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arm64: kernel: implement fpsimd CPU PM notifier

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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
This commit is contained in:
Lorenzo Pieralisi
2013-07-19 17:48:08 +01:00
committed by Alex Shi
parent ffc58bc556
commit 82c76f166d
1 changed files with 63 additions and 0 deletions
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63
arch/arm64/kernel/fpsimd.c
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@@ -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);