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-rw-r--r--src/arch/x86/wakeup.S99
1 files changed, 99 insertions, 0 deletions
diff --git a/src/arch/x86/wakeup.S b/src/arch/x86/wakeup.S
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+/*
+ * 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