From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Thu, 11 Apr 2024 10:27:49 +0200
Subject: Adding upstream version 6.6.15.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 arch/loongarch/kernel/kfpu.c | 90 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 arch/loongarch/kernel/kfpu.c

(limited to 'arch/loongarch/kernel/kfpu.c')

diff --git a/arch/loongarch/kernel/kfpu.c b/arch/loongarch/kernel/kfpu.c
new file mode 100644
index 0000000000..ec5b28e570
--- /dev/null
+++ b/arch/loongarch/kernel/kfpu.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <asm/fpu.h>
+#include <asm/smp.h>
+
+static unsigned int euen_mask = CSR_EUEN_FPEN;
+
+/*
+ * The critical section between kernel_fpu_begin() and kernel_fpu_end()
+ * is non-reentrant. It is the caller's responsibility to avoid reentrance.
+ * See drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c as an example.
+ */
+static DEFINE_PER_CPU(bool, in_kernel_fpu);
+static DEFINE_PER_CPU(unsigned int, euen_current);
+
+void kernel_fpu_begin(void)
+{
+	unsigned int *euen_curr;
+
+	preempt_disable();
+
+	WARN_ON(this_cpu_read(in_kernel_fpu));
+
+	this_cpu_write(in_kernel_fpu, true);
+	euen_curr = this_cpu_ptr(&euen_current);
+
+	*euen_curr = csr_xchg32(euen_mask, euen_mask, LOONGARCH_CSR_EUEN);
+
+#ifdef CONFIG_CPU_HAS_LASX
+	if (*euen_curr & CSR_EUEN_LASXEN)
+		_save_lasx(&current->thread.fpu);
+	else
+#endif
+#ifdef CONFIG_CPU_HAS_LSX
+	if (*euen_curr & CSR_EUEN_LSXEN)
+		_save_lsx(&current->thread.fpu);
+	else
+#endif
+	if (*euen_curr & CSR_EUEN_FPEN)
+		_save_fp(&current->thread.fpu);
+
+	write_fcsr(LOONGARCH_FCSR0, 0);
+}
+EXPORT_SYMBOL_GPL(kernel_fpu_begin);
+
+void kernel_fpu_end(void)
+{
+	unsigned int *euen_curr;
+
+	WARN_ON(!this_cpu_read(in_kernel_fpu));
+
+	euen_curr = this_cpu_ptr(&euen_current);
+
+#ifdef CONFIG_CPU_HAS_LASX
+	if (*euen_curr & CSR_EUEN_LASXEN)
+		_restore_lasx(&current->thread.fpu);
+	else
+#endif
+#ifdef CONFIG_CPU_HAS_LSX
+	if (*euen_curr & CSR_EUEN_LSXEN)
+		_restore_lsx(&current->thread.fpu);
+	else
+#endif
+	if (*euen_curr & CSR_EUEN_FPEN)
+		_restore_fp(&current->thread.fpu);
+
+	*euen_curr = csr_xchg32(*euen_curr, euen_mask, LOONGARCH_CSR_EUEN);
+
+	this_cpu_write(in_kernel_fpu, false);
+
+	preempt_enable();
+}
+EXPORT_SYMBOL_GPL(kernel_fpu_end);
+
+static int __init init_euen_mask(void)
+{
+	if (cpu_has_lsx)
+		euen_mask |= CSR_EUEN_LSXEN;
+
+	if (cpu_has_lasx)
+		euen_mask |= CSR_EUEN_LASXEN;
+
+	return 0;
+}
+arch_initcall(init_euen_mask);
-- 
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