x86/earlyprintk/efi: Fix infinite loop on some screen widths

An affected screen resolution is 1366 x 768, which width is not
divisible by 8, the default font width. On such screens, when longer
lines are earlyprintk'ed, overflow-to-next-line can never trigger,
due to the left-most x-coordinate of the next character always less
than the screen width. Earlyprintk will infinite loop in trying to
print the rest of the string but unable to, due to the line being
full.

This patch makes the trigger consider the right-most x-coordinate,
instead of left-most, as the value to compare against the screen
width threshold.

Signed-off-by: YiFei Zhu <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arend van Spriel <[email protected]>
Cc: Bhupesh Sharma <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Eric Snowberg <[email protected]>
Cc: Hans de Goede <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Jon Hunter <[email protected]>
Cc: Julien Thierry <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sai Praneeth Prakhya <[email protected]>
Cc: Sedat Dilek <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/platform/efi/early_printk.c b/arch/x86/platform/efi/early_printk.c
index 7476b3b097e1e94dc0c305c6e9ef18a4e41633b3..7138bc7a265c016359e372d8274f3a4f6f068215 100644 (file)
--- a/arch/x86/platform/efi/early_printk.c
+++ b/arch/x86/platform/efi/early_printk.c
@@ -183,7 +183,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
                        num--;
                }
 
-               if (efi_x >= si->lfb_width) {
+               if (efi_x + font->width > si->lfb_width) {
                        efi_x = 0;
                        efi_y += font->height;
                }