mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2025-08-18 10:04:15 +00:00
42c782fae3
Minimum version of binutils required to compile the kernel is 2.25. This version correctly handles the "rep" prefixes, so it is possible to remove the semicolon, which was used to support ancient versions of GNU as. Due to the semicolon, the compiler considers "rep; insn" (or its alternate "rep\n\tinsn" form) as two separate instructions. Removing the semicolon makes asm length calculations more accurate, consequently making scheduling and inlining decisions of the compiler more accurate. Removing the semicolon also enables assembler checks involving "rep" prefixes. Trying to assemble e.g. "rep addl %eax, %ebx" results in: Error: invalid instruction `add' after `rep' Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pavel Machek <pavel@kernel.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Link: https://lore.kernel.org/r/20250418071437.4144391-2-ubizjak@gmail.com
292 lines
5.9 KiB
ArmAsm
292 lines
5.9 KiB
ArmAsm
/* 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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* - Protected 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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