[deliverable/linux.git] / arch / x86 / boot / pm.c

/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright (C) 1991, 1992 Linus Torvalds
 *   Copyright 2007 rPath, Inc. - All Rights Reserved
 *
 *   This file is part of the Linux kernel, and is made available under
 *   the terms of the GNU General Public License version 2.
 *
 * ----------------------------------------------------------------------- */

/*
 * Prepare the machine for transition to protected mode.
 */

#include "boot.h"
#include <asm/segment.h>

/*
 * Invoke the realmode switch hook if present; otherwise
 * disable all interrupts.
 */
static void realmode_switch_hook(void)
{
	if (boot_params.hdr.realmode_swtch) {
		asm volatile("lcallw *%0"
			     : : "m" (boot_params.hdr.realmode_swtch)
			     : "eax", "ebx", "ecx", "edx");
	} else {
		asm volatile("cli");
		outb(0x80, 0x70); /* Disable NMI */
		io_delay();
	}
}

/*
 * Disable all interrupts at the legacy PIC.
 */
static void mask_all_interrupts(void)
{
	outb(0xff, 0xa1);	/* Mask all interrupts on the secondary PIC */
	io_delay();
	outb(0xfb, 0x21);	/* Mask all but cascade on the primary PIC */
	io_delay();
}

/*
 * Reset IGNNE# if asserted in the FPU.
 */
static void reset_coprocessor(void)
{
	outb(0, 0xf0);
	io_delay();
	outb(0, 0xf1);
	io_delay();
}

/*
 * Set up the GDT
 */

struct gdt_ptr {
	u16 len;
	u32 ptr;
} __attribute__((packed));

static void setup_gdt(void)
{
	/* There are machines which are known to not boot with the GDT
	   being 8-byte unaligned.  Intel recommends 16 byte alignment. */
	static const u64 boot_gdt[] __attribute__((aligned(16))) = {
		/* CS: code, read/execute, 4 GB, base 0 */
		[GDT_ENTRY_BOOT_CS] = GDT_ENTRY(0xc09b, 0, 0xfffff),
		/* DS: data, read/write, 4 GB, base 0 */
		[GDT_ENTRY_BOOT_DS] = GDT_ENTRY(0xc093, 0, 0xfffff),
		/* TSS: 32-bit tss, 104 bytes, base 4096 */
		/* We only have a TSS here to keep Intel VT happy;
		   we don't actually use it for anything. */
		[GDT_ENTRY_BOOT_TSS] = GDT_ENTRY(0x0089, 4096, 103),
	};
	/* Xen HVM incorrectly stores a pointer to the gdt_ptr, instead
	   of the gdt_ptr contents.  Thus, make it static so it will
	   stay in memory, at least long enough that we switch to the
	   proper kernel GDT. */
	static struct gdt_ptr gdt;

	gdt.len = sizeof(boot_gdt)-1;
	gdt.ptr = (u32)&boot_gdt + (ds() << 4);

	asm volatile("lgdtl %0" : : "m" (gdt));
}

/*
 * Set up the IDT
 */
static void setup_idt(void)
{
	static const struct gdt_ptr null_idt = {0, 0};
	asm volatile("lidtl %0" : : "m" (null_idt));
}

/*
 * Actual invocation sequence
 */
void go_to_protected_mode(void)
{
	/* Hook before leaving real mode, also disables interrupts */
	realmode_switch_hook();

	/* Enable the A20 gate */
	if (enable_a20()) {
		puts("A20 gate not responding, unable to boot...\n");
		die();
	}

	/* Reset coprocessor (IGNNE#) */
	reset_coprocessor();

	/* Mask all interrupts in the PIC */
	mask_all_interrupts();

