53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
|
/* 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
|