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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
* Copyright (C) 2023 SiFive
*/
#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>
#include <linux/thread_info.h>
#include <asm/vector.h>
#ifdef CONFIG_RISCV_ISA_V
/*
* may_use_simd - whether it is allowable at this time to issue vector
* instructions or access the vector 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)
{
/*
* RISCV_KERNEL_MODE_V is only set while preemption is disabled,
* and is clear whenever preemption is enabled.
*/
if (in_hardirq() || in_nmi())
return false;
/*
* Nesting is acheived in preempt_v by spreading the control for
* preemptible and non-preemptible kernel-mode Vector into two fields.
* Always try to match with prempt_v if kernel V-context exists. Then,
* fallback to check non preempt_v if nesting happens, or if the config
* is not set.
*/
if (IS_ENABLED(CONFIG_RISCV_ISA_V_PREEMPTIVE) && current->thread.kernel_vstate.datap) {
if (!riscv_preempt_v_started(current))
return true;
}
/*
* Non-preemptible kernel-mode Vector temporarily disables bh. So we
* must not return true on irq_disabled(). Otherwise we would fail the
* lockdep check calling local_bh_enable()
*/
return !irqs_disabled() && !(riscv_v_flags() & RISCV_KERNEL_MODE_V);
}
#else /* ! CONFIG_RISCV_ISA_V */
static __must_check inline bool may_use_simd(void)
{
return false;
}
#endif /* ! CONFIG_RISCV_ISA_V */
#endif
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