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/msr-index.h>
  22 #include <asm/cpufeatures.h>
  23 #include <asm/percpu.h>
  24 #include <asm/nops.h>
  25 #include <asm/bootparam.h>
  26
  27 /* Physical address */
  28 #define pa(X) ((X) - __PAGE_OFFSET)
  29
  30 /*
  31  * References to members of the new_cpu_data structure.
  32  */
  33
  34 #define X86             new_cpu_data+CPUINFO_x86
  35 #define X86_VENDOR      new_cpu_data+CPUINFO_x86_vendor
  36 #define X86_MODEL       new_cpu_data+CPUINFO_x86_model
  37 #define X86_MASK        new_cpu_data+CPUINFO_x86_mask
  38 #define X86_HARD_MATH   new_cpu_data+CPUINFO_hard_math
  39 #define X86_CPUID       new_cpu_data+CPUINFO_cpuid_level
  40 #define X86_CAPABILITY  new_cpu_data+CPUINFO_x86_capability
  41 #define X86_VENDOR_ID   new_cpu_data+CPUINFO_x86_vendor_id
  42
  43 /*
  44  * This is how much memory in addition to the memory covered up to
  45  * and including _end we need mapped initially.
  46  * We need:
  47  *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
  48  *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
  49  *
  50  * Modulo rounding, each megabyte assigned here requires a kilobyte of
  51  * memory, which is currently unreclaimed.
  52  *
  53  * This should be a multiple of a page.
  54  *
  55  * KERNEL_IMAGE_SIZE should be greater than pa(_end)
  56  * and small than max_low_pfn, otherwise will waste some page table entries
  57  */
  58
  59 #if PTRS_PER_PMD > 1
  60 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
  61 #else
  62 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
  63 #endif
  64
  65 /*
  66  * Number of possible pages in the lowmem region.
  67  *
  68  * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
  69  * gas warning about overflowing shift count when gas has been compiled
  70  * with only a host target support using a 32-bit type for internal
  71  * representation.
  72  */
  73 LOWMEM_PAGES = (((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT)
  74
  75 /* Enough space to fit pagetables for the low memory linear map */
  76 MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
  77
  78 /*
  79  * Worst-case size of the kernel mapping we need to make:
  80  * a relocatable kernel can live anywhere in lowmem, so we need to be able
  81  * to map all of lowmem.
  82  */
  83 KERNEL_PAGES = LOWMEM_PAGES
  84
  85 INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
  86 RESERVE_BRK(pagetables, INIT_MAP_SIZE)
  87
  88 /*
  89  * 32-bit kernel entrypoint; only used by the boot CPU.  On entry,
  90  * %esi points to the real-mode code as a 32-bit pointer.
  91  * CS and DS must be 4 GB flat segments, but we don't depend on
  92  * any particular GDT layout, because we load our own as soon as we
  93  * can.
  94  */
  95 __HEAD
  96 ENTRY(startup_32)
  97         movl pa(stack_start),%ecx
  98
  99         /* test KEEP_SEGMENTS flag to see if the bootloader is asking
 100                 us to not reload segments */
 101         testb $KEEP_SEGMENTS, BP_loadflags(%esi)
 102         jnz 2f
 103
 104 /*
 105  * Set segments to known values.
 106  */
 107         lgdt pa(boot_gdt_descr)
 108         movl $(__BOOT_DS),%eax
 109         movl %eax,%ds
 110         movl %eax,%es
 111         movl %eax,%fs
 112         movl %eax,%gs
 113         movl %eax,%ss
 114 2:
 115         leal -__PAGE_OFFSET(%ecx),%esp
 116
 117 /*
 118  * Clear BSS first so that there are no surprises...
 119  */
 120         cld
 121         xorl %eax,%eax
 122         movl $pa(__bss_start),%edi
 123         movl $pa(__bss_stop),%ecx
 124         subl %edi,%ecx
 125         shrl $2,%ecx
 126         rep ; stosl
 127 /*
 128  * Copy bootup parameters out of the way.
