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authorLorenzo Pieralisi <lorenzo.pieralisi@arm.com>2013-07-19 17:48:08 +0100
committerAlex Shi <alex.shi@linaro.org>2014-03-10 13:38:36 +0800
commit82c76f166d477c49c22d05688385041b9a8a74de (patch)
tree817dae2329a7ebc86f4fe96287d6ab12a63b79ad
parentffc58bc556717fa470d6e54a2a604ee0d7063278 (diff)
downloadlinux-linaro-stable-82c76f166d477c49c22d05688385041b9a8a74de.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> Conflicts: arch/arm64/kernel/fpsimd.c
-rw-r--r--arch/arm64/kernel/fpsimd.c63
1 files changed, 63 insertions, 0 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 2fa308e4a1fa..522df9c7f3a4 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>
@@ -85,6 +86,66 @@ void fpsimd_flush_thread(void)
preempt_enable();
}
+#ifdef CONFIG_KERNEL_MODE_NEON
+
+/*
+ * Kernel-side NEON support functions
+ */
+void kernel_neon_begin(void)
+{
+ /* Avoid using the NEON in interrupt context */
+ BUG_ON(in_interrupt());
+ preempt_disable();
+
+ if (current->mm)
+ fpsimd_save_state(&current->thread.fpsimd_state);
+}
+EXPORT_SYMBOL(kernel_neon_begin);
+
+void kernel_neon_end(void)
+{
+ if (current->mm)
+ fpsimd_load_state(&current->thread.fpsimd_state);
+
+ preempt_enable();
+}
+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.
*/
@@ -103,6 +164,8 @@ static int __init fpsimd_init(void)
else
elf_hwcap |= HWCAP_ASIMD;
+ fpsimd_pm_init();
+
return 0;
}
late_initcall(fpsimd_init);