aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--arch/i386/boot/pm.c170
-rw-r--r--arch/i386/boot/pmjump.S54
2 files changed, 224 insertions, 0 deletions
diff --git a/arch/i386/boot/pm.c b/arch/i386/boot/pm.c
new file mode 100644
index 000000000000..3fa53e15ed77
--- /dev/null
+++ b/arch/i386/boot/pm.c
@@ -0,0 +1,170 @@
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/*
12 * arch/i386/boot/pm.c
13 *
14 * Prepare the machine for transition to protected mode.
15 */
16
17#include "boot.h"
18#include <asm/segment.h>
19
20/*
21 * Invoke the realmode switch hook if present; otherwise
22 * disable all interrupts.
23 */
24static void realmode_switch_hook(void)
25{
26 if (boot_params.hdr.realmode_swtch) {
27 asm volatile("lcallw *%0"
28 : : "m" (boot_params.hdr.realmode_swtch)
29 : "eax", "ebx", "ecx", "edx");
30 } else {
31 asm volatile("cli");
32 outb(0x80, 0x70); /* Disable NMI */
33 io_delay();
34 }
35}
36
37/*
38 * A zImage kernel is loaded at 0x10000 but wants to run at 0x1000.
39 * A bzImage kernel is loaded and runs at 0x100000.
40 */
41static void move_kernel_around(void)
42{
43 /* Note: rely on the compile-time option here rather than
44 the LOADED_HIGH flag. The Qemu kernel loader unconditionally
45 sets the loadflags to zero. */
46#ifndef __BIG_KERNEL__
47 u16 dst_seg, src_seg;
48 u32 syssize;
49
50 dst_seg = 0x1000 >> 4;
51 src_seg = 0x10000 >> 4;
52 syssize = boot_params.hdr.syssize; /* Size in 16-byte paragraphs */
53
54 while (syssize) {
55 int paras = (syssize >= 0x1000) ? 0x1000 : syssize;
56 int dwords = paras << 2;
57
58 asm volatile("pushw %%es ; "
59 "pushw %%ds ; "
60 "movw %1,%%es ; "
61 "movw %2,%%ds ; "
62 "xorw %%di,%%di ; "
63 "xorw %%si,%%si ; "
64 "rep;movsl ; "
65 "popw %%ds ; "
66 "popw %%es"
67 : "+c" (dwords)
68 : "rm" (dst_seg), "rm" (src_seg)
69 : "esi", "edi");
70
71 syssize -= paras;
72 dst_seg += paras;
73 src_seg += paras;
74 }
75#endif
76}
77
78/*
79 * Disable all interrupts at the legacy PIC.
80 */
81static void mask_all_interrupts(void)
82{
83 outb(0xff, 0xa1); /* Mask all interrupts on the seconday PIC */
84 io_delay();
85 outb(0xfb, 0x21); /* Mask all but cascade on the primary PIC */
86 io_delay();
87}
88
89/*
90 * Reset IGNNE# if asserted in the FPU.
91 */
92static void reset_coprocessor(void)
93{
94 outb(0, 0xf0);
95 io_delay();
96 outb(0, 0xf1);
97 io_delay();
98}
99
100/*
101 * Set up the GDT
102 */
103#define GDT_ENTRY(flags,base,limit) \
104 (((u64)(base & 0xff000000) << 32) | \
105 ((u64)flags << 40) | \
106 ((u64)(limit & 0x00ff0000) << 32) | \
107 ((u64)(base & 0x00ffff00) << 16) | \
108 ((u64)(limit & 0x0000ffff)))
109
110struct gdt_ptr {
111 u16 len;
112 u32 ptr;
113} __attribute__((packed));
114
115static void setup_gdt(void)
116{
117 /* There are machines which are known to not boot with the GDT
118 being 8-byte unaligned. Intel recommends 16 byte alignment. */
119 static const u64 boot_gdt[] __attribute__((aligned(16))) = {
120 /* CS: code, read/execute, 4 GB, base 0 */
121 [GDT_ENTRY_BOOT_CS] = GDT_ENTRY(0xc09b, 0, 0xfffff),
122 /* DS: data, read/write, 4 GB, base 0 */
123 [GDT_ENTRY_BOOT_DS] = GDT_ENTRY(0xc093, 0, 0xfffff),
124 };
125 struct gdt_ptr gdt;
126
127 gdt.len = sizeof(boot_gdt)-1;
128 gdt.ptr = (u32)&boot_gdt + (ds() << 4);
129
130 asm volatile("lgdtl %0" : : "m" (gdt));
131}
132
133/*
134 * Set up the IDT
135 */
136static void setup_idt(void)
137{
138 static const struct gdt_ptr null_idt = {0, 0};
139 asm volatile("lidtl %0" : : "m" (null_idt));
140}
141
142/*
143 * Actual invocation sequence
144 */
145void go_to_protected_mode(void)
146{
147 /* Hook before leaving real mode, also disables interrupts */
148 realmode_switch_hook();
149
150 /* Move the kernel/setup to their final resting places */
151 move_kernel_around();
152
153 /* Enable the A20 gate */
154 if (enable_a20()) {
155 puts("A20 gate not responding, unable to boot...\n");
156 die();
157 }
158
159 /* Reset coprocessor (IGNNE#) */
160 reset_coprocessor();
161
162 /* Mask all interrupts in the PIC */
163 mask_all_interrupts();
164
165 /* Actual transition to protected mode... */
166 setup_idt();
167 setup_gdt();
168 protected_mode_jump(boot_params.hdr.code32_start,
169 (u32)&boot_params + (ds() << 4));
170}
diff --git a/arch/i386/boot/pmjump.S b/arch/i386/boot/pmjump.S
new file mode 100644
index 000000000000..2e559233725a
--- /dev/null
+++ b/arch/i386/boot/pmjump.S
@@ -0,0 +1,54 @@
1/* ----------------------------------------------------------------------- *
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/*
12 * arch/i386/boot/pmjump.S
13 *
14 * The actual transition into protected mode
15 */
16
17#include <asm/boot.h>
18#include <asm/segment.h>
19
20 .text
21
22 .globl protected_mode_jump
23 .type protected_mode_jump, @function
24
25 .code16
26
27/*
28 * void protected_mode_jump(u32 entrypoint, u32 bootparams);
29 */
30protected_mode_jump:
31 xorl %ebx, %ebx # Flag to indicate this is a boot
32 movl %edx, %esi # Pointer to boot_params table
33 movl %eax, 2f # Patch ljmpl instruction
34 jmp 1f # Short jump to flush instruction q.
35
361:
37 movw $__BOOT_DS, %cx
38
39 movl %cr0, %edx
40 orb $1, %dl # Protected mode (PE) bit
41 movl %edx, %cr0
42
43 movw %cx, %ds
44 movw %cx, %es
45 movw %cx, %fs
46 movw %cx, %gs
47 movw %cx, %ss
48
49 # Jump to the 32-bit entrypoint
50 .byte 0x66, 0xea # ljmpl opcode
512: .long 0 # offset
52 .word __BOOT_CS # segment
53
54 .size protected_mode_jump, .-protected_mode_jump
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-25 03:52:03 -0500