 129  * Note: %esi still has the pointer to the real-mode data.
 130  * With the kexec as boot loader, parameter segment might be loaded beyond
 131  * kernel image and might not even be addressable by early boot page tables.
 132  * (kexec on panic case). Hence copy out the parameters before initializing
 133  * page tables.
 134  */
 135         movl $pa(boot_params),%edi
 136         movl $(PARAM_SIZE/4),%ecx
 137         cld
 138         rep
 139         movsl
 140         movl pa(boot_params) + NEW_CL_POINTER,%esi
 141         andl %esi,%esi
 142         jz 1f                   # No command line
 143         movl $pa(boot_command_line),%edi
 144         movl $(COMMAND_LINE_SIZE/4),%ecx
 145         rep
 146         movsl
 147 1:
 148
 149 #ifdef CONFIG_OLPC
 150         /* save OFW's pgdir table for later use when calling into OFW */
 151         movl %cr3, %eax
 152         movl %eax, pa(olpc_ofw_pgd)
 153 #endif
 154
 155 #ifdef CONFIG_MICROCODE
 156         /* Early load ucode on BSP. */
 157         call load_ucode_bsp
 158 #endif
 159
 160 /*
 161  * Initialize page tables.  This creates a PDE and a set of page
 162  * tables, which are located immediately beyond __brk_base.  The variable
 163  * _brk_end is set up to point to the first "safe" location.
 164  * Mappings are created both at virtual address 0 (identity mapping)
 165  * and PAGE_OFFSET for up to _end.
 166  */
 167 #ifdef CONFIG_X86_PAE
 168
 169         /*
 170          * In PAE mode initial_page_table is statically defined to contain
 171          * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
 172          * entries). The identity mapping is handled by pointing two PGD entries
 173          * to the first kernel PMD.
 174          *
 175          * Note the upper half of each PMD or PTE are always zero at this stage.
 176          */
 177
 178 #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
 179
 180         xorl %ebx,%ebx                          /* %ebx is kept at zero */
 181
 182         movl $pa(__brk_base), %edi
 183         movl $pa(initial_pg_pmd), %edx
 184         movl $PTE_IDENT_ATTR, %eax
 185 10:
 186         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PMD entry */
 187         movl %ecx,(%edx)                        /* Store PMD entry */
 188                                                 /* Upper half already zero */
 189         addl $8,%edx
 190         movl $512,%ecx
 191 11:
 192         stosl
 193         xchgl %eax,%ebx
 194         stosl
 195         xchgl %eax,%ebx
 196         addl $0x1000,%eax
 197         loop 11b
 198
 199         /*
 200          * End condition: we must map up to the end + MAPPING_BEYOND_END.
 201          */
 202         movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
 203         cmpl %ebp,%eax
 204         jb 10b
 205 1:
 206         addl $__PAGE_OFFSET, %edi
 207         movl %edi, pa(_brk_end)
 208         shrl $12, %eax
 209         movl %eax, pa(max_pfn_mapped)
 210
 211         /* Do early initialization of the fixmap area */
 212         movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
 213         movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
 214 #else   /* Not PAE */
 215
 216 page_pde_offset = (__PAGE_OFFSET >> 20);
 217
 218         movl $pa(__brk_base), %edi
 219         movl $pa(initial_page_table), %edx
 220         movl $PTE_IDENT_ATTR, %eax
 221 10:
 222         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PDE entry */
 223         movl %ecx,(%edx)                        /* Store identity PDE entry */
 224         movl %ecx,page_pde_offset(%edx)         /* Store kernel PDE entry */
 225         addl $4,%edx
 226         movl $1024, %ecx
 227 11:
 228         stosl
 229         addl $0x1000,%eax
 230         loop 11b
 231         /*
 232          * End condition: we must map up to the end + MAPPING_BEYOND_END.
