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Use native syscalls instead of interrupt-based ones, move syscall from

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driver to arch, and add x86_64 specific native syscalls.
This commit is contained in:
csd4ni3l
2026-04-19 22:43:20 +02:00
parent f4c2657b94
commit e1c2373691
10 changed files with 174 additions and 73 deletions
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1
kernel/src/arch/mod.rs
View File

@@ -1,3 +1,4 @@
pub mod arch;
pub mod syscall;
#[cfg(target_arch = "x86_64")]
pub mod x86_64;

5
kernel/src/driver/syscall.rs → kernel/src/arch/syscall.rs
View File

@@ -5,6 +5,7 @@ use core::{
use x86_64::{
VirtAddr,
instructions::interrupts,
structures::paging::{FrameAllocator, Mapper, Page, PageTableFlags, Size4KiB},
};
@@ -190,7 +191,11 @@ pub unsafe extern "C" fn syscall_dispatch(
arg0: isize,
arg1: isize,
arg2: isize,
arg3: isize,
arg4: isize,
arg5: isize,
) -> isize {
interrupts::enable();
match num {
BRK => unsafe { sbrk(arg0) },
WRITE => {

22
kernel/src/arch/x86_64/gdt.rs
View File

@@ -10,7 +10,8 @@ use x86_64::structures::{
pub const DOUBLE_FAULT_IST_INDEX: u16 = 0;
lazy_static! {
static ref TSS: TaskStateSegment = {
#[repr(C, align(4096))]
pub static ref TSS: TaskStateSegment = {
let mut tss = TaskStateSegment::new();
tss.interrupt_stack_table[DOUBLE_FAULT_IST_INDEX as usize] = {
const STACK_SIZE: usize = 4096 * 5;
@@ -40,22 +41,33 @@ lazy_static! {
SegmentSelector,
SegmentSelector,
SegmentSelector,
SegmentSelector,
SegmentSelector
)
) = {
let mut gdt = GlobalDescriptorTable::new();
let kernel_code_selector = gdt.append(Descriptor::kernel_code_segment());
let kernel_data_selector = gdt.append(Descriptor::kernel_data_segment());
let user_code_selector = gdt.append(Descriptor::user_code_segment());
let user_code32_selector = gdt.append(Descriptor::UserSegment(
(x86_64::structures::gdt::DescriptorFlags::USER_SEGMENT
| x86_64::structures::gdt::DescriptorFlags::PRESENT
| x86_64::structures::gdt::DescriptorFlags::EXECUTABLE
| x86_64::structures::gdt::DescriptorFlags::DPL_RING_3)
.bits(),
));
let user_data_selector = gdt.append(Descriptor::user_data_segment());
let user_code_selector = gdt.append(Descriptor::user_code_segment());
let tss_selector = gdt.append(Descriptor::tss_segment(&TSS));
(
gdt,
(
kernel_code_selector,
kernel_data_selector,
user_code_selector,
user_code32_selector,
user_data_selector,
user_code_selector,
tss_selector,
),
)
@@ -70,12 +82,12 @@ pub fn load_gdt_x86_64() {
DS::set_reg(GDT.1.1);
ES::set_reg(GDT.1.1);
SS::set_reg(GDT.1.1);
load_tss(GDT.1.4);
load_tss(GDT.1.5);
}
}
pub fn user_code_selector() -> SegmentSelector {
GDT.1.2
GDT.1.4
}
pub fn user_data_selector() -> SegmentSelector {

3
kernel/src/arch/x86_64/init.rs
View File

@@ -3,6 +3,7 @@ use crate::{
gdt::load_gdt_x86_64,
interrupts::{PICS, init_idt_x86_64},
mouse::setup_mouse,
syscall::init_syscalls,
},
driver::mouse::MOUSE,
};
@@ -74,6 +75,8 @@ pub fn init_x86_64<'a>(
init_idt_x86_64();
init_syscalls();
unsafe {
let mut pics = PICS.lock();
pics.initialize();

