1/*
2 *
3 *	Trampoline.S	Derived from Setup.S by Linus Torvalds
4 *
5 *	4 Jan 1997 Michael Chastain: changed to gnu as.
6 *
7 *	This is only used for booting secondary CPUs in SMP machine
8 *
9 *	Entry: CS:IP point to the start of our code, we are
10 *	in real mode with no stack, but the rest of the
11 *	trampoline page to make our stack and everything else
12 *	is a mystery.
13 *
14 *	We jump into arch/x86/kernel/head_32.S.
15 *
16 *	On entry to trampoline_start, the processor is in real mode
17 *	with 16-bit addressing and 16-bit data.  CS has some value
18 *	and IP is zero.  Thus, we load CS to the physical segment
19 *	of the real mode code before doing anything further.
20 */
21
22#include <linux/linkage.h>
23#include <asm/segment.h>
24#include <asm/page_types.h>
25#include "realmode.h"
26
27	.text
28	.code16
29
30	.balign	PAGE_SIZE
31ENTRY(trampoline_start)
32	wbinvd			# Needed for NUMA-Q should be harmless for others
33
34	LJMPW_RM(1f)
351:
36	mov	%cs, %ax	# Code and data in the same place
37	mov	%ax, %ds
38
39	cli			# We should be safe anyway
40
41	movl	tr_start, %eax	# where we need to go
42
43	movl	$0xA5A5A5A5, trampoline_status
44				# write marker for master knows we're running
45
46	/*
47	 * GDT tables in non default location kernel can be beyond 16MB and
48	 * lgdt will not be able to load the address as in real mode default
49	 * operand size is 16bit. Use lgdtl instead to force operand size
50	 * to 32 bit.
51	 */
52	lidtl	tr_idt			# load idt with 0, 0
53	lgdtl	tr_gdt			# load gdt with whatever is appropriate
54
55	movw	$1, %dx			# protected mode (PE) bit
56	lmsw	%dx			# into protected mode
57
58	ljmpl	$__BOOT_CS, $pa_startup_32
59
60	.section ".text32","ax"
61	.code32
62ENTRY(startup_32)			# note: also used from wakeup_asm.S
63	jmp	*%eax
64
65	.bss
66	.balign 8
67GLOBAL(trampoline_header)
68	tr_start:		.space	4
69	tr_gdt_pad:		.space	2
70	tr_gdt:			.space	6
71END(trampoline_header)
72
73#include "trampoline_common.S"
74