Re: [patch] hibernation: utilize ACPI hardware signature

[Shaohua Li <shaohua.li@intel.com>]

On Sat, 2008-01-05 at 04:44 +0800, Rafael J. Wysocki wrote:
> On Friday, 4 of January 2008, Shaohua Li wrote:
> >
> > On Fri, 2008-01-04 at 01:04 +0800, Rafael J. Wysocki wrote:
> > > On Thursday, 3 of January 2008, Shaohua Li wrote:
> > > >
> > > > On Wed, 2008-01-02 at 22:05 +0800, Rafael J. Wysocki wrote:
> > > > > On Wednesday, 2 of January 2008, Shaohua Li wrote:
> > > > > > ACPI defines a hardware signature. BIOS calculates the
> signature
> > > > > > according to hardware configure, if hardware changes, the
> > > signature
> > > > > will
> > > > > > change, in this case, S4 resume should fail.
> > > > >
> > > > > The idea is fine, but I'd prefer to do that in a more
> > > straightforward
> > > > > way.
> > > > > Namely, we can just:
> > > > > * write the signature into a variable in, for example,
> > > > >   acpi_hibernation_prepare() (then, the "old" signature value
> will
> > > be
> > > > >   automatically saved in the image)
> > > > > * compare it with a the "new" value read from the BIOS in
> > > > >   acpi_hibernation_leave() and panic if there's a mismatch
> > > > > * add a configuration option to disable this behavior (just in
> > > case)
> > > > > This way we can avoid modifying the entire generic interface
> to
> > > add
> > > > > the feature
> > > > > specific to ACPI.
> > > > it would be better we do the check in boot kernel.
> > > Franky, I think we should also check in the image kernel, in case
> the
> > > boot
> > > one doesn't support ACPI as I said.
> > Ok, makes sense. I changed to check the signature
> in .higberation_leave
> 
> Thanks, comments below.
> 
> > Signed-off-by: Shaohua Li <shaohua.li@intel.com>
> > ---
> >  drivers/acpi/sleep/main.c |   20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > Index: linux/drivers/acpi/sleep/main.c
> > ===================================================================
> > --- linux.orig/drivers/acpi/sleep/main.c      2008-01-03
> 13:37:08.000000000 +0800
> > +++ linux/drivers/acpi/sleep/main.c   2008-01-04 13:36:10.000000000
> +0800
> > @@ -256,6 +256,17 @@ static int acpi_hibernation_enter(void)
> >       return ACPI_SUCCESS(status) ? 0 : -EFAULT;
> >  }
> > 
> > +static unsigned long s4_hardware_signature;
> > +static struct acpi_table_facs *facs;
> > +static int nosigcheck;
> 
> Use bool perhaps?
> 
> > +
> > +static int __init acpi_s4_nosigcheck(char *str)
> > +{
> > +     nosigcheck = 1;
> 
> And "true" here?
> 
> > +     return 1;
> > +}
> > +__setup("acpi_s4_nosigcheck", acpi_s4_nosigcheck);
> > +
> 
> Please put this function at the end of the file.  Also, I'd call it
> "acpi_s4_nosig", but whatever.
Fixed all except this one, the routine is defined with HIBERATION
configed.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
---
 drivers/acpi/sleep/main.c |   22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

Index: linux/drivers/acpi/sleep/main.c
===================================================================
--- linux.orig/drivers/acpi/sleep/main.c	2008-01-04 13:44:40.000000000 +0800
+++ linux/drivers/acpi/sleep/main.c	2008-01-07 09:31:42.000000000 +0800
@@ -256,6 +256,17 @@ static int acpi_hibernation_enter(void)
 	return ACPI_SUCCESS(status) ? 0 : -EFAULT;
 }
 
+static unsigned long s4_hardware_signature;
+static struct acpi_table_facs *facs;
+static bool nosigcheck;
+
+static int __init acpi_s4_nosigcheck(char *str)
+{
+	nosigcheck = true;
+	return 1;
+}
+__setup("acpi_s4_nosigcheck", acpi_s4_nosigcheck);
+
 static void acpi_hibernation_leave(void)
 {
 	/*
@@ -263,6 +274,10 @@ static void acpi_hibernation_leave(void)
 	 * enable it here.
 	 */
 	acpi_enable();
+	if (facs && s4_hardware_signature != facs->hardware_signature) {
+		printk(KERN_EMERG"PM: Hardware changed in the S4 circle, can't resume\n");
+		panic("S4 resume error");
+	}
 }
 
 static void acpi_hibernation_finish(void)
@@ -448,6 +463,13 @@ int __init acpi_sleep_init(void)
 		hibernation_set_ops(&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);