[PATCH 70/93] samsung-laptop: Disable on EFI hardware

[Herton Ronaldo Krzesinski]

3.5.7.5 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Fleming <matt.fleming at intel.com>

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.

Cc: Corentin Chary <corentincj at iksaif.net>
Cc: Matthew Garrett <mjg59 at srcf.ucam.org>
Cc: Colin Ian King <colin.king at canonical.com>
Cc: Steve Langasek <steve.langasek at canonical.com>
Signed-off-by: Matt Fleming <matt.fleming at intel.com>
Signed-off-by: H. Peter Anvin <hpa at linux.intel.com>
[ herton: adjust context ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/platform/x86/samsung-laptop.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/platform/x86/samsung-laptop.c b/drivers/platform/x86/samsung-laptop.c
index 1afbe5e..de9f432 100644
--- 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;
-- 
1.7.9.5