v4.19.13 snapshot.
diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
new file mode 100644
index 0000000..63b3393
--- /dev/null
+++ b/arch/x86/include/asm/realmode.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ARCH_X86_REALMODE_H
+#define _ARCH_X86_REALMODE_H
+
+/*
+ * Flag bit definitions for use with the flags field of the trampoline header
+ * in the CONFIG_X86_64 variant.
+ */
+#define TH_FLAGS_SME_ACTIVE_BIT 0
+#define TH_FLAGS_SME_ACTIVE BIT(TH_FLAGS_SME_ACTIVE_BIT)
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <asm/io.h>
+
+/* This must match data at realmode.S */
+struct real_mode_header {
+ u32 text_start;
+ u32 ro_end;
+ /* SMP trampoline */
+ u32 trampoline_start;
+ u32 trampoline_status;
+ u32 trampoline_header;
+#ifdef CONFIG_X86_64
+ u32 trampoline_pgd;
+#endif
+ /* ACPI S3 wakeup */
+#ifdef CONFIG_ACPI_SLEEP
+ u32 wakeup_start;
+ u32 wakeup_header;
+#endif
+ /* APM/BIOS reboot */
+ u32 machine_real_restart_asm;
+#ifdef CONFIG_X86_64
+ u32 machine_real_restart_seg;
+#endif
+};
+
+/* This must match data at trampoline_32/64.S */
+struct trampoline_header {
+#ifdef CONFIG_X86_32
+ u32 start;
+ u16 gdt_pad;
+ u16 gdt_limit;
+ u32 gdt_base;
+#else
+ u64 start;
+ u64 efer;
+ u32 cr4;
+ u32 flags;
+#endif
+};
+
+extern struct real_mode_header *real_mode_header;
+extern unsigned char real_mode_blob_end[];
+
+extern unsigned long initial_code;
+extern unsigned long initial_gs;
+extern unsigned long initial_stack;
+
+extern unsigned char real_mode_blob[];
+extern unsigned char real_mode_relocs[];
+
+#ifdef CONFIG_X86_32
+extern unsigned char startup_32_smp[];
+extern unsigned char boot_gdt[];
+#else
+extern unsigned char secondary_startup_64[];
+#endif
+
+static inline size_t real_mode_size_needed(void)
+{
+ if (real_mode_header)
+ return 0; /* already allocated. */
+
+ return ALIGN(real_mode_blob_end - real_mode_blob, PAGE_SIZE);
+}
+
+void set_real_mode_mem(phys_addr_t mem, size_t size);
+void reserve_real_mode(void);
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ARCH_X86_REALMODE_H */