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-rw-r--r--arch/x86/purgatory/entry64.S103
1 files changed, 103 insertions, 0 deletions
diff --git a/arch/x86/purgatory/entry64.S b/arch/x86/purgatory/entry64.S
new file mode 100644
index 0000000000..0b4390ce58
--- /dev/null
+++ b/arch/x86/purgatory/entry64.S
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * 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.
+ */
+
+#include <linux/linkage.h>
+
+ .text
+ .balign 16
+ .code64
+
+SYM_CODE_START(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)
+SYM_CODE_END(entry64)
+
+ .section ".rodata"
+ .balign 4
+SYM_DATA_START(entry64_regs)
+rax: .quad 0x0
+rcx: .quad 0x0
+rdx: .quad 0x0
+rbx: .quad 0x0
+rsp: .quad 0x0
+rbp: .quad 0x0
+rsi: .quad 0x0
+rdi: .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
+SYM_DATA_END(entry64_regs)
+
+ /* GDT */
+ .section ".rodata"
+ .balign 16
+SYM_DATA_START_LOCAL(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
+SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)
+
+SYM_DATA_START_LOCAL(stack)
+ .quad 0, 0
+SYM_DATA_END_LABEL(stack, SYM_L_LOCAL, stack_init)