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/cpufeature.h>
  23 #include <asm/percpu.h>
  24 #include <asm/nops.h>
  25
  26 /* Physical address */
  27 #define pa(X) ((X) - __PAGE_OFFSET)
  28
  29 /*
  30  * References to members of the new_cpu_data structure.
  31  */
  32
  33 #define X86             new_cpu_data+CPUINFO_x86
  34 #define X86_VENDOR      new_cpu_data+CPUINFO_x86_vendor
  35 #define X86_MODEL       new_cpu_data+CPUINFO_x86_model
  36 #define X86_MASK        new_cpu_data+CPUINFO_x86_mask
  37 #define X86_HARD_MATH   new_cpu_data+CPUINFO_hard_math
  38 #define X86_CPUID       new_cpu_data+CPUINFO_cpuid_level
  39 #define X86_CAPABILITY  new_cpu_data+CPUINFO_x86_capability
  40 #define X86_VENDOR_ID   new_cpu_data+CPUINFO_x86_vendor_id
  41
  42 /*
  43  * This is how much memory in addition to the memory covered up to
  44  * and including _end we need mapped initially.
  45  * We need:
  46  *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
  47  *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
  48  *
  49  * Modulo rounding, each megabyte assigned here requires a kilobyte of
  50  * memory, which is currently unreclaimed.
  51  *
  52  * This should be a multiple of a page.
  53  *
  54  * KERNEL_IMAGE_SIZE should be greater than pa(_end)
  55  * and small than max_low_pfn, otherwise will waste some page table entries
  56  */
  57
  58 #if PTRS_PER_PMD > 1
  59 #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
  60 #else
  61 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
  62 #endif
  63
  64 /* Number of possible pages in the lowmem region */
  65 LOWMEM_PAGES = (((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT)
  66
  67 /* Enough space to fit pagetables for the low memory linear map */
  68 MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
  69
  70 /*
  71  * Worst-case size of the kernel mapping we need to make:
  72  * a relocatable kernel can live anywhere in lowmem, so we need to be able
  73  * to map all of lowmem.
  74  */
  75 KERNEL_PAGES = LOWMEM_PAGES
  76
  77 INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
  78 RESERVE_BRK(pagetables, INIT_MAP_SIZE)
  79
  80 /*
  81  * 32-bit kernel entrypoint; only used by the boot CPU.  On entry,
  82  * %esi points to the real-mode code as a 32-bit pointer.
  83  * CS and DS must be 4 GB flat segments, but we don't depend on
  84  * any particular GDT layout, because we load our own as soon as we
  85  * can.
  86  */
  87 __HEAD
  88 ENTRY(startup_32)
  89         movl pa(stack_start),%ecx
  90
  91         /* test KEEP_SEGMENTS flag to see if the bootloader is asking
  92                 us to not reload segments */
  93         testb $(1<<6), BP_loadflags(%esi)
  94         jnz 2f
  95
  96 /*
  97  * Set segments to known values.
  98  */
  99         lgdt pa(boot_gdt_descr)
 100         movl $(__BOOT_DS),%eax
 101         movl %eax,%ds
 102         movl %eax,%es
 103         movl %eax,%fs
 104         movl %eax,%gs
 105         movl %eax,%ss
 106 2:
 107         leal -__PAGE_OFFSET(%ecx),%esp
 108
 109 /*
 110  * Clear BSS first so that there are no surprises...
 111  */
 112         cld
 113         xorl %eax,%eax
 114         movl $pa(__bss_start),%edi
 115         movl $pa(__bss_stop),%ecx
 116         subl %edi,%ecx
 117         shrl $2,%ecx
 118         rep ; stosl
 119 /*
 120  * Copy bootup parameters out of the way.
 121  * Note: %esi still has the pointer to the real-mode data.
 122  * With the kexec as boot loader, parameter segment might be loaded beyond
 123  * kernel image and might not even be addressable by early boot page tables.
 124  * (kexec on panic case). Hence copy out the parameters before initializing
 125  * page tables.
 126  */
 127         movl $pa(boot_params),%edi
 128         movl $(PARAM_SIZE/4),%ecx
 129         cld
 130         rep
 131         movsl
 132         movl pa(boot_params) + NEW_CL_POINTER,%esi
 133         andl %esi,%esi
 134         jz 1f                   # No command line
 135         movl $pa(boot_command_line),%edi
 136         movl $(COMMAND_LINE_SIZE/4),%ecx
 137         rep
 138         movsl
 139 1:
 140
 141 #ifdef CONFIG_OLPC
 142         /* save OFW's pgdir table for later use when calling into OFW */
 143         movl %cr3, %eax
 144         movl %eax, pa(olpc_ofw_pgd)
 145 #endif
 146
 147 #ifdef CONFIG_MICROCODE_EARLY
 148         /* Early load ucode on BSP. */
 149         call load_ucode_bsp
 150 #endif
 151
 152 /*
 153  * Initialize page tables.  This creates a PDE and a set of page
 154  * tables, which are located immediately beyond __brk_base.  The variable
 155  * _brk_end is set up to point to the first "safe" location.
 156  * Mappings are created both at virtual address 0 (identity mapping)
 157  * and PAGE_OFFSET for up to _end.
 158  */
 159 #ifdef CONFIG_X86_PAE
 160
 161         /*
 162          * In PAE mode initial_page_table is statically defined to contain
 163          * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
 164          * entries). The identity mapping is handled by pointing two PGD entries
 165          * to the first kernel PMD.
 166          *
 167          * Note the upper half of each PMD or PTE are always zero at this stage.
 168          */
 169
 170 #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
 171
 172         xorl %ebx,%ebx                          /* %ebx is kept at zero */
 173
 174         movl $pa(__brk_base), %edi
 175         movl $pa(initial_pg_pmd), %edx
 176         movl $PTE_IDENT_ATTR, %eax
 177 10:
 178         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PMD entry */
 179         movl %ecx,(%edx)                        /* Store PMD entry */
 180                                                 /* Upper half already zero */
 181         addl $8,%edx
 182         movl $512,%ecx
 183 11:
 184         stosl
 185         xchgl %eax,%ebx
 186         stosl
 187         xchgl %eax,%ebx
 188         addl $0x1000,%eax
 189         loop 11b
 190
 191         /*
 192          * End condition: we must map up to the end + MAPPING_BEYOND_END.
 193          */
 194         movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
 195         cmpl %ebp,%eax
 196         jb 10b
 197 1:
 198         addl $__PAGE_OFFSET, %edi
 199         movl %edi, pa(_brk_end)
 200         shrl $12, %eax
 201         movl %eax, pa(max_pfn_mapped)
 202
 203         /* Do early initialization of the fixmap area */
 204         movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
 205         movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
 206 #else   /* Not PAE */
 207
 208 page_pde_offset = (__PAGE_OFFSET >> 20);
 209
 210         movl $pa(__brk_base), %edi
 211         movl $pa(initial_page_table), %edx
 212         movl $PTE_IDENT_ATTR, %eax
 213 10:
 214         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PDE entry */
 215         movl %ecx,(%edx)                        /* Store identity PDE entry */
 216         movl %ecx,page_pde_offset(%edx)         /* Store kernel PDE entry */
 217         addl $4,%edx
 218         movl $1024, %ecx
 219 11:
 220         stosl
 221         addl $0x1000,%eax
 222         loop 11b
 223         /*
 224          * End condition: we must map up to the end + MAPPING_BEYOND_END.
 225          */
 226         movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
 227         cmpl %ebp,%eax
 228         jb 10b
 229         addl $__PAGE_OFFSET, %edi
 230         movl %edi, pa(_brk_end)
 231         shrl $12, %eax
 232         movl %eax, pa(max_pfn_mapped)
 233
 234         /* Do early initialization of the fixmap area */
 235         movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
 236         movl %eax,pa(initial_page_table+0xffc)
 237 #endif
 238
 239 #ifdef CONFIG_PARAVIRT
 240         /* This is can only trip for a broken bootloader... */
 241         cmpw $0x207, pa(boot_params + BP_version)
 242         jb default_entry
 243
 244         /* Paravirt-compatible boot parameters.  Look to see what architecture
 245                 we're booting under. */
 246         movl pa(boot_params + BP_hardware_subarch), %eax
 247         cmpl $num_subarch_entries, %eax
 248         jae bad_subarch
 249
 250         movl pa(subarch_entries)(,%eax,4), %eax
 251         subl $__PAGE_OFFSET, %eax
 252         jmp *%eax
 253
 254 bad_subarch:
 255 WEAK(lguest_entry)
 256 WEAK(xen_entry)
 257         /* Unknown implementation; there's really
 258            nothing we can do at this point. */
 259         ud2a
 260
 261         __INITDATA
 262
 263 subarch_entries:
 264         .long default_entry             /* normal x86/PC */
 265         .long lguest_entry              /* lguest hypervisor */
 266         .long xen_entry                 /* Xen hypervisor */
 267         .long default_entry             /* Moorestown MID */
 268 num_subarch_entries = (. - subarch_entries) / 4
 269 .previous
 270 #else
 271         jmp default_entry
 272 #endif /* CONFIG_PARAVIRT */
 273
 274 #ifdef CONFIG_HOTPLUG_CPU
 275 /*
 276  * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
 277  * up already except stack. We just set up stack here. Then call
 278  * start_secondary().
