/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* relocate_kernel.S - put the kernel image in place to boot
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* Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com>
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*/
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#include <linux/linkage.h>
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#include <asm/page_types.h>
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#include <asm/kexec.h>
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#include <asm/processor-flags.h>
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#include <asm/pgtable_types.h>
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#include <asm/nospec-branch.h>
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#include <asm/unwind_hints.h>
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/*
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* Must be relocatable PIC code callable as a C function, in particular
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* there must be a plain RET and not jump to return thunk.
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*/
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#define PTR(x) (x << 3)
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#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
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/*
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* control_page + KEXEC_CONTROL_CODE_MAX_SIZE
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* ~ control_page + PAGE_SIZE are used as data storage and stack for
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* jumping back
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*/
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#define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
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/* Minimal CPU state */
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#define RSP DATA(0x0)
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#define CR0 DATA(0x8)
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#define CR3 DATA(0x10)
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#define CR4 DATA(0x18)
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/* other data */
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#define CP_PA_TABLE_PAGE DATA(0x20)
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#define CP_PA_SWAP_PAGE DATA(0x28)
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#define CP_PA_BACKUP_PAGES_MAP DATA(0x30)
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.text
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.align PAGE_SIZE
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.code64
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SYM_CODE_START_NOALIGN(relocate_kernel)
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UNWIND_HINT_EMPTY
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/*
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* %rdi indirection_page
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* %rsi page_list
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* %rdx start address
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* %rcx preserve_context
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* %r8 sme_active
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*/
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/* Save the CPU context, used for jumping back */
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pushq %rbx
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pushq %rbp
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pushq %r12
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pushq %r13
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pushq %r14
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pushq %r15
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pushf
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movq PTR(VA_CONTROL_PAGE)(%rsi), %r11
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movq %rsp, RSP(%r11)
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movq %cr0, %rax
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movq %rax, CR0(%r11)
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movq %cr3, %rax
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movq %rax, CR3(%r11)
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movq %cr4, %rax
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movq %rax, CR4(%r11)
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/* Save CR4. Required to enable the right paging mode later. */
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movq %rax, %r13
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/* zero out flags, and disable interrupts */
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pushq $0
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popfq
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/* Save SME active flag */
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movq %r8, %r12
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/*
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* get physical address of control page now
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* this is impossible after page table switch
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*/
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movq PTR(PA_CONTROL_PAGE)(%rsi), %r8
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/* get physical address of page table now too */
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movq PTR(PA_TABLE_PAGE)(%rsi), %r9
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/* get physical address of swap page now */
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movq PTR(PA_SWAP_PAGE)(%rsi), %r10
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/* save some information for jumping back */
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movq %r9, CP_PA_TABLE_PAGE(%r11)
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movq %r10, CP_PA_SWAP_PAGE(%r11)
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movq %rdi, CP_PA_BACKUP_PAGES_MAP(%r11)
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/* Switch to the identity mapped page tables */
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movq %r9, %cr3
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/* setup a new stack at the end of the physical control page */
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lea PAGE_SIZE(%r8), %rsp
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/* jump to identity mapped page */
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addq $(identity_mapped - relocate_kernel), %r8
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pushq %r8
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ANNOTATE_UNRET_SAFE
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ret
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int3
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SYM_CODE_END(relocate_kernel)
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SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
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UNWIND_HINT_EMPTY
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/* set return address to 0 if not preserving context */
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pushq $0
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/* store the start address on the stack */
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pushq %rdx
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/*
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* Set cr0 to a known state:
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* - Paging enabled
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* - Alignment check disabled
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* - Write protect disabled
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* - No task switch
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* - Don't do FP software emulation.
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* - Proctected mode enabled
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*/
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movq %cr0, %rax
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andq $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax
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orl $(X86_CR0_PG | X86_CR0_PE), %eax
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movq %rax, %cr0
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/*
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* Set cr4 to a known state:
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* - physical address extension enabled
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* - 5-level paging, if it was enabled before
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*/
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movl $X86_CR4_PAE, %eax
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testq $X86_CR4_LA57, %r13
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jz 1f
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orl $X86_CR4_LA57, %eax
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1:
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movq %rax, %cr4
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jmp 1f
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1:
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/* Flush the TLB (needed?) */
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movq %r9, %cr3
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/*
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* If SME is active, there could be old encrypted cache line
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* entries that will conflict with the now unencrypted memory
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* used by kexec. Flush the caches before copying the kernel.
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*/
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testq %r12, %r12
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jz 1f
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wbinvd
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1:
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movq %rcx, %r11
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call swap_pages
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/*
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* To be certain of avoiding problems with self-modifying code
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* I need to execute a serializing instruction here.
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* So I flush the TLB by reloading %cr3 here, it's handy,
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* and not processor dependent.
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*/
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movq %cr3, %rax
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movq %rax, %cr3
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/*
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* set all of the registers to known values
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* leave %rsp alone
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*/
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testq %r11, %r11
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jnz 1f
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xorl %eax, %eax
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xorl %ebx, %ebx
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xorl %ecx, %ecx
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xorl %edx, %edx
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xorl %esi, %esi
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xorl %edi, %edi
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xorl %ebp, %ebp
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xorl %r8d, %r8d
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xorl %r9d, %r9d
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xorl %r10d, %r10d
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xorl %r11d, %r11d
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xorl %r12d, %r12d
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xorl %r13d, %r13d
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xorl %r14d, %r14d
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xorl %r15d, %r15d
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ANNOTATE_UNRET_SAFE
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ret
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int3
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1:
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popq %rdx
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leaq PAGE_SIZE(%r10), %rsp
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ANNOTATE_RETPOLINE_SAFE
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call *%rdx
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/* get the re-entry point of the peer system */
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movq 0(%rsp), %rbp
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leaq relocate_kernel(%rip), %r8
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movq CP_PA_SWAP_PAGE(%r8), %r10
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movq CP_PA_BACKUP_PAGES_MAP(%r8), %rdi
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movq CP_PA_TABLE_PAGE(%r8), %rax
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movq %rax, %cr3
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lea PAGE_SIZE(%r8), %rsp
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call swap_pages
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movq $virtual_mapped, %rax
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pushq %rax
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ANNOTATE_UNRET_SAFE
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ret
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int3
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SYM_CODE_END(identity_mapped)
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SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
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UNWIND_HINT_EMPTY
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movq RSP(%r8), %rsp
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movq CR4(%r8), %rax
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movq %rax, %cr4
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movq CR3(%r8), %rax
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movq CR0(%r8), %r8
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movq %rax, %cr3
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movq %r8, %cr0
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movq %rbp, %rax
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popf
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popq %r15
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popq %r14
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popq %r13
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popq %r12
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popq %rbp
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popq %rbx
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ANNOTATE_UNRET_SAFE
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ret
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int3
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SYM_CODE_END(virtual_mapped)
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/* Do the copies */
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SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
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UNWIND_HINT_EMPTY
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movq %rdi, %rcx /* Put the page_list in %rcx */
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xorl %edi, %edi
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xorl %esi, %esi
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jmp 1f
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0: /* top, read another word for the indirection page */
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movq (%rbx), %rcx
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addq $8, %rbx
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1:
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testb $0x1, %cl /* is it a destination page? */
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jz 2f
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movq %rcx, %rdi
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andq $0xfffffffffffff000, %rdi
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jmp 0b
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2:
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testb $0x2, %cl /* is it an indirection page? */
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jz 2f
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movq %rcx, %rbx
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andq $0xfffffffffffff000, %rbx
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jmp 0b
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2:
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testb $0x4, %cl /* is it the done indicator? */
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jz 2f
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jmp 3f
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2:
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testb $0x8, %cl /* is it the source indicator? */
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jz 0b /* Ignore it otherwise */
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movq %rcx, %rsi /* For ever source page do a copy */
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andq $0xfffffffffffff000, %rsi
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movq %rdi, %rdx
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movq %rsi, %rax
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movq %r10, %rdi
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movl $512, %ecx
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rep ; movsq
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movq %rax, %rdi
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movq %rdx, %rsi
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movl $512, %ecx
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rep ; movsq
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movq %rdx, %rdi
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movq %r10, %rsi
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movl $512, %ecx
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rep ; movsq
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lea PAGE_SIZE(%rax), %rsi
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jmp 0b
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3:
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ANNOTATE_UNRET_SAFE
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ret
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int3
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SYM_CODE_END(swap_pages)
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.globl kexec_control_code_size
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.set kexec_control_code_size, . - relocate_kernel
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