 233          */
 234         movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
 235         cmpl %ebp,%eax
 236         jb 10b
 237         addl $__PAGE_OFFSET, %edi
 238         movl %edi, pa(_brk_end)
 239         shrl $12, %eax
 240         movl %eax, pa(max_pfn_mapped)
 241
 242         /* Do early initialization of the fixmap area */
 243         movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
 244         movl %eax,pa(initial_page_table+0xffc)
 245 #endif
 246
 247 #ifdef CONFIG_PARAVIRT
 248         /* This is can only trip for a broken bootloader... */
 249         cmpw $0x207, pa(boot_params + BP_version)
 250         jb default_entry
 251
 252         /* Paravirt-compatible boot parameters.  Look to see what architecture
 253                 we're booting under. */
 254         movl pa(boot_params + BP_hardware_subarch), %eax
 255         cmpl $num_subarch_entries, %eax
 256         jae bad_subarch
 257
 258         movl pa(subarch_entries)(,%eax,4), %eax
 259         subl $__PAGE_OFFSET, %eax
 260         jmp *%eax
 261
 262 bad_subarch:
 263 WEAK(lguest_entry)
 264 WEAK(xen_entry)
 265         /* Unknown implementation; there's really
 266            nothing we can do at this point. */
 267         ud2a
 268
 269         __INITDATA
 270
 271 subarch_entries:
 272         .long default_entry             /* normal x86/PC */
 273         .long lguest_entry              /* lguest hypervisor */
 274         .long xen_entry                 /* Xen hypervisor */
 275         .long default_entry             /* Moorestown MID */
 276 num_subarch_entries = (. - subarch_entries) / 4
 277 .previous
 278 #else
 279         jmp default_entry
 280 #endif /* CONFIG_PARAVIRT */
 281
 282 #ifdef CONFIG_HOTPLUG_CPU
 283 /*
 284  * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
 285  * up already except stack. We just set up stack here. Then call
 286  * start_secondary().
 287  */
 288 ENTRY(start_cpu0)
 289         movl stack_start, %ecx
 290         movl %ecx, %esp
 291         jmp  *(initial_code)
 292 ENDPROC(start_cpu0)
 293 #endif
 294
 295 /*
 296  * Non-boot CPU entry point; entered from trampoline.S
 297  * We can't lgdt here, because lgdt itself uses a data segment, but
 298  * we know the trampoline has already loaded the boot_gdt for us.
 299  *
 300  * If cpu hotplug is not supported then this code can go in init section
 301  * which will be freed later
 302  */
 303 ENTRY(startup_32_smp)
 304         cld
 305         movl $(__BOOT_DS),%eax
 306         movl %eax,%ds
 307         movl %eax,%es
 308         movl %eax,%fs
 309         movl %eax,%gs
 310         movl pa(stack_start),%ecx
 311         movl %eax,%ss
 312         leal -__PAGE_OFFSET(%ecx),%esp
 313
 314 #ifdef CONFIG_MICROCODE
 315         /* Early load ucode on AP. */
 316         call load_ucode_ap
 317 #endif
 318
 319 default_entry:
 320 #define CR0_STATE       (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
 321                          X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
 322                          X86_CR0_PG)
 323         movl $(CR0_STATE & ~X86_CR0_PG),%eax
 324         movl %eax,%cr0
 325
 326 /*
 327  * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
 328  * bits like NT set. This would confuse the debugger if this code is traced. So
 329  * initialize them properly now before switching to protected mode. That means
 330  * DF in particular (even though we have cleared it earlier after copying the
 331  * command line) because GCC expects it.
 332  */
 333         pushl $0
 334         popfl
 335
 336 /*
 337  * New page tables may be in 4Mbyte page mode and may be using the global pages.
 338  *
 339  * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
 340  * if and only if CPUID exists and has flags other than the FPU flag set.