 279  */
 280 ENTRY(start_cpu0)
 281         movl stack_start, %ecx
 282         movl %ecx, %esp
 283         jmp  *(initial_code)
 284 ENDPROC(start_cpu0)
 285 #endif
 286
 287 /*
 288  * Non-boot CPU entry point; entered from trampoline.S
 289  * We can't lgdt here, because lgdt itself uses a data segment, but
 290  * we know the trampoline has already loaded the boot_gdt for us.
 291  *
 292  * If cpu hotplug is not supported then this code can go in init section
 293  * which will be freed later
 294  */
 295 ENTRY(startup_32_smp)
 296         cld
 297         movl $(__BOOT_DS),%eax
 298         movl %eax,%ds
 299         movl %eax,%es
 300         movl %eax,%fs
 301         movl %eax,%gs
 302         movl pa(stack_start),%ecx
 303         movl %eax,%ss
 304         leal -__PAGE_OFFSET(%ecx),%esp
 305
 306 #ifdef CONFIG_MICROCODE_EARLY
 307         /* Early load ucode on AP. */
 308         call load_ucode_ap
 309 #endif
 310
 311
 312 default_entry:
 313 #define CR0_STATE       (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
 314                          X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
 315                          X86_CR0_PG)
 316         movl $(CR0_STATE & ~X86_CR0_PG),%eax
 317         movl %eax,%cr0
 318
 319 /*
 320  * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
 321  * bits like NT set. This would confuse the debugger if this code is traced. So
 322  * initialize them properly now before switching to protected mode. That means
 323  * DF in particular (even though we have cleared it earlier after copying the
 324  * command line) because GCC expects it.
 325  */
 326         pushl $0
 327         popfl
 328
 329 /*
 330  * New page tables may be in 4Mbyte page mode and may be using the global pages.
 331  *
 332  * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
 333  * if and only if CPUID exists and has flags other than the FPU flag set.
 334  */
 335         movl $-1,pa(X86_CPUID)          # preset CPUID level
 336         movl $X86_EFLAGS_ID,%ecx
 337         pushl %ecx
 338         popfl                           # set EFLAGS=ID
 339         pushfl
 340         popl %eax                       # get EFLAGS
 341         testl $X86_EFLAGS_ID,%eax       # did EFLAGS.ID remained set?
 342         jz enable_paging                # hw disallowed setting of ID bit
 343                                         # which means no CPUID and no CR4
 344
 345         xorl %eax,%eax
 346         cpuid
 347         movl %eax,pa(X86_CPUID)         # save largest std CPUID function
 348
 349         movl $1,%eax
 350         cpuid
 351         andl $~1,%edx                   # Ignore CPUID.FPU
 352         jz enable_paging                # No flags or only CPUID.FPU = no CR4
 353
 354         movl pa(mmu_cr4_features),%eax
 355         movl %eax,%cr4
 356
 357         testb $X86_CR4_PAE, %al         # check if PAE is enabled
 358         jz enable_paging
 359
 360         /* Check if extended functions are implemented */
 361         movl $0x80000000, %eax
 362         cpuid
 363         /* Value must be in the range 0x80000001 to 0x8000ffff */
 364         subl $0x80000001, %eax
 365         cmpl $(0x8000ffff-0x80000001), %eax
 366         ja enable_paging
 367
 368         /* Clear bogus XD_DISABLE bits */
 369         call verify_cpu
 370
 371         mov $0x80000001, %eax
 372         cpuid
 373         /* Execute Disable bit supported? */
 374         btl $(X86_FEATURE_NX & 31), %edx
 375         jnc enable_paging
 376
 377         /* Setup EFER (Extended Feature Enable Register) */
 378         movl $MSR_EFER, %ecx
 379         rdmsr
 380
 381         btsl $_EFER_NX, %eax
 382         /* Make changes effective */
 383         wrmsr
 384
 385 enable_paging:
 386
 387 /*
 388  * Enable paging
 389  */
 390         movl $pa(initial_page_table), %eax
 391         movl %eax,%cr3          /* set the page table pointer.. */
 392         movl $CR0_STATE,%eax
 393         movl %eax,%cr0          /* ..and set paging (PG) bit */
 394         ljmp $__BOOT_CS,$1f     /* Clear prefetch and normalize %eip */
 395 1:
 396         /* Shift the stack pointer to a virtual address */
 397         addl $__PAGE_OFFSET, %esp
 398
 399 /*
 400  * start system 32-bit setup. We need to re-do some of the things done
 401  * in 16-bit mode for the "real" operations.
