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Fix GDT issue when using EFI handover protocol

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Hsy-Intel 2025-03-12 21:55:36 +00:00 committed by Tate, Hongliang Tian
parent 148695194f
commit dd3aa8fe81
1 changed files with 10 additions and 16 deletions
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26
ostd/src/arch/x86/trap/gdt.rs
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@ -21,10 +21,10 @@ use alloc::{boxed::Box, vec::Vec};
use core::cell::SyncUnsafeCell;
use x86_64::{
instructions::tables::{lgdt, load_tss, sgdt},
instructions::tables::{lgdt, load_tss},
registers::{
model_specific::Star,
segmentation::{Segment64, GS},
segmentation::{Segment, Segment64, CS, GS},
},
structures::{
gdt::{Descriptor, SegmentSelector},
@ -50,18 +50,13 @@ pub unsafe fn init(on_bsp: bool) {
};
// FIXME: the segment limit assumed by x86_64 does not include the I/O port bitmap.
// Get current GDT.
let gdtp = sgdt();
let entry_count = (gdtp.limit + 1) as usize / size_of::<u64>();
let old_gdt = core::slice::from_raw_parts(gdtp.base.as_ptr::<u64>(), entry_count);
// Allocate new GDT with 7 more entries.
// Allocate new GDT with 8 entries.
//
// NOTICE: for fast syscall:
// STAR[47:32] = K_CS = K_SS - 8
// STAR[63:48] = U_CS32 = U_SS32 - 8 = U_CS - 16
let mut gdt = Vec::from(old_gdt);
gdt.extend([tss0, tss1, KCODE64, KDATA64, UCODE32, UDATA32, UCODE64].iter());
let mut gdt = Vec::<u64>::new();
gdt.extend([0, KCODE64, KDATA64, UCODE32, UDATA32, UCODE64, tss0, tss1].iter());
let gdt = Vec::leak(gdt);
// Load new GDT and TSS.
@ -69,13 +64,11 @@ pub unsafe fn init(on_bsp: bool) {
limit: gdt.len() as u16 * 8 - 1,
base: VirtAddr::new(gdt.as_ptr() as _),
});
load_tss(SegmentSelector::new(
entry_count as u16,
PrivilegeLevel::Ring0,
));
load_tss(SegmentSelector::new(6, PrivilegeLevel::Ring0));
CS::set_reg(SegmentSelector::new(1, PrivilegeLevel::Ring0));
let sysret = SegmentSelector::new(entry_count as u16 + 4, PrivilegeLevel::Ring3).0;
let syscall = SegmentSelector::new(entry_count as u16 + 2, PrivilegeLevel::Ring0).0;
let sysret = SegmentSelector::new(3, PrivilegeLevel::Ring3).0;
let syscall = SegmentSelector::new(1, PrivilegeLevel::Ring0).0;
Star::write_raw(sysret, syscall);
USER_SS = sysret + 8;
@ -113,6 +106,7 @@ static mut USER_CS: u16 = 0;
const KCODE64: u64 = 0x00209800_00000000; // EXECUTABLE | USER_SEGMENT | PRESENT | LONG_MODE
const UCODE64: u64 = 0x0020F800_00000000; // EXECUTABLE | USER_SEGMENT | USER_MODE | PRESENT | LONG_MODE
const KDATA64: u64 = 0x00009200_00000000; // DATA_WRITABLE | USER_SEGMENT | PRESENT
#[expect(dead_code)]
const UDATA64: u64 = 0x0000F200_00000000; // DATA_WRITABLE | USER_SEGMENT | USER_MODE | PRESENT
const UCODE32: u64 = 0x00cffa00_0000ffff; // EXECUTABLE | USER_SEGMENT | USER_MODE | PRESENT