diff options
Diffstat (limited to 'arch/x86/machine/boot.S')
-rw-r--r-- | arch/x86/machine/boot.S | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/arch/x86/machine/boot.S b/arch/x86/machine/boot.S new file mode 100644 index 00000000..ece1bb89 --- /dev/null +++ b/arch/x86/machine/boot.S @@ -0,0 +1,243 @@ +/* + * Copyright (c) 2010, 2012 Richard Braun. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#define __ASSEMBLY__ + +#include <machine/asm.h> +#include <machine/cpu.h> +#include <machine/boot.h> +#include <machine/multiboot.h> + +/* + * Convert a physical address in the .boot section to its real address in + * the MP trampoline code. + */ +#define BOOT_MP_ADDR_PTOT(addr) (BOOT_MP_TRAMPOLINE_ADDR + (addr) \ + - boot_ap_start) + +.section .boothdr, "wax" + + /* + * Multiboot header. + */ +.align 4 +DATA(boot_header) + .long MULTIBOOT_OS_MAGIC + .long MULTIBOOT_OS_FLAGS + .long -(MULTIBOOT_OS_FLAGS + MULTIBOOT_OS_MAGIC) +END(boot_header) + +/* + * Entry point. + */ +ENTRY(_start) + .code32 + /* + * Set up a simple GDT to conform to the multiboot specification. + */ + lgdt boot_gdtr + + /* + * Keep %eax and %ebx. + */ + movw $0x10, %cx + movw %cx, %ds + movw %cx, %es + movw %cx, %ss + xorw %cx, %cx + movw %cx, %fs + movw %cx, %gs + ljmp $8, $1f + +1: + +/* XXX For now */ +#ifdef __LP64__ + hlt +#endif + + /* + * Set up the init stack. + */ + movl $(init_stack + BOOT_STACK_SIZE), %esp + movl %esp, %ebp + + /* + * Enable paging. + */ + pushl %ebx + pushl %eax + call init_paging + movl %eax, %cr3 + movl %cr0, %eax + orl $CPU_CR0_PG, %eax + movl %eax, %cr0 + ljmp $8, $1f + +1: +#ifdef __LP64__ + hlt +#else /* __LP64__ */ + /* + * Reset the stack, use high addresses. + */ + movl $(init_stack + BOOT_STACK_SIZE + KERNEL_OFFSET), %esp + movl %esp, %ebp + + /* + * Prevent stack tracing from searching previous frames. + */ + pushl $0 + jmp init +#endif /* __LP64__ */ + + /* + * Never reached. + */ +END(_start) + +.section .boot, "wax" + +DATA(boot_gdtr) + .word (8 * 3) + .long boot_gdt +END(boot_gdtr) + +/* + * This is where an AP runs after leaving the trampoline code. + */ +ENTRY(boot_ap_start32) + /* + * Set up the GDT again, because the current one is from the trampoline code + * which isn't part of the identity mapping and won't be available once paging + * is enabled. + */ + lgdt boot_gdtr + movw $0x10, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %ss + xorw %ax, %ax + movw %ax, %fs + movw %ax, %gs + ljmp $8, $1f + +1: + /* + * Set up the init stack. + */ + movl $(init_ap_stack + BOOT_STACK_SIZE), %esp + movl %esp, %ebp + + /* + * Enable paging. + */ + call init_ap_paging + movl %eax, %cr3 + movl %cr0, %eax + orl $CPU_CR0_PG, %eax + movl %eax, %cr0 + ljmp $8, $1f + +1: + /* + * Switch to the boot stack preallocated for this AP by the BSP. + */ + movl init_ap_boot_stack_addr, %esp + addl $BOOT_STACK_SIZE, %esp + movl %esp, %ebp + + /* + * Prevent stack tracing from searching previous frames. + */ + pushl $0 + jmp init_ap + + /* + * Never reached. + */ +END(boot_ap_start32) + +/* + * This section, including the GDT, is the MP trampoline code run by APs + * on startup. It is copied at a fixed location in the first segment and + * must enable protected mode to jump back into the kernel. + */ +.align 8 +ENTRY(boot_ap_start) + .code16 + cli + xorw %ax, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + movw %ax, %ss + lgdt BOOT_MP_ADDR_PTOT(boot_ap_gdtr) + movl %cr0, %eax + orl $CPU_CR0_PE, %eax + movl %eax, %cr0 + ljmp $8, $BOOT_MP_ADDR_PTOT(1f) + +.align 4 +1: + .code32 + movw $0x10, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %ss + xorw %ax, %ax + movw %ax, %fs + movw %ax, %gs + ljmp $8, $boot_ap_start32 +END(boot_ap_start) + +DATA(boot_ap_gdtr) + .word (8 * 3) + .long BOOT_MP_ADDR_PTOT(boot_gdt) +END(boot_ap_gdtr) + +.align 8 +DATA(boot_gdt) + /* + * Null selector. + */ + .word 0x0000 + .word 0x0000 + .word 0x0000 + .word 0x0000 + + /* + * Code segment selector. + */ + .word 0xffff + .word 0x0000 + .word 0x9a00 + .word 0x00cf + + /* + * Data segment selector. + */ + .word 0xffff + .word 0x0000 + .word 0x9200 + .word 0x00cf +END(boot_gdt) + +DATA(boot_ap_size) + .long . - boot_ap_start +END(boot_ap_size) |