x86/efi: Fix earlyprintk off-by-one bug

Dave reported seeing the following incorrect output on his Thinkpad T420
when using earlyprintk=efi,

[    0.000000] efi: EFI v2.00 by Lenovo
                    ACPI=0xdabfe000  ACPI 2.0=0xdabfe014 SMBIOS=0xdaa9e000

The output should be on one line, not split over two. The cause is an
off-by-one error when checking that the efi_y coordinate hasn't been
incremented out of bounds.

Reported-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/arch/x86/platform/efi/early_printk.c b/arch/x86/platform/efi/early_printk.c
index 6599a0027b76bb9ab3b390fe31e5ba0ae10ed124..81b506d5befd46e5a494d6cbef7aa71edceca7f1 100644 (file)
--- a/arch/x86/platform/efi/early_printk.c
+++ b/arch/x86/platform/efi/early_printk.c
@@ -142,7 +142,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
                        efi_y += font->height;
                }
 
-               if (efi_y + font->height >= si->lfb_height) {
+               if (efi_y + font->height > si->lfb_height) {
                        u32 i;
 
                        efi_y -= font->height;