Linux-2.6.33.2/arch/x86/kernel/head_32.S
/*
*
* 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>
/* 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
/* Enough space to fit pagetables for the low memory linear map */
MAPPING_BEYOND_END = \
PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT
/*
* Worst-case size of the kernel mapping we need to make:
* the worst-case size of the kernel itself, plus the extra we need
* to map for the linear map.
*/
KERNEL_PAGES = (KERNEL_IMAGE_SIZE + MAPPING_BEYOND_END)>>PAGE_SHIFT
INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE_asm
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)
/* 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
2:
/*
* 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 comand line
movl $pa(boot_command_line),%edi
movl $(COMMAND_LINE_SIZE/4),%ecx
rep
movsl
1:
#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
#endif /* CONFIG_PARAVIRT */
/*
* 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.
*
* Note that the stack is not yet set up!
*/
default_entry:
#ifdef CONFIG_X86_PAE
/*
* In PAE mode swapper_pg_dir 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(swapper_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(swapper_pg_fixmap)+PDE_IDENT_ATTR,%eax
movl %eax,pa(swapper_pg_pmd+0x1000*KPMDS-8)
#else /* Not PAE */
page_pde_offset = (__PAGE_OFFSET >> 20);
movl $pa(__brk_base), %edi
movl $pa(swapper_pg_dir), %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(swapper_pg_fixmap)+PDE_IDENT_ATTR,%eax
movl %eax,pa(swapper_pg_dir+0xffc)
#endif
jmp 3f
/*
* 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
#ifdef CONFIG_SMP
ENTRY(startup_32_smp)
cld
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
#endif /* CONFIG_SMP */
3:
/*
* 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
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(swapper_pg_dir),%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:
/* Set up the stack pointer */
lss stack_start,%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
#ifdef CONFIG_SMP
cmpb $0, ready
jz 1f /* Initial CPU cleans BSS */
jmp checkCPUtype
1:
#endif /* CONFIG_SMP */
/*
* start system 32-bit setup. We need to re-do some of the things done
* in 16-bit mode for the "real" operations.
*/
call setup_idt
checkCPUtype:
movl $-1,X86_CPUID # -1 for no CPUID initially
/* 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.
*/
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
#ifdef CONFIG_CC_STACKPROTECTOR
/*
* The linker can't handle this by relocation. Manually set
* base address in stack canary segment descriptor.
*/
cmpb $0,ready
jne 1f
movl $per_cpu__gdt_page,%eax
movl $per_cpu__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)
1:
#endif
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
#ifdef CONFIG_SMP
movb ready, %cl
movb $1, ready
cmpb $0,%cl # the first CPU calls start_kernel
je 1f
movl (stack_start), %esp
1:
#endif /* CONFIG_SMP */
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
/*
* setup_idt
*
* sets up a idt with 256 entries pointing to
* ignore_int, interrupt gates. It doesn't actually load
* idt - that can be done only after paging has been enabled
* and the kernel moved to PAGE_OFFSET. Interrupts
* are enabled elsewhere, when we can be relatively
* sure everything is ok.
*
* Warning: %esi is live across this function.
*/
setup_idt:
lea ignore_int,%edx
movl $(__KERNEL_CS << 16),%eax
movw %dx,%ax /* selector = 0x0010 = cs */
movw $0x8E00,%dx /* interrupt gate - dpl=0, present */
lea idt_table,%edi
mov $256,%ecx
rp_sidt:
movl %eax,(%edi)
movl %edx,4(%edi)
addl $8,%edi
dec %ecx
jne rp_sidt
.macro set_early_handler handler,trapno
lea \handler,%edx
movl $(__KERNEL_CS << 16),%eax
movw %dx,%ax
movw $0x8E00,%dx /* interrupt gate - dpl=0, present */
lea idt_table,%edi
movl %eax,8*\trapno(%edi)
movl %edx,8*\trapno+4(%edi)
.endm
set_early_handler handler=early_divide_err,trapno=0
set_early_handler handler=early_illegal_opcode,trapno=6
set_early_handler handler=early_protection_fault,trapno=13
set_early_handler handler=early_page_fault,trapno=14
ret
early_divide_err:
xor %edx,%edx
pushl $0 /* fake errcode */
jmp early_fault
early_illegal_opcode:
movl $6,%edx
pushl $0 /* fake errcode */
jmp early_fault
early_protection_fault:
movl $13,%edx
jmp early_fault
early_page_fault:
movl $14,%edx
jmp early_fault
early_fault:
cld
#ifdef CONFIG_PRINTK
pusha
movl $(__KERNEL_DS),%eax
movl %eax,%ds
movl %eax,%es
cmpl $2,early_recursion_flag
je hlt_loop
incl early_recursion_flag
movl %cr2,%eax
pushl %eax
pushl %edx /* trapno */
pushl $fault_msg
call printk
#endif
call dump_stack
hlt_loop:
hlt
jmp hlt_loop
/* 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
__REFDATA
.align 4
ENTRY(initial_code)
.long i386_start_kernel
/*
* BSS section
*/
__PAGE_ALIGNED_BSS
.align PAGE_SIZE_asm
#ifdef CONFIG_X86_PAE
swapper_pg_pmd:
.fill 1024*KPMDS,4,0
#else
ENTRY(swapper_pg_dir)
.fill 1024,4,0
#endif
swapper_pg_fixmap:
.fill 1024,4,0
ENTRY(empty_zero_page)
.fill 4096,1,0
/*
* This starts the data section.
*/
#ifdef CONFIG_X86_PAE
__PAGE_ALIGNED_DATA
/* Page-aligned for the benefit of paravirt? */
.align PAGE_SIZE_asm
ENTRY(swapper_pg_dir)
.long pa(swapper_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */
# if KPMDS == 3
.long pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
.long pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x1000),0
.long pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x2000),0
# elif KPMDS == 2
.long 0,0
.long pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
.long pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x1000),0
# elif KPMDS == 1
.long 0,0
.long 0,0
.long pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
# else
# error "Kernel PMDs should be 1, 2 or 3"
# endif
.align PAGE_SIZE_asm /* needs to be page-sized too */
#endif
.data
ENTRY(stack_start)
.long init_thread_union+THREAD_SIZE
.long __BOOT_DS
ready: .byte 0
early_recursion_flag:
.long 0
int_msg:
.asciz "Unknown interrupt or fault at: %p %p %p\n"
fault_msg:
/* fault info: */
.ascii "BUG: Int %d: CR2 %p\n"
/* pusha regs: */
.ascii " EDI %p ESI %p EBP %p ESP %p\n"
.ascii " EBX %p EDX %p ECX %p EAX %p\n"
/* fault frame: */
.ascii " 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:
*/
.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 per_cpu__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 */