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-rw-r--r--arch/x86/purgatory/setup-x86_64.S58
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/x86/purgatory/setup-x86_64.S b/arch/x86/purgatory/setup-x86_64.S
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index 000000000000..fe3c91ba1bd0
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+/*
+ * purgatory: setup code
+ *
+ * Copyright (C) 2003,2004 Eric Biederman (ebiederm@xmission.com)
+ * Copyright (C) 2014 Red Hat Inc.
+ *
+ * This code has been taken from kexec-tools.
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+ .text
+ .globl purgatory_start
+ .balign 16
+purgatory_start:
+ .code64
+
+ /* Load a gdt so I know what the segment registers are */
+ lgdt gdt(%rip)
+
+ /* load the data segments */
+ movl $0x18, %eax /* data segment */
+ movl %eax, %ds
+ movl %eax, %es
+ movl %eax, %ss
+ movl %eax, %fs
+ movl %eax, %gs
+
+ /* Setup a stack */
+ leaq lstack_end(%rip), %rsp
+
+ /* Call the C code */
+ call purgatory
+ jmp entry64
+
+ .section ".rodata"
+ .balign 16
+gdt: /* 0x00 unusable segment
+ * 0x08 unused
+ * so use them as the gdt ptr
+ */
+ .word gdt_end - gdt - 1
+ .quad gdt
+ .word 0, 0, 0
+
+ /* 0x10 4GB flat code segment */
+ .word 0xFFFF, 0x0000, 0x9A00, 0x00AF
+
+ /* 0x18 4GB flat data segment */
+ .word 0xFFFF, 0x0000, 0x9200, 0x00CF
+gdt_end:
+
+ .bss
+ .balign 4096
+lstack:
+ .skip 4096
+lstack_end: