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>

Documentation/kernel-parameters.txt

@@ -148,10 +148,12 @@ and is between 256 and 4096 characters. It is defined in the file
 			default: 0
 
 	acpi_sleep=	[HW,ACPI] Sleep options
-			Format: { s3_bios, s3_mode, s3_beep, old_ordering }
+			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
 			See Documentation/power/video.txt for s3_bios and s3_mode.
 			s3_beep is for debugging; it makes the PC's speaker beep
 			as soon as the kernel's real-mode entry point is called.
+			s4_nohwsig prevents ACPI hardware signature from being
+			used during resume from hibernation.
 			old_ordering causes the ACPI 1.0 ordering of the _PTS
 			control method, wrt putting devices into low power
 			states, to be enforced (the ACPI 2.0 ordering of _PTS is

arch/x86/kernel/acpi/sleep.c

@@ -150,6 +150,10 @@ static int __init acpi_sleep_setup(char *str)
 			acpi_realmode_flags |= 2;
 		if (strncmp(str, "s3_beep", 7) == 0)
 			acpi_realmode_flags |= 4;
+#ifdef CONFIG_HIBERNATION
+		if (strncmp(str, "s4_nohwsig", 10) == 0)
+			acpi_no_s4_hw_signature();
+#endif
 		if (strncmp(str, "old_ordering", 12) == 0)
 			acpi_old_suspend_ordering();
 		str = strchr(str, ',');

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);

include/linux/acpi.h

@@ -236,6 +236,7 @@ int acpi_check_mem_region(resource_size_t start, resource_size_t n,
 		      const char *name);
 
 #ifdef CONFIG_PM_SLEEP
+void __init acpi_no_s4_hw_signature(void);
 void __init acpi_old_suspend_ordering(void);
 #endif /* CONFIG_PM_SLEEP */
 #else	/* CONFIG_ACPI */