arch/x86/kernel/head_64.S

   1 /*
   2  *  linux/arch/x86_64/kernel/head.S -- start in 32bit and switch to 64bit
   3  *
   4  *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
   5  *  Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
   6  *  Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
   7  *  Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
   8  *  Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
   9  */
  10
  11
  12 #include <linux/linkage.h>
  13 #include <linux/threads.h>
  14 #include <linux/init.h>
  15 #include <asm/desc.h>
  16 #include <asm/segment.h>
  17 #include <asm/pgtable.h>
  18 #include <asm/page.h>
  19 #include <asm/msr.h>
  20 #include <asm/cache.h>
  21
  22 #ifdef CONFIG_PARAVIRT
  23 #include <asm/asm-offsets.h>
  24 #include <asm/paravirt.h>
  25 #else
  26 #define GET_CR2_INTO_RCX movq %cr2, %rcx
  27 #endif
  28
  29 /* we are not able to switch in one step to the final KERNEL ADRESS SPACE
  30  * because we need identity-mapped pages.
  31  *
  32  */
  33
  34         .text
  35         .section .text.head
  36         .code64
  37         .globl startup_64
  38 startup_64:
  39
  40         /*
  41          * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1,
  42          * and someone has loaded an identity mapped page table
  43          * for us.  These identity mapped page tables map all of the
  44          * kernel pages and possibly all of memory.
  45          *
  46          * %esi holds a physical pointer to real_mode_data.
  47          *
  48          * We come here either directly from a 64bit bootloader, or from
  49          * arch/x86_64/boot/compressed/head.S.
  50          *
  51          * We only come here initially at boot nothing else comes here.
  52          *
  53          * Since we may be loaded at an address different from what we were
  54          * compiled to run at we first fixup the physical addresses in our page
  55          * tables and then reload them.
  56          */
  57
  58         /* Compute the delta between the address I am compiled to run at and the
  59          * address I am actually running at.
  60          */
  61         leaq    _text(%rip), %rbp
  62         subq    $_text - __START_KERNEL_map, %rbp
  63
  64         /* Is the address not 2M aligned? */
  65         movq    %rbp, %rax
  66         andl    $~PMD_PAGE_MASK, %eax
  67         testl   %eax, %eax
  68         jnz     bad_address
  69
  70         /* Is the address too large? */
  71         leaq    _text(%rip), %rdx
  72         movq    $PGDIR_SIZE, %rax
  73         cmpq    %rax, %rdx
  74         jae     bad_address
  75
  76         /* Fixup the physical addresses in the page table
  77          */
  78         addq    %rbp, init_level4_pgt + 0(%rip)
  79         addq    %rbp, init_level4_pgt + (258*8)(%rip)
  80         addq    %rbp, init_level4_pgt + (511*8)(%rip)
  81
  82         addq    %rbp, level3_ident_pgt + 0(%rip)
  83
  84         addq    %rbp, level3_kernel_pgt + (510*8)(%rip)
  85         addq    %rbp, level3_kernel_pgt + (511*8)(%rip)
  86
  87         addq    %rbp, level2_fixmap_pgt + (506*8)(%rip)
  88
  89         /* Add an Identity mapping if I am above 1G */
  90         leaq    _text(%rip), %rdi
  91         andq    $PMD_PAGE_MASK, %rdi
  92
  93         movq    %rdi, %rax
  94         shrq    $PUD_SHIFT, %rax
  95         andq    $(PTRS_PER_PUD - 1), %rax
  96         jz      ident_complete
  97
  98         leaq    (level2_spare_pgt - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx
  99         leaq    level3_ident_pgt(%rip), %rbx
 100         movq    %rdx, 0(%rbx, %rax, 8)
 101
 102         movq    %rdi, %rax
 103         shrq    $PMD_SHIFT, %rax
 104         andq    $(PTRS_PER_PMD - 1), %rax
 105         leaq    __PAGE_KERNEL_LARGE_EXEC(%rdi), %rdx
 106         leaq    level2_spare_pgt(%rip), %rbx
 107         movq    %rdx, 0(%rbx, %rax, 8)
 108 ident_complete:
 109
 110         /*
 111          * Fixup the kernel text+data virtual addresses. Note that
 112          * we might write invalid pmds, when the kernel is relocated
 113          * cleanup_highmap() fixes this up along with the mappings
 114          * beyond _end.
