518 lines
13 KiB
ArmAsm
518 lines
13 KiB
ArmAsm
/*
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* linux/arch/x86_64/kernel/head.S -- start in 32bit and switch to 64bit
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*
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* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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* Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
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* Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
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* Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
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* Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
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*/
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#include <linux/linkage.h>
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#include <linux/threads.h>
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#include <linux/init.h>
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#include <asm/segment.h>
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#include <asm/pgtable.h>
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#include <asm/page.h>
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#include <asm/msr.h>
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#include <asm/cache.h>
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#include <asm/processor-flags.h>
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#include <asm/percpu.h>
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#include <asm/nops.h>
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#ifdef CONFIG_PARAVIRT
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#include <asm/asm-offsets.h>
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#include <asm/paravirt.h>
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#define GET_CR2_INTO(reg) GET_CR2_INTO_RAX ; movq %rax, reg
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#else
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#define GET_CR2_INTO(reg) movq %cr2, reg
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#define INTERRUPT_RETURN iretq
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#endif
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/* we are not able to switch in one step to the final KERNEL ADDRESS SPACE
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* because we need identity-mapped pages.
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*
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*/
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#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
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L4_PAGE_OFFSET = pgd_index(__PAGE_OFFSET)
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L3_PAGE_OFFSET = pud_index(__PAGE_OFFSET)
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L4_START_KERNEL = pgd_index(__START_KERNEL_map)
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L3_START_KERNEL = pud_index(__START_KERNEL_map)
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.text
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__HEAD
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.code64
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.globl startup_64
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startup_64:
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/*
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* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
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* and someone has loaded an identity mapped page table
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* for us. These identity mapped page tables map all of the
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* kernel pages and possibly all of memory.
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*
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* %rsi holds a physical pointer to real_mode_data.
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*
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* We come here either directly from a 64bit bootloader, or from
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* arch/x86_64/boot/compressed/head.S.
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*
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* We only come here initially at boot nothing else comes here.
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*
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* Since we may be loaded at an address different from what we were
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* compiled to run at we first fixup the physical addresses in our page
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* tables and then reload them.
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*/
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/*
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* Compute the delta between the address I am compiled to run at and the
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* address I am actually running at.
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*/
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leaq _text(%rip), %rbp
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subq $_text - __START_KERNEL_map, %rbp
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/* Is the address not 2M aligned? */
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movq %rbp, %rax
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andl $~PMD_PAGE_MASK, %eax
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testl %eax, %eax
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jnz bad_address
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/*
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* Is the address too large?
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*/
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leaq _text(%rip), %rax
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shrq $MAX_PHYSMEM_BITS, %rax
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jnz bad_address
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/*
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* Fixup the physical addresses in the page table
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*/
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addq %rbp, early_level4_pgt + (L4_START_KERNEL*8)(%rip)
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addq %rbp, level3_kernel_pgt + (510*8)(%rip)
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addq %rbp, level3_kernel_pgt + (511*8)(%rip)
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addq %rbp, level2_fixmap_pgt + (506*8)(%rip)
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/*
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* Set up the identity mapping for the switchover. These
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* entries should *NOT* have the global bit set! This also
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* creates a bunch of nonsense entries but that is fine --
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* it avoids problems around wraparound.
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*/
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leaq _text(%rip), %rdi
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leaq early_level4_pgt(%rip), %rbx
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movq %rdi, %rax
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shrq $PGDIR_SHIFT, %rax
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leaq (4096 + _KERNPG_TABLE)(%rbx), %rdx
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movq %rdx, 0(%rbx,%rax,8)
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movq %rdx, 8(%rbx,%rax,8)
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addq $4096, %rdx
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movq %rdi, %rax
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shrq $PUD_SHIFT, %rax
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andl $(PTRS_PER_PUD-1), %eax
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movq %rdx, 4096(%rbx,%rax,8)
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incl %eax
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andl $(PTRS_PER_PUD-1), %eax
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movq %rdx, 4096(%rbx,%rax,8)
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addq $8192, %rbx
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movq %rdi, %rax
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shrq $PMD_SHIFT, %rdi
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addq $(__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL), %rax
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leaq (_end - 1)(%rip), %rcx
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shrq $PMD_SHIFT, %rcx
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subq %rdi, %rcx
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incl %ecx
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1:
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andq $(PTRS_PER_PMD - 1), %rdi
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movq %rax, (%rbx,%rdi,8)
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incq %rdi
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addq $PMD_SIZE, %rax
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decl %ecx
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jnz 1b
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/*
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* Fixup the kernel text+data virtual addresses. Note that
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* we might write invalid pmds, when the kernel is relocated
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* cleanup_highmap() fixes this up along with the mappings
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* beyond _end.
