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Diffstat (limited to 'arch/arm64/include/asm/simd.h')
| -rw-r--r-- | arch/arm64/include/asm/simd.h | 52 |
1 files changed, 52 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..6a75d7ecd --- /dev/null +++ b/arch/arm64/include/asm/simd.h @@ -0,0 +1,52 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org> + */ + +#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> + +DECLARE_PER_CPU(bool, fpsimd_context_busy); + +#ifdef CONFIG_KERNEL_MODE_NEON + +/* + * 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) +{ + /* + * We must make sure that the SVE has been initialized properly + * before using the SIMD in kernel. + * fpsimd_context_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, fpsimd_context_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 !WARN_ON(!system_capabilities_finalized()) && + system_supports_fpsimd() && + !in_hardirq() && !irqs_disabled() && !in_nmi() && + !this_cpu_read(fpsimd_context_busy); +} + +#else /* ! CONFIG_KERNEL_MODE_NEON */ + +static __must_check inline bool may_use_simd(void) { + return false; +} + +#endif /* ! CONFIG_KERNEL_MODE_NEON */ + +#endif |