 341  */
 342         movl $-1,pa(X86_CPUID)          # preset CPUID level
 343         movl $X86_EFLAGS_ID,%ecx
 344         pushl %ecx
 345         popfl                           # set EFLAGS=ID
 346         pushfl
 347         popl %eax                       # get EFLAGS
 348         testl $X86_EFLAGS_ID,%eax       # did EFLAGS.ID remained set?
 349         jz enable_paging                # hw disallowed setting of ID bit
 350                                         # which means no CPUID and no CR4
 351
 352         xorl %eax,%eax
 353         cpuid
 354         movl %eax,pa(X86_CPUID)         # save largest std CPUID function
 355
 356         movl $1,%eax
 357         cpuid
 358         andl $~1,%edx                   # Ignore CPUID.FPU
 359         jz enable_paging                # No flags or only CPUID.FPU = no CR4
 360
 361         movl pa(mmu_cr4_features),%eax
 362         movl %eax,%cr4
 363
 364         testb $X86_CR4_PAE, %al         # check if PAE is enabled
 365         jz enable_paging
 366
 367         /* Check if extended functions are implemented */
 368         movl $0x80000000, %eax
 369         cpuid
 370         /* Value must be in the range 0x80000001 to 0x8000ffff */
 371         subl $0x80000001, %eax
 372         cmpl $(0x8000ffff-0x80000001), %eax
 373         ja enable_paging
 374
 375         /* Clear bogus XD_DISABLE bits */
 376         call verify_cpu
 377
 378         mov $0x80000001, %eax
 379         cpuid
 380         /* Execute Disable bit supported? */
 381         btl $(X86_FEATURE_NX & 31), %edx
 382         jnc enable_paging
 383
 384         /* Setup EFER (Extended Feature Enable Register) */
 385         movl $MSR_EFER, %ecx
 386         rdmsr
 387
 388         btsl $_EFER_NX, %eax
 389         /* Make changes effective */
 390         wrmsr
 391
 392         /*
 393          * And make sure that all the mappings we set up have NX set from
 394          * the beginning.
 395          */
 396         orl $(1 << (_PAGE_BIT_NX - 32)), pa(__supported_pte_mask + 4)
 397
 398 enable_paging:
 399
 400 /*
 401  * Enable paging
 402  */
 403         movl $pa(initial_page_table), %eax
 404         movl %eax,%cr3          /* set the page table pointer.. */
 405         movl $CR0_STATE,%eax
 406         movl %eax,%cr0          /* ..and set paging (PG) bit */
 407         ljmp $__BOOT_CS,$1f     /* Clear prefetch and normalize %eip */
 408 1:
 409         /* Shift the stack pointer to a virtual address */
 410         addl $__PAGE_OFFSET, %esp
 411
 412 /*
 413  * start system 32-bit setup. We need to re-do some of the things done
 414  * in 16-bit mode for the "real" operations.
 415  */
 416         movl setup_once_ref,%eax
 417         andl %eax,%eax
 418         jz 1f                           # Did we do this already?
 419         call *%eax
 420 1:
 421
 422 /*
 423  * Check if it is 486
 424  */
 425         movb $4,X86                     # at least 486
 426         cmpl $-1,X86_CPUID
 427         je is486
 428
 429         /* get vendor info */
 430         xorl %eax,%eax                  # call CPUID with 0 -> return vendor ID
 431         cpuid
 432         movl %eax,X86_CPUID             # save CPUID level
 433         movl %ebx,X86_VENDOR_ID         # lo 4 chars
 434         movl %edx,X86_VENDOR_ID+4       # next 4 chars
 435         movl %ecx,X86_VENDOR_ID+8       # last 4 chars
 436
 437         orl %eax,%eax                   # do we have processor info as well?
