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Diffstat (limited to 'arch/arm64/include/asm/simd.h')
| -rw-r--r-- | arch/arm64/include/asm/simd.h | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/simd.h b/arch/arm64/include/asm/simd.h new file mode 100644 index 000000000..6495cc512 --- /dev/null +++ b/arch/arm64/include/asm/simd.h @@ -0,0 +1,51 @@ +/* + * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#ifndef __ASM_SIMD_H +#define __ASM_SIMD_H + +#include <linux/compiler.h> +#include <linux/irqflags.h> +#include <linux/percpu.h> +#include <linux/preempt.h> +#include <linux/types.h> + +#ifdef CONFIG_KERNEL_MODE_NEON + +DECLARE_PER_CPU(bool, kernel_neon_busy); + +/* + * may_use_simd - whether it is allowable at this time to issue SIMD + * instructions or access the SIMD register file + * + * Callers must not assume that the result remains true beyond the next + * preempt_enable() or return from softirq context. + */ +static __must_check inline bool may_use_simd(void) +{ + /* + * kernel_neon_busy is only set while preemption is disabled, + * and is clear whenever preemption is enabled. Since + * this_cpu_read() is atomic w.r.t. preemption, kernel_neon_busy + * cannot change under our feet -- if it's set we cannot be + * migrated, and if it's clear we cannot be migrated to a CPU + * where it is set. + */ + return !in_irq() && !irqs_disabled() && !in_nmi() && + !this_cpu_read(kernel_neon_busy); +} + +#else /* ! CONFIG_KERNEL_MODE_NEON */ + +static __must_check inline bool may_use_simd(void) { + return false; +} + +#endif /* ! CONFIG_KERNEL_MODE_NEON */ + +#endif |