421 строка
10 KiB
ArmAsm
421 строка
10 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/desc.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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#ifdef CONFIG_PARAVIRT
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#include <asm/asm-offsets.h>
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#include <asm/paravirt.h>
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#else
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#define GET_CR2_INTO_RCX movq %cr2, %rcx
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#endif
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/* we are not able to switch in one step to the final KERNEL ADRESS 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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.section .text.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 = 1,
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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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* %esi 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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/* 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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/* Is the address too large? */
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leaq _text(%rip), %rdx
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movq $PGDIR_SIZE, %rax
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cmpq %rax, %rdx
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jae bad_address
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/* Fixup the physical addresses in the page table
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*/
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addq %rbp, init_level4_pgt + 0(%rip)
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addq %rbp, init_level4_pgt + (L4_PAGE_OFFSET*8)(%rip)
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addq %rbp, init_level4_pgt + (L4_START_KERNEL*8)(%rip)
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addq %rbp, level3_ident_pgt + 0(%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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/* Add an Identity mapping if I am above 1G */
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leaq _text(%rip), %rdi
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andq $PMD_PAGE_MASK, %rdi
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movq %rdi, %rax
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shrq $PUD_SHIFT, %rax
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andq $(PTRS_PER_PUD - 1), %rax
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jz ident_complete
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leaq (level2_spare_pgt - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx
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leaq level3_ident_pgt(%rip), %rbx
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movq %rdx, 0(%rbx, %rax, 8)
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movq %rdi, %rax
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shrq $PMD_SHIFT, %rax
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andq $(PTRS_PER_PMD - 1), %rax
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leaq __PAGE_KERNEL_IDENT_LARGE_EXEC(%rdi), %rdx
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leaq level2_spare_pgt(%rip), %rbx
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movq %rdx, 0(%rbx, %rax, 8)
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ident_complete:
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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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#ifdef CONFIG_X86_TRAMPOLINE
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addq %rbp, trampoline_level4_pgt + 0(%rip)
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addq %rbp, trampoline_level4_pgt + (511*8)(%rip)
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#endif
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/* Due to ENTRY(), sometimes the empty space gets filled with
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* zeros. Better take a jmp than relying on empty space being
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* filled with 0x90 (nop)
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*/
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jmp secondary_startup_64
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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 = 1,
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* and someone has loaded a mapped page table.
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*
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* %esi 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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/* Enable PAE mode and PGE */
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movl $(X86_CR4_PAE | X86_CR4_PGE), %eax
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movq %rax, %cr4
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/* Setup early boot stage 4 level pagetables. */
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movq $(init_level4_pgt - __START_KERNEL_map), %rax
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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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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. actually 0 would do too */
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movl $__KERNEL_DS,%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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/*
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* Setup up a dummy PDA. this is just for some early bootup code
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* that does in_interrupt()
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*/
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movl $MSR_GS_BASE,%ecx
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movq $empty_zero_page,%rax
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movq %rax,%rdx
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shrq $32,%rdx
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wrmsr
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/* esi is pointer to real mode structure with interesting info.
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pass it to C */
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movl %esi, %edi
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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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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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/* SMP bootup changes these two */
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__REFDATA
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.align 8
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ENTRY(initial_code)
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.quad x86_64_start_kernel
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__FINITDATA
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ENTRY(stack_start)
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.quad init_thread_union+THREAD_SIZE-8
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.word 0
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bad_address:
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jmp bad_address
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.section ".init.text","ax"
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#ifdef CONFIG_EARLY_PRINTK
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.globl early_idt_handlers
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early_idt_handlers:
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i = 0
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.rept NUM_EXCEPTION_VECTORS
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movl $i, %esi
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jmp early_idt_handler
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i = i + 1
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.endr
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#endif
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ENTRY(early_idt_handler)
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#ifdef CONFIG_EARLY_PRINTK
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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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GET_CR2_INTO_RCX
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movq %rcx,%r9
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xorl %r8d,%r8d # zero for error code
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movl %esi,%ecx # get vector number
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# Test %ecx against mask of vectors that push error code.
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cmpl $31,%ecx
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ja 0f
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movl $1,%eax
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salq %cl,%rax
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testl $0x27d00,%eax
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je 0f
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popq %r8 # get error code
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0: movq 0(%rsp),%rcx # get ip
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movq 8(%rsp),%rdx # get cs
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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 8(%rsp),%rsi # get 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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#ifdef CONFIG_EARLY_PRINTK
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early_recursion_flag:
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.long 0
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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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.previous
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.balign PAGE_SIZE
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#define NEXT_PAGE(name) \
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.balign PAGE_SIZE; \
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ENTRY(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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/*
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* This default setting generates an ident mapping at address 0x100000
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* and a mapping for the kernel that precisely maps virtual address
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* 0xffffffff80000000 to physical address 0x000000. (always using
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* 2Mbyte large pages provided by PAE mode)
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*/
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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(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_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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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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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_spare_pgt)
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.fill 512, 8, 0
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#undef PMDS
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#undef NEXT_PAGE
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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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.quad per_cpu__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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.section .bss, "aw", @nobits
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.align L1_CACHE_BYTES
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ENTRY(idt_table)
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.skip 256 * 16
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.section .bss.page_aligned, "aw", @nobits
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.align PAGE_SIZE
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ENTRY(empty_zero_page)
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.skip PAGE_SIZE
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