 115          */
 116
 117         leaq    level2_kernel_pgt(%rip), %rdi
 118         leaq    4096(%rdi), %r8
 119         /* See if it is a valid page table entry */
 120 1:      testq   $1, 0(%rdi)
 121         jz      2f
 122         addq    %rbp, 0(%rdi)
 123         /* Go to the next page */
 124 2:      addq    $8, %rdi
 125         cmp     %r8, %rdi
 126         jne     1b
 127
 128         /* Fixup phys_base */
 129         addq    %rbp, phys_base(%rip)
 130
 131 #ifdef CONFIG_SMP
 132         addq    %rbp, trampoline_level4_pgt + 0(%rip)
 133         addq    %rbp, trampoline_level4_pgt + (511*8)(%rip)
 134 #endif
 135
 136         /* Due to ENTRY(), sometimes the empty space gets filled with
 137          * zeros. Better take a jmp than relying on empty space being
 138          * filled with 0x90 (nop)
 139          */
 140         jmp secondary_startup_64
 141 ENTRY(secondary_startup_64)
 142         /*
 143          * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1,
 144          * and someone has loaded a mapped page table.
 145          *
 146          * %esi holds a physical pointer to real_mode_data.
 147          *
 148          * We come here either from startup_64 (using physical addresses)
 149          * or from trampoline.S (using virtual addresses).
 150          *
 151          * Using virtual addresses from trampoline.S removes the need
 152          * to have any identity mapped pages in the kernel page table
 153          * after the boot processor executes this code.
 154          */
 155
 156         /* Enable PAE mode and PGE */
 157         xorq    %rax, %rax
 158         btsq    $5, %rax
 159         btsq    $7, %rax
 160         movq    %rax, %cr4
 161
 162         /* Setup early boot stage 4 level pagetables. */
 163         movq    $(init_level4_pgt - __START_KERNEL_map), %rax
 164         addq    phys_base(%rip), %rax
 165         movq    %rax, %cr3
 166
 167         /* Ensure I am executing from virtual addresses */
 168         movq    $1f, %rax
 169         jmp     *%rax
 170 1:
 171
 172         /* Check if nx is implemented */
 173         movl    $0x80000001, %eax
 174         cpuid
 175         movl    %edx,%edi
 176
 177         /* Setup EFER (Extended Feature Enable Register) */
 178         movl    $MSR_EFER, %ecx
 179         rdmsr
 180         btsl    $_EFER_SCE, %eax        /* Enable System Call */
 181         btl     $20,%edi                /* No Execute supported? */
 182         jnc     1f
 183         btsl    $_EFER_NX, %eax
 184 1:      wrmsr                           /* Make changes effective */
 185
 186         /* Setup cr0 */
 187 #define CR0_PM                          1               /* protected mode */
 188 #define CR0_MP                          (1<<1)
 189 #define CR0_ET                          (1<<4)
 190 #define CR0_NE                          (1<<5)
 191 #define CR0_WP                          (1<<16)
 192 #define CR0_AM                          (1<<18)
 193 #define CR0_PAGING                      (1<<31)
 194         movl $CR0_PM|CR0_MP|CR0_ET|CR0_NE|CR0_WP|CR0_AM|CR0_PAGING,%eax
 195         /* Make changes effective */
 196         movq    %rax, %cr0
 197
 198         /* Setup a boot time stack */
 199         movq init_rsp(%rip),%rsp
 200
 201         /* zero EFLAGS after setting rsp */
 202         pushq $0
 203         popfq
 204
 205         /*
 206          * We must switch to a new descriptor in kernel space for the GDT
 207          * because soon the kernel won't have access anymore to the userspace
 208          * addresses where we're currently running on. We have to do that here
 209          * because in 32bit we couldn't load a 64bit linear address.
 210          */
 211         lgdt    cpu_gdt_descr(%rip)
 212
 213         /* set up data segments. actually 0 would do too */
 214         movl $__KERNEL_DS,%eax
 215         movl %eax,%ds
 216         movl %eax,%ss
 217         movl %eax,%es
 218
 219         /*
 220          * We don't really need to load %fs or %gs, but load them anyway
 221          * to kill any stale realmode selectors.  This allows execution
 222          * under VT hardware.