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*/
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leaq level2_kernel_pgt(%rip), %rdi
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leaq 4096(%rdi), %r8
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/* See if it is a valid page table entry */
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1: testq $1, 0(%rdi)
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jz 2f
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addq %rbp, 0(%rdi)
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/* Go to the next page */
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2: addq $8, %rdi
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cmp %r8, %rdi
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jne 1b
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/* Fixup phys_base */
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addq %rbp, phys_base(%rip)
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movq $(early_level4_pgt - __START_KERNEL_map), %rax
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jmp 1f
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ENTRY(secondary_startup_64)
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/*
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* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
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* and someone has loaded a mapped page table.
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*
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* %rsi holds a physical pointer to real_mode_data.
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*
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* We come here either from startup_64 (using physical addresses)
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* or from trampoline.S (using virtual addresses).
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*
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* Using virtual addresses from trampoline.S removes the need
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* to have any identity mapped pages in the kernel page table
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* after the boot processor executes this code.
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*/
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movq $(init_level4_pgt - __START_KERNEL_map), %rax
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1:
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/* Enable PAE mode and PGE */
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movl $(X86_CR4_PAE | X86_CR4_PGE), %ecx
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movq %rcx, %cr4
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/* Setup early boot stage 4 level pagetables. */
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addq phys_base(%rip), %rax
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movq %rax, %cr3
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/* Ensure I am executing from virtual addresses */
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movq $1f, %rax
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jmp *%rax
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1:
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/* Check if nx is implemented */
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movl $0x80000001, %eax
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cpuid
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movl %edx,%edi
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/* Setup EFER (Extended Feature Enable Register) */
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movl $MSR_EFER, %ecx
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rdmsr
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btsl $_EFER_SCE, %eax /* Enable System Call */
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btl $20,%edi /* No Execute supported? */
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jnc 1f
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btsl $_EFER_NX, %eax
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btsq $_PAGE_BIT_NX,early_pmd_flags(%rip)
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1: wrmsr /* Make changes effective */
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/* Setup cr0 */
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#define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
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X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
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X86_CR0_PG)
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movl $CR0_STATE, %eax
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/* Make changes effective */
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movq %rax, %cr0
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/* Setup a boot time stack */
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movq stack_start(%rip), %rsp
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/* zero EFLAGS after setting rsp */
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pushq $0
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popfq
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/*
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* We must switch to a new descriptor in kernel space for the GDT
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* because soon the kernel won't have access anymore to the userspace
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* addresses where we're currently running on. We have to do that here
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* because in 32bit we couldn't load a 64bit linear address.
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*/
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lgdt early_gdt_descr(%rip)
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/* set up data segments */
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xorl %eax,%eax
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movl %eax,%ds
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movl %eax,%ss
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movl %eax,%es
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/*
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* We don't really need to load %fs or %gs, but load them anyway
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* to kill any stale realmode selectors. This allows execution
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* under VT hardware.
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*/
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movl %eax,%fs
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movl %eax,%gs
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/* Set up %gs.
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*
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* The base of %gs always points to the bottom of the irqstack
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* union. If the stack protector canary is enabled, it is
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* located at %gs:40. Note that, on SMP, the boot cpu uses
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* init data section till per cpu areas are set up.
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*/
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movl $MSR_GS_BASE,%ecx
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movl initial_gs(%rip),%eax
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movl initial_gs+4(%rip),%edx
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wrmsr
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/* rsi is pointer to real mode structure with interesting info.
