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52 lines
1.5 KiB
52 lines
1.5 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* |
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* Copyright (C) 2017 Linaro Ltd. <[email protected]> |
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*/ |
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#ifndef __ASM_SIMD_H |
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#define __ASM_SIMD_H |
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#include <linux/compiler.h> |
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#include <linux/irqflags.h> |
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#include <linux/percpu.h> |
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#include <linux/preempt.h> |
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#include <linux/types.h> |
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DECLARE_PER_CPU(bool, fpsimd_context_busy); |
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#ifdef CONFIG_KERNEL_MODE_NEON |
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/* |
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* may_use_simd - whether it is allowable at this time to issue SIMD |
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* instructions or access the SIMD register file |
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* |
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* Callers must not assume that the result remains true beyond the next |
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* preempt_enable() or return from softirq context. |
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*/ |
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static __must_check inline bool may_use_simd(void) |
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{ |
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/* |
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* We must make sure that the SVE has been initialized properly |
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* before using the SIMD in kernel. |
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* fpsimd_context_busy is only set while preemption is disabled, |
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* and is clear whenever preemption is enabled. Since |
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* this_cpu_read() is atomic w.r.t. preemption, fpsimd_context_busy |
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* cannot change under our feet -- if it's set we cannot be |
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* migrated, and if it's clear we cannot be migrated to a CPU |
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* where it is set. |
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*/ |
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return !WARN_ON(!system_capabilities_finalized()) && |
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system_supports_fpsimd() && |
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!in_hardirq() && !irqs_disabled() && !in_nmi() && |
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!this_cpu_read(fpsimd_context_busy); |
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} |
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#else /* ! CONFIG_KERNEL_MODE_NEON */ |
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static __must_check inline bool may_use_simd(void) { |
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return false; |
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} |
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#endif /* ! CONFIG_KERNEL_MODE_NEON */ |
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#endif
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