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