 438         je is486
 439
 440         movl $1,%eax            # Use the CPUID instruction to get CPU type
 441         cpuid
 442         movb %al,%cl            # save reg for future use
 443         andb $0x0f,%ah          # mask processor family
 444         movb %ah,X86
 445         andb $0xf0,%al          # mask model
 446         shrb $4,%al
 447         movb %al,X86_MODEL
 448         andb $0x0f,%cl          # mask mask revision
 449         movb %cl,X86_MASK
 450         movl %edx,X86_CAPABILITY
 451
 452 is486:
 453         movl $0x50022,%ecx      # set AM, WP, NE and MP
 454         movl %cr0,%eax
 455         andl $0x80000011,%eax   # Save PG,PE,ET
 456         orl %ecx,%eax
 457         movl %eax,%cr0
 458
 459         lgdt early_gdt_descr
 460         lidt idt_descr
 461         ljmp $(__KERNEL_CS),$1f
 462 1:      movl $(__KERNEL_DS),%eax        # reload all the segment registers
 463         movl %eax,%ss                   # after changing gdt.
 464
 465         movl $(__USER_DS),%eax          # DS/ES contains default USER segment
 466         movl %eax,%ds
 467         movl %eax,%es
 468
 469         movl $(__KERNEL_PERCPU), %eax
 470         movl %eax,%fs                   # set this cpu's percpu
 471
 472         movl $(__KERNEL_STACK_CANARY),%eax
 473         movl %eax,%gs
 474
 475         xorl %eax,%eax                  # Clear LDT
 476         lldt %ax
 477
 478         pushl $0                # fake return address for unwinder
 479         jmp *(initial_code)
 480
 481 #include "verify_cpu.S"
 482
 483 /*
 484  *  setup_once
 485  *
 486  *  The setup work we only want to run on the BSP.
 487  *
 488  *  Warning: %esi is live across this function.
 489  */
 490 __INIT
 491 setup_once:
 492         /*
 493          * Set up a idt with 256 interrupt gates that push zero if there
 494          * is no error code and then jump to early_idt_handler_common.
 495          * It doesn't actually load the idt - that needs to be done on
 496          * each CPU. Interrupts are enabled elsewhere, when we can be
 497          * relatively sure everything is ok.
 498          */
 499
 500         movl $idt_table,%edi
 501         movl $early_idt_handler_array,%eax
 502         movl $NUM_EXCEPTION_VECTORS,%ecx
 503 1:
 504         movl %eax,(%edi)
 505         movl %eax,4(%edi)
 506         /* interrupt gate, dpl=0, present */
 507         movl $(0x8E000000 + __KERNEL_CS),2(%edi)
 508         addl $EARLY_IDT_HANDLER_SIZE,%eax
 509         addl $8,%edi
 510         loop 1b
 511
 512         movl $256 - NUM_EXCEPTION_VECTORS,%ecx
 513         movl $ignore_int,%edx
 514         movl $(__KERNEL_CS << 16),%eax
 515         movw %dx,%ax            /* selector = 0x0010 = cs */
 516         movw $0x8E00,%dx        /* interrupt gate - dpl=0, present */
 517 2:
 518         movl %eax,(%edi)
 519         movl %edx,4(%edi)
 520         addl $8,%edi
 521         loop 2b
 522
 523 #ifdef CONFIG_CC_STACKPROTECTOR
 524         /*
 525          * Configure the stack canary. The linker can't handle this by
 526          * relocation.  Manually set base address in stack canary
 527          * segment descriptor.
 528          */
 529         movl $gdt_page,%eax
 530         movl $stack_canary,%ecx
 531         movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
 532         shrl $16, %ecx
 533         movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
 534         movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
 535 #endif
 536
 537         andl $0,setup_once_ref  /* Once is enough, thanks */
 538         ret
 539
 540 ENTRY(early_idt_handler_array)
 541         # 36(%esp) %eflags
 542         # 32(%esp) %cs
 543         # 28(%esp) %eip
 544         # 24(%rsp) error code
 545         i = 0
 546         .rept NUM_EXCEPTION_VECTORS
 547         .ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1
 548         pushl $0                # Dummy error code, to make stack frame uniform
 549         .endif
 550         pushl $i                # 20(%esp) Vector number
 551         jmp early_idt_handler_common
 552         i = i + 1
 553         .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
 554         .endr
 555 ENDPROC(early_idt_handler_array)
 556
 557 early_idt_handler_common:
 558         /*
 559          * The stack is the hardware frame, an error code or zero, and the
 560          * vector number.