 402  */
 403         movl setup_once_ref,%eax
 404         andl %eax,%eax
 405         jz 1f                           # Did we do this already?
 406         call *%eax
 407 1:
 408
 409 /*
 410  * Check if it is 486
 411  */
 412         movb $4,X86                     # at least 486
 413         cmpl $-1,X86_CPUID
 414         je is486
 415
 416         /* get vendor info */
 417         xorl %eax,%eax                  # call CPUID with 0 -> return vendor ID
 418         cpuid
 419         movl %eax,X86_CPUID             # save CPUID level
 420         movl %ebx,X86_VENDOR_ID         # lo 4 chars
 421         movl %edx,X86_VENDOR_ID+4       # next 4 chars
 422         movl %ecx,X86_VENDOR_ID+8       # last 4 chars
 423
 424         orl %eax,%eax                   # do we have processor info as well?
 425         je is486
 426
 427         movl $1,%eax            # Use the CPUID instruction to get CPU type
 428         cpuid
 429         movb %al,%cl            # save reg for future use
 430         andb $0x0f,%ah          # mask processor family
 431         movb %ah,X86
 432         andb $0xf0,%al          # mask model
 433         shrb $4,%al
 434         movb %al,X86_MODEL
 435         andb $0x0f,%cl          # mask mask revision
 436         movb %cl,X86_MASK
 437         movl %edx,X86_CAPABILITY
 438
 439 is486:
 440         movl $0x50022,%ecx      # set AM, WP, NE and MP
 441         movl %cr0,%eax
 442         andl $0x80000011,%eax   # Save PG,PE,ET
 443         orl %ecx,%eax
 444         movl %eax,%cr0
 445
 446         lgdt early_gdt_descr
 447         lidt idt_descr
 448         ljmp $(__KERNEL_CS),$1f
 449 1:      movl $(__KERNEL_DS),%eax        # reload all the segment registers
 450         movl %eax,%ss                   # after changing gdt.
 451
 452         movl $(__USER_DS),%eax          # DS/ES contains default USER segment
 453         movl %eax,%ds
 454         movl %eax,%es
 455
 456         movl $(__KERNEL_PERCPU), %eax
 457         movl %eax,%fs                   # set this cpu's percpu
 458
 459         movl $(__KERNEL_STACK_CANARY),%eax
 460         movl %eax,%gs
 461
 462         xorl %eax,%eax                  # Clear LDT
 463         lldt %ax
 464
 465         pushl $0                # fake return address for unwinder
 466         jmp *(initial_code)
 467
 468 #include "verify_cpu.S"
 469
 470 /*
 471  *  setup_once
 472  *
 473  *  The setup work we only want to run on the BSP.
 474  *
 475  *  Warning: %esi is live across this function.
 476  */
 477 __INIT
 478 setup_once:
 479         /*
 480          * Set up a idt with 256 entries pointing to ignore_int,
 481          * interrupt gates. It doesn't actually load idt - that needs
 482          * to be done on each CPU. Interrupts are enabled elsewhere,
 483          * when we can be relatively sure everything is ok.
 484          */
 485
 486         movl $idt_table,%edi
 487         movl $early_idt_handlers,%eax
 488         movl $NUM_EXCEPTION_VECTORS,%ecx
 489 1:
 490         movl %eax,(%edi)
 491         movl %eax,4(%edi)
 492         /* interrupt gate, dpl=0, present */
 493         movl $(0x8E000000 + __KERNEL_CS),2(%edi)
 494         addl $9,%eax
 495         addl $8,%edi
 496         loop 1b
 497
 498         movl $256 - NUM_EXCEPTION_VECTORS,%ecx
 499         movl $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 2:
 504         movl %eax,(%edi)
 505         movl %edx,4(%edi)
 506         addl $8,%edi
 507         loop 2b
 508
 509 #ifdef CONFIG_CC_STACKPROTECTOR
 510         /*
 511          * Configure the stack canary. The linker can't handle this by
 512          * relocation.  Manually set base address in stack canary
 513          * segment descriptor.
