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linux-sg2042/arch/x86_64/kernel/head.S

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/*
* linux/arch/x86_64/kernel/head.S -- start in 32bit and switch to 64bit
*
* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
* Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
* Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
* Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
* Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
*/
#include <linux/linkage.h>
#include <linux/threads.h>
#include <linux/init.h>
#include <asm/desc.h>
#include <asm/segment.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/msr.h>
#include <asm/cache.h>
/* we are not able to switch in one step to the final KERNEL ADRESS SPACE
* because we need identity-mapped pages.
*
*/
.text
.section .bootstrap.text
.code64
.globl startup_64
startup_64:
/*
* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1,
* and someone has loaded an identity mapped page table
* for us. These identity mapped page tables map all of the
* kernel pages and possibly all of memory.
*
* %esi holds a physical pointer to real_mode_data.
*
* We come here either directly from a 64bit bootloader, or from
* arch/x86_64/boot/compressed/head.S.
*
* We only come here initially at boot nothing else comes here.
*
* Since we may be loaded at an address different from what we were
* compiled to run at we first fixup the physical addresses in our page
* tables and then reload them.
*/
/* Compute the delta between the address I am compiled to run at and the
* address I am actually running at.
*/
leaq _text(%rip), %rbp
subq $_text - __START_KERNEL_map, %rbp
/* Is the address not 2M aligned? */
movq %rbp, %rax
andl $~LARGE_PAGE_MASK, %eax
testl %eax, %eax
jnz bad_address
/* Is the address too large? */
leaq _text(%rip), %rdx
movq $PGDIR_SIZE, %rax
cmpq %rax, %rdx
jae bad_address
/* Fixup the physical addresses in the page table
*/
addq %rbp, init_level4_pgt + 0(%rip)
addq %rbp, init_level4_pgt + (258*8)(%rip)
addq %rbp, init_level4_pgt + (511*8)(%rip)
addq %rbp, level3_ident_pgt + 0(%rip)
addq %rbp, level3_kernel_pgt + (510*8)(%rip)
/* Add an Identity mapping if I am above 1G */
leaq _text(%rip), %rdi
andq $LARGE_PAGE_MASK, %rdi
movq %rdi, %rax
shrq $PUD_SHIFT, %rax
andq $(PTRS_PER_PUD - 1), %rax
jz ident_complete
leaq (level2_spare_pgt - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx
leaq level3_ident_pgt(%rip), %rbx
movq %rdx, 0(%rbx, %rax, 8)
movq %rdi, %rax
shrq $PMD_SHIFT, %rax
andq $(PTRS_PER_PMD - 1), %rax
leaq __PAGE_KERNEL_LARGE_EXEC(%rdi), %rdx
leaq level2_spare_pgt(%rip), %rbx
movq %rdx, 0(%rbx, %rax, 8)
ident_complete:
/* Fixup the kernel text+data virtual addresses
*/
leaq level2_kernel_pgt(%rip), %rdi
leaq 4096(%rdi), %r8
/* See if it is a valid page table entry */
1: testq $1, 0(%rdi)
jz 2f
addq %rbp, 0(%rdi)
/* Go to the next page */
2: addq $8, %rdi
cmp %r8, %rdi
jne 1b
/* Fixup phys_base */
addq %rbp, phys_base(%rip)
#ifdef CONFIG_SMP
addq %rbp, trampoline_level4_pgt + 0(%rip)
addq %rbp, trampoline_level4_pgt + (511*8)(%rip)
#endif
#ifdef CONFIG_ACPI_SLEEP
addq %rbp, wakeup_level4_pgt + 0(%rip)
addq %rbp, wakeup_level4_pgt + (511*8)(%rip)
#endif
/* Due to ENTRY(), sometimes the empty space gets filled with
* zeros. Better take a jmp than relying on empty space being
* filled with 0x90 (nop)
*/
jmp secondary_startup_64
ENTRY(secondary_startup_64)
/*
* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1,
* and someone has loaded a mapped page table.
*
* %esi holds a physical pointer to real_mode_data.
*
* We come here either from startup_64 (using physical addresses)
* or from trampoline.S (using virtual addresses).
*
* Using virtual addresses from trampoline.S removes the need
* to have any identity mapped pages in the kernel page table
* after the boot processor executes this code.
*/
/* Enable PAE mode and PGE */
xorq %rax, %rax
btsq $5, %rax
btsq $7, %rax
movq %rax, %cr4
/* Setup early boot stage 4 level pagetables. */
movq $(init_level4_pgt - __START_KERNEL_map), %rax
addq phys_base(%rip), %rax
movq %rax, %cr3
/* Ensure I am executing from virtual addresses */
movq $1f, %rax
jmp *%rax
1:
/* Check if nx is implemented */
movl $0x80000001, %eax
cpuid
movl %edx,%edi
/* Setup EFER (Extended Feature Enable Register) */
movl $MSR_EFER, %ecx
rdmsr
btsl $_EFER_SCE, %eax /* Enable System Call */
btl $20,%edi /* No Execute supported? */
jnc 1f
btsl $_EFER_NX, %eax
1: wrmsr /* Make changes effective */
/* Setup cr0 */
#define CR0_PM 1 /* protected mode */
#define CR0_MP (1<<1)
#define CR0_ET (1<<4)
#define CR0_NE (1<<5)
#define CR0_WP (1<<16)
#define CR0_AM (1<<18)
#define CR0_PAGING (1<<31)
movl $CR0_PM|CR0_MP|CR0_ET|CR0_NE|CR0_WP|CR0_AM|CR0_PAGING,%eax
/* Make changes effective */
movq %rax, %cr0
/* Setup a boot time stack */
movq init_rsp(%rip),%rsp
/* zero EFLAGS after setting rsp */
pushq $0
popfq
/*
* We must switch to a new descriptor in kernel space for the GDT
* because soon the kernel won't have access anymore to the userspace
* addresses where we're currently running on. We have to do that here
* because in 32bit we couldn't load a 64bit linear address.
*/
lgdt cpu_gdt_descr(%rip)
/* set up data segments. actually 0 would do too */
movl $__KERNEL_DS,%eax
movl %eax,%ds
movl %eax,%ss
movl %eax,%es
/*
* We don't really need to load %fs or %gs, but load them anyway
* to kill any stale realmode selectors. This allows execution
* under VT hardware.
*/
movl %eax,%fs
movl %eax,%gs
/*
* Setup up a dummy PDA. this is just for some early bootup code
* that does in_interrupt()
*/
movl $MSR_GS_BASE,%ecx
movq $empty_zero_page,%rax
movq %rax,%rdx
shrq $32,%rdx
wrmsr
/* esi is pointer to real mode structure with interesting info.
pass it to C */
movl %esi, %edi
/* Finally jump to run C code and to be on real kernel address
* Since we are running on identity-mapped space we have to jump
* to the full 64bit address, this is only possible as indirect
* jump. In addition we need to ensure %cs is set so we make this
* a far return.
*/
movq initial_code(%rip),%rax
pushq $0 # fake return address to stop unwinder
pushq $__KERNEL_CS # set correct cs
pushq %rax # target address in negative space
lretq
/* SMP bootup changes these two */
.align 8
.globl initial_code
initial_code:
.quad x86_64_start_kernel
.globl init_rsp
init_rsp:
.quad init_thread_union+THREAD_SIZE-8
bad_address:
jmp bad_address
ENTRY(early_idt_handler)
cmpl $2,early_recursion_flag(%rip)
jz 1f
incl early_recursion_flag(%rip)
xorl %eax,%eax
movq 8(%rsp),%rsi # get rip
movq (%rsp),%rdx
movq %cr2,%rcx
leaq early_idt_msg(%rip),%rdi
call early_printk
cmpl $2,early_recursion_flag(%rip)
jz 1f
call dump_stack
#ifdef CONFIG_KALLSYMS
leaq early_idt_ripmsg(%rip),%rdi
movq 8(%rsp),%rsi # get rip again
call __print_symbol
#endif
1: hlt
jmp 1b
early_recursion_flag:
.long 0
early_idt_msg:
.asciz "PANIC: early exception rip %lx error %lx cr2 %lx\n"
early_idt_ripmsg:
.asciz "RIP %s\n"
.balign PAGE_SIZE
ENTRY(stext)
ENTRY(_stext)
#define NEXT_PAGE(name) \
.balign PAGE_SIZE; \
ENTRY(name)
/* Automate the creation of 1 to 1 mapping pmd entries */
#define PMDS(START, PERM, COUNT) \
i = 0 ; \
.rept (COUNT) ; \
.quad (START) + (i << 21) + (PERM) ; \
i = i + 1 ; \
.endr
/*
* This default setting generates an ident mapping at address 0x100000
* and a mapping for the kernel that precisely maps virtual address
* 0xffffffff80000000 to physical address 0x000000. (always using
* 2Mbyte large pages provided by PAE mode)
*/
NEXT_PAGE(init_level4_pgt)
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 257,8,0
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 252,8,0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
NEXT_PAGE(level3_ident_pgt)
.quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 511,8,0
NEXT_PAGE(level3_kernel_pgt)
.fill 510,8,0
/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
.quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 1,8,0
NEXT_PAGE(level2_ident_pgt)
/* Since I easily can, map the first 1G.
* Don't set NX because code runs from these pages.
*/
PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD)
NEXT_PAGE(level2_kernel_pgt)
/* 40MB kernel mapping. The kernel code cannot be bigger than that.
When you change this change KERNEL_TEXT_SIZE in page.h too. */
/* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */
PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL,
KERNEL_TEXT_SIZE/PMD_SIZE)
/* Module mapping starts here */
.fill (PTRS_PER_PMD - (KERNEL_TEXT_SIZE/PMD_SIZE)),8,0
NEXT_PAGE(level2_spare_pgt)
.fill 512,8,0
#undef PMDS
#undef NEXT_PAGE
.data
.align 16
.globl cpu_gdt_descr
cpu_gdt_descr:
.word gdt_end-cpu_gdt_table-1
gdt:
.quad cpu_gdt_table
#ifdef CONFIG_SMP
.rept NR_CPUS-1
.word 0
.quad 0
.endr
#endif
ENTRY(phys_base)
/* This must match the first entry in level2_kernel_pgt */
.quad 0x0000000000000000
/* We need valid kernel segments for data and code in long mode too
* IRET will check the segment types kkeil 2000/10/28
* Also sysret mandates a special GDT layout
*/
.section .data.page_aligned, "aw"
.align PAGE_SIZE
/* The TLS descriptors are currently at a different place compared to i386.
Hopefully nobody expects them at a fixed place (Wine?) */
ENTRY(cpu_gdt_table)
.quad 0x0000000000000000 /* NULL descriptor */
.quad 0x00cf9b000000ffff /* __KERNEL32_CS */
.quad 0x00af9b000000ffff /* __KERNEL_CS */
.quad 0x00cf93000000ffff /* __KERNEL_DS */
.quad 0x00cffb000000ffff /* __USER32_CS */
.quad 0x00cff3000000ffff /* __USER_DS, __USER32_DS */
.quad 0x00affb000000ffff /* __USER_CS */
.quad 0x0 /* unused */
.quad 0,0 /* TSS */
.quad 0,0 /* LDT */
.quad 0,0,0 /* three TLS descriptors */
.quad 0x0000f40000000000 /* node/CPU stored in limit */
gdt_end:
/* asm/segment.h:GDT_ENTRIES must match this */
/* This should be a multiple of the cache line size */
/* GDTs of other CPUs are now dynamically allocated */
/* zero the remaining page */
.fill PAGE_SIZE / 8 - GDT_ENTRIES,8,0
.section .bss, "aw", @nobits
.align L1_CACHE_BYTES
ENTRY(idt_table)
.skip 256 * 16
.section .bss.page_aligned, "aw", @nobits
.align PAGE_SIZE
ENTRY(empty_zero_page)
.skip PAGE_SIZE
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