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Commit 32365e64 authored by Janet Liu's avatar Janet Liu Committed by Catalin Marinas
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arm64: fix bug for reloading FPSIMD state after CPU hotplug. 



Now FPSIMD don't handle HOTPLUG_CPU. This introduces bug after cpu down/up process.

After cpu down/up process, the FPSMID hardware register is default value, not any
process's fpsimd context. when CPU_DEAD set cpu's fpsimd_state to NULL, it will force
to load the fpsimd context for the thread, to avoid the chance to skip to load the context.
If process A is the last user process on CPU N before cpu down, and the first user process
on the same CPU N after cpu up, A's fpsimd_state.cpu is the current cpu id,
and per_cpu(fpsimd_last_state) points A's fpsimd_state, so kernel will not reload the
context during it return to user space.

Signed-off-by: default avatarJanet Liu <janet.liu@spreadtrum.com>
Signed-off-by: default avatarXiongshan An <xiongshan.an@spreadtrum.com>
Signed-off-by: default avatarChunyan Zhang <chunyan.zhang@spreadtrum.com>
[catalin.marinas@arm.com: some mostly cosmetic clean-ups]
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 6eb6c801

arch/arm64/kernel/fpsimd.c

+31 −0
Original line number Original line Diff line number Diff line
@@ -17,6 +17,7 @@ 
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

 */





#include <linux/cpu.h>

#include <linux/cpu_pm.h>

#include <linux/cpu_pm.h>

#include <linux/kernel.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/init.h>
@@ -296,6 +297,35 @@ static void fpsimd_pm_init(void) 
static inline void fpsimd_pm_init(void) { }

static inline void fpsimd_pm_init(void) { }

#endif /* CONFIG_CPU_PM */

#endif /* CONFIG_CPU_PM */





#ifdef CONFIG_HOTPLUG_CPU

static int fpsimd_cpu_hotplug_notifier(struct notifier_block *nfb,

				       unsigned long action,

				       void *hcpu)

{

	unsigned int cpu = (long)hcpu;



	switch (action) {

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

		per_cpu(fpsimd_last_state, cpu) = NULL;

		break;

	}

	return NOTIFY_OK;

}



static struct notifier_block fpsimd_cpu_hotplug_notifier_block = {

	.notifier_call = fpsimd_cpu_hotplug_notifier,

};



static inline void fpsimd_hotplug_init(void)

{

	register_cpu_notifier(&fpsimd_cpu_hotplug_notifier_block);

}



#else

static inline void fpsimd_hotplug_init(void) { }

#endif



/*

/*

 * FP/SIMD support code initialisation.

 * FP/SIMD support code initialisation.

 */

 */
@@ -315,6 +345,7 @@ static int __init fpsimd_init(void) 
		elf_hwcap |= HWCAP_ASIMD;

		elf_hwcap |= HWCAP_ASIMD;





	fpsimd_pm_init();

	fpsimd_pm_init();

	fpsimd_hotplug_init();





	return 0;

	return 0;

}

}