 514          */
 515         movl $gdt_page,%eax
 516         movl $stack_canary,%ecx
 517         movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
 518         shrl $16, %ecx
 519         movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
 520         movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
 521 #endif
 522
 523         andl $0,setup_once_ref  /* Once is enough, thanks */
 524         ret
 525
 526 ENTRY(early_idt_handlers)
 527         # 36(%esp) %eflags
 528         # 32(%esp) %cs
 529         # 28(%esp) %eip
 530         # 24(%rsp) error code
 531         i = 0
 532         .rept NUM_EXCEPTION_VECTORS
 533         .if (EXCEPTION_ERRCODE_MASK >> i) & 1
 534         ASM_NOP2
 535         .else
 536         pushl $0                # Dummy error code, to make stack frame uniform
 537         .endif
 538         pushl $i                # 20(%esp) Vector number
 539         jmp early_idt_handler
 540         i = i + 1
 541         .endr
 542 ENDPROC(early_idt_handlers)
 543
 544         /* This is global to keep gas from relaxing the jumps */
 545 ENTRY(early_idt_handler)
 546         cld
 547
 548         cmpl $2,(%esp)          # X86_TRAP_NMI
 549         je is_nmi               # Ignore NMI
 550
 551         cmpl $2,%ss:early_recursion_flag
 552         je hlt_loop
 553         incl %ss:early_recursion_flag
 554
 555         push %eax               # 16(%esp)
 556         push %ecx               # 12(%esp)
 557         push %edx               #  8(%esp)
 558         push %ds                #  4(%esp)
 559         push %es                #  0(%esp)
 560         movl $(__KERNEL_DS),%eax
 561         movl %eax,%ds
 562         movl %eax,%es
 563
 564         cmpl $(__KERNEL_CS),32(%esp)
 565         jne 10f
 566
 567         leal 28(%esp),%eax      # Pointer to %eip
 568         call early_fixup_exception
 569         andl %eax,%eax
 570         jnz ex_entry            /* found an exception entry */
 571
 572 10:
 573 #ifdef CONFIG_PRINTK
 574         xorl %eax,%eax
 575         movw %ax,2(%esp)        /* clean up the segment values on some cpus */
 576         movw %ax,6(%esp)
 577         movw %ax,34(%esp)
 578         leal  40(%esp),%eax
 579         pushl %eax              /* %esp before the exception */
 580         pushl %ebx
 581         pushl %ebp
 582         pushl %esi
 583         pushl %edi
 584         movl %cr2,%eax
 585         pushl %eax
 586         pushl (20+6*4)(%esp)    /* trapno */
 587         pushl $fault_msg
 588         call printk
 589 #endif
 590         call dump_stack
 591 hlt_loop:
 592         hlt
 593         jmp hlt_loop
 594
 595 ex_entry:
 596         pop %es
 597         pop %ds
 598         pop %edx
 599         pop %ecx
 600         pop %eax
 601         decl %ss:early_recursion_flag
 602 is_nmi:
 603         addl $8,%esp            /* drop vector number and error code */
 604         iret
 605 ENDPROC(early_idt_handler)
 606
 607 /* This is the default interrupt "handler" :-) */
 608         ALIGN
 609 ignore_int:
 610         cld
 611 #ifdef CONFIG_PRINTK
 612         pushl %eax
 613         pushl %ecx
 614         pushl %edx
 615         pushl %es
 616         pushl %ds
 617         movl $(__KERNEL_DS),%eax
 618         movl %eax,%ds
 619         movl %eax,%es
 620         cmpl $2,early_recursion_flag
 621         je hlt_loop
 622         incl early_recursion_flag
 623         pushl 16(%esp)
 624         pushl 24(%esp)
 625         pushl 32(%esp)
 626         pushl 40(%esp)
 627         pushl $int_msg
 628         call printk
 629
 630         call dump_stack
 631
 632         addl $(5*4),%esp
 633         popl %ds
 634         popl %es
 635         popl %edx
 636         popl %ecx
 637         popl %eax
 638 #endif
 639         iret
 640 ENDPROC(ignore_int)
 641 __INITDATA
 642         .align 4
 643 early_recursion_flag:
 644         .long 0
 645
 646 __REFDATA
 647         .align 4
 648 ENTRY(initial_code)
 649         .long i386_start_kernel
 650 ENTRY(setup_once_ref)
 651         .long setup_once
 652
 653 /*
 654  * BSS section
 655  */
 656 __PAGE_ALIGNED_BSS
 657         .align PAGE_SIZE
 658 #ifdef CONFIG_X86_PAE
 659 initial_pg_pmd:
 660         .fill 1024*KPMDS,4,0
 661 #else
 662 ENTRY(initial_page_table)
 663         .fill 1024,4,0
 664 #endif
 665 initial_pg_fixmap:
 666         .fill 1024,4,0
 667 ENTRY(empty_zero_page)
 668         .fill 4096,1,0
 669 ENTRY(swapper_pg_dir)
 670         .fill 1024,4,0
 671
 672 /*
 673  * This starts the data section.