 561          */
 562         cld
 563
 564         cmpl $2,(%esp)          # X86_TRAP_NMI
 565         je .Lis_nmi             # Ignore NMI
 566
 567         cmpl $2,%ss:early_recursion_flag
 568         je hlt_loop
 569         incl %ss:early_recursion_flag
 570
 571         push %eax               # 16(%esp)
 572         push %ecx               # 12(%esp)
 573         push %edx               #  8(%esp)
 574         push %ds                #  4(%esp)
 575         push %es                #  0(%esp)
 576         movl $(__KERNEL_DS),%eax
 577         movl %eax,%ds
 578         movl %eax,%es
 579
 580         cmpl $(__KERNEL_CS),32(%esp)
 581         jne 10f
 582
 583         leal 28(%esp),%eax      # Pointer to %eip
 584         call early_fixup_exception
 585         andl %eax,%eax
 586         jnz ex_entry            /* found an exception entry */
 587
 588 10:
 589 #ifdef CONFIG_PRINTK
 590         xorl %eax,%eax
 591         movw %ax,2(%esp)        /* clean up the segment values on some cpus */
 592         movw %ax,6(%esp)
 593         movw %ax,34(%esp)
 594         leal  40(%esp),%eax
 595         pushl %eax              /* %esp before the exception */
 596         pushl %ebx
 597         pushl %ebp
 598         pushl %esi
 599         pushl %edi
 600         movl %cr2,%eax
 601         pushl %eax
 602         pushl (20+6*4)(%esp)    /* trapno */
 603         pushl $fault_msg
 604         call printk
 605 #endif
 606         call dump_stack
 607 hlt_loop:
 608         hlt
 609         jmp hlt_loop
 610
 611 ex_entry:
 612         pop %es
 613         pop %ds
 614         pop %edx
 615         pop %ecx
 616         pop %eax
 617         decl %ss:early_recursion_flag
 618 .Lis_nmi:
 619         addl $8,%esp            /* drop vector number and error code */
 620         iret
 621 ENDPROC(early_idt_handler_common)
 622
 623 /* This is the default interrupt "handler" :-) */
 624         ALIGN
 625 ignore_int:
 626         cld
 627 #ifdef CONFIG_PRINTK
 628         pushl %eax
 629         pushl %ecx
 630         pushl %edx
 631         pushl %es
 632         pushl %ds
 633         movl $(__KERNEL_DS),%eax
 634         movl %eax,%ds
 635         movl %eax,%es
 636         cmpl $2,early_recursion_flag
 637         je hlt_loop
 638         incl early_recursion_flag
 639         pushl 16(%esp)
 640         pushl 24(%esp)
 641         pushl 32(%esp)
 642         pushl 40(%esp)
 643         pushl $int_msg
 644         call printk
 645
 646         call dump_stack
 647
 648         addl $(5*4),%esp
 649         popl %ds
 650         popl %es
 651         popl %edx
 652         popl %ecx
 653         popl %eax
 654 #endif
 655         iret
 656 ENDPROC(ignore_int)
 657 __INITDATA
 658         .align 4
 659 early_recursion_flag:
 660         .long 0
 661
 662 __REFDATA
 663         .align 4
 664 ENTRY(initial_code)
 665         .long i386_start_kernel
 666 ENTRY(setup_once_ref)
 667         .long setup_once
 668
 669 /*
 670  * BSS section
 671  */
 672 __PAGE_ALIGNED_BSS
 673         .align PAGE_SIZE
 674 #ifdef CONFIG_X86_PAE
 675 initial_pg_pmd:
 676         .fill 1024*KPMDS,4,0
 677 #else
 678 ENTRY(initial_page_table)
 679         .fill 1024,4,0
 680 #endif
 681 initial_pg_fixmap:
 682         .fill 1024,4,0
 683 ENTRY(empty_zero_page)
 684         .fill 4096,1,0
 685 ENTRY(swapper_pg_dir)
 686         .fill 1024,4,0
 687
 688 /*
 689  * This starts the data section.