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pass it to C */
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movq %rsi, %rdi
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/* Finally jump to run C code and to be on real kernel address
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* Since we are running on identity-mapped space we have to jump
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* to the full 64bit address, this is only possible as indirect
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* jump. In addition we need to ensure %cs is set so we make this
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* a far return.
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*
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* Note: do not change to far jump indirect with 64bit offset.
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*
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* AMD does not support far jump indirect with 64bit offset.
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* AMD64 Architecture Programmer's Manual, Volume 3: states only
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* JMP FAR mem16:16 FF /5 Far jump indirect,
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* with the target specified by a far pointer in memory.
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* JMP FAR mem16:32 FF /5 Far jump indirect,
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* with the target specified by a far pointer in memory.
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*
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* Intel64 does support 64bit offset.
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* Software Developer Manual Vol 2: states:
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* FF /5 JMP m16:16 Jump far, absolute indirect,
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* address given in m16:16
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* FF /5 JMP m16:32 Jump far, absolute indirect,
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* address given in m16:32.
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* REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
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* address given in m16:64.
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*/
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movq initial_code(%rip),%rax
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pushq $0 # fake return address to stop unwinder
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pushq $__KERNEL_CS # set correct cs
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pushq %rax # target address in negative space
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lretq
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#ifdef CONFIG_HOTPLUG_CPU
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/*
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* Boot CPU0 entry point. It's called from play_dead(). Everything has been set
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* up already except stack. We just set up stack here. Then call
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* start_secondary().
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*/
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ENTRY(start_cpu0)
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movq stack_start(%rip),%rsp
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movq initial_code(%rip),%rax
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pushq $0 # fake return address to stop unwinder
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pushq $__KERNEL_CS # set correct cs
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pushq %rax # target address in negative space
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lretq
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ENDPROC(start_cpu0)
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#endif
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/* SMP bootup changes these two */
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__REFDATA
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.balign 8
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GLOBAL(initial_code)
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.quad x86_64_start_kernel
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GLOBAL(initial_gs)
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.quad INIT_PER_CPU_VAR(irq_stack_union)
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GLOBAL(stack_start)
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.quad init_thread_union+THREAD_SIZE-8
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.word 0
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__FINITDATA
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bad_address:
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jmp bad_address
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__INIT
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.globl early_idt_handlers
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early_idt_handlers:
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# 104(%rsp) %rflags
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# 96(%rsp) %cs
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# 88(%rsp) %rip
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# 80(%rsp) error code
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i = 0
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.rept NUM_EXCEPTION_VECTORS
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.if (EXCEPTION_ERRCODE_MASK >> i) & 1
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ASM_NOP2
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.else
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pushq $0 # Dummy error code, to make stack frame uniform
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.endif
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pushq $i # 72(%rsp) Vector number
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jmp early_idt_handler
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i = i + 1
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.endr
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/* This is global to keep gas from relaxing the jumps */
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ENTRY(early_idt_handler)
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cld
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cmpl $2,early_recursion_flag(%rip)
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jz 1f
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incl early_recursion_flag(%rip)
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pushq %rax # 64(%rsp)
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pushq %rcx # 56(%rsp)
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pushq %rdx # 48(%rsp)
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pushq %rsi # 40(%rsp)
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pushq %rdi # 32(%rsp)
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pushq %r8 # 24(%rsp)
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pushq %r9 # 16(%rsp)
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pushq %r10 # 8(%rsp)
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pushq %r11 # 0(%rsp)
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cmpl $__KERNEL_CS,96(%rsp)
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jne 11f
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cmpl $14,72(%rsp) # Page fault?
