1/* 2 * linux/arch/x86/kernel/head_64.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/segment.h> 16#include <asm/pgtable.h> 17#include <asm/page.h> 18#include <asm/msr.h> 19#include <asm/cache.h> 20#include <asm/processor-flags.h> 21#include <asm/percpu.h> 22#include <asm/nops.h> 23#include "../entry/calling.h" 24#include <asm/export.h> 25 26#ifdef CONFIG_PARAVIRT 27#include <asm/asm-offsets.h> 28#include <asm/paravirt.h> 29#define GET_CR2_INTO(reg) GET_CR2_INTO_RAX ; movq %rax, reg 30#else 31#define GET_CR2_INTO(reg) movq %cr2, reg 32#define INTERRUPT_RETURN iretq 33#endif 34 35/* we are not able to switch in one step to the final KERNEL ADDRESS SPACE 36 * because we need identity-mapped pages. 37 * 38 */ 39 40#define p4d_index(x) (((x) >> P4D_SHIFT) & (PTRS_PER_P4D-1)) 41#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1)) 42 43PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE) 44PGD_START_KERNEL = pgd_index(__START_KERNEL_map) 45L3_START_KERNEL = pud_index(__START_KERNEL_map) 46 47 .text 48 __HEAD 49 .code64 50 .globl startup_64 51startup_64: 52 UNWIND_HINT_EMPTY 53 /* 54 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0, 55 * and someone has loaded an identity mapped page table 56 * for us. These identity mapped page tables map all of the 57 * kernel pages and possibly all of memory. 58 * 59 * %rsi holds a physical pointer to real_mode_data. 60 * 61 * We come here either directly from a 64bit bootloader, or from 62 * arch/x86/boot/compressed/head_64.S. 63 * 64 * We only come here initially at boot nothing else comes here. 65 * 66 * Since we may be loaded at an address different from what we were 67 * compiled to run at we first fixup the physical addresses in our page 68 * tables and then reload them. 69 */ 70 71 /* Set up the stack for verify_cpu(), similar to initial_stack below */ 72 leaq (__end_init_task - SIZEOF_PTREGS)(%rip), %rsp 73 74 /* Sanitize CPU configuration */ 75 call verify_cpu 76 77 /* 78 * Perform pagetable fixups. Additionally, if SME is active, encrypt 79 * the kernel and retrieve the modifier (SME encryption mask if SME 80 * is active) to be added to the initial pgdir entry that will be 81 * programmed into CR3. 82 */ 83 leaq _text(%rip), %rdi 84 pushq %rsi 85 call __startup_64 86 popq %rsi 87 88 /* Form the CR3 value being sure to include the CR3 modifier */ 89 addq $(early_top_pgt - __START_KERNEL_map), %rax 90 jmp 1f 91ENTRY(secondary_startup_64) 92 UNWIND_HINT_EMPTY 93 /* 94 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0, 95 * and someone has loaded a mapped page table. 96 * 97 * %rsi holds a physical pointer to real_mode_data. 98 * 99 * We come here either from startup_64 (using physical addresses) 100 * or from trampoline.S (using virtual addresses). 101 * 102 * Using virtual addresses from trampoline.S removes the need 103 * to have any identity mapped pages in the kernel page table 104 * after the boot processor executes this code. 105 */ 106 107 /* Sanitize CPU configuration */ 108 call verify_cpu 109 110 /* 111 * Retrieve the modifier (SME encryption mask if SME is active) to be 112 * added to the initial pgdir entry that will be programmed into CR3. 113 */ 114 pushq %rsi 115 call __startup_secondary_64 116 popq %rsi 117 118 /* Form the CR3 value being sure to include the CR3 modifier */ 119 addq $(init_top_pgt - __START_KERNEL_map), %rax 1201: 121 122 /* Enable PAE mode, PGE and LA57 */ 123 movl $(X86_CR4_PAE | X86_CR4_PGE), %ecx 124#ifdef CONFIG_X86_5LEVEL 125 orl $X86_CR4_LA57, %ecx 126#endif 127 movq %rcx, %cr4 128 129 /* Setup early boot stage 4-/5-level pagetables. */ 130 addq phys_base(%rip), %rax 131 movq %rax, %cr3 132 133 /* Ensure I am executing from virtual addresses */ 134 movq $1f, %rax 135 jmp *%rax 1361: 137 UNWIND_HINT_EMPTY 138 139 /* Check if nx is implemented */ 140 movl $0x80000001, %eax 141 cpuid 142 movl %edx,%edi 143 144 /* Setup EFER (Extended Feature Enable Register) */ 145 movl $MSR_EFER, %ecx 146 rdmsr 147 btsl $_EFER_SCE, %eax /* Enable System Call */ 148 btl $20,%edi /* No Execute supported? */ 149 jnc 1f 150 btsl $_EFER_NX, %eax 151 btsq $_PAGE_BIT_NX,early_pmd_flags(%rip) 1521: wrmsr /* Make changes effective */ 153 154 /* Setup cr0 */ 155 movl $CR0_STATE, %eax 156 /* Make changes effective */ 157 movq %rax, %cr0 158 159 /* Setup a boot time stack */ 160 movq initial_stack(%rip), %rsp 161 162 /* zero EFLAGS after setting rsp */ 163 pushq $0 164 popfq 165 166 /* 167 * We must switch to a new descriptor in kernel space for the GDT 168 * because soon the kernel won't have access anymore to the userspace 169 * addresses where we're currently running on. We have to do that here 170 * because in 32bit we couldn't load a 64bit linear address. 