Adding upstream version 6.6.15.upstream/6.6.15

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

23 files changed, 1330 insertions, 0 deletions

diff --git a/arch/x86/realmode/Makefile b/arch/x86/realmode/Makefile
new file mode 100644
index 0000000000..a0b491ae2d
--- /dev/null
+++ b/arch/x86/realmode/Makefile
@@ -0,0 +1,22 @@
+#
+# arch/x86/realmode/Makefile
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+#
+
+# Sanitizer runtimes are unavailable and cannot be linked here.
+KASAN_SANITIZE			:= n
+KCSAN_SANITIZE			:= n
+
+subdir- := rm
+
+obj-y += init.o
+obj-y += rmpiggy.o
+
+$(obj)/rmpiggy.o: $(obj)/rm/realmode.bin
+
+$(obj)/rm/realmode.bin: FORCE
+	$(Q)$(MAKE) $(build)=$(obj)/rm $@
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
new file mode 100644
index 0000000000..788e555954
--- /dev/null
+++ b/arch/x86/realmode/init.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/memblock.h>
+#include <linux/cc_platform.h>
+#include <linux/pgtable.h>
+
+#include <asm/set_memory.h>
+#include <asm/realmode.h>
+#include <asm/tlbflush.h>
+#include <asm/crash.h>
+#include <asm/sev.h>
+
+struct real_mode_header *real_mode_header;
+u32 *trampoline_cr4_features;
+
+/* Hold the pgd entry used on booting additional CPUs */
+pgd_t trampoline_pgd_entry;
+
+void load_trampoline_pgtable(void)
+{
+#ifdef CONFIG_X86_32
+	load_cr3(initial_page_table);
+#else
+	/*
+	 * This function is called before exiting to real-mode and that will
+	 * fail with CR4.PCIDE still set.
+	 */
+	if (boot_cpu_has(X86_FEATURE_PCID))
+		cr4_clear_bits(X86_CR4_PCIDE);
+
+	write_cr3(real_mode_header->trampoline_pgd);
+#endif
+
+	/*
+	 * The CR3 write above will not flush global TLB entries.
+	 * Stale, global entries from previous page tables may still be
+	 * present.  Flush those stale entries.
+	 *
+	 * This ensures that memory accessed while running with
+	 * trampoline_pgd is *actually* mapped into trampoline_pgd.
+	 */
+	__flush_tlb_all();
+}
+
+void __init reserve_real_mode(void)
+{
+	phys_addr_t mem;
+	size_t size = real_mode_size_needed();
+
+	if (!size)
+		return;
+
+	WARN_ON(slab_is_available());
+
+	/* Has to be under 1M so we can execute real-mode AP code. */
+	mem = memblock_phys_alloc_range(size, PAGE_SIZE, 0, 1<<20);
+	if (!mem)
+		pr_info("No sub-1M memory is available for the trampoline\n");
+	else
+		set_real_mode_mem(mem);
+
+	/*
+	 * Unconditionally reserve the entire fisrt 1M, see comment in
+	 * setup_arch().
+	 */
+	memblock_reserve(0, SZ_1M);
+}
+
+static void __init sme_sev_setup_real_mode(struct trampoline_header *th)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
+		th->flags |= TH_FLAGS_SME_ACTIVE;
+
+	if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
+		/*
+		 * Skip the call to verify_cpu() in secondary_startup_64 as it
+		 * will cause #VC exceptions when the AP can't handle them yet.
+		 */
+		th->start = (u64) secondary_startup_64_no_verify;
+
+		if (sev_es_setup_ap_jump_table(real_mode_header))
+			panic("Failed to get/update SEV-ES AP Jump Table");
+	}
+#endif
+}
+
+static void __init setup_real_mode(void)
+{
+	u16 real_mode_seg;
+	const u32 *rel;
+	u32 count;
+	unsigned char *base;
+	unsigned long phys_base;
+	struct trampoline_header *trampoline_header;
+	size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+#ifdef CONFIG_X86_64
+	u64 *trampoline_pgd;
+	u64 efer;
+	int i;
+#endif
+
+	base = (unsigned char *)real_mode_header;
+
+	/*
+	 * If SME is active, the trampoline area will need to be in
+	 * decrypted memory in order to bring up other processors
+	 * successfully. This is not needed for SEV.
+	 */
+	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
+		set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
+
+	memcpy(base, real_mode_blob, size);
+
+	phys_base = __pa(base);
+	real_mode_seg = phys_base >> 4;
+
+	rel = (u32 *) real_mode_relocs;
+
+	/* 16-bit segment relocations. */
+	count = *rel++;
+	while (count--) {
+		u16 *seg = (u16 *) (base + *rel++);
+		*seg = real_mode_seg;
+	}
+
+	/* 32-bit linear relocations. */
+	count = *rel++;
+	while (count--) {
+		u32 *ptr = (u32 *) (base + *rel++);
+		*ptr += phys_base;
+	}
+
+	/* Must be performed *after* relocation. */
+	trampoline_header = (struct trampoline_header *)
+		__va(real_mode_header->trampoline_header);
+
+#ifdef CONFIG_X86_32
+	trampoline_header->start = __pa_symbol(startup_32_smp);
+	trampoline_header->gdt_limit = __BOOT_DS + 7;
+	trampoline_header->gdt_base = __pa_symbol(boot_gdt);
+#else
+	/*
+	 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
+	 * so we need to mask it out.
+	 */
+	rdmsrl(MSR_EFER, efer);
+	trampoline_header->efer = efer & ~EFER_LMA;
+
+	trampoline_header->start = (u64) secondary_startup_64;
+	trampoline_cr4_features = &trampoline_header->cr4;
+	*trampoline_cr4_features = mmu_cr4_features;
+
+	trampoline_header->flags = 0;
+
+	trampoline_lock = &trampoline_header->lock;
+	*trampoline_lock = 0;
+
+	trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
+
+	/* Map the real mode stub as virtual == physical */
+	trampoline_pgd[0] = trampoline_pgd_entry.pgd;
+
+	/*
+	 * Include the entirety of the kernel mapping into the trampoline
+	 * PGD.  This way, all mappings present in the normal kernel page
+	 * tables are usable while running on trampoline_pgd.
+	 */
+	for (i = pgd_index(__PAGE_OFFSET); i < PTRS_PER_PGD; i++)
+		trampoline_pgd[i] = init_top_pgt[i].pgd;
+#endif
+
+	sme_sev_setup_real_mode(trampoline_header);
+}
+
+/*
+ * reserve_real_mode() gets called very early, to guarantee the
+ * availability of low memory. This is before the proper kernel page
+ * tables are set up, so we cannot set page permissions in that
+ * function. Also trampoline code will be executed by APs so we
+ * need to mark it executable at do_pre_smp_initcalls() at least,
+ * thus run it as a early_initcall().
+ */
+static void __init set_real_mode_permissions(void)
+{
+	unsigned char *base = (unsigned char *) real_mode_header;
+	size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+
+	size_t ro_size =
+		PAGE_ALIGN(real_mode_header->ro_end) -
+		__pa(base);
+
+	size_t text_size =
+		PAGE_ALIGN(real_mode_header->ro_end) -
+		real_mode_header->text_start;
+
+	unsigned long text_start =
+		(unsigned long) __va(real_mode_header->text_start);
+
+	set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
+	set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
+	set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
+}
+
+void __init init_real_mode(void)
+{
+	if (!real_mode_header)
+		panic("Real mode trampoline was not allocated");
+
+	setup_real_mode();
+	set_real_mode_permissions();
+}
+
+static int __init do_init_real_mode(void)
+{
+	x86_platform.realmode_init();
+	return 0;
+}
+early_initcall(do_init_real_mode);
diff --git a/arch/x86/realmode/rm/.gitignore b/arch/x86/realmode/rm/.gitignore
new file mode 100644
index 0000000000..6c3464f461
--- /dev/null
+++ b/arch/x86/realmode/rm/.gitignore
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+pasyms.h
+realmode.lds
+realmode.relocs
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
new file mode 100644
index 0000000000..f614009d3e
--- /dev/null
+++ b/arch/x86/realmode/rm/Makefile
@@ -0,0 +1,80 @@
+#
+# arch/x86/realmode/Makefile
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+#
+
+# Sanitizer runtimes are unavailable and cannot be linked here.
+KASAN_SANITIZE			:= n
+KCSAN_SANITIZE			:= n
+KMSAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
+
+# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+KCOV_INSTRUMENT		:= n
+
+always-y := realmode.bin realmode.relocs
+
+wakeup-objs	:= wakeup_asm.o wakemain.o video-mode.o
+wakeup-objs	+= copy.o bioscall.o regs.o
+# The link order of the video-*.o modules can matter.  In particular,
+# video-vga.o *must* be listed first, followed by video-vesa.o.
+# Hardware-specific drivers should follow in the order they should be
+# probed, and video-bios.o should typically be last.
+wakeup-objs	+= video-vga.o
+wakeup-objs	+= video-vesa.o
+wakeup-objs	+= video-bios.o
+
+realmode-y			+= header.o
+realmode-y			+= trampoline_$(BITS).o
+realmode-y			+= stack.o
+realmode-y			+= reboot.o
+realmode-$(CONFIG_ACPI_SLEEP)	+= $(wakeup-objs)
+
+targets	+= $(realmode-y)
+
+REALMODE_OBJS = $(addprefix $(obj)/,$(realmode-y))
+
+sed-pasyms := -n -r -e 's/^([0-9a-fA-F]+) [ABCDGRSTVW] (.+)$$/pa_\2 = \2;/p'
+
+quiet_cmd_pasyms = PASYMS  $@
+      cmd_pasyms = $(NM) $(real-prereqs) | sed $(sed-pasyms) | sort | uniq > $@
+
+targets += pasyms.h
+$(obj)/pasyms.h: $(REALMODE_OBJS) FORCE
+	$(call if_changed,pasyms)
+
+targets += realmode.lds
+$(obj)/realmode.lds: $(obj)/pasyms.h
+
+LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T
+CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj)
+
+targets += realmode.elf
+$(obj)/realmode.elf: $(obj)/realmode.lds $(REALMODE_OBJS) FORCE
+	$(call if_changed,ld)
+
+OBJCOPYFLAGS_realmode.bin := -O binary
+
+targets += realmode.bin
+$(obj)/realmode.bin: $(obj)/realmode.elf $(obj)/realmode.relocs FORCE
+	$(call if_changed,objcopy)
+
+quiet_cmd_relocs = RELOCS  $@
+      cmd_relocs = arch/x86/tools/relocs --realmode $< > $@
+
+targets += realmode.relocs
+$(obj)/realmode.relocs: $(obj)/realmode.elf FORCE
+	$(call if_changed,relocs)
+
+# ---------------------------------------------------------------------------
+
+KBUILD_CFLAGS	:= $(REALMODE_CFLAGS) -D_SETUP -D_WAKEUP \
+		   -I$(srctree)/arch/x86/boot
+KBUILD_AFLAGS	:= $(KBUILD_CFLAGS) -D__ASSEMBLY__
+KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables
+GCOV_PROFILE := n
+UBSAN_SANITIZE := n
diff --git a/arch/x86/realmode/rm/bioscall.S b/arch/x86/realmode/rm/bioscall.S
new file mode 100644
index 0000000000..16162d1979
--- /dev/null
+++ b/arch/x86/realmode/rm/bioscall.S
@@ -0,0 +1 @@
+#include "../../boot/bioscall.S"
diff --git a/arch/x86/realmode/rm/copy.S b/arch/x86/realmode/rm/copy.S
new file mode 100644
index 0000000000..b785e6f38f
--- /dev/null
+++ b/arch/x86/realmode/rm/copy.S
@@ -0,0 +1 @@
+#include "../../boot/copy.S"
diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S
new file mode 100644
index 0000000000..2eb62be6d2
--- /dev/null
+++ b/arch/x86/realmode/rm/header.S
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Real-mode blob header; this should match realmode.h and be
+ * readonly; for mutable data instead add pointers into the .data
+ * or .bss sections as appropriate.
