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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 | /* * linux/arch/x86_64/kernel/head.S -- start in 32bit and switch to 64bit * * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE * Copyright (C) 2000 Pavel Machek <pavel@suse.cz> * Copyright (C) 2000 Karsten Keil <kkeil@suse.de> * Copyright (C) 2001,2002 Andi Kleen <ak@suse.de> * Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com> */ #include <linux/linkage.h> #include <linux/threads.h> #include <linux/init.h> #include <asm/desc.h> #include <asm/segment.h> #include <asm/pgtable.h> #include <asm/page.h> #include <asm/msr.h> #include <asm/cache.h> #include <asm/processor-flags.h> #ifdef CONFIG_PARAVIRT #include <asm/asm-offsets.h> #include <asm/paravirt.h> #else #define GET_CR2_INTO_RCX movq %cr2, %rcx #endif /* we are not able to switch in one step to the final KERNEL ADRESS SPACE * because we need identity-mapped pages. * */ #define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1)) L4_PAGE_OFFSET = pgd_index(__PAGE_OFFSET) L3_PAGE_OFFSET = pud_index(__PAGE_OFFSET) L4_START_KERNEL = pgd_index(__START_KERNEL_map) L3_START_KERNEL = pud_index(__START_KERNEL_map) .text .section .text.head .code64 .globl startup_64 startup_64: /* * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1, * and someone has loaded an identity mapped page table * for us. These identity mapped page tables map all of the * kernel pages and possibly all of memory. * * %esi holds a physical pointer to real_mode_data. * * We come here either directly from a 64bit bootloader, or from * arch/x86_64/boot/compressed/head.S. * * We only come here initially at boot nothing else comes here. * * Since we may be loaded at an address different from what we were * compiled to run at we first fixup the physical addresses in our page * tables and then reload them. */ /* Compute the delta between the address I am compiled to run at and the * address I am actually running at. */ leaq _text(%rip), %rbp subq $_text - __START_KERNEL_map, %rbp /* Is the address not 2M aligned? */ movq %rbp, %rax andl $~PMD_PAGE_MASK, %eax testl %eax, %eax jnz bad_address /* Is the address too large? */ leaq _text(%rip), %rdx movq $PGDIR_SIZE, %rax cmpq %rax, %rdx jae bad_address /* Fixup the physical addresses in the page table */ addq %rbp, init_level4_pgt + 0(%rip) addq %rbp, init_level4_pgt + (L4_PAGE_OFFSET*8)(%rip) addq %rbp, init_level4_pgt + (L4_START_KERNEL*8)(%rip) addq %rbp, level3_ident_pgt + 0(%rip) addq %rbp, level3_kernel_pgt + (510*8)(%rip) addq %rbp, level3_kernel_pgt + (511*8)(%rip) addq %rbp, level2_fixmap_pgt + (506*8)(%rip) /* Add an Identity mapping if I am above 1G */ leaq _text(%rip), %rdi andq $PMD_PAGE_MASK, %rdi movq %rdi, %rax shrq $PUD_SHIFT, %rax andq $(PTRS_PER_PUD - 1), %rax jz ident_complete leaq (level2_spare_pgt - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx leaq level3_ident_pgt(%rip), %rbx movq %rdx, 0(%rbx, %rax, 8) movq %rdi, %rax shrq $PMD_SHIFT, %rax andq $(PTRS_PER_PMD - 1), %rax leaq __PAGE_KERNEL_LARGE_EXEC(%rdi), %rdx leaq level2_spare_pgt(%rip), %rbx movq %rdx, 0(%rbx, %rax, 8) ident_complete: /* * Fixup the kernel text+data virtual addresses. Note that * we might write invalid pmds, when the kernel is relocated * cleanup_highmap() fixes this up along with the mappings * beyond _end. */ leaq level2_kernel_pgt(%rip), %rdi leaq 4096(%rdi), %r8 /* See if it is a valid