pm: acpi hibernation: utilize hardware signature

ACPI defines a hardware signature.  BIOS calculates the signature according to
hardware configure and if hardware changes while hibernated, the signature
will change.  In that case, S4 resume should fail.

Still, there may be systems on which this mechanism does not work correctly,
so it is better to provide a workaround for them.  For this reason, add a new
switch to the acpi_sleep= command line argument allowing one to disable
hardware signature checking.

[shaohua.li@intel.com: build fix]
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: <Valdis.Kletnieks@vt.edu>
Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c
index 0489a7d1d42c..313507accf18 100644
--- a/drivers/acpi/sleep/main.c
+++ b/drivers/acpi/sleep/main.c
@@ -283,6 +283,15 @@ static struct platform_suspend_ops acpi_suspend_ops_old = {
 #endif /* CONFIG_SUSPEND */
 
 #ifdef CONFIG_HIBERNATION
+static unsigned long s4_hardware_signature;
+static struct acpi_table_facs *facs;
+static bool nosigcheck;
+
+void __init acpi_no_s4_hw_signature(void)
+{
+	nosigcheck = true;
+}
+
 static int acpi_hibernation_begin(void)
 {
 	acpi_target_sleep_state = ACPI_STATE_S4;
@@ -316,6 +325,12 @@ static void acpi_hibernation_leave(void)
 	acpi_enable();
 	/* Reprogram control registers and execute _BFS */
 	acpi_leave_sleep_state_prep(ACPI_STATE_S4);
+	/* Check the hardware signature */
+	if (facs && s4_hardware_signature != facs->hardware_signature) {
+		printk(KERN_EMERG "ACPI: Hardware changed while hibernated, "
+			"cannot resume!\n");
+		panic("ACPI S4 hardware signature mismatch");
+	}
 }
 
 static void acpi_pm_enable_gpes(void)
@@ -544,6 +559,13 @@ int __init acpi_sleep_init(void)
 			&acpi_hibernation_ops_old : &acpi_hibernation_ops);
 		sleep_states[ACPI_STATE_S4] = 1;
 		printk(" S4");
+		if (!nosigcheck) {
+			acpi_get_table_by_index(ACPI_TABLE_INDEX_FACS,
+				(struct acpi_table_header **)&facs);
+			if (facs)
+				s4_hardware_signature =
+					facs->hardware_signature;
+		}
 	}
 #endif
 	status = acpi_get_sleep_type_data(ACPI_STATE_S5, &type_a, &type_b);