diff options
Diffstat (limited to 'src/arch/x86/wakeup.S')
| -rw-r--r-- | src/arch/x86/wakeup.S | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/src/arch/x86/wakeup.S b/src/arch/x86/wakeup.S new file mode 100644 index 0000000000..38d6ea43ae --- /dev/null +++ b/src/arch/x86/wakeup.S @@ -0,0 +1,99 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2009 Rudolf Marek <r.marek@assembler.cz> + * Copyright (C) 2009 coresystems GmbH + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc. + */ + +#define WAKEUP_BASE 0x600 +#define RELOCATED(x) (x - __wakeup + WAKEUP_BASE) + +/* CR0 bits */ +#define PE (1 << 0) + +#ifdef __x86_64__ + .code64 +#else + .code32 +#endif + + .globl __wakeup +__wakeup: + /* First prepare the jmp to the resume vector */ + mov 0x4(%esp), %eax /* vector */ + /* last 4 bits of linear addr are taken as offset */ + andw $0x0f, %ax + movw %ax, (__wakeup_offset) + mov 0x4(%esp), %eax + /* the rest is taken as segment */ + shr $4, %eax + movw %ax, (__wakeup_segment) + + /* Then overwrite coreboot with our backed up memory */ + cld + movl 8(%esp), %esi + movl 12(%esp), %edi + movl 16(%esp), %ecx + shrl $2, %ecx + rep movsl + + /* Activate the right segment descriptor real mode. */ + ljmp $0x28, $RELOCATED(1f) +1: +.code16 + /* 16 bit code from here on... */ + + /* Load the segment registers w/ properly configured + * segment descriptors. They will retain these + * configurations (limits, writability, etc.) once + * protected mode is turned off. + */ + mov $0x30, %ax + mov %ax, %ds + mov %ax, %es + mov %ax, %fs + mov %ax, %gs + mov %ax, %ss + + /* Turn off protection */ + movl %cr0, %eax + andl $~PE, %eax + movl %eax, %cr0 + + /* Now really going into real mode */ + ljmp $0, $RELOCATED(1f) +1: + movw $0x0, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %ss + movw %ax, %fs + movw %ax, %gs + + /* This is a FAR JMP to the OS waking vector. The C code changed + * the address to be correct. + */ + .byte 0xea + +__wakeup_offset = RELOCATED(.) + .word 0x0000 + +__wakeup_segment = RELOCATED(.) + .word 0x0000 + + .globl __wakeup_size +__wakeup_size: + .long . - __wakeup |