/* * 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