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/desc.h>
  17 #include <asm/cache.h>
  18 #include <asm/thread_info.h>
  19 #include <asm/asm-offsets.h>
  20 #include <asm/setup.h>
  21 #include <asm/processor-flags.h>
  22 #include <asm/percpu.h>
  23
  24 /* Physical address */
  25 #define pa(X) ((X) - __PAGE_OFFSET)
  26
  27 /*
  28  * References to members of the new_cpu_data structure.
  29  */
  30
  31 #define X86             new_cpu_data+CPUINFO_x86
  32 #define X86_VENDOR      new_cpu_data+CPUINFO_x86_vendor
  33 #define X86_MODEL       new_cpu_data+CPUINFO_x86_model
  34 #define X86_MASK        new_cpu_data+CPUINFO_x86_mask
  35 #define X86_HARD_MATH   new_cpu_data+CPUINFO_hard_math
  36 #define X86_CPUID       new_cpu_data+CPUINFO_cpuid_level
  37 #define X86_CAPABILITY  new_cpu_data+CPUINFO_x86_capability
  38 #define X86_VENDOR_ID   new_cpu_data+CPUINFO_x86_vendor_id
  39
  40 /*
  41  * This is how much memory in addition to the memory covered up to
  42  * and including _end we need mapped initially.
  43  * We need:
  44  *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
  45  *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
  46  *
  47  * Modulo rounding, each megabyte assigned here requires a kilobyte of
  48  * memory, which is currently unreclaimed.
  49  *
  50  * This should be a multiple of a page.
  51  *
  52  * KERNEL_IMAGE_SIZE should be greater than pa(_end)
  53  * and small than max_low_pfn, otherwise will waste some page table entries
  54  */
  55
  56 #if PTRS_PER_PMD > 1
  57 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
  58 #else
  59 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
  60 #endif
  61
  62 /* Enough space to fit pagetables for the low memory linear map */
  63 MAPPING_BEYOND_END = \
  64         PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT
  65
  66 /*
  67  * Worst-case size of the kernel mapping we need to make:
  68  * the worst-case size of the kernel itself, plus the extra we need
  69  * to map for the linear map.
  70  */
  71 KERNEL_PAGES = (KERNEL_IMAGE_SIZE + MAPPING_BEYOND_END)>>PAGE_SHIFT
  72
  73 INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE_asm
  74 RESERVE_BRK(pagetables, INIT_MAP_SIZE)
  75
  76 /*
  77  * 32-bit kernel entrypoint; only used by the boot CPU.  On entry,
  78  * %esi points to the real-mode code as a 32-bit pointer.
  79  * CS and DS must be 4 GB flat segments, but we don't depend on
  80  * any particular GDT layout, because we load our own as soon as we
  81  * can.
  82  */
  83 .section .text.head,"ax",@progbits
  84 ENTRY(startup_32)
  85         /* test KEEP_SEGMENTS flag to see if the bootloader is asking
  86                 us to not reload segments */
  87         testb $(1<<6), BP_loadflags(%esi)
  88         jnz 2f
  89
  90 /*
  91  * Set segments to known values.
  92  */
  93         lgdt pa(boot_gdt_descr)
  94         movl $(__BOOT_DS),%eax
  95         movl %eax,%ds
  96         movl %eax,%es
  97         movl %eax,%fs
  98         movl %eax,%gs
  99 2:
 100
 101 /*
 102  * Clear BSS first so that there are no surprises...
 103  */
 104         cld
 105         xorl %eax,%eax
 106         movl $pa(__bss_start),%edi
 107         movl $pa(__bss_stop),%ecx
 108         subl %edi,%ecx
 109         shrl $2,%ecx
 110         rep ; stosl
 111 /*
 112  * Copy bootup parameters out of the way.
 113  * Note: %esi still has the pointer to the real-mode data.
 114  * With the kexec as boot loader, parameter segment might be loaded beyond
 115  * kernel image and might not even be addressable by early boot page tables.
 116  * (kexec on panic case). Hence copy out the parameters before initializing
 117  * page tables.
 118  */
 119         movl $pa(boot_params),%edi
 120         movl $(PARAM_SIZE/4),%ecx
 121         cld
 122         rep
 123         movsl
 124         movl pa(boot_params) + NEW_CL_POINTER,%esi
 125         andl %esi,%esi
 126         jz 1f                   # No comand line
 127         movl $pa(boot_command_line),%edi
 128         movl $(COMMAND_LINE_SIZE/4),%ecx
 129         rep
 130         movsl
 131 1:
 132
 133 #ifdef CONFIG_PARAVIRT
 134         /* This is can only trip for a broken bootloader... */
 135         cmpw $0x207, pa(boot_params + BP_version)
 136         jb default_entry
 137
 138         /* Paravirt-compatible boot parameters.  Look to see what architecture
 139                 we're booting under. */
 140         movl pa(boot_params + BP_hardware_subarch), %eax
 141         cmpl $num_subarch_entries, %eax
 142         jae bad_subarch
 143
 144         movl pa(subarch_entries)(,%eax,4), %eax
 145         subl $__PAGE_OFFSET, %eax
 146         jmp *%eax
 147
 148 bad_subarch:
 149 WEAK(lguest_entry)
 150 WEAK(xen_entry)
 151         /* Unknown implementation; there's really
 152            nothing we can do at this point. */
 153         ud2a
 154
 155         __INITDATA
 156
 157 subarch_entries:
 158         .long default_entry             /* normal x86/PC */
 159         .long lguest_entry              /* lguest hypervisor */
 160         .long xen_entry                 /* Xen hypervisor */
 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 #ifndef CONFIG_HOTPLUG_CPU
 266 .section .init.text,"ax",@progbits
 267 #endif
 268
 269 #ifdef CONFIG_SMP
 270 ENTRY(startup_32_smp)
 271         cld
 272         movl $(__BOOT_DS),%eax
 273         movl %eax,%ds
 274         movl %eax,%es
 275         movl %eax,%fs
 276         movl %eax,%gs
 277 #endif /* CONFIG_SMP */
 278 3:
 279
 280 /*
 281  *      New page tables may be in 4Mbyte page mode and may
 282  *      be using the global pages.
 283  *
 284  *      NOTE! If we are on a 486 we may have no cr4 at all!
 285  *      So we do not try to touch it unless we really have
 286  *      some bits in it to set.  This won't work if the BSP
 287  *      implements cr4 but this AP does not -- very unlikely
 288  *      but be warned!  The same applies to the pse feature
 289  *      if not equally supported. --macro
 290  *
 291  *      NOTE! We have to correct for the fact that we're
 292  *      not yet offset PAGE_OFFSET..
 293  */
 294 #define cr4_bits pa(mmu_cr4_features)
 295         movl cr4_bits,%edx
 296         andl %edx,%edx
 297         jz 6f
 298         movl %cr4,%eax          # Turn on paging options (PSE,PAE,..)
 299         orl %edx,%eax
 300         movl %eax,%cr4
 301
 302         btl $5, %eax            # check if PAE is enabled
 303         jnc 6f
 304
 305         /* Check if extended functions are implemented */
 306         movl $0x80000000, %eax
 307         cpuid
 308         cmpl $0x80000000, %eax
 309         jbe 6f
 310         mov $0x80000001, %eax
 311         cpuid
 312         /* Execute Disable bit supported? */
 313         btl $20, %edx
 314         jnc 6f
 315
 316         /* Setup EFER (Extended Feature Enable Register) */
 317         movl $0xc0000080, %ecx
 318         rdmsr
 319
 320         btsl $11, %eax
 321         /* Make changes effective */
 322         wrmsr
 323
 324 6:
 325
 326 /*
 327  * Enable paging
 328  */
 329         movl $pa(swapper_pg_dir),%eax
 330         movl %eax,%cr3          /* set the page table pointer.. */
 331         movl %cr0,%eax
 332         orl  $X86_CR0_PG,%eax
 333         movl %eax,%cr0          /* ..and set paging (PG) bit */
 334         ljmp $__BOOT_CS,$1f     /* Clear prefetch and normalize %eip */
 335 1:
 336         /* Set up the stack pointer */
 337         lss stack_start,%esp
 338
 339 /*
 340  * Initialize eflags.  Some BIOS's leave bits like NT set.  This would
 341  * confuse the debugger if this code is traced.
 342  * XXX - best to initialize before switching to protected mode.
 343  */
 344         pushl $0
 345         popfl
 346
 347 #ifdef CONFIG_SMP
 348         cmpb $0, ready
 349         jz  1f                          /* Initial CPU cleans BSS */
 350         jmp checkCPUtype
 351 1:
 352 #endif /* CONFIG_SMP */
 353
 354 /*
 355  * start system 32-bit setup. We need to re-do some of the things done
 356  * in 16-bit mode for the "real" operations.
