diff options
Diffstat (limited to 'sys/arch')
| -rw-r--r-- | sys/arch/amd64/cpu/boot.S | 9 | ||||
| -rw-r--r-- | sys/arch/amd64/cpu/gdt.S | 81 |
2 files changed, 88 insertions, 2 deletions
diff --git a/sys/arch/amd64/cpu/boot.S b/sys/arch/amd64/cpu/boot.S index 9fb8b60..3ce82e6 100644 --- a/sys/arch/amd64/cpu/boot.S +++ b/sys/arch/amd64/cpu/boot.S @@ -29,12 +29,17 @@ .globl _start .extern uart_init + .extern gdt_load + .extern GDTR _start: cli cld - xor %rbp, %rbp - call uart_init + xor %rbp, %rbp /* Terminate callstack */ + call uart_init /* Initialize platform UART */ + + lea GDTR(%rip), %rdi /* Our GDTR */ + call gdt_load /* Load our GDT */ 1: cli hlt diff --git a/sys/arch/amd64/cpu/gdt.S b/sys/arch/amd64/cpu/gdt.S new file mode 100644 index 0000000..b46f397 --- /dev/null +++ b/sys/arch/amd64/cpu/gdt.S @@ -0,0 +1,81 @@ +/* + * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team. + * 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. + * 3. Neither the name of Hyra nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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. + */ + .text + .globl gdt_load +gdt_load: + /* + * void gdt_load(GDTR *GDTR); + */ + + push %r12 + push %r13 + push %r14 + push %r15 + push %rbx + push %rbp + + lgdt (%rdi) /* Load our own GDT */ + lea 1f(%rip), %rbx /* Save the drop point */ + push $0x08 /* FRAME.CS */ + push %rbx /* FRAME.RIP */ + lretq /* Flush prefetch and update CS */ +1: mov $0x10, %ax /* Our DS */ + mov %ax, %ds /* Data segment */ + mov %ax, %fs /* F segment */ + mov %ax, %ss /* Stack segment */ + mov %ax, %es /* Extra segment */ + xor %ax, %ax /* We want GS in a known state */ + mov %ax, %gs /* Load it with NULL */ + + pop %rbp + pop %rbx + pop %r15 + pop %r14 + pop %r13 + pop %r12 + retq + + .section .data + .globl GDT +GDT: +.NULL: + .quad 0x0000000000000000 +.CODE: + .quad 0x00209A0000000000 +.DATA: + .quad 0x0000920000000000 + + .globl GDTR +GDTR: + .word . - GDT - 1 + .quad GDT + + +/* vim: ft=gas : +*/ |