 223          */
 224         movl %eax,%fs
 225         movl %eax,%gs
 226
 227         /*
 228          * Setup up a dummy PDA. this is just for some early bootup code
 229          * that does in_interrupt()
 230          */
 231         movl    $MSR_GS_BASE,%ecx
 232         movq    $empty_zero_page,%rax
 233         movq    %rax,%rdx
 234         shrq    $32,%rdx
 235         wrmsr
 236
 237         /* esi is pointer to real mode structure with interesting info.
 238            pass it to C */
 239         movl    %esi, %edi
 240
 241         /* Finally jump to run C code and to be on real kernel address
 242          * Since we are running on identity-mapped space we have to jump
 243          * to the full 64bit address, this is only possible as indirect
 244          * jump.  In addition we need to ensure %cs is set so we make this
 245          * a far return.
 246          */
 247         movq    initial_code(%rip),%rax
 248         pushq   $0              # fake return address to stop unwinder
 249         pushq   $__KERNEL_CS    # set correct cs
 250         pushq   %rax            # target address in negative space
 251         lretq
 252
 253         /* SMP bootup changes these two */
 254         __REFDATA
 255         .align  8
 256         ENTRY(initial_code)
 257         .quad   x86_64_start_kernel
 258         __FINITDATA
 259
 260         ENTRY(init_rsp)
 261         .quad  init_thread_union+THREAD_SIZE-8
 262
 263 bad_address:
 264         jmp bad_address
 265
 266         .section ".init.text","ax"
 267 #ifdef CONFIG_EARLY_PRINTK
 268         .globl early_idt_handlers
 269 early_idt_handlers:
 270         i = 0
 271         .rept NUM_EXCEPTION_VECTORS
 272         movl $i, %esi
 273         jmp early_idt_handler
 274         i = i + 1
 275         .endr
 276 #endif
 277
 278 ENTRY(early_idt_handler)
 279 #ifdef CONFIG_EARLY_PRINTK
 280         cmpl $2,early_recursion_flag(%rip)
 281         jz  1f
 282         incl early_recursion_flag(%rip)
 283         GET_CR2_INTO_RCX
 284         movq %rcx,%r9
 285         xorl %r8d,%r8d          # zero for error code
 286         movl %esi,%ecx          # get vector number
 287         # Test %ecx against mask of vectors that push error code.
 288         cmpl $31,%ecx
 289         ja 0f
 290         movl $1,%eax
 291         salq %cl,%rax
 292         testl $0x27d00,%eax
 293         je 0f
 294         popq %r8                # get error code
 295 0:      movq 0(%rsp),%rcx       # get ip
 296         movq 8(%rsp),%rdx       # get cs
 297         xorl %eax,%eax
 298         leaq early_idt_msg(%rip),%rdi
 299         call early_printk
 300         cmpl $2,early_recursion_flag(%rip)
 301         jz  1f
 302         call dump_stack
 303 #ifdef CONFIG_KALLSYMS
 304         leaq early_idt_ripmsg(%rip),%rdi
 305         movq 8(%rsp),%rsi       # get rip again
 306         call __print_symbol
 307 #endif
 308 #endif /* EARLY_PRINTK */
 309 1:      hlt
 310         jmp 1b
 311
 312 #ifdef CONFIG_EARLY_PRINTK
 313 early_recursion_flag:
 314         .long 0
 315
 316 early_idt_msg:
 317         .asciz "PANIC: early exception %02lx rip %lx:%lx error %lx cr2 %lx\n"
 318 early_idt_ripmsg:
 319         .asciz "RIP %s\n"
 320 #endif /* CONFIG_EARLY_PRINTK */
 321         .previous
 322
 323 .balign PAGE_SIZE
 324
 325 #define NEXT_PAGE(name) \
 326         .balign PAGE_SIZE; \
 327 ENTRY(name)
 328
 329 /* Automate the creation of 1 to 1 mapping pmd entries */
 330 #define PMDS(START, PERM, COUNT)                \
 331         i = 0 ;                                 \
 332         .rept (COUNT) ;                         \
 333         .quad   (START) + (i << 21) + (PERM) ;  \
 334         i = i + 1 ;                             \
 335         .endr
 336
 337         /*
 338          * This default setting generates an ident mapping at address 0x100000
 339          * and a mapping for the kernel that precisely maps virtual address
 340          * 0xffffffff80000000 to physical address 0x000000. (always using
 341          * 2Mbyte large pages provided by PAE mode)
 342          */
 343 NEXT_PAGE(init_level4_pgt)
 344         .quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
 345         .fill   257,8,0
 346         .quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
 347         .fill   252,8,0
 348         /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
 349         .quad   level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
 350
 351 NEXT_PAGE(level3_ident_pgt)
 352         .quad   level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
 353         .fill   511,8,0
 354
 355 NEXT_PAGE(level3_kernel_pgt)
 356         .fill   510,8,0
 357         /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
 358         .quad   level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
 359         .quad   level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
 360
 361 NEXT_PAGE(level2_fixmap_pgt)
 362         .fill   506,8,0
 363         .quad   level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
 364         /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
 365         .fill   5,8,0
 366
 367 NEXT_PAGE(level1_fixmap_pgt)
 368         .fill   512,8,0
 369
 370 NEXT_PAGE(level2_ident_pgt)
 371         /* Since I easily can, map the first 1G.
