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vt: coherence validation code for the unicode screen buffer 

Make sure the unicode screen buffer matches the video screen content.
This is provided for debugging convenience and disabled by default.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicolas Pitre 2018-07-17 21:02:41 -04:00 committed by Greg Kroah-Hartman
parent 9bfdc2611d
commit 0224080fc8
1 changed files with 39 additions and 0 deletions
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39
drivers/tty/vt/vt.c
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@ -328,6 +328,8 @@ void schedule_console_callback(void)
#define get_vc_uniscr(vc) vc->vc_uni_screen
#endif
#define VC_UNI_SCREEN_DEBUG 0
typedef uint32_t char32_t;
/*
@ -569,6 +571,42 @@ void vc_uniscr_copy_line(struct vc_data *vc, void *dest, int viewed,
}
}
/* this is for validation and debugging only */
static void vc_uniscr_debug_check(struct vc_data *vc)
{
struct uni_screen *uniscr = get_vc_uniscr(vc);
unsigned short *p;
int x, y, mask;
if (!VC_UNI_SCREEN_DEBUG || !uniscr)
return;
WARN_CONSOLE_UNLOCKED();
/*
* Make sure our unicode screen translates into the same glyphs
* as the actual screen. This is brutal indeed.
*/
p = (unsigned short *)vc->vc_origin;
mask = vc->vc_hi_font_mask | 0xff;
for (y = 0; y < vc->vc_rows; y++) {
char32_t *line = uniscr->lines[y];
for (x = 0; x < vc->vc_cols; x++) {
u16 glyph = scr_readw(p++) & mask;
char32_t uc = line[x];
int tc = conv_uni_to_pc(vc, uc);
if (tc == -4)
tc = conv_uni_to_pc(vc, 0xfffd);
if (tc == -4)
tc = conv_uni_to_pc(vc, '?');
if (tc != glyph)
pr_err_ratelimited(
"%s: mismatch at %d,%d: glyph=%#x tc=%#x\n",
__func__, x, y, glyph, tc);
}
}
}
static void con_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
enum con_scroll dir, unsigned int nr)
@ -2717,6 +2755,7 @@ rescan_last_byte:
do_con_trol(tty, vc, orig);
}
con_flush(vc, draw_from, draw_to, &draw_x);
vc_uniscr_debug_check(vc);
console_conditional_schedule();
console_unlock();
notify_update(vc);