 357  */
 358         call setup_idt
 359
 360 checkCPUtype:
 361
 362         movl $-1,X86_CPUID              #  -1 for no CPUID initially
 363
 364 /* check if it is 486 or 386. */
 365 /*
 366  * XXX - this does a lot of unnecessary setup.  Alignment checks don't
 367  * apply at our cpl of 0 and the stack ought to be aligned already, and
 368  * we don't need to preserve eflags.
 369  */
 370
 371         movb $3,X86             # at least 386
 372         pushfl                  # push EFLAGS
 373         popl %eax               # get EFLAGS
 374         movl %eax,%ecx          # save original EFLAGS
 375         xorl $0x240000,%eax     # flip AC and ID bits in EFLAGS
 376         pushl %eax              # copy to EFLAGS
 377         popfl                   # set EFLAGS
 378         pushfl                  # get new EFLAGS
 379         popl %eax               # put it in eax
 380         xorl %ecx,%eax          # change in flags
 381         pushl %ecx              # restore original EFLAGS
 382         popfl
 383         testl $0x40000,%eax     # check if AC bit changed
 384         je is386
 385
 386         movb $4,X86             # at least 486
 387         testl $0x200000,%eax    # check if ID bit changed
 388         je is486
 389
 390         /* get vendor info */
 391         xorl %eax,%eax                  # call CPUID with 0 -> return vendor ID
 392         cpuid
 393         movl %eax,X86_CPUID             # save CPUID level
 394         movl %ebx,X86_VENDOR_ID         # lo 4 chars
 395         movl %edx,X86_VENDOR_ID+4       # next 4 chars
 396         movl %ecx,X86_VENDOR_ID+8       # last 4 chars
 397
 398         orl %eax,%eax                   # do we have processor info as well?
 399         je is486
 400
 401         movl $1,%eax            # Use the CPUID instruction to get CPU type
 402         cpuid
 403         movb %al,%cl            # save reg for future use
 404         andb $0x0f,%ah          # mask processor family
 405         movb %ah,X86
 406         andb $0xf0,%al          # mask model
 407         shrb $4,%al
 408         movb %al,X86_MODEL
 409         andb $0x0f,%cl          # mask mask revision
 410         movb %cl,X86_MASK
 411         movl %edx,X86_CAPABILITY
 412
 413 is486:  movl $0x50022,%ecx      # set AM, WP, NE and MP
 414         jmp 2f
 415
 416 is386:  movl $2,%ecx            # set MP
 417 2:      movl %cr0,%eax
 418         andl $0x80000011,%eax   # Save PG,PE,ET
 419         orl %ecx,%eax
 420         movl %eax,%cr0
 421
 422         call check_x87
 423         lgdt early_gdt_descr
 424         lidt idt_descr
 425         ljmp $(__KERNEL_CS),$1f
 426 1:      movl $(__KERNEL_DS),%eax        # reload all the segment registers
 427         movl %eax,%ss                   # after changing gdt.
 428
 429         movl $(__USER_DS),%eax          # DS/ES contains default USER segment
 430         movl %eax,%ds
 431         movl %eax,%es
 432
 433         movl $(__KERNEL_PERCPU), %eax
 434         movl %eax,%fs                   # set this cpu's percpu
 435
 436 #ifdef CONFIG_CC_STACKPROTECTOR
 437         /*
 438          * The linker can't handle this by relocation.  Manually set
 439          * base address in stack canary segment descriptor.
 440          */
 441         cmpb $0,ready
 442         jne 1f
 443         movl $per_cpu__gdt_page,%eax
 444         movl $per_cpu__stack_canary,%ecx
 445         subl $20, %ecx
 446         movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
 447         shrl $16, %ecx
 448         movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
 449         movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
 450 1:
 451 #endif
 452         movl $(__KERNEL_STACK_CANARY),%eax
 453         movl %eax,%gs
 454
 455         xorl %eax,%eax                  # Clear LDT
 456         lldt %ax
 457
 458         cld                     # gcc2 wants the direction flag cleared at all times
 459         pushl $0                # fake return address for unwinder
 460 #ifdef CONFIG_SMP
 461         movb ready, %cl
 462         movb $1, ready
 463         cmpb $0,%cl             # the first CPU calls start_kernel
 464         je   1f
 465         movl (stack_start), %esp
 466 1:
 467 #endif /* CONFIG_SMP */
 468         jmp *(initial_code)
 469
 470 /*
 471  * We depend on ET to be correct. This checks for 287/387.
