3566561bfa
kexec: Avoid overwriting the current pgd (V4, i386) This patch upgrades the i386-specific kexec code to avoid overwriting the current pgd. Overwriting the current pgd is bad when CONFIG_CRASH_DUMP is used to start a secondary kernel that dumps the memory of the previous kernel. The code introduces a new set of page tables. These tables are used to provide an executable identity mapping without overwriting the current pgd. Signed-off-by: Magnus Damm <magnus@valinux.co.jp> Signed-off-by: Andi Kleen <ak@suse.de>
253 lines
5.4 KiB
ArmAsm
253 lines
5.4 KiB
ArmAsm
/*
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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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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/linkage.h>
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#include <asm/page.h>
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#include <asm/kexec.h>
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/*
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* Must be relocatable PIC code callable as a C function
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*/
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#define PTR(x) (x << 2)
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#define PAGE_ALIGNED (1 << PAGE_SHIFT)
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#define PAGE_ATTR 0x63 /* _PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY */
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#define PAE_PGD_ATTR 0x01 /* _PAGE_PRESENT */
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.text
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.align PAGE_ALIGNED
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.globl relocate_kernel
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relocate_kernel:
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movl 8(%esp), %ebp /* list of pages */
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#ifdef CONFIG_X86_PAE
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/* map the control page at its virtual address */
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movl PTR(VA_PGD)(%ebp), %edi
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movl PTR(VA_CONTROL_PAGE)(%ebp), %eax
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andl $0xc0000000, %eax
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shrl $27, %eax
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addl %edi, %eax
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movl PTR(PA_PMD_0)(%ebp), %edx
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orl $PAE_PGD_ATTR, %edx
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movl %edx, (%eax)
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movl PTR(VA_PMD_0)(%ebp), %edi
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movl PTR(VA_CONTROL_PAGE)(%ebp), %eax
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andl $0x3fe00000, %eax
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shrl $18, %eax
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addl %edi, %eax
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movl PTR(PA_PTE_0)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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movl PTR(VA_PTE_0)(%ebp), %edi
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movl PTR(VA_CONTROL_PAGE)(%ebp), %eax
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andl $0x001ff000, %eax
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shrl $9, %eax
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addl %edi, %eax
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movl PTR(PA_CONTROL_PAGE)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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/* identity map the control page at its physical address */
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movl PTR(VA_PGD)(%ebp), %edi
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movl PTR(PA_CONTROL_PAGE)(%ebp), %eax
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andl $0xc0000000, %eax
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shrl $27, %eax
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addl %edi, %eax
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movl PTR(PA_PMD_1)(%ebp), %edx
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orl $PAE_PGD_ATTR, %edx
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movl %edx, (%eax)
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movl PTR(VA_PMD_1)(%ebp), %edi
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movl PTR(PA_CONTROL_PAGE)(%ebp), %eax
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andl $0x3fe00000, %eax
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shrl $18, %eax
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addl %edi, %eax
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movl PTR(PA_PTE_1)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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movl PTR(VA_PTE_1)(%ebp), %edi
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movl PTR(PA_CONTROL_PAGE)(%ebp), %eax
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andl $0x001ff000, %eax
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shrl $9, %eax
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addl %edi, %eax
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movl PTR(PA_CONTROL_PAGE)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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#else
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/* map the control page at its virtual address */
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movl PTR(VA_PGD)(%ebp), %edi
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movl PTR(VA_CONTROL_PAGE)(%ebp), %eax
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andl $0xffc00000, %eax
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shrl $20, %eax
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addl %edi, %eax
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movl PTR(PA_PTE_0)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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movl PTR(VA_PTE_0)(%ebp), %edi
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movl PTR(VA_CONTROL_PAGE)(%ebp), %eax
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andl $0x003ff000, %eax
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shrl $10, %eax
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addl %edi, %eax
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movl PTR(PA_CONTROL_PAGE)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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/* identity map the control page at its physical address */
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movl PTR(VA_PGD)(%ebp), %edi
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movl PTR(PA_CONTROL_PAGE)(%ebp), %eax
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andl $0xffc00000, %eax
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shrl $20, %eax
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addl %edi, %eax
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movl PTR(PA_PTE_1)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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movl PTR(VA_PTE_1)(%ebp), %edi
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movl PTR(PA_CONTROL_PAGE)(%ebp), %eax
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andl $0x003ff000, %eax
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shrl $10, %eax
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addl %edi, %eax
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movl PTR(PA_CONTROL_PAGE)(%ebp), %edx
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orl $PAGE_ATTR, %edx
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movl %edx, (%eax)
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#endif
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relocate_new_kernel:
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/* read the arguments and say goodbye to the stack */
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movl 4(%esp), %ebx /* page_list */
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movl 8(%esp), %ebp /* list of pages */
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movl 12(%esp), %edx /* start address */
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movl 16(%esp), %ecx /* cpu_has_pae */
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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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/* get physical address of control page now */
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/* this is impossible after page table switch */
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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 4096(%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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ret
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identity_mapped:
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/* store the start address on the stack */
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pushl %edx
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/* Set cr0 to a known state:
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* 31 0 == Paging disabled
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* 18 0 == Alignment check disabled
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* 16 0 == Write protect disabled
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* 3 0 == No task switch
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* 2 0 == Don't do FP software emulation.
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* 0 1 == Proctected mode enabled
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*/
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movl %cr0, %eax
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andl $~((1<<31)|(1<<18)|(1<<16)|(1<<3)|(1<<2)), %eax
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orl $(1<<0), %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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/* Set cr4 to a known state:
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* Setting everything to zero seems safe.
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*/
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movl %cr4, %eax
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andl $0, %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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/* Do the copies */
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movl %ebx, %ecx
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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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testl $0x1, %ecx /* 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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testl $0x2, %ecx /* 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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testl $0x4, %ecx /* 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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testl $0x8, %ecx /* 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 $1024, %ecx
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rep ; movsl
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jmp 0b
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3:
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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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/* set all of the registers to known values */
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/* leave %esp alone */
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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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ret
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