52
kernel/src/arch/x86_64/interrupts.rs
View File

@@ -7,7 +7,6 @@ use lazy_static::lazy_static;
use pic8259::ChainedPics;
use spin::Mutex;
use x86_64::{
VirtAddr,
instructions::port::Port,
registers::control::Cr2,
structures::idt::{InterruptDescriptorTable, InterruptStackFrame, PageFaultErrorCode},
@@ -44,10 +43,6 @@ lazy_static! {
idt.double_fault
.set_handler_fn(double_fault_handler)
.set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
#[allow(function_casts_as_integer)]
idt[0x80]
.set_handler_addr(VirtAddr::new(syscall_interrupt_handler as u64))
.set_privilege_level(x86_64::PrivilegeLevel::Ring3);
}
idt[InterruptIndex::Timer.as_u8()].set_handler_fn(timer_interrupt_handler);
idt.page_fault.set_handler_fn(page_fault_handler);
@@ -136,50 +131,3 @@ pub extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: Interrupt
.notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
}
}
#[unsafe(naked)]
unsafe extern "C" fn syscall_interrupt_handler() {
core::arch::naked_asm!(
// push all registers
"push r15",
"push r14",
"push r13",
"push r12",
"push r11",
"push r10",
"push r9",
"push r8",
"push rbp",
"push rbx",
"push rcx",
"push rdx",
"push rsi",
"push rdi",
"push rax",
"sub rsp, 8",
"sti", // allow IRQ interrupts
"mov rcx, rdx", // arg2
"mov rdx, rsi", // arg1
"mov rsi, rdi", // arg0
"mov rdi, rax", // num
"call syscall_dispatch",
"add rsp, 8",
"add rsp, 8",
// pop them in reverse orser
"pop rdi",
"pop rsi",
"pop rdx",
"pop rcx",
"pop rbx",
"pop rbp",
"pop r8",
"pop r9",
"pop r10",
"pop r11",
"pop r12",
"pop r13",
"pop r14",
"pop r15",
"iretq",
)
}

1
kernel/src/arch/x86_64/mod.rs
View File

@@ -5,4 +5,5 @@ pub mod init;
pub mod interrupts;
pub mod mouse;
pub mod paging;
pub mod syscall;
pub mod usermode;

136
kernel/src/arch/x86_64/syscall.rs Normal file
View File

@@ -0,0 +1,136 @@
use core::arch::asm;
use lazy_static::lazy_static;
use x86_64::instructions::tlb::{self, flush_all};
use crate::arch::x86_64::gdt::{GDT, TSS};
const IA32_EFER: u32 = 0xC0000080;
const IA32_EFER_SCE: u64 = 1; // system call enable bit
const IA32_STAR: u32 = 0xC0000081;
const IA32_LSTAR: u32 = 0xC0000082;
const IA32_FMASK: u32 = 0xC0000084;
const IA32_KERNEL_GS_BASE: u32 = 0xC0000102;
#[repr(C)]
pub struct PerCpuData {
pub user_rsp: u64,
pub kernel_rsp: u64,
}
static mut PER_CPU: PerCpuData = PerCpuData {
user_rsp: 0,
kernel_rsp: 0,
};
pub unsafe fn wrmsr(msr: u32, value: u64) {
let low = value as u32;
let high = (value >> 32) as u32;
unsafe {
asm!(
"wrmsr",
in("ecx") msr,
in("eax") low,
in("edx") high,
);
}
}
pub unsafe fn rdmsr(msr: u32) -> u64 {
let low: u32;
let high: u32;
unsafe {
asm!(
"rdmsr",
in("ecx") msr,
lateout("eax") low,
lateout("edx") high,
);
}
((high as u64) << 32) | (low as u64)
}
pub fn init_syscalls() {
unsafe {
flush_all();
let efer = rdmsr(IA32_EFER);
wrmsr(IA32_EFER, efer | IA32_EFER_SCE); // enable syscalls
let per_cpu_addr = &raw const PER_CPU as u64;
wrmsr(IA32_KERNEL_GS_BASE, per_cpu_addr); // per-cpu kernel data
asm!("mov gs, ax", in("ax") 0u16);
let kernel_stack_top = TSS.privilege_stack_table[0].as_u64();
PER_CPU.kernel_rsp = kernel_stack_top;
#[allow(function_casts_as_integer)]
wrmsr(IA32_LSTAR, syscall_entry as u64); // set syscall entry function
wrmsr(IA32_FMASK, 1 << 9); // Mask interupts during syscalls
let kernel_cs = (GDT.1.0.0 & !0b11) as u64;
let user_ds = (GDT.1.3.0 & !0b11) as u64;
let sysret_base = user_ds - 8;
let star = (kernel_cs << 32) | (sysret_base << 48);
wrmsr(IA32_STAR, star);
}
}
#[unsafe(naked)]
#[unsafe(no_mangle)]
unsafe extern "C" fn syscall_entry() {
core::arch::naked_asm!(
r#"
.intel_syntax noprefix
swapgs
// save user stack
mov gs:[0], rsp
// use kernel stack
mov rsp, gs:[8]
push r11
push rcx
push rax
push rdi
push rsi
push rdx
push r10
push r8
push r9
mov rdi, rax
mov rsi, [rsp + 40]
mov rdx, [rsp + 32]
mov rcx, [rsp + 24]
mov r8, [rsp + 16]
mov r9, [rsp + 8]
push qword ptr [rsp]
call syscall_dispatch
add rsp, 8 // fix alignment
pop r9
pop r8
pop r10
pop rdx
pop rsi
pop rdi
add rsp, 8
pop rcx
pop r11
mov rsp, gs:[0]
swapgs
sysretq"#,
);
}