 472  */
 473 check_x87:
 474         movb $0,X86_HARD_MATH
 475         clts
 476         fninit
 477         fstsw %ax
 478         cmpb $0,%al
 479         je 1f
 480         movl %cr0,%eax          /* no coprocessor: have to set bits */
 481         xorl $4,%eax            /* set EM */
 482         movl %eax,%cr0
 483         ret
 484         ALIGN
 485 1:      movb $1,X86_HARD_MATH
 486         .byte 0xDB,0xE4         /* fsetpm for 287, ignored by 387 */
 487         ret
 488
 489 /*
 490  *  setup_idt
 491  *
 492  *  sets up a idt with 256 entries pointing to
 493  *  ignore_int, interrupt gates. It doesn't actually load
 494  *  idt - that can be done only after paging has been enabled
 495  *  and the kernel moved to PAGE_OFFSET. Interrupts
 496  *  are enabled elsewhere, when we can be relatively
 497  *  sure everything is ok.
 498  *
 499  *  Warning: %esi is live across this function.
 500  */
 501 setup_idt:
 502         lea ignore_int,%edx
 503         movl $(__KERNEL_CS << 16),%eax
 504         movw %dx,%ax            /* selector = 0x0010 = cs */
 505         movw $0x8E00,%dx        /* interrupt gate - dpl=0, present */
 506
 507         lea idt_table,%edi
 508         mov $256,%ecx
 509 rp_sidt:
 510         movl %eax,(%edi)
 511         movl %edx,4(%edi)
 512         addl $8,%edi
 513         dec %ecx
 514         jne rp_sidt
 515
 516 .macro  set_early_handler handler,trapno
 517         lea \handler,%edx
 518         movl $(__KERNEL_CS << 16),%eax
 519         movw %dx,%ax
 520         movw $0x8E00,%dx        /* interrupt gate - dpl=0, present */
 521         lea idt_table,%edi
 522         movl %eax,8*\trapno(%edi)
 523         movl %edx,8*\trapno+4(%edi)
 524 .endm
 525
 526         set_early_handler handler=early_divide_err,trapno=0
 527         set_early_handler handler=early_illegal_opcode,trapno=6
 528         set_early_handler handler=early_protection_fault,trapno=13
 529         set_early_handler handler=early_page_fault,trapno=14
 530
 531         ret
 532
 533 early_divide_err:
 534         xor %edx,%edx
 535         pushl $0        /* fake errcode */
 536         jmp early_fault
 537
 538 early_illegal_opcode:
 539         movl $6,%edx
 540         pushl $0        /* fake errcode */
 541         jmp early_fault
 542
 543 early_protection_fault:
 544         movl $13,%edx
 545         jmp early_fault
 546
 547 early_page_fault:
 548         movl $14,%edx
 549         jmp early_fault
 550
 551 early_fault:
 552         cld
 553 #ifdef CONFIG_PRINTK
 554         pusha
 555         movl $(__KERNEL_DS),%eax
 556         movl %eax,%ds
 557         movl %eax,%es
 558         cmpl $2,early_recursion_flag
 559         je hlt_loop
 560         incl early_recursion_flag
 561         movl %cr2,%eax
 562         pushl %eax
 563         pushl %edx              /* trapno */
 564         pushl $fault_msg
 565         call printk
 566 #endif
 567         call dump_stack
 568 hlt_loop:
 569         hlt
 570         jmp hlt_loop
 571
 572 /* This is the default interrupt "handler" :-) */
 573         ALIGN
 574 ignore_int:
 575         cld
 576 #ifdef CONFIG_PRINTK
 577         pushl %eax
 578         pushl %ecx
 579         pushl %edx
 580         pushl %es
 581         pushl %ds
 582         movl $(__KERNEL_DS),%eax
 583         movl %eax,%ds
 584         movl %eax,%es
 585         cmpl $2,early_recursion_flag
 586         je hlt_loop
 587         incl early_recursion_flag
 588         pushl 16(%esp)
 589         pushl 24(%esp)
 590         pushl 32(%esp)
 591         pushl 40(%esp)
 592         pushl $int_msg
 593         call printk
 594
 595         call dump_stack
 596
 597         addl $(5*4),%esp
 598         popl %ds
 599         popl %es
 600         popl %edx
 601         popl %ecx
 602         popl %eax
 603 #endif
 604         iret
 605
 606 .section .cpuinit.data,"wa"
 607 .align 4
 608 ENTRY(initial_code)
 609         .long i386_start_kernel
 610
 611 .section .text
 612 /*
 613  * Real beginning of normal "text" segment
 614  */
 615 ENTRY(stext)
 616 ENTRY(_stext)
 617
 618 /*
 619  * BSS section
 620  */
 621 .section ".bss.page_aligned","wa"
 622         .align PAGE_SIZE_asm
 623 #ifdef CONFIG_X86_PAE
 624 swapper_pg_pmd:
 625         .fill 1024*KPMDS,4,0
 626 #else
 627 ENTRY(swapper_pg_dir)
 628         .fill 1024,4,0
 629 #endif
 630 swapper_pg_fixmap:
 631         .fill 1024,4,0
 632 ENTRY(empty_zero_page)
 633         .fill 4096,1,0
 634
 635 /*
 636  * This starts the data section.
