[linux-2.6-block.git] / arch / x86 / realmode / rm / trampoline_32.S

/* 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"
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
48927bbb JS	2	/*
	3	*
	4	* Trampoline.S Derived from Setup.S by Linus Torvalds
	5	*
	6	* 4 Jan 1997 Michael Chastain: changed to gnu as.
	7	*
	8	* This is only used for booting secondary CPUs in SMP machine
	9	*
	10	* Entry: CS:IP point to the start of our code, we are
	11	* in real mode with no stack, but the rest of the
	12	* trampoline page to make our stack and everything else
	13	* is a mystery.
	14	*
	15	* We jump into arch/x86/kernel/head_32.S.
	16	*
f37240f1	17	* On entry to trampoline_start, the processor is in real mode
48927bbb JS	18	* with 16-bit addressing and 16-bit data. CS has some value
	19	* and IP is zero. Thus, we load CS to the physical segment
	20	* of the real mode code before doing anything further.
48927bbb JS	21	*/
	22
	23	#include <linux/linkage.h>
48927bbb JS	24	#include <asm/segment.h>
48927bbb JS	25	#include <asm/page_types.h>
e5684ec4	26	#include "realmode.h"
48927bbb JS	27
	28	.text
	29	.code16
48927bbb	30
8e029fcd	31	.balign PAGE_SIZE
78762b0e	32	SYM_CODE_START(trampoline_start)
48927bbb JS	33	wbinvd # Needed for NUMA-Q should be harmless for others
48927bbb JS	34
e5684ec4	35	LJMPW_RM(1f)
48927bbb JS	36	1:
	37	mov %cs, %ax # Code and data in the same place
	38	mov %ax, %ds
	39
	40	cli # We should be safe anyway
	41
f37240f1	42	movl tr_start, %eax # where we need to go
968ff9ee	43
968ff9ee PA	44	/*
968ff9ee PA	45	* GDT tables in non default location kernel can be beyond 16MB and
48927bbb JS	46	* lgdt will not be able to load the address as in real mode default
	47	* operand size is 16bit. Use lgdtl instead to force operand size
	48	* to 32 bit.
	49	*/
f37240f1 JS	50	lidtl tr_idt # load idt with 0, 0
f37240f1 JS	51	lgdtl tr_gdt # load gdt with whatever is appropriate
48927bbb	52
968ff9ee PA	53	movw $1, %dx # protected mode (PE) bit
968ff9ee PA	54	lmsw %dx # into protected mode
48927bbb	55
968ff9ee	56	ljmpl $__BOOT_CS, $pa_startup_32
78762b0e	57	SYM_CODE_END(trampoline_start)
968ff9ee PA	58
	59	.section ".text32","ax"
	60	.code32
78762b0e	61	SYM_CODE_START(startup_32) # note: also used from wakeup_asm.S
968ff9ee	62	jmp *%eax
78762b0e	63	SYM_CODE_END(startup_32)
48927bbb	64
51edbe6a PA	65	.bss
51edbe6a PA	66	.balign 8
78f44330 JS	67	SYM_DATA_START(trampoline_header)
	68	SYM_DATA_LOCAL(tr_start, .space 4)
	69	SYM_DATA_LOCAL(tr_gdt_pad, .space 2)
	70	SYM_DATA_LOCAL(tr_gdt, .space 6)
	71	SYM_DATA_END(trampoline_header)
51edbe6a	72
f37240f1	73	#include "trampoline_common.S"