6
kernel/src/driver/elf/loader.rs
View File

@@ -2,8 +2,9 @@ use core::ptr::null;
use x86_64::structures::paging::OffsetPageTable;
use crate::driver::{
elf::{
use crate::{
arch::syscall::{malloc, memset},
driver::elf::{
header::{
ET_DYN, ET_EXEC, ET_REL, Elf64Ehdr, Elf64Rel, Elf64Shdr, SHF_ALLOC, SHT_NOBITS, SHT_REL,
},
@@ -12,7 +13,6 @@ use crate::driver::{
section::elf_sheader,
validation::validate_elf,
},
syscall::{malloc, memset},
};
pub fn load_file(mapper: &mut OffsetPageTable, elf_bytes: &[u8]) -> (*const u8, u64) {

20
kernel/src/driver/elf/program.rs
View File

@@ -12,19 +12,15 @@ use x86_64::{
};
use crate::{
arch::arch::FRAME_ALLOCATOR,
driver::{
elf::{
header::{
DT_JMPREL, DT_NEEDED, DT_NULL, DT_PLTREL, DT_PLTRELSZ, DT_RELA, DT_RELAENT,
DT_RELASZ, DT_STRSZ, DT_STRTAB, DT_SYMENT, DT_SYMTAB, Elf64Dyn, Elf64Ehdr,
Elf64Phdr, Elf64Rela, Elf64Sym, PF_X, PT_DYNAMIC, PT_LOAD, R_X86_64_64,
R_X86_64_GLOB_DAT, R_X86_64_JUMP_SLOT, R_X86_64_NONE, R_X86_64_RELATIVE, SHN_UNDEF,
STB_WEAK,
},
reloc::elf_do_reloc,
arch::{arch::FRAME_ALLOCATOR, syscall::memset},
driver::elf::{
header::{
DT_JMPREL, DT_NEEDED, DT_NULL, DT_PLTREL, DT_PLTRELSZ, DT_RELA, DT_RELAENT, DT_RELASZ,
DT_STRSZ, DT_STRTAB, DT_SYMENT, DT_SYMTAB, Elf64Dyn, Elf64Ehdr, Elf64Phdr, Elf64Rela,
Elf64Sym, PF_X, PT_DYNAMIC, PT_LOAD, R_X86_64_64, R_X86_64_GLOB_DAT,
R_X86_64_JUMP_SLOT, R_X86_64_NONE, R_X86_64_RELATIVE, SHN_UNDEF, STB_WEAK,
},
syscall::memset,
reloc::elf_do_reloc,
},
util::{align_down, align_up},
};

1
kernel/src/driver/mod.rs
View File

@@ -3,5 +3,4 @@ pub mod graphics;
pub mod keyboard;
pub mod mouse;
pub mod serial;
pub mod syscall;
pub mod timer;