Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/simd.h b/arch/arm64/include/asm/simd.h
new file mode 100644
index 000000000..89cba2622
--- /dev/null
+++ b/arch/arm64/include/asm/simd.h
@@ -0,0 +1,52 @@
+/* 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_irq() && !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