fbcon: Avoid using FNTCHARCNT() and hard-coded built-in font charcount
For user-provided fonts, the framebuffer layer is using a magic negative-indexing macro, FNTCHARCNT(), to keep track of their number of characters: #define FNTCHARCNT(fd) (((int *)(fd))[-3]) For built-in fonts, it is using hard-coded values (256). This results in something like the following: map.length = (ops->p->userfont) ? FNTCHARCNT(ops->p->fontdata) : 256; This is unsatisfactory. In fact, there is already a `charcount` field in our virtual console descriptor (see `struct console_font` inside `struct vc_data`), let us use it: map.length = vc->vc_font.charcount; Recently we added a `charcount` field to `struct font_desc`. Use it to set `vc->vc_font.charcount` properly. The idea is: - We only use FNTCHARCNT() on `vc->vc_font.data` and `p->fontdata`. Assume FNTCHARCNT() is working as intended; - Whenever `vc->vc_font.data` is set, also set `vc->vc_font.charcount` properly; - We can now replace `FNTCHARCNT(vc->vc_font.data)` with `vc->vc_font.charcount`; - Since `p->fontdata` always point to the same font data buffer with `vc->vc_font.data`, we can also replace `FNTCHARCNT(p->fontdata)` with `vc->vc_font.charcount`. In conclusion, set `vc->vc_font.charcount` properly in fbcon_startup(), fbcon_init(), fbcon_set_disp() and fbcon_do_set_font(), then replace FNTCHARCNT() with `vc->vc_font.charcount`. No more if-else between negative-indexing macros and hard-coded values. Do not include <linux/font.h> in fbcon_rotate.c and tileblit.c, since they no longer need it. Depends on patch "Fonts: Add charcount field to font_desc". Suggested-by: Daniel Vetter <daniel@ffwll.ch> Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/e460a5780e54e3022661d5f09555144583b4cc59.1605169912.git.yepeilin.cs@gmail.com
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