	/* Actual transition to protected mode... */
	setup_idt();
	setup_gdt();
	protected_mode_jump(boot_params.hdr.code32_start,
			    (u32)&boot_params + (ds() << 4));
}
Commit	Line	Data
7052fdd8 PA	1	/* -- linux-c -- ------------------------------------------------------- *
	2	*
	3	* Copyright (C) 1991, 1992 Linus Torvalds
	4	* Copyright 2007 rPath, Inc. - All Rights Reserved
	5	*
	6	* This file is part of the Linux kernel, and is made available under
	7	* the terms of the GNU General Public License version 2.
	8	*
	9	* ----------------------------------------------------------------------- */
	10
	11	/*
7052fdd8 PA	12	* Prepare the machine for transition to protected mode.
	13	*/
	14
	15	#include "boot.h"
	16	#include <asm/segment.h>
	17
	18	/*
	19	* Invoke the realmode switch hook if present; otherwise
	20	* disable all interrupts.
	21	*/
	22	static void realmode_switch_hook(void)
	23	{
	24	if (boot_params.hdr.realmode_swtch) {
	25	asm volatile("lcallw *%0"
	26	: : "m" (boot_params.hdr.realmode_swtch)
	27	: "eax", "ebx", "ecx", "edx");
	28	} else {
	29	asm volatile("cli");
	30	outb(0x80, 0x70); /* Disable NMI */
	31	io_delay();
	32	}
	33	}
	34
7052fdd8 PA	35	/*
	36	* Disable all interrupts at the legacy PIC.
	37	*/
	38	static void mask_all_interrupts(void)
	39	{
8218d029	40	outb(0xff, 0xa1); /* Mask all interrupts on the secondary PIC */
7052fdd8 PA	41	io_delay();
	42	outb(0xfb, 0x21); /* Mask all but cascade on the primary PIC */
	43	io_delay();
	44	}
	45
	46	/*
	47	* Reset IGNNE# if asserted in the FPU.
	48	*/
	49	static void reset_coprocessor(void)
	50	{
	51	outb(0, 0xf0);
	52	io_delay();
	53	outb(0, 0xf1);
	54	io_delay();
	55	}
	56
	57	/*
	58	* Set up the GDT
	59	*/
7052fdd8 PA	60
	61	struct gdt_ptr {
	62	u16 len;
	63	u32 ptr;
	64	} __attribute__((packed));
	65
	66	static void setup_gdt(void)
	67	{
	68	/* There are machines which are known to not boot with the GDT
	69	being 8-byte unaligned. Intel recommends 16 byte alignment. */
	70	static const u64 boot_gdt[] __attribute__((aligned(16))) = {
	71	/* CS: code, read/execute, 4 GB, base 0 */
	72	[GDT_ENTRY_BOOT_CS] = GDT_ENTRY(0xc09b, 0, 0xfffff),
	73	/* DS: data, read/write, 4 GB, base 0 */
	74	[GDT_ENTRY_BOOT_DS] = GDT_ENTRY(0xc093, 0, 0xfffff),
88089519 PA	75	/* TSS: 32-bit tss, 104 bytes, base 4096 */
	76	/* We only have a TSS here to keep Intel VT happy;
	77	we don't actually use it for anything. */
	78	[GDT_ENTRY_BOOT_TSS] = GDT_ENTRY(0x0089, 4096, 103),
7052fdd8	79	};
ce29a1f8 CE	80	/* Xen HVM incorrectly stores a pointer to the gdt_ptr, instead
	81	of the gdt_ptr contents. Thus, make it static so it will
	82	stay in memory, at least long enough that we switch to the
	83	proper kernel GDT. */
	84	static struct gdt_ptr gdt;
7052fdd8 PA	85
	86	gdt.len = sizeof(boot_gdt)-1;
	87	gdt.ptr = (u32)&boot_gdt + (ds() << 4);
	88
	89	asm volatile("lgdtl %0" : : "m" (gdt));
	90	}
	91
	92	/*
	93	* Set up the IDT
	94	*/
	95	static void setup_idt(void)
	96	{
	97	static const struct gdt_ptr null_idt = {0, 0};
	98	asm volatile("lidtl %0" : : "m" (null_idt));
	99	}
	100
	101	/*
	102	* Actual invocation sequence
	103	*/
	104	void go_to_protected_mode(void)
	105	{
	106	/* Hook before leaving real mode, also disables interrupts */
	107	realmode_switch_hook();
	108
7052fdd8 PA	109	/* Enable the A20 gate */
	110	if (enable_a20()) {
	111	puts("A20 gate not responding, unable to boot...\n");
	112	die();
	113	}
	114
	115	/* Reset coprocessor (IGNNE#) */
	116	reset_coprocessor();
	117
	118	/* Mask all interrupts in the PIC */
	119	mask_all_interrupts();
	120
	121	/* Actual transition to protected mode... */
	122	setup_idt();
	123	setup_gdt();
	124	protected_mode_jump(boot_params.hdr.code32_start,
	125	(u32)&boot_params + (ds() << 4));
	126	}