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Diffstat (limited to 'sys/amd64/amd64/mpboot.S')
| -rw-r--r-- | sys/amd64/amd64/mpboot.S | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/sys/amd64/amd64/mpboot.S b/sys/amd64/amd64/mpboot.S new file mode 100644 index 000000000000..5576affbe836 --- /dev/null +++ b/sys/amd64/amd64/mpboot.S @@ -0,0 +1,236 @@ +/*- + * Copyright (c) 2003 Peter Wemm + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include <machine/asmacros.h> /* miscellaneous asm macros */ +#include <machine/specialreg.h> + +#include "assym.s" + + .data /* So we can modify it */ + + .p2align 4,0 + .globl mptramp_start +mptramp_start: + .code16 + /* + * The AP enters here in response to the startup IPI. + * We are in real mode. %cs is the only segment register set. + */ + cli /* make sure no interrupts */ + mov %cs, %ax /* copy %cs to %ds. Remember these */ + mov %ax, %ds /* are offsets rather than selectors */ + mov %ax, %ss + + /* + * Find relocation base and patch the gdt descript and ljmp targets + */ + xorl %ebx,%ebx + mov %cs, %bx + sall $4, %ebx /* %ebx is now our relocation base */ + orl %ebx, lgdt_desc-mptramp_start+2 + orl %ebx, jmp_32-mptramp_start+2 + orl %ebx, jmp_64-mptramp_start+1 + + /* + * Load the descriptor table pointer. We'll need it when running + * in 16 bit protected mode. + */ + lgdt lgdt_desc-mptramp_start + + /* Enable protected mode */ + movl $CR0_PE, %eax + mov %eax, %cr0 + + /* + * Now execute a far jump to turn on protected mode. This + * causes the segment registers to turn into selectors and causes + * %cs to be loaded from the gdt. + * + * The following instruction is: + * ljmpl $bootcode-gdt, $protmode-mptramp_start + * but gas cannot assemble that. And besides, we patch the targets + * in early startup and its a little clearer what we are patching. + */ +jmp_32: + .byte 0x66 /* size override to 32 bits */ + .byte 0xea /* opcode for far jump */ + .long protmode-mptramp_start /* offset in segment */ + .word bootcode-gdt /* index in gdt for 32 bit code */ + + /* + * At this point, we are running in 32 bit legacy protected mode. + */ + .code32 +protmode: + mov $bootdata-gdt, %eax + mov %ax, %ds + + /* Turn on the PAE bit for when paging is enabled */ + mov %cr4, %eax + orl $CR4_PAE, %eax + mov %eax, %cr4 + + /* + * Enable EFER.LME so that we get long mode when all the prereqs are + * in place. In this case, it turns on when CR0_PG is finally enabled. + * Pick up a few other EFER bits that we'll use need we're here. + */ + movl $MSR_EFER, %ecx + rdmsr + orl $EFER_LME | EFER_SCE, %eax + wrmsr + + /* + * Point to the embedded page tables for startup. Note that this + * only gets accessed after we're actually in 64 bit mode, however + * we can only set the bottom 32 bits of %cr3 in this state. This + * means we are required to use a temporary page table that is below + * the 4GB limit. %ebx is still our relocation base. We could just + * subtract 3 * PAGE_SIZE, but that would be too easy. + */ + leal mptramp_pagetables-mptramp_start(%ebx),%eax + movl (%eax), %eax + mov %eax, %cr3 + + /* + * Finally, switch to long bit mode by enabling paging. We have + * to be very careful here because all the segmentation disappears + * out from underneath us. The spec says we can depend on the + * subsequent pipelined branch to execute, but *only if* everything + * is still identity mapped. If any mappings change, the pipeline + * will flush. + */ + mov %cr0, %eax + orl $CR0_PG, %eax + mov %eax, %cr0 + + /* + * At this point paging is enabled, and we are in "compatibility" mode. + * We do another far jump to reload %cs with the 64 bit selector. + * %cr3 points to a 4-level page table page. + * We cannot yet jump all the way to the kernel because we can only + * specify a 32 bit linear address. So, yet another trampoline. + * + * The following instruction is: + * ljmp $kernelcode-gdt, $tramp_64-mptramp_start + * but gas cannot assemble that. And besides, we patch the targets + * in early startup and its a little clearer what we are patching. + */ +jmp_64: + .byte 0xea /* opcode for far jump */ + .long tramp_64-mptramp_start /* offset in segment */ + .word kernelcode-gdt /* index in gdt for 64 bit code */ + + /* + * Yeehar! We're running in 64 bit mode! We can mostly ignore our + * segment registers, and get on with it. + * Note that we are running at the correct virtual address, but with + * a 1:1 1GB mirrored mapping over entire address space. We had better + * switch to a real %cr3 promptly so that we can get to the direct map + * space. Remember that jmp is relative and that we've been relocated, + * so use an indirect jump. + */ + .code64 +tramp_64: + movabsq $entry_64,%rax /* 64 bit immediate load */ + jmp *%rax + + .p2align 4,0 +gdt: + /* + * All segment descriptor tables start with a null descriptor + */ + .long 0x00000000 + .long 0x00000000 + + /* + * This is the 64 bit long mode code descriptor. There is no + * 64 bit data descriptor. + */ +kernelcode: + .long 0x00000000 + .long 0x00209800 + + /* + * This is the descriptor for the 32 bit boot code. + * %cs: +A, +R, -C, DPL=0, +P, +D, +G + * Accessed, Readable, Present, 32 bit, 4G granularity + */ +bootcode: + .long 0x0000ffff + .long 0x00cf9b00 + + /* + * This is the descriptor for the 32 bit boot data. + * We load it into %ds and %ss. The bits for each selector + * are interpreted slightly differently. + * %ds: +A, +W, -E, DPL=0, +P, +D, +G + * %ss: +A, +W, -E, DPL=0, +P, +B, +G + * Accessed, Writeable, Expand up, Present, 32 bit, 4GB + * For %ds, +D means 'default operand size is 32 bit'. + * For %ss, +B means the stack register is %esp rather than %sp. + */ +bootdata: + .long 0x0000ffff + .long 0x00cf9300 + +gdtend: + + /* + * The address of our page table pages that the boot code + * uses to trampoline up to kernel address space. + */ + .globl mptramp_pagetables +mptramp_pagetables: + .long 0 + + /* + * The pseudo descriptor for lgdt to use. + */ +lgdt_desc: + .word gdtend-gdt /* Length */ + .long gdt-mptramp_start /* Offset plus %ds << 4 */ + + .globl mptramp_end +mptramp_end: + + /* + * From here on down is executed in the kernel .text section. + * + * Load a real %cr3 that has all the direct map stuff and switches + * off the 1GB replicated mirror. Load a stack pointer and jump + * into AP startup code in C. + */ + .text + .code64 + .p2align 4,0 +entry_64: + movq KPML4phys, %rax + movq %rax, %cr3 + movq bootSTK, %rsp + jmp init_secondary |