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authorJames Morse <james.morse@arm.com>2016-04-27 17:47:13 +0100
committerAlex Shi <alex.shi@linaro.org>2016-05-25 16:36:41 +0800
commit37edefbad0ab547d1fdf9c2ef2212d436fa40274 (patch)
tree238e6c4bf4e7520b8f8e946d86cc40947179a27f
parent9ac76e72f51549699c502cef9f72f0ba2760a16e (diff)
downloadlinux-linaro-stable-37edefbad0ab547d1fdf9c2ef2212d436fa40274.tar.gz
arm64: hibernate: Refuse to hibernate if the boot cpu is offline
Hibernation represents a system state save/restore through a system reboot; this implies that the logical cpus carrying out hibernation/thawing must be the same, so that the context saved in the snapshot image on hibernation is consistent with the state of the system on resume. If resume from hibernation is driven through kernel command line parameter, the cpu responsible for thawing the system will be whatever CPU firmware boots the system on upon cold-boot (ie logical cpu 0); this means that in order to keep system context consistent between the hibernate snapshot image and system state on kernel resume from hibernate, logical cpu 0 must be online on hibernation and must be the logical cpu that creates the snapshot image. This patch adds a PM notifier that enforces logical cpu 0 is online when the hibernation is started (and prevents hibernation if it is not), which is sufficient to guarantee it will be the one creating the snapshot image therefore providing the resume cpu a consistent snapshot of the system to resume to. Signed-off-by: James Morse <james.morse@arm.com> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> (cherry picked from commit 1fe492ce6482b77807b25d29690a48c46456beee) Signed-off-by: Alex Shi <alex.shi@linaro.org>
-rw-r--r--arch/arm64/kernel/hibernate.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 7e16fb3..f8df75d 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -17,6 +17,7 @@
#define pr_fmt(x) "hibernate: " x
#include <linux/kvm_host.h>
#include <linux/mm.h>
+#include <linux/notifier.h>
#include <linux/pm.h>
#include <linux/sched.h>
#include <linux/suspend.h>
@@ -459,3 +460,28 @@ int swsusp_arch_resume(void)
out:
return rc;
}
+
+static int check_boot_cpu_online_pm_callback(struct notifier_block *nb,
+ unsigned long action, void *ptr)
+{
+ if (action == PM_HIBERNATION_PREPARE &&
+ cpumask_first(cpu_online_mask) != 0) {
+ pr_warn("CPU0 is offline.\n");
+ return notifier_from_errno(-ENODEV);
+ }
+
+ return NOTIFY_OK;
+}
+
+static int __init check_boot_cpu_online_init(void)
+{
+ /*
+ * Set this pm_notifier callback with a lower priority than
+ * cpu_hotplug_pm_callback, so that cpu_hotplug_pm_callback will be
+ * called earlier to disable cpu hotplug before the cpu online check.
+ */
+ pm_notifier(check_boot_cpu_online_pm_callback, -INT_MAX);
+
+ return 0;
+}
+core_initcall(check_boot_cpu_online_init);