 637  */
 638 #ifdef CONFIG_X86_PAE
 639 .section ".data.page_aligned","wa"
 640         /* Page-aligned for the benefit of paravirt? */
 641         .align PAGE_SIZE_asm
 642 ENTRY(swapper_pg_dir)
 643         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0     /* low identity map */
 644 # if KPMDS == 3
 645         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
 646         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 647         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x2000),0
 648 # elif KPMDS == 2
 649         .long   0,0
 650         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
 651         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 652 # elif KPMDS == 1
 653         .long   0,0
 654         .long   0,0
 655         .long   pa(swapper_pg_pmd+PGD_IDENT_ATTR),0
 656 # else
 657 #  error "Kernel PMDs should be 1, 2 or 3"
 658 # endif
 659         .align PAGE_SIZE_asm            /* needs to be page-sized too */
 660 #endif
 661
 662 .data
 663 ENTRY(stack_start)
 664         .long init_thread_union+THREAD_SIZE
 665         .long __BOOT_DS
 666
 667 ready:  .byte 0
 668
 669 early_recursion_flag:
 670         .long 0
 671
 672 int_msg:
 673         .asciz "Unknown interrupt or fault at: %p %p %p\n"
 674
 675 fault_msg:
 676 /* fault info: */
 677         .ascii "BUG: Int %d: CR2 %p\n"
 678 /* pusha regs: */
 679         .ascii "     EDI %p  ESI %p  EBP %p  ESP %p\n"
 680         .ascii "     EBX %p  EDX %p  ECX %p  EAX %p\n"
 681 /* fault frame: */
 682         .ascii "     err %p  EIP %p   CS %p  flg %p\n"
 683         .ascii "Stack: %p %p %p %p %p %p %p %p\n"
 684         .ascii "       %p %p %p %p %p %p %p %p\n"
 685         .asciz "       %p %p %p %p %p %p %p %p\n"
 686
 687 #include "../../x86/xen/xen-head.S"
 688
 689 /*
 690  * The IDT and GDT 'descriptors' are a strange 48-bit object
 691  * only used by the lidt and lgdt instructions. They are not
 692  * like usual segment descriptors - they consist of a 16-bit
 693  * segment size, and 32-bit linear address value:
 694  */
 695
 696 .globl boot_gdt_descr
 697 .globl idt_descr
 698
 699         ALIGN
 700 # early boot GDT descriptor (must use 1:1 address mapping)
 701         .word 0                         # 32 bit align gdt_desc.address
 702 boot_gdt_descr:
 703         .word __BOOT_DS+7
 704         .long boot_gdt - __PAGE_OFFSET
 705
 706         .word 0                         # 32-bit align idt_desc.address
 707 idt_descr:
 708         .word IDT_ENTRIES*8-1           # idt contains 256 entries
 709         .long idt_table
 710
 711 # boot GDT descriptor (later on used by CPU#0):
 712         .word 0                         # 32 bit align gdt_desc.address
 713 ENTRY(early_gdt_descr)
 714         .word GDT_ENTRIES*8-1
 715         .long per_cpu__gdt_page         /* Overwritten for secondary CPUs */
 716
 717 /*
 718  * The boot_gdt must mirror the equivalent in setup.S and is
 719  * used only for booting.
 720  */
 721         .align L1_CACHE_BYTES
 722 ENTRY(boot_gdt)
 723         .fill GDT_ENTRY_BOOT_CS,8,0
 724         .quad 0x00cf9a000000ffff        /* kernel 4GB code at 0x00000000 */
 725         .quad 0x00cf92000000ffff        /* kernel 4GB data at 0x00000000 */