+ */
+
+#include <linux/linkage.h>
+#include <asm/page_types.h>
+#include <asm/segment.h>
+
+#include "realmode.h"
+	
+	.section ".header", "a"
+
+	.balign	16
+SYM_DATA_START(real_mode_header)
+	.long	pa_text_start
+	.long	pa_ro_end
+	/* SMP trampoline */
+	.long	pa_trampoline_start
+	.long	pa_trampoline_header
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+	.long	pa_sev_es_trampoline_start
+#endif
+#ifdef CONFIG_X86_64
+	.long	pa_trampoline_start64
+	.long	pa_trampoline_pgd;
+#endif
+	/* ACPI S3 wakeup */
+#ifdef CONFIG_ACPI_SLEEP
+	.long	pa_wakeup_start
+	.long	pa_wakeup_header
+#endif
+	/* APM/BIOS reboot */
+	.long	pa_machine_real_restart_asm
+#ifdef CONFIG_X86_64
+	.long	__KERNEL32_CS
+#endif
+SYM_DATA_END(real_mode_header)
+
+	/* End signature, used to verify integrity */
+	.section ".signature","a"
+	.balign 4
+SYM_DATA(end_signature, .long REALMODE_END_SIGNATURE)
diff --git a/arch/x86/realmode/rm/realmode.h b/arch/x86/realmode/rm/realmode.h
new file mode 100644
index 0000000000..c76041a353
--- /dev/null
+++ b/arch/x86/realmode/rm/realmode.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_X86_REALMODE_RM_REALMODE_H
+#define ARCH_X86_REALMODE_RM_REALMODE_H
+
+#ifdef __ASSEMBLY__
+
+/*
+ * 16-bit ljmpw to the real_mode_seg
+ *
+ * This must be open-coded since gas will choke on using a
+ * relocatable symbol for the segment portion.
+ */
+#define LJMPW_RM(to)	.byte 0xea ; .word (to), real_mode_seg
+
+#endif /* __ASSEMBLY__ */
+
+/*
+ * Signature at the end of the realmode region
+ */
+#define REALMODE_END_SIGNATURE	0x65a22c82
+
+#endif /* ARCH_X86_REALMODE_RM_REALMODE_H */
diff --git a/arch/x86/realmode/rm/realmode.lds.S b/arch/x86/realmode/rm/realmode.lds.S
new file mode 100644
index 0000000000..63aa51875b
--- /dev/null
+++ b/arch/x86/realmode/rm/realmode.lds.S
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * realmode.lds.S
+ *
+ * Linker script for the real-mode code
+ */
+
+#include <asm/page_types.h>
+
+#undef i386
+
+OUTPUT_FORMAT("elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(pa_text_start)
+
+SECTIONS
+{
+	real_mode_seg = 0;
+
+	. = 0;
+	.header : {
+		pa_real_mode_base = .;
+		*(.header)
+	}
+
+	. = ALIGN(4);
+	.rodata : {
+		*(.rodata)
+		*(.rodata.*)
+		. = ALIGN(16);
+		video_cards = .;
+		*(.videocards)
+		video_cards_end = .;
+	}
+
+	. = ALIGN(PAGE_SIZE);
+	pa_text_start = .;
+	.text : {
+		*(.text)
+		*(.text.*)
+	}
+
+	.text32 : {
+		*(.text32)
+		*(.text32.*)
+	}
+
+	.text64 : {
+		*(.text64)
+		*(.text64.*)
+	}
+	pa_ro_end = .;
+
+	. = ALIGN(PAGE_SIZE);
+	.data : {
+		*(.data)
+		*(.data.*)
+	}
+
+	. = ALIGN(128);
+	.bss : {
+		*(.bss*)
+	}
+
+	/* End signature for integrity checking */
+	. = ALIGN(4);
+	.signature : {
+		*(.signature)
+	}
+
+	/DISCARD/ : {
+		*(.note*)
+		*(.debug*)
+	}
+
+#include "pasyms.h"
+}
diff --git a/arch/x86/realmode/rm/reboot.S b/arch/x86/realmode/rm/reboot.S
new file mode 100644
index 0000000000..f10515b10e
--- /dev/null
+++ b/arch/x86/realmode/rm/reboot.S
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/page_types.h>
+#include <asm/processor-flags.h>
+#include <asm/msr-index.h>
+#include "realmode.h"
+
+/*
+ * The following code and data reboots the machine by switching to real
+ * mode and jumping to the BIOS reset entry point, as if the CPU has
+ * really been reset.  The previous version asked the keyboard
+ * controller to pulse the CPU reset line, which is more thorough, but
+ * doesn't work with at least one type of 486 motherboard.  It is easy
+ * to stop this code working; hence the copious comments.
+ *
+ * This code is called with the restart type (0 = BIOS, 1 = APM) in
+ * the primary argument register (%eax for 32 bit, %edi for 64 bit).
+ */
+	.section ".text32", "ax"
+	.code32
+SYM_CODE_START(machine_real_restart_asm)
+
+#ifdef CONFIG_X86_64
+	/* Switch to trampoline GDT as it is guaranteed < 4 GiB */
+	movl	$__KERNEL_DS, %eax
+	movl	%eax, %ds
+	lgdtl	pa_tr_gdt
+
+	/* Disable paging to drop us out of long mode */
+	movl	%cr0, %eax
+	andl	$~X86_CR0_PG, %eax
+	movl	%eax, %cr0
+	ljmpl	$__KERNEL32_CS, $pa_machine_real_restart_paging_off
+
+SYM_INNER_LABEL(machine_real_restart_paging_off, SYM_L_GLOBAL)
+	xorl	%eax, %eax
+	xorl	%edx, %edx
+	movl	$MSR_EFER, %ecx
+	wrmsr
+
+	movl	%edi, %eax
+	
+#endif /* CONFIG_X86_64 */
+	
+	/* Set up the IDT for real mode. */
+	lidtl	pa_machine_real_restart_idt
+
+	/*
+	 * Set up a GDT from which we can load segment descriptors for real
+	 * mode.  The GDT is not used in real mode; it is just needed here to
+	 * prepare the descriptors.
+	 */
+	lgdtl	pa_machine_real_restart_gdt
+
+	/*
+	 * Load the data segment registers with 16-bit compatible values
+	 */
+	movl	$16, %ecx
+	movl	%ecx, %ds
+	movl	%ecx, %es
+	movl	%ecx, %fs
+	movl	%ecx, %gs
+	movl	%ecx, %ss
+	ljmpw	$8, $1f
+SYM_CODE_END(machine_real_restart_asm)
+
+/*
+ * This is 16-bit protected mode code to disable paging and the cache,
+ * switch to real mode and jump to the BIOS reset code.
+ *
+ * The instruction that switches to real mode by writing to CR0 must be
+ * followed immediately by a far jump instruction, which set CS to a
+ * valid value for real mode, and flushes the prefetch queue to avoid
+ * running instructions that have already been decoded in protected
+ * mode.
+ *
+ * Clears all the flags except ET, especially PG (paging), PE
+ * (protected-mode enable) and TS (task switch for coprocessor state
+ * save).  Flushes the TLB after paging has been disabled.  Sets CD and
+ * NW, to disable the cache on a 486, and invalidates the cache.  This
+ * is more like the state of a 486 after reset.  I don't know if
+ * something else should be done for other chips.
+ *
+ * More could be done here to set up the registers as if a CPU reset had
+ * occurred; hopefully real BIOSs don't assume much.  This is not the
+ * actual BIOS entry point, anyway (that is at 0xfffffff0).
+ *
+ * Most of this work is probably excessive, but it is what is tested.
+ */
+	.text
+	.code16
+
+	.balign	16
+machine_real_restart_asm16:
+1:
+	xorl	%ecx, %ecx
+	movl	%cr0, %edx
+	andl	$0x00000011, %edx
+	orl	$0x60000000, %edx
+	movl	%edx, %cr0
+	movl	%ecx, %cr3
+	movl	%cr0, %edx
+	testl	$0x60000000, %edx	/* If no cache bits -> no wbinvd */
+	jz	2f
+	wbinvd
+2:
+	andb	$0x10, %dl
+	movl	%edx, %cr0
+	LJMPW_RM(3f)
+3:
+	andw	%ax, %ax
+	jz	bios
+
+apm:
+	movw	$0x1000, %ax
+	movw	%ax, %ss
+	movw	$0xf000, %sp
+	movw	$0x5307, %ax
+	movw	$0x0001, %bx
+	movw	$0x0003, %cx
+	int	$0x15
+	/* This should never return... */
+
+bios:
+	ljmpw	$0xf000, $0xfff0
+
+	.section ".rodata", "a"
+
+	.balign	16
+SYM_DATA_START(machine_real_restart_idt)
+	.word	0xffff		/* Length - real mode default value */
+	.long	0		/* Base - real mode default value */
+SYM_DATA_END(machine_real_restart_idt)
+
+	.balign	16
+SYM_DATA_START(machine_real_restart_gdt)
+	/* Self-pointer */
+	.word	0xffff		/* Length - real mode default value */
+	.long	pa_machine_real_restart_gdt
+	.word	0
+
+	/*
+	 * 16-bit code segment pointing to real_mode_seg
+	 * Selector value 8
+	 */
+	.word	0xffff		/* Limit */
+	.long	0x9b000000 + pa_real_mode_base
+	.word	0
+
+	/*
+	 * 16-bit data segment with the selector value 16 = 0x10 and
+	 * base value 0x100; since this is consistent with real mode
+	 * semantics we don't have to reload the segments once CR0.PE = 0.
+	 */
+	.quad	GDT_ENTRY(0x0093, 0x100, 0xffff)
+SYM_DATA_END(machine_real_restart_gdt)
diff --git a/arch/x86/realmode/rm/regs.c b/arch/x86/realmode/rm/regs.c
new file mode 100644
index 0000000000..fbb15b9f9c
--- /dev/null
+++ b/arch/x86/realmode/rm/regs.c
@@ -0,0 +1 @@
+#include "../../boot/regs.c"
diff --git a/arch/x86/realmode/rm/stack.S b/arch/x86/realmode/rm/stack.S
new file mode 100644
index 0000000000..0fca64061a
--- /dev/null
+++ b/arch/x86/realmode/rm/stack.S
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Common heap and stack allocations
+ */
+
+#include <linux/linkage.h>
+
+	.data
+SYM_DATA(HEAP,		.long rm_heap)
+SYM_DATA(heap_end,	.long rm_stack)
+
+	.bss
+	.balign	16
+SYM_DATA(rm_heap,	.space 2048)
+
+SYM_DATA_START(rm_stack)
+	.space	2048
+SYM_DATA_END_LABEL(rm_stack, SYM_L_GLOBAL, rm_stack_end)
diff --git a/arch/x86/realmode/rm/trampoline_32.S b/arch/x86/realmode/rm/trampoline_32.S
new file mode 100644
index 0000000000..3fad907a17
--- /dev/null
+++ b/arch/x86/realmode/rm/trampoline_32.S
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *
+ *	Trampoline.S	Derived from Setup.S by Linus Torvalds
+ *
+ *	4 Jan 1997 Michael Chastain: changed to gnu as.
+ *
+ *	This is only used for booting secondary CPUs in SMP machine
+ *
+ *	Entry: CS:IP point to the start of our code, we are
+ *	in real mode with no stack, but the rest of the
+ *	trampoline page to make our stack and everything else
+ *	is a mystery.
+ *
+ *	We jump into arch/x86/kernel/head_32.S.
+ *
+ *	On entry to trampoline_start, the processor is in real mode
+ *	with 16-bit addressing and 16-bit data.  CS has some value
+ *	and IP is zero.  Thus, we load CS to the physical segment
+ *	of the real mode code before doing anything further.
+ */
+
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/page_types.h>
+#include "realmode.h"
+
+	.text
+	.code16
+
+	.balign	PAGE_SIZE
+SYM_CODE_START(trampoline_start)
+	wbinvd			# Needed for NUMA-Q should be harmless for others
+
+	LJMPW_RM(1f)
+1:
+	mov	%cs, %ax	# Code and data in the same place
+	mov	%ax, %ds
+
+	cli			# We should be safe anyway
+
+	movl	tr_start, %eax	# where we need to go
+
+	/*
+	 * GDT tables in non default location kernel can be beyond 16MB and
+	 * lgdt will not be able to load the address as in real mode default
+	 * operand size is 16bit. Use lgdtl instead to force operand size
+	 * to 32 bit.
+	 */
+	lidtl	tr_idt			# load idt with 0, 0
+	lgdtl	tr_gdt			# load gdt with whatever is appropriate
+
+	movw	$1, %dx			# protected mode (PE) bit
+	lmsw	%dx			# into protected mode
+
+	ljmpl	$__BOOT_CS, $pa_startup_32
+SYM_CODE_END(trampoline_start)
+
+	.section ".text32","ax"
+	.code32
+SYM_CODE_START(startup_32)			# note: also used from wakeup_asm.S
+	jmp	*%eax
+SYM_CODE_END(startup_32)
+
+	.bss
+	.balign 8
+SYM_DATA_START(trampoline_header)
+	SYM_DATA_LOCAL(tr_start,	.space 4)
+	SYM_DATA_LOCAL(tr_gdt_pad,	.space 2)
+	SYM_DATA_LOCAL(tr_gdt,		.space 6)
+SYM_DATA_END(trampoline_header)
+	
+#include "trampoline_common.S"
diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
new file mode 100644
index 0000000000..c9f76fae90
--- /dev/null
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -0,0 +1,263 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *
+ *	Trampoline.S	Derived from Setup.S by Linus Torvalds
+ *
+ *	4 Jan 1997 Michael Chastain: changed to gnu as.
+ *	15 Sept 2005 Eric Biederman: 64bit PIC support
+ *
+ *	Entry: CS:IP point to the start of our code, we are
+ *	in real mode with no stack, but the rest of the
+ *	trampoline page to make our stack and everything else
+ *	is a mystery.
+ *
+ *	On entry to trampoline_start, the processor is in real mode
+ *	with 16-bit addressing and 16-bit data.  CS has some value
+ *	and IP is zero.  Thus, data addresses need to be absolute
+ *	(no relocation) and are taken with regard to r_base.
+ *
+ *	With the addition of trampoline_level4_pgt this code can
+ *	now enter a 64bit kernel that lives at arbitrary 64bit
+ *	physical addresses.
+ *
+ *	If you work on this file, check the object module with objdump
+ *	--full-contents --reloc to make sure there are no relocation
+ *	entries.
+ */
+
+#include <linux/linkage.h>
+#include <asm/pgtable_types.h>
+#include <asm/page_types.h>
+#include <asm/msr.h>
+#include <asm/segment.h>
+#include <asm/processor-flags.h>
+#include <asm/realmode.h>
+#include "realmode.h"
+
+	.text
+	.code16
+
+.macro LOCK_AND_LOAD_REALMODE_ESP lock_pa=0
+	/*
+	 * Make sure only one CPU fiddles with the realmode stack
+	 */
+.Llock_rm\@:
+	.if \lock_pa
+        lock btsl       $0, pa_tr_lock
+	.else
+        lock btsl       $0, tr_lock
+	.endif
+        jnc             2f
+        pause
+        jmp             .Llock_rm\@
+2:
+	# Setup stack
+	movl	$rm_stack_end, %esp
+.endm
+
+	.balign	PAGE_SIZE
+SYM_CODE_START(trampoline_start)
+	cli			# We should be safe anyway
+	wbinvd
+
+	LJMPW_RM(1f)
+1:
+	mov	%cs, %ax	# Code and data in the same place
+	mov	%ax, %ds
+	mov	%ax, %es
+	mov	%ax, %ss
+
+	LOCK_AND_LOAD_REALMODE_ESP
+
+	call	verify_cpu		# Verify the cpu supports long mode
+	testl   %eax, %eax		# Check for return code
+	jnz	no_longmode
+
+.Lswitch_to_protected:
+	/*
+	 * GDT tables in non default location kernel can be beyond 16MB and
+	 * lgdt will not be able to load the address as in real mode default
+	 * operand size is 16bit. Use lgdtl instead to force operand size
+	 * to 32 bit.
+	 */
+
+	lidtl	tr_idt	# load idt with 0, 0
+	lgdtl	tr_gdt	# load gdt with whatever is appropriate
+
+	movw	$__KERNEL_DS, %dx	# Data segment descriptor
+
+	# Enable protected mode
+	movl	$(CR0_STATE & ~X86_CR0_PG), %eax
+	movl	%eax, %cr0		# into protected mode
+
+	# flush prefetch and jump to startup_32
+	ljmpl	$__KERNEL32_CS, $pa_startup_32
+
+no_longmode:
+	hlt
+	jmp no_longmode
+SYM_CODE_END(trampoline_start)
+
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+/* SEV-ES supports non-zero IP for entry points - no alignment needed */
+SYM_CODE_START(sev_es_trampoline_start)
+	cli			# We should be safe anyway
+
+	LJMPW_RM(1f)
+1:
+	mov	%cs, %ax	# Code and data in the same place
+	mov	%ax, %ds
+	mov	%ax, %es
+	mov	%ax, %ss
+
+	LOCK_AND_LOAD_REALMODE_ESP
+
+	jmp	.Lswitch_to_protected
+SYM_CODE_END(sev_es_trampoline_start)
+#endif	/* CONFIG_AMD_MEM_ENCRYPT */
+
+#include "../kernel/verify_cpu.S"
+
+	.section ".text32","ax"
+	.code32
+	.balign 4
+SYM_CODE_START(startup_32)
+	movl	%edx, %ss
+	addl	$pa_real_mode_base, %esp
+	movl	%edx, %ds
+	movl	%edx, %es
+	movl	%edx, %fs
+	movl	%edx, %gs
+
+	/*
+	 * Check for memory encryption support. This is a safety net in
+	 * case BIOS hasn't done the necessary step of setting the bit in
+	 * the MSR for this AP. If SME is active and we've gotten this far
+	 * then it is safe for us to set the MSR bit and continue. If we
+	 * don't we'll eventually crash trying to execute encrypted
+	 * instructions.
+	 */
+	btl	$TH_FLAGS_SME_ACTIVE_BIT, pa_tr_flags
+	jnc	.Ldone
+	movl	$MSR_AMD64_SYSCFG, %ecx
+	rdmsr
+	bts	$MSR_AMD64_SYSCFG_MEM_ENCRYPT_BIT, %eax
+	jc	.Ldone
+
+	/*
+	 * Memory encryption is enabled but the SME enable bit for this
+	 * CPU has has not been set.  It is safe to set it, so do so.
+	 */
+	wrmsr
+.Ldone:
+
+	movl	pa_tr_cr4, %eax
+	movl	%eax, %cr4		# Enable PAE mode
+
+	# Setup trampoline 4 level pagetables
+	movl	$pa_trampoline_pgd, %eax
+	movl	%eax, %cr3
+
+	# Set up EFER
+	movl	$MSR_EFER, %ecx
+	rdmsr
+	/*
+	 * Skip writing to EFER if the register already has desired
+	 * value (to avoid #VE for the TDX guest).
+	 */
+	cmp	pa_tr_efer, %eax
+	jne	.Lwrite_efer
+	cmp	pa_tr_efer + 4, %edx
+	je	.Ldone_efer
+.Lwrite_efer:
+	movl	pa_tr_efer, %eax
+	movl	pa_tr_efer + 4, %edx
+	wrmsr
+
+.Ldone_efer:
+	# Enable paging and in turn activate Long Mode.
+	movl	$CR0_STATE, %eax
+	movl	%eax, %cr0
+
+	/*
+	 * At this point we're in long mode but in 32bit compatibility mode
+	 * with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn
+	 * EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use
+	 * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
+	 */
+	ljmpl	$__KERNEL_CS, $pa_startup_64
+SYM_CODE_END(startup_32)
+
+SYM_CODE_START(pa_trampoline_compat)
+	/*
+	 * In compatibility mode.  Prep ESP and DX for startup_32, then disable
+	 * paging and complete the switch to legacy 32-bit mode.
+	 */
+	LOCK_AND_LOAD_REALMODE_ESP lock_pa=1
+	movw	$__KERNEL_DS, %dx
+
+	movl	$(CR0_STATE & ~X86_CR0_PG), %eax
+	movl	%eax, %cr0
+	ljmpl   $__KERNEL32_CS, $pa_startup_32
+SYM_CODE_END(pa_trampoline_compat)
+
+	.section ".text64","ax"
+	.code64
+	.balign 4
+SYM_CODE_START(startup_64)
+	# Now jump into the kernel using virtual addresses
+	jmpq	*tr_start(%rip)
+SYM_CODE_END(startup_64)
+
+SYM_CODE_START(trampoline_start64)
+	/*
+	 * APs start here on a direct transfer from 64-bit BIOS with identity
+	 * mapped page tables.  Load the kernel's GDT in order to gear down to
+	 * 32-bit mode (to handle 4-level vs. 5-level paging), and to (re)load
+	 * segment registers.  Load the zero IDT so any fault triggers a
+	 * shutdown instead of jumping back into BIOS.
+	 */
+	lidt	tr_idt(%rip)
+	lgdt	tr_gdt64(%rip)
+
+	ljmpl	*tr_compat(%rip)
+SYM_CODE_END(trampoline_start64)
+
+	.section ".rodata","a"
+	# Duplicate the global descriptor table
+	# so the kernel can live anywhere
+	.balign	16
+SYM_DATA_START(tr_gdt)
+	.short	tr_gdt_end - tr_gdt - 1	# gdt limit
+	.long	pa_tr_gdt
+	.short	0
+	.quad	0x00cf9b000000ffff	# __KERNEL32_CS
+	.quad	0x00af9b000000ffff	# __KERNEL_CS
+	.quad	0x00cf93000000ffff	# __KERNEL_DS
+SYM_DATA_END_LABEL(tr_gdt, SYM_L_LOCAL, tr_gdt_end)
+
+SYM_DATA_START(tr_gdt64)
+	.short	tr_gdt_end - tr_gdt - 1	# gdt limit
+	.long	pa_tr_gdt
+	.long	0
+SYM_DATA_END(tr_gdt64)
+
+SYM_DATA_START(tr_compat)
+	.long	pa_trampoline_compat
+	.short	__KERNEL32_CS
+SYM_DATA_END(tr_compat)
+
+	.bss
+	.balign	PAGE_SIZE
+SYM_DATA(trampoline_pgd, .space PAGE_SIZE)
+
+	.balign	8
+SYM_DATA_START(trampoline_header)
+	SYM_DATA_LOCAL(tr_start,	.space 8)
+	SYM_DATA(tr_efer,		.space 8)
+	SYM_DATA(tr_cr4,		.space 4)
+	SYM_DATA(tr_flags,		.space 4)
+	SYM_DATA(tr_lock,		.space 4)
+SYM_DATA_END(trampoline_header)
+
+#include "trampoline_common.S"
diff --git a/arch/x86/realmode/rm/trampoline_common.S b/arch/x86/realmode/rm/trampoline_common.S
new file mode 100644
index 0000000000..4331c32c47
--- /dev/null
+++ b/arch/x86/realmode/rm/trampoline_common.S
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+	.section ".rodata","a"
+	.balign	16
+
+/*
+ * When a bootloader hands off to the kernel in 32-bit mode an
+ * IDT with a 2-byte limit and 4-byte base is needed. When a boot
+ * loader hands off to a kernel 64-bit mode the base address
+ * extends to 8-bytes. Reserve enough space for either scenario.
+ */
+SYM_DATA_START_LOCAL(tr_idt)
+	.short  0
+	.quad   0
+SYM_DATA_END(tr_idt)
diff --git a/arch/x86/realmode/rm/video-bios.c b/arch/x86/realmode/rm/video-bios.c
new file mode 100644
index 0000000000..848b25aaf1
--- /dev/null
+++ b/arch/x86/realmode/rm/video-bios.c
@@ -0,0 +1 @@
+#include "../../boot/video-bios.c"
diff --git a/arch/x86/realmode/rm/video-mode.c b/arch/x86/realmode/rm/video-mode.c
new file mode 100644
index 0000000000..2a98b7e236
--- /dev/null
+++ b/arch/x86/realmode/rm/video-mode.c
@@ -0,0 +1 @@
+#include "../../boot/video-mode.c"
diff --git a/arch/x86/realmode/rm/video-vesa.c b/arch/x86/realmode/rm/video-vesa.c
new file mode 100644
index 0000000000..413edddb51
--- /dev/null
+++ b/arch/x86/realmode/rm/video-vesa.c
@@ -0,0 +1 @@
+#include "../../boot/video-vesa.c"
diff --git a/arch/x86/realmode/rm/video-vga.c b/arch/x86/realmode/rm/video-vga.c
new file mode 100644
index 0000000000..3085f5c9d2
--- /dev/null
+++ b/arch/x86/realmode/rm/video-vga.c
@@ -0,0 +1 @@
+#include "../../boot/video-vga.c"
diff --git a/arch/x86/realmode/rm/wakemain.c b/arch/x86/realmode/rm/wakemain.c
new file mode 100644
index 0000000000..a6f4d8388a
--- /dev/null
+++ b/arch/x86/realmode/rm/wakemain.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "wakeup.h"
+#include "boot.h"
+
+static void udelay(int loops)
+{
+	while (loops--)
+		io_delay();	/* Approximately 1 us */
+}
+
+static void beep(unsigned int hz)
+{
+	u8 enable;
+
+	if (!hz) {
+		enable = 0x00;		/* Turn off speaker */
+	} else {
+		u16 div = 1193181/hz;
+
+		outb(0xb6, 0x43);	/* Ctr 2, squarewave, load, binary */
+		io_delay();
+		outb(div, 0x42);	/* LSB of counter */
+		io_delay();
+		outb(div >> 8, 0x42);	/* MSB of counter */
+		io_delay();
+
+		enable = 0x03;		/* Turn on speaker */
+	}
+	inb(0x61);		/* Dummy read of System Control Port B */
+	io_delay();
+	outb(enable, 0x61);	/* Enable timer 2 output to speaker */
+	io_delay();
+}
+
+#define DOT_HZ		880
+#define DASH_HZ		587
+#define US_PER_DOT	125000
+
+/* Okay, this is totally silly, but it's kind of fun. */
+static void send_morse(const char *pattern)
+{
+	char s;
+
+	while ((s = *pattern++)) {
+		switch (s) {
+		case '.':
+			beep(DOT_HZ);
+			udelay(US_PER_DOT);
+			beep(0);
+			udelay(US_PER_DOT);
+			break;
+		case '-':
+			beep(DASH_HZ);
+			udelay(US_PER_DOT * 3);
+			beep(0);
+			udelay(US_PER_DOT);
+			break;
+		default:	/* Assume it's a space */
+			udelay(US_PER_DOT * 3);
+			break;
+		}
+	}
+}
+
+struct port_io_ops pio_ops;
+
+void main(void)
+{
+	init_default_io_ops();
+
+	/* Kill machine if structures are wrong */
+	if (wakeup_header.real_magic != 0x12345678)
+		while (1)
+			;
+
+	if (wakeup_header.realmode_flags & 4)
+		send_morse("...-");
+
+	if (wakeup_header.realmode_flags & 1)
+		asm volatile("lcallw   $0xc000,$3");
+
+	if (wakeup_header.realmode_flags & 2) {
+		/* Need to call BIOS */
+		probe_cards(0);
+		set_mode(wakeup_header.video_mode);
+	}
+}
diff --git a/arch/x86/realmode/rm/wakeup.h b/arch/x86/realmode/rm/wakeup.h
new file mode 100644
index 0000000000..0e4fd08ae4
--- /dev/null
+++ b/arch/x86/realmode/rm/wakeup.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Definitions for the wakeup data structure at the head of the
+ * wakeup code.
+ */
+
+#ifndef ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H
+#define ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H
+
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+
+/* This must match data at wakeup.S */
+struct wakeup_header {
+	u16 video_mode;		/* Video mode number */
+	u32 pmode_entry;	/* Protected mode resume point, 32-bit only */
+	u16 pmode_cs;
+	u32 pmode_cr0;		/* Protected mode cr0 */
+	u32 pmode_cr3;		/* Protected mode cr3 */
+	u32 pmode_cr4;		/* Protected mode cr4 */
+	u32 pmode_efer_low;	/* Protected mode EFER */
+	u32 pmode_efer_high;
+	u64 pmode_gdt;
+	u32 pmode_misc_en_low;	/* Protected mode MISC_ENABLE */
+	u32 pmode_misc_en_high;
+	u32 pmode_behavior;	/* Wakeup routine behavior flags */
+	u32 realmode_flags;
+	u32 real_magic;
+	u32 signature;		/* To check we have correct structure */
+} __attribute__((__packed__));
+
+extern struct wakeup_header wakeup_header;
+#endif
+
+#define WAKEUP_HEADER_OFFSET	8
+#define WAKEUP_HEADER_SIGNATURE 0x51ee1111
+
+/* Wakeup behavior bits */
+#define WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE     0
+#define WAKEUP_BEHAVIOR_RESTORE_CR4		1
+#define WAKEUP_BEHAVIOR_RESTORE_EFER		2
+
+#endif /* ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H */
diff --git a/arch/x86/realmode/rm/wakeup_asm.S b/arch/x86/realmode/rm/wakeup_asm.S
new file mode 100644
index 0000000000..02d0ba16ae
--- /dev/null
+++ b/arch/x86/realmode/rm/wakeup_asm.S
