/* * 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 .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