arch/x86/kernel/head_32.S

   1 /*
   2  *
   3  *  Copyright (C) 1991, 1992  Linus Torvalds
   4  *
   5  *  Enhanced CPU detection and feature setting code by Mike Jagdis
   6  *  and Martin Mares, November 1997.
   7  */
   8
   9 .text
  10 #include <linux/threads.h>
  11 #include <linux/init.h>
  12 #include <linux/linkage.h>
  13 #include <asm/segment.h>
  14 #include <asm/page_types.h>
  15 #include <asm/pgtable_types.h>
  16 #include <asm/cache.h>
  17 #include <asm/thread_info.h>
  18 #include <asm/asm-offsets.h>
  19 #include <asm/setup.h>
  20 #include <asm/processor-flags.h>
  21 #include <asm/percpu.h>
  22
  23 /* Physical address */
  24 #define pa(X) ((X) - __PAGE_OFFSET)
  25
  26 /*
  27  * References to members of the new_cpu_data structure.
  28  */
  29
  30 #define X86             new_cpu_data+CPUINFO_x86
  31 #define X86_VENDOR      new_cpu_data+CPUINFO_x86_vendor
  32 #define X86_MODEL       new_cpu_data+CPUINFO_x86_model
  33 #define X86_MASK        new_cpu_data+CPUINFO_x86_mask
  34 #define X86_HARD_MATH   new_cpu_data+CPUINFO_hard_math
  35 #define X86_CPUID       new_cpu_data+CPUINFO_cpuid_level
  36 #define X86_CAPABILITY  new_cpu_data+CPUINFO_x86_capability
  37 #define X86_VENDOR_ID   new_cpu_data+CPUINFO_x86_vendor_id
  38
  39 /*
  40  * This is how much memory in addition to the memory covered up to
  41  * and including _end we need mapped initially.
  42  * We need:
  43  *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
  44  *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
  45  *
  46  * Modulo rounding, each megabyte assigned here requires a kilobyte of
  47  * memory, which is currently unreclaimed.
  48  *
  49  * This should be a multiple of a page.
  50  *
  51  * KERNEL_IMAGE_SIZE should be greater than pa(_end)
  52  * and small than max_low_pfn, otherwise will waste some page table entries
  53  */
  54
  55 #if PTRS_PER_PMD > 1
  56 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
  57 #else
  58 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
  59 #endif
  60
  61 /* Enough space to fit pagetables for the low memory linear map */
  62 MAPPING_BEYOND_END = \
  63         PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT
  64
  65 /*
  66  * Worst-case size of the kernel mapping we need to make:
  67  * the worst-case size of the kernel itself, plus the extra we need
  68  * to map for the linear map.
  69  */
  70 KERNEL_PAGES = (KERNEL_IMAGE_SIZE + MAPPING_BEYOND_END)>>PAGE_SHIFT
  71
  72 INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE_asm
  73 RESERVE_BRK(pagetables, INIT_MAP_SIZE)
  74
  75 /*
  76  * 32-bit kernel entrypoint; only used by the boot CPU.  On entry,
  77  * %esi points to the real-mode code as a 32-bit pointer.
  78  * CS and DS must be 4 GB flat segments, but we don't depend on
  79  * any particular GDT layout, because we load our own as soon as we
  80  * can.
  81  */
  82 .section .text.head,"ax",@progbits
  83 ENTRY(startup_32)
  84         /* test KEEP_SEGMENTS flag to see if the bootloader is asking
  85                 us to not reload segments */
  86         testb $(1<<6), BP_loadflags(%esi)
  87         jnz 2f
  88
  89 /*
  90  * Set segments to known values.
  91  */
  92         lgdt pa(boot_gdt_descr)
  93         movl $(__BOOT_DS),%eax
  94         movl %eax,%ds
  95         movl %eax,%es
  96         movl %eax,%fs
  97         movl %eax,%gs
  98 2:
  99
 100 /*
 101  * Clear BSS first so that there are no surprises...
 102  */
 103         cld
 104         xorl %eax,%eax
 105         movl $pa(__bss_start),%edi
 106         movl $pa(__bss_stop),%ecx
 107         subl %edi,%ecx
 108         shrl $2,%ecx
 109         rep ; stosl
 110 /*
 111  * Copy bootup parameters out of the way.
 112  * Note: %esi still has the pointer to the real-mode data.
 113  * With the kexec as boot loader, parameter segment might be loaded beyond
 114  * kernel image and might not even be addressable by early boot page tables.
 115  * (kexec on panic case). Hence copy out the parameters before initializing
 116  * page tables.
 117  */
 118         movl $pa(boot_params),%edi
 119         movl $(PARAM_SIZE/4),%ecx
 120         cld
 121         rep
 122         movsl
 123         movl pa(boot_params) + NEW_CL_POINTER,%esi
 124         andl %esi,%esi
 125         jz 1f                   # No comand line
 126         movl $pa(boot_command_line),%edi
 127         movl $(COMMAND_LINE_SIZE/4),%ecx
 128         rep
 129         movsl
 130 1:
 131
 132 #ifdef CONFIG_PARAVIRT
 133         /* This is can only trip for a broken bootloader... */
 134         cmpw $0x207, pa(boot_params + BP_version)
 135         jb default_entry
 136
 137         /* Paravirt-compatible boot parameters.  Look to see what architecture
 138                 we're booting under. */
 139         movl pa(boot_params + BP_hardware_subarch), %eax
 140         cmpl $num_subarch_entries, %eax
 141         jae bad_subarch
 142
 143         movl pa(subarch_entries)(,%eax,4), %eax
 144         subl $__PAGE_OFFSET, %eax
 145         jmp *%eax
 146
 147 bad_subarch:
 148 WEAK(lguest_entry)
 149 WEAK(xen_entry)
 150         /* Unknown implementation; there's really
 151            nothing we can do at this point. */
 152         ud2a
 153
 154         __INITDATA
 155
 156 subarch_entries:
 157         .long default_entry             /* normal x86/PC */
 158         .long lguest_entry              /* lguest hypervisor */
 159         .long xen_entry                 /* Xen hypervisor */
 160         .long default_entry             /* Moorestown MID */
 161 num_subarch_entries = (. - subarch_entries) / 4
 162 .previous
 163 #endif /* CONFIG_PARAVIRT */
 164
 165 /*
 166  * Initialize page tables.  This creates a PDE and a set of page
 167  * tables, which are located immediately beyond __brk_base.  The variable
 168  * _brk_end is set up to point to the first "safe" location.
 169  * Mappings are created both at virtual address 0 (identity mapping)
 170  * and PAGE_OFFSET for up to _end.
 171  *
 172  * Note that the stack is not yet set up!
 173  */
 174 default_entry:
 175 #ifdef CONFIG_X86_PAE
 176
 177         /*
 178          * In PAE mode swapper_pg_dir is statically defined to contain enough
 179          * entries to cover the VMSPLIT option (that is the top 1, 2 or 3
 180          * entries). The identity mapping is handled by pointing two PGD
 181          * entries to the first kernel PMD.
 182          *
 183          * Note the upper half of each PMD or PTE are always zero at
 184          * this stage.
 185          */
 186
 187 #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
 188
 189         xorl %ebx,%ebx                          /* %ebx is kept at zero */
 190
 191         movl $pa(__brk_base), %edi
 192         movl $pa(swapper_pg_pmd), %edx
 193         movl $PTE_IDENT_ATTR, %eax
 194 10:
 195         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PMD entry */
 196         movl %ecx,(%edx)                        /* Store PMD entry */
 197                                                 /* Upper half already zero */
 198         addl $8,%edx
 199         movl $512,%ecx
 200 11:
 201         stosl
 202         xchgl %eax,%ebx
 203         stosl
 204         xchgl %eax,%ebx
 205         addl $0x1000,%eax
 206         loop 11b
 207
 208         /*
 209          * End condition: we must map up to the end + MAPPING_BEYOND_END.
 210          */
 211         movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
 212         cmpl %ebp,%eax
 213         jb 10b
 214 1:
 215         addl $__PAGE_OFFSET, %edi
 216         movl %edi, pa(_brk_end)
 217         shrl $12, %eax
 218         movl %eax, pa(max_pfn_mapped)
 219
 220         /* Do early initialization of the fixmap area */
 221         movl $pa(swapper_pg_fixmap)+PDE_IDENT_ATTR,%eax
 222         movl %eax,pa(swapper_pg_pmd+0x1000*KPMDS-8)
 223 #else   /* Not PAE */
 224
 225 page_pde_offset = (__PAGE_OFFSET >> 20);
 226
 227         movl $pa(__brk_base), %edi
 228         movl $pa(swapper_pg_dir), %edx
 229         movl $PTE_IDENT_ATTR, %eax
 230 10:
 231         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PDE entry */
 232         movl %ecx,(%edx)                        /* Store identity PDE entry */
 233         movl %ecx,page_pde_offset(%edx)         /* Store kernel PDE entry */
 234         addl $4,%edx
 235         movl $1024, %ecx
 236 11:
 237         stosl
 238         addl $0x1000,%eax
 239         loop 11b
 240         /*
 241          * End condition: we must map up to the end + MAPPING_BEYOND_END.
 242          */
 243         movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
 244         cmpl %ebp,%eax
 245         jb 10b
 246         addl $__PAGE_OFFSET, %edi
 247         movl %edi, pa(_brk_end)
 248         shrl $12, %eax
 249         movl %eax, pa(max_pfn_mapped)
 250
 251         /* Do early initialization of the fixmap area */
 252         movl $pa(swapper_pg_fixmap)+PDE_IDENT_ATTR,%eax
 253         movl %eax,pa(swapper_pg_dir+0xffc)
 254 #endif
 255         jmp 3f
 256 /*
 257  * Non-boot CPU entry point; entered from trampoline.S
 258  * We can't lgdt here, because lgdt itself uses a data segment, but
 259  * we know the trampoline has already loaded the boot_gdt for us.
 260  *
 261  * If cpu hotplug is not supported then this code can go in init section
 262  * which will be freed later
 263  */
 264
 265 __CPUINIT
 266
 267 #ifdef CONFIG_SMP
 268 ENTRY(startup_32_smp)
 269         cld
 270         movl $(__BOOT_DS),%eax
 271         movl %eax,%ds
 272         movl %eax,%es
 273         movl %eax,%fs
 274         movl %eax,%gs
 275 #endif /* CONFIG_SMP */
 276 3:
 277
 278 /*
 279  *      New page tables may be in 4Mbyte page mode and may
 280  *      be using the global pages.
 281  *
 282  *      NOTE! If we are on a 486 we may have no cr4 at all!
 283  *      So we do not try to touch it unless we really have
 284  *      some bits in it to set.  This won't work if the BSP
 285  *      implements cr4 but this AP does not -- very unlikely
 286  *      but be warned!  The same applies to the pse feature
 287  *      if not equally supported. --macro
 288  *
 289  *      NOTE! We have to correct for the fact that we're
 290  *      not yet offset PAGE_OFFSET..
 291  */
 292 #define cr4_bits pa(mmu_cr4_features)
 293         movl cr4_bits,%edx
 294         andl %edx,%edx
 295         jz 6f
 296         movl %cr4,%eax          # Turn on paging options (PSE,PAE,..)
 297         orl %edx,%eax
 298         movl %eax,%cr4
 299
 300         btl $5, %eax            # check if PAE is enabled
 301         jnc 6f
 302
 303         /* Check if extended functions are implemented */
 304         movl $0x80000000, %eax
 305         cpuid
 306         cmpl $0x80000000, %eax
 307         jbe 6f
 308         mov $0x80000001, %eax
 309         cpuid
 310         /* Execute Disable bit supported? */
 311         btl $20, %edx
 312         jnc 6f
 313
 314         /* Setup EFER (Extended Feature Enable Register) */
 315         movl $0xc0000080, %ecx
 316         rdmsr
 317
 318         btsl $11, %eax
 319         /* Make changes effective */
 320         wrmsr
 321
 322 6:
 323
 324 /*
 325  * Enable paging
 326  */
 327         movl $pa(swapper_pg_dir),%eax
 328         movl %eax,%cr3          /* set the page table pointer.. */
 329         movl %cr0,%eax
 330         orl  $X86_CR0_PG,%eax
 331         movl %eax,%cr0          /* ..and set paging (PG) bit */
 332         ljmp $__BOOT_CS,$1f     /* Clear prefetch and normalize %eip */
 333 1:
 334         /* Set up the stack pointer */
 335         lss stack_start,%esp
 336
 337 /*
 338  * Initialize eflags.  Some BIOS's leave bits like NT set.  This would
 339  * confuse the debugger if this code is traced.
 340  * XXX - best to initialize before switching to protected mode.
 341  */
 342         pushl $0
 343         popfl
 344
 345 #ifdef CONFIG_SMP
 346         cmpb $0, ready
 347         jz  1f                          /* Initial CPU cleans BSS */
 348         jmp checkCPUtype
 349 1:
 350 #endif /* CONFIG_SMP */
 351
 352 /*
 353  * start system 32-bit setup. We need to re-do some of the things done
 354  * in 16-bit mode for the "real" operations.
 355  */
 356         call setup_idt
 357
 358 checkCPUtype:
 359
 360         movl $-1,X86_CPUID              #  -1 for no CPUID initially
 361
 362 /* check if it is 486 or 386. */
 363 /*
 364  * XXX - this does a lot of unnecessary setup.  Alignment checks don't
 365  * apply at our cpl of 0 and the stack ought to be aligned already, and
 366  * we don't need to preserve eflags.
 367  */
 368
 369         movb $3,X86             # at least 386
 370         pushfl                  # push EFLAGS
 371         popl %eax               # get EFLAGS
 372         movl %eax,%ecx          # save original EFLAGS
 373         xorl $0x240000,%eax     # flip AC and ID bits in EFLAGS
 374         pushl %eax              # copy to EFLAGS
 375         popfl                   # set EFLAGS
 376         pushfl                  # get new EFLAGS
 377         popl %eax               # put it in eax
 378         xorl %ecx,%eax          # change in flags
 379         pushl %ecx              # restore original EFLAGS
 380         popfl
 381         testl $0x40000,%eax     # check if AC bit changed
 382         je is386
 383
 384         movb $4,X86             # at least 486
 385         testl $0x200000,%eax    # check if ID bit changed
 386         je is486
 387
 388         /* get vendor info */
 389         xorl %eax,%eax                  # call CPUID with 0 -> return vendor ID
 390         cpuid
 391         movl %eax,X86_CPUID             # save CPUID level
 392         movl %ebx,X86_VENDOR_ID         # lo 4 chars
 393         movl %edx,X86_VENDOR_ID+4       # next 4 chars
 394         movl %ecx,X86_VENDOR_ID+8       # last 4 chars
 395
 396         orl %eax,%eax                   # do we have processor info as well?
 397         je is486
 398
 399         movl $1,%eax            # Use the CPUID instruction to get CPU type
 400         cpuid
 401         movb %al,%cl            # save reg for future use
 402         andb $0x0f,%ah          # mask processor family
 403         movb %ah,X86
 404         andb $0xf0,%al          # mask model
 405         shrb $4,%al
 406         movb %al,X86_MODEL
 407         andb $0x0f,%cl          # mask mask revision
 408         movb %cl,X86_MASK
 409         movl %edx,X86_CAPABILITY
 410
 411 is486:  movl $0x50022,%ecx      # set AM, WP, NE and MP
 412         jmp 2f
 413
 414 is386:  movl $2,%ecx            # set MP
 415 2:      movl %cr0,%eax
 416         andl $0x80000011,%eax   # Save PG,PE,ET
 417         orl %ecx,%eax
 418         movl %eax,%cr0
 419
 420         call check_x87
 421         lgdt early_gdt_descr
 422         lidt idt_descr
 423         ljmp $(__KERNEL_CS),$1f
 424 1:      movl $(__KERNEL_DS),%eax        # reload all the segment registers
 425         movl %eax,%ss                   # after changing gdt.
 426
 427         movl $(__USER_DS),%eax          # DS/ES contains default USER segment
 428         movl %eax,%ds
 429         movl %eax,%es
 430
 431         movl $(__KERNEL_PERCPU), %eax
 432         movl %eax,%fs                   # set this cpu's percpu
 433
 434 #ifdef CONFIG_CC_STACKPROTECTOR
 435         /*
 436          * The linker can't handle this by relocation.  Manually set
 437          * base address in stack canary segment descriptor.
 438          */
 439         cmpb $0,ready
 440         jne 1f
 441         movl $per_cpu__gdt_page,%eax
 442         movl $per_cpu__stack_canary,%ecx
 443         movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
 444         shrl $16, %ecx
 445         movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
 446         movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
 447 1:
 448 #endif
 449         movl $(__KERNEL_STACK_CANARY),%eax
 450         movl %eax,%gs
 451
 452         xorl %eax,%eax                  # Clear LDT
 453         lldt %ax
 454
 455         cld                     # gcc2 wants the direction flag cleared at all times
 456         pushl $0                # fake return address for unwinder
 457 #ifdef CONFIG_SMP
 458         movb ready, %cl
 459         movb $1, ready
 460         cmpb $0,%cl             # the first CPU calls start_kernel
 461         je   1f
 462         movl (stack_start), %esp
 463 1:
 464 #endif /* CONFIG_SMP */
 465         jmp *(initial_code)
 466
 467 /*
 468  * We depend on ET to be correct. This checks for 287/387.
 469  */
 470 check_x87:
 471         movb $0,X86_HARD_MATH
 472         clts
 473         fninit
 474         fstsw %ax
 475         cmpb $0,%al
 476         je 1f
 477         movl %cr0,%eax          /* no coprocessor: have to set bits */
 478         xorl $4,%eax            /* set EM */
 479         movl %eax,%cr0
 480         ret
 481         ALIGN
 482 1:      movb $1,X86_HARD_MATH
 483         .byte 0xDB,0xE4         /* fsetpm for 287, ignored by 387 */
 484         ret
 485
 486 /*
 487  *  setup_idt
 488  *
 489  *  sets up a idt with 256 entries pointing to
 490  *  ignore_int, interrupt gates. It doesn't actually load
 491  *  idt - that can be done only after paging has been enabled
 492  *  and the kernel moved to PAGE_OFFSET. Interrupts
 493  *  are enabled elsewhere, when we can be relatively
 494  *  sure everything is ok.
 495  *
 496  *  Warning: %esi is live across this function.
 497  */
 498 setup_idt:
 499         lea ignore_int,%edx
 500         movl $(__KERNEL_CS << 16),%eax
 501         movw %dx,%ax            /* selector = 0x0010 = cs */
 502         movw $0x8E00,%dx        /* interrupt gate - dpl=0, present */
 503
 504         lea idt_table,%edi
 505         mov $256,%ecx
 506 rp_sidt:
 507         movl %eax,(%edi)
 508         movl %edx,4(%edi)
 509         addl $8,%edi
 510         dec %ecx
 511         jne rp_sidt
 512
 513 .macro  set_early_handler handler,trapno
 514         lea \handler,%edx
 515         movl $(__KERNEL_CS << 16),%eax
 516         movw %dx,%ax
 517         movw $0x8E00,%dx        /* interrupt gate - dpl=0, present */
 518         lea idt_table,%edi
 519         movl %eax,8*\trapno(%edi)
 520         movl %edx,8*\trapno+4(%edi)
 521 .endm
 522
 523         set_early_handler handler=early_divide_err,trapno=0
 524         set_early_handler handler=early_illegal_opcode,trapno=6
 525         set_early_handler handler=early_protection_fault,trapno=13
 526         set_early_handler handler=early_page_fault,trapno=14
 527
 528         ret
 529
 530 early_divide_err:
 531         xor %edx,%edx
 532         pushl $0        /* fake errcode */
 533         jmp early_fault
 534
 535 early_illegal_opcode:
 536         movl $6,%edx
 537         pushl $0        /* fake errcode */
 538         jmp early_fault
 539
 540 early_protection_fault:
 541         movl $13,%edx
 542         jmp early_fault
 543
 544 early_page_fault:
 545         movl $14,%edx
 546         jmp early_fault
 547
 548 early_fault:
 549         cld
 550 #ifdef CONFIG_PRINTK
 551         pusha
 552         movl $(__KERNEL_DS),%eax
 553         movl %eax,%ds
 554         movl %eax,%es
 555         cmpl $2,early_recursion_flag
 556         je hlt_loop
 557         incl early_recursion_flag
 558         movl %cr2,%eax
 559         pushl %eax
 560         pushl %edx              /* trapno */
 561         pushl $fault_msg
 562         call printk
 563 #endif
 564         call dump_stack
 565 hlt_loop:
 566         hlt
 567         jmp hlt_loop
 568
 569 /* This is the default interrupt "handler" :-) */
 570         ALIGN
 571 ignore_int:
 572         cld
 573 #ifdef CONFIG_PRINTK
 574         pushl %eax
 575         pushl %ecx
 576         pushl %edx
 577         pushl %es
 578         pushl %ds
 579         movl $(__KERNEL_DS),%eax
 580         movl %eax,%ds
 581         movl %eax,%es
 582         cmpl $2,early_recursion_flag
 583         je hlt_loop
 584         incl early_recursion_flag
 585         pushl 16(%esp)
 586         pushl 24(%esp)
 587         pushl 32(%esp)
 588         pushl 40(%esp)
 589         pushl $int_msg
 590         call printk
 591
 592         call dump_stack
 593
 594         addl $(5*4),%esp
 595         popl %ds
 596         popl %es
 597         popl %edx
 598         popl %ecx
 599         popl %eax
 600 #endif
 601         iret
 602
 603         __REFDATA
 604 .align 4
 605 ENTRY(initial_code)
 606         .long i386_start_kernel
 607
 608 /*
 609  * BSS section
 610  */
 611 __PAGE_ALIGNED_BSS
 612         .align PAGE_SIZE_asm
 613 #ifdef CONFIG_X86_PAE
 614 swapper_pg_pmd:
 615         .fill 1024*KPMDS,4,0
 616 #else
 617 ENTRY(swapper_pg_dir)
 618         .fill 1024,4,0
 619 #endif
 620 swapper_pg_fixmap:
 621         .fill 1024,4,0
 622 ENTRY(empty_zero_page)
 623         .fill 4096,1,0
 624
 625 /*
 626  * This starts the data section.
