[PATCH RFC v3 05/12] arm64: kernel: implement fpsimd CPU PM notifier
Lorenzo Pieralisi
lorenzo.pieralisi at arm.com
Thu Nov 21 06:24:12 EST 2013
When a CPU enters a low power state, its FP register content is lost.
This patch adds a notifier to save the FP context on CPU shutdown
and restore it on CPU resume. The context is saved and restored only
if the suspending thread is not a kernel thread, mirroring the current
context switch behaviour.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
---
arch/arm64/kernel/fpsimd.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index bb785d2..4aef42a 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -17,6 +17,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <linux/cpu_pm.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
@@ -113,6 +114,39 @@ EXPORT_SYMBOL(kernel_neon_end);
#endif /* CONFIG_KERNEL_MODE_NEON */
+#ifdef CONFIG_CPU_PM
+static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
+ unsigned long cmd, void *v)
+{
+ switch (cmd) {
+ case CPU_PM_ENTER:
+ if (current->mm)
+ fpsimd_save_state(¤t->thread.fpsimd_state);
+ break;
+ case CPU_PM_EXIT:
+ if (current->mm)
+ fpsimd_load_state(¤t->thread.fpsimd_state);
+ break;
+ case CPU_PM_ENTER_FAILED:
+ default:
+ return NOTIFY_DONE;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block fpsimd_cpu_pm_notifier_block = {
+ .notifier_call = fpsimd_cpu_pm_notifier,
+};
+
+static void fpsimd_pm_init(void)
+{
+ cpu_pm_register_notifier(&fpsimd_cpu_pm_notifier_block);
+}
+
+#else
+static inline void fpsimd_pm_init(void) { }
+#endif /* CONFIG_CPU_PM */
+
/*
* FP/SIMD support code initialisation.
*/
@@ -131,6 +165,8 @@ static int __init fpsimd_init(void)
else
elf_hwcap |= HWCAP_ASIMD;
+ fpsimd_pm_init();
+
return 0;
}
late_initcall(fpsimd_init);
--
1.8.4
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