1 files changed, 73 insertions, 0 deletions
diff --git a/arch/x86/realmode/rm/trampoline_32.S b/arch/x86/realmode/rm/trampoline_32.S
new file mode 100644
index 000000000..3fad907a1
--- /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"