 627  */
 628 #ifdef CONFIG_X86_PAE
 629 __PAGE_ALIGNED_DATA
 630         /* Page-aligned for the benefit of paravirt? */
 631         .align PAGE_SIZE_asm
 632 ENTRY(swapper_pg_dir)
 633         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0     /* low identity map */
 634 # if KPMDS == 3
 635         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
 636         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 637         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x2000),0
 638 # elif KPMDS == 2
 639         .long   0,0
 640         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
 641         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 642 # elif KPMDS == 1
 643         .long   0,0
 644         .long   0,0
 645         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
 646 # else
 647 #  error "Kernel PMDs should be 1, 2 or 3"
 648 # endif
 649         .align PAGE_SIZE_asm            /* needs to be page-sized too */
 650 #endif
 651
 652 .data
 653 ENTRY(stack_start)
 654         .long init_thread_union+THREAD_SIZE
 655         .long __BOOT_DS
 656
 657 ready:  .byte 0
 658
 659 early_recursion_flag:
 660         .long 0
 661
 662 int_msg:
 663         .asciz "Unknown interrupt or fault at: %p %p %p\n"
 664
 665 fault_msg:
 666 /* fault info: */
 667         .ascii "BUG: Int %d: CR2 %p\n"
 668 /* pusha regs: */
 669         .ascii "     EDI %p  ESI %p  EBP %p  ESP %p\n"
 670         .ascii "     EBX %p  EDX %p  ECX %p  EAX %p\n"
 671 /* fault frame: */
 672         .ascii "     err %p  EIP %p   CS %p  flg %p\n"
 673         .ascii "Stack: %p %p %p %p %p %p %p %p\n"
 674         .ascii "       %p %p %p %p %p %p %p %p\n"
 675         .asciz "       %p %p %p %p %p %p %p %p\n"
 676
 677 #include "../../x86/xen/xen-head.S"
 678
 679 /*
 680  * The IDT and GDT 'descriptors' are a strange 48-bit object
 681  * only used by the lidt and lgdt instructions. They are not
 682  * like usual segment descriptors - they consist of a 16-bit
 683  * segment size, and 32-bit linear address value:
 684  */
 685
 686 .globl boot_gdt_descr
 687 .globl idt_descr
 688
 689         ALIGN
 690 # early boot GDT descriptor (must use 1:1 address mapping)
 691         .word 0                         # 32 bit align gdt_desc.address
 692 boot_gdt_descr:
 693         .word __BOOT_DS+7
 694         .long boot_gdt - __PAGE_OFFSET
 695
 696         .word 0                         # 32-bit align idt_desc.address
 697 idt_descr:
 698         .word IDT_ENTRIES*8-1           # idt contains 256 entries
 699         .long idt_table
 700
 701 # boot GDT descriptor (later on used by CPU#0):
 702         .word 0                         # 32 bit align gdt_desc.address
 703 ENTRY(early_gdt_descr)
 704         .word GDT_ENTRIES*8-1
 705         .long per_cpu__gdt_page         /* Overwritten for secondary CPUs */
 706
 707 /*
 708  * The boot_gdt must mirror the equivalent in setup.S and is
 709  * used only for booting.
 710  */
 711         .align L1_CACHE_BYTES
 712 ENTRY(boot_gdt)
 713         .fill GDT_ENTRY_BOOT_CS,8,0
 714         .quad 0x00cf9a000000ffff        /* kernel 4GB code at 0x00000000 */
 715         .quad 0x00cf92000000ffff        /* kernel 4GB data at 0x00000000 */