diff options
Diffstat (limited to 'arch/x86/kernel/head_64.S')
| -rw-r--r-- | arch/x86/kernel/head_64.S | 416 |
1 files changed, 416 insertions, 0 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S new file mode 100644 index 00000000000..b6167fe3330 --- /dev/null +++ b/arch/x86/kernel/head_64.S @@ -0,0 +1,416 @@ +/* + * 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> + +/* we are not able to switch in one step to the final KERNEL ADRESS SPACE + * because we need identity-mapped pages. + * + */ + + .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 $~LARGE_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 + (258*8)(%rip) + addq %rbp, init_level4_pgt + (511*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 $LARGE_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 + */ + 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_SMP + addq %rbp, trampoline_level4_pgt + 0(%rip) + addq %rbp, trampoline_level4_pgt + (511*8)(%rip) +#endif +#ifdef CONFIG_ACPI_SLEEP + addq %rbp, wakeup_level4_pgt + 0(%rip) + addq %rbp, wakeup_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 */ + xorq %rax, %rax + btsq $5, %rax + btsq $7, %rax + 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_PM 1 /* protected mode */ +#define CR0_MP (1<<1) +#define CR0_ET (1<<4) +#define CR0_NE (1<<5) +#define CR0_WP (1<<16) +#define CR0_AM (1<<18) +#define CR0_PAGING (1<<31) + movl $CR0_PM|CR0_MP|CR0_ET|CR0_NE|CR0_WP|CR0_AM|CR0_PAGING,%eax + /* Make changes effective */ + movq %rax, %cr0 + + /* Setup a boot time stack */ + movq init_rsp(%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 cpu_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 */ +#ifndef CONFIG_HOTPLUG_CPU + .pushsection .init.data +#endif + .align 8 + .globl initial_code +initial_code: + .quad x86_64_start_kernel +#ifndef CONFIG_HOTPLUG_CPU + .popsection +#endif + .globl init_rsp +init_rsp: + .quad init_thread_union+THREAD_SIZE-8 + +bad_address: + jmp bad_address + +ENTRY(early_idt_handler) + cmpl $2,early_recursion_flag(%rip) + jz 1f + incl early_recursion_flag(%rip) + xorl %eax,%eax + movq 8(%rsp),%rsi # get rip + movq (%rsp),%rdx + movq %cr2,%rcx + 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 +1: hlt + jmp 1b +early_recursion_flag: + .long 0 + +early_idt_msg: + .asciz "PANIC: early exception rip %lx error %lx cr2 %lx\n" +early_idt_ripmsg: + .asciz "RIP %s\n" + +.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 << 21) + (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 + .fill 257,8,0 + .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE + .fill 252,8,0 + /* (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 510,8,0 + /* (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(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD) + +NEXT_PAGE(level2_kernel_pgt) + /* 40MB kernel mapping. The kernel code cannot be bigger than that. + When you change this change KERNEL_TEXT_SIZE in page.h too. */ + /* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */ + PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL, KERNEL_TEXT_SIZE/PMD_SIZE) + /* Module mapping starts here */ + .fill (PTRS_PER_PMD - (KERNEL_TEXT_SIZE/PMD_SIZE)),8,0 + +NEXT_PAGE(level2_spare_pgt) + .fill 512,8,0 + +#undef PMDS +#undef NEXT_PAGE + + .data + .align 16 + .globl cpu_gdt_descr +cpu_gdt_descr: + .word gdt_end-cpu_gdt_table-1 +gdt: + .quad cpu_gdt_table +#ifdef CONFIG_SMP + .rept NR_CPUS-1 + .word 0 + .quad 0 + .endr +#endif + +ENTRY(phys_base) + /* This must match the first entry in level2_kernel_pgt */ + .quad 0x0000000000000000 + +/* We need valid kernel segments for data and code in long mode too + * IRET will check the segment types kkeil 2000/10/28 + * Also sysret mandates a special GDT layout + */ + + .section .data.page_aligned, "aw" + .align PAGE_SIZE + +/* The TLS descriptors are currently at a different place compared to i386. + Hopefully nobody expects them at a fixed place (Wine?) */ + +ENTRY(cpu_gdt_table) + .quad 0x0000000000000000 /* NULL descriptor */ + .quad 0x00cf9b000000ffff /* __KERNEL32_CS */ + .quad 0x00af9b000000ffff /* __KERNEL_CS */ + .quad 0x00cf93000000ffff /* __KERNEL_DS */ + .quad 0x00cffb000000ffff /* __USER32_CS */ + .quad 0x00cff3000000ffff /* __USER_DS, __USER32_DS */ + .quad 0x00affb000000ffff /* __USER_CS */ + .quad 0x0 /* unused */ + .quad 0,0 /* TSS */ + .quad 0,0 /* LDT */ + .quad 0,0,0 /* three TLS descriptors */ + .quad 0x0000f40000000000 /* node/CPU stored in limit */ +gdt_end: + /* asm/segment.h:GDT_ENTRIES must match this */ + /* This should be a multiple of the cache line size */ + /* GDTs of other CPUs are now dynamically allocated */ + + /* zero the remaining page */ + .fill PAGE_SIZE / 8 - GDT_ENTRIES,8,0 + + .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 |