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