver_probe_device+0xc6/0x220 driver_probe_device+0x32/0x100 __driver_attach+0x195/0x200 bus_for_each_dev+0xbb/0x120 driver_attach+0x27/0x30 bus_add_driver+0x22e/0x2f0 driver_register+0xa9/0x190 __pci_register_driver+0x90/0xa0 bochs_pci_driver_init+0x52/0x1000 [bochs] do_one_initcall+0x76/0x430 do_init_module+0x61/0x28a load_module+0x1f82/0x2e50 __do_sys_finit_module+0xf8/0x190 __x64_sys_finit_module+0x23/0x30 do_syscall_64+0x58/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Link: https://lkml.kernel.org/r/20221031113829.4183153-1-cuigaosheng1@huawei.com Fixes: c81f717cb9e0 ("fbcon: Fix typo and bogus logic in get_default_font") Signed-off-by: Gaosheng Cui Signed-off-by: Andrew Morton