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jnz 10f
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GET_CR2_INTO(%rdi) # can clobber any volatile register if pv
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call early_make_pgtable
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andl %eax,%eax
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jz 20f # All good
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10:
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leaq 88(%rsp),%rdi # Pointer to %rip
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call early_fixup_exception
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andl %eax,%eax
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jnz 20f # Found an exception entry
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11:
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#ifdef CONFIG_EARLY_PRINTK
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GET_CR2_INTO(%r9) # can clobber any volatile register if pv
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movl 80(%rsp),%r8d # error code
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movl 72(%rsp),%esi # vector number
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movl 96(%rsp),%edx # %cs
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movq 88(%rsp),%rcx # %rip
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xorl %eax,%eax
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leaq early_idt_msg(%rip),%rdi
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call early_printk
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cmpl $2,early_recursion_flag(%rip)
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jz 1f
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call dump_stack
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#ifdef CONFIG_KALLSYMS
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leaq early_idt_ripmsg(%rip),%rdi
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movq 40(%rsp),%rsi # %rip again
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call __print_symbol
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#endif
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#endif /* EARLY_PRINTK */
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1: hlt
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jmp 1b
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20: # Exception table entry found or page table generated
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popq %r11
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popq %r10
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popq %r9
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popq %r8
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popq %rdi
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popq %rsi
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popq %rdx
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popq %rcx
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popq %rax
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addq $16,%rsp # drop vector number and error code
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decl early_recursion_flag(%rip)
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INTERRUPT_RETURN
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ENDPROC(early_idt_handler)
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__INITDATA
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.balign 4
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early_recursion_flag:
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.long 0
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#ifdef CONFIG_EARLY_PRINTK
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early_idt_msg:
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.asciz "PANIC: early exception %02lx rip %lx:%lx error %lx cr2 %lx\n"
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early_idt_ripmsg:
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.asciz "RIP %s\n"
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#endif /* CONFIG_EARLY_PRINTK */
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#define NEXT_PAGE(name) \
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.balign PAGE_SIZE; \
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GLOBAL(name)
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/* Automate the creation of 1 to 1 mapping pmd entries */
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#define PMDS(START, PERM, COUNT) \
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i = 0 ; \
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.rept (COUNT) ; \
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.quad (START) + (i << PMD_SHIFT) + (PERM) ; \
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i = i + 1 ; \
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.endr
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__INITDATA
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NEXT_PAGE(early_level4_pgt)
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.fill 511,8,0
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.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
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NEXT_PAGE(early_dynamic_pgts)
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.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
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.data
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#ifndef CONFIG_XEN
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NEXT_PAGE(init_level4_pgt)
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.fill 512,8,0
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#else
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NEXT_PAGE(init_level4_pgt)
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.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
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.org init_level4_pgt + L4_PAGE_OFFSET*8, 0
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.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
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.org init_level4_pgt + L4_START_KERNEL*8, 0
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/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
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.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
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NEXT_PAGE(level3_ident_pgt)
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.quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
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.fill 511, 8, 0
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NEXT_PAGE(level2_ident_pgt)
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/* Since I easily can, map the first 1G.
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* Don't set NX because code runs from these pages.
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*/
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PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
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#endif
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NEXT_PAGE(level3_kernel_pgt)
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.fill L3_START_KERNEL,8,0
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/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
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.quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
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.quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
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NEXT_PAGE(level2_kernel_pgt)
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/*
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* 512 MB kernel mapping. We spend a full page on this pagetable
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* anyway.
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*
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* The kernel code+data+bss must not be bigger than that.
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*
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* (NOTE: at +512MB starts the module area, see MODULES_VADDR.
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* If you want to increase this then increase MODULES_VADDR
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* too.)
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*/
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PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
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KERNEL_IMAGE_SIZE/PMD_SIZE)
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NEXT_PAGE(level2_fixmap_pgt)
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.fill 506,8,0
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.quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
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/* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
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.fill 5,8,0
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NEXT_PAGE(level1_fixmap_pgt)
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.fill 512,8,0
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#undef PMDS
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.data
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.align 16
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.globl early_gdt_descr
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early_gdt_descr:
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.word GDT_ENTRIES*8-1
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early_gdt_descr_base:
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.quad INIT_PER_CPU_VAR(gdt_page)
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ENTRY(phys_base)
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/* This must match the first entry in level2_kernel_pgt */
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.quad 0x0000000000000000
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#include "../../x86/xen/xen-head.S"
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__PAGE_ALIGNED_BSS
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NEXT_PAGE(empty_zero_page)
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.skip PAGE_SIZE
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