171 */ 172 lgdt early_gdt_descr(%rip) 173 174 /* set up data segments */ 175 xorl %eax,%eax 176 movl %eax,%ds 177 movl %eax,%ss 178 movl %eax,%es 179 180 /* 181 * We don't really need to load %fs or %gs, but load them anyway 182 * to kill any stale realmode selectors. This allows execution 183 * under VT hardware. 184 */ 185 movl %eax,%fs 186 movl %eax,%gs 187 188 /* Set up %gs. 189 * 190 * The base of %gs always points to the bottom of the irqstack 191 * union. If the stack protector canary is enabled, it is 192 * located at %gs:40. Note that, on SMP, the boot cpu uses 193 * init data section till per cpu areas are set up. 194 */ 195 movl $MSR_GS_BASE,%ecx 196 movl initial_gs(%rip),%eax 197 movl initial_gs+4(%rip),%edx 198 wrmsr 199 200 /* rsi is pointer to real mode structure with interesting info. 201 pass it to C */ 202 movq %rsi, %rdi 203 204.Ljump_to_C_code: 205 /* 206 * Jump to run C code and to be on a real kernel address. 207 * Since we are running on identity-mapped space we have to jump 208 * to the full 64bit address, this is only possible as indirect 209 * jump. In addition we need to ensure %cs is set so we make this 210 * a far return. 211 * 212 * Note: do not change to far jump indirect with 64bit offset. 213 * 214 * AMD does not support far jump indirect with 64bit offset. 215 * AMD64 Architecture Programmer's Manual, Volume 3: states only 216 * JMP FAR mem16:16 FF /5 Far jump indirect, 217 * with the target specified by a far pointer in memory. 218 * JMP FAR mem16:32 FF /5 Far jump indirect, 219 * with the target specified by a far pointer in memory. 220 * 221 * Intel64 does support 64bit offset. 222 * Software Developer Manual Vol 2: states: 223 * FF /5 JMP m16:16 Jump far, absolute indirect, 224 * address given in m16:16 225 * FF /5 JMP m16:32 Jump far, absolute indirect, 226 * address given in m16:32. 227 * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect, 228 * address given in m16:64. 229 */ 230 pushq $.Lafter_lret # put return address on stack for unwinder 231 xorq %rbp, %rbp # clear frame pointer 232 movq initial_code(%rip), %rax 233 pushq $__KERNEL_CS # set correct cs 234 pushq %rax # target address in negative space 235 lretq 236.Lafter_lret: 237END(secondary_startup_64) 238 239#include "verify_cpu.S" 240 241#ifdef CONFIG_HOTPLUG_CPU 242/* 243 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set 244 * up already except stack. We just set up stack here. Then call 245 * start_secondary() via .Ljump_to_C_code. 246 */ 247ENTRY(start_cpu0) 248 movq initial_stack(%rip), %rsp 249 UNWIND_HINT_EMPTY 250 jmp .Ljump_to_C_code 251ENDPROC(start_cpu0) 252#endif 253 254 /* Both SMP bootup and ACPI suspend change these variables */ 255 __REFDATA 256 .balign 8 257 GLOBAL(initial_code) 258 .quad x86_64_start_kernel 259 GLOBAL(initial_gs) 260 .quad INIT_PER_CPU_VAR(irq_stack_union) 261 GLOBAL(initial_stack) 262 /* 263 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel 264 * unwinder reliably detect the end of the stack. 265 */ 266 .quad init_thread_union + THREAD_SIZE - SIZEOF_PTREGS 267 __FINITDATA 268 269 __INIT 270ENTRY(early_idt_handler_array) 271 i = 0 272 .rept NUM_EXCEPTION_VECTORS 273 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 274 UNWIND_HINT_IRET_REGS 275 pushq $0 # Dummy error code, to make stack frame uniform 276 .else 277 UNWIND_HINT_IRET_REGS offset=8 278 .endif 279 pushq $i # 72(%rsp) Vector number 280 jmp early_idt_handler_common 281 UNWIND_HINT_IRET_REGS 282 i = i + 1 283 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 284 .endr 285 UNWIND_HINT_IRET_REGS offset=16 286END(early_idt_handler_array) 287 288early_idt_handler_common: 289 /* 290 * The stack is the hardware frame, an error code or zero, and the 291 * vector number. 