page table entry */ 1: testq $1, 0(%rdi) jz 2f addq %rbp, 0(%rdi) /* Go to the next page */ 2: addq $8, %rdi cmp %r8, %rdi jne 1b /* Fixup phys_base */ addq %rbp, phys_base(%rip) #ifdef CONFIG_X86_TRAMPOLINE addq %rbp, trampoline_level4_pgt + 0(%rip) addq %rbp, trampoline_level4_pgt + (511*8)(%rip) #endif /* Due to ENTRY(), sometimes the empty space gets filled with * zeros. Better take a jmp than relying on empty space being * filled with 0x90 (nop) */ jmp secondary_startup_64 ENTRY(secondary_startup_64) /* * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1, * and someone has loaded a mapped page table. * * %esi holds a physical pointer to real_mode_data. * * We come here either from startup_64 (using physical addresses) * or from trampoline.S (using virtual addresses). * * Using virtual addresses from trampoline.S removes the need * to have any identity mapped pages in the kernel page table * after the boot processor executes this code. */ /* Enable PAE mode and PGE */ movl $(X86_CR4_PAE | X86_CR4_PGE), %eax movq %rax, %cr4 /* Setup early boot stage 4 level pagetables. */ movq $(init_level4_pgt - __START_KERNEL_map), %rax addq phys_base(%rip), %rax movq %rax, %cr3 /* Ensure I am executing from virtual addresses */ movq $1f, %rax jmp *%rax 1: /* Check if nx is implemented */ movl $0x80000001, %eax cpuid movl %edx,%edi /* Setup EFER (Extended Feature Enable Register) */ movl $MSR_EFER, %ecx rdmsr btsl $_EFER_SCE, %eax /* Enable System Call */ btl $20,%edi /* No Execute supported? */ jnc 1f btsl $_EFER_NX, %eax 1: wrmsr /* Make changes effective */ /* Setup cr0 */ #define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \ X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \ X86_CR0_PG) movl $CR0_STATE, %eax /* Make changes effective */ movq %rax, %cr0 /* Setup a boot time stack */ movq stack_start(%rip),%rsp /* zero EFLAGS after setting rsp */ pushq $0 popfq /* * We must switch to a new descriptor in kernel space for the GDT * because soon the kernel won't have access anymore to the userspace * addresses where we're currently running on. We have to do that here * because in 32bit we couldn't load a 64bit linear address. */ lgdt early_gdt_descr(%rip) /* set up data segments. actually 0 would do too */ movl $__KERNEL_DS,%eax movl %eax,%ds movl %eax,%ss movl %eax,%es /* * We don't really need to load %fs or %gs, but load them anyway * to kill any stale realmode selectors. This allows execution * under VT hardware. */ movl %eax,%fs movl %eax,%gs /* * Setup up a dummy PDA. this is just for some early bootup code * that does in_interrupt() */ movl $MSR_GS_BASE,%ecx movq $empty_zero_page,%rax movq %rax,%rdx shrq $32,%rdx wrmsr /* esi is pointer to real mode structure with interesting info. pass it to C */ movl %esi, %edi /* Finally jump to run C code and to be on real kernel address * Since we are running on identity-mapped space we have to jump * to the full 64bit address, this is only possible as indirect * jump. In addition we need to ensure %cs is set so we make this * a far return. */ movq initial_code(%rip),%rax pushq $0 # fake return address to stop unwinder pushq $__KERNEL_CS # set correct cs pushq %rax # target address in negative space lretq /* SMP bootup changes these two */ __REFDATA .align 8 ENTRY(initial_code) .quad x86_64_start_kernel __FINITDATA ENTRY(stack_start) .quad init_thread_union+THREAD_SIZE-8 .word 0 bad_address: jmp bad_address .section ".init.text","ax" #ifdef CONFIG_EARLY_PRINTK .globl early_idt_handlers early_idt_handlers: i = 0 .rept NUM_EXCEPTION_VECTORS movl $i, %esi jmp early_idt_handler i = i + 1 .endr #endif ENTRY(early_idt_handler) #ifdef CONFIG_EARLY_PRINTK cmpl $2,early_recursion_flag(%rip) jz 1f incl early_recursion_flag(%rip) GET_CR2_INTO_RCX movq %rcx,%r9 xorl %r8d,%r8d # zero for error code movl %esi,%ecx # get vector number # Test %ecx against mask of vectors that push error code. cmpl $31,%ecx ja 0f movl $1,%eax salq %cl,%rax testl $0x27d00,%eax je 0f popq %r8 # get error code 0: movq 0(%rsp),%rcx # get ip movq 8(%rsp),%rdx # get cs xorl %eax,%eax leaq early_idt_msg(%rip),%rdi call early_printk cmpl $2,early_recursion_flag(%rip) jz 1f call dump_stack #ifdef CONFIG_KALLSYMS leaq early_idt_ripmsg(%rip),%rdi movq 8(%rsp),%rsi # get rip again call __print_symbol #endif #endif /* EARLY_PRINTK */ 1: hlt jmp 1b #ifdef CONFIG_EARLY_PRINTK early_recursion_flag: .long 0 early_idt_msg: .asciz "PANIC: early exception %02lx rip %lx:%lx error %lx cr2 %lx\n" early_idt_ripmsg: .asciz "RIP %s\n" #endif /* CONFIG_EARLY_PRINTK */ .previous .balign PAGE_SIZE #define NEXT_PAGE(name) \ .balign PAGE_SIZE; \ ENTRY(name) /* Automate the creation of 1 to 1 mapping pmd entries */ #define PMDS(START, PERM, COUNT) \ i = 0 ; \ .rept (COUNT) ; \ .quad (START) + (i << PMD_SHIFT) + (PERM) ; \ i = i + 1 ; \ .endr /* * This default setting generates an ident mapping at address 0x100000 * and a mapping for the kernel that precisely maps virtual address * 0xffffffff80000000 to physical address 0x000000. (always using * 2Mbyte large pages provided by PAE mode) */ NEXT_PAGE(init_level4_pgt) .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE .org init_level4_pgt + L4_PAGE_OFFSET*8, 0 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE .org init_level4_pgt + L4_START_KERNEL*8, 0 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */ .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE NEXT_PAGE(level3_ident_pgt) .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE .fill 511,8,0 NEXT_PAGE(level3_kernel_pgt) .fill L3_START_KERNEL,8,0 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */ .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE NEXT_PAGE(level2_fixmap_pgt) .fill 506,8,0 .quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */ .fill 5,8,0 NEXT_PAGE(level1_fixmap_pgt) .fill 512,8,0 NEXT_PAGE(level2_ident_pgt) /* Since I easily can, map the first 1G. * Don't set NX because code runs from these pages. */ PMDS(0, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD) NEXT_PAGE(level2_kernel_pgt) /* * 512 MB kernel mapping. We spend a full page on this pagetable * anyway. * * The kernel code+data+bss must not be bigger than that. * * (NOTE: at +512MB starts the module area, see MODULES_VADDR. * If you want to increase this then increase MODULES_VADDR * too.) */ PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE) NEXT_PAGE(level2_spare_pgt) .fill 512, 8, 0 #undef PMDS #undef NEXT_PAGE .data .align 16 .globl early_gdt_descr early_gdt_descr: .word GDT_ENTRIES*8-1 .quad per_cpu__gdt_page ENTRY(phys_base) /* This must match the first entry in level2_kernel_pgt */ .quad 0x0000000000000000 #include "../../x86/xen/xen-head.S" .section .bss, "aw", @nobits .align L1_CACHE_BYTES ENTRY(idt_table) .skip 256 * 16 .section .bss.page_aligned, "aw", @nobits .align PAGE_SIZE ENTRY(empty_zero_page) .skip PAGE_SIZE |