PM / hibernate: introduce "nohibernate" boot parameter

To support using kernel features that are not compatible with hibernation,
this creates the "nohibernate" kernel boot parameter to disable both
hibernation and resume. This allows hibernation support to be a boot-time
choice instead of only a compile-time choice.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

5 files changed, 40 insertions, 5 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6eaa9cdb7094..f8f0466b8b1d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2184,6 +2184,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         in certain environments such as networked servers or
                         real-time systems.
 
+        nohibernate     [HIBERNATION] Disable hibernation and resume.
+
         nohz=           [KNL] Boottime enable/disable dynamic ticks
                         Valid arguments: on, off
                         Default: on
@@ -2980,6 +2982,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                 noresume        Don't check if there's a hibernation image
                                 present during boot.
                 nocompress      Don't compress/decompress hibernation images.
+                no              Disable hibernation and resume.
 
         retain_initrd   [RAM] Keep initrd memory after extraction
 
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index f76994b9396c..519064e0c943 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -327,6 +327,7 @@ extern unsigned long get_safe_page(gfp_t gfp_mask);
 extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
 extern int hibernate(void);
 extern bool system_entering_hibernation(void);
+extern bool hibernation_available(void);
 asmlinkage int swsusp_save(void);
 extern struct pbe *restore_pblist;
 #else /* CONFIG_HIBERNATION */
@@ -339,6 +340,7 @@ static inline void swsusp_unset_page_free(struct page *p) {}
 static inline void hibernation_set_ops(const struct platform_hibernation_ops *ops) {}
 static inline int hibernate(void) { return -ENOSYS; }
 static inline bool system_entering_hibernation(void) { return false; }
+static inline bool hibernation_available(void) { return false; }
 #endif /* CONFIG_HIBERNATION */
 
 /* Hibernation and suspend events */
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 49e0a20fd010..258f492f0347 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -35,6 +35,7 @@
 
 static int nocompress;
 static int noresume;
+static int nohibernate;
 static int resume_wait;
 static unsigned int resume_delay;
 static char resume_file[256] = CONFIG_PM_STD_PARTITION;
@@ -62,6 +63,11 @@ bool freezer_test_done;
 
 static const struct platform_hibernation_ops *hibernation_ops;
 
+bool hibernation_available(void)
+{
+        return (nohibernate == 0);
+}
+
 /**
  * hibernation_set_ops - Set the global hibernate operations.
  * @ops: Hibernation operations to use in subsequent hibernation transitions.
@@ -642,6 +648,11 @@ int hibernate(void)
 {
         int error;
 
+        if (!hibernation_available()) {
+                pr_debug("PM: Hibernation not available.\n");
+                return -EPERM;
+        }
+
         lock_system_sleep();
         /* The snapshot device should not be opened while we're running */
         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
@@ -734,7 +745,7 @@ static int software_resume(void)
         /*
          * If the user said "noresume".. bail out early.
          */
-        if (noresume)
+        if (noresume || !hibernation_available())
                 return 0;
 
         /*
@@ -900,6 +911,9 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
         int i;
         char *start = buf;
 
+        if (!hibernation_available())
+                return sprintf(buf, "[disabled]\n");
+
         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
                 if (!hibernation_modes[i])
                         continue;
@@ -934,6 +948,9 @@ static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
         char *p;
         int mode = HIBERNATION_INVALID;
 
+        if (!hibernation_available())
+                return -EPERM;
+
         p = memchr(buf, '\n', n);
         len = p ? p - buf : n;
 
@@ -1101,6 +1118,10 @@ static int __init hibernate_setup(char *str)
                 noresume = 1;
         else if (!strncmp(str, "nocompress", 10))
                 nocompress = 1;
+        else if (!strncmp(str, "no", 2)) {
+                noresume = 1;
+                nohibernate = 1;
+        }
         return 1;
 }
 
@@ -1125,9 +1146,17 @@ static int __init resumedelay_setup(char *str)
         return 1;
 }
 
+static int __init nohibernate_setup(char *str)
+{
+        noresume = 1;
+        nohibernate = 1;
+        return 1;
+}
+
 __setup("noresume", noresume_setup);
 __setup("resume_offset=", resume_offset_setup);
 __setup("resume=", resume_setup);
 __setup("hibernate=", hibernate_setup);
 __setup("resumewait", resumewait_setup);
 __setup("resumedelay=", resumedelay_setup);
+__setup("nohibernate", nohibernate_setup);
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 573410d6647e..8e90f330f139 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -300,13 +300,11 @@ static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
                         s += sprintf(s,"%s ", pm_states[i].label);
 
 #endif
-#ifdef CONFIG_HIBERNATION
-        s += sprintf(s, "%s\n", "disk");
-#else
+        if (hibernation_available())
+                s += sprintf(s, "disk ");
         if (s != buf)
                 /* convert the last space to a newline */
                 *(s-1) = '\n';
-#endif
         return (s - buf);
 }
 
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 98d357584cd6..526e8911460a 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -49,6 +49,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
         struct snapshot_data *data;
         int error;
 
+        if (!hibernation_available())
+                return -EPERM;
+
         lock_system_sleep();
 
         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {