/* 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) 2002-2004 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/nospec-branch.h>
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#include <asm/processor-flags.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 << 2)
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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 ESP DATA(0x0)
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#define CR0 DATA(0x4)
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#define CR3 DATA(0x8)
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#define CR4 DATA(0xc)
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/* other data */
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#define CP_VA_CONTROL_PAGE DATA(0x10)
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#define CP_PA_PGD DATA(0x14)
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#define CP_PA_SWAP_PAGE DATA(0x18)
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#define CP_PA_BACKUP_PAGES_MAP DATA(0x1c)
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.text
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SYM_CODE_START_NOALIGN(relocate_kernel)
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/* Save the CPU context, used for jumping back */
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pushl %ebx
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pushl %esi
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pushl %edi
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pushl %ebp
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pushf
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movl 20+8(%esp), %ebp /* list of pages */
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movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
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movl %esp, ESP(%edi)
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movl %cr0, %eax
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movl %eax, CR0(%edi)
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movl %cr3, %eax
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movl %eax, CR3(%edi)
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movl %cr4, %eax
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movl %eax, CR4(%edi)
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/* read the arguments and say goodbye to the stack */
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movl 20+4(%esp), %ebx /* page_list */
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movl 20+8(%esp), %ebp /* list of pages */
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movl 20+12(%esp), %edx /* start address */
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movl 20+16(%esp), %ecx /* cpu_has_pae */
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movl 20+20(%esp), %esi /* preserve_context */
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/* zero out flags, and disable interrupts */
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pushl $0
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popfl
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/* save some information for jumping back */
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movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
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movl %edi, CP_VA_CONTROL_PAGE(%edi)
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movl PTR(PA_PGD)(%ebp), %eax
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movl %eax, CP_PA_PGD(%edi)
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movl PTR(PA_SWAP_PAGE)(%ebp), %eax
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movl %eax, CP_PA_SWAP_PAGE(%edi)
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movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
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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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movl PTR(PA_CONTROL_PAGE)(%ebp), %edi
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/* switch to new set of page tables */
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movl PTR(PA_PGD)(%ebp), %eax
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movl %eax, %cr3
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/* setup a new stack at the end of the physical control page */
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lea PAGE_SIZE(%edi), %esp
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/* jump to identity mapped page */
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movl %edi, %eax
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addl $(identity_mapped - relocate_kernel), %eax
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pushl %eax
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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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/* set return address to 0 if not preserving context */
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pushl $0
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/* store the start address on the stack */
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pushl %edx
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/*
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* Set cr0 to a known state:
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* - Paging disabled
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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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movl %cr0, %eax
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andl $~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax
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orl $(X86_CR0_PE), %eax
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movl %eax, %cr0
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/* clear cr4 if applicable */
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testl %ecx, %ecx
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jz 1f
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/*
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* Set cr4 to a known state:
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* Setting everything to zero seems safe.
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*/
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xorl %eax, %eax
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movl %eax, %cr4
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jmp 1f
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1:
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/* Flush the TLB (needed?) */
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xorl %eax, %eax
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movl %eax, %cr3
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movl CP_PA_SWAP_PAGE(%edi), %eax
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pushl %eax
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pushl %ebx
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call swap_pages
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addl $8, %esp
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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, it's handy, and not processor dependent.
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*/
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xorl %eax, %eax
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movl %eax, %cr3
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/*
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* set all of the registers to known values
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* leave %esp alone
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*/
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testl %esi, %esi
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jnz 1f
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xorl %edi, %edi
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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 %ebp, %ebp
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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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popl %edx
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movl CP_PA_SWAP_PAGE(%edi), %esp
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addl $PAGE_SIZE, %esp
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2:
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ANNOTATE_RETPOLINE_SAFE
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call *%edx
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/* get the re-entry point of the peer system */
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movl 0(%esp), %ebp
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call 1f
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1:
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popl %ebx
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subl $(1b - relocate_kernel), %ebx
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movl CP_VA_CONTROL_PAGE(%ebx), %edi
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lea PAGE_SIZE(%ebx), %esp
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movl CP_PA_SWAP_PAGE(%ebx), %eax
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movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
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pushl %eax
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pushl %edx
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call swap_pages
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addl $8, %esp
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movl CP_PA_PGD(%ebx), %eax
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movl %eax, %cr3
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movl %cr0, %eax
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orl $X86_CR0_PG, %eax
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movl %eax, %cr0
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lea PAGE_SIZE(%edi), %esp
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movl %edi, %eax
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addl $(virtual_mapped - relocate_kernel), %eax
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pushl %eax
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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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movl CR4(%edi), %eax
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movl %eax, %cr4
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movl CR3(%edi), %eax
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movl %eax, %cr3
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movl CR0(%edi), %eax
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movl %eax, %cr0
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movl ESP(%edi), %esp
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movl %ebp, %eax
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popf
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popl %ebp
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popl %edi
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popl %esi
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popl %ebx
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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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movl 8(%esp), %edx
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movl 4(%esp), %ecx
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pushl %ebp
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pushl %ebx
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pushl %edi
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pushl %esi
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movl %ecx, %ebx
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jmp 1f
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0: /* top, read another word from the indirection page */
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movl (%ebx), %ecx
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addl $4, %ebx
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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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movl %ecx, %edi
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andl $0xfffff000, %edi
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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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movl %ecx, %ebx
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andl $0xfffff000, %ebx
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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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movl %ecx, %esi /* For every source page do a copy */
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andl $0xfffff000, %esi
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movl %edi, %eax
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movl %esi, %ebp
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movl %edx, %edi
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movl $1024, %ecx
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rep ; movsl
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movl %ebp, %edi
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movl %eax, %esi
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movl $1024, %ecx
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rep ; movsl
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movl %eax, %edi
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movl %edx, %esi
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movl $1024, %ecx
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rep ; movsl
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lea PAGE_SIZE(%ebp), %esi
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jmp 0b
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3:
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popl %esi
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popl %edi
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popl %ebx
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popl %ebp
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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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