diff options
Diffstat (limited to 'x86_64/boothdr.S')
| -rw-r--r-- | x86_64/boothdr.S | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/x86_64/boothdr.S b/x86_64/boothdr.S new file mode 100644 index 00000000..12fc7ca2 --- /dev/null +++ b/x86_64/boothdr.S @@ -0,0 +1,238 @@ +/* + * Copyright (C) 2022 Free Software Foundation + * + * 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 2 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 the program ; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <mach/machine/asm.h> + +#include <i386/i386asm.h> +#include <i386/i386/proc_reg.h> +#include <i386/i386/seg.h> + /* + * This section will be put first into .boot. See also x86_64/ldscript. + */ + .section .boot.text,"ax" + .globl boot_start + + /* We should never be entered this way. */ + .code32 +boot_start: + jmp boot_entry + + /* MultiBoot header - see multiboot.h. */ +#define MULTIBOOT_MAGIC 0x1BADB002 +#ifdef __ELF__ +#define MULTIBOOT_FLAGS 0x00000003 +#else /* __ELF__ */ +#define MULTIBOOT_FLAGS 0x00010003 +#endif /* __ELF__ */ + P2ALIGN(2) +boot_hdr: + .long MULTIBOOT_MAGIC + .long MULTIBOOT_FLAGS + /* + * The next item here is the checksum. + * XX this works OK until we need at least the 30th bit. + */ + .long - (MULTIBOOT_MAGIC+MULTIBOOT_FLAGS) +#ifndef __ELF__ /* a.out kludge */ + .long boot_hdr /* header_addr */ + .long _start /* load_addr */ + .long _edata /* load_end_addr */ + .long _end /* bss_end_addr */ + .long boot_entry /* entry */ +#endif /* __ELF__ */ + +boot_entry: + /* + * Prepare minimal page mapping to jump to 64 bit and to C code. + * The first 4GB is identity mapped, and the first 2GB are re-mapped + * to high addresses at KERNEL_MAP_BASE + */ + + movl $p3table,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p4table) + /* + * Fill 4 entries in L3 table to cover the whole 32-bit 4GB address + * space. Part of it might be remapped later if the kernel is mapped + * below 4G. + */ + movl $p2table,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3table) + movl $p2table1,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3table + 8) + movl $p2table2,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3table + 16) + movl $p2table3,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3table + 24) + /* point each page table level two entry to a page */ + mov $0,%ecx +.map_p2_table: + mov $0x200000,%eax // 2MiB page, should be always available + mul %ecx + or $(PTE_V|PTE_W|PTE_S),%eax // enable 2MiB page instead of 4k + mov %eax,p2table(,%ecx,8) + inc %ecx + cmp $2048,%ecx // 512 entries per table, map 4 L2 tables + jne .map_p2_table + + /* + * KERNEL_MAP_BASE must me aligned to 2GB. + * Depending on kernel starting address, we might need to add another + * entry in the L4 table (controlling 512 GB chunks). In any case, we + * add two entries in L3 table to make sure we map 2GB for the kernel. + * Note that this may override part of the mapping create above. + */ +.kernel_map: +#if KERNEL_MAP_BASE >= (1U << 39) + movl $p3ktable,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p4table + (8 * ((KERNEL_MAP_BASE >> 39) & 0x1FF))) // select 512G block + movl $p2ktable1,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3ktable + (8 * ((KERNEL_MAP_BASE >> 30) & 0x1FF) )) // select first 1G block + movl $p2ktable2,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3ktable + (8 * (((KERNEL_MAP_BASE >> 30) & 0x1FF) + 1) )) // select second 1G block +#else + movl $p2ktable1,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3table + (8 * ((KERNEL_MAP_BASE >> 30) & 0x1FF) )) // select first 1G block + movl $p2ktable2,%eax + or $(PTE_V|PTE_W),%eax + movl %eax,(p3table + (8 * (((KERNEL_MAP_BASE >> 30) & 0x1FF) + 1) )) // select second 1G block +#endif + + mov $0,%ecx +.map_p2k_table: + mov $0x200000,%eax // 2MiB page, should be always available + mul %ecx + or $(PTE_V|PTE_W|PTE_S),%eax // enable 2MiB page instead of 4K + mov %eax,p2ktable1(,%ecx,8) + inc %ecx + cmp $1024,%ecx // 512 entries per table, map 2 L2 tables + jne .map_p2k_table + +switch64: + /* + * Jump to 64 bit mode, we have to + * - enable PAE + * - enable long mode + * - enable paging and load the tables filled above in CR3 + * - jump to a 64-bit code segment + */ + mov %cr4,%eax + or $CR4_PAE,%eax + mov %eax,%cr4 + mov $0xC0000080,%ecx // select EFER register + rdmsr + or $(1 << 8),%eax // long mode enable bit + wrmsr + mov $p4table,%eax + mov %eax,%cr3 + mov %cr0,%eax + or $CR0_PG,%eax + or $CR0_WP,%eax + mov %eax,%cr0 + + lgdt gdt64pointer + movw $0,%ax + movw %ax,%fs + movw %ax,%gs + movw $16,%ax + movw %ax,%ds + movw %ax,%es + movw %ax,%ss + ljmp $8,$boot_entry64 + + .code64 + + /* why do we need this? it seems overwritten by linker */ + .globl _start +_start: + +boot_entry64: + /* Switch to our own interrupt stack. */ + movq $(_intstack+INTSTACK_SIZE),%rax + andq $(~15),%rax + movq %rax,%rsp + + /* Reset EFLAGS to a known state. */ + pushq $0 + popf + /* save multiboot info for later */ + movq %rbx,%r8 + + /* Fix ifunc entries */ + movq $__rela_iplt_start,%rsi + movq $__rela_iplt_end,%rdi +iplt_cont: + cmpq %rdi,%rsi + jae iplt_done + movq (%rsi),%rbx /* r_offset */ + movb 4(%rsi),%al /* info */ + cmpb $42,%al /* IRELATIVE */ + jnz iplt_next + call *(%ebx) /* call ifunc */ + movq %rax,(%rbx) /* fixed address */ +iplt_next: + addq $8,%rsi + jmp iplt_cont +iplt_done: + + /* restore multiboot info */ + movq %r8,%rdi + /* Jump into C code. */ + call EXT(c_boot_entry) + /* not reached */ + nop + + .section .boot.data + .comm _intstack,INTSTACK_SIZE + + .code32 + .section .boot.data + .align 4096 +#define SEG_ACCESS_OFS 40 +#define SEG_GRANULARITY_OFS 52 +gdt64: + .quad 0 +gdt64code: + .quad (ACC_P << SEG_ACCESS_OFS) | (ACC_CODE_R << SEG_ACCESS_OFS) | (SZ_64 << SEG_GRANULARITY_OFS) +gdt64data: + .quad (ACC_P << SEG_ACCESS_OFS) | (ACC_DATA_W << SEG_ACCESS_OFS) +gdt64end: + .skip (4096 - (gdt64end - gdt64)) +gdt64pointer: + .word gdt64end - gdt64 - 1 + .quad gdt64 + + .section .boot.data + .align 4096 +p4table: .space 4096 +p3table: .space 4096 +p2table: .space 4096 +p2table1: .space 4096 +p2table2: .space 4096 +p2table3: .space 4096 +p3ktable: .space 4096 +p2ktable1: .space 4096 +p2ktable2: .space 4096 |