 690  */
 691 #ifdef CONFIG_X86_PAE
 692 __PAGE_ALIGNED_DATA
 693         /* Page-aligned for the benefit of paravirt? */
 694         .align PAGE_SIZE
 695 ENTRY(initial_page_table)
 696         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0     /* low identity map */
 697 # if KPMDS == 3
 698         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0
 699         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 700         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
 701 # elif KPMDS == 2
 702         .long   0,0
 703         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0
 704         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 705 # elif KPMDS == 1
 706         .long   0,0
 707         .long   0,0
 708         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0
 709 # else
 710 #  error "Kernel PMDs should be 1, 2 or 3"
 711 # endif
 712         .align PAGE_SIZE                /* needs to be page-sized too */
 713 #endif
 714
 715 .data
 716 .balign 4
 717 ENTRY(stack_start)
 718         .long init_thread_union+THREAD_SIZE
 719
 720 __INITRODATA
 721 int_msg:
 722         .asciz "Unknown interrupt or fault at: %p %p %p\n"
 723
 724 fault_msg:
 725 /* fault info: */
 726         .ascii "BUG: Int %d: CR2 %p\n"
 727 /* regs pushed in early_idt_handler: */
 728         .ascii "     EDI %p  ESI %p  EBP %p  EBX %p\n"
 729         .ascii "     ESP %p   ES %p   DS %p\n"
 730         .ascii "     EDX %p  ECX %p  EAX %p\n"
 731 /* fault frame: */
 732         .ascii "     vec %p  err %p  EIP %p   CS %p  flg %p\n"
 733         .ascii "Stack: %p %p %p %p %p %p %p %p\n"
 734         .ascii "       %p %p %p %p %p %p %p %p\n"
 735         .asciz "       %p %p %p %p %p %p %p %p\n"
 736
 737 #include "../../x86/xen/xen-head.S"
 738
 739 /*
 740  * The IDT and GDT 'descriptors' are a strange 48-bit object
 741  * only used by the lidt and lgdt instructions. They are not
 742  * like usual segment descriptors - they consist of a 16-bit
 743  * segment size, and 32-bit linear address value:
 744  */
 745
 746         .data
 747 .globl boot_gdt_descr
 748 .globl idt_descr
 749
 750         ALIGN
 751 # early boot GDT descriptor (must use 1:1 address mapping)
 752         .word 0                         # 32 bit align gdt_desc.address
 753 boot_gdt_descr:
 754         .word __BOOT_DS+7
 755         .long boot_gdt - __PAGE_OFFSET
 756
 757         .word 0                         # 32-bit align idt_desc.address
 758 idt_descr:
 759         .word IDT_ENTRIES*8-1           # idt contains 256 entries
 760         .long idt_table
 761
 762 # boot GDT descriptor (later on used by CPU#0):
 763         .word 0                         # 32 bit align gdt_desc.address
 764 ENTRY(early_gdt_descr)
 765         .word GDT_ENTRIES*8-1
 766         .long gdt_page                  /* Overwritten for secondary CPUs */
 767
 768 /*
 769  * The boot_gdt must mirror the equivalent in setup.S and is
 770  * used only for booting.
 771  */
 772         .align L1_CACHE_BYTES
 773 ENTRY(boot_gdt)
 774         .fill GDT_ENTRY_BOOT_CS,8,0
 775         .quad 0x00cf9a000000ffff        /* kernel 4GB code at 0x00000000 */
 776         .quad 0x00cf92000000ffff        /* kernel 4GB data at 0x00000000 */