 674  */
 675 #ifdef CONFIG_X86_PAE
 676 __PAGE_ALIGNED_DATA
 677         /* Page-aligned for the benefit of paravirt? */
 678         .align PAGE_SIZE
 679 ENTRY(initial_page_table)
 680         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0     /* low identity map */
 681 # if KPMDS == 3
 682         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0
 683         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 684         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
 685 # elif KPMDS == 2
 686         .long   0,0
 687         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0
 688         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
 689 # elif KPMDS == 1
 690         .long   0,0
 691         .long   0,0
 692         .long   pa(initial_pg_pmd+PGD_IDENT_ATTR),0
 693 # else
 694 #  error "Kernel PMDs should be 1, 2 or 3"
 695 # endif
 696         .align PAGE_SIZE                /* needs to be page-sized too */
 697 #endif
 698
 699 .data
 700 .balign 4
 701 ENTRY(stack_start)
 702         .long init_thread_union+THREAD_SIZE
 703
 704 __INITRODATA
 705 int_msg:
 706         .asciz "Unknown interrupt or fault at: %p %p %p\n"
 707
 708 fault_msg:
 709 /* fault info: */
 710         .ascii "BUG: Int %d: CR2 %p\n"
 711 /* regs pushed in early_idt_handler: */
 712         .ascii "     EDI %p  ESI %p  EBP %p  EBX %p\n"
 713         .ascii "     ESP %p   ES %p   DS %p\n"
 714         .ascii "     EDX %p  ECX %p  EAX %p\n"
 715 /* fault frame: */
 716         .ascii "     vec %p  err %p  EIP %p   CS %p  flg %p\n"
 717         .ascii "Stack: %p %p %p %p %p %p %p %p\n"
 718         .ascii "       %p %p %p %p %p %p %p %p\n"
 719         .asciz "       %p %p %p %p %p %p %p %p\n"
 720
 721 #include "../../x86/xen/xen-head.S"
 722
 723 /*
 724  * The IDT and GDT 'descriptors' are a strange 48-bit object
 725  * only used by the lidt and lgdt instructions. They are not
 726  * like usual segment descriptors - they consist of a 16-bit
 727  * segment size, and 32-bit linear address value:
 728  */
 729
 730         .data
 731 .globl boot_gdt_descr
 732 .globl idt_descr
 733
 734         ALIGN
 735 # early boot GDT descriptor (must use 1:1 address mapping)
 736         .word 0                         # 32 bit align gdt_desc.address
 737 boot_gdt_descr:
 738         .word __BOOT_DS+7
 739         .long boot_gdt - __PAGE_OFFSET
 740
 741         .word 0                         # 32-bit align idt_desc.address
 742 idt_descr:
 743         .word IDT_ENTRIES*8-1           # idt contains 256 entries
 744         .long idt_table
 745
 746 # boot GDT descriptor (later on used by CPU#0):
 747         .word 0                         # 32 bit align gdt_desc.address
 748 ENTRY(early_gdt_descr)
 749         .word GDT_ENTRIES*8-1
 750         .long gdt_page                  /* Overwritten for secondary CPUs */
 751
 752 /*
 753  * The boot_gdt must mirror the equivalent in setup.S and is
 754  * used only for booting.
 755  */
 756         .align L1_CACHE_BYTES
 757 ENTRY(boot_gdt)
 758         .fill GDT_ENTRY_BOOT_CS,8,0
 759         .quad 0x00cf9a000000ffff        /* kernel 4GB code at 0x00000000 */
 760         .quad 0x00cf92000000ffff        /* kernel 4GB data at 0x00000000 */