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authorLorenzo Pieralisi <lorenzo.pieralisi@arm.com>2013-07-19 17:48:08 +0100
committerMark Brown <broonie@linaro.org>2014-06-19 12:33:56 +0100
commitd7ee1fd79f9677e5ab75215aa696e6ac50352ca9 (patch)
treead39e0904fb6127f31ef9e66327025bae2a43234
parent2f36c2ef1393d17dd2dde3458a55f804e0c10eac (diff)
downloadlinux-d7ee1fd79f9677e5ab75215aa696e6ac50352ca9.tar.gz
arm64: kernel: implement fpsimd CPU PM notifier
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@arm.com> (cherry picked from commit fb1ab1ab3889fc23ed90e452502662311ebdf229) Signed-off-by: Mark Brown <broonie@linaro.org>
-rw-r--r--arch/arm64/kernel/fpsimd.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index bb785d23dbd..4aef42a04bd 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(&current->thread.fpsimd_state);
+ break;
+ case CPU_PM_EXIT:
+ if (current->mm)
+ fpsimd_load_state(&current->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);