um: enable the use of optimized xor routines in UML

This patch enables the use of optimized xor routines from the x86
tree as well as the necessary fpu api shims so they can work on
UML.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/include/asm/fpu/api.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _ASM_UM_FPU_API_H
+#define _ASM_UM_FPU_API_H
+
+/* Copyright (c) 2020 Cambridge Greys Ltd
+ * Copyright (c) 2020 Red Hat Inc.
+ * A set of "dummy" defines to allow the direct inclusion
+ * of x86 optimized copy, xor, etc routines into the
+ * UML code tree. */
+
+#define kernel_fpu_begin() (void)0
+#define kernel_fpu_end() (void)0
+
+static inline bool irq_fpu_usable(void)
+{
+	return true;
+}
+
+
+#endif

arch/um/include/asm/xor.h

 /* SPDX-License-Identifier: GPL-2.0 */
-#include <asm-generic/xor.h>
+#ifndef _ASM_UM_XOR_H
+#define _ASM_UM_XOR_H
+
+#ifdef CONFIG_64BIT
+#undef CONFIG_X86_32
+#else
+#define CONFIG_X86_32 1
+#endif
+
+#include <asm/cpufeature.h>
+#include <../../x86/include/asm/xor.h>
 #include <linux/time-internal.h>
 
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+#undef XOR_SELECT_TEMPLATE
 /* pick an arbitrary one - measuring isn't possible with inf-cpu */
 #define XOR_SELECT_TEMPLATE(x)	\
 	(time_travel_mode == TT_MODE_INFCPU ? &xor_block_8regs : NULL)
+#endif
+
+#endif