From fb1ab1ab3889fc23ed90e452502662311ebdf229 Mon Sep 17 00:00:00 2001 From: Lorenzo Pieralisi Date: Fri, 19 Jul 2013 17:48:08 +0100 Subject: [PATCH] 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 --- 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 . */ +#include #include #include #include @@ -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); -- 2.7.4