@@ -0,0 +1,179 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * ACPI wakeup real mode startup stub
+ */
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/msr-index.h>
+#include <asm/page_types.h>
+#include <asm/pgtable_types.h>
+#include <asm/processor-flags.h>
+#include "realmode.h"
+#include "wakeup.h"
+
+	.code16
+
+/* This should match the structure in wakeup.h */
+	.section ".data", "aw"
+
+	.balign	16
+SYM_DATA_START(wakeup_header)
+	video_mode:	.short	0	/* Video mode number */
+	pmode_entry:	.long	0
+	pmode_cs:	.short	__KERNEL_CS
+	pmode_cr0:	.long	0	/* Saved %cr0 */
+	pmode_cr3:	.long	0	/* Saved %cr3 */
+	pmode_cr4:	.long	0	/* Saved %cr4 */
+	pmode_efer:	.quad	0	/* Saved EFER */
+	pmode_gdt:	.quad	0
+	pmode_misc_en:	.quad	0	/* Saved MISC_ENABLE MSR */
+	pmode_behavior:	.long	0	/* Wakeup behavior flags */
+	realmode_flags:	.long	0
+	real_magic:	.long	0
+	signature:	.long	WAKEUP_HEADER_SIGNATURE
+SYM_DATA_END(wakeup_header)
+
+	.text
+	.code16
+
+	.balign	16
+SYM_CODE_START(wakeup_start)
+	cli
+	cld
+
+	LJMPW_RM(3f)
+3:
+	/* Apparently some dimwit BIOS programmers don't know how to
+	   program a PM to RM transition, and we might end up here with
+	   junk in the data segment descriptor registers.  The only way
+	   to repair that is to go into PM and fix it ourselves... */
+	movw	$16, %cx
+	lgdtl	%cs:wakeup_gdt
+	movl	%cr0, %eax
+	orb	$X86_CR0_PE, %al
+	movl	%eax, %cr0
+	ljmpw	$8, $2f
+2:
+	movw	%cx, %ds
+	movw	%cx, %es
+	movw	%cx, %ss
+	movw	%cx, %fs
+	movw	%cx, %gs
+
+	andb	$~X86_CR0_PE, %al
+	movl	%eax, %cr0
+	LJMPW_RM(3f)
+3:
+	/* Set up segments */
+	movw	%cs, %ax
+	movw	%ax, %ss
+	movl	$rm_stack_end, %esp
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+
+	lidtl	.Lwakeup_idt
+
+	/* Clear the EFLAGS */
+	pushl $0
+	popfl
+
+	/* Check header signature... */
+	movl	signature, %eax
+	cmpl	$WAKEUP_HEADER_SIGNATURE, %eax
+	jne	bogus_real_magic
+
+	/* Check we really have everything... */
+	movl	end_signature, %eax
+	cmpl	$REALMODE_END_SIGNATURE, %eax
+	jne	bogus_real_magic
+
+	/* Call the C code */
+	calll	main
+
+	/* Restore MISC_ENABLE before entering protected mode, in case
+	   BIOS decided to clear XD_DISABLE during S3. */
+	movl	pmode_behavior, %edi
+	btl	$WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE, %edi
+	jnc	1f
+
+	movl	pmode_misc_en, %eax
+	movl	pmode_misc_en + 4, %edx
+	movl	$MSR_IA32_MISC_ENABLE, %ecx
+	wrmsr
+1:
+
+	/* Do any other stuff... */
+
+#ifndef CONFIG_64BIT
+	/* This could also be done in C code... */
+	movl	pmode_cr3, %eax
+	movl	%eax, %cr3
+
+	btl	$WAKEUP_BEHAVIOR_RESTORE_CR4, %edi
+	jnc	1f
+	movl	pmode_cr4, %eax
+	movl	%eax, %cr4
+1:
+	btl	$WAKEUP_BEHAVIOR_RESTORE_EFER, %edi
+	jnc	1f
+	movl	pmode_efer, %eax
+	movl	pmode_efer + 4, %edx
+	movl	$MSR_EFER, %ecx
+	wrmsr
+1:
+
+	lgdtl	pmode_gdt
+
+	/* This really couldn't... */
+	movl	pmode_entry, %eax
+	movl	pmode_cr0, %ecx
+	movl	%ecx, %cr0
+	ljmpl	$__KERNEL_CS, $pa_startup_32
+	/* -> jmp *%eax in trampoline_32.S */
+#else
+	jmp	trampoline_start
+#endif
+SYM_CODE_END(wakeup_start)
+
+bogus_real_magic:
+1:
+	hlt
+	jmp	1b
+
+	.section ".rodata","a"
+
+	/*
+	 * Set up the wakeup GDT.  We set these up as Big Real Mode,
+	 * that is, with limits set to 4 GB.  At least the Lenovo
+	 * Thinkpad X61 is known to need this for the video BIOS
+	 * initialization quirk to work; this is likely to also
+	 * be the case for other laptops or integrated video devices.
+	 */
+
+	.balign	16
+SYM_DATA_START(wakeup_gdt)
+	.word	3*8-1		/* Self-descriptor */
+	.long	pa_wakeup_gdt
+	.word	0
+
+	.word	0xffff		/* 16-bit code segment @ real_mode_base */
+	.long	0x9b000000 + pa_real_mode_base
+	.word	0x008f		/* big real mode */
+
+	.word	0xffff		/* 16-bit data segment @ real_mode_base */
+	.long	0x93000000 + pa_real_mode_base
+	.word	0x008f		/* big real mode */
+SYM_DATA_END(wakeup_gdt)
+
+	.section ".rodata","a"
+	.balign	8
+
+	/* This is the standard real-mode IDT */
+	.balign	16
+SYM_DATA_START_LOCAL(.Lwakeup_idt)
+	.word	0xffff		/* limit */
+	.long	0		/* address */
+	.word	0
+SYM_DATA_END(.Lwakeup_idt)
diff --git a/arch/x86/realmode/rmpiggy.S b/arch/x86/realmode/rmpiggy.S
new file mode 100644
index 0000000000..c8fef76743
--- /dev/null
+++ b/arch/x86/realmode/rmpiggy.S
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Wrapper script for the realmode binary as a transport object
+ * before copying to low memory.
+ */
+#include <linux/linkage.h>
+#include <asm/page_types.h>
+
+	.section ".init.data","aw"
+
+	.balign PAGE_SIZE
+
+SYM_DATA_START(real_mode_blob)
+	.incbin	"arch/x86/realmode/rm/realmode.bin"
+SYM_DATA_END_LABEL(real_mode_blob, SYM_L_GLOBAL, real_mode_blob_end)
+
+SYM_DATA_START(real_mode_relocs)
+	.incbin	"arch/x86/realmode/rm/realmode.relocs"
+SYM_DATA_END(real_mode_relocs)