samsung-laptop: Disable on EFI hardware

commit e0094244e41c4d0c7ad69920681972fc45d8ce34 upstream.

It has been reported that running this driver on some Samsung laptops
with EFI can cause those machines to become bricked as detailed in the
following report,

	https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557

There have also been reports of this driver causing Machine Check
Exceptions on recent EFI-enabled Samsung laptops,

	https://bugzilla.kernel.org/show_bug.cgi?id=47121

So disable it if booting from EFI since this driver relies on
grovelling around in the BIOS memory map which isn't going to work.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Cc: Corentin Chary <corentincj@iksaif.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Steve Langasek <steve.langasek@canonical.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/platform/x86/samsung-laptop.c b/drivers/platform/x86/samsung-laptop.c
index 1afbe5e0a3488c9825b183d9fc91b8dfaf73a8a8..de9f432cf22d10fabc0b9ca3b5782ebdd602fabb 100644 (file)
--- a/drivers/platform/x86/samsung-laptop.c
+++ b/drivers/platform/x86/samsung-laptop.c
@@ -26,6 +26,7 @@
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
 #include <linux/ctype.h>
+#include <linux/efi.h>
 #if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
 #include <acpi/video.h>
 #endif
@@ -1527,6 +1528,9 @@ static int __init samsung_init(void)
        struct samsung_laptop *samsung;
        int ret;
 
+       if (efi_enabled(EFI_BOOT))
+               return -ENODEV;
+
        quirks = &samsung_unknown;
        if (!force && !dmi_check_system(samsung_dmi_table))
                return -ENODEV;