 372          * Don't set NX because code runs from these pages.
 373          */
 374         PMDS(0, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD)
 375
 376 NEXT_PAGE(level2_kernel_pgt)
 377         /*
 378          * 512 MB kernel mapping. We spend a full page on this pagetable
 379          * anyway.
 380          *
 381          * The kernel code+data+bss must not be bigger than that.
 382          *
 383          * (NOTE: at +512MB starts the module area, see MODULES_VADDR.
 384          *  If you want to increase this then increase MODULES_VADDR
 385          *  too.)
 386          */
 387         PMDS(0, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL,
 388                 KERNEL_IMAGE_SIZE/PMD_SIZE)
 389
 390 NEXT_PAGE(level2_spare_pgt)
 391         .fill   512, 8, 0
 392
 393 #undef PMDS
 394 #undef NEXT_PAGE
 395
 396         .data
 397         .align 16
 398         .globl cpu_gdt_descr
 399 cpu_gdt_descr:
 400         .word   gdt_end-cpu_gdt_table-1
 401 gdt:
 402         .quad   cpu_gdt_table
 403 #ifdef CONFIG_SMP
 404         .rept   NR_CPUS-1
 405         .word   0
 406         .quad   0
 407         .endr
 408 #endif
 409
 410 ENTRY(phys_base)
 411         /* This must match the first entry in level2_kernel_pgt */
 412         .quad   0x0000000000000000
 413
 414 /* We need valid kernel segments for data and code in long mode too
 415  * IRET will check the segment types  kkeil 2000/10/28
 416  * Also sysret mandates a special GDT layout
 417  */
 418
 419         .section .data.page_aligned, "aw"
 420         .align PAGE_SIZE
 421
 422 /* The TLS descriptors are currently at a different place compared to i386.
 423    Hopefully nobody expects them at a fixed place (Wine?) */
 424
 425 ENTRY(cpu_gdt_table)
 426         .quad   0x0000000000000000      /* NULL descriptor */
 427         .quad   0x00cf9b000000ffff      /* __KERNEL32_CS */
 428         .quad   0x00af9b000000ffff      /* __KERNEL_CS */
 429         .quad   0x00cf93000000ffff      /* __KERNEL_DS */
 430         .quad   0x00cffb000000ffff      /* __USER32_CS */
 431         .quad   0x00cff3000000ffff      /* __USER_DS, __USER32_DS  */
 432         .quad   0x00affb000000ffff      /* __USER_CS */
 433         .quad   0x0                     /* unused */
 434         .quad   0,0                     /* TSS */
 435         .quad   0,0                     /* LDT */
 436         .quad   0,0,0                   /* three TLS descriptors */
 437         .quad   0x0000f40000000000      /* node/CPU stored in limit */
 438 gdt_end:
 439         /* asm/segment.h:GDT_ENTRIES must match this */
 440         /* This should be a multiple of the cache line size */
 441         /* GDTs of other CPUs are now dynamically allocated */
 442
 443         /* zero the remaining page */
 444         .fill PAGE_SIZE / 8 - GDT_ENTRIES,8,0
 445
 446         .section .bss, "aw", @nobits
 447         .align L1_CACHE_BYTES
 448 ENTRY(idt_table)
 449         .skip 256 * 16
 450
 451         .section .bss.page_aligned, "aw", @nobits
 452         .align PAGE_SIZE
 453 ENTRY(empty_zero_page)
 454         .skip PAGE_SIZE