292 */ 293 cld 294 295 incl early_recursion_flag(%rip) 296 297 /* The vector number is currently in the pt_regs->di slot. */ 298 pushq %rsi /* pt_regs->si */ 299 movq 8(%rsp), %rsi /* RSI = vector number */ 300 movq %rdi, 8(%rsp) /* pt_regs->di = RDI */ 301 pushq %rdx /* pt_regs->dx */ 302 pushq %rcx /* pt_regs->cx */ 303 pushq %rax /* pt_regs->ax */ 304 pushq %r8 /* pt_regs->r8 */ 305 pushq %r9 /* pt_regs->r9 */ 306 pushq %r10 /* pt_regs->r10 */ 307 pushq %r11 /* pt_regs->r11 */ 308 pushq %rbx /* pt_regs->bx */ 309 pushq %rbp /* pt_regs->bp */ 310 pushq %r12 /* pt_regs->r12 */ 311 pushq %r13 /* pt_regs->r13 */ 312 pushq %r14 /* pt_regs->r14 */ 313 pushq %r15 /* pt_regs->r15 */ 314 UNWIND_HINT_REGS 315 316 cmpq $14,%rsi /* Page fault? */ 317 jnz 10f 318 GET_CR2_INTO(%rdi) /* Can clobber any volatile register if pv */ 319 call early_make_pgtable 320 andl %eax,%eax 321 jz 20f /* All good */ 322 32310: 324 movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */ 325 call early_fixup_exception 326 32720: 328 decl early_recursion_flag(%rip) 329 jmp restore_regs_and_return_to_kernel 330END(early_idt_handler_common) 331 332 __INITDATA 333 334 .balign 4 335GLOBAL(early_recursion_flag) 336 .long 0 337 338#define NEXT_PAGE(name) \ 339 .balign PAGE_SIZE; \ 340GLOBAL(name) 341 342/* Automate the creation of 1 to 1 mapping pmd entries */ 343#define PMDS(START, PERM, COUNT) \ 344 i = 0 ; \ 345 .rept (COUNT) ; \ 346 .quad (START) + (i << PMD_SHIFT) + (PERM) ; \ 347 i = i + 1 ; \ 348 .endr 349 350 __INITDATA 351NEXT_PAGE(early_top_pgt) 352 .fill 511,8,0 353#ifdef CONFIG_X86_5LEVEL 354 .quad level4_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 355#else 356 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 357#endif 358 359NEXT_PAGE(early_dynamic_pgts) 360 .fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0 361 362 .data 363 364#ifndef CONFIG_XEN 365NEXT_PAGE(init_top_pgt) 366 .fill 512,8,0 367#else 368NEXT_PAGE(init_top_pgt) 369 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 370 .org init_top_pgt + PGD_PAGE_OFFSET*8, 0 371 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 372 .org init_top_pgt + PGD_START_KERNEL*8, 0 373 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */ 374 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 375 376NEXT_PAGE(level3_ident_pgt) 377 .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 378 .fill 511, 8, 0 379NEXT_PAGE(level2_ident_pgt) 380 /* Since I easily can, map the first 1G. 381 * Don't set NX because code runs from these pages. 382 */ 383 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD) 384#endif 385 386#ifdef CONFIG_X86_5LEVEL 387NEXT_PAGE(level4_kernel_pgt) 388 .fill 511,8,0 389 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 390#endif 391 392NEXT_PAGE(level3_kernel_pgt) 393 .fill L3_START_KERNEL,8,0 394 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */ 395 .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 396 .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 397 398NEXT_PAGE(level2_kernel_pgt) 399 /* 400 * 512 MB kernel mapping. We spend a full page on this pagetable 401 * anyway. 402 * 403 * The kernel code+data+bss must not be bigger than that. 404 * 405 * (NOTE: at +512MB starts the module area, see MODULES_VADDR. 406 * If you want to increase this then increase MODULES_VADDR 407 * too.) 408 */ 409 PMDS(0, __PAGE_KERNEL_LARGE_EXEC, 410 KERNEL_IMAGE_SIZE/PMD_SIZE) 411 412NEXT_PAGE(level2_fixmap_pgt) 413 .fill 506,8,0 414 .quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 415 /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */ 416 .fill 5,8,0 417 418NEXT_PAGE(level1_fixmap_pgt) 419 .fill 512,8,0 420 421#undef PMDS 422 423 .data 424 .align 16 425 .globl early_gdt_descr 426early_gdt_descr: 427 .word GDT_ENTRIES*8-1 428early_gdt_descr_base: 429 .quad INIT_PER_CPU_VAR(gdt_page) 430 431ENTRY(phys_base) 432 /* This must match the first entry in level2_kernel_pgt */ 433 .quad 0x0000000000000000 434EXPORT_SYMBOL(phys_base) 435 436#include "../../x86/xen/xen-head.S" 437 438 __PAGE_ALIGNED_BSS 439NEXT_PAGE(empty_zero_page) 440 .skip PAGE_SIZE 441EXPORT_SYMBOL(empty_zero_page) 442 443