1 files changed, 101 insertions, 0 deletions

diff --git a/arch/x86/purgatory/entry64.S b/arch/x86/purgatory/entry64.S
new file mode 100644
index 000000000000..be3249d7ed2d
--- /dev/null
+++ b/arch/x86/purgatory/entry64.S
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2003,2004  Eric Biederman (ebiederm@xmission.com)
+ * Copyright (C) 2014  Red Hat Inc.
+
+ * Author(s): Vivek Goyal <vgoyal@redhat.com>
+ *
+ * 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
+        .balign 16
+        .code64
+        .globl entry64, entry64_regs
+
+
+entry64:
+        /* Setup a gdt that should be preserved */
+        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 new stack */
+        leaq    stack_init(%rip), %rsp
+        pushq   $0x10 /* CS */
+        leaq    new_cs_exit(%rip), %rax
+        pushq   %rax
+        lretq
+new_cs_exit:
+
+        /* Load the registers */
+        movq    rax(%rip), %rax
+        movq    rbx(%rip), %rbx
+        movq    rcx(%rip), %rcx
+        movq    rdx(%rip), %rdx
+        movq    rsi(%rip), %rsi
+        movq    rdi(%rip), %rdi
+        movq    rsp(%rip), %rsp
+        movq    rbp(%rip), %rbp
+        movq    r8(%rip), %r8
+        movq    r9(%rip), %r9
+        movq    r10(%rip), %r10
+        movq    r11(%rip), %r11
+        movq    r12(%rip), %r12
+        movq    r13(%rip), %r13
+        movq    r14(%rip), %r14
+        movq    r15(%rip), %r15
+
+        /* Jump to the new code... */
+        jmpq    *rip(%rip)
+
+        .section ".rodata"
+        .balign 4
+entry64_regs:
+rax:    .quad 0x0
+rbx:    .quad 0x0
+rcx:    .quad 0x0
+rdx:    .quad 0x0
+rsi:    .quad 0x0
+rdi:    .quad 0x0
+rsp:    .quad 0x0
+rbp:    .quad 0x0
+r8:     .quad 0x0
+r9:     .quad 0x0
+r10:    .quad 0x0
+r11:    .quad 0x0
+r12:    .quad 0x0
+r13:    .quad 0x0
+r14:    .quad 0x0
+r15:    .quad 0x0
+rip:    .quad 0x0
+        .size entry64_regs, . - entry64_regs
+
+        /* GDT */
+        .section ".rodata"
+        .balign 16
+gdt:
+        /* 0x00 unusable segment
+         * 0x08 unused
+         * so use them as 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:
+stack:  .quad   0, 0
+stack_init: