kernel_optimize_test/arch/x86/kernel/head_32.S
Linus Torvalds 731a7378b8 Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 trampoline rework from H. Peter Anvin:
 "This code reworks all the "trampoline"/"realmode" code (various bits
  that need to live in the first megabyte of memory, most but not all of
  which runs in real mode at some point) in the kernel into a single
  object.  The main reason for doing this is that it eliminates the last
  place in the kernel where we needed pages to be mapped RWX.  This code
  separates all that code into proper R/RW/RX pages."

Fix up conflicts in arch/x86/kernel/Makefile (mca removed next to reboot
code), and arch/x86/kernel/reboot.c (reboot code moved around in one
branch, modified in this one), and arch/x86/tools/relocs.c (mostly same
code came in earlier due to working around the ld bugs just before the
3.4 release).

Also remove stale x86-relocs entry from scripts/.gitignore as per Peter
Anvin.

* commit '61f5446169046c217a5479517edac3a890c3bee7': (36 commits)
  x86, realmode: Move end signature into header.S
  x86, relocs: When printing an error, say relative or absolute
  x86, relocs: More relocations which may end up as absolute
  x86, relocs: Workaround for binutils 2.22.52.0.1 section bug
  xen-acpi-processor: Add missing #include <xen/xen.h>
  acpi, bgrd: Add missing <linux/io.h> to drivers/acpi/bgrt.c
  x86, realmode: Change EFER to a single u64 field
  x86, realmode: Move kernel/realmode.c to realmode/init.c
  x86, realmode: Move not-common bits out of trampoline_common.S
  x86, realmode: Mask out EFER.LMA when saving trampoline EFER
  x86, realmode: Fix no cache bits test in reboot_32.S
  x86, realmode: Make sure all generated files are listed in targets
  x86, realmode: build fix: remove duplicate build
  x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline
  x86, realmode: fixes compilation issue in tboot.c
  x86, realmode: move relocs from scripts/ to arch/x86/tools
  x86, realmode: header for trampoline code
  x86, realmode: flattened rm hierachy
  x86, realmode: don't copy real_mode_header
  x86, realmode: fix 64-bit wakeup sequence
  ...
2012-05-29 20:14:53 -07:00

764 lines
18 KiB
ArmAsm

/*
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Enhanced CPU detection and feature setting code by Mike Jagdis
* and Martin Mares, November 1997.
*/
.text
#include <linux/threads.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page_types.h>
#include <asm/pgtable_types.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm/setup.h>
#include <asm/processor-flags.h>
#include <asm/msr-index.h>
#include <asm/cpufeature.h>
#include <asm/percpu.h>
#include <asm/nops.h>
/* Physical address */
#define pa(X) ((X) - __PAGE_OFFSET)
/*
* References to members of the new_cpu_data structure.
*/
#define X86 new_cpu_data+CPUINFO_x86
#define X86_VENDOR new_cpu_data+CPUINFO_x86_vendor
#define X86_MODEL new_cpu_data+CPUINFO_x86_model
#define X86_MASK new_cpu_data+CPUINFO_x86_mask
#define X86_HARD_MATH new_cpu_data+CPUINFO_hard_math
#define X86_CPUID new_cpu_data+CPUINFO_cpuid_level
#define X86_CAPABILITY new_cpu_data+CPUINFO_x86_capability
#define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id
/*
* This is how much memory in addition to the memory covered up to
* and including _end we need mapped initially.
* We need:
* (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
* (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
*
* Modulo rounding, each megabyte assigned here requires a kilobyte of
* memory, which is currently unreclaimed.
*
* This should be a multiple of a page.
*
* KERNEL_IMAGE_SIZE should be greater than pa(_end)
* and small than max_low_pfn, otherwise will waste some page table entries
*/
#if PTRS_PER_PMD > 1
#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
#else
#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
#endif
/* Number of possible pages in the lowmem region */
LOWMEM_PAGES = (((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT)
/* Enough space to fit pagetables for the low memory linear map */
MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
/*
* Worst-case size of the kernel mapping we need to make:
* a relocatable kernel can live anywhere in lowmem, so we need to be able
* to map all of lowmem.
*/
KERNEL_PAGES = LOWMEM_PAGES
INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
RESERVE_BRK(pagetables, INIT_MAP_SIZE)
/*
* 32-bit kernel entrypoint; only used by the boot CPU. On entry,
* %esi points to the real-mode code as a 32-bit pointer.
* CS and DS must be 4 GB flat segments, but we don't depend on
* any particular GDT layout, because we load our own as soon as we
* can.
*/
__HEAD
ENTRY(startup_32)
movl pa(stack_start),%ecx
/* test KEEP_SEGMENTS flag to see if the bootloader is asking
us to not reload segments */
testb $(1<<6), BP_loadflags(%esi)
jnz 2f
/*
* Set segments to known values.
*/
lgdt pa(boot_gdt_descr)
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
movl %eax,%ss
2:
leal -__PAGE_OFFSET(%ecx),%esp
/*
* Clear BSS first so that there are no surprises...
*/
cld
xorl %eax,%eax
movl $pa(__bss_start),%edi
movl $pa(__bss_stop),%ecx
subl %edi,%ecx
shrl $2,%ecx
rep ; stosl
/*
* Copy bootup parameters out of the way.
* Note: %esi still has the pointer to the real-mode data.
* With the kexec as boot loader, parameter segment might be loaded beyond
* kernel image and might not even be addressable by early boot page tables.
* (kexec on panic case). Hence copy out the parameters before initializing
* page tables.
*/
movl $pa(boot_params),%edi
movl $(PARAM_SIZE/4),%ecx
cld
rep
movsl
movl pa(boot_params) + NEW_CL_POINTER,%esi
andl %esi,%esi
jz 1f # No command line
movl $pa(boot_command_line),%edi
movl $(COMMAND_LINE_SIZE/4),%ecx
rep
movsl
1:
#ifdef CONFIG_OLPC
/* save OFW's pgdir table for later use when calling into OFW */
movl %cr3, %eax
movl %eax, pa(olpc_ofw_pgd)
#endif
/*
* Initialize page tables. This creates a PDE and a set of page
* tables, which are located immediately beyond __brk_base. The variable
* _brk_end is set up to point to the first "safe" location.
* Mappings are created both at virtual address 0 (identity mapping)
* and PAGE_OFFSET for up to _end.
*/
#ifdef CONFIG_X86_PAE
/*
* In PAE mode initial_page_table is statically defined to contain
* enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
* entries). The identity mapping is handled by pointing two PGD entries
* to the first kernel PMD.
*
* Note the upper half of each PMD or PTE are always zero at this stage.
*/
#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
xorl %ebx,%ebx /* %ebx is kept at zero */
movl $pa(__brk_base), %edi
movl $pa(initial_pg_pmd), %edx
movl $PTE_IDENT_ATTR, %eax
10:
leal PDE_IDENT_ATTR(%edi),%ecx /* Create PMD entry */
movl %ecx,(%edx) /* Store PMD entry */
/* Upper half already zero */
addl $8,%edx
movl $512,%ecx
11:
stosl
xchgl %eax,%ebx
stosl
xchgl %eax,%ebx
addl $0x1000,%eax
loop 11b
/*
* End condition: we must map up to the end + MAPPING_BEYOND_END.
*/
movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
cmpl %ebp,%eax
jb 10b
1:
addl $__PAGE_OFFSET, %edi
movl %edi, pa(_brk_end)
shrl $12, %eax
movl %eax, pa(max_pfn_mapped)
/* Do early initialization of the fixmap area */
movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
#else /* Not PAE */
page_pde_offset = (__PAGE_OFFSET >> 20);
movl $pa(__brk_base), %edi
movl $pa(initial_page_table), %edx
movl $PTE_IDENT_ATTR, %eax
10:
leal PDE_IDENT_ATTR(%edi),%ecx /* Create PDE entry */
movl %ecx,(%edx) /* Store identity PDE entry */
movl %ecx,page_pde_offset(%edx) /* Store kernel PDE entry */
addl $4,%edx
movl $1024, %ecx
11:
stosl
addl $0x1000,%eax
loop 11b
/*
* End condition: we must map up to the end + MAPPING_BEYOND_END.
*/
movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
cmpl %ebp,%eax
jb 10b
addl $__PAGE_OFFSET, %edi
movl %edi, pa(_brk_end)
shrl $12, %eax
movl %eax, pa(max_pfn_mapped)
/* Do early initialization of the fixmap area */
movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
movl %eax,pa(initial_page_table+0xffc)
#endif
#ifdef CONFIG_PARAVIRT
/* This is can only trip for a broken bootloader... */
cmpw $0x207, pa(boot_params + BP_version)
jb default_entry
/* Paravirt-compatible boot parameters. Look to see what architecture
we're booting under. */
movl pa(boot_params + BP_hardware_subarch), %eax
cmpl $num_subarch_entries, %eax
jae bad_subarch
movl pa(subarch_entries)(,%eax,4), %eax
subl $__PAGE_OFFSET, %eax
jmp *%eax
bad_subarch:
WEAK(lguest_entry)
WEAK(xen_entry)
/* Unknown implementation; there's really
nothing we can do at this point. */
ud2a
__INITDATA
subarch_entries:
.long default_entry /* normal x86/PC */
.long lguest_entry /* lguest hypervisor */
.long xen_entry /* Xen hypervisor */
.long default_entry /* Moorestown MID */
num_subarch_entries = (. - subarch_entries) / 4
.previous
#else
jmp default_entry
#endif /* CONFIG_PARAVIRT */
/*
* Non-boot CPU entry point; entered from trampoline.S
* We can't lgdt here, because lgdt itself uses a data segment, but
* we know the trampoline has already loaded the boot_gdt for us.
*
* If cpu hotplug is not supported then this code can go in init section
* which will be freed later
*/
__CPUINIT
ENTRY(startup_32_smp)
cld
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
movl pa(stack_start),%ecx
movl %eax,%ss
leal -__PAGE_OFFSET(%ecx),%esp
default_entry:
/*
* New page tables may be in 4Mbyte page mode and may
* be using the global pages.
*
* NOTE! If we are on a 486 we may have no cr4 at all!
* So we do not try to touch it unless we really have
* some bits in it to set. This won't work if the BSP
* implements cr4 but this AP does not -- very unlikely
* but be warned! The same applies to the pse feature
* if not equally supported. --macro
*
* NOTE! We have to correct for the fact that we're
* not yet offset PAGE_OFFSET..
*/
#define cr4_bits pa(mmu_cr4_features)
movl cr4_bits,%edx
andl %edx,%edx
jz 6f
movl %cr4,%eax # Turn on paging options (PSE,PAE,..)
orl %edx,%eax
movl %eax,%cr4
testb $X86_CR4_PAE, %al # check if PAE is enabled
jz 6f
/* Check if extended functions are implemented */
movl $0x80000000, %eax
cpuid
/* Value must be in the range 0x80000001 to 0x8000ffff */
subl $0x80000001, %eax
cmpl $(0x8000ffff-0x80000001), %eax
ja 6f
/* Clear bogus XD_DISABLE bits */
call verify_cpu
mov $0x80000001, %eax
cpuid
/* Execute Disable bit supported? */
btl $(X86_FEATURE_NX & 31), %edx
jnc 6f
/* Setup EFER (Extended Feature Enable Register) */
movl $MSR_EFER, %ecx
rdmsr
btsl $_EFER_NX, %eax
/* Make changes effective */
wrmsr
6:
/*
* Enable paging
*/
movl $pa(initial_page_table), %eax
movl %eax,%cr3 /* set the page table pointer.. */
movl %cr0,%eax
orl $X86_CR0_PG,%eax
movl %eax,%cr0 /* ..and set paging (PG) bit */
ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */
1:
/* Shift the stack pointer to a virtual address */
addl $__PAGE_OFFSET, %esp
/*
* Initialize eflags. Some BIOS's leave bits like NT set. This would
* confuse the debugger if this code is traced.
* XXX - best to initialize before switching to protected mode.
*/
pushl $0
popfl
/*
* start system 32-bit setup. We need to re-do some of the things done
* in 16-bit mode for the "real" operations.
*/
movl setup_once_ref,%eax
andl %eax,%eax
jz 1f # Did we do this already?
call *%eax
1:
/* check if it is 486 or 386. */
/*
* XXX - this does a lot of unnecessary setup. Alignment checks don't
* apply at our cpl of 0 and the stack ought to be aligned already, and
* we don't need to preserve eflags.
*/
movl $-1,X86_CPUID # -1 for no CPUID initially
movb $3,X86 # at least 386
pushfl # push EFLAGS
popl %eax # get EFLAGS
movl %eax,%ecx # save original EFLAGS
xorl $0x240000,%eax # flip AC and ID bits in EFLAGS
pushl %eax # copy to EFLAGS
popfl # set EFLAGS
pushfl # get new EFLAGS
popl %eax # put it in eax
xorl %ecx,%eax # change in flags
pushl %ecx # restore original EFLAGS
popfl
testl $0x40000,%eax # check if AC bit changed
je is386
movb $4,X86 # at least 486
testl $0x200000,%eax # check if ID bit changed
je is486
/* get vendor info */
xorl %eax,%eax # call CPUID with 0 -> return vendor ID
cpuid
movl %eax,X86_CPUID # save CPUID level
movl %ebx,X86_VENDOR_ID # lo 4 chars
movl %edx,X86_VENDOR_ID+4 # next 4 chars
movl %ecx,X86_VENDOR_ID+8 # last 4 chars
orl %eax,%eax # do we have processor info as well?
je is486
movl $1,%eax # Use the CPUID instruction to get CPU type
cpuid
movb %al,%cl # save reg for future use
andb $0x0f,%ah # mask processor family
movb %ah,X86
andb $0xf0,%al # mask model
shrb $4,%al
movb %al,X86_MODEL
andb $0x0f,%cl # mask mask revision
movb %cl,X86_MASK
movl %edx,X86_CAPABILITY
is486: movl $0x50022,%ecx # set AM, WP, NE and MP
jmp 2f
is386: movl $2,%ecx # set MP
2: movl %cr0,%eax
andl $0x80000011,%eax # Save PG,PE,ET
orl %ecx,%eax
movl %eax,%cr0
call check_x87
lgdt early_gdt_descr
lidt idt_descr
ljmp $(__KERNEL_CS),$1f
1: movl $(__KERNEL_DS),%eax # reload all the segment registers
movl %eax,%ss # after changing gdt.
movl $(__USER_DS),%eax # DS/ES contains default USER segment
movl %eax,%ds
movl %eax,%es
movl $(__KERNEL_PERCPU), %eax
movl %eax,%fs # set this cpu's percpu
movl $(__KERNEL_STACK_CANARY),%eax
movl %eax,%gs
xorl %eax,%eax # Clear LDT
lldt %ax
cld # gcc2 wants the direction flag cleared at all times
pushl $0 # fake return address for unwinder
jmp *(initial_code)
/*
* We depend on ET to be correct. This checks for 287/387.
*/
check_x87:
movb $0,X86_HARD_MATH
clts
fninit
fstsw %ax
cmpb $0,%al
je 1f
movl %cr0,%eax /* no coprocessor: have to set bits */
xorl $4,%eax /* set EM */
movl %eax,%cr0
ret
ALIGN
1: movb $1,X86_HARD_MATH
.byte 0xDB,0xE4 /* fsetpm for 287, ignored by 387 */
ret
#include "verify_cpu.S"
/*
* setup_once
*
* The setup work we only want to run on the BSP.
*
* Warning: %esi is live across this function.
*/
__INIT
setup_once:
/*
* Set up a idt with 256 entries pointing to ignore_int,
* interrupt gates. It doesn't actually load idt - that needs
* to be done on each CPU. Interrupts are enabled elsewhere,
* when we can be relatively sure everything is ok.
*/
movl $idt_table,%edi
movl $early_idt_handlers,%eax
movl $NUM_EXCEPTION_VECTORS,%ecx
1:
movl %eax,(%edi)
movl %eax,4(%edi)
/* interrupt gate, dpl=0, present */
movl $(0x8E000000 + __KERNEL_CS),2(%edi)
addl $9,%eax
addl $8,%edi
loop 1b
movl $256 - NUM_EXCEPTION_VECTORS,%ecx
movl $ignore_int,%edx
movl $(__KERNEL_CS << 16),%eax
movw %dx,%ax /* selector = 0x0010 = cs */
movw $0x8E00,%dx /* interrupt gate - dpl=0, present */
2:
movl %eax,(%edi)
movl %edx,4(%edi)
addl $8,%edi
loop 2b
#ifdef CONFIG_CC_STACKPROTECTOR
/*
* Configure the stack canary. The linker can't handle this by
* relocation. Manually set base address in stack canary
* segment descriptor.
*/
movl $gdt_page,%eax
movl $stack_canary,%ecx
movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
shrl $16, %ecx
movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
#endif
andl $0,setup_once_ref /* Once is enough, thanks */
ret
ENTRY(early_idt_handlers)
# 36(%esp) %eflags
# 32(%esp) %cs
# 28(%esp) %eip
# 24(%rsp) error code
i = 0
.rept NUM_EXCEPTION_VECTORS
.if (EXCEPTION_ERRCODE_MASK >> i) & 1
ASM_NOP2
.else
pushl $0 # Dummy error code, to make stack frame uniform
.endif
pushl $i # 20(%esp) Vector number
jmp early_idt_handler
i = i + 1
.endr
ENDPROC(early_idt_handlers)
/* This is global to keep gas from relaxing the jumps */
ENTRY(early_idt_handler)
cld
cmpl $2,%ss:early_recursion_flag
je hlt_loop
incl %ss:early_recursion_flag
push %eax # 16(%esp)
push %ecx # 12(%esp)
push %edx # 8(%esp)
push %ds # 4(%esp)
push %es # 0(%esp)
movl $(__KERNEL_DS),%eax
movl %eax,%ds
movl %eax,%es
cmpl $(__KERNEL_CS),32(%esp)
jne 10f
leal 28(%esp),%eax # Pointer to %eip
call early_fixup_exception
andl %eax,%eax
jnz ex_entry /* found an exception entry */
10:
#ifdef CONFIG_PRINTK
xorl %eax,%eax
movw %ax,2(%esp) /* clean up the segment values on some cpus */
movw %ax,6(%esp)
movw %ax,34(%esp)
leal 40(%esp),%eax
pushl %eax /* %esp before the exception */
pushl %ebx
pushl %ebp
pushl %esi
pushl %edi
movl %cr2,%eax
pushl %eax
pushl (20+6*4)(%esp) /* trapno */
pushl $fault_msg
call printk
#endif
call dump_stack
hlt_loop:
hlt
jmp hlt_loop
ex_entry:
pop %es
pop %ds
pop %edx
pop %ecx
pop %eax
addl $8,%esp /* drop vector number and error code */
decl %ss:early_recursion_flag
iret
ENDPROC(early_idt_handler)
/* This is the default interrupt "handler" :-) */
ALIGN
ignore_int:
cld
#ifdef CONFIG_PRINTK
pushl %eax
pushl %ecx
pushl %edx
pushl %es
pushl %ds
movl $(__KERNEL_DS),%eax
movl %eax,%ds
movl %eax,%es
cmpl $2,early_recursion_flag
je hlt_loop
incl early_recursion_flag
pushl 16(%esp)
pushl 24(%esp)
pushl 32(%esp)
pushl 40(%esp)
pushl $int_msg
call printk
call dump_stack
addl $(5*4),%esp
popl %ds
popl %es
popl %edx
popl %ecx
popl %eax
#endif
iret
ENDPROC(ignore_int)
__INITDATA
.align 4
early_recursion_flag:
.long 0
__REFDATA
.align 4
ENTRY(initial_code)
.long i386_start_kernel
ENTRY(setup_once_ref)
.long setup_once
/*
* BSS section
*/
__PAGE_ALIGNED_BSS
.align PAGE_SIZE
#ifdef CONFIG_X86_PAE
initial_pg_pmd:
.fill 1024*KPMDS,4,0
#else
ENTRY(initial_page_table)
.fill 1024,4,0
#endif
initial_pg_fixmap:
.fill 1024,4,0
ENTRY(empty_zero_page)
.fill 4096,1,0
ENTRY(swapper_pg_dir)
.fill 1024,4,0
/*
* This starts the data section.
*/
#ifdef CONFIG_X86_PAE
__PAGE_ALIGNED_DATA
/* Page-aligned for the benefit of paravirt? */
.align PAGE_SIZE
ENTRY(initial_page_table)
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */
# if KPMDS == 3
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
# elif KPMDS == 2
.long 0,0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
# elif KPMDS == 1
.long 0,0
.long 0,0
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
# else
# error "Kernel PMDs should be 1, 2 or 3"
# endif
.align PAGE_SIZE /* needs to be page-sized too */
#endif
.data
.balign 4
ENTRY(stack_start)
.long init_thread_union+THREAD_SIZE
__INITRODATA
int_msg:
.asciz "Unknown interrupt or fault at: %p %p %p\n"
fault_msg:
/* fault info: */
.ascii "BUG: Int %d: CR2 %p\n"
/* regs pushed in early_idt_handler: */
.ascii " EDI %p ESI %p EBP %p EBX %p\n"
.ascii " ESP %p ES %p DS %p\n"
.ascii " EDX %p ECX %p EAX %p\n"
/* fault frame: */
.ascii " vec %p err %p EIP %p CS %p flg %p\n"
.ascii "Stack: %p %p %p %p %p %p %p %p\n"
.ascii " %p %p %p %p %p %p %p %p\n"
.asciz " %p %p %p %p %p %p %p %p\n"
#include "../../x86/xen/xen-head.S"
/*
* The IDT and GDT 'descriptors' are a strange 48-bit object
* only used by the lidt and lgdt instructions. They are not
* like usual segment descriptors - they consist of a 16-bit
* segment size, and 32-bit linear address value:
*/
.data
.globl boot_gdt_descr
.globl idt_descr
ALIGN
# early boot GDT descriptor (must use 1:1 address mapping)
.word 0 # 32 bit align gdt_desc.address
boot_gdt_descr:
.word __BOOT_DS+7
.long boot_gdt - __PAGE_OFFSET
.word 0 # 32-bit align idt_desc.address
idt_descr:
.word IDT_ENTRIES*8-1 # idt contains 256 entries
.long idt_table
# boot GDT descriptor (later on used by CPU#0):
.word 0 # 32 bit align gdt_desc.address
ENTRY(early_gdt_descr)
.word GDT_ENTRIES*8-1
.long gdt_page /* Overwritten for secondary CPUs */
/*
* The boot_gdt must mirror the equivalent in setup.S and is
* used only for booting.
*/
.align L1_CACHE_BYTES
ENTRY(boot_gdt)
.fill GDT_ENTRY_BOOT_CS,8,0
.quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
.quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */