/*
 *
 *  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.h>
#include <asm/pgtable.h>
#include <asm/desc.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm/setup.h>
#include <asm/processor-flags.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:
 *  - one bit for each possible page, but only in low memory, which means
 *     2^32/4096/8 = 128K worst case (4G/4G split.)
 *  - enough space to map all low memory, which means
 *     (2^32/4096) / 1024 pages (worst case, non PAE)
 *     (2^32/4096) / 512 + 4 pages (worst case for PAE)
 *  - a few pages for allocator use before the kernel pagetable has
 *     been set up
 *
 * Modulo rounding, each megabyte assigned here requires a kilobyte of
 * memory, which is currently unreclaimed.
 *
 * This should be a multiple of a page.
 */
LOW_PAGES = 1<<(32-PAGE_SHIFT_asm)

/*
 * To preserve the DMA pool in PAGEALLOC kernels, we'll allocate
 * pagetables from above the 16MB DMA limit, so we'll have to set
 * up pagetables 16MB more (worst-case):
 */
#ifdef CONFIG_DEBUG_PAGEALLOC
LOW_PAGES = LOW_PAGES + 0x1000000
#endif

#if PTRS_PER_PMD > 1
PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PMD) + PTRS_PER_PGD
#else
PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PGD)
#endif
BOOTBITMAP_SIZE = LOW_PAGES / 8
ALLOCATOR_SLOP = 4

INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_SIZE_asm

/*
 * 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.
 */
.section .text.head,"ax",@progbits
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 */
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 _end.  The variable
 * init_pg_tables_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+sizeof(page tables)+INIT_MAP_BEYOND_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(pg0), %edi
        movl %edi, pa(init_pg_tables_start)
        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 and including INIT_MAP_BEYOND_END
         * bytes beyond the end of our own page tables.
         */
        leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp
        cmpl %ebp,%eax
        jb 10b
1:
        movl %edi,pa(init_pg_tables_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(pg0), %edi
        movl %edi, pa(init_pg_tables_start)
        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 and including INIT_MAP_BEYOND_END
         * bytes beyond the end of our own page tables; the +0x007 is
         * the attribute bits
         */
        leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp
        cmpl %ebp,%eax
        jb 10b
        movl %edi,pa(init_pg_tables_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
 */

#ifndef CONFIG_HOTPLUG_CPU
.section .init.text,"ax",@progbits
#endif

#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

        btl $5, %eax            # check if PAE is enabled
        jnc 6f

        /* Check if extended functions are implemented */
        movl $0x80000000, %eax
        cpuid
        cmpl $0x80000000, %eax
        jbe 6f
        mov $0x80000001, %eax
        cpuid
        /* Execute Disable bit supported? */
        btl $20, %edx
        jnc 6f

        /* Setup EFER (Extended Feature Enable Register) */
        movl $0xc0000080, %ecx
        rdmsr

        btsl $11, %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 %eax,%fs                   # gets reset once there's real percpu

        movl $(__USER_DS),%eax          # DS/ES contains default USER segment
        movl %eax,%ds
        movl %eax,%es

        xorl %eax,%eax                  # Clear GS and LDT
        movl %eax,%gs
        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 $(__KERNEL_PERCPU), %eax
        movl %eax,%fs           # set this cpu's percpu
        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
#ifdef CONFIG_EARLY_PRINTK
        call early_printk
#else
        call printk
#endif
#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
#ifdef CONFIG_EARLY_PRINTK
        call early_printk
#else
        call printk
#endif
        addl $(5*4),%esp
        popl %ds
        popl %es
        popl %edx
        popl %ecx
        popl %eax
#endif
        iret

.section .cpuinit.data,"wa"
.align 4
ENTRY(initial_code)
        .long i386_start_kernel

.section .text
/*
 * Real beginning of normal "text" segment
 */
ENTRY(stext)
ENTRY(_stext)

/*
 * BSS section
 */
.section ".bss.page_aligned","wa"
        .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
.section ".data.page_aligned","wa"
        /* 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 EIP %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 */